Document B8dvx6qLXg9pEpqy2bZJrBeZo

Sr. Louis Public Library American Society of Heating and Air-Conditioning Engineers Heating ventilating air conditioning guide. VOL 34 19 American Society of Heating Refrigerating and Air Conditioning Engineers . St 628. 8 AMERICAN 21050 36601 no-___ 5.21010____ This Book Shall Not Be Taken From The Library Heating Ventilating Air Conditioning Guide 1956 Applied Science Department Heating Ventilating Air Conditioning GUIDE An Instrument ofService Preparedfor the-Profession containing A TECHNICAL DATA SECTION op reference material on the DESIGN AND SPECIFICATION OF HEATING, VENTILATING, AND AIR CONDI . HONING SYSTEMS BASED ON--THE TRANSACTIONS--THE INVESTIGATIONS of the Research Laboratory anp^ Cooperating Institutions-- and the Practice of the Mem.sejia.and Friends of the Society; A MANUFACTURERS' CATALOG- DATA SECTION containing ESSENTIAL AND RELIABLE INFORMATION CONCERNING MODERN EQUIP MENT; COMPLETE. INDEXES to Technical and Catalog Data Sections. A521000 Vol. 34 . $12.00 per copy Published Annually by the American Society of Heating and 1' kiR-Conditioning Engineers, Inc 62 Wobth St. New Yobs 13, N.Y. * . : Copyright 1956 . BY THE American Society op Heating and Air-Conditioning Engineers, Inc. AND BY IT Dedicated To the Advancement op The Propession AND Its Allied Industries TEXT AND ILLUSTRATIONS ARE FULLY PRO TECTED . BY COPYRIGHT; AND NOTHING 'THAT APPEARS MAY BE -REPRINTED -EITHER WHOLLY OR IN PART WITHOUT.'SPECIAL PERMISSION. Printed and Bound by Waverly Press, Inc. BALTIMORE MARYLAND ib-'w; wt* >nr PREFACE T CSLf'f 34th EDITION The 34th Edition of the Heating Ventilating Aib Conditioning Guide, 1956, contains 1176 pages of technical text--16 pages more than the'largest previous edi tion. In addition, new material equivalent to 14 pages has been added where con densation of previous text was possible. ^ Substantial improvements have been made in 16 chapters, some of which have been almost completely rewritten. In the outline of changes which follows,;it will be noted that special attention has been given to subjects dealing with heat transmis sion of building materials, cooling load* chimneyB, estimating fuel consumption, baseboard and finned-tube radiation, snow melting, central, systems for air condi-r tioning, air duct design, air heating and cooling coils, automatic control, pipe and tube characteristics and insulation, automobile air conditioning, heat' transfer measurements, and codes and standards. .; The following paragraphs describe the significant changes in the chapters having the most important revisions:. . , . .. . Chapter 1--Terminology. Revisions have been made, in several, definitions to obtain agreement with values adopted by the 9th and 10th General Conference on Weights and Measures. ' .' Chapter 4--Fluid Flow. Most of the illustrations have been improved. A number of clarifications have been made in the text. . . Chapter 9--Heai Transmission Coefficients of Building Materials. The chapter has been enlarged to permit addition of many materials to the list showing design values for conductivity and conductance. New information has been included for estimat ing the conductances of air spaces bounded by reflective surfaces. New tables facilitate the determination of the effect of adding insulation to wall, floor, and roof sections. A new chart makes it possible to correct quickly for the effect of framing members. The revision was prepared by the ASHAE Technical Advisory Committee on Insulation assisted by staff members of the ASHAE Research Laboratory. Chapter 1$--Cooling Load. Weather design data have been added for 21 Canadian cities, and a number of improvements have been made in the text. Chapter 17--Chimneys and Draft Calculations. The discussion of the theory of draft calculations has been rewritten. The sections oh residential chimneys and gas appliance chimney requirements have been revised and enlarged. Chapter 18--Estimating Fuel Consumption for Space Heating. The table of degree days has been extended to include 287 U. S. and 40 Canadian cities using up-to-date information furnished by the XJ. S. Weather Bureau and the Canadian Meteorological Service. , .. Chapter 22--Hot Water Heating Systems. A number of improvements have been made in the section on high temperature systems. . Chapter 28--Radiators, Convectors, Baseboard and Finned-Tube Units. Sections were added to supply information on baseboard and finned-tube units of present design. The chapter was largely rewritten. Chapter 24--Panel Heating. The section on snow melting was rewritten and en larged to include recent developments in this field and to provide new viscosity and other data for the designer. Chapter 26--Unit Air Conditioners arid Unit Air Coolers. Much of,the text was rewritten to describe present types of units as well as up-to-date practice in their application. ." Chapter 27--Pipe, Fittings, Welding. New tables were added to indicate the suita bility of various pipe, tube, and fitting materials for different applications. Char acteristics of drainage, waste and vent pipe and tube were discussed in the text and added to the table on dimensions and properties of copper tube. Chapter 28--Pipe and Industrial Insulation. Typical .conductivities of insulating materials were affirmed or revised by the ASHAE Technical Advisory'Committee on Insulation. .. , .. Chapter $0--Central Systems for Air Conditioning. The chapter was enlarged and largely rewritten with new text and diagrams describing year-round systems, unitary systems, high- and low-pressure induction convectors, and both dual duct and fan coil units. V Chapter;82--Air Duct Design. The chapter was rewritten by .a'subcommittee ,f the Technical Advisory Committee on Air Disfcribution~fc6 simplify explanation and use of formulas for duct design. New tables were added to extend the data on fric tion losses in elbows and fittings, and those due to area changes. ' Chapter $6--Heating and Cooling Coils. Information on use of coils and their selection was revised to indicate practical considerations involved;' An example-was added to show method of calculating the cooling load on coils. Chapter Sth-Automatic.Controt. This enlarged chapter'was completely rewritten employing current nomenclature in the field to describe up-to-date automatic controlsttheir application and coordination: . ' Chapter 48--Transportation Air Conditioning. The sections on automobile and railway passenger car air conditioning were revised and enlarged. Chapter 5--Instruments and Measurements. The text describing the use of thermo couples'and the measurement of thermal conductivity and conductance was enlarged and revised. ............ .... . \. Chapter'6S--Codes and Standards. Revisions were made where necessary to show latest editions and to include new standards in the field of heating and air condition ing which have become available.. ; . . .. . ... . In addition to changes mentioned for specific chapters, many improvements in other chapters were made as a result of a general review given the previous edition, by the Guide Committee. ' ;. i- The 24-page detailed subject.index has been continued to facilitate the finding of information under the various subject headings which readers might be expected to uise. V ' ' - . - - - The Catalog Data Section has-been expanded, to include reference material on products of. 335 manufacturers of-heating, ventilating, cooling and air,conditioning equipment. A comprehensive subject index makes it easy to find names of manu facturers and their products available for use by the designer.- - . - ....... The complete list of Society, committee members, other engineers; and authorities who have contributed material and assistance in the preparation of this edition can not be given here because of lack of space. These, sources of information are ex tremely important in keeping The Guide up to date with current practice. .The Guide Committee wishes to express its appreciation pf .the assistance received from all sources, and takes particular, pleasure in mentioning, the following individuals who have been especially helpful: ` H. W. Alyea -. D. W. Boyd C. B. Bradley A. D. Brandt W. P. Chapman R. E. Cherne J. H. Clarke ... ' L. F. Flagg S. F. Gilman , Nathaniel Glickman . J'. A. Goff Charles Graham . C. A.'GustafsOn W. S. Harris ' A. I. Heim . W. O. Huebner J. M. Kane G. S. LieberG' R.D. Madison . P; J. Mabschall D. C. McCoy .; - G. E, McElboy .. H.E.. McKenzie . &/W. McRae E. B. Moore L. C/Peaehn . . . . -F! J. Reed H. E. Robinson K. O. Schlentner J. P. Stewart ' - R.-F. Taylor . . H. C. S. Thom . ; R. K. Thulman J. R. Thygeson, Jr. , J. D. Vbbschoor'. 7 D. J: Vild . .... ; R. W. Watebfill * G. L. Wigg.s . C.F. Wood . This 34th edition of The Guide is presented by the Guide Committee with the anticipation and hope that it will be of great value as a means of keeping users abreast of current practice in the heitihg, ventilating, cooling, and air conditioning field. . .. . ,; P. R. Achenbach Albert Giannini R. A Gonzalez : T GUIDE^ COMMITTEE , : W. M..Wallace, II, Chairman : ..... : N. B. Hutcheon A. A. Mares- . , .. , A: T. Jones J. F. Sandport.. . \\ vM.'w! Keyes; - B. H. Jennings, Ex Officio ..Carl H. Flink, Technical Secretary .v vi CONTENTS . Page Title Page.................... ......... ..................... .................... .......... ........................... iii Preface.................... ................................................................... ............................. v Index to Technical Data..................................................................................... ix SECTION 1. FUNDAMENTALS . Chapter 1. Terminology............................................................. ........... ........ 1 2. Abbreviations, Symbols, Conversion Factors.......................... 11 3. Thermodynamics......................................................... 23 4. Fluid Flow......................... 67 - 5. Heat Transfer............................................... ......... ................ 89 SECTION n. HUMAN REACIONS Chapter 6. Physiological Principles.................... Ill 7. Air Conditioning in the Prevention and Treatment of Disease. 131 8. Air Contaminants . .................................................................... 151 SECTION m.. HEATING AND COOLING LOADS Chapter 9. Heat Transmission Coefficients of Building Materials............ 167 10. Moisture in Building Construction.......:...................... 205 11. Infiltration and Ventilation.............. 227 12. Heating Load.................................. 249 13. Cooling Load................................................................................ 275 SECTION IV. COMBUSTION AND CONSUMPTION OF FUELS Chapter 14. Fuels and Combustion................................................................ 331 15. Automatic Fuel Burning Equipment........................................ 367 16: Heating Boilers, Furnaces, Space Heaters............................... 395 17. Chimneys and Draft Calculations.............................................. 421 18. Estimating Fuel Consumption for Space Heating................... 445 SECTION V. SYSTEMS AND EQUIPMENT Chapter 19. Gravity Warm Air Systems........................................................ 463 20. Forced Warm Air Systems............................................. 475 21. Steam Heating Systems............................................ 493 22. Hot Water Heating Systems................................. '.................... 535 23. Radiators, Convectors, Baseboard and Finned-Tube Units... 561 . 24. Panel Heating.......... .................................................................. 571 25. Unit Heaters and Unit Ventilators............................................ 595 26. Unit Air Conditioners and Unit Air Coolers___:.................... 609 27. Pipe, Fittings, Welding............................................................... 623 28.' Pipe and Industrial Insulation.................................................. 653 29. District Heating......................... 671 30. Central Systems for Air Conditioning...................................... 685 - 31. Air Distribution......................................................................... 70L . 32. Air Duct Design.......................................................................... 73i . 33. Fans............................................................................................. 763 34. Air Cleaning............................................................................... ; 781 . 35. Spray Apparatus.......................................................................... 803 36. Air Heating and Cooling Coils.................................................. 829 37. Refrigeration.................... 847 38. Dehumidification by Sorbent Materials......................... 885 39. Automatic Control...................................................................... 895 40. Motors and Motor Controls........................................................ 923 41. Sound Control.............................................................................. 941 42. Electric Heating........................................................................... 963 ' vii CONTENTS (Concluded) SECTION V. SYSTEMS AND EQUIPMENT 0Continued) . Chapter 43. Corrosion and Water Formed Deposits, Causes and Prevention 981 44. Owning and Operating Costs!........................................ ..........1005 SECTION VI. SPECIAL SYSTEMS . Chapter 45. Industrial Air Conditioning...................... 1015 46. Industrial Exhaust Systems.......................................... . ------ 1041 47; Industrial Drying Systems.......:........ ....'....................1061 48. Transportation Air Conditioning...............................................1089 . 49. Water Services........................................................................... H05 50. Residential Summer .Air Conditioning.......................................1129 51. Schoolhouse Heating and Ventilating................................ . 1137 SECTION VII. INSTRUMENTS AND CODES . Chapter 52. Instruments and Measurements................................................. 1145 . 53. Codes and Standards.................................................................. CATALOG DATA SECTION;................................. - ...................................... 1177 Index to Advertisers................................................................... '.................H79 Index to Modern Equipment..........................................................................H87 Manufacturers'Catalog Data.........................................................................1217 INDEX Heating Ventilating Air Conditioning GUIDE 1956 . TECHNICAL DATA SECTION CHAPTERS 1*53! and PAGES 1-1176 Cross Reference to Subjects-in . Chapters 1-53 Alphabetically Lasted viii ' . I i 34th EDITION INDEX HEATING VENTILATING AIR CONDITIONING GUIDE 1956 Technical Data Section Chapters 1-53 and Pages 1--1176 A Abatement sir pollution, 151,154 smoke, 8, 155, 332 . Abbreviations, 11 Absolute . humidity, 5 pressure, 7 temperature, 9, 30 sero. 1, 9 Absorbent, 885, 889, 890 equipment, 891 process, 890 temperature, pressure, centration, 891 con ' Absorbers, 799 duet, sound, 950 outlet, 955 ' plate cells, 953 plenum, 955 Absorption systems, 883 Acceleration, 1 - Acclimatisation, 118 - Acoustics, 941 Activated alumina, 886 Activated carbon, 148, 1092 Activated bauxite, 887 . Adiabatic, 1 mixing two air streams, 57 saturation, 60 . Adsorbents, 799,885, equipment, 888 ' process, 887 , temperature, pressure, con centration, 885 ' Adsorption, odor, vapor, 156, 792 Aerosol, 1, 134,151 ' Air . change measurement, 1158 change method, 232, 288 . chemical vitiation of. 111, 152, 156 . circulation, 112, 463, 475, 685, . 731,1090 . circulation in dry, 1080' - classification of impurities, 151, 782 . dust, 151, 782 lint, 151, 782 cleaner, 151, 781, 1090 viscous impingement type, 783 cleaning, 781 cleaning devices, 781, 799, 800 charged media, 786 ' classification of, 781 . electrostatic, 798 installation, 790 maintenance,- 789 performance, 787 safety requirements, 791 ' selection, 789, 793 testing, 787 vapor adsorption, 792 combustion, 357, 358 Air (continued) conditioning process, 685,1005 oontamioants. 111. 151, 164, 782, 1041, 1163 oooled condensers, 872 , coolers, 615, 619 ' cooling, tropics, 136 current measurement, 1157 dehumidification, 885 distribution, 463, 475, 701, 703, 1086, 1090, 1100, 1134 air entrainment, 713 - application of methods, 727, 1090 balancing the system, 722 ceiling outlets, 719 - . definitions, 701 design methods,' 748 directional control, 724 duct approaches to outlets, 465, 723 entrainment ratios, 713 flow patterns, 723 friction chart, 734. 735 furnace systems, 463, 475 let pattern, 715 longslot,duchargefrom,711 noise level, 717 outlet location, 476, 477, 720, 726 outlet performance, 715, 721 outlets, 704, 718 perforated panels, 711 principles, 703 radial jets, 710 railway car, 1090 ' recommended velocity, 476. 747 . return and exhaust intakes, 726, 958 return grille, 465, 958 room air motion, 703, 717 selection, 720 . smudging, 718 - spread, 702, 704 standards for, 702 throw, 709, 715, 726 . . vanes, 715, 716 velocity, 597, 705, 747 ' velocity across jets, 706, 707, 709 velocity profiles, 709 . vertical drop and rise, 716' volume control, 723* 725 .. wall outlets, 476, 718. duct construction, 755, 1053 . duct design, 478, 731, 746, 757, 1053 duct friction loss, 731 dust concentrations, 155, 160, ' 161 . excess, 340,354,358,387 - filter, 783, 790 flow measurement, 78, 1152 - flow resistance of coils, 840 impurities, 113,151, 782 imfiltration, 227 - ' causes of, 227 due to wind pressure, 228 through walls, 228 leakage, 229, 231 XI Air (continued) moist, 25 motion, 122 movement, influence of, 117 movement, measurement of. 1152, 1156 outdoor. 113, 685 - physical impurities in. 113, 151, 155, 782 pollution, 151, 154 . abatement, 155, 336, 1071 primary, 338, 350, 354 quantity required, 113, 357, 358, 1091, 1093 refrigeration cycle; 860 requirements, 113, 358, 358. 1094 room motion, 703, 717 saturated, 1 secondary, 338,354,387 space conductance,-170,178 standard, 1 sterilisation of, 132,. 142 supply and return openings, 464, 465, 476, 718, 726 supply opening noise, 717, 955 temperature requirements, 122,126,251,276,1016-1026, 1101 thermodynamics of, 23 unit cleaning devices, 781, 803 washers, 1,803 ` - Air change method computing infiltration, 230, 265 . Air conditioning, 1 aircraft. 1097 automobiles in summer, 1095 central system, 685, 1131 oomfort, 2 hospitals, 131-148 humidity, table, 1016 industrial, 1016 atmospheric conditions re quired, 277,1016-1026 calculations, 1031, ' - general requirements, 1015 problem classification, 1015 typical applications, 1015 owning and operating cost, 1005, 1134 . passenger bus, 1094 processes, 54 adiabatic mixing. 57 " adiabatic saturation, 60 cooling, 55 heating, 54 railway passenger car, 10S9 residential, 1129 ship, 1100 stoker-fired units, 368 storage systems, 865 streetcar, 1093 summer design conditions, 276,277,279 temperature table, 270, 279, 1016 transportation, 1089 treatment of disease, 131 unit, 609 Heating Ventilating Air Conditioning Guide 1956 Air cooler, 609 units, 609, 619 .. defrosting-, 621 design, 619 ' ' :1 operation, 621 performance, 621 ratings, 621 types of, 619 Air filters, 783 Air pollution, 154 control, 155,792 . Air requirements. 118,338, - Air supply opening noises, << Air vdocity. 476, 697, 703. 747. 1042,1044 cooling towers, 818 design, 747 Airborne matter, 152, 782 Airborne infection, 132,164 control, 132, 164 Aircraft air conditioning, 1097 Allergic disorders, 144 ' apparatus, 145 . asthma symptoms, 145 hay fever symptoms, 144 # limitations of air conditioning ' methods, 145 . 1 Altitude, pressure and tempera* ture, 63 Anemometer, 1,1155,1156,115} deflecting vane, 1156 propeller, 1155 revolving vane, 1155 thermal, 1157 Anesthetics, 138 _. Anthracite ooal, 332-335 firing methods, 335 . - Apparatus dew point, 276,320 Aspect ratio, 1, 701 Asthma symptoms, 145 t Atmosphere, standard, 63 Atmospheric conditions for industrial proc- - esses, 1016-1026 cooling towers, 813 - make-up water, 827 - . winter freeling, 827' Atomizing humidifiers, 807 Atomizing oil burner, 375 Attenuation, 949 ' ducts, 949 duct branches. 949 elbows, 949 grilles, 949 . - Attic fans, 779 - location, 779 .. types, 779 temperature,t261 , . * Automobile - air conditioning, 1095 / Axial flow fans, 763 B name, i, aoo . Bare pipe heat loss,. 653 Barometer, 1151 1 . Basement ' ' ` ' ..." coefficients of transmission, 190 ` : heat loss, 262,263' ' ' ' " temperatures, 262 .- ' Basementiess houses, 264,492 Bernoulli equation, 68 Biochemical reactions- . ' control of rate of, 1029 ... . - Bituminous coal, 332,333, 336 firing methods,338 - Blast heater, 2 . .-. Blow, 2, 597 . Body adaptation to hot conditions, 118 : ' heat loss, 113, 120 thermal interchanges, 119, 120 Boiler,.boilers. 3951.__ 4.M AM care. -ixi\ 404 * cleaning, 408 oorobustion rates, 405 connections, 406, 520 Hartford return, 520 return, 520 sizing, 521 steam, 520 construction, 395 design, 397 efficiency, 402 erection, 407 fittings, 406 furnace design, 397 gas-fired, 384, 406 selection of, 403, 406 gas-fired units, 384 conversions, 385 grate area, 404 halting, 395 - heating surface, 2, 397 beat transfer rates, 397 horsepower, 2 -hot water supply, 403, 11X8 load, 397 . maintenance, 407 oil-fired units, 373 . operation, 407 output, 400 rating, 398,399,402,405 rating codes, 398 selection of, 403 based on heating surface and grate area, 404 cast-iron, 404 ' estimated design load, 403 estimated maximum load. gas-fired, 406 hot water supply load, 403, 1115 piping tax, 403, 654 radiation load, 403 steel, 896,398, 404 - warming up allowance, 403, 406 soot, 364 - space limitations, 406 steel, 396, 398, 404 stoker-fired units, 368 testing codea, 398, 1167 troubles, 407 ' types, 395 working pressure, 395 British thermal unit, 2 ' Bucket trap, 524, 525 Building, buildings - condensation, 207 . . heat transfer through surfaces, 186 infiltration, 227, 266, 311 intermittently heated, 270 materials, beat transfer through, 170, 175,* 186, 195, 263 multi-story, air leakage, 233 . Burner, oil, 375 ' Bus air conditioning, 1094 Bypass, 2, 680 .- . factor, 313 c Calcium chloride, 885, 890 Calculated heat loss method, 249 Calorie, 2 `" " Calorific value, 332,343,348,349, 356 . xii C^Sv.wd, 118, 885, 1092 . dioxide, 111.-158, 338, 346, 351, . 353-363 monoxide, 158,352-363 Cast-iron boilers, 395 Ceiling cooling units, 620 high, 260 outlets, 719, 1091 perforated, 720, 1091 unit heater, 596 . Central air conditioning sys tems, 685 accessibility, 700 air quantity, 691 apparatus dewpoint, 276, 320 control, 687, 915 cooling load, 275, 689 corrosion, 998 design procedure, 685, 731 dual duct, 695 , effectual temperature differ ence; 691 equipment arrangement, 686 equipment selection, 698 evaporative cooling, 697 fan and coil units, 696 fan system, 2, 685 features. 685 heating load, 249, 690 humidity control, 688 ' individual room control, 689 induction units, 692 ' high pressure type, 693 low pressure type, 692 location of apparatus, 700,1133 outdoor air, 6S5 precooling, 697 .- reheating, 686 - selection, 698 . sensible cooling, 697 - summer only, 1131 temperature differential, 691 unitary central types, 692 year-round, 685 `' zoning, 687 - Centrifugal compressors, 871 condensing unit, 871 * fan, 757 Charcoal, 800 Chart . air elimination, 505 air flow unequal openings, 238 air flow and sound level, 957 air friction, 734,735 avial jot velocities, 708 - chimney capacity, 426, 427, 429-432, 434, 433 . . / chimney draft, 423, 426, 429-. 432 chimney flow, 427, 428, -429,. 431, 438 coil temperature, 583 ' color, 22 . comfort, 126 , ' . compressor and ooQ perform- correction for pipe roughness, .736 - dehumidifier performance, 894 design temperature map,' 257 disease frequency, 133,134 draft required,_423. ' dry vs. wet weight,'1063 drying time, 1064,-1065 dust particle sue, 153 ( a economical thicknesa pipe in sulation, 669 edge loss, 265 effective diameter, 707 ' effective temperature, 124-127 elbow loss, 742, 743 entrainment ratio, 712 ` estimating surface tempera ture, 202, 579 expansion.factor, 8!, 82. evaporation chart,.1077 ' ' fan characteristics, 768-770 Index to Technical Data Section Chart {continues) A Unsound level, 768-779, 949 fan syatem characteristics, Til filter resistance, 790 firebox dimensions, 374 . flow coefficients, 79, 80 flow due to wind, 235 . flow through opening, 238, 23 flue area, 244 flue loss, 353 friction air ducts, 734,7a5 friction factor, 71 friction in pipes, 537,539,1108 1110 - fuel consumption, 391,392 fuel oil index, 346 Kid d'ue'totemperature, 536 heat flow, glass, 300 heat emission by radiation from panels, 576 - heat endurance, 119 n6'120'I21'122 canvas surface, 662 > j coefficients, insulated ducts, 760 convection from panel, 577 duct, 760 floor. 266 * iosulated pipe, 658-660, 662 insulation, 647, 658-660 humidity. 1075 infiltration, 229 . inside surface temperature, 579,580 . insulation of oold pipe, 664 Langelier formula, 989 moisture loss from body, 122 motor characteristics, 928-932 MRT elevation, 119 orifice coefficient, 77 orifice installation, 83 * panel heat output, 576-678 # permissible relative humidi ties for various transmis sion coefficients, 217 pressure loss in ducts, 732 pressure loss in elbows,' 740, 742, 743 pressure loss in faucets, 1111 pressure loss in meters, 1111 osychrometric charts, 61, 53, 1075 , persons at rest, 124 pump performance, 546 radial jet velocities, 708 radiation between black bodies; 99 radiation shape factor, 98 refrigerant pressure-enthalpy, 850,852 . refrigeration horsepower, 1013 room absorption correction, 959 ' . solubility of calcium salts,. 986,987 - solubility of gases, 985 sound attenuation. 953 .. static deflection, 9oI static regain, 752, 763 ,,. system characteristics, 771 temperature'in panel, 583 . pipe insulation, to prevent sweating, 664 velocity and velocity head, 742 vena oontraeta location, 85 viscosity, air, 69 . viscosity, water, 70 well water temperatures, 808 Chemical, chemicals ' laboratory hoods, 1046 reactions, 1026 control of rate of, 1027 vitiation of air, 111, 156 water treating, 992, 993, 996, 1002. Chimney, chimneys, 421 available draft, 422,429 construction details, 439 Chimney, chimneys (con tinued) determining sizes, 426, 434 ' . effect, 2 efficiency, 431, 433 factors affecting draft, 422 gas beating, 437 general considerations for, 436, 442 industrial, 424, 426, 427 performance, 421, 426, 427 residential, 428, 429 short, 431,433 sixes, 426, 427, 434 ' . static draft, 421 theoretical draft, 421 Cinders, 154 Circular equivalents of rectan gular ducts, 737 Circulatore, 546 Cleaning boilers, 408 Climatic conditions, 251,279 Closed expansion tank, 548, 549 sizing formula, 549 - Coal, coals ' :' anthracite, 332-335 bituminous, 332, 333,-336-340 classification of, 332 combustion, 335 ' draft required, 339,422 dustless treatment, 334 estimating consumption, 445, 457 firing methods, 335-338 lignite, 333 Codes, 1167 installation, 1167 . rating, 1167 ' . testing, 1167 Coefficients of transmission* 5, 167, 190-200, 657, 841 basement, 262 . floor, 195, 264 wall, 262 coils, 566, 841 correction for insulation, 182 185 . correction for framing, 186 doors, 200 floors and ceilings, 194 frame construction, 190, 194 glass, 200 block walls, 200 - insulating materials, 171, 172 masonry partitions, 193 masonry walls, 191 . overall, 167,566 - -. formulas for calculating, 168 practical, 180 - roofs, 196-200 skylights, 200 ' windows, 200 . . CoU, colls. 829 air flow resistance, 840 .. . applications, 834 arrangement, 830,834 * bypass factor, 322 . construction, 830. cooling, 829. __ .. ' dehuraidifying, 839, 843' direct-expansion, 832 ' dry oooting, 841 . fim coefficient, 842 . . flow arrangement, 834 . heat emission, 566,842, 1122 heat transfer surface, 840 heating, 838 . performance, 841,843 * cooling, 841 !- * - dehumidification, 843, 844 heating, 841 . pipe, 666 .. rating, 839 -. selection, 837 cooling. 839 _ ... dehumidifying, 839. . heating, 838 . . , . ` steam. 831 ' . - xin Coke classification of, 334 estimating consumption, 457 firing methods, 337 . Cold therapy, 143 ' Color, piping systems, 22 Combustion. 331 adjustments, 372, 375, 387 air required, 357 . analysis, 358 chamber, 373, 381 dew-point, 364 efficiency, 358, 380 -. flue gas, 358, 360 gas, 350 . neat balance, 361 ' heat of, 355 index,345 losses, 362 oil, 344 process, principles of, 352 rates, 386, 391, 392, 423 Comfort . - air conditioning, 2 air conditioning systems, 685. chart, 126 line, 2 sone, 2 Compartment dryer, 1082 Compressor, compressors. 869 centrifugal, 871 - - clearance, 859 - reciprocating, 869 refrigeration, performance of, 880,881 rotary, 870 volumetric efficiency, 859 Condensates, 677,983 -' ' . Condensate return pumps, 522 Condensation buildings, 217. 219 ooncealed, 219 ^ control, 221 flue gas, 365 surface, 217 ' visible, 217 - " .' Condensers. 872 air oooled, 872 data, 820 evaporative, 872 .. water cooled, 872 Condition lipe, 62,320 -. . .'. - Conductance, .3, 167, 170, 178, 179 - . . air space, 170, 178 : - - building materials, 171,178. insulators, 171, 178, 657 :. - soil, 169 : . . surface, 175,662 - - ' Conduction. 3, 89 drying methods; 1080 electric heaters, 963. - equation, 90 - ' ' steady-state solutions,101-- ' Conductivity, 3,89,.176, 178 batt type insulation, 171, 178 building boards, 171, 178 building materials,' 171,178 ' homogeneous materials, 169 innfatting materials; 171, 172, 1787179,657 . Insulation blankets, 171,178 loown fill Insulation, 172,178 masonry materials, 171,178 . plastering 171,178 - rigid Insulation,-172 ' roofing construction, 172 1 * Heating Conductor, 3 Conduits for piping, 675 Connections boiler, 406. 520 heating units, 532 Control, controls airborne infection, 132 . aircraft temperature, 1097 automatic, 895 automobile temperature, 1096 biochemical reactions, 1029* central fan systems, 686 chemical reactions, 1027 contaminant by exhaust,' 1041 corrosion, 995 crystallisation, 1029 dehydrating equipment, 804 dew-point, 1030 effect of hot environment, 1033 high temperature water sys tem, 558 ice bunker water, 865 laboratory conditions, 1030 motor, 923 panel heating, 911 passenger bus temperature, 1095 ' passenger car temperature, 1092 humidity, 1092 refrigeration, 874, 876 service water temperature, 1123 - ship air conditioning, 1102 slime. 993 sound, 941 . static electricity, 1030 . street car and coach tempera ture, 1093 ' temperature for machining, 1030 vibration, 959 Control, automatic,.695 action types, 896 air washers, 915 applications, 904 auxiliary equipment, 903 central fan systems, 912 . components of systems, 898 controlled devices, 902 controllers, 898 controlling elements, 899 cooling, 914 dehumidification, 914 design coordination, 917 electric, 896,900 electronic, 696, 900 equipment selection, 919 floating, 897 ~ . fuel burning equipment, 904 fundamentals, 895 gas burners, 907 hot water heating, 910 ' humiditv, 914 hydraulic, 896 indicating, 900 - individual room, 912 measuring elements, 898 - oil burners, 996 operating, 905 panel beating, 911 ' pneumatic, 896, 900 preheater coil, 913 - - primary, 908 `' ' proportional, 897 recording. 900 residential, 907 size of area , 918 . space conditions, 915 ' static pressure. 902, 915 steam flow, 920 steam beating, 909 - . stokers, 606 system types, 896 typical system, 915 - unit heaters, 916 unit ventilators, 917 valves, 902 . water now, 922 zone; 908 Ventilating Air Conditioning Guide 1956 Control, automatic tinued) zone systems, 909 Controllers, 895 functions, 895 types, 895 {con Convection, 3, 89, 99 equation. 91 unit conductances, 93 Convector, convectors, 3, 561, 563 correction factor. 568,,569 heat emission, 564 heating effect, 567 . induction, 692, 693 ratings, 566 Converging vanes, 716 Conversion ' burners, 385 equations, 15, 212 Comers, 609, 619, 873 Cooling, 275, 603 air conditioning units, 609, 1132 atmospheric water, 803 coil selection, 836 ' . evaporative, 697 W/275, 689 methods, 1129 . performance of coils, 841, 843 ponds? 811 residential, 1129,1122 sensible, 697 make-up water, 827 . size of equipment, 813 ` winter freezing, 828 systems, 685, 1090, 1094 towers, 810 atmospheric, 813 design, 819, 820 1 mechanical, 815 operation, 827 performance, 622 selection, 825 units, 609 '' component parts, 610 control, 615 definitions, 609 defrosting, 620 design, 610 performance, 609, 617 ratings, 616, 6ft) remote, 614 sound isolation, 613 types of, 619 water, 811, 818 water piping, 1U4- Copper elbow equivalents, 537 Copper tube dimensions, 626 Core area, 701,1156 Corrosion, 625,981 ' air ducts, 1000 atmospheric, 989, 999 boilers, 992 cathodic protection, 1001 ooa) storage equipment, 999 cold water,'982 . ' - condensates, 983, 984, 997, 998 flue gas, 364 flues, 999 heating systems, 991 hot water, 983 industrial exhaust systems, 1056 . yninini!ng condensate, 997 pipe, 993, 1000 prevention, 985, 1058 " refrigerating systems, 986 underwater, 993 ' Cost of air condltiohlng.1005, 1134 . amortization, 1005 ' condenser water, 1013 first, 1005 fixed charges, 1005 Y1V Cost of air conditioning {con tinued) heating, 1014 interest, 1008 installed, 1006 insurance, 1009 labor, 1010 .maintenance, 1009 , owning and operating, 1011 rent. 1009 service, 1009 taxes, 1008 , refrigeration equipment, 1011 water, 1011 Crack length method, 229 , used for computations, 267 Crystallization control rate of, 1029 Cylinder dryer, 1082 D Dalton's rale, 28 .. Damper, dampers, 340, 477, 685, 701,719, 725, 775,912 Darcy formula, 69 Decibel, 941 Definitions, 1 ' Defrosting, 621 Degree-day. 3, 449 for cities, 451, 460 formula lor, method, 450 industrial, 460,461 operating unit, 459 , unjt fuel consumption, 456 Degree of saturation, 8,25,31 Dehumidification,687,807,885 1 air conditioning Units, -613 air washers, 807 coil selection, 829, 839 comparison of methods, 885 control, 889 definitions and methods, 885 equipment, 807, 885, 888 performance, 888 estimating loads, 892 liquid methods, 890, 891 moisture load, 892 ships, 1102 solid methods, 887,888 vapor transfer, 893 Dehumidifying agents, 885 absorbents, 885 adsorbents, 885 Density of air, 1 Design conditions summer, 276, 279 winter, 251-258 Dew point apparatus temperature, 276, 320 ' flue gas, 364, 999 temperature, 9, 26, 1159 DichlorodiSuoromethane, 849* 851, 878, 879 Dielectric heating, 977 Diffusivity, thermal, 3 Direct expansion coils, 832 fired unit heater, 595 indirect heating unit, 3 radiator, 7 return system, 3; 542 Disc fan, 763 . . . Distribution of air (tee Air Distribution), 463, 475, 701, 1060,1098 District heating, 671 condensate return,.677 meters, 653 operation, 681 pipe insulation, 677 'piping, 667, 679 conduits for, 668 inside, 679 ' sizes, 675 tunnels, 678 . S * Index to Technical Data Section District heating (continued) steam requirement, 671 zoning, 681 - Diverging vanes, 716 Domestic oil burners, 375 * Door, doors coefficients of transmission. 200 leakage. 229. .231, natural ventilation, 240 Down-feed one-pipe riser, 3, 6, 495 Draft, drafts. 4, 421 available, 424, 429 calculations, 421 chimney, 421 control, 340 factors, 422 forced, 421 . general equation, 421 head, 4 , industrial chimneys, 423 natural, 233, 421 regulation, 339 residential chimneys, 428 requirements, 339, 422, 436 appliances, 436 theoretical, 421 Drawing symbols, 17 Drip, drips, 4, 494,629 Drum dryer, 1082 Dry air, 1 composition, 25,356 filters, 785 properties of, 30 velocity, bead, 742 Dry-bulb temperature, 9 Dry cooling coils, 829, 842 Dry return, 8, 493 . Dryer, dryers, 1080 cabinet, 1076, 1082 calculations, 1076' oompartment, 1082 cylinder. 1082 drum, 1082 rotary, 1082 spray, 1083 tunnel, 1082 Drying. 1027, 1061 application of hygroraetry, 1076 calculations, 1076 chart, 1067,1075.1077 conduction, 1081 constant rate period, 1065, 1067 oonvection, 1081 critical moisture, 1072 effect of air velocity, 1066 equations, 1070 equilibrium moisture, 1073 equipment, 1080 example, 1084 external conditions, 1063 factors influencing, 1062 falling rate period, 1089 internal conditions, 1063 mechanism of, 1062 methods, 1080 conduction, 1081 convection, 1081 radiant, 1060' periods, 1064 problem, 1084 radiant, 1080 ' surface temperature, 1066 systems, 1061 ' terminology, 1061 Duct, ducts. 465-467, 477, 723 air velocities in, 476, 747, 1044, 1052 approaches to outlets, 723 area change, 744 attenuation, 949, 953 Duct, ducts {continued) circular equivalents, 737. construction details, 755, 1053 design, 465. 478, 747, 7*8, 1048/ design methods, 748 ' equal friction, 748 static regain, 751 velocity reduction, 748 .dual duct, 695 dynamic losses, 740 elbow friction losses, 742 exhaust design, 1048 . friction losses. 733 hsat loss coefficients, 759, 760 lining, 952 measurement of velocities, 1152 noise transmitted, 944 pressure changes, 731 pressure loss, 731, 733. recirculating, 465, 467, 471* 726 rectangular equivalents of round, 439, 737 resistance, 731 roughness correction, 736 sizing, 731, 746 sound absorbers, 950 symbols for drawing, 17 system design, 465, 469, 473, 731,746 weight, 758, 759 Duct sizing, 731, 746, 1048 equal friction method, 750 general rules, 466.478,748 static regain method, 751 velocity method, 748 - Dust. 4, 151 combustible, 161 concentrations, 155 ' determination, 154 filters, 781, 790, 796 precipitators, 785, 798 removal, 761 size, 153 - Dust collectors, 781, 792 application, 781, 790, 794 centrifugal, 795 cyclone, 796 cloth, 796 - degree of dust removal, 793 . electrostatic, 798 fabric, 796, 798 factors affecting selection, 793 inertial separators, 795 settling chambers, 796 scrubbers, 795, 797 testing methods, 785 - types, 794 wet, 795 ' centrifugal, 797 packed tower, 797 ' spray towers, 797 washers, 797 - wet filters, 797 Dynamic head, 5, 740 losses, 740 E EDR (Equivalent direct radiatioo), 7, 396, 504, 508, 510, 512, 551 defined. 7, 404, 563 Effective temperature, 9,122 chart, 122, 128 - index, 122 Efficiency , boiler, 402 .conversion burner furnace, 414 seasonal, 446 Ejector nozzles, 719 Elbow attenuation, 949 oopper equivalents, 537 friction losses, 537, 742, 743 iron equivalents, 537. 557, 1112 sheet metal, equivalent, 740 Electric, electrical baseboard, 967 oonvector, 967 demand control, 978 dielectric heating, 977 heat applications, 964 beating, 963 calculating capacities, 975 central, 970, 971 . control, 978 domestic water, 974 equipment, 965 heat pump, 971 induction, 977 ' power problems, 977 resistors. 8,953 systems. 966 units, 9o4 hot water heating, 970 induction heating, 977 installation methods, 964 motor design limits, 924 panel heating, 575,968,969,970 precipitators, 785, 798 radiant convector, 967 radiant heating, 574, 967 ` resistors, 963, 968 steam radiator. 968 systems, 929, 965 voltage ratings, 924 Electricity, static,139, 1030 Emissivity, 95,170 Enclosed radiator, 561 Enthalpy. 4, 24,30, 61 . free, 4 specific, 4, 30 Entropy, 4, 30,51 ' - mixing, 51 Equivalent evaporation, 4 F>timating fuel consumption, 445 . Eupatheoscope, 1162 Evaporative oondensezs, 872 cooled, unit conditioners, 609 oooling, 697 Evaporators, 873 - Excesa air. 340,354,358,387 Exhaust opening, 726,1042, 1052 measurement of velocities, 1052, 1156 Exhaust systems, 1041 air flow equipment, 1054 axial velocity formula, 1042 capture velocities, 1042 . construction, 1053 conveying velocity, 1052 oorrosion, 1056 duct construction, 1053 duct design, 1048, .1053 . duct resistance, 1051 ' duct system design, 1048 duct velocity, 1044 ducts for, 1048 air velocities in, 1044-1048 construction, 1053 design. 1053 resistance, 1048 dust filters, 1055 - elements, 1041 equipment, 1055 exhaust requirements, 1048 general requirements, 1041 hoods. 1041 air now, 1043 air velocity, 1042 axial velocity formula for, 1042 canopy, 1044-1047 capture velocities, 1042 chemical laboratories, 1045 design principles, 1041 kitchen, 1045 special exhaust require ments, 1043 ' spray booths, 1047 - suction, 1055 XV Heating Ventilating Air Conditioning Guide 1956 Exhaust systems {continued) relocity contours, 1043 ventilation rates, 1044-1047 make-up air, 1035 maintenance, 1055 materials, 1053, 1050, 1053 performance, 1055 pressure loss, 1051 specifications, 1053 suction requirements, 1055 types of fans, 1054 velocity contours, 1043 velocity requirements; 1044 1051 ventilation rates. 1044-1049 Expansion factor, gases, 81, 83 of pipe, 639.644 tank installation, 551 tank piping, 548 tank use; 549 tanks, 548 valves, 875 Explosion hazard, 138 Extended plenum systems, 472, 473 F Pan. fans, 763 . application,. 777 arrangement of drives, 772 ; attio, 779 location, 779 . .axial flow, 763 ' centrifugal, 767 characteristic curves, 768-771 control, 774 designations, 764 ' drive position, 774 efficiency, 767 exhaust, 778 furnace system, 475 hot gas, 780 installation, 777 ' kitchen, 779 ' laws, 765 - marine, 778 ' mine, 778 . motive power,.775 noise generated, 946 . performance, 763, 767, 768,946 radial flow, 763, 767 rotation, 773 ` . selection of( 776 - .. atr conditioning systems, 775 industrial exhaust systems, 1054 special application, 779 speed,776 .' . - system characteristics, 771. types, 763 .- unitary systems, 778 . . velocity, operating. 776 volume control, 774 - Panning formula, 69,556 Fever therapy, 142 _ equipment for production of, 143 Film conductance, 93, 167, 168, 177 Filter, filters. 781 . air conditioning units, 613 atmosphere, 781 " 'charged media, 776 , dry air, 785, 796, 1094 '. dust, 785 installation, 790 ionising, 785 ' ' maintenance, 789 . moving curtain; 784 performance, 787 ' selection, 789, 793 testing, 787 _ _ vapor adsorption, 799 viscous impingement type, 783 Pitting allowance pipe, 609,537,1113 sheet metal, 482, 483, 740 Flash leg. 530 Flexible mountings, 959 ' Float trap, 524 Floor cooling unit, 609 heat transfer coefficients, 194, 195 ` panel design, 580 . unit heater, 595 Floor slab heat loss, .263 Flow coefficient, orifices, 77 compressible fluids, 73 ' critical, 76 measurement head meters, 78, 83 * liquids, 78 orifices, 78 Pitot tube, 84,1152 variable area meters, 85 Flow meters, 78,683,1111 Flue gas analysis, 360 - Flue gas dew-point, 364 Flue gas loss, 361 Fluids, flow, 67 ' theory, 67 Fluid metera, 78, till Fog, 4, 162 Force,4 Forced air heating system, 475 circulation pipe sixes, 542 convection, 91-93 Free convection. 92, 93 enthalpy, 4 Fleeting in gripes, 666 Friction loss . air ducts, 489,731 circular pipes, 69 effect of area change, 744 elbows. 468, 482, 609, 637. 742, 1112 gas piping, 389 high temperature, 556 - non-circular pipes, 72 refrigerant piping, 878. 879 water heating, 537,539- ' water piping, 537-639, 655, 1108-1110 Fuel, fuels, 331 ' analysis, 331, 341, 348 burning equipment, 387 - classification, 383.334,340,349 consumption, 445 -. calculated heat-loss method,' 447 degree-day method, 449 load factor, 461 .. ' maximum demands, 461 seasonal efficiency, 440 unit, 466-459 .. firing methods, 336,336,337 s; gaa.347 Squid, 340 solid, 331 unit consumption, 456,457 utilisation, 410. ' . : Fuel oil. 340 . analysis, 341 '. . carbon residue. 342 * classification of, 340, 343 combustion of, 844 flashpoint, 342 '' grade of, 843 ` . '.v . maximum carbon dioxide . values, 359 ' ;' theoretical air requirements, . 357 -. viscosity, 342 '- weight per gallon,' 344 ,- Fumes, 4, 151 - ' Furnace, furnaces. 4,409 capacity, 413 ' \ , .. casings, 4l5 -' ' Tin Furnace, furnaces (continued) cast iron, 411 ' design, 397, 414 . efficiency, 414 fan, 410, 411 filters. 410 . a ^ ' forced warm air, 410 gas-fired units, 385 . grate area, 413 Svity warm' air, 410, 412 ting surface, 412 humidification equipment, 415 materials, 411, 416 ( ' ' mechanic*1 warm air, 410 . controls, 490 ' cooling methods, 492,.1132 dampers, 477 ducts, 477 fans, 410 filters, 410 method of designing, 414 motors, 410 -' ratings, 412 oil-fired units, 411 ' rating, 406, 412, 413 steel, 411 ' - stoker-fired uoits,:368 types, 409 volume. 4, 340, 374, 377 warm air, 409 ' Gage* gages draft, 1149 pressure, 7f 1149 Garage ventilation, 246 1 Gas, gases, 152, 168,347 - appuanoe rating, 389 -- atmospheric, 152, .164 burner controls, 876 . burners, 385 calorific value, 348,349 chimneys for heating, 436 ' classification of, 349 [' combustion of, 350 . " `' ' equipment, commercial, 890 equipment, industrial, 890 * estimating consumption, '455 expansion factor, 81, 82 flammable, 157 flue, 358 ' . heaters, 419 pipe size, 389 . '' solubility, 985 ^ . space heaters, 386, 419 ' specific heat, 5 - . . wall heaters, 387 .. ' \ ' Gaseous fuels. 347 ' . calorific value, 848; 349 ' classification of, 348, 349 combustion of, 350,387.' * fnn*rirrinm carbon' dioxide values, 359 - j products of combustion,-854, 356 . . properties of, 348 " specific gravity, 348 ' theoretical air requirements; 356,858 . . typical analyses, 848 ; Gas-fired appliances, 384 v boilers, 384 ' *' combustion process, 387' controls, 406 ` ' -` conversion burners, 385 - furnaces, 385 - - measurement of efficiency of combustion, 387 '' pipe size. 389 ' '* - ratings for, 388 ' rising heating plants, 389 space heaters, 386 ' - Glass .. coefficient of transmission, 200 deign tables, 209,306 - -. beat absorbent, 302 - - Index to Technical Data Section Glass {continued) shading of, 308 ` solar heat transmitted, 297,304 window transmittance, 800 Glass block walls . coefficient of transmission, 200 solar heat gain, 305-307- Globe thermometer, 1162 . Graphical symbols for drawings, air conditioning, 17, 21 ' duct work, 19 heating, 17, 18,19 ' .. ventilating, 19,20. Grate area, 5,404, 412' Greek alphabet, 14 Grille, grilles, {tee register*), 465, 487. 476, 701, 716, 956 air supply noises, 955 attentuation, 949 exhaust, 465, 726 locations, 465, 720, 726 door, 727 ' ' floor, 727 wall, 727 mechanical furnace systems, 471 _ noises, 726,956 - railway car, 1091 ' ' - recirculating, 1091 selection, 956 velocity, 476, 726, 768 Ground temperatures, 262. Guarded hot plate, 1161 Gun type oil burners, 376'- - H. Hangers pipe, 648 Hartford return connection, 495,620 'Hay fever symptoms, 144 Health. 131,1031 ... Heat. 5 . ... area transmitting surface.1131 auxiliary sources, 269,314 balanoe, 381 . . . . combustion, 332/349,-8S&.656 emission of '.;' ' \ ' applicancea, 316 .. ' V occupants, 120-122, 314.. ' pipe coils, 672 ' ' . ' exchange measurements, 114 flow resistance, 99,167 flow through glass, 200, 297: flowthroughroofs, 189,196-199, 292,296 .. flow through walls,. 186/ 190^ 193,294 ... gain, 275 ' Smerated by motors, 816 : amid, 6 '' ' - infiltration`equivalent,'811 ' instantaneous lead; 283, 310 introduced by outride air, 811 lag, 690 .' latent, 5, 268, 276, 813,' 314, 327 liquid, 5 .. ' loss, pipe, 653 - . mechanical equivalent of, 6,18 ' TTMtKftd<i of, transfer, 89'' ! * radiant, 92, 95, 96 -.' ' " - ratio, sensible, 821 ' .'. 'removal, natural ventilation, 235 ' sensible. 5, 267,816 ' - specific, 5 . ` . ; transfer, 89. 190-200, 564-669; 759, 1121 . " 1 boiler rates, 397 ' '' , overall coefficients, 167, 168, 178-200, 841, 1121,1122 Heat {continued) surface coils, 838 symbols, 17,94, 167 . through budding materials. 167 water coils, 1121,1122 Heat gain, 375 . appliances, 316 ceilings, 311 components of, 275 ducts, 690. 759 electrical nesting equipment, 316 . . floors, 311 . -. ' gas burning equipment, 818 glass, 301-302 glass blocks, 305 infiltration, 311 instantaneous. 310' . latent, 284, 312, 314 lights, 815 moisture, 319 - . occupants, 314 outride air, 813 partitions. 307 people, 12u, 314 ; roof, 289,296 - sensible, 283. 312 - shaded windows, 308 . ' solar, 301 ,. -steam heated equipment, 317 various sources, 270, 819 . ventilation, 311 . ' wall, 289,294 '- Heat loss air change, 268 * bare pipe, 566, 653 basement, 263 duct, 759 ' . floor elab, 264 . ' '' infiltration, 266' ir>nUt^H pipe, 656 ' latent, 268 residence problems, 270 sensible, 267 .. through ceilings and roofs, 286 ' transmission. 167.285 Heat pump, 848, &6, 887, 971^ 1127 Heat removal, 237 . . Heater, heaters . direct-fired unit, 695 - electric, 597,963 gas, 419 . design, 420 ' ' efficiency, 419 . materials, 419 . - ' rating, 418 ' >' - testing, 418 -' '. oil, 417 design, 419 , materials, 418 ' ' . rating, 418 .; testing, 418' solar water, 1125 -. solid fuel, 416 ' design, 417 - - material, 416 ' -.- ' rating, 416 ' : ':`- testing, 416 - ' ' 1 epaoe, 416 : . ' - ' ' installation, 420 - - ' unit. 595, 964 vertical blow unit, 596 Heating ' air conditioning units; 609 .f ' boilers, 395 v. surface, 9,897 ' : ' . coil selection, 837 - .district, 671 . -'-'effect, radiator, 667 . ' electric, 963 1 hot water, 974 load, 249,319, 402,690 ' ' performance of omls; 841,1121. reversed cycle refrigeration, 867 : . Heating (continued) .. steam systems, 493 surface, 9 square foot of. 8 symbols for drawing, 17 . the radiator, 569 . vacuum systems, 10, 493,500 vapor, 10, 498 . warm air system, 10,463,475 water, 535,1118 Heavy duty fan furnace, 411 High duty humidifiers, 809. High temperature hazards, 117, 137 High temperature systems, 553 boilers for, 559 circuits, 556 . - control, 558 design, 655 - economics, 656 . fittings, 658 fitting pressure loss, 657 fundamental principles, 553 Sacral considerations, 553 sulation, 558 . pipe, 558 pumps, 556 - " storage effect, 560 Hood, hoods, 1041 Horsepower, boiler, 2 Hospital, hospitals ` ' air conditioning in, 181,147' operating rooms, 138 .. air conditions, 139 ' ' ' reducing explosion haxard, 138 1 . sterilization of air, 132 -' - ventilation requirements, 140 Hot water .- boiler supply load, 403, 1115 coil surface, 1121 demand per . . . fixture, 1106, 1107, 1118 ; . person, 1115,1116. ' electric nesting, 974 - . heat pump, 1127 .. heating surface, 1121 .,. Indirect heater, 1119' . " methods of hating, ms _.. panel heating, 571 - safety devices, 1124 '' service, 1105 servioe piping, 1122 . aolar heaters, 1125 .. storage tank, 1115 supply .' `1 . boilers, 896, 974, 1118 piping, 1122 . . . temperature control, 1123 ' ' Hot water heating systems, 5,535 circulation head, 535. S36-,r548 classification, 539. 642 -1 direct return system, 542 -- elbow equivalents, 537, 557 - expansion tank, 548 . - forced circulation..536,639, 544 friction heads, 53o' ' - - gravity, 585.539 -: ' available head, 535 - . , - circulation, 536 . pressure heads, 535 high temperature; 553 - - . boilers,559 - circuits, 556 oontrol, 558 .- . design, 555 .- economics, 555 - fundamental principles, 553 insulation, 55o. - pipe fittings, 558 - pumps, 556 - storage, 660 ' -' installation details,' 551 mechanical circulators,: 545, 546 > xvii Heating Ventilating Air Conditioning Guide 1956 Hot water beating systems (continued) forced circulation, 540, 543, 645 ` . gravity circulation, 539, 542, 545 _ . crifioe friction heads, 541 pipe sixes, 537-539, 555 foroed circulation, 535-540 ' gravity circulation, 535-540 piping design, 542, 556 ; .pressure head, 535 relief valve, 552 reversed return system, 542 safety devices, 552 two-pipe __ forced, 640, 543, 547 gravity, 539,546 soiling, 552 Human body acclimatization, lie adaptation. 113,118- oold condition, 125 hot conditions, 115,814 ' heat emission, 120,314 high temperature hazards, U< metabolic rates, 113 odors, 113 . temperature, 114 thermal interchanges, 113 SOne of evaporative regulation, 115 ,, Humid heat, 5 Humidification, 613, 805, 807 control, 490, 914 direct, 807 M forced furnace systems, 490 - - .--j**2 Humidifier, humidifiers air washer, 807 atomising, 809 high duty, 809 aeif-oontained, 810 - spray, 809 unit, 809 . HumidiBtat, 5 ` Humidity. 5 . absolute, 5 control, 688, 914, 1092 Influence of, 122,141 measurement of, 1158 . nurseries for premature in fanta, 140 ratio. 5, 25 relative, 5, 25, 699 Hygrometers, 1159, 1160 Hygroscopic materials, 1026 . Hygrostat, 5,901 . . I Ice systems, 865 Impulse trap, 524-527 ' Tnrh of water, 5 ' . Induction units, 693 - high pressure types, 693 low pressure types, 692 Industrial . air conditioning, 1015 - calculations, 1031 ' . conditioning and . drying, 1027 - contaminant control.-lv31 eontrol of chemical reac tions, 1027 dilution systems, 1032. . general requirements, 1015, 1031 . humidities, 1016-1026, 1030 laboratories, 1030 local relief, 1033 nwhining tolerance^-MBO - moisture content and regain, 1026. ' , = polished surfaces, 1030.. process, 1015 Industrial (continued) safety, 1031 . spot cooling, lf6 . . . static electricity. 1030 temperatures, 1016-1026 exhaust systems, 1041 Infiltration causes, 227 . due to wind pressure, 228 heat losses, 266 latent. 268 ... sensible, 267 measurement. 1158 temperature differences, 333 through outside doors, 229,231 through walls, 228 through windows, 229 . . Inflammability, 162 Inside temperature, 258,259,276 Instruments, 1145 Meter, meters (continued) force, 78 ihead, 78.83,684 installation, 683 orifice, 79, 1154 selection, 684 velocity, 684 venturi, 1155 Metering, liquids, 78, 683 Micromanometers, 1151 Micron, 6 Mist, 152 Moist air. 25 . properties of, 25 saturation. 26 specific volume, 32 Moisture, 205, 1026, 1061 content. 1026, 1028, 1062 in building construction, 205 Insulation, 6, 653 . economical pipe ihickna, 667 Savity furnace duct, 463, 464 w temperature pipe, 663 pipe, 653 '. pipes to prevent freezing, 665 sound, 950 . thermal conductivity, 657 underground pipe, 667 Intermittently heated build ings, 270- Isobartc, 6 . Isothermal; 6 Jets, 70S. expansion, 7uo radial, 710 velocity, 705 Joints, duct, 755 K Kata thermometer, 1157 Laboratories, 1030 Latent heat, 6,268, 275 1am, 268 . Laws of thermodynamics, Leaders, 463 . Leakage of air, 227 door, 229, 231. 232 . ' window, 229,230,311 Light heat gain, 315 Lignite, 333 Liquid absorbents, 890 heat of, 5 Lithium bromide, 885 Lithium chloride, 885 . . . loss per person, 122, 314, 892 movement in materials, 208 permeability, 212 regain, 1026 transmission, 208 MMoonbo6fluorotrichloromexth. ane, 849,853 Motor, motors, 270,210, 923. alternating current, 927 capacitor type, 930 classification, 926 control, 934, 937 . . . control equipment for, 934 current limitation,.935 - design limits, 924 drives, 924 - ' electric, 923 enclosures, 939 ' fet*5nmated by, 270 hermetically enclosed, 932 increment limitation, 935 multi-speed, 929,936 polyphase, 927 rating, 936 . repulsion induction, 931. selection, 923 tingle phase, 930 # speed characteristics, 926 speed classification, 939 speed ranges, 924 split phase, 931 squirrel cage, 927, 934 starting methods, 934. synchronous, 928,935 ' wound rotor, 928, 935 . a- . N Natural draft, 421 towers, 813 . . Natural ventilation, 235 general rules. 241 heat removal, 237 Load __ cooling, 275. 689. design, 6,269 _ - factor, 461 heating, 213, 690 maximum, 6, 403, 461 refrigeration, 275' - M Machine vibration, 959. Manometer, 6,1150' . ... Mrin> (see tkip heating, venti lating, air conditioning)' ' Mass, 6 - .*. ' Mbh, 538 . Mean radiant temperature, 119, 579,581,912 : : Meter, meters, 78, 683 . area, $81,85. 6g condensate, 683 flow, 78,85,683 , . Noise, noises. 941.1133 absorptive material, 950 air conditioning system, 942, 1133 ` air supply opening, 955 apparatus for measuring, .942 attenuation, 949 average in rooms, 946 control, 941 .' controlling vibration, 959 . cross transmission between rooms, 958 room lever, 946 duct sound absorbers, 950,952 duet system attenuation, 949 fans, 946 genual problem, 942 grille, 956 intakes, 726 kinds of, 944 levels, 717, 943, 945 loudness, 941 Index to Technical Data Section Noise, noises (continued) measurement, 942 openings, 955 plate cells, 953 _ plenum absorption, 955 through building construe; tion, 958 transmitted through ducts, 944 typical sound level, 945 unit of measurement, 941 Nozzle flow, 75, 78 Nurseries for premature In fants, 140 a air conditioning equipment, 141 o Odors. Ill, 113,147,156, 792 human body, 111 OH Fuel, 340 analysis, 341 calorific value, 344 classification of, 340, 343 oombustion index, 345 combustion of, 344, 378 estimating consumption, 392, 455 heating of, 383 piping, 383 storage, 383 Oil burners, 382 atomizing, 382 boiler settings, 381 classification, 375, 382 ' oombustion adjustments, 379 combustion efficiency, 360 combustion process, 378 commercial, 382 controls, 906 domestic, 375 ' furnace design, 381 gun type. 375 industrial, 382 . _ measurement of efficiency of combustion, 380 mechanical draft, 375 . operating requirements, 378 rotary type, 376, 382 vaporizing type, 377 One-pipe system, 494, 540, 545 . gravity air-vent, 496 hot water, 545 steam, 6 supply riser, 6 unit heater connection, 494 vapor, 496 ' . Opening, openings air supply noises, 955 stacks, 241 types of, 240 doors, 240 roof ventilators, 240 - skylights, 240 vertical, 234 windows, 240 . Operating rooms. 138 conditions, 139 _ ' reducing explosion hazard, 138 sterilization of air in, 140 Orifice discharge, 75, 504, 541 flow, 75 formulas, 77, 1154 r\hea. t-inTg._s_y_s1t1eamo s, 502 - Outlet, outlets air supply noises, 955 ceiling, 719 duct approaches, 723 location, 465, 475, 476, 720 performance, 715, 721 selection, 720 side outlets, 476 Outlet, outlets (continued) . sound absorbers, 955 types. 476, 704 wall outlets, 718 Outside temperature, 251, 279 Overhead distribution, 498, 1123 Overhead system, 498, 1123 Oxygen chambers, 146 tents, 146 therapy, 145 Ozone, 113 P Panel beating, 571 application methods, 571 calculation principles, 575, 580 convection transfer, 676 design of panel, 5S0, 583 electric. 572, 968-970 embedded piping, 572 hot water, 571 installation, 584 output from surface, 575, 678 piping, 583 radiation transfer, 575 starting system, 573 steam, 671 ' - warm air, 490, 574 Panel radiator, 6 Particle size chart, 153 Perfect gas relationships, 27 Perforated ceilings, 720 Perforated outlets, 711, 720 Permeability, 200,213 Permeance, 209, 212, 213 pH value, 409, 987, 994 #. Physical impurities in air, 113 Physiological principles. 111 acclimatization, 116 comfort chart, 126 effective temperature, 122 high temperature hazards, 117 thermal interchanges, 113 upper limits of heat, 119 Pine coils, 566, 591 heat emission, 565, 654 wall, 566 Pipe, piping, 623 application. 650 capacity, 506.508-518,538,1105 coatings, 1001 coil connections, 532 ooil output, 565 cold water, 1105 a commercial dimensions, 627 oonduits for, 674 a _ connection to heating units, 520.532 corrosion, 981, 993 covering, 655 . design, not water system, 542 dimensions; 624 v economical thickness insula tion, 667 . expansion, 644 . fittings, 629. 633 fitting equivalent, 509, 537, 558, 1106, 1112 flexibility, 644 _ forced circulation, 542 friction loss, 536, 655, 1109 hangers, 648 heat losses, 653, 656 hot water heating systems, 542 hot water supply, 1122 inside dimensions, 624 insulation, 656, 677 # insulation prevent freezing, 665 . low temperature insulation, 663 materials, 623, 1001 . # one-pipe forced circulation, 545 . . one-pipe gravity circulation, 546 XIX Pipe, piping (continued) overhead distribution, 499, 1123 properties, 624, 646 sizes, 507, 542 cooling systems, 1114 gas. 389 high pressure steam, 514 516, 554 high temperature water, 553 hot water foroed circulation, 545, 547 hot water gravity circula tion, 545 indirect heating units, 518 low pressure, 509 one pipe riser, 510, 516 one pipe vapor, 515 orifice systems, 502 pressure drop, 507 ' sub-atmospheric systems, 517 - tables for steam, 510-515 threading data, 628, 629 _ two-pipe forced circulation, 547 two-pipe gravity circula tion, 546 two-pipe low pressure, 516 two-pipe riser, 510 two-pipe vapor systems, 516 vacuum systems, 517 water supply systems, 1105, 1122 . steam distribution, 510, 675 steam heating systems, 510 515 supports, 648 surface, 626 symbols for drawings, 17 tax, 403, 653 threading practice, 629 tunnels, 677 . underground insulation, 667 unit heater connections, 494, 534,600 water supply, 1105 welding, 642 Pitot tubes, 84,1152 Plate cell, 953 Pollution of air, 151 Polyphase motors, 927 Ponds, 811 Potentiometer, 7, 1147 Power, 7 Precipitators, 785, 798 Preceding, 697 _ Premature infant nurseries, 140 Pressure absolute, 1 atmospheric, 1 changes in ducts, 731, 744 gages, 1149 loss, elbows, 468, 482, 509, 537, 557, 1112 loss, water supply piping, 1108-1110 measurement, 1139 barometer, 1151 . regulators, 518, 680, 902 static, 7 j' taps, 84 total, 7 vapor, 7 velocity. 7 . Prime surface (see Heating Sur face), 9 Propeller fan, 763, 771 Pump, pumps condensate return, 522 ' high temperature, 556 mechanical circulators, 546, 550 Heating Ventilating Air Conditioning Guide 1956 Pump, pumps (continued) vacuum beating, 522 controls, 523 piston displacement, 523 Pyrometer, 7,1149 optical, 1149 radiation, 1149 R Radial flow fan, 763 Radiant drying, 1QS0 Radiant heating, (see Panel heating) Radiation, 7, 89 baseboard, 564, 566 equation, 92 finned tube, 565 load, 403 ratings, 566 nhsDfl factor. 95, 575 Radiator, radiators, 7, 561 baseboard, 564, 567 codes, 663, 566,1172 concealed, 563 . connections, 531 correction factor, 568 direct, 7 effect of paint, 569 enclosed, 569 heating, 569 heating effect, 567 output of, 561,568 panel, 6 ratings, 566 recessed, 8, 565 tube, 562 types of, 562 Railway air conditioning, 1089 A ' air cleaning, 1090 - air distribution, 1090 heating, 1089 . humidity control, 1092 . . refrigeration, 1090 ___ summer systems, 1090 temperature control, 1092 ventilation, 1091 winter systems, 1089 Reciprocating compressors, 869. Recording equipment, 000 Rectangular duct equivalents, 737 ,, . Reducing valves, 518, 680 Reflective insulation, 170, 178 Refrigerant, refrigerants, 8, 847, 849 dichlorodifluoromethane, 850, 851 ' feeds,834 * \ monochlorodifluorometbane, 852, 853 monofluorotrichloromethane, 854 pipe sire, 877 -s water, 862 > Refrigeration, 847, 1090, 1094 a__b_s_o_r_pteioonn system, 863 . air cycle, 861 .- basic concepts, 847 complex cycles, 860 ' compressors, 869-872 ' condensers (se Condensers)', 872 control, 874, 876 coolers, 873 definitions, 847 discharge pressure, 858 - 1 equipment selection, 881 evaporators, 873 ' expansion valves, 875 float valves, 875 ' Refrigeration (continued) - . beat pump, 666, 867 ice systems, 865 load, 275 mechanical, 847,855,1094,1102 piping, 877 reverse cycle, 848, 867 ship,1102 simple qycle, 845 steam ic, 861 subcooling, 858. suction, 857 superheating, 654 symbols for drawing, 17 theory, 847 ton of, 8, 847 types of compressors (see CompressorsJ, 871 vapor compression cycle, 854 volumetric efficiency, 859 water jacket, 858 Regain. 1026, 1028 control of, 1015 hygroscopic materials, 885 static, 751 Register, registers, (see Grilles), 463, 465, 476, 701. 719,726 .. air supply noises, 955 mechanical furnace systems, 476 noises, 717,955 selection, 463, 476,720 Reheat, 686, 698 Relative humidity, 5, 25, 52, 217 measurement of, 1158 - KK2 1194 Residence control systems, 907 air conditioning, 907, 1129 domestic hot water supply, 1123 heating, 907 - coaling methods, 492, 1129 gravity furnace systems, 263 heat low problems, 270 hot water heating system, 535 mechanical furnace system, 475 steam heating system, 493 Residential Air Condition ing. 1129 air distribution, 1133 - application, 1131 . central systems, 1131 - equipment capacity, 1129' - equipment location, 1133 equipment types, 1130- noise, 1133 - operating oosts, 1134 Resistance thermometers, 1148 Resistors, 963 Return grille, 465, 471, 726, 958 .mains, 8, 493, 512-515 openings, 465, 726 . Reverse cycle refrigeration, 848, Reversed return system, 8,542 Ringelmann chart, 1162 ' . Roof, roofs heat flow through, 179, 196 199,289,292,296 . time lag of solar radiation, 310 ventilators, 240 - Room ' '. * air conditioners, 609, 1131 air motion, 702, 717 control, 908 - coolers, 609, 614, 615, 619 <TOS8 transmission noise, 95S latent heat, 314,315 noise level, 945 operating, 138 ' sensible heat, 313 . XX Rotary dryer, 1082 ___ Rotary oil burner, 376, 382' s Sanitary ventilation. 132 Saturated air, 1, 25 Saturation, 8 - degree of, 8,25 measure. 7 Scale, 985 cause and prevention, 981, 985 closed systems, 988 ,' heating systems, 992 high temperature, 992 open systems, 990 temperature, 9 Schoolhouse Heating and Ventilating design factors, 1138 - classrooms, 1138 direct radiation, 1142 economic, 1040 forced air, 1142 gravity exhaust, 1141 mechanical exhaust, 1141 panel heating, 1143 unit ventilator, 1143 general considerations, 1137 - maintenance, 1144 - operation. 1144 ' systems, 1141 '' Secondary air, 338, 354, .388 Sectional boiler, 395 Sensible cooling, 697 Sensible heat, 267, 275, 314 gain, 275, 314 . loin, 267 -* Sheet metal gages, 757, 758 . Ship heating, ventilation, air conditioning, 1100 air conditioning,-1100,.1102 ' design conditions, 1101 ' ' factors affecting design, 1100 ' general consideration, 1100 - heating, 1100 ' insulation of ducts, 1100 ' refrigeration, 1091 . requirements for space, 1101 cargo, 1102 ' J living, 1101 - machinery, 1101 storeroom, 1102 . systems, typical, 1102 ventilating, 1100 SUica gel. 887 - Silicon dioxide, 887 Single phase motors, 930 . - - Slime, 983,992 . cause and prevention, 992 formers, 981 ' Slotted outlets, 711 - Sludge, 981 . cause and prevention, 992 Smoke, 8,154 . . abatement, 155,3J8 density measurements, 1162 Smokeless arch. 8 -.. -,r' Smokeless combustion, 336 Snow melting, 584- ` . - antifreese characteristics, 588. circulating medium, 591 : effect of viscosity, 589 . , design, 584 ... ' draining, 591 drifting snow, 592. - heat from slab, 587 .. heating requirements, 584 installation, 590 ,. internal corrosion, 591 -. pumping head, 588 - safety, 590 -' slab construction, 591 ' snowfall, 685 testing installation, 591 ' thermal stresses, 591 . -. Soil specific heat, 174 Index to Technical Data. Section Solar constant. 8, 284 Solar heat, 284 . absorbed by glass, 300 altitude, 285 oba_ms calculation tables, 385-Zoo, 292-298 ' through sltaded windows, 308 time ifi 310 . transmission of, 284 ^ through gia3S, 237,ou| through glass block, 3U3 through roofs, 289 through walls, 289 Solar heat gain, 284 . basic principles, 284 design for figured rolled glass, . 303 ` design for flat glass, 299, 302 design for glass blook, 305 deviation from design, 306 pVin^inff glass, 308 . Solar radiation. 284 absorption of, 284 . magnitude, 284 Solar water heater, 1125 Sol-Air temperature, 289 Soot, 156, 336, 364 . Sorbents, 885 absorbents, 885,8S9 adsorbents, 885 Sound-(0 Noise), 941 absorbers, 950, 953 4 apparatus for measuring, 942 attenuation,.949 control, 946, 959 cross transmission between rooms, 958 ' . general problem, 942 . duct absorbers, 950,952,863 . intensity, 941 . isolation, 613 levels, 942, 946 measurement, 942 .. outlet absorbers, 955 . pressure, 941 ' -- unit. 941 Space heaters, 416 design, 417 rating, 416 Split systems, 8 ' ' Splitter dampers, 725 Spray '. - apparatus, 803 ; . booths, 1047 . cooling, 809 . cooling ponds, 811 . - oooling towers, 813 ` dehumidifier, 689, 807* - distribution, 809 dryer, 1083 equipment, 803 generation, 809 - humidifiers, 807-810 unit air conditioner, 613 Spread, air distribution, 702; 716 Square foot of heating surface, 8 Squirrel-cage induction motor, 924, 926, 927, 934 Stack, stacks, 227, 241, 421, 463 . height, 8,243 waQ. 463, 466 ' ' smoke, 421 Standard, standards, 1167 air distribution, 702 ' .atmosphere,' 63. ' Standard air, 1 . - ' Static '' electricity elimination, 1030 ' pressure, 7, 731, 764, * regain, 751 ' ' Steady flow, energy equation, . 24,67 '' Tables (coniinued) coils,'829, 838 . . ' distribution piping, 503, 674 estimating consumption, 456, 657,672 ' flow, 505, 506 _ flow measurement, 78, 683 heated equipment, 317,672 beating systems, 483 condensate return. 493; 677 connections to units, 532 _ control valves, 533 corrosion, 991 . drips, 529 flash leg, 530 gravity one-pipe air-vent, 495 gravity return, 494 Hartford return, 495 ' high pressure steam, 511 low pressure steam, 511 mechanical return, 494 one-pipe, 494 orifioe; 502 - piping for, 503 ^ sub-atmospheric, 501 two pipe, 496 . vacuum, 500 - vapor, 498 jet type system, 861 . meters, 78, 683 ' panel heating, 571 ' pipe capacities, 506-615 properties, 32, 49 - reducing valves, 518' requirements, 458, 672 - - . runout, 495 . . superheated, 8 -' tables, 32, 49 traps, 524 ' valves, 533 velocity, 508, 675 Steel boilers, 396_ Sterilization of air, 132 . - . air duct size, 466 air leakage, 228, 230, 232 air requirements, 113 air, volume of, 32 _ allowable concentration . gases, vapors, 158 dust, fumes, 160,161 altitude, pressure and tem perature, 63 aluminum ducts, 758 ,, analytical solutions for heat conduction, 107 anthracite size, 333 anti-freeze, solutions, 588 . atmospheric gas, 985 . atmospheric impurities, 153, 985 , . attenuation ' , between grille and room, 951 - data, lining board, 953 in straight ducts, 949 of branches, 950 of elbows, 950 ' of plate absorber, 954 attic ventilation, 223 asimuth angle, 288 . black body radiation, 96 boiler ratings, 399, 400, 401 bonnet pressure, 489 . building load factors, 462 ` calorific value, 332,344,348,356 Capacity constants, unit heat ers, 698 ' capture velocities, 1042 carbon dioxide maximum, 362 cast-iron boiler rating^402 ceiling temperature, 260 chimney draft, 435 ' .chimney efficiency, 433 circular equivalents of- rec tangular -ducts, 737, 738, 739 . '- classification of coals, 333 . Stoker, stokers, 387 hot water heating systems, classification of; 367 ' 542 combustion adjustments, 372 . motors, 926 - oombustion process, 369 - . water, 682 - ' controls, 375 . climatic conditions, 251, 279 furoaoe design, 373 . coal analyses, 332 - mechanical, 367 coal classification, 333 overfeed flat grate, 371 . . codes, 1167 overfeed inclined grate, 869 coil Mat emission; 566 sizing and ratings, 374 . combustible elements ' and underfeed, 370 - * compounds, 356 * ' Sub-atmospheric systems,.501 oombustion rates, 405 Summer air conditioning; ays- - oomfort ranges, 123 . torn, 275.1129 . condenser design data,- 826 Summer climatic conditions, 279 ' conductance, 93, 170-173, 175, Summer comfort, 126,127 178, 179 Superheated Steam, 8 . . V Supply mains, 9 ' . Supply openings, 476, 701, 718, 720, 955, 1091 .. . measurement of velocities, 1152,1156 Supports, pipe, 648 . air space, 170. 178. conduction problem soultion, . 101, 107 conductivity materials, 91, ! 171-175,178.179- contaminantexhaust, 1042 convection conductances, 93 conversion equations, 15' Surface ` - ' ' condensation, 205.217,221,656 conductance, 3, 170, 177 . coefficients, 92, 170,662' - external pipe, 624, 626; 654 heating, 9 . extended,9 temperature, 202,415,580,1148 Suspended unit heater, 596 oonveying velocity, 1044-1047 cooling coil arrangements, 839 on1ing tower performance, 824 <v%nKng tower pipe size, 1114 copper elbow equivalents,* 537 copper sheete, 758 oopper tube capacity, 540 - copper tube dimensions, 626 oopper tube surface, 626 correction factors . ' Symbols, 12,13,14,15 . ' air conditioning,' 21 . for drawings, 17- ' ' heating, 18 piping, 17 ventilating, 19 - steam radiator, 568 . unit heaters, 598 water radiator, 568 corrosion resistance^ 1156' cost of air conditioning; 1006 ' decibel scale. 943 - degree-days for cities, 451-454, . 460-461 design dry- and wet-bulb Tables air changes, 233 ' air conditioning temperatures temperatures, 251, 259, 276. 279, 1016, 1101 design humidity, 1016-1028 and humidities, '1016-1026 . XXI Heating Ventilation Air Conditioning Guide 1956 Tables (continued) - draft in ohimneya, (35 draft requirements of appli ance*, 436 duct attenuation, 949, 950- duct combinations, 458, 479 duct (apes, 757 duct joints, 756 duct pressure drop; 489 duct sizing, 466, 467, 479, 480, 485; 486. 1044 duct velocity, 747 duct weight, 758 dust concentration, 155 elbow attenuation, 950 elbow equivalent, o09,537,740, 1112 electric beating systems, 966 electric water beaters, 975 emissivity factors, 95, 96, 170 end reflection, 954 .. environmental conditions, limits, 118 . equivalent length of fittings, . 466, 467, 468, 509, 1112 . equivalent temperature dif ferentials, 292,294 _ exhaust pipes for machines, 1044-1048 - exhaust velocities, 1042, 1044 . 1048 . .expansion tank sizes, 550 fabric filters, 798 ` fan outlet velocity, 776 fan speed, 770 __ fitting allowance, 468, 482, 509 fitting dimensions, 633-643 - fixture flow, 1106 fixture units, 1106 \' flammability of gases and vapors, 162 flanged fittings surface, 655 flue gas dewpoint, 365 free convection, 94 friction loss, pipe. 389, 506, 510-515, 538, 540 . friction valves and fittings, 509,537, 1106 fuel combustion, 358 fuel consumption, 456, 457 fuel oil properties* 342 fumes, concentration, 160 gas analysis, 348 gas piping capacity, 389 . gaseous fuel properties, 348 glass absorptance, 300 glass transmittance, 300 graphical symbols, 17 heat absorbed, cooling water, 821 heat conductance, 93,101,170 173,178, 179 heat equivalents, 270 . heat flow walls and roofs, 190 193, 196-199, 292 : heat gain applianoes, 316 ooil heat emission, 566 glass, 301, 302 glass blocks, 305^307 - insulated cold pipes, 665 heat loss . - bare copper pipe, 654 bare steel pipe, 566, 654 . basement, 263 . floor, 265 pipe coils, 566 radiation, 96 residence, 271, 273 room, 271, 581 heat pump, 866 . heat transmission coefficients, 190 . building construction, 190 200, 292-296 doors, 200 ' glass, 200 roofs, 196-199, 296 walls, 190-193 water beaters, 1122 hot water demand. 1106, 1115, 1118 Tables (continued} '' hot water pipe sues, 538, 540 humidities, industrial air con ditioning, 1016^-1026 hyyosoopic materials, 1028 incident angle, 287 inertial separator, 796 . infiltration through outside doors, 232 infiltration through walls, 228 infiltration through windows, 230 inflammability, gases, 162 inside temperatures, 259, 279, 1016-1026 . instantaneous solar heat gain,- 301, 302, 304-307 insulation conductivity, 657 * insulation factors, 661 insulation thickness, 667, 668 insulation to prevent freezing, 666 insulation, underground, 668 intake velocity, 726 iron elbow equivalents, 537 life of equipment, 1006 . limits for. contaminants, 163 load factors, 462 maintenance cost, 1011 maximum allowable concern* tratioxu . dust, fumes, mists, 160 dusts, 160, 161 flammable gases, 158 gases, 158 vapors, 158 - metal gages for ducts, 757,1053 meter performance, 1112 . minimum outdoor air require ments to remove odors, 113 moistare content for ma terials, 1028 . moisture regain, 1028- . moisture transfer, 213 'motor classification, 926 motor current, 927 ` ' motor design limits. 924 motor drive applications, 931 motor horsepower, 924 motor ratings, 933 motor 8peed range, 924 motor starting methods, 934 motor torque, 931 motor voltage, 924 ' noise levels, 945,946 oil fuel specifications, 344 oil heat value, 344 operating cost, 1006,1009, 1010 operating hours, 1011 orifioe capacities, 504, 541 outdoor air requirement, 113 outlet velocities, 776 ` __ - outside temperature, 251, 279, 451 . owning and operating cost, 1006 particle size, 153, 154. - particulate matter, size, 153 permeability to vapor, 213 . physiological response to heat, pipe capacity, 389, 508. 508 510, 512-516; 638, 540, 878, 879 pipe covering factors, 661 pipe dimension, 624 pipe fittings, 630 dimensions, 633-642 pressure ratings,- 632 . - pipe freezing prevention, 666 pipe insulation, 657 ' pipe roughness, 73 pipe surface, 624 * thermal stress, 645, 646, 648. pipe volume, 624 pressure loss - ducts, 489- ` * elbows, 509, 537, 1112 fittings, 468, 482, 509, 537, 1112 ' . . refrigerant line, 878, 879 Tables (continued) registers, 487, 488 return intake, 726 properties of air, 32 . dichlorodifluoromethane, - 851 fuel oil, 342 gaseous fuels, 348 moist air, 32. monochlorodifluoro- metliane, 853 monofluorotrichloro- methaoe, 854 steam, 49 - water, 40 radiation, black body, 98 radiation factors, 95, 569 radiation problem solution* 97 radiator heat loss correction factors, 568 radiator sizes, 563, 564 a rating air conditioning units, 817 . rating steel boilers, 400 ratio of specific heats, 73 refrigerant properties, 851,853, refrigerant line capacity, 878, refrig87e9ration equ.ipm.ent.selec tion, 882 , regain of hygroscopic ma terials, 1028 . requirements for fuel oil, 342 return pioe capacities^ 507, 512 room temperature differential, 260 screen mesh, 154 hading effect, 309 - sheet metal gages for ducts, 757, 1053 ................ ship design conditions, 1101 limn control, 993 . slime formers, 983 ` smoke chart numbers, 1163 snowfall data, 585 anow melting systems, 587 sodium diebromate, 996 soil conductivity, 174 sol-air temperature, 290 ifnlftr altitude, 286, 288 rfor azimuth, 288 ' . solar declination, 288 solar heater design; 1127 solar radiation, 286 sound attenuation, 947-951, sound level, 945,946 . . sound pressures and intensi ties, 943 . ' specific gravity factors, 390 specific neat of compressible fluids, 73 . specific heat ratio, 73 spray pond design data, 813 steady-fitate conduction prob lems, 101 . steam consumption of build ings, 459 steam conversion factors, 667 steam pipe capacities, 506, 508-510, 612-515 steam table, 49 steel boiler ratings, 400. 401 summer climatic conditions, 279 , summer design conditions, 276, 279 surface conductance, 93, 170 temperature differential, 260, 292,294,691 .. temperature, industrial air conditioning,. 1016-1026 temperslure, inside, 259, 275, 1015-1026 . temperature limit for men, 118 temperature range, 278 temperature, summer, 279 temperature, w inter, 251 Index to Technical Data Section Tables (continued) .. thermal conduction problems, 107. 113 . thermal conductivity, 91, 657 thermal convection conduct- anoe, 93 .. thermodynamic properties moist air, 32 water, 40 transmittance, glass., 300, 301 unit conditioner rating, 617 unit fuel consumption, 456 ' unit heater capacity factors, unit ventilator capacities, 606 upper temperature limits, 118 vanes in elbows, 740 ' vapor transfer. 216 velocity, return intake, 726 ventilation standards, 285 warm air ducts, 466 warm air fittings, 468 water analyses, 982, 1003 water cooling effectiveness, 821 water fixture flow, 1106 water main temperatures, 806 water meter performance, 1112 water pipe capacities, 538/540 water requirements, 1115,1116, 1118 . weight'of air, 32 ' "' weights of ducts, 758 . wet collectors., 797 . . winter climatic conditions, 251 winter design temperatures, 251 ' Tank, tanks expansion, 550 Tax, pipe,403 . . Temperature, temperatures absolute, 9, 30 a attic, 261 ' automatic control, 895, 907 basement, 263 ' ' control for railway passenger car, 1092 control service water, 1123 * . design wet-bulb, 276, 279, 619 dew-point, 26 dry-bulb, 9 ' drying, 1083 effective, 9. ground, 263, 264 . hazard,117 industrial, 1161 - inside, 259, 276, 1101 . ceilings, high, 259 '' proper level, 259 mean radiant, 120, 578 measurement, 1145 1' pyrometers, 1149 thermocouple, 1146 ' thermometers,-1145 - outside, 251, 279 scales, 9 surface, 202, 414, 1148 thermodynamic wet-bulb, 26 unheated spaoes, 263 water main, 806 wet-bulb, 6 Terminology, 1 Test methods, 1145, 1167 ' Testing codes, 1167 Therapy cold, 143 fever, 142 oxygen, 145 Thermal conductance, 167, 170, 171 conduction equation, 90 conductivity, 90, 168 convection, 89, 91. convection equation, 91 expansion of pipe, 644 integrator, 1162 interchanges of body, 113 Thermal (continued) radiation equation, 92 resistance, 8, 167,170 resistivity, 8,170 . steady-state conduction prob lems, 101 . transmittance, 266 unit conductances for oon- vection, 93 Thermocouples, 1146 Thermodynamics. 23 air and water mixture, 25, 29, 32 laws of. 9, 23 wet-bulb temperature, 26 Thermometers. 1145 alcohol, 1145 dry'bulb, 1155 globe, 1162 Kata, 1157 mercurial, 1145 resistance, 1148 stem correction, 1145 wet-bulb, 1158 - Thermostat. 9,901 . - room. 908 Time lag through walls and roofs, 311, 689 Ton of refrigeration, 8 Total heat, 5 . Total pressure, 7 Tower, towers. 813 oooiing, design, 820. cooling, performance; 822 mechanical draft, 815 natural draft, 813 selection, 825 . spray cooling, 813 ' Transmission heat losses, 263-267 solar heat, 290, 297 Transmittanoe, thermal, 9 Transportation air conditioning, 1089 . . . temperature and humidity control, 1092, 1093, 1095 Trap, traps. 524. . . alternating receiver, 528 _ automatic return, 499, 528 bucket, 526 float, 524,526 impulse, 527 Installation, 528 steam, 524 - thermostatic, 524 .. . tilting, 527 . .. Traveling-grate stoker, 369, 371 Treatment of disease,.131,.137 Tropical air cooling, 136 ` Tube radiator, 8 Tunnel dryer, 1082 Tunnels, pipe, 678 . Turning vane, 724, 740 Two-pipe system, 10, 490; 510,' 540 u Ultra-violet light, 113,132, 156 Underfeed stoker. 368-370 . Underground pipe insulation, 667 Unheated space temperatures, 263 - Unit, units air cleaners, 781, 792 air conditioners, 609 application, 610 cooling, 619 dehumidifying, 613 humidifying, 613 ratings, 616, 617 remote units, 610, 614 xxiii' Unit, units (contirtiied) sound isolation, 613 types. 609 ' air ooolers, 619 defrosting, 620 design, 619 performance, 619 ratings, 620 types of, 619 air filters, 781..787 .British thermal, 2 dehumidification, 613 direct-indirect heating, 3 fuel consumption, 445 heaters, 595 application, 597 automatic oontrol, 600 boiler capacity, 603 capacity factors, 598 classification, 595 oontrol, 600 direct-fired, 595 electric, 597 maintenance, 602 ' outlet velocity; 597 piping connections, 600 ratings; 597 temperatures, 598,,600 types of, 595 " humidifiers, 810 types, of, 810 ' induction, 692, 693 - noise measurement;941 - systems, 595 ventilators, 604 - air exhaust vents, 608 - applications, 606 capacity, 605 ' - control, 607 location, 607 - ratings, 604 selection, 607 > window, 608' Unitary equipment, 595 definitions, 595 V Vacuum .. cooling units, 861 beating numps,.522 . ' oontrol, 523 piston displacement, 523 heating system, 10, 600 down-feed, 500 unit heater connection, 601 Valve, valves. 533, 635,902 automatic, 902 - check, 641 control, 533 . expansion, 875 gate, 533, 638 globe, 638 . . reducing pressure, 518, 641 relief, 552, 641 Van*, vanes, 70S, 715, 724. 740 Vaned outlets, 724 Vapor, vapors, 151 adsorption, 799 barrier, 208, 213, 221 heating systems, 10, 498 pressure, 7 transfer, 208 transmission, 208 . unit heater connection, 601 Vaporizing oil burner, 377 ^ Velocity. 10 capture, 1042 coil, 836, 841 oonveying, 1044-1048 duct, 747, 1044 exhaust intakes, 726, 1044-- 1048 hood, 1044 operating, 747, 776, 1042, 1044 1048 ' pressure, 7 reduction method, 748 Heating Ventilating Air Conditioning ...Guide 1956. Velocity '(continued). ; return grilles..728-. unit beater,' 595 - Ventilation, 10,278 animal shelters, $42-246 dairy stables, ?43 uvina apace, cm, ho - - natural, 235 - general rules, 241 .- passenger bus in summer, 1094 railway passenger car, 1091 : rules, 241- .- ship. 1100 symbols for drawings, 17 . systems, 677 ' walls and attics, 224 . wind foroes, 236 - Ventilator, ventilators. 240 oontrol, 241 . roof, 240 unit, 604 oontrol, 607,917 window, 608 ^ Vertical blow unit heater, 595 Vertical openings. 234 sealing of, 228 Vibration, machine, 959 Viscous filters, 783 impingement, 783 Vitiation of air. 111 Volume . control, 725 furnace, 374, 381. specific, 10 W Wall, walls heat flow through; 190-193,289 hast transfer coefficients, 88. 190-193 .. infiltration through, 228 * time lag of solar radiation, 310 Warm air gravity heating system, 463 combination carrying1 ca pacity, 469,470 . design procedure, 465, -469, 473 extended plenum, 473 furnace capacity, 412 installation practice, 463, standardized combinations, 466-470 ffifahawfcal heating systems, 475 air distribution. 467 ` automatic control, 415, 490, 895 ceiling panel system, 490 Warm air (continued) combination of parts, 478 cooling, methods, 1129 continuous circulation, 490 dampers, 477 . . " design procedure, 472, 481 ducts, 477 fans, 410 filters, 410 furnaoe, 409heavy duty, 411' selection, 473, 484 . humidification, 415 . ' large systems, 481 perimeter system, 491 ., pressure drop, 489 ' 1 . registers ana grilles, 476 standard combinations, 466, 478 panel heating, 490 radiators, 387 Washer, washers, 803 air, 1, 799, 801 cooling, 807 dehumidification, 807 humidification, 80S Water analysis, 982 atmospheric cooling equip ment, 811,813 - characteristics, 982 classification, 982 coils, 832, 1121 content of radiators, 550 control temperature servioe, 1123 cooled - condenser, 872 . cooling tower, 813 corrosion treatment, 997 demand, 1106,1115-1118 faucets, 1106 ' - fittings, loss, 1106,1111 fixtures, 1106 - fixture units, 1106 formed deposits, 981 - heater ' coal-fired, 1118 solar, 1125 heating. 1118 . . in building material, 207 load, 110$ make-up, 827,990 miimnm main temperature. meters, 1111 - - mineralized, 982 ' properties of, 40, .982 ' ` services, 1105 _ ` storase capacity, 1115 ` supply piping, 1122 " ' arrangement; 1122- temperature control, 1123 . - Water (continued)- .. ... *f. ther4m0od- ynamic propertie:s-Vf,- treating chemicals, '981, 1002 ' well temperatures, 808 Water vapor, 25, 32-39, 205 condensation in buildings, 205 saturation pressure, 25, 40 ' specific enthalpy, 4 specific volume, 10, 40 surface condensation, 217 Welding, 623 Wet-bulb temperature (see .. Temperature), 9,26,819 Wet cup, 212 '- Wet return, 8, 493 * Wind, winds '' foroes, 228, 235 - due to stack effect,;228 : natural draft equipment,'421. selection of, velocity, 250, 251. 278 . Window, windows " 1 ' coefficients of transmission, . 200 ' ' leakage, 229 '. solar radiation through, 297 ventilators, 607 ' Winter .' ' ' air conditioning System; 685, 1129 .: ' comfort sone, 124 .~ freezing equipment, 828 Wound rotor motor, 928 . Wrought-iron pipe, 823 * ' Wrought-cteel pipe, 623 ' ' ,Y Year-round air conditioning system. 685, lt29.;> air flow in, 637,-1133 .`7 ' . control methods,'687, 912 . design procedure,;685, 731' equipment arrangement, .TOO installation, 685,1129 . location of apparatus, 700,1132 residential, 908 .- - . . .. selection, 698, 1129.. Z . ; - Zone control, 687' . ; - Zone of evaporative^ regulation, 1115 Zoning, 552,687,908 control, 687,908 -. hot water system, 552. reheat, 688 - . volume control, 687 CHAPTER 1 TERMINOLOG Glossary of Physical and Heating, Ventilating and Air Conditioning Terms Used in the Absolute Zero: The zero from which absolute temperature is reckoned. Ap proximately --273.15.Cor --459.67 F. These values were established by the Tenth General Conference on Weights and Measures, 1954. * Absorbent: A sorbent which changes physically or chemically, or both,.during the sorption process.. Absorption: The action of a material in extracting one or more substances present in an atmosphere or mixture of gases or liquids; accompanied by physical change, chemical change, or both, of the sorbent. Acceleration: The time rate of change of velocity, t.e., the derivative of velocity with respect to time. In the cgs system the unit of acceleration is the centimeter per (second) (second); in the fps system the unit is the foot per (second) (second), a = -- Acceleration Due to Gravity: Tiro rate of gain in velocity of a freely falling body the value of which varies with latitude and elevation. The international gravity standard has the value of 980.665 cm per (sec) (sec) or 32.174 ft per (sec) (sec) which is the actual value of this acceleration at sea level and about 45 deg latitude. Adiabatic: Ah adjective descriptive of a process such that no heat is added to, or taken from, a substance or system undergoing the process. Adsorbent: A sorbent which does hot change physically or chemically during the sorption process. : .' .. :. Adsorption: The action, associated with surface adherence,-of a material in ex tracting one or more substances present in an atmosphere or mixture of gases and liquids, unaccompanied by physical or chemical change. Commercial adsorbent materials have enormous internal surfaces. Aerodbl: An assemblage of small particles, solid or liquid, suspended in air. The diameters of the particles may vary from lOO znicrons down to 0.01 micron or less, e.g.t dust, fog, smoke. .. Air Cleaner: A device designed for the purpose of removing airborne impurities such as dusts, gases^ vapors,'fumes and smokes. (Air cleaners include air washers; air filters, electrostatic precipitators and charcoal biters.) . Air Conditioning: The simultaneous control of all, or at least the' first three, of the following factors affecting both the physical and chemical conditions of the at mosphere within a structure: temperature, humidity, motion, distribution, pressure, dust; bacteria, odors^toxic'gases, and ionization. Air, Dry: In psychromefry; air unmixed with/ or containing no,: water vapor., ' Air, Saturated : A mixture bf dry air and saturated water vapor, all at the same dry-bulb temperature. ; ............. .. !. .. ...... . . Air, Standard: Air with a density of 0.075 1b per cii ft and an absolute viscosity of 1.22 X 10** lb mass per (ft) (sec); This is substantially equivalent to dry air at 70 F and 29.92In. (Hg) barometer. . . . . , *' Air Washer: An enclosure in which air is drawnor forced through a spray of water in onier to cleanse, humidify, or dehumidify the air. ; `. Anemometer: An instrument for measuring the velocity of a fluid. . Aspect Ratio:. In-air distribution outlets, the ratio of the length of the core of a grille, face or register to the width. . - , . In rectangular ducts, the ratio of the width to the depth. " Atmospheric Pressure: The pressure of the atmosphere to be measured by means of the barometer. Atmdspfoeric Pressure or Standard Atmosphere is exactly l,013,250:dynes per square centimeter by recent action of* the Tenth General Con ference on Weights and Measures (1954). It is approximately the pressure exerted by a column .of mercury 76 cm high at standard gravitational acceleration, 980.665 1 2 CHAPTER 1 1956 Guide cm per (sec) (sec), the mercury having a density of 13.5951 grams per cubic centimeter. It is equivalent- td i4.696 psi or 29.921 in. of mercury at 32 F. '. Baffle: A surface used for deflecting fluids, usually in the form of a plate or wall. Blast Heater: A set of heat transfer coils or sections used to heat air which is drawn or forced^through it by a faii. * Blow (throw): In air distribution, the distance an air stream travels from an outlet to a position at which air motion along the axis reduces to a velocity of 50 fpm. For unit heaters, thejdistance an air stream traVels from a heater without a per ceptible rise due to;temperature difference and loss of velocity. Boiler Heating Surface: That portion of the surface of the heat-transfer apparatus in contact with the fluid being heated on one side and the gas or refractory being cooled on the other, in which the fluid being heated forms part of the circulating system; this surface shall be measured on the side receiving heat. This includes the boiler, water walls, water screens, and water floor. (ASME Power Test Codes, Series 1929.) : Direct Heating Surface is generally understood to be the boiler heating surface subject to direct radiation from the surface of the grate, or from the surfaces of oil or gas burners. Indirect Heating Surface is the boiler heating surface within the flues. Boiler Horsepower: The equivalent evaporation of 34.5 lb of water per hr from and at 212 F. This is equal to a heat output of 970.3 X 34.5 = 33,475 Btu per hr. British Thermal Unit (Btu) : The Btu is defined as 778.177 foot-pounds if it is re lated to the IT calorie in such a way that 1 IT calorie per (kg) (C deg) = 1 Btu per (lb) (F deg), with 1 lb = 453.5924 grams. The Ninth General Conference on Weights and Measures (1948) recommended the absolute joule as the fundamental unit of energy thereby, in effect, liquidating the old international electrical units. This calls lor a redefinition of the International Tables calorie (IT cal) according to the following conversion factor: 4.18684 joule per IT calorie. Calorie (Gram Calorie) : The IT gram calorie is equivalent to 0.003968 Btu. (See definition of Btu.) - Central Fan System: A mechanical indirect system of heating, ventilating, or air conditioning, in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and is conveyed to and from the rooms by means of a fan and a system of distributing ducts. (See Chapter 30.) . Chimney Effect: The tendency of air or gas in a duct or other vertical passage to rise when heated due to its lower density compared with that of the surrounding air or gas. In buildings, the tendency toward displacement (caused by the difference in temperature) of internal heated air by unheated outside air due to the difference in density of outside and inside air. Comfort Air Conditioning: The process by which simultaneously the temperature, moisture content, movement and quality of the air in enclosed spaces intended for human occupancy may be maintained within required limits. (See also general definition of Air Conditioning on page 1 of this chapter.) Comfort.Line: A line on the comfort chart showing relation between the effective temperature and the percentage of adults feeling comfortable. Comfort Zone (Average): The range of effective temperatures over which the ma jority (50 percent or more) of adults feel comfortable. (See Chapter 6.) Condensate: The liquid formed by `condensation of a vapor. In steam heating, water condensed from steam: in air conditioning, water extracted from air, as by,con densation on the cooling coil of a refrigeration machine. Condensation:.The process of changing a vapor into liquid by the extraction of heat. Condensation oi steam or water vapor is effected in either steam condensers or in dehumidifying coils and the resulting water is called condensate. Conductance, Surface (C/nti): The amount of heat transferred by radiation, con duction, and convection from unit area of a surface to the air or other fluid in contact with it, or vice versa,-in unit time for a unit difference in temperature between the surface and the fluid. The common unit is: Btu per (hour) (square foot) (Fahren heit degree). Symbol /. The temperature of the fluid should be taken in a plane sufficiently far from the surface that it will not be affected by the temperature of the surface. ... Conductance, Thermal: The time rate of heat flow through unit area of a body, of given size and shape, per unit'temperature difference. Common unit is: Btu per (hour) (square foot) (Fahrenheit degree). Symbol C. Conduction, Thermal: The process of heat transfer through a materia! medium in Terminology 3 which kinetic energy is transmitted by the particles of the material from particle to particle without gross displacement of the particles. - '- . Conductivity, Thermal: The time rate of heat flow through unit area of a homo geneous substance under the influence of a unit temperature gradient. Common units are: Btu per (hour) (square foot) (Fahrenheit degree per inch). Symbol k. Conductor, Thermal: A material which readily transmits'heat by means of con duction. ; : .. . Convection: The motion resulting in a fluid from the differences in density and the action of gravity. In heat transmission this meaning has been extended to include both forced and natural motion or. circulation. Convective Heat Transfer: The transmission of heat by either natural or forced motion of-a fluid (liquid or gas). .' . Convector: An agency of convection. In heat transfer, a surface designed to transfer its heat to a surrounding fluid largely or wholly by convection. The heated fluid may be removed mechanically or by gravity (Gravity Convector). Such a surface may or may not be enclosed or concerned, when concealed and enclosed the resulting device is sometimes referred to as a concealed radiator. (See also definition' of Radiator.) (See also Chapter 23.) - Decibel: A unit used to express the relation between two amounts of power. By definition the difference in decibels between two powers P\ and Pt, Pi being the larger, is: db difference = 10 logioPj/Pi. ^ In acoustics the threshold of hearing at 1,000 cycles per Bee has been standardized at 10"" watts per sq cm. If Pi is the power in watts per square centimeter of a measured sound, then 10 logio P*/10^ie is the db difference above the threshold-and is known as the intensity level. This is a definite recognized way-of describing the intensity of a sound. : Declination of Sun: The angle above or below equatorial plane. It is plus if north of the plane, and minus if below. Celestral objects are located by declination. Degree-Day: A unit, based upon temperature difference and time, used in estimat ing fuel consumption and specifying nominal heating load of a building in winter. For any one.day, when the mean temperature is less than 65 F, there exists as many, degree-days as there are Fahrenheit degrees difference in temperature between the mean temperature for the. day and 65 F. ,- Dehumidlfy: To reduce by any process, the quantity of water vapor within a given space. . ; Dehydrate: To remove water in all forms from.matter.. Liquid water, hygro-. scopic water, and water of crystallization or water of hydration are.included. . .. Density: The ratio of the mass of a specimen of a substance to the volume of the specimen. The mass of a unit volume of a substance. When weight can be used without confusion, as synonymous with mass, density is the weight per unit volume. Dew-Point: See Temperature, Dew-Point. Diffusivity, Thermal: Thermal conductivity divided by product of density and specific heat = k/pc. Expressed in units of square feet per hour. Direct-Indirect Heating Unit: A heating unit located in the room or space to be' heated and partially enclosed; the enclosed portion being used to heat air which enters from outside the room. .- ., : Direct-Return System (Hot Water): A hot water system in which the water, after it.' has passed through a heating unit is returned to the boiler along a direct path so that the total distance traveled by the water is the shortest feasible, and so that there are considerable differences in the lengths of the several circuits composing the' system.' Down-Feed One-Pipe Riser (Steam): A pipe which carries steam downward to.the heating units and into which the condensate from the heating units drains. Down-Feed System (Steam): A steam beating system in which the supply mains are above the level of the heating unite which they serve. Draft: A.current of air. Usually refers to the pressure differencewhich causes a current of air or gases to flow through a flue, chimney; heater or space. . Draft Head (Side Outlet Enclosure) z The height of a gravity convector between the bottom of the heating unit and the bottom of the air outlet opening. (Top Outlet Enclosure): The height of a gravity convector between the bottom of the heating unit and the top of the enclosure. . . . .. . .... Drip: A pipe, or a steam trap and a pipe considered as a unit, which conducts con-' densation from the steam side of a piping system to the water or return side of: the system. .' 4 CHAPTER 1 1956 Guide . Dry: To separate or remove a liquid or vapor from another substance. The liquid may be water, but the term is also used for the removal of liquid or vapor forms of other substances. . Dust: An air suspension (aerosol) of solid particles of any material. (See also Chapter 8.) : : Enthalpy: A term used in lieu of total heal or heat content. Expressible in Btu per pound. Mathematically defined as h = u + pv/J. When a change occurs at con stant.pressure, as when water is boiled, the change in enthalpy is equal to the heat added; in this case latent heat. '. " Enthalpy, Free: A thermodynamic property which serves as a measure of the available energy of a system with respect to surroundings at the same temperature and same pressure as that of the system. No process involving an increase in avail able energy can occur spontaneously. ' Enthalpy, Specific: A term sometimes applied to enthalpy per unit weight, the English unit being Btu per pound. , Entropy: The ratio of the heat added to a substance to the absolute temperature at which it is added. Mathematically, for a reversible process, dS = dQ/T or S *= fdQ/T. - .. These formulas are applicable when temperature is not constant. During a re versible adiabatic change, entropy: is constant. During a reversible isothermal . change, the heat absorbed by the substance is equal-to the product of the absolute temperature of the substance and its change of entropy. . Entropy, Specific: A term sometimes applied to entropy per unit weight, the English unit being Btu per (Fahrenheit degree, absolute) (pound). Equivalent Evaporation: The amount of water a boiler would evaporate, in pounds per hour, if it received feed water at 212 F and vaporized it at the same temperature and corresponding atmospheric pressure. Fan Furnace System: See Warm Air Beating System. Fog: Suspended liquid droplets generated by condensation from the gaseous to the liquid state, or by breaking up a liquid into a dispersed state, such as by splashing foaming, and atomizing. (See also Chapter 8.) *- Force: The action on a body which tends to change its relative condition as to rest or motion. . Fumes: Smoke; aromatic smoke; odor emitted, as of flowers; a smoky or vaporous exhalation, usually odorous, as that from concentrated nitric acid. The wordfumes is so broad and inclusive that its usefulness as a technical term is very limited. Its principal definitive characteristic is that it implies an odor: The terms vapor, smoke; fog, etc., which can be more strictly defined, should be used whenever possible.- ' .` l Also defined as solid particles generated .by condensation from the gaseous state, generally, after volatilization from molten metals, etc., and often accompanied by a chemical reaction such as oxidation. .Fumes flocculate and sometimes coalesce. (See also Chapter 8.) . ;. .. . ' Furnace: That part of a boiler or warin air heating plant in which combustion tajres place. Also a complete heating unit for transferring heat, from fuel being bnrnea to the air supplied to a heating system. ; ,. . . .. Furnace Volume (Total): The total furnace volume for horizontal-return tubular.' boilers and water-tube boilers is the cubical contents of the furnace between the grate andjthe fust plane of entry into or between tubes. It therefore includes the volume behind the bridge wall as in ordinary horizontal-return tubular boiler settings, unless manifestly ineffective (i.e., ho gas flow taking place through it), as in the case of waste-heat boilers with auxiliary coal furnaces; where one part of the furnace is out of action when the other is being used. For Scotch or other internally-fired boilers, it is the cubical contents of the furnace* flues and combustion chamber, up to the plane of first entry into'the tubes. (ASME Power Test Codes, Series 1929.) Grate Area: The area of the grate surface, measured in square feet, to be used in estimating.the rate of burning fuel.;. This area is;construed.to mean the area meas ured in the plane of the top surface of the grate, except that; with special furnaces,, such as those, having magazine feed, or special shapes, the grate area shall be the mean area.of the active part of the fuel bed taken perpendicular .to the path of the gases through it. For furnaces having a*secondary grate, such as those in double grate down-draft boilers, the effective area shall be taken as the area of the upper grate plus one-eighth of the area of the lower grate, both areas being estimated as previously defined. V* ' Gravity, Specific: The ratio of the mass of a unit volume of a substance to. the. mass of the same volume of a standard substance at a standard temperature. Water Terminology 5 at 39.2 F is the standard substance ;usuaUy rafeiyqd 'tar: d^.*ra `the same temperature and pressure as the. gas, is often taken as the. StandardIsubstancA: Gravity Warm Air Heating System: SeeWarm Air 'Heating System^ > Head, Dynamic: Same as Total Pressure expressed in height of liquid. Heat: That form of energy which transfers from one. system to. another, by virtue of the temperature difference which exists between the two systems, wheh'they are placed in communication. ' . . . - ~ ,'v Heat, Humid: Ratio of increase of enthalpy, per pound of dry cur tc. nsc of tcsj perature under conditions of constant pressure and constant humidity ratio:; v -.h ; Heat, Latent: A term used to express the energy involved in a change of state::? Heat, Sensible: A term used in heating and cooling to indicate any portion ofheat which changes only the temperature of tne substances involved;. . : ''v/ Heat of the Liquid: The increase in enthalpy per unit weight of a saturated liquid as its temperature increases from a chosen base temperature. -;For water, .the base temperature.is usually taken as 32 F. . \r -- Heat, Specific: The heat absorbed (or given up) by a unit ihass of af Substance when its temperature is increased (or decreased) by 1- deg. Common Units^ Btu per (pound) (Fahrenheit degree), calories per .(gram)-(Centigrade degree).. For gases, both specific heat at constant pressure (cp) and specific heat at constant vol-qme(cT) are frequently used. In air conditioning, cp is usually used. ;rV; :C'r.; > Heat, Total: See Enthalpy. - .. - \`: Heat Transmission, Coefficient: Any one of a number of coefficients used in the calculation of heat transmission by conduction, convection, and radiation, through various materials and structures. (See thermal conductance, thermal conductivity, thermal resistance, thermal resistivity, thermal transmittance, etc.) :' * Heating Element, Electric: A unit assembly consisting of a resistor, insulated sup ports, ana terminals for connecting the resistor to electric power. - ; Heating Unit, Electric: A structure containing one or more heating elements1; electrical terminals or leads, electric insulation, ana a frame or casing, all assembled together in one unit. ' . .. .-s Hot Water Heating System: A heating system in which water is used as .the me^ dium by which heat is carried from the boiler to the heating units. Humidify: To increase, by any process, the density of water vapor within a given space. ' . ' ' ' . ' ' y- - 1-y; Huinldistat: A regulatory device, actuated by changes.in humidity, used for the automatic control ofrelative humidity. .. .^ Humidity: Water vapor within a given space. :r :: Humidity, Absolute: The weight of water vapor per unit volume, pounds per cubic foot or grams per cubic centimeter. -' ' Humidity, Relative: The ratio of the mol fraction of water vapor.in a mixture to the mol fraction of water vapor in saturated air at the same dry-bulb temperature and barometric pressure. (See discussion in Chapter 3.) Also defined in various texts as the ratio of the actual partial pressure of the-water vapor in a space to the saturation pressure of pure water at the same temperature. : Humidity Ratio: in a mixture of water vapor and air, the weight of water vapor per pound of dry.air. Symbol, W. Also coded Specific Humidity. . :: . - Humidity, Specific: SeeHumidity Ratio. . Hygrostat:; Same as Humidisttit. ... . ; ,' . Inch of Water: A unit of pressure equal to the pressure exerted by a column of liquid water 1 in: high at a.standard temperature. The standard temperature is sometimes taken as 0 C and sometimes as 62 F. One inch of waterat 62 F = 5.1971b per sq.ft. ..... - 1 : . ' . - - -d Insulation (Thermal): A material having a relatively high resistance to heat flow4, and used principally to retard the flow of heat. Isobaric: An adjective used to indicate a change takipg place at constant pressure! Isothermal: An adjective used to indicate a change taking place at constant temperature. - . - - s" - ; . Load, Estimated Design : In a heating or cooling system, the sum of the useful heat transfer, plus heat transfer from or to the-connected piping, plus heat transfer occurring in any auxiliary apparatus connected to.the system. Tne units are Btu per hour or, in heating, equivalent direct radiation (EDR).. ' : .. Load, Estimated Maximum : In a heating or cooling system, the Calculated maxi* mum heat transfer that the system will be called upon to provide. . 6 CHAPTER 1 1956 Guide Manometer : An instrument for measuring pressures; essentiallya U:tube par-' tially filled with a liquid, usually water> mercury, or a light ofl; so constructed that the amount of displacement of the liquid indicates the pressure being exerted on the.' instrument. . .: . Mass: A measure of the inertia of abody. It also measures the-quantitv of matter in a body. Since the only general property of a given portion of matter that cannot be changed is its inertia, it is this property by which quantities of-matter are defined; Two bodies which have equal inertias are.paid to have equal masses, or to contain equal quantities of matter. (This definition fails at velocities approaching the veloc ity of light.) The mass of a body is numerically equal to the ratio' ofthe. force re quired to give the body a given acceleration-, to the acceleration'.- m = F/a. The common units of mass are the gramcand the pound. / :: . * Mechanical Equivalent of Heat: The-quantity of-mechanicail energy equal to one unit of heat. J = 778.177 ft^lb per.Btu '4;1858 X TO7 ergs per gram-calorie. Medium, Heating: A substance such as water,.steam, air or furnace gas used to convey heat from the boiler, furnace or other source of heat of energy to'the heating unit from which the heat is dissipated. Micron: A unit of length, the thousandth part of 1 mm or the millionth of a meter. Millimeter of Mercury: A unit of pressure, equal to the pressure exerted by. a column of mercury 1 mm high at a temperature of 0 C. : One millimeter of mercury at 0 C = 1.934 X 10"* psi. -- ... Mol: A weight of a substance numerically equal to. its molecular, weight. If. the weight.is in pounds the Unit is a Pound Mol.'ui grarps the unit is a Cham For perfect gases the volume of 1 mol is constant ior all gases at the same temperature and pressure. For real gases this is approximately triie-at moderate pressures'. At 32 F and zero-pressure the value of the product, pressure times specific volume,' is 359.045 d= 0.006 atmosphere cubic feet (atm ft*),-for<f mol ofany gas. For dry air at 32 F and standard atmospheric pressure, the specific volume is 358.83 cu ft per mol (ft* per mol). .... . ' -^ One-Pipe Supply Riser-- (Steam): A pipe which carries steam vertically to a heat ing unit, and which also carries the condensate from the heating unit. Inanup-feed system, steam and condensate flow in opposite directions^in an overhead or dpwn- feed system, they flow in the. same direction. . V . ........ ' ' . One-Pipe System--(Steam): A steam heating system in which a single main serves the dual purpose of supplying steam to the heatmg unit and conveying condensate from it. Ordinarily to each heating unit there is but one connection which must serve as both the supply and the return, although separate supply and return.connections may be used. (Hot Water)- -A hot water system in which the cooled water.from.the heating units is returned to the supply main. .Consequently, the heating units far thest from the boiler are supplied with cooler water than those near the boiler in the same circuit. .. ; , - Overhead System: Any steam or hot water system in which the supply main is above the heating- unit.. In a steam system-the return must be-below the heating units; in a water system the return may be above or below the heating units. . Panel Heating: A heating system in which heat is transmitted by both radiation and convection from panel surfaces to both air and'surrounding surfaces. ; - .' . Panel Radiator: A heating unit placed on or flush with a flat wall surface, and in tended to function essentially as a radiator; ' " V- . Perimeter System: See.Warm Air Beating System. Plenum Chamber: An air compartment maintained under pressure, and connected to one or more distributing ducte. > . `Potentiometer: An instrument for comparing small electromotive forces, or for measuring small electromotive. forces by comparison with a known electromotive force. Its principal advantage is that during the measurement, no current flows through, the source of electromotive force. . . : Power: The rate of performing work. Common units are horsepower, Btu per hour, and watts. .. . . Pressure: Force per unit area. Common units are pounds per square inch, gram pgr square centimeter, inch of water, millimeter of mercury. .: * Pressure, Absolute: The sumof the gage pressure and the barometric pressure. Pressure, Dynamic: Same as Total Pressure. ' Pressure, Gage: Pressure measured from atmospheric pressure as a base. G&ge pressure may be indicated by a manometer which has one leg connected to the pres sure source and the other exposed to atmospheric pressure. - Terminology 7 - Pressure, Saturation: The saturation pressure for a pure substance for any given temperature is that pressure at which vapor and liquid, or vapor and solid, can co exist in stable equilibrium. . Pressure, Static: The normal force per unit area that would be exerted by a mov ing fluid on a small body immersed in it if the body were carried along with the fluid. Practically, it is the normal force per unit area at a small hole in a wall of the duct through which the fluid flows (piezometer) or on the surface of a stationary tube at a point where the disturbances, created by inserting the tube, cancel. It is supposed that the thermo-dynamic properties of a moving fluid depend on static pressure in . exactly the same manner as those of the same fluid at rest depend upon its uniform hydrostatic pressure. . Pressure, Total: In the theory of the flow of fluids; the sum of the static pressure and the velocity pressure at the point of measurement. Pressure, Vapor: The pressure exerted by a vapor. If a vapor is kept in confine ment over its liquid so that the vapor can accumulate above the liquid, the tempera ture being held constant, the vapor pressure approaches a fixed limit called the maxi- . mum, or saturated, vapor pressure, dependent only on the temperature and the liquid. The term vapor pressure is sometimes used as synonymous with saturated vapor pressure. Pressure, Velocity: In a moving fluid, the pressure capable of causing an equiva lent velocity, if applied to move the same fluid through an orifice such that all pres sure energy expenaed is converted into kinetic energy. . Psychrometer: An instrument for ascertaining the humidity or hygroraetric state of the atmosphere. * ' Psychrometric: Pertaining to psychrometry or the state of the atmosphere with reference to moisture. . Psychrometric Chart: A graphical representation of the thermodynamic proper ties of moist air. Psychrometry: The branch of physics relating to the measurement or determina tion of atmospheric conditions, particularly regarding the moisture mixed with the air. : . Pyrometer: An instrument for measuring high temperatures. Radiant Heating: A heating system in which only the heat radiated from panels is effective in providing the heating requirements. The term Radiant Heating is fre quently used to include both Panel and Radiant Heating. . . Radiation: The transmission of energy by means of electromagnetic waves. Radiation, Thermal (Heat) Radiation: The transmission of energy by means of electromagnetic waves of very long wave length. Radiant energy of any wave length may, when absorbed, become thermal energy and result in an increase in the tempera ture of the absorbing body. . Radiation, Equivalent Direct (EDR): A unit of heat delivery of 240 Btu per hr. It does not imply 144 sq in. of surface. .... Radiator: A heating unit exposed to view within the room or space to.be heated. A radiator transfers heat by radiation to objects within visible range, and by conduc tion to the surrounding air which in turn is circulated by natural.convection; a socalled radiator is also a convector, but the term radiator has been established by long usage. Radiator, Concealed: A heating device located within, adjacent to, or exterior to the room being heated, but so covered or enclosed or concealed that the heat transfer surface of the device, which may be either a radiator or a convector, is not visible from the room. Such a device transfers its heat to the room largely by convection air currents. , -> Radiator, Direct: Same as Radiator. Radiator, Recessed: A heating unit set back into a wall recess, but not enclosed. Radiator, Tube or Tubular : A heating unit used as a radiator in which the heat transfer surfaces are principally tubes. .' . Refrigerant: A substance which produces a refrigerating effect by its absorption of heat while expanding or vaporizing. . Refrigeration, Ton of: The removal of heat at a rate of 200 Btu per min, 12,000 Btu per hr, or 288,000 Btu per 24 hr. . Resistance, Thermal: The reciprocal of thermal conductance. Symbol R. Resistivity, Thermal: The reciprocal of thermal conductivity. Symbol r. 8 CHAPTER 1 *1956 Guide Resistor; Electric: A material used to produce beat by passing an electric current throu^i:it. . v v. . : r.............................................................. ....... ' Return, Dry: A return pipe in a steam heating system which carries both water of condensation and air. The' ary return is above the level of the water line in the boiler in a gravity system. (See'Rettfn,Wet.y . . . ': . Return, Wet: That part of a return main of a steam heating system which is filled with water of condensation. The. wet return usually is below the level of the water line in the boiler, although not necessarily so. (See Return, Dry.) Return Mains : Pipes or conduits whicH return, the heatingnr cooling medium from the heat transfer unit to the source of heat or refrigeration. ' ' . Reversed-Retum System: A system in. which the heating or eooling medium from several heat transfer units is returned along paths arranged so that.all circuits com posing the system or composing a major sub-division of it are of practically equal length. ' : .- . 7' ' ' . . ' Sabin: A unit of equivalent sound absorption equal to the equivalent absorption of one square foot of a surface of-unit absorptivity (i.e., of one square foot.of surface which absorbs all incident sound energy). * . .. . . .. ; Saturation: The condition for co-existence in stable equilibrium of a vapor and liquid or a vapor and solid phase of the same substance. Example: Steam over the water from which it is being generated. . Saturation, Degree of: The ratio of the weight of water vapor associated with a pound of dry air to the weight of water vapor associated with a pound of dry air- saturated at the same temperature. ,- Smoke : An air suspension (aerosol) of particles, usually but not necessarily solid, often originating in a solid nucleus, formed from combustion or sublimation. Also defined as carbon or soot particles less than 0.1 micron in size which result from the incomplete combustion of carbonaceous materials such as coal, oil, tar, and tobacco. Smokeless Arch: An inverted baffle placed in an up-draft furnace towardthe rear to aid in mixing the gases of combustion, and thereby to reduce the1 smoke produced. Solar Constant: The solar intensity incident on a normal surface located outside the earth's atmosphere at a distance, from the sun equal to the mean distance between the earth and the sun. Its value is 415, 445, or 430 Btu per (hr)- (sqdt) as the July, January, or mean value, respectively. At sea level in July the solar intensity value iB about 300 Btu per (sq ft) (hr) since about 28 percent is absorbed in the earth's at mosphere. --: : Sorbent: A material which extracts one or more substances present in an atmos phere or mixture of gases or liquids with' which it is in contact, due to an affinity for such substances. . .. Sorption: Adsorption or absorption. * "`1. Split System: A system in which the heating is accomplished by means of radia tors or convectors supplemented by mechanical circulation of air (heated or un heated) from a central point. Ventilation may be provided by the same system. < Square Foot of Heating Surface {Equivalent): This term is synonymous with Equivalent Direct Radiation (EDR). ' . Stack Height: The height of a gravity convector between the bottom of the heat ing unit and the top of the outlet opening.. Steam: Water in the vapor phase. Dry Saturated Steam is steam at the satura tion temperature corresponding to the pressure, and containing no water in suspen sion. Wet Saturated Steam, is steam at the saturation temperature corresponding to the pressure, and containing water particles in suspension. Superheated Steam is steam at a temperature higher than the saturation temperature corresponding to the pressure. . . .... Steam Heating System: A heating system in which heat is transferred from the boiler or other source of heat to the heating units by means of steam at, above, or below atmospheric pressure. . . Steam Trap: A device for allowing the passage of condensate, or air and con densate, and preventing the passage of steam. Supply Mains: The pipes through which the heating medium flows from the boiler or source of supply to the run-outs and risers'leading to the heating units. . Surface, Heating: The exterior surface of a heating unit. Extended heating sur face (or extended surface): Heating surface consisting of fins, pins or ribs which re ceive heat by conduction from the prime surface. Prime Surface: Heating surface having the heating medium on one side and air (or extended surface) on the other. (See also Boiler Heating Surface.) ' Terminology Temperature: The thermal state of matter with reference to its tendency to com municate heat to matter in contact with it. If no heat flows upon contact, there is noTdeifmfepreenracteurien, tAembspoelruatteu:reT.emperature expressed in degree. s above absolute zero. Temperature, Dew-Point: The temperature at which the condensation of water vapor in a space begins for a given state of humidity and pressure as the temperature of the vapor is reduced. The temperature corresponding to saturation (100 percent relative humidity) for a given absolute humidity at constant pressure. Temperature, Dry-Bulb: The temperature of a gas or mixture of gases indicated by an accurate thermometer after correction for radiation. Temperature, Effective: An arbitrary index which combines into & single value the effect of temperature, humidity, and air movement on the sensation of warmth or cold felt by the human body. Tne numerical value is that of the temperature of still, saturated air which would induce an identical sensation. . Temperature, Mean' Radiant (MRT): The temperature of a uniform black en closure in which a solid body or occupant would exchange the same amount of radi . ant heat as in the existing nonuniforin environment. . Temperature Scales. Three temperature scales, Centigrade, Fahrenheit, and Reaumur, derive their degree values by dividing the difference between the ice point and steam points of water as follows: Centigrade 100, Fahrenheit 180, and Reaumur 80. Only tne first two are important in the United States. The value of a Fahren heTithdeegKreeelviisnthscearelef,osreom5/e9timofeas CcaelnletdigCraednetidgeragdreee.absolute, has its zero point at the lowest attainable temperature 273.16 Centigrade degrees below the triple-point temperature of water and exactly 273.15 below the zero of the Centigrade scale. The Rankine scale, sometimes called Fahrenheit absolute, hiss its zero at the lowest attainable temperature 459.688 Fahrenheit degrees below the triple-point temperature of water and exactly 459.67 F deg below the zero of the Fahrenheit scale. To convert Centigrade to Kelvin temperature (generally designated K) add 273.15 degT.o convert Fahrenh. eit to Rankine temperature (generally designated R) add 459T.6e7mdpeegr.ature, Wet-Bulb: Thermodynamic wet-bulb temperature is the tempera ture at which liquid or solid water, by evaporating into air, can bring the air to satu ration adiabatically at the same temperature. Wet-bulb temperature (without qualification) is the temperature indicated by a wet-bulb psychrometer constructed and used according to specifications. (ASME Power Test Codes, Series 1932, In- stnzments and Apparatus, Part 18.) .' Therm: A quantity of heat equivalent to 100,000 Btu. Thermodynamics, Laws of: Two.lawB upon which rest the classical theory of thermodynamics. These laws have been stated in many different, but equivalent. ways. The First Law: (1) When work is expended in generating heat, the quantity of heat produced is proportional to the work expended; and conversely, when beat is employed in the performance of work, the quantity of heat which disappears is pro- portional to the work done. (Joule)* (G.P.)*>; (2) If a system is caused to change from an initial state to & final state by adiabatic means only, tire work done is the same for all adiabatic paths connecting the two states. (Zemansky); (3) In any power cycle or refrigeration cycle the net heat'absorbed by the working substance is exactly equal to tbe net work done. The Second Law: (1) It is impossible Tor a self acting machine, unaided by any external agency, to convey heat from a body of lower to one of higher temperature. (Clausius) (G.P.); (2), It is impossible to derive mechanical work from beat, taken from a body unless there is available a body of lower temperature into which the residue not so used may be discharged (Kelvin) (G.P.); (3) It is impossible to construct an engine that, operating in a cycle, will pro duce no effect other than the extraction of heat from a reservoir and the performance of an equivalent amount of work (Zemansky). -. Thermostat: An instrument which responds to changes in temperature, and which dirTercatlnysomrititnadnicree,cTtlyhecromnatrlo:lsThteemtpimereatruartee.of heat flow, from. the fluid oh the warm ride to the fluid on the cold side, per (square foot) (degree temperature difference be- tween the two fluids). Sometimes called Overall Coefficient of Beat Transfer, Common unit is Btu per (hour) (square foot) (Fahrenheit degree). Symbol U. 10 CHAPTER 1 1956 Guide Two-Pipe System (Steam or Water): A heating system in which one pipe is used for the supply of the heating medium to the heating unit, and another for the return of the heating medium to the source of heat supply. The essential feature of a twopipe system is that each heating unit receives a direct supply of the heating medium, which medium cannot have served a preceding heating unit. Up-Feed System:. A heating system in which the supply mains are below the level- of the.heating units which they serve. . . .. ' . - Vacuum Heating System: A two-pipe steam heating system equipped with the' necessary accessory apparatus which will permit operating the system below atmos pheric pressure when desired. . . . Vane Ratio: In air distributing devices the ratio of depth of vane to shortest open ing width between two adjacent grille bars. . . Vapor: The gaseous form of substances which are normally in the solid or liquid state, and which can be changed to these states either by increasing the pressure or- decreasing the temperature. - Vapors diffuse.' (A5A definition.) .. Vapor Heating System ; A steam heating system which operates under pressures' at or near atmospheric and which returns the condensate to* the boiler or receiver by gravity. Vapor systems have thermostatic traps or other means of. resistance on the return ends or the heating units for preventing steam from entering the return mains;! they also have a pressure-equalising and air-eliminating device at-the end of the dry-; return. . '. i . ` . ' Velocity: A vector quantity which denotes at once the time rate and the direction- of a linear motion. V = tat:* For uniform linear motion V -- ~f Common units'. are: feet per second. * Ventilation: The process of supplying or removing air,by natural or mechanical means, to or from any space. Such air may or may not have been conditioned. (See} Air Conditioning.) *. *' Viscosity: That property of semi-fluids, fluids and gases by virtue of which they: resist an instantaneous change'of shape'or arrangement of parts. It is the cause of fluid friction whenever adjacent layers of fluid move with relation to each other..,- The coefficient of viscosity is the resistance offered by a layer of the fluid of unit area to the motion parallel to this area of another layer of the fluid at unit distance: moving with unit velocity relative to the first.layer. This coefficient is known as: the absolute viscosity, and in cgs units is the.force in dynes per square centimeter at; a velocity of 1 cm per second at a distance of 1 cm.; Tms unit of absolute viscosity-is the poise. Values of absolute viscosity are frequently listed in centipoises, a centi-. poise being 1/100 of 1 poise. .. . .. ' In many formulas absolute viscosity is expressed in pounds per .foot second or pounds per foot hour. Conversion from centipoises may. be made as follows: visr cosity in centipoises X 0.000672 = viscosity in pounds per foot second, or viscosity in centipoises X 2.42 * viscosity in pounds per foot hour. : . Kinematic viscosity is the ratio of absolute viscosity to the density of a fluid. The unit is the stoke which equals one poise per cu cm per gram , or 1 sq cm per sec. For conversion to English units: kinematic viscosity in stokes X 0.001076 = kinematic viscosity in square feet per second. * ' . . .' Volume, Specific: The volume of a substance per unit mass; the reciprocal of. density. Units: cubic feet per pound, cubic centimeters per gram, etc. Warm Air Heating System: A warm air heating plant consists of a heating unit' (fuel-burning fuinace) enclosed in a casing, from which the heated air is distributed, to various rooms of the building .through ducts. ' . Warm Air Heating System, Forced: A warm air heatine system in which circular, tion of air. is effected by a fan. Such a system may include air cleaning devices. Warm Air Heating'System, Gravity; A warm air heating system in which the mo- ` tive head producing flow depends on the difference in weight between the heated-1 air leaving the casing and the cooler air entering the bottom of the casing. * Warm Air Heating System, Perimeter: A warm air heating system of the combi nation panel and convection.type.' Warm air ducts embedded in the concrete slab of a basementless house, around the perimeter, receive heated air from a furnace and-, deliver it to the heated space through-registers placed in or: near the floor. Air is returned to the furnace from registers near the ceiling.' . . CHAPTER 2 ABBREVIATIONS, SYMBOLS, CONVERSION FACTORS Standard Abbreviations; Standard Symbols; Greek Alphabet; Conversion Equations; . Graphical Symbols for Piping, Ductwork, Heating and Ventilating, Refrigerating; Identification of Piping by Color THIS chapter contains information regarding abbreviations, symbols, and conversion equations, which are of particular interest to the engi neer engaged in heating, ventilating, and air conditioning. ABBREVIATIONS Abbreviations are shortened forms of names and expressions employed in texts and tabulations, and should not generally be used as symbols in equations. Most of the following abbreviations have been compiled from a list of approved standards.1 In general, the period has been omitted in all abbreviations, except .where the omission, results in the formation of an English word. Additional abbreviations applying to individual chapters will be found at the end of Chapters 3, 4, 13, 32, and 47. Absolute...................................................................................... .................................................abs Air horsepower........................................................................................................................ air hp Alternating-current (as adjective)........................................ ..................... ............ a-c Ampere.................................... ........................... :.......................................................................amp Ampere-hour........................................................................... ;.................................. .. amp-hr Atmosphere.. Average........ Avoirdupois.. Barometer-- Boiling point. .. atin avg avdp . bar. ...bp Brake horsepower...................................................................... !....................;...:.............. .bhp Brake horsepower-hour.................... bhp-hr British thermal unit..................................................... mu British thermal units per hour................................................................... Btuh Calorie........................................................... cal Centigram................................ ..................................................... ............................v................,cg Centimeter....................................................................................................... .......................... cm Centimeter-gram-second (system)........................................ ............... ............. ............ cgs Cubic......... :................................................................................. ................................................ .cii Cubic centimeter...................................... ....................................... ........................ .cu cm or cc Cubic foot.................................................................................... ............................................cu ft Cubic feet per minute.................................................... ......................................................... cfm Cubic feet per second......... ........................................................................................................ cfs Decibel........... ..................................................................................................... db Degree*..................................................................................................................... ............ deg or Degree, Centigrade................................................................. ..:.................................................. C Degree, Fahrenheit............................................................................... ......... ;........................... F Degree, Kelvin................................................... ....................... "................................................... K Degree, Rankine.............................. ........... ................................................................ ............ .R Diameter........................... diam 1 Abbreviations for Scientific and Engineering Terms, Z10.1-1941 (American Standard* Association). * It is recommended that the abbreviation for the temperature scale, F. C, K, R, be included in expres sions for numerical temperatures but, wherever feasible, the abbreviation for degree be omitted eg-. 68 F. 11 12 CHAPTER 2 1956 Guide Direct-current (as adjective) Electromotive Force............... Feet per minute....................... Feet per second.............. ... Foot........................... .d-c emf fpm .fps ..ft Foot-pound................................ Foot-pound-second (system) Freezing point......................... ' Gallon.................... .................... Gallons per minute.......... ftJb . .fps .gpm Gallons per second...................................................................................................................... gps Gram........ ................. e Gram-calorie........................ .................................................................................................... g-cad Horsepower................... hp Horsepower-hour.......................................... hp-hr , Hour........... ............................................................................... hr Inch....................................... ;........... ................................................................... ............... .... .in. Inch-pound.............................. in.Jb Indicated, horsepower............................. ............,,.................................................................... ihp ' Indicated horsepower-hour......... .................... ihp-hr Kilogram...;. Kilowatt.......... Kilowatt-hour. Mass.................. Melting point. ....kg .. .kw jkwhr .mass ... .mp. Meter.................................................................................... m Micron................................................................................................................................ ... .p (mu) Miles per hour............... aiph Millimeter..................................... mm Minute........................................................................................................................... min ' Molecular weight........... Mol;....................... ........... Ounce................................. Pound.......................... ....... Pounds per square inch. mol wt ___ mol ' ........ oz ........ lb .... psi Pounds per square inch, gage........ Pounds per square inch, absolute. Revolutions per minute.................... Revolutions per second.................... Second.................................................... .psig .psia rpm . . .rps . .sec Specific gravity................................................................................... .....;........................... ap gr Specific neat............................. 1..................:........................................................................ sp nt =. Square foot.......... ............................................................................... ..................................... sq ft Square inch............................................. ;............................................................... ............... sq in. < Watt.................................................................................................................................................... w Watthour..:.......;................ ..;....................................'........................................... whr .. SYMBOLS . ' A letter symbol is a single character, with subscript or superscript if required, used to designate a physical magnitude in mathematical equa tions and expressions. Two or. more symbols together always represent a product. The following have been compiled from a selected list of approved standards.* Additional symbols and variations in the standard symbols , * letter Symbols (or Mechanics ol Solid Bodies, ZlO.3-1948, andLotter Symbols (or Heat and Thermo- dynanucs, Zl0.4-lM3'Cimeriean Standard* Association): ' .. Abbreviations, Symbols, Conversion Factors 13 found necessary in the individual chapters will be found in a list at the end of Chapters 3,4,13; 32, and 47. Acceleration, due to gravity...................................................................................... ..................................................9 Acceleration, linear............................................................. ....................................................................... ............a Change in specific voiume during vaporization........................................................ Density* Weight per unit volume, Specific weight....................................... .d or p (rho) Distance, linear............................................................................................................................... Dry saturated vapor, Dry saturated gas at saturation pressure and temperature, vapor in contact with liquid............................................................................ Subscript g Efficiency............................................................................. % Elevation above some datum.................................................................................................z, Z Emissivity............................................................. jj Energy in general; work, total; work, molal......................................................................... E Entropy. (The capital should be used for any weight, and the small letter for unit weight).....................................................................................................................S or s Force, total load.............................................................................................................................. F Gas Constant, in equation pV = nRT....................................................................... .... .R Head......................................:..........*......................... ,....<.......................:........................H or A Heat content, Total heat, Enthalpy. (The capital should Be used for any weight and the small letter for unit weight)................................ .....................H or A Heat content of saturated liquid, Total heat of saturated liquid, Enthalpy of saturated liquid, sometimes called heat of the liquid. ................................. ........At Heat content of dry saturated vapor, Total heat of dry saturated vapor, En- . thalpy of .dry saturated vapor...........................................................................................A* Heat of vaporization at constant pressure-........ .......................... .Lor At* Hydraulic radius...................................... i........................................................................:------ An Internal energy, Intrinsic energy. .(The capital should be used for any weight and the small letter for unit weight).....................................................................U oru Length of path of heat flow, thickness..................................... ............................................ L Load, total.............................................................. ........................................................................W Mechanical efficiency................................................... ................................................................ Mechanical equivalent of heat......... ............... ..................<.................................................. .J Power, Horsepower, Work per unit'time............................... ................... ............... -F Pressure,'Absolute pressure, Gage pressure, Force per unit area.............'................p Quantity (total) of fluid, water, gas, heat; Quantity by volume; Total1 quantity ; of beat transferred...........................'......................... ........................ ....... r................. yQ Quality of steam, Pounds of dry steam per pound of mixture....... ....._..................--s Saturated liquid at saturation pressure and temperature, Liquid in contact with vapor............ ...................................... ...................... .............................................Subscript f Specific heat.................. --.......... .................................................... . c Specific heat at constant pressure............... . ...... ^ . V. v - -Cp Specific heat at constant volume.;................ ;......... .................... Specific volume, Volume per unit weight, Volume per unit mass.......... ;................. Temperature (ordinary) F or C. (TAeto is used preferably only when t is used ' for Time in the same discussion)......................... ......................................< or 6 (theta) Temperature (absolute) F abs or K. {Capital theta is used preferably only when small theta is used for ordinary temperature)......................... T or 0 (capital theta) Thermal conductance:4 heat transferred per (unit time) (degree)..1.'......................... C .. c= I,,M,, g - t "fi - tt . . * Terms ending ivity designate properties independent of'sizs or shape, sometimes called- specific proper- Examples: conductivity, resistivity. Terms ending once designate Quantities-depending-not only on tiie material, but alao -upon aise and shape, sometimes called total quantities. -Examples: conductance, transmittance. Terms ion designate rate of heat transfer. Examplea: conduction, transmission. 14 CHAPTER 2 1956 Guide 1!| Thermal conductance per unit'area, Unit conductance: heat transferred per (unit time) (unit area) (degree)................................................................. --............ r 1 _ q -,k ' A RA A((i -- (*) L Thermal conductivity: heat transferred per (unit time) (unit areaj (degree per unit length)............... '.................................... '.......................................................................^ `-sis " *L Surface coefficient of heat transfer, Film coefficient of heat transfer, Individual coefficient of heat transfer: heat transferred per (unit time) (unit area) (degree)......................................................................................................................................./ /= g A U-tt (In general / is not equal to.k/L, where L is the actual thickness of the fluid film.) Overall coefficient of heat transfer, Thermal transmittance per unit area: heat . transferred per (unit time) (unit area) (degree overall)..........................................U ' .9 Thermal transmission (heat transferred per unit time)............................. Q T * Thermal resistance (degree per unit of heat transferred per unit time) 9 R -- ** ~ k ^ q kA Thermal resistivity............... ............................... ... j............................ ...................V* Vaporization values at constant pressure, DifferericesTbetween values for satu rated vapor and saturated liquid at the same pressure.......................Subscript fg Velocity......................... ..............................................................'.................................................... V Viscosity, absolute......... ...:....................... ..........................................................................-- m Viscosity, kinematic____ ......................................................................................... ..p/p Volume (total)................. i.................................... ........................ ;............................... ........... V. Volume per unit time,' Rate at which quantity of material passes through a machine, Quantity of heat per unit time, Quantity of heat per unit weight... Weight of a major item, Total weight................. ...................... ............................ ............ Weight rate, Weight per unit of power, Weight per unit of time................................. Work (total).......................... ..........;........... ........... ......................... ....................................... THE GREEK ALPHABET A a Alpha B/3 Beta r-r Gamma A S Delta E< Epsilon Zf Zeta H, Eta ` e&e Theta I i Iota K k Kappa A X Lambda M ii Mu N v Nu EJ Xi O o Omicron Hit Pi P p Rho , 2 a i Sigma T t Tau T u Upsilon $ <p <f> Phi X X Chi . 9.#. Psi . . Qa> Omega . . Abbreviations, Symbols, Conversion Factors 15 CONVERSION EQUATIONS6 Heat, Power and Work 1 ton refrigeration Latent heat of ice 1 Btu 1 Int. watthour 1 Int. kilowatthour 1 Int. kilowatt (1000 watts) 1000 I.T. calories! 1 I.T. Kilocalorie/ 1 horsepower 1 boiler horsepower Weight and Volume 1 gal (U. S.) 1 British or Imperial gallon 1 cu ft - 1 cu ft water at 60 F(in vacuo) 1 cu ft water at 212 F (" " ) 1 gal water at 60 F (" " ) 1 gal water at 212 F (" " ) 1 lb (avdp) 1 bushel 1 short ton Pressure 1 lb per square inch 1 oz per square inch f 12,000 Btu per hour \ 200 Btu per minute 143.4 Btu.per pound 778.3 ft-lb 0.2930 Int. whr . 252.0 I.T. calorie . [ 2656 ft-lb 3.413 Btu ] 3600 Int. joules [ 860 I.T. calories f 3,413 Btu | 3.517 lb water evaporated from { and at 212 F f 1.341 hp \ 56.88 Btu per minute [ 44,267 ft-lb per minute [ 3.968 Btu { 3088 ft-lb [ 1.1628 Int. whr 0.7455 Int. kw 42.40 Btu per minute 33.000 ft-lb per minute 550 ft-lb per second . / 33,475 Btu per hour \ 9.809 Int. kw . / 231 cu in. \ 0.1337 cii ft 277.42 cu in. / 7.481 gal \ 1728 cu in. 62.37 lb 59.83 lb 8.338 lb 7.998 lb f 16 oz \ 7000 grains 1.244 cu ft 2000 1b 144 lb per square foot 2.0360 m. mercury at 32 F 2.0422 in. mercury, at .62 F 2.309 ft water at 62 F 27.71 in. water at 62 F 0.1276 in. mercury at 62 F 1.732 in. water at 62 F '.Cheeked in 1944 by Natumal Bureau of Standard*. ' Abbreviations InL and I.T. refer to International and international (Steam) Table, fopectively. 16 CHAPTER 2 1956 Guide 1 atmosphere 14.696 lb per square inch 2116 lb per square foot 33.94 ft water at 62 F 30.01 in. mercury at 62 F ( 29.921 in. mercury at 32 F 1 in. water at 62 F (in vacuo) ( 0.03609 lb per square inch j 0.5774 os per square inch ( 5.197 lb per square foot 1 ft. water at 62 F (in vacuo) / 0.4330 lb per square inch \.62.37 lb per square foot 1 in. mercury at 62 F (in vacuo) 0.4897 lb per square inch 7.835 oz per square inch 1.131 ft water at 62 F 13.57 in. water at 62 F 1 in. mercury at 32 F (in vacuo) 0.49115 lb per square inch Metric Units 1 cm 1 in. 1m 1 ft 1 sq cm 1 sq in. 1 sq m 1 sq ft 1 cu cm 1 cu ra. 1 cum 1 cu ft 1 liter 1 kg 1 lb 1 metric ton 1 gram 1. kilometer per hour 1 gram per square centimeter 0.3937 in. * 0.0328 ft 2.540 cm 3.281 ft 0.3048 m 0.1550 sq in. 6.452 sq cm 10.76 sq ft 0.09290 sq m 0.06102 cu in. 16.39 cu cm 35.31 cu ft 0.02832 cu m 1000 cu cm = 0.2642 gal 2.205 lb (avdp) 0.4536 kg 2205 lb (avdp) 0.002205 lb (avdp) 0.6214 mph / 0.02905 in. mercury at 62 F \ 0.3942 in. water at 62 F 1 kg per sq cm (metric atmosphere) = 14.22 lb per square inch 1 gram per cubic centimeter f 0.03613 lb per cubic inch \ 62.43 lb per cubic foot 1 dyne 1 absolute joule -- 0.00007233 poundals 10,000,000 ergs 0.7376 ft-lb 1 Int. joule ` . 1 metric horsepower 0.7378 ft-lb / 75 kg-m per second. " \ 0.986 hp (U. S.) 1 I.T. kilocalorie per kilogram. 1 I.T. calorie per square centimeter =1.8 Btu per pound ` * 3.687 Btu per square foot 1 I.T. calorie per (second) (square centi- ' ( 2903 BTU per (hour) (square fooO meter) for. a temperature gradient,of 1 C = j for a temperature gradient of 1 F deg per centimeter .* deg per inch of thickness. Abbreviations, Symbols, Conversion Factors: 17 GRAPHICAL SYMBOLS FOR DRAWINGS* Graphical Symbols for Drawings Piping Heating .. 1. High Pressure Steam............... - 2. Medium Pressure Steam 3. Low Pressure Steam 4. High Pressure Return 5. Medium Pressure Return 6. Low Pressure Return 7. Boiler Blow Off 8. Condensate or Vacuum Pump Discharge 9. Feedwater Pump Discharge - 10. Make-Up Water 11. Air Relief Line 12. Fuel Oil Flow ! 13. Fuel Oil Return 14. Fuel Oil Tank Vent 15. Compressed Air . 16. Hot Water Heating Supply . 17: Hot Water Heating Return . --#>-- * *h *-------- *------*-- ---------- :------------ -- .-- -- --o o! --oa----oo- --^-------------- -- __ ___ -J--;--------fo'f- ------------ fob- --------- ---fov" ~ a-- ' . --------------- -- -- Aib Conditioning 18. Refrigerant Discharge 19. Refrigerant Suction 20. Condenser Water Flow 21. Condenser Water Return 22. Circulating Chilled or Hot Water Flow 23. Circulating Chilled or Hot Water Return 24. Make-Up Water 25. Humidification Line 26. Drain 27. Brine Supply - 28. Brine Return . 'RD R5-C- CH-------------------- Plumbing . 29. Soil, Waste or Leader (Above Grade) 30. Soil, Waste or Leader (Below Grade) 31. Vent 32. Cold Water 33. Hot Water 34. Hot Water Return ' . 35. Fire Line 36. Gas 37. Acid Waste 38. Drinking Water Flow , 39. Drinking Water Return . . 40. Vacuum Cleaning 41. Compressed Air . . _________ ____ _____ ________ ; " -_________ 1--------- ----------- . ________ :__ __ -r . - c_________ acid . - -. ` .v_________ . ^ Sprinklers 42. Main Supplies . 43. Branch and Head 44. Drain Extracted fnftn : American Standard Graphical Symbols for Pipe Fittings, Valves, and Piping . Z33.2.3-1EK9) and Atnar,<ffr> -Rfn/4n.rd Grapbiiad Symbols for Heating. Ventilating, and Air Conditioning (ASA Z32^.4-ld49) with the pennission of the publisker. The American Society of Mechanical Engineer*, West 39th St.. New York IAN. Y. 18 CHAPTER 2 Graphical Symbols for Drawings' : : = 1956 Guide Heating 1. Air Eliminator 2. Anchor 3. Expansion Joint 4. Hanger or Support 5. Heat Exchanger 6. Heat Transfer Surface, Plan (Indicate Type Such as Convector) 7. Pump (Indicate Type Such as Vacuum) 8. Strainer 9. Tank (Designate Type) 10. Thermometer 11. Thermostat 12. Traps 12.1 Boiler Return -*r 6 6- = - 0-n REC JL -Cfl=h 12.2 Blast Thermostatic 12.3 Float 12.4 Float and Thermostatic 12.5 Thermostatic 13. Unit Heater (Centrifugal Fan), Plan -s- -Hghfa--dj--tr 14. Unit Heater (Propeller), Plan 15. Unit Ventilator, Plan' * " ' ` Abbreviations, Symbols, Conversion Factors Graphical Symbols for Drawings 16. Valves 16.1 Check 16.2 Diaphragm 16.3 Gate 16.4 Globe 16.5 Lock and Shield 16.6 Motor Operated - 16.7 Reducing Pressure 19 Heating A- ixh 16.8 Relief (Either Pressure or Vacuum) 17. Vent Point . <S> -VENT Graphical Symbols for Drawings 18. Access Door 19. Adjustable Blank Off 20. Adjustable Plaque Ventilating r................... :-:_3 - t---- AD TR 20X12 . . |p-20xi2-7oocrm \ rT f EES 3.'7LTZ7T 700 cf m 21. Automatic Dampers 22. Canvas Connections 20 CHAPTER 2 Graphical Symbols for Drawings 1956 Guide Ventilating 23. Deflecting Damper 24. Direction of Flow 25. Duct (1st Figure, Side Shown; 2nd Side not Shown) 26. Duct Section (Exhaust or Return) 27. Duct Section (Supply) 28. Exhaust Inlet Ceiling (Indicate Type) 29. Exhaust Inlet Wall (Indicate Type) lXl-(E OR R 20X12) 1X3----------- (S 20 X 12) CR 20 X 12 - 700 cf m CG 20 X 12, " 700 C^"TT1 TR-I2X* 7oocy?m 30. Fan and Motor With Belt Guard 31. Inclined Drop in Respect to Air Flow 32. Inclined Rise in Respect to Air Flow 33. Intake Louvers on Screen 34. Louver Opening 35. Supply Outlet Ceiling (Indicate Type) j L 20)^12-700 C^m C^) 2o* oiam: iooo cfm 36. Supply Outlet Wall (Indicate Type) 37. Vanes D- TR - 12X8 700 .c^m llpjf 38. Volume Damper. 'J_ A.' Abbreviations, Symbols, Conversion Factors 21 Graphical Symbols for Drawings 39. Capillary Tube VW\Af" 40. Compressor 5 41. Compressor, Enclosed, Crankcase, Ro tary, Belted 42. Compressor, Open Crank case, Recipro cating, Belted 43. Compressor, Open Crank case, Recipro cating, Direct Drive' 44. Condenser, Air -- 11 Mfi A Cooled, Finned, M-l-ft ti A\J Forced Air - I i II l1 Air Conditioning 57. Evaporator Mani folded, Finned, Gravity Air 58. Evaporator, Plate Coils, Headered or Manifold 59. Filter, Line 60. Filter A Strainer; Line 61. Finned Tyne Cool ing Unit, Natural Convection 62. Forced Convec tion Cooling Unit 63. Gage OoIoOIoO ololo < ::::: *U s. 64.. High Side Float 47. Condenser, i Water Cooled, -- Shell and Coil 48. Condenser, I Water Cooled,--1 Shell and Tube " 49. Condensing Unit, Air Cooled SI50. Condensing Unit, Water Cooled *7^ |j ,J ^ 6- 51. Cooling Tower 52. Dryer 53. Evaporative Condenser 54. Evaporator, Circular, Ceil ing Type, Finned 55. Evaporator, Manifolded, Bare Tube, Gravity Air 56. Evaporator Manifolded, Finned, Forced Air :. 65. Immersion Cool ing Unit 66. Low Side Float 67. Motor-Compres sor, Enclosed Crankcase, - Reciprocating, Direct Connected &s> 68. Motor-Compres sor, Enclosed - Crankcase,. : . Rotary, Direct Connected -6 69. Motor-Compres sor, Sealed Crank- . case, Recipro' .eating 70. Motor-Compres sor, Sealed Crank- ` case, Rotary 71. Pressurestat --V\Ar-(p)--W\r-- 72. Pressure Switch 73. Pressure Switch .. With High ' Pressure Cut-Out . 74. Receiver, ' Horizontal 75. -Receiver, Vertical -dH> t=s 6- 22 CHAPTER 2 1956 Guide 76. Scale Trap 77. Spray Pond 78. Thermal Bulb 79. Thermostat (Remote Bulb) .... 80. Valves 80.1 Automatic Expan sion ' 80.2 Compressor Suction Pressure Limiting, Throttling Type (Compressor Side) 80.3 Constant Pressure, Suction. 80.4 Evaporator Pressure Regulating, Snap Action 80.5 Evaporator Pressure Regulating, Thermo static Throttling Type -Q- priri, !r; 80.6 Evaporator Pressure Regulating, Throt tling Type (Evapo rator Side) 80.7 Hand Expansion 80.8 Magnetic Stop -dP1' & 80.9 Snap Action -r 80.10 Suction Vapor Regulating 80.11 Thermo Suction 80.12 Thermostatic Ex pansion - 80.13 Water 81. Vibration Absorber, Line IDENTIFICATION OF PIPING SYSTEMS BY COLOR The color scheme for identification of piping systems, based on material carried, as listed in the following table and shown in Fig. 1, is reprinted from Part V, Fourth Edition, of the Engineering Standards of the Heal ing, Piping and Air Conditioning Contractors National Association.7 . Class Color F--Fire-protection Red - D--Dangerous materials S--Safe Materials and, when required Yellow or Orange Green (or the achromatic colors, white, black,, gray or aluminum) . P--Protective materials Bright blue . V--Extra valuable materials Deep purple t gee . Fio. L.Main Classification by Color for Identification of Piping Systems, A13-192S, American Standard* Association CHAPTER 3 THERMODYNAMICS Mass and Energy Balances; Thermodynamic Properties of Moist Air; Formulas and Tables; Thermodynamic Properties of Water, Formulas and Tables; Degree of Saturation; A.S.H.V.E. Psychrometric Chart; Solution of Air Conditioning Problems by Use of Tables and Psychrometric Chart; U. S. Standard Atmosphere THERMODYNAMICS is that branch of natural science which deals with energy and its transformations into various forms. In this chap ter the discussion will be limited to thermodynamics as it affects the arts of heating and air conditioning. This will' necessarily presume some knowledge of the fundamentals of the science on the part of the reader who may also find it desirable to refer to a standard text on the subject, preferably one published after 1930. . MASS AND ENERGY BALANCES The First Law of Thermodynamics is a statement of the Principle of Conservation.of Energy. ' It may be stated as follows: The energy added to a system is equal to the increase or decrease of the energy stored in the system, plus the energy which leaves the system. For a completely contained, or non-flow system, this may be restated as: The heat added to a non-flow system is equal to the change in the internal energy of the system, plus the work done by the system. iqi *> U, - Ui + w (l) For a constant pressure process : - ;Qi = Hi -- H, . (2) where . iqj = energy added between points 1 and 2. U = internal energy of system. w = work done by'system..-.. . ... H:= enthalpy .of system.' .. ' Subscripts 1 and 2 refer to sections of the system between which a change take, place. .... ' For engineering problems, a more important application of the First Law is its use in cases in which, in addition to energy, one or more fluids are crossing the boundaries of the system. The most simple of these is the steady flow system, in which the rates of energy and mass flow across the boundaries of the system are constant, and no mass or energy is stored or released by the system. . Consider a system as illustrated in Fig! 1. The fluid crossing the boundaries of the system carries with it potential energy by reason of its elevation above some convenient datum, kinetic energy by reason of its 23 24 CHAPTER 3 1956 Guide velocity, and energy in the form of enthalpy. Additional energy may cross the boundaries of the system in the forms of heat or work. The various forms of energy crossing the boundaries between the sections under consideration may be equated by applying the First Law of Thermody namics: + + , +PEI KEi + H, + i{> = PEt + KEt H w (3) where ' . PE = potential energy, Btu per pound dry air. KE = kinetic energy, Btu per pound dry air. . H = enthalpy, Btu per pound dry air. iqt = heat added between sections 1 and 2, Btu per pound dry air. w = shaft work withdrawn between sections 1 and 2, Btu per pound of dry air. v, hT 9 TwoFig. 1. Energy Change between Sections op a System For most psychrometric problems, since , the change , in the potential energy and kinetic energy terms is negligible compared to the enthalpy change, Equation 3 may be simplified to Hi + ns -- Et + w (4) where .. ", H = enthalpy of the flowing medium, Btu per pound of dry air. The enthalpy of the entire system may be broken down into constituent parts, thus: :. - GB ~ Gh + + SA,,, (5) where : 1. . A'-- enthalpy ot moist s.it, Btu per pound of dry air. Awi -- enthalpy of liquid water, Btu per pound. An = enthalpy of solid water, Btu per pound. , L = flow rate, of liquid water, pounds per hour. . S = flow rate of solid water,.pounds per hour. . G = flow rate of dry air, pounds per hour. : . Thermodynamics 25 Similarly,: an equation expressing1 the conservation of mass may be written thus: 1 : [Gd + W0 + A + S] = E (<7(1 + W) + L + S] in oat (0) where W = humidity ratio, pounds of water vapor per pound of dry air. THERMODYNAMIC PROPERTIES OF MOIST AIR The working substance of the air conditioning engineer is moist air. Air is actually a mixture of oxygen, nitrogen, carbon dioxide, water vapor, and traces of other gases. The mixture consisting of the components other than water vapor is known as dry air. Its composition remains essentially constant under all conditions. In moist air the amount of water vapor varies considerably. To allow for this variation the specific properties of moist air are developed in terms of the relative amounts of water vapor and dry air. Accepted air conditioning practice is to express this in terms of the amount of water vapor per pound of dry air. .' . Terms frequently used in describing the condition of a mixture of air and water vapor are humidity ratio, relative humidity, degree of saturation, dryAnJh temperature, thermodynamic wetibulb temperature, and dew-point temperature. These terms are defined in following paragraphs. Humidity Ratio. Weight of water vapor associated with unit'weight of dry air, pounds of water vapor per pound of dry. air. Humidity ratio has also been called specific humidity, and;this term is still used in many places. Relative Humidity. Ratio of the mol fraction of water vapor in the actual mixture to the mol fraction of water vapor in saturated air at the same dry-bulb temperature and barometric pressure. Degree of Saturation. Ratio of the actual humidity ratio to the humid ity ratio of saturated air at the same diy-bulb temperature and barometric pressure. " Relative humidity and degree of saturation are.related according to the identity: - 1' 1 ' ;' (7) where <t> " relative humidity, expressed as a decimal. n 19 degree of saturation, expressed as a decimal. . . Pa -- observed (or barometric) pressure of the moist air. P, = saturation pressure of pure water at the prevailing temperature, expressed in the same units as '' / aD a dimensionless factor which may be regarded as accounting for influences arising when air and water are intermixed. Magnitudes of / have been reported by Goff and Gratch1 and by Goff.1 Table 1 gives values of / for a limited range of conditions. 26 CHAPTER 3 1956 Guide Dry-Bulb Temperature. The temperature indicated by any type of thermometer or thermocouple not affected by the water vapor content of the air, or by radiation. . . Thermodynamic Wet-Bulb Temperature. The temperature at which liquid or solid water, by evaporating into air, can bring the air to satura tion adiabatically at the same temperature. Consider an adiabatic system as shown in Fig. 2. Unsaturated air at the state h,, Wi, enters the system at section 1, and saturated air at the. state h*, W*, leaves the system at section 2. Liquid water at the state A.*, corresponding to the temperature of the saturated air leaving the system is supplied. Then, since no work is done and the system is strictly adiabatic, the energy equation becomes . . fc. + (W - JFi)A,,* = fc* where . .. . . . indicates condition at thermodynamic wet-bulb temperature. (8) Table 1. Magnitudes or /. 0fob the Range to 125 F (Standard Barometric Pressure, 29.921 in. Hg) Temp. F fa Temp. F fa 0 1.0048 70 . 1.0045 10 1.0046 . . 80 1.0047 20 1.0046 90 1.0048 30 1.0045 100 1.0050 40 1.0044 110 1.0053 50 . 1.0044 120 1.0055 . 60 1.0044 125 1.0057 NoU: The original source1 gives /* to seven significant figures over the temperature range --203 F to + 202 F and over the pressure range 20 to 35 in. Hg. . The temperature corresponding to A* for given values of A, and Wx is called the thermodynamic wet-bulb temperature, or the temperature of adiabatic saturation. ,. The temperature indicated by an ordinary wet-bulb thermometer is affected by a number of factors not accounted for in Equation 8, and hence, may be quite different from the theoretical temperature obtained from its use. The measured wet-bulb temperature is influenced by (a) radia tion from the surroundings to the wick; (6) conduction of heat along the stem of the thermometer; and (c) impact of the air on the wick or bulb of the thermometer. Arnold1 has developed a theory which makes pos sible the calculation of the true thermodynamic wet-bulb temperature from observed data through the use of suitable corrections to be applied to the readings of the wet-bulb thermometer. However, unless extreme precision is required, the observed temperature may be taken equal to the theoretical temperature for most engineering problems, if no attempt is made to shield the wick from radiation and the air velocity past- the. wick is about 1000 fpm. ` Dew-Point Temperature. The saturation temperature corresponding to a given combination of humidity ratio IT and barometric pressure is called the dew-point temperature, It is the lowest temperature at which the Thermodynamics 27 given humidity ratio can exist at the corresponding barometric pressure. At this temperature condensation will first start to form when moist air-is cooled. Perfect Gas Relationships Hypotheses, based on experimental observation of the physical behavior of gases, which were advanced by Boyle, Charles, Gay-Lussac, Dalton, Gibbs, Joule, Kelvin and others, were reduced to reasonably simple mathe matical. expressions and came to be regarded as physical laws. However, as scientific knowledge increased, and as more precise methods of measure ment were developed, it, became apparent that these simple equations did not describe the behavior of the mixtures of actual gases and vapors ac curately. The original statements have been found to be useful tools, nevertheless, in many cases. For example, the behavior of common diatomic and tria- . <P f Fig. 2. Illustration of Adiabatic Satubation tomip gases at low pressures follows these equations closely enough so that they may be used for some types of engineering problems. Many useful engineering works have been constructed through the use of approxi mations. The degree of approximation, however, which may be tolerated in engineering design must be decided by the engineer, based upon his study and experience in the field. Boyle's Law. One of the original observations of the physical behavior of gases was made by Robert Boyle who noted that, if a constant weight of gas is compressed with the temperature held constant, the volume V varied inversely as-the absolute pressure P. Stated mathematically, ' PV = constant . (temperature constant) (9) . Charles' Law. Experiments made independently by Charles and GayLussac led to the formulation of what is now known as Charles' Law: If a constant weight of gas is heated or cooled at constant volume, the absolute pressure P varies as the absolute temperature T; if a constant weight of 28 CHAPTER 3 1956 Guide gas is heated or cooled at constant pressure, the volume V varies as the absolute temperature T. Stated mathematically, - p -- = constant (volume constant) ' (10) constant T (pressure constant) (ID Boyle's. Law and Charles' Law may be combined to form the equation of state for the ideal or perfect gas, PV - RT (12) where . R is a constant whose value depends on the units selected tor P, V, and T. Dalton's Rule. Dalton stated that each gas in a mixture occupies the total volume of the mixture just as though the other gases were not present. Gibbs later expanded this statement for perfect gases into the following principles: 1. The pressure of a mixture of gases is the sum of the partial pressures of the in dividual gases when they exist at the total volume and temperature of the mixture. 2. The internal energy, enthalpy, and entropy of a mixture of gases are respec tively equal to the sums of the individual internal energies, enthalpies, and entropies of the components when they exist at the total volume and temperature of. the mix ture. ' .. While these relationships do not hold exactly for all systems of real gases, they may be used with, a good degree of precision for many engineer ing applications at low pressures. Moreover, since water vapor very closely follows the perfect gas relationships in the range usually encountered in air conditioning, the Gibbs-Dalton Rule may frequently be applied to mixtures of dry air and water vapor. Thus, . Vm = P. = Pw (13) Tm = T. = T. , (14) Pm = p + pw Vlzah = ITlnht -{- tn-wh'w 1 (15) (16) where Subscript m denotes mixture; subscript a denotes dry air; subscript w denotes water vapor. . Symbol m = weight of dry air crossing any duct section, pounds per minute. Using Equations 12, 13, 14, and 15, the relation is obtained as follows: * nmRT nwRT (n. + nw)RT Vt p. p- p (17) where bt = total volume, cubic feet. = number of mpls of dry air. Thermodynamics 29 n. = number of inols' of water vapor.' ' . ; R = universal gas constant, 1545 foot-pounds per (Fahrenheit degree) (mol), p. = partial pressure of dry air. p,, = partial pressure of water vapor. T a absolute temperature, Fahrenheit degrees: The partial pressure of water vapor in the mixture is then n, Pw ft. + n. P (18) or, the partial pressure of the water vapor in moist air is equal to the product of the mol fraction of the water vapor and the observed pressure of the mixture. A similar expression is obtained for the dry air. Assuming that the perfect gas laws can be applied to water vapor at saturation at low pressures, the partial pressure of water vapor in a satu rated mixture may be written as ns P. = n* + ft. P (19) where = number of mols of water vapor at saturation. . The relative humidity may be obtained by combining Equations 18 and 19 and solving for the ratio of mol fractions. Thus, using perfect gas relationships, 11> pp. (20) The humidity ratio W may be obtained from Equation 17: 18.016 pw W = 0.622 28,966 p. (21) where 18.016 and 28.966 are. the molecular weights of water and dry air, respectively. Equation 16 may be rewritten as h = h. + Wh, (22) where h = enthalpy, Btu per pound of dry air. In relating the enthalpy to the state of the moist air, the fact that in all applications only differences in enthalpy are involved,' allows the arbitrary selection of a datum or zero enthalpy point. Accordingly, from perfect gas relationships, it is possible to write for any temperature of t, Fahrenheit' greater than OF A. = 0.24 ( . (23) where it is assumed that the same arbitrary datum of 0 F is used as in determining the properties of moist air in Table 2.- Tables of Thermodynamic Properties of Moist Air Research work conducted at the University of Pennsylvania and at other institutions has shown that the Gibbs-Dalton Rule is inaccurate in varying degrees, depending on temperature, pressure and the amount of water 30 CHAPTER 3 1956 Guide- vapor present. The probable reasons for this inaccuracy are due to the effect of:. 1. Chemical solution of gas molecules in the water vapor. 2. The finite sise of the molecules causing interference with the free passage of other molecules toward the boundaries of the system. 3. Intermolecular forces of attraction and repulsion. Many attempts have been made to develop an equation of state which would predict the true states of real gases and vapors. The Van der Waal, Maxwell, and Beattie-Bridgman equations are probably the best known. Unfortunately, these expressions rapidly become much too com plicated to be used in everyday calculations and, therefore, engineers find it more convenient to use tables of thermodynamic properties for specific working substances, as these can be prepared by physicists using the best laboratory equipment and all the refinements of mathematics. . Mechanical engineers have long been familiar with such tables for the properties of steam. ' Tables of the properties of moist air, as prepared by Goodenough and others, have been available for some time, but the latest and most precise of such tables are those which have resulted from a co operative research agreement between the American Society op Heating and Aik-Conditioning Engineers and the Tawne Scientific School of the University of Pennsylvania. These properties -are published herein as Table 2, and are taken from a research report by Goff and Gratch.4 Table 2, which experimentally and mathematically takes into account deviations from perfect gas behavior, such as those listed above, makes the applica tion of the Gibbs-Dalton Rule a less frequent necessity. In Table 2 there are 15 columns of figures, each column being headed by a suitable symbol. In the following sub-paragraphs brief explanations are given of the data in Table-2 under the appropriate column headings. t(F) = Fahrenheit temperature defined in terms of absolute temperature T by the relation. T = ( + 459.67- - . (24) W = humidity ratio at saturation. Saturation is the condition at which the vapor phase (moist air) may exist in equilibrium with a condensed phase (liquid or solid) at the given temperature and pressure (standard atmospheric pressure m the case of Table 2). At given values of temperature and pressure, the humidity ratio IF can have any value from zero to IF*. . -. Ok specific volume of dry sir, cubic feet per pound. ' ,. .. ska = o -- a, the difference between the volume of moist air at saturation, per pound of dry air, and the specific volume of the dry air itself, cubic feet per pound of dry air. ' Pa = specific volume of moist air at saturation per pound of dry air, cubic feet per pound of dry air. . K, = specific enthalpy of dry air, Btu per pound of dry air.' The specific enthalpy of dry air has been assigned the value zero at 0 F, standard atmospheric pressure. The energy unit Btu is related to the foot-pound by definition, as follows: 1 Btu = 778.3 ft-lb. . . .. ha, = h, -- h,, the difference between the enthalpy of moist air h< saturation, per pound of dry air, and the specific enthalpy of the dry air itself, Btu per pound of ary air. ' . h, = enthalpy of .moist air at saturation per pound of dry air, Btu per pound of dry air. Sa " specific entropy of dry air, Btu per (pound) (Fahrenheit degree). It will be .Thermodynamics . 31 noticed that the specific entropy of dry air has been assigned the value zero at 0 F and standard atmospheric pressure. iu o ia -- Sa, the difference between-the entropy of moist air at saturation, per pound of dry air, and the specific entropy of the dry air itself, Btu per (pound of ary air) (Fahrenheit degree). s< = entropy of moist air at saturation per pound of dry air, Btu per (pound of dry air) (Fahrenheit degree). A. = specific enthalpy of condensed water (liquid or solid) at standard atmospheric pressure, Btu per pound of water. The specific enthalpy of liquid water has been assigned the value zero at 32 F, saturation pressure (0.088586 psia). i. -= specific entropy of condensed water (liquid or solid) at standard atmospheric firessure, Btu per (pound of water) (Fahrenheit degree). The specific entropy of iquid water has been assigned the value zero at 32 F, saturation pressure (0.088586 psia). p, = saturation pressure of pure water vapor, pounds per square inch or inches of Hg (absolute pressure). At a given pressure, moist air can be saturated at any temperature, though this requires that it have a definite humidity ratio IF, and that the coexisting condensed phase contain a definite, but very small, quantity of dis solved air. On.the other hand, pure water vapor (steam) below the critical tempera ture, can be saturated at only one temperature for a given pressure. The values of saturation pressure listed in Table 2 have been computed from the formulas of Goff and Gratch. THERMODYNAMIC PROPERTIES OF WATER AT SATURATION Since water vapor at low . pressures acts almost as a perfect gas, the enthalpy of water vapor should also be a function only of the temperature within these limits. Therefore, the enthalpy of the water vapor may be expressed as being approximately equal to the enthalpy of saturated vapor at the dry-bulb temperature of the mixture. Substituting these values . in Equation 22, the enthalpy of the mixture becomes . h = 0.241 + Wh, (25) where hi is the value of the enthalpy of saturated vapor at the temperature t, and is obtained from Table 3. Table 3 offers revisions to existing steam table data with extensions downward to --160 F. These revisions and extensions were a necessary preliminary to the construction of Table 2. A detailed explanation of the methods employed in the construction of Table 3 is given in a paper by John A. Goff and S. Gratch.* . As in Table 2, the temperature scale used as argument in Table 3 is the Fahrenheit scale defined in terms of absolute temperature T by Equation 24. The symbols used as column headings in Table 3 are the same as those used in steam tables, and have the same meanings. Properties of water above 212 F from Keenan and Keyes* are given in Table 4. - DEGREE OF SATURATION Degree of saturation has previously been defined as the ratio of the actual humidity ratio to the humidity ratio of saturated air at the same drybulb temperature and barometric pressure. This may be stated mathe matically as Obviously the degree of saturation u can have any value from zero (dry air) to unity (moist air at saturation). The degree of saturation is con- % I1 !l s 32 CHAPTER 3 1956 Guide . |a . SSSS SSSS 8S2g gSS SSSS SSSS 3333 7777 7777 7777 71 " 1111 1 1111 1111 J 60 & Iiii 3S32 ssss sg|g sssi isii ssss ssso a . - * d O O. ddoo dddd 5 . s=ss ssss ssss ssssssss ssss dddd oodo . ssss ssss IssS ssss eiMn'd Vdd g a .1 - - sH v O H O. I a> .s Sw3 . l iS |S.S j I5S5I5S5 IrSrIrSr 3353 5553 Irsris" sil BSSiSlli. 3SS2S3Ss O1 O1 O1 OI 9I 9I 0I9I 0900lT' IOIO. OIIO II 9M00M0 101091 0I I99II90| " (9I9II00 . SS2 9SSS2SES: Mil 3233.SSSS SSSS 2222 a3S3S332 S322f2tJ23 1 1 II 1 1 II 1 1 II SSSS 5SSS .S5S 2S53 . 22S222S2 g2g2a2S2 S5?52E5*5r;- 2222 . Mil 1 M 1 MM fill. ooom SSSS 2S2S SSS2 SSSS SSSS 2S3-52? iioioso-ioiogool Bpoisosp iplolosp sOsOsOsO sOOsO&Oi sOsOssOsO? sOO2OO' 0000 oooo oooo oooo 0000 oooo 0000 ooeo MM II II MM II II MII II II II 1 1 1 1 1 T isll.Iiii Iff Iff! oooo ooos.SS0S poop opoo pppo poop opoo opoS oooo. eoSo.' OOOO ' OOod OOOO OOOO-' OOOO oooo oooo 'oooo Sa> ' I* 1SS2 fill 22*22 Biss ISSS sis? S2SS SSSS ssss ilss sill ills slii lgf lili fsss : ???? ??TT 1111 1111 1111 1111 1111'1111 a S n >.. Ej . ."ST Sfc. H ffl . O CS . ' rtfU. or 3 - :' 8 ; sWNiOii S09SM1S0 3s:MssQaWsCOaVg=No3SSe sCO s--ss sg>s3aos sososoos S2SS SSSS S&SS S8S8 2222 '2222: 222?' HH ' Mil MM III 1 II II . M l.l .Mil. III1. 1 1 1 1 . sill till Ills 111 liir ilil llsl: iiSS ooo^ oooo oooo oooo.oooo'oooo oooo -oooo JSSS ssss ssss l.l 1 1 S'SBSfi:; woo^p' k<.-.io#iqn !** '*-*9o as ssssssss ssss slls ssss sail' Ssss ssss: ssss ssss ssss sass- dsa-f iiii . 1 1 1 1 1 1 l.l 1 Mil l.l .1 1 Mil III11111 IsSi-Pis slis.;sslii. sill' ll5 'SIS;4lgri r-r>rr oooo oooo oooo' oooo] oooo oooo oooo' r * go m H c4 B . 3 5 H tgga-- H o8p8pSp Spp8SpSp oooo opoo SpSpSppSSpSoSoSp SpSoSopS SooSoooo oooooooo spsososp oooooooo oooo oooo oooo oooo.' ISci lip s ISil ills pal sisi .slss Ni't'l' oo so eo co oo oo cooo oe.okokp ' adotd oooo 'oooo OOOO' Ills 11! 1^11 =s lili lili, sill Pis ills Sip ISil lass oooo qooo oooo oooo edpo* mm' eeN cdo~*e .' sis SaH? ' - SSSS..SSSS. 8.52S. SSSS 77.77. 7.777 7777. .7M.1 SSSS-.SSSS ,S^3Sv;SSSS .' " ' " . > C om piled b y J o h n A .' G off and 8. G ratch. Thermodynamics 33 ahb. emp. T a b l e 2. T h e e m o d t n a m ic P b o p e b t ie s o f M o is t A m * (S t a n d a b u A t m o s p h b b io P b e s b u b e , 29.921 i n . H o) (C ontinued) 1(F) - pao<D*> (4000 r-oiO'r me.o QOON4D ec4t. mO*-*6 no 1 M 1 7777 7777 7777 MM Mil 1 . FT 1 s Bisi ssls Ssss. z SO SCOSWSoo 5wg g0.f1tO00g0 f-S oner* 1111 SSSS oisr< ^SSp 5S52 n& a oooo MNMN (4M a < a ssss iiii llsi ssss iiii& COIOH^-OOt & 2SS5 S2g SSRS 2|3S SSSS 3333 ??T78. OOOO. OOOO oooo oooo - 0000 oddo oddd a 1 M 1, n i i MM 1 1 M 1 ITM1 M MM A ssssO O oSS 3S? SSSS SfeeSS SSSS Q9eNcA. pppp Bess ssss ssss3|3 SSSS SSSS. S|S' dsN Z SSSS TT17 7777 7777 7777 7777 7777 7777 7777 0.00223 ' 0.00234 . 0.00246 0.00268 Is. 4 Q is Is Sta Ck D 1 rcaooOovOoncrot - 2353 5So? 2ggi..sssi pppp oooo- OOOO OOOO l.l 1 l>. MM II II isOc oooo oppp oooo 1 II 1 S332 SSSS oppp:. oooo II II 0^00 oooo SSS oopp oddo sill IIII dddd slsislsi oooo SS2S Sill oooo ssss oils oooo goo2 OOOO poop deed 2222 opoooopo. 5232 iiii oooo oooo 8SS2 ili oddo ssss poop oooo MM sill poop oooo 1 1 II slsislsi oooo Mil gilgigll oooo l .l M Isis ooopopop oooo Mil 2feo iiii oooo MII. ssss oops pSop dodo 1. oSMpCOoo4CSop4OS<o4 dddd 'a Biss Ills fill< (<o40>p1O4o0>o^0< 33Sp !!s S22i -*'' oooo P1 do-- hmnn 7TTT 7777 7777' 7777i i i III | SS|2. llii SSSS ssss ||23. 111 KS85 oopp = oooo OOOO oooo OOOO OOOO dopo dod.d d St isii issl sgss Bill& SS|S SgSS (4NN NC4-2SS5 2SS2 csonc 7T77 7777. 7777 7777 7777 -ddd MM 1dddd oo -- ts H gs . Ja OJ B iili gS 3 S sSis pppp ills ilss SSSS g&nS S - oooo iiiigononog oSoo pppp 3322 opoo mMMM poop 22 2* OOOO Mcao. oooS 3` oooo OOOO oooo oooo oooo oddo dodo oodd less ssssC4<t-4OI*C1 g pOpp OOOO Soip5pp Mges 5pSS 2SSS pppp Sfggv Eoi 2 Pm - x * . ills o5o SSSS Isii ills fggs onifia 5Sop2 siss C4MC4C. 4>de c^t^edd 03 000 - ' . i i 17 7777So.*.*. N p 040 IIM MM rscs --o O oo r- co MM -- O -- C4 nee 1 C om piled b y John A .'G o S ahd 8.' G ratoh ' 34 CHAPTER 3 .1956 Guide 3I& =2S=~2 SSS" "S5S SSSS SSSS SSSS SSSS m m p m p m p 1 la* .. * jj-. SI! Hi Hi MS! SB US SMS 81 Oj_ f Wap53 w J Mil 111 SIS- Hi !S13' 1111!"- till MM Mil 1 1 1 1 Mil Mil II III! ill! Sill Hit 1111 1111 1111 III!a S < OOOO OOOO OOOO OOOO OOOO OOOO oooo oooo j- e0 S III! HI? !II111111111ISII III! ijl ah. 1 4 nil nil ilil III! Hi nil IBS HIS oooo oooo oooo oooo oooo oooo oooo oooo hi mi m m m mi m m a5 55 . <a g3 i w'd (S`` hb m MfHi! ski m m w m sh mb hh'bm m m mb - a . a3 1; 3 8 g Eg& !af s* 1111SS11 MIS ISIS SIS SIS? US Ills ills Ilil 8338 3331 3833 III! ilil M8S PSS Illl 8333 3383 SSp 2=== ==22 2222 2222 2222 2222 2222 im mm m mi m mm ea or_ _ f5eh2*** ' -"S = 23? 2323 2SSS SSSS SSSS SSSS SSSS -*t _ ' C om piled b y John A . G off and 8. G rateh. E xtrapolated to represent metaatable e q u ilib riu m w ith undercooled liq u id . T a b l e 2. T h e r m o d y n a m ic P r o p e r t ie s o p M o is t Air * (S t a n d a r d A t m o s p h e r ic P r e s s u r e , 29.921 i n . H o) (C ontinued) Thermodynamics 35 C ondensed Water pj al--. a SCc, &<.H SSS= SS?3 3233 SSSS ssss ssss ssss ssss ^ p. a3>d-* 1! 111! HI 111! 11? II! > Illl Illl Illl fill Illl Illl Illl Illl oooo oooo oooo oooo oooo oooo oooo oooo E n tro p y B tuA Lb) (w ggsg 222 2=== ===2 2222 2222 222= ==== o=2* =52= sags assa aasa sjsss E nthalpy B tu/Lb * ii 0.06078 0.03006 0.03096 0.03168 `g - ' < H0Q 3 o3 Illl ii ill ill ilil ini lii jii 0 63 w oooo oooo oooo oooo oooo oooo oooo oooo 0 as0a. O $ 1! Ii Hi! 1! SI! Ill 1! * HB SIS ills II Isa as MSI MS a . a, > 3 0 sill Ills =lis S53S Isse ssss $;s3 ssss a a J 3 oooo oooo oooo 222= =222 mm(5 < ih sin mis Ha mi ms 0 S ISIS ISSI Sill ISII III ISIS Ills HIS < 1131 111! 33313311 111g jO nJ l Illl III! Mi 8 5 SSSS Illl ill SHI S1SS HIS as Illl EoS |S S** mi HI! HH Hi! Illl. ms m m 0 fa 333= 3333 3333 SSSS- SSSS SSSS SSSS SSSS I H 36 CHAPTER 3 1956 Guide m- g,-ss; sgRisg sssss ss&ss sssss sssss gsggs Is III HU iisii mu uni |||8 ||||f 1 ini mi! mu inn mis m m 8 SS333 33332 IIIII Hill Hill SHIS IIIII I * 11! mm !!! ill Ml IS!!! t! ___________________ ;________________________ ;______________:__________!__________________________________ j. Hill H5i Mil list Illii Mil! IHH 09000 ooooo ooooo ooooo ooooo ooooo ooooo "I Bill iil ill IIIII Illii if!!! Hilli ooooo ooooo ooooo ooooo- ooooo ooooo ooooo jj5f * i ihh ms suss suss Hiss inn mn m ssp.as m sss sss smb 23^789 24.029 24.270 24.610 24.761 24.991 19.221 ;ll 20.423 ' 1 S SIM silt Sill ISIS IISII SSSSS ill 1 g 5 ISISS11211SI1SI Sllll SHIS SISIl SISIH !!!!! ili 11115 mil IISII I!!!!!!!!! 22222 22222 22222 22222 222-- -- 533-^- -- w ffil IIIII iil iil! im ill!'!!!!! .'.ft SCSS5 SSRKK SSSSS SSSSS sssss sssss gsggs C om piled b y John A . G off and 8. Gratoh. T a b lb 2. T h e r m o d y n a m ic P r o p e r t ie s o r M o is t A i r * (S t a n d a r d A t m o s p h e r ic P r e s s u r e , 29.921 in . H o ) (C ontinued) E n t h a l p y/ o lb drt Thermodynamics 37 135 136 137 136 139 Eaj aso.--.. < MOOrO>0OOO) 110 111 112 113 114 SSS22 SSSSS NMCNPNt-ONOWO) 8mS35 u5fl "i-* s SonN<aeoemsonNeg>iMofj 0aNr-OtoOnCx4 iiiii nnnnn mnnnn SoSoS-cS.ST iSoepc.iso stodlidldgd sauSHa- >*2 ||t* SommS Se2ieSio2ttSo ssssg gSS3 or-oVSpS-Saono IIIII ooooo ooooo ooooo ooooo ooooo ooooo ooooo oo > J's.i ooooo ooooo 222aoS3 MOMOCOONON ooooo sssss --oo--ooOoO oooooooooo sssss oonovoooiooooooooooos g S SS(S8SNS ooooo IIIII ooooo S^OOCOO--SOOSNO----NON3-- d2NNN2dNMSNoCNSdOMd5* 0sSd0sdS--soStosdSMsdS0 sddaoidlsd oIcodelodclodciodim OE QJ csoceno ooooo SNSNSnrSeSS ooooo <3050S)08MSO o' 0 0 d 0 SOOsnQNSSMS ddodd Odc--odo--oodomSnd--3wco13 SoS3o52e ooooo<4<4C)N4 o'lncotg^t ddoddSCCPiCCDtCCI-COOtCt es aDt*. ' n4OM oOooo0>ooOooOoo-- soI2Qos2NosnOostnMosnn'. ondto9dooo7iood2cod29 Sododododo 0So0dS0dS0dSSdS omnSodooScodooSr-odoSoodoSoo SSooodS2odS22odSSodS . 3B ^COtetPCO 00 S3 3 2 S 52 --~*m SSSSS 823SS S 0" 2 2 2 . ^mrCOe00mIOoo -22SSS 2*3--3ata3oo5o onc.no 3S|2 000^0 or-ofnlooaovoooi 3 2S3S8 N>O<-> 38225 SS52S SSSSS otO-tm*t>ot<ecaor-mo' ^e0n0t^e0s0d0 oohS C-COO CO 00 SS223 'ceo --o SSSSS Illiim2--2S ss;jss WlbN onV NMMNM ts-asoasseso sssss soososmsosSB sssss dodo -- CO coco coco 33S2NO|NQ)N-- csmmSS S ioitsoddidi N0 n<0S10S)0o0 oeee2ooo2oce5ooe3o sssssMC-0IOAOOOODiOS' 00M0 ddddd d s s s s SSSli 2iil ao co 00 oo 00 g" SleSI- lllss |ill Islii" M S3 a^meo -- tgcjooe 2 m5*2 HHnMN toc-nnno9c coot S1S0 cicicieoco' MNNCn co co co com ``E iiiil 5j2S3 ssssS SS25S S --ssso ' nMMieoMogNnotnoonon jOOO-O' oomcon nc-to-.cn-.a--oeeoo aaooo ooooo ddddd ev^tooo ooooo SeSSe ooooo S322S o>B>oo ddodd S2S2S2S3S3 ddodd S3ococo mao -- -roo 0)0000 S-- S-- S-- Cn4oC4 aoooocnoomMeg . 3 SB' - o9oosoo O -- M CO SSS3Sotoc-aco sssss MmtNoor-coleeas*. nnnnS T a b l e 2. T h e r m o d y n a m ic P r o p e r t ie s o p M o i s t A i r * (S t a n d a r d A t m o s p h e r ic P r e s s u r e , 29.921 i n . H o ) E nthalpy B tu/Lb Aw 38 CHAPTER 3 1956 Guide lIs ' 15315 1155= sssss sssss ssgss g|sss gESIS . l k* ns! sisi ill m sun mu mu 31 wHae* ins Shi hi mu as uni sail mu mis mm ssis sis mu * HI! ill Sill III!! Hill ii!S SHIS I j !i!i il! ill!! SIS! SI!! S1SSI ISIS I- ' a IIS 111 IS! Mill 1! 11! Hi jsg- < i alias issii isaai as ass isr IsSil I1IS3 lilil liiii lilll 81135 liiii 5 IlSil II1SI illi ISlil Hill IBS HIS - '9 - a Sill! SHI.as nil ISIS USB ISIS >1 j . 'BBS BBS IBS SHB SB! IBS! 11118 g *. ISSII ISISIISSI SUSS Sill ISIISIIS1S ISSII BBS 111 ISIS! ill!! SIS! SISI . sis o2S-aSSS2 223S223S2 S2S2S2S22S S22S2&22 S2S2S2S2S2 S2S2&2S2S2 2222 T a b l e 2. T h e r m o d y n a m ic P r o p e r t ie s o f M o is t A i r * (S t a n d a r d A t m o s p h e r ic P r e s s u r e , 29.921 i n . H o) (Concluded) Thermodynamics f*SeH2tf-S'*s . SSSSS sssss sggss sssss-sssssi . E n tro p y tB$> > w m mts sH5 ***s. Bill S1SIISSII ISlIi-3SSII1 > IIIaH Z fi III HIS! a mmOzo a^> J> 4 ms! hi liiii 39 '5sHa s BBS BBs 5BH BBS mWoHs?Wd_aB* ill lings ftSHb> j ill IIS IS!! S!1 SiSiii K Hill 85311 m; iiiii mm S|5S3 j 15311 3I5SI l|l=|iiiii slllll WipS J IISISIIIIS Sisi BUS fill mm 16 mi sssii bbss .< mmgo 3 a 1 ' ii'si 'is m suns O1Q 0 SISSS IISSI SSIII SHIS 1SIISI l H u m id it y R a t io WB ill!Jill IliS'SHH ma j ts *&. 15ESS g=SS5 sgggs gssss.ssgsgg J 40 CHAPTER 3 1956 Guide 33s I3I1121 1 1 1 1 1Sl =l 1 Ilf'f'f' - ' ' f1s,1ff ff` j* f ssss E 1 hi l!ll 151! 11! l!li Sill 1ISS1111 ill sh I P H 1111! IS! ill III III Hi. S'S "3 I. i T1Y1T1T Illi 1111 iiii 7777 sTiTll fill 777? I??I?I?! I??I?I?! I?I?I??I r iiii ill iii ill ill a a mi 3 <5 .2 I tf 11 ii in hi hi in in ill a b l e 3 . T h e r m o d y n a m ic P r o p e r t ie s o p W a t e r a tT fl ii Ilia ?si| pis flil ill? Ip? l|fl Ip? 3. J*a a e. fpl iiii Ssii *'' 25 TM' 2"" 4i IpjIliliiiMHH!5TM1 i It,i 11! 11 IIII 111 III! if III! SB' C om piled by. John A . G off and 8 . G ratch. - i S a- liSl ili Is!! iiii mi ill! r A J 111 111 111! ISIS MS SJJa ms an 31s" 1212 2f2 221 s-ff jtff Thermodynamics Si fa t& f7?7 ^77 7777 7777 4) TM 8at. Vapor -U Lfa ' !!!! IS Hi 1111 Hi SIS is! !5H T a b l e 3 . T h e r m o d y n a m ic P r o p e r t ie s o p W a t e r a t S a t u r a t io n * (Continued) Sat. Solid a I 111 ii l!l Ml ill 111-SHI IBS s%a. H s s a aii iiii s iiii ni ii ul 1 dM Ills ii iii ill til! iii iiii; iiii 1 i!K ill? is in in in ms o' iiii00^ 11(1 MM MM Mil Mil MM II 1 1 Mil l 3 Sg3 0. c 6 &a - t*.fo* a i. O g<W - CO to 1 mm m mm.issi !i!i hi HiSl -ISIS IS! MB IB! fiffl Mi! Ml s2es2ss2sS2 gg2g2sg2s22s 2S2S22S222S2 g2g22g22g22 2222 s22s2s2s s22s22s2222s s22s22s222s2 2s2s22s2222s i 111!Is 1? SB? SSSS HI! ISM HI 111 SHI m iIAs' 3 A. <? 111! Hi liS I!h m m mi fa2a}<fJt_e ^777 7777 7777 7777 TTW 7777.7-" "T~ T a b l e 3. T h e r m o d y n a m ic P r o p e r t ie s o p WATBR a t S a t u r a t i o n 1 (Continued} 0.01743 0.01743!! IS 0.01744 CHAPTER 3 1956 Guide lie =222 2222 ssss 3 IS -.is 0.00000 as ssi! , sa1 &*. S2Sg2lg5 I!!! m Si dd 1 m si ' B' 1 Is isiSilil 5s!is?SS-lslss22i IIS 111! m il dd S d 1 I- % 111! 00=0 IIII oo=? till 0=00 ffi? ills ???? !7i?a7 9. i i 1111 ill IssIsIsI ssss IIII Hssssi Hi i 1- l 3SR8 sill ssss IIII SSSS IIII ssss IIII 11 ssss Hi I 1, 3 nMiill sIsIIsI; m1 M 1 1I1I3II1 1I3I1II1 2Si SSi S=iS2i 11 11 i 3 -at !, * IIII III! III! IIII Iiii IIII II- frI 8 I I* 1111 III! sill IIII IIII IIII iir i > I Ir 3. 11 a II IS I i: aa- 111!!! ionddi iiii IIII dodo II oo 1 d 1. 5 !!SI !!!|; IIII 111! III! 111! III ||6 t~coc*2 2222 222 2SSS SSSS ssss sss- Thermodynamics d SS3SS SSSS;. SSSSS sssss sssss sssss 43 Bat. Vapor T a b l e 3 . T h e r m o d y n a m ic P b o p e b t ie b o f W a t b r a t S a t u r a t i o n (Continued)' mil liiii Hill mu IIIII Hill SSSSS mmB0. ' - Dy H isssiisissisi y mm moNZ a ii ii ii 8at. Vapor Sat. L iq u id * a mmm iiiii 111111 a 0. ae y H iiii Hi 111 III 11 siiii a HZ A ims pmiiiii im mil 1111 Sat. L iq u id Af ' a BJ H0i . & iiiii iiii iiii iiii iiiii iiiii DO Bs p >o dg ja? H iiiii iiiii iiiii iiiii iiiii iiiii Sat. L iq u id W C0O1 HI!! 1111! Ill 11111 Btt P- MsB 5 4 HI 11! ill II! Si! SI! ] "a Bill1 ' i i C9O < JAS IIIII Hill IIIII. ISII1IIISI1 4 4-- 1sssss ssss; sssss sssss sssss sssss (I 44 iIeB ` lls i3, 1* CHAPTER 3 sssss bssse scsse essss sssss sssss HIS fllll HI!! illl! Hi! IIIII j 11! !1! Si! ISIS 111 Si! s1 11 III 111 11 111 ill I I* na ini liiii mu mil mu 1 li Hill ills liiii Hill IIIII IIIII sBe h3 sal mu in iissi aim as 1 1. * suss sim mi nisi liiii sa i !* i Hill HI!! III! llill IHII!!!!! l!!ll!!!!! !, Aa. Ills 111 S1IIS l!!!!!!!. !S!l! ;] Sll ill HI 111 HIS!!!!!: ' J|S Lb/S q In. Sat. Vapor Bat. L iq u id S8SSS SSggC SBSES RS2SS SS3SSS SSSSS3 . Mill liiii III! llill 1956 Guide r Thermodynamics 0 B Sh faH 0 trx b a fa < B^ ' faH , ss s s s ssss S3SSS ssssg p.eooi--O--'t 22222 T a b l e 3 . T h e r m o d y n a m ic P b o p e b t ie s o f W a t b r a t S a t u r a t i o n * (Continued) F "a a u p> .P n o0 Z H a >a M 0. P pa a g Id nonononoeot 3833 aj 0 SA> DO 0 . d. M sssts B >o3 Cd > b tp 0 ': 0 P 1 , m* >3 a < Lb/S q I d. 8 td-t 8at.. L iq u id Vi HIP 00090 1.5136 i 1.6613 1 1.6103 1.6607 1.7124 0.66711 0.89388 0.92137 0.94969 0.97864 1.7656 1.8200 1.8759 1.9334 1.9623 SSSSS OHHN Meinnn 1.0083 1.0388 1.0700 i 1.1021 1 1.1351 1.1688 1.2035 1 1.2390 1.2754 1.3128 llill CtMMCtn ` 1.3510 1.3902 1.4305 1.4717 1.6139 1.5571 1.6014 1.6468 1.6933 1.7409 i 3.1703 1 3.2606 3.3530 3.4477 3.6446 go pi to eg as sSgs o eo coco o 0.01611 0.01611 0.01611 0.01612 0.01612 , 0.01612 0.01612 0.01613 0.01613 0.01614 0.01614 0.01614 0.01614 '0 .0 1 0 1 5 - 0.01615 0.01616 0.01616 0.01016 0.01617 0.01617 0.01617 0.01618 0.01618 0.01618 0.01619 1 0.01619 0.01620 0.01620 0.01620 0.01621 ssssss 381.51 870.73 860.30 350.20 340.42 251.25 244.57 238.10 231.82 225.73 219.83 214.10 206.54 203.16 197.63 S3S83 mncni-n'OnSn ' caSoceS SSSe5 >. w Sat. Vapor Sat. L iq u id i Af 441.12 428.40 416.09 404.19 892.67 881.53 870.75 360.32 350.22 340.44 65.02 ' 66.02 67.02 ' 68.02 69.01 70.01 71.01 i 72.01 j 73.01 1 74.01 287.98 280.16 272.60 265.26 258.16 75.00 76.00 77.00 1 78.00 79.00 80.00 80.99 81.99 82.99 83.99 219.85 214.12 208.56 203.18 197.95 Sov&n 00-00 0 1041.27 1040:70 1040.13 1039.66 1039.00 1038.43 1037.86 1037.29 ! 1036.72 i j 1036.16 | 1032.73 1032.16 1031.58 1031.01 1030.44 1029.86 . 1029.30 1028.72 1028.15 1027.57 1026-99 1026.42 1025.85 1026.28 1024.70 etiOMttp. ctetctetct c >-? 1101.30 1101.73 1102.16 1102.69 1103.02 1103.45 1103.88 1104.31 1104.74 1105.17 1105.59 1106.02 1106.45 1106.88 1107.30 1107.73 1108.16 1108.68 1109.01 1109.44 1109.86 1110.29 1110.71 1111.14 1111.66 1111.98 1112.41 1112.83 1113.26. 1113.68 a Sat. L iq u id Evap. 0.11520 0.11701 0.11881 0.12061 0.12241 1.8874 1.8830 1.6786 1.8741 1.8698 liiii 0.12420 0.126QO 0.12778 0.12967 0.13135 .0.13313 0.13490 0.13667 0.13844 0.14021 1.8437 .1.8394 1.8351 1.8309 1.8266 0.14197 0.14373 0.14649 0.14724 0.14899 1.8224 1.8182 1.8140 1.8098 1.8066 0.15074 0.15248 0.15423 0.16596 0.15770 1.8016 1.7973 1.7932 .1.7890 1.7849 0.16943 0.16116 0.16289 0.16461 0.16634 1 1.7809 1.7767 1.7727 1.7687 1.7647 I 1.9103 1 1.9379 1.9356 1.9333 1.9310 00990k oSooooaSoq gllgg eoeo^OtO viSSSSSS cBdod>d> c(eScfeMaoemiean oaa>a>e 1 1 t:22SC Seoeo ooo ---- 97 68 99 100 101 112 113 114 115 116 45 46 CHAPTER 3 19S6 Guide T a b le . 3. T hebmodynamic Pbopebties op W ater at E n th a lp y , Bto pbr lb Bat. Vapor 192.85 187.93ill sgsgg sgggg sgsgg ggggs S==== sssss i i, !1S111111! Bill 111 Mil 1HI I 3 !!!!! lit 111 IHI! Ill ill 1 1 11 IS! if! 11 SIS! Ill 8at. L iq u id ftf L 52S2S 22m mil SSSp 3S2SI 2 SSSSS SSSSS SS2S3 ssssa sssaa ssass iiiii inn mu mil mu mil L him mm iiiii iiiii mu 3 l IHI Ilia Hill HIS HIS mil .E g 1 ft. H > 1 1. UlSimi mu in in ill j l = SB!? SHI ISSII SKI HISS SSB J- 1 mm aa mm uni b y John A . Goff end 8. Gratch. .m SgSBg aasBa Baaaa Saa== ===== === Thermodynamics 47 B:|C saaaa sssss sssss sssgg Saaaa saggs .1 e mil Hill mi ||| iiiii iiia b a 3 A. ff-t ' H>fat J-? urn iiii mil. iiiii mu inn * HAOHZ. Hill IHI Iiiii llill I1IH Bill *f Sat. L iq u idV 1 Sat. V apor T a b l e 3. T h e r m o d y n a m ic P r o p e r t ie s o p W a t e r a t Sa t u r a t io n * (C o n tin u e d ) sssss sssss aasss s=sss sssss sasss afBt aSaaa aSaaS BaaaB SaSaa aBBBa aaSBa 111 maAf(<t. >* H>jj*< IIS IS IBS BiS Af<t. ? Wz sssss sssss sssss sssss sssss sssss SBsSa aaaSa aBaSa aBaaB S=SS5 SB=== Sat. L iq u id Af a aft au A. E ir ms! ns is inn sssii mis i -a0ft . >1fot > A III IlSSi .18311 HIM I1S1IIIII H CAO. Hi 11 III ill Hill 111 Sat. L iq u id IV ! a S IIIII IIIII S83K.M8W-.EliK MMS 3a d otioioido; 2222-- = = = 22 22222 =2=22 a a* 6ft oa *a< e 0c0 J !??? fill! 111111111! 11!!!!!!!! faar<.HSfc aasaa asSBS 'BSBI SUBS aaaaa Baals  r I 48 CHAPTER 3 1956 Guide. Thermodynamics 49 Jj- 3Ss B3S3 SSSSs BsSs 2232S 223s 1 i. i ill! lit ill III! ill ill B 1 i* 111 Hi ill 111 III 1111 x* ! iIls"SsSi IGllsslsSg HSSisssss jsssslillli SgslslSisl IsSssisigs ooooo oddod eeedd'deddd dddoe odddd Sat Vapor Sat. L iq u id A* s liiilillliiiiii iiiiiiiiii ini 1 l* I13I11I1I lllirllillisil Hill I J 1. ism lassi siiii his mu Hill i Sat. Vapor Pf 2 B' iiiriffli iiiii mm sssii B \ 1* mu uni:mu ami um iju > j iiriiiyiiiffliirii ^ .U a u id s s i!!i* riissi' sii!s si mm 1: i I mmmmwm m S333S sssgs.-sgsag .gssss 2=5=2 2=2s Table 4. Pbopebties of Satcbated Steam: Pbessube Table* Aba. Passe. In. Ho V Sfbcotc Volume Enthalft Entbopt - Asa. - F Sat Liquid .W Sat. ' .Vapor . * Sat . liquid Evaf. - **c Sat Vapor Sat Liquid Evap. ' Stt Ac Sat Vapor St Pbess. In. Ha P 0.26 0.76 1.00 8 10 40.23 68.80 70.43 79.03 91.72 101.14 125.43 140.78 152.24 161.49 0.01603 0.01604 0.01608 0.01608 0.01611 0.01814 0.01622 0.01630 0.01635 0.01640 2423.7 1256.4 856.1 652.3 444.9 339.2 176.7 120.72 92.16 74.76 .8.28 1 1071.1, 26.86 1060.6 88.47 1054.0 47.05 1049.2 59.71 1042.0 69.10 1036.6 93.34 1022.7 108:67 1013.6 120.13 1006.9 129.38 1001.4 1079.4 1087.6 1092.5 1096.3 1201.7 1105.7 1116.0 1122.3 1127.0 1130.8 0.0166 0.0532 0.0764 0.0914 0.1147 0.1316 0.1738 0.1996 0.2186 0.2335 2.1423 2.0453 1.6881 1.9473 1.8894 1.8481 1.7476 1.6881 1.6454 1.6121 2.1589 2.0985 2.0635 2.0387 3.0041 1.9797 1.9214 1.8877 1.8640 1.8456 0.25 0.50 0.75 1.00 1.5 2 4 6 8 10 12 169.28 0.01644 63.03 137.18 996.7 1133.9 0.2460 1.5847 1.8307 12 176.05 0.01648 54.55 143.96 992.6 1136.6 0.2568 1.5613 1.8181 .14 16 182.06 0.01652 48.14 149.98 988.9 1138.9 0.2662 1.5410 1.8072 16 18 187.45 0.01655 43.11 155.39 985.7 1141.1 0.2746 1.5231 1.7977 18 20 192.37 0.01658 39.07 160.33 982.7 1143.0 0.2822 1.5069 1.7891 20 196.90 0.01661 ' 35.73 164.87 979.8 1144.7 0.2891 1.4923 1.7814 22 24 201.09 0.01664 32.94 169.09 077.2 U46.3 0.2955 1.4789 1.7744 24 26 206.00 0.01667 30.56 173.02 974.8 .1147.8 0.3014 1.4665 1.7679. 26 28 208.67 0.01669 28.52 176.72 972.6 1149.2 0.3069 1.4550 1.7619 28 30. 212.13 0.01672 26.74 180.19 ; 970.3: 1150.6 0.3122 1.4442 1.7564 30 . Lb/8q In. 14.696 16 18 20 22 24 26 28 212.00 216.32 222.41 227.96 233.07 237.82 242.25 246.41 0.01672 0.01674 0.01679 0.01683 0.01687 0.01691 0.01694 0.01698 26.80 24.75. 22.17 20.089 18.375 16.938 15.715 14.663 180.07 184.42 190.56 196.16 201.33 206.14 210.62 214.83 970.3 067,6 963.6 960.1 956.8 963.7 950.7 947.9 lifi0.4 1152.0 1154.2 1156.3 1168.1 1159.8 1161.3 1162.7 0.3120 0.3184' 0.3275 0.3356 0.3431 0.3500 0.3564 0.3623 1.4446 1.4313 1.4128 1.3962 1.3811 1.3672 1.3544 1.3425 1.7566 1.7497 1.7403 1.7319 1.7242 1.7172 1.7108 1.7048 Lb/Sq In. , 14.696 16 ' . 18 , 20 22 24 26' ; 28 30 250.33 0.01701 13.746 218.82 945.3 1164.1 0.3680 1.3313 1.6993 30 32 254.05 0.01704 12.940 222.59 942.8 1165.4 0.3733 1.3209 1.6941 32 34 257.58 0.01707 12.226 226.18 940.3 1166.5 0.3783 1.3110 1.6893 34 36 260.95 0.01709 11.588 229.60 938.0 1167.6 0.3831 1.3017 1.6848 36 38 264.16 . 0.01712 11.015 .232.89 935.8 1168.7 0,3876 1.2929 1.6805 38 40 267.25 0.01716 10.498 235.03 .933.7 1169,7 0:3919 1.2844 1.6763 40- 42 270.21 0.01717 10.029 239.04 931.6 1170.7 0.3960 1.2764 1.6724 . 42 44 273.05 0.01720 ' ' 9.601 241.95 929.6 1171.6 0.4000 1.2687 1.6687' 44 46 275.80 0.01722 9.209 244.75 927:7 1172.4 0.4038 1.2613 1.6652 46 . 48 278.45 0.01725 8.848 247.47 925.8 1173.3 0.4075 1.2542 1.6617 48 ' 60 52 64 66 68 60 62 64 66 - 68 281.01' 283.49 285.90 288.23 290.60 292.71 294.85 296.94- 298.99 300.98 0.01737 0.01729 0.01731 0.01733 0.01736 0.01738 0.01740 .0.01742 0.01744 0.01746 8.515 250.09 924.0 1174.1 0.4110 1.2474 1.6585 60. 8.208 252.63 922.2 1174:8 0.4144 ` 1.2409 1.6553 52 7.922 255.09 920.5 1175.6 0.4177 1.2346 1.6523 54 7.656 257.50 91818 1176,3 0.4209 1.2285 1.6494 - 56' 7.407 259.82 917.1 1176.9 0.4240 2.2226 1.6466 58 7.175 262.09 915.5 1177.6 0.4270 1.2108 1.6438 60 6.957 264.30 913.9 1178.2 0.4300 1.2112 1.6412 62 6.752 266.45 912.3 1178.8 0.4328 1.2059 1.6387 64 6.560 268.55 .-910.8 1179.4 0.4356 1.2006 1.6362 66 6.378 270.60 909.4 1180.0 0.4383 1.1955 1.6338 68 70 302.92 - 0.01748 , 6.206: 272.61 907.9 1180.6* 0.4409. 1.1906 1.6315 70 - . ;' 72 304.83 0.01750 ; 6.044. 274.57 906.5 1181.1 0.4435 1.1857 1.6292. .72 74 306.68 0.01752 5.890 276.49 905.1 1181.6 0.4460 1.1810 1.6270 74 76; 308:50 0.01754 . -6:743! 278.37 903.7 1182.1 0.4484 1.1764 1.6248 76 78 310.29 0.01755 5.604 .280.21 902.4 1182.6 0.4508 1.1720 1.6228 1 78 80 312.03 0.01767 5.472 282.02 .901:1 1183.1 .0.4531 1.1676 1.6207 80 82 313.74 0.01769 5.346 283.79 899:7 1183.5 0.4554 1.1633 1.6187 82 84 315.42 0.01761 . 5.228 285.53 .888.6 1184.0 0.4570- 1.1592 1.6168 84 86 317.07 0.01762 5.111 287.24 897.2 1184.4 0.4598 1.1551 1.6149 86 88 318.68 0.01764 5.001 288.91 895.9 1184.8 0.4620 1.1510 1.6130 88 90 92 94 96 98 100 150 200 300 500 320.27 321.83 323.36 324.87 326.35 327.81 358.42 381.79 417.33 444.59 467.01' 0.01766 0.01768 0.01769 0.01771 0.01772 0.01774 0.01809 0.01839 0.01890 Sam; 4.896 290.56 4.796 292.18 . 4.699 293.78 4.606 295.34 4.517 .296.89 4.432 298.40 3.015 330.51 2.288 355.36 1.5433 393.84 olwi 894.7 893.6 892.3 891.1 889.9 888.8 863.6 843.0 809.0 1185.3 1165.7 1186.1 1186.4 :1186.8 1187.2 1194.1 1198.4 1203.8 'SoJ:* 0.4641 0.4661 0.4682 0.4702 0.4721 0.4740 0.5138 0.5435 0.5879- o:87 1.1471 1.1433 1.1394 1.1358 1.1322 1.1286 1.0556- 1.0018 0.9225 S:S8 1.6112 1.6094 1.6076 1.6060 1.6043 1.6026 1.5694 1.5453 1.6104 l:Sm 90 92 . 94 96 . 98 100 . 150 ; 200,' - 300 . loo . `Reprinted by permission from Thermodynamic Propertied oj Steam, by J. H. Keenan and-F. ,G. Keyes pobHahed by John Wiley and Sons, Inc., 1936 edition. -. 50 CHAPTER 3 1956 Guide veniently used to interpolate values for the enthalpy, specific volume, and . entropy of moist air from the data of Table 2. Within the .estimated precision of the data of Table 2, at temperatures belbw 150 F, the volume v, enthalpy h, and entropy s, of moist air per pound of dry air at any de gree of saturation y may be computed from the simple relations: . u = Pi + pPu (27) h - fc. + yh,, 8 = S + y8m* . ' (28) ' (29) Thus, the degree of saturation is used in conjunction with Table 2 in the same manner as the quality is used with tables of the thermodynamic properties of steam. Correction of Table 2 for Temperatures Above 150 F The simple relations expressed in Equations 27, 28, and 29 give the properties of unsaturated air with satisfactory precision for most engineer ing design problems. Above 150 F, when greater precision than obtained by Table 2 is required, these simple relations can be adjusted by the addi tion of supplementary terms. To correct the volume, it is necessary to add a correction term 6 which is defined as ' . n(l -- y)& l +- aW& (30) where a denotes the ratio of the apparent molecular weight of dry air (28.966) to the molecular weight of water (18.016) and is equal to 1.6078. Table 5 gives the values of the coefficient A for several higher temperatures, the value of y at which the correction term v attains its maximum value, and the maximum value of 5 term there attained. The correction term for the enthalpy is = p(1 -- y)B 1 + aWrft (31) Table 5. Coefficients A, B, C Appearing in Equations 30, 31, 32, Maximum Values of Corrections Defined by Equations 30, 31, 32. Degree of Saturation at Which These Maxima Occur, Am. Maximum Value of Correction Defined bt Equation 33.- Degrbe_of. Saturation at Which.This Maximum'Occurs, Jim. . (Standard Atmospheric Pressure) c `t (F) A' (ft/lb) B (Btu/Ib.) (Btu/F/ lb.) Vmaz tw/lb.) Am&x (Btu/lba) mx (Btu/F/ lb) m (B*tu/T/ lb.) Am 96 0.0018 112 0.0042 128 0.0096 144 0.0215 160 .0.0487 176 0.1169 192 0.3363 0.0268 0.0650 0.1439 0.3149 0.6969 1.636 4.608 0.00004 0.00009 0.00020 0.00042 0.00091 0.00207 0.00567 0.0004 0.0010 0.0022 0.0047 0.0099 0.0207 0.0451. 0.0069' 0.0155 0.0332 0.0693 0.1418 0.2903 0.6180 0.00001 0.00002 0.00005 0:00009 O.OO019 0.00037 0.00076 0.4925 0.4878 0.4805 0.4691 0.4511 0.4213 0.3662 0.0015 0.0025 0.0040 0.0065 0.0106 0.0179 0.0333 0.3650 0.3632 0.3602 0.3557 0.3485 0.3363 0.3129 Th ermodynamlcs 51 Table 5 gives the values of the coefficient B and maximum values of h, the maximum values occurring at the same degree of saturation as i). Corrections for the entropy consist of two terms: which is defined as . _ m(1 - )C 1 + aW^i (32) and 5, the so-called mixing entropy, which contributes the larger part of the error. The mixing entropy is defined as I = 0.1579 [(1 + ixoWm) logio(l + paWi -- juaWalogio Ox) -- /x(l + aW) logi0(l + aW.] (33) Table 5 lists the values of the coefficient C, the maximum values of s and s and the values of y at which they occur. The maximum $ occurs at tho same degree of saturation as the maximum values of v and H. THE ASHAE PSYCHROMETJUC CHART a, gtapuivai icjJlOOCUU&tlUU LU tile LUCiTUO- dynamic, properties of moist air. To be of real value in the solution of engineering problems, it must, have distinctive features which aid in problem analysis. An examination of psychrometric mass and energy balances shows that no properties other than enthalpy and humidity ratio are required for the solution of problems. It is logical, then, to use these properties as the coordinates of a psychrometric chart. This was initially done by Mollier in 1923,7-8 and is the arrangement followed in the chart included with The Guide. The A.S.H.A.E. Psychrometric Chart is based on the best thermodynamic data available today, namely, those of Goff and Gratch, as given in Table 2. The chart is plotted on oblique coordinates of enthalpy and humidity ratio; the enthalpy axis making an angle of approximately 40 deg with the humidity ratio axis. This is shown in Fig. 3. For practical use, the inclusion of dry-bulb and wet-bulb temperatures, volumes, and indices of the condition of the air in relation to saturation, is necessary for locating and describing states on the chart. The arrange- 52 CHAPTER 3 1956 Guide ment of the families of curves of constant dry-bulb temperature, wet-bulb temperature, volume, relative humidity and degree of saturation, are shown in Fig. 4. Mass and energy balances deal only with net changes between definite states', the detailed history of a change is net involved# A chart used to facilitate such calculations must primarily aid in clearly establishing states. Lines drawn on the chart to connect different states need have Thermodynamics 53 CA) (B) FlO. 4. AbEANQEMENT OF FAMILIES OF CUBVES ON A.S.H.A.E. PSYCHBOMETRIC CHART no other significance than being loci lines, that is, lines which contain the two terminal points of a change according to the particular overall con ditions imposed. Loci lines are commonly called condition lines for the processes' concerned. On .the A.S.H.A.E. chart a condition line is char acterized by the ratio (ftj -- Ai)/(TF -- TFi). ; '. An abridgment.of the. A.S.HAJ3. Psychrometric Chart appears in Fig. 5. A large size (24 x 32) chart will be found on the inside of the back cover. The chart is drawn for standard atmospheric pressure. Steady flow changes commonly involve pressure drops with the flow, but so long as these pressure.drops remain a small fraction of the.barometric pressure,, no appreciable errors need arise from using a constant pressure chart For many design problems, the use of the standard pressure chart will not incur any undue error up to about 2000 ft above sea level. . The region above the saturation curve is a two-phase region giving equilibrium states for water in both the liquid and vapor phases. The ordinate of a point in this region is the weight of water in both phases per pound of dry air in the vapor phase, neglecting any dissolved air in the condensed phase. The ordinate at the saturation curve, or the point at which the break in the isotherm through the point in question occurs, is the weight of water per pound of dry air in the vapor phase. Consequently, the difference between the two ordinates is the weight of condensed moisture per pound Of dry air in the vapor-phase. The shaded solid-liquid-vapor region at 32 F is an isothermal three- phase zone, and separates the liquid-vapor zone from the solid-vapor zone. The temperature is 32 F throughout the shaded area. . 54 CHAPTER 3 1956 Guide It is possible to obtain two values for the wet-bulb temperature when this temperature is below 32 F. If the bulb of a thermometer is dipped into water at a temperature slightly above 32 F and held in a stremn of air whose wet-bulb temperature is below 32 F, the temperature indicated by the thermometer will drop rapidly until a minimum is reached below 32 F. This will be accomplished without the formation of ice on the bulb of the thermometer. After reaching this minimum temperature, * the reading will jump'.back to 32 F and remain there until the water on the bulb is frozen, after which it will slowly drop again until equilibrium is reached. The final temperature may be higher or lower than the first minimum reading, or it may be the same depending on the amount of moisture present in the mixture. In the absence of reliable data on the wet-bulb temperature over sub-cooled water, the chart, below 32 F, has been drawn for the equilibrium condition, that is, the values plotted on the A.S.H.A.E. chart are\for the condition where the minimum temperature is reached with ice on the bulb of the thermometer. -. USE OF TABLE 2 AND THE A.S.H.A.E. PSYCHROMETRIC CHART ' The use of Table 2 and the A.S.H.A.E. Psychrometric Chart in analyzing' typical air conditioning problems, is best explained by means of illustrative examples. In each of the following it is to be understood that the processes " in question take place at a constant pressure of 29.921 in. Hg, t.e., standard atmospheric pressure. - . Example 1: Determine the enthalpy of moist air at 80 F dry-bulb temperature and 0.40 degree of saturation. Solution a: From the data of Table 2, at 80 F, A, = 19.221 Btuper lb of dry air and A,. = 24.47 Btuper lb of dry air. Then A at the specified conditions is 19.221 + 0.40(24.47) = 29.01 Btu per lb of dry air. Solution b: From the A.S.H.A.E. Chart. Follow the 80 F dry;bulb line vertically until it intersects the 0.40 degree of saturation line. From this intersection, follow the line of constant enthalpy to the enthalpy scale and read 29.00 Btu per lb of dry air. Example S: Determine the thermodynamic wet-bulb temperature of moist air at the conditions of Example 1. . Solution a: From the data of Table 2. Applying Equation 8, A, = 29.01 Btu per lbof dryair (Example 1). As a first approximation this is A*, the enthalpy at satura7 tion at the thermodynamic wet-bulb temperature which is, therefore, approximately 63.5 F. W* at 63.5 F is 12.57 X 10~* lb of water vapor per lb of dry air, and W, is 0.02233 X 0.40 = 0.00893 lb of water vapor per lb of dry air. The specific enthalpy of liquid water at 63.5 F is 31.58 Btu per lb of water. As a second approximation, A* = 29.01 + (0.01257 - 0.00893) (31.58) = 29.12 Btu per lb of dry air. Interpola tion in Table 2 gives as the final answer (= 63.64 F. _ Solution b: From the A.S.H.AE. Chart. At the intersection of the 80 F. dry- bulb temperature line and the 0.40 degree of saturation line, read the thermodynamic wet-bulb temperature. Heating of Moist Air at Constant Pressure Without Addition of Moisture Example S: Air initially at 20 F, 0.80 degree of saturation, is heated to 120 F. Find the quantity of heat required to process 20,000 cfm of heated air. The process is diagrammatically illustrated in Fig. 6. The energy equation for the process is Ohi + !?, -- Ght igi ~ G(ht -- A,) Thermodynamics Q /////, F] ' G "2 77 /////// */4 777777 77 55 . . ' 1^2 ' Fig. 6. Illustration of Pbocbss of Example 3 Solution a: From the data of Table 2. The initial humidity ratio, which is the same as the final humidity ratio, is 0.80(0.002152) = 0.001722 lb of water vapor per lb of dry air; the initial enthalpy is 4.804 + 0.80(2.302) = 6.646 Btu per lb of dry airthe final degree of saturation is 0.001722/0.08149 = 0.02113; the final enthalDV is 28.841 + 0.02113(90.70) = 30.757 Btu per lb of dry air; the final volume is 14 611 40.02113(1.905) = 14.651 cu ft per lb of dry air. Since 20,000 cfm of heated air are to be processed, the total quantity of heat required is . .1?, = (20,000/14.651) X 24.111 = 32,914 Btu per min. Solution b: From the A.S.H.A.E. Chart. The process' is represented by the horizontal line 1-2, Fig. 7. The initial enthalpy," at 20 F dry-bulb temperature and 0.80 degree of saturation,is 6.65 Btu per lb of dry air. Since the final humidity ratio is the same as the initial humidity ratio, the ratio (A, -- hCi/(W, - Wt) = The horizontal line 1-2, Fig. 7, then represents the condition line for the process, and the final state of the moist air must lie on this line. The final state is located at the point at which the 120 F dry-bulb temperature line crosses the condition line and is labeled point 2 on the figure. At this condition the final enthalpy is 30.8 Btu per lb of dry air and the final specific volume is 14.65 cu ft per lb of dry air. Substituting these values in the energy equation,- . . . , . i?. = (20,000/14.65) X (30.8*-- 6.65) = 32,950 Btu per min. Cooling of Moist Air at Constant Pressure with Condensation of Water Referring to Kg. 8,moist air cooled from state 1 passes through successive states along the line W = tP, = constant until the saturation line is intersected. The 56 CHAPTER 3 2955 Guide temperature at this point of intersection is by definition the dew-point temperature for state 1. Further cooling through successive equilibrium states is accompanied by condensa tion. The succession of states for the total system, moist air and liquid water, is represented by a continuation of the W = Wi line into the liquid vapor region. (Tem peratures below 32 F would involve the solid-vapor region). Consider that the final temperature is U. The final enthalpy is then hi; the liauid water formed is {Wi -- Wt), where point 3 is at the intersection of the isotherm through 2 and the saturation curve; the final humidity ratio of the moist air is Wt; and this final moist air has dew-point, wet-bulb and dry-bulb temperatures all equal to t9. Example 4: How much heat must be removed from 20,000 cfm of air at 95' F dry-bulb temperature and 0.50 degree of saturation to cool the air to 70 F, saturated? Solution a: From the data of Table 2. The initial humidity ratio is 0.50(0.03673) 0.01837 lb of water vapor per lb of dry air; the initial enthalpy is 22.827 + 0.50(40.49) <= 43.072 Btu per Id of dry air; the humidity ratio at saturation at the Thermodynamics CU ft per lb of dry air; and the final enthalpy is 34.2 Btu per lb of dry air. The solu tion of the problem is . .= y (43 _ 34 2) = 12,200 Btu per min. 14.4 ' .; The other method is to use au energy balance, iff. " f*[5i -- hi -- hwdffli -- IF,)] . The initial humidity ratio is 0.0183 lb of water vapor per lb of dry air, and the final humidity ratio is 0,0158 lb-of .water vapor per lb of dry. air.. .Therefore; the,beat to be removed is ; : , : . ... i : ; = ?000 x (43 _ 34^1 _ 0.0025 X 38.07) 14.4 '. . ; ! = 12,130 Btu per min. ' .* w, W5 Fig. 8. Cooling op Aib at Constant Pressure Shown on A;S.H.A.E. PsYCHBOMETBIC CHABT final temperature is 0.01582 lb of water vapor per lb of dry air; the quantity of liquid fonhed is 0.01837.-:0.01582 = 0.00255 lb of water vapor per lb of dry air; A^, at .70 Fis 38.11 Btu per lb of water; the initial specific-volume is 13.980 + 0.50(0,822) 14.391 cu ft per lb of dry air. > Fig. 9 illustrates the process-diagrammatically: The energy equation for the process is . ' GAi Ght + G{Wi - W9)hmt + i9i i2i = G[hi -- ks -- {W\ " l^i)liwi] X (43.072 - 34.09 - 0.00255 X 38.07) = 12,350 Btu per min. . . Solution 5; From the A.S.H.A.E. Chart. Two methods may be used to solve the problem by use of the psychrometric chart. The simpler is to use the region to the. loft of the saturation line (Fig. 8). From point 1 draw a horizontal line on the chart until it intersects the constant temperature line in the liquid-vapor, region corre-. sponding to the final temperature,'70 F. This is shown as point 2 on the diagram. . . . .iff* -Ba G(hi -- hi) . The initial enthalpy is 43 Btu per lb of dry air; the initial specific volume is 14.4 G<wr-w,)hwj \ Fig. 9. Illustration of Process of Example 4 Adiabatic Mixing of Two Steady plow Air Streams at Constant Pressure The process is diagrammed in Fig. 10. By applying the principles of the con- servation*of mass and.energy,.three equations paay be written:: :; Mass balance for the dry air, Qi + G*~Q>. Energy balance for the process, . Gihi 4* Gthi Gth*. Mass balance for the water vapor, . . - GiWi + GtWt = GtWi Eliminating G% and combining the three equations yield the equation, .hi -- hi Wt -- Wt Gi .. . .. hr -- 'hr Wt*-- Wj - 'G% - ' * - ' ' (34): Example 5: Outside air at 0 F dry-bulb temperature.and0.80 degree.of saturation is to be mixed adiabatically with recirculated inside air. at 70 F dry-bulb temperature and 0.20 degree of saturation, in the ratio of one pound of dry air in the former to fou'r in the latter. Find the temperature and degree of saturation in the resulting mixture. ... , Solution a.* .From the data of-Table 2. , The only unknown properties afro the ' humidity and the enthalpy hi of the resulting mixture... TheSe may be determined from Equation 34. Thus, . ., 58 CHAPTER 3 1955 Guido ... . . . , 20.270 - A, 0.003164 - IF, 1 A, - 0.668 = Wi - 0.0006304 - . . ........ - : . \ !: from Which A, 16.350 and Wt 0.002657. The enthalpy of the final mixture may also be expressed by Equation 28: " ~ A, A* -h . Since m by definition is W.t/W,, Equation 28 may be rewritten as . 16.350 = A. + (0-002657/lF.) X ...... At 56 F the right side of the equation is 16.332, and at 57 F it is 16.582.'' Interpola tion gives as tne final dry-bulb temperature of the mixture 56.07 F. At this tem perature the humidity ratio at saturation is 0.00060 lb of water vapor per lb of dry air. Therefore, the final degree of saturation is #* W0X02657/0.00960 = 0.277 Solution b. From the AJ3.H.AJE. Chart. Equation 34 indicates that the state point of the resulting mixture lies on a straight line connecting the state points of Fig. 10. Illustration of Mixing of Two Steady Flow Streams at Constant Pressure .. the two streams being mixed, and^diyides this Une into two segments whose'respec- tive lengths are inversely proportional to the rates of dry air flow in the correspond ing streams. This is illustrated in Fig. 11. Points 1 and 2 are located and connected by a straight line. The state of the final mixture is set so that......... .. . ' ^_Pm _ 1 - Gt ; 4" . - Scaling the distances on the . chart, the required solution to Example 5 is 56 F dry-bulb temperature and 0.28 degree of saturation. Addition of Moisture to an Adiabatic Stream Consider a stream of moist air flowing adiabatically. between two sections, 1 and 2, as in Fig. 12. with moisture addition at the' rate (ti(1F, -- Wi) and the moisture having the enthalpy h* Btu per pound of moisture. . An energy balance yields^. . . . ' ,rt' . , Gifti + OAWt - W,)h. - G,h, (35) .. Example 6: Liquid water chilled to 40 F is injected into an air stream initially at Thermodynamics 59 Fig. 11. Solution of 5Example on A.S.H.V.E. Psychrometric Chart 95 F dry-bulb temperature and 80 F thermodynamic wet-bulb temperature. At what temperature will saturation be reached? now much water must be evaporated to reach saturation? . Solution a: From the data of Table 2. The solution of Equation 35 for As yields A, A, + (W, -- TPOft- The initial enthalpy of the moist air A* must be found from Equation 8, A, - A* - (IF* - IFOAw* . 22.827 + **40.49 = 43.69 - (0.02233 - 0.03673#*) (48.05) from which #* 0.511. Hence, As 22327 + 0311(40.49) = 43.52 Btu per lb of dry air: and IFi = 0.03673(0:511) 0.01877 lb per lb of dry air. The solution of Equation 35is At = 4332 + (IF, - 0.01877) (8.09) By trial and error, this equation will be satisfied at the temperature 79.87 F. At this temperature the humidity ratio IF, is 0.02223. The weight of water evaporated is therefore 0.02223 -- 0.01877 0.00346 lb per lb of dry air. AT ENTHALPY h. . Fig. 12. Illustration of Addition1 of Moisture to an Adiabatic Stream 60 CHAPTER 3 1956 Guide Solution b: From the A.S.H.A.E. Chart. Solution of Equation 35 for the ratio (ht - hi)/(Wi - Wx) yields . hi - hx Wt-Wi 1 (36) The slope of the condition line is therefore determined by the enthalpy of the water which is supplied. This slope is established on the chart by connecting the center of the protractor on the psychrometric chart with the value of hw on the pro5- tractor. Draw a line parallel to this reference line through the initial point 1 (Fig. 13). The second line is the condition line for the process. Since the conditions of the problem require the final point to lie on the saturation line, the intersection of the condition line with the saturation line gives the desired solution. Adiabatic Saturation Adiabatic saturation is the designation given any process in which the state of moist air is changed from some initial unsaturated condition to a saturated one with- t Fig. 13. Solution of Example 6 on A.S.HA.E. Psychbometbic Chabt t out the addition or removal of heat. According to this definition, the addition of moisture to an adiabatic stream may become an adiabatic saturation process.' Ex- ample 6 is an illustration. . .... . j, / ' A type of adiabatic saturation of further practical interest is the use of continually recirculated spray water in a saturating air washer. Here the spray water will ultimately come to the same temperature as the saturated leaving air; this tempera ture is, by definition, the thermodynamic wet-bulb temperature. Hence, adiabatic saturation in this manner will have the final state point on the saturation curve, with the same thermodynamic wet-bulb'temperature as the original state point. In a process such as this, the moist air enthalpy changes very slightly. The moisture added and temperature change may be obtained from the psychrometric chart as sketched in Fig. 14.- * ' Example 7: Moist air at 75, F dry-bulb temperature and 0.60 degree of saturation, is saturated adiabatically with recirculating spray water. Find the amount of water added and the change in enthalpy. '- , Solution a: From the data of Table 2. As previously stated, the final tempera ture of the mixture will be the thermodynamic w;et-bulb temperature at the initial state. This must first be determined by the method of Example 8, and is 65.51 F. At this temperature the humidity ratio at saturation and enthalpy at saturation are 0.01350 and 30.45, respectively. The.humidity ratio at the initial state is 0.60(0.01882). = 0.01129; the initial enthalpy is 0.60(20.59) + 18.018 = 30.372. The weight of water i Thermodynamics .61 Fig. 14. Moistubb Added and Tempebatube Change added is therefore 0.01350 -- 0.01129 = 0.00221 lb per lb of dry air; the enthalpy change is 30.45 -- 30.372 = 0.078 Btu per lb of dry air. Solution b: From the A.S.HA.E. Chart. Since the initial and final states have the same thermodynamic wet-bulb temperature., the results may be read directly from the chart. , Addition of Heat and Water Vapor to an Air Stream in Steady Flow Fig. 15 is a schematic representation of a system operating at constant pressure, where G\ is the rate of flow of dry air, pounds per minute. Gw is the rate of evaporation of the water, pounds per minute. . ' hw is the enthalpy of the liquid water entering, Btu per pound. . Q is the rate of heat addition, Btu per minute. . An energy balance for the system gives . . <7ihi + Q + Gwhw = Giht (37) A mass balance gives Gi + GiWi + Gw = Gi + GiWt or . GXWX + Gw GxWt ' . (38) Fig. 15. . Illustration of Addition of Heat and Wateb Vapob to an Aib Stbeam- in Steady Flow ' 62 CHAPTER 3 1956 Guide Combining equations 37 'and 38 and solving for the ratio (A, -- h\)/(Wt -- ifr1), ' ' hi -- hi : W, - Wi (39) Example 8: Moist air at 20 F dry-bulb temperature and 0.80 degree of saturation is heated and humidified until it is at 120 F dry-bulb temperature and 71.5 F thermo dynamic wet-bulb temperature. Water at 65 F is supplied. If the air flow rate is 20,000 cfm at the initial conditions, how much heat is required? Solution a: From the data of Table 2. The initial humidity ratio is 0.80(0.002152) = 0.00172; the initial enthalpy is 4.804 + 0.80(2.302) = 6.6456; the initial specific volume is 12.084 + 0.80(0.042) = 12.118. The degree of saturation at the final state may be determined from Equation 8 which may be rewritten as A*i + /ihut -f- hw*(W* -- oWrt) = A* Fio. 16. Solution of Example 8 on A.S.H.A.E. Pstcurometric Chabt The values of these properties are: A* -- 35.39; W* = 0.01668; A* = 39.61; AmS = 90.70; = 0.08149; A., = 28.84. , Making the proper substitutions and solving for degree of saturation, . u = 0.0681. . The final humidity ratio is therefore 0.0681(0.08149) = 0.005549; the final enthalpy is 28.84 + 0.0681(90.70) - 35.02 Btu per lb dry air. , The rate'of water addition iB obtained from Equation 38. G~ = T2T? (0 005549 ~ 0 00172) <m 6.32 lb perimin. The heat supplied is obtained from Equation 37. Q= -- hi) - ffwhw = (35.02 - 6.65) - 6.32(28.08) . *= 46,667 Btu per min. Solution b: From the A.S.H.A.E. ,Chart. . Locate the initial and final states on the. chart and connect them with a. straight line. Through the reference point on the chart, draw a line parallel to the line connecting the initial and final state points, the condition line, ana read the value of the ratio (ht -- -- Wt) as 7500 from Thermodynamics 65 the protractor on the chart (Fig. 16). From Equation 39 - Ai - hi Wt-Wi 7500 The rate of water supply was determined in Solution a, but will be found from the; chart. It is . ' ' '. . Gw = (0.0055 - 0.0017) = 6-28 lb per min Q - <7.(7500 - h.) = 6.28(7500 -- 23) => 46,900 Btu per min. Table 6. Pbessure and Temperature pob Altitudes in U. S. * ' Standard Atmosphere Altitude Feet Z - 1,000 - 500 0 + 500 . + 1,000 ; + 5,000 10,000, 15,000 20,000 . 25.000 . . 30,000 35,000 40,000 45,000 . 50,000 . Pressure Ik. op Hg P' 31.02 30.47 29.921 29.38 28,86 24.89 , 20.58 16.88 13.75 11-10 8.88 7.04 5.54 4.36 3.436 - . ' FTemp v t `' +62.6 +60.8 +59.0 +57.2 +55.4 ': ': .. , +41.2 +23.4 + 5.5 -12.3 -30.1 , -47.9 -85.8 -67.0 -67.0 -67.0 :. . U. S. STANDARD ATMOSPHERE The definition of the U. S= Standard Atmosphere is important to .the air conditioning engineer as an essential standard of reference. The basic assumptions in defining, the Standard Atmosphere are: .: 1. There is a linear decrease in temperature T with altitude up to the limit of the isothermal atmosphere at 35,332 ft. Thus, . ; . T = To - 0.003566 Z (40) 2. The air is dry. 3. Air is a perfect gas obeying the laws of Charles and Boyle: PV = RT ^ /. 4. Gravity is constant at all altitudes with the standard value.' 5. The temperature of the isothermal atmosphere is --66 F. ' Standard values at sea level, which are part of the definition of the Standard Atmosphere, are: ; .Pressure Temperature 29.921 in. Hg 59 F 64 CHAPTER 3 1956 Guide Absolute Temperature . Gravity Density 518.67 F Abs 32.1740 ft per (sec) (sec). 0,076505 lb per cu ft Values of pressure and temperature are listed in Table 6 for altitudes in. the standard atmosphere from --1000 to 50,000 ft above sea level! For further explanation, References 9 and 10 should be consulted. LETTER SYMBOLS USED IN CHAPTER 3 n a degree of saturation (decimal). ^ p = density of fluid, pounds per cubic foot. <p -- relative humidity (decimal). a ** ratio of apparent molecular weight of dry air (28.966) to the molecular weight of water (18.016) =* 1.6078. A coefficient from Table 5 for use in Equation 30 (obtained from Table 5). B = coefficient to be used in Equation 31 (obtained from Table 5). C = coefficient for use in Equation 32 (obtained from Table 5). /, = factor accounting for effect of mixing air and water, dimensionless......... O ** flow rate of dry air, pounds per hour. . G\flow rate of dry air, pounds per minute. ' Gw rate of evaporation of water, pounds per minute. H = enthalpy of the system. H = enthalpy of the flowing medium, Btu per pound of dry air. h = enthalpy of moist air, Btu per pound of dry air. . h = enthalpy correction term to be added above 150 F, to enthalpy. hi *= specific enthalpy of dry air, Btu per pound. .; hn h, -- hi the difference between the enthalpy of moist air at saturation per pound of dry air, and the specific enthalpy of the dry air itself, Btu per pound of dry air. 'y Ac ** enthalpy of saturated water vapor, Btu per pound. .; .. . hi a enthalpy of moist air at saturation per pound of dry air, Btu per pound of dry air. :....... hi* enthalpy of moistair atsaturationat thermodynamic wei-bvXb temperature, t* Btu per pound of dry air; ' v i kw = specific enthalpy of condensed water (liquid or solid) at standard.pressuie, : . Btu per pound water. . . . . . - ;* hw* a specific enthalpy of water-as added at the thermodynamic wet-buib tem- ... ,perature t*,, Btu per pound of dry air. .... . ; . hwi a enthalpy of liquid water, Btu per pound. ; ; hwa b enthalpy of solid water,. Btu per pound. 1KE = average kinetic energy, Btu per pound. . .. ; a average kinetic energy, Btu per pound. - '' * L flow rate of liquid water, pounds per hour. - m a weight of dry air crossing any duct section, pounds per minute.. n a mols dry air. ., .. n. a mols of Water vapor at saturation. . - ' n a mols of water vapor. . ' P absolute pressure. . " ' -/ Pi a atmospheric pressure, inches Hg. .% Thermodynamics 65 LETTER SYMBOLS (Continued) p a standard atmospheric pressure by definition 29.921 in. Hg.. p saturation pressure of pure water at prevailing temperature. p => total pressure of a mixture of air and water vapor, pounds per square inch or Hg. ' p, = partial pressure of dry air, pounds per square inch or inches Hg. p, = saturation pressure of pure water vapor, pounds per square inch or inches ' Hg. ^ s partial pressure of water vapor in mixture of air and water vapor, pounds per square inch or inches Hg. .. PE = potential energy, Btu per pound dry air. . PE average potential energy, Btu per pound dry air. q c= total heat added or subtracted, between sections, Btu per minute. q = ratio of energy added (or removed) to water added (or removed), Btu per pound. Also called specific enthalpy of water added. ,q, = energy added between points 1 and 2. ,qt = heat added between sections 1 and 2, Btu per pound dry air. _ r - universal gas constant, 1645 foot-pounds per (Fahrenheit degree) (mol). Rm -m gas constant for dry air. Rw = gas constant for water vapor. S = flow rate of solid water, pounds per hour. . .. g a entropy of moist air per pound of dry air, Btu per (pound). (Fahrenheit degree). ' 3 = correction to be added to entropy of moist air obtained from Table 2. g a additional correction to be added to entropy because of"mixing entropy" (obtained from Table 5)..Correction to be added to value of s obtained from Table 2. .. .. <. Si = specific entropy of dry air, Btu per (pound) (Fahrenheit degree; absolute). Bn =* the difference between the; entropy of moistair at &aiuration per pound of dry air, and the specifio entropy of. the dry air itself, Btu per (pound of dry air) (Fahrenheit degree, absolute).. ., *, =. entropy of moist air at saturation per pound of dry air, Btu per (pound of dry air) (Fahrenheit degree, absolute). ; v = specific entropy of condensed water (liquid or sblid). at standard atznos- pheric pressure, Btu per (pound of water), (Fahrenheit degree, absolute). T = absolute temperature, Fahrenheit degrees. . - To = standard atmospheric temperature, by definition 518.4 F absolute. t = temperature, Fahrenheit degrees. t* a thermodynamic wet-bulb temperature, Fahrenheit degrees. U = internal energy of system. U = internal energy. V -- volume. F = average velocity, feet per minute. v = volume of moist air per pound of dry air, cubic feet per pound. 0 *= correction to be added to volume of moist air per pound of dry air, above 150 F. Vi = specific volume of dry air, cubic feet per pound. 66 CHAPTER 3 1956 Guide LETTER SYMBOLS (Concluded) v*a ** -- p, the difference between volume of moist air at saturation, per pound of dry air, and the volume of the.dry air itself, cubic feet per pound of dry . air. .. .* ' . . v, = volume of moist air at saturation per pound of dry air, cubic feet per pound of dry air,; . .. or = total volume, cubic feet. W = humidity ratio, of moist air, pounds of water per pound of dry air. Wt -- humidity ratio, at saturation, weight of water vapor per pound of dry air, pound per pound. = humidity ratio corresponding to thermodynamic wet-bulb temperature t*, pounds of water per pound of dry air. w =* work done by system. . .. w = shaft work withdrawn between sections 1 and 2, Btu per pound of air. Z = elevation above any datum, feet. 2 average elevation, feet. . Subscripts with symbols have following meanings: 1, 2, 3 indicate section of flow; a = air, w -- water, wJ = liquid water, ws = solid water, s -- saturation, m = mixture; indicates that the value is at thermodynamic wet-bulb temperature. . _ REFERENCES 1 The Humidity Ratio of Moist Air at Saturation, by J. A. Goff and S. Gratch (Special Report of University of Pennsylvania Thermodynamic Research Laboratory, March 1948). . * Standardisation of Thermodynamic Properties of Moist Air, by J. A. Goff (A.S.H.VJ3. Transactions, Vol. ,55; 1949, p. 459). . 1 The Theory of the Psychrometer, by J. H. Arnold (Physics, Vol. 4, 1933). 4 Thermodynamic Properties of Moist Air, by J. A. Goff and S. Gratch (A.S.H.V.E. Transactions, Vol. 51,1945, p. 125). * Low Pressure Properties of Water in the Range --160 to 212 F, by J. A. Goff and S. Gratch (A.S.H:VJE. Transactions, Vol. 52, 1946, p. 95). Thermodynamic Properties of Steam, by J. H. Keenan and F. G. Keyes (John Wiley and Sons, Ihc., New York, 1936).' ^ ' 7 Ein neues Diagramm fflr Dampfluftgemlsche, by R. Mollier, (ZVDI, Vol. 67, Sept. 8, 1923, p. 869-872). *Das i-x Diagramm fur Dampfluftgemische, by R. Mollier (ZVDI, Vol. 73, July 20, 1929, pp. 1009-1013), . . ... . .. National Advisory Committee for Aeronautics, Technical Report No. 218, 1925; u National Advisory Committee for Aeronautics, Technical Report^No. 538, 1935. CHAPTER 4 FLUID FLOW Theory of Fluid Flow, Pressure Loss in Circular Pipes, Pressure Loss in Non Circular Pipes; Flow of Compressible Fluids, Ideal Fow Through Nozzle or Orifice; Flow Measurement, Head Meters, Location of Head Meters . and Pressure Taps Pitot Tube, Variable Area Flow Meters THE flow of fluids is part of the branch of engineering science known as fluid mechanics, which will be discussed here insofar as it applies to the work of engineers in the fields of heating, ventilating, and air con ditioning. Probably air is the most frequently handled fluid, but other gases and liquids are often involved. Compressible fluids (gases) and incompressible fluids (liquids) vary somewhat in behavior, though in cases where pressure and density changes are small, the gases may be treated as incompressible fluids. THEORY OF FLUID FLOW The following energy equation for one dimensional steady flow processes will serve as a basis for the theory of the flow of fluids. This equation is presented in several ways in various texts, but a suitable form is -- 4- Jui 4- pivi + Jq + " zi = 2?e 0 + Jut + p&* 4- W 4-- zi . ffe (1) where V = velocity in feet per second. . ' g = gravitational acceleration, in feet per (second) (second). gc a gravitational conversion factor = 32.174 (pounds mass .per pound force) X ft per (second) (second). J -- mechanical equivalent of heat'=!778foot pounds per Btu. ti internal energy, in Btu per pound of fluid. :; p = pressure in pounds per square foot. . o = specific volume, in cubic feet per pound. ' . . W " mechanical work done by the fluid in foot pounds per pound of fluid. . q = heat transferred to the fluid in Btu per pound of fluid flowing. z = elevation above some arbitrary' datunij in feet. . Subscript 1 refers to the entrance, subscript 2 to the exit. . Introducing the enthalpy h, which by definition is u + jf' expressed in. Btu per pound of fluid, Equation 1 becomes -- -j- jhi 4* Jq 4* " zi = t-* + Jhi 4- W 4- -- z* 2ge ge 2gc . 0e The equivalent differential form for energy Equation 1 is . (2) . -- dF7 4~ J du 4- d(pv) 4- " dz -- J dq 4" dW = 0 20o 0, 67 . (3) 68 CHAPTER 4 1956 Guide Replacing v by its equal g/g,.j> (where p is density in pounds weight per cubic foot) and rearranging, Equation 3 becomes ' -- dV* + - dp + dz + -- [/ du + p dv -- / dg + dW] = 0 2g p g (4) In the case of flow through a pipe, no outside work is performed so that dW = 0. Furthermore, J du + pda = JTda = J dq + JTdsf (5) where ds = total change in entropy. da' = change in entropy due to internal irreversibility from turbulence and friction. fluid Flow 69 diameter were the same throughout, the velocity, and consequently the velocity head, would be the same at both points, but the higher elevation at point 2 would still be responsible for a loss in pressure. The utility of the equation is evident, though it should be remembered that in it the effects of friction and turbulence are neglected, and that Fig. 1 represents ideal conditions. It should also be noted that care must be taken in de termining the proper mean density. Accordingly, the Bernoulli equation is applied most conveniently to. incompressible, fluids for which density is constant. Fig. 1. Relation op Vaeious Factobs in Bernoulli Equation Accordingly, Equation 4 may be written I dyi +'!*? + dz + - JTds' = 0* . . 2p p p . ' (6) In cases where there is no internal irreversibility, ds' = 0, and Equation 6 may be integrated to give' F** , P* , , _ j. Pi , ' -- 4------.+ Pi = "Z i--------- r 2g Pn 2p Pm (7) where pm is the proper mean density. This is commonly called the Bernoulli equation, named after the Swiss mathematician and physician who first propounded the theory. -- is known as the velocity head, -- is the pressure head, and z is the elevation P head, all in feet of the fluid; the total head, ht is the sum of the other three heads. Fig. 1 shows diagrammatically the relation of the various factors. The pressure at point 2 is lower than at point 1 because of the : elevation of point 2 over point 1, and the velocity at point 2 is lower than at point 1 because of the larger pipe diameter at point 2. If the pipe a In tho of subsequent portions of this chapter the distinction between s and will be omitted* Aside from the dimensional Consistency the factor, glge is not in general wignificaht in fluid flow analysis. Pressure Loss in Circular Pipes . v The pressure loss in circular. pipes is customarily expressed by the formula: .~ . . , flV * . 2ffd - (8) where . hi = the loss in head of the fluid under conditions of flow, in feet. ' l = the length of the pipe, in .feet. .' . V = the velocity, in feet per second. g = the acceleration due to gravity = 32.174 ft per (second) (second). d = the internal diameter of the pipe, in feet. / = a dimensionless friction coefficient. . The formula is generally known by the name of Darcy Or Fanning, though it seems to have been originated by d'Aubisson de Voisins in 1834: The factor / is a function of the Reynolds number, ` Aa. d Vp u (9) 70 CHAPTER 4 1956 Guide where ; NE. *= Reynolds number. p = the density in pounds per cubic, foot. . p = the absolute viscosity in pounds per foot-second. . Both / and the Reynolds number are dimensionless. To aid in comput ing the Reynolds number, values of -, the kinematic viscosity, are shown as a function of temperature for air in Fig. 2, and for water in Fig. 3. Fig. 4 shows the relation between / and the Reynolds number, adapted from a review by Moody.1 The straight line sloping downward at the left of the chart supplies, the values of / for laminar flow determined by the formula: .- Fluid Flow 71 unstable region where the flow changes from laminar to turbulent, or vice versa. .The actual value is impossible of prediction for any condi tions of flow, though in general it may be said that the prevailing type of flow persists into the unstable region; however, once the change starts, it proceeds very rapidly. When the flow is turbulent, the velocity profile is essentially parabolic over four-fifths of the pipe diameter, but near the pipe walls, the effect of friction becomes evident, and in the boundary layer at the pipe wall the flow is laminar. Fig. 5 compares the velocity profiles for three different Reynolds numbers, but for the same average velocity. The lower curve in the turbulent region in Fig. 4 represents the relation of / to the Reynolds number for smooth pipe, such as drawn brass tubipg Fio. 3. Relation of Kinematic Viscosity to Temperature op Water 64 f 'nr. (10) With laminar flow, the velocity profile is a .parabola, having the formula: V - ^! (i* -r V) (11) where r = the radius of the pipe in feet. L = distance perpendicularly from the axis of the pipe, in feet. Accordingly, the:maximum velocity occurs at the center of the pipe and is twice the average velocity; the average velocity is found when L -- 0.707 r. It is worth noting that roughness, of the pipe wall has no effect on the loss in head for laminar flow. Between values of the Reynolds number of 2000 and 4000, there is an * Superior number* refer, to the. references at the end of chapter. . Fio. 4. Relation Between Friction Factor and Reynolds Number Note: The straight line at left shows values of Friction Factor for laminar flow. Reprinted by permission from ASMB Transaction*. . or glass tubing. The effect of roughness on/, an effect which is considerable in turbulent flow, is open to some conjecture; artificially roughened pipes, for instance, give results at variance with actual tests. The curves above the smooth pipe curve of Fig. 4 represent a summary of tests on rough pipe, each of them identified by a value of e/d, with e signifying theabsolute roughness in feet. Values of e for different pipes are given in Table 1. To find the friction loss for any pipe, follow the curve with the proper value of e/d, to the pertinent value of NKta and from this' point proceed horizontally to left margin to find the value of / for use in Equation 8. 72, CHAPTER 4 1956 Guide The curves in Fig. 4 may be approximated very closely by the empirical formula:1 f - 0.0055 K--5*sT] Equation 8 is applicable to all liquids, ahd to gases when the pressure loss is less than 10 percent of the initial pressure. When the loss in. head is high, the formula to be used for gases is Pi* - Pi1 = fivi Pi* . gd pin (13) which may be arranged to give the loss in pressure, Fig. 5. Comparison of Velocity Profiles fob 3 Different Reynolds . Numbers but fob Same Average Velocity ^ Pressure loss in Non-Circular Pipes ;. The. formulas for friction loss in pipes are based on the use of pipes of circular cross-section. The same formulas may be extended, to non circular sections, by suitable modification. > In the basic formula, Equation 8,-the internal diameter d is to be replaced by the hydraulic diameter dH defined by the equation: ' ^4 X area of cross-section (15) *. wetted perimeter of cross-section . For example, in a rectangular duct, 1 ft by 2 ft, the cross-section area is 2 sq ft, and the perimeter 6 ft. Then the hydraulic diameter will be dB = (4 x 2)/6 = l'/ ft. - In the case of a round pipe, 4 X *d*/4 - --------- ---; = a . (16) In computing the Reynolds number, and from that the friction factor, the hydraulic diameter, is not to be used; A better approximate procedure is to. replace the length in the Reynolds number by the shortest dimension plus one-fourth of the hydraulic diameter. Thus, in a duct of dimension a x b where a. < b, Nb., for the purposes, of calculating friction factore,/is : JVb. = (o + 0i5dH)Fp/B ' : (17) FluidElow 73. Table 1. Values of e fob Diffebent Kinds of Pipe Typs of Pipe Smooth drawn tubing........ Commercial steel or wrought iron Asphalted cast-iron........................ Galvanised iron................................ Cast-iron.......................... ,,................. Wood stave....................-................... Concrete.. ................ ........... '............. Riveted steel..................... ................. 0.000005 0.00015 0.0004 0.0005 . : 0.00085 0.0006 to 0.003 0.001 to 0.01 0.003 to 0.03 This value of No. may be used in Equation 10 for laminar flow, and in Equation 12 or Fig. 4 for turbulent flow. The error in the approximation is somewhat greater for laminar than for turbulent flow; In the. former case, the relative error may be as much as 10 percent, while in the latter it almost always is less than 3 percent. : ' FLOW OF COMPRESSIBLE FLUIDS In the flow of compressible . fluids, the large density variations make impracticable the use of the Bernoulli equation, (Equation 7). In certain special cases, however, the exact equations for. compressible flow may be stated. If flow occurs with no friction or other internal irreversibility, Equation 6 becomes ,. ' - d.V' + -- = 0 2$ p If, in addition, the flow is adiabatic, . ; PfT* = pipi-* so that Equation 18 becomes or by integration, =1 -"-+ -d-v'-'0 2g ' (18) . . (19) (20) (21) This extension to compressible flow of Bernoulli's equation reduces to the more familiar form if the pressure change is small. The ratio of specific heats, fc, is used extensively in fluid dynamics; values of k for various gases are given in Table 2. Table 2. Ratio of Specific Heat at Constant Pressure to Specific , Heat at Constant Volume fob Compressible Fluids Fum>Coicfressiblx Ratio h -- Cp/ct . Carbon dioxide, methane, natural gas, superheated steam, 1.66 1.40 1.34 1.28Aol-.32 1 1.24 to 1.26 I-:?' $: i !; iii :7 CHAPTER 4 . . 1956'Guide ij . > " . It is convenient in the analysis of compressible flow to introduce the fl velocity of propagation of pressure impulses or, more familiarly, the sonic velocity, a, For perfect gases this is given by the equation:. ^ ' ; a1 = kgp/p - kgRT ; (22) Accordingly^ Equation 21 may be written M A[(sF_i]=o (23) ** or, by rearrangement, (24) which permits the calculation of the ratio of pressures at entrance and 9 exit of the steady flow device--pipe, orifice, or nozzle. From Equations || 19 and 22 it follows that . .- 1 *-t . aS Ti \pi) k (25) f so that k - 1 (TV - F,!) + - a, = 0 (26) and k ~ 1 Zl! of 1 + 2 a,' 1 7,1 1 +- 2 a,* ' : (27) The ratio of flow velocity to sonic velocity is known as the Mach number, M = y/a . i This parameter is particularly useful in compressible flow analysis. In general, if M ^ 0.1 the flow may be considered to be incompressible. |g This is generally true in heating and ventilating air ducts. In terms of the Mach number and 4-1 2j 1 + --W (28) I I' p '1+ Pj Pi MS \k~1 (29) ; - Fluid Flow 75 is called the stagnation pressure, and gives a measure of pressure energy. For incompressible flow P = P+ = p+g . (31) where ?=^pV> (32) and is the dynamic pressure. A total head tube measures stagnation pres sure directly. -.. From Equation 29 it follows that for frictionless, adiabatic flow . P = Pi0 . . (33) This represents another extension of the Bernoulli equation to compressible flow. Friction will cause a loss in pressure energy. Ideal Flow through .Nozzle or Orifice The majority of low-head measuring systems depend upon a correlation between pressure drop7 area, and quantity of flow. The basic formulas may be stated on the assumption that the flow is frictionless and adiabatic. Designating the main stream by station 1, and flow at some measuring restriction by station 2, the flow in pounds per second is to -- P1A1Vi = p>A,V, (34) or, in terms of Mach number, to = AtMi VkgptPt According to Equation 29 W 4 -- 1. 1 + ~-^MS 1+ (35) (36) from which MS = (37) so that = k-1 j/ 1---+---------- -?----MS` ./zfcjptpt-] V1 - MS/MS 4-1 l\pj J (38) MiIf the initial velocity is sufficiently small, will be negligible so that The quantity, P = P (l + * - * -']/ ifefGF KsF -r] If this is computed and the figures are plotted, the curved line (partly CHAPTER 4 solid and partly broken) of Fig. 6 is found. The maximum value of ^ may be computed by differentiating w with respect to p2 and equating -y the result to zero. This operation produces the formula: SR V1! (40) pi V* +1/ f For air, with k = 1.40, Pi = 0.53. Pi V? Actually, the broken part of the curve is not attained for the flow in I the nozzle. If the ratio of p2 to p2 is decreased from unity, the mass rate . of discharge, as well as the volume, increases from zero to a. maximum, as shown by the solid section of the curve in Fig. 6; thereafter, as p2/pi is decreased further, the discharge is constant, as indicated by the horizontal line. The value of p2 at the maximum point is called the critical pressure, or pc , and it is seen that p,, is approximately 53 percent of pi when air is flowing. & Fig. Relation of Flow of Gas to Pressure Drop in a Converging Tube To find the velocity at the critical pressure, it is assumed that the up- tstream velocity Vx is so small as to be negligible. Using the subscript I* c to indicate conditions at the critical point, from Equation 29 (41) I' or Me = % (42): Substituting the critical pressure ratio from Equation 40 it follows that || . Mc = 1 (43) f or that the velocity at the throat is equal to the local sonic velocity. M In developing the working equations'for orifices and nozzles, it is custom ary to start with the incompressible form of the flow Equation 38.. ;.-In' this case1 both Mi and M2 are'.small quantities, pi =. '--/pi)/,P.ir = Ap/p2 is small. Retaining only fimt order terms, it. follows frofiijEqua- tion 35 that . ` - . .. . . , : ... Mi M Mi= A, (44) so that k -1 1 +.---t-Mi1 i - ,=/*, -- Vi (Ai/AlY 1 (45) ; where 0 = D2/Di. The quantity 1/ vV -- |34 is the velocity of approach' t-JHN `ttl Jr* Wo- O d o $0.02 Dj W - SO.IOD, 11- 0.80 * 0.76 $0.72 . u ui 0.68 o 'O. 0.64 _A A| 0.70 5-10*2 0A0 030 0.20 O.fO 5 10* .0.05 <a03 Df- $0.03 Dt . pVlPl Fig. 7. Dimensions and Flow Coefficient for Standard Square-Edged Orifice with Corner Taps or Annular-Slits v , (Coefficient shown as a function of Reynolds Number and Ratio, A/A.) Note: From Reference 4. Used by permission. : pfactor as generally used, with being the ratio of the throat or orifice di ameter to the pipe diameter. Since Ap/p2 is small 5 and the mass flow is 2k fc_1LVV J~ Pi (46) The volume flow is. then V2spAp Vl-P4 (47) Q~At v'2^P'/p = 2Bh' (48) ill 78 CHAPTER 4 1956-Guide FLOW MEASUREMENT ,, The measurement of quantity of flow of fluids is generally accomplished either; by-making observations on the change of state due to flow system configuration, such as the pressure drop across a metering orifice, or by.the displacement of sOme device, such, as a rotating vane system. The selec tion of the metering system will be determined by the type of fluid, the precision of measurement desired, the cost of equipment and installation, the range of flow quantity, the ease of maintenance, and the method of observation and recording. Fluid meters may be classified as follows: (1) Head Meiers (Pressure Sensitive), which may be of Venturi, flow nozzle, orifice plate, or Pilot tube types; (2) Area Meiers, which may be of gate, tapered lube, or tapered plug types; (3) Force Meters, which may be of vane, propellor, or turbine types; (4) Quantity Meters, which may be of weighing tank, reciprocating piston, or gearedimpeller types, Rate meters are generally of the first three groups, although rates are Fluid-Flow Fig. 8. Dimensions for International Standards Association Flow Nozzle Note: From Reference 3. Used by permission of A.S.M.B. obtainable from timed observations of quantity meters. Similar quantityW measurements can be obtained by suitable integration of rate meter in-Sj dications. if Head Meters Jl The head meter is of sufficient flexibility so that almost any type of flow|f measuring problem can be handled. For this reason, standard and refer-: ence measurements are usually made in this way. With proper care, ex-;, treme precision can be obtained. Also, an inexpensive installation can bej made to give moderate precision. In general, a head meter requires fairly:; competent installation and maintenance to give satisfactory service. Among the types of head meters, the Venturi has the advantage of having a low pressure loss, but requires considerable length of space. The orifice^ plate reduces the required length to a minimum at the cost of considerable; pressure drop. The flow nozzle represents a compromise, but must b|L calibrated individually, or made with extreme care from standard specifica tions, to obtain a good precision of measurement. Standard configuration^* for representative orifice plates and flow nozzles, are shown in Figs. 7 an 8, respectively. Additional specifications are given in References 2, 3j and 4 at end of chapter. | The measurement of flow in head meters is dependent upon observation! 79 80 CHAPTER 4 of a static pressure difference between two parts of the system. Standard locations for these static pressure measurements are illustrated in Figs. 8 and 16. In general, there exists a reduction in area, either by a smooth contour as in the case of a Venturi or flow nozzle, or by a vena contracta following an orifice. In either case, the flow will be given by a suitable modification of Equations 47 and 48. Adding a correction term, these become a,c V 2ffpAp Vi - p (49) # J'/Sf . . ..... .( The coefficients K and C will be determined by the area ratio AJA2, or by'the diameter ratio Di/D2 and the Reynolds number. Extensive data are available from various sources.1-4 Figs. 9,10,11, 12 show repre sentative values of K based on NRe, the Reynolds number, and the ratio of diameter of the orifice or nozzle throat to pipe diameter. In any specific application, numerical values for areas, densities, and pressure units can be substituted in Equations 52 and 53 to obtain compact working formulas. In planning flow measurements, standard flow meter -;i M i' ii 'i Fig. 12. Flow Coefficient fob International Standards Association FlowII Nozzle Shown in Fig. 8 as a Function of Area Ratio (Di/Di)5 and.: the Reynolds Number Nr,, Note: From Reference 3. Used by permission of ASME m and AtC Q = Vw \/2ghi (S0)| In all cases, Ai refers to the minimum area of the Venturi, nozzle, orl orifice. The correction factor C is introduced to account for any loss due to departure from isentropic flow, and for any deviation between the; downstream measured pressure and the actual pressure at the minimum section. Since these corrections are usually dependent on configuration^ as described by the ratio of upstream to minimum area Ai/A2 , it is often convenient to introduce, a combined flow coefficient, K which is -' % ^ K Vl - f>` (51)1 so that w = KAt\/2ffpAp (4l 1195 --J L90 ----- v90----A \S $1Ti ---- AV LOO 03 l \! v rio. 13. Relation of Expansion Factor, <t>, for Nozzles to Diameter Ratio . and Pressure Loss for Air and Other Diatomic Gases dimensions and standard pressure tap locations should preferably be used so that published flow coefficients can be used for accurate determination of flow rates. In measuring the flow of compressible fluids, the approximate Equations 52 and 53 must be corrected for density variations. The need for such correction is evident by comparing Equations 35 and 38 with Equation 47. Introducing a multiplicative correction factor <j> the equation for flow with no loss becomes: . ' -- = Vl -- /S' * By comparison with Equation 35, ~ Pi) (54) * From Equations 34 and 35, A Pi - p) Y 2 pi (Pl/Pl) - 1 Mi'/Ms = 0(j 4 (55) (56) P' 1956'Guide I 82 CHAPTER 4 Hence, by Equation 38 for a small value of Mi, P ' * .y ww \k-\J (p,/p,) -ti-.fKpi/Pi)tt From,Equations 37 and 56,'if Ms-ia not too large, . Z .rA 4 Mf \pt / so that, approximately, . 1 - P'+ Hi - 2(4 - 2)p]Mf . - -m S ' 1' '(58) |j . -m: (59) fA Fluid Flow 83 practice, with reference to fittings and valves, is shown by- Fig. 1(5. If. these conditions cannot be met, some flexibility is possible by introducing straightening vanes, as described more fully in References 2 and 5. The static pressure difference across the head meter is measured by suitably located static pressure taps. For orifices, the different sets of pressure taps are called flange taps, radius taps, vena contracts taps, and pipe or full-flow taps.- The relative locations of the first three of these are shown in Fig. 16. - . : The flow coefficients in Figs. 9, 10 and 11 apply only to measurements made with these pressure tap locations. The need for applying suitable m fa -Hf 40, 3d 520! 2< 10 & 02 0.4 D*/D, . --. a- -- --B--1 - 40i - 30 </) *20 t bz<i 10 50 3 D./0, OS OS ' ' ` LOO W.SU ___ Fig. 14. Relation op Expansion Factpo2r/p, </>, fob Nozzles. to Diameter Ratiov|feJ and Pressure loss for Steam, Carbon Dioxide and Natural Gas Mj where to the same degree of approximation from Equation 36 '3.^3 .. ' ' ' . (60)f'^ 4pi .' ' - , . i, ' '-%r Values of ^ are also given by Figs.. 13 and 14. ^ While <f> may be used for smooth nozzles and Venturi tubes, it is necessary^ in the case of orifices, where the departure from ideal flow is significant,|| to replace <t> by an empirical factor Y obtained by the equation Y = 1- (0.41 + 0-35g')(P`-~ p* /kj (61F When this correction is used, the flow will be given by the equation w = KAiY\/2gpl(pi - pj Location of Head Meters and Pressure Taps In the installation of Venturis, orifices, and nozzles, care must be taken in regard to upstream and downstream flow conditions. Recommended- <40| H30 ho <40i .t B 02 0.4 06 D*/D| 08 0l2 0.4 D./D, Eig. 15. Minimum Conditions to be Observed When Installing Orifices and Nozzles Between Fittings and Valves coefficients to measurements obtained by means of the different taps, is indicated by the curve of change, in pressure of the flowing fluid, shown' in the lower part of Fig. 16. Pipe taps are located pipe diameters upstream and 8 pipe diameters.downstream (both distances being measured from the upstream face of the orifice plate) so that pressures are measured before the orifice plate has had any effect on the flow, and after the recovery in pressure has been completed. The use of pipe or full-flow taps has been limited to the metering of natural fuel gas in certain areas. As they are not suited to use in heating and ventilating work, no data for them are given in this chapter. Still another type of pressure tap, the corner tap, is used in European Practice. Pressures are taken from recesses in the flange connected to annular slits in the comers formed by the pipe wall and the orifice plate. 84 CHAPTER 4 Coefficients for these taps have been adopted by the International Standards Association, but are not used commercially in America. , It will be noted that the location of the downstream pressure tap of the vena contracta arrangement is variable. Vena contracta is the term applied to the minimum cross-section of the jet from the orifice, where the static pressure is at a minimum. Its location, and the location of the downstream vena contracta tap, vary with the ratio of orifice to pipe diameter, and with rate of flow, as shown in Fig. 17; the tap is generally located in accordance with the mean curve in the figure. Similar precautions are required when using flow nozzles and Venturi tubes. In many cases, these will be supplied ready for installation. In such cases, the manufacturer's instructions should be followed with care ^i.oo" flange" taps 1o3TOOSD|'I VENA CONTRACTA TAPS (SEE FIGURE 17) ............ i --. - i ii l i n n i.\ kumiss ri p-" " y|!| 1 J--------- D,-------- 0.5 Dr radius taps .7 1 Fig. 16. Relative Location of i* in order to avoid serious errors, given in References 2, 3, and 5. . 'is Further information on such systems is PitIont Tceurbtaein cases, such as in rectangular ducts, it is impracticable to use) standard orifices, and consequently, either a specially designed orifice* must be calibrated, or an independent flow device must be used. In eitherj case, the Pitot tube is useful. It consists essentially of an inner bent'tubef with its open end pointing upstream so as to measure total pressure, and S an outer tube having small holes on the side for communicating static pressure to a manometer. (See Fig. 3, Chapter 52). The difference inis liquid level in the manometer will be proportional to the square of they velocity, for incompressible flow, so that in general ! ^ (63)1 Fluid Flow 85 For compressible flow, the differential head is to be divided by the correc tion Fc from Equation 64, . - where ' Fo = 1 + 1M' + Att4 . (64) M' = 2 (65) In the usfe. of a Pitot tube system, care is required in obtaining correct total and static pressures. The total pressure tube must be smoothly, constructed; and should point directly upstream. The static pressure ' tap must be located so that local flow interferences will not reduce the value. In any case, it is better to obtain an independent calibration, or use a specially designed and manufactured probe. A number of such Pitot tube probes are available, and can be used without calibration. In using Pitot tubes to obtain flow rates, it is necessary to make a traverse`of the" pipe and thereby to obtain one op the profiles of Fig. 5. Fig. 17. Location of Vena Contracta in Relation to Ratio of Orifice to Pipe Diameter and to Rate of Flow - In rectangular ducts or near valves or fittings, a disturbed flow pattern would be obtained, and therefore, in such cases, a fairly complete survey should be made. The flow in such cases will be computed from the average of the local velocities, as obtained by Equation 63. Variable Area Flow Meters f or permanent installations where high precision, ruggedness, and ease of operation are important, the variable area flow meter has proved very satisfactory. Its most frequent use is in measurement of liquids'or gases in small diameter pipes. For ducts or pipes over 6 in. in diameter, the expense of this meter may not be warranted. In large systems, however, the meter might be placed in a by-pass line and used in conjunction with an orifice. In its most common form, the variable area meter, Fig. 18, consists essentially of a float which is free to move vertically in a transparent tapered tube. The fluid to be metered enters at the narrow bottom end of the tube and moves upward, passing at some point through the annulus formed between the float and inside wall of the tube. At any particular rate of flow, the float assumes a definite position in the tube, its location being indicated by means of a calibrated scale on the tube. : The position of the float is established by a balance between the fluid pressure forces across the annulus and the weight of the float itself. The buoyant force which must support the float, vi(pf -- p), is balanced by the pressure difference acting on the cross-section area of the float, At&p, where pi, At, Vt, are, respectively, the float density, float cross-section area, arid float volume. Accordingly, the difference in head across the annulus is given by Ap P|0>( ~ p) h, p Atp ' CAPACITY SCALt OR RtrCRCKCe ,, tapered TRANSPARENT METERING TU9? II Fig. 18. Schematic Diagram of Variable Area Flow Meter The volume flow follows from equation (53) as Q = KAt\/2gvi(pt -- p)/pAt and the mass flow as w = pQ -- KAi\/igvApt -- pVp/Ai The,flow for any selected fluid is, accordingly, very nearly proportional^ . to the area, so that a convenient calibration of the tube may be obtained.|f The behavior of the flow coefficient, K, has been investigated6 and the ac-J tion of. the flow meter as just outlined, experimentally confirmed. The fmloewtecrofeofrficdieifnfet rveanrtiaftluioidnsf.orSaonmyeflodeavt emloupsmt ebnetsknhoawven bineeonrdcearrrtioedusoenthinemjf the design of the float to reduce the variation of the flow coefficient withjf Reynolds number, and also with regard to float materials, to reduce thejl dependence of mass flow calibration on fluid density. ||| This type of flow meter is usually furnished in standard sizes calibratedj|| .Ml Fluid Flow 87 for specific fluids by the manufacturer. The compactness, reliability, and ease of installation are particularly advantageous when many measure ments of essentially the same type are to be made. J^ LETTER SYMBOLS USED IN CHAPTER 4 0 = ratio, throat or orifice diameter to pipe diameter. _ ft = absolute viscosity, pounds per foot second. r ft/p -- kinematic viscosity, square feet per second. !. " ' ' p -- density of flowing fluid, pounds per cubic foot. :. pm = proper mean density. ... p, -- density of water at 60 F (62.37 lb per cubic foot). : pf = density of float in variable area meters. tf> = expansion factor for nozzles. , a = velocity of sound, feet per second. A -- cross-sectional area of flow, square feet. P = correction factor (coefficient of discharge) for flow through orifice, nozzle or Venturi. . cp = specific heat of gas at constant pressure. ct *= specific heat of gas at constant volume. - ,/ D = diameter af fluid stream, feet. .' d = internal diameter of pipe, feet. ... ; . , da hydraulic diameter, feet. . . .. e = absolute roughness of pipe surface, feet. ^ F0 = correction factor for differential head in compressible flow. / = dimensionless friction coefficient. g = gravitational acceleration, feet per (second) (second). ge = gravitational conversion factor = 32.174 (pounds mass, per pound force) X feet per (second) (second). .. : A = enthalpy, Btu per pound of fluid. . Ar = loss of head, feet of fluid. . At = total head, feet of fluid. .< J = mechanical* equivalent of heat = 778 foot pounds per Btu; K = flow coefficient (correction factor), including velocity of approach correc tion factor, for flow through orifice, nozzle or Venturi. k = ratio of specific heat at constant pressure to specific heat at constant vol- L = perpendicular distance from axis of pipe, feet. .r l = length of pipe, feet. . M = Mach number. . .. = Reynolds number. p pressure, pounds per square foot. .. p *= stagnation pressure. ; pe = critical pressure. Q = discharge rate, cubic Teet per second. 4 q == heat transferred to the fluid per pound of fluid flowing. R = gas constant, r = radius of pipe in feet. s = entropy of fluid in Btu per (pound) (Fahrenheit degree). T = temperature, Fahrenheit degrees, absolute. u = internal energy, Btu per pound of fluid. V =* velocity, feet per second. Vc s= critical velocity, feet per second. v = specific volume, cubic feet per pound. . W = mechanical work, foot pounds per pound of fluid flowing. to = mass flow of gas, pounds per second. Y = expansion factor--correcting for expansion, of gas under reduced down- stream pressure. z = elevation above some arbitrary datum, feet. REFERENCES . 1 Friction Factors for Pipe Flow, by Lewis F. Moody {ASME Transactions, 66, {^>671-678; Discussion, idem. tffl,.1944, 678-684); also, An Approximate Formula Ior Pipe Friction Factors (Mechanical Engineering, 69, 1947, 1005-1006). CHAPTER 4 Mi-1 Fluid Meters, Their, Theory and Application (American Society of Mechanical Eng* iFnleoewrsM, 4eathsuEredmiteiontn, ,P,1o9w3e7r). Test Codes, Part 5, Chap. 4 (American I. Society . of-Me- ~~ chn*nSictaanl dEanrgdisnefeorrs,D1is9c4h9)a.rge Measurement (National Advisory Committee for Aero- nautics, NACA Tech. Mem. 952, 1940) (Translation of German Industrial Standard 1932). . 6 Gas Measurement Committee Report No. 2, Natural Gas Department (American Gas Association, 1948). * The Flow Mechanism and Performance of the Rotameter, by E. M. Schoenborn, Jr. and A. P. Colburn (Institute of Chemical Engineers, Transactions, 35, 1939, 359 381). -' jre pf f? f;1 ,|| '|'| Bi BIBLIOGRAPHY [A] Thermodynamics, by Edward F. Obert (McGraw-Hill Book Company, 1948). [B] Thermodynamics of Fluid Flow, by Newman A. Hall (Prentice-Hall, Inc., 195[C1)]. Fluid Mechanics, by Russell A. Dodge and Mi. lton J. Thompson (McGraw- Hil[lDB]oFolkuiCdoM.,e1c9h3a7n)i.cs, by R. C. B- inder (Prentice-Hall, Inc., 2nd.Edition, 1949). [E] The Physics of Solids and Fluids, by P. P. Ewald, H. Poschl and L. Prandtl (Bl[aFc]kAie,S1t9u3d6y).of the Data on the Flow of Fluids in Pipes, by Emory Kemler, Hy draulic Paper HYD-55-2 (A.S.M.E. Transactions 6B, No. 10, 7-22, 1933; Discussion, ide[mG.], TSBh,eNFolo. w10o, 2f 3F-l3u2id, s19in33C). losed Conduits, by R. J. S. P. igott (Mechanical Engi- fit^ neering SB, 1933, 497-501, 515). . || [H] Fluid Meters, Their Selection and Installation (American Society of Mechanical Eng[Iin] eTehrse, O19ri3fi3c)e. Meter for Measurement of Flow of Gases and Liquids, by ,Allen D. i MacLean (Pittsburgh Equitable Meter Co., 1938). (j [J] Pitot Tube Practice, by Edward S. Cole (A.S.M.E. Transactions 57, 1935, 281 294[;KD]isPciutosst iTounb, eidseimn.L6a8r,g1e9P36ip, e1s4,6b-1y56E)d. ward S. Cole and E. Shaw Cole (A.S.M.E _ Transactions, St, 1939, 466-473; Discussion, idem. 61, 1939, 473-475). [L] Investigation of Errors of Pitot Tubes, by C. W. Hubbard (A.S.M.E. Trans-?;*; . act[ioMn]s,P6i1p,in4g77A-4rr9a7n;gDeimsceunstssiofonr, Aidcecmep. t6a1bl,e19F3l9o,w4m97e-5te0r6A).ccuracy, by R. E. Sprenkle;; (A.S.M.E. Transactions, 67, 345-357,1945; Discussion, idem. 67, 357-360,1945). ! CHAPTER 5 HEAT TRANSFER , Conduction, Convection, Radiation; Equations for Conduction, Convection, Radi ation and Combined Convection and Radiation; Heat-Flow Resistance, in . Series and Parallel; -Practical Heat Transfer Problems; `. : Periodic and Transient Heat Flow . _ i. EAT is the form of energy that is transferred by virtue of an existing H temperature difference. The temperature difference is the potential which causes the transfer, the latter in turn being resisted by the thermal properties of the material combined in a single term known as the resist ance. Energy exchange associated with evaporation, condensation, etc., is treated elsewhere such as in the section on cooling tower design in Chapter 35. The objectives of this chapter are to; 1. Describe the mechanisms and present the rate equations for the different modes of heat transfer. .. 2. Illustrate the application of the basic concepts to steady-state problems (tem perature independent of time or a cyclic variable thereof) by means of several typical solutions of heat transfer systems. 3. Present concise summaries of available methods of analysis for transient and periodic heat transfer problems. Further applications to specific systems will be found throughout The Guide. . CONDUCTION, CONVECTION AND RADIATION . Thermal conduction is the term applied to the mechanism of heat trans fer whereby the molecules of higher kinetic energy transmit part of their energy to adjacent molecules of lower kinetic energy by direct molecular action. Since the temperature is proportional to the average kinetic energy of the molecules, thermal transfer will occur in the direction of decreasing temperature. The motion of the molecules is random; there is no net material flow associated with the conduction mechanism. In the case of flowing fluids, thermal conduction is significant in the region very close to a solid boundary or wall, for in this region the flow is laminar, parallel with the wall surface, and there are practically no cross currents m direction of the heat transfer across the solid fluid boundary. In solid bodies the significant mechanism of heat transfer is always thermal conduction. . Contrasted to the thermal conduction mechanism, thermal convection involves energy transfer by eddy mixing and diffusion1 in addition to conduction. This is shown schematically in Fig. 1 which exhibits transfer ri>m a pipe wall at surface temperature t, to a colder fluid at a bulk tem perature tf. (Bulk temperature is that which would be attained if the uid stream were drawn off at a certain section and mixed. It is therefore omewhat higher than the lowest temperature in the stream.) In the minor sublayer, immediately adjacent to the wall, the- heat transfer thCU^Sff thermal conduction; in the transition region, which is called e buffer layer, eddy mixing as well as conduction effects are significant; 90 CHAPTER 5 1956 Guide m. '.V? in the eddy or turbulent region the major fraction of the transfer occurs by eddy mixing. ' H rj In most commercial equipment the main body of the fluid is in turbu lent flow, and the laminar film exists at the solid walls only, as shown in Fig. 1, but in cases of low-velocity flow in small tubes, or with viscous liquids such as heavy oil (low Reynolds numbers), the entire flow may be laminar. In these latter cases there is no transition or eddy region. When the fluid currents are produced by sources external to the heat transfer region, as for example by a pump, the described solid to fluid heat transfer is termed forced convection. In contrast, if the fluid currents are generated internally, as a result of non-homogeneous densities arising from the temperature variations, the heat transfer is termed free convection. -V*l U is . In the conduction and convection mechanisms, the transfer of heat is (fit associated with matter. .For radiant heat transfer, however, a changer in '38j {Laminar region ^Buffer region " Eddy legion kP 1 `3*5. I Heat Transfer 9F- Expressions of conductivity used in the heating field are usually incon sistent in this sense, in that it is customary to refer to the conductivity per squarefoot but for one inch of thickness. This custom has been adopted for the reason that wall thicknesses are usually expressed in inches, whereas if expressed in feet, decimal or fractional thicknesses would result. When dealing with flat walls, no complication is involved in using the inconsistent expression of conductivity. However, where curved or spherical walls are concerned, considerable complication is involved. Therefore, in this discussion the consistent units of conductivity expressed in Btu per (hour). {square foot) {Fahrenheit degrees per one foot thickness) are used throughout. Conductivity values obtained from Chapter 9 or Table 1 in this chapter, must therefore be converted for use in the calculations of this chapter by dividing by 12. As an example, the conductivity of brick listed as 5.0 in Table 2 of Chapter 9, becomes 0.42 when used in the calculations of this chapter. _t, Fig. 1. Thermal Convection Conditions energy form takes place, from internal energy at the source to electromag- || netic energy for transmission, then back to internal energy at the receiver.'r|J The rate of heat transfer, corresponding to the three transfer mech- i|v: anisms previously described, may be expressed by three rate equations.^ These are similar to Ohm's Law for electrical flow, the current flow througho | a resistance being proportional to the potential. The convection andiS radiation flow rate expressions may be approximated by a potential (tem-.:ff; perature difference) and a resistance in order that heat transfer calculations. may be effected more conveniently and rapidly. | Thermal Conduction Equation ^ Equation ; 1 states symbolically that the thermal conduction per unit$8 transfer area normal to the flow, q/A, Btu per (hour) (square foot), is<M proportional to the temperature gradient (di)/(dL), Fahrenheit degrees per foot. The proportionality factor is termed the thermal conductivity, k, Btu.ijf per (hour) (square foot) (Fahrenheit degree per foot of thickness). . J* mi dL9., A` The minus sign on the right side of the equation is introduced to indicate^ positive transfer in the direction of decreasing temperature. Fig. 2 shows|jl the physical significance of the indicated quantities. ifs It should be emphasized that the thermal conductivity used should bef| expressed in consistent units; either using the inch or foot throughout. f Fig. 2. Thermal Conduction in a Flat Slab Also, it should be emphasized that in order to make the calculations, and applications consistent in this chapter, oil dimensions of thickness must be expressed in feet. Thermal Convection Equation - hit. -t,) (2) This rate equation states that the thermal convection per unit transfer area {q/A), Btu per (hour) (square foot) is proportional to the tem- Table 1. Approximate Unit Thermal Conductivities* Conductivity, k = Btu per (hr) (sq ft) (F deg per in.) Material Air............ Aluminum. . Brass (70 - 30) Cast-Iron. XPper.............. niass ___ 0.168 1416.0 720.0 336.0 2640.0 3.6-7.32 Material Lead.............. Nickel............ Soil................ Steel, mild. .. Water, liquid. 240.0 408.0 2.4-12.0 312.0 4.08 92 CHAPTER 5 . 1956'Guide .. perature difference (, -- ,) which is the. temperature of the surface less that of the fluid. The particular fluid temperature to use for a given system will be noted under the discussion of that system. The prQportionaiity factor is termed the -unit thermal convective conductance (sometimes called the film coefficient for convection), hc, Btu per (hour) (square foot) (Fahrenheit degree). Fig. 1 shows the conditions associated with con vection. The heat transmission by free or natural convection for objects sur- rounded by air can be conveniently expressed as in Equation 2a: A'i ?.. -3L. .ff (2a) where -- = heat transmission by convection, Btu per (squarefoot) (hour). A C -- a constant depending upon the shape of the surface. D = diameter of pipe or circular duct or height of vertical wall, inches. (Effect of diameter or height becomes constant at 24 in.). = average of wall surface and surrounding air temperature, Fahrenheit degrees absolute. 4, -- i, = temperature excess between wall surface and surrounding air, Fahren heit degrees. . ir J For horizontal cylinders, the value of C -- 1.02 has been well estab- Jja lished by various investigations. For vertical plates, the value of C = 1.39 has been fairly well established. Suggested values2 of C for hori- ;9: zontal plates warmer than the surrounding air are 1.79 when facing upward, Sfc and 0.89 when facing downward. ^ Problems in either forced convection or natural convection may be solved ^ by the simple first-power equation if the convection coefficient is expressed as a unit conductance: . q = K A (q -- f,) (2b) where q =* heat transmission by convection, Btu per hour. v A = surface area, square feet. . ti -- t3 => temperature difference between the'surface and the fluid, Fahrenheit degrees. ' => unit convective conductance, from Table 2, Btu per (square foot) fS (hour) (Fahrenheit degree temperature difference). ^ Thermal Radiation Equation ` f% ' The relation given by Equation 3 is applicable to systems in which -Ag radiant exchange takes place between the surfaces of solids, as schemati- .j. q, = <tA,FaFb (2V - T,V (3) |g cally shown in Fig. 3. Gaseous and luminous radiation are not considered M in this discussion. Equation 3 states that the net radiation per unit trans fer area of surface 1, qjA Btu per (hour) (square foot), which sees surface 2 through a non-absorbing medium, is proportional to the difference of the f CHAPTERS Cabs %- Approximate Unit. Conductances fob. 'riTMTMAh Convection fob Several Flow Systems (Concluded) ' . Stbtem! .. * Heat Transfer Equation* -.and rre Limits of Affucation REVEBt ence , ,. ; . ` i Same as Case 7. ,'Fobced CoNvflbUITON . ' : ' General Equation (laminar Flow) . Fot (?) <S00,000 Sameas Case7. - . . ' he (innte) ~ 2Aex ` Eqxtation for Air ' ' (Laminar Flow) _ ' _ hex = 0D562<ri) i- -- - For (--) < 500.000 Free Convection0 Equation for Atr -ojt,,(/Pk)\-w /VAdt)V* io> < jvGr < 10' Free convection past & heated horizontal cylinder._________________ IT i 1< Free convection past a single vertical sur face. .. 7-777-77-77L-- 1 --J Free convection past a heated horizontal surface (face up).__________________ . Equation for Air 10` < ArGt < 10' - -420 /PV" KfJ v/ r) 10 < JVGr < 10" Equationfor Air h" 0 478 GD'" (?)" J03<A^g?<ioj Eqxtation for Air 5 as >/.////// - 'V// . , *0>-< xGr <w Free convection past a heated horizontal surface (face down). * Fluid properties should be evaluated at the arithmetic mean fluid temperature, tf = << +1 divided by 2. , Sg b These expressions are suitable approximations to longitudinal flow in other than ripht circular cylinders,^ provided the hydraulic diameter is employed as the conduit dimension parameter. For non-circular engsg sections, the hydraulic diameter is equal to four times the cross-sectional area divided by the wetted penm^a c For low rates of heat transfer by free convection the exponent decreases towards zero, and for V18)?jjS rates, increases towards 0.33. The above equations employing an exponent equal to 0.25 are applicable in intermediate range indicated. NOMENCLATURE AND DIMENSIONS FOR TABLE 2 Cp = teat capacity at constant pressure, Btu per (pound) (Fahrenheit degree)^ D = cylinder diameter, feet. '.-rig / = subscript denoting film. jm Heat Transfer 95 g = body force per unit mass, feet per hour per hour. (For static system on earth, g = 32.2 X 3600* feet per hour per hour.) 6 = 3600 UmP = mass flow per unit cross-sectional area normal to flow, pounds per (hour) (square foot of flow cross-section). Nor = Grashof modulus, dimensionless (Nor = D^p'pAlg/u*). he = average unit thermal convective conductance from the leading edge of . surface to the position as, Btu per (hour) (square foot) (Fahrenheit degree). hex = local unit thermal convective conductance, at the position x from the leading edge of surface, Btu per (hour) (square foot) (Fahrenheit degree). k = thermal conductivity, Btu per (hour) (square foot) (Fahrenheit degree per foot thickness). . 2 = a dimension of the system, feet, m = a subscript denoting mean. P -- pressure, atmospheres. = pressure (atmospheric) atmospheres. . t = temperature, Fahrenheit. T = temperature, Fahrenheit, absolute. u = fluid velocity, feet per second. V = volume, cubic feet. x -- a dimension of the system, feet. . . 1 dV P = coefficient of cubical expansion <fi = y(jy)p); fr perfect gases p = 1/T. At = difference between wall and fluid temperatures, Fahrenheit degrees, p = fluid viscosity, pounds per (hour) (foot). . ". P density, pounds-per cubic foot. "o = infinity, referring the quantity to a point not directly affected by the phenomenon in question. Table 3. Radiation Factors ob Emissivities, t* For the determination of factor Fb in Equation S Crabs Subfaces Fraction of Black-Body Radiation ' At 50-100 F At 1000 F Absobftivtm fob Sodas Radiation 1 A small hole in a large box, sphere, furnace, or 2 Black non-metallie surfaces such as asphalt, car- 0.90 to 0.98 3 Red brick and tile, concrete and stone, rusty steel and iron, dark paints (red, brown, green, etc.).. 0.85 to 0.95 0.75 to 0.90 0.65 to 0.80 4 Yellow and buff brick and stone, firebrick, fire clay.......................................................... .................... 0.85 to 0.95 5 White or light-cream brick, tile, paint or paper. 0.50 to 0 70 6 0 85 to 0.95 0.60 to 0.75 0.90 to 0.95 Transparent* 7 Bright aluminum paint; gilt or bronze paint____ : 0.40 to 0.00 0.30 to 0.50 8 Dull brass, copper, or aluminum; galvanized 0.20 to 0.30 0.40 to 0.65 9 10 Highly polished aluminum, tin plate, nickel, chromium.......................................... .................... 0.02 to 0.04 O.O&toO.lO 0.10 to 0.40 * Emissivities of other materials may be found in Reference 4. - Reflects about 8 percent. fourth powers of the absolute surface temperatures (TV -- TV). The pro portionality factor' (oFjiFb) may be conveniently separated into three parts (excepting in some problems involving interreflections, where it is not possible to divide the product (FaFe) into separate terms): v " the Stefan-Boltzmann radiation constant = 1730 X lO-'1 Btu per (hour) (square foot) (Fahrenheit degree absolute temperature to the fourth power). Fa = the geometrical factor which is dimensionless and g 1. This factor accounts for the shape and relative position of the two surfaces. The value of Fa = 1 may be used in the cases of large parallel planes, long concentric cylinders or smaller bodies in large enclosures. Fb = the emissivity factor which is also dimensionless and S 1- This factor ac counts for the absorption and emission characteristics of the surfaces for the 96 radiation which exists. Emissivities or absorptivities (e) for many common surfaces, are given in Table 3. . The value of Fe for large parallel planes, long concentric cylinders, or large enclosed bodies is 1 + (1/ei.+ l/ -- 1). m The radiation under black-body conditions, or for an emissivity of 1.0, is given in Table 47 for cold surfaces as low as --39 F to warmer surfaces Ias high as 139 F. Some net radiation exchange solutions for several common radiation systems are given in Table 5. ,$i>4 There are several methods by which the geometrical factors FA can be determined. One method involves the use of a mechanical geometrical integrator (Reference 8). Photographic and other methods are given in References 9 and 10. Equivalent Conductance for Radiation Although Equation 3 is a suitable equation for' describing radiant exchange, it is not convenient for computations where other modes of energy transfer are operative. For such cases, it is convenient to define an equivalent conductance for radiation by the equation: ' if q, = h, A (ti -- tj) (4) Table 4. Heat Transmission by Radiation fob Black-Body Conditions* Temp F Deo 0 Expressed in Bin per (square fool) {hour) -1 -2 -3 -4 -5 --6 ' -7 -8 TZ 'I. i-9 K -30 -20 -10 0 59.3 65.2 71.4 78.0 58.7 64.7 70.8 77.4 58.2 64.1 70.1 76.7 57.7 63.5 69.5 76.0 57.2 62.9 68.9 75.4 56.7 62.3 68.3 74.7 56.2 61.7 67.7 74.0 65.7 61.1 67.1 73.4 55.2 60.5 66.4 72.7 54.7 . 59.9 65.8 72.1 & 9f "0 +1 +2 . +3 +4 +5 . +6 +7 +8 + 0 78.0 78.7 79.4 80.1 80.8 81.5. 82.2 82.9 83.6 84.3 10 85.0 85.7 86.5 87.2 88.0 88.7 89.4 90.2 90.9 91.7 20 92.4 93.3 94.0 94.8 95.6 96.4 97.2 98.0 98:8 99:8 30 40 100 101 102 109 110 111 103 112 104 112 105 113 105 114 106 107 115 116 108 117 50 118 119 120 121 122 123 123 124 125 126 60 127 128 129 130 131 132 133 134 135 138 70 80 137 138 148 149 139 140 142 150 151 152 143 153 144 154 145 146 155 156 147 ` 157 90 100 159 170 160 171 161 173 162 174 163 175 164 176 166 178 167 179 168 180 169 182 110 120 183 196 184 185 187 188 189 191 197 199 200 201 203 204 192 193 206 .207 195 209. 216130 211 212 214 217 218 220 221 222 224 * Example: Radiation from walls of room at 32 F to surface a* -25 F for effective emissivity of 0.95 (102 -- 62.3) 0.95 = 37.7 Btu per (square foot) (hour). Heat Transfer 97: System Table 5. Net Radiation Solutions Solution Remarks ifl| 2 Two infinite parallel planes. a[Ti*__Ts*) (Considering interreflectio&s. A. I+-^l * (Reference 6) i e4 e3 1* 2 A " (2)1 , 1 O' e "<r`* 1 T*)\ Considering interrefiectiona (Reference 5) One radiation shield between two infinite parallel planes. Ml B J__AA A Considering interrefiectiona. 1 (Reference5) t; : where is the net radiation ex-| h radiation shields between two infinite parallel planes. . change without the shields. O Vo At\*t IConsidering interrefiectiona 1 and diffuse surfaces. (Ref erence 5) . . Two concentric spheres or two infinitely long cylinders. . " tPa(Ti* - 7V) Surface diffuse, neglecting interreflection. . (Refer! ence 5) Two areas dAi and dA* :OI` ' TMtef^Ifinite `ength Pan*llel * ' (0!ir = Neglecting interrefiectiona. - rt) 1 (Reference 5) [where N is the length of cylinder! from which Qr is exchanged /~ ^7 ' Surfaces are perfect radi-j ators. ' ^ ant* -a"4 rectangle above taongle contained in noormneacl otorndeAr o. f reo* Surfaces are perfect raJ diators. See Fig. 4 See Fig. 5 (Reference 4) (Referenced) rectangles in perpendicular Surfaces are perfect ra-l diators. eSHS.1d.!jJrallel rectonles and disks of See Fig. 6 (Reference 4) 1 98' CHAPTERS 1956 Guide Fro. 4. Geometrical Factob F Fob Direct Radiation Between an Element dA and a Parallel Rectangle* Heat Trausfer 99 i The conductance hz thus defined is a function of the shape-emissivity factor, as well as the temperatures of the radiator and receiver. Fig. .7 shows a plot of the equivalent conductance for two black bodies (t.e., -with emissivities equal to unity) which exchange energy only with one another. Combined Convection and Radiation . It should be noted that the previous equations and tables give the heat transfer by convection and by radiation computed separately. In many practical cases it is desirable to treat convection and radiation as a angle combined process, using a first-power equation: ?ro " hre A (ti -- /,) , (5) where is the total heat flow due to radiation and convection, in Btu per hour. Values of Arc, the surface or film conductance for combined Fig. 5. Geometrical Factor F for Direct Radiation Between Adjacent Rectangles in Perpendicular Planes* , Fig. 6. Geometrical Factor F fob Direct Radiation Between Opposed Parallel Rectangle and Discs of Equal Size* -------------- t, ... . . . ,, ( Hnttel fMechanical Engineering, July 1930, pp. 700 to 703) FromRadisut Heat Transmission, by H. O. Hottel liueammau m Fig. 7. Equivalent Conductance fob Radiation Between Two Black Bodies Exchanging Enebgf Only with One Another radiation and convection, are given in Chapter 9, (Table 1 and Fig. 4). Complete tables for the combined heat transfer of steam and hot water radiators, pipes, coverings, etc., will be found in the appropriate chapters. HEAT-FLOW RESISTANCE In most of the steady-state heat transfer problems encountered in air conditioning applications, more than one of the heat transfer mechanisms are effective, and the thermal current flows through several resistances in series or in parallel. In using the resistance concept, the calculations in volved are analogous to the application of Ohm's Law in electricity, viz., the heat flow or thermal current is directly proportional to the thermal potential or temperature difference, and inversely proportional to the thermal resistance: h -1, 9r = R (6) 100 CHAPTER 5 1956 Guide Following the electrical analogy, when there is a thermal current flowing through several resistances in series, the resistances are additive: Ri t- Rt -4- Rt + * + Ra (7) Similarly, conductance is the reciprocal of resistance, and for heat flow through several resistances in parallel, the conductances are additive: Ct Rt R, + R, + R.'++R. (8) M Practical Heat Transfer Problems The use of these relations for resistance and conductance makes pos sible the solution of many practical heat transfer problems. As discussed in Chapters 9, 28 and 36, the practical analyses of heat transfer in building walls, in fin-tube coils and in pipe coverings, are usually computed by this Ifmethod.. The same resistance analysis may be applied to complicated Heat Transfer 101 Table 6-Solutions for Some Steady-State Thermal Conduction Problems*. * No. System `he rK,iStaI,C<J R "* -to __ __________? ~ At/A (Jbttu per hour) " curved wall if curvature is small OralUJuckness less than 0.1 of inside dia- R=-- kJ Surface area, A Radial flow through a right circular cylinder. ,Ot ' Long cylinder of length, N" ^ R --------- D 2rkN (See footnote c). Long cylinder 'TVJ of length, N flow in a hollow sphere. lOg* R" + tokN CCBh-l = Ttk# For ^ ^ 3, satisfactory approximation is: Ioge coeh~l - K> -- T 9 2**iV 2rkN~ 1l n _ro Ark Fig. 8. Heat Transfer Conditions in an Insulated Cold Water Line steady-state conduction problems. Table 6 gives the resistances in six common cases of steady-state conduction. A complete analysis by the resistance method is well illustrated by considering the heat transfer from the air outside to the cold water inside of an insulated pipe. The temperature gradients and the nature of the resistance analysis are indicated by the two sketches of Fig. 8. Since air is sensibly transparent to radiation, there will be some heat transfer by both radiation and convection to the outer insulation surface. The mechanisms act in parallel on the air side. The total transfer by radiation and convection then passes through the insulating layer and the pipe wall by thermal conduction, and thence by convection and radiation into main cold water streams. (Radiation is not significant on the water side as liquids are sensibly opaque to radiation, although water transmits? energy in the visible region). The contact resistance between the insula-, tion and the pipe wall is presumed to be equal to zero. . Referring to Fig. 8, the heat transferred for a given length N of pipe,; 5rc, Btu per hour, may be thought of as flowing through the parallel resistances R, and Rc, associated with the insulation surface radiation and convection transfer. Then the flow is through the resistance offered to thermal conduction by the insulation, Rz, through the pipe wall resistance,, The straight fin or rod heated at one end. . Conduction i , ' cross-section j _______ area, A ^ambient Finned surface of area HB. R~ m hap tanh mL; (see-footnotes d and e). For nti > 2.3, tanh wl = 1 m ~\/hap/kA ' A ~ conduction cross-section area. p = perimeter of croes-section A. A# =* unit conductance to the surroundings from the fin surface. _ A -- thermal conductivity fin material. At = wall temperature--ambient temperature (# + *) ' (~ tanh ml + ,) HB \/y At defined as in Case 5 above. ox The("dimhte)ns(sioqnusatroe fboeoet)m(pFloayherdeninhetihtedseegsreoeluftoiornosnaerfeo:oltenthgictkhnoefssd)i;muennistsionofpA, ,LB,tru=pefere(th; ouunri)ts(soqf ukar=e> (Fahrenheit degree); units of area, A -- square feet. The thermal conductivity, k, in these solutions should be taken at the average material temperature. * hoge x = 2.303 logio *. ' . hi. This expression can also be employed as an approximation for tapered fins or of annular fins by emp ymg average magnitudes of A and p. e tanh is the hyperbolic tangent. . Heat Transfer 103 ft2, and into the water stream through the convection resistance, fti. Note the analogy to the direct current electrical circuit problem. A temperature (potential) drop is required to overcome these resistances to m the flow of thermal current. The total resistance to heat transfer, .ft,, hour Fahrenheit degrees per Btu, is the summation of the individual resistances: ' . i&i TfS Rt = Ri -h Rg ~t~ Rj ~h R4 'M (9) where the resultant parallel resistance ft, is obtained from 1 R, ' Rr + R. (10) Provided the individual resistances may be evaluated, the total resistance can be obtained from this relation. Then the heat transfer for the length si of pipe (N, ft) can be established by the relation m (to - ft) q,, (Btu per hour) = Rr (ID For a unit length of the pipe the heat transfer rate is The convection resistances to heat transfer from the pipe wall to the cold water, fti, and from the air to the surface of the insulating, material, Re, are dependent on the flow conditions prevailing at these surfaces, and on the thermal properties of the fluids. These resistances are also directly dependent upon the temperature distribution, and for this reason it is necessary first, to guess on the basis of the problem statement, a tempera ture distribution upon which to base the initial calculations. Since the values of hc for heat transfer between water and pipe walls are relatively high in this temperature range, it is logical to assume only a small tempera ture difference between the temperature of the fluid body and the tempera ture of the pipe wall. For the purpose of an initial guess, this temperature difference will be assumed to be 2 deg. On the other hand, h0 for heat transfer from air to a body is relatively small, and a higher temperature difference would be expected between these masses. The value initially assumed here will be 20 deg. In summary, the temperature distribution in the system is assumed as follows: . Fluid temperature = 34 F. .. . Inner pipe wall temperature = 36 F. Outer insulation surface temperature = 100 F. Ambient air temperature = 120 F. (to - td ^ Btu per (hour) (foot) = N RtN (12) The temperature drop, At, through an individual resistance may then be With these assumptions and the problem statement, it is now possible to calculate values for the convective resistances. If it is found in the ultimate solution of the problem that the temperature distribution is different from that assumed, it will then be necessary to repeat the solution procedure. calculated from the relation: ; * At = R If reference now be made to Table 2, it is found that Case 3 of this table (13) is a system similar to that encountered in the convection between.-the water and.the pipe wall. The equation for this case is the following:; where ft is the resistance in question. ' The problem is now reduced to one of evaluating the individual resist ances of the system. This entails suitable manipulation of the rate Equa ho (15) tions 1, 2 and 3 to produce expressions of the form: . where At q=R (14) where q is the heat transfer rate, and At is the potential drop or tempera- 1 ture difference through the resistance ft. Table 6 lists such solutions for six different conduction systems. Table 2 in Chapter 9 and Table 1 of } this chapter indicate the magnitudes of the thermal conductivities, k, to ; be employed in the expressions of Table 6, after dividing fc by 12. The solution applicable to the problem depicted in Fig. 8, for the cal culation of fti and ft, is case 2 in Table 6. Thus for a 1 ft length of- 2 in. nominal size pipe (I. D. = 2.067 in., O. D. = 2.375 in.) insulated with , 1 in. of material having a conductivity of 0.025: ' Ua = 5 fpS 2.067 D= 12 0.1725 ft 34 + 36 k= 35F h. = 139 X 6'9-^ ~62 = 494 Btu per (hr) (sq ft) (F deg). 0.7UO . '. This heat transfer rate is through the inner surface of the pipe and it is, therefore, this area that determines the resistance ftj. 1.188 log. Rt = 2ir X 1.033 26 X 1 = 85 X 10~* (hr) (F deg) per Btu. 2.188 loS 1,188 R. = 3.9 (hr) (F deg) per Btu. 2. X 0.025 X 1 and therefore A = vD = 0.542 sq ft per unit length of pipe, heA " 494 x 0.542 Ri = 3.73 X 10~* (hr) (F deg) per Btu. . 1 Case il of Table 2 fits the conditions of the problem if only free convec tion heating of the pipe is assumed. The equation in this case is;as follows: 0*(sr( P ft* = 0571 ^ (16) mi where therefore. At = 20 F D = 0.364 ft P = Pa = one atmosphere 0-0m{/ ^20 \oa ill ft* = 0.737 Btu per (hr) (sq ft) (F deg). ' Using the surface area of the insulation, the value of the resistance per unit length is determined. /4.375\ X 1 = 1.14 sq ft 1 B. = ft*A 0.737 X 1.14 . . B* = 1.19 (hr) (F deg) per Btu. This result may not be deemed conservative inasmuch as the expression is for still air. If, however, the air is not still, but flows at approximately;5 mph or 7 fps, the heat transfer equation for forced convection would apply. This equation is Case 5 of Table 2. ^ e(&Ttnta) /(u p\)A0-8B 0.211(T,)"u-^7- , (17) Ti 100 + 120 + 460 = 670 Rankine (Fahrenheit absolute) = 7 fps /520\ P = 0.0761 -- 1 = 0.0694 lb per cu ft and Z> = 0.364 ft 0.211(570) u(7 X 0.0694)- Ag(annge) : (0.364)'* 2.73 Btu per (hr) (sq ft) (F deg) "c(avens*) ' 11 B. (Forced Convection) ' ft*+ 2,73 X 1.14 ft. *,<s Jp p'~. B* 0.321 (hr) (F deg) per Btu. The radiation resistance, R,, which acts in parallel with the resistance!^; just calculated, can be computed with the aid of Fig. 7. The pipe wall,iS assumed at 100 F sees the surroundings at 120 F. If these two tempera-,|| Heat Transfer 105 tures are used with Fig. 7, a value for _ is determined directly. f1 APE ',, , , . . , - Fa^e = 1-4 BtU per ^ (8a- ft)' The angle, factor, FA, is unity, and for an estimated surface emissivity of 0.95 (see Table 3), Ff. = 0.95. Therefore, , . ft, = 1.4 FaFe = 1.4 X 1 X 0.95 . ' ft, .= 1.33 Btu per. (hr) (F deg) (sq ft) and the radiation resistance, Rr, is then the following: ' 11 . B, h,A 1.33 X 1.14 Br = 0.659 (hr) (F deg) per Btu. ' The resultant resistance of Re and Rr acting in parallel (see Fig. 8) can now be evaluated as: ; + R, R, = 0.216 (hr) (F deg) per Btu. The overall resistance, Rt, surroundings to cold water, is the sum of Ri -j- Ri + Rs + Rt = 4.12 (hr) (F deg) per Btu for 1-ft length of pipe. Note that the controlling resistances are #3 and Rt, and that neglect of both Bi and Ri would not significantly influence the total resistance, Rt. On the basis of this resistance calculation, the heat transfer from the surroundings to the cold water may be evaluated as: . ^ = ^ = ^ = 2o.8Btuper(hr)(ft) or about 0.175 tons of refrigeration per 100 ft of pipe. Since the calculation is based on a 1-ft pipe length, - g,, = 20.8 Btu per hr.' The temperature drops through the various resistances are now readily evaluated by Equation 14 as: . . - ... at = qR " t> -- ta (air to insulation surface) = qRt = 20.8 X 0.216 = 4.49, F deg , , -- la (through the insulation) = gB> = 20.8 X 3.9 = 81.2 F deg . * -- hi (through the pipe wall) = qRt = 2)5 X 8.5 X 10-* = 0.018 F deg -- ti (pipe wall to cold water) = qRt = 20.8 X 3.73 X 10'* => 0.078 F deg . .This solution was obtained on the temperature distribution assumptions initially made. It is apparent that a better solution could be obtained if the whole problem were reiterated using the temperature distribution just calculated. 106 CHAPTER 5 1956 Guide PERIODIC AND TRANSIENT HEAT FLOW . The foregoing data and examples dealt with steady-state heat transfer (not varying with time). In most practical heat transfer problems the heat flow depends upon time. Such cases can usually be divided into two classes : periodic and transient. Periodic heat transfer repeats periodically in time: Transient heat transfer exhibits no periodicity. Graphical* ana lytical and numerical methods are available for solving transient or periodic heat flow problems.4-6-10-11,12 Graphical and numerical methods are the most versatile, and can be applied with minimum mathematical training. A large number of analytical solutions for the case of heat conduction in variously shaped solids are available in the literature. Table 7 gives a m s it I M] ssl Fio. 9. Example op a Graphical Solution to a Problem in Transient Heat Conduction. summary of the cases reported and tabulated. `Many more analytio&l solutions are available in the form of infinite series,11-12-18-10 but are not: tabulated. Certain complex cases may be treated by combining the simple analytical solutions as discussed ih Reference 17. (See also Reference 20). Frequently, transient heat flow problems in one dimension have boundary conditions which make the problem difficult to treat analytically. In such cases, recourse may be made to a graphical method of solution sometimes ; called the Schmidt method.4-10-19-21-22 This method will be briefly outlined ; for the case of transient heat flow in a slab insulated on one face, and; suddenly-exposed on the other face through a fixed thermal resistance to a) higher temperature. The technique is general, however, and methods may1 be devised for any boundary conditions,6-21 and also, for one dimensional', (radial) heat flow in spheres and cylinders.2222 . Heat Transfer 107 Table 7. Analytical Solutions for Heat Conduction in Variously Shaped Solids - Shape op Solid Semi-infinite Bo undart Conditions Data Available in Graphs Surface temperature changed. suddenly Temperature distribution in solid as a function of time. References: (4) p.37,(5) p. V-28; (10) p, 254; (13) p. 46. A steady flow of heat is suddenly applied to the surface. The surface temperature has been varying sinusoidally with time for a long time. ui uuie. - -. References: (10) pp. 256,267; (13) p. 47. Temperature distribution as a func tion of time. Reference: (10) p. 257. Temperature distribution as a func tion of time. . Reference: (10) p. 296. .. Semi-infinite with free surface. fluid, at' The temperature of the fluid in con tact with the surface has a sudden change in temperature. (Thesur- ' face conductance is oonstant). Heat flow from surface as a function of time. Reference: (10) p. 296. Temperature distribution as a func tion of time. References: (4) p. 37; (5) pp. V-45,46, The temperature of the fluid in con tact with the surface has been varyi ng sinusoidally with time for a long time. (The surface con ductance is constant.) The temperatures ti and h are sud denly changed from the initial uni form slab temperature to a new temperature. (The case where the surface on one side is insulated is fayated by taking the ease ol aslab of twice the given thickness since the midplane has no beat flow due to symmetry.) Temperature distribution as a func tion of time. Reference: (10) p. 298. Heat flow from the surface as a func tion of time.. Reference: (10) p. 298. ` ` ' ' ' Temperature distribution as a func tion of time.' References: (5) p. V-12; (10) p. 265. The temperatures ti and h suddenly begin to increase as linear func tions of time. The slab is in- at u"form temperature. Ube case where one surfaoe is insulated against heat flow is treated as noted above.) Temperature distribution as a func tion of time. Reference: (10) p. 268. The temperature at both surfaces has been varying sinusoidally for a long time. Temperature distribution as a func tion of time. Reference: (10) p. 300. Slab immersed in a fluid with constant conductance be tween fluid and slab surface. n% hc ik* The temperature of the fluid is sud denly changed from the initial uni form slab temperature. (If one surfaoe is insulated against heat flow, see above.) Heat flow from the surface. Reference: (10) p. 303. Temperature distribution as a func tion of time. References: (4) pp. 32, 33, 34, 35; (5) PP- V-9,10, 35, 42; (10) pp. 274, 284; (13) p. 106. The temperature of the fluid at one surface varies as a periodic func tion of time while the temperature of the fluid at the other surface is constant. The conductances need not be the same on both sides. (The variations in temperature are expressible as a Fourier series.) Heat flow from the surface as a func tion of time. References: (5) p. V-10; (10) p. 274; (13) p 107. Temperature distribution as a func tion of time. Reference 14. ' Heat flow at the surface as a function of time. - -- Reference 14. 1956'Guide 108 CHAPTER S Table 7. Analytical Solutions fob Heat Conduction in Variously Shaped . Solids (Concluded) / Shape of Sous Cylinder o! infinite axial di mension . Boundaby Conditions The surface temperature is suddenly changed from the initial (uniform) temperature. ' Data Available in Graphs Temperature distribution as a func tion of time. Reference: (10) p. 266. . Heat flow from surface as a function of time. Multiply temperature difference be tween surface and fluid 6y surface conductance. The surface temperature suddenly begins to increase linearly with time. . The surrounding fluid suddenly Cylinder of infinite axial di- , changes from the initial (uniform) ' mension immersed in a 1 temperature of the cylinder. fluid. Temperature distribution as a func tion of time. Reference: (10) y. 269. ______________ -- ---------------------------Temperature distribution as a func tion of time. . References: (4) p. 36; (5) PP- V-35, V-43, V-48; (10) pp. 278, 286, a:' (15). -pE Heat flow from the surface as a JuneH^LSwp.V-16; (10) P- 278. The temperature of the surrounding fluid changes sinusoidally. Temperature distribution as a func tion of time. Reference: (6) p. Vl-34. ;. Heat flow- from the surface as a /line- tionoftime. Reference: (5) p. VI-36. The temperature of the surface is 1 suddenly changed from the initial uniform temperature. Temperature distribution as a funcMerenT(5) p. V-23; (10) PP-264, .265. VV- V # The temperature at tbe surface sud- ( denly begins to change as a linear function of time. . The temperature of the surrounding fluid suddenly changes from the initial uniform s phere temperature. tion of time. Reference: (10) p. * Temperature distribution as a func tion of time. References: (4) p. 36; (5) pp. V-21, V-35, V-44; (10) pp. 281, 282; (4). L lA**" Heat flow as a function of time. References: (5) p. V-21; (10) p. 281. Rectangular bar of infinite length. Any of the above noted boundary conditions for a slab. Temperature distribution as a func tion of time. Combine solutions as indicated in Refs. 16 aDd 17. Parallelopiped (rectangular) Cylinder of finite length. Any of the aWe noted boundary conditions for a slab. Temperature distribution as a func tion of time. ` Combine solutions as indicated in Refs. 16 and 17. I Temperature distribution as a fun</ Any of the boundary conditions given above for a cylinder and a 1 tion of time. Combine solutions as indicated' in slab. Refs. 16 and 17. Hollow cylinder of infini te ex terior radius. The temperature of the surface sud den) y changes from the initial (uniform) temperature. Temperature distribution as a func tion of time. .# Combine solutions as indicated in Refs. 16 and 17. I Heat flow at the surface as a.func- I tion o! time. I Reference: (10) p. 267. Consider the slab to be divided, as shown in Fig. 9, by n equidistant planes parallel to the slab surface and a distance Ax apart. Let the tem perature of the slab at any plane and any time (0) be denoted by Tz,eThen the temperature of the slab at the two adjacent planes at th& same Heat Transfer 109 time will be denoted as 7W4.,i> and In a similar manner the temperature of the x plane at a time A0 later will be In accordance with this nomenclature, the temperature at any plane * and time 0 + A 0 is given as m T(r+As,0) + T(s--Aa.ff) T(i,+A) -- ------------------------------------------ (18) which may be interpreted as follows. The temperature of the slab at any plane, x, and any time, 0, is equal to the average temperature of the two adjacent planes obtained at the time (0 -- A0). The time interval A 0 is determined by the equation Jp . Ax* A0 = --- 2o ' , . (19) Omitting the graphical construction at the slab boundaries, reference to Fig. 9 demonstrates the graphical method by means of which the tempera ture at each plane is determined at successive intervals of time in accordance with Equation 18. For the problem stated, the boundary condition at the insulated surface is specified by theequation ' dT 0 dx and at the uninsulated face by the equation h(T,, -- T) = --k~. 0s In terms of finite differences these two equations (employing nomenclatun. established by Fig. 9) become . and Tf -- Te = 0 or Ty = Te at. x = L Az - (Tb - 7V) MT. TV) = --it at x = 0 TV - Tb k/h Az The details of the graphical construction are best obtained by inspection of Fig, 9. Note that tbe line (0,0,0') used to initiate the graphical con struction, is the only one drawn to the slab boundary A'. The numbered points indicate temperatures at the sub-slab boundaries at 1,2,3, etc., time intervals (A0) after the slab is exposed to the high temperature. For transient heat flow in two dimensions, and also, for steady state conduction, numerical methods of solution are available in the litera ture.6'10-12'19 These numerical methods are applicable to three dimensional problems, although the calculations involved normally become too tedious for most applications of the method. An additional technique of solution for one and two dimensional problems in transient conduction results from 110 CHAPTER 5 1956 Guide the analogy of electrical resistance-capacitance networks to thermal systems.*4 ' For two dimensional problems in steady state conduction; additional techniques of solution are found in flux plotting,4,19 and in the use of a potential tank.9,19 These methods sure of most direct use in problems in which the boundaries of the two dimensional shape are made up of isothermal and adiabatic surfaces; REFERENCES 1 Absorption and Extraction, by T. K. Sherwood (McGraw-Hill Book Co., Inc., 1937). . '' I The Transmission of Heat by Radiation and Convection, by Griffith and Davis (Special Report No. 9, 1933, Department of Scientific and Industrial Research. His Majesty's Stationery Office, London, England). 7 A Method of Correlating Forced Convection Heat Transfer Data and a Compari son with Fluid Friction, by A. P. Colburn (American Institute of Chemical Engineers Transactions, Vol. 29, 1933, p. 174). . 4 Heat Transmission, by W. H. McAdams (McGraw-Hill Book Co., Inc.). 4 Beat Transfer Notes, by L. M. K. Boelter, V. H. Cherry, H. A. Johnson and R. C. Martinelh (University of California Press, 1946). * Heat Transfer by Free Convection from Heated Vertical Surfaces, by V. S. Touloukian, G. A. Hawkins and M. Jakob (A.S.M.E: Transactions, 1948, p. 13). 7 Heat Insulation in Air Conditioning, by R. H. Heilman (Industrial and Engineer ing Chemistry, Vol. 28, July 1936, p. 782). 8 Photoelectric Photometer for Rapid Comparison of Two Light Sources, by L. M. K. Boelter, J. T. Gier and F. A. Ryder (Illuminating Engineering Society Transac A is'* i 4.1'i. ir,- tion"s,S1c9ie3n9t)i.fic Basis of Illuminating Engineering, by Perry Moon (McGraw-Hill Book Co., Inc., 1936). . 10 Beat Transfer, by Max Jakob (John Wiley and Sons, Inc., Vol. I, 1949). II Numerical Methods in Engineering, by L. E. Grinter (The MacMillan Co., 1949). a Numerical Analysis of Beat Flow, by G. M. Dusinberre (McGraw-Hill Book Co., Inc1.7,1E9le4m9e),nts of Beat Transfer and Insulation, by Max Jakob (John Wiley and Sons, Inc., 1942). 14 Periodic Heat Transfer at the Inner Surface of a Homogeneous Wall, by H. A. Johnson (A.S.H.V.E. Transactions, Vol. 54, 1948, p. 143) " Temperature Charts for Induction and Constant Temperature Heating, by m m. m m f M. P. Heisler (A.S.M.E. Transactions, Vol. 69, 1947, p. 227). 71 Temperatures in Solids During Heating and Cooling, by F. C. W. Olsen (In dustrial and Engineering Chemistry, Vol. 34, 1942, p. 874). IKi 17 Applied Mathematics in Chemical Engineering, by T. K. Sherwood and Charles E. Reed (McGraw-Hill Book Co., Inc., 1939). " Introduction to the Mathematical Theory of the Conduction of Beat in Solids, by H. S. Carslaw (Dover, 1945). w 19 Beat Conduction, by L. R. Ingersol], A. C. Ingersoll and O. J. Zobel (McGraw- M Hill Book Co., Inc., 1948, p. 209). 70 Charts for Estimating Temperature Distribution in Heating or Cooling Solid , -. Shapes, by H. P. Gurney and J. Lurie (Industrial and Engineering Chemistry, Vol. ijvnV 15,1923, p. 1170). 171 Applied Mathematics in Chemical Engineering, by T. K. Sherwood (McGraw-Hill Book Co., Inc., 1949, p. 241). . 77 Methods graphiques pour l'etude des installations de Chauffage et de refrigera tion en regime discontinu, by A. Nessi and L. Nissolle (Dunod, Paris, 1949). . 77 Transient Heat Conduction in Hollow Cylinders after Sudden Change of Inner- lSurface Temperature, by R. L. Perry, and W. P. Berggren (University of California 4*! Publications in Engineering 5, Vol. 59, 1944). . 74 Method for Determining Unsteady-State Heat Transfer by Means of Electrical u MAnalogy, by V. Paschkis (A.S.M.E. Transactions, Vol. 64, 1942, p. 105). ti CHAPTER 6 PHYSIOLOGICAL PRINCIPLES Chemical Vitiation of Air, Physical Impurities in Air, Thermal Interchanges Between the Body and Its Environment, High Temperature Hazards, Acclimati zation. Upper Limits of Heat for Men at Work, Application of Physiologic Principles .to Air Conditioning Problems, * Effective Temperature Index and Comfort Zones '- ENTILATION is defined in part as the process of supplying air to,, V or removing air from, any space by natural or mechanical means. The word in itself implies quantity, but air must be of the proper quality also'. The term air conditioning in its broadest sense implies control of any or . all of the physical or chemical qualities of the air. The A.S.H.V.E. Code of Minimum Requirements for Comfort Air Conditioning1 defines it "as the process by which simultaneously the temperature, moisture content, movement and quality of the air in enclosed spaces intended for human occupancy may be -maintained within required limits. If an installation . cannot perform all of these functions, it shall be designated by a name that describes only the function or functions performed." CHEMICAL VITIATION OF AIR People living indoors bring about certain physical and chemical changes., in the air about them. The oxygen content of the air diminishes and the. carbon dioxide increases, but these changes are too slight to be significant, except in air tight spaces as in submarines. Organic matter which is usually perceived as odors, comes from the body or clothes. Moisture* and heat are given off by the body. There is no evidence of any toxic volatile material given off by man to the ambient air. Stale air may be offensive because of odors and may induce loss of appetite and loss of energy. Objectionable body odors have the same effects. These reasons, whether esthetic or physiological, usually make it desirable in the design of air conditioning systems to provide for the elimination or control of" odors, arising, from occupancy, cooking, or other sources. This .may be accomplished by introducing odor-free air in sufficient quantities to reduce odor concentrations by dilution to a level which is not objectionable. Odor-free air may be outdoor air or air which has been cleared of odors by sorption, washing, or other appropriate means. In the case of vitiation by a few hazardous gases such as carbon mon oxide from heating, cooking, and certain industrial processes, no satis factory chemical treatment for the elimination of the impurity has been found. The only satisfactory solution is elimination at the source by local exhaust ventilation; or, if this is impossible, reduction to a safe concen tration by dilution. (See Chapter 8.) In the case of contamination by other matter, including volatile vapors and gases, chemical treatment for the removal or reduction of the impurities has been made available through air cleaning methods, which are discussed in .Chapter 34. , When the only source of contamination is the human occupant, and over heating is not a problem, the minimum quantity of outdoor air needed ap pears to be that required to remove objectionable body odors, or tobacco smoke. The concentration of body odor in a room, in turn, depends Hi 112 CHAPTER 6 1956 Guide upon a number of factors, including the dietary and hygienic habits of. the ; occupants (frequently reflecting their socio-economic status), the outdoor air supply, air space allowed per person, odor adsorbing capacity of air conditioning processes, and temperature and relative humidity. The in tensity of odor sensation has been found to vary as the logarithm of the concentration of the odoriferous substance in the air, or inversely with the logarithmic function of the amount of outdoor air supplied and the air space per person. i; I; >< The relation between air supply and occupancy has been reported by the Harvard School of Public Health2 (Table 1) and the A.S.H.A.E. Research Laboratory.3 Outdoor air requirements for removal of objec tionable tobacco smoke odors are not accurately known, but available information and current practice indicate the need of 15 cfm per person or more.4 ' . The total quantity of outdoor air to be circulated through an enclosure is often governed chiefly by physical considerations for controlling tern-, perature, air distribution, and air velocity. Other factors which must be taken into consideration, include the type and usage of the building, locality, climate, height of rooms, floor area, window area, extent of occu pancy, and the operation of the system distributing the air supply. Fre quently, some of these factors, particularly the need for air movement and good distribution, may be satisfied by recirculation of inside air rather than outside air. ' s It will be noted that, with adequate air space, the rate of air change sjff indicated in Table 1 is: from 4 to 30 cfm per person. In rooms occupied Jj| by only a few persons, such an air change will be automatically attained .. in cold weather by normal leakage around doors and windows, and can easily be secured in warm weather by the opening of windows. With a S0. space allotment of 400 cu ft per person, only 1% air changes per hour are ^ necessary to provide a ventilation rate of 10 cfin per person. . Therefore, in the ordinary dwelling with adequate cubic space allot- wi ment, no special provision for controlling chemical purity of the air is JS necessary (aside from removal of fumes from heating appliances). For, such.conditions, the control of air temperature is the major consideration. , J| In more crowded rooms (large offices, large workrooms, auditoriums), g where the cubic space per person is less and it is usually impossible to || admit untempered outside air without creating drafts, mechanical ventila- jS tion is essential. ; || The present data regarding the effect of cubic space on outdoor air |:s requirements are not universally accepted. The Code of Minimum Re- ' quirements for Comfort Air Conditioning1 prescribes definite minimum ; ? requirements which should be familiar to the designing engineer. It ;ffi should be emphasized, however, that the code Sixes minimum, rather than '.||| adequate requirements. (See also Tables 1 and 3 of Chapter 13.) Notwithstanding the rapid advance made in air conditioning, some per sons still believe there is a stimulating quality'in outdoor air (particularly country, mountain and seashore air) under ideal weather conditions, which -fyfr is lacking in artificially conditioned air. It is apparent, however, thatl^| modem air conditioning insures control of the phenomena of nature for--.: the service and comfort of . man independently of weather conditions.' Freedom of movement, action and thought, together with the variability of stimuli experienced by persons under ideal conditions in the country,'-1*1 mountains or seashore, undoubtedly has some stimulating effect. Variously experimenters have attempted to duplicate the invigorating qualities, ofejf Physiological Principles 113 Type op Occupants Am Space per Person Cu Ft CFM per Person jSgdentary adults of average socio-economic status.... Laborers........................................ jGrade schoolchildren of average socio-economic status Grade school children of lower socio-economic status.-- Children attending private crade schools 100 200 300 500 200 100 200 300 500 200 100 25 16 12 7- . 23 29 21 17 11 38 22 ........ ............ . uy means aj ceninjugal Humidifier. Water atomization rale 8 to 10 gph. Total air circulation SO cfm per person. Sedentary Adults.... .............. ........................... I 200 12 Summer season. Air cooled and dehumidified by means of a spray dehumidifier. Spray water changed daily* Total air circulation SO cfm per person. Sedentary Adults............................. ....... 200 <4 ` outdoor air by the use of ozone, ionization, or ultra-violet light, but results to date have been inconclusive or negative.5 Ozone in amounts of 0.01 to 0.05 ppm of air is allowable in comfort air conditioning. Above this limit there is .a pungent, unpleasant odor and perhaps respiratory distress, depression, and stupor.6 . PHYSICAL IMPURITIES IN AIR . Dust particles of almost any type can produce irritation of the mucous membranes of the nose and throat, if present in high concentrations. Cer tain dusts may be very harmful,-but coal dust is tolerated well. The effects of various industrial dusts, pollens, etc., are discussed in Chapter 8. A certain part of the dissemination of disease in confined spaces may be due to pathogenic organisms floating in the air like dust particles. (See Chapter 7). ... While in some instances it may be possible to reduce the physical im purities of the air by dilution from a non-contaminated source, such a source is rarely available. Frequently, outdoor air contains a higher con centration of physical impurities than indoor air. Therefore, it is usually desirable to reduce the concentration of physical impurities by air clean- m8 methods. (See Chapter 34.) ' THERMAL INTERCHANGES WITH ENVIRONMENT Body temperature depends upon the balance between heat production ^d heat, loss. Heat resulting from oxidation in the body (metabolism) 114 CHAPTER 6 1956 Guide maintains the body temperature well above that of the surrpunding. air in a cool or. cold environment. At the same time, heat is constantly lost from the body by radiation, convection and evaporation. Since, under ordinary conditions, the body temperature is maintained at its normal level of about .98.6 F, the heat production must be balanced by the heat loss. During work, the body temperature may rise; in fact, afternoon tem peratures of normal persons average 1 deg above the resting value of the morning whether working or not. -. The fundamental thermodynamic processes concerned in heat inter changes between the body and its environment may be described by the equation: M = S + ERC (1) where M = rate of metabolism, beat produced within the body. S = rate of storage, change in intrinsic body heat. E = rate of evaporative heat loss. R = rate of, radiative heat loss or gain. C = rate of convective heat loss or gain. . The rate of metabolism, M, is always positive. The storage, S, may be either positive or negative, depending upon whether heat is being stored or depleted owing to a rise or fall in body temperature. Under ordinary circumstances (when the dew-point of the air is below the body surface temperature) the evaporation loss, E, is always positive; that is, heat from metabolism supplies this loss. R and C are positive when body surface temperature is above that of walls and air, and negative when it is below. . DuBois,7 after careful calorimeter studies on a fasting, nude man, plotted the partition of body heat loss and heat production as a function of tem perature. Fig. 1 shows some disparity between heat production and heat Toss. This disparity is <$ in Equation 1. In the central range of the experiments S. was quite low and no increase in heat loss by vaporization was apparent. Within the range of 81-86 F air temperature, with still air, there is, for a resting nude man, a point at which his body has to take no particular action to maintain its heat balance. If he is clothed, or if he is active, this point will naturally lie at a lower level. At this point, which may be termed the neutral point for that individual, conditions are neither too hot nor too cold. If, through a fall in air temperature, or a rise in air movement, the rate of heat loss from the skin to the environment is increased, then the - body must do something to counteract this heat loss. . Over a certain range, the body can achieve this by decreasing the flow of blood through the skin. This will result in some cooling of the skin and subjacent tissues, but the temperature of the deep tissues will be preserved. The range of external conditions over which this may be achieved, may be termed the zone of vaso-molcrr regulation against cold. Beyond this range, the tempera ture of the superficial tissues will fall still further, and that of the deep tissues will fall as well, unless some other steps are taken. The Body normally does react; it increases heat production by increasing muscular tension, by shivering, or by spontaneous increase in activity.* As long as. these are adequate to meet the increased rate of heat loss to the environ ment, a fall in deep body temperature may be prevented^ Such conditions may be said to lie in the zone of metabolic regulation against cold. Beyond Physiological Principles 115 this point; the body enters the zone of inevitable.body cooling. . Once body temperature starts to fall, man is headed for disaster. > .; It will be seen that, in man, deep body temperature is preserved over an important range of cold external conditions, at the expense of (1) a fall in the temperature of the peripheral tissues, and (2) an increased expendi ture of energy. . As regards the firet of these, the farther away superficial tissue lies from the central body mass, the more readily will its temperature fall. . "' , .. . . On the hot side of the neutral point, there exists a. zone of vaso-molor regulation against heat, corresponding to that against'cold. The blood flow through the skin is increased when the opportunities for heat loss to the environment are restricted.8 This increase in blood flow may double the conductance of the superficial tissues over that characteristic of the neutral point, and the temperature of the skin surface may rise until it is only three degrees below that of the deep tissues. If this increase in blood flow is a Normal control, naked, in calorimeter at temperatures from 72,8 to 94.1 F. First column in each experi ment represents heat production as determined by indirect calorimetry, the second column, heat elimination. The portion marked with vertical lines represents vaporization; the dotted area, convection; the unmarked ' area, radiation. The skin temperature represents the average reading of 18 spots on the surface. ' unable to balance the restriction in heat loss, the body has entered the next zone. Once again, the normal body takes steps to prevent a change in its deep temperature; but they are not the counterpart of the steps taken under similar circumstances on the cold side. There is, in fact, very little change in heat production, beyond that resulting from a disinclination for exertion. The second line of defense, on the hot side, is a new and power ful method of promoting heat loss--the provision of water, by the operation of the sweat glands, for evaporative cooling. As long as evaporation is adequate to restore the desired heat loss, the body is in the zone of evapora tive regulation against heat. When this ceases to be adequate, the body is in the zone of inevitable body healing. The body enjoys a little more latitude in this zone than it did in the corresponding zone on the cold side, but when the deep temperature rises more than 4 deg F, it loses its efficiency. All factors which affect the evaporation of water from the skin affect heat regu lation in the zone of evaporative regulation. Atmospheric vapor pressure 116 CHAPTER 6 1956 Guide and air motion are most important. With dry-bulb temperature above body temperature, .air motion facilitates evaporative heat loss by removing hot humid air from:.contact with the skin and replacing it with relatively drier air. ` -" ! . : .. . Heat regulation in'man requires ah intact set of sensory nerves, a nor mal sympathetic nerve supply to sweat glands and blood vessels, a great many sweat glands, and a. circulatory system capable of carrying heat from muscles and viscera to the skin by circulation of the blood. Some of the phenomena of body temperature control are Shown graphi cally in Fig. 2. The dotted curves, from a study at the John B. Pierce Laboratory of Hygiene,10 are for subjects lightly clothed in a semi-reClining position, and give the relation between the dry-bulb temperature of the environment (with about 45 percent relative humidity) and the metabolic i\-.r s t 'r -:V I I I %*: 50 M 70 eu aw ___ ... DRY*BULB TEMPERATURE. DEG fAHR (AT45 PER CENT RELATIVE HUMIDITY} Fig. 2. Relation Between Metabolism, StoragEj Evaporation, Radiation Plus Convection, and Temperature for the Clothed Sup/ect I V'. rate (heat production), the rate of heat dissipation by radiation and con vection combined, and the latent heat loss due to evaporation from the $' skin and the respiratory tract. The smooth line curves from the work of the A.S.H.A.E. Research Laboratory11 give the same relationships for j"; healthy, male subjects (18 to 24 years of age), seated at rest and dressed in customary winter indoor clothing. The Pierce Laboratory data for y'ti the semi-reclining subjects also include the rate of heat storage (either M positive or negative) due to a rise or fall in body temperature. For the :h- normally clothed subjects, a curve gives the total heat loss (that is, the sum of the radiation, convection and evaporative losses). Here, storage is given by the difference between the metabolism and total heat loss. jjp The small difference between the metabolic rates for the two groups of subjects may be accounted for by difference in activity. Heat exchange y between the body and the environment by radiation and convection is :<* greater for the lightly clothed subject, both for cool conditions where f.\ there is excessive heat loss, and for very warm conditions where there is Sv transfer of heat from the atmosphere to the body. The two curves for k Physiological Principles 117 evaporative loss serve to show how physiological control uses evaporation of sweat to maintain equilibrium at high temperatures. Below 75 F, for the normally clothed subject, and below 85 F for the lightly clothed sub ject, evaporation loss is minimal and constant. Burch12 has shown that this insensible perspiration reflects the permeability of the skin to the moisture of the body. Above these temperatures, control is obtained by the availability of sweat for evaporation. The difference in the curves above 75 F is probably largely determined by the difference in clothing and activity. In the zone of evaporative heat regulation, air movement facilitates heat loss if the temperature of the air is not above that of the skin.18 Under hot, dry conditions air movement may be of little advantage, or even of disadvantage, if it increases the addition of heat to the skin by conduction more than it promotes the loss of heat from the skin by evaporation. Table 2. Physiological Responses to Heat op Men at Rest and at Woke* LfKrtrrivfl Temp 60 70 80 85 90 95 100 105 110 Actual Temp (Fahh . Deo) 96.1 96.6 97.0 97.6 99.6 104.7 Men at RzST Men at Wore 90,000 IT-LB OP Wons PEB Houa --Rise in _ Increase Approximate Rectal in Pulse Labs in Body Temp Rate Weight by (Fahr Deg (Beats per Perspiration per Hr) Min per (Lb per Hr) Hr) Total Work Accomplished (Ft-Lb) Rise in Body Temp (Fahr Deg per Hr) Increase in Pulse Rate (Beats per Min perHr) Approximate Loss in Body Wt by Per-spiration (Lb per Hr) o.o" 0.0 o.t 0.3 0.9 2.2 4.0 5.96 ""o' 0 1 4 15 40 83 1376 0.2 0.3 0.4 0.5 0.9 1.7 2.7 4.0b 225,000 225.000 209.000 190.000 153.000 102.000 67.000 49.000 37.000 0.0 0.1 0.3 0.6 1.2 2.3 4.06 6.0b 8.5b 6 7 11 17 31 61 1036 1586 2376 0.5 0.6 0.8 1.1 1.5 2:0 2.7b 3.5b 4.4b _______________ wivu XUU/AILUO Studies at the A.S.H.A.E. Research Laboratory14 and elsewhere during the past two decades have made available much information dealing with the physiological effects of hot atmospheres on workers, and means of alleviating the distress and hazards associated therewith. Table 2 gives some of the physiological responses of men, at rest and at work, to hot environments. Frequent and continued exposure of workers to hot envi ronments results in physiological derangement affecting the leucocyte count of the blood, and other factors dealing with man's mechanism of defense against infection. Wherever S (Equation 1) becomes strongly positive and body tem perature rises progressively, men will continue to work until body tempera ture reaches 103 F. When these body temperatures are exceeded, men work with declining efficiency and may be subject to heat stroke. ' Heat exhaustion is a circulatory failure in which the venous return to the heart is reduced so that fainting results.15 Early symptoms of heat. exhaustion may include fatigue, headache, dizziness when erect, loss of appetite, nausea, abdominal distress, vomiting, shortness of breath, flushlng of face and neck, pulse rate above 150, glazed eyes, and mental dis- 118 CHAPTER 6 1956 Guide Table 3. Uppeb Limits op Environmental Conditions fob Acclimatized, Healthy, Young Men in Militaby Sebvice : ' Environment R-EACTIONB AT TB8 END OF 4 BB Rectal Temp F . Pulse rate Below 101 101 to 102 Above 102 Below 130 130 to 145 Over 145 turbances as apathy, poor judgment, and irritability which usually precede fainting (syncope). Recovery is usually prompt when the man is removed to a cool place and kept lying down for a time, unless he has some other illness such, as heart disease. Heat cramps are painful muscle spasms in extremities, back and abdo men due, at least in part, to excessive loss of salt in sweating. Formerly common in hot industries, this manifestation of illness due to heat is now greatly reduced by drinking water containing 0.1 percent salt, or by proper use of salt tablets. Heat cramps are readily alleviated by administration of salt solution intravenously. . Heat stroke is a serious effect of exposure to great heat. The body temperature climbs rapidly to excessive levels often above 105 F when for unknown reasons free sweating suddenly stops. At such high temperatures, coma appears and death may be imminent. Emergency measures are required to reduce the excessive body temperature by cooling quickly to avoid irreparable damage to the brain.18 . The deleterious physiologic effects of high temperatures exert a power ful influence upon physical activity, accidents, sickness and mortality. Both laboratory and field data show that physical work in warm atmos pheres is a great effort, and that production falls progressively as the temperature rises. fir is. at % # $ g & 'M ACCLIMATIZATION When men move to deserts or to jungles some adaptation to the climate f4' takes place. If work is gradually increased day by day, and if the men can get plenty of water and salt, and can sleep each night, acclimatization may be complete in 7 to 10 days. The acclimatized man works with a lower ^ heart rate, lower skin and rectal temperature, and more stable blood pres sure than when unacclimatized. The process of acclimatization requires work in the heat.17 During the recent war, white troops lived and did hard ig physical work for long periods in tropical conditions when disease hazards || were controlled. In recent tests made at the AJ3.H.A.E. Research Laboratory,18 subjects % were required to perform light work under very hot conditions for a 4-hr ft period each day. It was found that the ability of a new subject to endure a,; these conditions showed daily improvement for a period of at least 2 weeks. However, after acclimatization was completed, a recess of several days ir had no effect on the endurance of the subject. - Individuals differ widely ^ in their capacity to acclimatize. Acclimatized men lose most of these improvements in a few weeks of temperate climate, even though they are ^ vigorously active. In the course of acclimatization, the sweat glands come to secrete fluid less rich in salt.19 For all except those carrying out really f|; hard work in hot, dry atmospheres, this effects an important saving in 4* Physiological Principles 119 Fiq. 3. Heat Endubance op Acclimatized Subjects Wobkinq at a Specific Rate10 salt loss, and makes all the difference between being exposed and not being exposed to the risk of heat cramps. , The adaptive level changes somewhat with the season. There are also marked differences between the sexes. In the cold zone the thickness of thermal insulating tissues of women is almost double that of men, although the sensory responses to cold are similar. In the hot zone, the threshold of sweating is higher for women. The thickness and insulating value of the clothing worn are also important factors in the determination of the comfort level. , UPPER LIMITS OF HEAT FOR MEN AT WORK In very hot conditions humidity is the limiting factor, and the wet-bulb temperature assumes great importance. In 1905 Haldane recognized that 88 F wet-bulb was the limit of endurance for coal miners, and later observers have concurred. A study was made at the Armored Medical Research Laboratory70 to determine the upper limits of -environmental conditions under which a man can perform certain work. Thirteen enlisted men, thoroughly accli matized to the hot conditions, served as subjects. During each test, the subjects were required to march for 4 hr at the rate of 3 mph, carrying PlO 4 W,TM. ,, EFFECTIVE TEMPERATURE MRTffect of Elevation in Terms of Effective Temperature 120 CHAPTER 6 1956 Guide- 20 lb packs under a wide range of environmental conditions winch were rated as relatively easy, difficult, and impossible, on the basis of the physiological reactions of the subjects at the end of the 4-hr period as shown in Table 3 and Fig. 3. Recognition of the need of air conditioning for workers in hot industries is growing rapidly. The choice of the type of system to be used in any given instance, must be determined by the air conditioning engineer after a study of conditions. In some hot industries where few workers are || mi .lrfi Physiological Principles 121 rise in MRT produces the same effect as 1 deg rise in ET; but when the ET is 92 deg, it takes a rise of 11 F deg in the MRT to produce the same effect as 1 deg rise in ET. The upper curve relates to conditions in. which the MRT was kept about 40 F deg higher than the DBT. It will be seen that under these conditions, a rise in MRT is less effective, even at low values of ET; and that it loses its relative effectiveness more rapidly as the ET rises. It should not be assumed, however, that MRT does not matter much. All that these comparisons indicate is that unit rise in MRT becomes less important as compared with unit rise in ET, as conditions get hotter. This may be due more to a growing importance of unit rise in ET than to a diminishing importance of unit rise in MRT. Under ordinary stiU air conditions the effects of air temperature and MRT appear to be interdependent. Various authorities give 0.3 to 1 deg increase of room temperature to compensate for 1 deg depression of the MRT. (j 4,4 MVi I; i!!; Fm. 5. Relation Between Total Heat Loss from the Human Body and Effec tive Temperature for Still Air* 14 * Curve A--Persons working, metabolic rate 1310 Btu per hour. Curve B--Persons working, metabolic rate 850 Btu per hour. Curve C--Persons working, metabolic rate 660 Btu per hour. Curve D--Persona seated at rest, metabolic rate of 400 Btu per hour. Curves B and > based on test data covering a wide tem- gsrature range. Curves A and C based on test data at an Effective Temperature of 70 and extrapolation of urves B and D. All curves are averages of values for high and low relative humidities; variation due to humidity is small. engaged in large spaces the worker himself, rather than the atmosphere, J? can be cooled by placing him in a small booth, and blowing cooled air fe' over him, or by circulating cooled air through a loose-fitting suit.21 . The A.S.H.A.E. Laboratory has studied the effects of walls of higher temperature than the air.18 The findings are in part shown in Fig. 4. It will be seen that the importance of mean radiant temperature, as com- f' pared with that of the effective temperature, decreases as the effective temperature rises; and also, to a certain extent, as the mean radiant tem perature itself rises. The lower of the two curves relates to conditions vl, in which the MRT was kept approximately at the level of the DBT. If v-. this curve is followed, it will be seen that, at 80 ET, a little more than 1 deg ' 1/ Fig. 6. Relation Between Radiation and Convection Loss from the Human Body and Dry-Bulb Temferature for Still Air* 14 * See footnote a. Fig. 5, APPLICATION OF PHYSIOLOGIC PRINCIPLES TO AIR CONDITIONING PROBLEMS In order to estimate cooling loads in occupied spaces it is necessary to know the metabolic rate (heat'production) of man. This has been studied extensively, and found to remain relatively constant per unit of body sur face area in a subject fasting and resting quietly after a good night's sleep. The rate is high in children, and diminishes gradually with age; it increases in certain diseases and in the presence of fever. The metabolic rate is some what lower in women. Heat production goes up sharply with work and varies widely in different persons doing the same work. Figs. 5, 6, and'7 and Table 25 of.Chapter 13 give sufficient basic data for estimating heat pro duction and heat loss under various conditions. ? 1=!; 5 ' ii`i EFFECTIVE TEMPERATURE INDEX AND COMFORT ZONES There is no precise physiologic observation by which comfort can be evaluated. Mean skin temperature offers some promise. The zone of thermal neutrality differs with clothing, season, activity, and all the other factors controlling heat production (Table 4). The comfort zone is very similar to the zone of thermal neutrality. Sensations of warmth or cold depend not only on the temperature of the surrounding air as registered by a dry-bulb thermometer, but also upon the temperature indicated by a wet-bulb thermometer, upon air movement, and upon radiation effects. Dry air at a relatively high tem perature may feel cooler than air of lower temperature with a high moisture content. Air. motion makes any moderate condition feel cooler. Radia tion" to cold or from warm surfaces is another important factor under certain conditions affecting the comfort reaction of the individual. 3*.- m DRY*BULB TEMPERATUKt utti t-AHK Fig. 7. Evaporative Heat and Moisture Loss prom the Human Body in Rela- < tion to Dry-Bulb Temperature for Still Air Conditions* 14 ;s a See footnote a. Fig. 5. : Combinations of temperature, humidity, and air movement which in- ; duce the same feeling of warmth are called thermo-equivalent condi tions. A series of studies22 at the A.S.H.A.E. Research Laboratory estab- ( lished the equivalent conditions for practical use. This scale of thermo- equivalent conditions not only indicates the sensation of warmth, but . also to a considerable degree determines the physiological effects on the \ body induced by heat or cold. For this reason, it is called the effective } temperature scale or index, and it denotes sensory heat level. i Effective temperature is an empirically determined index of the degree J of-warmth perceived on exposure to different combinations of temperature, humidity, and air movement. It was determined by trained subjects who J compared the relative warmth of various air conditions in two adjoining : conditioned rooms by passing back and forth from one room to the other. ; The numerical value of the index for any given air conditions is fixed by i the temperature of slowly moving (15 to 25 fpm air movement) saturated ^ Physiological Principles 123 air which induces' a like sensation of warmth or cold. Thus, any air con dition has an effective temperature of 60 deg when it induces a sensa tion of warmth like that experienced in slowly moving air at 60 F saturated with moisture. The effective temperature index cannot be measured directly, but is determined from dry- and wet-bulb temperatures and air motion observations by reference to an Effective Temperature Chart (see Figs. 8, 9, and 10) or tables. Fig. 8 gives the effective temperature for any combination of dry- and wet-bulb temperatures for still air (15 to 25 fpm) conditions. Charts similar to Fig. 8 for air velocities of 100 and 300 fpm have been presented in earlier editions of The Guide, e.g. 1939. Fig. 9 is another form of effective temperature chart embodying all three variables: dry-bulb and wet-bulb temperatures, and air velocity. Table 4. Comparison op Comfobt Ranges With Zone op Thebmal Neutbautt Investigators Effective Temperature Operative Temp Optimum Line Range Range Remarks Comfort Zone Houghten and Yaglou. 66 Yaglou and Drinker... Yaglou;... Keeton et al. , 71 72.5 75 63-71 66-75 66-82 74-76 Winter non-basal; at rest, nor mally clothed. Men and women. Summer non-basal: at rest and normally clothed. Men. Entire year; non-basal; at rest and stripped to waist. Men. Entire year ;basal,nude .Steady state (9 hr exposure). Men and women. . Zone of Thermal Neutrality DuBois and Hardy.... Winslow, Herrington and Gaerge.. 75 71.8 73.2-76.9 64.8-76.0 Basal; nude; men. Basal; clothed; men. 84.0-87.8 Non-basal; at rest; nude; men. 74 -84 Non-basal ;at rest ;clothed ;men. _____ j v/uuvvivc pcuipci9>i/UI^/ IE Red IQQ6X OI Till Ol warmth experienced by the body. An effective temperature line is, there fore, a line defining the various combinations of conditions which will induce like sensations of warmth. It does not necessarily follow that like sensations of comfort will also be experienced along the entire length of an effective temperature line. Some degree of discomfort is likely to be experienced at very high or very low relative humidities, regardless of the effective temperature. It has also been found that the optimum effective temperature varies with the season, and is lower in winter than in summer. Tests14 made at the A.S.H.A.E. Research Laboratory in very hot con ditions, with subjects doing light work, were in very close agreement with the effective temperature chart. Other work20 under similar environ mental conditions, but with subjects walking 3 mph and carrying 20 lb packs,- indicated that, the effective temperature lines should be more 124 CHAPTER 6 1956 Guide nearly horizontal. It therefore appears that the slope of the ET lines may vary, depending upon the rate of work being performed. Fig. 10 shows the A.S.H.A.E. Comfort Chart as published since 1950. The areas and arrows indicating the summer and winter comfort zones on the previous charts have been removed. The summer comfort zone was removed because it extended to temperatures where too large a percentage of the people would be uncomfortable. The winter comfort zone was removed for the same reason, and because' of inadequate data in later studies. jr' ./ if : 00i _ : 'v_ a.s.h.v.e. Ill -- RESEARCH LABORATORY tc --i <160 1TLL1 ^ ~rj t * L X DU / f \ ^_ --! \ o ^ 1/ y y ^ v, / o3120 0. 1I in i __i n V2 * 0^ ^ \ SX 11 66 F DEW-POINT \ \P H&oJyC' s: \ ^ ^ /[Vv f y C* t ~i H o 80 _i n _j yf^V inLTu^^r'^'^^' >pfk?( -*d\ _j i i q n "C 40 i 1 i 4C m j5 $< ^ x S2 ^ At v '1^ v\ - | I I I5ss 3 S sp 30 40 50 60 70 dry bulb temperature f 80 90 Fig. 8. Psychrometbic Chart, Persons at Rest, Normally Clothed, in Still Air P ik & i Physiological Principles 125. , The distribution curve, showing the percent of people feeling comfortable ty. at various effective temperatures in summer, indicates that a maximum of l" 98 percent of the people were comfortable at 71 ET. The study was conducted with relative humidities between 30 and 70 percent. ft The distribution curve shown on the previously used chart, showing the jy percent of people feeling comfortable at various effective temperatures in i'. the winter, was based on research prior to 1932. This curve indicated ;> ; that at 66 ET a maximum number of people were comfortable. Later '/ studies by the A.S.H.A.E. Research Laboratory indicated that a maxi mum of 97.7 percent of the people were comfortable at 68 ET, and this -k finding has been confirmed by current practice. However, adequate.4p data from the later studies were available only for the ET range of 65 to 69, SC Under Following Conditions: w Customary indoor clothing. B. Activity: Sedentary or light muscular work. C. Healing mafloat; Convection type, *.e., warm air, direct steam or hot water radiators, plenum systems. as presented' in Fig. 10. The studies should be extended to cover a wider range. The lighter weight clothing, probably worn in the later studies, accounts for the higher desirable ET. Radiation from occupants to room surfaces, and between the occupants, has an important bearing on the feeling of warmth, and may alter to some 126 CHAPTER 6 1956 Guide measurable degree the optimum conditions for comfort previously in dicated. Since the mean radiant temperature of a space is affected by cold walls and windows, as well as by the warm surfaces of heating units placed within the room or imbedded in the walls, these factors must be Physiological Principles 127 Many field studies23 have been made to determine the optimum indoor effective;temperature for both winter arid summer in several metropolitan districts of the United States and Canada, in cooperation with the manage-1 ments of offices employing large numbers of workers (Fig. 11). On the whole, women of all age groups studied prefer an effective temperature for comfort, 1.0 deg higher than men.. All men and women over 40 years of age prefer a temperature 1 deg ET higher than that desired by persons below this age. The persons serving in all of these studies were repre sentative of office workers dressed for air conditioned spaces in the summer season, and engaged in the customary office activity. ' .1 % 'i-H- Mia if* 70 80 DRY BULB TEMPERATURE F * Fig. 10. A.S.H.A.E. Comport Chart fob Still Aia*-b m * .Vote.--Both summer and winter comfort lines apply to inhabitants of the United States only. .Applica tion of winter comfort line is further limited to rooms nested by central systems of the convection type; The line does not apply to rooms heated by radiant methods. Application of summer oomfort line is limited to homes, offices and the like, where the occupants become fully adapted to the artificial air conditions. The line does not apply to theaters, department stores, and the like where the exposure is less than 3 hours. The summer oomfort line shown pertains to Pittsburgh and to other cities in the northern portion of the United States and Southern Canada, and at elevations not in excess of 1000 ft above sea level. An increase of one deg m ET should be made approximately per 5 deg reduction in north latitude. b Dotted portion of winter comfort line was extrapolated beyond test data. compensated. Likewise, in densely occupied spaces, such as classrooms, theaters and auditoriums, temperatures somewhat lower than, those indicated by the comfort line may be desirable because of counter radiation between the bodies of occupants in close proximity to each other. . Such radiation will also elevate the mean radiant temperature of the room. -msCs\r Pig. H. Relation Between Effective Temperature and Percentage Observa tions Indicating Comfort On the basis of present knowledge, for different geographical regions and age groups, the most popular temperature varies from a low of 66 ET in winter to a high of 73 ET in summer. The spread for summer comfort is 69 to 73 ET. . A spread of 3 deg in the optimuiri effective temperature for summer cooling is ascribed to geographical location: However, variations in sensa tion. of comfort among individuals may be greater for any given location than variations due to a difference in geographical location. The available information indicates that changes in weather conditions over a period of a few days do not alter the optimum indoor temperature. Sudden chilling of persons entering a cooled and air conditioned space during the summer months, may at times be important. It is due to the rapid evaporation of perspiration which accumulated on the skin and in the clothing during previous subjection to hot and humid outside condi tions and increased heat loss by radiation. While studies25 have shown that for healthy individuals this chilling is not harmful, under some condi- 128 CHAPTER 6 1956 Guide tions it may be unpleasant or even harmful. People entering and remaining in cooled spaces for short periods, 15 min or less, may be satisfied with less cooling. For long occupancy very little deviation from the optimum effec tive temperature is indicated. Upon leaving an air-cooled space and re-entering a hot atmosphere, sudden warming occurs. Experiments at the A.S.H.A.E. Research Labora tory26 and elsewhere25 indicated no demonstrable harm to a healthy indi vidual. Adaptation occurred as soon as normal perspiration was estab lished. Mild exercise shortened the adaptation time. A great number of persons seem to be fairly content in summer with a higher plane of indoor temperature. Studies by the University of Illi nois*7 in cooperation with the A.S.H.A.E. Committee on Research indi cate that effective temperatures as high as 74.5 ET are acceptable in the living quarters of a residence, and while this condition is not representstive of optimum comfort, it provides sufficient relief in hot weather to be acceptable to the majority of users, in the interest of economy. Individual minority differences can be counteracted by clothing. Satisfactory comfort conditions for persons at work28 vary, depending upon the rate of work and the amount of clothing worn. In general, the greater the degree of activity, the lower the effective temperature neces sary for comfort. Clothing has been evaluated for its overall insulation effects by a physical unit, the do which equals 0.116 C deg per (kilogram calorie) (square meter) (hour).28 Yaglou30 criticizes the concept of overall insulation, and points out that different parts of the body require different amounts of insulation. The literature on effects of clothing is difficult to coordinate at the present time, as much of it is still in military service reports which are yet to be published and amplified. For prematurely bom infants, the optimum temperature varies from 100 to 75 F, depending upon the stage of development. The optimum relative humidity for these infants is placed at 65 percent.31 No data are yet available on the optimum air conditions for full term infants and young children up to school age. Satisfactoiy air conditions for these age groups are assumed to vary from 75 to 68 F with natural indoor humidities. For children (having high metabolism) at school, in winter clothes, 70 F has been considered correct, with 55 F recommended for gymnasiums. A >< & $ ?..... REFERENCE 1 Code of Minimum Requirements for Comfort Air Conditioning (A.S.H.V.E. Transactions, Vol. 44, 1938, p. 27). 2 A.S.H.V.E. Research Report No. 1031--Ventilation Requirements, by C. P. Yaglou, E. C. Riley and D. J. Coggins (A.S.H.V.E. Transactions, Vol. 42, 1936, p. 133). 1 A.S.H.V.E. Research Report No. 959--Indices of Air Change and Air Distribu tion, by F. C. Houghten and J. L. Blackshaw (A.S.H.V.E. Transactions, Vol. 39, 1933, p.261). * Tobacco Smoke Control--A Preliminary Study, by Charles S. Leopold (A.S.H.V.E. Transactions, Vol. 51, 1945, p. 255). 8 A.S.H.V.E. Research Report No. 921--Changes in Ionic Content in Occupied Rooms Ventilated by Natural and Mechanical Methods, by C. P. Yaglou, L. C. Benjamin and S. P. Choate (A.S.H.V.E: Transactions, Vol. 38, 1932, p. 191). A.S.H.V.E. Research Report No. 965--Physiologic Changes During Exposure to Ionized Air, by C. P. Yaglou, A. D. Brandt and L. C. Benjamin (A.S.H.V.E. Trans actions, Vol. 39,1933, p. 357). A.S.H.V.E. Research Report No. 985--Diurnal and Seasonal Variations in the Small Ton Content of Outdoor and Indoor Air, by C. P.' IIYaglou and L. C. Benjamin (A.S.H.V.E. Transactions, Vol. 40,1934, p. 271). The Physiological Principles 129 Nature of Ions in Air and Their Possible Physiological Effects, by L. B. Loeb (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 101). The Influence of Ionized Air Upon Normal Subjects, by L. P. Herrington (Journal Clinical Investigation, 14, January, 1935). The Effect of High Concentration of Light Negative Atmospheric Ions on the Growth and Activity of the Albino Rat, by L. P. Herrington and Karl L. Smith ([Journal Industrial Hygiene, 17, November, 1935). Subjective Reactions of Human Beings to Certain Outdoor Atmospheric Conditions, by C.-E. A. Winslow and L. P. Herrington (A.S.H.V.E. Transactions, Vol. 42, 1936, p. 119). The British Medical Journal, Editorial, June 25, 1932, p. 1182. 2 The Mechanism of Heat Loss and Temperature Regulation, by Eugene F. DuBois (Lane Medical Lectures, Stanford University Publications, Medical Science, Vol. 3, 1937, No. 4, p. 348; also Transactions of the Association of American Physicians, Vol. 51, 1936, p. 252). * Exchanges of Heat and Tolerance to Cold in Men Exposed to Outdoor Weather, by E. J. Adolph and G. W. Molnar (American Journal of Physiology, Vol. 146, 1946, p. 507). A.S.H.V.E. Research Report No. 11087-Cardiac Output, Peripheral Blood Flow and Blood Volume Changes in Normal Individuals Subjected to Varying Envi ronmental Temperatures, by F. K. Hick, R. W. Keeton, N. Glickman and H. C. Wall (A.S.H.V.E. Transactions, Vol. 45, 1939, p. 123). 10 A.S.H.V.E. Research Report No. 1107--Recent Advances in Physiological Knowledge and Their Bearing on Ventilation Practice, by C.-E. A. Winslow, T. Bed ford, E. F. Dubois, R. W. Keeton, A. Missenard, R. R. Sayers and C. Tasker (A.S.H.V.E. Transactions, Vol. 45, 1939, p. 111). . 11 A.S.H.V.E. Research Report No. 830--Heat and Moisture Losses from the .Human Body and Their Relation to Air Conditioning Problems, by F. C. Houghten, W. W. Teague, W. E. Miller and W. P. Yant (A.S.H.V.E. Transactions, Vol. 35. 1929, p. 245). * ' 12 Rate of Insensible Perspiration (Diffusion of Water) Locally Through laving and Through Dead Human Skin, by G. E. Burch and T. Winsor (Archives of Internal Medicine, Vol. 74, 1944, p. 437). 12 The Influence of Clothing, Work and Air Movement on the Thermal Exchanges of Acclimatized Men in Various Hot Environments, by N. A. Nelson, W, B. Shelly, S. M. Horvath, L. W. Eichna, and F. F. Hatch (Journal of Clinical Investigations, Vol. 27, 1948, p. 209). . " A.S.H.V.E. Research Report No. 654--Some Physiological Reactions to High Temperatures and Humidities, by W. J. McConnell and F. C. Houghten (A.S.H.V.E. Transactions, Vol. 29, 1923, p. 129). A.S.H.V.E. Research Report No. 672-- Further Study of Physiological Reactions, by W. J. McConnell, F. C. Houghten and F. M. Phillips (A.S.H.V.E. Transactions, Vol. 29, 1923, p. 353). A.S.H.V.E. Re search Report No. 690--Air Motion, High Temperatures and Various Humidities-- Reactions on Human Beings, by W. J. McConnell, F. C. Houghten and C. P. Yag lou (A.S.H.V.E. Transactions, Vol. 30, 1924, p. 167). A.S.H.V.E. Research Re port No. 718--Work Tests Conducted in Atmospheres of High Temperatures and , Various Humidities in Still and Moving Air, by W. J. McConnell and C. P. Yaglou (A.S.H.V.E. Transactions, Vol. 31, 1925, p. 101). A.S.H.V.E. Research Report No. 719--Basal Metabolism Before and After Exposure to High Temperatures and ! Various Humidities, by W. J. McConnell, C. P. Yaglou and W. B. Fulton (A.S.H.V.E. Transactions, Vol. 31, 1925, p. 123). A.S.H.V.E. Research Report No. 908Heat and Moisture Losses from Men at Work and Application to Air Conditioning . Problems, by F. C. Houghten, W. W. Teague, W. E. Miller and W. P. Yant (A.S.H.V.E. Transactions, Vol. 37, 1931, p. 541). A.S.H.V.E. Research Report No. 1106--Air Conditioning in Industry--Physiological Reactions of Individual Workers to High Effective Temperatures, by W. L. Fleisher, A. E. Stacey, Jr., F. C. Houghten and M. B. Ferderber (A.S.H.V.E. Transactions, Vol. 45, 1939, p. 59). A.S.H.V.E. Reseahch Report No. 1153--Seasonal Variation in Reactions to Hot Atmospheres, by F. C. Houghten, A. A. Rosenberg and M. B. Ferderber (A.S.H.V.E. Transactions, Vol. 46, 1940, p. 185). J* A.S.H.V.E. Research Report No. 1151--The Peripheral Type of Circulatory E?.ilure 111 Experimental Heat Exhaustion, by R. W. Keeton, F. K. Hick, Nathaniel Glickman and M. M. Montgomery (A.S.H.V.E. Transactions, Vol. 46,1940, p. 157). 16 Heat Disease; Clinical and Laboratory Studies, by M. W. Heilman and E. S. Montgomery (Journal of Industrial Disease and Toxicology, 18:651, 1936). . 17 Performance in Relation to Environmental Temperature, by L. W. Eichna, B. Bean, W. F. Ashe and N. Nelson (Bulletin of Johns Hopkins Hospital, Vol. 76, 1945, p. 25-58). . 130 CHAPTER 6 1956 Guide M : ** Physiological Response of Subjects Exposed to High Effective Temperatures and Elevated Mean Radiant Temperatures, by C. M. Humphreys, Oscar Imalis and Carl Gutberlet (A.S.H.V.E. Transactions, Vol. 52, 1946, p. 153). ' 11 Life, Heat and Altitude, by David B. Dill (Harvard University Press, Cam bridge, 1938). ; `"The Upper Limits of Environmental Heat-and Humidity Tolerated by Accli matized Men, Working in Hot Environments, by Ludwig W. Eichna, William F. Ashe, William B. Bean and Walter B. Shelley (The Journal of Industrial Hygiene and Toxi cology, Vol. 27, March, 1945, p. 59). 11 A.S.H.V.E. Research Report No. 1188--Local Cooling of Workers in Hot Industry, by F. C. Houghten, M. B. Ferderber and Carl Gutberlet (A.S.H.V.E. Transactions, Vol. 47, 1941, p. 403). . a A.S.H.V.E. Research Report No. 673--Determination of the Comfort Zone, by F.C. Houghten and C. P. Yaglou (A.S.H.V.E. Transactions, Vol. 29, 1923, p. 361). A.S.H.V.E. Research Report No. 691--Cooling Effect on Human Beings Produced by Various Air Velocities, by F. C. Houghten and C. P. Yaglou (A-S.H.V.E. Trans actions, Vol. 30, 1924, p. 193). A.S.H.V.E. Research Report No. 717--Effective Temperature with Clothing, by C. P. Yaglou and W. E. Miller (A.S.H.V.E. Trans actions, Vol. 31, 1925, p. 89). A.S.H.V.E. Research Report No. 755--Effective Temperature for Persons Lightly Clothed and Working in Still Air, by F. C. Hough ten, W. W. Teague and W. E. Miller (A.S.H.V.E. Transactions, Vol. 32,1926, p. 315). How to Use the Effective Temperature Index and Comfort Charts, by C. P. Yaglou, W. H. Carrier, Dr. E. V. Hill, F. C. Houghten and J. H. Walker (A.S.H.V.E. Trans actions, Vol. 38, 1932, p. 410). ** A.S.H.V.E. Research Report No. 1196---Comfort with Summer Air Condition ing, by Thomas Chester, N. D. Adams, C. R. Bellamy, G. D. Fife, E. P. Heckel, Dr. W. J. McConnell, F. C. McIntosh, A. B. Newton, B. F. Raber and C. Tasker (A.S.H.V.E. Transactions, Vol. 48, 1942, p. 107). ** Conditions for Comfort, by C. S. Leopold (A.S.H.V.E. Transactions, Vol. 53, 1947, p. 295). * A.S.H.V.E. Research Report No. 1102--Shock Experiences of 275 Workers After Entering and Leaving Cooled and Air Conditioned Offices, by A. B. Newton, F. C. Houghten, Carl Gutberlet, R. W. Qualley andM. C. W. Tomlinson (A.S.H.V.E. Transactions, Vol. 44,1938, p. 571). Physiologic Adjustments of Human Beings to Sudden Change in Environment, by N. Glickman, T. Inouye, S. E. Telser, R. W. Keeton, F. K. Hick and M. K. Fahnestock (A.S.H.V.E. Transactions, Vol. 53, 1947, p. 327). . 26 A.S.H.V.E. Research Report No. 1055--Cooling Requirements for Summer Comfort Air Conditioning, by F. C. Houghten, F. E. Giesecke, C. Tasker and Carl Gutberlet (A.S.H.V.E. Transactions, Vol. 43, 1937, p. 145). " A.S.H.V.E. Research Report No. 1012--Study of Summer Cooling in the Re search Residence for the Summer of 1934, by A. P. Kratz, S. Konzo, M. K. Fahne stock and E. L. Broderick (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 207). " A.S.H.V.E. Research Report No. 755--Effective Temperature for Persons Lightly Clothed and Working in Still Air, by F. C. Houghten, W. W. Teague and W. E. Miller (A.S.H.V.E. Transactions, Vol. 32, 1926, p. 315). *' A Practical System of Units for the Description of the Heat Exchange of Man with His Environment, by A. P. Gagge, A. C. Burton, and H. C. Gazett (Science, '< Vol. 94, 1941, p. 428). 10 Thermal Insulation of Clothing, by C. P. Yaglou (A.S.H.V.E. Transactions, Vol. 54, 1948, p. 291). . " Application of Air Conditioning to Premature Nurseries in Hospitals, by C. P. Yaglou, Philip Drinker and K. D. Blackfan (A.S.H.V.E. Transactions, Vol. 36, 1930, p. 383). CHAPTER 7 AIR CONDITIONING IN THE PREVENTION AND TREATMENT OF DISEASE : Sanitary Ventilation, Control of Airborne Infection, Value of Air Cooling Under Tropical Conditions, Treatment of Disease,'Operating Rooms, Nurseries for Premature Infants, Fever Therapy, Cold Therapy, Allergic Disorders, Oxygen Therapy, General Hospital Air Conditioning - THE Second World War caused an increase of interest in the preventive aspects of air conditioning. It re-emphasized the importance of the control of airborne infection and demonstrated the value of air cooling under tropical conditions for the prevention of heat rash, for promoting proper rest and sleep, and in the convalescence of patients. The problem of air conditioning or air purification in shelters, hospitals, or any buildings, .following an atomic explosion- has the attention of engi neers, military personnel, public health authorities, private physicians, and the general public. The type and structure of shelters are important. In strategic areas likely to be bombed, they should be windowless, under ground, strong enough to resist blast and have sufficient cover to protect against initial . radiation. Suitable ventilation is a necessity, and could be provided by the use of pressurized installation in which any air taken from .the outside is forced through a ventilator. Air conditioning and heating or.cooling systems could then.be kept in continuous operation for improv ing inside air conditions and controlling room temperature. Heat trans mission through the walls, carbon dioxide accumulation, and the total number of people using the shelter, are factors in determining the neces sity for using outside air. Such a shelter should be closed to outside air during the period immediately following a blast. A surface or subsurface burst of an atomic bomb would result in a wide dispersion of airborne radioactive particles.1 Windows of buildings within a three-mile radius from the point of detonation of a 20 KT bomb would be broken, and consequently, any protection however slight, obtainable through the use of conventional air-conditioning systems would not be accomplished. Beyond- the three-mile radius many structures may be found with windows undamaged and otherwise capable of providing some degree of protection from airborne radioactive particles by the utilization of an air-conditioning system. However, conventional air-conditioning systems should not be relied upon for such protection in urban structures which may be utilized in the accomplishment of specific missions follow ing an atomic detonation. There are special techniques and devices available which will provide this protection. The smog incident in Donora, Pa., has focused the attention of health authorities and engineers on the problem of air contamination by toxic gases. The exact way in which such substances affect the human being is unknown.2 There has been a great deal of speculation, but in reality there is little specific information concerning this problem. It is believed that in such cases the combination of contaminants, rather than any single substance, produces the-toxic effects. It is known that low atmospheric pressure, with accumulation of toxic substances in increasingly higher 131 ,132 CHAPTER 7 1956 Guide concentration, produced the condition in Donora. TheU. S. Piiblic Health team, in their investigation, found that this same city had experienced several previous incidences of lesser severity during the preceding 30 years. This was shown by much higher mortality rates during certain periods. A high percentage of the population of this city suffered .to some, extent during the recent,smog. .Older individuals were more seriously affected With eardio-respiratory symptoms. .............. ; ,: 1 Study of such a situation is rather difficult, as explained in the afore mentioned report., The.medical profession has much to 'learn about the effects of these substances oh: human beings, ahd until more precise [knowl edge is obtained, it'is difficiilt to know when' precise controls are really needed. Further research is urgently needed.8 ' SANITARY VENTILATION During the last 15 years great popular interest has been aroused in the spread of respiratory infection indoors, and control by ventilation or its sanitary equivalent by air disinfection. In Europe three important docu ments have appeared recently in English, Swedish, and French literature.*'5,8 In the United States where the study began, the vast literature has been consolidated, and definitions, formulations, and factors of sanitary ventila tion codified in a volume now being edited for publication. The Council of Physical Medicine of the American Medical Association approved the radiant disinfection of air in 1943, and two sub-committees of the Committee on Research and Standards of the American Public Health Association have reported favorably upon the control of airborne infection by sanitary ventilation and on air sanitation respectively.7'8'9'10 The work of a Technical Advisory Committee on Air Sterilization of the A.S.II.V.E. has from time to time since 1944 reported progress in The Journal, and has recommended a set of definitions, formulations and factors for joint adop tion by the American Public Health Association and the Society. ' But this important new field of sanitary ventilation is just emerging from the research to the development stage. When consolidation and cod ification of present data have been completed, a more comprehensive treatment in The Guide may be possible. The following section on Control of Airborne'Infection gives some idea of the scope of the subject. CONTROL OF AIRBORNE INFECTION The majority of airborne diseases are spread indoors where people gather. Any program of air sanitation is influenced by a number of factors. In ^ the winter months, the closing of doors, windows and other means of access rti to the outside air to conserve warmth, as well as the crowding of persons Js indoors, provides conditions conducive to a high incidence of contagion. This seasonal phenomenon, illustrated in Fig. 1 which represents a study, it made by the U. S. Public Health Service, will concern the ventilating |}] engineer insofar as air quality (determined by temperature, humidity, air ;.Areplenishment and type of air movement and by freedom from contamina-J.f" tion) is a major intrinsic factor. Apart from the seasonal picture of air-'J borne contagion, are such extrinsic factors as rate of turnover of. personnel,|| and the marked susceptibility of the recruit in comparison with permanent: / personnel11 as shown in Fig. 2 by studies of military personnel housed iirij barracks. These extraneous variables and the factor of contact infection;^ (direct spray) tend to complicate any evaluation of the effectiveness ofj? air sanitation for elimination of micro-organisms in droplet-nuclei and drop-'jgj let-dust. Thus, control measures may eliminate consistently 90 percent" Air Conditioning in Prevention and Treatment of Disease 133: of airborne organisms in laboratory tests, but cannot effect a decrease in actual incidence of infection exceeding 30 percent. Thirty percent may be the maximal reduction in infection possible by air treatment methods. The distinction should be clearly drawn, therefore, between the effective ness of a procedure in laboratory tests and its effectiveness and applicability in actually reducing the incidence of airborne disease. On the other hand, recent studies suggest that inhalation of dust-borne bacteria is more im portant than direct inhalation of infectious droplets or droplet nuclei in the spread of respiratory tract infections.12 The following sequence of events has been postulated as occurring in a large proportion of intra-ward infections: (a) ejection of relatively large protected infective particles from patients; (b) rapid venting or settling of these particles so that those remaining airborne are in low con- Pig. 1. Study of Average Monthly Frequency (1921-1926 Inclusive) of Speci fied Respiratory Diseases* centration; (c) survival of infective particles to permit the accumulation of high concentrations on surfaces; (d) repeated reintroduction of infective particles into the air under the stimulus of ward activities or by air currents of the order of 50 fpm over the floor; and (e) extension of infective areas by air turbulence throughout the ward or hospital. The most important link in this probable infection chain has been demonstrated to be the reintro duction of particles into the air.13 Intensive studies on air disinfection have indicated two distinct control measures: (a) suppression of dust and lint, and (6).disinfection of dropletftuclei. A third measure, control of relative humidity, is important. It has been shown that the viability of certain organisms sprayed into the atmosphere from a liquid suspension is dependent on relative humidity. The mortality rate of the organisms is very high at a relative humidity of 50 percent,14 and decreases at humidities above and below this figure. It CHAPTER 7 has also been reported that the influenza virus loses much of its virulence when the relative humidity is 50 percent.16 .. Well controlled, large scale tests of the various methods of air sterilization conducted in barracks16'17 have confirmed the importance of dust control in minimizing the spread of airborne disease, a consideration which has guided the practices of ventilating engineers for a number of years. The importance of the dust factor has been emphasized by many engineers, and has been convincingly demonstrated by subsequent bacteriologic studies aboard ships. Treatment of floors and bedclothes with oil emulsions has proved effec tive in reducing bacterial dispersion by as much as 90. percent; in Army barracks and station hospitals.17 The incidence of acute respiratory in fections was from 10 to 30 percent lower in barracks with oiled floors and bedclothes than it was in control barracks which received no special treat ment. More recent studies, however, have yielded inconsistent results. I Fiq. 2. phly Incidence of acute kesfibatoki cbuits and Ship's Company (Pebmanent Pebsonnel) An emulsifying mixture, Fixanol C containing cetyl pyridinium bromide, when incorporated in the oil-in-water emulsion imparted a bactericidal' action to the emulsion. Blankets treated with this substance and oil became bactericidal and retained this property for as long as three months. The possibility of hypersensitivity of an occasional individual to bromide drugs should be borne in mind when exposing large groups to treated gar ments or blankets.1* No simple method for disinfecting droplet-nuclei has yet been devised. Under favorable laboratory conditions, propylene glycol in concentrations of 0.07 to 0.14 milligrams per liter, and triethylene glycol in a concentra tion of 0.0045 milligrams per liter were highly germicidal for most air borne bacteria in clean air when the relative humidity was between 40 and; 60 percent.18- " A humidity of 50 percent, without the use of glycol vapor, has been reported as destructive to some bacteria. However, maxi mum rates of bactericidal action of triethylene glycol vapor will be secured at humidities between 20 to 50 percent.11 In a recent report on the effect of triethylene glycol vapor in air dis infection, it is pointed out that the rate of ventilation, as determined by the number of air changes per hour, is important and that continuous va porization is needed to maintain effective concentrations of glycol vapor.11 Air Conditioning in Prevention and Treatment of Disease 135? In the absence of an apparatus to measure the concentration of vapor in the room, a slight fog is an indication of adequate concentration. Ab-: sence of such a fog indicates a non-bactericidal concentration. The report' stated: "However, under experimental conditions we have observed no apparent decomposition of triethylene glycol when temperatures up to290 F were maintained at the site of vaporization, provided the vaporizing unit was designed so that heat was applied to liquid glycol only at the point of vapor formation. On the other hand, decomposition was frequently observed when the vaporizing temperature was raised above 290 F, or. when liquid glycol was kept above 120 F for long periods of time. The precise nature of the decomposition products is as yet unknown, but they may well be irritant or toxic and their formation should be avoided. For this reason, it is felt that a limit of 290 F should be applied to the tempera ture employed in vaporization, and furthermore, that liquid glycol should not be heated above 120 F for long periods of time." It was also recommended that a given vaporizer be capable of various outputs as measured by grams of liquid glycol vaporized'per hour; for instance, from 0.5 g to at least 2.0 g per 1000 cu ft of volume treated, for small vaporizing units. Such high rates secure bactericidal concentra- tion in less than an hour. Each room should be furnished with a single small vaporizer, and* one vaporizer should not be expected to handle a volume greater than 4000 cu ft. Apparatus for the production of glycol vapor, and an independent duct system for carrying this vapor and dilut ing air for large rooms or spaces, and unit type vaporizers for small spaces, have been described recently.12 There is also available a device for the automatic regulation of glycol vapor in the air called the glycostat. This instrument has been calibrated to measure the degrees of saturation of the air with glycol vapor by direct reading of the variations in the intensity of light reflected from the glycol condensing surface of the wheel of the instrument.23 1 ' Under practical conditions, particularly in the presence of dust in the air, glycol effectiveness is much reduced. The use of other chemical areosols that have been tried is limited by their toxicity, odor, or destructive ness to fabrics and metals. A recently reported controlled experiment in the offices of the Metropolitan Life Insurance Company showed that under ordinary working conditions triethylene glycol vapor failed to reduce the number of airborne bacteria and the incidence rate of minor respira tory infections.24 Ultraviolet radiation of floors and upper air has been studied extensively . at the Naval Training Center, Sampson, N. Y. In barracks housing naval recruits, hospital admissions for respiratory infections (mostly catarrhal fever) were 25 percent lower in a group of men exposed to ultraviolet radiation--2537 Angstrom Units, 1 to 7 ergs per (cm2) (sec) at bed level-- than they were in adjacent control barracks without ultraviolet radiation.16 A controlled study over a six-year period on the evaluation of ultraviolet radiation of sleeping quarters as a supplement of accepted methods of respiratory disease control was recently reported.26 The amount of ra diation over the last two years of the period was believed to be about five times that recommended commercially. No significant effect in the incidence of disease could be detected in about 400 inmates during the six- year period. This conclusion may not be applicable to present ultraviolet equipment installed in accordance with manufacturers' recommendations, the data imply that air layers were not sufficiently mixed. However, more efficient mixing would have been obtained at the expense of increased 136 CHAPTER 7 1956 Guide circulation of dust and lint. Sources of ultraviolet radiation should be so situated as to protect the eyes of the occupants of the room from direct or reflected rays. A combination of ultraviolet radiation and dust control measures is believed to be more effective than either one of the two used. alone, but the proof for- this has yet to come. There is no doubt that these methods will reduce the number of bacteria in the air of an enclosed space, but there is still considerable question as to whether they are practical measures for reducing the total number of respiratory infections among personnel, since exposure by contact is an important factor. Bourdillon and his group concluded that there is justi fication for attempting to reduce the load of air-borne microorganisms by the methods now at our disposal.4 They have explored the properties of a number of compounds, and their conclusions are in agreement with those of American investigators. The present status is admirably reviewed by the Committee on Sanitary Engineering of the National Research Council,27 and by a subcom mittee of the American Public Health Association. Both committees feel that the problem of air disinfection is still in the experimental stage. Knowledge concerning the effectiveness of glycol vapors has not kept pace with the development of vaporizing devices, and there is real danger that commercial exploitation of the various devices may discredit the method and discourage careful research in this important field.28 More experimentation is needed for arriving at a definite conclusion concerning its use in industry and public buildings. ` - " .4 : ;.s :s . VALUE OF AIR COOLING UNDER TROPICAL CONDITIONS 4 The commissioning of a class of naval hospital ships with all wards, 4 laboratories and living spaces air cooled is a notable achievement to pro- v vide better treatment of patients, especially those suffering from extensive >. burns, by control of environmental factors. Although statistics are not ii at hand to indicate the deaths or retarded recoveries of patients due to lack v of air cooling in ships operating in tropical waters, it is generally agreed 4 among competent observers that high temperature and humidity are major f. factors in prolonging disability and increasing mortality of the sick and / injured. Physiologic data obtained on healthy men, moreover, show the J large loss of body fluids and the stress on the cardiovascular system in terms 4 of increased pulse rate when these men are continuously subjected to high 4 temperatures. Even at rest about 50 cc of fluid per hour are lost as sweat28 -4 through intact skin. In bum patients the difficulty, encountered in tern- f. perate climates, of maintaining fluid and electrolyte balance is tremendously augmented by the additional evaporative fluid loss in hot environments. \ Patients who have such varied conditions as heart disease, thyrotoxico- f. sis, shock from any cause, severe hemorrhage, or those who have had an 4 anesthetic, will invariably store heat when subjected to a hot, humid envi ronment. The gradient between the body surface temperature and the 4 environmental temperature is such that loss by radiation is slight. The y heat loss by evaporation in a warm, humid environment is low whether the patient does or does not perspire. The heat regulatory center may be 44 temporarily deranged following an anesthetic, brain injury, or after an 4 overdose of barbiturate. Loss of fluids and electrolytes is another influ-, pi encing factor. Cooling the body is the answer to this problem, and this 45 can best be done in a cool room of low relative humidity where conditions ; for heat loss are ideal. This measure is also valuable in controlling tem perature height of patients with various acute febrile diseases.20 yg Air Conditioning in Prevention and Treatment of Disease 137 Frequently from 50 to 75 percent of personnel aboard naval vessels operating in tropical waters are afflicted with heat rash to a degree that interferes with rest and sleep. In carefully controlled experiments29 it was possible to produce a fulminating type of rash in all men living con tinuously at an effective temperature of 85 (90 F dry-bulb and 83 F wetbulb). In the control group, 12 out of 24 hr were spent in a relatively cool atmosphere of 75 ET (80 F dry-bulb, and 70 F wet-bulb). These men either remained free from heat rash, or occasionally developed a mild form. Thus, intermittent cooling to a degree which prevented sweating in men at rest eliminated a serious handicap to good performance of duty. In both laboratory tests and aboard hospital ships a relatively cool living environment of 76 to 78 ET provided an atmosphere conducive to rest and sleep without excessive sweating. Berthing spaces tended to have ex tremely low odor levels. Motivation, initiative and alertness, in contrast to the usual irritability and lack of incentive incident to residence in tropical climate, were maintained.21 Little has been done, however, to obtain practical methods for application of air conditioning under heavy heat loads and on the enormous scale that would be needed to modify life in the tropics. It is not improbable that cooled houses in a tropical climate, if used consistently for one generation, would modify the whole character of a population. The obvious advan tages of part time cooling on personnel to promote rest and sleep in tropical areas would provide a prophylactic measure of great potential importance. TREATMENT OF DISEASE In the past few years considerable progress has been made in using air conditioning as an adjunct in the treatment of various diseases. Among the important applications are those in operating rooms, nurseries for premature infants, maternity and delivery rooms, children's wards, clinics for arthritic patients, heat therapy, cold therapy, oxygen therapy, X-ray rooms, the control of allergic disorders, and for the physiological effects in industry. . Normal individuals may be subjected to considerable strain in adjusting to hot, humid conditions. Heat loss by radiation is reduced, as is loss by evaporation of sweat. Individuals with eertain disease processes are at a still greater disadvantage since they may also have difficulty in the trans port of heat from the interior to the surface of the body via the circulation. Patients with thyrotoxicosis tolerate hot, humid conditions or heat waves veiy poorly. Their metabolism is high, and therefore their heat production ls excessive. They may be unable to eliminate heat from the body surface as rapidly as it is produced and transported to the skin. They develop hyperthermia or fever, and a tachycardia or rapid heart rate. The demand on the circulation for transport of heat from the interior of the body to the skm surface is increased. The increased body temperature leads to in creased cell metabolism, and in turn to still greater heat production. This vicious cycle may threaten life if the cardio-vascular or transport mecha nism breaks down. A cool, dry environment favors the loss of heat by radiation and evaporation from the skin, and may save the fife of the pa tient with thyrotoxicosis. . Cardiac patients may be unable to maintain the circulation necessary to insure normal heat loss. Recently the importance of air conditioning Hospital wards and rooms of cardiac patients, particularly those with con gestive. heart failure, has been stressed as a therapeutic measure.32 It is more important in tropical or subtropical climates. Individuals with head 138 CHAPTER 7 1956 Guide injuries, those subjected to brain operations, and those with barbiturate * poisoning may have hyperthermia, especially in a hot environment, due to " a disturbance in the heat regulatory center of the brain. Obviously, one of v the most important factors in recovery is an environment in which the patient can lose heat by radiation and evaporation, namely, a cool room ' with dehumidified air. . ;: The patient in shock, or the patient who has had a severe hemorrhage, . may have an inadequate volume of circulating blood and be unable to maintain an adequate skin circulation. This may result in heat storage ' or fever. Patients with extensive skin bums may be unable to lose heat [ adequately from the limited uninvolved skin surface, and thus develop a - fever. They need adequate fluid replacement, saline solution, plasma or f blood to expand the circulating blood volume and thereby improve pe ripheral circulation. A cool environment is valuable in aiding heat loss , after adequate skin circulation is established. A hot, dry environment (89.6 F and 35 percent relative humidity) has been used over an extended period for the treatment of patients with y rheumatoid arthritis, with reported improvement.33 'v OPERATING ROOMS I The widest application of air conditioning in hospitals is in operating f rooms. Complete air conditioning of operating wards is important be- :g cause winter humidification helps reduce the danger of anesthetic gases; J summer cooling with some dehumidification tends to eliminate excessive fatigue and to protect the patient and operating personnel; and finally, | filtering aids the removal of allergens from the operating room air. | Reducing Explosion Hazard Explosion hazards in operating rooms increased with the introduction of || anesthetic gases and apparatus. Ether administered by the old drop % method gives rise to an explosive mixture, but in practice this method is .;( still regarded as comparatively safe. When ether is mixed with pure oxy gen, or nitrous oxide in certain concentrations, the explosion hazard may yy be as great as with ethylene-oxygen, or cyclopropane-oxygen mixtures. ?i j Of the anesthetic gases nitrous oxide alone does not explode but supports jj combustion. Ether, vinyl ether, ethylene, and cyclopropane are as poten tially dangerous as gasoline or illuminating gas in the home.34 Chloroform-1 ; does not explode violently in contact with flame, but decomposes to liberate % phosgene. All of the anesthetic gases and vapors, except ethylene, are;*-; heavier than air. Although the incidence of injury or death from explosion is negligible compared with other hazards in the operating room, the dra matic features surrounding an explosion justify continued investigation I to eliminate the hazard. ^ During the course of ethylene anesthesia, the mixture, usually 80 per- ijcent ethylene and 20 percent oxygen, is so rich that the danger of explosion f) is slight in the immediate vicinity of the face mask, but leakage of ethyleney) into the air may accumulate to any lower concentration, and thus introduce a serious hazard. The most dangerous period is at the end of the operation al when the patient's lungs and the anesthesia apparatus are customarily.^ washed out with oxygen with or without the addition of carbon dioxide.^: Even when this procedure is omitted, it is difficult in practice to avoid;''! dilution of the anesthetic gas with air during the normal course of breathings following the administration. In either case the mixture would pass|| through the explosion range and extraordinary precaution is necessary for^? the safety of the patient and operating personnel. ^ 1ft I Air Conditioning in Prevention and Treatment of Disease 139 In a study35 of 230 anesthetic explosions and fires, 70 percent of the ex plosions and 60 percent of the deaths were caused by igniting agents other than static sparks. The National Fire Protection Association36 made certain recommendations for safe practice based on available informa tion in Pamphlet No. 56, Recommended Safe. Practice for Hospital Operating Rooms (July 1952). These recommendations outline in some detail ways and means for eliminating or correcting hazardous conditions which experience and investigation have shown to contribute to the hazards in question. They are dividedinto three parts: Part I, General, deals with the nature of the hazards, Part II, Construction and Equipment, deals with physical standards for features incorporated into the construction and equipment of the surgical suite, and Part III, Administration, contains precautions to be observed by hospital personnel. The requirements and recommendations are interdependent and each will be ineffective unless coordinated with the other. To approach complete success in the preven tion of anesthetic explosions, all persons--the surgical staff, the nursing staff, the maintenance staff and administrative personnel--must be edu cated and periodically reminded of the explosive nature of combustible anesthetic agents. Experience has shown that neither high humidity nor intercoupling devices have eliminated the danger from static electric discharge. The removal of gas concentrations from the operating table area, by means of specially devised exhaust ventilation, should be thoroughly tested. Port . able duct systems as installed aboard ship should be acceptable. Serious explosions can occur in a closed system, but proper precautions will reduce this hazard to a minimum. A comprehensive study of the explosion problem and of the general causes and prevention of operating room hazards, by the University of Pittsburgh, the ASHAE Research Laboratory, and the U. S. Bureau of Mines has led to a fruitful attempt to eliminate the explosive range of cyclopropane, one of the best but most difficult gases to handle. The use of helium as a diluent in the total gaseous mixture controls the oxygen concentration by displacement and, because of its flame quenching properties, it is the ideal gas for this purpose. In addition, a gaseous mixture containing helium is more difficult to ignite by electric discharges, and this quality also in creases the safety factor of anesthetic administration. Operating Room Conditions . Little is known about optimum air conditions for maintaining normal body temperatures during anesthesia and the immediate post-operative period. An anesthetized patient displays dilation of blood vessels in the skin resulting in profuse sweating and (it has been believed) inability to regulate body temperature. From this it was concluded that all anes thetized patients suffered considerable heat loss, although there may be little more than 0.8 F variation in the rectal temperature during the course of the operation.37 The severe physiological effects, such as excessive sweating and rapid pulse, of high operating room temperatures on attend ants and patients during the hot months signify the need for proper coollng. Statements of surgeons who operate in both air conditioned and non-air conditioned rooms strongly indicate that the recuperative power of the patient is greater when operated upon in air conditioned rooms.37 Although the comfortable air. conditions for the operators are not identi cal with those for the patient, it is usually not difficult to compromise within a range of 55 to 60 percent relative humidity and 72 to 80 F temperature. 140 CHAPTER 7 1956 Guide The work just cited reported that 68 to 70 F effective temperature not only furnished comfort for the operating room workers, but apparently pre vented exhaustion of patients as evidenced by rapid convalescence in the recovery ward. Additional heat may be furnished to patients locally or by suitable covering, according to body temperature in individual cases. In the control of airborne infection in the operating room, the prevention of dispersal of infectious materials into the air, control of dust, and proper ventilation supersede attempts to remove or kill pathogenic organisms. The bacterial content of conditioned operating rooms is generally lower than that of non-conditioned rooms. Bacterial counts aboard an air-conditioned submarine were found to be exceptionally low and not cumulative with time, although all of the air was recirculated for more than 12 hours'8 without replenishment. The removal of bacteria by the process of air cooling and condensation of mois ture out of air, merits further study.'9 The degree of air contamination can be reduced by proper ventilation if velocity of air over the floor does not exceed 50 fpm. Research is in progress on the use of filtered air flowing through a system of mechanical cleaners which protect the patient against infection from attendants, and from bacteria-eontaining air in the corridor or ward.40 Operations are frequently postponed on allergic patients during asthmatic manifestations through fear of complications. The removal of airborne allergens, therefore, is in some cases an important function of the air con ditioning system in preparing patients for operation. Central system air conditioning plants and unit air conditioners pro ducing between 8 and 12 air changes per hour of adequately filtered and properly conditioned air are generally acceptable to the medical profession for operating rooms. Opinions vary considerably on the use of all outside air versus recirculation for operating rooms. There is a current trend among eminent authorities on anesthesiology to recommend that a mini mum of 50 percent outside air be introduced to the operating room, with a maximum of 50 percent recirculated filtered room air; A separate ex haust fan system is usually necessary to confine and remove the gases and odors. Double windows are desirable and often necessary to prevent con densation and frosting on the glass in cold weather, and to minimize drafts. The air flow of 8 to 12 air changes in operating rooms should: (1) reduce the concentration of the anesthetic to well below the pharmacologic threshold in the vicinity of the operating personnel; (2) remove the great amounts of heat and sometimes moisture, from sterilizing equipment if inside the operating room, from the powerful surgical lights, from solar heat, and from the bodies of the operatives; and (3) provide extra capacity for quickly preparing the room for emergency opera tions. Much can be gained by thermal insulation of sterilizing equipment, and by thorough exhaust ventilation of sterilizing rooms adjoining the operating rooms. An air conditioned recovery ward in connection with the air conditioned operating room, is of great value in stabilizing peripheral circulation, and in reducing excessive loss of fluids on hot humid days. NURSERIES FOR PREMATURE INFANTS One of the most important requirements in the care of premature infants is the stabilization of body temperature. This is necessary because the. infant's heat regulatory system is not fully developed, with the resultant: tendency for environmental temperature to influence body temperature.; Air Conditioning in Prevention and Treatment of Disease 141 The younger the premature infant, the greater is the tendency. As the infant's metabolism is low, heat production is not adequate to maintain a normal body temperature in a cool environment. The resistance to in fection is low, and the mortality rate is high. In general, the younger the age of the premature infant, the higher the mortality rate. Nurseries constructed for metabolic research should be air conditioned so that conditions are reproducible. Results of such studies may be in valid if environmental conditions are not identical, since fluid and electro lyte loss may vary greatly with change in environmental conditions. Air Conditioning Requirements The optimum air conditions for growth and development of premature infants were determined by extensive research41 at the Children's Hospital, Boston, Mass., using four valid criteria, namely, stability of body tempera ture, gain in weight, incidence of digestive syndromes, and mortality. Individual temperature .requirements varied widely (from 72 to 100 F) according to the constitutional state of the infants and body weights. The optimum relative humidity was about 65 percent, and the air move ment less than 20 fpm. . A single nursery conditioned to 77 F and 65 percent relative humidity was found to fulfill satisfactorily the requirements of the majority of pre mature infants. Additional heat for weak (or debilitated) infants may be furnished in the cribs or by means of electric incubators placed inside the conditioned nursery, and the temperature adjusted according to individual requirements. In this way multiplicity of chambers and of air conditioning apparatus is obviated; the infants in the heated beds derive the benefit of breathing cool humid air, and the nurses and doctors need not expose themselves to extreme conditions. Importance of Humidity. Although external heat is an important factor in the maintenance of normal body temperature, humidity appears to be of equal or greater importance. When the premature nurseries at the Children's Hospital were kept at relative humidity between 25 and 50 percent for two weeks or longer, the body temperature became unstable, gain in weight diminished, the incidence of gastro-intestinal disturbances increased, and the mortality rose. On the other hand, continuous ex posure to air conditions with 55 to 65 percent relative humidity gave satisfactory results over a period of years. The initial physiologic loss of body weight (loss occurring within first four days of life) was found.to vary inversely with the humidity. In the old nurseries with natural humid ity it averaged 12.4 percent of the birth weight; in the conditioned nur series it was 8.9 percent with 25 to 49 percent relative humidity, and 6.0 percent with 50 to 75 percent relative humidity. The number of days required to regain the birth weight was correspondingly maximum in the old nursery, and minimum in the conditioned nurseries under high humidity. Maximum gains in body weight occurred in the conditioned nurseries under high humidity (55 to 65 percent) in infants weighing less than 5 lb. The gains were less under low humidity (25 to 50 percent) in the same nurseries, and in the old nurseries prior to use of air conditioning apparatus. . The incidence and severity of digestive syndromes, with diarrhea, per sistent vomiting, diminishing gain or loss of body weight, and other symp toms, were generally from two to three times as high under low as under high humidity. Summarizing, the best chances for life in premature infants are created hy maintaining a relative humidity of 65 percent in the nursery, and by 142 CHAPTER 7 1956 Guide providing a uniform environmental temperature just sufficiently high to keep the body temperature within normal limits. Medical and nursing care are, of course, factors of equal and sometimes of greater importance. Air Conditioning Equipment Many of the installations now in use are of the central system type pro viding for filtration, for humidification and heating in cold weather, and for cooling and dehumidification in hot weather. A ventilation rate be tween 8 and 12 air changes per hour is desirable to remove odors and main tain uniformity of temperatures in extremes of weather. Recirculation should not be used in these wards owing to odors and the possibility of infection. There should be a frequent change in spray water.. ' Control of Airborne Infection . The protection of the premature and older infant against infection is of the utmost importance. It was found in one installation equipped with air conditioning, germicidal fights and mechanical barriers that air con ditioning alone did not prevent the spread of respiratory cross-infections.42 Bacterial ultraviolet barriers, air conditioning and mechanical barriers are efficient. However, infections are brought in by, and often spread by, ward personnel in spite of these measures. FEVER THERAPY Artificial production of high fever in man can be considered an imitation of nature's way of overcoming invading pathogenic organisms. The action may be direct and specific by destruction of the invading organism within the safe limit of human temperatures, or indirect in the case of heat re sistant organisms, by general mobilization of the defensive mechanisms of the body. Although the action may be direct and specific by destruction of the invading organisms within the safe human limits, fever therapy exerts much of its benefit through the improvement of the mechanism of bodily defense. A serious challenge to the theory on which fever therapy is based comes from the demonstration that high fever causes a reduction in the concentration of circulating antibodies in experimental animals. Patients for fever therapy should be carefully selected. The most serious complications which may arise are heat stroke, heat exhaustion and cir culatory collapse. The chief minor complications are heat cramps, fever blisters and mild dehydration. ' The limits of induced systemic fever are usually between 104 and 107 F (rectal), and the duration from 3 to 8 hours at a time. The total period of fever treatment varies with the type of the organism involved. The diseases which respond favorably to artificial fever therapy are gonorrhea and its complications (which include arthritis, pelvic infections in women, and involvement of the eye), syphilis and chorea. The most striking results are seen in gonorrhea and syphilis, since the causative organisms can be destroyed at temperatures compatible with human life. However, the use of fever therapy has decreased since peni cillin has been found so effective in the treatment of gonorrhea and syphilis. Mild fever, up to 101 F for one hour, has recently been used in the treatment of rheumatoid arthritis. This degree of fever is not bactericidal, but is believed to stimulate the body defense mechanism. Air Conditioning in Prevention and Treatment of Disease 143 Equipment for Production of Fever ' Artificial fever can be induced by injections of various crystalloid or colloid substances, bacterial products of typhoid and malarial organisms, or by physical methods using hot baths, radiant heat cabinets, hot humidi fied air cabinets, or by short wave diathermy in combination with a cabinet. The relative advantages of various methods have been evaluated clin ically.43 Among the devices for the production of fever by physical means, the one most widely used is the hot humid air or air conditioned cabinet. This apparatus was developed at the Kettering Institute for Medical Re search at Miami Valley Hospital in Dayton, Ohio. . In the earlier studies of the Society, temperatures were elevated more easily using saturated atmospheres. A fever therapy apparatus44 using these same principles has proved efficient as a means of inducing.and main taining fever in a body, with small likelihood of bums because of the com paratively low dry-bulb temperatures. When heat is necessary in treating legs or arms, such media as short or long wave diathermy, micro-waves, infrared, water baths, etc., have been used extensively. A recent development, a saturated atmosphere heating unit, similar to one previously described has proven satisfactory, because heat may be administered over longer periods which render deep heating possible without fear of burns or shocks. Local heating has been somewhat satisfactory in relieving the painful symptoms of peripheral vascular disease. This procedure, however, is not without danger. Elevation of tissue temperature increases cell metabolism and the need for oxygen. The inadequate blood supply and oxygen deficiency may lead to tissue death , or gangrene. Application of heat to the trunk or abdomen, with conse quent reflex dilatation of the vessels of the extremities, eliminates this dan ger of local heat application. Short wave diathermy within the cabinet during the induction phase has been used. When the desired body temperature has been reached by elec trical induction, the atmosphere of the enclosure is kept at saturation to prevent heat loss, thus maintaining the patient's temperature at the de sired point. The two underlying principles in the production of fever by the hot, humid air cabinet are: (1) the transfer of heat by conduction from the circulating hot air to the body, and (2) prevention of heat loss. The latter is more important. In an atmosphere of high humidity, the heat loss by evaporation is markedly decreased. COLD THERAPY Cold as an anesthetic agent was advocated by Allen several years ago.45 Freezing of the tissue must be avoided. For certain patients, in whom am putation of an extremity is indicated, the application of a tourniquet with cooling of the affected extremity down to near freezing (5 C or 40 F) is of value. The patient, following this procedure can be prepared for surgery without the handicap of absorption of septic products and severe pain. This procedure has proven especially valuable in the neglected diabetic patient with an infected gangrenous extremity. Time for treatment of coma and hydration of the patient is gained. However, if amputation f an extremity is not indicated, the application of a tourniquet and pack- 144 CHAPTER 7 1956 Guide ing in ice are dangerous procedures, since loss of the limb usually results. An extremity with inadequate blood supply can be readily cooled with out the use of a tourniquet, but such an extremity is also usually even tually lost. Theoretically, cooling is said to reduce the metabolism of the tissue with suspension of the vital processes. It also reduces the blood flow to practically zero, and few extremities with inadequate blood supply remain viable or recover. Packing in ice, or use of low temperatures, is contra-indicated in the treat ment of patients with frostbite, immersion foot or trench foot. The affected extremities should be exposed to the air in a cool room and not rubbed with snow or packed in ice. The lowering of temperature by packing the body in ice for treatment of cancer has not proven successful. . The methods used for refrigeration, depending upon available facilities, are as follows:45 (1) Cracked or shaved ice which is simple and has the advantage of not freezing tissues. However, it is cumbersome and sloppy to handle and is unsuited to pro longed treatments. ' (2) Use of ice in a pail for immersion of local parts. (3) Special boxes for holding ice with padded or curtained openings for the limb. (4) Bare ice bags and cloth bags for iced wet dressings for prolonged treatments and convenience. . (5) A double chambered cabinet using dry ice has been constructed. (6) Electrical refrigerating apparatus, consisting of a compact noiseless unit that pumps fluid to various types of applications, is available. The applicators may be in the form of blankets containing rubber tubes suitable for covering the entire body, or all or part of a limb. Special applicators are available for insertion into various body cavities, and for inducing dental anesthesia. (7) An air chamber at regulated temperature for treatments of frostbite and im mersion foot, and amputation stumps. The electrical apparatus is costly, but has the advantages of thermostatic regulation, light weight, freedom.of movement, and permits prolonged treatments with heat, as well as cold over the range of temperatures thera peutically desirable. - ALLERGIC DISORDERS Hay fever, asthma, eczema and contact dermatitis are classified as allergic disorders. The allergic individual responds to contact with a variety of substances, which are innocuous to a non-allergic person, with severe manifestations of hypersensitivity. These substances are known as allergens and consist of airborne irritants such as dusts, molds, feathers, pollens, animal dander and others; of food protein such as milk, wheat, eggs, etc., or of simple chemicals brought in ' contact with the skin. They may enter the body by various routes of which inhalation is the most common type. Ingestion of offending food substances is not infrequent. ' The offending substance reacts with the sensitized cells of the mucousmembranes or skin. During this reaction, histamine or a histamine-like';, substance is released and causes (a) increased capillary permeability, (b). secretion of mucus and (c) muscular contraction. In the eyes and nose`s this produces itching, redness and lacrimation or rhinorrhea, in short, the-- symptoms of hay fever. In the lungs it causes, in addition to the secretory ; Air uonaiuomng in Prevention and Treatment of Disease 145 response, a contraction of the smooth muscles of the bronchi resulting in bronchial asthma. It is commonly known that non-specific environmental factors such aa lust, irritating gases, change of temperature and humidity may precipitate asthmatic attacks in allergic subjects, even in the absence of exposure to specific allergens. It is assumed that the presence of frequent allergic bronchial constriction renders the smooth muscles of the bronchi so sensi tive to various non-specific stimuli that the threshold of their response to such irritation is considerably lower than that of a non-allergic individual. Air Conditioning Apparatus Of all the measures to relieve a specifically sensitive individual, elimina tion of exposure to the responsible allergen is the most efficient, though not always a practical, form of treatment. In recent years considerable effort has been made to accomplish such elimination by removal of respiratory allergens from enclosures by filtration or other air conditioning processes. Paper or cloth filters, mounted in inexpensive window or floor units, prove quite satisfactory in many cases, but since dust and smoke frequently cause asthmatic attacks, it is desirable that an air filter, to be of full value in the treatment of asthma, should remove all possible dusts and pollens regardless of size Or amount. Electrostatic air cleaners are more efficient than most commonly used types for capturing very fine dust. Although the chief remedial factor in the treatment by conditioned air is the filtration of pollen, a certain amount of cooling and dehumidification appears to be desirable. A comfortable temperature between 70 and 75 F, and a relative humidity well below 50 percent proved satisfactory.46 Di rect drafts, overcooling or overheating are apt to initiate or aggravate the symptoms. Limitations of Air Conditioning Methods The results obtained with air filtration, or other air conditioning pro cesses, in the control of allergic conditions, are fairly comparable to those ob tained by desensitization treatment, so long as the patients remain in the . pollen-free atmosphere. For all practical purposes filtration gives only temporary relief. In mild cases sleeping in an air conditioned, space may make it possible for the individual to pass more comfortable nights. With rare exceptions, the symptoms recur on exposure to pollen-laden' air. More over, the usefulness of air conditioning methods is limited, because all cases are not caused by airborne substances. Cases of bacterial asthma do not . respond to treatment with filtered air. Despite these limitations, air conditioning methods possess definite.ad vantages in the simplicity of treatment, convenience, and under certain conditions, almost immediate relief.47 Pollen cases are usually relieved of most of their symptoms within 1 to 3 hr after exposure to properly filtered mr. A pollen-free atmosphere is especially valuable when desensitization has given little or no relief, and when desensitization is not advisable owing to intercurrent illness. Lnerapy is used to prevent or relieve anoxia. Some of the moi important clinical conditions in which oxygen treatment is beneficial ii elude pneumonia, severe anemia, cardiac decompensation, pulmonary at( CHAPTER 7 1956 Guide lectasis, asphyxia and asthma. The effectiveness of oxygen therapy is dependent on the concentration of the oxygen in the inspired air, or the partial pressure of oxygen in the pulmonary alveoli. ' Oxygen is usually administered by nasal catheter, face mask or tent.48 The necessity of air conditioning in oxygen therapy arises from the fact that oxygen is too expensive a gas to waste in the ventilation of oxygen tents and oxygen chambers. Air conditioning is applied to the oxygen tent or chamber through reconditioning of the atmosphere in a closed circuit. Excessive heat, moisture and carbon dioxide are removed. Oxygen Tents In oxygen tents, the air enriched with oxygen is usually circulated by means of a small motor blower which sends the air over soda lime to remove carbon dioxide, and then over ice to remove excess heat and moisture. The concentration of oxygen in the tent is regulated by means of a pressure reducing valve and flow meter. In an inadequately cooled tent, high tem peratures and humidities are inevitable, increasing the discomfort of the patient and imposing an added strain on an already overburdened heart. Oxygen therapy under such conditions may do more harm than good. An ice melting rate of approximately 10 lb per hour gives satisfactory results in patients with fever in a medium size oxygen tent. jj Oxygen tents are. confining to the patient. They may terrify the restless and delirious patient. Medical and nursing care is complicated, as the -p tent must be opened or removed with attendant loss of oxygen. Oxygen p concentrations of 50 percent or more are difficult to maintain, and it is a gf problem to keep the temperature and-humidity low enough in hot weather. Si However, with attention to details, the patient can be made quite com- f fortable. In fact, during hot, humid weather an oxygen tent may be very f]| valuable in controlling a patient's temperature, since the upper part of the ;f body within the cooled tent loses heat rapidly. Oxygen Chambers The conventional oxygen chamber is an air-tight sheet metal enclosure '& of fire-proof construction, large enough to accommodate one or two patients..Jg Trap doors or curtains are provided for the personnel, food and service, to avoid loss of oxygen. Glass windows in the ceiling and walls admit%g light from outside the chamber. The air conditioning system may be of ' the gravity type, or of the fan type using mechanical refrigeration or airi|| drying agents. . . The temperature and humidity requirement in oxygen therapy depends ^' primarily upon the physical condition of the patient, and secondarily uponsg the type of disease. In pneumonias49 prescribed conditions should be a-j^ temperature of 60 to 75 F, humidity 50 to 55 percent, moderate air move- ment, oxygen concentration of 50 percent, and carbon dioxide of less than|p one percent. M. sp Oxygen in Aviation An important application of the principle of oxygen therapy is in aviation.g:r? At the present time all high altitude military airplanes in this country arejte* provided with gaseous oxygen equipment, and military personnel are re^ quired to utilize oxygen at all times while in flight above 15,000 ft, or be-|j tween 12,000 to 15,000 ft for longer than two hours, or between 10,000m Air Conditioning in Prevention and Treatment of Disease 147 to 12,000 ft for longer than six hours. The use of oxygen in commercial aviation will depend on the height and duration of the flights, as well as the state of health of the passengers. The necessity for portable, comfortable equipment, the possible fire hazards due to smoking, and the use of oxygen on sleeper planes are some of the difficulties facing civil airline operators. The pressure cabin airplane is a solution to the problem. . GENERAL HOSPITAL AIR CONDITIONING Complete conditioning of a large hospital involves a capital investment and running expenses which may not be justified. In clean and quiet districts, the requirements of almost all general and private wards during the cool season of the year can be satisfactorily fulfilled by the use of con ventional heating equipment, in conjunction with window air supply and gravity or mechanical exhaust. Insulation against heat and sound is much more important than humidification in winter; it will also help in keeping the building cool in warm weather. Excessive outside noise and dust may require the use of silencers and air filters in the openings. Cooling and dehumidification in warm weather are important. In new hospitals particularly, the desirability of cooling certain sections of the building should be given serious consideration. Financial reasons may preclude the cooling of the entire building, but the needs of the average hospital can be met by the use of built-in room coolers and a few portable units which can be wheeled from ward to ward when needed. In the North, and certain sections of the Pacific Coast, cooling is needed but a few days during summer, while in. the South, it can be used to ad vantage from May to October, and in tropical climates almost continuously throughout the year. F. L. Grocott of the Anglo-Iranian Oil Co. states that in Iran, the medical ' staff after 10 'years' experience with air conditioning, demand a uniform environment of 75 F and 50 percent relative humidity (70 ET) under all summer outside conditions for general wards and treatment rooms, and 70 F with 30 to 50 percent relative humidity (65-66 ET) for winter conditions. In the operating rooms, 70 F with 50 percent relative humidity (66 ET) is demanded all the year 'round, although the annual external range is 40 F to 120 F. No ill effects have been noted in the medical personnel, though they are exposed to changes from external to internal conditions many times daily. Temperature shock in either direction seems to create discomfort for a short interval, but if the individual is in good health, no injury re sults.60' .Aside from comfort and recuperative power of the patients, cooling is of great assistance in the treatment of fevers in the new-born and in post operative -cases, in enteric disorders, fevers, heat stroke, heart failure, thyroid crisis, and in a variety of other ailments which often accompany summer heat waves. ot Odors The evacuation of battle casualties in aircraft and their subsequent hospitalization have stimulated efforts to minimize odors arising from drain ing wounds, old odorous casts, and gangrenous wounds. For aircraft, chemical sprays and vapors, perfumes, oxidizing gases and simple exhaust methods are unsatisfactory. An ideal deodorant would purify the air by means of odor adsorption so that subsequently the air can be recirculated. 148 CHAPTER 7 1956 Guide Based upon the effectiveness of activated carbon commercially and in dustrially to adsorb odors, individual adsorption units have been used successfully. In hospital wards the question of superiority of adsorption methods for elimination of odors over other methods remains to be an swered. The present status of the problem is that the commercial aspect is highly controversial.51 REFERENCES I The Effects of Atomic Weapons, Revised September, 1950. (For sale by the Supt. of Documents, U. S. Government Printing Office, Washington 25, D. C.). Investigation of the Smog Incident in Donora, Pa., and Vicinity, by James G. Townsend, M.D. (American Journal of Public Health 40:183-189, Feb., 1950). The Physiologic Aspects of Atmospheric Pollution, by Carey P. McCord, M.D., (.Industrial Medicine and Surgery, 19:97-101, March, 1950). 7 Studies in Air Hygiene, by R. B. Bourdillon, O. M. Lidwell and J. E. Lovelock with W. C. Cawston, L. Colebrook, F. P. Ellis, M. Vanden Ende, R. E. Glover, A. M. Macfarlan, A. A. Miles, W. F. Raymond, E. Schuster and J. C. Thomas (Medical Research Council of Great Britain, 1948. Special Report Series No. 262). Ultraviolet Irradiation with Artificial Illumination, by Hans E. Ronge, Uppsala, Sweden, 1948, 191 pages. 8 L'flygiene du Batiment per L'Ultra-violet by P. A. Burrucand, Centre Scien tific et Technique du Batiment, Paris, 1949. 7 Acceptance of Ultraviolet Lamps for Disinfecting Purposes, Council of Physical Therapy (Journal of American Medical Association, 122:503-504, 1943). Evaluation of Methods to Control Airborne Infection, by J. E. Perkins (Ameri can Journal of Public Health, 35:891-897, 1945). The Present Status of the Control of Airborne Infections, by Committee on Evaluation of Methods o Control Airborne Infections of the American Public Health Association (Journal American Public Health Association, 37:13-22, 1947). 10 Progress in the Control of Airborne Infections, by Sub-Committee on Air Sani tation (American Public Health Association Yearbook, 40:5, May 1950 p. 82.) II Factors in the Control of the Spread of Acute Respiratory Infections with Ref erence to Streptococcal Illness and Acute Rheumatic Fever, by S. M. Wheeler and T. D. Jones (American Journal of the Medical Sciences, 209:58, 1945). 17 Dust Control, Report on Suppressive Measures for the Control of Dust, to the Standard Methods Committee for the Examination of Germicides and.Antibacterial Agents, by Clayton G. Loosli (American Journal of Public Health, Vol. 38, p. 409, March, 1948). 11 Laboratory and Field Studies of Glycols and Floor-Oiling in the Control of Air- Y Borne Bacteria, by A. P. Krueger, et al(U. S. Naval Medical Bulletin, 42:1288,1944). v !* The Lethal Effect of Relative Humidity on Air-Borne Bacteria, by Edward Wj'* Dunklin and Theodore T. Puck (Journal of Experimental Medicine, 87:87-101, Feb. Y 1948). 16 Quotation by William Lester, Jr., in Health on the Job, No. 22, February 1949, published by Institute of Industrial Medicine, New York University, New York, N. Y.lf > Bacteria! Content of Air in Army Barracks, by H. M. Lemon, H. Wise and M. y Hamburger (War Medicine, 6:92, 1944). '?' 17 A Study of the Nature and Control of Air-Borne Infection in Army Camps, by f O. H. Robertson, M. Hamburger, C. G. Loosli, T. T. Puck and H. M. Lemon (Jour-3^ nal of the American Medical Association, 126:993, 1944). r ls Lethal Effects of Triethylene Glycol Vapor on Air-Borne Bacteria and Influ- jK enza Virus, by O. H. Robertson, el al (Science 97:142,1943). : 17 The Present Status of Glycol Vapors in Air Sterilization, by M. Hamburger, Jr., O. H. Robertson, and T. T. Puck (American Journal of the Medical Sciences,f: 209:162, 1945). ! .* 70 Summary of a 3-Year Study of the Clinical Applications of the Disinfection of r,y Air by Glycol Vapors, by T. N. Harris and J. Stokes, Jr. (American Journal of the- ': Medical Sciences, 209:152, 1945). Air Conditioning in Prevention and Treatment of Disease 149 71 Factors of Importance in the Use of Triethylene.Glycol Vapor for Aerial Dis infection, by William Lester, Jr., Saul Kaye, O. H. Robertson and Edward Dunklin (American Journal of Public Health 40:813-820, July 1, 1950). 77 Triethylene Glycol Vapor Distribution for Air Sterilization, by Edward Bigg, B. H. Jennings, and F. C. V/. Olson (ASHVE Transactions, Vol. 53,1947, p. 393). 77 Glycol Vapors for Disinfecting Purposes, Editorial (Journal of the American Medical Association, 133:696, March 8, 1947). 71 An Experiment with Triethylene Glycol Vapor for the Control of Colds Among Office Employ,,ees,, b,,y W__.__J_._M__c_Connell (yInnudiuusmtrniaail mMeeadiicctinnee,, 1188::55,,119922--119966,, MMaayy,, 11994499)).. 7*5 Ultra-Violet Light Control or>ff AAiVr--BBonr-nnen ITn_fre--ct-ions in a Naval Train-ing C- enten by S. M. W.iuhceceliecri, Hii. oS. IinnggTraahnaam, A. Hollaender, N. D. Lill, J. Gersshhoon-Cohen, and E. W. Brown (American Journal of Public HHemaUlth, Vvo,,il. 3o5k, p-. 457 ,1"9'45r'). 7* An Evaluation of Ultraviolet Radiation of Sleeping Quarters as Supplement of Accepted Methods of Disease Control, by H. G. DuBuy, J. E. Dunn, F. S. Brackett, W. C. Dreessen, P. A. Nealand, and I. Possner (American Journal of Hygiene, 48: 207-226, Sept., 1948). 77 Recent Studies on. Disinfection of Air in Military Establishments (American Journal of Public Health, Vol. 37, p. 189, Feb. 1947). 77 Commercial Exploitation of Glyool Vaporizers (Editorial in American Journal of Public Health, Vol. 39, No. 2, February 1949, p. 222). 78 A Comparative Study of the Effect on Men of Continuous Versus Intermittent Exposure to a Tropical Environment, by N. Pace, M. B. Fisher, J. E. Birren, G. C. Pitts, W. A. White, Jr., W. V. Consolazio, and L. J. Pecora (Research Project X-205, Report No. 2, Naval-Medical Research Institute, Bethesda, Md., May, 1945). 70 Mechanism of Heat Retention, by F. K. Hick and M. M. Montgomery. (Un published). 71 Environmental and Physiologic Studies Aboard, an Air-Cooled Hospital Ship En Route from Norfolk, Virginia to Canal Zone (U. S- S. Tranquility (AH-14), 6-L3, June 1945), by A. R. Behnke (Research Project X-205, Report No/4, Naval Medical Research Institute, Bethesda, Md., September, 1945). 37 The Influence of Environmental Temperature and Relative Humidity on the Rate of Water Loss Through the Skin in Congestive Heart Failure in a Subtropical Climate, by G. E. Burch (American Journal of Medical Science, Vol. 211,1946, p. 181). The Response of Patients with Congestive Heart Failure to Rapid Elevation in At mospheric Temperature and Humidity, by G. Berenson and G. E. Burch (American Journal of Medical Science, Vol. 223, 1952, p. 45). 33 Investigation Into the Effect of Hot, Dry Microclimate on Peripheral Circula tion in Arthritic Patients, by Gunner Edstrom, G. Lundin and T. Wramer (Annals of Rheumatic Diseases, 7:76-82, June, 1948). 37 Fundamentals of Anesthesia (American Medical Association Press, Chicago, 111., 2nd Edition, 1944, p. 204). 77 The Hazard of Fire and Explosion in Anesthesia, by B. A. Green (Anesthesiology, 2:144, 1941). 87 Control of Physical Hazards of Anesthesia, by R. M. Tovell and A. W. Friend . (Canadian Medical Association Journal, 46:560, 1942). 37 ASHVE Research Report No. 1111--Air Conditioning Requirements of an Operating Room and Recovery Ward, by F. C. Houghten and W. Leigh Cook, Jr. (ASHVE Transactions, Vol. 45,1939, p. 161). " Unpublished Naval Studies, by A. R. Behnke and O. Schneider (1940). " Disinfection of Air by Air Conditioning Processes, by C. P. Yaglou and Ursula Vnlson (American Association for the Advancement of Science, Publication No. 17, p. loiJ). 43 The Control of Cross-Contamination by the Use of Mechanical Barriers, by J- A. Reyniers (Aerobiology, American Association for the Advancement of Science, Symposium, 17:254, 1942). 41 The Premature Infant: A Study of the Effect of Atmospheric Conditions on growth and on Development, by K. D. Blackfan, C. P. Yaglou and K. McKenzie lAmerican Journal Diseases of Children, 46 -.1175,1933). 47 Observations on the Control of Respiratory Contagion in the Cradle, by I. 'tosenstern (Aerobiology, American Association for the Advancement of Science, Sym posium, 17:242, 1942). - 1956 Guide CHAPTER 7 150 ** Physical Medicine, by F. H. Krusen (W. B. Saunders Co., Philadelphia and Lon"dAonS,H1V94E1).Research Report No. 1054--Fever Therapy Indu.ce.d by Condi tioned Air, by F. C. Houghten, M. B. Ferderber, and Carl Gutberlet (ASHVE Transactions, Vol. 43, 1937, p. 131). ASHVE Research Report No. 1161-- Fever Therapy Locally Induced by Conditioned Air, by M. B. Ferderber, F. C. Houghten and Carl Gutberlet (ASHVE Transactions, Vol. 46, 1940, p. 307). ** Refrigeration for Anesthesia and Therapy, by L. W. Crossman and S. K. Salford (Th"eTMhoedeEmffeHctosopf itLaol,w64R:8e6l,at1iv94e5)H. umidity and Constant Temperature on Pollen Asthma, by B. Z. Rappaport, T. Nelson, and W. H. Welker (Journal of Allergy, 6:1n11H,1o9s3p5i)t.al Air Conditioning, by C. P. Yaglou (The Environment and Its Effect Upon Man, Harvard School of Public Health, p. 244,1939). 49 Principles and Practices of Inhalational Therapy, by A. L. Baracb (J. B. Lip- pincott Co., Philadelphia, London, Montreal, 1944). 49 The Management of Pneumonia, by J. G. M. Bullowa. (Oxford University Press, p. *26W0, h1a9t3A7)r.e the Right Conditions for Comfort Cooling, by Cyril Tasker (Heat .s- ing, Piping, and Air Conditioning, Aug., 1948, p. 84). 11 Odors Physiology and Control, by C. P. McCord and Wm. R. Witheridge (Mc Graw-Hill Book Co., New York, 1949). . XI CHAPTER 8 AIR CONTAMINANTS Classification of Air Contaminants; Sizes of Airborne Particles; Air Pollution by Smoke, Ash and Cinders; Smoke. Abatement and Air Pollution Control; Odor Nuisance; Industrial Air Contaminants; Flammable Gases and Vapors; Combustible Dusts; Atmospheric Pollen; Airborne Bacteria; Radioactive Air Contaminants THE normal constituents of the earth's atmosphere are oxygen,'nitro gen, carbon dioxide, water vapor, argon, small or negligible amounts of other inert gases, hydrogen, variable traces of ozone, and small quantities of microscopic and submicroscopic solid matter, sometimes called permanent atmospheric impurities. From the viewpoint of the air conditioning engi neer, all other airborne substances may be termed contaminants. This term is applied preferably, however, to undesirable or chance impurities, since the occasion may arise for adding to the air controlled amounts of solid or gaseous diluents for the prevention of explosions; germicidal vapors or mists (aerosols) for bacteria control; masking substances for odor control; or a substitute for one of the normal gases, as, for example, when helium is used to replace nitrogen in atmospheres for compressed air workers or divers. Control of the chemical quality of air is one of the functions of complete air conditioning, and some knowledge of the composition, concentration and properties of air contaminants under various circumstances is therefore essential. Air contaminants arise from the normal processes of wear, erosion, wind storm, sea-spray evaporation, thermal disintegration, earthquake, volcanic eruption, combustion, manufacturing, transportation, agriculture, and the biochemical or biological processes of life. They are classified at various times as organic and inorganic, visible or invisible, microscopic or macro scopic, particulate or gaseous, toxic or harmless, beneficial or destructive. The following classification is based chiefly upon the origin or method of formation of air contaminants. CLASSIFICATION OF AIR CONTAMINANTS Dust, Fumes, and Smokes are solid particulate air contaminants. Busts are solid particles projected into the air by natural forces, such as wind, volcanic eruption or earthquake, and by mechanical processes, such as crushing, grinding, milling, drilling, demolition, shovelling, conveying, screening, bagging and sweeping. Some of these forces produce dust from larger masses, while others simply disperse materials that are already pulverized. Generally, particles are not called dust unless they are smaller than about 100 microns. Dusts may be of mineral type, such as rock, ore, metal, sand; vegetable, such as grain, flour, wood, cotton, pollen; or animal, such as wool, hair, silk, feathers, leather. Fumes are solid particles commonly formed by the condensation of vapors from normally solid materials such as molten metals. Metallic fumes generally occur as she oxides in air because of the highly reactive nature of finely divided matter, fumes may also be formed by sublimation, distillation, calcination, or chemical Reaction, whenever such processes create airborne particles predominately below the micron size. Fumes permitted to age tend to flocculate into clumps or aggregates 1 larger size, thereby facilitating removal from air. Smokes are the extremely small solid particles produced bv incomplete combustion ' 151 152 CHAPTER 8 1956 Guide of organic substances such as tobacco, wood, coal, oil,, tar and other carbonaceous materials. The term smoke is commonly applied to the mixture of solid, liquid and gaseous products of combustion, although the technical literature prefers to distin guish between such components as soot or carbon particles, fly-ash, cinders, tarry matter, unburned gases, and gaseous combustion products. The finest particulate constituents are much less than 1 micron in size, often in the range of 0.1 to 0.3 mi cron. Mists and Fogs are liquid particulate air contaminants. Mists are very small airborne droplets of materials that are ordinarily liquid at normal temperatures and pressures. They may be formed by atomizing, spraying, splashing, mixing, violent chemical reaction, electrolytic evolution of gas from a liquid, or escape of a dissolved gas upon release of pressure. Very email droplets expelled or atomized into the air by sneezing constitute mists containing micro organisms that become air contaminants. Fogs are limited by some classifications to airborne droplets formed by condensa tion from the vapor state. This arbitrary distinction between mist and fog is of minor importance, as both terms are used to indicate the particulate state of airborne liquids (occasionally termed aerosols), Fog nozzles are so named because of their ability to produce extra fine droplets as compared to the mist from ordinary spray devices. The highly volatile nature of some liquids quickly reduces their airborne droplets from the mist to the fog range, and eventually to the vapor phase until the air becomes saturated with that liquid. Many droplets in fogs or clouds are micro scopic and submicroscopic in size, and may be conceived as the transition state between the larger mists and the vapors. Vapors and Gases are non-particulate air contaminants. Vapors are the gaseous phase of substances that are either liquid or solid in their commonly known state, examples being gasoline, kerosene, benzene, carbon tetra chloride, mercury, iodine, camphor. Vapors may be changed to the solid or liquid form by increasing the pressure, decreasing the temperature or applying both proc esses simultaneously. They are removed from the air by condensation with less \ difficulty than are the gases. , Gases are normally formless fluids which tend to occupy a space or enclosure com- i pletely and uniformly at ordinary temperatures and pressures. The following subBtances qualify as gases: oxygen, nitrogen, carbon dioxide, carbon monoxide, hydro- . gen, ammonia, sulfur dioxide. Gases, likewise, may be solidified or liquefied by the i proper control of temperature and pressure. : The preceding classification is not suitable for the airborne living or- - ganisms, which range in size from the submicroscopic viruses to the largest i pollen grains, not considering the smallest insect life. Bacteria range from about 0.2 to 5 microns in size, fungus spores from 1 to 10 microns, and pol len from 5 to 150 microns. V SIZES OF AIRBORNE PARTICLES Fig. 1 is a graphic tabulation of the properties of airborne solids andj; liquids arranged according to size on the micron scale. There are 25,400 microns in 1 inch. . ;? Particles larger than 10 microns are unlikely to remain suspended ini' air currents of moderate strength, but settle out by gravity at speeds^.' dependent upon the shape, size and specific gravity of the particle, wind*? velocity, orientation of the collecting surface, and topography. These ; larger particles are of major interest to the engineer in the solution of nui--g- sance problems, but it is usually the smaller particles, or those below lQg microns, that remain in the air long enough to be of hygienic as well aA, economic significance. Industrial dust particles are predominantly of the order of 1 micron ,vi size. Tremendous numbers are also present in the submicroscopic range--'] below 0.5 micron, but those below 0.1 micron are not believed at present ? Air Contaminants 153 to be of practical importance, possibly due to their exceedingly small mass in comparison with the balance of airborne matter. In fact, particles this small may become the permanent atmospheric impurities that have little,if any, opportunity of settling because of the continual motion imparted to them by air currents and the molecular activity of gases (Brownian Movement). Compiled by W. G. Frank and Copyrighted, used by permission; ' Eio. X. Sizes and Characteristics op Airborne Particulate Matter The survey1 of atmospheric pollution in 14 American cities conducted from 1931 to 1933 indicated the average size of outdoor dust particles lo be 0.5 micron, as collected by the Owens jet dust counter and measured floder the microscope. Inability of the light field microscope to reveal CHAPTER 8 particles in the 0.1 micron vicinity may have influenced the determination of average particle size. , The lower limit of particle size visible to the naked eye cannot be stated definitely. It depends not only upon the individual eye,- but also upon the shape and color of the particle, intensity and quality of the light, and na ture of the background or opportunity for contrast. Under ideal condi tions a particle of 10-micron size might be recognized, while under less favorable conditions it may be impossible to distinguish a particle smaller than 50 microns. The lower limit of visibility probably ranges from 10 to 50 microns. . Dusts, powders and granular materials are frequently classified by refer ence to the size of screens used for separation. Particles above 40 microns Iare said to be the screen sizes and those below, the sub-screen or microscopic sizes. Approximate or theoretical sizes of particles corresponding to the mesh scale of the U. S. Standard Sieve Series are given in Table 1. Microscopic examination of screened dust indicates that the average diameter of a sample of irregular particles may be substantially larger Table 1. Relation op Screen Mesh to Particle Size U. S. Standard Sieve Mesh... 400 325 200 140 100 60 35 18 Nominal Sieve Opening in Microns........................................ 37 : 44 74 105 149 250 500 1000 than the openings of the screen through which it has passed, if the particle ,3 shapes deviate considerably from the spherical form.2 The smallest di-hj mension of many such particles will correspond with the maximum per missible distance between the wires of commercial screens made to ASTM g; Standard Specifications. Screening does not give sharp separation into size groups, and accordingly, such a classification is statistical rather than absolute. AIR POLLUTION BY SMOKE, ASH AND CINDERS # . '' Total airborne solids settling in urban areas are usually reported as soot \ fall in tons per (square mile) (month). Such data published for the cities in this country range from 20 to 200 tons per (square mile) (month). To :> the air conditioning engineer this information may indicate the effective- > ness of smoke abatement or fuel combustion control methods in his locality, J5 but it does not provide a suitable index,of the suspended dust that air,;- cleaners in a ventilating system are expected to capture.' *6 Gravimet ric or weight data of the type given in Table 2 are preferable. In soBM&t cases airborne particle counts may be necessary, as for pollen, bacteria, & spores, and insoluble dusts causing illness or lung disease. S-j Dust concentrations by weight cannot be converted readily to concern;Jt' trations by particle count because of the variability of particle size, shape v and specific gravity, and the inherent characteristics of dust counting and weighing procedures. One milligram of dust per cubic meter of air may*4 represent dust counts from 1 million to 100 million particles per cubic foot,% of air (lightfield microscope technic) according to the size distribution Air Contaminants 155 the airborne dust sample. Information of this type for a specified applica tion is best obtained by simultaneous sampling for both counting and weighing and noting carefully at the time all factors that might affect the reproducibility of the count-weight ratio. Smoke Abatement and Air Pollution Control . Successful abatement of atmospheric pollution caused by smoke requires the combined efforts of the combustion engineer, industrial executive, public health officer, city planning commission and the community at large. Electrification of industry and railroads, increases in the use of domestic oil and gas furnaces, and segregation of industrial districts are gradually providing effective aid in the solution of this problem. In the large cities where nuisance from smoke, fly-ash and cinders is more serious, limited areas obtain some relief by the use of district heating. (See Chap ters 14,15 and 16 for further discussion on fuel burning teclmic:) Table 2. Dost Concentration Ranges ` . Location Grains per 1000 Cu Ft* Rural and suburban districts.. Metropolitan district Industrial districts.......... Ordinary factories or workrooms. . Excessively dusty factories or mines Minimum explosive concentrations 0.02-0.2 0.04-0.4 0.1 -2.0 0.2 -4.0 4r-400 4000-200,000 * 1 grain per 1000 cu ft = 2.3 milligrams per cubic meter. 1 or per cubio foot = 1 gram per liter = 1000 grams per cubic meter Milligrams per Cubic Meter 0.1 - 1.0 0.5 -10 10-1000 10,000-500,000 many present ordinances limit the number of minutes in any one hour that smoke of a specified density (determined by comparison with a Rmgel- mann Chart which is described in Chapter 52) may be discharged. There is now considerable interest and activity in the control of air pol lution factors in addition to smoke. Difficulty in the establishment of acceptable criteria for certain corrosive and irritant gases, such as fluorides and the oxides of sulphur and nitrogen discharged with the gases of com bustion, and the frequently complicated technical and economic problems encountered in control, have delayed the drafting and enforcement of legislative measures. Recent reports of an increased incidence of diseases, such as pneumonia and lung cancer, in areas high in certain air contami nants, require further critical investigation before acceptance. The values finally adopted will undoubtedly be lower than the M.A.C. (Maximum Allowable Concentration) limits for use in industry, because the exposure is continuous compared with the 8-hour day, 5 or 6-day week upon which M.A.C. values are based, and because the exposed population contains individuals with greater variation in age and health status. In foggy weather, or with an inversion of atmospheric conditions, accu mulation of gaseous contaminants may cause irritation of eyes, nose, and respiratory passages, and possibly cause even more serious physiological effects.' The Meuse Valley fog disaster (Belgium 1930) and the Donora STpog (Pennsylvania 1948) are classic examples in the history of gaseous air pollution. In both instances it is believed that irritant gases, princi- 156 CHAPTER 8 pally from industrial plants, accumulating during periods of exceptionally prolonged meteorological inversion and fog, contributed to the illness of many persons, and to the death of some who were especially susceptible. Absorption of Solar Radiation Absorption of solar ultraviolet light by smoke and soot is recognized as ' a health problem in many industrial cities. Measurements of solar radia tion in Baltimore6 by actinic methods demonstrated that ultraviolet light intensity in the country was 50 percent greater than in the city. In New York City7 a loss as great as 50 per cent in visible light was found by photo electric measurements. ODOR NUISANCE A problem companionate with smoke abatement is the control of odor nuisance in the neighborhood of industrial plants discharging noxious or offensive air contaminants. Community planning and zoning will avoid much of the difficulty in the future, but meanwhile many industrial cities must resort to corrective measures by requiring installation of air cleaning devices, alteration of manufacturing processes, or termination of the of fensive operation in residential or commercial districts. Control of outdoor odor nuisance is especially troublesome because of the extremely minute quantities of contaminant that are capable of offend ing through a wide area. New industrial chemicals with strange or un familiar odors tend to receive more attention from the neighborhood than the customary odors generated by well known processes and raw materials. Methods of odor control currently in use include charcoal adsorption, scrubbing towers and air washers, chlorination, condensation, masking, passage of the odorous air through combustion chambers, dispersion through a tall stack, and best of all, substitution of less offensive materials i whenever possible.8,9'1011 Control of air quality within buildings ventilated for human occupancy is discussed in Chapter 6. Tobacco smoke odors, cooking odors and body odors are air contaminants of the nuisance type which now command a decisive position in the standards of air quality for indoor comfort. How ever, the engineer will find, at times, that odors originating outside build- ' ings in industrial or business districts may determine the kind and capacity V of equipment he must provide for a high quality air supply installation, '.si INDUSTRIAL AIR CONTAMINANTS Many industrial processes are sources of contaminants. Their control > is an important function of the ventilating or air conditioning engineer, ; ; because the atmosphere within buildings is the medium whereby such finely divided matter is dispersed and transported from the source to remote locations where it may cause property damage, nuisance, fire, ex-A;, plosion, disease and even death. ./, Tables 3, 4 and 5 give maximum allowable concentration values for ";; many industrial air contaminants; Some of these values have been pro- ; .; i posed by ASA Sectional Committee Z37 on Allowable Concentrations of Toxic Dusts and Gases, and others by the Committee on Threshold Limits Ky of the American Conference of Governmental Industrial Hygienists. - The Air Contaminants 157 values have been adopted by the American Conference of Governmental In dustrial Hygienists and by many of the official industrial hygiene agencies. It must be emphasized that these limits in the great majority of in stances are only suggested maximum working levels since they are estimates, based in many cases upon incomplete environmental and medical studies. Where there is agreement between the ASA Standard Z37 and A.C.G.I.H. values, reliability of the ASA Standard is increased. The values are not fixed, but are subject to revision, upward or downward, with the develop ment of new' information. There is by no means complete agreement regarding these values among responsible industrial hygienists. In applying these guide limits, the following factors must be considered: 1. The duration of exposure is 8 hr a day for 5 or 6 days a week. 2. The measurements are indicative of the concentration in the breathing zone of the exposed person. 3. The M.A.C. is usually accepted as the average exposure value when the upper limits do not greatly exceed the M.A.C. value. For example, it cannot be assumed that if 100 ppm is considered safe for 8-hour exposure, that 800 ppm for one hour will be permissible. . 4. Two substances with similar M.A.C. values may be quite different as to phys iological effects at other concentrations. In one instance the selection of a limit may be predicated upon- a discomfort factor, with a wide margin of safety before systemic effects would be encountered, while in another case the value represents an appreciable fraction of the concentration which may be associated with severe and irreversible injury. 5. These values are upper limits; it is desirable to operate well below the levels if the engineering and economic factors permit. The prudent engineer will incor porate a reasonable margin of safety in his estimates of ventilation capacity. In Table 3, Column 1 lists the ASA Sectional Committee Z37 M.A.C. values; Column 2, those of the A.C.G.I.H. Committee on Threshold Limits. Column 3 gives the value in grams per cubic meter or ounces per 1000 cu ft for-the corresponding A.C.G.I.H. limits; Column 4 shows the liquid ounces of chemical, if liquid at 20 C (68 F), which, if equally dis persed in 1000 cu ft, would give the corresponding M.A.C. In Table 4, Columns 1 and 2 are respectively the M.A.C. values from the ASA and A.C.G.I.H. Committees. In Table 5, the M.A.C. values for industrial dusts as given were obtained from data of the A.C.G.I.H. Committee on Threshold Limits. A.C.G.I.H. limits for either gamma or Roentgen radiations are 0.3 roent gens per week. Information on the properties and effects, with respect to health, of specific industrial air contaminants is available in publications listed at the end of this chapter. FLAMMABLE GASES AND VAPORS Adequate ventilation is a primary requirement for minimizing the hazard of fire or explosion due to gases and vapors. The need for good ventila tion is not removed by the use of other precautions, such as the elimina. tion of known ignition sources, segregation of hazardous operations, adop tion of safe building construction, and installation of automatic alarms. Some safety engineers regard over-ventilation of an operation employing flammable liquids as a legitimate operating charge for the privilege or necessity of using a dangerous process. However, it is not possible to 158 CHAPTER 8 1956 Guide ' ' ' 3*| Table 3. Maximum Allowable Concentration of Gases and Vapobb . Substance ASA Stand ards M.A.C. ppm by volume Acetic add........................... ............................. Acetic anhydride........................................... .. Acrolein................................................................. Acrylonitrile.......................................................... Amyl alcohol (iso)............................................... A.kiiimo........... 1,3-Butadiene.............................. -....................... ....................................................................................... Butyl "cellosolve" (2 butoxyethanol)... Carbon disulfide............................................. ; "Cellosolve" (2-ethoxyethanol).................... 100 20 100 1-Chloro-l-nitropropane.................................. Cydopropane (propane)........................ 1-2 Dibromoethane (ethylene dibromide) 1,2-Dichloroethane (ethylene dichloride] D i chloromonofluormethane........................ 1,2-Dichloropropane (propylene dichlo- Dimethylaniline................................................ Ethyl alcohol................................................1 Ethylene chlorhydrin.................................... Fluorotrichloromethane.............................. * Heptane............................................................... 10 Threshold Limit Values A.C.G.I.H.* 1954 ppm 200 10 5 1000 0.5 20 100 200 100 5 0.05 35 1 1000 100 250 200 5000 20 100 25 200 100 1 75 25 100 20 5 400 100 100 400 400 25 50 1000 100 100 200 15 500 1000 10 75 1000 25 5 1 100 400 1000 25 200 200 1000 5 100 400 100 100 0.1 1000 5 500 500 Gm/cu m or Os/1000 cu ft ' ii/1000 cu ftb 0.36 0.02554 0.02085 .2.4130 0.1145 0.04336 0.069 1.064 0.36 0.019 0.11393 0.00653 0.3030 0.735 0.948 0.900 . .0.43 0.02 0.02 2.42 0.05 0...0.2 0.03 0.36 1.04 0.0622 . 0.157 0.54 0.76 0.53 0.3465 0.0905 0.488 0.101 0.022 1.375 0.409 1.34 0.6875 0.02 1.69 0.3005 4.94 0.405 0.794 0.0878 1.74 4.20 0.0589 0.3265 6.98 0.045 0.02475 0.00515 0.36 1.44 0.24 0.59 1.25 0.4 0.29 0.07 0.02 0.003 0.868 0.892 0.01645 0.18 0.303 5.62 0.006135 2.045 0.96 0.09 0.315 -& ^9 I $f .*- i St si T? I %} I I mMjf$1: .AT Sf: Si -.01 aJ i Ay $ & 41; i Air Contaminants 159 Table 3. Maximum Allowable Concentration of Gases and Vapobs (Concluded) Substance ASA Stand ards M.A.C. ppm by volume Threshold Limit Values A.C.G.I.H.* 1954 Ppm Gm/cu m or Oz/1000 cu ft Oz/1000 cu ftb Hexane............................................................. Hydrogen chloride............................................ Hydrogen cyanide........................................ ..... Hydrogen fluoride. ............................ Hydrogen selenide....................................... Hydrogen sulfide............................ ............ . 500 5 10 3 0.05 20 1.76 0.00746 0.01104 0.00245 Iodine............... , Isophorone............. Isopropyl alcohol. Isopropyl ether... Mesityl oxide......... Methyl acetate... Methyl alcohol.................................................... Methylal................................................................ Methyl bromide.................................................. Methyl butyl ketone (hexanone).............. Methyl"cellosolve" (2-methoxyethanol). Methyl "cellosolve" acetate......................... Methyl chloride....................rr............................. Methyl chloroform (1-1*1 trichloroethane): Methylcyclohexane........... ......................... Methylcydohexanol................................... Methylcyclohexanone............................... Methyl formate ........ ................................... Methyl iso-butyl ketone.................. Monochlorobenzene............................ Monofluorotrichlofomethane..... Naphtha (coal tar)............................ Naphtha (petroleum)...................... Nickel carbonyl.................................. Nitrobenzene.................................................. Nitroethane............................................................ Nitrogen dioxide................................................ Nitrogen oxides (other than nitrous ox ide) ......................................................................... Nitroglycerine....................................................... Nitromethane....................................................... 2-Nitropropane.................................. Nitrotoluene......................................... Octane..................................................... Ozone...................... ............................ Pentane................................................. Pentanone (methyl propanone) . Phenol...................................................... Phosgene................................................. Phoephine............................................... Phosphorus trichloride................ Propyl acetate..................................... Stibine.................... Stoddard solvent. otyTene monomer hulf ur chloride Sulfur dioxide.'..'.'.'.'.'........................................ rl:h ^-Tetrachloroethane..'........ ^trachloroethylene (perchloroethylene) Toluene. Toluidine...;;;'" trichloroethylene turpentine Vinyl Chloride " " Xylene___ 200 200 200 200 1 25 400 500 50 200 200 1000 20 100 25 25 100 500 500 100 100 100 100 75 1000 200 500 0.001 i 100 5 25 0.5 100 50 5 500 1000 200 5 1 0.05 0.5 200 0.1 500 200 1 5 200 200 5 200 100 500 200 0.01039 0.141 1.022 2.085 0.2005 0.606 0.2618 3.11 0.0778 0.352 0.7775 0.1208 0.2086 2.005 0.466 0.458 0.2554 0.409 0.3465 5.61 0.638 1.945 0.000007 0.00503 0.307 0.00464 0.2495 0.182 0.028 2.33 2.94 0.704 0.00281 0.834 2.845 0.85 0.00552 0.343 1.358 0.752 0.0219 1.072 0.556 1.28 0.868 * A.C.GJM. American Conference of Governmental Industrial Hygienists. ** Liquid ounces (at 20 C) of chemical in 1000 cu ft. c From 1953 list. 2.54 0.004 0.015 0.003 0.0002 0.15 1.22 2.75 0.22 0.62 0.32 3.5 0.04 0.41 0.078 0.11 0.22 2.44 0.49 0.48 0.25 0.49 0.3 3.59 0.71 2.6 0.000006 0.004 0.275 0.003 0.21 0.17 0.23 3.17 4.5 0.82 0.0018 0.885 3.4 0.89 0.003 0.02 0.810 0.83 0.02 0.70 . 0.58 1.33 0.96 . 160 CHAPTER 8 . 1956 Guide gf ' ' . ,**$*/ apply a reasonable safety factor to the ventilation estimate without con sideration of the concentrations of gases or vapors that approach the danger / point. Safety engineers prefer to limit the concentration to j or 5 of the : lower explosive limit, and this fact should be given full weight in determin- * ing the capacity and design of ventilating equipment. Rarely should . consideration be given to operation above the vpper explosive limit in the open areas of buildings or rooms--even though unoccupied--because the danger of temporary drop of gas concentration to a point within the ex plosive range is too great. Ability of a flammable liquid to form explosive mixtures is determined largely by its vapor pressure, volatility, or rate of evaporation. Flash Table 4. Limits fob Toxic Dusts, Fumes and Mists Substance A.S.A. Standards, MLA.C. mg/cu m Threshold Limit Values, A,C.G.LB. 1954 mg/cu m Antimony.......... ................................................................................... Arsenic................................................................................................... Barium-..................................... i........................................................ Cadmium.............................................................................................. . Chiorodiphenyl.................................................................................... Chromic acid & chromates as CrOt............................................ Cyanide as CN................................................................................... Dinitroioluene...................................................................................... O-Dinitrocresol..................................................................................... Fluorides............................................................................................... Iron Oxide fume.................................................................................. Lead........................................................................................................ Magnesium oxide fume.................................................................... Manganese,,.......................................................................................... Mercury.................................................. ............................................... Parathion (0,0-diethyl-O-p-nitrophenyl thiophosphate).. Pentachloronaphthalene................................................................. Pentachlorophenol............................................................................. Phosphorus (yellow)................................. ...................................... Phosphorus pentachloride.............................................................. Phosphorus pentasulfide................................................................. Selenium as Sc..................................................................................... Sulfuric add..................................................................................... Tellurium.............................................................................................. Tetryi..................................................................................................... Trichloronaphthalene........ .............................................................. Trinitrotoluene.......................'............................................................ Uranium (soluble compounds)...................................................... Uranium (insoluble compounds)................................................. Zinc oxide fumes................................................................................ 0.1 (W) 0.1 0.15 0.1 0.5 00..15 1 0.1 5 10..25 2.5 15 0.15 1605.1 0.1 0.5 001 ..15 001..11 1.5 5 1.5 0.05 0.25 15 point is a convenient method of expressing this property in terms of the temperature scale. It may be defined as the temperature to which a com- 5 bustible liquid must be heated to produce a flash when a small flame is-ip passed across the surface of the liquid. The higher the flash point, the i;; more safely can the liquid be handled. Liquids with flash points under- 70 F should be regarded as highly flammable. jV-? Upper and lower limits of flammability of gases and vapors, and the flashy " points of the corresponding liquids are given in Table 6. Methods for estimating the flammable limits of mixtures of gases <8^- vapors must be applied with caution; the reader is referred to other publi-jA? cations for this information.12-13 ,;11 Design of equipment for the control of combustible anesthetics is lined in Chapter 7. Construction of equipment for handling air contain-, Air Contaminants 161 ing flammable substances, or operating in atmospheres so contaminated, is discussed in Chapter 46. It is customary to report the concentrations of flammable gases or vapors in percent by volume, or volume percent Comparison with concentra tions on the part per million scale used in chemical, medical or industrial hygiene literature is readily made by the conversion: 1 percent = 10,000 ppm (parts of contaminant per million parts of air, by volume, or in other words, cubic feet of contaminant per million cubic feet of air). It will be noted in Table 6 that nearly all of the substances listed have lower explosive limits above 1.0 percent, while, the maximum allowable concentrations for gases and vapors in Table 3 are below 1006 ppm or 0.1 percent in most cases. Therefore, control of toxic or injurious vapors to levels below their maximum allowable concentrations for health usually requires much more effective ventilation than for the prevention of a fire hazard. COMBUSTIBLE DUSTS A dust explosion is essentially a sudden pressure rise caused by the very rapid burning of airborne dust. The primary explosion often originates Table 5. Limits fob Minebal Dusts Substance) Threshold Limit Values A.C.G.I.B. 1954 mppcfa Alundum....................................... Asbestos............................................ . Carborundum.............. ................. Cement............................ . Dust (nuisance, no free silica). Mica (below 5% free silica)..... ... Silica--high (above 50% free SiO) . , Silica--medium (5 to 50% free SiO*), Silica--low (below 5% free SiOi)----Slate (below 5% free SiOi)............. .... Soapatono (below 5% free SiO) . Total dust (beiow 5% freo SlO,)! * mppcf--million particles per cubic foot of air, standard light field count. 50 5 50 50 50 20 250 50 50 2200 50 from a small amount of dust in suspension exposed to a source of ignition and the pressure and vibration it creates may be sufficient to dislodge large accumulations of dust on horizontal ledges or surfaces of the building and equipment, thereby creating a secondary explosion of great force. Thus the air conditioning engineer is involved for two reasons: (1) to obtain a movement of dust-laden air into exhaust hoods or openings, and through ventilating or pneumatic conveying ducts, in a manner that will prevent accumulation of highly flammable dust at points where it could ignite inside the equipment; and (2) to so design process ventilation as to prevent the escape of dust which might settle on horizontal surfaces and become a potential source of disaster at some distance from the dusty operation. (See Chapter 46). Intensity of a dust explosion depends upon: chemical and thermal properties of the dust; particle size and shape; concentration in air; propor tion of inert dust in the air; moisture content and composition of the air; size and temperature of the ignition source; and degree of dispersion of the dust cloud. Investigations on the explosibility of dusts require determina tion of the maximum pressure developed during explosion of a known air concentration, as well as determination of the rate of pressure rise. In- 162 CHAPTER 8 1956 Guide Table 6. Limits of Flammability of Single Gases and Vapors Approximate In Air at Ordinary Temperatores and Pressures . Gas ob Vapor Lower Limit Percent by Volume Upper Limit Percent by Volume Closed Cupb Flash Point Fahrenheit NBFU CLASSIFI CATION Acetyldehyde Acetone........... Acetylene -- AUyl alcohol. Ammonia.. Amyl alcohol. ... Amyl chloride. .. Amylene.................. Benzene (benzol) Benzyl chloride.. Butane.................... Butyl acetate -- Butyl alcohol.... Butylene............. Carbon disulfide Carbon monoxide Crotonaldehyde.. . Cyclohexane......... Cyclopropane... Decane.................... Dichloroethylene (1, 2) Diethyl selenide............. Dioxane............................... Ethane................................. Ether (diethyl)............... Ethyl acetate.. Ethyl alcohol.. Ethyl bromide. Ethyl celioeolve Ethyl chloride. Ethylene............ ........................ Ethylene dichloride................. Ethyl formate............................. Ethyl nitrite--........................ Ethylene oxide............................ Furfural (125 C) - Gasoline (variable) Heptane........... .......... Hexane............. Hydrogen cyanide. Hydrogen.................................... Hydrogen sulfide ---------- -Illuminating gas (coal gas). Isobutyl alcohol.......-----Isopentane................................... Isopropyl acetate Isopropyl alcohol Methane.................. Methyl acetate. Methyl alcohol. 4.0 2.5 2.5 2.5 15.5 111...266 11..13 1.6 1.4 211...702 122..15 1.3 2.4 0.67 2.2 3.3 6.7 26 4.0 26..72 2-7 3.0 3-0 2.1 1.411--.012.5 5.6 4.0 4.3 5.3 1.7 1.3 12..80 5.0 3.1 6.7 5172.8 80 26'6 els 8.4 15.0 *9l7 50 74.2 15.5 8.4 120..65 12.8 22.2 12.5 36.5 11.5 19.0 11.3 15.7 14.8 28.6 15.9 16.6 50 80 7.46-.70.6 6.9 40.0 74.2 45.5 33.0 7.8 15.5 36.5 0-17 . *70 100 12 140 "84 -22 551 115 57 54 -49 28 54 *i04 -58 56 -4 -31 140 -50 25 -15 *82 . 43 53 **i4 52 I I II HI I hi in i n I HI n ii i n ii iu i ii ii in i ii i m ii ii i ii Methyl bromide......................... Methyl butyl ketone............... Metbyl chloride............. ............ Methyl cyclohexane................. Methyl ethyl ether................... Methyl ethyl ketone............... Methyl formate.......................... Methyl propyl ketone............. Natural gas (variable)............; Naphtha (benzene).................. Naphthalene................................ Nonane........................................... .Octane............................................. Paraldehyde ............................ .. Pentane........................................... 1183...225 21..10 1.8 5.0 1.5 41..31 0.6 0.83 0.95 1.3 1.4 8.0 18.7 ioli 9.5 282..72 163.-05 *25 -35 -320 2(Mio 176 56 u i ii i hi iii ii Air Contaminants 163 Table 6. Approximate Limits of Flammability of Single Gases and Vapors In Air at Ordinary Temperatures and Pressures* (Concluded) Gab or Vapor Lower Limit Percent by Volume Upper Limit Percent by Volume Closed Cuph Flash Point Fahrenheit NBFU CLASSIFI CATION0 Propane....................................... Propyl acetate.......................... Propyl aloohol.......................... Propylene................................... Propylene dichloride.............. Propylene oxide........................ Pyridine...................................... Toluene (toluol)....................... Turpentine................................. Vinyl ether................................ Vinyl chloride........................... Water gas (variable).............. Xylene (xylol).............. --:. 2.1 1.8 2.1 2.0 3.4 2.0 1.8 1.3 0.8 1.7 4.0 6.0 1.0 10.1 8.0 13.5 11.1 14.5 22.0 12.4 7.0 27.6 21.7 70 6.0 . 58 59 60 74 40 95 63 II H II III II IU II 4 Adapted from: Fire and Explosion Hazards of Combustible Gases and Vapors, by G. W. Jones; Chapter 13, Industrial Hygiene and Toxicology, edited by F. A. Patty (Interscience Publishers, 1948); Properties of Flammable Liquids, Gases and Solids (Associated) Factory-Mutual Fire Ins. Cos., January (1940); and National Fire Codes for Flammable Liquids, Gases, Chemicals and Explosives--1945 {National Fire Protec tion Association). b Closed cup refers to the equipment used in flash point determinations. ' 0 From Standards for Storage, Handling and Use of Flammable Liquids (National Board of Fire Un derwriters, No. 30, July -1954)...,. __ vestigators frequently experience difficulty in obtaining dust suspensions of uniform dispersion, and this should be kept in mind when comparing results from several sources.14 Minimum explosive concentrations of airborne dusts already tested range from 0.01 to 0.5 oz per cubic foot, or 10 to 500 grams per cubic meter of air. Maximum pressures generated have been reported as high as 500 psi, although they are more likely to be of the order of 50 psi. Investiga tions on the flammable characteristics of dusts are currently made at 0.1 and 0.5 oz. per cubic foot.15"21 ATMOSPHERIC POLLEN Properties of pollen grains discharged by weeds, grasses and trees and responsible for hay fever, are of special interest to designers of air cleaning equipment (see Allergic Disorders in Chapter 7, and Air Cleaning, Chap ter 34). Whole grains and fragments transported by the air range chiefly between 10 and 50 microns in size, but some have been measured as small as 5 microns, and others over 100 microns in diameter. Ragweed pollen grains are fairly uniform in size within the range of 15 to 25 microns. Pollen grains can be removed from the air more readily than the particles of dust prevalent in outdoor air or produced by dusty processes, since the latter predominate in the range of 0.1 to 10 microns in size. Most grains are quite hygroscopic and therefore vary in weight with the humidity. Illustrations and data on individual pollen grains are available in the botanical literature.22 , 23 24 Geographical distribution of plants known to produce hay fever is also recorded.26, 26 The quantity of pollen grains in the air is generally estimated by exposing an adhesive-coated glass plate outdoors for 24 hr, and then counting cali brated areas under the microscope. Methods are available for determin ing the number of grains in a measured volume of air,26,2728 but their greater accuracy has not caused them to replace the more simple gravity slide method used for most pollen counts. Counting technics vary some what, but the daily pollen counts reported in local newspapers during the 164 CHAPTER 8 1956 Guide hay fever season usually represent the number of grains found on 1.8 sq cm of a 24-hr gravity slide. j Hay fever sufferers may notice the first symptoms when the pollen count is 10 to 25, and in some localities the maximum figures for the seasonal peak may approach 1000 for a 24-hr period, dependirlg upon the sampling and reporting methods of the laboratory. Translation of gravity counts by special formulas to a volumetric basis, or the number of grains per cubic yard or per cubic foot of air, is unreliable because of the complexity of the modifying factors. When such information is important, it is best obtained directly by a volumetric instrument. The number of pollen grains per cubic yard of air evidently varies from 2 to 20 times the number found on 1 sq cm of a 24-hr gravity slide, depending on grain diameter, shape, specific gravity, wind velocity,- humidity and physical placement of the collecting plate.29- 30- 31 AIRBORNE BACTERIA ' Study of the occurrence and significance of micro-organisms in the at mospheres of the indoor world is absorbing the energies of a substantial number of physicians, bacteriologists, aerobiologists, physicists, public health workers, engineers and hospital personnel. Some data are available on the types and quantities of bacteria found in a variety of spaces, but it is not possible at present to use this information as a conclusive, index of the potential health hazard of a given environment. The reported number of airborne organisms may vary from 1 to 1000 per cubic foot of air, influ . enced somewhat by the method of testing.32 Many are attached to the dust particles present in the air. Where it seems advisable or desirable to control the bacterial content of rooms, public conveyances or buildings, highly effective methods are available (see Chapter 7), and their extended use may do much to assist the workers in this field in accumulating the necessary mass of evidence that will decide the practical value of air sterilization for the control of communicable disease. It is now well established that ultraviolet radia tion is feasible for the protection or preservation of pharmaceuticals, cos metics, and food products. RADIOACTIVE AIR CONTAMINANTS33 Radioactive air contaminants are physically similar to ordinary indus trial and chemical plant contaminants. They differ from ordinary con taminants, however, in that they may be highly toxic when ingested and may present a direct radiation hazard when accumulated in appreciable quantities. Another factor which must be considered in the filtration of these materials is the possibility of their being concentrated in plant and animal life in the area of contamination. Concentrations resulting from absorptions by plants and subsequent feeding of animals in the magnitude of several thousand times, is not unusual. Tolerances for radioactive con taminants have been established and are under continuing study and re- view. Guidance in regard to tolerance levels for discharge of contaminated air in different types of localities can best be had from the classified litera-. ture which is available through proper clearance procedures. - .i REFERENCES - ` Atmospheric Pollution of American Cities for the Years 1931 to 1933, J. E. Ives, et al (17. S. Public Health Service Bulletin No. 224, March 1936). ' 1 Micrometries, The Technology of Fine Particles, by J. M. DallaValle (Pitman ' Publishing Corporation, 1943). Air Contaminants 165 * Atmospheric Pollution Due to Smoke, by A. C. Stern (Heating and Ventilating, May, 1945). Atmospheric Pollution Due to Dust and Cinders, by A. C. Stern (Heating and Ventilating, July, 1945). 4 Sootfall Studies for New York City, by J. Siegel and B. Feiner (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, September, 1945, p. 495)' ` The Use of Fuel Consumption and Equipment Data in the Abatement of Atmos pheric Pollution, by A. C. Stern (A.S.H.V.E. Journal Section, Healing, Piping and Air Conditioning, August, 1945, p. 447-454). Effects of Atmospheric Pollution Upon Incidence of Solar Ultra-Violet light, by J. H. Shrader, M. H. Coblentz and F. A. Korff (American Journal of Public Health, Vol. 19, 1929, p. 7). 7 Studies in Illumination--III: A Study of the Loss of Light Due to Smoke on Manhattan Island, by J. E. Ives (C7. S. Public Health Service Bulletin No. 197, June, 1930). Study and Control of Industrial Atmospheric Pollution Nuisances, by F. M. Stead (American Journal of Public Health, Vol. 35, May, 1945, p. 491-498). Evaluation of Odor Nuisance in the Manufacture of Kraft Paper, by J. M. DallaValle and H.-C. Dudley (17. S. Public Health Service Reprint No. 2022, Public Health Reports, Vol. 54, January 13, 1939, p. 35-43). ""Disposal of Refinery Wastes, Section II: Waste Gases, Vapors, Sludges and Dusts (American Petroleum Institute, New York City, 1938). 11 Offensive Trades, by David Ronald (William Hodge and Co., London, 1935). 11 Limits of Inflammability of Gases and Vapors, by H. F. Coward and G. W. Jones (17. S. Bureau of Mines Bulletin No. 279, 1939). 13 Inflammation Limits and Their Practical Application in Hazardous Industrial Operations, by G. W. Jones (Chemical Reviews, Vol. 22, February, 1938). 14 Private Communication, by Hylton R. Brown (Bureau of Mines, College Park, Maryland). " Explosibility of Agricultural and other Dusts as Indicated by Maximum Pres sure and Rates of Pressure Rise, by P. W. Edwards and L. R. Leinbach (U. S. De partment of Agriculture Technical Bulletin No. 490, October, 1935). 13 Dust Explosion Hazards in Plants Producing or Handling Aluminum, Magne sium, or Zinc Powder, by H. R. Brown (V. S. Bureau of Mines Information Circular No. 7148, March, 1941). *' Inflammability and Explosibility of Metal Powders, by I. Hartman, J. Nagy, and H. R. Brown (17. S. Bureau of Mines Report of Investigation No. 3722, October, 1943). 13 Inflammability and Explosibility- of Powders Used in the Plastics Industry, by I. Hartman and J. Nagy (U. S. Bureau of Mines Report of Investigation No. 3751, May, 1944). . " Industrial Dust Explosions, by H. R. Brown (17. S. Bureau of Mines, Informa tion Circular No. 7309, January, 1945). 70 Proposed Code for the Prevention of Dust Explosions in the Plastics Industry (National Fire Protection Association, Boston, May, 1945). s" National Fire Codes for the Prevention of Dust Explosions (National Fire Pro tection Association, Boston, 1944). Contains codes for aluminum, magnesium, coal, pulverized fuel, flour, spice, starch, sugar, cocoa, sulfur and wood. 22 An Introduction to Pollen Analysis, by G. Erdtman (Chronica Botanies Co.> Waltham, Mass., 1943). 23 Pollen Grains, by R. P. Wodehouse (McGraw-Hill Book Co., New York, 1935). 24 Atmospheric Pollen, by R. P. Wodehouse (Aerobiology, p. 8-31, Publication No. 1<, American Association for the Advancement of Science, Washington, D. C., 1942). 25 Hayfever Plants, by R. P. Wodehouse (Chronica Botanies Co., Waltham, Mass., 1945). ,T 23Hay Fever: A Geographical and Botanical Survey, by E. R. Squibb and Sons, New York, 1937. 27 Techniques for Appraising Air-Borne Populations of Microorganisms, Pollen and Insects (Phytopathology, Vol. 31, March, 1941, p. 201-225). 23 Apparatus for Determining the Pollen Concentration of the Atmosphere, by B. J. Uody, W. F. Kinney and N. A. Kerstein (Research Department, the Detroit Edison Company, Detroit). w '&* 166 CHAPTER 8 1956 Guide * The Volumetric Incidence of Atmospheric Allergens, by O. C. Durham (Journal of Allergy, Vol. 14, September, 1943, p. 455-461). * The Volumetric Incidence of Atmospheric Allergens, II: Simultaneous Measure ments by Volumetric and Gravity Slide Methods, by O. C. Durham (Journal of Allergy, Vol. 15, May, 1944, p. 226-235). ** Air-Borne Fungus Spores as Allergens, O. C. Durham (Aerobiology, p. 32-47, Publication No. 17, American Associationfor the Advancement of Science, Washington, D. C., 1942). ` M Sampling Devices, by H. G. DuBuy and A. Hollaender (American Journal of Medical Science, Vol. 299, February, 1945, p. 172-177). . . ** Ventilation Problems in Safe Handling of Radioactive Materials, by W. W. McIntosh, paper presented at ASME Spring Meeting, March 1952. BIBLIOGRAPHY Abstracts and Bulletins (monthly, annual and special) Industrial Hygiene Founda tion, Inc., Pittsburgh, Pa. ' - .. Aerobiology, Publication No. 17 (American Association for the Advancement of Science, Washington, D. C., 1942). A ir Sanitation and Industrial Ventilation, by W. N. Witheridge (Detroit, Mich., 1945). . American Industrial Hygiene Association Quarterly (4400 Fifth Ave., Pittsburgh, Pa.). . - Analytical Chemistry of Industrial Poisons, Hazards and Solvents, by M- B. Jacobs (Interscience Publishers, New York, 1941). Bibliography of Industrial Hygiene, 1900-1943 (17. S. Public He'alth Service Bul letin No. 289, 1945). Clouds and Smokes, by W. E. Gibbs (P. Blakiston's Son & Co., Philadelphia, Pa., 1924). Determination and Control of Industrial Dust, by Bloomfield and DallaValle (17. S. Public Health Service Bulletin No. 217, 1935). Dust, by S. C. Blacktin (The Sherwood Press, Cleveland, 1934). (The) Environment and Its EBect upon Man (Harvard School of Public Health, BosIntodnu, s1t9ri3a7l)D. ust, by Drinker and Hatch (McGraw-Hill Book Co., New York, 1936). Industrial Health Engineering by A. D. Brandt (John Wiley & Sons, Inc., New York, 1947). .. Industrial Hygiene and Toxicology, edited by F. A. Patty (Interscience Publishers, Inc., New York, Vol. I, 1948 and Vol. II, 1949). Journal of Industrial Hygiene and Toxicology (monthly) (Harvard School of Public Health, Boston, Mass.). See cumulative abstract and subject indexes. Manual of Industrial Hygiene, by W. M. Gafafer, et al (U. S. Public Health Service, W. B. Saunders Co., Philadelphia, 1943). Noxious Gases and the Principles of Respiration Influencing Their Action, by Hen derson and Haggard (American Chemical Society Monograph Series No. 35, Reinhold, New York, 1943). Occupation and Health, two. volumes (International Labor Office, Washington, D. C.). Toxicology and Hygiene of Industrial Solvents, by Lehmann and Flury, trans-; lated by Eleanor King and H. F. Smyth, Jr. (Williams and Wilkins, Baltimore, 1943). -Vf -wr 'Tms* M CHAPTER 9 HEAT TRANSMISSION COEFFICIENTS OF BUILDING MATERIALS Heat Transfer Symbols; Calculating Overall Coefficients; Conductivity of Homo geneous Materials; Soil Conductivity and Specific Heat; Surface Conductance; Air Space Conductance; Practical Coefficients and Their Use; Insulating Materials; Computed Coefficients of Walls, Roofs, Ceilings and Floors; Combined Ceiling and Roof Coefficients; Glass Coefficients; Calculating Surface Temperatures THE design of air conditioning or heating systems for buildings requires a knowledge of the thermal properties of the walls enclosing the space. (The term walls in this case, includes windows, doors, ceilings, floors, roofs, and skylights). The rate of heat flow through the walls under steady-state conditions at design temperatures is usually the basis for calculating the heat required. For"a given wall under standard conditions the rate is a specific value designated as U, the overall coefficient of heat transmission or thermal transmittance. It may be determined by test in a guarded hot box apparatus, or it may be computed from known values of the thermal conductance of the various components. Because testing of all combina tions of building materials is impracticable, the procedure and necessary data for calculation of the value of U are given in this chapter, together with tables of computed values for the more common constructions. HEAT TRANSFER SYMBOLS U * overall coefficient of heat transmission ot thermal transmittance (air to air); the time rate of heat flow expressed in Btu per (hour) (square foot) (Fahrenheit de gree temperature difference between air on the inside and air on the outside of a wall, floor, roof or ceiling). The term is applied to the usual combinations of materials, and also to single materials, such as window glass, and includes the surface con ductance on both sides. ' k ^ thermal conductionty; the time rate of heat flow through a homogeneous ma terial under steady conditions per unit temperature gradient through unit area per pendicular to the temperature gradient. Its value is expressed in Btu per (hour) ' (square foot) (Fahrenheit degree per inch of thickness). Materials are considered homogeneous when the value of k is not affected by variation in thickness or size of sample within the range normally used in construction. P = thermal conductance; the time rate of heat flow through a unit area of a ma terial from one of its surfaces to the other per unit temperature difference between the two surfaces. Its value is expressed in Btu per (hour) (square foot) (Fahrenheit de gree). The term is applied to specific materials as used, either homogeneous or heterogeneous, for the thickness stated, not per inch of thickness. / = film or surface conductance; the time rate of heat flow between a unit area of a surface and the surrounding air. Its value is expressed in Btu per (hour) (square loot of surface) (Fahrenheit degree temperature difference). Subscripts i and o are used to differentiate between inside and outside surface conductances, respectively. aa =- thermal c--ond* uctance o*f an air space; th- e time rate of heat flow through a unit rea of an air space per unit temperature difference between the boundary surfaces. s value is expressed in Btu per (hour) (square foot of area) (Fahrenheit degree). inductance of an air space is dependent on the temperature difference, the rel t- depth, the position and the character of the boundary surfaces. The lationsbips are not linear, and accurate values must be obtained by test and not uy computation. > 167 168 CHAPTER 9 1956 Guide e = emissivity; the ratio of the total radiant flux emitted by a surface to that emitted by an ideal black body at the same temperature. E = effective emissivity ; the combined effect of the surface eroissiVities e of the boundary surfaces of an air space; the boundaries assumed to be parallel and of large dimensions as compared to the distance between them. r = surface reflectivity; the ratio of the radiant flux reflected by an opaque sur face to that falling upon it. R = thermal resistance. Its value is obtained from the reciprocal of heat trans fer as expressed by V, k, C, / or a. It is expressed in (hours) (square feet) (Fahren heit degrees) per (Btu). For example, a wall with a U value of 0.25 would have a resistance value of R = 1/0.25 = 4.0. Therefore, 4 hours would be required for the transfer of one Btu for each square foot of area and each degree'of temperature dif ferential. CALCULATING OVERALL COEFFICIENTS From Chapter 5, Equation 7, the total resistance to heat flow through a wall is equal numerically to the sum of the resistances in series. 1 R-r = Ri 4- E* -f- I2i + Ri + - .. + Ed (1) where E>, Ri, etc., are the individual resistances of the wall components. Et = total resistance. Heat Transmission Coefficients of Building Materials 169 CONDUCTIVITIES AND CONDUCTANCES The method of calculating the overall coefficient of heat transmission for a given construction is comparatively simple, but accurate values of con ductivities and conductances must be used to obtain satisfactory results. In addition, there' are sometimes parallel heat flow paths of different re sistances in the same wall, and these may necessitate modification of the formula. In such cases calculated results should be checked by test. The determination of the fundamental conductivities and conductances requires considerable skill and experience to obtain , accurate results. It is recommended that, thermal conductivities of homogeneous materials be determined by means of the Guarded Hot Plate.1 For determination of conductances, a Guarded Hot Box method2 is generally used. Tables 1 and 2 give conductivities and conductances selected by the ASHAE Technical Advisory Committee on Insulation from available in formation. The values selected were those which in the judgment of the committee were good design values for surfaces, spaces, etc., and for the types of products marketed today. " DENSITY POUNDS rtK vwoit. rvw> Fig 1 Typical Variation op Thermal Conductivity with Density-for For a wall of a single homogeneous material of conductivity k and thickness x, with surface coefficients j\ and /,,, 1x 1 Ri `fi + i'+7o (2) Then by definition, XJ = i./et. For a wall with air space construction and consisting of two homogeneous^ materials of conductivities h and k3, thicknesses Xi and x2, respectively and separated by an air space of conductance o, . .A Bt1 = fi+kti+a--k+ ttj+o. (3), and . U = 1/Et In the case of types of building materials having non-uniform or irregu lar sections such as hollow clay tile or concrete blocks, it is necessary to use the conductance C of the section unit as manufactured instead of a conductivity k. The resistance of the section 1/C is therefore substituted for x/k in Equations 2 and 3. - y MEAN TEMPERATURE-FAHRENHEIT DEGREES Fig. 2. Typical Variation op Thermal Conductivity with Mean Temperature Conductivity of Homogeneous Materials Thermal conductivity is a property of a homogeneous material and of types of building materials such as lumber, brick, and stone, which may be considered homogeneous. Most insulating materials, except reflective types, are of a porous nature and consist of combinations of solid matter with small voids. The thermal conductivity of these materials will vary with density, mean temperature, size of voids, fibers, or particles, degree and extent of bond between particles, moisture present, and the arrange ment of fibers or particles within the material. The effect of density upon conductivity (at constant mean temperature) is illustrated for two fibrous materials in Fig. 1. Typical variation of con ductivity with mean temperature is shown in Fig. 2. Thermal Conductivity of Soil . . The following statements are based largely on results of a study3 made m the Engineering Experiment Station, University of Minnesota, and pub lished in Bulletin No. 28. Tests were made on nineteen different soils which represented a wide textural variety, including gravel, sand, sandy mam, silt loam and clay, as well as some crushed rocks and a fibrous peat. Moisture contents in tests varied from air-dried values to those greater *han the optimum moisture content; densities varied from a loosely-poured i '] l '! i ; b lift 170 CHAPTER 9 1956 Guide Table 1. Conductances (C) fob Subfaces and Air Spaces All conductance values expressed in Btu per (hr) (sg ft) (F deg tenij> diff) Section A. Surface Conductances for Still Air* Surface Emissivity Position of Surface Direction of Heat Flow Non-Reflective e 0.90 Reflective 0.20 Reflective = 0.05 ' RR Horizontal.................................................. Sloping--45 deg. Vertical.................. Slopin g--45 .deg.. Horizontal.. Upward Upward Horizontal Downward Downward 1.53 1.60 1.46 1.32 1.08 0.61 00..6628 0.76 0.92 00..9818 0.74 0 60 0.37 1.10 1.14 1.35 1.67 2.70 0.76 0.73 0.59 00..2425 1.32 1.37 12..2720 4.55 * Conductances are for surfaces of the stated emissivity facing surroundings having an emissivity equal to 0.9 and at the same temperature as the ambient air. . Values are based on a surface-air temperature differ ence of 10 F and for surface temperature of 70 F. (See Table 2 for surface conductances for moving air.) Position Heat of Flow Air Space Horiz. Up 45* Slope Up Vert. Horiz. 45 Slope Horiz. Down Down1 Thick ness*5 Inches 54 to 4 54 to 4 54 to 4 54 to 4 54 154 4 54 154 4 Mean Temp* F 50 50 90 50 50 90 50 50 90 50 50' 90 50 50 50 90 90 90 Temp Diff deg 10 30 10 10 30 10 10 30 10 10 30 10 20 20 20 20 20 20 Thermal Conductance-C Thermal Resistance-R. Value of Ec,d Value Df Ed 0.05 0.2 - 0.5 0.82 0.05 0.2 0.5 0.82 0.41 0.54 0.41 0.55 0.68 0.58 0.82 0.95 0.92 1.11 1.24 1.28 2.44 1.84 2.47 1.83 1.47 1.73 1.22 1.05 1.09 0.90 0.80 0.78 0.35 0.48 0.35 0.49 0.62 0.52 0.76 0.89 0.86 1.05 1.18 1.23 2.84 2.08 2.85 2.05 1.62 1.92 1.31 1.13 1.16 0.95 0.85 0.81 0.28 0.38 0.29 0.42 0.69 0.52 0.79 C.46v 0.80 0.99 1.08 1.16 3.52 2.64 3.49 2.37 1.94 2.19 1.44 1.27 1.25 1.02 0.92 0.86 0.24 0.30 0.25 0.38 0.43 0.42 0.65 0.71 0.76 0.94 1.00 1.12 4.14 3.36 4.07 2.65 2.30 2.40 1.54 1.41 1.32 1.08 1.00 0.89 0.28 0.18 0.11 0.42 0.31 0.25 0.69 0.58 0.52 0.98 0.87 0.81 3.57 5.56 8.94 2.38 3.23 4.03 1.45 1.73 1.92 1.02 1.15 1.23 0.31 0.20 0.13 0.48 0.37 0.30 0.82 0.71 0.64 1.18 1.07 1.01 3.23 5.00 7.82 2.08 2.70 3.35 1.22 1.41 1.56 0.85 0.93 0.99 ` ; ' * 'Jrr 1 rv /y, a At' ;V j& % Notes: *b SWphaeceres aofraunngifeoormf ththicickknneessssi,sbgoivuennde, dthbeygmiveonaecraovnediuycatauniucuevuis the average over the range; extreme values within the range differ therefrom by less than 10 percent. ' c Interpolation, and moderate extrapolation, of conductance values are permissiblefor other values of mean temperature, temperature difference and effective emissivity 23. d Effective emissivity of space, B, is given by ~ * -- d--------- 1 where ei and e* are the emissivities a \ tt f Tohf ethceosnudrufactcaenscoefs thoef haoirrizspoanctea.l sp(SaceeesSweictthionheCa.t fbloewlowd)o. wnward are substantially independent of * BasetdemonpeNraattuiorneadliBffeurreenacueo. f Standards data presented in Housing Research P. aper No. 32, Housing and Home Finance Agency, 1954 (U. S. Government Printing Office, Washington, D- C.) ' Surface isdvit, Values of VaricusISrfaces* EfTecJ^m.s.v^s of^Spaces 2 Effective Emissivity E of Air space Reflectivity in percent Average Emissivity e With one sur face having emissivity e and other 0.90 With both ' surfaces of emissivity * a, - f il 1111 ' * ** Aluminum coated paper, polished............. Building materials: wood, paper, glass, masonry, non-metallic paints................... 92 to 97 80 to 95 75 to 84 70 to 80 30 to 70 5 to 15 0.05 0.12 0.20 0.25 0.90 0.05 0*20 0.24 0.82 0.03 0.06 0.11 0.15 0.35 oi82 ' ' ,, ; a See ftlw Chapter 5, Table 3. Heat Transmission Coefficients of Building Materials 171 Table 2. Conductivities (k), Conductances (C) and Resistances (R) of Building and Insulating Materials (Design Values)* These constants are expressed in Btu per (hour) (squarefoot) (Fahrenheit degree temperature difference). Conductivities (A) are per inch thickness and, conductances ((7) are for thickness or construction stated, not per inch (AicAness ' Conductivity or Resistance Conductance (R) Material Description Density (Lb. per Cu Ft) (k) .2 -a 3l(C) ICL 8.9 AIR SPACESb See Table 1--Section B. Position Heat Flow Thickness Horizontal............... Up............................................ H~iin. Sloping (45).......... Up............................................ H~4in. Vertical...................... Horizontal...............................M-4in. Sloping (45).......... Down............. .................54-4 in. Horizontal.............. Down.......................................... Hin. Horizontal................Down........................................... 1V4in. Horizontal............ .. Down........................................... 4in. Horizontal...............Down........ ........................... 8 in. SURFACES Still Ais 15 mph Wind 7H mfh Wind See Table 1--Section A Position------- Heat Flow Horizontal......................................................................... Up Up Sloping (45)..........................................................Up Vertical.............................................................. Horizontal Sloping (45)............................................................ Down Horizontal............................................................. Down Any Position--Any Direction.................................... Any Position--Any Direction....................................... BUILDING BOARD* Boards, Sheathing, Etc. fiOTLEUNG paper ftOORING MATERIALS Asbestos-cement board.......................................... ..... Asbestos-cement board......................................H in. Gypsum or plaster board.................................H in Gypsum or plaster board........................................ Hin. Plywood............ ..................... ................................... Plywood.......................................................................... Hin. Plywood..........................................................................56in. Plywood.......................................................................... Hin Plywood or Wood Panels........................................ Hin. Wood fiber board, laminated or homogeneous..( Wood fiber--hardboard type................................;.. Wood fiber--hardboard type..................................>4in. Wood--fir or pine sheathing............................... *54*in- . Vapor--permeable felt.......................... Vapor--seal, 2 layers of mopped 15 lb felt Vapor--seal, plastic film....................................... | Asphalt tile................................................................... 54in. | Carpet and fibrous pad................................................. Carpet and rubber pad.......................................... Ceramic tile....................................................................1in. Cork tile......................................................................Cork tile........................................................................54in. Pelt, flooring.............................. '....................................... Floor tile or linoleum--av. value......................... 54in. Linoleum........................... 54 in. Plywood subfloor........................................................H*n. Rubber or plastic tile............................................... 54in. Terrazzo........................................................... I in. i Wood subfloor................`................................. *54* in. I Wood, hardwood finish........................................$4 in.| 50 50 34 34 34 34 31 65 65 - -Blanket Batt Board Cotton fiber*............................................................... Mineral wool, fibrous form, processed from rock, slag, or glass*.......................................................... Wood fiber........................................................................ Wood fiber, multilayer, stitched expanding*........ 0.8-2.0 1.5-4.0 3.2-3.6 1.5-2.0 Glass fiber.......................................................................... .Wood or cane fiber . Acoustical tile]........................................................54in. Interior finish (plank, tile, lath).................... .. Interior finish (plank, tile, lath).............. 54 in. Sheathing (impreg. or coated).......................... 8heathing (impreg. or coated)....................54 in. Sheathing (impreg. or coated)...............*54* in- 15.0 2105..00 20.0 20.0 G) G) 11..1118 1.03 0.97 0.98 0.87 0.81 0.80 0.85 0.90 0.97 11..0032 1.15 1.23 1.25 1.63 1.60 1.46 1.32 61..0008 4.00 0.61 00..6628 0.76 0.92 0.17 0.25 4.0 0.25 3.10 2.25 0.03 0.32 0.45 0.42 0.50 1.40 23..1220 1.60 1.07 1.02 22..3080 0.72 0.31 0.47 0.63 0.94 0.18 0.98 16.70 8.35 00..1026 Negl 24.80 0.48 0.81 12.50 3.60 211026...007000 1.28 42.40 112..0520 I 1.47 2.22 0.04 2.08 1.23 0.08 0.28 0.06 0.05 0.08 00..0728 0.08 00..9688 0.26 0.27 0.25 0.27 3.70 4.00 3.70 0.35 0.38 0.84 0.56 0.70 0.76 0.49 2.86 2.63 1.19 1.78 1.43 1-32 2.06 172 CHAPTER 9 1956 Guide Table 2. Conductivities (k), Conductances (C) and Resistances (ft) op Building and Insulating Materials (Continued) , (Design Values) Description INSULATING MATERIALS Board and SLAB8 . Cellular glass.......................................................................... Corkbo&rd (without added binder)............................ Hog hair (with asphalt binder).................................... PWlaoosdticsh(froeadtdneedd()c..e...m....e..n...t.e...d....i.n.....p...r..e..f..o...r.m....e...d....s..l..a..b...s...).. Loose Fill Macerated paper or pulp products.. Redwood bark shredded................... Mineral wool (glass, slag, or rock). Sawdust or shavings...... ..................... Vermiculite (expanded)...................... ROOF INSULATION MASONRY materials Concretes All types8 , ,, Preformed, for use above deck. Approx... Approx.. Approx Approx Approx Approx Cement mortar.................................................................. Gypsum-fiber concrete 87V4% gypsum, !2Yi% lighwtwoeodigchhtipsaggregates including expanded shale, clay or slate; expanded slags; cinders; pumice; perlite; vermiculite; also cellular concretes MASONRY UNITS Sand and gravel or stone aggregate (oven tlried) Sand and gravel or stone aggregate (not dried) Stucco `' Brick, common...................................................................... Brick, face............................................................................... Cl1aycetillled,eheopl.l.o...w...:................................................................ 3in. 1 cell deep..................................................................... 4in. 2 cells ,deep.................................................................... 6in. 2 cells deep......................................................................8in. 2 cells deep....................................................................10in. 3 cells deep.................................................................... 12in. Concrete blocks, three oval core: Sand <fc gravel aggregate................................ 4 in. .............................. 8 in. .................................12 in. Cinder aggregate................................................. 3 in. .................................... 4 in. Gypsum partition tile; 3 x 12 x 30 in. solid... 3 x 12 x 30 in. 4-cell. 4 x 12 x 30 in. 3-cell............. Lightweight aggregate (expanded shale, clay, slate or slag; pumice). .12 in. -- Stone, lime or sand METALS plastering materials Cement plaster, sand aggregate Sand aggregate............................ Sand aggregate............................................................ >4u. Gypsum plaster; Lightweight aggregate.'............................................Hin. Lightweight aggregate............................................ %in. Lightweight agg. on metal lath.. ..H-i4n4-in. . -- IT 173 (ft)Table 2. Conductivities (k), Conductances (C) and Resistances of Building and Insulating Materials (Concluded) . (Design Values)* ICoNDUCTIVITyJ (R) OB Resistance .Conductance! Material Description Density (Lb, per Cu Ft) (*) (C) SjH e kC4b mB J PLASTERING MATERIALS Perlite aggregate--'.................................................. Sand aggregate- -....................;............................. ..- - Sand aggregate.................................................... H . Sand aggregate -- . -.....................................H in, Sand aggregate on metal lath..................... H in Sand aggregate on wood lath.......................... Vermiculate aggregate.............. .............................. ROOFING Asbestos-cement shingles. Asphalt roll roofing............. ' ' Asphalt shingles.................. Built-up roofing.......... ' Slate..................................',, ' Sheet metal................. .. Wood-shingles...............'' ' [ ` ` " ...9$ _ .. . H in. SIDING materials (On Flat Sub face) Shingles Wood, 16-in. 79$-in. exposure.................... Wood, double, 16-in., 12-in. exposure.. Wood, plus insul. backer board............. Ms in. Siding - Asbestos-cement, H in., lapped .. Asphalt Roll Siding.. Asphalt Insulating Siding (% in. bd.). Wood, Drop, 1 x 8 in...................................... Wood, Bevel, x 8 in., lapped--'......... Wood, Bevel, M x 10 in-, lapped............... Wood, Plywood, 9 in., lapped.................. Structural glass.......................... WOODS Maple, oak, and similar hardwoods. Fir, pine, and similar softwoods........ G) (a) 45 105 105 105 1.5 5.0 11.10 9.10 00..1678 00.,1019 7.70 0.13 2.50 0.40 0.59 120 4.76 0.21 70 70 6.50 2.27 0.15 0.44 20.0070 3.00 0.33 m+ 0.05 Negl 1.06 0.94 1.15 0.84 0.71 01..8107 1.40 1.20 0.80 4.76 6.50 0.69 1.27 1.23 0.95 110..0509 0.92 1.25 0.21 0.15 2.45 0.79 0.81 1.05 0.59 0.10 . " Representative values for dry materials at 75 F mean temperature, selected by the A.S.H.A.E. Tech nical Advisory Committee on Insulation. They are intended as design (not specification) values for ma terials of building construction in normal use. For conductivity of a particular product, the user may obtain the value supplied by the manufacturer or secure the results of unbiased tests. - b Air space resistance values shown here are based on a temperature differenceof 20 F deg and a mean tem perature of 50 F for spaces faced both sides with ordinary rion-re/leetire materials (e ~ 0.90 and B =* 0.82). j Surface resistance values shown here are for ordinary non-reflective materials (e = 0.90). See also Insulating Materials, Board. . *: .` * Includes paper backing and facing if any) In cases where the insulation forms a boundary (highly fiective or otherwise) of an air space, refer to Table 1, Sections B and C, to obtain the insulating value of ra air space for the appropriate effective emiasivity and temperature conditions of the space. 1 Insulating values of acoustical tile vary depending on density of the board and on the type, _ size atnhde depth of the perforations- An average conductivity i value is 0.42. _ 8 The U. S. Deportment of Commerce, Simplified Practice Recommendation for Thermal Conductance Factors for Preformed Above-Deck Roof Insulation, No. R 257-55, recognizes the specification of roof insula tion on the basis of the C values shown. Roof insulation is made in thicknesses to meet these values. There fore,thickness supplied by different manufacturers may vary depending on the conductivity k value of the particular material. . Not oven dried--conductivity k prior to drying, approximately 1 to 3 years. condition to the maximum density obtainable by heavy ramming. The general findings of the investigation are-as follows: Effect of Temperature. Soils were tested at several mean temperatures.. The degree of influence of temperature depends upon whether it is above or below freezuig. For increases of moisture content exceeding about 6 to 12 percent, the conduc tivity of-frozen soil becomes progressively greater than that of the unfrozen soil. Effect of Density. Density affects the thermal conductivity of a soil in about the same manner for all soils, at any moisture content, and for either the frozen or un frozen condition. On the average, each one pound per cubic foot increase in dry density increases the thermal conductivity by about 3 percent. Effect of Moisture. An increase in moisture content, up to the point of saturation. IIhi? i' llI aw CHAPTER 9 1956 Guide 1ca7u4ses an increase in thermal conductivity. The rate of increase in typical soils was as follows: average conductivities, m Btu per (square foot) (hour) (Fahren heit degree per. inch), of four sands at a density of 110 lb percu ft were: 6.8 at 2.5 percent moisture, 8.9 at 5 percent moisture, 11:2 at 10 percent moisture. Five soils of a fine texture at a density of 100 lb per cu ft, gave average conductivities of 6.7 at 10 percent moisture, and 9.5 at 20 percent. Thus, the doubling of moisture con tent within the ranges cited increases the conductivity by approximately 30 or 40 tppeeenrrEcct efewfnenitctt..ht ionAAf ttShhhoeiiigglrhhaCeenhrrgaemmrsaooceiitsseuttruurisorreetic--ccs-oo-.-nn--ttT-ee--hnn-ettss the percentage increase tthheermpearlcecnotnagdeuctivity of would be _t_h_e__soil, less. at a given density and moisture content, varies in general with the texture of a soil, being rela- tively high for coarse-text-u--r-e-d1 sO,,o;iilos and relatively low for fine-textured soils. T1 he mineral composition of the soils also affect8 the cond' uc''tivriLt-y-. Quartz tends too give high values, whereas minerals such as plagioctase-feldspar and pyroxene, which are constituents of basic rocks tend to give low values of.thermal conductivity. These points are illustrated by the values in Table 3 which lists seventeen soils in approxi mate order of their magnitnde of thermal conductivity from greatest to least for Table 3. Thermal Conductivity (Is) Values or Soils in Approximate Order ov Decreasing Values* Mean Tempe. rat--ure--40 F -- Monro re Content % - Son. Debionation Sand | 0.5 10 10 19.4 70.3 770 57.9 13-0 o.o oo 50..51 2.5 0.0 o.o 0.6 46-.28 21.2 10.0 10.0 sctthuliovocssiheteytthwoaaipttthesarohmgitgieivthseatnqsruewcaaoesrrntoezdnaipctVibooOlnenQt.eelnux.tStwsra_a, _npbdoeylaadltoiotahnmeotsfaotbhilueslaaatarioeianm. oidr whaa..vy..e_i_nt_hethgeretaabtelest acnodqofuil.t,er;_ I. grained soils such as clay and silt loam are last. I Estimating Thermal Conductivity. The four diagrams of Fig. 3 are presented-tp^| afoidr isnantdhse oerstsimanadtey osof itlsh,eatnhdertmwaol fcoornsdiultcatinvditycloafyasnoyilss.oil.OnTewoof othfethdeiacghraarmtss'JOfjjc each type of soils is lor the frozen, and the other for the unfrozen condition. R.!J& ecxepnet.cteTdhtehaetffethcet soef cshuacrhtsfawcitlol rgsivaes cdoennsdiutyc,timviotyisvtuarlueecsowntiethnta, fprereecziisniogn, oorf t2e5xPtui^ff may be easily approximated by use of these graphs. flte Specific Heat of Soils ifep Tests to determine specific heat were run on twelve soils. On five..Pfe the soils, tests were made at three or four mean temperatures varyjh&j|i Heat Transmission Coefficients of Building Materials 175 from about 10 to 140 F. The specific heat values of all twelve soils varied by only a small amount (about 0.01), and averaged 0.19 at 140 F. The specific heat values of the soils decreased with a decrease in temperature. The average value at- zero F would be about 0.16. Values at temperatures between zero and 140 F can be estimated by considering a straight-line relationship between the two values given. Surface Conductance . The surface conductance of a wall is the combined heat transfer to or from the wall by radiation, convection and conduction. Bach of the three portions making up the total may vary, independently of the others, thus MOISTURE CONTENT - PERCENT MOISTURE CONTENT-PERCENT Fig. 3. Determining Thermal Conductivity of Soils from Density and Moisture Content - affecting the total conductance. The heat transfer by radiation between two surfaces, is controlled by the character of the surfaces (emissivity), the temperature difference between them, and the solid angle through which they see each other. The heat transfer by convection and conduction is controlled by the roughness of the surface, by air movement, and tempera ture difference between the air and the surface. The importance of the effect of temperature of surrounding surfaces on the surface conductance, due to the effect on radiation, is illustrated in Table 4, which applies to a vertical surface at 80 F, with ambient air at 10 F and with radiation exchange corresponding to an effective emissivity of 0.83." In many cases, because the heat resistance of the internal parts of the wall is high compared with the surface resistance, the surface factors are of minor importance. In other cases, e.g., single glass windows, the surface resistances constitute almost the entire resistance and are therefore very important. An analysis of various factors affecting surface conductance 176 CHAPTER 9 1956 Guide and the difference between surface and air temperatures will be found in Reference 5. (See also Chapter 24.) The convection part of the surface conductance is affected markedly by air movement. This is illustrated by Fig. 4, which shows the results of tests6 made on 12 in. square samples of different materials at a mean temperature of 20 F, and for wind velocities up to 40 mph. These con ductances include the radiation portion of the coefficient which, for the conditions of the tests, was about 0.7 Btu per (hr) (sq ft) (F deg). More recent tests7 on smooth surfaces show that surface length also affects sig nificantly the convection part of conductance; the average value de creases as the surface length increases. Moreover, observations8 of the magnitude of low temperature radiant energy received from outdoor sur roundings show that .only under certain conditions may the out-of-doors be treated as a black body radiating at air temperature. Because of these factors, the selection of surface conductance coefficients for a practical building becomes a matter of judgment.. In calculating the overall heat transmission coefficients for the waUs, etc., of Tables 7, 8, 9, 15, 16, 17, 18, 19, and 21, 1.65 has been selected as an average inside surface conductance, and 6.0 as an average outside surface conductance for a 15 mph Table 4. Variation in Surface Conductance Coefficient for Vertical Surfaces with Different Temperatures of Subbounding Surface Surrounding Surface Temperatube 75 F 70 F 69 F 60F 50F Convection--Btu per (hr) (sq ft).. Radiation-- Btu per (hr) (sq ft)... Total--Btu per (hr) (sq ft).............. 6.6 .4.4 11.0 6.6 8.6 15.2 6.6 9.6 16.2 6.6 17.0 23.6 6.6 24.9 31.5 wind. Both values combine the effects of convection and radiation, and are applicable to ordinary building materials. They should not be used for low emissivity surfaces such as bright metal. Values of U for windows in Table 20 have been computed from somewhat different data, as described in a later section, in order to give proper weight to actual surface con ductance. In special cases, where surface conductances become important factors in the overall rates of heat transfer, more selective coefficients may be required. Principles and data given in Chapter 5, Heat Transfer, may be applied in such cases. _ Air Space Conductance The transfer of heat across an air space involves the boundary surfaces as well as the intervening air, and depends markedly on the orientation of the air space and the direction of heat flow. The coefficients given for air space conductance represent the total conductance from one surface bounding the air space to the other. The total conductance is the sum of a component due to radiation and a component due to convection and conduction combined. These compohents may vary independently of each other. The radiation portion of the coefficient is affected by the temperature, of the two boundary surfaces, and by their respective surface emissivities e, the combined effect of which is expressed by means of the effective emit' sivily E of the air space. The radiation component is not affected by tbe thickness of the space or by its orientation or direction of heat flow. The AI heat transfer by convection and conduction combined, however, is markedly affected by the orientation of the air space and the direction of heat flow, is significantly affected by the temperature difference across the space and in some cases by the thickness of the space,- and is affected to only a small extent by the mean temperature of its surfaces. For air spaces usually employed in building construction, the radiation and convection-conduc tion components may vary independently of each other. Table 1, Section B, gives the thermal conductances and resistances of air spaces of uniform thickness and moderately smooth surfaces, based on thicknesAsitinnouthgeh rtahnegecoonvdeurcta%n_c_ien_s._,_o_af _vaeirrasgpeuaucvceaslltuuveaisurmyartaeoi ttsasobumrueelaaetuexdotefnfoStrtwatnihtdherange from hi in. to 4 in., for all except horizontal spaces with heat flow downward. The error involved by averaging is less than 10 percent in me extreme case and less than 5 percent in most. For more exact values Reference 9 may be consulted. For narrow air spaces, which may be defined as those for which the Product of the cube of the thickness of the space in inches times the tem perature difference (Fahrenheit degrees) across the space is less than 3 or heat flow horizontally or downward, or less than 1 for heat flow up- a*d> the conductance is the sum of the radiative heat transfer coefficient *"at for conduction alone through air, since convection is practically ^oppressed. The radiation component can be computed by means of Equation 4 and Table 4 of Chapter 5; the conduction component can be 1956 Guide CHAPTER 9 178 5. (A), (C),Table Conductivities Conductances and Resistances (R) used in Calculating Heat Transmission Coefficients (U) in Tables 7 to ,19" These constants are ex-pressed in Btu per (hour) (square foot) (Fahrenheit degree temperature difference), .Cofufactarilies (fc) are per tnc& tfttcfcneM and conductances (C) are for thickness or construction staled, not per inch thickness . i CONDCCtlVlTI! OB 1 . ` Resistance Conductakce Material Description For {Per Inch Thick Thick ness G)(k) (C) ness Listed <e) g Ik AIBRtoeSurnPiadAleCsd.E...bS...y.....O....r....d...i.n....a...r....y.....M.....a...-... i Vertical**, | in, or more in width... r AluminumFoil. | Vertical, | in. or more in width... Bounded bt b EXTERIOR FINISHES (Frame Walls) Brick Veneer.............................. Stucco (1 in.)................................ Wood Shingles........................... Yellow Pine Lap Sidxno. . 4 in. thick (nominal).. 1.10 0.46 0.91 2.17 1.28 1.28 0.08 0.44 0.78 0.78 insulating materials Aluminum Foil............................. Bats and Blankets -............... COBKBOARD................. Insulating Boabd. . Mineral Wool........... V ERMICULITE............. SMeaedAe ifrroSmpacmeisn.e...r.a...l..o...r...v..e...g..e...t.a..b...l.e...f..i.b..e...r. or animal hair, enclosed or open... Pur, no added binder...................... Vegetable fiber............ . ____ Fiber made from rock, slag or Expanded............... .................................... INTERIOR FINISHES Composition Wallboard.... Gypsum Plaster........................ Gypsum Board (| in.)........... - Gypsum Lath (g in.) and Plaster......................................... Insulating Board (I in.) .... Insulating Boabd Latb (i in.) and Plaster............. Insulating Board Lath (i in.) and Plaster............. Metal Lath and Plaster . Pctwood (i in.)......................... Wood Lath and Plabtbb. -. fy in. to l in. thick .. Plain or decorated. .. Plaster thickness assumed 1 in........ Plain or decorated................................ Plaster thickness assumed I in... Plaster thickness assumed ! in... Plaster thickness assumed i in... Plain or decorated............................ 0.27 0.30 0.33 0.27 0.48 3.70 3.33 3.03 3.70 3.08 2.00 0.30 3.70 30..466 o:eo 0.31 42..4102 2.60 MASONRY MATERIALS Brick................................................ Brick................................................ Brick................................................ Cement Mortar.......................... 3 in. Clat Tile (Hollow). Adobe, assumed 4 in..thick .... Common, assumed 4 in. thick. Face, assumed 4 in. thicE ..... 12.00 0.89 1.25 2.30 {17.0*80 4 in. Clay Tile (Hollow). 6 in. Clay Tile (Hollow). 0.64 0.60 8 in. Clay Tilb (Hollow) 0.58 10 in. Clay Tile (Hollow) .. 12 in. Clay Tile (Hollow) 0.40 0.31 16 in. Clay Tile (Hollow).aggregate...... Concrete.............................................. Concrete............... -- ............1 3 in. Concrete Blocks . 4 in. Concrete Blocks . 8 in. Concrete Blocks . !12 in. Concrete Blocks . 8 in. Concrete Blocks 12 in. Concrete Blocks 8 in. Concrete Blocks . 12 in. Concrete Blocks Gypsum Fiber Concrete 3 in. Gypsum Tile 4 in. Gypsum TilR . Stucco......... ..................... Tile and Terbaxzo.. ^ gravel aggregate.. Hollow, cind er aggrega'Ate* Hollow, cinder aggregate Hollow, gravel aggregate............... Hollow gravel aggregate......................... Hollow, cinder aggregate.......................... Hollow, cinder aggregate........................ Hollow, light weight aggregate ......... Hollow, light weight aggregate -.......... 87i percent gypsum and 124 percent wood chips............................................... Hollow.................................................. . Hollow........................................................... For flooring 122..5000 1.66 1122..5000 12.50 11..2080 l.0 0.80 0.60 0.53 0.50 0.47 0.61 0.46 Stone.............................. . 0.08 0.40 0.03 0.08 0.08 0.08 0.42 1.52 1.67 3.18 ,0.23 0.47 0.40 A- 1.12 0.80 0.43 01..7080 1.57 1.67 1.72 2.50 3.23 011...700800 11..2656 12..8080 2.13 21..1684 Heat Transmission Coefficients of Building Materials 179 Tablb 5. Conductivities (4), Conductances (C), and Resistances (R) Used in Calculating Heat Transmission. Coefficients (U) in Tables 7 to 19 (Concluded) These constants are expressed in Btu per (hour) (square foot) (Fahrenheit degree temperature difference). Conductivities (k) are per inch thickness and conductances (d are for thickness or ' construction stated, not per inch thickness Conductivity or Conductance Resistance Material Description Per Inch For Thick Thick ( (C) ness ness Listed (0 G) ROOFING MATERIALS Asbestos Shingles............... .... Asphalt Shingles. ................... -- --_ Wood Shingles........... i................ 8HEATHING y. Insulating Board (34 in.) .. Plywood (A in.)........... r Fib oh Y ellow Pine (1 in.) . Fir, Plus Building Paper. . Actual thickness 31 in................... ................. Actual thickness 31 id........................... ............ SURFACES Still air. ..:..................................... 15 mph Wind Velocity............. Ordinary non-reflective materials. vertical...................................................................... Ordinary non-reflective materials. vertical. ................................................................ WOODS Fir Sheathing (1 in.) Building Paper and Yellow __ __ __ __ -- -- -- _ Yellow Pine or Fib................ 0.80 6.00 6.50 1.28 0.42 2.56 1.02 0.86 1.65 6.00 -- __ _ __ __ __ __ -- __ -- _ 0 87 1.25 0.17 0.15 0.78 2.37 0.39 0.98 1.16 0.61 0.17 2.00 -- * The values in thin table do not agree exactly with those given in Table 2 which was revised in this issue- out the differences are not significant for design use. Tables 5 and 7 through 19 are in the process of revi rion, so that they will correspond to Table 2. . b For practical accuracy these values can be usedaa an average for vertical and horizontal surfaces. Where accuracy is desired refer to Table 2. These values for Tables 5 and 7 through 19 are in the process of revision-. computed using the conductivity of air at the appropriate mean tempera ture (see Table 1, Chapter 5). The effects of different mean temperatures, temperature differences, and effective emissivities are indicated in Table 1, Section B. As indicated, use may be made of interpolation and moderate extrapolation of con ductance values in the table to obtain conductances for conditions moder ately different from those given. Interpolation of resistance values is not recommended, especially in relation to emissivity values. Table 1, Section C gives values for the surface reflectivities and emis sivities of materials used as boundaries of air spaces in building construc tion, for total radiation at ordinary building temperatures. Effective emissivities for various combinations of these materials, for use in con junction with Section B of Table 1, are given in the last two columns of Section C. When considering heat transfer across air spaces in building construction, the emissivities of the boundary surfaces should be known. The possibility of change in emissivity of highly reflective surfaces due to exposure to con ditions promoting chemical action, deposition of dust, soiling of the surface 180 CHAPTER 9 1956'Guide or the application of coatings, even though transparent to the eye, must be considered ip selecting a material for use.10 Surface emissiyity values should be obtained by tests. ' PRACTICAL COEFFICIENTS AND THEIR USE For practical purposes it is necessary to compute average coefficients that may, be applied to various materials and types of construction. Table 2, as revised in this issue, gives representative values for dry materials at 70 F mean temperature, as selected by the ASHAE Technical Advisory Committee on Insulation. Since there may be some variation in the materials and in test conditions, these selected values may not be in exact agreement with published data of all manufacturers. The exact value for the conductivity or conductance of a certain manufacturer's material can only be secured from unbiased tests or guaranteed by the manufacturer. ' Caution The conductivity or conductance values given in Tables 1 and 2 are taken from values obtained in most cases by the guarded hot plate method ASTM Standard C-177-45 which states, .. "Because of the requirements prescribed in this method as to conditions under which conductivity tests shall be made, it should be recognized that the conductivity coefficients obtained will not necessarily be the values pertaining under all service conditions. As an example, the method provides that the conductivity coefficient shall be obtained by test on dry specimens, while in service such a condition will seldom be realized." The user should realize that the average conductivity and conductance values given in Tables 2 or 5 do not necessarily apply'to all products of the ' same general description. In using these values, judgment should be exer- ' cised with regard to the extent to which the product (either as received or > as applied) will comply with the tabulated values. Exact conductivities , or conductances for specific materials should be obtained from the manu facturer. Table 5 has been retained in this edition because it is the basis ' for computation of the 17-values shown in Tables 7 to 18. ' Because U values for heat flow upward, such as for ceilings in winter, may differ greatly from U values for heat flow downward, such as for ceil ings in summer, a serious error may be made in calculating heat losses or, gains if the appropriate U value is not used. (See Chapter 13 for recom mended temperature gradients for cooling loads.) , Due to the inconsistency of actual building construction, because of the human element, many designers do not use overall coefficients of transmis; _ sion lower than 0.10 for walls and particularly roofs, except where the . construction is installed under continuous supervision. It should also be noted that these coefficients do not include any factor of safety and that : when no supervision is used, some designers incorporate a 10 percent factor of safety. ' Attention is called to the necessity of applying the insulating material in accordance with the manufacturer's specification. The engineer must' ; evaluate carefully the economic considerations involved in the selection of an insulating material as adapted to various building constructions. Lack ' of proper evaluation, or improper installation may lead to unsatisfactory 7 results; Special attention must be given to vapor barriers as outlined in Chapter 10. Moisture from condensation or other sources materially re duces the heat-flow resistance of insulation. 1 Jf- Heat Transmission Coefficients of Building Materials 181 Insulating Materials In order to determine the benefit derived from the addition of insulating materials to a given construction, the overall coefficient of heat transmission' Ui of the insulated construction may be compared with the corresponding' coefficient U without insulation. Table 6 (Part A to Part D) may be used for determining the coefficients of transmission of constructions with any combination of fibrous, bulk, or mass insulation and air spaces of various effective emissivities. INSULATED CONSTRUCTIONS--HOW TO USE TABLE 6 In Tables 7 to 17, U values are given for many common types of building wall, floor, and ceiling constructions. For such of these constructions as contain an air space, the tabulated U value is based on the assumption that the air space is empty, and that its surfaces are of ordinary building ma terials of low thermal reflectivity, such as wood, masonry, plaster or paper. Considerable benefit in reducing the heat transmission coefficient of a con struction can be effected by the application of thermal insulating materials in the air space. Table 6 provides a means of determining, without calculations, the U value of the between-framing area of such constructions with the added insulation installed in the air space. Column 1 of Table 6 refers to the V values of uninsulated constructions as taken from Tables 7 to 17. Col umns 2 to 14 of the table give corresponding coefficients Ui for the con structions with various insulating applications in the between-framing air space, as indicated by the column headings. Table 6 is in four parts, corresponding to the type of building element and the direction of heat flow. Each part is based on temperature conditions considered generally appropriate for the case. . Any and all U values are based on a series of assumptions as to nominal characteristics. Common variations in conditions, materials, workman ship, etc. can introduce much greater variations in U values than the varia tions resulting from the assumed mean temperatures and temperature dif ferences described. From this it is also clear that the use of more than two sign ificant figures in stating a U value is assuming more precision than can possibly exist. Three significant figures are used in Table 6 merely as a means of reducing cumulative errors when the table is used several times to obtain a single result. It should not be assumed that the figures are accurate, over-all, to three significant figures. Also a result taken from Table 6 should always be rounded off to two significant figures. To use Table 6: 1. Find in Column 1 of the appropriate table the value for U obtained from rabies 7 to 17. 2. If there is a column which exactly corresponds to the condition for which you desire the U value, read the answer in this column, opposite the Column 1 value, interpolate if necessary. 3. If there is no column which fully corresponds to the condition for which you desire the U value, then obtain the answer by means of two or more steps--each time using the value obtained in one step to reenter the same table through Column f In this way U values may be obtained for combinations of insulation in the fram lQg space. Special Uses of Table 6 Jalues fr insulating applications or combinations other than those mdicated by the headings of Columns 2 to 14 of Table 6 can be ascertained 182 CHAPTER 9 1956 Guide 00 10a >0 0 0 0g O ~tt> >eh*i Or-H oOOooo) <N r- C3 CO CO 00 oooo 0ro-5. oCr-O-oCrO-o0co5 ICQOHOClQOUH) OOOO 0 0 oooo oooo oooo OOOO co 0 0 1 000 0o TdS M to 0Jo-C^O0003 rOlSD-H3 COO ^O Or-< C0OO5 O0--51 CCOOO OOu('oOCoOoOCi-Ot S0000 0O oooo oooo OOOO o CQ 3 gw 00h*5 00 0 0H8 S 1- S3 SSiS lONOHDOOOHt>O*HCPD OQOC5 CO 03 CO CD (N 3288 co 0< aO - . oooo oooo 000.0 OOOO p z u>- aao<*i o zo s a 3 to P 3 a > i WE&3 . *?_ e s 3ug a < O H a> i MO3 O . ON O S O.. S O O o oo < Z r_, 2g SoQ <ft sotat oz p p 0H3 Ph a ap*: > SO HH vS Scv g9 4. 0 a0 0 T m g Ha zo p < p OM O 1 CO <0 O eo >0 C35t>-cOO 0H0 Ht-a HH^ oooo 0 0 o CO C3 03 OOOO iT--Q O1--1^OOOC5 a-H r--t r--* O OOOO O05 CCOO D cO> OOOO OOOO s' 0 0^WtCOifO^O C3 C oooo 03 I-M 0iO0 TfiOH-^ OOOO 1C^O. 0C53 O03 03 hh OOOO 0 0 0Co1--O1 ^o^ot^ oooo CCD3 O O h.(NCOH CCCJ5HC3 -^ CO CO C3 oooo (NNON C3CCO3CN3CO3 OOOO ^05O00OCON10 H rH tH r-H OOOO NlNNH C^HO CH3 OrH 0O5 OOOO O O 0aCoO^^C0O 0C0030iCo* oooo 1--1 00T*< CO U3 C(NO O03 05 *--< OOOO rt rH NCO oooo ^ rH 00 2388 0CO0D OOOO O CcTOtOCT3iii rrCHtOO0053i oooo r-H CO C0O3 C0O3 CC33 O03 OOOO ^0rH5Q0-0HCr5HOQ*rH0 oooo 0cCO0OC3>O00 HH.H OOOO CtHO O O 0C3 O O t> CD ^ oooo CO CO C3 03 OOOO C3 O 00 OOOO CO C3 oooo 00 0 0 00 o 0ta3C0O5 D00CCDO oooo OOOO oooo oooo 0000CuDJC^D Nc&OCO oooo iO ^ iD 5 oooo oooo C3 O O oooo No>6HoOjsj oooo oooo oooo oooo hp o> ^ co NoCofitoOioQ oooo 03 p3 00 CS USnpCOCS oooo OCO C3 C3 i-> o oooo OC3C5CS O7-1 o0o0ob oooo 03 co HP ap CDO OcsCc3Q<n^cW>3 oooo 0Cp33h0roH3 j^rwH N,-SH OOOO (cODciOC'Oa'Trtf oooo --*0oo>0*50 Hoo oooo ot-- o IS JS *x , *8 3-. ^ s : ** *-s .3 ^ aZ taflO p< p Sgl ''Is p> B .5 1C o 00 CO cs co C3 03 oooo oooo oooo a ^4 P . lio 12-i.af o *o - 8 8 > a*;j S * J3 O V1 t*sJQg. CaQ 5$>:3 JHi! o2ao f!ot. 552 '"fl Heat transmission Coefficients of Building Materials 183 0.05 0.20 0.82 0.20 0.05 a 00 00B 002 00 00a 2 03 rH rH O Tf Tj< rf< OOOO O O 05 05 ! co co tH co CS CO CO CO oooo CD US -p c*s cs cs eo cs oooo rH 00 CSC3 g; OOOO OOOO OOOO oooo do Oh p ig m if Eh Kza p (E a a a z h 00co ^ 03 rH oooo co oooo oooo 03 t- If CO N tn (h |h OOOO OOOO 03 O 00 CO tH tH CD c OOOO OOOO hPi-hcOh** CO CD us US oooo OOOO 00 do 0003 cd r* CO03 1-H 03 C3 C3 C3 oooo - 00us 03 V3 O O tn CD 03 lH H H OOOO rH CO US c CO us H* CO oooo CO CO US HP C3 rH O 05 rH rH rH O OOOO 0000 < do fiO O 00a 5* I - SDUJiO O U5 u5 ID oooo Tt*03r-HO us us us us OOOO 05 00 tH O ^ ^ HP ': US Hp 03 O HP HP Hp HP 0.0 0 0 OOOO tH CS CSCS < oooo OOOO oooo oooo do 0. 00 . sE < S3 000 0 05 05 00 00000O 03 00 <* i-H C3rHfHrl tn co co OOCiCs -- HP rH OO h ' O CO rH CO ao OO tH tH CO oooo oooo us us oooo OOOO oooo oooo do CQ 3 ' 05 00 0< ` O & N00 O -S> NcOOO CO COCO C3 0CO0^^0r5H 0O0 03 03 03 03 NlflCOO ao tn <j CO 00 CO Hp CO rH 05 C3 00 tH 00oooo OOOO oooo oooo z- O >--. < s ft$ o|h sjts gSiSf S* i a to Spo WofcOEoT t{OJ, S5 hP CPQ a p a < z o p z< a > a > F> g> to ' OS5 f>a* Ss co i 0 5 a z N 00 a a B Z T w z a0 H 0 H r* P z 0p a n r>N ,ftct" f><a3 p rsJ aa 0000 0 0 0000 rH CD CO "HOO O CD rH 05 OOOOO --* O O O NtPaHOO ooabaot-H HP us NNOtO oooo Hp tn US Hp oooo OOOO -oooo oooo do 0 0 0 0 0 0 0tH co C<HO D3 03 03 03 05 CO 03 CD 00 tn CD US cs c ao us HP CO C3 05 05 05 QO 1--1 03 00 rHrHOO cocs tn CO 0d o' d * OOOO . OOOO oooo do 0 0 0030 00<c> p O D Is cD to ^ * O us eo co CO Hp C3 O 03 C3 03 03 CO HP 000 rH O oooo OOOO OOOO oooo do 6 .5 2 u .2S 2L-8X I5 scS ^i - au I 2& aa3 O 00 CD us OONNN pooo oooo cJ* 03 05 00 0 0 0 0tn lH CO CO OOOO CO S ^*03 co co CD co OOOO OOOO O |H. Hp rH CD US US us OOOO OOOO tH C3 0 0HP Hp 0CO CD rHrHOO OOOO -hnh O 03 05 05 <-HOOO Oooo 90500fH0. 0^00W0 OOOO OOOO 00 HP 05 HP St-toco oooo oooo 8008 00 Sii S . s3 -M $ O j3 C ; 0 0 gaS-3. US CD us 00 QO tr CQ rH 03 03 00 <D US HP dS CS tH rH 1 NN-h OOOC3CS O O 03 00 -- -4 CSC3 SS - _ - .O O--I. OOOO oooo OOOO oooo OO ; e tj O -1 0 0 SIN U)H<0 O 00 CO TJ< CO 03 03 03 O 03 03 CS r 05 QO 03 03 rH rH us co CD us tn O US Hp HPCS 1-h 00 cs C3 rH 05 rH rH i-H O oo ; '= -g's. 3OOOO oooo oooo oooo dd .t E-i - ?ET-s & 8* a Jg-3 ,i! OOOO OOOO 8SS8 OOOO 222:2 oooo' 2g 00 18 si' fof-p I o * a -c W g CQ H a T a b l e 6 . D e t e r m i n a t i o n o f U V a l u e R e s u l t i n g f r o m A d d i t i o n o f n s u l a t i o n o r A i r S p a c e s t o U n i n s u l a t e d B u i l d i n gI , S e c t io n s * ( C ontinued) . ; 0.20 0 .1 8 0 0 .1 7 1 0 .1 6 0 0 .1 5 4 0 .1 4 6 0 .1 3 8 0 .1 2 9 0 .1 2 5 0 .0 9 7 0 .0 9 0 0 .0 8 3 0 .0 7 5 0 .0 6 7 0 .0 5 8 a & Wag ^ e* 2-8 gW Q H a H ta S tDCJHCD ^JW WN HlOOO^ Wi--t pHH OpH Or-f ^t-COOO O-<03 Q3 00 '<* 03 CC CO 00 NNcO oooo 0C4O CkDO OO O OO OOOO oooo OOOO oo OkOD'# CO 04 pH O O OOOO a C t-- t* co co oooio^ CCC4C4 04 f-C3 03 pH N0*N00H0H00 04 cc CC CO tp-HCpOH kpOH tp*H <N pH 03 CO CpCH 0pH4 OPH 0O3 04 foO cO oo oooo .OOOO OOOO OOOO OO a i3 a - oft fca n Hwh Q s> sa ft a 0 u< o * t* 1a t I ? *0 SB eg 3s 53 gq a a 3 1 a z co O O ft m a e Mz aCrO a 2 aa 5 h 2o a Da 2 IS &o s 0.82 0.20 *> aCO eo e* 0.20 CO^<0> C14-4C040p0H 0--0* oooo 00 kO OOOO 'tOOO-# CO C4 C<J rH pH pH pH H OOOO COD 0003 OC3 Oco PHOOO OOOO N CO OO oo 0.073 0.064 0 .0 7 6 1 0.105 0.088 0 .0 9 9 1 I 0.136 0.109 0 .1 1 9 1 o Cc4'5**^'$(<NC-4i C4 C4 C4 C4 CD kO 00 pH 03 00 CO CO pH pH pH pH CD r-~ 00 lo CO 04 pH pH pH pH OOOO OOOO OOOO 0 .0 9 0 0 .1 2 0 0 .1 5 0 0 .2 0 4 0 .1 9 1 0 .1 7 8 0 .1 6 4 MOOO OO O O t1*C4 OOCO rH oo co cc ph CO h*co> co 4 04C4C4 oooo oooo cc CO C4 00 k-D O CD -H CD o * C CO N^HO ^cc . 0*010*04 pH C3 CO 03 O* CO kO pH pH pH pH pH 00 kD pH CjMpjO OO H* CO fp oo boo OOOO OOOO oooo . OO 160 0 so ro 8110 ze ro 9H 0 i 6 S I0 WC-Hm NH<OW - <* "* CO CO oooo 0 .3 0 0 0 .2 6 9 0 .2 3 7 0 .2 2 4 pH 03 CO CO p0H4 0pH3 0P0H CpHOOOO < cno0o0o0o0 oCoO co io ^ 03 O O* 04 00 ->* 03 tCC CC 04 o* CC TH H* kO kO CC pH 03 04 04 04 pH co co tp oo tp-i pDH cpHc ppHH 03 03 8S OOOO OOOO oooo oooo do* *o o OO CD ID 00 t'-t"-* t-- oooo h* C4 03 00 C-- C-- CO CD OOOO CD iD 04 CO CO CO CO oooo ON'fH CO ID kD kD oooo tT-* CT4* OO oooo OOOO oooo oooo oo H MOD'# ppHH HH Ot--1 OH HNCCH O 03 03 03 pHOOO 03 ^ pH 00 CD 00 00 oooo 0t-0 ri--t<cC3c''o* OOOO 0iD0 25 OO OOOO oooo oooo OOOO oo* CO WcDiftCO 03 oo Cx CD iH PI pi pH C4 04 00 CpHO pHDp<H* CpCH CCCO ((N-- 0pH4 k-OH 0O0 OO C034 CoCo Ct-C Cc4 pH pH O O > OOOO oooo oooo OOOO do cc D -* C> c O OO CO ^ CO C4 04 <N O 04 (N ^ CC pH 03 00 C4 04 pH pH kD<C0O CkOO khO* "* cc ph oo CC pH 0pH4 ppHH 03 kD O 00 tp oo OOOO OOOO oooo OOOO do* Q a ft 2 a ftg *< d e* 1 >o 1 h24 OOOO kD oo r# CC CC 04 C0O4 <-h0*40044 OC4 00 co -<*04 OpH oo do3 oooo oooo oooo OOOO D W 1w a f I 1 186 CHAPTER 9 1956 Guide if the table is used appropriately. For instance, going horizontally in the table from Column 2 to Column 3 is equivalent to adding in. of fibrous insulation to the construction; similarly, going from Column 2 to Column 4 adds l\i in. of fibrous insulation to the construction. In the same way, going horizontally from Column 8 to Column 11 is equivalent to adding to a construction the insulating value of one additional highly reflective (E = 0.05) air space, and going from Column 6 to Column 12 in effect adds two non-reflective (E = 0.82) air spaces to the construction, etc. CORRECTION FOR FRAMING Correction for parallel heat flow through framing and insulated areas may be made by use of Fig. 5. Correction for the effect of framing should Heat Transmission Coefficients of Building Materials 187 at the University of Minnesota, a direct comparison can be made between calculated and tested values. . Example 2: Calculate the coefficient of heat transmission V for a wall shown in Fig. 6. Wall construction consists of two 4-in. concrete walls separated by a 24-in. space filled with insulation; 14-in. diameter metal tie rods are imbedded a distance of 1 in. in each 4-in. concrete wall, and spaced 9 in. vertically and 12 in. horizontally. Values of k are: insulation 0.30, concrete 12.00, tie rods 400.00. Solution: In Fig. 6 the following paths of heat flow from plane A to plane F will be noted: . 1. From A to B: One path through 3 in. of concrete. . 2. From B to C: Two paths, (a) through 1 in. of tie rod, and (b) through 1 in. of concrete. . Fio. 5. Correction for Effect of Framing in Insulated Building Sections JJst -- average U value for building section. (J\ = U value for area between framing members. 17* -- V value for area backed by framing members. S = Percentage of area backed by framing members. . ., be applied after final Ui and Ua values have been obtained for a given con struction. In many cases this correction may be omitted. Example 1: Consider a frame wall with 2-in. blanket insulation which has a Ui value of 0.08. By calculation it is found that heat loss from the area backed by fram ing members ([/,,) is 0.13. U,/Ui is 1.63. From Fig. 5 if 15 per cent of wall area is backed by framing, the value J/.v/I/i = 1.1. /.v is therefore 1.1 X 0.08 = 0.088. Computed Heat Transmission Coefficients Computed overall heat transmission coefficients of many common types of building construction are given in Tables 7 to 21. In the analysis of any wall construction for the purpose of calculating the overall coefficient of heat transmission U, it is first necessary to determine the paths of heat flow, that is, whether they are parallel or series, or a combination of both. This is in accordance with the basic laws of heat transfer which state that in parallelflow the conductances are additive, while in series flow the resistances are additive. Likewise, in order to determine the total resistance for the wall, the conductance must be known. . The importance of this analysis cannot be over-emphasized. This is especially true in wall constructions in which there are parallel paths of heat flow; and one path has a high heat transfer, while others have a low heat transfer. The method of making this calculation can best be shown by Example 2 and Fig. 6. As this wall was tested by the hot box method Fro. 6. Section of Concrete Wall Having Steel Tie Rods and Insulation 3. From C to D: Two paths, (a) through 2% in. of tie rod, and (b) through 2 in. of insulation. 4. From D to E: Two paths, (a) through 1 in. of tie rod, and (b) through 1 in. of concrete. 5. From E to F: One path through 3 in. of concrete. It will be noted that items 2 and 4 are paths of similar flow, and could be treated as one. If equilibrium or steady state heat transfer is assumed, there will exist a temperature difference between the metal tie rod and the concrete, and also between the metal tie rod and the insulating material. The rate of heat transfer between these materials is dependent upon their conductivity values and the temperature difference. As the conductivity of the metal tie rods is considerably higher than that of the concrete or insulating material, it cannot be assumed that the same rate of heat transfer takes place for all parallel paths. Likewise, an appreciable error would be made by assuming that no heat transfer takes place between'the metal tie rod and the surrounding materials. Although the pattern of the isotherms is unknown, the following method of calculation does partially take into account the heat flow be tween the metal tie rods and its bounding materials. Parallel Flow. The conductances through the areas of parallel heat flow may be determined as follows: . 1. The area of each 14-in. diameter tie rod is 0.00034 sq ft, and as the tie rods are BPaced 9 in. vertically, and 12 in. horizontally, there will be 0.00034 X 44 = 0.00045 89 ft of tie rod to each square foot of wall area. Then from plane B to plane C, the conductance Cj is C, 0.00045 400 0.99952 12 1.0 X 1.0+ 1.0 XL0 = 0.180 + 11.994 = 12.174 1956 Guide CHAPTER 9 188 2. For tie rod and insulation from plane C to plane D the conductance Ci is _ 0.00045 .. 400 , 0.99952 .v_ 0.30 _ 0 072 + 0.120 = 0.'192 C* = 1.0 X 2!o+ 1.0 2.5 3. For tie rod and concrete from plane D to plane E the conductance Cj is _ 0.00045 ^ 400 0.99952; .x. --12 = 0.180 + 11-994 = 12.174 C, = 1.0 x 1.0+ 1.0 1.0 Series Flow. After the conductance values have been determined, the total re sistance and U value can be determined as follows: _ 1 x, , 1 1 1 x, 1 Rt = -- -f- -- 4" -- 4-- 4--* 4-- 4~ -- A *. C, C, ,, 1 3.0 1 1 '1 3.0 ,1 Hj =! 1--.65 4- 1--2.0 4--1--2--.1--7-44"-0--.-1-9--24----1--2-.-1--7-44~ --12.04----6--.0- Rt = 0.606 4- 0.250 4- 0.0822 4- 5.208 4- 0.0822 4- 0.250 4- 0,167 = 6.727 J_= 1 . 0.149 Btu per (hr) (sq ft) (F deg). U ' Rj 6.727 ' The Hot Box test value, from University of Minnesota, for this wall, corrected for a 15 mph wind velocity, was U = 0.150 Btu per (hr) (sq ft) (F deg). The error between the calculated and test values would be 0.150 - 0.149 X 100 = 1 percent. 0450 If the effect of the tie rods were omitted from- the calculations, the over all U value would be 0.103. Although the percentage of area occupied by the tie rods per square foot of wall area is ^ X 100 = 0.045 percent, the error between the calculated and test values would be 0.150 - 0.103 X 100 = 31 percent. 0.150 ` Values Used in Calculation of U Value Tables . ' In making the calculations for values of U shown in Tables 7 to 19, the following conditions have been assumed: ' Equilibrium or steady-state heat transfer, eliminating effects of heat capacity^: Surrounding surfaces at ambient air temperatures. Exterior wind velocity of 15 mph for winter and 7.5 mph for summer. . '' SSuparfcaecse beemtwiseseinvitfyraomf ionrgdionrarfuyrbriunigldinnogt minastuelraiatelsd.= 0(S.8e3e. Table 6 for method of corAreirctsinpagcfeosraarded%ediinn.sourlamtioonre.)in width. " Variations of conductivity with mean temperature neglected. Corrections for framing to be made on basis of parallel heat flow through 2 X 4 ii>, (nominal) studs, 16 in. on centers, the framing covering 15 per cent of wall area, C4 indTichaetermd ainl reFsigis.ta5n. ce for gypsum board and insulating board apply equally to plain material and to those which may be decorated at the factory or on the job. (4 Heat Transmission Coefficients of Building Materials 189 Actual thicknesses of lumber assumed to be as follows: Nominal " Actual 1 in. (S-2-S)............... .. in. lj in. (S-2-S)............................... ,1A in. 2 in. (S-2-S)..................................if in. 2f in. CS-2-S)-----:......................... 2\ in. Nominal Actual 3 in. fS-2-S).................................. . ...2| in. 4 in. (S-2-S)....................................... 3$ in. Finish flooring, (maple or oak)... | in. Coefficients for frame construction are corrected for the effect of framing where such correction would increase the coefficients, but not where the correction would decrease the coefficients.11 It should be noted that the effects of poor workmanship in construction and installation have an increasingly greater percentage effect on heat transmission as the coefficient becomes numerically smaller. Failure to meet design estimates may be caused by lack of proper attention to exact compliance with specifications. A factor of safety may be employed as a precaution when it is judged desirable. ' Roof Coefficients - Computations for wood shingle roofs applied over wood stripping are based on 1 by 4 in. wood strips, spaced 2 in. apart. Values for roofs con taining Spanish and French clay roofing tile are assumed the same as for slate roofs. Values for pitched roofs in Table 17 apply where the roof is over a heated attic or top floor, so that the heat passes directly through the roof structure, including any interior finish material. Combined Ceiling and Roof Coefficients If the attic space between the ceiling and roof is unheated and not venti lated) the combined coefficient from room air below the ceiling to exterior air can be calculated from the following formula: . ,,1 l Rr = u:.+^ur (4) and U = 1/Rt (5) where U = combined coefficient to be used with- ceiling area. Rt = total resistance of ceiling and roof. (7c = coefficient of transmission of ceiling. U, = coefficient of transmission of roof. n = ratio of roof area to ceiling area. : -......... It should be noted that the overall coefficient U should be multiplied by the ceiling area to determine heat loss, and not by the. roof. area. Values of Ur and U,, should be calculated using a. value of 2,2 (the reciprocal of one-half the air space resistance) rather than 1.65 fob the: cbnductances of surfaces facing the attic, since the attic is equivalent to ah air space. If the attic contains windows, dormers and vertical wall spaces, and if their area is small compared to that of the roof, they may be considered part of the roof area. For accuracy, the sum of the coefficients of each individual section, multiplied by its percentage of the total area, should be used as UT. Where attic wall areas are large, it is preferable to estimate the attic temperature as illustrated in Chapter 12, and calculate the heat loss through the ceiling by multiplying the value of {/<* for the ceiling by the difference in temperature above and below the ceiling: ufV 190 CHAPTER 9 1956 Guide Table 7. Coefficients of Transmission (f/) of Frame Walls* These coefficients ore expressed in Btu per (hour) (square foot) (Fahrenheit degree difference in temperature between the air on the two sides), and are based on an outside wind velocity of IS mph. No Insulation Between Studs* (See Tabus 6) Heat transmission Coefficients of Building Materials 191 Table 8. Coefficients of Transmission (U) of.Masonry Walls* Coefficients are expreued in Btu per {hour) (square fool) (Fahrenheit degree difference in temperature between the air on the two sides), and are based on an outside wind velocity of 16 mph. INTERIOR FINISH (Plot Insolation Whkbs Indicated) If31 3 3i 3 i4fi as Is njj sag nII- Is3, *3 ^ Id ki H ollow Concratx 8 046 042 044 12 0.49 0.46 042 _o o Si042 0.24 043 040 0.22 042 0.15 1 62 0.14 63 Cinder Aggregate 8 12 0.41 048 049 046 048 046 048 046 047 045 0.21 040 040 0.19 0.15 0.15 0.13 ] 84 0.13 | 65 light Weight Aggregate* 12 | _0.34 ). 00,3334 |I 00..2256 I) 00..4245 1 00.4244 {| 00..1199 J] 00..1189 I| 00..1154~~I (See text p. 186.) * See Table 5 Note a. Based on 4 in. hard brick and remainder common brick. The 8 in. and 10 in. tile figures are based on two cells in the direction of heat flow. The 12 in. on three cells in the direction of heat flow. The 16 in. tile consists of one 10 in. and one 6 in. tile, tile is based two cells in the direction of heat flow. ' each having Limestone or sandstone. These figures may be used with sufficient accuracy for concrete walls with stucco exterior ^Expanded slag, burned clay or pumice. finish. Thickness of plaster assumed } in. * Thickness of plaster assumed i in. Based on 2 iD. furring strips; one air space. 192 CHAPTER 9 1956 Guide Table 9. Coefficients of Transmission (f/) of Brick and Stone Veneer Masonry Walls* ' Coefficients are expressed in Bln per (hour) (square foot) (Fahrenheit degree difference in temperature between the air on the two side*), and are based on an outside wind velocity of 15 mph. INTERIOR FINISH (Plus Insulation Where Indicated) TYPICAL CONSTRUCTION PACINO BACKING a s 3 IIsa 3. ."8 3 S sl 33 II 11 lot; 8tn.HoBowTU*. SlaHoDowTHeK. ,0.13 88 0.13 89 8 In. Concrete.- 024 0.23 0.17 0.15 023 023 0.17 0.15 8 In. Concrete Blocks (Gravel A| * 8 In. Concrete B 8 lik Concrete Bfo-- (light Weight Aggregate)*-. 0.41 0.29 033 025 022 025 0lnHottowT1le*,, 8 la Hollow 82i^v fV` 95 A 96 ;- 4 In. Cut Stone Veneer* 0ta Concrete-. 8 la Concrete-. 8 laConcrete Blocks? (Gravel Aggregate. 8 ta Concrete Bracks* (Cinder Aggregate).-. 8 la Concrete Blocks* (lightWeight Aggregate)*-. 0(0J55T 3 '-iV-f if* 1100^ (See text p. 186). * See Table 6, Note a. " Calculation based on ) in. cement mortar between backing and facing, except in the case of the concreta^;^ backing which is assumed to be poured id place. b The hollow tile figures are based on two air cells in the direction of heat flow. \, e Hollow concrete blocks. d Expanded slag, burned clay or pumice. * Thickness of plaster assumed } in. 1 Thickness of plaster assumed i in. 0 Based on 2 in. furring strips; one air space. % Heat Transmission Coefficients of Building Materials 193 Table 10. Coefficients of Transmission (V) of Frame Partitions or Interior Walls0* ` Coefficients are expressed in Btu per (hour) (square foot) (Fahrenheit degree difference in temperature between the air on the two sides), and are based on still air (no wind) conditions on both side*. INTERIOR .FINISH Interior finish SINGLE PARTITION (Finish on one side only of studs) DOUBLE PARTITION (Finish on both sides of studs) No INSULATION BETWEEN BTUDS 1 nr. BtumiH BETWEEN STUDS. Oai AIB SPACE. Metal Lath and Rasta*-------- Gypsum Board (H te.) Decanted.. Wood Lath and Raster .......----. Gypsum Lath (H la) Plastered*-- Plywood ($4 in.) Plain or Decorated Insulatinog BBooaarrdd(..H.....i.n...) Rain or D^SrateZT. Insulating Board Lath (U in.) Plastered'ZIZm Insulating Board Lath (1 in.) Plastered*-ZZZII 0.67 0.62 0.61 039 035 023 B 0.39 0.37 0.34 034 0.33 0.19. 0.18 012 0.16 aid 016 015 015 0.11 Oil 0.082 (See.text p. 186.) * See Table 5 Note e. "Coefficients not weighted; effect of studding neglected. * Plaster assumed 1 in.- thick. . e Plaster assumed I in. thick. - d For partitions with other insulations between studs refer to Table 6, using values in Column B of above table, in left-hand column of Table 6. Example: What is the coefficient of transmission (U) of a partition consisting of gypsum lath and plaster on both sides of studs with 2 in. blanket between studs? Solution: According to above table, this partition with no insulation between studs (No. 4B) has a coefficient of 0.34. Referring to Table 8, it will be found that a wall having a coefficient of 0.34 with no insulation between studs, will have a coefficient of 0.10 (approx.) with 2 in. of blanket insulation between studs (No. 56B). Table 11. Coefficients of Transmission W) of Masonry Partitions* fficients are expressed in Btu per (hour) (square foot) (Fahrenheit degree difference in temperature betu the air on the two sides), and are eased on still air (no wind) coriditions on both sides. M t/8HXY' ' TYPE OF PARTITION T h ic k n e s s o f M aso n bt ( I nches) type of finish No Finish (Plain walls) Plasteb One Sxsa AB Plasteh Both Sides* c .3 1 sos j Bouof Ola, Tm. HouorGipbiw rn.B r oS5o 4 . 3 035 - 4 0.29 0.47 0.43 0.42 0.40 033 . 032 038 . 037 9 10 11 12 Bouow UOKCRBIB Tn*oa Blocks Cinder Aggregate.________,, 3 4 Urfit Weight Aggregate*-- 3 4 CoMMOlt Bmor 4 030 0.45 0.41 035 030 0.47 0.42 0.39 034 0.46 0.43 13 030 14 037 15 032 . 16 0.43 17 bim` 8oIi<l plaster partition, U. = 0.53. Panded slag, burned clay or pumice. 4w ^ Heat Transmission Coefficients of Building Materials 195 13; (U)Table Coefficients of Transmission of Concrete Construction. Floors and Ceilings* Coefficients ore expressed in Btu per (hour) (square foot) (Fahrenheit degree difference in temperature between ike air on the two sides), and are based on still air (no wind) conditions on both sides. TYPE OF CEILING Tyf B OF FlOO alNG Thickness OF ` Concrete (Inches) % No Flooring (Concrete Bare) Tile* or Terrasso Flooring on Concrete H In. Asphalt Tile Directly on Concrete Parquette Flooring in Mastic on ^ Concrete' Double <4 a Wood S3 Floor on a p .2 Sleepers* AB C D No Ceiling.............. ................................... M in. Plaster Applied to Underride of Concrete................................................... Metal Lath and Plaster*--Suspended or Furred........... ..................................... Gypsum Board (H in.) and Plaster^-- Suspended or Furred.......................... \ Insulating Board Lath (H in.) and Plaster^--Suspended or Furred___ 3 6 10 3 6 10 3 6 10 3 6 10 3 6 10 0.68 0.69 0.60 0.63 0.54 0.46 0.38 0.35 0.32 0.36 0.33 0.30 0.25 0.23 0.22 0.65 0.66 0.48 0.59 0.52 0.44 0.37 0.34 0.31 0.35 0.32 0.29 0.24 0.23 0.21 0.66 0.68 0.49 0.60 0.63 0.45 0.37 0.35 0.32 0.35 0.33 0.30 0.26 0.23 0.22 0.45 0.41 0.36 0.43 0.39 0.34 0.30 0.28 ' 0.26 0.28 0.27 0.24 0:21 0.20 0.39 0.25 0.23 0.22 0.24 0.22 0.21 .. 0.1fr;: 0.18 0.17 0.19 0.18 0.37 0.15 0.15 0.34 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 * Thickness of tile to be 1 in. * See Table 5, Note a. b Conductivity of asphalt tile assumed to be 3.1. Thickness of wood assumed to be *Me in.; thickness of mastic, J4 in. (k * 4.6). Col. D may also be used for concrete covered with carpet. ^ Based on *94* in. yellow pine or fir sub-flooring and 1 Mo in. hardwood finish flooring with an air space between sub-floor and concrete. Thickness of plaster assumed to be H in. * Thickness of plaster assumed to be H in. 8 For other thtclrnggq of concrete, interpolate. -- Table 14. Coefficients of Transmission (G) of Concrete Basement Floors on Ground with Various Types of Finish Flooring V - 0.10* Btu per (hr) (sq ft) (Fahrenheit degree temperature difference between the ground and the air over the floor). * Since authentic data are not available, this coefficient is sometimes used for concrete floors on ground. Fw mote recent procedures refer to Notional Bureau of Standards Report BMS-103.WU Basement Floor, Basement Wall and Concrete Slab Floor Coefficients The heat transfer through basement walls and floors to the ground is dependent on the temperature difference between the air within and that of the ground, on the material constituting the wall or floor, and on the conductivity of the surrounding earth. The conductivity of the earth will vary with local conditions, and is usually unknown. Tests12 at the A.S.H.A.E. Research Laboratory indicate a heat flow of approximately 2.0 Btu per (hr) (sq ft) through an uninsulated concrete basement floor, with a temperature difference of 20 deg between ground temperature and the air temperature 6 in. above the floor. Based on this result a coeffi cient of 0.10 Btu per (hr) (sq ft) (Fahrenheit degree difference) is recom mended for calculation where it is desirable to allow for the small base ment floor heat loss, e.g., for heated basements. For basement walls the same coefficient may be used, but due to closer proximity to the surface of the ground, the temperature difference for win- 196 CHAPTER 9 1956 Guide Table 15. Coefficients of Transmission (U) of Flat Roofs Covered with Built-up Roofing. No Ceiling--Under Side of Roof Exposed* (See Table 16 for Flat Roofs with Ceilings) These coefficients are expressed in Btu per (hour) (square foot) (Fahrenheit degree difference in temperature between the air on the two sides), and are based on an outside wind velocity of IS mph. Ttpb op Roof Deck Thick ness OF Nolw- BTJLA- Roof (UDtceacmk ) Insulation on Top of Deck . (COTBBBD 'WITH BtJILT-UP ROOFING) Insulating Board (Thickness Below) In. In. 2* In. CoBKBOABn ' (Thickness Below) 14 In. Flat Metal Roof Deck0 . ttfSOlATtM/ 0.94 0.24 0.23 Heat Transmission Coefficients of Budding Materials 197 Table 16. Coefficients of Transmission (U) of Flat Roofs Covered with Built-up Roofing. With Lath and Plaster Ceilings* (See Table 15 for Flat Roofs with No Ceilings) These coefficients are expressed in Btu per (hour) (square foot) (Fahrenheit degree difference in temperature between the dir on the two sides), and are based on an outside wind velocity of IS mph. Type of Roof Deck ` Insulation on Top of Deck (Covered with Built-Up Roofing) Thick ness of Roof Deck (Inches) No In sula tion Insulating Boabd (Thickness Below) I In. 1 In. 11 In. 2 In. Cobkboard (Thickness Below) 14 In. 2 In. DE H NUMBKB Flat Metal Roof Deck 0.15 Precast Cement Tile /tiff JLOOFlHCt /Tuft spkfep 1| in. 0.8 0.16 0.13 Concrete ItiWUUTl*M> ...... tr- 2 in. 4 in. 6 in. 0.82 0.72 0.65 0.36 0.34 0.33 0.24 0.23 0.22 0.17 0.17 0.16 0.14 0.13 0.13 0.22 0.21 0.21 0.16 0.16 0.16 0.13 0.12 0.12 Gypsum Fiber Concrete^ on ) in. Gypsum Board iMJUt/ffidn/ ipJor\ ftOARF' r-3| in. 0.38 0.31 0.24 0.21 0.18 0.16 0.24 0.13 0.12 0.11 0.17 0.13 0.11 0.15 0.12 0.10 109HH6* / 1 in. 14 in. 2 in. 3 in. 0.49 0.37 0.32 0.23 0.28 0.24 0.22 0.17 0.20 0.17 0.16 0.14 0.15 0.14 0.13 0.11 0.12 0.11 0.11 0.096 0.16 0.17 0.16 0.13 0.14 0.13 0.12 0.11 0.12 0.11 0.10 0.091 See Table 5, Note a. < Coefficient of transmission of bare corrugated iron (no roofing) is 1.50 Btu per (hr) (sg ft of project*! area) (F deg difference in temperature) based on an outside wind velocity of 15 mph. 6 87| percent gypsum, 12J percent wood fiber. Thickness indicated includes 4 in. gypsum board. e Mm;noi thtnirnafise* AnAcified--actual thicknesses used in calculations. _ Precast Cement Tile ftetrtN4. /fttt If in. 0.26 0.14 Concrete 2 in. 4 in. 6 in. 0.42 0.40 0.37 0.26 0.19 0.25 0.18 0.24 0.18 0.14 0.14 0.14 0.12 0.12 0.11 0.18 0.17 0.17 0.14 0.13 0.13 0.11 0.11 0.11 GTM'Ium Fiber Concrete* 0Q 4 n. Gypsum Board 0.27 0.23 0.19 0.17 0.15 0.14 0.12 0.11 0.10 0.14 0.097 0.13 0.12 0.11 0.097 0.091 Wood* R0,Fl>,,^TtCn, 1 in. 14 in. 2 in. 3 in. 0.31 0.26 0.24 0.18 0.21 0.19 0.17 0.14 0.16 0.15 0.14 0.12 0.13 0.12 0.11 0.10 0.11 0.10 0.097 0.087 0.15 0.14 0.13 0.11 0.12 0.11 .0.11 0.095 0.10 0.095 0.092 0.082 . * 1 1 1 -_ iafan^ra*cCyafolcruglaytpiosnusmtnlasethd*oornwmooedtallaltahthanadndplapslatestrecrecileinilginsg. s,Ibt uist assumed that there is an Ti^Bp&ce w between 1blunder side of the roof deck and the upper side ofjne ceiling. .. .- - tf87H percent gvnsum ivja *>*.-~--*------ J c' 3 specified--actual thicknesses used in calculations. H` 4'. 198 CHAPTER 9 N um ber 3 In. - NWM'IO o.n 0.085 CO o z BA E *1 OOcOqOcOoO0mOO0cOi oo a 5S" 3B <w ^fn aa) Q < A - pi u&. z H 4 Ma . N Q W * OOOO oooo 1In. j O u a2 %* ao A zo g to :e> oooo 3oe . zo. ' ' s p a Z None ' MM too o eoeoeoc* oooo 3 In. 1 1 Blanket or Bat . 2 'a K ao a 5 Pi z Oz oh;"' "OD <Zrtg a 6tw- si* Sjg s a zo KCD- Od < *zo '^ BjDIS Z 5 is S< =o o5 :o. = SS S g-o e. sa < Pi zHtt U A zo B jpzat Blanket or Bat (Thickness Below) (Thickness Below) None None 0,084 0.083 0.082 , 0.081 0.081 O ;a 0.15 0.15 0.14 O.U 1 do oo fl * oooo oooo o eoea --- oooo 0.081 ' 3 In. 0 Q ooc SooSoS oo o o 1 In. I ' d lo C4 e A ` ! at oro 0.31 0.14 1 0.30 0.14 oooo oooo 0.29 0.14 0.29 0.14 0.079 0.072 0.072 0.064 0.30 0.23 0.22 0.17 0.10 0.091 0.090 0.079 0.081 0.074 0.073 0.066 0.31 0.24 0.23 0.17 0.15 0.13 0.12 0.10 0.10 0.092 0.091 0.080 0.081 0.074 0.074 0.060 ^C4C40 oooo aoaeosoNo oooo oooo 0.29 0.22 0.22 0.16 . . . . i a Sad~Ss.-sJ ao'Os 'ao*'tdr ,3,S ` Ills so^o so || * vaa O^ww C--XJ3 * n, '-mm ---OTJTJ dSS a --ooo t* fcc T5.S.S-S 33 a EL(3--IM3-tt3-M .1 Heat Transmission Coefficients of Building Materials 199 18.Table Combined Coefficients of Transmission (U) of Unvented Pitched Roofs and Horizontal Ceilings--Based on Ceiling Area** Coefficients ore expressed in Bin per (fomr) (square foot of ceiling area) (Fahrenheit degree difference in temperature between the air on the txoo sides), and are based on an outside wind velocity of16 mph. Ttfe of Roofing and Roof Sheathing Ceiung Coefficients Wood Shingles on Wood Strips* No Roof Insulation (Rafters Exposed) (Ur - 0.48) H In. Insu- 1 In. Insulating Board lating Board on Under Side on Under Side of Rafters of Rafters (Ur - 0.22) (Ur *= 0.16) Asphalt Shingles' or Roll Roofing on Wood Sheathing* No Roof Insulation (Rafters Exposed) (Ur =* 0.53) H In. Insu- lating Board lating Board on Under Side on Under Side of Rafters of Rafters (Ur = 0.23) (Ur - 0.17) A a S A B C D EF - 0.10 0.085 0.11 0.092 0.12 . 6.099 0.13 0.11 0.14 - 0.11 0.073 0.078 0.082 0.087 0.091 0.066 0.07 0.074 0.078 0.081 0.087 0.094 0.10 0.11 0.11 0.074 0.079 0.083 0.088 0.093 0.067 0.071 0.075 0.079 0.083 19 20 21 22 23 0.15 o:ie 0.17 0.18 0.19 0.20 0.21 0.22 0.23' 0.24 0.25 0.26 0.27 0.28 0.29 0.12 0.13 0.13 0.14--------- 0.14 0.15 0.15 0.16 0.16 0.17 0.17 0.18 0.18 0.19 0.19 0.096 0.10 0.10 0.11. 0.1L 0.11 0.12 0.12 0.12 0.13 0.13 0.13 0.13 0.14 0.14 0.084 0.087 0.090 0.093 0.095 . 0.098 0.10 0.10 0.10 0.11 0.11 0.11 0.11 0.12 0.12 0.12 0.13 0-13 0.14 0.15 0.15 0.16 0.17 0.17 0.18 0.18 0.19 0.19 0.19 0.20 0.097 0.10 0.10 0.11 0.11 0.12 0.12 0.12 0.12 0.12 . 0.13 0.13 0.13 .0.14 0.14 0.086 0.089 0.092 0.095 . 0.098 24 25 26 27 28 0.10 0.10 0.11 0.11 0.11 29 30 31 32 33 0.11 0.11 0.12 0.12 0.12 . 34 35 36 37 38 0.30 0.34 0.35 0.36 0.37 0.20 0.21 0.22 0.22 0.23 0.14 0.15 0.15 0.15 0.15 0.12 0.12 0.13 0.13 0.13 0.20 0.22 0.22 0.23 0.23 0.14 0.15 0.15 0.15 0.16 0.12 0.13 0.13 0.13 0.13 39 40 41 42 43 0.45 0.59 0.61 0.62 0.67 0.69 _____ _____________ 0.25 0.29 0.29 0.30 0.31 0.31 0.17 0.18 0.18 0.19 0.19 0.19 0.13 0.14 0.15 0.15 0.15 0.15 0.26 0.30 0.31 0.31 0.33 0.33 0.17 0.19 0.19 0.19 0.20 0.20 0.14 0.15 0.15 0.15 0.16 0.16 44 45 46 47 48 49 (See text on p. 189.) * See Table 5, Note a. ' Calculations based on $ pitch roof (n = 1.2) using the following formula: i, Ur X (Joe u JJ~ UrH---- n U -- combined coefficient to be used with ceiling area. Ux = ooeffioent of transmission of the roof. . Uce = coefficient of transmission of the ceiling. n -- the ratio of the area of the roof to the area of theceiling. Use ceiling area (not roof area) with these coefficients. e Coefficients in Columns D, E and F may be used with sufficient accuracy for tile, slate and rigid as- *)estcB shingles on wood sheathing. . Based on 1 x 4 in. stiips spaced 2 in. apart. Sheathing assumed 2^2 in. thick. Values of Un to be used in this column may be selected from Table 12. ter design conditions will be greater than for the floor. The test results indicate a unit area heat loss, at mid-height of the basement wall approxi mately twice that of the same floor area. For concrete slab floors laid in contact with the ground at grade level, recent tests13 indicate that for small floor areas (equal to that of a house 25 feet square) the heat loss may be calculated as proportional to the length of exposed edge rather than total area. This amounts to 0.81 Btu Per (hr) (linear foot of exposed edge) (Fahrenheit degree difference between 200 CHAPTER 9 Table 19. Coefficients of Transmission (17) of Solid Wood Doors' Coefficients are expressed in Btu per {hour) {square foot) {Fahrenheit degree difference in temperature between the air on the two sides), and are based upon an outside wind velocity of iS mph. Nominal Thickness Inches Actual Thickness Inches . ;: (/b Exposed Doob ji -</ 1 With Glass Stobm Doob' 1 H 37 1A 0.69 0.59 0.52 0.35 0.32 0.30 H U if 0.51 0.30 0.46 0.28 2 2J 3 2 21 0.38 0.33 0.25 0.23 ** SCAeoeUmTpvauabtllueeed5ou, fsN0ino.8gt5ekma.--ay1.b1e5 ufoser dwfooords,ifnigl--e e1x.6p5o,s/ecd=do6o.r0s, caonndta1i.n10infgorthaiinr swpoaocde. panels or single panes of glas*s5, 0apnder0c.e3n9tfgolrasthseansdamtheinwwithoogdlapsasnsetlosr.m doors. ' Table 20. Coefficients of Transmission (17) of Windows, Skylights i and Glass Block Walls Coefficients are expressed in Btu per {hour) {square foot) {Fahrenheit degree difference in temperature belxot air on the two sides), and are based upon the following outdoor conditions: 0 F air temperature, clear skits, no solar radiation ' . ' -:Vr Section A--Vertical Glass Sheets & -----"t& Number of Sheets One Two --IThree Air Space, inch.. None 1.13 W 0.61 0.55 1 0.53 H 0.41 0.36 0M Seoton B--Horizontal Glass Sheets (beat flow op)_ Number of Sheets One None 1.40 K 0.70 Two j0.66 1 0.63 - ,h Description 5| x 5f x 3} in. thick............... ........................................................................ 7i x 7} x 3| in. thick....................................................................................... 711||xx7l\lxj 3x iZini i.nt.htihckicwk.i..t.h....g..l.a.s..s...f..i.b...e..r...s..c..r..e..e..n....d...i.v...i.d..i..n..g....t..h.e....c...a...v..i.t..y. . U 0.60 0.56 0.52 0.48 -II 4 it SECTir.^AVPFLAT`g1SbA"v""S,FVA^,^^OWB Windows -with SXOB-Ifi Sash* (See text p. 201.) * Fororm1 iunn.pourbglirsehaetedr.data recommended by ASHVE Tech. Adv. Comm, on Glass. * Unit type double glazing (two lights or panes in same opening). * UBsaesewd iothn aUrevaaoluf esxpfoosretdwpoosrhtieoentsofwsiathsh1: dinoe. sanirostpinaccelu. de frame or portions of sash concealed by / For metal storm sash Or metal sash with attached storm pane. . a Heat Transmission Coefficients of Building Materials 201 the inside air temperature and the average outside air temperature). It should be noted that this may be appreciably reduced by insulating under the ground slab, and also along the edges between the floor and the abut ting walls. See also sections on Basement Temperatures and Heat Loss, and on Floor Heat Loss in Basementless Houses, in Chapter 12. In most calculations if the perimeter loss is calculated accurately, no other floor loss need be considered. , . Glass Coefficients The U values for glass sheets and hollow glass block, given in Sections A, B and C of Table 20, have been computed by methods and data given in an A.S.H.V.E. Research Paper.8 It is assumed that the surface conduct ance for convection loss to the air is 4.0 Btu per (hr) (sq ft) (F deg). It is also assumed that the glass loses heat by radiation to the ground and to the clear sky, which together have an effective radiating temperature below the air temperature. It is therefore necessary to determine, by trial and error, the temperature of the outdoor glass surface such that the sum of the radiation and convection losses equals the heat conducted through the glass section, and equals the heat delivered to the glass from the heated space. This heat flow, divided by the air-to-air temperature difference, results in a U value..which is used in the usual manner. The equivalent surface conductance for radiation and convection combined, based on airto-surface temperature difference, therefore varies from about 5.5 for sin gle glass to about 6.6 for double glass for exactly the same environmental design conditions. It is assumed that the room air temperature equals the average tem perature of the room surfaces seen by the glass. Special consideration should be given to those cases where the glass sees interior surfaces at temperatures differing greatly from the room air temperature, i.e., such cases as in sun rooms, greenhouses, and some panel heated rooms, or where there is an unusual amount of air motion in the vicinity of the glass. Although based on zero outdoor air, the values change only slightly with different design temperatures, being about 5 percent greater for a 30 F outdoor design temperature. In computing the Table 20 values, consideration, of the dependence of the, indoor surface conductances upon temperature and direction of heat flow leads to surface conductances averaging about 1.50 for block and vertical glass, and about 1.80 for horizontal glass, as compared to the value of 1.65 used in computing U values given in other tables in this chapter. These values should therefore be used in estimating the tem perature at which condensation on glass surfaces will occur. The application factors given in Section D of Table 20 are based upon hot box tests summarized in a research bulletin,14 and are approximate 9ly. In practice, some variation in heat flow through windows having the same ratio of glass to sash area, may be expected because of difference construction details and in air space edge effects. The high conductance f aluminum and steel sash must be taken into consideration where exces sive amounts of metal sash and frames are involved. This is particularly important when they are in close proximity to radiation heat sources and are consequently subjected to high differential temperatures. Wind Velocity Correction for U Values f Tables 7 to 9, and 15 to 19, present values of V for walls and other sur- ccs based on an outside wind velocity of 15 mph. Table 21 shows com parative values of U for other wind velocities. 202 CHAPTER 9 1956 Guide : Example 3: Find the coefficient of transmission U of a frame wall consisting of stucco, 2^2'in. insulation board sheathing, 2 x 4-in. studs, gypsum lath and plaster, and with 2-in. blanket insulation between studs, for 25 mph wind velocity. Solution: From Table 7, Wall No.20, with no insulation between studs has a value of U = 0.19. From Table 6, Col. 4, this wall with 2-in. insulation added has a value of U ~ 0.084. Entering Table 21 in the 15 mph column, interpolate between 0.080 and 0.090 in 15 mph column and proceed horizontally to the 25 mph column where the 17 value is found by interpolation to be 0.085. . UTable 21. Conversion Table for Wall Coefficient fob Various WiNjn Vpt.TJPVTIES 0.050 0.060 0.070 . 0.080 0.090 .0.100 0.110 0.130 0.150 0.170 0.190 0.210 0.230 0.250 0.270 0.290 0.310 0.330 0.350 . 0.370 0.390 0.410 0.430 0.450 0.500 0.600 0.700 0.800 01..900000 1.100 1.200 1.300 0.049 0.059 0.068 0.078 0.087 0.096 0.105 0.123 0.14! 0.158 0.175 0.192 0.209 0.226 0.241 0.257 0.273 0-288 0.303 0.3J8 0.333 0.347 0.362 0.376 0.410 0.474 0.535 0.592 0.645 0.695 0.742 0.786 0.828 0.050 0-059 0.069 0.079 0-089 0.099 0.108 0.127 0.147 0.166 0.184 0.203 0.222 0.241 0.259 0.278 0.296 0.314 0.332 0.350 0.368 0.385 0.403 0.420 0.464 0.548 0.631 0.711 0.789 0.865 0.939 1.010 1 1.080 0.050 0.060 0.070 0.080 0.090 0.100 0.109 0.129 0.149 0.169 0.188 0-208 0.227 0.247 0.266 0.286 0.305 0.324 0.344 0.363 . 0-382 0.402 0.421 0.439 0.487 0.581 0.675 0.766 0.858 0.949 1.039 1.129 1.217 0.050 0.060 0.070 0.080 0.090 0.100 0.110 0.131 0.151 0.171 0.191 0.212 0.232 0.252 0.273 0.293 0.313 0.333 0.354 0.375 0.395 0.416 0.436 0.457 0.509 0.612 0.716 0.821 0.927 1.034 1.142' 1.250 1.359 0.050 0.060 0.070 0.080 0.091 0.101 o.m 0.131 0.151 0.172 0.192 0.213 0.233 0.253 0.274 0.295' 0.315 0.336 0.357 . 0-378 0.399 0.420 0.441 0-462 - 0-514 0.620 0.728 0.836 0.946 1.058 1.170 1.285 1.400 3 calculated foi 15 mph wind velocity. V in first column is from previous tables or i 0.050 0.060 0.070 0.080 0.091 0.101 o.m 0.131 0.152 0.172 0.193 0.213 0.234 0.254 0.275 0.296 0.317 0.338 0.359 0.380 0.401 . 0.422 0-444 0.465 0.518 0.826 0.736 0.847 0.960 1.075 1.192 1.318 1.430 CALCULATING SURFACE TEMPERATURES In many heating and cooling load calculations it is necessary to deter mine the inside surface temperature or the temperature of the surfaces within the structure. As the resistance of any path of heat flow is ex pressed in Fahrenheit degrees per (Btu) (hour) (square foot), the re sistances through any two paths of heat flow would be proportional to the temperature drop through these paths, and can be expressed as follows: A. . ~~ *> R*' ' (u - o (6) where R\ the resistance from the inside air to any point in the structure at which the temperature is to be determined. Heat Transmission Coefficients of Building Materials 203 Rt = the overall resistance of the wall from inside air to outside air. li = inside air temperature. == temperature to be determined. ta - outside air temperature. * Example 4: Determine the inside surface temperature for a wall having an overall coefficient of heat transmission U = 0.25, inside air temperature 70 F, outside air temperature -- 20 F. Solution: Rt = l//i = 1/1.65.* 0.606 Rt 1/17 = 1/0.25 = 4.00 Then, by Equation 6 0.606 70 - U 4.00 = 70 - (-20) tx * 56.4 F The same procedure can be used for determining the temperature at any point within the structure. A chart for determining inside wall surface temperature is given in Fig. 12 of Chapter 24, Panel Heating. ' REFERENCES 1 Standard Method of Test for Thermal Conductivity by Means of the Guarded Hot Plate, sponsored by A.S.H.V.E., A.S.T.M., A.SM.Eand N.R.C., and approved as a Tentative Code by A.S.H.V.E. and A.S.T.M. in 1942 {A.S.T.M. designation C-177-45, Approved 194&). * Heat Transmission Through Building Materials, by F. B. Rowley and A. B. Algren {University of Minnesota. Engineering Experiment Station Bulletin. No. 8, P- U). * Thermal Properties of Soils, by Miles S. Kersten {University of Minnesota, En gineering Experiment Station Bulletin No. 28, June 1949). 4 Radiation and Convection from Surfaces in Various Positions, by G. B. Wilkes and C. M. F. Peterson (A.S.H.V.E. Transactions, Vol. 44, 1938, p. 513). 6 Radiation Corrections for Basic Constants Used in the Design of All Types of Heating Systems, by B. F. Raber and F. W. Hutchinson (A.S.H.V.E. Transactions, Vol. 51. 1945, p. 213). A.S.H.V.E. Research Report No. 869--Surface Conductances as Affected by Air Velocity, Temperature and Character of Surface, by F. B. Rowley, A. B. Algren and J. L. Blackshaw (A.S.H.V.E. Transactions, Vol. 36, 1930, p. 444). 'Forced Convection Heat Transfer from Flat Surfaces, by G. V. Parmelee and R. G. Huebscher (A.S.H.V.E. Research Bulletin No. 3, p. 40; also published in A.S.H.V.E. Transactions, Vol. 53, 1947, p. 245). " A.S.H.V.E. Research Report No. 1399--Heat Flow through Unshaded Glass: Design Data for Load Calculations, by G. V. Parmelee and W. W. Aubele (A.S.H.V.E. Ihansactions, Vol. 56, 1950, p. 371). "The Thermal Insulating Value of Airspaces, by H. E. Robinson, F. J. Powlitch fnr4 R. S. Dill {Housing and Home Finance Agency, Housing Research Paper No. 32, iy54> U. S. Government Printing Office). p ^cnnal Test Coefficients of Aluminum Insulation for Buildings, by G. B. Wilkes* * G. Rechler and E. R. Queer (A-S.H.Y.E. Transactions, Vol. 46,1940, p. 109). p H,?^ect of Studs and Joists on Heat Flow Through Frame Walls and Ceilings, by au D. Close (Heating, Piping and Air Conditioning, October, 1943, p. 529). . A-S.h.v.E. Research Report No. 1213--Heat Loss Through Basement Walls a Qt!00rs by F. C. Houghten, S. I. Taimuty, Carl Gutberlet and C. J. Brown VA-b.H.V.E. Transactions, Vol. 48, 1942, p. 369). Vi^jjsurements of Heat Losses from Slab Floors, by R. S. Dill, Wm. C. Robinson Report BMS*o3f^on ^a^ona^ ^ureau f Standards, Building Materials and Structures *J tteat Transmission through Glass, by G. V. Parmelee (A.S.H.V.E. Research Bulletin No. 1, July 1947). ' . CHAPTER 9 ' 1956 Guide 204 BIBLIOGRAPHY , A.S.H.V.E. Research Reports: , , / ` "" ' No. 852--Effects of Air Velocities on Surface Coefficients, by F. B. Rowley, A. B. Algren and J. L. Blaekshaw (A.S.H.V.E. Transactions, Vol. 36, 1930, p. 123). .: No. 895--Wind Velocity Gradients Near a Surface and Their Effect on Film Conductance, by F. C, . Houghten and Paul McDermott (A.S.H.V.E. Transactions, Vol. 37, 1931, p. 301). . No. 914--Surface Coefficients as Affected by Direction of Wind, by F. B. Rowley and W. A. Eckley ..................... (A:S.H.V.E. Transactions, Vol. 38, 1932, p. 33). /' - ` No. 915--Conductivity of Concrete, by F. C. Houghten and Carl Gutberlet (A.S.H.V.E. Transact No. 964--tTihoensH, eVaotl.C3o8n, 1d9u3c2t,ivpi.ty47o).f Woo.d at Cl.imatic .Temperature Differences, by F. .B. Rowley (A.S.H.V.E. Transactions, Vol. 39, 1933, p.` 329). No. 996--Insulating Value of Bright Metallic Surfaces, by F. B. Rowley (A.S.H.V.E. Transactions Vol. 40, 1934, p. 413). . .. No. 1026--Thermal Properties of Concrete Construction, by F. B. Rowley, A. B. Algren and Clifford Carlson (A.S.H.V.E. Transactions} Yol. 42,1936, p. 33). ^ No. 1048--Thermal Properties of Concrete Construction, by F. B. Rowley, A. B. Algren and Robert Lander (A.S.H.V.E. Than8actions,~Vo1. 43, 1937, p. 33). ' No. 1351--Overall Coefficients for Flat Glass Determined under Natural Weather Conditions, by G. V; Parmelee and W, W. Aubele (A:S.H.V:E, Transactions, Vol. 55, 1949, p. 39). . Radiation and Convection Across Air Spaces in Frame Construction, by G.B. Wilkes andC. M. F. Peter* son (A.S.H.V.E. Transactions, Vpl. 43, 1937-, p. 351).;.......... ^ . r> .. ..... ... Insulating Effect of ' Successive Air Space Bounded by Bright Metallic Surfaces, by L. ,W. Schad (A.S.H.V.E. Transactions, Vol. 37, 1931, p. 285). . . ' ' Thermal Conductivity of Wood, by J. D. MacLean (A.S.H.V.E. Transactions, Vol. 47,1941, p. 323). The Specific Heat of Thermal Insulating Materials, by G. B. Wilkes and C. O, Wood (A.S.H.V.E. Tranb- AcnoNS, Vol. 48, 1942, p. 493). _ .. ' Heat Loss Studies in Four Identical Buildings to Determine the Effect of Insulation, by D. B. Anderson (A.SE.fHfe.cVt.oEf. CTerialinnsgaIcntsiuolnasti,oVnoul.p4o8n, 1S9u42m, pm.e4r7C1)o. mfoH, b y T. D. Phillips (National Bureau of Standardi, Report BMS52, July 1, 1940)... . . .. , -. Thermal Insulation Made of Wood-Base Materials. Its Application and Use in Houses, by L. V. Teesdate (U. S. Forest Products Laboratory Report No. R1740,.October 1949).' ' . ' HeatTransmission'Through Building Materials,'by F. B. Rowley and A. B. Algren {University of Minne sota, Engineering Experiment Station Bulletin No. 8). Building Insulation^by Paul D-CipW:(Amcr^n TecAnwai Society, Chicago, 4th Edition, 1951). . CHAPTER 10 ' ' : . MOISTURE IN BUILDING CONSTRUCTION Properties of Water in Air; Water in Building.Materials; Movement of Moisture in Materials; Vapor Transmission; Permeance and Testing'; Visible Condensation; Concealed Condensation in Heated Buildings; ' Control of Concealed'Condensation; Condensation in '\ Cooled Structures THE behavior of moisture is too often overlooked or given, scant at tention in the design and construction of buildings. It is present as a vapor-in all air and as adsorbed moisture in most building materials. may be present also at times in the free liquid state or as ice, in the solid state, within the range of temperatures encountered ip many buildings. Problems involving-moisture may arise from changes in: moisture content, from the presence of excessive moisture, or from effects associated with its changes in state. : : It Of particular interest here is the change from the vapor to the liquid or solid state, known :as condensation. This may be associated with a re duction of temperature with time; or may occur as a result of migration of water vapor to regions of lower temperature. Moisture problems involv- . ing condensation are therefore most likely to occur mi buildings in any climate in which there is a source :of water vapor at temperatures above normal, or in cooled structures, and in buildiigs in cold climates. Moisture problems in residences occur in winter and become increasingly important as homes are built smaller and tighter. Water vapor originates from such necessary living requirements as cooking, laundering, bathing, and the breathing and perspiration of people. In a typical family of four, the average daily production of water vapor from these .sources may be as much as 25 lb, aiid may be much greater where such appliances as humidifiers, automatic washers, and dryers are used.1 Another large source of water vapor is sometimes the bare earth in a crawl space or base ment. All this water vapor must escape from the dwelling. . PROPERTIES OF WATER VAPOR IN AIR Water vapor in air is a gas which occupies all the space, along with the air present. In many ways, the water vapor can act independently of the au-, since in general its properties do not depend on the presence of the aw- It exerts its own vapor pressure, and can move about through air in space, or move through materials under differences in its own vapor swiHSUT' lnf^Pendently of the air. However, when the air is moved aff t r *s h^ted or cooled, the water vapor present is similarly ected, so that it is usually necessary to consider it as a part of an airVaPor mixture. lcnT^6 properties of mixtures of air and water vapor are relatively well in tif11 an^ are c?ea^ with fully in Chapter 3, Thermodynamics. Changes the Vi6 ProPert,les with heating and cooling can be followed readiiy with TM 01 a psychrometric chart, shown in outline in Fig. 1. The satura- a; Si ij: ;!; :r -i lit n [( if- jif 11: \l\ r.v 206 CHAPTER 10 1956 Guide tion line represents the limiting concentrations of water vapor which can exist as vapor at various temperatures. . A common condition inside buildings, 70 F. and 40 percent relative humidity, is represented by point A. This is a condition of partial satura tion; i.e., less than .100 percent relative humidity. The vapor pressure of the water present in the air, although not shown on the chart, can be calcu lated readily from the vapor pressure at saturation and the relative hu midity, since relative humidity is very nearly equal to the ratio of the actual vapor pressure to the saturation pressure at the existing temper ature. The increasing relative humidity accompanying cooling from the condition represented by A on the chart to point B can readily be followed. At B, however, at 44.6 F, the relative humidity becomes 100 percent, and the-air-vapor mixture is said to be saturated. The temperature at which this particular air-vapor mixture, upon cooling, becomes saturated is its 1 TwoFig Typical Heating and Cooling Processes in Air within Buildings '' A.S.H.V.E.Shown on Psychrometric Chart dew-point temperature. Upon further cooling, to 35 F, the original amount of water vapor can no longer be retained and is reduced, in this case, to the condition represented by C, from 0.0633 lb per lb dry air to 0.0427 lb per lb dry air. The process ABC is typical of that which an air-vapor mixture experiences when it comes in contact with a cool window surface. Cooling from B to C results in visible condensation on the glass surface. If the point C were below 32 F., the condensation would be in the form of frost. Once the temperature drops below the dew point, or frost point if be low 32 F., the vapor pressure at the condensing surface is also reduced, thereby establishing a gradient of vapor pressure from the room air to the window surface. This gradient will operate, in conjunction with the convective action within the room, to move water vapor continuously to the window surface to be condensed, so long as the concentration of water vapor in the room is maintained. A common winter process is that shown by DE, showing air at 20 F-,. saturated, being heated to 70 F. with a resulting large decrease in relative humidity. This explains, in part, the greatly reduced relative humidities Moisture in Building Construction 207 experienced in houses in extreme cold weather, when cold outside air enters the house and is heated. , WATER IN BUILDING MATERIALS The surfaces of most common materials have an affinity for water molecules. Molecular forces of attraction will hold water molecules to the surface, but decrease veiy rapidly with increase in distance Of molecu lar proportions. The film thickness and therefore the amount of water held in equilibrium with the surrounding atmosphere is roughly propor tional to relative humidity. Surface films of water molecules, at low humidities, may be only one molecule thick; at moderate humidities poly-molecular films may be established, while at humidities very close to 100 percent, the films become so thick, relatively, that small pores may become filled and larger capillaries may be partially filled. At satura tion conditions all voids in the material may be completely filled. Some materials such as silica gel, alumina and most natural fibrous materials present very large effective surfaces to the water molecules, so that the amount of water held on the effective surface in these materials may be relatively large, even at moderate humidities. These are said to be hygroscopic. Other materials, such as most metals, not penetrated by the water molecules, present relatively small surfaces and so may take only minute quantities of water, except when wetted directly by liquid. Substances having a great affinity for water, and their use as dehumidifying agents, are described in Chapter 38. Data on the moisture contents of various common materials in equilibrium with the atmosphere at various relative humidities are given in Table 2 of Chapter 45, and equilibrium moisture content is further discussed in Chapter 47 on Industrial Drying Systems. Significant dimensional changes take place in many materials used in buildings, with change in moisture content: Those which take place in wood, of the order of 0.1,'2, and 4 percent in the longitudinal, radial and tangential directions, respectively, on a change from air dry at 12 to 15 percent moisture content to oven dry are perhaps the best known. Most wood-fiber products, including papers, will exhibit moisture expansion consistent with the basic wood properties to a degree dependent on the fiber orientation and arrangement.. Data on wood are available in publica tions on wood technology. Almost all plant and animal fibers experience appreciable moisture changes with changing relative humidity and undergo substantial dimensional changes of the same order as those in wood. Less generally recognized are the dimensional changes which can occur in masonry materials as a result of changes in moisture content. Water is either an essential or a contributory factor in almost all cases f breakdown of building materials resulting from chemical changes such as the rusting of steel, physical changes such as the spalling of masonry by frost action, or biological processes such as the rotting of wood. The control of water in building constructions may be necessary to ensure adequate service from the materials involved. Condensation of water vapor, although not the only means by which wetting may be brought about, is nevertheless a most insidious one par ticularly in respect of freeze-thaw breakdown, since from its nature it is most likely to occur at points of low temperature at which there may later be risk of freezing while the material remains in a saturated condition. 208 CHAPTER 10 1956 Guide Moisture in building materials may have a marked effect upon the trans mission of heat through them. It has been commonly assumed that mois ture when present in a material will remain more or less stationary and will increase the conductivity largely by adding to the path available for heat flow. On this basis, the effect of moisture on heat flow can be accounted for quite simply by the use of suitable coefficients of conductivity in the usual heat-flow equations. The data presented in Chapter 9 on moist soils are of this type. , Evidence to date indicates, however, that in porous materials partially saturated with water there is likely to be a migration of moisture to the cold side under the influence of the temperature gradient. This can occur by a process of evaporation, vapor flow, and condensation within the material, a substantial amount of heat being transferred as latent heat of the vapor, particularly in the case of open fibrous materials. The trans mission of heat through moist materials becomes complex whenever condi tions are such as to produce any appreciable migration of the moisture, and, consequently, calculations by the usual heat-flow theory alone, are an approximation. . MOVEMENT OF MOISTURE IN MATERIALS Moisture is caused to migrate in granular media or in porous solids by gradients in hydrostatic pressure, vapor pressure, capillary forces, concen tration of salts, temperature, or electrical potential. Neither the various mechanisms nor the particular potentials involved are entirely unrelated. They are frequently combined in most complex ways not at all well un derstood. A temperature gradient in a moist material usually produces a vapor-pressure gradient with consequent vapor migration. Whether the temperature gradient is able to produce migration by other mecha nisms is still being debated. There is a relationship between vapor pres sure and capillary force, and with a condition of capillary-force gradient but uniform temperature, there will also be a vapor-pressure gradient. At high relative humidities small capillaries may be completely filled and larger capillaries partially filled, "so that movement of liquid water may occur in combination with vapor movement. There is some evidence that under special conditions vapor movement and liquid movement through capillaries may occur simultaneously but in opposing directions. VAPOR TRANSMISSION THROUGH MATERIALS The equation presently used in calculating water-vapor transmission through materials is based on a form of Fick's Law, and is as follows: where to = weight of vapor transmitted through a unit area in unit time. p -- vapor pressure. x = distance along the flow path. and hence: ^2- = vapor pressure gradient. dx u = permeability. Moisture in Building Construction 209 The close parallel with Fourier's equation for heat flow will be noted. The actual transmission of vapor through a material is extremely complex, so that the coefficient, m, is not a simple one but is actually a function of relative humidity and temperature, and may vary along the flow path through the material in question. Integrating Equation 1 from x = 0 to x -- l and from pt to jh, and re arranging, the following is obtained: (Pi -- Pi) (2) i Let Then, (3) where w = Pi - pi l (4) i = length of flow path (or thickness of material). If Equation 1 had been integrated, assuming the coefficient p to be independent of vapor pressure (and temperature) along the flow path, Equation 4 would have been obtained, but with p. replaced by p. The coefficient p is therefore an average permeability coefficient applicable to the varying conditions along the flow path of length l, while the coefficient ,p is the spot or differential permeability. Equation 4 may be rewritten and units assigned: where, W = pAb (5) W = total weight of vapor transmitted, grains. A = area of cross-section of the flow path, square feet. = time during which the transmission occurred, hours. rip -- difference of vapor pressure between ends of the flow path, inches of mercury. I = length of flow path, (or thickness of specimen), inches. The basic units given are those now favored by the building industry. The permeability p or g is therefore expressed in a unit of grains-inches Per (square foot) (hour) (inch of mercury vapor pressure difference). Whenever it is convenient to deal with a material of a stated or implied thickness other than the unit thickness to which p or g refer, use may be mad of the permeance coefficient M, where M = p/l. The designation perm for the unit of permeance is now widely used, and is a convenient substitute for the unit, 1 grain per (square foot) (hour) (inch of mercury vapor pressure difference).2 The corresponding unit of permeability is Perm-inch, since it is the permeance of unit thickness. The corresponding now equation is: ' Resistance to vapor flow provided by a'sheet or board is the reciprocal 210 CHAPTER 10 1956 Guide of the permeance, and correspondingly, the over-all vapor resistance of an assembly (like a wall) of materials in series is the sum of the resistances of its component parts. The over-all permeance of the assembly may be found from the permeances of the individual components3-4 in a manner paralleling that used in calculating the over-all coefficient of thermal con ductivity from the individual conductances: , )Mt M \Mi +J- ^ Mi + Mt ... + (7) This simple theory for vapor flow, as in the case of the corresponding PLASTER MINERAL WOOL SHEATHING ON LATH BETWEEN STUOS^ PAPER a SIDING Fig. 2. Temperate and Vapor Pressures ender Vapob Flow Condition IN THE Insulated Frame Wall op example i. simple heat-flow theory, assumes conditions of unidirectional, steadystate flow. Useful calculations can be made for an assembly or sub assembly for which the inflow and outflow of vapor are equal (a condition at which no condensation occurs) if a permeance applicable to actual conditions can be assigned to each component part. Over-all permeances, vapor pressures and vapor flow can be calculated, and in conjunction with thermal calculations, relative humidities can be determined, and the imminence of condensation predicted. (See Example 1, and Fig. 2. See also Chapter 13, Cooling Load, for use of vapor-flow calculations.) ` Example 1: A wood frame wall is exposed to inside conditions 70 F. and 50 peme"5 relative humidity (0.37 in. Hg vapor pressure) and outside conditions 0 F. anJ * percent relative humidity (0.03 in. Hg vapor pressure). The wall consists of painted plaster on gypsum lath on the inside over 2 x 4 in. studs, mineral wool fill betwee" Moisture in Buildine Construction 211 studs, 1 in. wood exterior sheathing, paper, and pine lap siding. Check for possible condensation. . To simplify the example, consider the paint, plaster and lath as a single element having a permeance Af = 1.0 perms and a thermal conductance C = 2.4, and the exterior sneathing, paper, siding and paint as another single element for which M = 2.0 perms and C = 0.50. From Table 1 the value for the permeability of mineral wool fill may be found a8f = 116 perm-inches. The thermal conductivity for mineral wool, k = 0.27. .. Solution: In this particular wall, insulated, and with moderate warm-side relative humidities, condensation is unlikely to occur until the sheathing is reached. To check directly for condensation on the warm side of the exterior sheathing (designated as plane X -- X in Fig. 2 for convenient reference) proceed as follows: Calculate according to the method of Chapter 9 the temperature at plane X -- X. This is found to be 9 F. The saturation vapor pressure at this temperature is 0.06 in. Hg. If condensation is imminent or occurring at X -- X, the vapor pressure there will be 0.06 in. Hg. Calculate the permeance for the portion of the wall from the warm side to X -- X, and the vapor flow rate to X -- X as follows: Permeance of wall to X -- X = ---------= 0.97 perms. _1__L 4.o25 1.0 + 116 Vapor presssure drop to X -- X = 0.37 -- 0.06 = 0.31 in. Hg.- Vapor flow to X --- X-= 0.97 X 0.31 = 0.30 grains per (sq ft) (hr). Calculate the vapor flow rate from X -- X to outside as follows: Permeance of wall from X -- X to outside = 2.0 perms. Vapor pressure drop from X -- X to outside = 0.06 -- 0.03 = 0.03 in. Hg. Vapor flow rate to outside ^ 2.0 X 0.03 = 0.06 grains per (sq ft) (hr). It is apparent that continuity of vapor flow is not possible, since at the highest vapor pressure at X -- X permitted by the temperature, there is indicated a greater flow to plane X -- X than from it to outside. Condensation is indicated at a rate of 0.30 -- 0.06 = 0.24 grains per (sq ft) (hr). Whether thiB condensation rate will be serious must still be decided, since it might readily be absorbed by the sheathing during the condensation period without excessive wetting. When the temperature at X -- X is below freezing, as in this case, the condensation will be in the form of frost which may accumulate until re leased over a short period upon a rise in outside temperature. Condensation will be reduced or avoided if the permeance of the warm side of the wall can be reduced so that the flow to X -- X is limited to 0.06 grains per (sq ft) (be). Permeance required for this is q pg = 0.19 perms or less. A more re sistant paint film on the plaBter, reducing the paint-plaster-lath permeance to 0-19 perms would accomplish this. . When the critical plane for condensation is unknown, or for a more informative, graphical representation of the situation throughput the wall, temperatures and YaPr pressures may be calculated and plotted as in Fig. 2. The vajjor pressures throughout the wall, for continuity of flow, are calculated in a manner similar to the temperatures; the external vapor pressures are given, and the vapor pressure drops across each element are taken in proportion to resistance to vapor flow. The curve for saturation vapor pressures at the various temperatures throughout a'So shown in Fig. 2 and is seen to fall below the curve for vapor pressures VtL ?ntiRuity of flow, .toward the outer portions of the wall. This indicates that an4 6 `ven temperatures and vapor pressures, continuity of flow is not possible defi * condensation will occur. Condensation on the sheathing is indicated as a possibility, and the new vapor pressure curve can be constructed for this ondition, as shown. This new curve does not rise above the saturation-vapor-pres- 212 CHAPTER 10 1956 Guide ure curve, thereby confirming that the critical plane for condensation was correctly assumed. ., With the vapor pressures thus established, the relative humidities may be found, by reference to the saturation vapor pressures. The permeances originally assigned to the various elements may then be re-examined in the light of the service conditions of temperatures and relative humidities indicated, ana the analysis repeated, if necessary, using more appropriate permeance values. In a more detailed analysis, individual values might be assigned to the elements forming the outer portion of the wall, which is here dealt with as a composite, homo geneous element. The transmission of water vapor as outlined is based on the assumption of a diffusion process. The possibility of vapor being transferred as part of a moving air stream has thus far been ignored, except in Example 1 .in which it is implied that the air circulation on either side of the wall will be sufficient to eliminate surface film resistances to vapor flow. Differences .in total pressure of the air may result in a transfer of vapor with air, aug menting and at times over-riding the effects of the flow produced by vapor pressure gradients alone. This can be particularly, important in the trans fer of vapor through cracks and pinholes or through air-permeable building constructions. This means of vapor transfer is similar to that of transfer of heat by air leakage in and through building constructions, requiring for purposes of calculation information on the nature and amount of the air leakage. It will seldom be important in constructions without air spaces and having parged or plastered surfaces. It may, however, be an important means of vapor transfer through constructions lacking in air tightness, and may contribute to condensation difficulties, since the mechanism of condensa. tion is not dependent upon the way in which the vapor is transferred. PERMEANCE AND TESTING The simplest method of finding the permeance of a specimen is to seal it over the top of a cup containing desiccant or water, placing it in a con trolled atmosphere, and weighing it periodically. The steady rate of weight gain or loss is normally the water vapor transfer. When the cup contains a desiccant the procedure is called the dry-cup method and when the cup contains water, the wet-cup method. ' Usually the outside atmos phere is held at 50 percent relative humidity, thus providing, in either method, substantially the same difference of vapor pressure, but the results obtained by the two methods on the same specimens are likely to be much different, the wet cup method producing the higher values. The relationship between these values can best be understood by reference to Fig. 3, which shows a typical variation of spot permeability with relative humidity at one particular temperature (isothermal conditions) for a material such as wood. The vapor permeability is shown to vary only moderately at low humidities, but to increase at an increasing rate as higher humidities are reached. The dry-cup test of this material carried out with 0 percent relative humidity one side and 50 percent on the other, will experience throughout its thickness, because of the variation in relative humidity, a variation in spot permeability. The average permeability . i* ji, is by definition (Equation 3), given by ~ , and since at a fixea temperature there is a linear relationship between vapor pressure and relative humidity, this expression can be seen to correspond to the mean height of the area under the spot permeability curve, between the appr' Moisture in Building Construction - , j Table 1. Permeance and Permeabilitt of Materials . to Water Vapor.: . : 213 Material Ais (still) - Insulation Cellular glass Corkboard : Corkboard # . Structural InsulatingBoard (vegetable, uncoated)- Mineral Wool (unprotected) . Wood Sugar Pine Plywood (Exterior type 3 ply D.F.), M in. Plywood (Interior type 3 ply D.F.), H in. Masonry . Concrete (1:3:4 Mix) Concrete (3* cored bloek wall; limestone agrgt.) Brick wall--with mortar--4 in. Tile wall--with mortar--4 in. Intbrior Finish Plaster on wood lath Plaster on metal lath-- Plaster on plain gypeuza lath (with studs) Gypeum wall board--plainrrfi in. Insulating wall board (uncoated)--Yt in. pPAaTintt"t*---- 2 c-"o-a*ts , Asphaltic paint on plywood Aluminum in varnish on wood . Enamels, brushed on smooth piaster Prttrtcri or Sealer* on insulating wall board Various Primer* -h 1 coat fiat paint on plaster ' Flat paint (alone) on insulating wall board Water Emulsions on insulating wall board Paint--Exterior, 3 coats __ # White lend tfc oU prepared paint on wood siding White lead-sine oxide 4 linseed oil on wood Per-, Permea* meance Perm ' j; bility Perm-inch 120. , 0.0 2.1-2.6 .9.5 20-50 116. 2*4 `S 92-73 73-0 100-45 40-x 100-30' 0.4-5.4 50-0 95-0 Lb. per 600 Bq ft PxPXBB AND FblTS I duplex sheet, asphalt laminae, aluminum/oU one ) side ' Saturated and coaled felt heavy roll roofing ' i tTi a*Pha2t laminae. Reinforced 30-120-30 Aa spwha,lt-saaturatedUPa>nadspcohaatlet-dsasth.,eoantheinagidpeagploesrsy aapnalt-saturated sheathing paper Impound asphalt felt _ '70 impound tar felt . 70 omgle sheet Kraft, double infused 16 Permeance-Perms dry cup 0.002 ( .j * Description is a guide only, and does not insure permeance. Methods: d--dry cup; w--wet cup: t--two temperatures: b--special cell; v--air velocity both sidea; average of four methods. .- . of ifv^ere.nc^ No*.7 also includes Bulletin* 22 and 25 of the Enjineerinp Experiment Station, Vniveretiy ^ includes data to be published by the Engineering Experiment Station, The Penntylvania rc^a^ve humidity limits. The average permeability as found.'for to: dry-wap conditions should therefore have the value mi . -'. Similarly or the wet-cup test between 50 percent and 100 percent relative humidity, 5Xa*ue should be fi2 It is not uncommon for these values for wood and ^od-fiber materials to be in the ratio of 1 to 3, or higher. (See Table 1.) tic ! averaSe permeability /Z for any other relative humidities at a parcurv JemPera^ure is given by the -mean height of the' area under the rve * spot permeability for the material at that temperature, between CHAPTER 10 1956 Guide 214 the appropriate limits of relative humidity. Only average permeabilities (or permeances) are measurable directly in practical tests. However, if several average permeabilities at different relative humidities are known, and can be plotted as for the wet-cup and dry-cup tests shown in Fig. 3, it is possible to construct,.by trial and error, a spot permeability curve which will satisfy the condition that the average height of the curve between the appropriate limits for each test must equal the value found in each test. Separate curves are required for each temperature so that a large number of permeance cup tests would be required to cover a range of con ditions of both temperature and humidity. Experience to date shows that the effect of temperature is quite moderate and. for some purposes, differences in temperature at which tests are run Em. 3. ncr Wet Cup Tests and the Spot Material such, as Wood . may be ignored. Corrections for temperature have been made with some success by the use of an equation based on activation energy6 which states: '* ' lufi BT . (8) where, in appropriate units, no " permeability at T = R = gas constant E = activation energy _ e = Naperian base of logarithms = 2.718 ThTrou=gahbtshoelutuesteemofptehraistuereq.uation, spot permeability curves for a variety tveimdepderoantulyretshactatnwboetecsotnssatrtudcitfefedrefrnotmtemapceurravteurfeosrcoannebteemrupne,rfarotumre,which E, the activation energy, can be evaluated. In this way it becomes pp8" 1 Moisture in Building Construction 215 sible to describe the permeability of a material reasonably completely from the results of as few as five single tests at carefully selected conditions. No method has yet been found, other than by direct testing for a particu lar set of conditions, of predicting the effective permeabilities for conditions of temperature gradient along.with a humidity (or vapor pressure) gradient, from data obtained under other conditions, even though this is the general situation in practice. A very considerable amount of information is available on the permeances and permeabilities of various materials, but these are frequently obtained at different conditions so that the results cannot be compared directly, nor do they often give a coverage of a range of conditions to permit construction of basic curves of spot permeability or permeance. Since dry-cup and wet-cup tests are much easier to carry out than tests at intermediate humidities, many of the data available have been obtained in this way. In the absence of data obtained from tests dupli cating the conditions of temperature and relative humidity in service the permeance of a piece of material may be judged adequately for many pur poses if it is tested by both dry and wet methods. It is obvious that any statement of permeance of a specimen should include the conditions of test. Method of test E96HS3T of the American Society for Testing Materials describes procedures for testing for water vapor transmission of materials in sheet form under five different test conditions. These include the drycup and wet-cup methods, based on 50 percent relative humidity outside the cup, at either 73.4 or 90 F, and a fifth condition at an elevated tempera ture of 100 F. with relative humidities of 0 and 90 percent on either side of the sheet. Standard T448m-49 of the Technical Association of the Pulp and Paper Industry covers the determination of water vapor transmission of paper and paperboard, and calls for the dry-cup method at 73.4 F., based on 50 percent relative humidity outside the cup. Unfortunately, there is no general agreement as yet to report results as coefficients of permeance, or of permeability where appropriate, as adopted m this chapter, or to use the same basic units. Test data are frequently reported in terms of weight transmitted per (unit area) (unit time). Such data may be called water vapor transmission data or WVT data and values are either high or low depending on the difference of vapor pressure chosen for the test. When this difference is known, WVT data can be converted to permeance, care being taken if conversion of the basic units (weight, area and time) is also required. The following formula applies: `where, WVT rating Permeance = ----------------- Ap WVT rating = weight of vapor transmitted, grains per (sq ft) (hour). Ap =-- vapor pressure difference in the test, in inches of mercury. Permeance is expressed in perms. (9) table 2 presents the conversion factors applicable to the commonly hsed units and test methods. Table 1 presents some data on typical building materials showing, in each case, the source and method and, where aPplicable, the thickness tested. Water-proofed building papers are listed in Federal Specifications UU-P*47, May 24,1948, according to water vapor resistance required as: 216 CHAPTER 10 1956 Guide Class A. For uses where a high degree of water vapor resistance is required. Class B. For uses where a lower degree of water vapor resistance and of water resistance is required. Class C. For uses where a moderate degree of water resistance is required. Class D. For uses where low resistance to water vapor is required. It may be noted that a paper may be water-proof, i.e. possess water re sistance, and still have low water vapor resistance. Detail requirements in these specifications are given as follows, the specified WVT Test being a dry method at 73 F: Class A paper shall have a minimum tensile strength in each direction of either 35 Table 2. Conversion Factors for Vapor Transfer Units Mulctflt Numbed of WVT Units to Obtain j, grams (24 hrs) (sq m) grains (hr) (sq ft) . ' BTWD* (24 hrs) (sq m) Ky method*' S**118 (hr) (eq ft) Perms by same method' by same method* method C & D, 90^ F method E, 100 F Nominal Test Conditions 16.7 ' 1 0.0597 1 0.144 0.0840 0.0344 2.41 1.41 0.675 % Relative Humiditt on the Two . Sides op Specimen: ' , . \ Method Temperature-F Id cup A B C D E 73.4 73.4 90 90 100 0 100 0 100 0 Data obtained by one method cannot be reliably converted to another method. Outside cup 50 50 50 50 90 Tloo ccoonnvveerrtt (2g4ra^ms-(-s---q--m----)---(--m---m----- Hg) to perms multiply by 1.62. . . ; > `v' >r lb per inch width, or 20 lb per inch width, as specified in the invitation for bids. Paper of both strengths shall have a minimum water resistance of 24 hr, and a maadjfc; mum water vapor permeability (WVT) of 4 grams per (square meter) (24 hr) 0.57C6lapsesrmB. paper shall have a minimum tensile strength in each direction of either 35 . lb per inch width, or 20 lb per inch width, as specified in the invitation for bids.,-." Paper of both strengths shall have a minimum water resistance of 16 hr, and a maxtyj*. mum water vapor permeability (WVT) of 6 grams per (square meter) (24 hr) 'i&i.C 0.864 perm. _ , Class C paper shall have a minimum tensile strength in each direction of either 355" lb per inch width, or 20 lb per inch width, as specified in the invitation for bids/./' Paper of both strengths shall have a minimum water resistance of 8 hr. oilLl Class D paper shall have a minimum tensile strength in each direction of 20 lb yflf inch width. The paper shall have a minimum water resistance of 10 min., a mini'- " \ mum water vapor permeability (WVT) of 35 grams per- (square meter) (24 hr) 5.04 perms. . V? ;V Moisture in Building Construction 217 . VISIBLE CONDENSATION , Just as moisture collects on the outer surface of a glass of cold water, so does it also condense on other cold materials. In winter, visible con densation may collect bn cold closet walls and attic roofs and is commonly observed on frosted window panes. Although condensation, if liquid, may enter an unpainted surface as fast as it forms and thus be unseen, any condensation on a visible surface will for convenience here be called visible condensation to distinguish it from concealed condensation. Within residences and public buildings, visible condensation occurs in winter and may damage decorative finishes and window sash. . Interior visible condensation occurs when any surface is colder than the dew point of the near-by air. The temperature of any such surface-- wall, roof, or glass--is dependent upon the air temperature inside and out- F .ig 4. Relative Humidity at Which Visible Condensation Will Appear on Inside Surface side the building and the heat transfer coefficient U of the surface structure. Based on a value of 1.65 for the inside surface conductance, Fig. 4 shows the relative humidity in a room at 70 F when visible condensation will appear at various 17-values. The curves for single and double glass at their usual U-values are included. It should be noted that 17-values as commonly used are an average for a large area within which there may be spots, such as the studs in an insulated wall, where the transmittance is higher. The inside surface temperature of a wall will, in general, be lower at the bottom due to such things as stratification of inside air and the ef fects of air leakage and of convection in walls with air spaces. Since con densation seeks the coldest spot, values from Fig. 4 can be applied only with caution.. As a result, the limit of relative humidity for a non-homogeneous wall is lower than might be inferred from its average U-value. Normally, glass is the most likely spot in a heated room for appearance of condensation, but an uninsulated wall surface shielded from radiation by furniture, may be equally cold. In some cases where condensation is barely avoided, the surface, being but little warmer than the dew-point tempera- 218 CHAPTER 10 1956 Guide ture, is exposed to moisture damage--such as swelling, mold or discolora tion. . . . Visible condensation may occur also in summer. It is often seen on basement concrete walls and floors which are cooled by the earth and which being massive, tend to hold a constant temperature from day to day while the weather dew-point temperature rises. When no water .vapor is re leased in the space, the dew point tends to equal that of the outside (though . it is likely to, lag when there is slight ventilation). At times the dew-, point temperature rises above the temperature of walls and floors and condensation results. If the basement is decorated the trouble may be perious.. As an operating problem, the solution may be to reduce ventila tion at times of high weather dew point, to warm the.walls, or to dehumidify Fig. 5. Relative Humidity in Dwellings the space. Warming the walls, a slow process at best, is generally accom plished in favorable climates by excess ventilation. In a climate having low temperature at night, it may be feasible to ventilate only at night and thus reduce the moisture content of hygroscopic materials which will then act as a desiccant to retard the dew-point rise during the day. In base ment walls and floors insulation should be applied in the concrete or on its outside. Insulation placed on the inside of such walls eliminates visible condensation but fosters concealed condensation. The control of the latter will be discussed. A practical and fully effective technique for such control has, however, not been developed. Usually, sub-surface dwellings should be designed for occupancy and should be dehumidified. A similar situation is seen in dwellings with concrete floor slabs laid on the ground where such slabs are not a part of the heating system. In a northern climate where high dew-point temperatures occur in summer, con densation or very high relative humidity may damage rugs which are them selves contributors to the trouble since they reduce the floor slab tempera ture. Slab floors above grade are not so serious a problem as floor slabs on grade but their response to air temperature change is slow. Faster warm ing is accomplished by the removal of rugs and abundant ventilation a proper times. In their design, floor slabs should have as low specific heat and as high thermal resistance as is consistent with other requirements. Suitable insulation below the slab, especially well drained gravel, will help Moisture in Building Construction 219 somewhat. A top surface cover of insulating value that is unaffected by water on its lower side would be desirable in the less favorable northern climates. The avoidance of interior visible condensation is partly a construction and partly an operating problem. It is accomplished by reducing the in terior dew-point temperature or by raising the surface temperatures that are below the dew-point, or both. The dew-point temperature may be lowered by giving attention to the sources of the moisture, and in winter, may be controlled by ventilation, or possibly by some moisture absorption process. The temperatures of the inside room surfaces in winter may be increased by adding insulation to outside walls, by double glazing of win dows, by circulating warm air over the surface, or perhaps by direct heating of the surface. The most expedient method of overcoming a surface con densation difficulty will depend upon special conditions surrounding the problem. CONCEALED CONDENSATION IN HEATED BUILDINGS Water vapor produced in a building necessarily raises the vapor pressure above that outside thus providing the force that causes its diffusion into exterior walls. T-he,amount of vapor pressure rise in the building depends on the amount of vapor produced and inversely on its chance to escape. The resulting balance may be expressed in terms of relative humidity if the inside temperature is 70 F. The relative humidity in heated buildings covers nearly all of the possible range. In zero weather it may be only 10 percent in an office, and 85 percent in an industrial plant where humidifi cation is required for a process, or where vapor release is incidental to a process. In residences the relative humidity in cold winter weather ranges from 10 percent to 60 percent, the latter figure applying to a very small, crowded and unventilated dwelling. A 40. percent level is considered representative of a substantial number of modem tightly constructed small houses although the average house relative humidity is probably below 25 percent. Surveys in residences show that the relative humidity increases as would be expected in warmer weather. Fig. 5 represents the results of one such survey. When water vapor is allowed to enter a wall and condensation occurs on its outer cold elements, it appears as frost or liquid. If the weather temperature rises frequently, frost melts and becoming liquid, is likely to penetrate capillary materials like wood, or run down when the surface is non-absorbing or is already saturated with water. In weather that is con tinuously cold for a long period, the frost may build back into a cavity or fibrous insulation and, when it reaches a warmer plane, will run to lower, cooler levels where it forms a mass of ice. Water seepage to the weather side may occur harmlessly in masonry walls when the weather is above freezing but water seepage into the building must obviously be avoided. In typical frame construction with wood sheathing which has large water absorbing capacity, seepage is rare and occurs only after a long period of steady cold weather. More generally, moisture accumulates in wood sheathing and siding through the colder months and reaches a peak in late winter, after which the drying of spring and summer completes the annual cycle. The average winter temperature and its duration are factors in the condensation problem. In Fig. 6 the map of the United States is divided in to condensation zones based on winter weather conditions. The solid lines separating the zones follow state lines, and are those recommended by the 220 CHAPTER 10 1956 Guide Housing and' Home Finance Agency for the guidance of owners, builders, and architects.14 The dotted lines are the -- 20 F, 0 F, and +20;F isotherms' of winter design temperature taken from Fig. 1, Chapter 12. It will be noted that there is reasonably good correlation between the zones deter mined by the two sets of lines. Zone I roughly includes those areas where the design temperature is -- 20 F or colder; zone II those for which the design temperature is zero to --20 F, and zone III those at zero and wanner. Within each zone, similar degrees of condensation trouble are to be expected, and similar corrective measures apply. In roofs, the condensation problem is much the same as in walls. The roof covering may be even more resistant to the escape of vapor than wall . Fig. 6. Condensation Zones in the United States (Zones Include Areas with Design Temperatures about as follows: Zone I, --20 F and lower: Zone 11. 0 F to -- 20 F; and Zone 111, above 0 F. Note that cross hatched areas are outside of Zones I and III.) coverings such as paint; and while paint is likely to be ruptured by exces sive moisture, no such relief occurs in roofs. Thus roofs furnish con spicuous examples of rapid decay in lumber. . In crawl spaces over uncovered damp ground, a large water evaporation sometimes occurs and causes condensation on the outer ends of floor joists and other members that are below the floor line and near to the outside. Water vapor from the crawl space may also enter walls, be transported by rising air in a stack effect, and even reach the attic by this route when the wall structure permits. Ventilation, as discussed later in this chapter, is an important correction factor in these cases. Insulation in a wall or roof reduces heat loss and lowers the temperature of the outer elements of the structure, thus increasing the possibility of condensation if the vapor path to the cold surface is not blocked. Since low vapOr resistance is a characteristic of fibrous insulation, the needed vapor resistance must be provided by other means. It is to be noted that, Moisture in Building Construction 221 in typical residential conditions, condensation does not occur in fibrous insulation itself, except when frost has formed on sheathing and gradually built backward among the fibers. Wet insulation may result from this condition or from liquid condensation seeping down from a higher level. CONTROL OF CONCEALED CONDENSATION An excessive accumulation of moisture in walls (or roofs) can be pre vented by one or more of the following measures: (1) provide a vapor bar rier to limit vapor entrance into the wall,. (2) ventilate the building to reduce vapor pressure therein, (3) ventilate the wall cavity to remove vapor that has entered. 1. Vapor Barrier. A vapor barrier is the principal and most obvious correction, but each measure is more effective if aided by the effect of another. In habitations, some ventilation of the living space, either inci dental or planned, is necessary. Also, a small amount of cavity ventilation is essential in cases where the vapor inflow is not completely stopped and the moisture storing capacity of the outer wall elements is slight. This applies to some prefabricated designs using metal siding. . Vapor barrier sheets are often built into the wall near the warm surface. In wood frame walls they may be applied to the inside surface of the studs. They are sometimes attached to the warm side of the insulating materials, or they may be applied on the cold side of plaster base materials. Special designs may be attached like wall paper to the inside of the wall, when satisfactory from the decorative view point. Sheet barriers often contain asphalt as the vapor resisting ingredient; metal foils, so placed that they are not too cold, may also be used. ' The interior wall board or finish material may itself be vapor resistant, or a barrier coating may be applied to its concealed side when that side will not be too cold. The interior finished surface may be coated with a suit able paint having the required vapor resistance and also serving as the decorative finish, or it may be covered by another coat. A paint coat on the interior finish, though of adequate resistance, is not likely to be so effective as a sheet barrier properly applied during the wall construction. This applies especially to houses of more than one story having cavities in ceilings which open into the outside walls. Such cavities allow vapor entering the ceiling to diffuse or be transported to the cold- areas. Stoppage of this path is difficult, requiring normally the painting of the ceiling as well as the walls. Similar treatment may be required on internal partitions, or at least the first stud space adjacent to the cold wall. The necessary barrier resistance depends on a number of factors. When the vapor flow occurs in annual cycles as in heated buildings, the require ment is not so exacting as it is for a cold storage room where there is no chance for drying out an accumulation of moisture. In a heated structure covered on the outside with materials highly resistant to water vapor such paint or roll roofing, the winter season is a time of moisture accumulation m the cold outer elements and their safe moisture holding capacity is an important factor in determining the barrier requirement. A house without sheathing requires a better barrier; and a prefabricated design with only a sheet of metal outside of insulation requires very high barrier resistance, t he interior vapor pressure and the length and severity of the winter are mso important. . For typical frame dwellings with wood sheathing and siding in the north ern United States, a barrier permeance of one perm or less has been found 222 CHAPTER 10 1956 Guide satisfactory. There are cases, however, in residential construction where a one perm barrier would not be adequate and there are also many industrial applications in which a very much higher vapor resistance is required. In any event, the choice of an adequate barrier implies that its permeance be definitely established. The usually accepted test procedure for this pur pose is a dry method at a temperature of 70 F to 80 F. If obtainable at reasonable cost (including good application), a barrier better than required should be chosen for any construction. Despite the theoretical possibility of safely discharging some vapor through a wall, a higher than minimum permeance is hot preferred. ; An exact statement showing which buildings require a vapor barrier is not readily formulated. However, in view of . the distressing results its Fig. 7. Water Vapor Balance in a Dwelling (Vapor Barrier, 1 perm; Wall and Ceiling Area 2000 bq ft Insulated) omission may bring, it is tentatively recommended that the walls of every well constructed modem dwelling include a vapor barrier when the con struction includes any material that would be damaged by moisture or its freezing. This applies to all condensation zones in Fig. 6 when the V value for the wall is lower than 0.25 Btu per (sq ft) (hr) (F deg), and it applies in Zone I and Zone II to walls of higher transmittance. In applying vapor resistance to a wall, there are certain fundamental principles which should be followed. First, the vapor barrier should be placed as near to the warm surface of the wall as practicable. Second, it should be continuous with no direct openings through the barrier. Good workmanship and application are very important. Workmanship that leaves two openings through the barrier, or around its margin, at different levels, connecting air spaces at only slightly different temperatures, leaves a path for thermosyphon air rotation which will transport large amounts of water vapor from the warmer space to the colder. If a membrane barrier is used back of the plaster or interior finish, its joints should be made over some solid framing member, and not between the studs or in similar places. Usually a two-inch lap over a framing member will make a sufficiently tight joint when the interior finish is applied. Such a lap, however, without backing would not be adequate. Barriers attached to the warm side of Moisture in Building Construction 223 insulation should form a continuous unbroken membrane over the entire insulated area. Edges should be lapped over framing members; ends of strips should be fastened by lapping over plates or headers. All openings for electrical fixtures and joints around window and door casings should be carefully sealed. Holes accidentally made in the barrier should be sealed. 2. Ventilation of Living Space. The second measure listed for the control of concealed condensation is ventilation of the house. This measure is obviously necessary as an accompaniment to a vapor barrier since, if the barrier blocks entrance into the walls, the water vapor must be removed 1 :. Table 3- Recommended Good Practicei4-Loft and Attic Ventilation* Flat Roof--Slope Less than 3 Inches in 12 Inches Condensation Zone 1: Total net area of ventilation should be Hoothb,distributed uniformly at the eaves pitta a vapor barrier in the top story ceiling. Free circulation must be provided through all spaces. Condensation Zone II and III: Same as for Zone I. - Gable Roof--Slope oveb 3 Inches in 12 Inches Condensation Zone I: Total net area of at least 2 louvers on opposite sides located near the ridge to be Hoothb pitta a vapor barrier in the top story ceiling, ' ' . Condensation Zone II: Same-ventilation as for Zone I. A vapor barrier is not considered necessary. - Condensation Zone III: Same as for Zone II. ' Hip Roof . Condensation Zone I: Total net area of ventilation should be Hoothb with Hoothb distributed uniformly at the eaves and }6oothb located at the ridge with all spaces interconnected. A vapor barrier should *lso be used in the top story ceiling. , Condensation Zone II: Same ventilation as for Zone I. A vapor barrier is not considered necessary. Condensation Zone HI: Same as for Zone II. Gable ob Hip Roof--With Occupancy Contemplated Condensation Zone I* Total net area of ventilation shoud be Hoothb with Hoothb distributed uniformly at the eaves and J6oothb located at the ridge with all spaces interconnected. A vapor barrier should also be used on the warm side of the top full story ceiling, the dwarf walls, the sloping part of the roof, and the attic story ceiling. :^ Condensation Zone II: Same as for Zone I. ' Condensation Zone III: Same as for Zone I except that a vapor barrier is not considered necessary if insula* tion is omitted. * It b recognised that in many areas increased ventilation may be desirable for summer comfort. For winter comfort, insulation is recommended between a living space and a loft or attic ventilated at these rates. HefeTS to area enclosed within building lines at eave level. The zone numbers refer to Fig. 6. . by other means. No great volume of air change is necessary, however, and normal infiltration alone is frequently all that is required in winter weather. The effectiveness of ventilation is shown in Fig. 7, which also shows the small amount of water vapor escaping into the barrier-equipped, well-in sulated walls and ceilings (2000 sq ft) of a typical small dwelling, the floor being neglected. Evidently, ventilation of 2000 cu ft per hr will remove 21 lbs of vapor per day with the relative humidity at 40 percent, while at the /o<?e 1-0 lbs escapes into the structure. The total vapor production lb) is a typical amount. Double glass will be barely safe from visible 2nonenSat'n 38 be seen in Fig. 4. By reference to Chapter 6, r300 cu ft per hr appears to be near the minimum for odor control, and , ebtdation would have to be higher when cooking is done. By reference Chapter 11, it appears that usual infiltration will normally supply the ecessary air change, but that supplementary ventilation may be neces- 224 CHAPTER 10 1956 Guide sary in kitchen and laundry for proper vapor control and for the reduc tion of peaks in relative humidity which would otherwise occur in those areas. ' . 3. Ventilation of Structure. The third measure listed for the control of concealed condensation, ventilation of the structure itself, is effective in certain cases especially as a supplement to warm side vapor resistance which is considerable but not of itself fully adequate. Air from outside is used. The vents must be shielded from the entrance of rain and insects. Attics and crawl spaces may be considered as parts of the structure, and for these portions ventilation is practically a necessity. Attic ventilation has long been an established practice but its effectiveness is likely to be diminished by the newer practice of adding insulation to ceilings. In sulation requires added ventilation which in turn necessitates adequate insulation. The recommended ventilation shown in Table 3 for dwellings14 is based on such insulation. The net area refers to the total of all openings free from obstructions. The use of louvers and 8-mesh screen (usually recommended) requires a gross area 2.25 times that listed. In Zone I of Fig. 6 a ceiling vapor barrier is recommended for all constructions. It is also necessary that stray openings from walls into the attic, or around a loose fitting attic door be avoided. The stack effect allows a large inflow of warm air from the dwelling, transporting much vapor to a danger area. More desirable ventilation of the house can be arranged. Crawl spaces under dwellings where the earth is damp and uncovered require a high rate of ventilation. At least four openings, one at each comer, as high as possible, should be provided.14 Their total net area may be calculated by the formula: 2L A_ 100 + 300 (10) where: . L = the perimeter of the crawl space, linear ft. A = the area of the crawl space, square feet. a = the total net area of all vents, (or the gross area if a 4-mesh screen is used), square feet. ' This ventilation is usually sufficient but cools the first floor so much that insulation is needed. A better treatment is a cover on the damp ground. This cover may be a concrete slab, or merely heavy roll roofing laid on a graded surface with its edges lapped 2 in. (but not necessarily cemented). With this barrier, the vent area may be reduced to 10 percent of that calculated by Equation 10. In building walls, cavity ventilation can be applied in a moderate climate as the sole vapor control system. In general, however, air passages vn walls designed to remove an unrestricted vapor supply are unduly large and may waste considerable heat. On the other hand, a barrier as the only control measure would, in some cases, require so high a resistance as to be impractical. Ventilation of the structure in conjunction with a vapor barrier, is a procedure with important applications, but its general utility has not been fully investigated. Ventilation is most effective when each structural space has a clearly defined air passage with an inlet and outletIn walls a small thermosyphon effect may be utilized by locating one vent- at the bottom and one at the top of each space. ,. Moisture in Building Construction 225 The best time to vapor-proof a building is during its construction. After a building is completed, ventilation of the occupied space is the most easily applied of the three basic control measures. Paint that is chosen for its low vapor permeance can be applied as a barrier on the interior with good results, care being taken that all areas, including parts of partitions and ceilings which offer an indirect vapor path to the cold wall, are covered. Ventilation of the wall cavity is effective in certain cases especially to sup plement the foregoing measures. When such venting is required, each cavity space isolated by framing should be separately vented with an inlet and outlet judiciously placed, to accomplish proper air change. CONDENSATION IN COOLED STRUCTURES Water vapor is sometimes an even greater problem in cooled structures than in those which are heated, but the basic facts of its migration and condensation on cold surfaces are the same. Refrigerators, cold pipes and cold vessels all require insulation and should be provided with a vapor barrier. The barrier, as always, should be placed on the warm side of the insulation and as close as possible to the warm surface of any enclosure. It resists the movement of water vapor toward the colder parts of the structure, and its job is even more exacting than that required in residential construction. In the case of an insulated cold pipe line, the process is likely to be uninterrupted for years and there is no chance for vapor that enters the insulation to dry out periodically. Also, no vapor can escape from the cold side, if this is a metal (vapor tight) pipe. For such an appli cation vapor control requires insulating material that is itself very highly resistant to water vapor or a coating whose permeance is the minimum obtainable, not over 0.1 perm. Metal coverings are desirable but difficult to apply. ` Similar considerations apply in the case of cold rooms whether con structed inside a heated building or as a separate building. In the latter case, cold rooms operating above freezing provide some periods of vapor reversal in winter but such drying can be of little help. Refrigerators, however, if lined with cement or other vapor permeant material, will allow slight amounts of vapor to pass and to that extent reduce the accumulation of moisture that may have penetrated the barrier. While this is helpful, emphasis must be placed on an adequate warm side barrier not greater than 0.1 perm. Summer air cooling for comfort does not involve serious vapor problems and vapor control measures are not essential. Normally the cooled air is little, if any, colder than the dew-point temperature of the outside at mosphere and there are no areas of condensation. However, the interior vapor pressure is often below that outside and therefore, vapor, which diffuses inward, adds to the cooling load. Vapor barriers in walls installed for Winter needs, are a help in reducing this element of the cooling load. REFERENCES 1 Research in Home Humidity Control, by S. C. Hite and J. L. Dray (Purine University, Bnyineeriny Experiment Station, Research Series No. 106, November 1948). * Permeance Measurement Improved by Special Cell, by F. A. Joy and E. R. Queer (A.S.H.V.E. Trans actions, Vo). 55, 1949, p. 377). , * Water Vapor Transfer Through Building Materials, by F. A. Joy, E. R. Queer and R. E. Schreiner {Penn sylvania State College, Engineering Experiment Station Bulletin No. 61, December 1948). 4 The Diffusion of Water Vapor Through Various Building Materials, by J. D. Babbitt (Canadian Jourof Research, Vol. 17, February, 1939, p. 15). * Diffusion In and Through Solids by R. M. Barrer (Cambridge Press, 1951). <V'W 226 CHAPTER 10 1956 Guide y Remedial Measures for Building Construction, by L. V. TeesdaJe (Report R1710 of V. S. Forest Products Laboratory 1947). - 1 Methods of Moisture Control and Their Application to Building Construction, by F. B. Rowley, A. B. Algren and C. E. Lund (University of Minnesota, Engineering Experiment Station Bulletin No. 17). 8 The Relation of Wall Construction io Moisiurt Accumulation in Pill-Type Insulation by Henry J. Barre {Iowa State College of Agriculture and Mechanic Arts Agricultural Experiment Station Bulletin No. 271,1940). '8 Moisture Migration: A Survey of Theory and Existing Knowledge, by P. F. McDermott (Refrigerating Engineering, August 1941, p. 103). . ' 'p Permeability of Paint Films to Moisture, by R. I. Wray and A.- R. Van Vorst {Industrial and Engineer ing 1C1 hWeamteisr trVyaVpoorl.T2ra5,nspm. 8is4s2i,on19o33fB). uilding Materials Using Pour Different Testing Methods, by R. R. Britton and R. C. Reichel, (U. 8. Housing and Home Finance Agency Technical Bulletin No. 12, January 1950). 11 Water-Vapor Permeability of Building Papers and Other Sheet Materials, by E. R. Bell, M. G. Seidl, and N. T. Krueger (A.S.H.V.E. Transactions, Vol. 57, 1951, p. 287), t* Value from unpublished tests of Pennsylvania State College Engineering Experiment Station. 14 Condensation Control in Dwelling Constructions (U. S. Housing and Home Finance Agency, 1949). BIBLIOGRAPHYXilUA/l V/ VJ a.a.------------- MoistureCondensation in Building Walls, by H. W. Wooley (Notional Bureau of Standards, ReportBMS6 3 December 14, 1940). .- Condensation of Moisture and Its Relation to Building Construction and Operation, by F. B. Rowley, A. B. Algren and C. E. Lund (A.S.H.V.E. Transactions, VoL 45, 1939, p. 231). A Theory Covering the Transfer of Vapor Through Materials, by F. B. Rowley (A.S.H.V.E. Transac A Theory v^ovenug uc ........-- _ tioWnNSs9im,, VVulootall..n44e55o,,u11s9933H99,,eppa..t 55a44n55d)). Vapor Transfer Characteristics of an Insulating Material,, by F.,, G. Hechier., 3. R. McLaughlin and E. R. Queer (A.S.H.V.E. Transactions, Vol. 48, 1942, p. 505). /' Comparative Resistance to Vapor Transmission of Various Building Materials, by L. V Teesdale Comparative rtesistaucv iv * 0p%-______ _______ _ " ~ " cm(.A..SPS.e.Hrm.Vis.Esi.blTerRaneslaatcivteionHsu,mViodli.tie49s, 1in943H, upm. 1id24if)i.ed Buildings, by Paul D. Close (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, December, 1939, p. 766). Condensation Within Walls, by F. B. Rowley, A-. B. Algren and C. E. Lnnd (A.S.H.V.E. Transactions, Condensation ttivuiu - - -- ----------- . . Volt..P44h44y,,s11ic99s3388o,, fppC.. 9o955n))d..ensation in Buildings, by J. D. Babbitt 0u...U....t.l.i.n...*.N.. o. "2, National *R --tzm--rcIh, fCT nouuDnfcH^il, of.f royaiva vnmoo^,,,, _____ _ CiannWaadodaoad)). Handbook (Forest Products Laboratory, United States Department o.f A'..g..r..i.c..u...l.t.u...r.e.. , 1940). Studies of the Physical Properties of Hardened Portland Cement Paste by T. C. Powers and T. L. Brown- yard (Journal, American Concrete Institute, Vol. 18, No. 8, April 1947, p. 933). - Experiments on the Freezing of Certain Building Materials by W. N. Thomas (FutWinp Research, Tech nicaMl oPiasptuerreNMoi.gr1a7t,ioHn.Min.Sa.OC.lTosLeodn,dGonu,ar1d9e3d8).Hot Plate by J. A. Paxton and N. B. Hutcheon (A.S.H.VJ2, . TraMnosavcemtioennst ,oVf oWl.a5te8r, 1in952S,,opil. D30u1e).to a Temperature Grad.ient by C. G. Gurr, T. J. Marshall, and J. T. Hutton {Soil Science, Vol. 74,.No. 5, November, 1952, p. 335). . * Fundamental Similarities Between Electro-osmotic and Thermo-osmotic Phenomena by H. F. Winter* korn (Proceedings 87th Annual Meeting, Highway Research Board, Vol. 27, 1947, p. 443). Performance of Desiccants in the Dry Pan Test for Water Vapor Permeance of Membranes by S. C. Chang and N. B. Hutcheon (Canadian Journal of Technology, 31, September, 1953, p. 175-192.) Fundamental Considerations in the Design of Exterior Walls for Buildings by N. B. Hutcheon (Technical Report No. 13, D.B.R., National Research Council of Canada, 1953). chapter n INFILTRATION AND VENTILATION Causes of Infiltration, Infiltration Due to Wind Pressure, Infiltration Due to Temperature Difference, Sealing of Vertical Openings, Infiltration Meas urement, Natural Ventilation, Wind Forces, Temperature Difference Forces, Heat Removal, Effect of Unequal Openings, Combined Wind and Temperature Forces, Types of Openings, General Ventilation Rules, Ventilation of Animal Shelters, Garage Ventilation Infiltration is the air leakage through cracks and interstices, around windows and doors, and through floors and walls. Its magnitude depends on the structural design, workmanship, and condition of the building. The rate of infiltration cannot be controlled by the inhabitants of the building to any considerable-extent. Natural ventilation is the controlled displace ment of air through openings, such as windows, doors and ventilators as well as through combustion heating devices. CAUSES OF INFILTRATION The air leakage which takes place through various apertures in buildings must be estimated in heating and cooling calculations and enough heating or cooling capacity provided to offset the heat lost or gained by the air leakage. The rate of air flow into and out of a building depends on the magnitude of the pressure difference between the inside and outside of the structure and on the resistances presented to this pressure difference. The pressure difference exerted on the building walls by the air may be caused either by wind or by a difference in density of the . air inside and outside the building. The effect of the wind depends on the interrelation of the speed and direction of the wind and the exposure of the building. The effect of the difference in the density of the air depends on the magnitude of the inside-outside temperature difference, the height of the rooms, the shape of the openings, and their elevation in the room or building. The effect of the difference in density is often referred to as the chimney or stack effect. The pattern of air flow through any part of the structure de pends on both the pressure difference and the openings. In general, when the pressure difference is the result of wind pressure, air will enter the building through openings in the windward walls and leave through open ings in the leeward walls or through ventilating ducts in the roof. When the pressure difference is caused by the inside-outside temperature differ ence the flow will be along the path of least resistance from inlets at lower levels to outlets at higher levels in a heated building or in the opposite direction for an air-conditioned building. . An exact estimate of the amount of infiltration under design conditions Is difficult to make. The complicating factors include (1) variations ln building construction, particularly as to width of crack or size of openings through which air leakage takes place; (2) the variations in J'ond velocity and direction; (3) the exposure of the building with respect air leakage openings, and with respect to adjoining buildings; (4) the 227 228 CHAPTER 11 1956 Guide variations in outside temperatures which influence the chimney effect; (5) the relative area and resistance of openings on the windward and leeward sides, and on the lower floors and on the upper floors; and (6) the influence of a planned air supply and the related outlet vents. Tight construction is essential for preventing large heat loss due to infiltration. INFILTRATION DUE TO WIND PRESSURE The wind causes a pressure to be exerted on one or two sides of a building. As a result, air comes into the building on the windward side through cracks or porous construction, and a similar quantity of air leaves on the leeward side through like openings. In general, the resistance to air movement is similar on the windward to that on the leeward side. This causes a building up of pressure within the building, and a lesser air leakage than that ex perienced in single wall tests as determined in the laboratory. It is assumed Table 1. Inwltration Through Walls* Expressed in cubic feet per square foot per hour Type op Wall Wind Velocity. Miles per Hour 6 10 15 20 25 30 8yi in. Brick Wallb_ J Plain_________ 2 ) Plastered1-- 0.02 4 0.04 8 0.07 12 0.11 19 0.16 23 0.24 /Plain 13 in. Brick Wallb__< Plastered'-- (.Plastered^-- 1 0.01 0.03 4 0.01 0.10 7 0.03 0.21 12 0.04 0.36 16 0.07 0.53 21 0.10 0.72 Frame Wall, with iath and plaster'.. 0.03 0.07 0.13 0.18 0.23 0.26 * The values given in this table are 20 percent less than test values to allow for building up of pressure in rooms, and are based on test data reported in the papers listed in chapter footnotes. b Constructed of porous brick and lime mortar--workmanship poor. 0 Two coats prepared gypsum plaster on brick. d Furring, lath, and two coats prepared gypsum plaster on brick. 9 Wall construction: Bevel aiding painted or cedar shingles, sheathing, building paper, wood lath and three coats gypsum piaster. that actual building leakages, owing to this building up of pressure, will be 80 percent of laboratory test vsdues. While there are cases where this is not true, tests in actual buildings substantiate the factor for the gen eral case. Mechanical ventilating systems are frequently designed to produce positive or negative pressures in an enclosure, which are greater or lower than prevalent wind pressures. In such designs, if the specified rate at which air is to be supplied to, or removed from, the enclosure by posi tive means, exceeds the infiltration rate, it is common practice to use the greater value in determining the heating capacity to warm the outside air. Infiltration Through Walls Data on infiltration through brick and frame walls are given in Table l-1 The brick walls listed in this table are walls which show poor workman ship, and which are constructed of porous brick and lime mortar. For good workmanship, the leakage through hard brick walls with cement time mortar does not exceed one-third the values given. These tests indicate that plastering reduces the leakage by about 96 percent; a heavy Infiltration and Ventilation 229 coat of cold water paint, 50 percent; and three coats of oil paint carefully applied, 28 percent. The infiltration through walls ranges from 6 to 25 percent of that through windows and doors in a 10-story office building, with imperfect sealing of plaster at the baseboards of the rooms. With perfect sealing the range is from 0.5 to 2.7 percent; or a practically negli gible quantity, which indicates the importance of good workmanship in proper sealing at the baseboard. It will be noted from Table 1 that the infiltration through properly plastered walls can be neglected. The value of building paper, when applied between sheathing and shingles, is indicated by Fig. 1, which represents the effect on outside con struction only, without lath and plaster. The effectiveness of plaster properly applied is no justification for the use of low grade building paper, or of the poor construction of the wall containing it. Not only is it diffi- T" V,,,.ra Ttpes ,, Co,,,,,,c,,0,, cult to secure and maintain the full effectiveness of the plaster, but also it is highly desirable to have two points of high resistance to air flow with an air space between them. The infiltration indicated in Fig. 1 is that de- ' termined in the laboratory, and should be multiplied by the factor 0.80 to give proper working values. ' Window and Door Leakage There are two methods of estimating air leakage through window and door cracks, namely, (1) the crack method, and (2) the air change method. The crack method is generally regarded as being more accurate than the Mr change method, provided the variables, such as crack width and clear-' ance, can be properly evaluated. Crack Method The crack method is based on known air leakage factors for various types of windows, and widths of crack and clearance. The wind velocity and length of crack are also considered when the crack method is employed. Table 2. Infiltration Through Windows Expressed in Cubic Feet per Foot of Crack per Hour I'Wuin V eloott, Miles peb Hour Try* or Window Remarks .__ -6 10 15 20 25 30 -- Around frame in masonry wall--not calked**........... Around frame in masonry wall--calked". ................. Around frame in wood frame construction............. Total for average window, non-weather-stripped, 2 8 14 20 27 35 23456 6 11 17 23 30 Wood Windows (Un locked) He-in. crack and %4-ins clearance.6 Includes wood frame leakage.................................. ........ J Ditto, weatherstripped........................................................ Total for poorly fitted window, non-weather- stripped, %s-in. crack and Hs-in. clearance. Includes wood frame leakage.................................... Ditto, weatherstripped.:.................. ..................... 7. 4 27 Double-Hung Metal Windows* Non-we&therstripped, locked.......... Non-weatheiatripped, unlocked.'.. Weatherstripped, unlocked.. 6 Rolled Section Steel Bash Windows* Industrial pivoted, He-io. crack*................ Architectural projected, Hs-in. crack}*... Architectural projected, %4-ta. crack-.. Residential casement, crack}......... Residential casement. Hs-in., crack1......... ----------------* ****mTi nmiectcd. H4-1 `8 21 13 39 24 59 36 80 104 49 63 69 111 154 199 249 19 34 61 71 92 43 47 70 96 125 154 74 104 137 170 19 32 46 60 76 103 36 52 18 176 62 88 33 244 86 116 47 304 112 152 60 372 139 182 74 32 10 52 18 76 too 128 26 3 48 24 38 54 72 92 - --------- 1------- --------- Hollow Metal, vertically pivoted window*............................................ . 30 88 145 186 t 221 242 * The values given in this table, with the exception of those for double-hung and hollow metal windows are 20 percent less than test values to allow for building up of pressure in rooms, and are based on test data, rep*o*rTtehdeinvatluheespgaipveerns floisrtferadmine clehaakpatgeer faoroetnpoetrefso.ot of sash perimeter, as determined for double-hung wood windows. Some of the frame leakage in masonry walls originates in the brick wall itself, and cannot be pre vented by calking. For the additional reason that ealking is not done perfectly and deteriorates with time, it is considered advisable to choose the masonry frame leakage values for calked frames aa the average deter min*eTdhbeyftiht eofctahlekeadvearnadgenodno-ucballek-ehdutnegswtso. od window was determined 69 Mfr-in. crack and clearance by measurements on approximately 600 windows under heating season conditions. -- - d The values riven are the totals for the window opening per foot of sash perimeter, and include frame leakage and so-caUed elsewhere leakage. The frame leakage values included are for wood frame construction, but apply aa well to masonry construction assuming a 60 percent efficiency of flame calking. 1 WA i&nd-oinw.sctreasctkeadnind cplleaacreainncebureilpdriensge,nstoathpoaot rnlyofriettdeudcwtioinndforowm, mteuscthvpaoluoerseristhnaenceasvsearrayg,ea-s mentioned in foot8nIonteduas. trial pivoted window generally used in industrial buildings. Ventilators horizontally pivoted at c*e* nAtrecrhoirtesclitguhratllylyapbroovjeec, tleodwmerapdearotfsswaminegisnegcotiount.s as industrial pivoted, except that outside framing mem ber is heavier, and it has refinements in weathering and hardware. Used in semi-monumental buddings such as schools. Ventilators swing in or out and are balanced on side arms. Hs-in. crack isobtainablein the beet practice of manufacture and installation, H*-in. crack considered to represent average practice. * Of same design and section shapes as so-called heavy section casement, but of tighter weight. K-iu- crack 1* obtainable in the best practice of manufacture and installation, Hz-in. crack considered torepresentaverage prac1 tMicaed. e of heavy sections. Ventilators awing in or ou t and stay set at any degree of opening. .H<-in. crack iiobtainable in the best practice of manufacture and installation, Hs-in. crack considered, torepresentaverage practice. Known as Intermediate Windows by steel window manufacturers. 0k With reasonable care in installation, leakage at contacts where windows are attached to steel frame*, work and at mullions, is negligible. With H-in. crack, representing poor installation, leakage at contact with steel framework is about one third, and at mullions, about one-sixth of that given for industrial pivoted windows in the table. The amount of infiltration for various types of windows is given in Table'%M 2* The fit of double-hung wood windows is determined by crack and clearance. Crack thickness is equivalent to one-half the difference be-?|* tween the inside window frame dimension and the outside sash width. The difference between the width of the window frame guide and thes^| sash thickness is considered as the clearance. The length of the perimeter^ | opening or crack for a double-hung window is equal to three times the width,M plus two times the height, or in other words, it is the outer sash penmete^g length, olus the meeting rail length. All of the window crack in any gjvebjjW$%~` Infiltration and Ventilation 231 room is not necessarily used in estimating the infiltration heat loss by the crack method. The length of crack to be selected in any given case de pends on the number of exposed sides, as explained in Chapter 12. . Values of leakage shown in Table 2 for the average double-hung wood window were determined by using, on nine windows tested in the labora tory, the average measured crack and clearance of a large number of windows found in a field survey. In addition, the table gives figures for a poorly fitted window. All of the figures for double-hung wood windows are for the unlocked condition. Just how a window is closed, or fits when it is closed, has considerable influence on the leakage. The leakage will be high if the sash are short, if the meeting rail members are warped, or if the frame and sash are not fitted squarely to each other. It is possible to have a window with approximately the average crack and clearance that will have a leakage at least double that of the figures shown. Values for the average double-hung wood window in Table 2 are considered to be easily obtainable figures, provided the workmanship on the window is good. Should it be known that the windows under consideration are poorly fitted, the larger leakage values should be used. Locking a window generally decreases its leakage, but in some cases may push the meeting rail members apart and increase the leakage. On windows with large clearances, locking will usually reduce the leakage. Wood casement windows may be assumed to have the same unit leakage as for the average double-hung wood window when properly fitted. Lock ing, a normal operation in the closing of this type of window, maintains the crack at a low value. For metal pivoted sash, the length of crack is the total perimeter of the movable or ventilating sections. Frame leakage on steel windows may be neglected when they are properly grouted with cement mortar into brick work or concrete. When they are not properly sealed, the linear feet of sash section in contact with steel work at mullions should be figured at 25 percent of the values given in Table 2 for industrial pivoted windows. When storm sash are applied to well fitted windows, some reduction in infiltration is secured; the application of the sash provides an air space which reduces the heat transmission and helps prevent the frosting of the win dows. By applying storm sash to poorly fitted windows, a reduction in leakage of 50 percent may be obtained, the effect, so far as air leakage is concerned, being roughly equivalent to that obtained by the installation of weatherstrips. Door Leakage Doors vary greatly in fit because of their large size and tendency to warp, tor a well fitted door, the leakage values for a poorly fitted double-hung wood window may be used. If poorly fitted, twice this figure should be "sed. If weatherstripped, the values may be reduced one-half. A single door which is frequently opened, as might be the case in a store, should nave a value applied which is three times that for a well fitted door. This extra allowance is for opening and closing losses, and is kept from being greater by the fact that doors are not used as much in the coldest and windi est weather. The infiltration rate through swinging and revolving doors is generally a matter of judgment by the engineer making cooling Toad determinations, and in the absence of adequate research data, the values given in Table 3 represent current engineering practice. Some tests of infiltration through swinging and revolving doors have been reported.4, The data in Table 3 232 CHAPTER 11 1956 Guide are indicative of what might be expected in this connection, but it should be noted that Table 3 is based on a no-wind condition, and therefore not directly applicable to heating design. A wide range of infiltration rates would be expected for swinging doors because of variations in the indoor-outdoor pressure difference caused by wind, temperature differences, and the degree to which a heating or an air conditioning system tended to raise or lower the inside pressure by blower action. The frequency of door usage would also affect the amount of leakage per passage. Air Change Method The amount of air leakage may be estimated by assuming a certain num ber of air changes per hour for each room, the number of changes as sumed being dependent upon the type, use, and location of the room, as Table 3. Infiltration Through 72-Inch Revolving Door and 36-Inch Swinging DoOR*.b (Cubic Feet per Person per Passage) Ubagb Fbbblt-Rbvolving Doob Doob Equipped with Bbake 75 60 60 50 40 40 36-Inch Swinging Door........... .. - ............. .. -.................... .. 20 to^OO * These figures are based on the assumption that there is no xnad pressure and thatswinging doors are in use in one wall only. Any swinging doors in other walls should be kept closed to insure air conditioning in acckorFdaronmce AwpitphlicthaetsioenreEcnogminmeeenridnegdSsttaannddaarrddss.for Air Conditioning for. Comfort 1947, Air Conditioning <6 Refrigeration Institute, Inc., Washington, D. C. and from experimental data of National Bureau of Standarda., Used by permission. indicated in Table 4. Where it is not possible to determine or pre-determine with accuracy the width of crack or clearance of windows, or when other sources of air leakage cannot readily be evaluated, as is often the case, the use of the air change method may be justified.5 The values in Table 4 may be used with reasonable accuracy for resi dences, and are the requirements for each room. The total infiltration allowance for the entire building should be one-half the sum of the infil tration allowances of the individual rooms, since whatever air enters on the windward side, generally leaves the -building on the leeward side, and the infiltration requirements therefore do not exist simultaneously on all sides or in all rooms. An allowance of one air change per hour for all sources of air leakage for the entire volume may be considered average for a well constructed residence. The air leakage, due to opening and closing of doors in vestibules, is sometimes based on the air change method, even though the air leakage estimates for other rooms are based on the crack method. Except for vestibules and reception halls, it is not advisable to attempt to apply the air change method to factories and industrial and commercial buildings, because of wide variations in the type and percentage of fenestration which is the principal source of air leakage in such buildings. Infiltration and Ventilation 233 INFILTRATION DUE TO TEMPERATURE DIFFERENCE The air exchange due to temperature difference, inside to outside, is a chimney effect, causing air to enter through openings at lower levels, and to leave at higher levels6 when the building is heated or causing flow in the reverse direction when the building is cooled. This air exchange is usually of considerable importance in tall, single-story buildings with open ings near the ground level and hear the ceiling; it should also be considered in tall, multi-story buildings unless the sealing between various floors is nearly perfect; and may be appreciable in one-story buildings with base ments and attics. The flow of air through a building under the influence of indoor-outdoor temperature difference is quite complex except for single-story structures without a basement or attic. It can best be understood by visualizing the building as a complex chimney with a number of passages and a number of restrictions. The basement represents the lower section of this imaginary chimney with air moving inward through cracks in the walls and around " CHANGES 1AKING rLACE UNDEB AVEBAGE CONDITIONS IN Residences, Exclusive of Aib Provided fob Ventilation* Kind 07 Room or Building Number 07 Air Changes taking Place per Hour Kind 07 Room or Building Number of Air Changes taking Place per Hour Rooms, 1 side exposed.-- Rooms, 2 sides exposed-- Rooms, 3 sides exposed-- Rooms, 4 sides exposed;.-- 1 m 2 2 Rooms with no windows or outside doors Entrance Halls------------- Reception Halls ......-- H to 2 to 3 2 Bath Rooms------------------- 2 )-.*<" 7L!rcSn0We"thenitriPPed wind0WB or Btorm "e * values, where applicable, but never windows and doors. The air then moves upward through cracks and open ings in the floor which acts like a damper in the chimney. Above the floor the chimney has many parallel passages consisting of the several rooms and the hollow wall spaces in certain types of construction. These separate passages are all interconnected by cracks and also communicate with the outside through cracks and fissures.' The ceiling acts as another damper with air flowing upward through various cracks and openings. This condi tion is repeated in every story of a multi-story building and can be further complicated by open stairways, elevator shafts, and utility ducts. The attic finally represents the union of all the parallel passages in the chimney with the outward flow of air being again restricted by the roof construction. Since the chimney effect in a building produces a negative pressure and an inward flow of air at the lower levels and positive pressure and outward flow at the higher levels, a neutral zone7 exists near midheight where there 18 no pressure difference between indoors and. outdoors, if the openings are about uniformly distributed in a vertical direction. At the neutral zone there would be no air flow through openings in the outside walls as a result of temperature differences. The infiltration caused by the indoor-outdoor temperature differences can be calculated by means of the crack method described earlier in this chapter for determining the infiltration caused by wind pressure. This is done by determining the equivalent wind velocity that would produce the ame rate of infiltration as was caused by the prevailing temperature dif ference. It is recommended that one-half the total crack length of the 234 CHAPTER 11 1956 Guide building be used for this computation. To determine the infiltration caused by the temperature difference, one-half the crack length of the building is multiplied by the infiltration coefficient from Table 2 corresponding to the equivalent wind velocity computed from the following equation developed from basic relationships between velocity, pressure, density and tempera ture. V, = By/h(ti -- U) (1) where = equivalent wind velocity corresponding to the temperature difference (ti -- to), miles per hour. . ft = height of rooms, feet. . . U -- inside temperature, Fahrenheit. fo = outside temperature, Fahrenheit. B = a constant to account'for leakage through floor and ceiling and for the num ber of stories in the building. The constant 5 would be 0.12 for a single-story building or for any stoiy of a multi-story building whose floor and ceiling were impervious to air, whereas the value of B was found to be approximately unity for a single story frame building with basement and attic having double wood flooring, plastered ceiling, and the walls finished with plasterboard on the inside. The value of this constant would increase as the the number of stories in creased and for stories farther removed from the neutral zone in either direction in buildings that lacked perfect sealing between stories. Sealing of Vertical Openings In tall, multi-story buildings, every effort should be made to seal off vertical openings, such as stair-wells and elevator shafts, from the remainder of the building. Stair-wells should be equipped with self-closing doors, and, in exceptionally high buildings, should be closed off into sections of not over 10 floors each. Plaster cracks should be filled. Elevator en closures should be tight, and solid doors should be used. If the sealing of the vertical openings is made effective, no allowance need be made for the chimney effect. Instead, the greater wind move ment at the greater heights makes it advisable to install additional heating surface on the upper floors above the level of neighboring buildings, this additional surface being increased as the height is increased. One arbi trary rule is to increase the heating surface on floors above neighboring buildings by an amount ranging from 5 percent to 20 percent. This extra heating surface is required only on the windward side and on windy days, and hence, automatic temperature control is especially desirable with such installations. In stair-wells that are open through many floor levels, although closed off from the remainder of each floor by doors and partitions, the strati fication of air makes it advisable to increase the amount of heating surface at the lower levels, and to decrease the amount at higher levels. One rule is to calculate the heating surface of the entire stair-well in the usual way> and to place 50 per cent of this in the bottom third, the normal amount in the middle third, and the balance in the top third. Infiltration and Ventilation 235 Infiltration in buildings normally supplies the air required for combus tion by fuel-burning appliances, but in some cases weatherstripping, sealr ing and calking may reduce infiltration to the point that special openings must be provided to supply adequate air to the heating appliances. This need for combustion air is recognized in various building codes. For instance, the State Building Construction Code of New York State for One- and Two-Family Dwellings8 requires that an air inlet area not less than the area of the smoke pipe connection be provided if adequate air supply at all times is not assured. Similarly the same code for multiple 7/V // tTV",..........'..s .' , , , , J* * * * s > / / / j v rr Fia. 2. The Jump of Wind from Windward Face of Building. (A--Length o_f S__u__c_t__io_ .n.. Area; B----iWPoiinTtOoFfMMAaXxIMimUuMm IIntensity C--o__p_ nSuction; ~ P" oint op AMx-a---x----i-m-- -u-- m vP' ressure*) dwellings requires a permanent opening to the outdoor air for rooms con taining fuel-burning appliances having a gross capacity in excess of 250,000 Btu per hour. NATURAL VENTILATION Ventilation by natural forces finds application in industrial plants. Public buildings, schools, dwellings, garages, and in farm buildings. The natural forces available for moving air into, through, and out of buildings are; (a) wind forces, and. (i>) the difference in temperature between the air inside and outside a building. The air movement may be uused by either of these forces acting alone, or by a combination of the two, depending upon atmospheric conditions, building design, and location. 236 CHAPTER 11 1956 Guide The ventilating results obtained will vary, from time to time, due to varia tion in the velocity and direction of the wind, and the temperature difference. The arrangement, location, and control of the ventilating openings should be such that the two forces act cooperatively rather than in opposition. WIND FORCES In considering the use of natural wind forces for producing ventilation, account must'be taken of: (1) average wind velocity; (2) prevailing wind direction; (3) seasonal and daily variations in velocity and direction; and (4) local wind interference by nearby buildings, hills or other obstructions of similar nature. Values are given in Table 3, Chapter 13 for the average wind velocities for the months June to September in various localities throughout the United States, while Table 1, Chapter 12, lists similar values for the winter. In almost all localities,- the summer wind velocities are lower than those in the winter, and in about two-thirds of the localities the prevailing direc tion is different during the summer and winter. While the tables give no average velocities below 5 mph, there will be times when the velocity is lower, even in. localities where the seasonal average is considerably above 5 mph. There are relatively few places where the velocity falls below onehalf of the average for many hours per month. Consequently, if the natural ventilating system is designed for wind; velocities of one-half of the average seasonal velocity, it should prove satisfactory in almost every case. .` Equation 3 may be used for calculating the quantity of air forced through ventilation openings by the wind, or for determining the proper size of such openings to produce given results: - . Q = EAV (3) where . ., ....... . Q = air flow, cubic feet per minute. A = free area of inlet openings, square feet. V = wind velocity, feet per minute, = miles per hour X 88. E = effectiveness of openings. (E should be taken at 0.50 to 0.60 for perpendicu lar winds, and 0.25 to 0.35 for diagonal winds.) The precision of results obtained by the use of Equation 3, depends upon the placing of the openings, as the formula assumes that ventilating openings have a flow coefficient slightly greater than that of a squareedged orifice. If the openings are not advantageously placed with respect to the wind, the flow per unit area of the openings will be less and, if un usually well placed, the flow will be slightly more than that given by the formula. Inlets should be placed to face directly into the prevailing wind, while outlets should be placed in one of the five places listed: 1. On the side of the building directly opposite the direction of the prevailing wiu't - 2. On the roof in the low pressure area caused by the jump of the wind (see Fig. ") 3. On the sides adjacent to the windward face where low pressure areas occur. 4..In a monitor on the side opposite from the wind. 5. In root ventilators or stacks. . ' TEMPERATURE DIFFERENCE FORCES7 ,. The stack effect produced within a building, when the outdoor tempera ture is lower than the indoor temperature, is due to the difference in weight Infiltration and Ventilation 237 of the warm column of air within the building and cooler air outside. The flow due to stack effect is proportional to the square root of the draft head, or approximately where Q = 9.44 Vh(t, - J,,) (4) Q -- air flow, cubic feet per minute. A = free area of inlets or outlets (assumed equal), square feet. h = height from inlets to outlets, feet. (, = average temperature of indoor air in height h, Fahrenheit. t0 = temperature of outdoor air, Fahrenheit. 9.4 = constant of proportionality, including a value of 65 percent for effectiveness of openings. This should be reduced to 50 percent (constant = 7.2) if con ditions are not favorable. HEAT REMOVAL In problems of heat removal, knowing the amount of heat to be removed and having selected a desirable temperature difference, the amount of air to be passed through the building per minute, to maintain this tempera ture difference, can-be determined by means of Equation 5. where H Q= Cp X p X 60(f, -- t0) H 1.08(<j -- to) (5) Q = air removed, cubic feet per minute. H -- heat removed, Btu per hour. Cp = specific heat of air at constant pressure, 0.24. p = density of standard air, 0.075 pounds per cubic foot, i, -- to = indoor-outdoor temperature differences, Fahrenheit. EFFECT OF UNEQUAL OPENINGS The largest flow per unit area of openings is obtained when inlets and outlets are equal, and the preceding equations are based on this condition. Increasing outlets over inlets, or vice-versa, will increase the air flow, but not in proportion to the added area. When solving problems having an unequal distribution of openings, use the smaller area, either inlet or out let, in the equations, and add the increase as determined from Fig. 3. COMBINED FORCES OF WIND AND TEMPERATURE Equations have already been given for determining the air flow due to temperature difference and wind. It must be remembered that when both forces are acting together, even without interference, the resulting air flow is not equal to the sum of the two estimated quantities. The flow through any opening is proportional to the square root of the sum of the heads acting on that opening. . When the two heads are about equal in value, and the ventilating openwgs are operated so as to coordinate them, the total air flow through the building is about 10 percent greater than that produced by either head acting independently under conditions ideal to it. This percentage de creases rapidly as one head increases over the other. The effect of the larger head will predominate. The wind velocity and direction, the outdoor temperature, or the indoor 238 CHAPTER 11 distribution, cannot be predicted with certainty, and refinement in calcu lations is not justified; consequently, a simplified method/can be used. This may be done by using the equations and calculating the flows produced by each force separately, under conditions of openings best suited for co ordination of the forces. Then, by determining the ratio of the flow pro duced by temperature difference to the sum of the two flows, the actual flow due to the combined forces can be approximated from Fig. 4. Example 1: Assume a drop forge shop, 200 ft long, 100 ft wide, and 30 ft high. The cubical content is 600,000 cu ft, and the height of the air outlet over that of the inlet is 30 ft. Oil fuel of 18,000 Btu per lb is used in this shop at the rate of 15 gph (7.75 lb per gal). Desired summer temperature difference is 10 deg, and the prevail ing wind is 8 mph perpendicular to the long dimension. What is the necessary area for the inlets and outlets, and what is the rate of air flow through the building? . Infiltration and Ventilation 239 n oi opening in its path for inflow, and 595 in the lee side of the monitor for outflow with the windward side closed. The air flow, as calculated by Equation 3, will be: Q = 0.60 X 400 X 704 = 168,960 cfm. This gives 16.9 air changes per hour, which should be more than ample when there is no heat to be removed. ' j... \,unu>int'A* neons: since the windward side of the monitor is closed when the wind is blowing, the flow due to temperature difference must be calculated for this condition, using Fig. 3. This chart shows that, when inlets are twice the size of the outlets, in this case 1,190 sq ft in the sidewalls and 595 sq ft in the monitor) the flow will be increased 26.5 percent over that produced by equal openings. Using Fig. 3. Increase in Flow Caused by Excess of One Opening Over Another Solution Jot Temperature Difference Only: The heat H -- 15 X 7.75 X 18,000 =f. 2,092,500 Btu per hr. ' By Equation 5, the air flow required to remove this heat with an average temperature difference of 10 deg is H Q= 1.08(fi - to) 2,092,500 = 193,750 cfm. 1.08 X 10 This is equal to about 20 air changes per hour. From Equation 4, the inlet (or outlet) opening area should be \;l Q A= 9.4VA(ti - to) 193,750 9.4 V30 X 10 1190 sq ft- The flow per square foot of inlet or outlet would be 193,750 -e 1190 = 162.5 cfm, with all windows open. ... Solution for Wind Only: With 1,190 gq ft of inlet openings distributed around the sidewalls, there will be about 400 sq ft in each long side and 195 sq ft in each en,,<JThe outlet area will be equally distributed on the two sides of the monitor, or 595 w- ft on each side. With the wind perpendicular to the long side, there will be 400si Fig. 4. Determination of Flow Caused by Combined Forces of Wind. and Temperature Difference ^o- unt for uthpiesiucnognadnitaiotn-newnilol wbeper square foot obtained previously, the calculated. 595 X 163 X 1.265 = 122,700 cfm. Adding the two computed flows: Temperature Difference = 122,700 = 42 percent. Wind = 168,960 -- 58 percent. Total 2__91.,,6vv6v0 - 1a0w0 ppCetrVcCeUnbt.i . From Fig. 4 it.is determined that, when the flow due to temperature difference is 4*percent of the total, the actual flow due to the combined forces, will be about -1.6 hmes that calculated for temperature difference alone, or 196,300 cfm. . . The original flow due to temperature difference alone was 193,750 cfm with all openings in use. The effect of the wind is to increase this to 196,300 elm, even though "Rif of the outlets are closed. A factor of judgment is necessary in the location of the openings in a building, especially those in the roof, where heat, smoke, and fumes are to ue removed. Usually, windward monitor openings should be closed, but if 240 CHAPTER 11 1956 Guide the wind is low enough for the temperature head to overcome it, all windows may be opened. , TYPES OF OPENINGS Types of openings may be classified as: (1) windows, doors, monitor openings and skylights; (2) roof ventilators; (3) stacks connecting to registers; and (4) specially designed inlet or outlet openings. The various types and principles of operation are discussed in following paragraphs. Windows, Doors and Skylights Windows have the advantage of transmitting light, as well as providing ventilating area, when open. Their movable parts are arranged to open in various ways; they may open by sliding either vertically or horizontally, by tilting on horizontal pivots at or near the center, or by swinging on pivots, at the top, bottom or side. Regardless of their design, the air flow per square foot of opening may be considered to be the same under the same conditions. The type of pivoting should receive consideration from the standpoint of weather protection, and certain types may be ad vantageous in controlling the distribution of incoming air. Deflectors are sometimes used for the same purpose, and these devices should be con sidered a part of the ventilation system. Roof Ventilators The function of a roof ventilator is to provide a storm and weather proof air outlet. These are actuated by the same forces of wind and tem perature head which create flow through other types of openings. The capacity of a ventilator depends upon four things: (1) its location on the roof; (2) the resistance it and the duct work offer to air flow; (3) the height of draft; and (4) the efficiency of the ventilator in utilizing the kinetic energy of the wind for inducing flow by centrifugal or ejector action. For maximum flow induction, a ventilator should be located on that part of the roof where it will receive the full wind without interference.' If ventilators are installed within the suction region created by the wind passing over the building, or in a fight court, or on a low building between two high buildings, their performance will be seriously influenced. Their normal ejector action, if any, may be completely lost. The base of the ventilator should be of a taper-cone design to produce the effect of a bell-mouth nozzle whose coefficient of flow is considerably higher than that of a square-entrance orifice. If a grille is provided at the base, or if. the base or structural members present obstructions, addi tional resistance is introduced, and the base opening should be increased in size accordingly. Air inlet openings located at lower levels in the building, should be at least equal to, and preferably larger than, the combined throat areas of all roof ventilators. The air discharged by a roof ventilator depends on wind velocity and temperature difference, and, in general, its performance will be the same as any monitor opening located in the same place but, due to the four capacity factors already mentioned, no simple formula can be devised for expressing ventilator capacity. Roof ventilators may be classified as stationary, pivoting or oscillating, and rotating. Generally, these have a round throat, but the continuousridge ventilator would fall in the stationary classification. When selecting roof ventilators, some attention should be given to ruggedness of construc- Infiltration and Ventilation 241 tion, storm-proofing features, dampers and damper operating mechanisms, possibility of noise, original cost, and maintenance. : Natural ventilation units may be used to supplement power-driven supply fans, and under favorable weather conditions it may be, possible to stop the power-driven units. Units are not subject to code tests for ratings. Generally, they must be selected from manufacturers' tables. It is, therefore, very important to consider the reliability of the ratings used. Controls . Gravity ventilators may have dampers controlled by hand, thermostat, or wind velocity, in combination with a fan. The thermostat station may be located anywhere in the building, or it may be located within the ventilator itself. The purpose of wind velocity control is to obtain a definite volume of exhaust regardless of the natural forces, the fan motor being energized when the natural exhaust capacity falls below a certain minimum, and again shut off when the wind velocity rises to the point where this minimum volume can be supplied by natural forces. . Stacks Stacks or vertical flues are really chimneys which function through the effects of the wind and temperature difference. Like the roof ventilator, the stack outlet should be located so that the wind may act upon it from any direction. With little or no wind, the chimney effect depends entirely on temperature difference to produce a removal of air from the rooms where the inlet openings are located. GENERAL VENTILATION RULES A few of the important considerations, in addition to those already out lined, are: 1. Inlet openings in the building should be well distributed, and should be located on the windward side near tbe bottom, while outlet openings are located on the lee ward side near the top. Outside air will then be supplied to the zone to be ventilated, 2. Inlet openings should not be obstructed by buildings, trees, sign boards, etc., outside, nor by partitions inside. -. 3. Greatest flow per square foot of total opening is obtained by using inlet and out let openings of nearly equal areas. :' . _4. In the design of window ventilated buildings, where the direction of the"wind is quite constant and dependable, the orientation of the building, together with amount end grouping of ventilation openings, can be readily arranged to take fall advantage of the force of the wind. Where the wind's direction is quite variable, the openings should be arranged in sidewalls and monitors so that, as far as possible, there will be approximately equal areas on all sides. Thus, no matter what the wind's direction, there will always be some openings directly exposed to the pressure force, and others to a suction force, and effective movement through the building will be assured. . 5. Direct short circuits between openings on two sides at a high level may clear the air at that level without producing any appreciable ventilation at the level of oc cupancy. 6- In order that temperature difference may produce a motive force, there must be Ihl '-Ca* ^stance between openings. That is, if there are a number of openings avail able in a building, but all are at the same level, there will be no motive head produced y temperature difference, no matter how great that difference might be. va lu order that the force of temperature difference may operate to maximum adDo 'v!P' *'*le vertiai distance between inlet and outlet openings should be as great as lion > e Openings in the vicinity of the neutral zone are less effective for ventila- the use of monitors, windows on the windward side should usually be kept "Sed, since, if they are open, the inflow tendency of the wind counteracts tbe outflow 242 CHAPTER 11 1956 Guide tendency of temperature difference. Openings on the leeward side of the monitor result in cooperation of wind and temperature difference. ; . 9. In an industrial building where furnaces that give off heat and fumes are to be installed, it is better to locate them in the end of the building exposed to the prevail ing wind. The strong suction effect of the wind at the roof near the windward end will then cooperate with temperature difference, to provide for the most active and satisfactory removal of the heat and gas-laden air. 10. In case it is impossible to locate furnaces in the windward end, that part of the' building in which they are to be located should be built higher than the rest, so that the wind, in splashing therefrom, will create a suction. The additional height also increases the effect of temperature difference to cooperate with the wind. 11. The intensity of suction, or the vacuum produced by the jump of the wind, is greatest just back of the building face. The area of suction does not vary with the wind velocity, but the flow due to suction is directly proportional to wind velocity. 12. Openings much larger than the calculated areas are sometimes desirable, espedaily when an increase in occupancy may occur, or when extremely hot days may be anticipated. In the former case, free openings should be located at the level of occu pancy for psychological reasons. 13. In single story industrial buildings, particularly those covering large areas, natural ventilation must be accomplished by taking air in and out of the roof open ings. Openings in the pressure zones can be used for inflow, and openings in the suc tion zone, or openings in zones of less pressure, can be used for outflow. The ventila tion is accomplished by the manipulation of openings to get air flow through the zones to be ventilated. VENTILATION OF ANIMAL SHELTERS10 Animal shelters require ventilation to remove moisture, odors and, in the case of dairy stables, excess heat. Outlets. Outlet flues for natural draft systems should be round or approximately square. A thermal resistance (1/17) of not less than two is required in their side walls. They should extend at least two feet above the highest part of the roof. Only one outlet is recommended for each room or pen. The use of several outlet flues may result in excessive up-drafts in some flues, and down-drafts in others. If flues have roofs or covers, these should be high enough to provide unobstructed openings on all sides, equal in height to one-half the least dimension of the flue, Fig. 5. A level, heavily insulated ceiling under the flue roof, and over the entire area of the flue, is important. Inlets. Inlets should direct the incoming air vertically upward so as to avoid drafts on the animals, and to insure immediate mixing of incoming air with the room air. A reasonably uniform distribution around the. stable or pen is desirable. Inlet flues, that deliver air close to the side walls, stimulate convection currents, which is desirable. When so placed, they also tend to bathe the side walls with cool air, thus reducing temperature differ ence between the inside and outside of the wall. From the standpoint of air movement, insulation of inlet flues is not important. Condensation is, however, likely to occur on them, unless the thermal resistance of their walls is at least two. Controls or throttling devices in inlet flues are seldom required. If used, they are best applied to the inlets and limited to the side of the building facing prevailing winter winds. They should be so made that an opening, at least one inch wide by the width of the flue, will always remAaminouonptesn.of heat and water produced by livestock vary not only with the different kinds of animals, but also with age, weight, feed consumption and production. These facts, and the vagaries of the weather, make exact Infiltration and Ventilation 243 calculations impossible. The following practical recommendations are based on numerous, carefully checked observations. It is desirable to keep the relative humidity of livestock shelters below 83 percent. Temperatures may be as indicated in the discussion fpr each kind of animal. Dairy Stables The most usually accepted temperatures for dairy stables, where cows are confined in stanchions or tie stalls, are from 45 to 55 F. These tempera tures are readily maintained in winter weather by the body heat of the herd in well constructed, well stocked and well ventilated stables. Stable volume in excess of 600 cu ft, and exposed wall area in excess of 130 sq ft per 1000 lb animal weight are, in general, undesirable. Side walls should have an overall thermal resistance of from 2 to 5, depending on the temperature zone and wind exposure. . Thermal re- Fio. 5. Recommended Type op Coveb fob Wooden Outlet Flue . The opening H should equal one-half the least dimension of the flue. Heavy insulation of the level deck tt essential. _ sistance of the ceiling should be 50 percent greater than that of the side walls. In stables of this sise and so insulated, a ventilation rate of 3200 to 3800 cu ft per (hr) (1000 lb of animal) usually insures good conditions. The following recommendations do not apply to so-called pen stables or loafing bams in which there is a thick manure and bedding pack on the floor, and in which doors are normally kept open. Outlets. One flue will serve a stable 200 ft long. In stables over 120 ft long, the flue should be about midway between the ends or, if the stable is L-shaped, near the angle. In shorter stables, it may be at any con venient location. The exhaust point in the stable should be not more than 18 in. above the floor. ,Hiis permits removal of only the coolest air, and prevents rapid fluctuations in stable temperature. A basic rule for finding the cross-section of the outlet flue is ,, tonere , 176 N Ao ~ Vh 4 area of the outlet flue, square inches. (6) 1956 Guide CHAPTER 11 244 N -- weight of animal population, thousands of pounds. h vertical distance from top of inlet flues to top of outlet flue, feet. ^ '` i For large flues the flue area obtained from the basic formula may well be reduced according to the chart, Fig. 6, because of a decrease in friction. Example 2: Assume a stable in which the vertical height from the top of the inlets to the top of the outlet flue is 32.5 ft, and in which 38 cows, averaging 1300 lb, will be housed. Determine required Bize of outlet flue. . Solution: From Equation 6 176 X (38 X 1-300) 1525 sq in. A,, V&Z From Fig. 6 the factor to be applied to this area is 94.5 percent. Therefore, the area of flue required is 1525 X 0.946 = 1441 sq in. . Inlets. Inlet flues, each approximately 60 sq. in. in area, have given good results. One such flue should be provided for each 3500 lb animal weight. They should deliver air from points 12 to 18 in. below the ceiling. Area for Outlets Exceeding 1000 Sq In. Fig. 6. Modification, of Flue A S. hSeehpelBtearsrnussed for breeding and feeding stock usually have enough open ings, so that no special provision for ventilation is required. Barns for win-. ter lambing flocks, however, require ventilation systems. Fermentation,, in the floor pack of manure produces heat, vapor and odor. These musk be added to the ventilation load regularly produced by the animals. Outlets. In practice, results obtained by the basic formula, Equation, 7, when modified by the use of the chart. Fig. 6 have given good re suits: where ' ,C 4,, = area of the outlet, square inches. h == fvloeortricaarel ah,esigqhutarfreofmeetto. p of inlet openings to top of outlet flue, feet. .'; The bottom of the outlet flue should be 15 to 24 in. above the surface of theInmleatsn.urePproacvkid.e one inlet, 60 sq in. in area, for each 150 sq ft of flo Infiltration and Ventilation 245 area. Inlets should be well distributed around the side walls, and de signed to deliver air near the ceiling (see section on Daily Stables). Swine Bams Community swine barns,, because of the extent of slop feeding and the absence of daily cleaning of the pens, are the most difficult farm buildings to ventilate satisfactorily. Farrowing pens, to which supplemental heat is supplied, present less of a problem. In all cases, good floor drainage to remove urine and excess spilled water is important. Temperatures of from 50 to 55 F are usually recommended for farrowing pens. It is desirable to maintain temperatures above freezing in all other pens in community houses. For bams that are well stocked and adequately ventilated, this requires walls with an overall thermal resistance of from 3 to 6, and ceilings with 40 to 50 percent greater resistance. : Outlets. The outlet flue should draw air from a level of 15 to 18 in. above the floor. Equation 8 is the basic formula for flue area, and gives reasonably good results when modified according to the chart. Fig. 6. 5 x At A~ Vh (8) Inlets. At least one inlet flue should be used for each pen. Swine are given or select definite nesting places, and care must be exercised to avoid having inlets located over them. Total inlet area should be approximately 70 percent of outlet area. The area of individual inlets is best determined from the total area re quired, and the number that can be so installed as to meet previous speci fications, Inlets should deliver air from points 12 to 15 in. below the ceil ing, or from a level deflector on a sloping ceiling. Poultry Laying Houses From the standpoint Of ventilation, poultry laying houses may be di vided into cold houses and warm houses. The former are uninsulated, except in the ceiling. The inside-outside temperature difference is seldom more than 5 F deg. In the warm house, because of insulation or supple mental heat, the temperature seldom falls below 32 F, and is usually above 45 F. Outlets. The outlet flue is best placed near the middle of the pen. It is advisable to limit the length of pens to 80 ft. The area of the outlet flue may be determined from Equation 9, and modified according to the chart, Fig. 6. 2.5 x A i Vh (9) . For a cold house, the bottom of the flue should be at the level of the msulated ceiling. In warm houses, the bottom of the flue should be 12 to 15 in. above the level of the floor litter. Inlets. Inlets may be approximately 60 sq in. in area. The total inlet area may be equal to 70 percent of the outlet area. Inlets in cold and in ?"arm houses should deliver air from points 12 to 24 in. above the floor. 19 cold houses which normally do not have storm sash, windows may be 246 CHAPTER 11 1956 Guide raised enough to give the desired area, and be fitted with baffle boards to direct the air straight and upward. . In houses less than 20 ft in width, all inlets may be on one side. In wider houses, a rather uniform distribution of inlets is essential. GARAGE VENTILATION Because of hazards resulting from carbon monoxide and other physi ologically harmful or combustible gases or vapors in garages, the importance of proper ventilation of these buildings cannot be over-emphasized. Dur ing the warm months of the year, garages are usually ventilated adequately because the doors and windows are kept open. The A.S.H.A.E. Code of Minimum Requirements for Heating and Ventilating Garages,11 adopted in 1935, specifies that openings for natural ventilation shall be distributed as uniformly as possible in at least two outside walls, and that the total area of. such openings shall be equivalent to at least 5 percent of the floor area. The code further states that where it is impracticable to operate such a system of natural ventilation, a mechanical system shall be used, and shall provide for either the supply of 1 cfm of outdoor air for each square foot of floor area, or for exhaust of the same amount of air, dis charging it to the outside as a means of flushing the garage. Cooperative research" on garage ventilation, undertaken by the A.S.II.A.E. Committee on Research at Washington University, St. Louis, Mo.,and at the University of Kansas, and tests conducted at the A.S.H.A.E. Research Laboratory, have resulted in authoritative papers on the subject; Some of the conclusions based on work at these laboratories are; . 1.' Upward ventilation results in a lower concentration of carbon monoxide at the breathing line and a lower temperature above the breathing line, than does downward ventilation for the same rate of carbon monoxide production, air change, and the same temperature at the 30-in. level. 2. A lower rate of air change and a smaller heating load are required with upward than with downward ventilation. 3. In the average case, upward ventilation results in a lower concentration of carbon monoxide in .the occupied portion of a garage, than that obtained with mixing of the exhaust gases and the air supplied. However, the variations in concentration from point to point, together with the possible failure of the advantages of upward ventilation to accrue, suggest the basing of garage ventilation on complete mixing, and an air change sufficient to dilute the exhaust gases to the allowable concentration of carbon monoxide. ; 4. The rate of carbon monoxide production by an idling car is shown to vary from 25 to 50 cfh, with an average rate of 35 cfh. 5. An air change of 350,000 cfh per idling car is required to keep the carbon mon oxide concentration down to one part in 10,000 parts of air. Individual Exhaust Ducts Motor vehicle servicing areas may be provided with underground or overhead exhaust systems discharging outdoors. Each service location should be provided with a flexible branch duct, the inlet end of which is sized to slip over the tail pipe of the engine, or over any deflector attached to the tail pipe. The minimum branch size and ventilation rate for the largest class of vehicle regularly serviced at each location are shown in Table 4. Where each tail pipe exhaust branch is provided with an automatic de vice to close the branch inlet when it is not in use, the capacity of the fan for the system should be based on the maximum number of branches in simultaneous use. Where the branch inlets are open when not in use, the tf-VJ- Infiltration and Ventilation 247 Table 4. Minimum Tail Pipe Connection Size aNd Ventilation Rate '5 ~~ r 1 Class of Vehicle Auto. Truck Bus .. Tail Pipe Diameter, in. Under 2 2 to 3 3 and over Ventilation Rate, cfm 100 150 250 Flexible Pipe, Diam, in. I Diameter of Rigid Branch Connection TO Flexible Pipe, in system capacity should be based on the total number of branches connected to the main. Individual straight lengths of gas tight duct, not over 20 feet in length, terminating outdoors, may be provided where exhaust systems are not installed. The duct should fit tightly over the tail pipe and be of a diam: eter not less than the diameter of the tail pipe. ` . .. REFERENCES 1 A.S.H.V.E. Research Report No. 786--Infiltration Through Plastered and Unplastered Brick Walls, by F. C. Houghten and Margaret Ingels (A.S.H.V.E. Transactions, VoI. 33, 1927, p. 377). No. 826--Air Infiltration Through Various Types of Brick Wall Construction, by G. L. Larson, D. W. Nelson and C. Braatz .. (A.S.H.V.E. Transactions, Vol. 35,1929, p. 183). No. 851--Air Infiltration Through Various Types of Brick"Wall Construction, by G. L. Larson, D. W. Nelson and C. Braatz (A.S.H.V.E. Transactions, VoI. 36, 1930, p. 99). No. 868--Air Infiltration Through Various Types of Wood Frame Construction, by G. L. Larson, D. W. Nelson and C. Braatz (A.S.H.V.E. Transactions, Vol. 36, 1930, p. 397).' . ' Bu1ildAi.nSg.sHb.Vy.EF.. RCe.sHeoarucghhtRenepaonrdtsC.NCo.. 6S8c6h--raAdierrL(eAa.kSa.gHe.VT.hEr.ouTgrhanthseacOtpioennsin,gVsoinl. 30,1924, p. 105). No. 704--Air Leakage Around Window Openings, by C. C. Schrader (A.S.H.V.E. Transactions, Vol. 3b, 1924, p. 313). No. 803--Air Leakage Studies on Metal Windows in a Modern Office Building, by F. C. Houghten and M. E. O'Con nell (A.S.H.V.E. Transactions, Vol. 34, 1928, p. 321). No. 815--Air. Leakage Through a Pivoted Metal Window, by F. C. Houghten and Mi E. O'Connell (A.S. . H.V.E. Transactions, Vol. 34, 1928, p. 519). No. 817--Effect of Frame Calking _ and Storm Windows on Infiltration Around and Through Windows, by W. M. Richt- mann and C. Braatz (A.S.H.V.E. Transactions, Vol. 34, 1928, p. 547).- No. 909-- Air Infiltration Through Double-Hung Wood Windows, by G. L. Larson, Di W. Nelson and R. W. Kubasta (A.S.H.V.E. Transactions, Vol. 37, 1931, p. 571). The Weathertightness of Rolled Section Steel Windows, by J. E. Emswiler and W. C. Randall (A.S.H.V.E. Transactions, Vol. 34, 1928, p. 527). Pressure Differences Across Windows in Relation to Wind Velocity, by J. E. Emswiier and W. C. Randall (A.S.H.V.E. Transactions, Vol. 36, 1930, p. 83). Air Infiltration Through Steel Framed Windows, by D. O. Rusk, V. H. Cherry and L. Boelter (A.S.H.V.E. Trans actions, Vol. 39, 1933, p. 169). `Fuel Saving Resulting from the Use of Storm Windows and Doors, by A. P. Kratz and S. Konzo (A.S.H.V.E. Transactions, Vol. so iaoa - or' . 4The Tnfilti-o*:--v>--' ' ` of --,ce BturiladninsgacatsioInnfslu,eV^nocle. d40b,1y9t3h4e, pS...t.a.3.c.8.k.7..)E... ff.eN..cojtj.,m1bu0yi6u9Fs--n. RHCw.eaHatnoindugguhRateerqlnutiaiurnetdbmeCernaletrslt n".,let (A.S.H.V.E. Transactions, Vol. 43, 1937, p. 437). Flue Action in High tv jby H. L. Alt (A.S.H.V.E. Journal Section, Heating, Piping and Air ...'`-hhonmg, May, 1932, p. 376). Influence of Stack Effect on the Heat Loss in o Buildings, by Axel Marin (A.S.H.V.E. Transactions, Vol. 40, 1934, p. 377). Neutral Zone in Ventilation, by J. E. Emswiler (A.S.H.V.E. Transactions, 32,1926, p. 59). 1956 Guide CHAPTER 11 248 8 State Building Construction Code Applicable to One- and Two-Family Dwell ings, State Building Code Commission, 1740 Broadway, New York 19, N. Y. 8 Predetermining Airation of Industrial Buildings, by W. C. Randall and E. W. Conover (A.S.H.V.E. Transactions, Vol. 37, 1931, p. 605). 10 Dairy Stable Ventilation, by F. L. Fairbanks (A.S.H.V.E. Transactions, Vol. 34, 1928, p. 181). Cow Barn Ventilation, by Alfred J. Offner (A.S.H.V.E. Trans actions, Vol. 39, 1933, p. 149). For additional information on this subject refer to Technical Bulletin, V. S- Department ofAgriculture (1930), by M. A. R. Kelley. Also see Air Conditioning of Farm Buildings, by F. L. Fairbanks (Agricultural Engineer ing, November, 1937, p. 485), Dairy Stable Ventilation (Revision of 1949) by F. L. Fairbanks and A. M. Goodman (Cornell University, Cornell Extension Bulletin No. 151) and The Ventilation of Poultry Laying Houses (Revision of 1950) by F. L. Fairbanks and A. M. Goodman (Cornell University, Cornell Extension Bulletin No. 3151)1. Code of Minimum Requirements for Heating and Ventilating Garages (A.S.H.V.E. Transactions, Vol. 41,1935, p. 30). Airation Study of Garages, by W. C. Randall and L. W. Leonhard (A.S.H.V.E. Transactions, Vol. 36, 1930, p. 233). A.S.H.V.E. Research Report No. 874--Carbon Monoxide Concentration in Garages, by A. S. Langsdorf and R. R. Tucker (A.S.H.V.E. Transactions, Vol. 36, ,1930, p. 511). A.S.H.V.E. Research Report No. 935--Carbon Monoxide Distribu tion in Relation to the Ventilation of an Underground Ramp Garage, by F. C. Houghten and Paul McDermott (A.S.H.V.E. Transactions, Vol. 38,1932, p. 439). A.S.H.V.E. Research Report No. 934--Carbon Monoxide Distribution in Relation to the Ventilation of a One-Floor Garage, by F. C. Houghten and Paul McDermott (A.S.H.V.E. Transactions, Vol. 38, 1932, p. 424). A.S.H.V.E. Research Report No. 967--Carbon Monoxide Distribution in Relation to the Heating and Ventilation of a One-Floor Garage, by F. C. Houghten and Paul McDermott (A.S.H.V.E. Transactions, Vo). 39, 1933, p. 395). Carbon Monoxide Surveys of Two Garages, by A. H. Sluss, E. K. Campbell and Louis M. Farber (A.S.H.V.E. Transactions, Vol. 40, 1934, p. 263). bibliography GaEraxgpeerivmeennttialal tSiotundies on the Effect of Ethyl Gasoline and its Combustion Prod ucts, by R. R. Sayers, A. C. Fieldner, W. P. Yant and B. G. H. Thomas (V. S. Bureau of MViennetsilaMtioonnogorfaVphehNicou. l2a,r1T92u7n)n.els, by A. C. Fieldner, Yandell Henderson, J. W. P' auUls,eRo. fRD. iSeasyeelrEs,negtinaels(Ain.ST.Hun.Vn.eEls.,JboyurSn. Hal. JAasnh.-aDnedeL. .19L2.6N). aus (V. S. Bureau of. MinVeesnItnilfaotriomnatIionnvoClviercdulianr tNhoe. U7s2e22,of19G42a)s.oline Powered Equipment in Enclosed Spaces, by L. B. Berger (U. S. Bureau of Mines Information Circular No. 7404,1947). . Diesel Engines Underground: Composition of Exhaust Gas from Engines in Proper Mechanical Condition, by J. C. Holtz, L. B. Berger, M. A. Elliott and H. H. SchreBk (UD. Sie.sBeul ErenaguinoefsMUinnedserRgeropuorntdo: fUInsveeosftigDaietisoenlsLNooco. m35o0t8iv, e1s94in0).Construction of the Delaware Aqueduct . Effect of Exhaust Gases upon Quality of Tunnel Air, by L. B. Berger, M. A. Elliott, J. C. Holtz and H. H. Schrenk (17. S. Bureau of Mines Report. of Investigations No. 4032, 1947). CHAPTER 12 HEATING LOAD General Procedure, Design Outdoor Weather Conditions, Inside Temperatures, Attic Temperatures, Temperatures in Unheated Spaces, Ground Tempera tures, Basement Temperatures and Heat Loss, Heat Losses from Floor Slabs, Transmission Heat Loss, Infiltration Heat Loss, Selection of Wind Velocities, Auxiliary Heat Sources, Intermittently Heated Buildings, Residence Heat Loss Problems PRIOR to designing a beating system, an estimate must be made of the maximum probable beat loss of each room or space to be heated, based on maintaining a selected inside air temperature during periods of design outdoor weather conditions. The heat losses may be divided into two groups, namely: (1) the transmission losses orheat transmitted through the confining walls,, floor, ceiling, glass or other surfaces; and (2) the in filtration losses or heat required to warm outside air which leaks in through cracks and crevices, around doors and windows, opening of doors and win dows, or heat required to warm outside air used for ventilation. GENERAL PROCEDURE The general procedure for calculating heat losses of a structure is: 1. Select the design outdoor weather conditions: temperature, wind direction and wind velocity. The data on climatic conditions given in Table 1 and the isotherms of average design temperature in Fig. 1 will be helpful, but should be used with judg ment as suggested in the section Design Outdoor Weather Conditions. 2. Select the inside air temperature, which is to be maintained in each room during the coldest weather. (See Table 2). 3. Estimate temperatures in adjacent unheated spaces and the attic. The attic temperature need not be estimated if the combined roof and ceiling coefficient is used, 4.. Select or compute the heat transmission coefficients for outside walls and glass; also for inside walls, floors, or top-floor ceilings, if these are next to unheated space; include roof if next to heated space. (See Chapter 9. If the design wind velocity is appreciably different from 15 mph, the appropriate change in the heat transmission coefficients in Tables 6 to 9 and 15 to 19 of Chapter 9 can be found in Table 21 of that chapter.) 5. Measure net area of outside wall, glass and roof next to heated spaces, as well as any cold walls, floors or ceilings next to unheated space. Such measurements are made from building plans, or from the actual building, using inside dimensions. 6. Compute the heat transmission losses for each kind of wall, glass, floor, ceiling and roof in the building by multiplying the heat transmission coefficient in each case py the area of the surface in square feet, and the temperature difference between th e inside and outside air. (See Items 1, 2, and 3). t v' elect unit values and compute the heat equivalent of the infiltration of cold air taking place around outside doors and windows.. These unit values depend on the Rind or width of crack, wind velocity, and the temperature difference between the inside and outside air; the result expresses the heat required to warm up the cold air leaking into the building per hour. (See Chapter 11). 8. When positive ventilation using outdoor air is provided by an air heating or an m c,?4itibning unit, the heat required to warm the outside air to room temperature must be provided by the unit; if mechanical exhaust from the room is provided, in mount equal to the outside air drawn in by the unit, the natural infiltration losses must also be provided for by the unit. If no mechanical exhaust is used, and the 249 250 CHAPTER 12 1956 Guide outdoor air supply equals or exceeds the amount of natural infiltration which would occur without ventilation, the natural infiltration may be neglected. 9. The sum of the heat losses by transmisions (Item 6) through the outside walls and glass, as well as through any cold floors, ceilings or roof plus the heat equivalent (Item 7) of the cold air entering by infiltration, or required to replace mechanical exhaust, represents the total heat loss equivalent for any building. 10. In buildings which have a reasonably steady internal heat release of appre ciable magnitude from sources other than the heating system, a computation of tnis heat release under design conditions should be made for deduction from the total of the heat losses computed in items 1-9. This is especially important for heating sys tems of high initial cost'or those for which a .demand charge is based on installed capacity. DESIGN OUTDOOR WEATHER CONDITIONS There are no hard and fast rules for selecting the design outdoor weather conditions to be used for a given locality or type of building or healing system,, and the selection is to some extent a matter of judgment and experience. The appropriate design temperature in a given locality may vary with heat capacity and degree of insulation of a particular structure, the amount of protection from the wind, the length of time that nightly minimum tempera tures persist, whether the particular building is being used day and night, and perhaps other factors. For heating systems that depend primarily on electrical energy as a source of heat it will often be desirable, for economic reasons, to make a more careful analysis of the factors that affect design weather conditions than would otherwise be justified. The outside design temperature seldom is taken as the lowest tempera ture, or even the lowest daily mean temperature ever recorded in a given locality. Such temperatures rarely recur in successive years. Likewise the wind direction and velocity occurring at the time of design outside tempera ture may be different from the average velocity and prevailing direction during the winter. . The A.S.H.A.E. Technical Advisory Committee on Weather Design Conditions has recommended the adoption for heating load calculations of an outside design temperature which is equalled or exceeded during 97\ percent of the hours in December, January, February and March. Complete design temperature data based on this formula are not available, but Col umn 8, Table 1, lists this recommended design temperature based on airport station readings for the period indicated, generally the five years, 1935 1939. In most cases these stations are outside of the city and these data apply primarily to rural areas. In general the use of the airport data for buildings within an adjacent city will not make an appreciable difference in design load. Because of the limited data available in Column 8 of Table 1, design temperatures in common use are listed in Column 10 for the United States. Many of those values were furnished by A.S.H.A.E. members, the re mainder were taken from an ACRMA Bulletin,1 manufacturers' publica tions, and other sources,2 and a few were estimated. The map in Fig. 1 shows isotherms of outdoor winter design temperature which are based on the values in Column 10 of Table 1 with some modifica tions where other data indicated that Column 8 furnishes a more reasonable design temperature. These isotherms have also been modified slightly u* accordance with the elevations of the various cities. The isotherms are drawn on 10 deg temperature intervals, in most cases, and are so placed that interpolation between isotherms will provide the proper design temper ature for cities between the isotherms. Thus, a city located half-way be- Heating Load 251 Table 1. Winter Climatic Conditions* Col. 1| Col. 2 Station1* COL. 3 Col. 4 Ele - VA- TIONv Period Record** FT Col. 5 Low- EST Temp. on RecOHDd F Col. f Aver- An- NTJAL Min. Temp. e "F Col. 7 Win- TER Temp.1 F Col. 8 Desic N Dry Bulb Temp onTA 974% Basis K *F Col. 8 WlNI> VEL. 4 T DebigN Temp. i Mph Col. 1 Dbsig DryBulb Temp IN COMMO Use* *F 0 " n Col. 11 Avg. Wind Vel. Dec. Jan*. Feb.* Mpb - Ala.... Anniston........... Birmingham... Birmingham... Mobile.......... ;.. Mobile................ Montgomery... Montgomery... Aria.... Flagstaff.......... .. Kingman............. Phoenix............. [ Phoenix.......... * ] Tucson............... [ Tucson.................. Winslow............... Winslow............... Yuma................... Ark.... Fort Smith..... Fort Smith......... Little Rock........ Cal.. Little Rock........ Bakersfield-;*. Daggett Eureka.. Fresno... LeOS Angel Oakland.. Sacramento.. Sacramento.. Col... Denver.. Denver.. Conn. D.C... Fla. Ga... Miami. Pensacola.......... Pensacola........ .. Tampa... Tamp .....![ Titusville........ .. ..C 733 1893-1947 ..C 711 1893-1945 A 615 1939-1947 1872-1947 1940-1947 C 293 1872-1947 .A 226 1938-1944 1899-1947 1935-1939* 1895-1947 1937-1947 Up to 1946 1935-1939** C 4853 Up to 1946 .A 4899 1932-1947 .C 146 C 545 1876-1946* 1882-1945 .A 463 1945-1947 C 451 .A 282 1879-1942 1942-1947 .A 499 ."A 740 A 1925 1937-1946* 1931-1947 1935-1939* C 115 1886-1947 C 387 1887-1939 A 281 1939-1947 C 534 1877-1947 A 21 1929-1947 C 341 1877-1934 A 346 1944-1947 A 579 1935-1939* C 116 1877-1947 A 22 1938-1947 C 90 1871-1940 A 34 1939-1947 C 164 1875-1947 C 100e Up to 1946 A 124 1935-1939* C 5398 1871-1947 A 5379 1934-1947 C 4587 1889-1945* C 4770 1889-1938* A 4810 1939-1947 C 229 1905-1940 A 20 1940-1947 C 180 1872-1946* i 17 1943-1947 C 128 1871-1947 \ 20 3 23 : 104 1935-1939* 1922-1947 1871-1947 K 29 1938-1947 3 23 1871-1947 i 48 1939-1947 3 253 i 13 " 67 1896-1947 1940-1947 1879-1947 i 113 ? 111 i 12 52 1943-1947 1890-1940* 1941-1946 1935-1939* 1020 I878-J945* 195 1871-1946* 424 1939-1947 -10 -10 -1-10 13 -59 -25 8 16 21 6 19 -19 -18 22 -15 7 --12' 7 19 21 20 17 23 28 23 17 25 17 17 22 25 34 27 -21 -27 -15 -4 -15 18 10 16 41 42 27 28 7 20 19 3r 18 19 -15 29 26 52.3 53.8 51.8 58.9 56.4 35.9 59.5 57.7 57.2 57.2 43.6 43.5 62.5 50.4 51.6 55.5 57.5 49.3 53.8 59.3 51.9 53.9 52.9 53.0 54.2 53.5 39.0 37.0 .9 41.1 36.4. 43.4 60.9 62.0 60.6 73.1 72.5 71.4 59.7 66.0 51.3 54.2 21 7.4 30 8.5 22 8.6 31 5.6 30 6.3 6 7.5 21 6.6 33 5.6 35 4.9 27 8.5 4.5 36 7.5 32 7.1 43 5.8 29 8.3 8.8 2 6.4 4 8.3 11 8.1 14 7.4 31 7.0 45 7.3 38 6.5 22 10.2 5 10 15 10 -10 25 25 -10 30 10 5 25 _-- 8.0 9.9 7.5 5.4 5.2 6.7 8.3 8.3 30 7.3 25 5.4 35 6.4 30 6.1 30 35 35 25 -10 -15 -20 0 0 0 25 25 45 35 20 30 7.2 6.3 7.5 7.5 4.4 7.9 8.7 9.4 7.8 8.4 9.0 10.6 10.1 10.9 8.6 10 11.7 10 6.5 408 899-1947 432 939-1947 54.7 15 6.7 Idaho.. Boise...........' ' ' Boise............. Burley... Idaho Falls........ A Lewiston............. ' `' r* Pocatello......... c, Pocatello......... ;;::A Cairo....... q Chicago.............. Blank e 115 871-1945 56 939-1947 2818 864- 939* 2849 939-1947 4150 935-1939* 4744 935-1939* 763 900-1944 4522 899-1947 4467 : 938-1947 319 ] 872-1947 601 (Up to 1946 - - --18 --23 --28 --23 - - 58.5 56.7 40.3 39.8 36.9 1 42.7 -12 37.1 35.0 46.4 37.6 29 7.7 20 9.5 -10 5 4.5 2 8.8 -7 7.6 9.1 5 4.1 6 7.2 -5 8.9 0 9.8 -10 12.0 252 CHAPTER 12 -1956 Guide State Table 1. Winter Climatic Conditions*--(Continued) Col. 2 r Station* . Ele- va TION* Col. 4 Period ARec0oFrd*1 Col. 5 Low est Temp. on Rec ord*1 F Col. 6 Col. 7 Col. 8 Co1. 9 Col. 10 Col. 11 Aver age An nual Min. Temp.* Avg. Win ter Temp.* Design Dry- Wind Bulb Vel. at Temp. onTAC Design TEMP.h 97*% Basis8 Design Dry- Bolb Temp. IN Common U8E* Avg. Wind Vel. Dec. Jan.. Feb.1 *F F Mph >F Mph 111.. Chicago....................... A Moline..........................A Peoria...........................A Springfield.................C Springfield................ A 615 594 660 603 608 1935-1939* 1935-1939* 1935-1939* 1879-1947 1930-1947 Evansville.................. C 464 1897-1940 Fort Wayne...............C 885 1911-1941 Helmer........................ A 970 Indianapolis............. C 816 1935-1939* 1871-1946* Indianapolis............. A 800 Terre Haute..............C 1146 1932-1946* 1893-1946* Iowa.. Terre Haute............. A Charles City.............C Davenport.................C Des Moines................C 589 1023 648 805 1891-1945* 1872-1947 1878-1945* Des Moines___ ... .A 979 Dubuque....................C 740 1935-1939* 1874-1947 Keokuk............. ;. ..C 637 1871-1945* Sioux City..................C 1093* 1889-1944 Sioux City'............. -A 2098 1940-1946* Concordia. ............... C 1425 Dodge City.............. C 2515 1885-1947 1942-1947 Dodge City...............A 2599 1874-1942 Topeka........................ C 991 1887-1947 Topeka.... ................A 883 1946-1947 Wichita........................ C 1497 1888-1939 Wichita........................ A 1423 1939-1947 Ky.. Louisville................. C 563 Louisville...................A 544 1871-1947 1937-1947 La... New Orleans............ C 85 1874-1947 New Orleans............ A 8 1937-1947 Shreveport................ A 179 1935-1939* Maine Eastport......................C 100 Portland..................... C 70 1873-1947 1885-1940 Portland..................... A 66 1940-1947 Md... Baltimore...................C 114 Baltimore...................A 43 1871-1947 1935-1939* Boston......................... C 356 1870-1935* Boston......................... A 45 1936-1947 Nantucket.................C 45 1886-1947 Nantucket.................A 48 1946-1947 Mich.. Alpena......................... C 615 Up to 1946 Detroit............... 1000 1873-1933 Detroit............... 632 1935-1939* Eecanaba... ... 645 1878-1945* Grand Rapids 706 1891-1946* Lansing............ 1910-1947 863 1940-1947 Marquette............. ..C 721 1874-1947 Sault St. Marie.. c 724c 1888-1942* Minn.. Duluth................. ..C 1133 1874-1947 Duluth................. ..A 1413 1942-1947 Minneapolis------ ..G 945 1890-1947 Minneapolis.... 873 1938-1947 St. Paul............... ..C 951 1871-1933 St. Paul................ A 708 1937-1947 Miss.. Meridian.............. ..O 410 '1889-1947 Meridian.............. ..A 298 1939-1947 Vicksburg........... ..C 316 1874-1947 Vicksburg........... A 266 1941-1947 Columbia............ 739 1889-1947 Columbia............ A 787 1939-1947 Kansas City -- ..G 741* 1889-1940 Kansas City-- A 780 1935-1939* St. Louis.............. ..G 646 1871-1947 St. Louis............. ..A 597 1930-1947 Springfield......... ..A 1270 1935-1939* Billings................. A 3584 1935-1939* Butte..................... 5700c 1894-1931 Butte..................... ...A 5538 1932-1947 Havre................... G 2498 1880-1947 Helena.................. G 4175* 1880-1940* K&lispeU.............. G 3004 1897-1947 Miles City......... ...G 2400 1892-1942* Miles City........... ...A 2629* 1935-1939* Neb... Lincoln............... ...G 1189 1887-1947 -20 -24 -19 -18 -24 -25 -18 -18 -11 -34 -27 -30 -32 -27 -35 -24 -25 -26 -26 -25 -21 -22 -10 -20 -15 7 19 -23 -21 -39 -7 -18 -14 -6 12 -28 -24 -32 -24 -25 -10 -27 -37 -41 -33 -34 -31 -41 -26 -6 . -7 - -1 10 -26 -18 -22 -22 -19 -34 -52 -57 -42 -34 -49 -29 -6 35.1 34.6 -8 37.3 -7 39.8 37.7 j 45.1 37.6 -6 39.6 39.0 --5 41.7 -22 -13 -17 -12 --20 -13 -- 10 31.2 37.0 36.4 35.4 34.6 39.3 .32.6 40.7 41.4 42.1 -4 43.6 -5 45.1 43.9 26 61.6 60.6 16 -15 31.5 -6 33.8 33.0 8 44.3 44.1 -3 38.1 39.3 -12 29.6 -11 36.5 27.3 36.0 34.0 -13 -22 -28 -23 28.3 26.0 24.3 29.4 -25 29.0 -18 15 54.8 ' 18 -6 56.8 53.6 42.3 41.1 41.5 -2 -5 -30 -36 -24 -17 -30 -13 43.6 42.3 34.9 30.7 27.0 28.4 31.6 31.6 29.0 27.6 37.0 -3 11.7 -6 10.8 -6 10.7 -2 11.6 -1 11.5 2 11.4 -8 14.5 6 14.7 9 8.8 36 12.8 27 8.9 13 8.9 8 12.3 4k 11.0 -15 9.9 2 10.6 3 20.8 8 11.0 -17 9.1 -18 4.8 -18 8.4 11.7 -10 10.8 -10 8.3 -10 11.9 9.6 -10 10.4 -10 11.3 10.2 7.9 --15 10.5 -15 10.1 -20 7.1 8.3 -20 11.5 -10 7.7 -10 10.6 -10 9.2 -10 12.4 0 9.8 20 8.6 20 -10 . --5 8.8 12.6 10.4 8.2 0 12.4 0 14.8 -10 11.0 --10 12.0 -IS 9.5 -10 12.1 -10 9.8 -10 --20 --25 -20 -20 10 10 -10 -10 0 -25 --20 -30 --35 -10 10.6 8.9 13.4 11.3 9.5 6:3 8.3 8.9 10.3 11.8 11.0 12.4 9-4 7.4 5-2 5.6 10.6 Heating Load 253 Table 1. Winter Climatic Conditions*--(Continued) State Col. 2 Station*1 Col. 3 Col. 4 Ele va tion* Period Record*1 ft Col. 5 Low. EST Temp. on RecORDd F Col. 6 Aver age An nual Min. Temp F Col. ' Avg. Win ter Temp. F Col. i Col. 9 Col. 10 Col. 11 Desioi Design DryBulb oTneTmApC. , 97*% VDWeeilsn.idga.:_f Temp.1 DryBulb Temp. ~ComINmon Avo. Wind. Vel. Dec. Jan. Basis8 Use1 Feb.* cF Mph F Mph A 1185 1933-1947 North Platte. C 2815 1874-1947 North Platte. A 2788 1935-1939* 2 1219 1873-1935 A 1009 1935-1947 C 2627 1889-1947 Nev... Elko.. A 5079 1935-1939 A 1882 1937-1947 Reno.. 2 4588 1905-1942 Reno.. A 4417 1940-1947 2 4293 1871-1947 N. H. 2 343 1871-1941 Concord. A 359 1941-1947 N. J.. 2 45 1874-1947 A 20 1935-1939* A 15 1931-1947 3 19 1914-1938* N. M.. Albuquerque. 3 144 1866-1946 3 5022 1931-1933 Albuquerque-r- A 5319 1933-1947 Ei Morro......... A *7120 1940-1947 Rodeo............... A 4116 1935-1939* 2 3643 1905-1947 N. Y... i. 4054 .1935-1939*2 114 1874-1947 A 280 1938-1947 Binghamton.. 2 915 1891-1946 Binghamton.. A 836 1942-1947 Buffalo........... .. 2 693* 1873-1945* Buffalo............. i 726 1935-1939* 3 458 1889-1947 Elmira.. l 948 1935-1939* Ithaca........ v 3 888 1879-1937 New York.. 3 425 1871-1947 3 363 1871-1943 Rochester. 3 609 1872-1947 Rochester. . 560 1935-1939* Syracuse... 3 465 1928-1940 Syracuse... N. C.. Asheville.. 404 1940-1947 3 2280 1902-1947 Charlotte.. 3 809 1878-1947 757 1939-1947 Greensboro.. 896 1928-1947 Raleigh.......... , 405 1944-1947 Raleigh.......... 446 1935-1939* Wilmington,. N. D.. Bismark........ 78 1871-1947 1675 1875-1940 1655 1940-1947 1481 1904-1947 Dickinson. 2599 1935-1939* Fargo.......... 900 1935-1939* Ohio. Williston... Akron........... 830 1935-1939* 1919 1879-1947 1887-1931* Akron........... 1040 1935-1939* Cincinnati.. 772 1870-1947 488 1931-1947 669 1871-1946* 813 1930-1946* 812 1878-1946* 820 1939-1947 1086 1883-1943 1002 1940-1947 608 1878-1946* Ua... Toledo.............. .....A Ardmore____ . . . . . .A Oklahoma City....C 668 626 762 1264 1871-1947 1940-1947 1935-1939* 1890-1947 Ore... Oklahoma City....A 1311 lulsa................... Waynoka...... a a' 686 1529 Arlington....................A 881 Baker ^er........... n 3501 3374 ugene................. C 366 Eugene........................ a 368 Medford.:........... C 1428* 1939-1947 1932-1947 1935-1939* 1935-1939* 1889-1947 1939-1947 1890-1942* 1942-1947 1911-1929 -26 -35 -32 -21 -38 8 -19 -16 -36 -35 -37 -9- -14 -11 -14 5 --6 -25 -29 -24 -22 -28 -17 -20 -43 -24 -14 -23 -22-16 -24 -26 -6 -5 -3 -7 -2 5 -45 -38 -46 -50 -20 -17 -14 -17 -5 -20 -15 -28 -11 -16 -16 -13 -17 -10 -5 -25 -19 -4 9 -10 -17 -i4 -22 16 -10 -15 6 35.6 35.4 36.4 33.6 53.8 41.7 38.0 33.2 42.3 41.2 2 42.0 44.3 -19 51.4 49.1 -11 35.2 -11 34.7 -4 34.8 -26 ? 29.5 -10 34.9 -3 41.1 -9 34.4 -4 35.1 34.8 6 46.1 12 50.6 46.4 13 50.0 18 -31 -33 54.6 25.3 22.9 21.7 -25.6 24.5 37.3 -2 43.0 -2 37.2 40.4 -3 38.2 40.4 38.0 -5 37.2 .35.7 2 47.9 49.0 -17 35.2 33.8 45.9 45.4 44.7 --4 23 10 13 0 5 :4 -i 22 17 20 -24 -20 -25 -30 9 7 6 4 4 18 14 13 10 7 3 -23 12.7 '4.0 : 5.3 9.5 11.6 8.4 9.2 9.6 14.0 8.0 11.9 8.9 7.5 7.8 8.5 7.1 12.4 10.9 11.9 10.6 S.O 13.8 10.5 12.1 9.7 14.7 11.3 11.3 7.8 6.4 5.3 10 -25 0 --10 0 0 --5 15 5 7.9 9.7 9.2 8.1 6.2 16.1 10.9 7.3 7.1 10.5 6.8 17.1 10.5 11.3 16.8 12.1 9.6 11.2 9.5 7.3 9.4 9.1 8.6 8.5 14.7 11.6 11.1 11.0 12.1 254 CHAPTER 12 1956 Guide Col. 1 State Table 1. Winter Climatic Conditions"--(Continued) Col. 2 Station^ ' (^OL. 3 Col. 4 Ele va tion* Period Record*1 FT Col. 5 Col. 6 Low EST Temp, on Rec ord*1 Aver age An nual Min. ' 'BMP.* "F F Col. 7 Col. 8 Dol. 9 Col. 10 (7ol. 11 IDesign Design Avo. Win ter Temp.1 Drt- Wind. Bulb /EL. AT cTN9e7Tm*%Ap.C^iDrEeMsipg.nb DryBulb Temp, (Dominmpn Use* Avg. Wind Vel. Dec. Jan. Feb. F F Mph F Mph Ore____ Medford................. .A 1343 C 98 1929-1947 1874-1947 A 25 1940-1947 C 523 1877-1947 Pa..'... A 2219 C 771 1943-1947 1873-1946 .A 736 1935-1939" C 335* 1888-1938* Harrisburg ., , A 339 1935-1939* Pa......... Philadelphia... .0 200 Philadelphia........ .A 18 1871-1947 1940-1947 C 929 1875-1947 A 1284 1935-1947 C 311 1913-1947 c 877 1901-1947 Sunbury................ A 448 1935-1939* R. I...- .C 46 1881-1947 C 77 1904-1947 S. C. ..c 59 1871-1947 A 51 1940-1947 ..c 401 1887-1947 A 227 1939-1947 ..C 1006* Up to 1946 S.D... ..c 1342 1881-1938 ..A 1287 1938-1947 Rapid City........... ..C 3309 1887-1947 Rapid City......... A 3220 Chattanooga........ ..C 952 1939-1947 1879-1947 Chattanooga........ ..A 675 1940-1947 ..C 1024 1871-1942 ..A 1007 1942-1947 Memphis............. ..C 348 1872-1941 Memphis............. ..A 267 1941-1947 ..C 714 1871-1947 ..A 610 1939-1947 Texas.. ..C 1748 ..A 1756 1885-1944 1940-1947 ..C 3686 1892-1941 ..A 3595 1941-1947 ..C 625 1897-1942 ..A 625 1942-1947 Brownsville.... ..G 140 1922-1943 Brownsville.... ..A 25 1943-1947 Corpus Christi. ..C 21 1887-1942* Corpus Christi - ..A 45 1943-1946* ..C 732 1913-1940 ..A 520 1940-1947 ..C 1020 1905-1947 ..C 3792 1880-1942 ..A 3956 1939-1947 C 708 1898-1939* Fort Worth......... ..A 728 1940-1947 ..C 128 1871-1947 ..A 9 1939-1947 ..C 198 1888-1947 73 1932-1947 < 555 1881-1947 Port Arthur.... ( 64 1917-1947 ...J 21 1944-1947 .. L 770 1885-1941 San Antonio___ ..J 800 1942-1947 ..J 513 1931-1947 Utah. Wink...................... ...J 2811 Milford................. ...J 5095 ...C, 5472 1935-1939* 1935-1939* 1901-1947 ...C 4346 1874-1947 ...J 4254 1928-1947 Vt.... Burlington.......... ...c; 409 1884-1943 Burlington.... ...Ai 335 Va.... Cape Henry... ...(; 24 1943-1944 1874-1947 Lynchburg------ ...(; 644 1874-1944 ' Lynchburg____ ...Al 951 ^ 91 1944-1947 1871-1947 Richmond........ ...i D 180 1897-1947 .... k 172 1929-1947 ... i 1194 1935-1939* Wash. Ellensburg . .1k 1731 1935-1939* -3 -2 3 -6 -10 -16 -14 -11 1 -20 -16 -14 -19 -10 -17 7 14 -2 9 -5 -43 -30 -34 -27 -10 6 -16 1 -9 1 -13 -15 -6 -9 -16 --7 -1 . 13 12 30 11 : 23 -3 5 12 --5 11 -8 4 8 14 5 5 -6 11 4 -17 --32 --29 -5 -7 2 --3 18 46.1 44.3 19 46.7 33.7 -3 37.3 3 39.9 6 42.7 -2 : 40.9 .38.7 41.2 37.7 40.1 1 37.5 22 57.4 55.0 19 54.4 -26 49.2 28.2 -21 33.4 9 50.3 4J .8 46.8 9 51.1 5 48.5 53.9 0 45.2 58.4 29 66.8 63.7 13 55.6 60.6 16 53.5 12 55.1 61.7 22 61.0 57.1 21 60.6 -15 -17 8 15 36.3 40.0 38.3 31.5 49.2 46.8 49.3 47.0 36.2 23 . 22 0 6 7. 6 7 19 19 14 - 20 11 26 33 32 23 15 21 4.3 8.0 13.5 12.1 9.0 10 10 --5 12.1 7.1 6.9 6.2 8.9 7.3 10.4 12.9 8.8 8.6 15 10 10 -20 -20 10 . 15 -10 20 a5n0 20 0 15 10 10 20 . -20 20 20 8.5 -io -10 10 5 15 15 7.1 3.8 __________ 7.3 3.9 13.6 7.6 11.0 11.6 9.0 7.6 20.6 12.1 10.5 8.0 8.4 10.7 8.0 7.7 7.2 9.3 10.1 12.1 8.3 10.4 11.0 10.6 9.0 10.5 11.2 8-0 10.7 8.3 9.0 7.8 11.6 14.0 8.1 12-1 8.1 Heating Load Table 1. Winter Climatic Conditions*-- (Continued) 255 Col. Col.2 Col. 3 Col. 4 State Station1*. Ele va tion Period OP Record*1 ft Wash.. North Head............. C 199 Seattle ............ C 104 Seattle................ A 47 Spokane............... C 2030 Spokane................... A 1974 Tacoma...................... C 279 Tatoosh Is............... C 110 Yakima C\ 1160 Yakima A 1066 W. Va.. Elkins...................... C 1969 Parkersbure........... C 685 Wise... Green Bav............ O 598 La Crosse.................. C 725 La Crosse................ A 677 Madison......................C 1008 Madison....................A 884 Milwaukee.......... O 744 Milwaukee............... A 707 Wyo.. . Cheyenne.................. C 6144 Cheyenne.................. A 6161 6448 Lander...................... A 5568 Rock Snrinn A 6746 1884-1947 1890-1947 1928-1947 1881-1941 1941-1947 1897-1947 1888-1947 1938-1946 1944-1947 1898-1944 1888-1947 1886-1947 1872-1947 1943-1947 1858-1947 1935-1939d 1870-1947 1927-1947 1873-1935 1935-1947 1891-1946 1946-1947 1932-1942 m%Col. 5 LowEST Temp. on RecORDd F Col. 6 Col. 7 Col. 8 Col. 9 Col. 10 Aver- j Design Design age AnNOAL Min. Temp.* WinTemp.1 . DryBulb Temp. OnTAC Wind Vel. at Design DryBulb Temp, Temp*1 in Common F F Basis* Use* F Mph *F. Col. Avg. Wind Vel. Dec. Jan. Feb.' Mph 11 3 3 -30 -7 7 7 -24 -4 -28 -27 -36 -43 -28 -29 24 20 -5 -8 s -1 -18 -21 -25 -29 -38 -34 -40 -14 -33 -12 -18 -12 46.4 46.3 45.1 37.7 44.9 45.4 39.8 39.4 42.9 29.8 31.7 30.5 31.4 33.4 29.0 33.6 30.0 30.1 . 24 4 -17 -8 -6 -3 -7 20 15 6.3 5.1 "IS , 15 - - 15 ; ^5, . -10~ -10 -20 : - -25 6.9 , 9.1 -15 11.9 . 11.1 -15 -15 `I -18 16.1 9.8 6.2 8.0 18.9 4.1 6.2 7.2 10.5 9.3 10.1 12.1 13.3 3.9 Prov. op Can ada Station1* Ele- va tion0 Period op Record*1 Alta.. Calgary........................A fcdmoDton................. A Grande Prairie___ A 0 B. C.. Lethbridge.................A McMurray............ .. .A Medicine Hat...........A Estevan Point......... C 3018* 12160 Fort Nelson...............A Penticton.............. A Prince George.......... A Prince Rupert......... C Vancouver................. A Man.., Victoria.......................C Brandon......................c Churchill... A The Pas..............:;:.A N. B... Winnipeg.....................A Campbellton............ C Fredericton................C Moncton................. A Nfld... Saint John ... C Corner Brook.. ...C Gander.................. a Goose Bay................. a St. John's...................A n.w.t. Aklavik....................... c Fort Norman........... C Frobisher................. a Resolute.......... c N.S... Yellowknife.............. A Halifax.................. n Halifax............. "a !ydny.................... '.'.A Oat.... Yarmouth___ A Fort William..........A Hamilton....................q Kapuskasing. .... A Kingston.................... c Kitchener................ Q London.................'.['.A 1121* 2218 170r 22* 228* 1200* 115* 894 786 42 164 248 119 40 482 144 463* 30* 300 68 56 682 83 138 197* 136 644 303 752 340* 1100 912 1921-1950 1921-1950 1942-1950 1921-1950 1921-1950 1921-1950 1924-1950 1938-1950 1921-1950 1921-1950 1921-1950 1938-1950 1921-1950 1921-1950 1932-1950 1921-1950 1921-1950 1938-1950 1923-1950 1921-1950 1921-1950 1933-1950 1937-1950 1942-1950 1926-1950 1927-1950 1926-1950 1942-1950 1948-1950 1942-1950 1921-1950 1944-1950 1921-1950 1921-1950 1921-1950 1939-1950 1921-1950 1921-1950 1921-1950 1921-1950 Low est Temp. on Rec ord*1 *F BWinteb Design Temp1* l i% F 2H% F S% "F 10% *F -46 -55 -62 -45 -64 -49 7 -61 -16 -58 -3 0 6 -49 -50 -54 -44 -31 -38 -36 -21 -25 -16 -35 -10 -62 -65 -49 -55 -60 -21 -11 -23 -11 -41 -17 -53 -31 -29 -27 -31 -39 -47 -32 -51 -34 22 -47 -42 12 13 20 -40 -43 -42 -35 -24 -23 -12 -12 -10 -30 -2 42 -54 -44 -53 51 1 -29 -6 -42 -35 -29 -39 -33 -43 -39 -38 -32 -48 -42 -41 -35 14 17 -42 -38 -14-- .-6 -43 -32 58 8 11 12 15 -36 -32 -43 -42 -43 -39 -33 --29 -14 -11 -9 -6 -11 -8 -6 -3 -4 -1 -6 -3 -29 -26 -1 1 -50 -46 --46 -42 --51 -47 -45 -42 -49 -47 04 -3 2 -7 1 47 -30 -24 -4 0 -34 -30 -15 -11 -8 -3 -5 -1 -25 -29 -34 -28 -37 -31 21 -33 -1 -25 12 15 19 -28 -40 -30 -25 -8 -3 -5 0 2 0 -24 4 -43 -39 -43 -40 -45 7 5 4 10 -20 5 -27 -6 2 3 -16 -21 --27 -19 -30 -22 27 -28 4 .-16 18 21 25 -24 -37 -26 -21 -3 2 0 5 6 4 -20 7 -39 -35 -39 -36 -41 11 9 8 13 -15 10 -22 -1 7 8 Avo. Wind. Vbl. 10.1 7.6 7.9 15.0 9.0 9.9 3.7 7.2 8.0 7.7 12.3 14.7 6.4 12.0 9.2 14.9 13.8 17.2 10.3 19.3 9.6 12.4 13.1 1 1 256 CHAPTER 12 1956 Guide COL. 1 Pbov. op CanADA Table 1. Winter Climatic Conditions*--(Concluded) Col. 2 Station1* Col. 3 Ele va tion FT Col. 4 Pebiod of Record Col. 5 Low- E8T Temp. on Rec ORD *F Col. 6 Aveb- AQE An nual Min. Temp. F Col. 7 Col. 8 j.CoL. 9 Col. 10 r?nL. n Winter Design Temp. SM% 5% 10% F "F F "F Avg. Wind Vet. Mph Out.... P. E. I. Que.... Sask.-* y. t... ..A Ottawa................ A Peterborough... ..C Sioux Lookout. . A Sudbury............. C Timmins............. c ..c ..A Windsor.............. ..A Charlottetown.. O ..o Knob Lake........ ..A Mont Joli............ A .0 Montreal............ A Port Harrison.. C ..C Seven Islands.. A Sherbrooke........ C Three Rivers... . C Prince Albert... ..A ..A Saskatoon........... ..A Swift Current. . ..A Dawson............... ..O Whitehorse......... ..A 1210* 339 648* 1227 837 1100 379 578 637 74 375 1605 150 187 98 66 296 190 620 50 1414* 1884 1645* 2677 1062 2289* 1925-1950 1921-1950 1921-1950 1931-1950 1921-1950 1921-1950 1921-1950 1938-1950 1921-1950 1921-1950 1932-1950 1948-1950 1943-1950 1921-1950 1942-1950 1942-1950 1921-1950 1944-1950 1921-1950 1921-1950 1021-1950 1921-1950 1021-1950 1921-1950 1921-1950 1941-1950 -46 -38 -38 -50 -45 -55 -22 -24 -10 -23 -42 -59 -28 -29 --28 -49 -32 -43 -39 -43 -56 -54 -54 -54 -73 -62 -33 -26 -21 -39 -34 -7 -13 -2 -11 -31 -48 -16 -20 -42 -19 -24 -24 -46 -39 -41 -34 -54 -51 -24 -18 -15 -38 -21 -30 -4 -9 0 -6 -23 -44 -14 -12 -14 -43 -16 -23 -15 -17 -48 -39 -45 -39 -62 -49 -20 -15 -11 -33 -17 ` -26 0 -4 3 -3 -19 . -40 -11 -9 -11 -39 -12 -20 -12 -13 -41 -34 -37 -33 -56 -43 -16 -11 -6 --29 -12 -22 5 1 7 0 -16 -34 -8 -6 -8 -35 -9 -17 -9 -10 -37 -30 -33 -29 -50 -37 -11 -7 -1 -24 -5 -17 10 6 11 4 -11 -30 -3 -2 -4 -31 -4 -12 -6 -5 -30 -25 -26 -24 -39 -26 11.3 11.1 8.5 14.1 12.1 12.3 11.3 8.2 13.3 12.3 13.1 13.4 12.4 8.2 4-9 12.1 9.7 14.6 8.7 United States data compiled from U. 8. Weather Bureau Records for years indicated, and Canadian data from the Climatological Atlas of Canada for years indicated. b Col. 2. The stations followed by letter A are airport stations; all others are city office stations and are followed by letter C. Col. 3. The elevations marked c are ground elevations of the station. All other elevations given are the actual elevations of the thermometer bulb above mean sea level. ^ Col. 4. The periods of record indicated apply only to the lowest temperature ever recorded shown in Col. 5, and generally extend from a summer month of the first year indicated through the spring months of the last year indicated. The periods marked by * terminated in December of the year indicated ^ Average of readings oif one lowest temperature obtained for each year for period of record. For Canada, in some cases, more than one location have been used. *For period October to April, inclusive. B It should be noted that Col. 8 in the United States section of the table applies only to airports, as these data for city stations are not available at this time. The temperature shown is the minimum hourly out-door temperature which has been equalled or exceeded 97>4 percent of the total hours in December, January and February for the period of record. It as pointed out that in most cases the airport stations are outside of the city and these data would apply primarily to rural areas. b Col. 9 indicates the maximum wind velocity which occurred at temperatures the same as, and lower than, the temperatures shown in Col. S. , ' 1 Col. 10 records design temperatures in use by A.S.H A.E. Members as reported by Chapter Secretaries for the various stations. Where these were not available the design temperatures from an A CRM A publica tion and various other sources have been inserted. ' * The wind , velocities indicated in Col. 11 were furnished by the U. S. Weather Bureau and corrected through Feb. 1948. k A bulletin prepared by A.S.H.A.E. and U. S. Weather Bureau for annual weather data of city of Detroit indicates 6 as design temperature based on Dec. to March, inclusive. . m Computed for Reading by Karl Shelley and O. F. Smith. n The winter design temperatures for Canadian cities for bases of 1, 2H, 5 and JO percent are the Fahrenheit temperature values at or below which 1, 2J-i, 5 and 10 percent of the January hourly outdoor temperatures occur, for the 10 years 1941 to 1950. The tabulated values are based on hourly temperature observations `or some of the cities and upon the difference between the mean monthly temperature and the design temperature for the remainder of the cities listed. - Most of the wind speeds are based on periods ending in 1947 which are somewhat shorter than the periods for the minimum temperatures. The three months, December, January and February were used- Heating Load 257 F i o . 1 . s o t h e r m s o p W i n t e r O u t d o o r D e s i g n T e m p e r a t u r eI o- f 5 P althuourgahnsaha1UrpTcihsaonthgeesrmins ewleovualdtionnormmuaslltybheatvaekeandeinstiognctoenmsipdeerraattuioren m mountainous areas where large differences in climate may occur within relatively small distances. This map will be of considerable value in selectln design temperatures for cities and towns not listed in Table 1. The design temperatures in Column 10 of Table 1 are often used with a aesign wind velocity of 15 mph. However, Column 11 shows that the 258 CHAPTER 12 1956 Guide average wind velocity from December through February is 15 mph or higher in only 7 of the cities listed and Column 9 shows that a wind velocity of 15 mph did not occur in any city listed for temperatures equal to or lower than those shown in Column 8 for the years 1935-1939. Conse quently, it will often be desirable to modify the U values in Tables 6 to 9 and 15 to 19 of Chapter 9 to correspond to lower wind velocities. Correc tion factors for wind velocities can be found in Table 21 of Chapter 9. Column 6 in Table 1 lists the average annual minimum temperature which is the average of readings of the one lowest temperature occurring for each year the weather station has been in existence. A comparison of the temperatures listed in Columns 6, 8, and 10 of Table 1 offers some guid ance in selecting a suitable outdoor design temperature for particular cities. For the 63 cities in the United States having temperatures listed in all three columns the average annual minimums in Column 6 average 2.3 deg warmer than the design temperature in common use listed in Column 10 whereas the design temperatures in Column 8 average 11.0 deg warmer than those in Column 10. There are variations of 6 deg or more in either direction from these average differences, however, for a few cities in this group. Designers are cautioned against attempting to compensate for internal vagrant heat sources in a structure, the heat generated by electrical equip ment, the approximations that may exist in heat transmission factors and infiltration rates, and the safety factors used in selecting heating plant capacity by adjusting the design temperature difference between indoors and outdoors. These factors should be accounted for by more careful analysis of their existence and magnitude in computing the heating load that must be carried by the heating plant itself. , INSIDE TEMPERATURES The inside air temperature which must be maintained within a building is understood to be the dry-bulb temperature at the breathing line, 5 ft above the floor, or at the seating level, 30 in. above the floor, and not less than 3 ft from the outside walls. Inside air temperatures usually specified, vary in accordance with the intended use of the building. Table 2 presents values which conform to good practice. The proper dry-bulb temperature to be maintained depends upon the relative humidity and air motion, as explained in Chapter 6. In other words, a person may feel warm or cool at the same diy-bulb temperature, depending on the relative humidity and air motion. The optimum winter effective temperature for sedentary persons, as determined at the A.S.H.V.E. Research Laboratory, is 67-68 ET. As explained in Chapter 6 for so-called still air conditions, a relative humidity of approximately 50 percent is required to- produce an effective temperature of 68 ET when the diy-bulb temperature is 72.5 F. However, even where provision is made for artificial humidification, the relative humidity is seldom maintained higher than 40 percent during the ex tremely cold weather, and where no provision is made for humidification, the relative humidity may be 20 percent or less. Consequently, in using the figures listed in Table 2, consideration should be given to the actual relative humidity to be maintained, if provision is to be made for humidifi' cation. If no humidification is to be provided, the higher temperatures Heating Load 259 may not even produce comfort on cold days; if humidity is to be main tained at 50 percent, the lower temperatures will apply. - ' In rooms having large glaiss areas, when sun is not shining, or in rooms with walls having a'high transmission coefficient, the lowered surface tem perature will cause a feeling of coolness even though the air temperature in the room is at or above the temperatures indicated in the table. In rooms of this character, it is desirable to design for even higher temperatures than those listed, unless a compensating lugher temperature surface is installed to offset the low temperature surfaces. Table 2. Winteb Inside Dby-BolbTemperatubes Usually Specified'1 Type op Building Schools-- Class rooms................................. Assembly rooms......................... Gymnasiums............................... Toilets and baths...................... Wardrobe and.locker rooms.. Kitchens......................................... Dining and lunch rooms........ Playrooms___ ;............................. Natatoriums................................ Hospitals-- - - --- Private rooms................... .. . Private rooms (surgical)., Operating rooms.................. Wwds........................................ Kitchens and laundries... Toilets....................................... Bathrooms...;..................... Deg F Ttpe op Building . 70-72 68-72 55-65 70 65-68 66 65-70 - 75 70-72 70-80 70-95 68 66 68 70-80 Theaters-- Seating space.................... Lounge rooms............... Toilets.............................. . Hotels-- ` Bedroom* *nd hath* Dining room*............................. Kitchens and laundries___ . Rntlmom* ........................... Toilets and service mnmn ,,. Homes............................................ ............ Steam baths........................................... Factories and machine shops Foundries and boiler shops. . Deo F 68-72 68-73 68 70 70 66 66-68 68 70-72 65-68 68-73 120 110 60-65 50-60 ' * The most comfortable dry-bulb temperature to be maintained depends on the relative humidity and air motion. These three factors considered together constitute what is termed the effective temperature. (See Chapter 6.) When relative humidity is not controlled separately, optimum dry-bulb temperature for comfort will be slightly higher than shown in Table 2. The inside temperatures specified in Table 2 may be used for panel heated spaces as well as for spaces heated by warm air, radiators or con vectors. It is true that warm panel surfaces tend to produce a comfortable environment at a lower room air temperature than when warm panels are not present, but field experience in the United States has indicated that actual reductions in air temperatime are slight in operation. Temperature at Proper Level. In making the actual heat loss compu tations, however, for the various rooms in a building it is often necessary to modify the temperatures given in Table 2 so that the air temperature at the proper level will be used. By dir temperature at the proper level is meant, in the case of walls, the air temperature at the mean height be tween floor and ceiling; in the case of glass, the air temperature at the mean height of the glass; in the case of roof or ceiling, the air temperature at the mean height of the roof or ceiling above the floor of the heated room; and in the case of floors, the air temperature at the floor level. Temperature at Ceiling. The air temperature at the ceiling is generally mgher than at the breathing level due to stratification of air resulting from "he tendency of the warmer or less dense air to rise. An allowance for this act should be made in calculating ceiling heat losses, particularly in the case of high ceilings. However, the exact allowance to be made may be somewhat difficult to determine as it depends on many factors, including U) the type of heating system, (2) ceiling height, and (3) the inside- outside temperature differential. The type of heating sykem is par- 260: CHAPTER 12 1956 Guide tiCularly; important;, as the temperature gradient from .floor to breathing- level to ceiling may depend to . a .large extent ,on whether .direct radiation, unit heaters or warm air is used, and in the letter case> whether the air is moved mechanically or by gravity. The temperature of the heating medium is also a factor. ' r -- It is impracticable to establish rigid rules for determining the temperature difference to use in all cases. However, for residences and structures hav ing ceiling heights under 10 ft,. the comparatively small temperature differential between the breathing level and ceiling generally may be Table 3. Approximate Temperature Differentials Between Breathing Level and Ceiling, Applicable to Certain Types op Heating Systems" r>F, I Height ,(Fi): 60 Breathing Levee Temperature (5 ft Arove Floor) 65 70 72 ,74 - 76 78 80 . '90/: 10 n 12 .13 14 *15 : * 16 .17 - 18 -19 .20 '25 30 35 40 45 . 50 3.0 3.6 4.2 4.8 5.4 6.0 6.1 6.2 6.3 6.4 6.5 7.0 7.5 8.0 8.5 9.0 9.5 3.3 3.9 4.6 5.2 5.9. 6.5 6.6 6.7 6:8 6.9 7.0 7.58.0 8.5 9.0 9.5 10.0 3.5 3.6 3.7 4.2 4.3 4.4 4.9 5.0 5.2 5.6 ? 5.8 5.9 6.3 6.5 6.7 7.0 7.2 .. 7.4 7.1 7.2 7.3 7.4 7.5' 7.3 ~ 7.5 7.4 7.6 7.5 7.7 7.6 7.8 7`7 7.9 8.0 8.2- 8.4 8.5 8.7 - 8.9 9.0 9.2- f ' 9.4 9.5 9.7 - 9.9 10.0 10.2 10.4 10.5 10.7 10.9 3.8 4.6 5.3 6.1 . 6.8 7.6 7.7 - 7.8 7.9 8.0 8.1 8.6 9.1 9.6 . 10.1 10.6 11.1 3.9 4.0 4.3 . 4.5' 3.7 .4.8 5.1 5.4. 5.5 5.6 6.0 6.3- 6.2 ' 6.4 -.6.8 .7.2. 7.0 - 7.2 : 7.7 8.1- 7.8 8.0 8.5. 9.0 7.9 8.0 . 8.1 8.2 8.3 8.1 8.6 8.2 8.7 . . ;8 3 : 17-8.8 8.4 8.9 8.5- 9.0 9.1 , .. 9:2 9t3 - 9:4: '9.5`* 8.8 9.6 9:5 10.0 9.3 9.8 9.5 10.0 10:0 10.5 1101..501- 10.3 10.5 11.0 11.5 10.8 11.0 U.5 12.0 31.3 11.5 - 12.0 12.5 : * The figures in this table are based on an increase of 1 percent per foot of height above the breathing level - (5 ft) up to 15 ft and Mo of one degree for each foot above 15 ft. This table is generally applicable to forced air types of heating systems. For direct radiation or gravitywann air, increase values 50 percent to 100 percent. `. .. neglected without serious error. For higher ceilings, an allowance of approximately 1 percent per foot of height above the breathing level may be made for ceiling heights up to 15 ft and approximately yj of 1 deg per foot of height above this level. The values in Table 3 are calculated on this basis. For direct radiation and gravity warm air systems, the allow ance should be increased from 50 percent to 100 percent over those given in Table 3, These, rules should, however, be used with considerable dis cretion, and they do not apply, to some: types: of heating systems such as those using panel and baseboard'. radiation, where very low . temperature differences between: the; floor and the ceiling may exist. : ; Temperature at Floor Level. According to tests at the University of Illinois,3' 4> 6' 6 the temperature at the floor level ranged from about 2 to 6 deg below that at the breathing level, or somewhat greater than the difference between the breathing level and ceiling temperatures. Tests at the University of Wisconsin7 indicated; a somewhat smaller differential Between the floor and breathing level temperatures. As a general rule, $ the breathing level to ceiling temperature differential 's neglected (as with ceiling heights under 10 ft), the breathing level to floor differential may also be neglected, as the two are somewhat compensating, especially where both floor and ceiling losses are calculated for the.same space. In other cases, the 10 ft temperature differentials in Table 3 may be used in arriving at the floor heat loss, these differentials to be subtracted from the breathing level temperature. Heating Load 261 ` ATTIC TEMPERATURES " " ' ' - Frequently, it is necessary to estimate the attic, temperature, and in such cases Equation 1 can be used for this purpose: . . ' where ,. ' ^ AMA -4-' UA,V, -f AH + AkUfj a,uc + a;u, + A .11. + +,[/,' ; / , \ (1) tt = attic temperature, Fahrenheit degrees. - . ti = inside temperature'near top floor ceiling, Fahrenheit degrees. = to -- outside temperature, FaKrenheit degreea. . . . . i . ,. : Ac = area of ceiling, square feet. A, = area of roof, square.feet. . . _ ; .. /t = area, of net vertical attic1 wail surface, square feet- . A, = area of attic glass, square feet. .. Uc -- coefficient of transmission of ceiling,,based on-surface-conductance of 2.30 . (upper surface, see Chapter 9). . 2.20 = reciprocal of one-half the air space resistance.. . .. ' .. .... XJr -- coefficient of transmission of roof, based on surface conductance of 2.20 (lower surface, see Chapter 9). . """ " Ur, = coefficient of transmission of vertical wall surface. Uf = coefficient of transmission of glass. Example 1. Calculate the temperature in an unheated attic, assuming the follow ing conditions: f, = 70; lo =10; Ac = 1000; A, - 1200; A,, - 100; -A, = 10; U, = 0.50; Uc = 0.40; U,, = 0.30; U, * 1.13. Solution: Substituting these values in Equation 1; . . (1000 X 0.40 x 70) + 1Q[(120Q X 0.50) + (100 X 0.30) + (10 X 1.13)] * = (1000 x 0.40) + (1200 X 0.50) + (100 X 0.30)+ (10 X 1.13) 34,413 U= 1041 33.1 F. Equation 1 neglects the effect of any interchange of air such as would take place through attic vents or louvers intended to preclude attic con densation. However, according to tests,8 such venting of attics by means of small louvers or other small openings does not appreciably reduce the -attic temperature and may be neglected without serious-error. Neither does this equation take into consideration such factors as heat exchange between chimney and attic or solar radiation to and from the roof. Because of these latter effects, actual attic temperatures are fre quently higher than the calculated values using Equation 1.. The attic temperature may be calculated in the usual mariner by means of Equation 1, allowing the full value of the roof. The error resulting from this assump tion will generally be considerably less than if the roof were neglected (as is sometimes the practice) arid the attic temperature assumed to be the same the outside temperature. When relatively large louvers are installed, is customary in the southern states; the attic temperature is often as- brined as the average between inside and -outside. : ' For a shorter, approximate method of calculating heat losses through 262 CHAPTER 12 1956 Guide attics, the combined ceiling and roof coefficient may be used, as described in Chapter >. - . TEMPERATURES IN UNHEATED SPACES The heat loss from heated rooms into unheated rooms or spaces must be based on the estimated or assumed temperature in such unheated spaces. This temperature will lie in the range between the inside and outside temperatures, depending on the relative areas of the surfaces ad jacent to the heated room and those exposed to the outside. If the re spective surface areas adjacent to the heated room and exposed to the outside are approximately the same, and if the coefficients of transmission are approximately equal, the temperature in the unheated space may be assumed to be the mean of the inside and outside design temperatures. If, however, the surface areas and coefficients are unequal, the tempera ture in the unheated space should be estimated by means of Equation 2. _ l(Ai(7i AjUt d~ AjUi 4- etc.) tg(AgU* -t- AbUb -4- AgUg -I etc.) , . A-iUi -f- A~tUt -f- etc. -f~ 4" At>Ub + A.cUe -l~ etc. where la = temperature in unhealed Bpace, Fahrenheit degrees. t = inside design temperature of heated room, Fahrenheit degrees, to = outside design temperature, Fahrenheit degrees. Ai, A,, At, etc. = areas of surface of unheated space adjacent to heated space, square feet. A., At,, Ac, etc. = areas of surface of unheated space exposed to outside, square feet. - Ui, Ut, Vu etc. = coefficients of transmission of surfaces of A,, At, At, etc. Ua, Ut,, Uc, etc. = coefficients of transmission of surfaces A, As, Ac, etc. Example B: Calculate the temperature in an unheated space adjacent to a heated room having surface areas (A,, A,, and A,) in contact therewith of 100, 120, and 140 sq ft and coefficients (Ui, Ut, and Ut) of 0.15,0.20, and 0.25, respectively. The surface areas of the unheated space exposed to the outside (A, and As) are respectively 100 and 140 sq ft, and.the corresponding coefficients are 0.10 and 0.30. The sixth surface is on the ground and is neglected in this example. Assume t = 70 and to = -- 10. Solution: Substituting in Equation 2: 701(100 X 0.15) -(- (120 X 0.20) -f (140 X 0.25)) 4- -101(100 X 0.10) + (140 X 0-30)1 " (100 X 0.15) + (120 X 0.20) 4- (140 X 0.25) + (100 X 0.10) + (140 X 0.30) ' 4660 U 126 37 F. The temperatures in unheated spaces having large glass areas and having two or more surfaces exposed to the outside (such as sleeping porches and sun parlors), generally are assumed to be the same as outside. v GROUND TEMPERATURES ; Ground temperatures to be assumed for estimating basement heat losses usually will differ in the case of basement walls and floors, the tern: peratures under the floors generally being higher than those adjacent' to walls. Factors affecting these temperatures will be discussed. '< Temperatures Under Basement Floors The temperature of the ground under basement floors9 is affected by : , heat sources within the basement and is not influenced by atmospheric Heating Load 263 conditions. In computing losses through basement floors, the ground tem peratures may be assumed to be the same as water temperatures at depths of 30 to 60 ft given in Fig. 3, Chapter 35. Test observations indicate that heat losses through basement floors frequently are over-estimated.10 Temperatures Adjacent to Basement Walls Ground temperatures near the surface and - under open spaces vary with the climate, the season of the year and the depth below the surface. The nearer the surface (during the cold weather) the lower will be the ground temperature. Frost will penetrate to a depth of over 4 ft in some localities if not protected by snow. A thick blanket of snow will result in a higher ground temperature near the surface. Therefore, in localities where the ground is covered with a heavy blanket of snow throughout the Table 4. Below Gbade Heat Losses fob Basement Walls and Floobs Ground Watbb Temperature* Basement Floor Loss'5 Btu/Sq Ft Below Grade Wall Loss'* Btu/Sq Ft 40 50 60 ` 3.0 2.0 1.0 . * See Fig. 3, Chapter 35. ' b Based on basement temperature of 70 F and U of 0.10. . 6.0 4.0 2.0 winter, the ground temperatures near the surface will be higher than when little or no snow is present. Complete data on ground temperatures adjacent to buildings are not available, but since the recommended transmission coefficient for base ment walls in contact with the soil is only 0.10, any reasonable, assumed ground temperature will not materially affect the calculated heat loss. BASEMENT TEMPERATURES AND HEAT LOSS The allowance to be made for basement heat loss depends on whether the basement is to be heated or not. If the basement is heated to a specified temperature, the heat loss should be calculated in the usual manner, based on tbe proper wall and floor co efficients (see Chapter 9) and the outside air and ground temperatures. Heat loss through windows and walls above grade should be based on out side temperatures and the proper air-to-air coefficients. Heat loss through basement walls below grade should be based on the floor and wall coeffi cients for surfaces in contact with the soil, and on the proper ground temperature. The heat loss values for below grade basement walls and floors given in Table 4 are sufficiently precise for general practice. If a basement is completely below grade and is not heated, the tem perature in the basement normally will range between that in the rooms ^bove and the ground temperature. Basement windows will, of course, jewer the basement temperature when it is cold outside, and heat given off cy the heating plant will increase the basement temperature. In any case, me exact basement temperature is indeterminate if the basement is not heated. In general, it is found that the transient heat from the heating Plant warms the air near the basement ceiling sufficiently to make it un- 264 CHAPTER 12 1956 Guide necessary to make an allowance for floor heat loss from rooms located over the basement. The temperature in crawl spaces below floors will vary widely depending on the number and size of wall vents, the amount of warm piping present and type of piping insulation. It is necessary, therefore, to evaluate the conditions and to select an appropriate temperature by judgment. HEAT LOSSES FROM FLOOR SLABS Two types of concrete floors used in basementless houses are (a) the unheated floor, relying for warmth on heat delivered above floor level by the heating system, and (b) the heated floor containing heated pipes or ducts that constitute a radiant slab or portion thereof for complete or partial heating of the house. For type (a) the floor heat loss, economically considered, is of minor importance since is comprises generally about 10 percent of the total heat loss of the house. From the comfort standpoint, however, it may be most important, since houses with cold floors are not successfully heated. In this connection, it should be remembered that a well insulated floor does not assure comfort if down-drafts from windows or exposed walls create pools of chilly air over considerable areas of the floor. For this reason a floor of type (a) should not be used in a severe climate.except'with a heat ing system that delivers enough heat near the floor to counteract the down drafts of the exterior walls and the heat transmission through the floor. The results of some experiments10'11 with type (a) unheated floor slabs indicate that the heat loss from a concrete slab floor on grade is more nearly proportional to the perimeter than to the area of the floor, and that the heat loss can be estimated by means of the equation: Hr = FP (( - f0) (3) where Hf = heat loss of the floor, Btu per hour. P = perimeter or exposed edge of the floor, linear feet. F = heat loss coefficient, Btu per (hour) (linear foot of exposed edge) (degree dif ference in temperature between the inside air and the outside air). (F ranges between 0.81 for a floor with no edge insulation to 0.55 for a floor with edge in sulation). t = inside air temperature, Fahrenheit. <0 = outside air temperature, Fahrenheit. . . In most instances the values given in Table 5 for edge loss are of sufficient precision for use.12 The insulation shown extending under the floor hori zontally for 2 ft can also be located along the foundation wall with equal effectiveness if the insulation extends 24 in. below the floor level. Example S: Calculate the heat loss from the floor of a 12 ft x 15 ft room with two exposures. The floor is an unheated concrete slab which is insulated at the edg. with 2 in. of insulation extending horizontally for a distance of 2 ft from the eug?>. and the house is located in an area with an outside design temperature of --151 Solution: From Table 5 the heat loss per foot of exposed edge is 45 Btu per op The length of exposed edge is 12 ft + 15 ft = 27 ft, and the total edge loss 27 x 45 r 1215 Btu per hr. . Floors of type (b) containing heating pipes or ducts, are now in comm011. Heating Load 265; use. The heat loss downward into the ground and outward through the edges of the floor slab is called the reverse loss. The results15 of an investigation in which a warm-air perimeter duct was embedded in four types of concrete floor slab and foundation constructions has verified the indication that Equation 3 can be used to calculate the reverse loss when warm-air perimeter heating ducts are used. To make the results of this application more usable, values corresponding to those shown in Table 5 for unheated floors are given in Table 6 for concrete floors with a warm-air perimeter duct. The desirability of edge insulation is apparent. One inch of waterresistant material is the minimum thickness of edge insulation that should be used, but a 2-in. thickness is recommended.12-14'16 The values of edge loss in Table 6 indicate that the reverse heat loss of heated slabs is likely to be about 20 percent of the total heat loss of many types of present day Table 5. Heat Loss of Concrete Floors at or Near Grade Level per Foot of Exposed Edge Heat Loss peb Foot or Exposed Edge, Btu/hb Ootdoob Design Temperature. F Recommended 2-in. Edge Insulation 1-in. Edge Insulation P 1-in. Edge Insulation . V 3*1. -20 to -30 50 55 60 -10 to -20 45 50 55 0 to -10 40 45 50 This construction not recommended; shownfor comparison only. No Edge Insulation* p 75 65 60 houses, and may exceed 20 per cent if only one inch of insulation is used at the edge of the floor. The concrete floor slab is usually placed on a gravel fill 4 in. thick or more, both to insulate the floor from the earth and to retard the rise of ffn wa^er by capillarity. A waterproof membrane should be in stalled over the gravel fill. Obviously, it is important that such floors be air several inches above grade, and that effective subsoil drainage be pro vided to avoid slabs soaked by rain or melting snow, and consequent excessive heat loss. TRANSMISSION HEAT LOSS The basic formula for the loss of heat by transmission through any sunace is given in Equation 4: where Ht = AU (l- tQ) (4) ^1 heat loss transmitted through the wall, roof, ceiling, floor, or glass, Btu per hour. . ^ -- area of wall, glass, roof, ceiling, floor, or other exposed surface, square feet. 266 CHAPTER 12 1956 Guide . V = coefficient of transmission, air to air, Btu per (hour) (square foot) (Fahr enheit degree temperature difference) (Chapter 9). j t = inside temperature near surface involved (this may not necessarily be the so-called breathing line temperature), Fahrenheit degrees. U = outBide temperature, or temperature of adjacent unheated space or of the ground, Fahrenheit degrees. ; Example 4: Calculate the:transmission loss through an 8 in. brick wall having an: area of 150 sq ft, if the inside temperature t is 70 F and the outside temperature 0 is - 10 F. ` Solution: The coefficient oi transmission (U) of a plain 8 in. brick wall is 0.50 (Chapter 9, Table 8). The area (-4) is 150 sq ft. Substituting in Equation 4: flt = 150 X 0.50 X [70 - (-10)1 = 6000 Btu per hour. , Tabus 6 ' Floor Heat Loss to be Used When Wabm-Air Perimeter Heating Ducts Are Embedded in Slab* Btu per (hour) (linear foot of heated edge) Edge Insulation Outdoor Design Temperature, F 1-in. Vertical Extend ing Down 18 in. Below Floor Surface 1-in. L-Ttpe Extend 2-in. L-Tyfb Extend ing at Least 12 in. ing at Least 12 in. Deep and 12 in. Under Down and 12 in. Under -20 -10 0 10 20 . 105 95 . 85 75 62 100 90 80 70 57 85 75 65 55 45 * Factors include loss downward through inner area of slab- Transmission Loss Through. Ceilings and Roofs The transmission heat loss through top floor ceilings, attics, and roofs may be estimated by either of two methods: 1. By substituting in Equation 4 the ceiling area A, the inside-outside tempera ture difference (t -- 1,,) and the proper value of U: a. Flat roofs. Select the coefficient of transmission of the ceiling and roof from Tables 15 or 16, Chapter 9, or use appropriate coefficients in Equation 1 if side walls extend appreciably above the ceiling of the floor below. b. Pitched roofs. Select the combined roof and ceiling coefficient from Table 18, Chapter 9 or calculate the combined roof and ceiling coefficient by means of Equations 4 and 5, Chapter 9, where these formulas are applicable as explained in Chapter 9. 2. By estimating the attic temperature (based on the inside and outside design temperatures) by means of Equation 1, and substituting for to in Equation 4, the value of f. thus obtained, together with the ceiling area A and the ceiling coefficient U. This applies to pitched roofs. In the case of flat roofs it is not necessary to calculate the attic temperatures, as the ceiling-roof heat loss can be determined as suggested in paragraph la. INFILTRATION HEAT LOSS The infiltration heat loss includes (1) the sensible heat loss or the heat required to warm the outside air entering by infiltration, and (2) the latent heat loss or the heat equivalent of any moisture' which must be added. Heating Load 267 Sensible Heat Loss The formula for the heat required to warm the outside air which enters a room by infiltration to the temperature of the room, is given in Equation 5: where H, = 0.240 Qd (t - t,,) (5) H, = heat required to raise temperature of air leaking into building from t0 to t, Btu per hour. 0.240 = specific heat of air. Q = volume of outside air entering building, cubic feet per hour (see Chapter 11). d = density of air at temperature to, pounds per cubic foot. It is sufficiently accurate to use d = 0.075 in which case Equation 5 reduces to H, = 0.018 Q (t - to) (5a) The volume ~Q of outside air entering per hour depends on the wind velocity and direction, the width of crack or size of openings, the type of openings and other factors, as explained in Chapter 11. Where the crack method is used for estimating leakage, it is more convenient to express the air leakage heat loss in terms of the crack length: where a. = B t (t - Q (5b) B = air leakage per (hour) (foot of crack) (Chapter 11) for the wind velocity and type of windows or door crack involved, multiplied by 0.018. L = length of window or door crack to be taken into consideration, feet. Example 5: What is the infiltration heat loss per hour through the crack of a 3 x 5 ft average, double-hung, non-weatherstripped, wood window, based on a wind velocity of 15 mph? Assume inside and outside temperatures to be 70 F and zero, respectively. . Solution: According to Table 2, Chapter 11, the air leakage through a window of this type (based on A in. crack and 5\ in. clearance) is 39 cu ft per (ft of crack) (hour). Therefore, B = 39 X 0.018 = 0.70. The length of crack L is (2 X 5) + (3 X 3) , or 19 ft; t -- 70 and t0 = 0. Substituting in Equation 5b, Hb = 0.70 X 19 X (70 - 0) = 931 Btu per hour. Crack Length to be Used for Computations , For designers who prefer to use the crack method, the basis of calculation ts as follows: The amount of crack used for computing the infiltration heat loss should be not less than half of the total length of crack in the outside walls of the room. For a building having no partitions, air entermg through the cracks on the windward side must leave through the cracks on the leeward side. Therefore, take one-half the total crack for computing each side and end of the building. In a room with one exposed wall, take all the crack; with two exposed walls, take the wall having the 268 CHAPTER 12 1956. Guide 7 most crack; and with three or four exposed walls, take the wall haying the most crack; but in no case take less than half the total crack. In small residences the total infiltration loss of the house is generally considered to be equal to the sum of the infiltration losses of the various rooms. However, this is not necessarily accurate as at any given time infiltration will take place only on the .windward side or sides and not on the leeward side. Therefore, for determining the total heat requirements of larger buildings it is more accurate to base the total infiltration loss on the wall having the most total crack, but in no case on less than half of the ' total crack in the building. Number of Air Changes to be Used for Computations . Since a certain amount of judgment is required regarding quality of construction, weather conditions, use of room and other factors in esti mating infiltration by . any method, some designers base infiltration upon an estimated number of air changes rather than upon the length of window cracks. Table 4 of Chapter 11 indicates air changes commonly used, but should he taken only as a guide. When calculating infiltration losses by the air change method, Equation 5a may be used by substituting for Q the volume of the room multiplied by the number of air changes obtained from Table 4, Chapter 11. For further discussion of the method see section on Air Change Method in Chapter 11. Latent Heat Loss When it is intended to add moisture to air leaking into a room in order to maintain proper winter comfort conditions, it is necessary to determine the heat required to evaporate the water vapor added. This heat may be calculated by the equation : . H, = Qd (W, - W0) hu (6) where H, = heat required to increase moisture content of air leaking into building from m,, to mi, Btu per hour.. Q = volume of outside air entering building, cubic feet per hour. d = density of air at temperature ti, pounds per cubic foot. Wi = vapor density of inside air, pounds per pound of dry air. . Wo = vapor density of outside air, pounds per pound of dry air. hit = latent heat of vapor, at m\, Btu per pound. ' If the latent heat of vapor h/0 is assumed to be 1060 Btu per lb, Equa tion 6 reduces to: . Hi = 79.5 Q (W, - Wo) (6a) Equations 5a, 5b and 6a may also be used for. determining the sensible and latent heat gains due to infiltration in cooling load computations. SELECTION OF WIND VELOCITIES The effect of wind on the heating requirements of any building should be given consideration for two reasons: , 1. Wind movement increases the heat transmission of walls, glass, and roofi affecting poor walls to a much greater extent than good walls. Heating Load 269 2. Wind increases materially the infiltration of cold air through the cracks around doors pnd windows, and even through the building materials themselves (see Tables .rand'2, Chapter'll)..'... . . .'' ' . ' .. ' Theoretically, as a basis for design, the most unfavorable combination of temperature and wind velocity should be chosen. It is entirely possible that a building might require more heat on.a windy day with a moderately low outside temperature, than on a quiet day with a much lower outside temperature. However, the combination of wind and temperature, which is the worst, would differ with different buildings, because wind velocity has a greater effect on buildings which have relatively high infiltration losses. It would be possible to compute the heating load for a building for several different combinations of temperature and wind velocity which records show to have occurred, and to select the worst combination, but designers generally do not feel that such a degree of refinement is justified. Therefore, where Table 1 lists the maximum wind velocity occurring during the coldest 2\ % of the winter hours for each locality, this value should be the. basis' for estimating infiltration losses. When using the air change method it will not be necessary to consider the wind velocities. Designers employing the crack method generally use values corresponding to a 15-mile wind'. The effect, of the wind velocity on the transmission coefficient cah'beevaluated from Table 21 of Chapter 9. Exposure Factors Many designers use empirical exposure factors to increase the calculated heat loss of rooms or spaces on the side or sides of the building exposed to the prevailing winds) However, the use of exposure factors is unneces sary when the Guide method of calculating heat losses is used. Therefore, exposure factors may be regarded as/actors of safety for the rooms or spaces exposed to the prevailing winds, to allow for additional capacity for these rooms or spaces, or to balance the radiation, particularly in the case of multi-story buildings. Tall buildings may have severe infiltration heat losses, induced by their stack effect (see Chapter 11), which will require special consideration. Although the exposure allowance frequently is as sumed to be 15 percent, the actual allowance to be made, if any, must to a large extent be a matter of experience and judgment of the designer, since there are at present no authentic test data available from which rules could be developed for the many conditions encountered in practice. AUXILIARY HEAT SOURCES The heat supplied by persons, lights, motors and machinery always should be ascertained in the case of theaters, assembly halls, and industrial plants, but allowances for such heat sources must be made only after careful consideration of all local conditions. In many cases, these heat sources should not affect the size of the heating plant at all, although they may have a marked effect on the operation and control of the system. In general, where audiences are present, the heating system must have sufficient capacity to bring the building to the stipulated inside temperature before the audience arrives. In industrial plants, quite a different condition exists, and heat sources, if always available during occupancy, may be substituted for a portion of the heating installation. In no case should the actual heating installation (exclusive of heat sources) be reduced below that required to maintain at least 40 F in the building. 270 CHAPTER 12 1956 Guide Electric Motors and Machinery Motors and the machinery which they drive, if both are located in the room, convert all of the electrical energy supplied into heat. This heat is retained in the room if the product manufactured is not removed until its temperature is the same as the room temperature. . If power is transmitted to the machinery from the outside, then only the heat equivalent of the brake horsepower supplied is used. In some mills this is the chief source of heating, and it is frequently sufficient to overheat the building even in zero weather, thus requiring cooling by ventilation the year round. Table 7 shows the heat output equivalent Table 7. Heat Equivalents of Various Sources* Machinery (Motor in room) = Motor Hp/efficiency x 2544 ' Btu/hr. Machinery (Motor outside room) = Motor Hp x 2544 Btu/hr. Electric Lights = Kilowatts x 3413 Btu/hr. Gas (Producer 150) (Manufactured = 535) (Natural 1000) Btu/cu ft. * Additional values are given in Chapter 13, Table 26. . of various sources of heat in a factory. For information concerning the heat supplied by persons, refer to data given in Chapter 6, and also Table 25, Chapter 13. For appliances see Table 26, Chapter 13. INTERMITTENTLY HEATED BUILDINGS In the case of intermittently heated buildings additional heat is required for raising the temperature of the air, the building materials and the ma terial contents of the building to the specified inside temperatime. The rate at which this additional heat must be supplied depends upon the heat capacity of the structure and its material contents, and upon the time in which these are to be heated.15 This additional heat may be computed and allowed for as conditions re quire, but inasmuch as the heating system proportioned for taking care of the heat losses will usually have a capacity about 100 percent greater than that required for average winter weather, and inasmuch as most buildings may either be continuously heated or have more time allowed for heating up during the few minimum temperature days, no allowance usually is made, except in the size of boilers or furnaces. For churches, auditoriums and other intermittently heated buildings, additional capacity should be provided. RESIDENCE HEAT LOSS PROBLEMS The following Examples 6 and 7 will illustrate the procedure for calcu lating the heat loss of a residence, uninsulated and insulated, in accordance with the recommendations given in this chapter. Example 6: Calculate the heat loss of the residence shown in Fig. 2 located in the vicinity of Chicago. From Table 1, design outdoor conditions are --10 F and 12 mpy wind velocity. Inside temperature from Table 2 is assumed to be 70 F.' The attic is unheated. Assume ground temperature to be 50 F (see Fig. 3, Chapter 35) under basement and garage floors and 32 F adjoining basement walls. Estimate infiltration losses by the air change method. No wall, ceiling or roof insulation is to be con sidered in this problem, but all first and second floor windows, except in the garage, Heating Load 271 Room or Space Bedroom A and Closet Bedroom B and Closet r,,^m or Sthuctube oa Inpiltbatiom Ajb Changes Avails Glass Ceiling ` *: Infiltration (X)* Walls Glass Ceiling Infiltration (54)* Net Abba ob Ajb Volume 238 sq ft 40 sq ft - 252 sq ft 1510 cfhb . 156 sq ft 40 sq ft 170 sq.ft 1020cfhb 39.8* Bedroom C and Closet Bedroom D and Closet Walls Glass Ceiling . Infiltration (54)* Walls Glass Ceiling Floor over garage Infiltration (54)* Walls Glass ^Ceiling Infiltration.(1)* Walls Glass Ceiling Floor over garage Infiltration (1)* 114 sq ft 27 sq ft 129 sq.ft 874cfbb 39.8* 118 sq ft 20 sq ft HO sq ft 110 sq ft 660cfhb 30 sq ft 14 sq ft 55 sq ft 440cfhb 79 sq ft 9 sq ft 35 sq ft 35 sq.ft 280cfhb 0.28 0.45 0.69 j0.25 , 1 0.018 |~0.28 0.45 0.69 , 0.018 39.8* 35 Dining Room Kitchen and Entrance to Garage Yvette and Vestibule Entrance Hall Walls ,, Walls (adjoining gffcnge) Glass Floor '. Infiltration (1Hr Walls Glass (doore) Glass (windows) Floor . Infiltration (1*4)* Walls Adjoining garage) Door Floor Infiltration 054)' Walls . . Walls (adjoining garage) Glass Door Floor . Infiltration (IV4)* Walls Door Ceiling' Infiltration^)1 267 sq ft 94 sq ft 50 aq ft 294 sq.ft 3745cfbb 0.018 166 sq ft 35 aq ft 20 sq ft j 0.28 0.85 I 0.45 2140 I 0.018* 80 35 80 80 80 80 80 80 96 sq ft 51 sq ft 18 sq ft 17 sq ft 80 35 80 35 0.018 80 0.018 Heat Loss (Btu per hour) Totals (Btu per hour) 3490 1440 4660 1470 2560 970 3540 1260 2650 720 3020 960p 950 670 500 1510 630 1640 310? 400 5980 1280* 1800 5400 3720 2380 720 3080 2150 700* 650 300 2300 15,860 11,060 8,300 3.310 3,630 14.460 9,900 -- 6.100 4.650 ^creation Room* Walls Glass Doors Infiltration 054) Floor Gain adjoining rooms Walls Glass Floor Infiltration (1)* 220 sq ft ' 8 sq ft 287 sq ft 2010 cfbb 5.500 5,020 TOTAL 100,600 272 CHAPTER 12 1956 Guide Notes for Table 8. * The inside-outside temperature diBerence is 70-- (--10) or 80 F eacept where otherwise noted, _ h*b TVVnooelluuimmnseeiQooeff*uiinnutffeiillwttrr<aawttiio--onn--,,,cc.fthh = = (no. (no. air air changes) % changes) x (floor or ceiling area) s (floor or cemuS - (ceiling height). _______ d The ceiling heat lasses are calculated by estimating the attic temperature and then calculating the loss thro6uFgrhomtheEqcueailitniognu6sain. g the proper temperature difference. This unhealed attic is not ventilated during winter months. The attic temperature is estimated from Equation l to be 30.2 F when the outside tem perature is --10 F and room temperature is 70 F. The temperature difference is then 70--30.2 or 39.8 deg. For the insulated residence, attic temperature become 4.6 F and temperature difference 70--4.6 9 65.4 deg. *1 TCeomefpfiecireantut froerinwagallraadgejoainsisnugmgeadratgoebcea3lc6uFla,,ted on basis ot metal lath and plaster on both aides of studs (U 8*O0n.3e9h).alf of value from Table 4, Chapter 11, for storm windows or weatherstripping. ' * Exposed on two sides, we&thentripped windows offset by fire-place. Use 1>$. * Window on one side weatherstripped but double-doors are hard to close tightly. Hence, conservative valu1eAossfu1mHi-ng k' i'tch* en--v--en*t, door*taovveessttibibuuleleuussuuaallylyooppeenn,,aallolowwffuulllttaabblelevvaalulueeooff11HH- * One-half value in Table 4, Chapter 11, increased to 1H 'by near*by outside door ?int\ vestibule. 1 Full value in Table 4, Chapter U, to allow for frequent opening of outside door. m Two tides exposed, large doors but large volume. Use value 1H as given in Table 4, Chapter 11. a Two small unweatherstripped windows in pro tected location, but fireplace, indicate 1 change. p Heat losses from these rooms into garage are heat gainqsNfoerggleacrtagbee.at loss to basement, as losses from boiler, piping, etc., will probably keep basement near, if n*oUt apbsotaveir,s70hFal.l ceiling figures with downstairs. Heat should be provided downsiairs for both. " Linear feet of exposed edge. basement plan Fio. 2. Floor Plans of Residence Heating Load 273 Table 9. Summary of Heat Losses of Uninsulated Residence (Btu Per Hour) Room ok Space Walls Ceiling and Root Floor Glass and Door Infil tration Totals Bedroom A Bedroom B Bedroom C Bedroom D Bathroom I Bathroom 2 Living Room Dining Room Kitchen Lavette Entrance Hall Garage Recreation Design Totals Operating Totals6 Percentages4* 5330 3490 2560 2650 670 1640 7260 3720 2850 3000 870 -- 1030* 840 33.850 33,850 38.4 6910 4660 3540 3020 1510 960 2390. -I27(r 21.720 21,720 24.6 960 310 1060 570 2,900 2.900 3.3 1440 1440 970 720 500 320 1800 3100 950 1100 640 3710 720 17,410 17,410 19.7- 2180 1470 1260 950 630 400 MOO 3080 2300 550 1600 1910 2890 24,620 12,310 14.0 15,860 11,060 8,330 8.300. 3,310 3.630 14,460 9.900 6.100 4,660 5.500 4,380 5,020 100,500 88,190 100.0 B Wall heat loss of 2110 Btuh minus wall heat gains of 1280, 700 and 1160 Btuh. Heat gains of 96Q andb 0 Btuh. c Based on H computed infiltration. d Based on operating totals. are to have storm sash. The building is constructed as follows (heat transmission coefficients U are parentheses): Walls: Brick veneer, building paper, wood sheathing, studding, metal lath and Elaster (0.28). Walls of dormer over garage, same except wood siding in place of rick veneer (0.26). - Attic Walls: Brick veneer, building paper, wood sheathing on studding (0.42). Basement Wa!is: 10 in. concrete (0.10). . Roof: Asphalt shingles on wood sheathing on rafters (0.53). Ceiling (Second floor): Metal lath and plaster (0.69). Windows: Double-hung wood windows averaging 70 percent glass (0.45; from Chapter 9, Table 20, Section D, the U value for wood windows with storm sash is 0.53 X application factor; by interpolation this factor is 0.85). Steel casement sash in garage and basement (1.13;from Chapter 9, Table 20, U is 1.13 for all glass and the application factor is 1.00). French doors in dining room 50 percent glass, no storm doors (0.85; from Chapter 9, Table 20, U is 1.13 for all glass; by interpolation the application factor is 0.75). Floor (Bedroom D): Maple finish flooring on yellow pine sub-flooring; metal lath and plaster ceiling below (0.25). Floor (Basement and Garage)-. 4 in. stone concrete on 3 in. cinder concrete (0.10). Solution: The calculations for this problem are given in Table 8, and a summary Table 10. Summary of Heat Losses of Insulated Residence (Btu Per Hour) Room or Space Walls Ceiling and Roof Floor Glass and Door Infil tration Totals Bedroom A Bedroom B Bedroom C Bedroom D Bathroom 1 Bathroom 2 living Room fating Room Kitchen Lavette Entrance Hall Recreation Resign Totals ' Operating Totals6 Percentages41 2480 1620 1190 1230 310 760 3370 1730 1320 1390 410 --470* 840 16,180 16,180 29.1 2460 1660 1260 1080 540 250 850. -aiob 7.190 7,190 12.9 690 220 1060 570 2,540 2,540 4.6 1440 1440 970 720 500 320 1800 3100 950 1100 640 3710 720 17,410 17,410 31.3 2180 1470 1260 950 630 400 5400 3080 2300 550 1600 1910 2890 24,620 12,310 22.1 8,560 6,190 4,680 4,670 1,980 1,950 10,570 7,910 4,570 3.040 3,500 5.300 5,020 67,940 55,630 100.0 I., keat loss of 980 Btuh minus wall heat gains of 590, 320 and 540 Btuh. b Heat gains 690 and 220 . nh. Based on >4 computed infiltration. d Based on operating totals. 274 CHAPTER 12 1956 Guide of the results in Table 9. The values in column F of Table 8 were obtained by multi plying together the figures in columns C, D, and E. The heat losses are calculated to the nearest lOBtu. See reference notes for Table 7 for further explanation of data. Attention is called to the summary of heat losses (Table 9) for the uninsulated resi dence. As storm windows are used in this instance the glass and door transmission heat losses of 19.8 percent are relatively small. The infiltration losses of H.O per cent are also comparatively small because the storm windows are equivalent to weatherstripping. In this problem, the wall, ceiling and floor transmission losses comprise 66.2 percent of the total. Example 7: Calculate the heat loss of residence shown in Fig. 2 based on the same conditions as in Example 6 but having construction improved or insulated to obtain coeWffiaciielsn,ts0.1a3s ;foWllaolwlsso: f Dormer over Garage, 0.12; Aide Walls, 0.28; Walls Adjoining Garage, 0.18; BasementWalls (Recreation Room), 0.10. Roof, 0.53. Ceiling (Second Floor), 0.15. Windows (Same as in Example 6). FSloolourtio(Bne: dTrohoempDro)c, e0d.1u8re. for calculating the heat losses is similar , to that for Example 6. A summary of the results is given in Table 10. REFERENCES 1 ART Application Engineering Standards for Air Conditioning for Comfort, 1947 {Air-Condiliomng and*RAenfriAgenraalytisoins JonfsWltluinlgte).r Temperatures for One Hundred and Twenty Cities, by Clark M. Humphreys {Ca*rnIengvieesItnigsatittiuotne ooffOTeilc-FhniroelodgFy oBrcuelldetAinir1F93u9rn).ace Systems in the Research Residence, by A. P. Kratz and S. Konzo (University of Illinois Engineering Experiment Station Bulletin No. 318). 4 Performance of a Hot-Water Heating System in the I=B=R Research Home at the University of Illi nois, by A. P. Kratz, W. S. Harris, M. K. Fahnestock, and R..' J. Martin (University of ftlvnoiz Engineering Exp*eArimSetundt ySotaftRioandBiaunllteBtainseNboo.a3rd49H).eating in t-h e I=B=R Research Home, by A. P. Kratz and W. S. Harris (University of Illinois Engineering Experiment Station Bulletin No. 358). * Performance of a One-Pipe Steam System in the I--B*=R Research Home, by W. S. Harris (University of J7UAtn.Sot.sHE.Vng.Ein.eRereinsgeEarxcpheriRmeepnotrSttaNtioon. 1B0t1t1U--erTinesNteo.o3f 8T3h).ree Heating Systems in an Industrial Type of Building, by G. L. Larson, D. W. Nelson, and John James (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 135). Methods of Moisture Control and Their Application to Building Construction, by F. B. Rowley, A. 8. Algren and C. E. Lund (University of Minnesota, Engineering Experiment Station Bulletin No. 17). . A.S.H.V.E. Research Report No. 1213--Heat Loss Through Basement Walls and Floors, by F- C. Houghten, S. I. Taimuty, Carl Gutberlet and C. J. Brown (A.S.H.V.E. Transactions, Vol. 48, 1942, p. 369)1.0 Measurements of Heat Losses from Slab Floor, by Rr S. Dill, W. C. Robinson and H. E. Robinson (U. S. Department of Commerce, National Bureau of Standards, Building Materials and Structures Report BM11ST1e03m).perature and Heat Loss Characteristics of Concrete Floors Laid on the Grounrd, by H. D. Bareither, A- N. Flemming and B. E. Alberty (University ofIllinois, Small Homes Council Technical Report). 11 Concrete Floors for Basementless Houses (University of Illinois, Small Homes Council Circular No. F 4.w3)W. arm-Air Perimeter Heating, Part III--Heat Losses from Floor Slab, by J. R. Jamieson, R. W. Roose and14SW. Kaormnz-oA.ir P(AerSimHeVteEr THeraatninsga--ctMioannsu,aVl 4o,l.N5a8,tio19n5a2l, Wp.a2rm17)A. ir Healing and Air Conditioning Association. Heat Requirement Tables for Intermittently Heated Buildings (Engineering Experiment Station Bulletin No. 60, A. and M. College of Texas, College Station, Texas) contains a set of tables applicable to either intermittent heating or cooling. Further information may be found in a paper, A Method of Compiling Tables for Intermittent Heating, by Elmer G. Smith (A.S.H.V.E. Journal. Section, Heating, Piping and Air16CSolnadbi-toionn-Gingro,uJnudneCo19n4s2t,rupc.ti3o8n6)f.or Residences, (Publication No. 385, ' Building Research Advisory Board, National Research Council). ' CHAPTER 13 COOLING LOAD (Tooling Load Calculations; Design Conditions; Instantaneous Heat Load; Solar Ra diation; Periodic Heat Flow; Tables for Calculating Solar Heat Gain Through Walls, Roofs and Glass; Instantaneous Heat Gain vs. Cooling Loads; Load from Interior Partitions, Ceiling and Floors; Load from Outside Air, Ventilation and Infiltration; Effect of Outside Air on Load; Heat Sources Within Conditioned Space; Moisture Transfer Heat Load; Miscellaneous Heat Loads; Apparatus Dew Point and Required Air Quantity Through Conditioning Equip ment; Minimum Entering Air Temperature; Ex ample Cooling Load Calculation THE variables affecting cooling-load calculations are numerous, often difficult to define precisely, and always intricately inter-related. Most of the components of the cooling load vary in magnitude over a wide range during a 24-Hour period, and as the cyclic changes in load com ponents are not usually in phase with each other, careful analysis is re quired to establish the resultant maximum cooling load for a building or zone. A zoned system must often handle peak loads in different zones at different hours. . Economic considerations must be of particular influence in the selection of equipment for cooling season operation in comfort air conditioning, and this fact, coupled with present inadequacies in available data and knowl edge of the air-conditioning art, places a premium on the experienced judg ment essential to successful design or practice. Variations in the weather, building occupancy, and other factors affecting load, necessitate carefully coordinated controls to regulate simultaneously the components and the equipment in order to maintain the desired room conditions. The calculation procedures presented in this chapter deal with the vari ous instantaneous rates of heat gain, both sensible and latent, in a condi tioned space. There may be an appreciable difference between the net instantaneous rale of heat gain and the total cooling load at any instant. This difference is caused by the storage and subsequent release of heat by the structure and its contents. This thermal-storage effect may be quite im portant in determining an economical cooling equipment capacity. The lack of any adequate means of treating this storage quantitatively in its entirety for a complete structure, must be recognized in judging the pro-, cedures and data presented for calculating individual components of the net rate of instantaneous heat gain. Solar healing calculations involve the same principles as cooling load calculations. Many of the data on solar radiation given in this chapter can be used in calculations for solar heating. , COOLING LOAD CALCULATIONS Summer cooling load calculations, whether for industrial or comfort applications, require consideration of the following factors: A. Design Conditions: (1) indoor conditions; (2) outdoor conditions;. (3) venti lation rate. ' B. Instantaneous Heat Load, Sensible and Latent: (1) load from solar radiation, 275 "A 276 CHAPTER 13 1956 Guide sky radiation and from outdoor-indoor temperature differential for glass areas and exterior, walls and roofs, modified by periodic heat flow or lag factors depending on the type of structure; (2) load due to heat gain through interior partitions, ceilings and floors; (3) load due to ventilation, either natural or mechanical; (4) load due to heat sources within the conditioned space such as people, lights, power equipment, and appliances; (5) load due to moisture transfer through permeable building materials; (6) miscellaneous heat sources. , - . :-- C- Determination of Air Quantity and Apparatus Dew Point. . These factors will be discussed in turn. The material presented leads to an illustrative .procedure for a coding-load calculation, and a numerical example is given to demonstrate the calculations involved. DESIGN CONDITIONS Indoor Conditions Indoor air conditions for human health and comfort have heen and con tinue to be the subject of much discussion and research. The effective temperature index, explained in Chapter 6 is probably the best available source of design criteria for comfort air .conditioning systems for buildings or enclosures in which the air and inside surface Design Room Conditions Usually Specified fob Summer Average Table 1. Type op Installation Relative Dby-Bulb Temp Wet-Bulb TEMPb Humidity Per Cent Grains Per LBb 1. Ample Capacity............... 2. Practical Application----3. Occupancy--15 to'40 min. 78 - 65 80 67 .82 68 50. 51 49 a Values in Table 1 are for peak toaa conditions, ac a *..i0vv~ w mately 76 F and 50 percent relative humidity at other than peak load. b Psychrometric data for standard barometric pressure. c Fig. 10, Chapter 6, air movement 15 to 25 fpm. " 72.7 78.5 80.0 72.2 74.0 75.3 _ _____ _ . _ _ ' temperatures remain substantially equal; a condition that can safely be assumed for most ordinary comfort air conditioning installations. Other sources of design specifications are to be found in the requirements of codes and ordinances, and in the varied long-term experiences of manufacturers, contractors, and engineering specialists. Past experience, cumulative over many years, indicates that indoor de sign conditions for which summer air-conditioning equipment is selected, should not exceed a temperature of 80 F or a relative humidity of 50 per cent for the average job in the United States. If these conditions are exceeded, complaints of discomfort may be expected, especially with con tinuous occupancy. For very brief occupancy only, a slightly higher peak load design temperature may be employed. In regard to the lower limit of humidity, complaints are not encountered for store installations oper ated down to 35 percent relative humidity or, for office jobs, somewhat lower. These observations apply to normal commercial practice in this, country only; for extremes, such-as tropical or very hot regions, it is re garded as more practicable to design for a peak-load outdoor-indoor tem perature difference of about 15 to 20 F/ Table 1 offers typical design conditions for average requirements en countered. The values in line 1 would also apply in general for localities having a summer outdoor design temperature of 90 F or less; and the 15 to 40 min occupancy values, or even somewhat higher dry-bulb tern- Cooling Load 277 peratures, would indicate acceptable conditions for very hot localities. Tablfe 1 is lo be used with good judgment, for there is no universal rule which may be applied to indoor design conditions. Guarantees of conditions to be maintained for summer operation are based upon a definite set of load conditions. At other than the guarantee load, the conditions produced by a system are determined by the balance of imposed load and equipment capacity, and by the method adopted for regulating the system operation. Complete specifications of indoor design conditions would include part-load and overload operation, particularly from the viewpoint of economy. In the field of industrial air conditioning, indoor design conditions are established by the requirements of goods and processes, ih addition to the comfort and efficiency of the workers. Many typical indoor design condi tions for products in industrial air conditioning are given in Chapter 45. The load calculations for either comfort or industrial air conditioning are usually made in accordance- with a guarantee. In comfort applica tions, for example, this is frequently 80 F and 51 percent relative humidity or 78 F and 50 percent relative humidity. The system is normally operated at 75 or 76 F and approximately 50 percent relative humidity at all times as long as the equipment has capacity to maintain these conditions. Dur ing very hot weather, the room temperature will rise above the control point and the equipment will operate continuously. Normally, industrial jobs are operated at design conditions at all times if the optimum condi tions are selected for the benefit of the product. -- The indoor design conditions suggested have had reference to conditions to be maintained at the level of occupancy. For extremely high ceilings in public or industrial buildings, only the zone from 10 to 15 ft above the floor may be cooled to the full extent. The air temperature at the ceiling would be much higher, and this should be kept in mind when calculating the convective portion of the roof heat gain. A reduction of outdoor-toindoor air temperature differential may be assumed in such instances; radiation from the inner roof surface is not diminished. Outdoor Conditions Summer climatic conditions and suggested design wet-bulb and drybulb temperatures are given in Table 2 for various locations ih the United States. The highest temperature ever recorded is for the period of record shown. In some cases it should be noted that this period of record is com paratively short, and higher temperatures may be expected. In making comparisons for other localities than those shown in Table 2, due considera tion must be given to elevation. Column 6 of Table 2 indicates the design dry-bulb temperature suggested by the A.S.H.A.E. Technical Advisory Committee - on Weather Design Conditions. This temperature is the maximum hourly outdoor tempera ture which has been equalled or exceeded 2J percent of the total hours of June,- July, August and September for the period of record, in this case the 5-year period 1935-1939, and should not be confused with the period of record given in Column 4 which applies only to highest temperature ever recorded. Since all of these data (Column 4) are based on airport records, they are not necessarily applicable to cities. The data given in Columns 7 and 8 were obtained from local A.S.H.A.E. Chapter Secretaries, and represent the design temperatures in local use. Where such information was not available, it was taken from a publication of the A.R.I.1 and from various other sources. 278 CHAPTER 13 1956 Guide The Technical Advisory Committee on Weather Design Conditions has suggested that wet-bulb design temperature be taken a's that wet-bulb temperature which has been equalled or exceeded in 5 percent of the hours during months of the period of record. While not available for the 1956 edition of The Guide, due to the tremendous task of compiling these data/ it is hoped that they will be available for some stations for future editions. The wind velocity to be used in design should be that wind velocity which accompanies the design temperatures in each instance, but since these data are not available, the average summer wind velocities for the period of record were taken from U. S. Weather Bureau records revised to 1948. It is pointed out that this is not necessarily the velocity which coincides with the design temperatures, but it may serve as a guide to the designer. Other weather data, such as daily range of temperature, are useful particu larly when making cooling load calculations for an early morning peak on an east exposure. Daily range of temperature is the difference between the average of the daily maximum dry-bulb temperatures and the average of the daily minimum temperatures. This range is highest in semi-arid or desert regions and at high elevations, and lowest near the oceans or very large lakes. The daily range of temperature (Fahrenheit degrees) in July for the principal areas of the United States can be approximated from the following tabulation: East Sea Shore................ 12 to 18 East of Mississippi River................................ 19 to 24 Gulf Sea Shore.................12 to 18 Mississippi River to Rocky Mountains___ 24 to 33 Great Lakes Shore_____ 18 to 21 Rocky Mountain Area.............................................33 to42 West Sea Shore........... .. 15 to 20 West Coastal States.......................................... .20 to 36 Ventilation Rate The introduction of outside air is necessary for the ventilation of condi tioned spaces. Chapter 6 suggests minimum outdoor-air requirements for representative applications; but it is to be emphasized that minimum re quirements are not necessarily adequate requirements for all psychological attitudes and physiological responses. Where maximum economy in space and load are essential, as in submarines or other restricted spaces, as little as 1 cfm of outside air per person has been found to be sufficient provided that satisfactory ventilation is simultaneously obtained by an adequate decontamination of recirculated air.{ Local codes and ordinances frequently specify ventilation requirements for public places and for industrial installations.. For operating rooms, minimum requirements for safe practice are given in a National Board of Fire Underwriters' pamphlet.* This pamphlet does not require 100 percent outside air in operating rooms, although 100 percent outside air is normally : used and recommended. Recommended and minimum ventilation .rates for the most common applications are summarized in Table 3. For further general applications, a basis of estimating the cfm per person may be taken as: . 1. People not smoking........................................... 71 Recommended . 2. People smoking....................................................40 Recommended S Minimum '. SB Minimum , The cooling load due to the introduction of outside air for ventilation w determined once the indoor and outdoor design conditions are fixed. CaK culations will be discussed subsequently. *- v. Cooling Load 279 Col. 1 State Col. 2 Station1* I Cox.. 3 | Cox,. < {Eleva Period Col. 5 H&ighTest ,1 fDeesBigrn J DDCeeobslri.gow7n I IwiS?0s1*'s, | IavC^ol.o9 tion0 Record*1 itECORDEDd|T-A.C. 2j% Temp, in i Temp, in Basis'* { Common Use1 VKhSv. to.1(GUHaDCh.Ca(.ooCCAnloA.nar..k.rMlv..PiPiLI..BfS.^SlSJMd.A..A'JA,ooneo.PtJPl.uafaaH.JJJSaiaclAuuawScateWWiNeNHevrfHhvaaBlntaUaccmDg?mia$W~palug*SniSaanJaScoreoecReosteRoaR:utaaggauyfyaarIaasenuEksneaaenDek"warBwt.yapLeapA.nsPJosioesePsrenarvolYPBonsm.alnlernlntsJvnannclBuSW.c.htElhlnhtM..-tM-.saabiastaioMddcoMd..iojeocABn..f,.oofadHuatuaara.arc.HaBvH..rivJ,.i?do.Fook.glnD.n.8..tdkinoD.ana......tr;ee'n..o.ro.hor..h.nin.hm...ole.:neo.mt..lo0BeB*..l.eni...tra.r.rr;aggle.g.tbi.ve.migl..m.as...r..v.ik:i6.ae._.i.n.n.J.ns....damnbs.rdg.;..o..e.*be.r.c.rm....vS..t..ovtfae1til...s.:la.Ss._.i...a......u;..g.st.oeee.lo.u....tn.lu...i.i....o...1....gg.n.i...Re:R....elgl.....l..nt.;.ntg.....i.......!.l..mcf..ne.!.j..en...nenm..n.....n..c....a.t....e:f.l.W.fo;oi...n.......nu.o.,.n.......k..*a.....go.oeAf..o....f..c..t...;.....t..;.i......._Wg..fC................_.g.s..o....o-.Wi..m....A..n_.i....;f...:l.Ctmc...t...c.......A....._t....c.Pt..--;d...C.._h........oc.i.c......;._...aah..h";......Oh..o....k...._..c...k..AP....A...OO.e..AC....a.......o.P.._C......a;..;en.A...oSs....C.........a...On._p'...p.AC$oR.......CA.A.C.r.........C.pAOPmCApW...Omr....._..'.-....A..yPC..OCApA......;.......W..yP.pOC.OOP.P._....A.O...P..AOPcA;C......Cc..C..O.._p.PO..P....A.A.Cr...oi'CO...A..P.'.._o..PCP*OOaoAO..AA...pa'..PAAc_OC4.p.Oo4.CACpc4p45C2O266pA3PPC4pCp5a77nO9P1P18018OA1oPO61442O644P4O510145O195p171302231429029584615411248641565115510422216202725357323332181821119437085873591173020965003290327849217198047441242U31443065448082*1835629181546118954146119412172149126255p9611017c12997172113185519289169919111341129131933132819877913631981909313815191t33923511916832U13789U1899o1930J58,U17398153-19-89944199-19-948l7-91891119--4191915-79-135p-1791p1-238101-113-8317p91-119479891-119610-191-110941-191119983128-81-99911581-U11791-9139337294991-39181-4199-4511I981t0-99-14t37-91989131-4-93798-91139945131t949-14-4719o3115419o71798411729-81479141397-p11981-o141999-8493741869583319919-3--4791419398-179491459778914987749799481-1-7917494391d-5786-39-4139694988-947961-442139091d9-951132-7143-779t197647147991-4171-57374,--41939157-799479-od53-99-9-1998971424-J7197-19394219011-7-01393-49974144-81-44993-1-17979414939-9147991-d9-41-7614-9607139713999416411974414974494979749949979439974967372454464744794474J9d747617777151116111010011010110111060271051603001501701040909129111952501510509619280108010825001139006159100151401201160690141011181001140.141101591415116116111060110118141811212111150121911105250113101111317111009370030707020800733743375 107 102 97 104 94 104 103 103 90 93 95 94. 105 100 110 95 90 105 *90 85 100 85 92 95 95 95 95 95 95 95 F 1 78 78 SO 78 . 65 *76 72 70 `78 76 Mph 5.4 8.0 e!o 6.1 65 74 7.9 70 5.8 65 70 65 70 10.7 6.9 65 65 65 6.3 5-9 8.4 7.4 76 7.9 76 5.8 65 65 280 CHAPTER 13 1956 Guide Table 2. Summer Climatic Conditions* (Continued) Suggested Design Wel-BuU> and Dry-Bulb Temperatures Col. 1 8tatb Col. 2 Station1* Col. 3 0Eleva tion Ft Col. 4 Period of . Record0 Col. 5 Highest Temp. Ever . Recorded0 Col. 6 { Design j Dry-Bulb Temp, on T.A.C. 24% Basis9 Col. 7 Design DbytBulb Temp, in Common Use* if* F >F Col. 3 Design Wet-Bulb Temp, in Common Use* "F Col; 9 Averagb Summer Wind Velocitt* Mph m..., Imd.. lows___ Kans.. Peoria................. AP Springfield...........CO Springfield.........AP Evansville........... CO Fort Wayne........ CO Helmer.............. AP Indianapolis--CO Indianapolis.... AP Terre Haute--CO Terre Haute -- AP Davenport...........CO Dee Moines......... AP Dubuque............. CO Keokuk.................CO Sioux City...........CO Sioux City...........AP Concordia............ CO Dodge City.........CO ^Xcity.::::.co 660 603 608 464 885 970 816 800 1146 589 648 979 740 637 1093* 1098 1425 2515 2599 991 Ky.. Topeka................. AP Wichita................. CO Wichita................. AP Louisville............. CO Louisville............. AP New Orleans.... CO 883 1497 1423 563 544 85 Maine.. Md..... Mich... New Orleans--AP Shreveport...........AP Eastport............... CO Portland...............CO Portland............... AP Baltimore.............CO Baltimore.............AP Boston...................CO Boston.................. AP Nantucket...........CO Nantucket........... AP Alpena...................CO Detroit.................. CO Detroit................. AP T^jitting................. CO 8 179 100 185 65 114 43 356 45 45 48 615 1000 632 861 Minn. Lansing............. Marouette----- CO Duluth........... Duluth............ .AP Minneapolis... CO 863 721 1133 1413 945 Minneapolis... AP 873 .CO 951 St. Paul.......... AP Meridian......... CO Meridian......... .AP 708 410 298 Vicksburg....... CO Vicksburg....... .AP 316 266 Mo....... Columbia....... .CO Columbia....... .AP WanML* City.. AP St. Louis........ CO St. Louis........ AP Springfield-- ..AP Billings........... AP Butte............... ..AP Havre.............. CO ..CO 739 787 780 646 597 1270 3584 5538 2498 4175 Kalispell......... CO Miles City-- ..AP Lincoln........... CO Lincoln........... ..AP North Platte. ..CO North Platte: ..AP CO 3004 2629 1189 1185 2815 2788 1219 Omaha............ AP 1009 Valentine-- CO . Elko............... ..AP Las Vegas.... AP CO 2627 5079 1882 4588 Reno.............. AP Winnemucca. ..CO N. H... . Concord......... CO Concord........ ..AP 4417 4293 343 359 1935-1939 1879-1947 1930-1947 1897-1940. 1911--1941 1935-1939 1871-1946 1932-1946 1893-1946 1941-1946 1872-1947 1935-1939 1874-1947 1872-1946. 1889-1944 1940-1946 1885-1947 , 1874-1942 1942-1947 1887-1947 1946-1947 1888-1939 1939-1947 1871-1947 1937-1947 1874-1947 1937-1947 1935-1939 1873-1947 1885-1940 1940-1947 1871-1947 1935-1939 1870-1935 1935-1947 1886-1947 1946-1947 1874-1946 1873-1933 1934-1947 1910-1947 1940-1947 1874-1947 1874-1947 1941-1947 1890-1947 1938-1947 1871-1933 1937-1947 1889-1947 1939-1947 1874-1947 1941-1947 1889-1947 1939-1947 1935-1939 1871-1947 1930-1947 1935-1939 1935-1947 1931-1947 1880-1947 1880-1940 1897-1947 1935-1939 1887-1947 1933-1947 1874-1947 1935-1939 1873-1935 1935-1947 1889^1947 1935-1939 1937-1947 1905-1942 1940-1947 1871-1947. 1871-1941 1941-1947 111 110 109 108 106 107 106 107 no 103 111 111 no 113 111 108 116 109 109 114 108 114 109 107 . 103 102 100 109 93 103 99 107 105 104 101 92 82 104 104 105 102 98 108 106 95 108 104 104 104 105 105 104 104 111 102 112 no 111 105 106 100 108 103 101 108 115 115 109 109 in 114 no 102 117 106 105 108 102 99 64 96 89 91 95 . ioo 93 93 98 9i 87 89 91 ioi 97 96 92 85 97 101 98 98 92 108 93 96 - 98 95 65 95 95 95 95 95 . 95 65 *05 95 ioo ioo 95 95 ioo 90 90 95 92 . '95 '95 95 95 '93 93 '95 95 95 95 ioo ioo 95 90 95 95 65 95 95 95 95 115 95 95 90 76 77 78 75 76 `78 `78 78 78. 78 78 `78 78 '78 *75 78 80 78 70 73 '78 ' 75 75 *75 75. 73b 75 73 73 75 75 `jo *78 *78 *76 78 66 *70 67 65 '78 '78 '78 *78 75 65 65 73 8.2 7.0 8l9 8.6 1L8 7.2 6.9 7;0 . 8.7 7.4 12.5 9.5 lO C6 .M 9.1 8.1 Cooling Load 281; Table 2. Summer Climatic Conditions* (Continued) Suggested Design Wet-Bulb and Dry-Bulb Temperatures Col. 1 State Col. 2 Station1* Col. 3 Eleva tion Ft Col. 4 Period of Record* Col. 5 Col. 6 Highest Temf. Ever Recorded4 Design Dry-Bulb Temp, on T.A.C. 2J7 Basis F Col. 7 Design Dry-Bulb Temf. in Common Use* F Col. 8 Col. 9 Design Wet-Bulb Temp, in Common Use* Average Summer Wind Velocitt* *F - v Mph N. J... N. M.. N.C.. N. D.. Ohio.. Okla.. Ore.. Pa B. I... 8. C... Buffalo......... Canton...... 1 _ Elmira................AP Oswego..................... Rochester........... CO Rochester........... AP Syracuse....... .CO Syracuse.......... .'APAshville.............. CO Charlotte............CO Charlotte............AP Greensboro........ AP Raleigh...............CO Raleigh............... AP Wilmington........ CO Bismarck............CO Bismarck............AP Devils Lake....... CO Dickinson.......... AP Fargo.................. AP Pembina............. AP WiUiston............. CO Akron................. AP Cincinnati..........CO Cincinnati..........AP Cleveland........... CO Cleveland...........AP Columbus...........CO Columbus.......... AP Dayton............... CO Dayton............... AP Sandusky___ ...CO Toledo................ CO Toledo................ AP Ardmore.............AP Oklahoma City. CO Oklahoma City AP Tulsa.................. AP Waynoka.......... ..AP Arlington.......AP Baker..................CO Baker..................AP Eugene............... CO Eugene............... AP Medford............. CO Medford............. AP Portland............. CO Portland............ AP Boseburg.___ CO Curwenaville... AP Erie..................... CO *vv............... AP Hamsburg......... AP Philadelphia.... CO Philadelphia... AP Pittsburgh..........CO Pittsburgh..........AP Beading....;.... CO gcranton............. CO bunbury............. AP Block Island....CO Providence......... CO Charleston.......... CO Charleston.......... AP 45 20 J5 144 5022 5319 7120 4116 3643 4054 114 280 915 836 726 458 948 425 363 609 560 465 404 2280 809 757 896 405 446 78 1675 1655 1481 2599 900 830 1919 104 772 488 669 813 812 820 1086 1002 608 668 626 762 1264 1311 686 1529 881 3501 3374 366 368 1428 1343 98 25 523 2219 771 736 339 200 18 929 1284 311 877 448 46 77 59 31 1874-1947 1935-1939 1931-1947 1866-1946 1931--1933d 1933-1947 1935-1939 1935-1939. 1905-1947 1935-1939 1874-1947 1938-1947 1891-1946 1942-1947 1935-1939 1906-1947 1935-1939 1871-1947 1871-1947 1872-1947 1935-1939 1902-1940 1940-1947 1902-1947 1878-1947 1939-1947 1928-1947 1887-1947 1944-1947 1871-1947 1875-1940 1940-1947 1904-1947 1935-1939 1935-1939 1935-1939 1879-1947 1935-1939 1870-1947 1931-1947 . 1871-1946 1930-1946 1878-1948 1939-1947 1883-1943d 1940-1947 1878-1946 1871-1947 1940-1947 1935-1939 1890-1947 1939-1947 1932-1947 1935-1939 1935-1939 1889-1947 1939-1947 1890-1942 1942-1947 1911-1929 1929-1947 1874-1947 1940-1947 1877-1947 1943-1947 1873-1946 1935-1939 1935-1939 1871-1047 1940-1947 1875-1947 1935-1947 1913-1947 1901-1947 1935-1939 1881-1947 1904-1947 1871-1947 1040-1947 104 105 104 106 99 101 92 . 104 107 107 104 99 103 97 95 99 .. 96 102 100 102 98 . . 102 97 99 103 103 101 104 102 103 114 109 112 112 116 ' 109 110 101 108 108 100 107 106 100 108 99 105 105 100 no 113 109 109 115 111 104 103 104 105 no 115 107 105 109 90 98 96 103 106 100 103 102 105 103 101 93 100 104 103 91 89 93 84 97 97 88 86 88 89 88 93 91 93 96 94 93 92 88 94 90 90 9i 99 99 100 103 95 90 88 95 87 82 85 91 88 89 9i ' 95 95 95 95 95 93 95 93 90 95 93 95 93 93 95 95 95 95 95 95 05 95 95 95 95 95 95 95 95 ioi ioi 96 90 95 90 90 93 95 95 95 95 95 95 93 95 78 70 75 75 73 73 75 13.5 73 75 75 75 : 6.8 78 78 78 6.3 78- 8.4 73 9.6 70 75 ' 73 75 78 6.6 75 li.i 76 78 75 75 77 9.8 77 66 68 70 68 6.6 66 75 78 9.7 75 8.9 75 75 75 75 9.5 78 9.8 282 CHAPTER 13 1956 Guide Table 2. Summer Climatic Conditions*' (Continued) Col. 1 State Col. 2 Station^ Col. 3 VATtONC Ft Col. 4 Con.'5 Col. 6 Design Col. 7 Design Highest Dry-Bulb 1 )By-BuLB Period of Record*1 Temp. Temp, on ^. ReEcovredred0.1 T-A.C. 2*% Basis* Temp, in Common Use* F F F Col. 8 Design V 'et-Bulb Temp, in Common F Col. 6 veragb Sommbb y Wind ELocm* Mpb . Columbia___,. .CO 401 1887-1947, Columbia........... AP i 227 1939-1947d Huron................. CO 1342 I88I-I938d Huron................. AP 1287 1938-1947 Rapid City........CO 3309 1888-1947 Rapid City........AP 3220 Chattanooga... .CO 952 1939-1947 I 1879-1947 I Chattanooga___AP 675 Knoxville........... CO 1024 1940-1947, 1871-19426 Knoxville........... AP 1007 1942-1947. Memphis.............CO 348 1872-1941* Memphis............ AP Nashville............CO 267 714 1941-1947 1871-1947 Nasbvitte........... AP 610 1939-1947 ,, Abilene............... CO 1748 Abilene............... AP 1756 1885-1944'*' 1940-1947 Amarillo............. CO 3686 Amarillo............. AP 3595 1892-1941 1941-1947 Austin................. CO Austin................. AP 625 625 1897-1942 1942-1947 Brownsville........CO Brownsville........AP Corpus Christi- .CO 140 25 21 3922-1943d 1943-1947 1887-1942 Corpus Christi..AP 45 1943-1946 Balias................. CO 732 1913-1940 Dallas................. AP 520 1940-1947 Del Rio............ CO 1020 1905-1947 El Paso............... CO 3792 ETPaso............... AP 3956 1887-1942 1939-1947 Fort Worth........ CO Fort Worth.........AP- 708 728 1898-1939 1940-1947 Galveston...........CO 128 1871-1947 Galveston.......... AP 9 1939-1947 Houston............. CO 198 1888-1947 Houston............. AP 73 1932-1947 Palestine............ CO Port Arthur....... CO Port Arthur..:. .AP 555 64 . 21 1881-1947 1917-1947 1944-1947 San Antonio....CO 770 18S5--1941d San Antonio___ AP 800 1942-1947 Waco....................AP 513 3931-1947 Wink................... AP 2811 1935-1939 Utah.. Milford............... AP 5095 Modena...............CO 5472 1935-1939 1901-1947 Salt Lake City..CO 4346 1874-1947 Salt Lake City..AP 4254 1928-1947 Burlington......... CO 409 1884-1943d Burlington......... AP Cape Henry.......CO 335 24 1943-1947 1874-1947 Lynchburg.........CO Lynchburg.........AP Norfolk............... CO Richmond..........CO Richmond..........AP Roanoke............. AP 644 951 91 180 172 1194 1874-1944 1944-1947 1871-1947 1897-1947 1929-1947 1935-1939 Wash.. Ellensburg......... AP North Head'.. .CO Seattle.................CO Seattle.................AP 1731 199 104 47 1935-1939 1884-1947 1890-1947 1928-1947. Spokane............. CO 2030 I881-1941d Spokane............. AP 1974 1941-1947 Tacoma...............CO Tatocah Island.CO 279 no 1897-1947 1883-1947 W. Va. Wise.. Yakima.............. CO Yakima.............. AP Parkersburg ... .CO Green Bay..........CO La Croese........... CO La Crosse........... AP Madison..............CO 1160 1066 685 598 725 677 1008 1928-1946 1944-1947 1888-1947 1886-1947 1872-1947 1943-1947 1858-1947 Wyo. Madison....___ AP Milwaukee......... CO Milwaukee..........AP Cheyenne........... CO Cheyenne........... AP Lender................ CO Lender................ AP 884 744 707 6144 6161 5448 5568 1935-1939 1870-1947 1927-1947 1873-1935 1935-1947 1891-1946 1936-1947 Rock Springs . .AP 6746 1932-1942 106 104 111 no 106 108 103 105 104 . 102 106 105 106 104 111 109 107 106 109 104 102 100 105 101 110 109 111 106 104 112 no 101 101 108 105 108 102 98 107 104 111 no 103 101 105 106 100 101 104 106 100 105 107 104 103 105 97 100 99 108 104 98 88 110 103 106 104 108 96 107 106 105 106 100 100 102 1 9978 94 94 96 97 96 99 97 93 98 98 99 94 95 92 90 90 si 92 9i 89 87 89 '87 95 95 . *95 95 95 95 95 ioo ioo ioo ioo *95 ioo ioo 100 ioo 95 95 ioo 95 ioo 75 75 70 `76 75 78 78 74 72 78 80 'so '78 `78 69 78 80 'so . 78 79 '78 iol L9 5l 5.7 7.3 1L8 7-6 9.3 8.4 flJ7 9-7 8.8 7.8 95 95 90 '95 95 '95 95 95 85 85 93 85 '95 95 95 95 95 95 95 95 65 65 73 78 75 - '78 78 76 65 65 65 *64 65 75 75 75 75 '75 '65 65 1 T# O 10.1 6.4 i'.i 6.5 5.L 6.4 ,7.9 9.8 i.i Cooling Load 283 Table 2. Summer Climatic Conditions* (Concluded) Suggested Design Wet-Bulb and Dry-Bulb Temperatures Col. 1 Pbov. op Can ada^ Col. 2 Station1* Col,. 3 Col. 4 Col. Col. Col. Col. Col. Col. 10 Col. 11 Col. 12 5 High Ele Period est op Temp. va tion0 Record* on rb- CORD* 6, 7 8 9 Summer Design Temp. 1% 2% 9 FF Design DB Temp. IN Com mon Use* F Design WB Temp. IN . Com MON. Ubv.-` F Avo. Sum- ' . MSB . Wind Vblo-' CITTTM Mfh Alta... Calgary........... AP 3540 1921-1950 97 86 83 80 77 Edmonton.... .AP 2219 1921-1950 99 87 83 80 77 Medicine hat.. AP 2365 1921-1950 106 92 89 86 82 B.C.... Vancouver........ AP 22 1938-1950 87 80 77 75 72 Man... Winnepeg..... AP 786 1921-1950 108 89 86 84 81 NS.... Fredericton... no 164* 1921-1950 102 89 87 84 81 Saint John....... .CO 119 1921-1950 93 80 - 77 75 72 N.S.... Halifax........... oo 83* 1921-1950 94 80 78 76 73 Sydney............. .AP 197* 1921-1950 95 `85 83 80 75 Out.... Fort William... AP 644* 1921-1950 ` 104 85 82 79 76 North Bay....... .AP 1210* 1925-1950 99 83 80 77 74 Ottawa.............. .AP 339* 1921-1950 102 89 86 84 SI Sault Ste. Mane. CO 635* 1921-1950 99 83 80 77 74 Toronto............ CO 379 1921-1950 105 88. 86 83 81 Toronto............ AP 578* 1938-1950 101 90 87 84 81 P.E.I.. Charlottetown CO 74* 1921-1950 98 82 79 77 74 Que.. . Montreal........... CO 187 1921-1950 97 87 84 82 79 Montreal... r.'rr TAP 98* 1942-1950 96 88 85 83 80 Quebec.............. .CO 296 1921-1950 96 85 82 80 77 Bask. -. Regina............ .AP 1884* 1921-1950 111 91 88 85 81 .Saskatoon........ .AP 1645* 1921-1950 104 92 89 85 81 90 9G 90 80 90 90 90 90 93 93 90 90 90 90 66 9.7 : 68 . 8.9 65 9.1 67 7.8 7i 11.5 75 7.9 75 6.6 9.9 8.4 9.6 75 8.9 75 75 8.1 8.7 8.7 75 9.9 ; 9.5 75 9.0 71 12.4 70 10.7 Notes for Table 2 Data compiled from U. S. Weather Bureau Data and various other sources. b Column 2. The station designation AP or CO indicates airport or city office station, respectively. 6 Column 3. The elevations marked c are ground elevations of the-station. All other elevations given are the actual elevations of the thermometer bulb above mean sea level, corrected to 1948. . d The periods of record indicated apply only to the highest temperature ever recorded shown in Column 5, and do not necessarily include all of the summer months of the first year indicated. The last year indi cated includes July or August, except those marked d which terminate prior to July of that year. It should be noted that Column 6 in the United States section of the table applies only to airports, as these data for city stations are not available at this time. The temperature shown is the maximum hourly Outdoor temperature which has been equalled or exceeded 2| percent of the total hours of June, July, August and September for the 5-year period 1935-1939 inclusive. It is pointed out that in most cases the airport stations are outside of the city, and that these data would apply primarily to rural areas. . Columns 7 and 8 in the United States section and Columns 9 and 10 in the Canadian section of the table record wet and dry-bulb temperatures in use by A.S.H.A.E. members as reported,by Chapter secretaries for various stations. Where such values were not available, the design temperatures published by API or ob tained from various other sources have been inserted. , 8 The average wind velocities in Column 9 in the United States section were furnished by the-U.S. Weather Bureau, corrected to 1948. In general these velocities are averages for the months of June through September. b The bulletin published by the A.8.H.AK. lor the annual weather data of Detroit indicates73 F as the design wet-bulb temperature which haa been equalled or exceeded 5 percent of the hours for period 1935-39. | Blank spaces indicate data not available. . / The data for Canada were compiled by D. W. Boyd and Morley Thomas from the reoords of the Meteoro logical Division, National Research Council of Canada. The highest temperature ever recorded in the Canadian section of the table is for the 30 year period, 1921-1950, where available. In some cases the stations have been relocated and in a few instances some year, are missing. . . 1 In the Canadian section of the table, the summer design dry-bulb temperatures for the basis of 1, 2}, * and 10 percent are the Fahrenheit temperature values at or above which these percentages of all the July Coyr*y outdoor temperatures occur, for the years 1941-1950 inclusive. T^. Most of the wind speeds are based on the periods ending in 1947 which are somewhat shorter than the Periodsfor the highest temperatures. The three months June, July and August were used. INSTANTANEOUS HEAT LOAD The total cooling load is frequently divided for convenience into two components, sensible heal and latent heat. While this subdivision is not imperative, past practice has found it convenient. A gain of sensible heat is considered to occur when there is a direct addi- 284 CHAPTER 13 1956 Guide tion of heat to the enclosure by any one or all of the mechanisms of conduc tion, convection, and radiation. A gain of latent heat is considered to occur when there is an addition of water vapor to the air of the enclosure. For example, when the humidity in an enclosure is increased by water vapor emitted by human occupants, or by water vapor resulting from a process such as cooking, the heat required to vaporize the water does not come from the air. Maintenance of a constant humidity ratio in a sealed enclosure requires the condensation of water vapor in the cooling apparatus at a rate equal to its rate of addition within the enclosure. The rate of heat removal from this condensing vapor would be substantially equal to the product of the rate of condensation and the latent heat of condensation; this product, expressed in Btu per hour, would be called a latent heal load. As a further example, the infiltration of outdoor air with a high drybulb temperature and a high humidity ratio, and the corresponding escape of room air at a lower dry-bulb temperature and a lower humidity ratio, would increase both the sensible heat load and the latent tad load. SOLAR RADIATION Magnitude of Solar Radiation If a plane surface were set perpendicular to the sun's rays (i.e., for normal incidence) outside the earth's atmosphere, it would receive solar radiation of about 420 Btu per (hr) (sq ft). A similarly oriented surface, at the surface of the earth, would receive considerably less solar energy because a large part of the radiation is scattered in passing through the air, moisture, smoke, and dust which comprise the earth's atmosphere, and also, because some of the atmospheric constituents, notably water vapor, ozone, and carbon dioxide, absorb solar radiation. The intensity of solar radiation varies with wave length, reaching a peak at about 0.5 microns (a micron equals 1/1000 of a millimeter) and, for practical pur poses, is confined to the radiation spectrum between 0.3 and 2.3 microns. The effects of scattering and absorption vary with the wave length, but to make an exact analysis of these phenomena is impracticable in air conditioning estimates. The important principle to remember is that the total radiation It, received by a surface at the earth, is the sum of /D and Ia, where Id = K IDa = the direct or beamed solar radiation, Btu per (hour) (square foot of receiving surface). 7do = the direct solar radiation normal to the' sun's rays, Btu per (hour) (square foot of receiving surface). Id -- the sky or diffuse solar radiation, Btu per (hour) (square foot of receiving surface). This comes principally from the atmosphere itself as a conse quence of scattering. Vertical surfaces also receive solar radiation by reflection of direct and diffuse radiation from the ground and other objects. Such radiation is usually diffuse. The diffuse radiation strikes at all angles. 11 = total incident solar radiation, Btu per (hour) (square foot of receiving surface). K = cosine of the angle of incidence, 8. For a vertical surface, 0 is defined >n Fig. 1. Standardized, practical-purpose values of the direct solar radiation Jn incident upon a plane perpendicular to the sun's rays at the earth's surface. Cooling Load 285 Fig. J. t- WALL A2IMWTH, f *-S0LAR azimuth, f -LINE PRRDJCULAR TO VERTICAL WALL . ,* Definition of Solar Angles . ' '' .. , have been proposed by Moon.4 Table 4 gives these values. They are representative of a clear summer day at sea-level elevation, and are nearly identical with values derived from suggested design' sol-air temperatures for Lincoln, Nebraska.6 Values typical of a humid industrial area derived from sol-air data for New York City6 are also given in Table 4. Day-to day changes in the amount of dust and water vapor in the atmosphere cause large differences in solar intensity values observed on cloudless days at a given locality-.- For example, it has-been observed in Cleveland that . Table 3. Outdoor Air Requirements Application Smoking Cvm peb Person^ Cfm peb Sob Ft op Floor Recommendei [ Minimum8 Minimum Apartment Average.. DeLuxe.. Banking Space............. Barber Shops... Beauty Parlors. Brokers' Board Rooms.............................. I Very Heavy... -- Cocktail Bars....................................... Corridors (Supply or Exhaust). Department Stores........................ * I Directors' Rooms.. Drug Stores'5. f Factories4*- f............................ Five and Ten Cent Stores,. I Considerable.. None............... Funeral Parlors.. Garages1*............... I None............ . . None................. Hospitals Operating Rooms1* *......... _ Private Rooms.................. Wards.:.................................... ! None___ None.... Hotel Rooms............................................. ! None___ Kitchens Restaurant............................. . laboratoriRese*s.i.d..e...n..c..e.............................................................. Some.. Meeting Rooms........................................1 Very Heavy.. Offices General...................... Private/.!..'.'.'...................... .......... I ?r0me- - Rest,iauPraroivt aCteaf_e_t_e!r!ia!!............... VT Dining Room. School Rooms4*.......................................... None.... 20 10 15 10 50 40 n 50 W 10 n 10 30 20 30 20 50 15 25 30 12 15 10 10 7* 10 7*/ 20 25 5 30 J* n 25' 10 25 15 30 10 15 25 10 12 6.25 0.05 ----------- o.io i.o' 2.0 0.33 0.33 4.0 2.0 1.25 6.25 0.25 Shop, Retail.............................................. None.... Theater4*..................................................... None....... Theater., .. ............... Some.......... Toilets*1 (Exhaust)........................................................ io' 7*. 7j 5 W ... | ... | 2.6 . * Taken from present-day practice. --- ---- lfPacyargxseaprrdeocofitafhlaesnotewusrotch.eestidcos'fSS._eec_eeom_Sllnooe--LtcceaaaaNmmll ccaKiinnoo.tiwaaddoeettn,iissouoanwwnwl Rhhoo. iinrrccnhhll"oorJmmccTaahaalliyysccoggoisddooeevvcsseeo',.rrnnnt..a8mAinllMaonauty-tfsbriedeeegoavier.rrneecdnombuymueexnmhdiaenudimstt.oumo*vMiesracuyosmebdee, tgaokveertnheed explosion See National Board of Fire Underwriters' pamphlet No. 56. 286 CHAPTER 13 1956 Guide "? Table 4. .Values of Id,, Direct Solar Radiation Received at Normal Incidence at the Earth's Surface, and Values of /a, Diffuse or Sky Solar Radia tion, Received by Variously Oriented Surfaces Solar Altitude 0, Degrees Bru peb (hour) (square foot) For Clear Atmospheres For Industrial Atmospheres Direct * Normal Radi ation Diffuse or Set Radiation*0 Direct*1 Normal Radi ation Diffuse or Sky Radiation* 0 AM-* l 5 10 15 20 25 30 35 40 45 . 50 60 70 . 80 90 NE 87 123 166 . 197.. 218 235 248 258 266 273 283 289 292 294. . 6n 11 20 14 27 15 32 16 35 17 36 17 36 18 36 19 35 19 33 21 28 2_2_ 23 __ --. ` -- - S w Horiz. NE S 44 87 11 10 13 12 15 13 17 15 19 16 21 17 23 18 25 19 27 21 29 23 __ -__ T-" -- 7 14 19 23 26 28 30 31 . 32 33 34 35 __ -- 34 58 80 103 121 4 11 5 8 22 9 11 28 13 13 36 17 16 43 21 136 18 ' 47 24 148 19 50 27 158 20 50 30 165 21 49 31 172 22 47 34 181 ' 22 188 22 195 - -- 200 -- 41 37 34 41 ---- -- -- w Horiz. 39 7 18 9 24 12 31 16 38 18 44 21 48 23 52 25 55 27 58 30 63 34 69 -- ---- pit-. N W s E Horiz. N W S E Horiz. " Moon's4 proposed standard for sea level, 20 mm precipitable water vapor, 300 dust particles per cu cm, 2.8 mm Hg partial pressure of ozone. b For 40 deg north latitude on about .August 1. . c Based on observations by ASHAE Laboratory at Cleveland on cloudless days during which the observed normal incidence values closely approximated the normal incidence values tabulated. d Derived from recommended design sol-air temperatures* for New York City for a horizontal surfacewith bsorptivity of 1.0. values of the order of those given for industrial atmospheres are usually associated with dry-bulb and wet-bulb temperatures near the design values of 95 F and 75 F (67 F dew-point). On the other hand, values approaching or exceeding those for a clear atmosphere are often encountered during Cleveland summers, but with dew-point and maximum dry-bulb temperatures 10 to 15 deg lower. Considerable judgment, therefore, is required in selecting solar intensity values for design purposes. Data regarding the irradiation of vertical and horizontal surfaces by diffuse or sky radiation are few. Suggested design values for a 40-deg latitude on August 1 (18 deg declination, north) are given in Table 4 for the two types of atmospheres. These are based upon observations made on cloudless days in Cleveland over a period of several summers. Since less extensive data were available for industrial atmospheres, there is more uncertainty regarding these values. In both instances, the values include an unknown amount of ground reflection, which may be expected to vary with location. It should be noted that clouds which do not obscure the sun tend to increase diffuse radiation values. Nearby buddings may reduce diffuse irradiation by partial shading. Calculation Tables The irradiation of a surface by the sun is the product of 1dd, the direct normal radiation (see Table 4), and the cosine K oi the incident angle, A. For horizontal surfaces, the cosine K equals the sine of the solar altitude. Cooling Load 287 Table 5. Values of K, the Cosine of the Incident Angle, for Variously Oriented Walls and-a Horizontal Surface Computed for 18 Deg Declination, North (August 1) Sun Time AM i K ovCosine the Incident Angle SB Ho&n. 6 a-m'. 7 8 9 6 pja. 5 4 3 5 a.m. 6 7 8 7 p.m, 6 5 4 8 ajQ. 7 p.m 8 8--. 7 5" 84 93 10 2 11 1 12 pI- 0.287 0.144 0.030 0.862 0.753 0.604 0.427 0.234 0.039 0.400 0.237 0.079 0.934 0.840 0.705 0.533 0.337 0.129 0.385 0.199 0.010 0.922 0.813 0.656 0.465 0.252 0.030 NW 0.919 0.824 0.672 0.476 0.246 0.000 0.914" 0.951 0.919 0.824 0.673 0.475 0.246 0.000 0.920 0.951 0.918 0.824 0.073 0.475 0.247 0.000 W 0.484 0.548 0.561 0.524 0.438 0.310 0.147 0.358 0.505 0.694 0.631 0.614 0.542 0.424 0.265 0.378 0.532 0.643 0.700 0.699 0.642 0.532 0.375 SW 0.068 0.144 0.192 0.208 0.069 0.196 0.292 0.354 0.375 0.078 0.265 0.166 0.316 0.433 0.505 0.530 0.183 0.375 SB 0.156 0.367 0.566 0.737 0.886 0.951 0.978 0.009 0.199 0.391 0.566 0.713 0.829 0.903 0.927 0.078 0.233 0.399 0.545 0.669 0.766 0.829 0.848 Horiz. For vertical walls, K is a function of the solar altitude |3 and the wall solar azimuth y, thus .K cos O = cos 8 cos y (\1) These three angles are defined in Fig. 1. Values of K are given in Table 5 and values of 0 and y are given in Table 6 for 18 deg north declination (August 1). " - To compute K values for orientations other than those given in Table 5, third angle 4>, the solar azimuth, is required. In this discussion, <f> will be measured east from south in the morning, and west from south in the after noon. Hence, <fi values are equal to 90 deg minus the y values for an east or west facing wall, except when Table 6 shows the south walls to be in the shade. In this case <j> equals 90 + 7, that is, <j> is greater than 90 deg. The wall azimuth is the angle, measured east-from south to the per pendicular to the wall for walls which have an easterly component, and west from south for those having a westerly component. For example, for a wall facing northeast is 135 deg. . The wall solar azimuth y may be found according to the following schedule: . ' For walls facing east of south: r = <t> -- ^ a.m. Y = <0 + f p.m. For walls facing west of south: y = 4> $ a.m. <y = 4> -- yj/ p.m. Treat negative values of y as if they were positive. If 7 is greater than 90 deg, the wall is in the shade. 288 CHAPTER 13 1956 Guide orTable 8.- Values the Wall Solab Azimuth, y, fob Variously Oriented * ' ' Walls and Solas Altitude ' Computed for 18 Deg Declination, North (August 1) a Bun Tom e E S AM-* i 1 6 a.m. 6 P.m, 75 O8 4 fc 9 3 o a 10 P 11 2 1 8 12 6 a.m, 7 p.m. I6 o $5 7 8 6 5 4 a a 9 3 P 10 2 O 11 1 12 5 a.m. 7 p.m. I6 O Z 7 8 65 4 o a 9 sP 10 11 12 3 2: 1 pii-. Solas Altitude 9 Degrees 9.0 21.6 34.6 47.5 60.0 72.0 78.0 0.6 11.6 23.0 34.6 45.5 56.0 64.5 68.0 4.5 13.5 23.5 33.0 42.0 50.0 66.0 58.0 . Asimuth Angle 7, Degrees N NE 74 81 88 shade 29 36 43 61 62 ... ' 83 shade 66 76 85 shade 21 31 40 50 61 76 shade 67 78 90 shade 22 33 45 57 70 87 shade N NW E 16 9 2 6 17 38 90 24 14 5 5 16 31 55 90 . 23 12 0 12 25 42 64 90 W be 61 54 47 39 28 7 45 69' 59 50 40. 29 14 10 45 68 67 45 33 20 3 19 45 SW s 8W shade 84 73 62 0 shade 45 shade 85 74 59 35 0 shade 80 45 80 78 65 48 26 0 Ls shade 71 45 SE Values of K for other seasons and latitudes may be found in the litera ture,7 or may be computed from data given in Hydrographic Office Bulletin No. 214, Tables of Computed Altitude and Azimuth8 and the Ephemeris of the Sun.9 Table 7 shows the variation of solar declination during the months ordinarily requiring cooling. >. Example 1: Find the solar azimuth <j, at 6:30 p.m. at 40 deg north latitude on August 1st. Solution: From Table 6 in the column of y for a wall facing west <j> for 6:00 p.m. is 90 -f- 14 = 104 deg, and at 7:00 p.m. is 90 + 24 = 114 deg. .By interpolation, for 6:30 p.m. is 109 deg west of south (at 5:30 a.m. <t> would be 109 deg east of south.) Example S: Find K for a wall facing 18 deg east of south at 10:00 a.m. on August 1 at 50 deg north latitude. Solution: The wall azimuth is 18 deg. The solar azimuth is 48 deg east (Table 6). The wall solar azimuth is 48 -- 18 or 30 deg. From Table 6, /3 is 50 deg. Then F -- nac ft p.rva . Table 7. Approximate Solar Declinations in Deqbees DATS April 1 April 15 May 1 May 15 Declination 4.5 10.0 15.0 19.0 Date June 1 June 15 July 1 July 15 Declination 22.0 23.5 23.0. 21.5 Date Aug- 1 Aug. 15 Sept. 1 , Sept.15 Declination 18.0 14.0 8.5 3.0 Cooling load 289 Example 8: Find K for the wall in Example B at 3:00 p.m. ' Solution: The solar azimuth is 65 deg west. The wall solar azimuth is therefore 65 + 18 = 83 deg. The angle 0 is 42 deg. K = cos 42 X cos 83 = 0.743 X 0.122 = 0.091. Example 4: Find the total solar irradiation for the wall for the conditions of Example 8. Solution: Use clear atmosphere solar intensities. At 50 deg altitude, the direct normal radiation is 273 Btu per (hr)` (sq ft). Then, 7d = K X /d. = 0.557 X 273 = 152.0 Btu per (hr) (sq ft). By linear interpolation, the diffuse irradiation is /a = 25 + f (33 -- 25) = 26.6 Btu per (hr) (sq ft). The total solar irradiation is h = 152.0 + 26.6 = 178.6 Btu per (hr)(sq ft). PERIODIC HEAT FLOW THROUGH WALLS AND ROOFS The calculation of heat flow, through a structural section of a building exposed to the weather, requires consideration of the diurnal cycles of solar irradiation and air temperature. These cycles and other factors lead to a periodic variation-in the instantaneous rate of heat flow into the weather surface, and a related periodic variation in the rate of heat flow into the air conditioned space. Because of heat capacity and other factors, these - heat flow cycles are, in general, out of time phase and unequal in amplitude. In order to calculate the rate of heat entry into the weather surface of a building, it is necessary to know: 1. The intensity of direct solar radiation striking the surface. . 2. The absorptivity (or reflectivity) of the surface for direct solar radiation. 3. The intensity of diffuse or sky solar radiation striking the surface. 4. The absorptivity (or reflectivity) of the surface for diffuse or sky solar radia tion. 5. The rate at which the surface emits radiation to the sky and other surroundings. .6. The rate at which the surface absorbs the low temperature radiation emitted by the sky and other surroundings by virtue of their temperatures and radiat ing characteristics. 7. The temperature of the surrounding air. 8. The temperature of the outer building surface. 9. The unit convective conductance for heat transfer between the air and the building surface. . The Sol-Air Temperature . The complex interrelationship of the above factors can be considerably simplified through the use of the sol-air temperature concept. The sol- air temperature t, is the temperature of the outdoor air, which, in the absence of all radiation exchanges, would give the same rate of heat entry mto {he surface as would exist with the actual combination of incident solar radiation, radiant energy exchange with the sky and other outdoor sur roundings, and convective heat exchange with the outdoor air. The sol-air temperature data6, 10 as developed by Mackey and Wright for an industrial atmosphere were used as a basis for preparing Table 8 showing summer design sol-air temperatures. Sol-air temperatures may a!so be estimated from experimental observation of surface temperatures 290: CHAPTER 13 1956 Guide Table 8. Summer Design Sol-Air Temperatures Used for Tables 9 AND 10 Soi-Aib Temperature (. Fahrenheit Deobees Mean Sun Tm Ratio4: 12 Midnight 1 AM 2 3 4 5 6 7 8 9 10 11 12 Noon 1 PM 2 3 8 9 10 11 Any Sur- faceb 77 76 76 75 74 74 74 75 77 80 83 87 90 93 94 95 94 93 91 87 85 83 81 79 North 0.225 77 77 76 76 76 76 75 75 74 74 74 74 76 74 91 75 106 77 119 80 129 83 137 87 142 90 144 93 140 94 132 95 120 94 107 93 96 91 90 87 85 85 83 83 81 81 79 79 East 0.225 0.125 0.225 0.U5 0.225 0.125 77 76 76 75 74 75 110 123 126 125 117 108 92 93 95 95 94. 93 91 87 .85 83 81 79 77 76 76 75 74 80 93 100 103 104 100 96 85 83 81 79 77 76 76 75 77 76 76 75 77 76 76 75 77 76 76 75 74 74 74 75 74 74 74 75 74 74 74 75 74 74 74 75 82 93 102 110 78 86 93 99 77 80 83 89 77 80 83 87 114 115 111 104 104 105 104 100 96 110 124 135 92 102 111 119 99 95 91 96 141 120 94 139 118 91 125 111 87 103 94 85 83 81 79 .0 85 83 81 79 86. 2 85 83 81 79 93. 9 85 83 81 79 88. a = surface absorptivity, dimensionless: root = u.y; oara light walls = 0.5. fco -- ua -- ...., -- convective conductance = 4.0 Btu per, (hr) (F deg). 6 values in this column are magnitudes of fo, the outdoor air temperature. of walls and roofs which appear in the literature.11,12 Both analytical and experimental studies have been made on the problem10 of heat flow through walls and roofs. Those concerned with a further study of the details of cooling-load estimates in particular relation to periodic heat flow will find much of value and interest in the reports of experimental studies of these problems.10,11. 16 13. w. >5 The reader may also refer to the Cooling Load chapter of The Guide 1952 for the theory of heat flow through walls and roofs. PRACTICAL TABLES FOR CALCULATING SOLAR HEAT GAIN THROUGH WALLS AND ROOFS The analytical10 method reported by Mackey and Wright was used by Stewart10 to obtain temperature differentials based on Table 8 and shown in Tables 9 and 10. These analytical procedures, as well as those using Tables 9 and 10, presented here, yield generally higher rates of heat gain Cooling Load 291 than reported for Pittsburgh in early A.S.H.A.E. experimental studies. Current authoritative opinion indicates a preference for analytical calcu lations. Thermal and physical properties of materials used in these tables are given in a paper.16 The rate of heat flow is obtained by multiplying the overall heat transmission coefficient of the structure by the equivalent temperature differential obtained from the tables. Tables 9 and 10 were developed by using an outside surface conductance of 4.0 and an inside film conductance of 1.65 Btu (hr) (sq ft) (F deg). A reduction was made in the temperature differentials for roofs amounting to some 20 percent of solar radiation as explained by Stewart.16 This was to compensate for several factors, one of which is the radiant heat lost to the sky which is not included in the Mackey and Wright method. Recent experimental work by Parmelee17 and previous work by Brunt18 gives data showing the magnitude of this radiant heat loss from a roof or wall to the sky. Temperature differentials for roofs probably would be reduced be low those shown in Table 9 whenever the radiant heat lost to the sky is in cluded in calculation of sol-air temperature. The temperature differentials for roofs were based on an inside surface conductance of 1.65 because the charts prepared by Mackey and Wright10 used this value, and it was not considered practicable to repeat their work using a different film coefficient. An examination of the values given in their paper indicates that the tem perature differential would be changed very little even if a value 1.20 were used instead of 1.65. But to obtain the heat flow rates through roofs, more accurate values will be obtained if the overall heat transmission coefficient is calculated using 1.2 as the inside film conductance for summer. The roof coefficients of transmission for summer shown in Table 11 are based on surface conductances/cro of 4.0 for an outside roof surface and 1.20 for an inside ceiling surface. The outside conductance 4.0 is used for summer because it corresponds to a wind velocity of approximately 7.5 mph averaged for rough and smooth surfaces, and is more representative of summer wind velocities. Also, the lower wind velocity should be used in order to be on the safe side in determining the sol-air temperature. The inside conductance 1.20 is used because the convective portion of the film conductance for downward heat flow from a horizontal surface is appre ciably less than the winter conductance for heat flowing upward. Since there is little difference in wall transmission coefficients for summer, based on the conductances of 4.0 and 1.65, and the winter coefficients, based on 6.0 and 1.65, it is recommended that the overall coefficient V, for walls, be taken directly from the tables in Chapter 9 in which they are based on an outside film conductance of 6.0, corresponding to a 15 mph wind velocity. Advantages of Equivalent Temperature Differential Method The advantages of the equivalent temperature differential method of determining the total heat transmission are given in following paragraphs, and are apparent from Examples 6 to 7. . 1- The total sensible heat flow is obtained by multiplying the overall heat trans mission coefficient, U, and the equivalent temperature differential indicated in fables 9 and 10. 2. The temperature, differentials listed for a few representative types of construc tion may be used on all classes of walls and roofs, even though the overall heat trans mission coefficient is different, provided the structure has thermal and physical Properties similar to one of those listed in Tables 9 and 10. 3. Adjustments can be made, according to instructions given in the footnotes, for om and outdoor conditions different from those on which the tables are based. CHAPTER 13 1956 Guide Table 9 Total Equivalent Temperature Differentials for Calculating Heat Gain Through Sunlit and oiiaueu Ropfs Description op Roof Construction 1" Woodb or 1" Woodb + 1" or 2" Insulation P.M. 8 | 10 12 2 4 6 8 10 12 oofs--Exposed to Sun 12J 38 54 62 50 26 10 4 0 Cooling Load 293 5. Corrections. For temperature difference when outdoor maximum design temperature minus room is^dif-' ferent from 15 deg. If the outdoor design temperature minus room temperature is different from the base of 15 deg, correct as follows: When the difference is greater (or less) than 15 deg add the excess to (or subtract the deficiency from) the above differentials. ' For outdoor daily range of temperature other than 0 deg. If the daily range of temperature is less than 20 deg, add 1 deg for every 2 deg lower daily range; if the daily range is greater than 20 deg, substract 1 deg for every 2 deg higher daily range.. For example, the daily range in Miami, Florida is 12 deg or 8 deg less than 20 deg. therefore, the correction is + 4 deg at all hours of the day. -. Light Colors. Credit should not be taken for light colored roofs except where the permanence of the light color is established by experience, as in rural areas or where there is little smoke. When the exterior surface of roof exposed to the sun is a light color, such as white or aluminum (which absorb approximately 50 percent and reflect 50 percent of the solar radiation) add to the temperature differential for roof in shade 55 percent of the difference between the roof in sun and roof in shade. When the roof exposed to the sun is a medium color such as light grey, blue or green, or bright red, add 80 percent of this difference. - For solar transmission in latitudes other than 40 deg north, and in other months. The table values of tem perature differentials will be approximately correct for a roof in the following months: Medium Construction Roofs--Exposed to Sun .'2" Concrete or 2" Concrete + 1" or 2" Insulation or .2* Woodb . 6 30 48 58 50 32 14 , 2 Lati tude (deg) North Latitude * Months Lati tude (deg) South Latitude . ' Months 2" Gypsum or 2' Gypsum + 1" Insulation 1* Woodb or 1 ' 2" Woodb or i+ V Rock Wool 2" Concrete or [in Furred Ceiling 2' Gypsum ) 0 20 40 52 54 42 20 10 6 4" Concrete or 4" Concrete with 2' Insulation 0 20 38 50 52 40 22 I12 1 l Heave Construction Roofs--Exposed to Sun 0 All Months 10 All Months iS All Months Ail Months 20 All Months except Nov, Dec, Jan 20 All Months except May, June, July 30 Mar, Apr, May, June, July. Aug. Sept 30 Sept, Oct, Nov, Dec, Jan, Feb, Mar 40 April, May, June. July, Aue . 40 Oct, Nov, Dec, Jan, Feb 50 May, June, July 50 Nov, Dec, Jan For other months, the total temperature differential (tx) may be approximated by the use of the following orraula: fx = fa + (tv -- fa) iy 6' Concrete 6" Concrete + 2' Insulation 46 42 Roofs Covered with Water--Exposed to Sun Light Construction Roof with 1* Water Heavy Construction Roof with 1" Water Any Roof with 6' Water 4' 16! -2 -4 00 44 32 44 34 14 10 16 14 10 8 12 14 2 10 4 where fa = temperature differential for the same roof in shade for desired time of day; obtained from Table 9. ly ~ maximum solar transmission through glass, Btu per (hr) (sq ft) for fiat skylight in Aug., 40 deg * north latitude (Note: this is maximum value irrespective of time). , It =* same as 7y except use the maximum value for fiat skylight, for month, and latitude desired for fx. ' fv = temperature differential for particular roof exposed to sun for the desired time of day from Table (Note tkat this makes adjustment only for solar radiation and that there may be additional correction for out door temperature.) Roofs with Roof Sprays--Exposed to Sun Light Construction Heavy Construction 0 4| 12 18 -2 -2 2 8 16 12 14 14 10 12 2 10 Roofs in Shade Light Construction Medium Construction Heavy Construction 0 --2l -2' a Includes fin. felt roofing with or without slag. May also be used for shingle roof. of the wood. ^Nominal thickness -* Examples of Use of Equivalent Temperature Tables Example 5: Given: A roof is constructed of 6 in. of stone concrete with 2 in. of insulating board and tar felt roofing f in. thick, and is exposed to the sun. _The loca tion is the central part of the United States. Find the rate of heat flow into building at 2:00 p.m. during July for an outdoor design temperature 95 F, and an inside tem perature 80 F. . Solution: From Table 9 in 2 p.m. column for 6 in. concrete plus 2 in. insulation, find the total equivalent temperature differential 34 deg. The overall heat trans mission coefficient for summer is taken from Table 11 and is found to be 0.13. The heat flow rate equals 34 X 0.13 = 4.42 Btu per (hr) (sq ft). Example 6: For the conditions of Example 5, find the rate of heat flow into build NOTES FOR TABLE 9 Total heat transmission from solar] [radiation and temperature difference l between outside and room air. Btu | per (hr) (sq ft) of roof area Equivalent temperaturel ^ idifferential from above! table Heat transmission] coefficient for sum-1 mer Btu per (r)| (sq ft) (F deg) ing at 2:00 p.m. during July for design temperatures of 105 F (outdoor) and 78 F (in door). Daily range of temperature 30 deg, t.e., outdoor temperature minimum of '5 F which occurs at 4:00 or 5:00 a.m.; this being 30 deg less than the maximum. Solution: Make correction in equivalent temperature differential in accordance with Note 5 in Table 9 as follows: . ' 'li AuasnSedHdmAiniEncioamrlciugumilnaatteilomtnessptesuernaewtTura.ebaUletU8nU.i)gMhHFis.oUarp.tvyp.pr_oic_x_ai_ml_d_ae_te_s_ilgy_n75dFay(wdahielyrerathnegemoaf xteimmupmeraotuutrdeo,o2r0tFem) mpeeraantu2r4ehr-t-em The correction for 27 deg design temperature difference is (27 -- 15) *= + 12. perature 84 F for a room temperature of 80 F. All roofs have been assumed a dark coior which absorbs w 30_20\ (perc2.enAtpopf lsicoalatirorna. diTahtieosne, avnaldueresflmecatsy obnelyus1e0d pfeorrceanllt.normal air conditioning estimates; usually without' ------^-- ) = -- 5. ........................ correction, in latitude 0 deg to 50 deg north or south when the load is`calculated for the hottest weather. Note 5ex3p.laPinesakbeodwRtoooafsd. juIsft tthhee treomofpiserpaetuarkeeddiaffnedretnhteiahl feoartogtahienr irsoopmrimanadriloyudtduoeotrotesmolpaer rraatduiraetsio. n, use for the area of the roof, the ares projected on a horizontal plane. ' * 4. Attics. If the ceiling is insulated and if a fan is used in the attic for positive ventilation, the total tem Net total correction is + 12 -- 5 = +7. The heat flow rate at 2:00 p.m. is (34 + 7) X 0.13 = 5.32 Btu per (hr) (sq ft). perature differential for a roof exposed to the sun may be decreased 25 percent. 294 CHAPTER 13 1956 Guide Table 10 Total Equivalent Temperature Differentials for Calculating ' Heat Gain Through Sunlit and Shaded Walls- ________ >_ ' Son Time North Latitude Wald Facing \ A.M. ' 8 | 10 | 12 P.M. 2 | 4 | 6 | 8 | 10 | 12 Exterior color of Wall--D = dark, L = light Dl l|d| l|d| l|d|l|d|l|d|l|d|l|d|l|d[ L South Latitude ` Wall Facing Frame NE E SE S SW w NW N (Shade) 22 10 30 14 13 6 -4 -4 24 36 26 4 12 18 16 0 14 32 28 22 10 16 18 12 12 10 14 14 14 14 10 10 12 12 14 14 14 14 10 10 24 16 16 14 14 14 10 10 30 20 26 20 16 14 10 10 6 6 6 6 4 6 4 6 2 2 2 2 2 2 2 2 --4 -4 0 -2 -4 0 0 -4 -4 0 -2 -4 -2 -2 6 6 6 4 4 6 4 4 26 22 40 '28 42 28 24 20 20 12 40 28 48 34 22 22 12 10 24 20 40 26 34 24 10 10 14 14 12 12 8 8 6 8 6 4 4 8 4 4 2 2 2 0 2 2 2 0 SE E NE N. NW W SW S (Shade) 4 In. Brick or Stone Veneer + Frame NE E SE S SW w NW N (Shade) -2 -4 24 12 2 0 30 14 2 -2 20 10 --4 -4 -2 -2 20 31 28 12 10 17 16 6 10 14 26 24 6 14 16 16 12 12 18 26 10 12 14 18 14 14 14 20 14 14 14 16 12 12 12 12 12 12 12 12 10 10 10 6 10 8 8 8 64 66 6 `6 4 4' SE E NE N 0 -2 0 -2 0 -2 0 0 -4 -4 -2 -2 -4 -4 -2 -2 2 4 2 0 2 2 2 0 12 10 8 6 8 8 6 6 32 26 12 10 22 18 12 10 36 40 30 12 26 28 22 12 34 42 34 12 24 28 24 12 10 16 12 8 86 14 .6 10 6 84 6 6 6 4 NW W SW S (Shade) 8 8In. Hollow Tile or In. Cindeb Block NE E SE S SW w NW N (Shade) 0 4 2 0 00 2 12 02 00 0 4 0 0 20 24 16 2 10 12 8 0 16 '28 20 12 10 14 12 6 10 20 20 24 6 12 14 14 12 12 14 26 10 10 12 16 14 14 14 20 12 12 10 8 12 14 .10 10 12 12 10 8 14 12 10| 8 8 8 6 6 2 0 2 020 424242 0 0 002 0 -2 -2 -2 -2 -2 -2 6 6 4 0 4 4 2 0 12 10 8 6 10 26 8 18 6 12 6 10 18 30 20 26 14 30 22 32 10 22 18 30 10 10 10 10 18 22 22 10 8 18 10 6 6 14 8 6 SE E NE N_ NW W SW S (Shade) 8 In. Brick or 12 In. Hollow Tile ob 12 In. Cindeb Block NE E SE S SW w NW N (Shade) !2 4 2 6 4 2 2 8 6 4 2 10 6 14 46 24 2 8 4 2 16 18 14 4 8 10 10 2 14 18 15 1C 8 10 12 e 1C 14 ie le e 8 12 1C 1C 8 14 10 12 1C 1C IS 10 14 12 15 1C K 1C 1( 10 12 12 1C 1(> 1C } SE E NE N , 8 8 2 0 4 4 2 0 6 6 2 0 4 4 2 0 6 6 2 0 4 6 2 0 8 8 4 ( 4K CK 2l <: c 12 e 14 4l 5{ 8 2C IS 24 1C 2( 1 l 8 2C l 24 1 24 1 5 c 1C l8 1C u 18 ( 11 ) NW W SW J % S (Shade) 12 In. Brick NE E SE S SW w NW ' N (Shade) 8 12 10 8 68 8 12 6 10 68 68 8 12 6 10 66 4 8 6 4 8 10 10 6 4 10 6 12 6 10 46 4 12 6 12 6 10 6 10 8 14 10 14 10 14 8 14 6 12 8 14 10 14 10 12 4 8 4 10 6 12 8 12 6 SE 8E * 8 NE 8- N _ 10 12 8 4 6 10 8 12 68 42 6 10 8 12 68 22 6 8 4 2 10 10 8 2 6 10 6 10 48 22 6 10 6 10 48 22 8 10 6 10 48 22 8 12 6 12 6 10 24 8 14 10 8 16 10 6 10 6 466 NW W SW J , S (Shade) ^ NE E SE S SW w NW N (Shade) 8 In. Concbbte ob Stone ob 6 In. ob 8 In. Concrete Block 4 6 6 2 24 4 14 26 12 0 8 4 1 16 24 16 4 8 12 10 1 14 8 10 6 12 8 12 10 10 8 8 24 18 12 12 18 18 10 12 14 14 10 12 14 12 10 10 12 12 10 10 10 10 12 6| 16 12 18 12 14 12| 10 8 8 6 8 8 6 9 6 4 0 2 4 2 0 4 6 4 0 2 4 0 0 6 6 4 0 2 4 2 0 8 4 14 10 22 16 24 16 22 16 10 8 & 4 2 6 12 46 24 8 20 14 28 18 26 18 14 10 6 12 10 20 14 22 16 8 c 466886644 --- SE E N NE ___ NW W SW J . S (Shade) Cooling Load 295 Table 10. _Total Equivalent Temperature Differentials for Calculating Heat Gain Through Sunlit and Shaded Walls--Concluded. Sun Time Nobth Latitude Wall Facing NE E SE S SW W NW N (Shade) A.M. P.M. Exterior color of Wall--D = dark, L = light D L D L D L P L D L D L D L d[l|d|l South Latitude Wall Facing 12 In. Concrete or Stone 14 18 14 8 10 8 2 14 18 16 10 8 12 10 6 10 16 16 14 8 10 10 10 10 8 12 10 14 10 16 12 12 14 12 14 10 10 10 10 10 14 12 10 8 10 10 8 SE E NE N . 6 10 48 8 10 6 10 6 12 8 18 14 20 14 18 12 8 16 W 24 14 22 14 4 6 4 8 6 10 8 18 12 20 14 6I0 2 2 4 4 6 6 8 8 6 NW W SW S(Shade) NOTES FOR TABLE 10 [Total heat-transmission from solar Explanation; Irsdiation and temperature difference ibetween outside and room air, Btu [per (hr) (sq ft wall area) ,j NOTES: [Equivalent temperature 1 differential from above I table [Heat transmission [coefficient for wall,! |Btu per (hr) (sqj ft) (F deg) j 1. SO URCB. Same as Table 9. A north wall has been assumed to be a wall in the shade; this is practi cally true. Dark colors on exterior surface of walls have been assumed to absorb 90 percent of solar radiation and reflect 10 percent; White colors absorb 50 percent and reflect 50 percent. This includes sotn allowance for dust and dirt since clean, fresh white paint normally absorbs only 40 percent of solar radiation. 2. APPLICATION. These values may be used for all normal air conditioning estimates, usually with out corrections, when the load is calculated for the hottest weather. Correction for latitude (Note 3) is neces sary only where extreme accuracy is required. There may be johs where the indoor room temperature is considerably above or below 80 F, or where the outdoor design temperature is considerably above 95 F, in which case it may be desirable to make correction to the temperature differentials shown. The solar intensity onall walls other than east and west varies considerably with time of year. , 3. CORRECTIONS. Outdoor minus room temperature. If the outdoor maximum design temperature &rinus room temperatureis different from the base of 15 deg, correct as follows: When the difference is greater (or less) than 15 deg, add the excess to (or subtract the deficiency from) the above differentials. Outdoor daily range temperature. If the daily range of temperature is less than 20 deg, add 1 deg to every 2 deg lower daily range; if the daily range is greater than 20 deg, subtract 1 deg for every 2 deg higher daily f&nge. For example, the daily range in Miami, Florida is 12 deg, or 8 deg less than 20 deg; therefore, the cor rection is +4 deg. . . Color of exterior surface of wall. Use temperature differentials for light walls only where the permanence of the light wall is established by experience. For cream colors use the values for light walls. For medium colors interpolate half-way between the dark and light values. Medium colors are medium blue, medium Breen, bright red, light brown, unpainted wood, natural color concrete, etc. Dark blue, red, brown, green, etc., are considered dark colors, ' v Porlatitudes other than t0 deg north; and in other months. These table values will be approximately correct [or the east or west wall in any latitude (0 deg to 50 deg North or South) during the hottest weather. In the lower latitudes when the maximum solar altitude is approximately 80 deg to 90 deg (the maximum occurs at &0Q) the temperature differential for either a south or north wall will be approximately the same as a north, or shade wall. The temperature differential (fx) for any wall facing, and for any latitude for any month may e approximated as follows: !* = !, + _ 1--0. ,___ _ ` u. mcicuiuu ivr tuesauie wan in snaaeior desired time of day; obtained from Table 11 maximum solar radiation intensity transmitted through glass, Btu per (hr) (sq ft) for particular wall facing, in July, 40 deg north latitude (note: this is maximum value irrespective of time). It = same as h except use the maximum value for wall facing, for month, and latitude desired for t%. . * temperature differential for particular wall facing, for the desired time of day from above table. (Note that this makes adjustment only for solar radiation, and that there may be additional correction for outdoor temperature.) 4. FOR INSULATED WALLS use Bame temperature differentials as used for uninsulated walls. 296 Table 11. CHAPTER 13 1956 Guide Summed Coefficients of Heat Tbanemission V of Flat Hoofs Covbkep With Built-Up Hoofing* Biu per (hour) {square foot) (F deg difference between the air on the two sides) 1 Insulation oi? Top op Deck * (Covered With Built-Up Roofing) Furred Ceiling with Air Space, Metal lath and Plaster i_____________________________________________. , , _________ * The summer coefficients are considered temporary* and have been calculated with an outdoor wind 1.6l5poevcatittlyyueoo.ff 88Imnznpaphlhl..o-tfrFtohoerrsbseuurwxmoioumfuseuaar.a44nnpi.lnsviydssfeiiddereeltassruoutroerfffmaahccpaeeosccrbaooenlnjedd,nuuccattsaasnnuccmeeeoo-d-ff--1}11--.i.-22n--.hh-taahssicbbkee,eetnnheuussrmeeddaiilnncssotteenaaddduocotifivtmhiteey regular *--* l1*.3*3** vPeitlocchita; nd slag have bees assumed as an additional thi`ck*ness o*f 4* -in-. --w*h**`ic-lh haaos tbweenn assigned thermal con d^ ucbti8v7i4type=rc1e.0n.t gIynpsbuomth, c1a2s4epsetrhceernmt awlocoodnfdibuecrt.iviTtyhricekfenresstsoinondeicvantce&dtihnidckundeesss.4 in. gypsum board. This i's a6pNouormedinraolothf.ickness of wood is specified, but actualthickness was used in calculations. . 4 If corkbo&rd insulation is used, the coefficient U may be decreased 10 percent. ` A method of determining heat flow rates, when structure is not given in Tables 9 or 10,is illustrated in Example 7. Example 7: A 4 in. stone concrete roof covered with sn average depth of 4 in. cin der concrete (k = 4.9) on which is placed a f in. thick felt roof with $ in. pitch and slag surface, is exposed to the sun. The location is the central part of the United States. Cooling' Load 297 Design temperatures are: outdoor 95 F; daily range 20 deg; indoor temperature 80 F. Find the heat flow rate at 2:00 p.m. for a day in July. .. Solution: For the purpose of selecting the equivalent temperature differential, this construction is assumed to be equal approximately to an uninsulated 6 in. concrete roof, for which the equivalent temperature is found to be 38 deg in the 2:00 p.m. column of Table 9. Calculate the overall heat transmission coefficient V (see Equa tion 3 of Chapter 9) of the roof as follows: V =------------------------------------------------------ = 0.33. J_ 1 A 0375 0J50 jl , 1.2 + 12 + 4.9 + 1.33 + 1.00 + 4.0 The heat flow rate is then 38 X 0.33 equals 12.5 Btu per (hr) (sq ft). SUN y[SKY SURROUNDING^/ REFLECTED JRANSUITTEP 1 radiation (RAVE LENGTHS UNCHANGED) TRANSMITTED OUTDOOR RADIATION (WAVE LENGTHS UNCHANGED INCIDENT INDOOR RADIATION OUTDOOR CONVECTION THERMAL CAPACITANCE or CLASS INDOOR CONVECTION V<u * > ti HTTgP OUTDOOR RAOUTION firrCRENT DISTRIBUTION or ENERGY VS. WAVE LENGTH THEN TRANSMITTER EMITTED INDOOR RADIATION (DIFFERENT DISTRIBUTION * 1 OF ENERGY VS.WAVE LENGTH THEN TRANSMITTED) -it1--a1--yf- OUTDOOR AIR TEMPERATURE * tg, a OUTDOOR CLASS - SURFACE TEMPERATURE tl INDOOR AIR TEMPERATURE tgt-- INDOOR. GLASS- SURFACE TEMPERATURE . Fia. 2. Instantaneous Heat-Balance Conditions on a Glass Section TABLES FOR CALCULATING SOLAR HEAT GAIN THROUGH GLASS AREAS Basic Principles . In order to set forth the principles involved in calculating heat flow through glass areas, the general instantaneous heat-balance relation will be presented. It will be shown schematically in Fig. 2. The net heat gain for the indoor space is the result of several contributing phenomena. Some observations concerning the behavior of glass with respect to radiant energy will lead to a better understanding of the heat-balance relation. To various degrees glass transmits radiation having wave lengths between 0.29 and 4.75 microns. Of the portion not transmitted, part is absorbed, and the remainder is reflected. Outside these limits glass is opaque, absorbing approximately 94 percent and reflecting 6 percent. Only a negligible amount of radiant energy from a surface at 450 F has a wave length shorter than 4.75 microns. It is therefore convenient to treat all forms of solar radiant energy separately from radiant energy from other 298 CHAPTER 13 1956 Guide sources, so long as the temperature of these sources is not over approxi mately 450 F. /. The complete heat-balance for a glass section can be expressed for a unit time interval as follows: Total heat flow, [through glass sectiioon _ ... , "I ("Heat flow by convective^ Transmitted, and radjative exchanges at (2a) isolar radiationJ indoor surface J The second term of the right side of Equation 2a can also be expressed by a heat balance equation as follows: . Heat flow by convective-] rAbsorbed-] ["Radiative exchanges be- and radiative exchanges -- solar tween outer surface of glass .at the indoor surface J Lradiation J Land outdoor surroundings Convective exchanges ~| THeat storage-] [between outer surface of I 1 within the I glass and outdoor air J Lglass sectionJ Equations 2a and 2b can be combined and expressed in symbolic terms by Equation 2c. Tabular values of the two bracketed terms of Equation 2a are presented later in this section for various types of glass for Specific design conditions. (9/A) = [td/d + Td/dl + [oTd/d + a&I& + EuRt -- UoRfO -- /to (tgo -- to) -- S], . Btu per (hr) (sq ft) (2c) where - (q/A) = instantaneous rate of heat flow, Btu per (hour)(square foot). id, Td -- transmittance of glass for direct and diffuse solar radiation, respectively. Id, Id = incident direct and diffuse solar radiation, respectively, Btu per (hour) (square foot). od, ad = absorptance of glass for direct and diffuse solar radiation, respectively. eeo R, = -- elomwistseimviptyeroaftugrlaesrsaadtiatenmt epneerragtyurfeal1lei<n>' g on glass from outdoor surround ings, Btu per (hour) (square foot). Rgo = low temperature radiant energy emitted by a surface with emissivity equal to 1.0 at temperature <e- . /eo = outdoor convective conductance, Btu per (hour) (square foot) (Fahren heit degree). <eo = temperature of outdoor surface of glass, Fahrenheit degrees. ta = temperature of outdoor air, Fahrenheit degrees. S = rate at which glass stores energy, Btu per (hour)(square foot). Transmissivity and absorptivity vary with both wave length of the incident radiation and incident angle. Values of t and a for a single sheet of the average ordinary drawn window glass are given in Table 12 for a standard distribution of solar energy.4 Values for two air-spaced sheets are also given. Normal incidence transmittance values for some com monly-used types and combinations are given in Table 15. Some varia tion in these values can be expected in practice due to variations in manufacture and in solar energy distribution. However, a change in transmissivity causes an approximately equal and opposite change in absorptivity. Hence, the total heat flow is not greatly altered. Trans- . mittance data for other types of glass and various patterns of 8-in. glass block are given in A.S.H.A.E. research papers.19-20- 21- 2225 As stated earlier in this chapter, present data as to the value of & are inadequate, so for the present it is suggested that /,,,, be increased to include radiation, and the term e^Jt. -- be disregarded. It is not sal Cooling Load 299 practicable to give values of S in this chapter. However, for ordinary glass, the value of S is small. Fig. 3 is a graphical solution, for single glass, of Equation 2b. Only absorbed solar radiation is considered, although low temperature radiation exchange and heat storage can be added algebraically to ajt if such data are available. The small thermal resistance of the glass has been neglected. The heat flow rates are for a 75 F indoor temperature, an indoor surface conductance for convection /oi as given by Equation 3, and an equivalent surface conductance for radiation f,, as given by Equation 4. Indoor surfaces seen by the glass are assumed to radiate as a black body at room air temperature. /i = 0.27. (,i - ,) (3) where . t,i = temperature of indoor surface of glass, Fahrenheit. ti = temperature of indoor air, Fahrenheit. A more complete treatment of the problem is given in an A.S.HA..E. research paper.22 Example. 8: Find the total heat gain at 10 a.m. sun time for a single unshaded sheet of common window glass in a wall facing 18 deg east of south on August 1 at 50 deg north latitude. The indoor temperature is 75 F, the outdoor temperature is 83 F. Use clear atmosphere radiation values and = 4.0. Solution: From Example 2, K is 0.S57; hence, the angle of incidence, 8, iB 56 deg 9 min. From Example 4, Id = 152.0, Id = 26.6. By interpolation in Table 12, td is found to be 0.81, aD is 0.06; rd and as are 0.79 and 0.06, respectively. The heat gain due to transmitted solar radiation is lq/A), = 152.0 X 0.81 + 26.6 X 0.79 = 144.1 Btu per (hr)(sq ft). The heat gain by convection and radiation from the indoor surface is found from Fig. 3: from which to + loo gg + 0.06 (152.0 + 26.6) 85.7 F (?/A),, = 11.5 Btu per (hr)(sq ft). From Equation 2a the total heat flow is ' (g/A) = 144.1 + 11.5 = 155.6 Btu per (hr)(sq ft). Design Tables for Flat Glass Tables 13 and 14 give design values of instantaneous rates of heat gain for single unshaded common window glass for a solar declination of 18 deg. This corresponds to a nominal August 1 day. The tables are based upon solar intensity values for a clear atmosphere as given in Table 4. Table 13 represents the first bracketed term of Equation 2a; therefore, the values are dependent only upon values of I and t. Table 14 is the second term of Equation 2a, and is based upon a 80 F indoor temperature and a 300 CHAPTER 13 1956 Guide Table 12. Tbansmittances and Absorptances of Common Window Glass for Direct and Diffuse Solar Radiation , Angle op Incidence, 0, DEO 0 20 40 . 50 ' 60 ` 70 80 90 | Single Sheets TWO AIR-SPACED SHEETS D "d Outdoor Sheet Indoor Sheet For Direct Radiation 0.87 0.87 0.86 0.84 0.79 0.67 0.42 0.0 0:05 0.05 0.06 0.06 0.06 0.06 0.06 0.0 0.76 0.76 0.74 0.72 0.66 0.52 0.25 0.0 0.06 0.06 0.06 0.07 0.07 0.07 0.07 0.0 0.04 0.04 0.04 0.05 0.05 0.05 0.05 0.05 . 0.79 Fob Diffuse or Sky Solar Radiation j 0.06 | 0.6S j 0.07 0.05 dry-bulb temperature cycle, with a 95 F maximum as tabulated. The total heal gain is the sum of the Table 13 and Table 14 values. In preparing Table 14, convection and radiation heat exchange were combined, and a combined surface conductance of 4.0 used. Corrections to be applied for other design temperatures are given in Table 23 in a later section,. Effect of Deviation from Design Conditions. ` ' ' " .: ; Tables 13 and 14 may be used for other types of glass with good accuracy, by using the factors given in Table 15. Table 13 values are multiplied by the appropriate factor given in Table 15 to obtain heat gain due to trans mitted solar radiation. For glasses having a transmittance for normally incident radiation differing from the table values, factors may be found by linear interpolation. To obtain instantaneous rates of heat gain by con vection and radiation, two steps are required. First, Table 14 values are multiplied by the appropriate coefficient of X listed in Table 15. Second, Table 16 values are multiplied by the appropriate coefficient of Y listed \ - Fio. 3. Convection and Radiation Heat Flow fob Vertical Single Glass . .. Table 13. Instantaneous Rates of Heat Gain Due to Transmitted Direct and Diffuse or Sky Solar Radiation by A Single Sheet of Unshaded ' Common Window Glass For Clear Atmospheres and 18 Deg Declination, North (August 1) Note: For total instantaneous heat gain, add these values to the Table 14 values. 8 _,PhP Sun Time AM J i Instantaneous Heat Gain i n Bru per (hr) (sq it) -------- N ' NE E SE S SW W NW Horiz. EC 6 i.m. 6 p.m. zo 8 9 5 4 3 o 10 Q o 11 12 2 1 25 23 16 16 17 18 18 5 a .m. 7 p.m. B Zo .6 7 8 6 5 4. 3 26 16 14 a 9 3 15 Q . - 10 11 2 , 16 17 12 17 m h 5 a m. 7 p.m. - 20 66 25 K ZO 7 8 5 4 12 13 a9 Q 10 o M3 11 12 3 2 1 14 15 16 16 -- T PM- N 98 108 155 190 148 - 205 106 180 54 . 128 20 59 19 19 7 116 149 129 79 31 . 18 17 6 131 195 205 180 127 58 19 . 54 128 139 107 54 18 16 16 54 149 197 202 176 124 57 18 NW W 110 10 136 14 136 21 116 34 78 45 35 49 2, 67 124 156 162 148 113 64 - ; 0 7 11 18 42 69 90 98' 20 3. 81 8 136 12 171 32 183 72 174 110 143 136 96 144 sw S 10 13 15 17 19 35 0 6 10 12 14 16 23 84 3 7 10 12 14 16 42 96 SE 5 17 10 10 71 13 13 137 15 15 195 16 16 241 18 18 ` 267 19 19 276 00 1` 6 6 25 10 10 77 12 12 137 14 14 . 188 16 16 229 17 17 252 19 17 259 33 6 7 7 34 10 12 1120 80 129 14 14 173 15 15 206 16 16 227 18 16 234 E NE Horiz. --.... ... ihotantaneous hates of Heat Gain by Convection and Radiatic from a Single Sheet of Unshaded Common Window Glass For Clear Atmospheres and 18 Deg Declination, North (August 1) For 80 F Indoor Temperature Note: For total instantaneous heat gain, add these values to the Table 13 values. Son Time 5 6 a7 9 10 11 12 1 2 3 4 5 6 7 8 Dry- North Bulb Deo F Degrees N 74 74 -5 75 --5 77 --3 80 0 S3 87 90 30,40,50 93 94 3 8 12 15 16 95 17 94 16 93 15 91 13 87 8 85 83 Instantaneous Heat Gain in Btu peb (hr) (sq ft) NE --6 --4 --2 0 2 4 8 12 15 16 17 16 15 13 8 6 31 E SE ' --6 --6 --4 --5 --2 --3 10 43 66 10 11 12 13 15 16 16 .16 17 17 16 16 15 15 13 13 88 66 3! 3 S --6 --5 --5 --2 1 5 10 14 17 18 19 -17 15 13 8 6 3 SW W . NW --6 --6 --6 -- --6 --6 --5 --5 --5 --3 --3 --3 000 333 9 88 13 12 12 17 17 15 19 19 17 21 21 19 20 20 19 18 19 18 14 15 15 888 666 333 Hor. --6 --5 --3 0 3 8 13 16 20 21 21 19 17 13 8 6 3 302 CHAPTER 13 1956 Guide Table 15. Application Factobs to Apply to Tables 13, 14 and 16 to Obtain Instantaneous Rates op Heat Gain fob Vabious Types op Single Flat Glass and Combinations op Two Sheets op Flat Glass Spaced at 1 in. Glare* 81ngle Common Window Single Regular Plate ' Single Heat Absorbing Plate Double Common Window Double Regular Plate Heat Absorbing Plate Outdoors! Regular Plate Indoors / Normal Incidence Transmittance 0.87 0.77 0.41 0.76 0.60 0.35 Factor to Applt to Table 13 1.00 0.87 0.46" 0.85 0.68? 0.37k Factor to Applt to Table 14 low + 0.0(104 I.0(X) 4- 0.25(F) 1.0(X) + l.OO(K) 0.6(X) +0.MHY) 0.0(X) + 0.65m 0.6(X) + 0,75(r) Common window glass 1 in. thick. Plato glass l in. thick. *> For hotter precision, increase factora 10 percent when glass is in the shade. I values are Table 14 valum. d Y values are Table 18 values. Table 16. Heat Absobbed in Glass. Values of Y to be Used with Factobs in Table 15 and Table 17 in the Detebmination op Instantaneous Rates op Heat Gain Due to Convection and Radiation fob Vabious Types op Single Glass and Combinations op Two Sheets op Glass Spaced at J in. . For Clear Atmospheres and 18 Deg Declination, North (August 1) Sun Time 5 a.m. 6 7 8 9 10 11 1 p.m. 2 3% 4 5 6 7 40 Degrees North Latitude 5 a.m. 6 7 10 11 12 1 p.m. 30b Degrees North Latitude Values of Y in Btu per (hr) (sq ft)* S SW W NW 010 16 18 9 24 30 20 22 33 25 16 30 29 0 1 2 2 8 0 1 2 2 3 0 1 2 2 3 00 13 2 11 2 21 3 32 5 3 3 3 3 25 12 3 3 3 27 21 15 3 3 14 18 19 19 16 3 3 12 22 27 3 3 3 10 24 3 37 3 42 3 45 3 44 4 41 3 3 2 1 0 3 3 2 1 0 3 10 30 31 15 35 3 2 4 29 36 23 26 2 23 34 27 17 1 14 24 21 02 33 6 1 SW Sun Time Latitude SE SW 0 0 5 a.m. 7 16 18 2 7 22 2 24 3 20 13 1 22 2 28 3 30 13 22 16 6 3 3 3 10 3 11 4 12 14 1 p.m. 21 508 Degrees North Latitude 31 27 20 20 25 27 25 22 5 17 26 3 3 2 21 1 11 00 16 33 7 31 2 26 1 17 07 * Values of Y for 8 and 9 pm. are sero. b For N, NE, E, W, NW and horizontal use 40 deg North Latitude values. Cooling Load 303: in Table 15, and added to the first value. All convection and radiation gain values for double glass were computed for a J-in. air space. No great error is involved in cooling load estimates if these are used for double glass with other air spaces. Example 9: Find the total instaneous heat gain through a single sheet of regular plate glass in a southwest wall at 2 p.m. sun time and 40 deg north latitude on August 1. The maximum dry-bulb temperature for design is 98 F; the atmosphere is clear. The indoor temperature is 80 F. Solution: From Table 13 the heat gain due to transmitted radiation is 148 Btu per (hr) (sq ft) for common window glass; from Table 15, the factor for regular plate glass is 0.87. The coefficient of X in Table 15 is 1.0, while X is found from Table 14 for common window glass for the same hour, orientation and latitude. The co efficient of Y in Table 15 is 0.25, while the Y value is found from Table 16 for a south west wall at 2:00 p.m. and 40 deg north latitude. The correction for design dry-bulb . temperature is found from Table 23 to be 1.0 Btu per (hr) (sq ft) per degree difference from 95 F design temperature. The total instantaneous heat gain is, from Equa tion 2a, q = 0.87 X 148 + 1.0 X 19 + 0.25 X 27 + 1.0 (98 - 95) = 157.5 Btu per (hr) (sq ft). Design Tables for Rolled Figured Glass Tables 17 and 18 give design values of instantaneous rates of heat gain for a number of common patterns of single vertical sheets of rolled figured glass. The tables are for a solar declination of 18 deg, which corresponds to a nominal August 1 day, and are based upon the solar intensity values for a clear atmosphere as given in Table 4. The values are given in terms of corrections to apply to Tables 13 and 14. The heat gain due to transmitted solar radiation is found by multiplying the Table 13 values by the approximate percentages given in Table 18. To obtain instan taneous rates of heat gain by convection and radiation, Table 16 values are multiplied by the appropriate value of Y from Table 17 and then added to the corresponding Table 14 values: The total instantaneous heat gain is the sum of the gain due to transmitted solar radiation and the gain by convection and radiation. The values given in Tables 17 and 18 are based upon an A.S.H.A.E. research paper28 to which the reader is directed for additional data. The values in Tables 17 and 18 may be used with fair precision for other pat terns of similar transmittance and surface characteristics., For example, the data for hammered glass may be used for glass having shallow, closelyspaced ribs or for glass having small, closely-spaced circular indentations. Because some patterns have distinct orientation properties, no attempt has been made to give values for non-vertical glass. Design Tables for Glass Block Walls Tables 20 and 21 give design values of instantaneous rates of heat gain for sunlit walls of Type I pattern 8-in. hollow glass block for a solar de clination of 18 deg (see Table 19 for description of block patterns). These tables are based upon the solar intensity values for a clear atmosphere ' as given in Table 4. For solar energy transmittance data the reader is referred to reference 21. Table 20 presents values of transmitted direct and diffuse solar radiation, while Table 21 gives values of instantaneous rates of heat gain by convection and radiation from the wall. The latter values are for an indoor temperature of 80 F and a 95 F maximum dry-bulb temperature, as indicated in the table, and are based upon experimentally- I ! II i| r 'I: .. 304 CHAPTER 13 1956 Guide Table 17. Application Factors to Apply to Tables 14 and 16 to Obtain In stantaneous Rates op Heat Gain fob Vebtical Single Sheets . op Rolled Figured Glass Having Normal Incidence Transmittances and Listed Thicknesses ' (Smooth Side Indoors, Figured Side Outdoors) ` -- ` m.u. ,o FAmI Glass Pattern Normal. Incidence ' Transmittance Thickness, Inches Factob to Applt to Table 14 Hammered . Hammered, etched both sides Deep ribs on J in. centers H"amm-e-r-eJd1 hea*t-avb^swoKrbininr,g **/! 0.76 0.67 0.77 approx. 0.21 0.14 w Vis 7/ii H LOOT*+ 0.5000^' LOOT + 0.65(Y)d 1.0(X) +0.5000.' LOOT +1.15(50' l.O(X) +1.40(50 a X values are Table 14 values b y values are Table 16 values 0 Use 0.40((1T0) (for east anda west glass d Use 0.601 V) lor east and west glass Use 0.35(50 for east and west glass 1 U__s_s_0__.9_5.(_5,,0 (or south glass Table 18.' Instantaneous Rates of Heat Gain Due to Transmitted Direct and Diffuse Solab Radiation by Unshaded Rolled Figured Glass Multiply the Table 13 Values by These Percentage Factors Far Clear Atmospheres and 18 Degrees Declination, North (August 1) For SO, 40, and SO Degrees North Latitude Note: To obtain total instantaneous heat gain add adjusted Table IS values to adjusted Table 14 values ' PlTME Sun Time AM 4 "* 7 8 9 10 11 12 7 p.m. 6 5 4 3 2 7 p.m. 6 75 84 93 10 2 11' 12 N, NW w, sw NE E . SE S 80 86 70 80 80 85 85 75 80 80 75 85 85 80 80 80 75 60 80 80 60 65 75 u 65 7080 60 654 80 80 80 60 65* Ribs on J In. Centers 60 60 60 60 60 85 25 85 30 85 40 80 50 70 55 60 60 40 55 35 40 60 60 35 NW W sw Hammered and Etched 20 25 20 20 25 20 20 25 20 20 20 20 20 20 20 20 20 20 25 20 20 25 25 20 wNW SW Sun Time AM 4 5 a.m. 6 7 9 10 11 12 7 p.m. 6 5 4 3 2 1 t PM-> Hammered and Etched Heat Absorbing N, NW w, SW 20 . 20 20 20 20 20 20 N, NE E, SE NE E 15 15 15 15 10 15 10 15 10 10 15 10 20 10 20 20 NW W SE 10 10 10 10 10 10 10 10 sw 4 Decrease values 10 percent for 30 deg latitude; increase IS percent for SO deg latitude Increase values 30 percent for SO deg latitude Cooling Load Table 19. Description op Glass Block Patterns A Outdoor surface D-Indoor surface 305 E-Covify partition Elevation Section of Hollow Glass Block to Indicate Location of Surface Patterns Type I --Smooth Face Type IV--Light Diffusing A, D: Smooth A, D: Close pitch deep horizontal B: Wide vertical ribs or flutes corrugations C: E: Wide horizontal ribs or flutes None B, C: Vertical light diffusing prisms E: None Type II --Semi-Light Diffusing Type IVA--Light Diffusing A, D Narrow vertical ribs or flutes Same as IV except corruga B, C Etched or stippled ' tions vertical E, None Type V --Light Directing Type III--Light Diffusing A, D: Narrow vertical ribs or flutes B, C: Etched or "stippled E: Glass fiber screen A, D: B, C: E: Close pitch deep vertical cor rugations Horizontal light directing prisms None Table 20. Instantaneous Rate op Heat Gain Due to Transmitted Direct and Diffuse Solar Radiation by Unshaded Walls op 8-in. Hollow Glass Block op Type I Pattern ' For Clear Atmospheres and 18 Deg Declination, North (August 1) Note: For total instantaneous heat gain add these values to Table SI values BoD $ U- Sun Time AM-> 4 Instantaneous Heat Gain in Btu per (hb) (sq ft) N NE E SE S SW W NW a 6 a.m. 6 p.m. 4 45 55 ' 12 2 5 59 94 29 4 Z 5 42 94 38 5 o 5 25 59 34 6 5 10 2. 6 ` 12 27 24 9 12 6 8 12 13 10 6 6 78 9 & - o 5 a.m. 6 ' 7 p.m. 6 5 4 Z8 4 5 a .9 Q 10 11 12 3 2 1 5 6 6 6 EC 5 a.m. 7 p.m. 4 K 6. 6 . 5 O7 5 4 4 ftuO 9 10 Q 11 12 3 2 1 5 5 6 6 33 50 67 54 98 34 90 18 59 8 29 6 13 66 28 27 53 77 44 101 26 86 12 57 6 29 6 14 66 00 17 2 36 4 47 5 47 ' 10 35 15 22 18 . 13 . 17 4j 22 3 44 4 57 7 60 .16 54 25 34 32 20 34 `t PM-y N NW W SW S 2 3 4 5 6 7 8 0 2 4 4 5 5 7 13 1 2' 4 4 5 6 10 20 3 4 5 6 7 2 4 5 6 6 6 2 4 5 5 6 6 SE E 5 6 6 4 5 6 6 6 5 5 6 6 NE 306 CHAPTER 13 1956 Guide 21.Table Instantaneous Rates of Heat Gain by Convection and Radiation from Unshaded Walls of 8-in. Hollow Glass Block of. Patterns Type 1, II, III, IV, 1VA and V* ' For Clear Atmospheres and 18 Deg Declination, North (August 1) For 80 F Indoor Temperature Note: For total instantaneous heal gain add these values to values in Table 18, or Table 80 adjusted by Table 88 factors. Sun Time Bulb Fahr. 6 7 8 9 10 11 12 .. 1 p.m. 2 3 4 5 6 7 *8 9 74 74 75 77 80 83 87 90 93 94 95 94 .93 91 87 85 83 40 Decrees North Latitude Instantaneous Heat Gain in Btu per (hr) (sq ft) N NE E SE S ' SW W NW --3 --3 --3 --3 --3 --3 --3 --3 0 3 4* 3 --2 --2 --2 --2 1 15 17* 13 --1 --1 --1 --1 0 21 .26* 21 1 0 0 0 0 20 33 27 5 1 2 1 2 12 . 36 32 12 3 3 3 4 6 29 32 19 5 6 5 8 8 - 16 26 23 9 8 7 8 10 14 14 26 25 12 9 9 10 15 11 . 25 37 28 11 11 11 16 11 21 44 41 17 11 11 15 11 16 45 44 30 11 10 13 10 13 43 42* 35 13 9 11 9 11 35 35* 29 11 7 8 7 8 19 21* 15 7 4 4 4 4 7 74 4 3 2 3 2 3 43 Sun Time DryBulb 74 6 74 7 75 8 77 9 80 . 10 83 11 87 12 90 93 2 94 3 95 4 94 5 93 6 91 7 87 8 . 85 9 83 Latitude 30b Degrees North SE S --3 --3 1 --2 11 --1 20 0 26 1 29 4 26 8 18 12 10 15 11 16 12 14 12 13 U 11 10 9 66 44 33 SW --3 --2 --1 0 2 4 5 7 16 30 39 43 41 32 15 16 3 Latitude 50b Degrees North Latitude SE S SW --3 --3 --3 5 --2 --2 13 --1 --1 21 0 0 27 6 1 32 15 2 35 22. 4 33 28 17 23 31 31 12 32 39 11 28 43 11 20 44 10 12 43 9 10 36 7 7 23 4 4 10 3 33 a Eor types III, IV, IVA and V patterns and 30, 40 and 50 deg latitudes, multiply east wall values for 6 7 and 8 a.m. by 1.40, and west wall values for 5, 6 and 7 p.m. by 1.25. k For N, NE, E, W and NW use 40 deg North Latitude values. " determined values of solar energy absorption and temperature difference between the two faces. Because the exact dependence of the latter on weather conditions has not been determined, the values of convection and radiation gain cannot be regarded as exact for the assumed design con ditions. Indoor and outdoor convection and radiation heat transfer data are the same as those used for common window glass. Table 23 gives cor rections to be applied for other design temperatures. To obtain transmitted direct and diffuse solar radiation for other types of 8-in. block, the Table 20 values are multiplied by the approximate per centages given in Table 22. Note that corrections are the same for all latitudes, and that they vary only on the surfaces exposed to the direct sun. The convection and radiation gain values for all blocks are so nearly U\J i Table ,22. DInstantaneous Rates of Heat Gain ub to Transmitted . Direct and Diffuse Solar Radiation by Unshaded Walls of 8-in Hollow Glass Block of Types II, III, IV, IVA and V Patterns Multiply the Table 80 Values for Type I by These Percentage Factors For Clear Atmospheres and 18 Deg Declination, North (August J) For SO, 40, and SO Deg North Latitude Note: To obtain total instantaneous heat gain add adjusted Table 80 values to the Table 81 values. InstAUTAKfeovs Heat Gain Dunto Tbanshittxd Solaii Radiation as a Pebcentaoe or Ttpe i Pattejut Sun Time | Tna IIR.---- * Typu III Pattbbn AM -- 1 5 a.m. 7 8 10 11 12 ------------ _ 7 PJn. S 4 1 T 1 pi-* N, NW, w.sw NE E BE S 60 60 60 60 60 60 N, NE. E, SE 35 35 35 35 35 40 50 65 80 90 70 105 60 80 60 60 NW W 30 30 35 50 90 105 110 85 60 60 60 60 60 00* 105* 115* SW S Designation of Block Type II--Semi-Light Diffusing III--Light Diffusing IV--Light Diffusing IVA--Light Diffusing V--Light Directing Reduce, by 30% for 30 deg N lAt- itudeonly. ^ Table 23. Approximate Corrections to Tables 14 and 21 fob Deviations from Indoor and Outdoor Desion Temperatures For each degree the design room temperature exceeds 80 F, subtract correction. For ----- - * each degree the design outdoor dry.bulb temverntura aea.-.i. nc ip --n * - - throes Glass Type Jif,ured GlassD-- o&leFFFllaattGr,iRasoslIeadnd Glass Block Correction Btu per (hr) (sq ft) 1.0 0.5 308 CHAPTER 13 - 1956 Guide the same that a single table suffices. Note, however, that corrections must be made for certain hours for east and west facing, walls of some patterns. ................. Example 10: Find the total instantaneous heat gain through an east wall of 8-in. hollow glass block of Type V pattern at 8 a.m. and 50 deg north latitude. The design temperatures are 80 F indoors, and 95 F maximum outdoor dry-bulb, clear atmosphere. . Solution: The gain due to transmitted solar radiation is found from Table 20 for Type I pattern. The factor for Type V is found from Table 22. The convection and radiation gain is found from Table 21 (note the footnote). The total instantaneous heat gain is, from Equation 2a, q = 86 X 0.65 + 26 X 1.4 = 92.3 Btu per (hr)(sq ft). - Effect of Deviations from Design Conditions If the indoor temperature differs from 80 F, or the design outdoor drybulb temperature differs from 95 F, corrections can be made to the convec tion and radiation gain values for flat glass, rolled figured glass, and glass block according to the schedule in Table 23. The effect of the humid industrial type atmosphere is to cause a con siderable reduction in heat gain, if all factors except solar intensity remain the same. Reference 22 gives heat gain values for four orientations at 40 deg north latitude on August 1 for several types of flat glass and glass block, and solar intensities typical of humid industrial atmospheres. These data show that the following approximate reductions, based on total gain for the day, can be expected: 20 percent for all types of glass and glass block in east or west facing walls; 10 percent for south facing flat glass; 5 percent for south facing glass block walls. Shading of Glass Areas--Design Tables The effects and possibilities of shading should be carefully investigated whenever the heat gain from glass is a large portion of the cooling load. Vertical glass, which is not mounted in the plane of the building surface, is partially shaded by the setback. If a vertical window of height l and width w be set back from the plane of the building a distance s, the fraction of the total area of the window which receives direct solar radiation is: where _ , n tan p nr, tan p tan y Gt = 1--------------------n tan y + ------------------------- cos y cos y .. (5) r, = s/l, r, = s/to, p = solar altitude, and y is the wall solar azimuth (see Fig. 1) Values of and y for various latitudes and August 1 are given in Table 6. Special cases not covered by the tabulated data may be solved analy tically;24 however, the design" conditions chosen will yield a satisfactory approximation if used without correction for any time during the summer period. ' Example 11: Estimate the total instantaneous rate of heat gain for a west win dow 3 ft wide by 5 ft high, with a setback of 6 in., for August 1 and 40 deg north latitude at 3:00 pm (sun time). * Solution: From Table 13, the instaneous rate of heat gain, due to-transmitted direct and diffuse solar radiation, is 180 Btu per hr. From Table 6, P is 45.5 deg and Cooling Load 309 ~ 1 ~ -1 taf-- -- 0.167 tan 16 -f '167 taa tan 16 ;C0S 16 cos 16 = 1 - 0.106 - 0.048 + 0.005 = 0.851 In this instance the convection and radiation heat gain is due principally to temperature difference, so that shading has but a small effect on that portion of the absorbed radiation. Hence, the factor 0.851 is applied 24.Table Effect of Shading Upon Instantaneous Solar Heat Gain Through Single Thickness of Common Window Glass Type of Shading Canvas awning sides open > Canvas awning top and sides tight against building Inside roller shade, fully drawn* Inside roller shade, fully drawn* . Inside roller shade, fully drawn* ` Inside roller shade.balf.drawn* Inside roller shade, half drawn* . . Inside roller shade, half drawn* - Inside Venetian blind, slats set at 45 deg" ' Inside Venetian blind, slats set at 45 deg" - Inside Venetian blind, slats set at 45 deg Inside Venetian blind, slats set at 45 deg" Outside Venetian-blind, slats set at 45 dee" Outside Venetian blind, slats set at 45 deg"' * extended fully covering window as awning Outside Venetian blind, slats set at 45 deg, extended covering of window as awning Finish on Side Exposed to Sun -Fraction op Gain Through Unshaded Window Dark or medium Dark or medium White, cream Medium Dark White, cream Medium Dark '. : White, cream Diffuse reflecting | aluminum metalj 0.25 0.35 0.41* 0.62 0.81 0.71 0.81 0.91 0.56* 0.45* Medium Dark . White, cream White, cream White, cream 0.65* 0.75* 0.15* . 0.15 0.43 Outside shading screen solar altitude 10 deg Outside shading screen solar altitude 20 deg Outside shading screen solar altitude 30 deg Outside shading screen solar altitude, above 40 deg Darkd> * ` , * Holler shades are assumed to-be opaque. Some white ,i shades -- may transmit considerable bolor radia tion. For white translucent'shades fully drawn use 0.55 and for half drawn use 0.77. __ b Venetian blinds are-fully drawn and cover window. It is assumed that the occupant will adiust slats to prevent direct rays from passing between slats. If slats are fully closed (slats set at 60 deg.) use same factors as used for roller shade fully drawn. _ ^ Commercial shade with wide slats. The sun may shine on window through sides of shade. Estimate the exposed portion of glass as unshaded.. ' _ __ a Commercial shade, bronze. Metal slats 0.05 inches wide 17 per inch and set at 17 deg angle with hori zontal. At solar altitudes below 40 deg some direct solar rays are allowed to pass between slats,.and this amount becomes progressively greater at low solar altitudes. -- _. Commercial aluminum shade. Slats 0.057 inches wide, 17.5 per inch, set at 17 deg angle with horizontal. At solar altitudes below 40 deg some direct solar rays arealiowed to pass between slats and this amount be comes progressively greater at low solar altitude. From first paper in Reference 9. . only to the Table 13 value. Note also a small error results from the fact that the diffuse radiation is not shaded to the same extent as the direct radiation. The total instantaneous heat gain therefore is: q = 3 X 5 (0.851 X 180 + 26) = 2690 Btu per (hr)(sq ft) A window such as the one used in Example 11 would customarily be pro vided with an additional shading means for use particularly when directly sunlit. Conventional shading devices include awnings, shades, and screens f" various types. Much experimental and analytical work conducted at the A.S.H.A.E. 310 CHAPTER 13 1956 Guide Research Laboratory26 as well as earlier experimental work,24'28 and other research27 to determine the effectiveness of various types of window shades, have been used as the basis for the recommended ratios in column 3 of Table 24. A study, of absorptivity of the shade to solar radiation and heat transfer from the shade to the outdoors and indoors, was used to determine these ratios. ' There are a number of variables affecting these ratios such as color, fit, solar altitude, and angle of incidence of the solar radiation. These values, therefore, must be considered as approximate, only, and will have to be used with considerable judgment. An inside shade is effective to the ex tent of its reflectivity, since the portion of the solar radiation directly transmitted by the glass that is absorbed by the shade is transferred by convection to the room air, and by radiation to the solid room surfaces. Fig. 4. Origin of the Difference Between the Magnitudes of the Instan- taneous Heat Gain and Instantaneous Cooling Load The radiation absorbed by the interior furnishings and structure reaches the conditioning equipment after a considerable delay in INSTANTANEOUS HEAT GAINS VS. INSTANTANEOUS COOLING LOADS The difference between instantaneous heat gain and instantaneous cool ing load has been mentioned previously; its practical importance is suffi cient to warrant further consideration. Fig. 4 offers a simplified schematic illustration showing how the radiative part of the instantaneous heat gain is first absorbed by solid objects, and is not encountered by the conditioning equipment as a cooling load until some later time, when it finally appears in the air stream entering the equipment. While it is true that some lag also is inherent in convective heat transfer and the time required to change the air in the conditioned space, this is usually of the order of a few minutes to perhaps half an hour. Heat storage in the interior furnishings and structure increases according to the proportion of the instantaneous heat gain which is in the form of radiation, and also as the thermal capacitance of the objects and materials involved is increased. Constituents of the total instantaneous heat gain which have appreciable radiation components include those due to glass areas, exposed walls and roofs, lighting, appliances, and people. No comprehensive data are presently available for use in design load estimates to evaluate the interior load-lag effect, but several investigators"' i4. as. 29. so have made a study of the problem and have presented many useful data. Tables 9,10,13,14,18,20, and 21 are all based on instantane ous rates of heat transfer. Hence, practical judgment and experience offer the only basis of procedure. Until the needed data become available, it is recommended that the non-continuous load be averaged over two or three hours during the time of maximum load, when determining the total instantaneous cooling load where a large portion of the heat gain is radiant. This suggestion applies only to conditions near the time of maximum heat Cooling Load 311 gain, as the heat stored within the structure would necessarily appear in the cooling load eventually; but if. it appears at a time when the gain from outside is relatively low, the equipment will be able to maintain satisfactory conditions within the range of maximum capacity. LOAD FROM INTERIOR PARTITIONS, CEILINGS, AND FLOORS Whenever a conditioned space is adjacent to another space in which a different temperature prevails, the transfer of heat through the separating structural section must be considered. Calculations are made according to the relation: q = V,A,(tb -- <j) Btu per hour. (6) where U-, = coefficient of overall heat transfer between the adjacent and the condi tioned space, Btu per (hour) (square foot) (Fahrenheit degree). A> = area of separating section concerned, square feet. lb -- air temperature in adjacent space, Fahrenheit degrees. Ii = air temperature in conditioned space, Fahrenheit degrees. Magnitudes of U-, may be obtained from Chapter 9. The temperature tb may have'any value over a considerable range, according to conditions in the adjacent space. The temperature in a kitchen or boiler room may be as much as 15 to 50 deg above the outdoor air temperature. It is recom mended that actual temperatures be measured in adjoining spaces wherever practicable. Where nothing is known, except that the adjacent space is of conventional construction and contains no heat sources, it is recommended that the difference (lb -- U) be taken as the difference between the out door-air and conditioned-space design dry-bulb temperatures minus 5 deg. In some cases it may be that the air temperature in the adjacent space will correspond closely to the outdoor air temperature at all times. Undei these latter conditions, the heat gain through the partition will be periodic in nature, and the value of a shaded wall should be used from Table 10. For floors directly in contact with the ground, or over an underground basement that is neither ventilated nor warmed, the heat transfer may be neglected for cooling-load estimates. LOAD FROM OUTDOOR AIR, VENTILATION AND INFILTRATION Ventilation. Data for determining the necessary ventilation rate have been presented previously in this chapter. Ventilation required is pri marily dependent upon the number of occupants and upon the materials and apparatus within the space which may give off odors. For spaces having ceiling heights 10 ft or less, the total requirement should be checked against the volume, and in no case should the ventilation air rate be less than one air change per hour. In spaces having ceilings higher than 10 ft where the occupant load is low, a check calculation can be made against the volume of the space below an assumed 10-ft ceiling. Infiltration must never be counted upon to provide ventilation, because on still days there will be little or no infiltration. Infiltration. The principles of infiltration calculations have been dis cussed in Chapters 11 and 12, with emphasis on the heating season. For the cooling season, infiltration calculations are usually limited to doors and windows. To compute cooling-load infiltration for windows by the crack method, 312 CHAPTER 13 1956 Guide use the data of Table 2, Chapter 11, for a wind velocity of 10 mph. Note that for double-hung windows the length of crack is three times the width plus twice the height; while for metal-sash windows the crack length is the total perimeter of the movable or ventilating sections. In calculating window infiltration for an entire structure, it is not necessary to consider the total crack length on all sides of the building, for the wind would not act simultaneously on all sides at once. In no case, however, should less than half of the total crack length be figured. A knowledge of the pre vailing wind direction will aid judgment in this consideration. Cooling-load infiltration for doors32 may be obtained from Table 3, Chapter II. For conditions other than those covered, the notes appended to the table will provide a basis for estimates. The tabulated data may also be used as the basis of estimates for interior doors between an air-condi tioned and a non-air-conditioned space. Infiltration load must be included whenever the new air introduced through the system is not sufficient to maintain excess pressure within the enclosure to prevent the infiltration. Whenever economically feasible, it is desirable to introduce sufficient outdoor air through the air-conditioning equipment to maintain a constant outward escape of air, and thus eliminate the infiltration portion of the load. The pressure maintained must, of course, be sufficient to overcome wind pressure through cracks and door openings. When this condition prevails it is not necessary to include any infiltration load. When the quantity of new air introduced through the cooling equipment is not sufficient to build up the required pressure to offset infiltration, the entire infiltration load should be included in the cooling load calculations. Total Outside Air Load. Many cooling coil manufacturers publish tables giving psychrometric data based on the average conditions of the leaving air for various coil temperatures, air velocities, and entering dry-bulb and wet-bulb conditions. When these tables are used, it is necessary to cal culate the mixed air condition entering the coil, and determine from the tables what coil and air velocity will produce the desired leaving air con ditions as required for the space to be conditioned. When cooling coils are listed as 80 to 95 percent efficient, the manufacturer indicates that 20 to 5 percent of the air passes through the coil without being cooled. If data of this nature are used, the uncooled portion of the air must be added to the space load before determining the effective air quantity. See later section on Apparatus Dew Point. To determine the design cooling load caused by the introduction of out side air, the maximum rate of outside-air entry is first established. In some applications the use of special exhausters from the conditioned space may add to the outdoor-air requirements in determining the maximum rate. Once this design quantity is established, and with the design indoor and outdoor air states known, the cooling load may be computed. There are several methods in use; the more accurate of these require rather detailed calculations. Refer to Chapter 3, and also section on Apparatus Dew Point in this chapter. The following equations are considered to be of sufficient precision for use at usual design conditions, as their accuracy is within 1 percent. (0.00923 1 ------0 62~ = Q X 1.08 (<,, -- tCi, Btu per hour (7) Cooling Load 313 Latent Load g. = Q X 60 X 0.075 X 1076 (W,, - Wd = Q X 4810 (ITo -- KM, Btu per hour (8) Total Load where g, = q, + g. <9) Q rate of entry of outside air, cubic feet per minute. . outdoor dry-bulb temperature, Fahrenheit, indoor dry-bulb temperature, Fahrenheit, JPo outdoor humidity ratio, pounds moisture per pound of dry air. Wi indoor humidity ratio, pounds moisture per pound of dry air. 0.075 standard air density, pounds per cubic foot. 0.244 a constant approximating the specific heat of dry air corrected for mois ture Btu per (pound) (Fahrenheit degree). 1076 = a factor approximating the average Btu released in condensing one pound of water vapor from air. As explained later in the section on Apparatus Dew Point, some methods of load calculations break down the ventilation air into two parts; one por tion which does not contact the coil surfaces (t'.e. bypasses the coil) in passing through the coil and thus becomes a part of the room load; and a second portion, the remainder of the air which contacts the coil surfaces and is cooled down to the apparatus dew point. This detailed method ex plained in the literature by Ashley,81 is believed to be very easy and ac curate to use. Similar equations, therefore, Can be written; Space Sensible Ventilation Load, g.i = Q X 1.08(4 - ti) X 6 Space Latent Ventilation Load, g.i = Q X 484007,, - KM X 5 Remaining Sensible Ventilation Load, g.x = Q X 1.08ft, - *0(1 - 6) Remaining Latent Ventilation Load, g = X 4840(170 - T7t)(l - 6) g. = g.i + g.x + g.i + g.x where (10) (11) (12) (13) (14) 6 = fraction of air passing through coil which does not contact surfaces, coil by " pass factor. Standard air weight (0.075) lb per cu ft) is recommended for use in all calculations, as this is the basis for rating fans and its consistent use keeps all parts of the calculations in conformity. . HOW OUTDOOR AIR LOAD AFFECTS ROOM LOAD Actually, the outdoor air used for ventilation would pass through the conditioning equipment, and be cooled and dehumidified to a lower tem perature and humidity ratio than room conditions before entering the room ; hut for heat-balance purposes the cooling load chargeable to idle outdoor eir is that corresponding to the difference between the outdoor and indoor eir conditions. One important purpose of the cooling load estimate is to determine the 314 CHAPTER 13 1956 Guide conditions and quantity of air supplied to the space. All the various sen sible and latent heat loads within the space must be included. Infiltration must be included, in the space load since this air enters the doors and win dows, and its heat and moisture load must be offset by the introduction of cooler, dryer air to the space. However, since outdoor air is taken through the conditioning equipment and cooled, this portion does not be come a part of the space load, except a small portion which passes through the coil untreated. To determine the total load on the refrigeration ma chine, the remaining outdoor air load must be included in the grand total load. ' 25.Table Rates op Heat Gain fbom Occupants of Conditionep Spaces'- Degree op Activity Typical Application Total, Heat 1 j Total Heat Adults, . Male Btu/Hb Adjusted Btu/Hb Sensible Heat. Btu/He Latent Heat Btu/Hb . Seated at Rest.......................... ......... Seated, Very Light Work.............. Moderately Active Office Work.. Standing, Light Work; or' Walking Slowly.................................. Walking; Seated........................ Standing; Walking Slowly*.. Sedentary Work...................... Light Bench Work............. Moderate Dancing.. Walking 3 mph; Moderately Heavy WorkTBtoawwlilningffd ....................................... Heavy Work Theater-Matinee___ Theater-Evening-- Offices, Hotels, Offices, Hotels, Department Store, ' Retail Store Drug Store Factory........................ 390 390 450 475 550 550 490 800 900 1000 1500 ' 330 350 400 450 450 500 550 750 850 1000 1450 180 195 W5 200.. 200 200 220 220 245 300 465 150 155 205 250 250 300 700 985 * Note: Tabulated values are based on 80'F room, dry-bulb temperature. For 78 F room dry-bulb, the total heat remains the same, but the sensible heat values should be increased by approximately 10 percent, and the latent heat values decreased accordingly. - , k Adjusted total heat gain is based on normal percentage of men, women, and children for the application liafced, with the postulate that the gain from an adult female is 85 percent of that for an adult male, and that the gain from a child is 75 percent of that for an adult male. c Adjusted total heat value for sedentary work, restaurant, includes 60 Btu per hour for food per individual (30 Btu sensible and 30-Btu latent). ' d For bawling figure one person per alley actually bowling, and all others as sitting (400 Btu per hour) or standing (550 Btu per hour). ].' ' Example 12: For outdoor design conditions of 95 F dry-bulb and 75 F we^-bulb, and indoor design conditions of 80 F dry-bulb and 67 F wet-bulb, and for the supply of outdoor air at the rate of 1000 cfm and the exhaust of room air at the corresponding rate, calculate the total, sensible and latent heat gains. Solution: Substituting in Equation 7: q. = 1000 X 1.08 (95 - 80) = 16,200 Btu per hr. From psychrometric data Wo = 0.01413, Wi = 0.01122. Substituting in Equations 8 and 9: q. = 1000 X 4840 (0.01413 - 0.01122) = 14,100 Btu per hr. qt = q. + ?. = 30,300 Btu. HEAT SOURCES WITHIN THE CONDITIONED SPACE People. The rates at which heat and moisture are given off by human beings under different states of activity are given in Table 25. In many applications these sensible and latent heat gains become a large fraction of Cooling Load 315 the total load. Appreciable variations in heat-emission rates must be recognized according to the age and sex of the individual; state of activity, environmental influences, and duration of occupancy (since for short occupancy the extra heat and moisture brought in by people may be a significant factor). While Chapter 6 should be referred to for detailed information. Table 25 in this chapter summarizes practical data representing conditions com monly encountered. Lighting. In general, the instantaneous rate of heat gain from electric lighting*2 may be calculated from the following relation: {total light f use (special allow- wattage (factor * (ance factor 3.41, Btu per hr. (15) The total light wattage is obtained from the ratings of all fixtures installed, both for general illumination and for display use. . The use factor is the ratio of the wattage in use, for the conditions under which the load estimate is being made, to the total installed wattage. For commercial appli cations such as stores, the use factor would be unity. The special allowance factor is introduced to care for fluorescent fixtures, and for fixtures which are either ventilated or installed so that only part of their heat goes to the conditioned space. For fluorescent fixtures, the special allowance factor is recommended to be taken as 1.20 in order to allow for power consumed in the ballast. For ventilated fixtures, recessed fixtures, and the like, manufacturers' or other data** must be sought to establish the fraction of the total wattage which may be expected to enter the conditioned space. Power. When equipment of any sort is operated within the conditioned space by electric motors, the heat equivalent of this operation must be considered in the cooling load. The general equation for calculating this load is: /Horsepower Rating^ / Load = ( MotorX (.Factorj X ^ Bt" ^ ^ 6) It is assumed that both the motor and the driven equipment are within the conditioned space. If the motor is without the space, then do not divide by the motor efficiency in Equation 16. The load factor is merely the fraction of the rated load which is being delivered under the conditions of the cooling-load estimate. Molar efficiencies may be approximated as follows: about 50 to 60 percent at hp rating, increasing to 80 percent at 1 hp, and to 88 percent at 10 hp and above. Appliances. Care must be taken in a cooling-load estimate to take into account the heat gain from all appliances, electrical, gas, or steam. Table 26 presents recommended data.84 Note that the maintaining rate in Table 26 is the heat input required to maintain the appliance at the normal operating temperature even though it is not being used, i.e., no coffee is being made, no toast is being made, no food is being cooked in the fry kettle, etc. The maintaining rate is useful in setting up a lower limit to the heat gain to a room from the appliance when in operation. Experienced judgment must be used in the application of data given in Table 26. Consideration must be given to the heat contributed by appli ances which are in use at the time of peak load. The quantity of heat will depend upon whether products of combustion are vented to a flue, whether they escape into the space to be conditioned, or whether appliances are hooded allowing part of the heat to escape through a stack. There are bo generally accepted data available on the effects of venting and shielding CHAPTER 13 1956 Guide Cooling Load 319 heating appliances, but it is believed that when they are properly hooded with a positive fan exhaust system through the hood, 50 percent of the heat will be carried away and 50 percent dissipated in the space to be condi tioned, The same effectiveness of the hood should be figured for both latent arid sensible heat. ' LOAD FROM MOISTURE TRANSFER THROUGH PERMEABLE BUILDING MATERIALS The diffusion of moisture through all common building materials is a natural phenomenon which is always present to a greater or lesser degree. The permeability and permeance values for various building materials are given in Table 2 of Chapter 10, together with an explanation of mois ture transmission through these materials. In the usual comfort air-conditioning application, it is common prac tice to neglect moisture transfer through walls, for the actual rate is quite small and the corresponding latent-heat load is hardly significant. Socalled vapor barriers are frequently employed in modem construction for the purpose of keeping moisture transfer to a minimum, and reducing the deteriorating and insulation-destroying effects of moisture. Industrial jobs,, on the other hand, frequently call for a low moisture content to be maintained in a conditioned space. Here the matter of moisture transfer cannot be neglected; indeed, it is quite possible to have the latent-heat load accompanying this transfer be of greater magnitude than any other latent-heat load. The equation for computing this load is; (f) - & - (dTTM) >< *> <"> where M = permeance of the specimen in perms, or grains per (square foot) (hour) (inch of mercury vapor pressure difference). 7000 = grains per pound. The factor 1076 is defined in list of symbols at Equation 9. (Sensible cooling of the water vapor is included in the factor 1076 ) The only means of preventing moisture transfer is to use a vapor proof wall, or to apply a special lining, which is vapor proof. All openings in moisture proof construction must be equipped with special gaskets to pre vent entrance of moisture. When moisture transfer contributes an appreciable part of the latentheat load, it is recommended that estimates should be made intentionally liberal in order to avoid later difficulties with insufficient dehumidifying capacity. Storage spaces, for example, would require sufficient dehumidifying capacity to handle the moisture brought in with goods to be stored, m addition to moisture leaking in subsequently. . MISCELLANEOUS HEAT LOADS This designation is intended to cover the various small heat gains from exposed piping, ducts, work done by circulating fan, and unforeseen con tingencies. Where sufficient data are available, these various heat gains bmy be estimated individually. In the majority of cases, however, common Practice is to lump these factors together and combine them with a safety 320 CHAPTER 13 -1956 Guide factor according to the experience and judgment of the estimator. On this basis, a small safety factor is added to the calculated cooling load to com pensate for miscellaneous effects. No rules can be given/for this proce dure, as experience in air conditioning is indispensable for application of suitable safety factors. APPARATUS DEW POINT AND REQUIRED AIR QUANTITY THROUGH CONDITIONING EQUIPMENT In ordinary practice, with commercial apparatus, complete saturation of the air is seldom obtained. Four-row finned cooling coils contact ap proximately 80 percent of the air, whereas six-row finned coils contact approximately 95 percent of the air. In spray type dehumidifiers of good Fig. 5. Apparatus Dew-Point Shown on A.S.H.A.E. Psychkometric Chart design the air leaves the dehumidifier at I to 2 deg higher wet-bulb tem perature than the spray water leaving the dehumidifier, and the difference between the dry-bulb and wet-bulb temperatures leaving the dehumidifier may be as low as 1 deg. A spray type dehumidifier haying sufficient length of spray chamber and density of spray, together with proper ar rangement of nozzles, may approach saturation very closely. As explained in Chapter 3, and shown in Fig. 5, the slope of the line on the psychrometrie chart connecting the room condition with the apparatus dew point on the saturation line, detennines the ratio of sensible heat absorbing capacity to the moisture absorbing capacity of the supply air. Therefore the room condition can be maintained as long as the supply air temperature lies on this fine, but a greater volume of supply air must be used to satisfy the room loaa if the cooling coil does not contact 100 per cent of the air. For a given room load, the same apparatus dew point will be required whether the cooling appliance contacts all the air or only part of the air. From the point of view of satisfying the given cooling load require ments, the air passing through the apparatus without being cooled below the dew point temperature produces two effects: 1. The air quantity which must be passed through the dehumidifier must be in-. Cooling Load 321 creased. Thus, if 20 percent of the air passing is contacted, then (20 + 80) X 100 = 25 percent more air must be used than would be necessary if all of it were contacted. 2. Passing untreated air may change the room cooling load, which in turn maychange the enthalpy-humidity difference ratio (sometimes called the sensible heat factor). If return air only is passed through the dehumidifier or if room air only is bypassed, the room load will not change, but if some outside air is passed through, the room sensible heat gain and room latent heat gain will be changed due to the addition of untreated outside air, which changes the enthalpy-humidity difference ratio. ' When a load calculation is made, it ia necessary to know the percentage of air affected in the dehumidifier, and calculation must be made accordingly. If the ventilation air is drawn through the dehumidifier before it goes into the room, only that portion of the air not saturated must be included in the room load for the purpose of determining the apparatus dew point and supply air quantity. It should be noted when evaluating the load added by untreated outside air that the temperature difference between room air and outside air, and the moisture content difference between room air and outside air, should be used, rather than the difference between outside air and apparatus dew point, since the rise from the apparatus dew-point to room condition is charged against the dehumidifier as the cooling and dehumidifying load. The procedure for determining the required air quantity is based upon the thermodynamic principles of Chapter 3 and the use of the A.S.H.A.E. psychrometrie chart. Readers are advised to review these principles, paying particular attention to the illustrative examples. Calculation of the cooling load for a conditioned space is equivalent to making, for the space, a heat balance in which all heat, moisture, and infil tration are treated as directly entering the space. As explained in the section. Load from Outside Air, Ventilation, and Infiltration, the outside air load normally does not become a part of the space load, because heat and moisture are removed in the air conditioner before this air gets into the conditioned space. The desired conditions are maintained by considering a certain quantity of air to be withdrawn from the space, passed through the conditioning equipment, and returned to the space with such a tem perature and humidity ratio that its net effect will be to counterbalance or remove the given entering amounts of heat and water vapor. This quan tity of indoor air, which is considered to be circulated in this maimer, is called the required air quantity and its determination is normally part of every cooling-load estimate. The procedure is as follows: space. 2. Compute the quantity called the enthalpy-humidity difference ratio (also referred to as "heat-moisture ratio) of the room load, ^Use the equation where hi -- ft, _ (Space sensible load -f space latent load) Wt -- W. Space latent load/1076 ' K = enthalpy of moist air supplied to the space, Btu per pound of dry air. hi = enthalpy of moist air at room design conditions, Btu per pound of dry air-. IF, = humidity ratio of moist air supplied to the space, pounds of vapor per pound of dry air.) fFi = humidity ratio of moist air at room design conditions, pounds of vapor per pound of dry air. 322 CHAPTER 13 1956 Guide : Note that the ratio (space latent load/1076) is the equivalent of the required rate of water vapor removal in pounds per hour. If the rate of water removed is known, it may be used directly in.Equation 18. ' . 3. Draw a line through the reference point on the A.S.H.V.E. psychrometric chart and the value of (A,- -- h,)/(Wi -- W,) determined above. Draw a second line through the state point of the room air (design wet-bulb and dry-bulb temperatures) parallel to this line. This is the condition line for the process. 4. Read the.temperature where the condition line from step 3 intersects the satura tion line. This isealled the apparatus dew point. See Fig. 5. Note that instead of using this graphical method the left hand side of Equation 18 may be solved by trial and error by substituting values of A, and W, corresponding to assumed apparatus dew-point temperatures. 5.. Compute the required air quantity from the relation (Space sensible load) K Space \ _ /Apparatus \"1 1.08 dry-bulb/ \ dew-point /J k Coil \ bypass I factor / (19) The magnitude of Qn is substantially the quantity, cfm, of cooled and dehumidified air for which the distribution system must be designed. (The numerical factor 1.08 is derived from the product 1 cfm X 60 min X 0.244 X 1----0- `009-2-3- \] = 1.08, assuming an average supply air dew point of 55 F. Si.nce standard air0d.6e2ns/ity (0.075) includes the weight of the water vapor, it is desirable to reduce it to the basis of dry air by the last factor where 0.00923 = humidity ratio of air at 55 F dew point, and 0.62-= ratio of density of water vapor to dry air at same temperature and pressure. Refer to Chapter 36 for coil selection. . Note that the product [ (space dry-bulb) -- (apparatusdew point)] X (1 -- coil by. pass factor) is equal to the dry-bulb range through which the conditioned air is coo led Hence, in rare instances when the condition line of the process may not intersect the saturation line, any other convenient reference temperature on the condition line may be used instead, provided that the coil bypass factor is specified accordingly on the proper basis. - MINIMUM ENTERING AIR TEMPERATURE Due consideration must be given to the temperature of the air entering the conditioned space in order to prevent objectionable drafts. With ceil ing type diffusers or wall grilles with a high aspect ratio (see Chapter 31), many engineers consider 20 deg as the maximum difference for good design under average conditions. This difference can only be exceeded with ex tremely high ceiling outlets or wall grilles. Thus, if 80 F dry-bulb is to be maintained in a space with average ceiling height, the minimum delivered air temperature would be limited to about 60 F dry-bulb temperature. If the latent heat load is relatively high, it is often necessary to circulate more air with a higher delivered dry-bulb temperature in order to produce a thermodynamic balance. If the dry-bulb temperature of the air supplied to the space is known, the required air quantity can be calculated from the formula, Qro 1.08 (ti - O (20) or the supply temperature t, can be determined as follows, t- q` f. 1 1.08 X (21) Cooling Load 323 EXAMPLE--COOLING LOAD CALCULATION Example 13: A one-story office building Fig. 6 is located in an eastern state near 40 deg latitude. The adjoining buildings on the north and west are not conditioned, ana the air temperature within them is known to be substantially equal to the outdoor air temperature at any time of the day. South wall construction: 8 in. concrete block, 4 in. brick veneer, J in. plaster on walls. (Table 9, Chapter 9, No. 92B, U = 0.41.) East wall and outside north wall construction: 8 in. concrete block, painted white, i in. plaster on walls. (Table 8, Chapter 9, No. 82B, U = 0.52.) West wall and adjoining north party wall construction: 13 in. solid brick, no plaster: = + ! + i r' If = 0-263. Use U = 0.26. Roof construction: 2* in. flat roof deck of 2 in. gypsum fiber concrete on gypsum board surfaced with built-up roofing. (Table 11, U = 0.34 for summer.) Floor construction: 4 in. concrete on ground. Window: 3 ft x 5 ft, non-opening type, with medium colored Venetian blinds for windows on south wall. Approximately 4 in. reveal on all windows. Front doors: Two 2 ft-6 in. x 7 ft (glass panels). Side doors: Two 2 ft-6 in. x 7 ft (I glass panels). Rear doors: Two 2 ft-6 in. x 7 ft (wood panels). Outside design conditions: Maximum dry-bulb 95 F, wet-bulb 78 F; Wo = 0.0169 lbs vapor per lb dry air; h0 = 41.38 Btu per lb dry air. Indoor design conditions: Dry-bulb 80 F, wet-bulb 65 F; W, = 0.0098 lb vapor per lb dry air;Ai = 29.95 Btu per lb dry air. Occupancy: 85 office workersLights: 12,000 watts, fluorescent; 4000 watts tungsten. Fan motor: 7$ hp. . Assume that cooling coil has a bypass factor of 0.15, i.e., that 15 percent of the mr passeS'through the coil without contacting the coil surface. Conditioning equipment to be located in adjoining structure to north. Find: Total, sensible, and latent maximum cooling loads and required air quantity through conditioning equipment. 324 CHAPTER 13 ' 1956 Guide Solution: From Table 3, the" recommended ventilation rateis 15 cfm per person. Total necessary = 85 X 15 = 1275 cfm or 76,500 cu ft per hr. . As the room volume is 40,000 cu ft; the air changes per hour will be 76,500/40,000 = 1.91 which is more, than one air change. : . ,, j, .. Estimated Time oj Maximum Cooling Load: ' - '' - : " For this job, judgment indicates that the roof will make the greatest single con tribution to the cooling load. Hence, the time of Maximum.cooling load probably will be the time of maximum heat gain through the roof. , From Table 9 the maxi mum temperature differential for a 2 in. gypsum roof of medium'weight construction is 54 deg at 4:00 p.m., and 53 deg at 3:00 p.m." Examination of Table 13 (40 deg N Latitude) shows that solar heat gain through glass on the south wall is 18.Btu per (hr) (sq ft) at 4:00 p.m., and 42 Btu at 3:00 p.m. This indicates that the maximum cooling load occurs at approximately 3:00 p.m. Therefore make load calculations at 3:00 p.m. sun time. (This may be slightly different from 3:00 p.m. local time.) In some cases, there would be no clear-cut evidence of this nature,1 and consequently, it would be necessary to estimate the load for several successive times, and then to select the.maximum. .. . ., ..... ..... ., Ileal Gain Through Outer Wall and Roof Areas: . .-. . . / ....., .: Froih.Table 10 the temperature differential for the south wall (8 in: concrete block with 4 in. brick veneer) may be about the same as a 12 in. brick which is 6 deg at 3:00 p.m. for a dark colored wall. From the same table, the temperature differential for the east wall (8 in. concrete block with plaster) will be 11 deg at 3:00 p.m. for a light colored wall (interpolating between 2:00 and 4:00 p.m.). Likewise, the tem perature differential for the north exposed wall (8 in. concrete block plus plaster) will be 3 deg at 3:00 p.m. (by interpolation) for a light wall. The party wall of 13 in. brick on the west side and part of the north side may be treated as if it were an outside wall in the shade which has a temperature differential (from Table Iff) of j2 deg. ; ` For the door in.north'wall estimate U = 0.59 from Chapter 9, Table 10, No. 5A. The outdoor temperature at 3:00 p.m. is 95 F. Neglect time lag and any decrement factor. The temperature differential is (*,, -- {,) -- 95 -- 80 = 15 deg. The tabula tion of the preceding values at 3:00 p.m. is given in the following table: Section North Exposed Wall West 4 North Party Wall Door in North Wall Net Area Sq Ft 4000 405* 765" : 170" 1065* 35 Temperature Differential, F Deg Heat 7 Transmission Coefficient (U) - Heat Flow . Rate per Hour Btu 53 0.34 72,000 6 0.41 995 11 0.52 4,380 3 0.52 265 2 0.26 550 15 0.59 310 78,500 " Calculated from gross wall area, less windows and doom. Heat Gain Through Glass Areas In computing the load for 3:00 p.m., only the south windows and doora will be exposed to direct sunlight: Tables 13 and 14 will give the total heat gain from the glass areas. The window reveals will shade the south windows; the fraction of the window area receiving direct radiation is obtained from Equation 5 by substituting values as follows: r, = s/l -- 4/60; rj = 4/36; 0 = 45.5 deg, tan 0 = 1.02 : y = 74 deg, tan y = 3.487, cos y -- 0.276 ,, _ , _ i / L02\ _ 4 /\ (4\ (1.02) (3.487) 0, 1 60 (.0.276/ 36 *3487^ + (.60/ \36j 0.276 = -462' The south doors will be considered entirely sunlit. The outdoor air temperature Cooling'Load 325 is;95'F at 3:00 pan\ From Table 24-the inside Venetian blind factoT is 0.65. The instantaneous heat gains due to transmitted direct and diffuse solar radiation, and irom convection and radiation gain, are found in Tables 13 and 14 as listed below for the south facing doors and windows, the north facing windows and the j glass doors in the east wall., The gain through the solid portion of the east doors may be approximated by use of Fig. 3, since the wood panels have little heat capacity. From Table 4. the diffuse radiation value is taken as 18 Btu.per (hr)(sq ft) from which to -f ajfjfco is found to be 98.2 for o =' 0.7 and = '4.0. From Fig. 3, q = 27.0 Btu per (hr)(sq ft). These heat gains are itemised in the following table (note that there,are no corrections to Table 14 values since table is based on 80F temperature, but Fig. 3is bhsed on 75 F room temperature). Location South Windows South Doors ` ; -' East Doors/Glass \Wood North Windows Total . Cobb Area ` Frac tion Sunlit Sq Ft Shade Factor Trans Solar Gain Btu/ (hr) (sq ft) CONV and Rad Gain from 75F to 80F Btu/ Indoor (hr) Temper (8Q FT) ature Btu/(hr) (bq ft) Total Gain Btu/ (hr) (sq ft) Total Gain Btu/hr . - 60 . " ` 35 18 ' 18 . 30 0.462 1.00 ;0.65 . 13 42 14 15 19 19 17 27 17 _ 32 1920 61 2135 31 '560 ' 22 395 32 960 5970 . ____ ,______ _________ ........ ....... ... icucacc vor uecreasej tne instantaneous radi ation heat gain by a load-lag factor. The reason for not doing so in this case is that the solar gain is of a low magnitude, and reference to the table indicates that 0.8 of the previous hour would not affect the results materially. Since the desired outdoor air rate 1275 cfm is greater than one air change per hour, it will be satisfactory for determining the ventilation component of the heat gain. .. Window infiltration can be taken as negligible Bince the windows do not open. Door infiltration requires some judgment. Assume that for each person passing through the double doors, the infiltration will be 100 cu ft of outdoor air, see Chapter 10, Table 3. Assume that the outside doors will be used at the rate of 10 persons per .hour and the inside doors at the rate of 30 persons per hour. Total infiltration will then be 40 X 100 = 4000 cfh or 67 cfm. The design rate of entry of outside air is then : The sensible, latent and total loads are determined from Equations 7, 8, and 9, respectively, at 3:09 p.m. (Table 8) U 95, ti = 80, Wo = 0.0169, Wi = 0.0098. All the air entering the room as infiltration becomes a part of the space load. Infiltration (see Equations 7, 8, and 9): q. = ' 67 X 1.08 (95-80) = 1085 Btuh, sensible. q. = '67 X 4840 (0.0169-0.0098) = 2300 Btuh, latent. ' + g,, = 1085 + 2300 = 3385 Btuh, total. Ventilation Air Taken through Cooling Unit Which Becomes a Part of the Space Load (see Equations 10and 11): . , ?.i = 1275 X 1.08 (95-80) (0.15) = 3,100 Btuh, sensible. = 1275 X 4840 (0.0169-0.0098) (015) = 6,570 Btuh, latent. 326 CHAPTER 13 1956 Guide Ventilation Air Taken through Cooling Unit Which Dots Not Become aPart of the Space Load (see Equations 12 and 13): = 1275 X 1.08 (95-80) (1-0.15) = 17,600 Btuh, sensible. g = 1275 X 4840 (0.0169-0.0098) (1-0.15) = 37,230 Btuh, latent. St = ff.i + g + g.i + ?. = 3100 -f 17600 + 6570 + 37230 = 64,500 Btuh total. Heat Gain from Sources within the Conditioned Space: For the occupants, use the data of Table 25 for moderately active office work. Sensible heat gain = 85 X 200 = 17,000 Btu per hr. Latent heat gain = 85 X 250 = 21,250 Btu per hr. Total = 38,250 Btu per hr. For the gain from lighting, use Equation 15 with a use factor of unity, and a special allowance factor of 1.20 for the fiuorescents and of unity for the tungsten globes. q., = (12,000 X 1.20 + 4000) X 3.41 = 62,700 Btu per hr. For the fan motor, use Equation 16 with a load factor of unity, and omit term Motor Efficiency because the motor is not within the space. -- 7.5 X 2544 = 19,100 Btu per hr. Moisture Permeation, Miscellaneous Allowance, and the Load-Lag Estimate: Moisture permeation will be negligible, since this is a comfort job with a good building construction. There would be some heat gain in the ductwork, but this would not be great be cause of the short run involved. Practical judgment for this job would suggest that no adjustment for load-lag need be made to the load as computed. (Refer to Fig. 4). While it is true that inside radiation forms an important part of the total heat gain, it is advisable to be conservative in recognizing the effect of the large, flat, hot roof on the comfort sensations of the occupants. Radiation from the relatively low ceiling, augmented by heat absorption from the lighting fixtures, Would produce a sensation of warmth in excess of the nominal effective temperature (see Chapter 6) estab lished by the wet-bulb and dry-bulb temperatures. Hence, it is not desirable to take advantage of every small decrease possible in the peak design load, especially since the peak occurs in mid-afternoon when everything would be rather well warmed. Total Loads and Required Air Quantity through Conditioning Equipment: The total loads are summarized in the following table: - SuMMABT OF TOTAL LOADS--EXAMPLE 13 Load Component Sensible Btufht Latent Btu/br Space Load............................................................ Totals...................................................................... Grand Total Sensible and Latent.................... 78,500 6,030 1,085 3,100 17,000 62,700 19,100 187,515 17,600 205,115 2,300 6,570 21,250 30,120 37,230 67,350 272,465 Compute the enthalpy difference ratio from Equation 18. h, - h. (187,455 + 30,120) X 1076 = 7770. Wi-W. 30,120 Cooling Load 327 From the A.S.H.A.E. psychrometric chart Chapter 3, determine that the appa ratus dew-point as 53.9 F. ' Compute the effective air quantity (Equation 19). Then, 187,455 Q,. 1.08 (80 - 53.9) X 0.85 = 783 Cfm' From note under Equation 19 the dry-bulb range will be (80 -- 53.9) X 0.85 = 22:2 deg, and the dry-bulb temperature of air leaving the coil will be 80 --.22.2 = 57.8 F. The dry-bulb temperature leaving the fan (including the heat supplied by the fan motor), or delivered into the room, will be (from Equation 16): 187,455 - 19,100 1.08 X 7830 80 - 19.9 = 60.1 F. : With good distribution and diffusion, this temperature should not produce objec tionable drafts. The various calculations for the sensible, latent, and total heat loads for Example 13 may be summarized as follows: Outdoor Conditions..' Space ConditionsTT.'.'. Difference. .-.. 13:Example Summary .:. . . .95 DB ..........80 DB 78 WB 65 WB 15 0.0169 Humidity Ratio 0.0098 Humidity Ratio 0.0071 Sensible Load . Transmission Roof 4000 sq ft X 53 X 0.34 .. ......................................................... S. Wall 405 sq ft X 6 X 0.41 =.......................................... ..................... E. Wall 765 sq ft X 11 X 0.52 =............................................................. N. Wall Ex. 170 sq ft X 3 X 0.52 =........,-------.......... N. & W. Party Wall 1065 sq ft X 2 X 0.26 =......................... .. Floor None Btu/Hr 72,000 44,,33928896"0055 550 Door 35 sq ft X 15 X 0.59 =..................... '................................................ 310 All Glass and Rest of Doors =........................................................... 33,0n2o0n Solar Radiation S. Glass 60 sq ft X 13 =,..................................................................... S. Glass (Doors) 35 sq ft X 42 =........ ........... .......................................... E. Glass (Doors) 18 sq ft X 14 =.............................................................. N. Glass 30 sq ft X 15 =............................................................ ......... 11,477800 250 450 Internal Load Infiltration 67 cfm X 1.08 X 15 =..:.................... .................................. Ventilation 1275 cfm X 108 X 15 X 0.15................................................ Lights (12,000 X 1.20 + 4000) 3.41 =............................................... 33-1,,100805 People 85 X 200 =................................ ,....................... ............... ... - 62,700 Motor, Fan 7.5 hp X 2544 =............................................................... 17,000 19,100 Total Sensible Space Load........................................................................ ' Latent Load . Infiltration 67 cfm X 4840 X 0!0071 =........................... ......................... 2, Ventilation 1275 elm X 4840 X 0.0071 X 0.15 ........................................... 62,,300 People 85 X 250 -................................................................................... 6,570 21,250 187,455 Total Latent Space Load............................................................................ Ventilation Air Which Does Not Become Pabt of Space Load Sensible 1275 cfm X 1:08 X 15 X (1-0.15) "....................:.....................D. Latent 1275 cfm X 4840 X 0.0071 X (1-0.15) ............................ ' Grand Total Load.................. ................................................. 30,120 17,600 37,230 272,405 328 CHAPTER 13 1956 Guide LETTER SYMBOLS USED IN CHAPTER 13 a = fraction of incident solar radiation absorbed, dimensionless; subscripts D, d, and t refer to direct, diffuse and total, respectively. 0 = solar altitude, degrees. . y ~ wall solar azimuth, degrees. t = emissivity, dimensionless. fl = incident angle, degrees. \ = amplitude decrement factor, dimensionless, r = fraction of incident solar radiation transmitted, dimensionless. Subscripts D, d and t refer to direct, diffuse and total, respectively. = solar azimuth, degrees. ' rf/ wall azimuth, degrees. A = area across which heat is being transferred, square feet. 6 = fraction of air passing through coil which does not contact surfaces, coil by-pass factor. f = unit surface conductance, Btu per (hour) (square foot) (Fahrenheit degree). Subscripts c,.r, o, and i refer to convection, radiation, outdoor, and indoor, respectively. Of = fraction of total window area receiving direct solar radiation when shaded by ` , window reveal, dimensionless. h = enthalpy of air per pound of dry air, Btu per pound. Subscripts i, o, and s refer to indoor, outdoor, and supply air, respectively. 1 - incident solar radiation, Btu per (hour) (square foot). Subscripts D, d, Dn, and t refer to direct, diffuse, direct normal and total solar radiation, respectively. K = cosine of angle of incidence for direct solar radiation striking a surface, dimen sionless. k = thermal conductivity of building material, Btu per (square foot) (hour) . (Fahrenheit degree per inch). I = height of window, feet., M = the permeance of the specimen in perms or grains per (square foot) (hour) (inch of mercury vapor pressure difference). Q = rate of entry of butdoor air, cubic feet per minute. Q,, = required air quantity through conditioning equipment, cubic feet per min ute. . q = instantaneous rate of heat transfer, Btu per hour. qe = instantaneous latent heat load, Btu per hour. ge, = instantaneous space latent ventilation load, Btu per hour. qa = instantaneous latent ventilation load- which does not become a part of space load, Btuh. ' qm = latent heat load due to moisture transmission through materials, Btu per (hour) (square foot). q, -- instantaneous sensible heat load, Btu per hour. ' q,= instantaneous space sensible ventilation load, Btu per hour. g,, = instantaneous sensible ventilation load which does not become a part of space load, Btu per hour. gt = g. 4- g>, also g.i 4- g f g.i 4- ?ex, Btu per hour. . R, -- low temperature-radiant energy received from outdoor surroundings (does ' not include solar radiation), Btu per (hour) (square foot of receiving surface). R = radiant energy emitted by a black body, Btu per (hour) (square foot). Subscripts go and L refer to outdoor surfaces of glass and building, respec tively. S -- rate of heat storage within a glass section, Btu per (hour) (square foot), t,, = sol-air temperature, Fahrenheit. Cooling Load 329 4* = sol-air temperature at a time earlier than the time for which heat gain is being found by ap amount that is equal to the time lag of the wall or roof Fahrenheit. tgl = temperature of indoor glass surface, Fahrenheit. <go = temperature of outdoor glass surface, Fahrenheit. h = indoor air temperature, Fahrenheit. to. = 24-hr cyclic average sol-air temperature, Fahrenheit. = outdoor air temperature, Fahrenheit, f. = room supply air dry-bulb temperature, Fahrenheit. U = overall coefficient of heat transfer of a structural section, Btu per (square foot) (hour) (Fahrenheit degree). - '- Vo = volume of outdoor air per pound of dry air, cubic feet. w -- width of window, feet. . W = humidity ratio, pounds moisture per pound of dry air. Subscripts i, o, and s refer to indoor, outdoor, and supply air, respectively. REFERENCES 1 Application Engineering Standards for Air Conditioning for Comfort (Air Conditioning and Refrigerat ing Machinery Association, lnc.t 1947, pp. 4-7). * Minimal Replenishment Air Required for Living Spaces, by W. V. Consol&zio and L.. J. Pecora (A.S.H.V.E. Transactions, Vol. 63, 1947, p. 127). . * Recommended Safe Practice of the NBFU for Hospital Operation Rooms, Pamphlet No. 66, National Board of Fire Underwritere. * Proposed Standard Solar Radiation Curves for Engineering Use, by P. Moon (Journal of the Franklin Institute, November 1940, Vol. 230, No. 5, pp. 683-617). * A.S.H.VJC. Research Report No. 1268--Summer Weather Data and Sol-Air Temperature--Study of Data for Lincoln, Nebr., by C. O. Mackey (A.S.H.V.E. Transactions, Vol. 61,1945, p. 93). * Summer Weather Data and Sol-Air Temperature--Study of Data for New York City, by C. O. Mackey and E. B. Watson (A.S.H.VJE. Transactions, Vol. 51, 1945, p. 75). 7 Summer Cooling for Comfort as Affected by Solar Radiation, by G. A. Hendrikson and J. H. Walkei (Heating and Ventilating, Vol. 29, No. 11, November 1932, pp. 14-21). .' Tables of Computed Altitude a$d Aximuth (U. B. Navy Dept. Hydrographic Office Bulletin No. 214' Vola. 1-9, Washington, D. C., 1940). * The American Nautical Almanac (U. S. Naval Observatory, Washington, D. C., annual). M A.S.H.V.E. Research Report No. 923--Heat Transmission as Influenced by Heat Capacity and Solar Radiation, by F, C. Houghten,. J. L. Blackshaw, E. M. Pugh and Paul McDermott (A.S.H.V.E. Trans actions, Vol. 38, 1932, p. 231). Effect of Heat Storage and Variation in Outdoor Temperature and Solar Intensity on Heat Transfer Through Walls, by J. S. Alford, J. E. Ryan and F. O. Urban (A.S.H:V.E. Trans actions, Vol. 45, 1939, p. 369). Periodic Heat Flow in Building Walls Determined by Electrical An alogy Method, by Victor Paschkis (A.S H.V E. Transactions, Vol. 48, 1942, p. 75).--Periodic Heat FlowHomogeneous Walls or Roofs, by C. O. Mackey and L. T. Wright, Jr. (AB.H.V.E. Transactions. Vol. 60. 1944, p. 293). Periodic Heat Flow--Composite Walls or Roofs, by C. O. Mackey and I*. T. Wright, Jr. (A.S.H.V.E. Transactions, Vol. 52, 1946, p. 283). Periodic Heat Transfer at the Inner Surface of a Homogeneous Wall, by H. A. Johnson (A.S.H.VJ1 Transactions, Vol. 54,1948, p. 143). 11 TheEffect of Solar Radiation on th Tfmwmttyi(>n Thynygh by F. C. Houghten, CarlGutberlet aijd A. A. Rosenburg (American Society of Testing Materials Symposium on Thermal Insulating Materials, Philadelphia, 1939). . A.S.H.VJS. Research Report No. 1157--Summer Cooling Load as Affected by Heat Gain Through Sprinkled and Water Covered Roofs, by F. C. Houghten, H. T. Olson and Carl Gutberlet (A.S.H.VH. Transactions, Vol. 46, 1940, p. 237). ** A.S.H.VJ2. Research Report No. 1002--Cooling Requirements of Single Rooms in a Modern Office uilding, by F. C. HoughteD, Carl Gutberlet, and Albert J. Wahl (A.S.H.V.E. Transactions, Vol. 41,1935* P. 53). 14 Stu<Jy Actual vs. Predicted Cooling Load on An Air Conditioning System, by James N. Livermore (A.S.H.V.E. Transactions, Vol. 49, 1943, p. 287). . ** A.S.H.V.E. Research Report No. 1195--Heat Gain Through Walls and Roofs as Affected by Solar Radiation, by F. C. HoughteD, E. C. Hacb, S. 1. Taimuty and Cart Gutberlet (A.8.H.V.E. Transactions vol. 48, 1942, p. 91). 330 CHAPTER 13 1956 Guide 11 Solar Heat Gain Through Walls and Roofs for Cooling Load Calculations, by J. P. Stewart (A.S.H.V.E. (Transactions, VoI. 54,1948, p. 361). ' . A.S.H.V.E. Research Report No. 1442, Radiant Energy Emission of Atmosphere and Ground, by G. V. Parmeleeand W. W. Aubele (A.S.H.V.E. Transactions, Vol. 58, 1952, p. 85). w Radiation in the Atmosphere, by D. Brunt (Supplement to the Quarterly Journal of the Royal Mete orological Society, Vol. 66, 1940). A.S.H.V.E. Research Repost No. 1333--Measurements of Solar Heat Transmission Through Flat Glass, by G. V. Parmelee, W. W. Aubele and R. G. Huebscber (A.S.H.V.E. Transactions, VoL 54, 1948, p. 165). * A.S.H.V.E. Research Report No. 1348--Solar and Total Heat Gain Through Double Flat Glass by G. V, Parmelee and.W. W. Aubele (A.S.H.VJ2. Transactions, Vol 54, 1948, p. 407). . ** A.S.H.VJS. Research Repost No. 1374--Solar Energy Transmittance of Eight-Inch Hollow Glass Block, by G. V. Parmelee and W. W. Aubele (A.S.H.V.E. Transactions, Vol. 55.1949, p. 435) ` B A.S.H.V.E. Research Report No. 1399---Heat Flow Through Unshaded Glass: Design Data for Use in Load Calculations, by G. V. Parmeleeand W. W. Aubele (A.S.H.VJS. Transactions Vol. 56,1950, p. 371). ** A.S.H.V.E. Research Report No. 1417--Solar Energy Transmittance of Figured Rolled Glass, by G. V. Parmeleeand W. W.'Aubele (A.S.H;V.E. Transactions, Vol. 57, 1951, p. 209). ** A.S.H.VJE. Research Report No. 975--Studies of Solar Radiation Through Bare and Shaded Win dows, by F. C. Houghten, 'Carl Gutberlet and J. L. Blackshaw (A.S.H.V.E. Transactions, Vol. 40, 1934, p. 101). -. A.S.H.V.E. Research Report No. 1485--Design Data for Slat-Type Sun Shades for Use in Load Es timating, by G. V. Parmelee and D. J. Vild (A.S.H.V.E. Transactions, Vol. 59, p. 403), A.S.H.V.E. Re search Report No. 1474--The Shading of Sunlit Glass: An Experimental Study of Slat-Type Sun Bhades, by G. V. Parmelee, W. W. Aubele and D. J. Vild (A.S.H.V.E. Transactions, Vol. 59, 1953, p. 221). A.S. H. VJ3. Research Report No. 1460--The Shading of Sunlit Glass: An Analysis of the Effect of Uniformly Spaced Flat Opaque Slats, by G. V. Parmelee and W. W. Aubele (A.S.H.V.E. Transactions, Vol. 58,1952, p. 337). * A.S.H.VJS. Research Report No. 1180--Heat Gain Through Western Windows With and Without Shading, by F. C. Houghten and David Shore (A.S.H.VJ2. Transactions, Vol. 47, 1941, p. 251). n The Mechanism of Heat Transfer, Panel Cooling and Heat Storage, Part H: Solar Radiation, by C. S. Leopold (Refrigerating Engineering, June 1948, p. 571). " * The Mechanism of Heat Transfer, Panel Cooling, Heat Storage, by C. S. Leopold (Refrigerating Engi neering, July 1947, p. 33). Hydraulic Analogue for the Solution of Problems of Thermal Storage, Radiation, Convection and Conduction, by C. S. Leopold (A.S.H.VJ3. Journal Section, Seating, Piping and Air Conditioning, July 1948, p. 105)! ' '* Heat Gains Are Not Cooling Loads, by C, O. Mackey and N. R. Gay (A.S.H.V.E. Transactions, Vol. 55, 1949, p. 413). w Cooling Load From Sunlit Glass, by C. O. Mackey and N. R. Gay (A.S.H.V.E. Transactions, Vol. 58, 1952, p. 321). 41 Psychrometric Factors in the Air Conditioning Estimate, by C. M. Ashley (A.S.H.VJS. Transactions, Vol. 55, 1949, p. 91). ** See Reference 1, p. 8. ** Cooler Footcandlee for Air Conditioning, by W. G. Darley (A.S.H.V.E. Transaction, Vol. 46, 1940, p. 367). Lighting and Air Conditioning Design Factors, Report of 1JSJS.--A.S.H.VJ3. Joint Committee on Lighting and Air Conditioning (AJ3.H.V.E. Journal Section, Beating, Piping and Air Conditioning, Sep tember 1941, p. 605). Lighting and Air Conditioning, by Howard M. Sharp (Heating and Ventilating, No vember 1942, p. 35). m Compiled by J. P. Stewart from various sources. CHAPTER 14 FUELS AND COMBUSTION Solid Fuels: Analysis, Classification of Coals, Dustless Treatment, Classification of Cokes, Combustion of Solid Fuels, Firing Methods for Solid Fuels, Secondary Air, Draft Requirements and Regulation, Furnace Volume; Fuel Oils: Classification, Analysis, Combustion, Air Required; Fuel Gases: Classification, Heat Value, Combustion; General Combustion Principles; Air Required; Efficiency from Flue Gas Analysis; . Heat Balance; Condensation and Corrosion; Soot FUELS may be classified according to their physical state as solid, liquid, or gaseous. The principal fuels used for domestic heating are coal, oil, and gas. However, coke, wood, kerosene, sawdust, briquettes, and other substances are used for heating in special applications or in localities where an adequate supply is available. Experiments are in progress in the use of a colloidal siispension of coal particles in fuel oil, but this fuel has not attained wide-spread usage as yet. The choice of fuel is usually based on dependability, cleanliness, availability, economy, operating requirements, and control. Analysis of Fuels SOLID FUELS Coal has a complex composition that makes classification into clear-cut types difficult. Chemically it consists of carbon, hydrogen, oxygen, nitro gen, sulfur, and a mineral residue called ash. A chemical analysis provides some indication of the quality of a coal, but does not define its burning characteristics sufficiently. The coal user is interested principally in the available heat per pound of coal, the handling and storing properties, the amount of ash and dust produced, and the burning characteristics. A description of the relationship-between the qualities of coals and these characteristics requires considerable space; a treatment applicable to heating boilers is given in a Bureau of Mines Bulletin.1 There are two forms of coal analyses, namely, the proximate analysis and the ultimate analysis. In the proximate analysis the proportions of moisture, volatile matter, fixed carbon, sulfur, and ash are determined. This analysis is more easily made and is satisfactory for indicating most of the characteristics which are of interest to the user. For the proximate analysis the moisture is determined by observing the loss of weight of a sample of coal when dried at about 220 F. To determine the volatile matter, the dried sample is heated to about 1750 F in a closed crucible, and the loss of weight is noted. The remaining sample is then burned in an open crucible, and the accompanying loss of weight represents the fixed carbon. The unbumed residue is ash. Although determined separately, the sulfur content is frequently reported with the proximate analysis be cause the usefulness of a coal for certain purposes depends on its sulfur content. In the ultimate analysis, which is difficult to make, the percentages of carbon, hydrogen, oxygen, nitrogen, sulfur; and ash in the coal sample are determined. It is used for detailed studies of fuels, and in computing 331 . 332 CHAPTER 14 1956 Guide a heat balance when required in testing of heating devices. Typical ulti mate analyses of the various kinds of coal are shown in Table 1.* ' Other important qualities of coals are the screen sizes, ash fusion tem perature, friability, caking tendency, and the qualities of the volatile matter. In considering these factors the following points are of interest. The volatile products given off by coals when they are heated differ mate rially in the ratios by weight of the gases to the oils and tars. No heavy oils or tars are given off by anthracite, and very small quantities are given off by semi-anthracite. As the volatile matter in the coal increases to as much as .40 percent of ash and moisture-free coal, increasing amounts of oils and tars are released. For coals of higher volatile content, the relative quantity of oils and tars decreases and is therefore low in the sub-bituminous Table 1. Typical Ultimate Analyses for Coals Btu per La . Constituents, Psa Cxnt Rank Moist, MineraJtnatter- free* Moist, aa Received Oxygen Hj- Carbon Nitrogen Sulfur drogen 1 Anthracite. __ -- .. 14,600 12,910 5.0 2.9 80.0 0.9 0.7 Semi-Anthracite_______ 15,200 13,770 5.0 3.9 80.4 1.1 1.1 Low-Volatile Bituminous 15,350 14,340 5.0 4.7 81.7 1.4 1.2 Medium-Volatile Bituminous_________ 15,200 13,840 5.0 5.0 79.0 1.4 1.5 High-Volatile Bituminous A_______ 14,500 13,090 9.2 5.3 73.2 1.5 2.0 High-Volatile Bituminous B -- .. 13,500 12,130 13.8 5.5 68.0 1.4 2.1 High-Volatile Bituminous C----------- 12,000 10,750 21.0 6.8 60.6 1.1 2.1 Sub Bituminous B... ..... 10450 9,150 29.5 6.2 52.5 1.0 1.0 Sub Bituminous C......... 9,000 8,940 35.8 6.5 46.7 0.8 0.6 Lignite................ -......- 7,500 6,900 44.0 6.9 40.1 0.7 1.0 Ash . 10.5 8.5 6.0 8.1 8.8 9.2 9.4 9.8 9.6 7.3 fOfrrff C 87.9 89.3 91.4 89.0 87.7 87.3 87.4 88.2 89.0 91.0 * (Btu as received) X 100 4- (100 -- 1.1 AehJ coals and in lignite. The percentage of ash and its fusion temperature do not indicate the composition or distribution of its constituents. ; Classification of Coals A classification of coals is given in Table 2, and a brief description of the kinds of fuel is given in the following paragraphs, but it should be recog nized that there are no distinct lines of demarcation between the kinds, and that they graduate into each other. ' Anthracite is a clean, dense, hard coal which creates little dust in handling.. It is comparatively hard to ignite, but it burns freely when well started. It is non-caking, it bums uniformly and smokelessly with a short flame, and it requires no attention to the fuel bed between firings. It is capable of giving a high efficiency in the common types of hand-fired furnaces. A tabulation of the quality of the various anthracite sizes will be found in a Bureau of Mines Report.3 Standard anthracite sizing specifi cations are shown in Table 3. Semi-anthracite has a higher volatile content than anthracite. It is hot so hard, and ignites somewhat more easily. Otherwise their properties are similar. - Semi-bituminous coal is soft and friable, and fines and dust are created by handling it. It ignites somewhat slowly and burns with a medium length of flame. Its cakingproperties increase as the volatile matter increases, but the coke formed is relatively weak. Having only half the volatile matter content of the bituminous coals, it can be burned with less production of smoke, and is sometimes called a smokeless coal. Fuels and "Combustion 333 The term bituminous coal covers a large range of coals and includes many types having distinctly different composition, properties, and burning characteristics. The coals range from the high-grade bituminous coals of the East to the poorer coals of the West. Their caking properties range from coals which melt completely, to those from which the volatiles and tars are distilled without change of form, so that they are classed as non-caking or free-burning. Most bituminous coals are strong Table 2. Classification of Coals by Rank" ' Legend; F.C. = Fired Carbon.. V.M. * .Volatile Matter. Btu = British thermal unite. Class Group Limits ov Fixed Carbon - ob Btu Minebal-Matteb- Requisite Physical Fbse Basis Properties ` 1. Meta-anthracite. Dry F.C., 98 per cent or 2. Anthracite........... more (Dry V.M., 2 per cent or less) jDry F.C., 92 per cent or X. Anthracite. .. 3. Semi-anthracite. 1. Low volatile bituminous ooal.. more and less than 98 per cent (Dry V.M., 8 percent or less and more than 2 per cent) Dry F.C., 85 per-cent, or more and less than 92 per cent (Dry V.M., 14 per cent or less and more than 8 per cent) Dry F.C.; 78 per cent or Non-agglomerating II. Bituminous** 2. Medium coal volatile bituminous ' more and less than 86 per cent (Dry V.M., 22 per cent or less and more than 14 per cent) Dry F.C., 69 per cent or more and less than 78 i per cent (Dry V.M./ 31 | per cent or less and more ' than 22 per cent) Either agglomerate mg oj- non- Hi Sub-bitumi nous Iv- .....I 3. High volatile A bituminous coal . 4. High volatile B bituminous coal .. _ 5. High volatile C bituminous Coal l. Sub-bituminous A coal................ 2. Sub-bituminous B coal.. 3. Sub-bituminous C coal.. Dry F.C., less than 69 per cent (Dry V.M . more than 31 per cent); and moist* Btu, I4,000r or more . Moist* Btu, 13,000 or more and less than 14,000* Moist Btu, 11,000 or more and less than 13,000* Moist Btu, 11,000 or more and less than 13,000* Moist Btu. 9500 or more and less than 11,000* Moist Btu, 8300 or more and less than 9500* Moist Btu less than 8300 Moist Btu less than 8300 weathering^ Both weathering and non-agglomerat ing Consolidated Unconsolidated a This classification does not include a few coals which have unusual physical and chemical properties and which come within the limits of fixed carbon or Btu of the high-volatile bituminous and sub-bituminous mnks. All of these coals either contain less than 48 percent dry, mineral-matter-free fixed carbon, or have more than 15,500 moist, mineral-matter-free Btu. * If agglomerating, classify in low-volatile group of the bituminous class. _ _ _ . e Moist Btu refers to coal containing its natural bed moisture but not including visible'water on the surface - of the coal. A It is recognised that there may be non-caking varieties in each group o 1 the bituminous cJass. _ * Coals having 69 percent or more fixed carbon on the dry, mineral-matter-free basis shall be classified Recording to fixed carbon, regardless of Btu. ' { There are three varieties of coal in the high-volatile C bituminous ooal group, name) y, Variety 1, agglom erating and non-weathering; Variety 2, agglomerating and weathering; Variety 3, non-aggloraerating and non-weathering. . Adapted from AJ3.T.W. Standards. 1957, Supplement, p. 145, American Society for Testing Materials. and non-friable enough to permit the screened sizes being delivered free from fines general, they ignite easily and burn freely; the length of flame varies with different coals, but it is long. Much smoke and soot are possible* if improperly fired, especially at low rates of burning. ! Sub-bituminous cools occur in the western states; they are high in moisture when mined and tend to# break up as they dry or when exposed to the weather; they are liable to ignite spontaneously when piled or stored. They ignite easily and quickly, and have a medium length flame; are non-caking and free-burning; the lumps tena to break into small pieces if poked; very little smoke and soot are formed. Liffnite is of woody structure, very high in moisture as mined, and of low beating 334 CHAPTER 14 1956 Guide value; it is clean to handle. It has a greater tendency than the sub-bituminous coals to disintegrate as it dries, and it also is more liable to spontaneous ignition. Freshly mined lignite, because of its high moisture, ignites slowly. It is hon-caking. The char left after the moisture and volatile matter are driven off burns very easily, like charcoal. The lumps tend to break up in the fuel bed, and pieces of char falling into the ashpit continue to burn. Very little smoke or soot is formed. Dustless Treatment In order to allay the dust, the more friable coals are sometimes sprayed with various petroleum products, a solution oi calcium chloride, or a mix ture of calcium and magnesium chlorides. The coal is usually treated at the mine, but sometimes by the local dis tributor just before delivery. The salt solutions are sprayed under high Table 3. Standahd Anthuacite Specifications* Size ot Coal Test Mesh Round __ OVZB0XZS t Maximum Impubthes . In. Max. % Max. % Min. % Slate*1 % I Bone*5 % or Aeh % 4H 3)4 to 3 1*Me Me . hMe* Me 3H to 3 2M* IM. MMvMees M MMe* 7M 10 10 15 1H 1H in ltt m2 m in in m 10 in N o. 5 .............. M* 11 11 11 11 12 13 13 15 15 16 * Approved and adopted, effective July 28, 1947, by the Antxuacne womuuiiiicv ____ . _ InfobrmWahteionnd,aAtenicAoronctettnetiinnxtthitvetseic).es from Broken to Nut inclusive is less thpn above standards, bone content may be increased by one and one-half times the decrease in the slate content under the allowable limits, but slate content specified above shell not be exceeded in any event, - Ac Atoshlerdaentceermo!in1aptieorncsenatries oanlloawdedryonbatshies. maximum percentage of undersize and the maximum percentage of ash content. The maximum percentage of undersize is applicable only tp anthracite as it is produced at theSplaretepaisradteiofinnepdlaansta. ny material which has less than 40 percent of fixed carbon. ' Bone is defined as any material which has 40 percent or more, but less than 75 percent of fixed carbon. pressure, using from 2 to 4 gal or from 5 to 10 lb of the salt per ton of coal, depending on its friability and size. Oil for the dustless treatment of coal is also applied under high pressure, in concentrations of 1 to 8 qt per ton of coal, depending upon the characteristics of the coal and oil. Dustless treatments, which are of such a corrosive nature that they may damage coal handling or burning equipment, should not be used. ClaCsoskeifiicsaptrioodnuocefdCboykethse distillatio- n of the volatile matter from coal. The type of coke depends on the coal or mixture of coals used, the temperatures and time of distil lation and, to some extent, on the type of retort or oven. Coke is also produced as a residue from the destructive distillation of oil. High-temperature cokes. Coke, as usually available, is of the high-temperature type, and contains between 1 and 2 percent volatile matter. High-temperature cokes are subdivided into beehive coke of which comparatively little is now sold for domestic use, by-product coke, which covers the greater part of the coke sold, and gas-house coke. - The differences among these three cokes are relatively small; their denseness and hardness decrease and friability increases in the order named. In general, the lighter anLdomwo-treemfpriearbalteurceockoeksesiganreitepraondducbeudrnatmloowrecroekaidngilyt.emperatures, and only a portion of the volatile matter is distilled off. Cokes, as made by various processes under de velopment, have contained from 10 to 15 percent volatile matter. In general, these cokes ignite and burn more readily than high-temperature cokes. The properties of various low-temperature cokeB may differ more than those of the various high-tem- Fuels and Combustion 335 perature cokes because of the differences in the quantities of volatile matter, and because some may be light and others briquetted. Petroleum cokes, which are obtained by coking the residue left from the distillation of petroleum, vary in the amount of volatile matter they contain, but all have the common property of a very low ash content, which necessitates the use of refractory pieces to protect the grates from being burned. 1 COMBUSTION OF SOLID FUELS Firing Methods for Anthracite An anthracite fire should never be poked or disturbed, as this serves to bring ash to the surface of the fuel bed, where it may melt into clinker. Egg size is suitable for large fire-pots (grates 24 in. and over) if the fuel can be fired at least 16 in. deep. For best results this coal should be fired deeply. Stove is the proper size of anthracite for many boilers and furnaces. It bums well on grates at least 16 in. in diameter, on which it is fired about 12 in. deep. The fuel should be fired deeply and uniformly. , . Chestnut size coal is in demand for fire-pots up to 20 in. in diameter, and is usually fired to a depth of from 10 to 15 in. Pea size coal-is often an economical fuel to bum. When fired carefully, pea coal can be burned on standard grates. Care should be taken to shake the grates only until the first bright coals begin to fall through the grates. The fuel bed, after a new fire has been built, should be increased in thickness by the addition of small charges until it is at least level with the sill of the fire-door. A satisfactory method of firing pea coal consists of drawing the red coals toward the front end, and piling fresh fuel toward the back of the firebox. Pea size coal requires a strong draft, and therefore the best results generally will be obtained by keeping the choke damper open, and regu lating solely by means of the cold air check and the air inlet damper. Buckwheat size coal, for best results, requires more attention than pea size coal, and in addition the smaller size of the fuel makes it more difficult to bum on ordinary grates. Greater care must be taken in shaking the grates than with the pea coal on account of the danger of having fuel fall through the grate. In house heating furnaces, the coal should be fired lightly and more frequently than pea coal. When banking a buckwheat coal fire, it is advisable after coaling to expose a small spot of hot fire by putting a straight poker down through the bed of fresh coal. This wiil serve to ignite the gas that will be distilled from the fresh coal and prevent delayed ignition which, in some cases, depending upon the thickness of the bed of fresh coal, is severe enough to blow open the doors and dampers of the furnace. Where frequent attention can be given and care exercised in manipulation of the grates, this fuel can be burned satisfactorily without the aid of any special equipment, except small mesh grates. In general, it will be found more satisfactory with buckwheat coal to maintain a uniform heat output and, consequently, to keep the system warm all the time, rather than to allow the system to cool off at times and then to attempt to bum the fuel at a high rate while warming up. A uni form low fire will minimize the clinker formation and keep any clinker formed in an easily broken up condition so that it readily can be shaken through the grate. Forced draft and small mesh grates or, for greater convenience, domestic stokers are frequently used. Buckwheat anthracite No. 2, or rice size, is used principally in stokers 336 CHAPTER 14 1956 Guide of the domestic, commercial and industrial type. No. 3 buckwheat anthra cite, or barley, has no application in domestic heating. / Firing Methods for Bituminous Coal A commonly recommended procedure for firing domestic heating units, called the side-bank method, requires the movement of live coals to one side or the back of the grate, and placing the fresh fuel charge on the opposite side. The results are a more uniform release of volatile gases, and the subjection of these gases to the high temperature of the red coals. If the fresh charge is covered with a layer of fine coal, still better results may be obtained because of slower release of volatile matter. Bituminous coal should never be fired over the entire fuel bed at one time. A portion of the glowing fuel should always be left exposed to ignite the gases leaving the fresh charge. The importance of firing bituminous coal in small quantities at short intervals is discussed in a U. S. Bureau of Mines technical paper.1 Better combustion is obtained by this method in that the fuel supply is main tained more nearly proportional to the air supply. If the coal is of the caking kind, the fresh charge will fuse into one solid mass which can be broken up with the stoking bar and leveled from 20 min to one hr after firing, depending on the temperature of the firebox. Care should be exercised when stoking not to bring the bar up to the surface of the fuel, as this will tend to bring ash into the high temperature zone at the top of the fire, where it will melt and form clinker. The stoking bar should be kept as near the grate as possible, and should be raised only enough to break up the fuel. With fuels requiring stoking it may not be necessary to shake the grates, as the ash is usually dislodged during stoking. * It is acknowledged that it may be difficult to apply the outlined methods to domestic heating boilers of small size, especially when frequent attendance is impracticable. The adherence to these methods insofar as practicable, however, will result in better combustion. The output obtained from any heater with bituminous coal will usually exceed that obtained with anthracite, since bituminous coal bums more rapidly than anthracite, and with less draft. Bituminous coal, however, will usually require frequent attention to the fuel bed. Preventing Smoke In general, time, temperature and turbulence are the essential require ments for smokeless combustion. Anything that can be done to increase any one of these factors will reduce the quantity of sgioke discharged. Special care must be taken in hand-firing bituminous coals. Checker or alternate firing, in which the fuel is fired alternately on separate parts of the grate, maintains a higher furnace temperature and thereby decreases the amount of smoke. Coking and firing, in which the fuel is first fired close to the firing door and the coke pushed back into the furnace just before firing again, pro duces the same effect. . The volatiles as they are distilled thus have to pass over the hot fuel bed where they will be burned if they are mixed with sufficient air, and are not cooled too quickly by the heat-absorbing surfaces of the boiler. : Steam or compressed air jets, admitted over the fire, create turbulence in the furnace and bring the volatiles of the fuel more quickly into contact Fuels and Combustion 337. with the air required for combustion. These jets are especially helpful for the first few minutes after each firing. Frequent firings of small charges shorten the smoking period, and reduce the density. Thinner fuel beds on the grate increase the effective combustion space in the fur nace, supply more air for combustion, and are sometimes effective in reduc ing the smoke emitted, but care should be taken that holes are not formed in the fire. A lower volatile coal or a higher A.P.I. gravity oil always produces less smoke than a high volatile coal or low A.P.I. gravity oil used in the same furnace and fired in the same manner. The installation of more modem or better designed fuel-burning equip.ment, or a change in the construction of the furnace, will often reduce smoke. The installation of a Dutch oven, which wall increase the furnace volume and raise the furnace temperature, often produces satisfactory results. In the case of new installations, the problem of smoke abatement can be solved by the selection of the proper fuel-burning equipment and furnace design for the particular fuel to be burned, and by the proper operation of that equipment. Constant vigilance is necessary to make certain that the equipment is properly operated. In old installations the solution of the problem presents many difficulties, and a considerable investment in special apparatus is often necessary. Lower rates of combustion per square foot of grate area will reduce the quantity of solid matter discharged from the chimney with the gases of combustion. The burning of coke, coking coal, and sized coal from which the extremely fine coal has been removed, will not, as a general rule, produce as much dust and cinders as will result from the burning of non-coking coals and slack coals when they are burned on a grate. Modem boiler installations are usually designed for high capacity per square foot of floor space, because such designs give the lowest cost of construction per unit of capacity. Designs of this type discharge a large quantity of dust and cinders with the gases of combustion, and if pol lution of the atmosphere is to be prevented, some type of dust and cinder catcher must be installed. 's Firing Methods for Semi-Bituminous Coal The Pocahontas Operators' Association recommends the central cone method of firing, in which the coal is heaped on to the center of the bed forming a cone, the top of which should be level with the middle of the firing door. This allows the larger lumps to fall to the sides, and the fines to remain in the center and be coked. The poking should be limited to breaking down the coke without stirring. Grates should be rocked gently. It is recommended that the slides in the firing door be kept closed, as the thinner fuel bed around the sides admits the required air. Firing Methods for Coke Coke ignites less readily than bituminous coal and more readily than anthracite, and bums rapidly with little draft. In order to control the air admitted to the fuel it is very important that all openings or leaks into the ashpit be closed tightly. A coke fire responds rapidly to the opening of the dampers. This is an advantage in warming up the system, but it also makes it necessary to watch the dampers more closely in order to prevent the fire from burning too rapidly. In order to obtain the same interval of attention as with other fuels, a deep fuel bed always should be maintained when burning coke. The grates should be shaken only 338 CHAPTER 14 1956 Guide slightly in mild weather, and should be shaken only until the first red particles drop from the grates in cold weather. The best size of coke for general use, for small fire-pots where the fuel depth is not over 20 in., is that which passes over a 1 in. screen and through a lj in. screen. For large fire-pots where the fuel can be fired over 20 in. deep, coke which passes over a 1 in. screen and through a 3 in. screen can be used, but a coke of uniform size is always more satisfactory. Large sizes of coke should either be mixed with fine sizes or broken up before using. ' SECONDARY AIR When bituminous coal is hand-fired in a furnace, the volatile matter in the fuel distills off leaving coke on the grate. The product of combustion of the coke is COj and under certain conditions some CO may arise from the bed. The combustion of the volatile matter and the CO may amount to the liberation of from 40 to 60 percent of the heat in the fuel in the combustion space over the fuel bed. Fig. 1. Combustion of Fuel in a Hand-Fibed Fubnace . The air that passes through the fuel bed is called primary air, and the airthat is admitted over the fuel bed in order to.burn the volatile matter and CO is called secondary air. This process of combustion is illustrated in Fig. I.4 The free oxygen of the air passes through the grate and the ash above it, and bums the carbon in the lower 3 or 4 in. of the fuel bed forming carbon dioxide. This layer noted as the oxidizing zone, is indicated by the symbols CO% arid Oi- Some of the carbon dioxide of the oxidizing zone is reduced to carbon monoxide in the upper layer of the fuel bed, noted as the reducing zone and indicated by the symbols C02 and CO- The gases leaving the fuel bed are mainly carbon monoxide, carbon dioxide, nitrogen, and a small amount of free oxygen. Free oxygen is admitted through the firing door in an attempt to bum carbon monoxide, as well as the volatile combustible distilled from the freshly fired fuel. The division of the total into primary and secondary air necessary to produce the same rate of burning and the same excess air, depends on a number of factors which include size and type of fuel, depth of fuel bed, and size of fire-pot. Size of the fuel is a very important factor in fixing the quantity of second ary air required for non-caking coals. With, caking coals it is not so important, because small pieces fuse together and form large lumps. Fortunately, a smaller size fuel gives more resistance to air flow through Fuels and Combustion 339 the fuel bed, and thus automatically causes a larger draft above the fuel bed. More secondary air is drawn through the same slot openings, but, nevertheless, the smallest size of fuel will' require the largest second ary air openings. For certain sizes of fuel, no secondary air openings are required, and for large sizes, too much excess air may pass through the fuel bed. In general, the efficiency of domestic hand-fired furnaces and boilers burning either anthracite or bituminous coal, can be increased for an hour or two after firing, if some secondary air is admitted through the slots of the fire door. However, unless the slots are closed when secondary air is no longer beneficial, the decrease in efficiency during the remainder of the firing cycle, because of excess air, may more than offset the gain resulting from the secondary air at the beginning of the firing period. Unless the secondary air can be readjusted between firings, it is probable that a greater average efficiency will be obtained for domestic hand-fired devices by leaving the secondary air slots closed at all times. There is usually an appreciable amount of air leakage around the firing door and secondary air slots of domestic furnaces and boilers. When attention is given between firings, the efficiency of combustion can be raised appreciably by admitting secondary air over a bituminous coal fire, to. burn the gases and reduce the smoke. The smoke produced is a good indicator, and that opening is best which reduces the smoke to a minimum. Too much secondary air will cool the gases below the ignition point, and. prove harmful instead of beneficial. Secondary air that enters the combustion chamber too far removed from the zone of combustion, will also be harmful, because the oxygen in the secondary air will not react with any unbumed gases, unless the mixture is subjected to high temperatures. Draft Requirements for Coal and Coke Firing The draft required to effect a given rate of burning the fuel is dependent on the following factors: (1) kind and size of fuel; (2) grate area; (3) thick ness of fuel bed; (4) type and amount of ash and clinker accumulation; (5) amount of excess air present in the gases; (6) resistance offered by the boiler passes to the flow of the gases; and (7) accumulation of soot in the passes. Insufficient draft will necessitate additional manipulation of the fuel bed, and more frequent cleanings to keep its resistance down. Insufficient draft also restricts the control that can be accomplished by adjustment of the dampers. For draft requirements see Chapter 17. The quantity of excess air present has a marked effect on the draft required to produce a given rate of burning. If the excess is caused by holes in the fuel bed, or an extremely thin fuel bed, it is often possible to produce a higher rate of burning by increasing the thickness of the bed. The thickness of the fuel bed should not, however, be increased too much, because the increased draft resistance will reduce the rate of primary air supply and, the rate of burning. Draft Regulation for Coal and Coke Firing Because of the varying heating load demands present in most instal lations, it is necessary to vary the rate of fuel burning. The maintenance of the proper air supply for the various rates of burning is accomplished hy regulation of the drafts. Methods' of draft regulation used for solid fuel We shown in Fig. 2. The air enters through the ashpit draft door, firing 340 CHAPTER 14 1956 Guide door, and by leaks in the setting, whereas the gases leave only through the outlet. By throttling the gases with the damper in the outlet all the air entering by each of the three intakes is reduced in the same proportion, thus maintaining about the same percent of excess.air. If inlet air is con trolled by the ashpit draft door, the, air admitted through the ashpit is reduced, while it is increased through the other two intake openings, resulting in an increase of excess air. A considerable increase in the efficiency of hand-fired furnaces and boilers can be realized by regulating . the air supply by means of the damper in the outlet instead of the ashpit damper. Use of the ashpit damper is required, of course, for low rates of combustion. The cold air check damper is-to be- used only when chimney draft is excessive. It is normally closed unless closing of the Fig. 2. Methods of Draft Regulation in a Hand-Fibed Fubnace outlet damper and ashpit damper is unable to control the rate of combustion. Furnace Volume for, Coal and Coke The principal requirements for a hand-fired, furnace are that it shall have enough grate area and correctly proportioned combustion space. The amount of grate area required is dependent upon the desired combus tion rate. . The furnace volume is influenced by the kind of coal used. Bituminous coals, on account of their long-flaming characteristic, require more space in which to burn the gases of combustion completely than do the coals low in volatile matter. For burning high volatile coals, provision should be made for mixing the combustible gases thoroughly, so that combustion is complete before the gases come in contact with the relatively cool heating surfaces. An abrupt change in the direction of flow tends to mix the gases of combustion more thoroughly. Anthracite requires compara tively little combustion space. CLASSIFICATION OF FUEL OILS . Fuel oils are mixtures of hydrocarbons derived from crude petroleum by refining processes designed to produce suitable proportions of naphtha, gasoline, kerosene, fuel oil, and lubricating oil. The processes leaye a residue of coke, asphalt, or paraffin depending on the source of the crude oil. the past, refining processes have been directed toward producing the maxi mum amount of gasoline, because this product was in greatest demand. The relative proportions of gasoline and fuel oil produced, per unit volume Fuels and Combustion 341 of crude oil could be varied considerably to suit seasonal changes in demand or gradual trends from year to year. At present gasoline; represents about 43 percent and fuel oil (including kerosene) about 22 percent,of the yield from crude oil. Crude oil is distilled in towers at atmospheric pressure to produce gaso line, naphtha, kerosene distillates, arid colored distillates, and leave straight- run residues. The colored distillates are distilled further to produce fight distillate fuel oils, some lubricating oil, wax, etc., whereas the straight-run residues are distilled under vacuum to produce heavier distillates. The residual fuels remaining can then be passed through cracking plants to produce more gasoline, cracked kerosene, cracked distillates, and cracked residual fuel oils. The exact processes used depend on the proportions of the various end products!desired, and to some extent upon the composi tion and characteristics of the crude oil. ': Fuel oils may be described as straight-run fuels, thermally-cracked fuels, catalytically-cracked fuels, or blended fuels depending on the refining proc ess used to produce them. Straight-run fuels are those produced by distil lation under atmospheric pressure or a vacuum without decomposition of the hydrocarbons by cracking. Thermally-cracked fuels are those produced ' by a cracking^ process involving elevated temperatures. (850-1100 F) to decompose some of the heavier hydrocarbons. Catalytically-cracked fuels are those produced with the aid of an alumina-silica catalyst in the crack ing process at lower temperatures than those used for thermal cracking. Blended fuel oils are mixtures of any of the above three types. Over 90 percent of all No. 5 fuel oils are blended. There is no particular problem involved with the burning Of a blended oil providing it is blended from two oils which come from the same source. If the oils are not properly blended under heat or pressure, they will ex hibit a degree of instability in storage, resulting in sludge formation and a tendency to plug filters and atomizing nozzles in high pressure burners. This is especially true when the oil burning rate is 1 gpm or less. There is some evidence that the viscosity of blended oils is generally higher than for straight run fuels of the Same grade. The viscosity Of the oil can change the spray pattern such that smoking and pulsation may result. The adverse effects of high viscosity can be alleviated to a con siderable degree in high pressure burners by the use-of higher atomizing pressures. In all cases the pressure should be 100 psig or higher and in some cases pressures up to 150 psig have been used .to correct difficulties attributed to high viscosity oil. Analysis of Fuel Oils . Crude oil in its natural state contains primarily paraffin hydrocarbons (chemical formula Cnffsn+s, naphthene hydrocarbons (formula C,,/f2,,), and aromatic hydrocarbons (formula where n is a. whole number. Fuel oils produced by pure distillation, that is the straight-run fuel oils contain essentially these same hydrocarbons. Those produced by crack ing processes may contain generally all *the hydrocarbon series from CnH2n+2 to 2C,,f/ ,,_n, and especially do they contain appreciable percentages of the olefin hydrocarbons which are relatively less stable than theparaffin, napthene; and aromatic hydrocarbons," The paraffin hydrocarbons are hydrogen-saturated, are among .the 'most stable, and have the highest hydrogen-carbon ratio of any of the hydrocarbon series. The straight-run fuel oils have the highest paraffin content, the highest hydrogen-carbon ratio and are the most stable of the fuel oils. The thermally-cracked fuel Fuels and Combustion 343 oils have the lowest paraffin content while the catalytically-cracked fuel oils are intermediate in paraffin content and stability. The hydrogencarbon ratio of straight-run fuel oils ranges from 0.155 to 0.170, and in catalytically-cracked fuel oils ranges from 0.133 to 0.156, while it is some what lower for thermally-cracked fuels. ' The blending of straight-run oils with cracked oils is common practice to improve the paraffin content, stability, and ignition characteristics of fuel oils. A high paraffin content and a high hydrogen-carbon ratio are generally desirable characteristics for domestic fuel oils and consequently, the straight-run distillates are better suited to this use than the fuel oils produced by the various cracking processes. On the other hand, thermally-cracked fuel oils often have a lower pour point and a lower viscosity than comparable straight-run fuel oils. The color, and stability of cracked fuel oils can be much improved by treatment with sulfuric aicd, by neutralization, and by redistillation. Grade Classification of Fuel Oils * Fuel oils are most commonly classified by dividing them into grades in accordance with the Commercial Standard (CS12-48) entitled Fuel Oil published by the U. S. Department of Commerce. These specifications, given in Table-4, conform to ASTM Materials Tentative Specifications for Fuel Oils D 396 - 48 T. Oils may be classified roughly by specific gravity but it is not an adequate index of the suitability of an oil for a given purpose. Other characteristics of fuel oils which determine their grade classification in the Commercial Standard, and their suitability for given uses are the flash point, pour point, water and sediment content, carbon residue, ash, sulfur content, distillation characteristics, and vis - cosity. The flash point of an oil is important with regard to safety in storage and ease of ignition in systems employing automatic ignition. The distil lation characteristics determine whether or not the oil can be completely evaporated in some types of burners, and whether cracking will be likely to occur prior to combustion. A low pour point and low water content are desirable for outdoor storage in cold climates. Sediment, carbon residue, and ash should be low to prevent clogging of strainers and the accumulation of unbumed material in the burner. A low viscosity allows the fuel oil to flow through supply lines readily and to be broken up into small droplets in atomizing'type burners. The sulfur content is of importance because sulfur compounds corrode the burner and heating system or because un desirable compounds of sulfur may be formed in certain.industrial processes. Some of these characteristics of a fuel oil are required to lie within certain limits for each of the grades of fuel oil listed in Commercial Standard CS12-48. Some fuel oils do not fall into any of the grade classifications of the Commercial Standard because failure to comply with all of the re quirements of one grade does not automatically place the fuel oil in the next lower grade, unless it meets all of the requirements of the lower grade. By ultimate analysis the No. 1 and No. 2 fuel oils contain 84 to 86 per cent carbon, 12.0 to 13.5 percent hydrogen, one to three percent oxygen and nitrogen, and 0.5 percent or less of sulfur. The heavier grades of fuel oil, Nos. 4, 5 and 6, may contain as much as 88 percent carbon, as low as 11 percent hydrogen, and considerably more sulfur than is permissible in the domestic grades. Due to variation in the constituents of different fuel oils and the different refining methods used, the API gravities.and calorific values of the different grades of fuel oil cover a range in each grade with some overlapping 344 CHAPTER 14 1956 Guide between domestic grades and between commercial and industrial grades. The relation between the API gravity of fuel oils and their'calorific value is shown in Table 5. Grades No. 1 and No. 2 are used predominantly in domestic heating equipment whereas grades 5 and 6 are used in commercial and industrial burners. Grade 6 usually requires preheating to increase its fluidity and to permit atomization, whereas grade 5 is used in some burners without preheating. Grade 4 fuel oil does not require preheating and can be burned satisfactorily in a limited number of domestic burners. COMBUSTION OF FUEL OILS Many theories have been advanced during the past century to explain the mechanism of combustion of hydrocarbons in oil burners and other devices used for producing heat or light. These theories have been modi fied from time to time to agree with new experimental evidence. Much Table 5. Approximate Gravity and Calorific Value of Standard Grades of Fuel Oil Commercial Standard No. Approximate Gravity AJ>.I. Weight LB PER GALLON Calorific Value Btu Per Gallon i 35-45 7.076-6.675 138,800-132,900 2 26-40 7.481-6.870 144,300-135,800 4 12-25 8.212-7.529 153,000-145,000 5 10-23 8.328-7.627 154,600-146,200 6 8-17.5 8.448-7.909 156,000-149,700 still remains unknown about the process of decomposition and combustion of hydrocarbons. Only three theories will be discussed here: (1) the carbonic combustion theory, (2) the aldehydeous combustion theory, and (3) the chain reaction theory. The carbonic combustion theory postulates that thermal destruction of hydrocarbon molecules is likely to occur if (1) the oil is suddenly exposed to intense heat without allowing time for previous evaporation, (2) the oil and air are inadequately mixed, and (3) there is no preheating of the air or mixture. According to this theory the hydrocarbons would be thermally decomposed into hydrocarbons of lower molecular weight along with some free carbon atoms released under the conditions just described. The free carbon atoms may produce smoky combustion while those carbon atoms that are oxidized to carbon dioxide will produce a yellow luminous flame. The aldehydeous combustion theory is based on the evidence that alde hydes, alcohols, and possibly peroxides are formed as intermediate products when hydrocarbons are decomposed and oxidized to the final products of combustion. The formation of formaldehyde is certain since it can be identified in the flue gases from blue flame oil burners when insufficient combustion air is provided. Alcohols have been identified by certain in vestigators during the oxidation of methane and ethane. Aldehydeous combustion is illustrated by the blue flame oil burner and the conditions conducive to this type of hydrocarbon decomposition consist of (1) allowing the oil time and opportunity to evaporate completely prior to combustion, (2) mixing the air and oil vapor thoroughly before combustion, and (3) pre heating the air or the mixture. Blue and yellow flame combustion can be demonstrated by the apparatus Fuels and Combustion 345 illustrated in Fig. 3. If methane is burned in an atmosphere of air, as in burner A, a yellow flame will result, whereas the introduction of the air for combustion in the center of a stream of methane, as in burner B, will result in blue flame combustion. As the center of the flame in burner A is exposed to intense radiation the methane is thermally decomposed and liberates carbon particles which emit a yellow luminous flame during oxida tion. In burner B the center of the flame cone is filled with air which can not decompose under heat, the methane gas at the zone of contact with the air is only moderately heated because of outward radiation, and the air is preheated in the center as it approaches the flame; each of these conditions tend to produce aldehydeous combustion. It is probable that the chain reaction theory is an extension of the alde hydeous combustion theory since most investigators who have studied the former have observed that the formation of aldehydes is one of the steps in the combustion process. It has been well established that fuel oils Fig. 3. Illustration of Blue and Yellow Flame Combustion must be gasified before combustion can occur, and that molecules of a hydrocarbon and oxygen do not combine directly with each other to form carbon dioxide and water vapor, but pass through intermediate reactions in the process. Lewis and von Elbe,6 Pease, and others6 have advanced the theory that the reactions between hydrocarbons and oxygen are probably chain reac tions. This theory postulates that a great many different reactions take place simultaneously or progressively between molecules, atoms, and radi cals in a mixture of hydrocarbons and oxygen. Some of these reactions produce particles or substances that tend to accelerate the reactions while others tend to slow down the process. Also, temperature, pressure, light and certain catalytic agents all may affect the speed and nature of these processes. The kind of intermediate products formed before combustion is complete depends on the physical conditions mentioned, as well as the molecular structure of the particular hydrocarbon participating in the re action. Aldehydes, methyl and ethyl alcohols, formic acid, and other substances, have all been identified as intermediate products in certain reactions. The chain reaction theory, in reality embraces and elaborates on the aldehydeous combustion theory. Oil Burning Indexes . A number of indexes have been used, or proposed, as an indication of the burning qualities of fuel oils based on one or more physical measure ments made on the oil. These may be summarized as follows: 346 CHAPTER 14 1956 Guide A. Indexes based on a single physical test: (1) API gravity7, (2) Aniline point', (3) Institute of Petroleum smoke test, (4) Carbon-Hydrogen ratio leased on flue gas analysis or ultimate analysis, and (5) Percent aromatics determined by sulfuric acid absorption tests'. B. Indexes based on two or more physical tests: (1) Diesel index' based on API gravity and aniline point, (2) Institute of Petroleum cetane number 10 based on the API gravity and 50 percent distillation point, (3) Universal Oil Products characteri sation factor11 based on specific gravity and average boiling point, (4) Burning index" based on API gravity and 50 percent distillation point, and (5) Estimated CarbonHydrogen ratio1' based on API gravity aniline point, and boiling point. Various investigators have shown correlation between one or more of these indexes and the performance of fuel oils in oil burners. Experiments 60Smote Spot Reflectance tor % ot UUimote CO*. 0 80Per Cent, of Ultlmote C t tor % Relollve Retlectonce rr4* U 5O O za: *- )' 1 k '"S CO* OO u. u r Sm>oke W bJ !s> St 0 5 O..0O 30 35 40 API GRAVITY rff r*" CO* mo e ft 1 0.12 0.13 - 0.14 0.15 0, HYDROGEN-CARBON RATIO 20 4Q 60 DIESEL INDEX f0 rt / 7\ 7 N-S Aid CO* Sm >ke 80 BURNING INDEX * I- o O CD CL CO (K til OU. 100tOO-1- Fig. 4. Correlation of Burning Qualities of Fuel Oils with Four Combustion Indexes conducted with the Oil Heal Institute Reference Test Unit" indicated good correlation between the smoking tendency of fuel oijs and API gravity, burning index, Diesel index, and hydrogen-carbon ratio for a limited num ber of oils in laboratory apparatus simulating a pressure-atomizing burner. These results are shown graphically in Fig. 4. Smoking tendency is given here in terms of smoke spot reflectance, the light reflectance of a smokesoiled filter paper. A high reflectance, relative to a clean filter paper, indicates low smoking tendency. CO2/U is the observed CO2 divided by the ultimate or maximum theoretical C02 expressed as a percentage. Reid and Hersberger12 have related burning qualities and burning index for various oils in a wall-flame burner. Cauley and Delgass13 cite test results on combustion indexes obtained with vaporizing burners. The present experimental data are probably too meager as yet to correlate adequately any one of these indexes with burning qualities of oil fuel for all types of burners. Few attempts have been made to suggest limits for any of these Fuels and Combustion 347 fuel oil indexes for particular applications, even though correlations be tween them and burning qualities have been observed. In other words, none of the above mentioned indexes has yet gained sufficiently wide usage to replace the grading of oils by Commercial Standard CS12-48. Experiments have shown that thermal decomposition or cracking of hydrocarbons begins at a temperature of approximately 680 F at atmos pheric pressure, although the temperature of cracking varies somewhat above and below this value. Thus pure distillate fuel oils, whose end point does not exceed this temperature, can usually be completely evaporated in vaporizing-type oil burners at atmospheric pressure without leaving a residue or without cracking of the hydrocarbons. Fuel oils that cannot be completely evaporated below 680 F are likely to undergo cracking in vaporizing type burners, with the resulting possibilities of smoky combus tion and residues in the oil burner. A complete distillation curve cannot usually be determined for fuel oils containing fractions that evaporate above 680 F. Since No. 1 grade fuel oil in Commercial Standard CS12-48 has a maxi mum end point of 625 F, it can in most cases be completely evaporated in atmospheric vaporizing burners without cracking, although occasionally an oil is found that undergoes cracking at temperatures below 625 F. By the same criterion, No. 2 grade fuel oil in the Commercial Standard, which can have a maximum distillation temperature of 675 F at the 90 percent point, would frequently be cracked in a vaporizing burner. How eVer some No. 2 fuel oils do not crack before complete evaporation takes place. Vaporizing-type burners can generally use only No. 1 fuel oil with assurance that thermal decomposition will not occur during combustion. On the other hand either No. 1 or No. 2 fuel oils may be employed in high or low pressure atomizing burners when the temperatures developed in the combustion chamber are high enough to assure complete combustion, even if the fuel oil is thermally decomposed. In vaporizing burners, preheating of the combustion air and fuel, com plete evaporation of fuel before it is exposed to intense heat, and thorough mixing of the air and gasified fuel promote complete combustion without smoke and with a minimum of excess air. In pressure-type burners pre heating of the combustion air, a maximum of air turbulence, good atomiza` tion of the fuel, and high combustion chamber temperatures (preferably red hot) promote smokeless combustion with a minimum of excess air. Natural draft burners depend on the motivating force of a chimney to induce enough air into the burner for complete combustion. Forced draft burners are supplied with combustion air by means of a blower or fan; the chimney merely conducts the flue gases outdoors and prevents leakage of flue gases inside the building. More details on the operation of the different kinds of oil burners and on chimneys and draft will be found in Chapters 15 and 17 respectively. FUEL GASES Fuel gases employed for various heating and air conditioning processes throughout the United States fall into three broad classifications: natural, manufactured, and liquefied petroleum. Natural gas is a mixture of several combustible gases and, usually, a small percentage of inert gases obtained from geologic formations. Natural gas is produced in significant amounts m 20 states. Texas is by far the largest producer, followed by Louisiana, Oklahoma, California, Kansas, and West Virginia. Manufactured gas is made by the distillation or cracking of oil or coal, by the steam carbon 348, CHAPTER 14 1956 Guide Fuels and Combustion 349 ojo-h.oioa5ot>-QO .2 < 1 C4 t"- <0 h- reaction, or by combinations of these processes. Liquefied petroleum gases (propane and butane) are higher hydrocarbon gases normally obtained as a by-product of oil refineries or by stripping natural gas. These two com pounds are generally gaseous under usual atmospheric conditions although they can be liquefied by the application of moderate pressures at normal temperatures. . The demand for gaseous fuels has increased so tremendously during the past 25 years that few cities now can be said to depend solely on one source of supply. During peak load periods, heating demands on natural gas distribution systems may necessitate augmenting the base supply with supplemental fuels such as high Btu oil gas or liquefied petroleum gasair mixtures. The supply of manufactured gases may be similarly increased by adding natural gas, reformed refinery gases, or relatively low heating value mixtures of liquefied petroleum gas and air. In American gas practice the heating value of a gas and appliance effi ciencies are based on the gross heating value. This value is the number of Btu liberated by complete combustion, at constant pressure, of one cubic foot of gas saturated with water vapor and measured at 60 F and 30 in. of mercury, with air at the same temperature and pressure. Products of combustion are cooled to the initial temperature of the gas and air and the water formed by combustion of free and combined hydrogen is condensed to the liquid state. T a b l e 6. T y p ic a l G as A n alyses Constituents of G as-P ercent by Volume Classification of Gases Representative properties of gaseous fuels commonly employed for do mestic heating processes are shown in Table 6.15> 16 17 18 ' Natural gas contains from- 55 to 98 percent methane with various per centages of higher hydrocarbons, chiefly ethane. In addition to these components, small quantities of non-combustible gases such as carbon dioxide, nitrogen, and helium are sometimes present. Percentages of the . different components vary with the area from which natural gas is with drawn. They may even vary slightly from any given well during its lifetime but these variations are inconsequential insofar as the utilization of the gas is concerned. Heating values of natural gases vary from 900 to 1400 Btu per cu ft but the usual range for use is from 1000 to 1050 Btu (gross) per cu ft. A typical analysis is given in Table 6. Manufactured gases commonly produced are listed in Table 6. Gross, or higher, calorific values of typical send-out gases made from these, manu factured gases generally range from 500 to 600 Btu per cu ft. Due largely to the greatly increased demand for city gases the tendency during recent years has been to increase rather than to decrease heat content of manu factured gases, thus making it possible to serve more customers through the existing distribution system. . Mixed gases are a result of increased distribution of natural gas, through transcontinental transmission lines, into areas having existing manufac tured gas facilities^ In such instances some gas companies supply a 600 to 800 Btu mixture (See Table 6). In some territories these mixtures are distributed as an intermediate step in changing oyer from manufactured gas to natural gas. Although the burden of adjusting installed heating and air conditioning equipment and supplying new orifices and burner equipment is generally assumed by the gas companies when the gas is changed, it is,advisable to consult the local gas company to insure that equipment is provided with proper orifices and burners when installed. Most states enforce legislation through their public service commissions 350 CHAPTER 14 1956 Guide to require delivery of a gas of specified average or minimum heating value within their respective limits. Any given heating value within reason fortunately may be maintained and yet permit considerable latitude in the composition of the gas distributed. Hence the constituents of city gases are not necessarily the same in different districts nor even at succes sive stations in the same district. In every community, however, the objective is to maintain variations in composition and gas pressure within limits which will provide satisfactory operation and performance of all common types of gas burning equipment. Liquefied petroleum gases, such as propane and butane or mixtures thereof have calorific values ranging from 2500 to 3200 Btu per cu ft. These fuels are often supplied as liquids under pressure in tanks or bottles. In such cases the liquid evaporates when pressure is relieved, the heat neces sary for vaporization being obtained from the surrounding air or ground. As butane boils at 32 F some provision is necessary, for maintaining the gas above this temperature or for lowering the partial pressure by dilution if the gas is utilized in colder climates. Propane, with a boiling-point of --40 F, may be served in localities where temperatures substantially below freezing are encountered. When employed for heating purposes, these gases are usually stored in high pressure tanks and delivered by tank truck in much the same manner as fuel oil. Both gases, mixed with air, or in undiluted form, are also extensively employed by gas companies to aug ment their base load supplies during peak load periods. In some smaller communities, where gas manufacturing plants are not economically feasible and natural gas is unavailable, liquefied petroleum gases or liquefied petro leum gas-air mixtures are supplied through mains in much the same manner as manufactured or natural gas. COMBUSTION OF GASEOUS FUELS Gas burners employed in domestic heating appliances are generally of the non-luminous flame or Bunsen type. Part of the air required for com bustion is inspirated as primary air into the burner mixing tube where it mixes with gas, and then takes part in combustion at the burner ports. As the amount of primary air is seldom sufficient to support complete com bustion, additional air is supplied to the burner flames around the periphery of its ports. This secondary air is induced into the appliance and around the base of each separate burner flame by force of the issuing mixture of gas and primary air and by draft inspiration inherent in the heat of the flames. If a Bunsen type burner is properly adjusted, its flames will generally have a clear, blue appearance. Yellow flames are indicative of insufficient primary air supply, and possibly of incomplete combustion. An appreciable updraft is seldom, if ever, present even in. flue-connected gas heating appliances, because most appliances of this kind are equipped with a draft hood which reduces the chimney draft at the appliance. It is important to note that gas furnaces and boilers, as well as most other classes of heating equipment, are designed to create their own draft. The air-to-gas ratio in a Bunsen burner head has a decided effect on the rate of flame propagation. The gas-air mixture must flow from the burner ports faster than the flame bums, otherwise flashback will occur. The flashback condition normally results either from an excess amount of primary air or insufficient gas or both. Conversely, the velocity of the issuing mixture must not be so high that the flame will be blown from the ports, a condition known as lifting. Fortunately, contemporary types of such burners have a rather wide range of flexibility in capacity and aajust- Fuels and Combustion 351 ment. In addition to this characteristic, gas supply is normally so uni form that if a gas heating appliance is properly adjusted when it is installed, its burners, with occasional cleaning, should provide trouble-free service for years. When problems incident to changeover of the gas supply are involved, they are generally assumed by the local utility providing the supply of gas. It should be recognized that a change in fuel gas will change the operating COs value. For example, an appliance operating on carburetted water gas at 20 percent excess air will have 14.2 percent COi in the flue gases. If a change is made to coke oven gas at the same gas in put rate, with the excess air maintained at 20 percent, the operating COj would drop to 9.2 percent. Luminous flame burners are occasionally used in central heating gas ap pliances. With these devices all air required for complete combustion is supplied to the flames as secondary air. Two fundamental advantages of this type of burner are that the possibilities of flashback are eliminated, and that a much higher gas velocity 'is needed to blow the flames off the ports. On the other hand, if there is any appreciable amount of flame impingement on any portion of the heating surface, or if secondary air is not effectively supplied to the flames, .soot may be formed and also com bustion may be incomplete. In some types of gas burners radiant baffles are used to convert part of the energy formed during the process of combustion to radiant heat. These .baffles may also serve to direct the flow of products of combustion along the heat-absorbing surface. . Gas designed furnaces and boilers approved by the American Gas Asso ciation "are certified for operation at the rating shown on the nameplate. Considerations relating to safety, performance, and service life, require that such appliances be adjusted at inputs which do not exceed the name plate input rating. These' appliances normally draw in from 20 to 50 percent excess air, depending on the type and general design. As has been indicated, some excess air is necessary to insure complete combustion at all times and also to provide a reasonable degree of flexibility in performance. Various types of appliances used for gas space heating purposes are described in Chapter 15. ' Care must be exercised to insure adequate air supply for combustion equipment installed in buildings or other structures. Where the equip ment is closely confined, as in closets or small furnace or boiler rooms, the air supply must also provide for ventilation. Current recommended prac tices are: 1. Where the equipment is not closely confined (typical cellar installation or equiv alent) provide not less than 1 sq in. of free access to outside air for each 1000 Btu per hr heat release of fuel consumed. Infiltration into conventional frame or brick construction, unless unusually tight with storm windows and tight doors, provides adequate air. , 2. Where the equipment is closely confined, provide two openings to outside air or from spaces freely communicating to the outside. One opening should be near the top of the equipment enclosure and the other near the bottom. Each opening should have not less than -i sq in. of free area for each 1000 Btu per hr heat release of fuel burned, and should communicate to air source or outside by suitable ducts. Where the enclosure is in a building of otherwise conventional construction, and the air source will be the normal infiltration into building, each opening shall have not less than 1 sq in. of free area for each 1000 Btu per hr heat release. 3. Clearances from equipment to closely confining enclosures should conform to local codes and to standards listed by recognized agencies such as AGA Testing Lab oratories'* and Underwriters' Laboratories.'0 See Fig. 5 for details concerning installs- TOTAL LOSS IN FLUE GAS )N PER CENT 352 CHAPTER 14 1956 Guide tion of gas burning equipment.1 * For installation of equipment burning other types of fuel, refer to the National Building Code of the N.B.F.U. 4. Certain additional precautions may be required for certain fuels (such as un diluted liquefied petroleum gas) and consequently provisions of local codes and other authoritative agencies should be followed. FUNDAMENTAL PRINCIPLES OF COMBUSTION Regardless of the type of fuel under consideration, its combustion results in the production of gaseous products. Many kinds of solid fuels contain minerals which'cannot be burned and are therefore left as a residue com monly called ash. Moreover, unless sufficiently high temperatures are employed and an ample supply of oxygen properly distributed is present, Fuels and Combustion 353 - F . 5. Antig Illustration Showing Openings Necessary to Supply Air fob Combustion When Appliance is Installed in Confined Space ' A. Ventilating air outlet register for furnace room, I sq in. free area for each 1000 Btu per hr furnace input located above relief opening of draft hood. Register must not be blocked by drapes or other furnishings. B. Both registers must either face same large ventilated interior space or extend to such space by means of ducts. Vertical.distance C/L to C/L of registers should be not less than ft. - C. Suggest room access door be not less than 6 ft high by a width sufficient to provide for installation or removal of furnace. At least 2 ft horizontal clearance should be provided in front of furnace when closet door is open, or 18 in. when door is closed. D. Combustion and ventilation air inlet register for furnace room, 1 sq in. free area for each 1000 Btu per hr furnace input, located at or below combustion air inlet to furnace. Register must not be blocked by drapes or other furnishings. E. Air circulated by furnace must be handled by ducts which are sealed to furnace **rring and are entirely separate from means provided for supplying combustion and ventilation air. F. Spacing between draft hood and wall at least 6 in. (unless approved for closerspacing). If flue products may be directed toward wall, 12 in. spacing recommended. G. No part of furnace casing closer than 6 in. to wall (unless approved for closer spacing). . * H. Flue should terminate above peak of roof,and above nearby walls to assure satisfactory flue perform ance. In installations where the flue terminal is below nearby walls or roof peaks, an effective vent cowl should be used. the combustible constituents of solid, liquid, and even gaseous fuels can not be completely burned. Incomplete or partial combustion of all fuels produces toxic gases, such as carbon monoxide, with smaller quantities of aldehydes, ketones, and other hydroxylated hydrocarbon compounds. This fact indicates that, while combustion processes involving common types of fuel may be regulated by experienced operators to produce the most efficient results, normal combustion processes can be so unbalanced as to createhazards unless both design and operation are planned with a knowl edge of the fundamental principles of combustion. Combustion may be defined as the chemical combination of a substance with oxygen resulting in the evolution of heat, and usually some light. The rate of combustion depends upon the rate of reaction of the substance with oxygen, upon the rate at which oxygen is supplied, and upon the tempera- TOTAL LOSS in FLUE GAS IN PER CENT Anthracite ' Fuel Oil Fig. 6. Flub Gas Losses with Vabious Fuels1 Flue Gas Temperature Shown. Loss is Based on 65 F Room Temperature. 354 CHAPTER 14 1956 Guide ture obtained due to surrounding conditions. This is combustion in its simplest form. All solid, as well as liquid and even gaseous fuels generally contain several combustible elements in combination with others which, depending on their nature, affect oxygen requirements and thus govern the combustion process. For a continuous reaction, as in heating processes, it is necessary to establish an effective balance between rates of removing heat and of supplying fuel and air or oxygen to keep the reaction going. In establishing such a balance, consideration must be given to the removal or venting of products of combustion, so that the entire process is one of flow wherein draft conditions in the combustion space are important. Complete combustion is obtained when all combustible elements in a fuel are oxidized by all of the oxygen with which they will combine. All oxygen or air supplied is generally not utilized, and this excess portion is commonly referred to as excess oxygen or excess air. Excess air is usually expressed as a percentage of the of air required for perfect combustion. Perfect combustion results when the exact amount of oxygen required for complete combustion of all elements of a fuel is supplied and utilized. The percentage of carbon dioxide contained in the products of combustion from such a reaction is obviously the maximum attainable and is referred to as the ultimate CO2 or maximum theoretical percentage of carbon dioxide. This condition of perfect combustion, without having excess air or oxygen left from the reaction, is seldom, if ever, realized in practice. Most types of heating equipment must be sufficiently flexible in performance to pro vide complete combustion with not only variations in the quality of a fuel but also changes in the rate at which it is supplied. This situation makes it advisable, from a practical standpoint, to insure complete combustion but not perfect combustion in the sense expressed above. To attempt to do so would undoubtedly result eventually in unsatisfactory performance especially from a safety standpoint. Consequently, common types of heating equipment are usually designed, installed, and adjusted to operate with some excess air. The exact percentage of such air depends on the type of fuel being utilized, as well as anticipated variations in its quantity and quality. Despite these practical limitations, however, it should not be inferred that common types of fuels cannot be utilized economically. Reference to flue loss charts such as Figs. 6 and 7 for gas burning equip ment and to the air requirements discussion in Chapter 15 shows that reasonable quantities of excess air can be used without appreciable reduc tions in operating efficiencies. Oxygen combines with the combustible elements and compounds of any fuel in accordance with fixed laws. The reactions and resultant products of perfect combustion of common fuel constituents are set forth in Table 7. All of the oxygen required for combustion is normally obtained from the surrounding air, which is a mechanical mixture of nitrogen and oxygen with small amounts of carbon dioxide, water vapor and inert gases. For prac tical combustion calculations, air is considered to consist of 20.9 percent oxygen and 79.1 percent nitrogen by volume, and 23.15 percent oxygen and 76.85 percent nitrogen by weight. The nitrogen, being inert, passes through the reaction without change. Table 7 gives the air quantities corresponding to the oxygen required for perfect combustion. Air supplied to the combustion reaction is in most instances introduced in two ways. Primary air is introduced through or with the. fuel, and secondary air is supplied to the flames issuing from the fuel. Incomplete combustion is obtained when any of the combustible elements are not completely oxidized in the combustion reaction. This condition Fuels and Combustadn 355 not only represents inefficient use of the fuel but also presents a hazard because carbon monoxide is usually one of the products of incomplete combustion. For example, a hydrocarbon may not oxidize completely to carbon dioxide and water, as indicated in Table 7, but may also form al cohols, ketones, aldehydes, or carbon monoxide depending on where and. how the reaction is interrupted. Too low a temperature (such as may be caused by flame impingement on a cold surface), a poor oxygen supply to the flames (due to insufficient or poorly located air supply, or smothering %co, % EXCESS AM IN FLUE % EXCESS AIR . %COl IN FLUE GASES j ui 8 XQ__ %flue LOSS ui u. t <5 -i o * -10 Adapted from American Gas Association Laboratories Fine Loss Charts. Fig. 7. Alignment Chart for Calculation of Flue Losses for Butane, Propane, Coke Oven, and Natural Gases by products of combustion not properly vented), or insufficient mixing of the air and fuel, are the primary causes of incomplete combustion. Heat of Combustion As previously stated, the process of combustion results in the evolution of heat. The heat generated by the complete combustion of a unit of fuel is constant for a given combination of combustible elements and com pounds, and is known as the heal of combustion, calorific value, or healing value of the fuel. The heat of combustion of the several substances found in the more common fuels is given in Table 7. The calorific value of a fuel may be determined either by direct measure ment of the heat evolved during combustion in a calorimeter, or it may be computed from the ultimate analysis and the heat of combustion of the several chemical elements in the fuel. When the heating value of a fuel is determined in a calorimeter, the water vapor is condensed and the latent heat of vaporization is included in the heating value of the fuel. The heat- 356 gg MSH |3 3 g3oa 2Q * 2 g*N *** D CHAPTER 14 1956 Guide 111 I III I :'".;". ^ '; 05 C5 C5 CO. C5 CO V0v0i0v0 0*0 C5 C5 CO CO -H 1-H <N oo j-* TjH '(> . to .*& lO Ifl "5 05 r- C5 co ^ O ^ t' eo co co co r- co oo o CO VO cO VO co .co co.eo co jg S lI I f (0M5 ^09 Iios* Tt* vo 05 00 to CO 05 oo o O O O 1-t CO 05 05 05 ...05 <M 05 C5 VO Ss C5 C5 05 C5 .--I CO O O co O cO 00 co co vo r-i ( j--t *--i --i 05 C5 C5 05 -S C5 05 CO 00 OO 05 05 co co oO os" i <4 i A 05 vo 05 05 O VO 05 00 05 C5 2. a 8 S 5S oga 0 O 05 05 1 O o +'+' + oo 05 05 . CO o o d 05 + oo oo o + a ,+ oo Do o VO) +05 .+ d d o d o d CO + o o n d ++ O 05 o o So5J CO d 05 4* + +' d o d d o eo a ,.o d +VO + "t d. ^ d d d d. 05 05 d I 1 till d ^ *5c 553 - co &; tc oooos?^o.c5 *2 'x o &Q -a . c3 a ~qj o <U to Mt a eS o 3 Xfl >> *r o -S co W-*s>= HX.*3* **3KL. 'O W> a. 3 o Fuels and Combustion 357 ing value so-determined is termed the gross or higher heating value, and this is what is ordinarily meant when the heating value of a fuel is specified. In burning the fuel, however, the products of combustion are not cooled to the dew-point and the higher heating value cannot be utilized. When combustion is complete, the carbon in the fuel unites with oxygen to form carbon dioxide, COi, the hydrogen unites with oxygen to form water vapor, H2O, and the nitrogen, being inert, passes through the re action without change.. When combustion is incomplete, some of the carbon may unite with oxygen to form carbon monoxide, CO, and some of the hydrogen and hydrocarbon gases may not be burned at all. When carbon monoxide or other combustible gases, are present in the flue gases, there is a loss of heat produced per unit of :fuel consumed, and a lower combustion efficiency is obtained. Incomplete combustion may result from any or all of the following three conditions: (1) inadequate air supply, (2) insufficient mixing of air and gases, and (3) a temperature too low to produce ignition or maintain combustion. AIR REQUIRED FOR PERFECT COMBUSTION Air requirements for combustion of solid and liquid fuels are ordinarily expressed in pounds. On the other hand similar, requirements for gaseous fuels are usually^ stated on a cubic foot basis. For solid and gaseous fuels this method of treatment corresponds to the standards of measurement commonly employed by these two industries. The weight of air required for perfect combustion, per pound of solid or liquid fuel may be calculated after substitution of the proper percentages by weight of the various elements obtained from an ultimate analysis of the fuel in Equation 2. For gaseous fuels see Equation 3 for volume of air required. - / Solid or Liquid Fuels: . - . . .. 34.56 fC (- 0\ S' Pounds air required per pound fuel =----- -- + I H -- -- 1 + - ' 100 3 \ 8/0 (2) For Gaseous Fuels: - Cubic feet air required per cubic foot gas = 2.39 (CO + 7/2) + 9.53 CH4 + 16.68 CiHt + 23.82 CJh + 30.97 CtH10 + 11.91 CiHt + 14.29 CtHt + 7.15 H2S -- 4.78 Os.+ 30.47 UluminantB (3) Gaseous fuels may contain a wide variety of components classified as illuminanls, which are not separated by the usual methods of gas analysis. The principal ones in addition to ethylene and acetylene which are included in Equation 3, with the air required per cubic foot of gas are: propylene, 21\44; butylene, 28.58; pentene, 35.73; benzene, 35.73; toluene, 42.88; and xylene, 50.02. Since toluene and xylene are normally scrubbed from the gas before distribution, they may be disregarded in computing air. required for a fuel gas. An approximate value of 30.47 (as shown in Equation 3) may, therefore, be employed. If ethylene and acetylene are included as illuminanls, it is suggested that the value 19.65 be used. If it is desired to make the gas calculations on a weight basis the equation is expressed as follows: Pounds air required per pound fuel = 2.47 CO + 34.34 Hs + 17.27 CH, + 16.12 C\H, + 15.70 C,H, + 15.49 CJIi0*+ 13.30.Cjff, +. .. (4) 14.81 CtH, + 6.10 HS - 4.32 0. 358 CHAPTER 14 1956 Guide Where approximate results only are desired, values appearing in Table 8 may be substituted for Equations 2, 3, and 4; or the air required for perfect combustion may be estimated by assuming that 0.9 cu ft air is required per 100 Btu of fuel. Where extreme precision is involved it is suggested that the reader refer to scientific literature published on the subject of combustion and related topics by the various industries concerned. If approximate values for the oretical air requirements suffice, or if complete information on the fuel is not available, the following values should also be found helpful: 1. Solid Fuels (Pounds air per pound fuel). Anthracite, 9.6; Semi-Bituminous, 11.2; Bituminous 10.3; Lignite 6.2; and Coke 11.2. Table 8. Approximate Aik Requirements for Theoretically Perfect Combustion of Fuels* OF Fuel Ain Required fob Perfect Combustion Lbs per Lb Fuel Cu Ft per Unitb Fuel ApproxiMATE. Pbeci- Pek Cent Exceptions . Solid Btu per lb X 0.00073 Btu per lb X 0.0097 Liquid Btu per lb X 0.00071 Btu per lb X 0.0094 Gas Btu per lb X 0.00067 Btu per cu ft X 0.0089 3 Fuels containing more than 30% water 3 Results low for gasoline and kerosene 5 Gases of 300 Btu per cu ft or less * Values in table taken from page 270 of Gaseous Fuels, 1948, published by American Gas Association. b Units for solid and liquid fuels in pounds, for gas in cubic feet. 2. Fuel Oil (Pounds air per gallon): Commercial Standard No. 1, 102.6; No. 2, 105.5; No. 5, 112; No. 6, 114.2. 3. Gaseous Fuels (Cubic feet of air per cubic foot): Natural, 10.0; Mixed Natural and Manufactured, 8.0; Manufactured, 4.7, Propane, 23.8, Butane, 31.0. COMBUSTION EFFICIENCY FROM THE FLUE GAS ANALYSIS Excess Air A commonly employed index of efficiency of combustion is the relation existing between the amount of air theoretically required for perfect com bustion and the amount of air actually supplied. Since the difference between air supplied for combustion and theoretical air required is charac terized as excess air, its percentage may be calculated by use of the follow ing equation, Percent excess air Air supplied -- Theoretical air^ c Theoretical air X 100 j (5) The amount of dry air supplied per pound of fuel burned may be obtained from Equation 6 which has reasonable precision for most solid and liquid fuels. Values for CO,, CO and N, are percentages by volume from the flue gas analysis, and C is the weight of carbon burned per pound of fuel, cor rected for carbon in the ash. 3.04N, Pounds dry air supplied per pound of fuel .= (CO, + CO) X C (6) Because excess air calculations are almost invariably made from Orsat Fuels and Combustion 359 analysis results, and theoretical air requirements are not always known, another convenient method of expressing the relation , of Equation 5 is as follows: 100(0, -CO/2) Percent excess air = N, X 0.264 -- (O, -- CO/2) (7) As measurement standards for gaseous fuels are almost universally ex pressed in cubic feet, Equation 8 may be employed for computing excess air on a percentage basis for gases.21 ., where Percent excess air (U - CO,) X 100 7 CO, A (8) U = ultimate carbon dioxide, percent of flue gases resulting from perfect com bustion. . CO, = carbon dioxide content of flue gases, percent. P = dry products from perfect combustion, cubic feet per cubic foot of gas burned. .. A <= air theoretically required for complete combustion, cubic feet per cubic foot oFgas'burned.. . As the ratio of P/A is approximately 0.9 for most city gases, a value of * p. ... 90 may be substituted lor 100 j in Equation 8 for rough , calculation. Carbon-hydrogen ratios of different fuels vaiy considerably, hence the maximum -or ultimate CO, attainable also varies. Where they are un known, theoretical maximum CO, values,may be calculated from a flue gas analysis by use of Equation 9. : ;. , Maximum theoretical %,, C,,O,,, = % CO, in flue gas sample X -------- --- --.------ - - 100 ^ 70, in same sample\ "V 0.21 / (9) Approximate maximum CO, values for perfect combustion of several common types of fuel are shown in Table 9 together with values of CO, that will be attained with different amounts of excess air. Desirable values to be attained in practice depend upon the fuel, the method of firing, and other considerations. In general, fuels burned in suspension, such as gas, l and pulverized coal, can be burned with a lower amount of excess air than fuels burned on grates. To produce heat efficiently by burning any common fuel a number of basic requirements must be met: (1) adequate heat absorbing surface of proper shape and construction is necessary in the appliance, (2) heat trans fer surfaces must be clean, (3) a minimum amount of excess air must be present, (4) air employed for combustion and combustible gases must be properly mixed, and (5) flue gas losses must be reduced to a safe minimum. If insufficient heating surface is employed, or if heat transfer surfaces are covered with soot, ash, or scale, flue losses will generally be excessive due to the large amount of sensible heat escaping to the chimney. Too much excess air dilutes flue gases excessively and increases sensible flue gas loss. On the other hand, a deficiency of excess air will in all probability cause incomplete combustion, and some of the combustible gases will pass from the appliance without being completely burned. Highest combus- 360 CHAPTER 14 1956 Guide fcion efficiency is not always obtained when sufficient excess air is supplied to eliminate incomplete combustion entirely, because the air supply must not only be adequate but also be properly mixed with the combustible gases. Even with appliances connected to an effective flue every reason able precaution should be taken to insure as complete combustion as possible at all times. This is of vital importance in unvented equipment such as a gas space heater, for example. It is considered good practice to supply from 20 to 50 percent excess air, the exact amount depending on.the kind of fuel burned and especially on the type of equipment in which it is utilized; Flue Gas Analysis As radiation, convection, and conduction losses from common types of central heating appliances are largely employed in heating occupied spaces, flue gas losses logically become the item of principal concern. Another reason for their importance is the fact that they are usually larger than all other heat losses combined. These important considerations and others indicate not only the desirability but absolute necessity of a reasonably accurate method for determining flue losses if it is desired to compute even approximate operating efficiencies. Customary procedure in arriving at flue gas losses is to make an analysis of a representative sample of flue gases and to measure their temperature. This information will enable the observer to compute the amount of flue gases produced, the excess air, the actual quantity of air supplied for com bustion, and the flue losses. While the. analysis of flue gases has been well described in several governmental and other scientific publications, the subject is of such importance that it warrants brief repetition here. Carbon dioxide arid oxygen content are of principal interest in determining flue losses. Either or both of these values may be employed in such calcula tions. While the former constituent is probably most commonly employed, special considerations may make the latter of greater interest. Fortun ately, both can be determined readily by use of an Orsat gas analysis ap paratus, a device of reasonably simple construction and design. For field testing and burner adjustment, simple portable devices are available for determining carbon dioxide only. See Chapter 52 for details regarding the operation of the Orsat apparatus. . . The weight of dry flue gas per pound of fuel burned is widely used in combustion loss calculations. For solid fuels this item may be determined by application of Equation 10. Pounds dry flue gas per pound fuel IlC0, + 80, + 7(C0+Vd 3 (CO, + CO) x Values for C02 Ot, CO, and N2 are percentages by volume from the flue gas analysis, and C is the weight of carbon burned per pound of fuel, cor rected for. carbon in the ash. Total dry gas volumes of flue gases resulting from the combustion of one cubic foot of gaseous fuels for various percentages of C02 may be deter mined by application of Equation 11: ' Cubic feet dry flue gases per cubic foot fuel gas = Cubic feet COt produced per cubic foot of gas burned X 100 Percent COt by analysis. . After obtaining the quantity of flue gases from Equations 10 or 11, the excess air quantity may be determined by subtracting the quantity of dry Fuels and Combustion 361 flue gases which would result from perfect combustion. Computations of flue losses are described in the next section on Heat Balance. Application of the preceding equations and tables are illustrated by Ex amples 1 and 8. Example 1: The analysis of the flue gases resulting from the burning of a natural gas is 10.0 percent COt, 3.1percent Ot, and 86.9 percent Nt by volume. The analysis of the fuel.is 90 percent CHt, 5 percent Nt, and 5 percent CtHs by volume. Find V the maximum theoretical percent COt and the percent excess air. Solution: From Equation 9: 1 ' From Equation 8, (lO.OXlOO) 100 - ( \0.21/ 118% CO, Percent Excess Air (11.8 - 10,0) x 90 .10 = 16.2 Example 2: For the analyses in Example 1 find, per cubic foot of fuel gas, the cubic feet of dry air required for combustion, the cubic feet of each constituent in the flue gases, and the total volume of dry and wet flue gases. Seiuiion.-Frdm'Equation 3 (or Table 7) the Volume of dry air required for combus tion is: (9.63) (CH,) + (16.68)(Cy/,) - 9.53 X 0.90 + 16.68 X 0.05 = 9.41 cu ft/cu. ft gas. * From Table 7, the constituents per cubic foot of gas are: Nitrogen, Nt: From methane = (0.9 CHt)(9.53 -- 2.0) = 6.78 NitroFgroemn ienthfuaneel = = (0.05 CtH,) (16.68 - 3.0) = 0.68 0.05 Nitrogen in excess air = 0.791 X -162 X 9.41 = 1.20 . - Total Nitrogen 8.71 eu ft Oxygen, Ot: Oxygen in excess air = 0.209 X .162 X 9.41 = 0.32 cu ft Carbon dioxide, COt: .. From methane = (0.9 CU<)(1.6) = 0.90 From ethane = (0.05 C#H,,)(4.0/2.0) = 0.10 Total Carbon Dioxide 1.00 eu ft Water vapor, HtO (does not appear in Orsat analysis): (0.9 Cfl,)(2.0) = 1.8 (0.05 CtH0 (6.0/2.0) = .15 Total water vapor = 1.95 cu ft Total volume of dry gas per cubic foot of gas: 8.71 + 0.32 -f 1.00 = 10.03 cu ft Total volume of wet gases per cubic foot of gas (neglecting water vapor in combus tion air); ' 10.03 + 1.95 = 11.98 cu ft The cubic feet of dry flue gas per cubic foot of fuel gas may also be computed from Equation II as follows: - (1.00). (100) 10.0 10.0 cu ft HEAT BALANCE The usual practice in analyzing the performance of heating appliances is to make an accounting, insofar as possible, of the disposition of all heat Units available in the quantity of fuel burned. This accounting is called CHAPTER 14 . 1956 Guide 362 Ttpe ov Fuel Maximem Theoretical or Ultimate Percent COt Coke Anthracite Bituminous Coal No. 1 and 2 Fuel Oil No. 6 Fuel Oil Natural Gas Carburetted Water Gas Coke Oven Gas Mixed Gas (Natural and Carbu retted Water Gas) Propane Gas (Commercial) Butane Gas (Commercial) 21.0 20.2 18.2 15.0 16.5 12.1 17.2 11.2 15.3 13.9 14.1 Percent CO at Given Excess Air Valdes 20% 40% 60% 17.5 16.8 15.1 12.3 15.0 14.4 12.9 10.5 13.0 12.6 11.3 9.1 13.6 9.9 14.2 9.2 11.6 8.4 12.1 7.8 10.1 7.3 10.6 6.8 12.5 11.4 11.6 10.5 9.6 9.8 9.1 8.4 8.5 a heat balance. Various components of this balance are generally expressed in terms of Btu per pound of fuel burned, or as a percentage of its calorific value. Components of special interest are listed as items 1 to 7 inclusive. 1. Useful heat transferred to heating medium, usually computed by. determining the rate of flow of the heating fluid through the heating device, and the change in enthalpy of the fluid (heat added) between the inlet and outlet. 2. Heat loss in the dry chimney gases. hi = U>eCp (t, - G). . 3. Heat loss in water vapor formed by the combustion of hydrogen. , h, = 9ffi (1089 - G + 0.455 G) (12) (13) 4. Heat loss in water vapor in the air supplied for combustion. hi => 0.455 M w, (lt -- <,) 5. Heat loss from incomplete combustion. h, = 10143C \co, + coj 6. Heat loss from unburned carbon in the ash or refuse. As= 14600i^c) (14) (15) (16) 7. Radiation and all other unaccounted for losses. Radiation and convection losses from a heating appliance are not usually deter mined by direct measurement. For this reason they, together with any other losses not measured, are determined by subtracting the total of items 1 to 6 from the heat of combustion of the fuel. If the heating appliance is located within the heated space, however, radiation and convection losses may be considered as useful beat rather than lost heat. They may, therefore, be omitted from calculations of heat " A value of 14600 applies in calculating ash pit loss; in calculating heat ol formation ol carbon ootnpounds use' 14093 Btu perlba Fuels and Combustion 363 losses, or added to item 1. If there is CO in the flue gases, small amounts of un burned hydrogen and hydrocarbons will probably also be present. The small loses due to incomplete combustion of these latter gases would also be included in item 7. Symbols used in Equations 12 to 16 inclusive are: hi = heat loss in the dry chimney gases, Btu per pound of fuel. h, = heat loss in water vapor from combustion of hydrogen, Btu per pound of fuel. h, = heat loss in water vapor in combustion air, Btu per pound of fuel, hi = heat loss from incomplete combustion of carbon, Btu per pound of fuel, hi *= heat loss from unburned carbon in the ash, Btu per pound of fuel, = weight of dry flue gas per pound of fuel (from Equation 10), pounds, c,, = mean specific heat of flue gases at constant pressure (cp ranges from 0.242 to 0.254 for flue gas temperatures from 300 F to 1000 F)!, Btu per pound, t. = temperature of flue gases at exit of heating device, Fahrenheit, G = temperature of combustion air, Fahrenheit. Hi = percentage of hydrogen in fuel by weight from ultimate analysis of fuel burned. 1091.8 = enthalpy of saturated water vapor at a temperature of 70 F, Btu per pound. M = humidity ratio of combustion air, pounds of water vapor per pound ol dry air. ~ to. = weight of combustion air per pound of fuel used, pounds, from Equations 2, 4,5, 6, 7 and 8. CO* COi = percentages of CO, COt in flue gases by volume. c = weight of carbon burned per pound of fuel corrected for carbon in ash, pounds. C = WCU - WjC. 100 w (17) where C,, = percentage of carbon in the fuel by weight from the ultimate analysis. IF, = weight of ash and refuse, pounds. C, = percent of combustible in ash by weight (combustible in ash is usually considered to be carbon). W = weight of fuel used, pounds. Flue gas losses for solid and liquid fuels, listed as items 2, 3 and 4 of the heat balance, may be determined with sufficient precision for most purposes from curves shown in Fig. 62, if COi content and temperature of flue gases are known. Values of the losses plotted for fuel oil were com puted from the ultimate analysis of a typical fuel oil used in domestic burners, while those presented for the several ranks of coal were computed from the typical ultimate analyses shown in Table 1. The curves for medium volatile bituminous coal may be used for high volatile bituminous coal with negligible error. Utilization of gaseous fuels, for numerous reasons, is generally a more sim ple process than is the case with either solid or liquid fuels. Accordingly, the determination of a practical heat balance is also a more simple procedure in that items 5 and 6 do not generally apply to gas installations. A series of typical alignment charts has been combined in Fig. 7 for use in determin ing flue losses of items 2,3 and 4 from common types of gas burning appli ances. To determine flue losses place a straight edge extending from the corrected temperature reading to the percent COi recorded. Percent flue loss is indicated where the straight edge interesects the flue loss column. 364 CHAPTER 14 1956 Guide The operating efficiency of a gas appliance can then be computed with sufficient precision by application of Equation 18. / Percent Combustion Efficiency = Gross Btu of fuel \ (gas per cubic foot/ /total flue losses per\ \cubic foot fuel gas)/ Gross Btu of fuel gas per cubic foot ^ Reference to Table 9 will show that ultimate-CCb percentage values of fuel gases vary. While personal errors involved in C02, temperature, and chart determinations, would doubtless more than offset any inaccuracies due to universal use of the alignment charts shown, precise laboratory work may require a more exact method. For more complete information the reader is referred to Combustion, 3rd Edition, and Gaseous Fuels, (published by American Gas Association) and particularly to tables covering - various properties of different commercial gases included in these publications. CONDENSATION AND CORROSION Sulfur" dioxide or sulfur trioxide, formed by the combustion of sulfur in fuels, are the principal corroding substances in flue gases. They become active whenever sufficient moisture is present for the formation of sulfurous or sulfuric acid,22 and they lower the dew points of flue gases appreciably. Therefore, unless heating equipment is designed for operation at flue gas temperatures.below the dewpoint, which is seldom the case, it is always ad visable to maintain temperatures above this value in all parts of the ap pliance. Excessive spot temperatures in the combustion chamber or else where, on the other hand, are also destructive in that they may result in rapid oxidation of ordinary heating surfaces. American Standard Reguiremints for gas furnaces, floor furnaces, and recessed heaters, for example, specify that minimum spot heating surface temperatures during normal operation must neither fall below 178 F (50 F above average dewpoint) nor exceed 875 F on any portion of the heating surface. In any event it is usually desirable to maintain flue temperatures within the limits in dicated not only throughout the appliance, but in its connecting vent, flue, or chimney as well. Otherwise, excessive condensation and corrosion problems, with resultant customer dissatisfaction, will in all probability be the result. Average dewpoint temperatures of flue gases resulting from the combustion of various fuels, when burned with the amount of excess air normally supplied to insure complete combustion, are shown in Table 10. SOOT The deposit of soot on the flue surfaces of a boiler or heater acts as an insulating layer over the surface, and reduces the heat transmission to the water or air. The Bureau of Mines Report of Investigations No. 3272 shows that the loss of seasonal efficiency is not so great as has been be lieved, and usually is . not over 6 percent because the greater part of the heat is transmitted through the combustion chamber surfaces. The Bureau of Standards Report BMS 5424 points out that, although the de crease in efficiency of an oil fired boiler, due to soot deposits, is relatively small, the attendant increase in stack temperature may be considerable. The soot accumulation clogs the flues, reduces the draft, and may pre vent proper combustion. Soot can probably be most effectively removed by a jet of compressed air, by means of a brush, or a vacuum cleaner. However, it has been found that copper chloride, lead chloride, tin chloride, zinc chloride, common salt and some other salts are partially effective in Fuels and Combustion 365 Table 10. Average Flue Gas Dew-Point for Various Fuels8 , ". Type or Fuel Average Dew-Point : Temperature. F Anthracite................................................................................. .. Semi-Bituminous Coal........................................................ . Bituminous Coal.............................................................. . Oil.................................................... Natural Gas....................................... Manufactured Gas.......................... .. Propane Gas (2500 Btu/cu ft)....................................... ........... .. Butane Gas (3200 Btu/cu ft)........................................................... Butane-Air Gas Mixture (535 Btu/cu ft................................ .. 68 84 93 m127 137 119 ' 124 121 removing soot from furnaces and boilers when properly used.26 A discus sion of instruments and methods of evaluating smoke, will be found in Chapter 52. '. ' REFERENCES 1 Five Hundred Tests of Various Coals in Househeating Boilers (U. S. Bureau of Mines Bulletin No. 276). 2 Combustion Efficiencies as Related to Performance of Domestic Heating Plants, by A. P. Kratz, S. Konzo and D. W-. Thompson ( University of Illinois, Engineering Experiment Station Circular No. 44). . -- - 3.Quality of Anthracite as Prepared at Breakers, 1935 (If . S. Bureau of Mines Re port of Investigation, li. I. 3283). 4 Hand Firing Soft Coal Under Power Plant Boilers (U, S. Bureau of Mines Tech nical Paper No. 80). 5 Combustion Flames and Explosions of Gases. Lewis and von Elbe (Cambridge University Press, 1938). 8 Oil Burning, by H. A. Romp (Martinus Nijhoff, 1937). 2 A STM Test Designation D287-39. -. ' 8 ASTM Test Designation D611-43T. ' 8 Tomorrow's Fuel Oil, by W. A. Sullivan and E. B. Glendenning (Fueloil and Oil Heat, Vol. 4, No. 1. May 1945 p. 36). ................ 10 The Correlation of Cetane Number with Other Physical Properties of Diesel Fuels (Journal of the Institute of Petroleum, Vol. 30, 1944, p..193^197). ' " Characterization of Petroleum Fractions, by K. M: Watson, E. F. Nelson and G. B. Murphy (Industrial and Engineering Chemistry, Vol. 27, Dec. 1935, p. 1464). 11 Burning Index for Distillates, by J. C. Reid and A. B. Hersberger. Fueloil and Oil Heat, Vol. 5, No. 9, Jan. 1947, p. 90). 11 Carbon Hydrogen Ratio of Catalytically Cracked Distillate Fuel Oils, by S. P- Cauley and E. B. Delgass (The Oil and Gas Journal, Vol. 45, No. 12 July 27, 1946. P- 166). , 14 Rating of Fuel Oils by a Test Unit, by D. W. Locklin and G. V. Parmelee (ASHVE Transactions, Vol. 57,1951, p. 139). u Gaseous Fuels (American Gas Association, 1948, p. 32). 18 Gas Analysis and Testing of Gaseous Materials by V. J. Altieri (American Gas Association, First Ed. 1945). 12 Tentative Methods of Test for Specific Gravity of Gaseous Fuels (American Society for Testing Materials, ASTM Designation: 1070-49). 18 Standard Method of Test for Calorific Value of Gaseous Fuels by the Water- Flow Calorimeter (American Society for Testing Materials, ASTM Designation: yOO-48). . 19 American Standard for Installation of Gas Piping and Gas Appliances in Buildmgs. ASA Z 21.30 1950 (American Gas Association). 20 NBFU Standard for the Installation of Oil Burning Equipments--NBFU pam phlet no. 31. (National Board of Fire Underwriters). ' 21Domestic Gas Range Research (American Gas Association Laboratories Bulletin 7> p. 64). . 366 CHAPTER 14 1956 Guide ** Condensation of Moisture in Flues, by William R. Morgan (University of Illi nois, Engineering Experiment Station Circular No. 22). , " Effect of Soot on Heat Transmission in Boilers (U. S. Bureau of Mines Report of Investigation No. 3272). 14 Effect of Soot on the Rating of an Oil-Fired Heating Boiler (National Bureau of Standards Report BMS 54). " Removal of Soot from Furnaces and Flues by the Use of Salts and Compounds, by P. Nicholls and C. W. Staples (V. S. Bureau of Mines Bulletin No. 360). BIBLIOGRAPHY Fuels and Their Combustion, by Haslam and Russell (McGraw-Hill Co., 1926). Principles of Combustion in the Steam Boiler Furnace, by Arthur D. Pratt (Bab cock and Wilcox Co.). Smoke-Producing Tendencies in Coals of Various Ranks, by H. J. Rose and F. P. Lasseter (A.S.H.V.E. Transactions, Vol. 45, 1939, p. 329). Fundamentals of Combustion in Small Stokers, by C. A. Barnes (Bituminous Coal Research, Inc., Technical Report No. IV). Hand-Firing of Bituminous Coal in the Home, by A. P. Kratz, J. R. Fellows, and J. C. Miles (Illinois Engineering Experiment Station Circular No. 46). Classification and Selection of Illinois Coals, by G. H. Cady (Illinois Slate Geo logical Survey Bulletin No. 62). Bituminous Coal Research, Inc.: . Technical Report VI, The Treatment of Coal with Oil and Other Petroleum Prod ucts, by J. M. Pilcher and R. A. Sherman. Information Bulletin No. 4, Dustless Treatment of Coals with Materials Other Than Oil, by R. A. Sherman and G. W. Land. Information Bulletin No. 6, Questions and Answers on the Use of Fuel Oil for Dust less Treatment. Technical Report VII--Application of Overfire Air Jets, by R. B. Engdahl. Bureau of Mines Publications: Bulletin No. 97, Sampling and Analyzing Flue Gases, by Henry Kreisinger and F. K. Ovitz. Report of Investigations (R. I. 2980), Coke as a Domestic Heating Fuel, by P. Nicholls and B. A. Landry. Technical Paper No. 303, Value of Coke, Anthracite, and Bituminous Coal for Generating Steam in a Low-pressure Cast-Iron Boiler, by John Blizard, James Neil, and F. C. Houghten. . Bulletin 378, Effect of Preheat, and Distribution of Ash in Fuel Beds, by P. Nicholls. Handbook, Questions and Answers for the Home Fireman (Revised), by J. F. Barkley. Anthracite Industries Laboratories Publications: Report 2015, Comparison of Sizes, Egg, Stove and Chestnut Anthracite. Report 2018, Domestic Survey. Report 2062, Utilization of Anthracite for Domestic Heating. Report 2204, The Crater Method of Firing. Report 2403, Anthracite Industries Manual. . Oil and Gas Publications: Oil Fuels and Burners, by James A. Moyer (McGraw-Hill Co., 1937). Industrial Gas Series, Combustion (American Gas Association). Comfort Heating (American Gas Association). Gaseous Fuels (American Gas Association, 1948). Handbook of Oil Burning, by F. H. Faust and G. T. Kaufman (Oil-Heat Institute of America, 1951). Formulas and Graphs for Representing the Interchangeability of Fuel Gases, by Elmer R. Weaver (National Bureau of Standards Journal of Research, 1951, Re search Paper R.P. 2193). CHAPTER 15 AUTOMATIC FUEL BURNING EQUIPMENT Classification of Stokers, Combustion Process and Adjustments, Furnace Design, Rating; Classification of Oil Burners, Combustion Process, Combustion Chamber Design; Commercial and Industrial Oil Burners, Types of Burners; Oil ' Storage Tanks and Piping; Classification of Gas-Fired Heating ' Equipment, Combustion Process, Ratings; Sizing of Gas - .v Piping, Fuel Burning Rates . AUTOMATIC mechanical equipment for the combustion of solid, liquid, and gaseous fuels is considered in this chapter. MECHANICAL STOKERS A mechanical stoker is a device that feeds a solid fuel into a combustion chamber, provides a supply of air for burning the fuel under automatic control and, in some cases, incorporates a means of removing the ash and refuse of combustion automatically. Coal can be burned more efficiently by,a mechanical stoker than by hand firing because the stoker provides a uniform rate of fuel feed, better distribution in the fuel bed and positive control of the air supplied for combustion. Classification of Stokers According to Capacity Stokers may be classified according to their coal feeding rates. The following classification has been made by the U. S. Department of Com merce, in cooperation with the Stoker Manufacturers Association. Class 1. Capacity under 61 lb of coal per hour. Class 2. Capacity 61 to 100 lb of coal per hour. Class 3. Capacity 101 to 300 lb of coal per hour. Class 4. Capacity 300 to 1^)0 lb of coal per hour. Class 5. Capacity 1200 lb of coal per hour and over. . ` Class 1 Stokers These stokers are used primarily for home heating and are designed for quiet, automatic operation. Simple, trouble-free construction and attrac tive appearance are desirable characteristics of these small units. A common stoker in this class (Fig. 1) consists essentially of a coal hopper, a screw for conveying the coal from the hopper to the retort, a fan which supplies the air for combustion, a transmission for driving the coal feed worm, and an electric motor for supplying power for coal feed and air supply. :. Air for combustion is admitted to the fuel through tuyeres at the top of the retort which may be either round or rectangular. Stokers in this class are made for burning anthracite, bituminous, semi-bituminous, and lignite coals, and coke. The U. S. Department of Commerce has issued commercial standards for household anthracite stokers.1 Units are available in either the hopper type, as shown in Fig. 1, or in the bin-feed type as shown in Figs. 2 and 3. Some stokers, particularly those designed for use with anthracite, automatically remove ash from the ash pit and deposit it in an ash receptacle as shown in Fig. 3. Most 367 , ; i 1 ! ` : iiii t j i.| r 1956 Guide of the bituminous models, however, require removal of the ash from the fuel bed after it is fused into a clinker. . Stokers in this class feed coal to the furnace intermittently in accordance with temperature or pressure demands. A special control is used to insure sufficient stoker operation to maintain a fire during periods when no heat is required. Where year-round domestic hot water is supplied by a boiler and indirect water heater connected to a storage tank, the stoker will usually be called on to operate often enough to maintain the fire. Stoker-Fired Boiler and Furnace Units Boilers, air conditioners, and space heaters especially designed for stokers are available having design features closely coordinating the heat absorber and the stoker. Although efficient and satisfactory performance can be obtained from the application of stokers to existing boilers and, I hopper Fig. 1. Underfeed Stoker, Hopper Type, Class 1 Fio. 2. Underfeed Stoker, Bin Feed Type, Class 1 furnaces, some of the combination stoker-fired units (Fig. 4) are more compact and attractive in appearance. Class 2 and 3. Stokers Stokers in this class are usually of the screw feed type without auxiliary plungers or other means of distributing the coal. They are used exten sively for heating plants in apartments and hotels, also, for industrial plants. They are of the underfeed type and are available in both the hop per type, as illustrated in Fig. 5, and the bin feed type, shown in Fig. 6. These units also are built in plunger feed type with an electric motor or a steam or hydraulic cylinder coal feed drive. Stokers in this class are available for burning all types of anthracite, bituminous and lignite coals. The tuyere and retort design varies accord ing to the fuel and load conditions Stationary type grates are used on bituminous models, and the clinkers formed from the ash accumulate on the grates surrounding the retort. Anthracite stokers in this class are equipped with moving grates which Automatic Fuel Burning Equipment 369 discharge the ash into a pit below the grate. This ash pit may be located on one or both sides of the grate and, in some installations, is of sufficient capacity to hold the ash for several weeks' operation. Class 4 Stokers Stokers in this group vary widely in details of design, and several methods of feeding coal are employed. The underfeed stoker is widely used, al though a number of the overfeed types are used in the larger sizes. ; Binfeed, as well as hopper models, are available in both underfeed and overfeed types. Class 5 Stokers The prevalent stokers in this field are: (1) underfeed side cleaning, (2) underfeed rear cleaning, (3) overfeed fiat grate, and (4) overfeed inclined grate. Underfeed side cleaning stokers are made in sizes up to approximately 500 boiler horsepower. They are not so varied in design as those in the smaller classes, although the principle of operation is similar. A stoker of this type is illustrated in Fig. 7.. The rear cleaning underfeed stoker is usually of the multiple retort design, and is used in some of the largest industrial plants and central power stations. Zoned air control has been applied to these stokers, both I6ngitudinally and transversely of the grate surface. The overfeed flat grate stoker is represented by the various chain--or traveling-grate stokers. A typical traveling-grate stoker is illustrated in Fig. 8. Another distinct type of overfeed flat-grate stoker is the spreader (Figs. 9 and 10) type in which coal is distributed either by rotating paddles or by air over the entire grate surface. This type of stoker is adapted to a wide range of fuels and has a wide application on small sized fuels, and on fuels such as lignites, high-ash coals, and coke breeze. . The overfeed inclined-grate stoker operates on the same general com bustion principle as the flat-grate stoker, the main difference being that rocking grates, set on an incline, are provided in the former to advance the fuel during combustion. Combustion Process In anthracite stokers of the Class 1 underfeed type, burning takes place entirely within the stoker retort. The refuse of combustion spills over the edge of the retort into an ash pit or receptacle from which it may be removed either manually or automatically. Larger underfeed anthracite stokers operate on the same principle, except that the retort is rectangular and the refuse spills over only one or two sides of the grate. Anthracite for stoker firing is usually the No. 1 buckwheat or No. 2 buckwheat size. Because the majority of the small bituminous coal stokers operate on the underfeed principle, a general description of their operation is given. When the coal is fed into the retort, it moves upward toward'the zone of combustion and is heated by conduction and radiation from tjie burning fuel in the combustion zone. As the temperature of the coal rises, it gives off moisture and occluded gases, which are largely non-combustibles. When the temperature increases to around 700 or 800 F the coal particles become plastic, the degree of plasticity varying with the type of coal. 370 CHAPTER 15 1956 Guide Automatic Fuel Burning Equipment 371 Fig. 3. Underfeed Anthracite Stoker with Automatic Ash Removal, Bin Type ' Feed igw / Fig. 4. Stoker-Fired Winter Air Conditioning Unit Fig. 7. Underfeed Side Cleaning Stoker Fig. 5. Underfeed Screw Stoker, Hopper Type, Class 2, 3 or 4 A rapid evolution of the combustible volatile matter occurs during and directly after the plastic stage. The distillation of volatile matter con tinues above the plastic zone where the coal is coked. The strength and porosity of the coke formed will vary according to the size and character istics of the coal. While some of the ash fuses into particles on the surface of the coke as it is released, most of it remains on the hearth or grates and, as this ash layer becomes thicker with time, that portion exposed to the higher temperatures surrounding the retort fuses into a clinker. The temperature in the fuel bed, the chemical composition and homogeneity the ash, and the time of heating govern the degree of fusion. Most bituminous coal stokers of Glasses 1, 2, .3 and 4 require manual removal of the ash in clinker form. :372 CHAPTER 15 1956 Guide In the underfeed side-cleaning stokers the fuel is introduced at the front of the furnace to one or more retorts, and is advanced away from the retort as combustion progresses, while finally the ash is disposed of at the sides. This type of stoker is suitable for all bituminous coals, while in the smaller sizes it is suitable for small sizes of anthracite. In this type of stoker the fuel is delivered to a retort beneath the fire and is raised into the fire. During this process the volatile gases are released, are mixed with air, arid pass through the fire where they are burned. The ash may be con tinuously or periodically discharged at the sides. The' underfeed rear-cleaning stoker accomplishes combustion in much the same manner as the side-cleaning type, but consists of several retorts placed side by side and filling up the furnace width, while the ash disposal is at the rear. In principle, its operation is the same as the side-cleaning underfeed type. Overfeed flat-grate stokers receive fuel at the front of the grate in a Automatic Fuel Burning Equipment 373 as to maintain a balance between the load demand and the heat liberated by the fuel, tinder such conditions, no manual attention to the fuel bed should be required other than the removal of clinker in stokers which operate on this principle of ash removal. As in all combustion processes, the maintenance of the correct proportions ofair and fuel is essential. It is desirable to supply the minimum amount of air required to properly bum the fuel at the rate of feed. While there may be only slight variations in the rate at which the coal is being fed, due to variations in the size or density of the coal, there may be wide variations in the rate of air flow as the result of changes in fuel bed re sistance. These changes in resistance may be caused by changes in the porosity of the fuel bed due to variations in size or friability of the coal, ash and clinker accumulation, and variations in depth of the fuel bed. Because of this variable fuel bed resistance, many bituminous stokers, even in the smaller domestic sizes, incorporate air controls which automatically eom- layer of uniform thickness and move it horizontally to the rear of the furnace. Air is supplied under the moving grate to carry on combustion at a sufficient rate to complete the burning of the coal near the rear of the furnace. The ash is carried over the back end of the stoker into an ash pit beneath. This type of stoker is suitable for small sizes of anthracite or coke breeze, and also for bituminous coals; the characteristics of which make it desirable to bum the fuel without disturbing it. This type of stoker requires an arch over the front of the fuel bed to maintain ignition of the incoming fuel, and frequently a rear combustion arch. In addition to the use of rocking grates, the overfeed inclined-grate stoker is provided with an ash plate on which ash is accumulated and dumped periodically. This type of stoker is suitable for all types of coking fuels, but preferably for those of low volatile content. Its grate action keeps the fuel bed broken up, thereby allowing free passage of air. Because of its agitating effect on the fuel, it is not desirable for badly clinkering coals. It usually should be provided with a front arch to ignite the volatile gases. Combustion Adjustments The coal feeding rate and air supply to the stoker should be regulated so Fig. 10. Overfeed Spreader Stoker (Pneumatic Type) pensate for these changes in resistance and maintain a constant air fuel ratio. The efficiency of combustion may be determined by analyzing the flue gases, as explained in Chapters 14 and 52. It is desirable on most stoker installations to provide automatic draft regulation in order to reduce air infiltration and provide better control during the banking, or off, periods of the stoker. Furnace Design ' . - ' Although there is considerable variation in stoker, boiler, and furnace design, the stoker industry, from; long-time experience, has, established* certain rales for the. proportioning of furnaces for domestic; and com mercial stokers. The stoker installer and designer of stoker-fired equip ment should give careful consideration to these factors. : . -. ` The Stoker Manufacturers Association has published standard recom mendations on setting heights for stokers having capacities up to 1200 lb of coal per hour.2 . The empirical formulas for determining these setting heights are: For burning rates up to 100 lb coal per hour H = 0.1125 B + 15.75 ' <I) 374 CHAPTER IS 1956 Guide For burning rates from 100 to 1200 lb coal per hour H = 0.03 B + 24 where H = minimum setting height, inches, measured from dead plates to crown sheet for steel boilers. For cast-iron boilers height may be f H. B = burning rate coal per hour, pounds. Standards for minimum firebox dimensions and base heights have been formulated by the Stoker Manufacturers Association as shown in Fig. 11.* In considering these recommendations, it should be understood that they show the average recommended minimum. There are many factors affecting the proper application of stokers to various types of boilers and furnaces, and, - in certain instances, setting height or firebox dimensions shown in the standards may be modified without impairing performance. Such modification will depend upon the experience of the installer or de- Automatic Fuel Burning Equipment 375 or hot water heating system, a piping and pick-up factor of 1.33 is com monly used in sizing the stoker, but this factor should be increased at times due to unusual conditions. Controls , The heat delivery from the stoker of the smallest household type to the' largest industrial unit can be regulated accurately with fully automatic controls. The smaller heating applications are controlled normally by a thermostat placed in the building to be heated. Limit controls are supplied to prevent excessive temperature or pressure from being developed in the furnace or boiler, and refueling controls are used to maintain ignition during periods of low heat demand. Automatic low water cut-outs are recom mended for. use with all automatically-fired steam boilers. (See Chapter DOMESTIC OIL BURNERS An oil burner is a mechanical device for producing heat automatically from liquid fuels. Two methods are employed for the preparation, of the Fig. 11. Suggested Minimum Firebox Dimensions and Base Heights* * For reference in selecting or designing boilers and fundees for stoker firing. Dimenswrasshown are fo net inside clearance at grate level using coal with heating value of not less than 12,000 Btu per pound. Under certain conditions smaller fireboxes will permit satisfactory performance but these dimensions are pieferreo normal minimums. . signer with a particular stoker, the type of fuel used, and the construction of the boiler or furnace. Installation of stokers (particularly smaller sixes) on the side of the boiler or furnace will sometimes facilitate clinker removal. Rating and Sizing Stokers The capacity or rating of small underfeed stokers is usually stated as the burning rate in pounds of coal per hour. Codes for establishing uni form methods of rating anthracite and bituminous coal stokers have been adopted by the Stoker Manufacturers Association.* The Association also has adopted a uniform method of selecting stokers that is published in convenient tables and charts.' The required capacity of the stoker is calculated as follows: Stoker burning rate Load (Btu per hour)______________________ = required (pounds of Heating value of coal (Btu per pound) X overall efficiency of coal per hour) stoker and boiler or furnace In determining the total load placed on a stoker-fired boiler by a steam oil for the combustion process; atomization, and vaporization. The simpler types of burners depend upon the natural chimney draft for supplying the air for combustion. Other burners provide mechanical air supply or a combination of atmospheric, and mechanical. Ignition is accomplished by an electrical spark or hot wire, or by an oil or gas pilot. Some burners utilize a combination of these methods. Continuously operating burners may use manual ignition. Burners of different types operate with lumi nous or non-luminous flame. Operation may be intermittent, continuous with high-low flame, or continuous with graduated flame. Classification of Burners . Domestic oil burners may be classified by type of design or operation mto the following groups: pressure atomizing or gun, rotary, and vapor izing or pot. These are further classified as mechanical draft, and natural draft. Pressure Atomizing (Gun Type) Burner Gun type burners are usually designed to bum No. 1 or 2 grade fuel oil. They may be divided into two classes: high-pressure and low-pressure 376 CHAPTER 15 1956 Guide atomization. The high-pressure atomizing type, illustrated in Fig. 12, is characterized by an air tube, usually horizontal, with oil supply pipe cen trally located in the tube and arranged so that a spray of atomized oil is introduced at about 100 psi, and mixed in the combustion chamber with the air stream emerging from the air tube. A variety of patented shapes is employed at the end of the air tube to influence the direction and speed of the air, and thus the effectiveness of the mixing process. A fan is used to supply the air for combustion. Ignition is established by a high-voltage electric spark that may be .operative continuously while the burner is running, or just at the beginning of the running period. The burner operates on the intermittent on-off principle, and with a luminous flame. ; The combustion process is completed in a chamber constructed of re fractory material, or stainless steel, this being a part of the installation. Automatic Fuel Burning Equipment ; ; 4 > 377 or refractory material which is placed around the hearth. Dependent upon combustion adjustment, these burners may operate with either a semiluminous or non-luminous flame. Both types of vertical rotary burners are further characterized by their installation within the ash pit of the boiler or furnace. Various types.'of ignition are utilized, gas and electric, either spark or, hot wire. The air for combustion is supplied partially by natural draft, and partially by fan effect of the central spinner element. . Vaporizing Burner . In the vaporizing burner, fuel oil is ignited" (manually or electrically) and vaporized in a vessel or pot which is open at the top or one side. Heat for vaporization is supplied by the combustion process. Openings in the side' walls of the burner admit primary air which forms a rich mixture of air and oil vapors in the burner. Adjacent to the outlet opening; sufficient addi tional or secondary air is admitted to complete combustion. The openings The low pressure atomizing type differs from the high pressure type mainly by having means for supplying a mixture of oil and primary air to the burner nozzle. The air pressure before mixing and the pressure of the oil-air mixture at the nozzle vary with different makes of burners, but are in a low range of 1 to 15 psig for the air and 2 to 7 psig for the mixture, respectively. The various parts of the burner, except for oil and air mixing parts, are the same as shown in Fig. 12. Rotary Type Burner This class of burners may be divided into two groups: vertical and horizontal. Most of the smaller rotary burners are of the vertical type, and use a fuel oil of No. 1 or 2 grade. The most distinguishing feature of vertical rotary burners is the principle of flame application. These burners are of two general types: the center flame and wall flame. In the former type (Fig. 13), the oil is atomized by being thrown from the rim of a revolving disc or cup, and the flame bums in suspension with a characteristic yellow color. Combustion is supported by means of a bowl-shaped chamber or hearth. The wall flame burner (Fig. 14) differs in that combustion takes place in a ring of stainless steel for admitting air are arranged to obtain gradual and intimate mixing of air and oil vapor for combustion, with a minimum amount of excess air and resulting high combustion efficiency. Fuel is fed by gravity from a constant level control valve, and the flow is either on (at rated capacity) or off (at pilot flow), according to the de mand of the thermostat. However, the high fire can be reduced and the pilot fire can be increased to give almost any desired control characteristic within the range of the burner. The majority of vaporizing burners are manufactured in sizes up to one gallon per hour input. Most vaporizing burners are limited to use with No. 1 fuel oil having a maximum end point of 625 F and a minimum A.P.I. gravity of 35 deg. A barometric draft regulator is required to maintain the recommended draft. A draft of not more than 0.06 in. of water column is recommended for most natural draft burners. When burners are equipped with me chanical forced' draft, a slightly lower chimney draft can be used. A burner of this type is illustrated in Fig. 15. A gravity type is shown in Fig. 16. . Vaporizing burners are adaptable to water heaters, space heaters, and furnaces. Some types have also been applied successfully to conversion 378 CHAPTER IS 1956 Guide installations. The heat output is in the range of requirements for the average or small home. ;' The modulating flame allows simple manual control by regulation of a metering valve, and simplifies the control equipment. Quiet combustion and the absence of moving parts contribute to quiet operation when the heating device is located in the living quarters. The ability to operate on natural draft and gravity feed of the fuel, makes possible the use of these burners where electric current is not available or is unreliable. However, most furnaces are thermostatically controlled, and many are provided with mechanical draft. .- ' - - V . . Oil-Fired Boiler and Furnace Units A number of types of specially designed oil-fired boiler-burner and furnace-burner units are available. Various locations of burners will be noted in such units; some having the combustion chamber and burner Automatic Fuel Burning Equipment 379 A vaporizing burner prepares the oil for combustion by transforming the liquid fuel to the gaseous state by the application of heat. In an atomizing burner, the oil is mechanically separated into very fine particles so that the surface exposure of the liquid to the radiant heat of the combustion chamber is vastly increased and vaporization thereby promoted. The result is the ability to bum more and heavier oil within a given combustion space. Because the air enters the combustion chamber with the liquid fuel particles, mixing, vaporization and burning occur all at once in the same space. This produces a luminous flame. A deficient amount of air is indicated by a dull red or dark orange flam? with smoky tips. An excessive supply of air may produce a brilliant white flame or a short ragged flame with incandescent sparks flashing through the com bustion space. While extreme cases may be detected, it is not possible Fig. 16. Vaporizing Gravity Pot-Type Burner at the top, some at the bottom, and some at the center of the appliance. Typical combination units are shown in Figs. 17 and 18. The coordinated design of boiler (or furnace) and burner elements insures the optimum in operating characteristics, and the maintenance of balanced performance. This type of equipment usually has more heating surface, and better flue proportions and gas travel than conventional boilers or furnaces. Some of the better conversion installations, however, may equal the unit type in performance. Operating Requirements for Oil Burners The U. S. Department of Commerce, in conjunction with the oil burner and heating appliance industries, has established commercial standards for con version burners and burner-appliance units which cover installation, con struction and performance tests.4 Combustion Process Efficient combustion must produce a clean flame and use a relatively small excess of air, i.e., between 25 and 50 percent. This can be done only by vaporising the oil quickly and completely, and mixing it vigorously with air in a combustion chamber hot enough to support the combustion. OIL BURNER Fig. 17. Typical Boiler-Burner Unit to distinguish, by eye, the effect of the finer adjustment which competent installation requires. Combustion Adjustments The present-day oil burner with mechanical oil and air supply, properly installed and equipped with an automatic draft regulator, is capable of maintaining efficient combustion for a considerable period following the initial adjustments of oil and air. Eventually, certain changes will occur, and may be such that the amount of excess air will decrease below allow able limits. A decrease in air supply while the oil delivery remains con stant, or an increase in oil delivery while the air supply remains constant, will make the mixture of oil and air too rich for clean combustion. The more efficient the adjustment, the more critical it will be. The oil and air supply rates must remain constant. The following factors may influence the oil delivery rate: (1) changes m oil viscosity due to temperature change or variations in grade of oil delivered; (2) erosion of atomizing nozzle; (3) fluctuations in by-pass relief pressures; and (4) possible variations in methods of atomization. Any change due to partial stoppage of oil delivery null increase the proportion 380 CHAPTER 15 1956 Guide of excess air. This will result in less heat, reduced economy ; and possibly a complete interruption of'service. " ' ' / : The following factors may influence the air supply: (1) changes in combustion draft due to a variety of . causes (t.e., ..changes in chimney draft because of weather changes, seasonal changes, back drafts, failure or inadequacy of automatic draft regulator, .use of chimney for other purposes, possible stoppage of the chimney, and changes in draft resistance of boiler due to partial stoppage of .the flues); and (2) changes in air inlet adjustments at the fan. ' ". Air leakage into the boiler or furnace setting should be reduced to a minimum. The amount of air leakage will be determined by the draft in the combustion chamber. It is important that this draft should be reduced as low as is consistent with the proper disposal of the gases of combustion. When using mechanical draft burners with average condi tions,' the combustion chamber draft should not be allowed to. exceed 0.02-0.05 in. water. An automatic draft regulator is necessary in order to maintain constant draft conditions which, in turn, improve efficiency of operation. The draft regulator should be adjusted in accordance with the manufacturer's instructions. ' \ Even though a fan is generally used to supply the air for combustion, in most oil burners, the. importance of a iproper: chimney ..should not be - overlooked. The chimney should have sufficient height and size to insure that the draft will be uniform withinThe limits given,if maximum efficiency throughout the heating season is to he"maintained. ... . Measurement of the Efficiency, of Combustion ; 1/ . Since efficient combustion is based Upon' a' clean flame and definite proportions of oil add air employed) it is possible to determine the results by analyzing the combustion gases. It is usually sufficient- to analyze only for carbon dioxide (CO2) and to obtain the temperature of the stack gas. A showing of TO to 12 percent indicates the best' adjustment, if the flame is clean. Most of the good installations show from 8 to 10 percent Automatic Fuel Burning Equipment 381 CO2. Taking into acoount the potential hazard of low excess air (high CO2), a setting to give 10 percent C02 constitutes a reasonable standard for most oil burners. Commercial Standard CS-75 requires that oil burners labeled as complying with the standard shall obtain smoke-free combustion at 10 percent :C02. In all cases smokeless combustion is a requirement for oil burners. . Combustion Chamber Design With burners requiring a refractory combustion chamber, the size and shape should be in accordance with the manufacturer's instructions. It is important that the chamber be as nearly air tight as is possible, except when the particular burner requires a secondary supply of air for combustion. The atomizing burner is dependent upon the surrounding heated com bustion chamber surfaces to vaporize the oil and support combustion. Unsatisfactory combustion may be due to inadequate atomization and mixing. ' A combustion chamber can only compensate for these things to a limited extent. If liquid fuel continually reaches some part of the fire brick surface, a carbon deposit will result. The combustion chamber should enclose a space having a shape similar to the flame, but large enough to avoid flame contact. The nearest approach in practice is to have the bottom of the combustion chamber flat, but far enough below the nozzle to avoid flame contact, the sides tapering from the air tube at the same angle as the nozzle spray, and the back wall rounded. A plan view of the combustion chamber resembles in shape the outline of the flame. This insures quick vaporization, rapid combustion and better mixing by elimi nating dead spaces in the combustion chamber. An overhanging arch at, the back of the fire pot is sometimes used to increase the flame travel and give more time for mixing and burning,"and sometimes to prevent the gases from going too directly into the boiler flues. When good atomization and vigorous mixing are achieved by the burner, combustion chamber design becomes a less critical matter. Where secondary air is used, combustion chamber design is quite important. When installing some of the vertical rotary burners, the manufacturer's instructions must be followed carefully when installing the hearth, as in this class successful performance depends upon this factor. Boiler Settings 1 As the volume of space available, for combustion is a determining factor in oil comsumption, it is general practice to remove grates and extend the combustion chamber downward to include or even exceed the ash pit volume; in new installations the boiler may be raised to make added, volume availably. Approximately 1 cu ft of combustion volume should be provided for every developed boiler horsepower, and in this volume from 1-5 to 2.5 lb of oil per hour can properly be burned. This corresponds to an average liberation of about 38,000 Btu per cubic foot per hour. At times much higher fuel rates may be satisfactory. For best results, care should be taken to keep the gas velocity below 40 fps. Where checkerwork of brick is used to provide secondary air, good practice calls for about 1 sq in. of opening for each pound of oil fired per hour. Such checkerwork is best adapted to flat flames, or to conical flames that can be spread over the floor of the combustion chamber. The proper bricking of a large or even medium sized boiler for oil firing is important, and frequently it isadvisable to consult an authority on this subject. The essential in combustion 382 CHAPTER 15 1956 Guide chamber design is to provide against flame impingement upon either me tallic or firebrick surfaces. Manufacturers of oil burners usually have available detailed plans for adapting their burners to various types of boilers, and such information should be utilized. Controls for oil burner operation, including devices for the safety and protection of a boiler or furnace, are fully described in Chapter 39. COMMERCIAL AND INDUSTRIAL OIL BURNERS Oil burning equipment for commercial and industrial applications is usually designed for burning the lower cost heavy fuel oils such as U. S. Commercial Standard Grades Nos. 4, 5, and 6. The viscosity of these oils is much greater than that of the lighter domestic grades and, therefore, the equipment required for satisfactory storage, pumping, and combustion differs greatly from that used in the typical domestic oil burning system.' Both the initial cost and the operating cost of an oil burning system may be affected materially by the characteristics of the industrial fuel oil to be used. These characteristics should, therefore, be given careful con sideration when setting up the specifications of the fuel oil for which the system is to be designed. ' Classification of Burners These burners are usually classified according to the method used for atomizing the oil as (1) horizontal rotary cup atomizing, (2) mechanical pressure atomizing, (3) steam atomizing, and (4) air atomizing. Horizontal Rotary Cup Burner In this type of burner, oil is delivered into a horizontal cup that is rotated at high speed. As the thin film of oil is spun from the rim of the cup, it enters a cone of high velocity primary air and very effective atomiza tion is obtained. In most applications secondary air for combustion is supplied by natural draft through checkered openings in the floor of the combustion chamber. In some applications, however, the secondary air is admitted through openings surrounding the burner nozzle and may be supplied by forced draft. The rotary cup burner has been the most popular type in the capacity range from approximately 25 to 500 boiler horsepower. Its principal ad vantages are that it is a self-contained integral unit; it is readily adaptable to manual, semi-automatic, or fully-automatic control; and the firing rate may be easily modulated through a wide range while maintaining high combustion efficiencies. These burners are frequently used for firing pack aged steam generator units. Mechanical Pressure Atomizing Burner In this burner oil is atomized by passing it through a specially designed nozzle under pressures of approximately 100 to 250 psig. The air for com bustion may be supplied by either natural or forced draft, and is usually admitted through an air register surrounding the burner nozzle or through checkered openings in the floor of the combustion chamber. This burner is popular for marine service and for large capacity multiple installations. It is not readily adapted to fully automatic operation. Automatic Fuel Burning Equipment - 383 Steam Atomizing Burner High pressure steam is used in this burner for atomizing the oil. Oil is delivered to the nozzle at pressures ranging from approximately '5 to 50 psig, and steam at approximately 50 to 150 psig is admitted to the nozzle by various methods to assist in the atomization. Combustion air is usually supplied by natural draft through checkered openings in the floor of the combustion chamber or through an air register surrounding the nozzle. . This burner is relatively low in first cost but is not adapted to fully automatic operation or wide variations in firing rate. -. Air Atomizing Burner , The air atomizing burner is similar to the steam atomizing type, except that air under pressure instead of steam is used for atomization. The performance characteristics of the two burners are also similar but higher temperature oil is usually required when using air for atomization. Heating the Oil ; - Commercial, Standard No. 4 fuel oil is intended for use in burners that are not equipped with preheating facilities. Nos. 5 and 6 oils usually require preheating equipment to reduce their viscosity sufficiently for satis factory pumping and atomization. Some oils in the lower viscosity range of No. 5 specification may at times be handled without preheating, but definite viscosity limitations should be specified if this is attempted. In northern climates, the pour point of oil may affect the preheating require ments and should be included in the oil specifications. The common heat sources employed in the heating of fuel oil are steam, hot water and electricity. Shell and tube type heaters connected to the oil fired boiler are normally used for steam or hot water heating. It is extremely important in many plants to provide oil heating-equipment that will readily permit starting the burner After a prolonged shutdown during cold weather. While the initial cost of this heating system may be higher, it is necessary where a plant shutdown may cause the oil in the tank and oil lines to congeal to a point where circulation cannot be re-established unless the oil preheating system is designed for this type of service. OIL STORAGE TANKS AND PIPING Storage tanks, also the piping and pumping facilities for delivering the oil from the tank to the burner, are very important considerations in the design of an industrial oil burning system. The construction and location of the tank and oil piping are usually subject to local regulations which should always be consulted, and to the standards of the National Board of Fire Underwriters, such as NFBU Pamphlet No. 31. The size of the storage tank is usually based on the rate at which oil is to be consumed, the space available, method of oil delivery (truck or tank car) and the ease with which deliveries can be made under all weather conditions. A minimum capacity of at least the maximum weekly usage is desirable. If deliveries are to be made by tank car, the capacity should not be less than 15,000 gal. The 275 gal oil storage tank is commonly used for domestic installations. 384 CHAPTER 15 1956 Guide In most localities it may be installed in basements without being enclosed. Where a greater storage capacity is necessary, local regulations usually permit inside installation of two tanks of 275 gal each in accordance with NBFU Standards Pamphlet No. 31. . GAS-FIRED HEATING EQUIPMENT A gas burner is defined by the American Gas Association as "a device for the final conveyance of the gas, or a mixture of gas and air, to the combustion zone." Burners used for domestic heating are of the atmos pheric injection, luminous. flame, or power burner types. . Because of the ease with which gas fuel may be controlled, automatic gas-fired heating equipment has become veiy widely used, and is available Automatic Fuel Burning Equipment 385 cast-iron, steel, and non-ferrous metals. The burners are located beneath the sections, and the flue gases pass upwards between the sections to the flue collector. Some boilers are designed to . provide domestic hot water through the use of tankless or instantaneous heaters. ., Warm air furnaces are of two types, gravity and forced air. The former depends upon a thermal head to provide circulation of air over the heat exchanger and thence directly to the space to be heated, usually through ducts. Most gravity furnaces can be equipped with humidifiers. Forced warm air furnaces utilize a motor-driven blower to circulate air over the heat exchanger and through the ducts. A common type is quite similar to Fig. 18 except that gas burners, pilots, controls, and gas pressure regu1 lator are substituted for the oil burner, and a draft hood is attached to the outlet of the furnace. Due to the pressure developed by the blower, ductwork becomes smaller and the location of the furnace less critical than in gravity systems. Designs of forced air furnaces vary from the conven tional types that deliver heated air to overhead ductwork to the downblow types wherein the heated air is delivered at the bottom of the furnace, this Fig. 19. Gas-FmED Boiler SECTIONAL VIEW in a number of types of domestic gas heating appliances and systems. These may be classified in types designed for central heating plants and those for unit application. Gas designed units and conversion burners are available for the several kinds of central systems in which gravity and forced warm air furnaces or steam and hot water boilers are used, and for other applications where warm air floor furnaces and room heaters are installed in the space being heated. Central Heating Systems Boilers and furnaces specially designed for gas-firing incorporate design features for obtaining maximum efficiency and performance. Small flue passes to secure good heat transfer, the use of materials resistant to the corrosive effects of products of combustion, and draft hoods are notable features. Control equipment includes gas pressure regulators, automatic pilots, and limit controls designed to protect the appliance and to insure safety of operation. A boiler designed for gas-burning is illustrated in Fig. 19. . Gas designed boilers for hot water or steam heating are available in Fig. 20. Typical Single Port Gas Conversion Buhner latter type being designed for perimeter or radiant panel heating. Several types of low height horizontal furnaces are available for installation in attics or under floors of unexcavated houses. These furnaces are designed for compactness. The A.G.A. listed output at the boiler nozzle or at the bonnet for forced air and gravity furnaces is 80 and 75 percent, respectively, of the approved input to the burners. Conversion Burners Conversion burners are usually complete burner and control units de signed for installation in existing boilers and furnaces. A typical gas con version burner is shown in Fig. 20. Atmospheric conversion burners may have drilled port, slotted port, or single port burner heads. Single port types have become increasingly popular in the last few years due to their simplicity of construction and ease of installation. In rectangular or round, drilled and slotted port burners baffles of clay or metal are usually used to direct the products of combustion toward the side walls of the combustion chamber. In single port burners the flame usually impinges against a horizontal cast-iron, stainless steel, or ceramic distributor plate which directs the products of combustion toward the side walls. For certain applications, particularly wet base boilers, a horizontal single port burner 386 CHAPTER 15 1956 Guide is utilized. This design produces a horizontal flame which strikes a curved baffle that spreads the flame in a fan shape. , ' Several power burners in domestic sizes are available. These are of gun burner design and feature small mechanical blowers for supplying all the air required for combustion. These are particularly desirable for handling restricted flue boilers or furnaces where an atmospheric burner cannot obtain the desired output. . . ' . Conversion burners for domestic application are available in sizes ranging from 50,000 to 400,000 Btu per hr capacity. It should be noted that the American Standard Approval Requirements are limited at present to con version burners of capacities up to 400,000 Btu per input hr. Burners of larger capacity, for use in large steel boilers, are usually engineered by a contractor specializing in this type of work, or by the local utility company. They are available in a large number of sizes and types. In some cases the burner may be an assembly of multiple burner heads filling the entire firebox. For conversion burner installation in boilers requiring more than 400,000 Btu per hr input, reference should be made to the American Standard Requirements for Installation of Gas Equipment in Large Boilers, ASA Z21.33-1950. Domestic sizes of conversion burners should conform to American Stand ard Listing Requirements of Conversion Burners, ASA Z21.17-1948. As the successful and safe performance of a gas conversion burner depends on numerous factors other than those incorporated in such equipment, instal lations of this kind must be made in strict accordance with American Standard Requirements for Installation of Domestic Gas Conversion Burn ers, ASA Z21.8-1948. Also, draft hoods conforming to American Standard Listing Requirements for Draft Hoods, ASA Z21.12-1937, R 1950, should be installed (in place of the dampers used with a solid fuel) on all boilers and furnaces intended to operate without chimney draft. The A.G.A. lists the output efficiency of conversion burners at 72 percent. This value is based on average installations and average heating equipment perform ance. One form of central heating system is the warm air floor furnace.5 The use of these furnaces is adaptable to mild climates, or for auxiliary heating or heating of single rooms in colder climates. They are used for heating first floors, or where heat is required in only one or two rooms. A number may be used to provide heat for the entire building where all rooms are on the ground floor, thus giving the heating system flexibility. In floor-furnace applications, the heating element, gas piping, and flue vent piping are suspended below the floor, and the only part in the room being heated is the circulating air register which may be of the single-type installed in the floor, or of the dual-type installed in a partition, and heating two rooms. The A.G.A. rating of floor furnaces is based on an efficiency of 70 percent. A recent type of central heating, used in mild climates, is the recessed. heater which is either a gravity or forced-air furnace designed for installa tion in the interior partition of a building, and having stub ducts conduct ing air to two or more rooms. This type of heater is usually installed in new homes, and is plastered into the wall, becoming a permanent part of the building. . Space Heaters Space heaters are defined as heating units that take the air for com bustion from the space being heated. They may be broadly classified as room heaters and unit heaters,. Automatic Fuel Burning Equipment 387 Room healers are used for heating single rooms or connecting rooms with good circulation between them and, except for wall-type heaters, they are semi-portable. Unvented-type room heaters should not be used unless space is properly ventilated to prevent excess moisture and to provide sufficient combustion air to prevent formation of carbon monoxide. All types of room heaters are capable of automatic control, although they are generally controlled manually. When equipped for automatic control, they must have an automatic pilot as part of the control equipment. Room heaters may be classified as follows: Circulators, vented and unvented, are small warm air furnaces that heat the room mainly by convection, although some have radiants over the burner, with windows in the front to allow some heat by radiation. Radiant heaters, usually unvented, although some vented types are avail able, have a refractory directly above the burners which is heated to in candescence, and gives off at least 30 percent of its heat in the form of radiant energy. Gas-fired steam and hot water radiators, vented and unvented, are similar . in appearance to an ordinary steam or hot water radiator, but are self- contained, and the gas input is controlled by steam pressure or water tem perature within the radiator. Warm air radiators are vented pr unvented circulators whose heating elements are constructed in the form of a steam radiator. Wall heaters, vented or unvented, are usually a type of radiant heater constructed with sufficient insulation (either solid or circulating air) to prevent overheating of the casing, and are built into a wall with the front flush with the wall surface. , The A.G.A. rating of room-type heaters is based on an efficiency of 70 percent. Unit heaters are used extensively for heating large spaces such as stores, garages, and factories. These heaters consist, of a burner, heat exchanger, fan for distributing the air, draft, hood, automatic pilot, and controls for burners and fan. They are usually mounted in an elevated position from which the heated air is directed downward by louvers. Some unit heaters are suspended from the ceiling, and others are free-standing floor units of the heat tower type. Unit heaters are classified for use with, or without, ducts depending on specific A.G.A. approval. When connected to ducts they must have sufficient blower capacity to deliver an adequate air quan tity against the duct resistance. ' Duct furnaces are usually of the unit heater type without the fan, and are used for heating air in existing duct systems where blowers are pro vided for moving the air through the system. Duct furnaces are tested for operation at much higher static pressures than are obtained in unit heaters. Combustion Process and Adjustments Most domestic gas burners are of the atmospheric injection (Bunsen) type in which primary air is introduced and mixed with the gas in the throat of the mixing tube. For normal operation of most atmospheric type burners, 40 to 60 percent of the theoretical air as primary air will give best operation. Slotted port and ribbon burners may require from 50 to 80 percent primary air for proper operation. The amount of excess air required in practice depends upon several factors, notably:.uniformity of air distribution and mixing, direction of gas travel from burner, and the height and temperature of combustion chamber; With power type burners utilizing motor driven blowers to provide both primary and secondary air, the excess air can be closely controlled while securing proper combustion 388 CHAPTER 15 ' 1956 Guide Secondary air is drawn into gas appliances by natural draft. As with other fuels, excess secondary air constitutes a loss, and should be reduced to a proper minimum; which usually cannot be less than 25 to 35 percent, if the appliance is to meet ASA approval requirements. Yellow flame burners depend upon secondary air, alone, for combustion. The flame produced by atmospheric injection, burners is non-luminous. Air shutter adjustments for manufactured gas should be made by closing the air shutter until yellow flame tips appear, and then by opening the air shutter to a final position at which the yellow tips just disappear. This type of flame obtains ready ignition from port to. port, and also favors quiet flame extinction. When burning natural gas, the air adjustment is generally made to secure as blue a flame as is obtainable without lifting of flames from burner ports. Manufacturers' instructions for burner ad justment should be followed. . Gas designed equipment does not usually incorporate any means for varying the secondary air supply (and hence the COz). The amount of effective opening and baffling is determined by A.G.A. tests and cannot be varied. Gas conversion burners, however, do incorporate means for con trolling secondary air to permit adjustment over a wide range of inputs according to the type of installation encountered. The manufacturer's specific instructions contained in the installation manual required to be supplied with each burner should be followed. It is possible through the use of suitable indicators to determine whether carbon monoxide is present in flue gases. Carbon monoxide should not exceed 0.04 percent when operating at the maximum gas input to the burners. During recent years, the use of fuel gas (natural, manufactured, and liquified petroleum) has become increasingly popular for heating tourist cabins and motels. Due largely to the intermittent use of such equipment and the fact that so many of the users are entirely unfamiliar with the fundamentals governing its operation, many special and unusual problems arise. The importance of safe-guarding the public interest has prompted some state and city officials to adopt and enforce legislation governing not only the manner in which these appliances are installed but the extent to which they must be equipped with reliable safety devices, for example, connection to an effective flue is mandatory. Furthermore, all such heating equipment must incorporate an automatic ignition pilot which will shut off gas supply to the main burner or burners in the event of pilot outage. If liquified petroleum gas is used, the automatic pilot must cut off all gas supply to the appliance, including the pilot burner, in case the pilot flame becomes extinguished. Ratings for Gas Appliances Input rating for a gas appliance is established by demonstrating that the appliance can meet the Approval Requirements of the ASA. The tests are conducted at the A.G.A. Laboratories. Output rating is deter mined from the approved input and an average efficiency stated in the: Approval Requirements, and is the heat available at the outlet. Sizing Gas-Fired Heating Plants Although gas-burning equipment usually is completely automatic, maintaining the temperature of rooms at a predetermined figure, there are some manually controlled installations. In order to overcome effec tively the starting load and losses in piping, a manually-controlled gas Automatic Fuel Burning Equipment 389 boiler should have an output as much as 100 per cent greater than the equivalent standard radiation which it is expected to serve. Boilers under thermostatic control, however, are not subject to such severe pick-up loads and consequently, it is possible to use a lower selec tion factor. For a gas-fired boiler or furnace under thermostatic control, a factor of 20 to 25 percent is usually sufficient for pick-up allowance. . In those installations, in mild climates where 100 per cent outside air is used, furnaces should be of larger size in order to provide adequate capacity and quick pick-up under intermittent heating conditions. The factor to be allowed for loss of heat from piping will vary somewhat,, the proportionate amount of piping installed being greater for small installations than for large ones. For selection factors to be added to installed radiation under thermostatic control, see Chapter 16. . Table 1. Capacity op Gas Piping Length of Pipe m Feet * .Nominal Diameter of Pipe in Inches , ... 2 Capacity--Cu Ft Per Hr with a 0.6 Sp Gr Gas and Pressure Drop of 0.3* Water Column 15 . ' 30 45 60 . . 75 ' 90 105 120 150 180 '~172 120 99 86 77 70 65 345 241 199 173 155 141 131 120 , 109 100 750 535 435 380 345 310 285. 270 242 225 850 700 610 545 490 450 420 380 350 920 .860 780 720 Appliances used for heating with gas should bear the approval seal of the A.G.A. Laboratories on the manufacturer's nameplate, together with the official input and output- ratings. It is not permissible to operate a gas heating unit above its stated rating. It. may be necessary to operate below this rating at elevations above 2000 ft, unless the appliance has been tested and approved for operation at altitudes up to 5200 ft, in which case such approval will be shown on the manufacturer's nameplate. Installa tions should be made in accordance with recommendations shown in the publications of the American Gas Association. Controls Temperature controls for gas burners are described in Chapter 39. Some central heating plants are equipped with push-button or other manual control. The main gas valve may be of either the snap action or throttling type. Automatic electric ignition is available. Sizing of Gas Piping . Piping for gas appliances should be of adequate size, and so installed as to provide a supply of gas sufficient to meet the maximum demand without undue loss of pressure between the point of supply (the meter) and the burner. The size of gas pipe required depends upon the following: 1- Maximum gas consumption to be provided. 390 CHAPTER 15 \ 1956 Guide: 2. Length of pipe and number of fittings. 3. Allowable loss in pressure from the outlet of the meter to the burner. 4'. Specific gravity of the gas. , To obtain the cubic feet per hour of gas required by the burner, divide the Btu input at which the burner will be adjusted, by the average Btu heating value per cubic foot of the gas. Capacities of different sizes and lengths of pipe, in cubic feet per hour, with a pressure drop of 0.3 in. of water column for a gas of 0.60 sp gr' are shown in Table 1. In adopting a 0.3 in. pressure drop, due allowance for an ordinary number of fittings was made. To convert the figures given in Table 1 to capacities for another gas of different specific gravity, multiply the tabular values by the multipliers shown in Table 2. Table 2. Multipliebs fob Vabious Specific Gravities For Use With Table l Specific Gravity Multiplier Specific Gravity ' Multiplier .35 .40 .45 .50 .55 .60 .65 .70 .75 .80 .85 .90 1.31 1.23 1.16 1.10 1.04 1.00 .962 .926 .895 .867 .841 .817 1.00 1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00 2.10 '.775 .740 .707 .680 . .655 .633 .612 .594 .577 .565 .547 .535 ' COMMERCIAL AND INDUSTRIAL GAS EQUIPMENT No attempt can be made, due to space limitation, to describe or classify the varied types of equipment used for commercial and industrial applica tions. Much of the equipment utilized is custom built to suit a particular process. Certain standard parts such as venturi and burner head sets, ring burners, proportional mixers, or compressors, are purchased for as sembly in existing equipment, usually by the installer. Furnaces to pro vide particular atmospheres or for annealing, soaking pits, metal melting, etc. are usually engineered by industrial gas equipment manufacturers. Burners utilized in industrial equipment often operate at gas pressures higher than encountered in domestic usage. High pressure gas provides flexibility of control required in the production of constant temperatures. In addition, air-gas ratios can be closely maintained under throttling condi tions, and heat liberation per cubic foot of combustion space is considerably greater than can be achieved with lower pressures. : A few of the many basic types of burners used are as follows: single-pipe high pressure, proportional mixing, pre-mix, two-pipe high pressure, and atmospheric. The single-pipe high pressure burner system utilizes gas delivered to the orifice of a venturi at pressures from 10 to 50 psig. A constant pressure compressor, sometimes remotely placed, is occasionally used to increase the v^--- Automatic Fuel Burning Equipment 391 . gas pressure. The velocity of the gas issuing from the orifice entrains primary air which is controlled by an air shutter on the venturi tube. An advantage of this system is that when the gas pressure is reduced (lowering the input) the air-gas ratio will remain constant over a fairly wide range. In the proportional mixing burner, an enclosed type venturi is used and high pressure air is delivered through an orifice. The resulting partial vacuum entrains the gas which is supplied through a zero pressure governor. When the air pressure is reduced, the amount of gas entrained is similarly reduced, thus maintaining a constant air-gas ratio over a side fuel capacity range. , ' Thp pre-mix burner system embodies a compressor which mixes air and gas intimately and discharges the mixture through pipes to the burners GROSS OUTPUT- THOUSAJ 6 T.U-PtR HOUR r - ir r--i-----i----1 i i-----r--"i---- -----1--- ------'-- i------i--------- r"'T - 02 4 6 B 10 12 W 18 20 GROSS OUTPUT' HUNDRED FEET STEAM RADIATION i --r i--\ t--i--r i r- 'I--i--i--i--i--r--j--i--i--r--i--i--r--i--i--i--i--i r-i i i i i " 0 5 tO 15 20 25 . 30 GROSS OUTPUT * HUNDRED FEET WATER RADIATION Fig. 21. Coal Fuel Burning Rate Chabt where it is discharged through orifices and burned. The pre-mix compres sor can be remotely installed and the mixture can be closely controlled. The two-pipe high pressure burner system utilizes both air and gas under pressure, both being delivered through orifices and mixed prior to delivery to the burner. ' The atmospheric burner system is not commonly used. It consists of a burner supplied with gas at a pressure of 2 to 12 in. water. A portion of the air or primary air required for combustion is entrained from the atmosphere by the stream of gas issuing from an`orifice, and the air-gas mixture is delivered through a venturi mixing tube to the burner head and parts. About 40 to 60 percent of the air required for combustion is in the form of primary air and the remainder, known as secondary air, is supplied from the air surrounding the flame. Each system embodies characteristics essential for certain applications It is strongly recommended that proper and qualified engineering authors ties be consulted prior to the purchase, installation, or operation of indus trial gas equipment. - Lh:' 392 CHAPTER 15 1956 Guide 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1i------,------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ----- --""i------ ------- ----- r--i------ ------- ------r" 0 2 4 6 S 10 12 14 16 18 20 GROSS OUTPUT - HUMORED FEET STEAM RAOIATION r--i--i--i--i--i--i--i--i--i--r--i--i--i--i--i--i--i--i--i--r--i--I--I--I--I--I--I--I--I--I--I-- 0 5. K> 15 20 25 30 GROSS OUTPUT - HUNDRED FEET WATER RADIATION Pig. 22. Oil Fuel Burning Rate Chart* * This chart is based upon No. 2 oil having a h^t.content of 143,400 Btu per gallon. If other grades of oil are used multiply the value obtained from this chart by the following factors: No. 1 oil (139,000 Btu per gallon) 1.032; No. 4 oil (144,500 Btu per gallon) 0.992; No. 5 oil (146,000 Btu per gallon) 0.982; and No. 6 oil (150,000 Btu per gallon) 0.956. - .; li' i-T-i 0 -GROSS OUTPUT * HUNDRED FEET STEAM RADIATION i i--i--i--i- i i" r ----i--i -r i--i--i--i--i i i i n--i--i--i--r--r 5 10 S 20 25 30 GROSS OUTPUT'HUNDRED FEET WATER RADIATION Fig. 23. Gas Fuel Burning Rate Chart Automatic Fuel Burning Equipment 393 FUEL BURNING RATES The burning rate for automatic fuel burning devices is determined by the gross heat output required of the boiler, or furnace, to carry the net heating load, plus allowances for system losses and pick-up. General values for these allowances have been given in preceding text. Detailed information for piping and pick-up allowances for steam and hot water systems, is given in Chapter 16, and for warm air systems, in Chapters 19 and 20. . When the gross output, operating efficiency, and heat value of the fuel are known, the required rate of burning can be determined by means of . Pigs. 21, 22 and 23 for the several fuels. . As the rate of fuel burning is directly proportional to the load for a given efficiency, these charts can be extended by moving the decimal points the same number of digits in both vertical and horizontal scales. The correct fuel burning rate can be determined directly from the several charts for oil or gas burning installations, as these customarily operate on a strictly intermittent basis. These fuel burning devices usually introduce the fuel at a single fixed rate during the on periods, and this rate should be sufficient to carry the gross load. In the case of coal stokers, which are usually capable of variable rates of firing, it is desirable to operate at as low a rate as weather conditions will permit, but the maxi mum firing rate of the stoker should be sufficient to carry the gross load. This rate may be determined by the same method as used for oil or gas. REFERENCES 1 Domestic'Burners for Pennsylvania Anthracite (Underfeed Type), (U. S. De partment of Commerce, National Bureau of Standards, Commercial Standard No. CS48-40). - * Stoker Manufacturers Association Manual: Industry Standards, Recommended Practices, Technical Information. Published by Stoker Manufacturers Association, 307 N. Michigan Ave., Chicago 1, 111. * Code for Determination of Rated Capacities of Anthracite Underfeed Stokers, adopted June 1,1944, and a Code for Determination of Rated Capacities of Bitumi- . nous Underfeed Stokers, adopted May 3, 1944. See Stoker Manufacturers Associa tion Manual. ' ` Automatic Mechanical Draft Oil Burners Designed for Domestic Installations (U. S. Department of Commerce, National Bureau of Standards, Commercial Standard No. CS75-42). Flue Connected Oil Burning Space Heaters Equipped with Vaporiz ing Pot Type Burners (U. S. Department of Commerce, National Bureau of Standards, Commercial Standard No. CS101-43). Warm-Air Furnaces Equipped with Vaporiz ing Pot-Type Oil Burners (.U. S. Department of Commerce, National Bureau of Stand ards, Commercial Standard No. CS104-46). Oil-Burning Floor Furnaces Equipped with Vaporizing Pot-Type Burners (U. S. Department of Commerce, National Bureau of Standards, Commercial Standard No. CS113-44). 1 Gas Floor Furnaces, Gravity Circulating Type (17. S. Department of Commerce, National Bureau of Standards, Commercial Standard No. CS99-42). BIBLIOGRAPHY Performance Expectancy of Domestic Underfeed Stokers for Anthracite, by Allen J. Johnson (Transactions, A.IMJB., Coal Division, Vol. 119, 1936). The Relation of the Size of Bituminous Coals to Their Performance on Small Underfeed Stokers--Burning Tests on Four Typical Coals, by R. A. Sherman, E. R. Kaiser and H. R. Limbacher, Technical Report No. 1, Bituminous Coal Research, ' Inc. (July, 1937) Part II. Oil Fuels and Burners, by James A. Moyer (McGraw-Hill). 394 CHAPTER 15 1956 Guide Handbook of Oil Burning, by Harry F. Tapp. Handbook of Oil Burning, by F. H. Faust, Editor-in-Chief, anil G. T. Kaufman, Editor (Oil Heal Institute of America, New York). Domestic Oil Burners, Installation and Servicing, by C. H. Burkhardt (McGraw- Hill Book Co., New York). , A Study of the Oil Burner as Applied to Domestic Heating, by Arthur H. Senner (Technical Bulletin 109, V. S. Department of Agriculture). Progress in Domestic Oil Heating, by Rene J. Bender (Mechanical Engineering, October, 1942). A.S.H.V.E. Research Report No. .907--Study of Performance Characteristics of Oil Burners and Low Pressure Heating Boilers, by L.' E. Seeley and E. J. Tavanlar (A.S.H.V.E. Transactions, Vol. 37, 1931, p. 517). A.S.H.V.E. Research Report No. 925--A Study of Intermittent Operation of Oil Burners, by L. E. Seeley and J. H. Powers (A.S.H.V.E. Transactions, Vol. 38, 1932, p. 317). Air Supply and Its Effect on Performance of Oil Burners and Heating Boilers, by L. E. Seeley, J. H. Powers and E. J. Tavanlar (A.S.H.V.E. Transactions, Vol. 39, 1933, p. 75). Study of Fuel Burning Rates and Power Requirements of Oil Burners in Relation to Excess Air, by L. E. Seeley and E. J. Tavanlar (A.S.H.V.E. Transactions, Vol. 40, 1934, p. 319). . Oil Burning in Residences, by D. W. Nelson (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 355). .^ A Study of Oil-Fired Heating Boilers, by R. C. Cross and W. R. Lyman (Heating and Ventilating, October, 1931). Gaseous Fuels (American Gas Association). Comfort Heating (American Gas Association). American Standard Approval Requirements for Central House Heating Gas Ap pliances, ASA Z21.13- (American Standards Association). Vol. I. Steam and Hot Water Boilers, Z21.13.la-1954. Vol. II. Gravity and Forced Air Central Furnaces, Z21.13.2-1951, with addenda Z21.13.2b-1954. Vol. III. Gravity and Fan Type Floor Furnaces, Z21.13.3-1951 with addenda, Z21.13.3a 1954. Vol. IV. Gravity and Fan Type Vented Recessed Heaters, Z21.13.4-1953 with addenda Z21.13.4a, 1954. American Standard Requirements for Installation of Domestic Gas Conversion Burners, ASA Z21.8-1948 (American Standards Association). American Standard Requirements for Installation of Gas Equipment in Large Boilers, Z21.33-1950 (American Gas Association). American Standard for Installation of Gas Piping and Gas Appliances in Build ings, Z21.30-1954 (American Gas Association). 1951 A.G.A. Industrial Gas School Lectures (American Gas Association). Radiant Gas Burners, by J. D. Keller, A.G.A. Sales Conference, 1949 (American Gas Association). Industrial Furnaces, Vol. 1 & 2, by W. Trinks. (John Wiley & Sons, 1944). A Method for Determining Fuel Burning Rates in Heating Boilers Fired by Auto matic Devices, by R. C. Cross (Heating and Ventilating, January, 1932). Heat Losses and Efficiencies of Fuels in Residential Heating, by R. A. Sherman and R. C. Cross (A.S.H.V.E. Tanrsactions, Vol. 43, 1937, p. 185). CHAPTER 16 HEATING BOILERS, FURNACES, SPACE HEATERS BOILERS: Construction, Types, Design Considerations, Rating and Testing Codes, Efficiency, Rating, Selection, Space Limitations, Connections and Fittings, Erection, Operation and Maintenance. FURNACES: Types, . Materials and Construction, Ratings, Testing and Rating Codes, Efficiency, Design Considerations, Humidification Equipment. SPACE HEATERS: Types: Solid Fuel, Oil, Gas; Materials ' and Construction, Testing- and Rating, Design Considerations, Installation . IN presenting the subject of Boilers, Furnaces and Space Heaters this chapter is divided: into three parts; the first dealing with boilers, the second treating warm air furnaces, and the third covering space heaters. HEATING BOILERS . Steam and hot water boilers for low pressure heating are built of steel or cast-iron in a wide variety of types and sizes, many of which are illus trated in -the Catalog Data Section. - The nationally recognized code governing the construction of low-pres sure steel and cast-iron heating boilers is the ASME Boiler Construction Code for Low Pressure Heating Boilers. Some states and municipalities have their own codes which apply locally, but these are usually patterned after the ASME Code. . ... The maximum allowable working pressures are limited'by the ASME Code for Low Pressure Heating Boilers to 15 psi for steam and 160 psi for hot water heating boilers, with a maximum temperature limitation of 250 F. Hot water boilers are generally designed for a working pressure of 30 psi and may be supplied for higher working pressures, for either heating purposes or for hot water supply, only when designed, tested and stamped for the higher pressure. TYPES OF HEATING BOILERS Heating boilers are classified:in a number of different ways, such as: 1. According to materials of construction. These are steel and cast-iron. Veryfew non-ferrous boilers are made. 2. According to the fuels for which the boilers are designed. These are coal, handfired or stoker-fired; oil; gas; or wood. Some boilers are designed specifically for one fuel, but many boilers are designed for more than one fuel. 3. According to the specific purpose or application for which the boiler is used, such as space heating or domestic hot water supply. 4. According to the design or construction of the boiler such as sectional, round, fire-tube, water-tube, magazine feed, Scotch, etc. ' Cast-Iron Boilers Cast-iron boilers are generally classified as: 1. Sqdare or rectangular boilers with vertical sections and rectangular grates, commonly known as sectional boilers. ' 2. Round boilers with horizontal pancake sections and circular grates. 395 396 CHAPTER 16 - %V y 1956 Guide ^ Cast-iron boilers are usually shipped in sections, and assembled at the place of installation. However some small boilers are shipped factory assembled. In the majority of boilers the sections are assembled with push nipples and tie rods but external headers and screw nipples are also used successfully. Many sectional boilers are provided with large push nipples at top to permit the circulation of water between adjacent sections at both the water line and bottom of the boiler, which is necessary to enable the use of an indirect water heater with the boiler for summer-winter hot water supply. Round and sectional boilers may be increased in size by the addition of sections and corresponding plate work. Small sectional type boilers are available with wet-base construction, wherein the ashpit or combustion chamber sides and bottom are sur rounded by extensions of the water legs of the boiler sections, and thus no separate base is required. This type of construction permits the boiler to be set directly on a wood or composition floor without danger of fire. The wet-base also provides some additional heating surface. Capacities of cast-iron boilers range generally from capacities required for small residences up to about 12,000 sq ft of steam radiation but boilers are made with capacities up to approximately 32,000 sq ft E.D.R. ' ' `. Steel Boilers Steel boilers may be of the fire-tube type, in which the gases of combus-. tion pass through the tubes and the boiler water circulates around them, or of the water-tube type, in which the gases circulate around the tubes and the water passes through them. Either the fire-tube or water-tube type may be designed with integral water jacketed furnaces, or arranged for refractory lined brick or refractory lined jacketed furnaces. Those with integral water jacketed furnaces are called portable firebox boilers, and are the most commonly used type. They are usually shipped in one piece, ready for piping connections. Refractory furnaces are usually^ installed in refractory lined furnace boilers after they are set in place. Capacities of steel boilers range from those required for small residences up to about 50,000 sq ft E.D.R. (steam). Boilers for Special Applications One of these is known as the magazine feed boiler developed for the burning of small sizes of anthracite and coke, and has a large fuel carrying capacity, which results in longer firing periods than would be the case with 4 the standard types burning coal of buckwheat size. Special attention must be given to proper chimney sizes and connections in order to insure adequate draft. Boilers for hot water supply are classified as direct, if the water heated passes through the boiler, and as indirect, if the water heated does not come in contact with the water or steam in the boiler. Direct heaters are built to operate at the pressures found in city supply mains, and are tested at pressures from 200 to 300 lb per square inch. The life of direct heaters depends almost entirely on the scale-forming properties of the water supplied and the temperatures maintained. If low water temperatures are maintained, the life of the heater will be much longer due to decreased scale formation and minimized corrosion. Direct water heaters in some cases are designed to burn refuse and garbage. Indirect heaters generally consist of steam boilers in connection with heat exchangers of the coil or tube types which transmit the heat from the : Heating Boilers, Furnaces, Space Heaters 397 steam to the water. This type of installation has the following advantages: 1. The boiler operates at low pressure. 2. The boiler is protected from scale and corrosion. 3. The scale is formed in the heat exchanger in which the parts to which the scale is attached, can be cleaned or replaced. The accumulation of scale does not affect efficiency, although it will affect the capacity of heat exchanger. 4. Discoloration of water may be prevented if the water supply comes in contact with only non-ferrous metal. Where a steam or a forced circulation hot water heating system is in stalled, the domestic hot water may be heated by an indirect heater at tached to the boiler. For most satisfactory performance in the steam system, this heater is placed just below the water line of the boiler. In a forced circulation hot water system, it should be located as high as pos sible with respect to the boiler.. BOILER DESIGN CONSIDERATIONS Furnace Design Good efficiency and proper boiler performance are dependent on correct furnace design. There must be sufficient volume for burning the particular fuel which is used, and means to obtain a thorough mixing of air and gases at a high temperature and at a velocity low enough to permit complete combustion of all the volatiles. For hand-fired boilers, the furnace volume should be large enough to hold sufficient fuel for reasonably long firing periods. (See Chapters 14 and 15.) Heating Surface Boiler heating surface is that portion of the surface of the heat transfer apparatus in contact with the fluid being heated on one side and the gas or refractory being cooled on the other side. Heating surface on which the fire shines, is known as direct or radiant surface, and that in contact with hot gases only, as indirect or convection surface. The amount of heating surface, its distribution, and the temperatures on either side thereof, in fluence the capacity of any boiler. Direct heating surface is more valuable than indirect per square foot because it is subjected to a higher temperature and also, in the case of solid fuel, because it is in position to receive the full radiant energy of the fuel bed. The effectiveness of the heating surface depends on its cleanliness, its location in the boiler, and the shape of the gas passages. The area of the gas passages must not be so small as to cause excessive resistance to the flow of gases, where natural draft is employed. Inserting baffles so that the heating surface is arranged in series with respect to the gas flow, in creases boiler efficiency and reduces stack temperature, but increases the draft loss through the boiler. Heat Transfer Rate . Practical average overall heat transfer rates, expressed in Btu absorbed per square foot of surface per hour, will average about 3300 for hand-fired boilers, and 4000 for mechanically-fired boilers when operating at design load. When mechanically-fired boilers are operating at maximum load, as defined in this chapter under heading Selection of Boilers, these values will run. between 5000 and 6000. Boilers operating under favorable con ditions at these heat transfer rates, will give exit gas temperatures that 398 CHAPTER 16 . 1956 Guide are considered consistent with good practice, although there are boilers which have high efficiencies and also operate at higher transmission rates. RATING AND TESTING CODES Heating boilers are usually rated according to codes developed by the Steel Boiler Institute, the Institute of Boiler and Radiator Manufacturers, the American Gas Association, and the Heating, Piping and Air Condition ing Contractors National Association, whose test codes have been prepared specifically for the purpose of obtaining information required for estab lishing acceptable ratings. In view of the preference of industry for the above codes, consideration is being given to the withdrawal of the follow ing five Society codes for determining efficiency and performance char acteristics : ASHVE Standard and Short Form Heat Balance Codes for Testing Low-Pressure Steam Heating Solid Fuel Boilers--Codes 1 and 2---(Revi sion of June, 1929).1 . ASHVE Performance Test Code for Steam Heating Solid Fuel Boilers-- Code No. 3--(Edition of 1929).! The ASHVE Standard Code for Testing Steam Heating Boilers Burning Oil Fuel, (Adopted June, 1938).3 The ASHVE Standard Code for Testing Stoker-Fired Steam Heating Boilers, (Adopted June 1938 ;4 also adopted by the Stoker Manufacturers Association, 1938). ' The various current rating and testing codes will be discussed in follow ing paragraphs in which limitations, methods of application, and resulting ratings will be described. , The Steel Boiler Institute has adopted a rating code for boilers designated Table 1 Steel Boilers and Table 2 Steel Boilers and a testing code for Oilfired Table 2 Steel Boilers (SBI Rating Code, Sixth Edition, July 1954). Tables 1 and 2 of this chapter show the SBI ratings of these two classes of boilers. The Table 1 boilers (defined as those having 129 to 3571 sq ft of heating surface and formerly designated as Commercial boilers) are rated in square feet E.D.R. (steam) on the basis of heating surface with limitations set for grate area, furnace volume, and furnace height. The. Table 2 boilers (defined as those having not more than 294 sq ft of heating surface and formerly designated as Residential boilers) are rated from tests of oil-fired boilers, with limitations in relation to heating surface and testing conditions. Stoker-fired and gas-fired Table 2 boilers are rated (SBI Net Rating) not in excess of the oil-fired rating. Hand-fired Table 2 boilers are rated (SBI Net Rating) not greater than fourteen times the heating surface. The Institute of Boiler and Radiator Manufacturers has adopted a code5 for rating cast-iron heating boilers, based upon performance obtained under controlled test conditions. This code applies to all sectional cast- iron heating boiler except those of magazine-feed type. The Gross I=B = R Output is obtained by test, and is subject to cer tain limiting factors. For hand-fired boilers, the number of boilers of a series to be tested, the minimum overall efficiency, the minimum time limit (the time an Available Fuel Charge will last when burned at a rate which will produce the Gross I = B = R Output), the chimney area and height, and the draft in the stack are all subject to the limits established in the code. Tests are run using anthracite coal of standard specification. Bituminous coal and.coke ratings are the same as for anthracite. For automatically-fired boilers, the number of boilers of a series to be Heating Boilers, Furnaces, Space Heaters (a) Steam R eturn I.P.S. In. (18) o -- 0. < F 1 =2 coO-i V v.- M) M inim um G ra te SAqreFat (18) *** * nnn '**". -*> <0<0< t OOOOCO CO OO CD OCOOO CMCMrM mi-nn ooo -- ---H --*>cm cm CnMoCMoCoO CeOdCcO^ ^-- r-orl cd~-`^ 8.000. 000 9,000,000 10,COO,000 4.000. 000 5.000. 000 8.000. 000 7.000. 000 2.500.000 3.000. 000 3.500.000 1.400.000 1.700.000 2,000,000 8,000 1 1,200,000 6,870 1 1,000,000 900,000 600,000 700.000 800.000 360.000 439.000 821.000 " ------------------- 4.000 4,670 5.330 2,400 2,630 3,470 S B I N e t R ating 9.600.000 10,800,000 12,000,000 4.800.000 18.670 6.000. 000 20,830 7.200.000 25,000 8.400.000 29,170 3.000. 00100,420 16.700 3.600.000 12,500 20,000 4.200.000 14,580 23.330 -2 ST o H ccorJsSjc 5 a " cJ~cd z . | ^CD 1.500 1.830 2.170 2.500 2,920 3.330 3,750 4.170 5,000 6.000 5.830 9.330 7,080 11.330 8.330 13.330 26.670 33.330 40.000 46.670 33,330 37,800 41.670 53,300 60.000 86.700 .3 8 -5 1.680.000 2.040.000 2 ,4 0 0 ,0C0 6.000 9.600 1.440.000 1,200,000 4.500 7,200 1,080,000 720.000 840.000 660.000 432.000 528.000 624.000 B tu'P er Hr (12) c aj mto 2sob 5 <->- Sq F t W ater (11) (01) U bS 2,880 3,520 4,160 4,800 5.600 6,400 5.000 ; 8.000 , 7,000 11,200 8.500 1 13,600 10,000 16,000 12.500 20,000 15.000 24.000 17.500 28.000 40.000 45.000 50.000 20.000 25.000 30.000 35.000 3.000 3.500 4.000 1,800 2,200 2,600 * I S22 ~~ sli IIs SES SS3g fe-BSn 8c SSKZSj SocmS -H CM CM CMcd'cO ' "---------------- --.--------------------------- -------------------------- ` 5 *3 -.5 CMC4C4 S= 555 ,55 * CM CD CO CO CD CD MeScD S? 3 8 sxs gg ^ t S -8 2 32.000 40.000 48.000 58.000 64.000 72.000 80.000 (7) (8) <>> M inim um Furnace H eight In. , i ta p p in g aiz.bs s h o w n fo r h o iltPO k a u tn a 19O Krtft 346.9 390.3 433.Q 11,657,000. 40.000 64.000 9.600.000 13.114.000 45.000 72.000 10,800,000 14.570.000 50.000 80.000 12,000,000 4.800.000 173.5 6.000. 000 216.9 7.200.000 260.3 8.400.000 303.6 3.000. 000108.5 3.600.000 130.2 4.200.000 151.8 60.8 73.8 86.8 43.5 62.1 1.680.000 2.040.000 2.400.000 1,200,000 1.440.000 1.313.000 4.500 7,200 1,080,000 39.1 26.1 30.4 34.8 15.7 16.2 22.6 M ini mum Furnace VCouluFmte (o) , . 720.000 840.000 960.000 432.000 528.000 624.000 20.000 25.000 30.000 35.000 3.643.000 12.500 20,000 4.373.000 15.000 24.000 5.100.000 17.500 28.000 5.000 8,000 6.000 l 9,600 3.000 4.600 3.500 5.600 4.000 l 6,400 Sq F t Sq F t Steam Water (4) [ (8) aQ BJ te _c "3 d zZ < X 5 S s B tu Per H r (8) 2,880 3,520 4,160 11,200 13,600 16,000 32.000 40.000 48.000 56.000 * 4o ta _52TM >= & 3 7.000 8.500 10.000 1,800 2,200 2,600 5.830.000 7.286.000 8.743.000 10,200,000 2.040.000 2.479.000 2.916.000 1.450.000 1.760.000 876.000 1,020.000 1,166,000 520.000 643.000 758.000 B tu Per Hr (3) Sq F t W ater (2) S B I R ating S55.Scm.SS. m8St. 2i**2P"S** 2O2cj2'c oCMDo--Oo ""S 222 SgS t0o0*ro0-cCoMcoOo o g'SSS SS5S co2~ = _a JfSrS.t *3 : S | ill 111 Ss SSS ggs gggg ess Z VON iBcd-' --CM CM CMCDD-S SSt- C*ocd mvm- ooo'cf m'"o'o`W-- CM CD CD ^ tn'Vo ^5 W 400 CHAPTER 16 1956 Guide ciency, the draft loss through the boiler, and the heat release in the com bustion chamber are subjected to limitation by the code.6 Oil-fired boiler ratings are established by tests using gun-type oil burners and commercial grade No. 2 fuel oil. Stoker-fired ratings are based on the Gross I--B = R Output obtained by oil-fired tests. Gas-fired ratings for boilers having gross outputs greater than 300,000 Btu per hour, where no A.G.A. Rating is published, are based on the Gross I--B=R Output obtained by oil-fired tests. Gas-fired ratings for boilers having gross outputs less than 300,000 Btu per hour, where no A.G.A. Rating is pub lished, are established by gas-fired tests with atmospheric, single-porttype burners using natural or manufactured gas or a mixture of these two Tabus 2. SBI Net Rating Data fob Table B Steel Boilers--Oil-Fired* . SBI Net Rating SqFt (1) 275 320 400 550 Steam Btuh (2) 66,000 77,000 96,000 132,000 Water Btuh (3) ' 74,000 87,000 108,000 149,000 Minimum Furnace Volume Cu Ft Minimum Heating Surface Sq Ft (4) 2.5 . 2.9 3.6 5.0 (5) 16' 19 24 32 700 900 1100 168,000 216,000 264,000 189,000 243,000 297,000 6.4 8.2 10.0 41 53 65 1300 1500 1800 312,000 360,000 432,000 351,000 405,000 486,000 11.8 13.6 16.4 77 88 106 2200 2600 3000 528,000 624,000 720,000 594,000 702,000 810,000 20.0 23.6 27.3 129 153 177 3500 4000 4500 5000 840,000 960,000 1,080,000 1,200,000 945,000 1,080,000 1,215,000 1,350,000 31.8 36.3 40.9 45.4 206 236 265 294 Stoker-Fired and Gas-Fired SBI Net Rating not greater than oil-fired rating. Hand-Fired Net SBI Eating (Steam) not greater than 14 times the square feet of heating surface. gases. The. A.G.A. Output Rating of a gas-designed boiler may be used in determining the Net I = R = R Rating. The Net I=B--R Rating is determined from the Gross I = B-- R Output by applying specified Piping and Pickup Factors which range from 2.36 to 1.40 for hand-fired boilers, and from 1.56 to 1.288 for automaticallyfired steam boilers, and from 1.333 to 1.288 for automatically-fired hot water boilers. In all cases, the factor decreases as the boiler size in creases. Table 3 is abstracted from the 1951 I=B = R Boiler Rating Tables in the code and illustrates the relationship between Net I=B = R Rating and Gross I --B= R Output. . The American Gas Association rates gas-designed boilers at 80 percent of the A.G.A. Input Rating. These ratings are determined by per formance tests described in the A.G.A. Approval Requirements for Central Heating Appliances. The Heating, Piping and Air Conditioning Contractors National As sociation has adopted a method, based on their physical characteristics for T a b l e .3. I< = B = R B o il e r R a t in g a b le 1T Heating Boilers, Furnaces, Space Heaters 401 !|J J S"S=-Q2 s J I| .Sco<55 s 5P? <ycy< * a OOOOOO OOOOOO OOO........................... ` '&i : * an n*o *o ia *A eo n SSStSS q a) y h* oo 0^ SSKS5SS ok r- o *o o ***** SSg33 m m m. A A.. SSgSSS Rsfe 8 e$l ||cSo||*|SoS,o*?PyP*S2yo2yY"5yY2> oYCnOM^Nbwgi6iayQ na0Skcdo*eOemOc0o*c9YY* Oo(0o0oOoOoO(oOoOoOoOoO affouoBomMoSoIoHoeiiSA 2nm5Sm23S Pining and Pickup Factor 1 <* 2?C2?295r?2t2?2e5?2jw25?2 5t2<2i52e2:o22*2522*4o0 nnnen-ooceeoipM-c-OoYcoi ackyaScovpeaeottojccoo*cacoo*aacoo* aSooooaooooooooooSoaaoo mSSoamS 52222 oooo min mimS22m o'C^cqcq -* *o $ < t- co coo*oooy< <Za>0-" e w oy*en*jnwaooooo4 a S1 `"sssls Ies^rS*eg?oEooSto 8nSoSc2nSnSv Soe38n8eSoSo Soo2ooSe|*|o| |a|aa| l|05a* a3 I ' I** d Jjg -Sco< & S aOM oj? <s.$f >Y**0*0P,5 OiCldW<5 esook*-*^. W-Ic'lCgDNOrt-O-i Wcro-C^lopMy*W VOOOQION ttiar'Coon eocoCYY*eoc9 PSOOhN mill in 2 if SslliS sll I I0*00000 OOOC *000*00*0 OtQOtfiieO 3 I2I=I| I3! ||ihooco <<OeweOr*mNCt3YN Cr.D- s-ioi-a * - Em u < fe c a. ft* o cj co m as eo oy,y`>o^o oooooo oooooo Oh.or. *fWN"OC OOOOOO 0-000 OielO^YY --Y*--Y -- -- -- Y* Y*Y*Y`Y*Y*Y* Y* Y* Y* Y* Y* Y* oooooo o< OOOOOO o<_ *YY*Y*Y*Y*Y* . Y* Y* Y* 252222 --Ills 111 t2oa ^C7 cd du " 03 6 <8 O 3* 2S25S9ft2 sososoososos sosososososo IoIe y*y*y**oo ttaooNYi eo linnNO)oYH<e Uo3cC4oon---Y e-l O OooCoCKoJeK4JcYo - CO0)O*-*<4 ,YO"*.k.OO*C24sQ9ONO a .s ill ^ I NOOO)Y C*OY'ON YSinOOr(.fOnflOMaaOci9OdY0 .IO.Q..oI_O_c_Ny_V_y null 111NCJNNNC 402 CHAPTER 16 1956 Guide rating boilers that are not rated in accordance with the SBI or I=B=R Codes. Ratings are expressed on a Net Load basis in square feet of steam radiation. The HP&ACCNA, has also adopted a Testing and Rating Code for Boiler-Burner Units.6 The purpose of this Code is to provide a basis of rating commercial sizes of steel heating boiler-bumer units fired with oil or gas fuel. This code allows a higher rating than is permissible under the SBI Code. A gross output is established with certain limiting factors applying to flue gas temperature, carbon dioxide, efficiency and quality of steam. This output is divided by 1.5 to determine the net rating. BOILER EFFICIENCY The term efficiency, as used for guarantee of boiler performance, is usu ally construed as follows: ' 1. Solid Fuels. The efficiency of the boiler alone is the ratio of the heat absorbed by the water and steam in the boiler per pound of combustible burned on the grate, to the calorific value of 1 lb of combustible as fired. The combined efficiency of boiler, furnace and grate is the ratio of the heat absorbed by the water and steam in the boiler per pound of fuel as fired, to the calorific value of 1 lb of fuel as fired. 2. Liquid and Gaseous Fuels. Tkecombined efficiency of boiler, furnace and burner is the ratio of the heat absorbed by the water and steam in the boiler per pound or cubic foot of fuel, to the calorific value of 1 lb or cubic foot of fuel, respectively. The following efficiencies apply to current designs of boilers operated under favorable conditions at their gross output ratings. Some older boilers, designed primarily for hand firing, may have lower efficiencies when automatically fired. Anthracite, hand-fired....................................................................... 60 to 75 percent Bituminous coal, hand-fired.......................-.................................... 50 to 65 percent Stoker-fired............................................................................................ 60 to 75 percent Oil and gas-fired.................................................................................. 70 to 80 percent Higher efficiencies for hand-fired bituminous coal may be obtained by careful firing of either a regular or a smokeless boiler. RATING OF BOILERS In referring to boiler rating, it is necessary to know the basis on which the rating has been established in order to understand the exact meaning of the term. The following example will illustrate the meaning of three ratings which might be established for the same boiler. Assume that an installation has the following loads determined in accordance with the section Selection of Boilers: Net Load........................................................................ 1000sq ft of steam radiation Piping Tax.................................................................... 200 sq ft of steam radiation Design Load................................................................ 1200 sq ft of steam radiation Pickup Allowance...................................................... 240 sq ft of steam radiation Maximum or Gross Load.......................................... 1440sq ft of steam radiation A boiler that is just large enough to carry this system might be said to have a net load rating of 1000 sq ft, a design load rating of 1200 sq ft, or a gross load rating of 1440 sq ft, depending on the basis on which the boiler is rated. On a net load basis the boiler would be rated 1000 sq ft of steam radiation and would have sufficient excess capacity to supply the normal piping and pickup load. Net I=B -- R Ratings. SBI Net Ratings, and Net Load Heating Boilers, Furnaces, Space Heaters ' 403 Ratings of the Heating, Piping and Air Conditioning Contractors National Association are established on this basis. . On a design load basis the boiler would be rated 1200 sq ft of steam radia tion and would have sufficient excess capacity to supply the pickup load. It would be of adequate size for a system in which the sum of the net load and the piping heat loss did not exceed 1200 sq ft of steam radiation. The SBI Ratings shown in columns 1, 2, 3, 10, 11 and 12 of Table 1 (not to be confused with SBI Net Rating) are established on a design load basis. On a gross output basis of rating, the boiler would be rated 1440 sq ft of steam radiation and would be of adequate size for a system in which the sum of the net load, piping load, and pickup load did not exceed 1440 sq ft of steam radiation. Gross I-B=R Output and A.G.A. Ratings are established on a gross output basis. ' In the determination of boiler ratings, the Gross Output is the-quantity of heat available at the boiler nozzle, with the boiler normally insulated and when operating under limitations stipulated in the code or method by which the boiler is rated. The boiler may be capable of producing a greater nozzle output, but in doing so would exceed some of these limitations. ____ SELECTION OF BOILERS General Factors The Maximum Load or Gross Load on the boiler is the sum of the four following items. The Design Load is the sum of items 1, .2, and 3. The Net Load is the sum of items 1 and 2. 1. Radiation Load. The estimated heat emission in Btu per hour of the connected radiation (direct, indirect, or forced convection coils) to be installed. The connected radiation is determined by calculating the heat losses for each room in accordance with data given in Chapters 9,11 and 12. The sum of the calcu lated heat losses for all the rooms represents the total required heat emission of the connected radiation, expressed in Btu per hour. As practically all boilers are now rated on a Btu basis, it is unnecessary to convert the radiation load to square feet of equivalent direct radiation. 2. Hot Water Supply Load. The estimated maximum heat in Btu per hour re quired to heat water for domestic use. I = B = R recommends that allowance for hot water supply load be made only for bathrooms in excess of two, as follows: Instantaneous Coil 12,000 Btu per hour, and for Storage Tank installation 120 Btu per (hour) (gallon of tank capacity). For instantaneous coil installations the boiler capacity should not be less than required to heat 2 to 3 gal of water, 100 deg per min. See also Chapter 49. 3. Piping Tax. The estimated heat emission in Btu per hour of the piping con necting the radiation and other apparatus to the boiler. As the heating industry as a whole is not entirely agreed upon piping tax allowances for different sizes of installations, it is better to compute the heat emission from both bare and covered pipe surface in accordance with data in Chapter 28. In average house heating systems, it is common practice to consider the piping tax to be equal to 25 percent of the Net Load. In determining Net I -- B -- R Ratings from Gross I -- B = R Output, the piping factor allowed varies from 30 percent for small boilers to 12 percent for larger boilers. . l }^armin9~Up r Pick-Up Allowance. The estimated increase in the normal load in Btu per hour caused by the heating up of the cold system. The warming-up allowance represents the load due to heating the boiler and con tents to operating temperature, and heating up cold radiation and piping. Other items to be considered in boiler selection are as follows: 404 CHAPTER 16 1956 Guide 0. Efficiency with hard or soft coal, gas, or oil firing, as the case may be. ft. Grate area with hand fired coal, or fuel burning rate with stokers, oil, or gas c. Combustion space in the furnace. ' d. Type of heat liberation, whether continuous or intermittent, or a combination of both. e. Convenience in firing and cleaning. /. Adaptability to changes in fuel and kind of attention. . g. Height of water line. h. Miscellaneous items such as draft available, possibility of future extension, possibility of break-down, and head room in the boiler room. . 1. The most economical size of boiler is usually one that is just the right size for the load. Either larger or smaller boilers may be less economical. Cast-Iron Boilers Net toad ratings of cast-iron boilers are usually available from manu facturers' catalogs. They may also be obtained conveniently from pub lished tables of I=B = R ratings,7 or from recommendations of the Heating, Piping and Air Conditioning Contractors National Association,8 and can be used in selection of boilers, unless the heating system contains an unusual amount of bare pipe, or the nature of the connected load is such that the normal allowances for pipe loss and pickup do not apply. In such a case, the selection must be based on the gross output. Steel Heating Boilers SBI catalog ratings, in accordance with the previously mentioned Steel Boiler Institute code, are intended to correspond with the estimated design load. When the heat emission of the piping is not known, the net load to be considered for the boiler may be determined from Tables 1 and 2. The difference between design load and net load represents an amount which is considered normal for piping loss of the ordinary heating system. Boilers with less than 294 sq ft of heating surface and having SBI net ratings (steam) of not more than 5000 sq ft if mechanically fired and 4120 sq ft if hand-fired, are classified as Table 2 Steel Boilers, formerly Residential boilers. An insulated Table 2 boiler for oil, gas, or stoker firing may carry a net load expressed in square feet of steam radiation of not more than seventeen times the square feet of heating surface in the boiler, provided the boiler has been tested in accordance with the SBI Code for testing oil-fired steel boilers at output rates of 125, 150 and 175 percent of the steam SBI net rating. The SBI net rating for a water boiler, automatically fired, expressed in Btu per hour, is 270 times the Steam SBI net rating in square feet. The net water rating is 12}4 percent greater than the steam rating because a lower piping and pickup factor is generally required in a water system: The SBI net rating (sq ft steam) for hand-fired Table 2 boilers is not greater than fourteen times the heating surface. If the heat loss from the piping system exceeds 20 percent of the installed radiation, the excess is to be considered as part of the net load. Heating Surface and Grate Area Basis Where neither the net load nor gross output ratings based upon perform ance tests are available, a good general rule for conventionally designed boilers is to provide 1 sq ft of boiler heating surface for each 14 sq ft of equivalent radiation (240 Btu per sq ft) (hr) represented by the design Heating Boilers, Furnaces, Space Heaters .405 .load. This is equivalent to allowing 10 sq ft of boiler heating surface per . boiler horsepower. In this case it is assumed that the maximum load including the warming-up allowance will be provided for by operating the boiler in excess of the design load, that is, in excess of the 100 percent rating on a boiler-horsepower basis. SBI ratings for hand firing are based on 10 sq ft of heating surface per boiler horsepower. Due to the wide variation which may be encountered in manufacturers' ratings for boilers of approximately the same capacity, it is advisable to check the grate area required for heating boilers burning solid fuel by means of the following formula: " CXFxE ; (1) where G -- grate area, square feet. H -- required gross output of the boiler, Btu per hour (see Selection of Boilers). C = desirable combustion rate for fuel selected, pounds of dry coal per square foot of grate per hour (see Table .4). F = calorific value of fuel, Btu per pound. E = efficiency of boiler, usually taken as 0.60. Example 1: Determine the grate area for a required gross output of the boiler of 500,000 Btu per hour, a combustion rate of 6 lb per hour, a calorific value of 13,000 Btu per pound, and an efficiency of 60 percent. 500,000 G= = 10.7 sq ft 6 X 13,000 X 0.60 The boiler selected should have a grate area not less than that deter- mined by Equation 1. With small boilers, where it is desired to provide Table 4. Practical Combustion Rates for Coal-Fired Heating Boilers Operating at Maximum Load on Natural Draft of From i$ in. to J$ in. Water* . Kind of Coal Sq Ft Grate Lb of Coal peb Sq Ft Grate per Hour No. 1 Buckwheat Anthracite Up to 4 5 to 9 10 to 14 15 to 19 20 to 25 3 3l$ 4 41$ 5 Anthracite Pea Up to 9 10 to 19 20 to 25 '5 51$ 6 Anthracite Nut and Larger Up to 4 5 to 9 10 to 14 15 to 19 20 to 25 8 9 10 11 13 Butumifious Up to 4 5 to 14 15 and above 9.5 12 15.5 . * Steel boilers usually have higher combustion rates for grate areas exceeding 15aqft than those indicated m this table. 406 CHAPTER 16 1956 Guide sufficient coal capacity for approximately an eight-hour firing period plus a 20 percent reserve for igniting a new charge, more grate'area may be re quired depending upon the depth of the fuel pot. . Gas-Fired Boilers After determining the net load for the installation, gas designed boilers can usually be selected from manufacturers' tables of net load ratings which are based on piping and pickup allowances varying from 56 percent for small steam boilers and 33.3 percent for small hot water boilers to 28.8 percent for very large boilers. If the piping and pickup load or other factors create an unusual load., & boiler should be selected which has_ an A.G.A. output rating equal to the maximum output required. Detailed recommendations for selection of gas designed boilers are given in the A.G.A. publication, Comfort Heating.9 SPACE LIMITATIONS Boiler rooms should, if possible, be situated at a central point with respect to the building, and should be designed for a maximum of natural fight. The space in front of the boilers should be sufficient for firing, stok ing, ash removal and cleaning or renewal of flue tubes, and should be at least 3 ft greater than the length of the tubes. . A space of at least 3 ft should be allowed on at least one side of every boiler for convenience of erection and for accessibility to the various damp ers, cleanouts, and trimmings. The space at the rear of the boiler should be ample for the chimney connection and for cleanouts. With large boilers the rear clearance should be at least 3 ft in width. The boiler room height should be sufficient for the location of boiler accessories, and for proper installation of piping. In general, the ceiling height for small steam boilers should be at least 3 ft above the normal -boiler water line. With vapor heating, especially, the height above the boiler water line is of vital importance. CONNECTIONS AND FITTINGS Steam outlet connections should be the full size of the manufacturers' tappings, in order to keep the velocity of flow through the outlet reasonably low, and to avoid fluctuation of the water line and undue entrainment of moisture, and should extend vertically to the maximum height available above the boiler. A steam velocity in boiler outlets not exceeding 25 to 30 fps at maximum load is recommended, unless data are available to show that a higher velocity is satisfactory. See further data on pipe connections to boilers in Chapters 21 and 22 and in the ASME Boiler Construction Code for Low Pressure Heating Boilers. Where a return header is used on a cast-iron sectional boiler to distribute the returns to both rear tappings, it is advisable to provide full size plugged tees instead of elbows where the branch connections enter the return tap pings. This aids in cleaning of sludge from the bottom of the boiler sec tions through the large plugged openings. An equivalent cleanout plug should be provided in the case of a single return connection. Blow-off or drain connections should be made near the boiler, and so arranged that the entire system may be drained of water by opening the drain cock. In the case of two or more boilers separate blow-off connec tions must be provided for each boiler, on the boiler side of the stop valve on the main return connection. ' Water service connections must be provided, for both steam and water Heating Boilers, Furnaces, Space Heaters 407 boilers, for refilling and for the addition of make-up water to boilers. This connection is usually of galvanized steel pipe, and is made to the return main near the boiler or boilers. Fitting connections for pressure gage piping, water gage connections, and safety valves, should be made in accordance with the ASME Boiler Construction Code for Low Pressure Heating Boilers. Smoke Breeching and Chimney Connections. The breeching or smoke pipe from the boiler outlet to the chimney should be air-tight and as short and direct as possible, preference being given to long radius and 45-deg instead of 90-deg bends. The breeching entering a brick chimney should not project beyond the flue fining, and where practicable it should be grouted from the inside of the chimney. A thimble or sleeve usually is provided where the breeching enters a brick chimney. Where a battery of boilers, is connected into a breeching, each boiler should be provided with a tight damper. The breeching for a battery of boilers should not be reduced in size as it goes to the more remote boilers. Good connections made to a good chimney will usually result in a rapid response by the boilers to demands for heat. ERECTION, OPERATION, AND MAINTENANCE The directions of the boiler manufacturer should always be read before the assembly or installation of any boiler is started, even though the con tractor may be familiar with the boiler. All joints requiring boiler putty or cement, which cannot be reached after assembly is complete, must be finished as the assembly progresses. Five precautions that should be taken in all installations to prevent damage to the boiler are: 1. There should be provided proper and convenient drainage connections for use if the boiler is not in operation during freezing weather. _ 2. Strains on the boiler, due to movement of piping during expansion, should be prevented by suitable anchoring of piping, and by proper provision for pipe ex pansion and contraction. 3. Direct impingement of too intense local heat upon any part of the boiler sur face, as with oil burners, should be avoided by protecting the surface with firebrick or other refractory material. . 4. Condensation in steam systems must flow back to the boiler as rapidly and uniformly as possible. Return connections should prevent the water from backing out of the boiler. 5. Automatic boiler feeders and low water cut-off devices which shut off the source of heat if the water in the boiler falls below a safe level, are recommended for me chanically-fired boilers. Boiler Troubles A complaint regarding boiler operation generally will be found to be due to one of the following: 1. The boiler fails lo deliver enough heat. The cause of this condition may be: (a) poor draft; (f>) poor fuel; (c) inferior attention or firing; (d) boiler too small; (e) im proper piping; (/) improper arrangement of sections; (g) heating surfaces covered withsoofr; (h) insufficient radiation installed; and (t) with mechanical firing, fuel burning equipment too small. 2. The water line is unsteady. The cause of this condition may be: (a) grease and dirt in boiler; (6) water column connected to a very active section and, therefore, not showing actual water level in boiler; and (e) boiler operating at excessive rate of output. 3. Wafer disappears from the gage glass: This may be caused by: (a) priming due to grease and dirt in boiler; (i>) too great pressure difference between supply and 408 CHAPTER 16 1956 Guide return piping preventing return of condensation; (c) valve closed in return line; (d) connection of bottom of water column into a very active section or thin waterway; and (e) improper connections between boilers in battery permitting boiler with excess pressure to push returning condensation into boiler with lower pressure. 4. Water is carried over into steam main. This may be caused by: (a) grease and dirt in boiler; (6) insufficient steam dome or too small steam liberating area; (c) outlet connections of too small area; (d) excessive rate of output; and (e) water level carried higher than specified. 5. Boiler is slow in response to operation of dampers. This may be due to: (a) poor draft resulting from air leaks into chimney or breeching; (6) inferior fuel; (c) inferior attention; (d) accumulation of clinker on grate; and (e) boiler too small for the load. 6. Boiler requires too frequent cleaning of flues. This may be due to: (a) poor draft; (6) smoky combustion: (c) too low a rate of combustion; and (d) too much excess air in firebox causing chilling of gases. 7. Boiler smokes through fire door. This may be due to: (a) defective draft in chimney or incorrect setting of dampers; (6) air leaks into boiler or breeching; (c) gas outlet from firebox plugged with fuel; (d) dirty or clogged flues; and (e) improper reduction in breeching size. . 8. Low carbon dioxide. This may be due on oil burning boilers to: (a) improper adjustment of the burner; (6) leakage through the boiler setting; (c) improper fire caused by a fouled nozzle; or (d) to an insufficient quantity of oil being burned. Cleaning Boilers All boilers are provided with flue clean-out openings through which the heating surface can be reached by means of brushes or scrapers. Flues of solid fuel boilers should be cleaned often to keep the surfaces free of soot or ash. Gas boiler flues and burners should be cleaned at least once a year. Oil burning boiler flues should be examined periodically to deter mine when cleaning is necessary. . The grease used to lubricate the cutting tools during erection of new pip ing systems serves as a carrier for sand and dirt, with the result that a scum of fine particles and grease accumulates on the surface of the water in all new boilers, while heavier particles may settle to the bottom of the boiler and form sludge. These impurities tend to cause foaming, preventing the generation of steam and causing an unsteady water line. This unavoidable accumulation of oil and grease should be removed by blowing off the boiler as follows; If not already provided, install a surface blow connection of at least 1J in. nominal pipe size with outlet extended to . within 18 in. of the floor or to sewer, inserting a valve in line close to boiler. Bring the water line to center of outlet, raise steam pressure, and while fire is burning briskly open valve in blow-off line. When pressure recedes, close valve and repeat process adding water at intervals to maintain proper level. As a final operation bring the pressure in the boiler to about 10 lb, close blow-off, draw the fire or stop burner, and open drain valve. After boiler has cooled partly, fill and flush out several times before filling it to proper water level for normal service. The use of soda, or any alkali, vinegar or any acid is not recommended for cleaning heating boilers be cause of the difficulty of complete removal and the possibility of subsequent injury, after the cleaning process has been completed. Effective insoluble compounds have been developed and are available. Special instructions on the proper cleaning compound and directions for its use, as given by the boiler manufacturer, should be carefully followed. Treatment of Boiler Water Corrosion on the water side of a boiler can be prevented by proper treat ment of the boiler water. Generally, treatment which will remove the Heating Boilers, Furnaces, Space Heaters 409 dissolved oxygen and carbon dioxide and maintain a minimum pH of 11 (slightly alkaline water) will effectively prevent corrosion. A pH higher than 11 may be used although the boiler water is more likely to foam and cause wet steam with the greater concentration of alkali. A number of compounds are being marketed for this purpose. The Steel Boiler In stitute adopted a conditioning compound for use with steel boilers after an extensive cooperative study and many members of the Institute either supply this compound with their boilers or have it available. It should be emphasized that when the character of the water is such that treatment is required, the treatment should be administered im mediately after the boiler and system have been cleaned.' It is not good practice to fill a boiler with fresh water and allow it to stand idle as the dissolved gases in fresh water available in many localities can start cor rosive action in a very short time. After refilling a system it is advisable to elevate the temperature close to the boiling point to drive off the dis solved gases immediately. Care of Idle Heating Boilers Heating boilers are often seriously damaged during summer months due chiefly to corrosion resulting from the combination of sulfur in the soot with the moisture in the cellar air. At the end of the heating season the following precautions should be taken: 1. All heating surfaces should be cleaned thoroughly of soot, ash and residue, and . the heating surfaces of steel boilers should be given a coating of lubricating oil on the fire side. 2. All machined surfaces should be coated with oil or grease. 3. Connections to the chimney should be cleaned, and in case of small boilers, the pipe should be placed in a dry place after cleaning. 4. If there is much moisture in the boiler room, it is desirable to drain the boiler to prevent atmospheric condensation on the heating surfaces of the boiler when they are below the dew-point temperature. Due to the hazard that some one may in advertently build a fire in a dry boiler, however, it is safer to keep the boiler filled with water, particularly in residential installations. Air can be excluded from a steam boiler by raising the water level into the steam outlets. A hot water system usually is left filled to the expansion tank. 5. The grates and ashpit should be cleaned. 6. Clean and repack the gage glass if necessary. 7. Remove any rust or other deposit from exposed surfaces by scraping with a wire brush or sandpaper. After boiler is thoroughly cleaned, apply a coat of preservative paint where required to external parts normally painted. 8. Inspect all accessories of the boiler carefully to see that.they are in good work ing order. In this connection, oil all door hinges, damper bearings, and regulator parts. 9. If a system has been drained and refilled with fresh water, the boiler should be fired long enough to elevate the water temperature close to the boiling point to drive off dissolved oxygen and carbon dioxide. These gases can be responsible for exces sive corrosion if allowed to remain in the system. WARM AIR FURNACES Warm air heating furnaces of a number of types and a wide range of sizes are listed and illustrated in the Catalog Datd Section. Warm air furnaces may be classified in several different ways: I. According to method of heat distribution--these are either gravity or me chanical (blower) furnaces. 410 CHAPTER 16 1956 Guide 2. According to fuels for which the furnaces are designed--these are coal hand- fired or stoker-fired, oil, gas, or wood. , 3. According to materials of construction--they are cast-iron, low carbon steel, and occasionally high temperature steel alloys. . 4. According to design or construction, such as drum and radiator, tubular, horizontal, etc. Gravity Warm Air Furnaces A gravity furnace is one in which the motive head producing air flow depends upon the difference in density between the heated air leaving the top of the casing and cooled air entering the bottom of the casing. Since this gravity head is relatively low, the furnace must have low internal re sistance to the flow of air, and relatively large areas must be available for free circulation within the furnace casing. It is common practice to pro vide approximately 50 percent free air area through gravity type furnaces. Furnaces for gravity type systems are available in designs suitable for central heating, pipeless furnace, or unit floor furnace installations. Booster fans are sometimes used in conjunction with gravity design systems* to in crease air circulation. Where a fan is to be used with a furnace casing sized for gravity air flow, some form of baffling must be employed to re strict the free area within the casing and to force impingement of the air . against the heating surfaces. Where square casings are used, the comers must be baffled. Mechanical Warm Air Furnaces Mechanical or forced warm air furnaces include fans or blowers as in tegral parts, for the purpose of circulating the air, and usually include air filters. Centrifugal fans with either backward or forward curved blades are the type most commonly used. Motors may be mounted on the fan shaft or connected to the fan by a belt drive. Adjustable pulleys are desirable to provide means of regulating the quantity of air distributed to the heated spaces. Either the motor load or the noise considerations may limit the maximum operating fan speed. Two-speed motors have given successful operating results. Motors and mountings must be carefully selected for quiet operation. Electrical conduit and water piping must not be fastened to, nor make contact with the fan housing. Filters Several types of filters are available- for mechanical warm air furnace applications, and are discussed in Chapter 34. For maximum efficiency and life under operating conditions, filters should not be subjected to a. temperature in excess of 150 F. Filters should have at least 80 percent average efficiency on an 8-hr test at a maximum resistance of 0.25 in. of water. Filter resistance rises rapidly with the accumulation of dirt, and: may reduce the air circulation over heating surfaces. In domestic fur naces, the maximum velocity, based on nominal filter area, should not exceed 300 fpm. - Fuel Utilization A combustion rate of from 5 to 8 lb of coal per (square foot of grate) (hour) is recommended for residential furnaces. A higher combustion rate is permissible with larger furnaces for buildings other than residences, . Heating Boilers, Furnaces, Space Heaters 411 depending upon the ratio of grate surface to heating surface, firing period, and available draft. . In residential furnaces for coal burning, the ratio of heating surface to grate area will average about 20 to 1; in commercial sizes the ratio may be as high as 50 to 1, depending on fuel and draft. Furnaces may be installed singly, each furnace with its own fan, or in batteries of a number of furnaces, using one or more fans. Where oil fuel Is used, care must be exercised in selecting the proper size and type of burner for the particular size and type of furnace used. Furnaces for burning oil fuel are usually designed for blow-through instal lations so that the pressure in the air space is higher than that in the combustion chamber or flues. The National Warm Air Healing and Air Conditioning Association has prepared a Tentative Code for Testing and Hating of Oil-Fired Furnaces. Compact fan-fumace-burner units are available, suitable for basement, closet, or attic installations. Gas-fired forced air furnaces should conform in construction and per formance to A.G.A. Approval Requirements. Heavy Duty Fan Furnaces Fan furnaces' for large commercial and industrial buildings, churches, schools, etc., are available in sizes ranging from 300,000 to 6,000,000 Btu per (hour) (unit). Heavy duty furnace heaters may be arranged in bat tery combinations of one or more, units. . Most manufacturers of heavy duty furnaces rate their furnaces in Btu per hour, and also in the number of square feet of heating surface. Con servative practice indicates that at no time in the heating-up period should the furnace surface be required to emit more than an average of 3500 Btu per square foot. A higher rate of heat emission tends to Increase the heat loss up the chimney, and raise fuel consumption, to. shorten the life of the furnace, and to overheat the air. The ratio of heating surface to grate area of furnaces for this type of work should never be less than 30 to 1 and, as indicated previously, may run as high as 50 to 1. Control of temperature is secured through (1) controlling the quantity of heated air entering the room, (2) using mixing dampers, or (3) regulating the fuel supply. The design of heavy duty fan furnace heating systems is in many re spects similar to that of the central fan heating systems described in Chap ter 30. Ducts are designed by the method outlined in Chapter 32. MATERIALS AND CONSTRUCTION Both cast-iron and steel furnaces are made in capacities ranging from those for small insulated residence application with inputs of 40,000 Btu per hour or less, to capacities as large as 600,000 Btu per hour. Cast-iron furnaces are usually constructed with a minimum sectional thickness of ( in., and effectively resist high temperatures and corrosion. They usually have a fairly large heat capacity because of their mass, which provides a distinct.#*/ wheel or carry-over heating effect. In steel furnaces welding, riveting, or both are used to join the formed metal. The use of steel castings, however, is rare, because of the cost, and because high stresses are not encountered in normal furnace construc tion. Steel furnaces have low heat capacities as a result of their relatively low mass'and, therefore, deliver heat rapidly on demand. 412 CHAPTER 16 1956 Guide FURNACE RATING Rating Equations for Gravity Warm Air Furnaces10 Until a method of testing and rating gravity warm air furnaces has been developed, the following empirical rating equations are recommended by the National Warm Air Heating and Air Conditioning Association. Gravity warm-air furnaces of conventional design, having ratios (of heating surface to grate area) of 15 to 1 or greater, and having a ratio of casing area to face area not less than 0.4, are rated by the following equa tions: 1. Hand-fired furnaces converted to Stoker, Gas, or Oil Firing. . Bonnet Capacity in Btu per hour = 1785 X S X 1.333 (2) 2. Hand-fired furnaces, with ratios of heating surface to grate area greater than 15 to 1 and less than 15 to 1. , . Bonnet Capacity in Btu per hour = 1785 X S X 1.333 (3) 3. Hand-fired furnaces with ratios of heating surfewe to grate area in excess of 55 to 1. ' Bonnet Capacity in Btu per hour 1785 X 25 X G- X 1.333 (4) where S = heating surface, in square feet. G = actual grate area, in square feet. . . The Register Delivery Rating is equal to 0.75 x (Bonnet Capacity). The Leader Pipe Rating in square inches, formerly used as a rating unit, may be found by dividing the Register Delivery Rating by 136. Heating Surface of Furnace - . Prime healing surface is defined10 as surface above the top of the grate having hot gases or live fuel on one side and circulating air over the other, and in all cases is measured on the exterior or air side. The areas of the outer casing, the inner liner, and any radiation shields shall not be considered as heating surface. In determining the amount of heating surface, extended surfaces are considered to be prime heating surface subject to the following limitations: 1. Extended heating surface may consist of fins, ribs, webs, lugs, or other pro jections. from the prime heating surface. Projections less than } in. thick at the base, and extending more than 1 in. from the prime surface are classified as fins.* 2. Integral fins are continuously welded to, or cast as a part of, the prime heating surface. Both sides are included as heating surface, subject to the following allow ances: Distance from Prime Surface . 1st inch 2nd inch 3rd inch Over 3 in. Ratio of Effective Area to Total Area................................ 0.40 0.30 0.20 None 3. Non-integral fins are spot welded to, or otherwise held in line contact with the prime heating surface. Both sides are included as heating surface, subject to t e following allowances: Distance from Prime Surface . Ratio of Effective Area to Total Area................................ 1st inch 0.30 2nd inch 0.20 3rd inch 0.15 Over 3 in. None Heating Boilers, Furnaces, Space Heaters 413 4. In the case of ribs, webs, or lugs more than 1 in. thick at the base and extending less than 1 in. from the prime surface, the entire surface in contact with circulating air in included as heating surface. . 5. In the case of ribs, webs, or lugs more than } in. thick at the base and extending more than 1 in. from the prime heating surface, the areas of both sides of the first inch are included as prime heating surface. The portions projecting beyond 1 in. are treated as integral fins. ' Grate Area Grate area is defined10 and treated for purpose of rating as follows: 1. The nominal grate area is defined as the total cross-sectional area of the bottom of the firepot. In steel furnaces the nominal grate area is the cross-sectional aretj inside the firebrick lining. 2. The actual grate area, used for calculating the ratios of heating surface to grate are3, is the nominal grate area minus certain areas that cannot be considered as part of the grate itself. The following rules govern these deductions: (1) If a solid, con tinuous ledge extends around the grate and inside the firepot, any area of this ledge extending inside of a circle, the diameter of which is 1 in: less than the diameter of the bottom of the firepot, shell be deducted. (2) If separate, solid projections ex tend from the firepot towards the grate, the areas of any portions of these projections extending inside of a circle, the diameter of which is 3 in. less than the diameter of the bottom of the firepot, shall be deducted. (3) In the case of grates which are inclined, or are conical, the projected area is the same as the nominal grate area. The latter should, therefore, be used after making any necessary deductions. Ratings for Forced Air Furnaces For solid fuel burning, forced air furnaces having bonnet capacities between 80,000 and 250,000 Btu per hour, no standard method of test has been accepted, although eventually such codes will be developed. The National Warm Air Heating and Air Conditioning Association recommends the following empirical equations for use in rating solid fuel forced air furnaces: 1. Hand-fired furnaces converted to Stoker, Gas, or Oil Firing. Bonnet Capacity in Btu per hour => 2265 x S x 1.177 (5) 2. Hand-fired furnaces, with ratios of heating surface to grate area greater than 15 to 1 and less than 55 to 1. , Bonnet Capacity in Btu per hour = 2265 x S i 1.177 (6) 3. Hand-fired furnaces with ratios of heating surface to grate area in excess of 55 to 1 where Bonnet Capacity in Btu per hour = 2265 x 25 x G x 1.177 .. (7) S = heating surface, in square feet. G = actual grate area, in square feet. The Register Delivery Rating is equal to 0.85 x (Bonnet Capacity). The following testing and rating codes have been generally accepted in the industry: Commercial Standard CS-109-JH for rating solid fuel-burning, forced-air furnaces Saving bonnet outputs of 80,000 Btu per hour or less. This provides a method of rating small coal-fired forced-air furnaces by test. ' d Tentative Code for Testing Oil-Fired Furnaces. This code has been adopted by he National Warm Air Heating and Air Conditioning Association for rating oil-fired furnaces by test. The American Gas Association method of rating gas-fired furnaces on performance under tests. This is described in the Approval Requirements for Central Heating Iras Appliances. 414 CHAPTER 16 1956 Guide Commercial Standard US-51 is a method of rating oil-burning floor furnaces by test, , Commercial Standard CS 104-49 is a method of rating warm air furnaces equipped with pot-type oil burners by test. Various codes covering the construction and performance of appliances as related to -fire hazards have been developed by Underwriter Laboratories, Inc. In addition, there are many municipal codes11 which regulate construction and-installation of furnace equipment. The yardstick of the National Warm Air Heating and Air Conditioning Association provides criteria for evaluating a furnace design and installation against industry accepted standards. . FURNACE EFFICIENCY Rating formulas of the National Warm Air Healing and Air Conditioning Association are based on 55 percent efficiency for gravity coal furnaces and 65 percent efficiency for forced-air coal furnaces. In the tentative Oil Testing Code the contemplated minimum efficiency is 70 percent for oil-fired forced-air furnaces. Gravity gas furnaces approved by the Ameri can Gas Association are assigned a rating based on 75 percent efficiency. All forced-air gas-fired furnaces approved by American Gas Association are assigned a rating based on 80 percent efficiency. DESIGN CONSIDERATIONS Considerations of prime importance in the design of warm air furnaces and some general suggestions to be observed in connection with each, are as follows: 1. Adequate heat transfer surface. a. Heat transfer rates of 2,000 to 4,500 Btu per (hour) (square foot) of heating surface may be obtained without unduly high metal temperatures. b: Fins, pins and bosses are frequently used to add surface and to break down superficial gas films, both on gas-to-metal and metal-to-air surfaces. c. Surface and stack (flue gas) temperatures are good indications of the amount and effectiveness of the heating surfaces. 2. Safe and efficient combustion offuel. a. Proper mixture of fuel and air is necessary for efficient combustion. This necessitates careful attention to the design of grates, nozzles, burners, air inlet areas and location, and combustion chamber baffling. b. Regulation of the quantity and the distribution of the air for combustion should be provided by use of check dampers, draft regulators, draft hoods, . , air shutters and air orifices. c. Total draft loss through appliances should not exceed that available from chimneys which would normally be obtainable in the size of building which the appliance will supply with heat. d. The use of ignition safety devices such as safety pilots, hold-fire controls, and the like is recommended. 3. Fuel capacity of appliance. a. With solid fuels adequate coal capacity should be provided for at least 5 hr of operation at the maximum rated combustion rate. 4. Adequate circulation of air over heating surface. a. In gravity furnaces, free air space between casing and heat exchanger should . be great enough to permit free flow over all surfaces. ' b. Forced air furnace design must include fans having proper capacity and suitable performance characteristics. Internal static pressures must be minimized without losing the advantages of high velocity circulation over the heat exchanger surfaces. c. The air flow over the heating surface must be directed to obtain maximum - efficiency and to eliminate hot spots and air noises. d. Air velocities at bonnet should not be much in excess of 1,000 fpm, and air temperature distribution at the furnace outlet should be uniform within approximately 30 deg. Heating Boilers, Furnaces, Space Heaters 415 5. Durability. a. A minimum metal weight for gas-fired heat exchangers is established as No. 20 U.S. Gage for plain carbon steel by the A.G.A. Approval Requirements for Central Heating Gas Appliances, with some municipal codes specifying 18 gage. Cast-iron sectional thicknesses of i in. to | in. are recommended. b. Added strength and reinforced designs may be required to preclude damage in shipment, burning out from overfiring, or corrosion from condensation. c. Maximum heat exchanger surface temperatures which may be used vary with the metal. The American Gas Association Approval Requirements for Cen tral Heating Gas Appliances specify a maximum of 875 F for cast-iron or steel gas furnaces, and the National Bureau of Standards CS 109-44 Code for Forced Air Solid Fuel-Burning Furnaces specifies 1000 F as a maximum surface tem perature. These temperatures define the range in which oxidation of non alloy ferrous metal begins. The use of proper alloy additions increases the temperature resistance properties of metals. d. Casing temperatures should be controlled so that they do not become hazards to burn those who touch them, or to create fires. 6. Serviceability. a. Those parts of the furnace which may be subject to soot, fly-ash, or conden sation deposits should be accessible for cleaning. b. Parts which may require adjustments or replacements, such as grates, baffles, liners, controls, should be removable. c. Furnaces should be so designed that they can be installed with a minimum of difficulty. 7. Control. a. Thermostatic controls of various types should be used to correlate space temperatures with unit operation. b. Controls should be provided wherever possible, to prevent the occurrence of excessive temperatures or other conditions in any part of the unit which might cause unsafe operation. 8. General design considerations. a. Furnace casings are normally constructed of formed and painted sheet steel or of galvanized iron. The casing should be protection from excessive radia tion losses and temperatures by use of insulation or sheet steel air space liners. Liners should extend from the grate level to the top of the furnace and should be spaced from 1 in. to II in. from the outer casing. b. The hood or bonnet of the casing above the furnace should be as high as base . ment conditions will allow, to form a plenum chamber over the top of the furnace. This tends to equalize the pressure and temperature of the air leaving the bonnet through the various openings. It is generally considered advisable to take off the warm air pipes from the side of the bonnet near the top, as this method of take-off allows the use of a higher bonnet and thus provides a larger plenum chamber. c. Warm air outlet and return air connections should be designed so that the ductwork may be easily attached. A i in. flange is normally used for this purpose. d. Suitable provision should be made in appliances so that the controls and humidifiers may be installed in the proper location. When these auxiliary units are installed in the ductwork, detailed instructions should be provided . to insure their proper location. e. The flue connection should be of integral flue pipe size, and provision should be made to attach the flue pipe to the flue outlet of the furnace. HUMIDIFICATION EQUIPMENT Evaporating pans are usually located in the outlet, air. There is a present trend toward heating the water. Equipment for doing this may make use of sprays, or it may take the form of water circulating coils placed within the combustion chamber, and connected by pipes to the humidifier pans where a constant water level is maintained by some separate float device. All humidifiers require provision for removal of dirt, and lime. 416 CHAPTER 16 1956 Guide SPACE HEATERS Space heaters may be classified in several ways, such as: ' , 1. By the type of fuel used as coal, wood, gas, and fuel oil. 2. According to the method of heat distribution as circulators or radiant types. A radiant heater is one in which the heat exchanger surface is exposed directly to the room atmosphere, and the generated heat is dissipated primarily by radiation. A circulating heater is essentially a jacketed radiant heater from which circulation of room air is promoted by the chimney effect caused by the movement of air passing upward between the jacket and heat exchanger surface. 3. According to method of design for particular fuel types, such as: (a) surfacefired and magazine-feed for solid fuels, (b) vaporizing pot-type and blue-flame heater for oil, and (c) vented and unvented heaters for gas. (The type of gas burner design, such as injection, yellow flame, power, and pressure, may also be mentioned.) SOLID FUEL-FIRED HEATERS Surface-fired beaters normally have a front firing door and are operated with relatively shallow fuel beds. A magazine-feed heater includes a deep reservoir of fuel to lengthen the attention intervals. In a true magazine feed heater the rate of fuel ignition would be equal to the rate of burning; and self-feeding should operate to move the unbumed fuel by gravity flow from the magazine section into the hearth area. However, the ideal balance between rate of ignition and rate of burning is virtually impos sible to attain for any solid fuel under normal usage, although self-feeding may be obtained with wood and some free burning coals. Thus, a maga zine-type space heater is essentially a deep surface-fired heater, its principal difference being increased fuel capacity. m f Materials and Construction There is no accepted code governing the construction of solid fuel burn ing space heaters. In past years cast-iron was used predominantly in the construction of coal and wood heaters, with the exception of the so-called air-tight heaters designed as low-cost wood-burning units with little con sideration for long life, and stoves were priced on a poundage basis. The present trend is toward fabricated steel parts and welded assemblies, al though cast-iron is still used for grates, firebox liners, and parts subject to high temperatures. Refractory firebox liners are also used quite exten sively. Formed sheet steel is used predominantly for the outer jacket of circula iV; tor heaters, although heaters with outer casings formed from cast-iron are still readily available. Circulator cabinets normally have surfaces finished ; with a porcelain enamel, while the casing of a radiant heater is finished with an air-dried japan or a baked enamel. ' Both welding and stove bolts are used in unit assembly, and stove cement p: is used on section joints to prevent air leakage. This latter is extremely important to obtain a low rate of combustion when desired. .ft Testing and Rating < Y' 4- There is no accepted code governing the method of testing and rating solid-fuel space heaters. A tentative procedure, TS-3443, has been issued, by the Division of Trade Standards, National Bureau of Standards, but is based on use of anthracite as a rating fuel, although bituminous coals are used predominantly as heating fuels. This procedure, which has been the basis of published ratings, consists of determining the heater output, expressed in Btu per hour, by the indirect method. The measurable heat Heating Boilers, Furnaces, Space Heaters 417 losses: (1) loss due to moisture in the fuel, (2) loss due to heat in the dry flue gases, (3) loss due to unbumed carbon monoxide, and (4) loss due to unbumed combustible in the ash and refuse, are measured by test. The total of these four measurable losses, plus an assumed value for unac counted for losses, are then subtracted from the heat input. The dif ference multiplied by the burning rate in pounds per hour is the heater output. When using anthracite as the rating fuel, the unaccounted for loss has been assumed to be zero. It has been accepted practice to use a 20 percent allowance for the unaccounted for losses when burning a bituminous coal. The value of this factor has been under study and, although test work is incomplete, a value of 12 percent of the heat input has been determined as representing the losses due to smoke and unbumed hydrocarbons for a surface-fired heater, when burning a high volatile bituminous coal. No allowance is made for a radiation loss, as this is useful heat. Design Considerations Some important considerations in the design of solid fuel space heaters are: 1. Suitable protection by baffling or insulation against overheating of floors and walls. Although there are no industry-accepted standards by which floor and wall temperatures may be determined, some indication of heater performance, with regard to overheating, may be found by the use of the corner booth test arrangement de scribed in National Bureau of Standards Commercial Standard CS 103-43 and Under writer's Laboratories Standard, Subject 896, mentioned in following section on Oil Heaters. 2. Tight heater construction to prevent air leakage, and to enable maintenance of a suitably low minimum burning rate. This includes a ground, paper tight joint between the ashpit door and door frame. 3. Sufficient free air space, between the casing and heat exchanger of circulating heaters, to permit free air flow over all surfaces and maintain a suitably low casing temperature. 4. Protection of all metal parts from deterioration due to high temperature. This may be accomplished by: (a) fabrication of certain parts from cast-iron or.an alloy iron, (b) protection by a refractory liner, (c) use of high temperature enamel coat ings, (d) directing air against hot spots. 5. Proper admission of secondary air to complete the combustion process. Care should be taken to prevent this air from also functioning as primary air. 6. Strength in assembly to prevent transportation and use damage. Considerable work has been directed in the past few years towards inprovement of the performance of bituminous coal-fired space heaters, with particular reference to smokeless operation under conditions of normal operation such as obtained in homes. A recent paper describes the smoke less coal heater developed by Bituminous Coal Research, Inc., wherein smokeless combustion is obtained by admitting secondary air through a narrow slot, extending from side to side, above the edge of the fuel bed where the gas leaves to enter a vertical gas passage.12 Complete mixing of the volatile material, released from the coal in the magazine, with the secondary air supplied is obtained as both streams pass under the bottom of the arch. Complete combustion results from this intimate mixing in a region `which maintains itself at high temperatures even during banking periods. - OIL HEATERS Vaporizing pot-type oil heaters consist of: (1) a metal pot in the bottom . of which the oil is vaporized, the vapors burning at or near the top of the 418 CHAPTER 16 1956 Guide pot; (2) a secondary combustion chamber, or heat exchanger, in which combustion is completed. The flue connection is made to this chamber or through a second heat exchanger which may be of the diving-flue type installed to increase efficiency. The burner may be designed for operation both with and without mechanical draft. Blue-flame oil burners differ from the pot-type variety in that removable perforated sleeves are provided above an oil pan instead of a metal pot, and lighting rings or kindlers are used for easy fighting. Both types of oil burners operate by the burning of the oil vapor rather than the oil itself, the oil being first fed to a chamber in which the oil is entirely varporized, then mixed with air introduced through suitably lo cated ports and burning at the top of the pot or perforated sleeves. Such heaters are designed to bum No. 1 oil (See Table 4, Chapter 14) or kero sene (coal oil). At no time should oil heavier than that for which the burner is designed be used, as heavier oils may cause excessive carboniza tion in the burner or fuel feed fine. Materials and Construction Formed sheet steel and welded assemblies are used primarily in oil heater construction. Standards governing construction which have been generally accepted are: 1. Commercial Standard for Flue-Connected Oil-Burning Space Heaters equipped with Vaporizing Pot-Type Burners, CS101-43 (National Bureau of Standards). 2. Standard for Oil-burning Stoves, Subject 896 (Underwriters' Laboratories, Inc.). 3. Standard for Construction and Performance of Oil Burners for Installation in Stoves and Ranges, Subject 865 (Underwriters' Laboratories, Inc.). Some states or municipalities have codes which apply locally, but these usually apply primarily to installation, and the Underwriters' Laboratories label of approval is sufficient to cover acceptance of the unit. Testing and Rating Commercial Standard 'CS101-43 is intended to provide a uniform stand ard method for ascertaining the maximum practical heat output in Btu per hour of flue-connected oil-burning space heaters under approximately normal service conditions. This method is based upon the following equations: Hr = A - B (8) - and E = Ht/A (9) where . A = total heat of fuel used. B = heat lost in flue gases. H, -- net heat delivered to the room. E = unit efficiency. " ` . ' The following minimum performance requirements are stipulated: I. Adequate provision for ease of lighting and insurance against loss of ignition prior to heating of burner. 2. Ease of operation of controls. Heating Boilers, Furnaces, Space Heaters 419 .3. Proper operation of burner without excessive carbonization with gradeB of oil recommended by the manufacturer. 4. The heater shall be capable of passing the 6 percent ICHAM smoke test. 5. The heater shall be capable of operating with an overall efficiency of not less than 70 percent under conditions of test, or at a lower stack draft recommended by the manufacturer. <: Design Considerations Some factors important in the design of oil-burning heaters are: 1. Proper pitch of oil lines from the sump to the burner, thus preventing vapor and air lock. i, m 2. Proper positioning of the oil sump or constant-level valve to maintain the proper oil level in the burners, if factory assembled. .. 3. Tight construction, not only of oil lines, but of oil tank, sump, and burner to prevent a hazardous condition due to oil leakage. 4. Provision for leveling and aligning the entire heater for maintenance of proper operation. If a separate fuel tank is used, the heater should have provision for secure fastening to the floor to prevent excessive strain on oil supply line, and the conse quent danger of leakage of oil. . .. ..... 5. Provision of a draft regulator to prevent abnormal draft fluctuations!' 6. Proper shielding of an attached fuel oil supply tank to prevent excessive oil temperatures. 7. AH metal parts subjected to the corrosive action of the oil shall be made of non- corrodible.metal, or of metal suitably coated to resist corrosion. . . , ; ... - . 8. The heatir should have suitable baffling or insulation to prevent overheating of floors and walls. . 9. Strength in assembly to prevent transportation and use damage. ' GAS HEATERS Vented gas heaters are defined as those capable of removing 90 percent of the flue gases through a single flue outlet. All heaters having a gas in put rating in excess of 50,000 Btu per hour must be of the vented type in order to meet ASA Approval Requirements for Gas-Fired Room Heaters.1' Space heaters may be classified by burner type as follows: .. 1. Injection Burner type which employs the energy of a jet of gas to inject air for combustion into the burner and mix it with the gas. !. 2. Yellow Flame Burner type in which secondary air only is depended on for the combustion of the gas. Materials and Construction Standards covering materials and accessories used in the construction of gas heaters are described in ASA Approved Requirements for Gas-Fired Room Heaters15 and in applicable Listing Requirements.14 Efficiency Requirement . Vented space heaters having input ratings in excess of 20,000 Btu per hour are required to have a heating efficiency of not less than 70 percent,15 based on the total heating value of the gas. Vented space heaters;having input ratings of 20,000 Btu per hour or less are required to have a heating efficiency of not less than 65 percent.15 These efficiencies are based ,upon the following equation: . et 100 - -- X 100 9 (10) where et = heating efficiency, percent. H, = heat above room temperature carried away by the flue products, Btu per hour. g = hourly gas heat input, Btu per hour. 420 CHAPTER 16 1956 Guide Radiant heaters are required to have a radiant efficiency of not less than 28 percent. ; Design Considerations Some factors important in the design of gas heaters are: 1. Proper design of the burner head, port sizes and locations so that the flame Will not lift, float, or flash back, and be excessively noisy in operation. 2. Proper venting of combustion chamber for relief of forces resulting from igni tion of an explosive mixture of gas and air. 3. Protection of valve handles to prevent excessive temperature rise during opera tion. 4. Insulation and baffling of heater to prevent over-heating of walls and floor. INSTALLATION OF SPACE HEATERS The two most important considerations involved in the installation of a space heater are safety and chimney draft. The items of chimney details and flue connections which should have special attention, are outlined in Chapter 17, Chimneys and Draft Calculations. In all cases, it is recom mended that installation be made in accordance with the current National Building Code. ' REFERENCES 1 See A.S.H.V.E. Transactions, Vol. 35, 1929, p. 322. 3 See A.S.H.V.E. Transactions, Vol. 35, 1929, p. 332. 3 See A.S.H.V.E. Transactions, Vol. 37,1931, p. 23. See A.S.H.V.E. Transactions, Vol. 44, 1938, p, 366.. i I-B=R Testing and Rating Code for Low Pressure Heating Boilers, July 1952 Institute of Boiler and Radiator Manufacturers). 6 Testing and Rating Code for Boiler-Burner Units, July, 1954 (Heating, Piping and Air Conditioning Contractors National Association). . v/=B=R Ratings for Cast-Iron Boilers May 10, 1955 (Institute of Boiler and Radiator Manufacturers). Engineering Standards, Part II, Net Square Feet Radiation Loads in 70 Deg Fahr, Recommended for Low Pressure Heating Boilers, July, 1954 (Heating, Piping and Air Conditioning Contractors National Association). 3 Comfort Heating, 1938, pp. 35 to 39 (American Gas Association). '10 Gravity Code and Manual for the Design and Installation of Gravity Warm Air Heating Systems, Manual No. 5, Fifth Ed., (National Warm Air Heating and Air Conditioning Association). "Recommended forms for municipal installation and fire codes are included in Manual 7--Code and Manual for design and Installation of Warm Air Winter Air Conditioning Systems, Fourth Edition, (National Warm Air Healing and Air Con ditioning Association). " The Development of a Design of Smokeless Stove for Bituminous Coal, by B. A. Landry and R. A. Sherman, presented at the 1948 Annual Meeting of the ASME, 13 American Standard Approval Requirements for Gas Fired Room Heaters, ASA Z21.ll, 1954 (American Standards Association). "American Standard Listing Requirements for: Automatic Pilots, Z21.20, 1951, Gas Appliance Thermostats Z21.23,1941, Domestic Gas Appliance Pressure Regula tors Z21.18,1936, with addenda effective June 15,1935, July 8,1938, Automatic Valves for 6as Appliances, Z21.21, 1952 (American Standards Association). - . CHAPTER 17 CHIMNEYS AND DRAFT CALCULATIONS Draft Definitions, Theoretical Natural Draft, Factors Affecting Natural Draft, Available Draft, Required Draft; Industrial Chimneys, Available Draft for the Industrial Chimney, Determining Industrial Chimney Sizes; Residential Chimneys, Available Draft for Residential Chimneys, Short Chimneys, Determining Residential Chimney Sizes, Draft Requirements of Appli ances, Chimneys for Gas Appliances; Recommendations of the NationalBoard of Fire Underwriters; General Considerations DRAFT is the pressure difference associated with the movement of flue gases through a flue or chimney. Natural draft is caused and meas ured by the difference in weight of a column of flue gas within the.flue and a corresponding column of air of equal dimension outside the flue. Natural draft is always negative and is expressed in inches of water gage. When the movement of air is supplied by a fan, the draft is said to be forced or induced. When the fan is located, so as to push the flue gases through the flue, the draft is forced. When the fan is located so as to' draw the flue gases through the flue, the draft is induced. ' THEORETICAL NATURAL DRAFT Theoretical natural draft is produced solely by the difference in weight of the column of flue gases within the flue and that of a corresponding column of air of equal dimensions outside the flue. In the determination of theoretical natural draft, no allowance is made for friction or other posi tive or negative effects. Theoretical natural draft is expressed by the following formula: Dt = 2.96ffB0(^-- (1) where Dt = theoretical draft, inches of water. H = height of flue or chimney, feet. B0 = barometric pressure, inches of mercury. Po = density of air at 0 F and 1 atmosphere pressure, pounds per cubic foot. po = density of flue gas at 0 F and 1 atmosphere pressure, pounds per cubic foot. . To -- temperature of air surrounding the chimney, Fahrenheit absolute. Tc = temperature of the gases, average or effective, in the chimney, Fahrenheit absolute. Theoretical natural draft may also be expressed by the following simpli fied-formula in which it is assumed that the densities of the flue gas and of the air are equal at the same temperature and pressure: PH(TC - T0) b.2Tc (2) where: - P = mean density of atmospheric air, pounds per cubic foot. ' 421 422 CHAPTER 17 1956 Guide FACTORS AFFECTING NATURAL DRAFT As indicated in both Equations 1 and 2, the theoretical natural draft is directly proportional to the height of the flue and is dependent upon the absolute mean temperature.of the gases within the flue. ' It is also directly proportional to the density of the air outside the flue although the effect of this factor is minor: The formulas for theoretical natural draft are based on mean or average temperature which is one half of the sum of the entering and exit tempera ture. Since the difference in exit and entering temperatures, or the tem perature gradient in the flue, is due to the escape of heat through the walls of the flue and chimney, the heat transfer characteristics of the chimney construction affect draft. Heat transfer is also affected by the rate of flow of the flue gases through the flue so that draft is also affected directly. The flow of flue gases through the flue is retarded by friction which varies directly with the friction coefficient of the flue surface, and with the rate of-flue gas flow. The friction loss may be estimated by means of one of the formulas for ducts such as the Fanning equation or it may be estimated: with sufficient accuracy by the method used for air ducts. (See Chapter 32.) The height of the flue is measured from the point of entrance of the flue gases to the top of the flue. With no wind to produce an aspirating effect and with no obstruction such as a rain cap at the top of the flue, the column of flue gases may extend upward above the top of the flue for several feet. The effect of tins column may be sufficient to overcome the negative or retarding effect of friction and to cause the observed draft to exceed the theoretical draft. This added effect has been measured in some test work. A wind blowing across the top of the flue may also produce an aspirating effect sufficient to overcome the effect of friction and to cause the observed draft to, exceed the theoretical. Both of these effects are transient and un reliable and should not be considered in determining the proper design, of a chimney. AVAILABLE DRAFT The available draft produced by any chimney is equal to the theoretical natural draft minus the friction loss. Given the height, the heat transfer characteristics of the chimney construction, the entering temperature of the flue gases and their volume, and the friction coefficient of the flue and its dimensions, the available draft is readily calculable. The efficiency of a chimney is defined as the ratio of the observed draft or available draft, produced by the chimney for a given inlet temperature and flow rate, to the ideal draft that would be observed if the same quan tity of flue gases traversed the chimney without cooling and without fric tion. The chimney efficiency may be calculated as follows: final measured draft _____ Efficiency ;deaj draft calculated from the inlet temperature REQUIRED DRAFT Before the proper chimney for a particular installation can be selected or designed, the required draft of the combustion unit must be known. The required draft is equal to the sum of all of the resistances to gas flow from the point at which combustion air enters the unit to and including the chimney connection. This is based on the assumption that air forcombus- Chimneys and Draft Calculations 423 tion is available without restriction (such as would be caused by tightly enclosed building construction) at that point of entrance to the unit. Particularly in residences, unrestricted supply of combustion air must be assured. Fig. 1 presents information on the fuel-bed draft loss for various kinds of coal burned at different rates. Rough generalizations can be given for the losses in the flue passages of boiler or furnace but, on account of the great differences in such devices, more reliable data on their flue gas volume, temperature and flue resistance should be obtained for design purposes from their respective manufacturers' Flue gases encounter resistance to flow in breechings or smoke pipes, and this can probably be treated with sufficient accuracy by means of the POUNDS OF COAL BURNED PER SQ FT OF GRATE SURFACE PER HOUR Fig. 1. Draft Required at Different Rates of Combustion for Various Kinds of Coal' method used for air ducts. (See Chapter 32.) The friction in straight ducts can be estimated by means of the last term of Equations 3 and 4. Also, the temperature of flue gases falls during passage through breech ings or flue pipes. For uninsulated surfaces this probably can be ade quately estimated by assuming a loss of heat from the flue gas of 3 Btu per (hr) (sq ft) (Fahrenheit deg temperature difference between the gases and surrounding air). INDUSTRIAL CHIMNEYS Chimneys can be classified as residential and industrial, the chief dif ference being their sizes and the types of draft. Chimneys over approxi mately If ft in diameter are in the industrial chimney class, and their re quirements should be treated accordingly. The majority of industrial chimneys operate under induced or forced draft, resorting to natural draft operation only in the case of emergencies. They are built of brick, con crete, or steel, depending upon economy and the type of installation needed. Proper height is of importance because of removal of waste products, inas much as the products of combustion are often deflected downward around 424 CHAPTER 17 1956 Guide ihe chimney and, with the large amount of gases that are exhausted to the atmosphere through the industrial chimney, downwash can be very ob jectionable.1 ' AVAILABLE DRAFT FOR THE INDUSTRIAL CHIMNEY The available draft, Z)a, for large chimneys and stacks has been estimated with apparent satisfaction in the past by means of formulas which in effect deduct an estimated friction loss from a theoretical draft determined as in Equation 1. The friction loss can be estimated by means of one of the formulas available for ducts, such as the Fanning equation. This pro cedure results in formulas for the available draft as follows: For a cylindrical stack: D, = 2.96 BBo Po \ 0.00126IFT./Z, TJ d?B^c (3) and for a rectangular stack: Z>*= 2.96 HB0 Pc \ Q.mmW*TcfL(x + y) T,,) (xyYBvPe (4) where D = available draft, inches water gage. H = height of chimney above inlet, feet. B0 = existing barometric pressure, inches of mercury. Po = density of air at 0 F, 1 atmosphere pressure. po = density of flue gais at 0 F, 1 atmosphere pressure. To -- temperature of atmosphere, Fahrenheit, absolute. . To = temperature of flue gas, Fahrenheit, absolute. W = flue gas flow rate, pounds per second. / = coefficient of friction. L = length of friction duct (approximately equal to H), feet. d - minimum diameter of round chimney, feet. x and y = length and width of cross-section of rectangular chimney, feet. The following notes facilitate the use of Equations 3 and 4. 1. The barometric pressure, represented by B,,, is the actual pressure at the site of the chimney and not the pressure reduced to sea level datum. In general, the barometric pressure decreases approximately 0.1 in. Hg per 100 ft increase in elevation. 2. The unit weight of a cubic foot of chimney gases at 0 F and sea level barometric pressure is given by the equation: ' Po = 0.131CO, + 0.095O, + 0.083AT, (5) In this equation COt, Oj.and Ni represent the percentages of the parts by volume of the carbon dioxide, oxygen and nitrogen content, respectively, of the gas analysis: For ordinary operating conditions, the value of pc may be assumed at 0.09. The density effect on the chimney gases, due to superheated water vapor resulting from moisture and hydrogen in the fuel, or due to any air infiltration in the chimney proper, is disregarded. Though water vapor content is not disclosed by Orsat analy sis, its presence tends to reduce the actual weight per cubic foot of chimney gases. 3. The atmospheric temperature is the actual observed temperature of ttye outside air at the time the analysis of the operating chimney is made. The mean atmospheric temperature in the temperate zone is approximately 62 F. 4. The chimney gas temperature decreases from the breeching connection to the top of the stack. Tins drop in temperature depends upon the material and construction Chimneys and Draft Calculations 425 of the stack, its tightness or freedom from leaks, its area, its height, and the velocity of the gases through it. The same chimney will suffer different temperature losses depending upon the capacity under which it is working, and the variable atmospheric conditions. No general equation covering all these variables has been suggested, but from observations on chimneys varying in diameter from 3 to 16 ft, and in height from 100 to 250 ft, Equation 6 was deduced :* r,, = (6) where T, = temperature at the center of the connection from the breeching, Fahrenheit degrees, absolute. Ht, = height of the stack above center line connection to breeching, feet. 5. The coefficient of friction between the chimney gases and a sooted surface has been taken by many workers in this field as a constant value of 0.016 for the condi tions involved. This value, of course, would be less for a new unlined steel stack than for a brick or brick-lined chimney, but in time the inside surface of all chimneys, re gardless of the materials of construction, becomes covered with a layer of soot, and thus the coefficient of friction has been taken the same for all types of chimneys and generally constant for all conditions of operation. For reasons of simplicity and convenience-to the reader, this constant value of 0.016 has been employed in the de velopment of the various special equations and charts shown in this chapter. In important large chimney design, especially when the construction or the mate rials are unusual, it is recommended that use be made of the Reynolds number1 in determining the friction factor,/. The following problem illustrates the use of Equation 3: Example 1: Determine the available draft of a natural draft chimney 200 ft in height and 10 ft in diameter, operating under the following conditions: atmospheric temperature, 62 F; chimney gas temperature, 500 F; sea level atmospheric pressure. Bo = 29.92in. Hg; atmospheric and chimney gas density, 0.0863 and 0.09, respectively; coefficient of friction, 0.016; length of friction duct, 200 ft. The chimney discharges 100 lb of gases per second. Solution: Substituting these values in Equation 3 and reducing, D, /0.0863 2.96 X 200 X 29.92 X V, 522 0.09\ 960 ) 0.00126 X 1001 X 960 X 0.016 X 200 10s X 29.92 X 0.09 = 1.27 - 0.14 = 1.13 in. Fig. 2 shows the variation in the available draft of a typical 200 ft by 10 ft chimney operating under the general conditions noted in Example 1. When the chimney is under static conditions and no gases are flowing, the available draft is equal to 1.27 in. of water, the theoretical intensity. As the amount of gases flowing increases, the available draft decreases until it becomes zero at a gas flow of 297 lb per second, at which point the draft loss, due to friction, is equal to the theoretical intensity. The point of maximum draft and zero capacity is called shut-off draft, or point of im pending delivery, and corresponds to the point of shut-off head of a centrif- ' ugal pump. The point of zero draft and maximum capacity is called the wide open point, and corresponds to the wide open point of a centrifugal pump. . A set of operating characteristics may be developed for any size chimney operating under any set of conditions by substituting the proper values in Equation 3, and then plotting the results in the manner shown in Fig. 2. Fig. 3 is a typical chimney performance chart giving the available draft for various gas flow rates and sizes of chimney. This chart is based on an 426 CHAPTER 17 1956 Guide atmospheric temperature of 62 F, a chimney gas temperature of 500 F; a unit chimney gas weight of 0.09 lb per cu ft, sea level atmospheric pressure, a coefficient of friction of 0.016, and a friction duct length equal to the height of the chimney above the grate level. These curves may be used for general operating conditions. For specific conditions, a new chart may be prepared from Equation 4. DETERMINING INDUSTRIAL CHIMNEY SIZES If the required performance for a proposed chimney is known, and if a chimney-gas velocity is assumed, Equation 3 can be transposed to yield the necessary height, and an equation can be developed for the required diame ter. These operations result in the following equations: . H= 2.96B, D,______________ Pc \ _ 0.184/PcfioV; Tj T4 (7) Chimneys and Draft Calculations 427: where / i7e = economical chimney gas velocity, feet per second. ' Equations 7, 8 and 9 can of course be simplified if values are assumed for some of the factors in it. Some typical figures for boiler plants are: Average chimney gas temperature 500 F............................................ T. 960 F absolute ' Average atmospheric temperature 62 F......................................... T0 = 522 F absolute Average coefficient of friction 0.016...........................................f = 0.016 . Average chimney, gas density, 0 F, 1 Atmosphere.....................p,, = 0.09 lb per cu ft Barometer reading, sea level........................................................ ,B,,,= 29.92 in. Hg Fig. 2. Typical Set of Operating Characteristics of a Natural Draft Chimney dVBj>c , ,. , The weight of gas per second, W = 12.075 --7p^~~ from which c /d = 0.288 WTy R,,PcF (8) where H = required height of chimney above grate, feet. d required minimum diameter of chimney, feet. V = chimney gas velocity, feet per second. D, = total required draft, inches of water. For large chimneys, it is usual to assume, that total construction cost is least when the product Hd (height X diameter) is minimum. On this assumption, the product of Equations 7 and 8 can be differentiated, and the differential set equal to zero to find the minimum. Solution for velocity then yields the following equation: V, (9) To totve a typical example: Proceed horizontally from a Weight Flow Rate point to intersection with diameter line; from this intersection fol low vertically to chimney height line; from this intersection follow hori zontally to the right to Available Draft scale. Starting from a point of Available Draft, take steps in reverse order. When these values are substituted in Equations 7, 8 and 9, respectively the results are: H = 190Dr (10) d = I.dIVV* (11) V. = 13.71F1A (12) These, equations should be used for general operating conditions only, or where the.required data necessary for an exact determination are difficult lmpossible secure- Whenever it is possible to obtain accurate data, or the anticipated operating conditions are fairly well known, the required size should be determined from Equations 7, 8, and 9. Additional construction data for large industrial chimneys, whether 428 CHAPTER 17 1956 Guide brick, concrete, or steel may be found in Kent's Mechanical Engineers' Handbook4 or the Handbook of Building Construction.5 / RESIDENTIAL CHIMNEYS Since residential heating appliances depend to a large extent on the natural draft of residential chimneys for satisfactory performance, the chimneys must be of adequate height and of optimum cross-sectional area, reasonably gas tight, and as smooth as practicable internally. They must be of such construction as to create no fire hazard to the building. The height and location of a residential chimney are usually limited by archi tectural and structural considerations, and therefore the draft produced Chimneys and Draft Calculations 429 flues usually operate at a higher mean temperature for a given entering temperature and therefore produce slightly higher drafts. AVAILABLE DRAFT FOR THE RESIDENTIAL CHIMNEY Equations 3 and 4 cannot readily be used for computing the available draft for residential chimneys because of the relatively greater importance of friction losses, cooling of the gases, and soot deposits in small chimneys. Eddy currents and simultaneous flow both upward and downward can occur in a residential chimney for very low flue-gas velocities. At present, it is best to rely on actual test data for determining the available draft of residential chimneys. Fig. 4 shows the available draft HEIGHT OF CHIMNEY ABOVE CENTER LINE OF THIMBLE-FEET Fig. 4. Available Dbaft fob 9* x 9" and 9* x 13' Masonry Chimneys (Ambient Temperature 0 F) will sometimes be inadequate for satisfactory and efficient operation of the fuel burning equipment. The basementless house, the one-story ranch or rambler type, and the flat-roofed structure are usually restrictive, particu larly with regard to adequate chimney height. The limitations of chimney height should be carefully considered to determine whether or not the type of heating equipment specified will operate properly. If the available draft of the chimney is less than the draft required for the particular heating equipment specified, auxiliary means such as forced or induced draft 'should be included. Until recently most chimneys for residences were constructed of masonry. The National Building Code of the National Board of Fire Underwriters specifies a minimum of 4 in. of masonry enclosing a fire clay flue liner.. Within the past several years, however, the Underwriters' Laboratories have tested and listed as approved Type A flues, several chimneys of prefabri cated construction. Their advantages, compared with masonry chimneys, are ease of installation, and usually lower cost and a greater degree of safety under abnormal firing conditions. Through the use of insulation or other means to reduce heat transfer through the chimney walls, these Type A HEIGHT OF CHIMNEY ABOVE CENTER LINE OF THIMBLE - FEET Fig. 5. Available Dbaft fob 9" x 9* and 9' x 13* Masoney Chimneys (Ambient Temperature 60 F) of nominal 9 X 9-in. and 9 X 13-in. masonry chimneys with an ambient temperature of 0 F for a range of effective heights from 5 to 32 ft, a range of entering flue-gas temperatures from 200 to 1000 F, and for mass flow rates of 83 and 300 lb per hr. Fig. 5 shows the same information for an ambient temperature of 60 F. The available drafts produced by 9 X 9-in. and 9 X 13-in. masonry chimneys are equal for practical purposes over the range of mass flow from 83 to 300 lb per hr.6 In tests of these chimneys the smaller chimney produced slightly greater drafts in the lower end of the range of mass flow rates whereas the larger chimney produced slightly higher drafts in the upper end of the range. The chimney height for heating plants that operate on an on-off or highfire low-fire cycle should be selected to produce the desired draft from Fig. 5 since this class of heating system is required to operate at rated input for short periods when the outdoor temperature is 60 F. Heating plants whose fuel-burning rate is gradually increased as the outdoor temperature decreases are not required to operate at rated input except when outdoor temperatures approach-design conditions. For such systems, the chimney height should be selected from Fig. 4 which shows the available draft for 430 CHAPTER 17 i ,1956 Guide an outdoor temperature of 0 F since this is. likely to be the more critical condition with respect to chimney draft. The available draft, for outdoor temperatures between 0 F and 60 F can be obtained by interpolation from Figs. 4 and 5 with only slight error. / '. ~ Fig. 6 is a graphical representation of the available draft for a 13-ft brick chimney with a nominal 8 X 8-in. flue liner7 over a wide range of mass flow rates and for inlet flue-gas temperatures ranging from. 200 to 1000 F. This family of curves is a typical group of performance curves showing that there is a certain mass flow rate that produces a maximum available draft for any flue-gas temperature. The following approximate method may alternately be used to determine the available draft for small residential chimneys, from 10 to 25 ft in height Chiihneys and Draft Calculations ' 431 H = chimney height, feet. Ti = chimney inlet temperature, Fahrenheit degrees, absolute. To = ambient air temperature, Fahrenheit degrees, absolute. The clay-lined brick chimney is the most commonly used chimney, but recently other building materials have been used for reasons of economy or convenience. Investigations have established that the results shown in Figs. 4 and 5 for brick chimneys can be used, with slight error, for chimneys made of shale tile, concrete block, or cinder block.8 SHORT CHIMNEYS The application of heating systems to one-story houses without base ments requires special consideration because the chimneys in such houses FLUE-CAS FLOW-POUNDS PER HR Fig. 6. Available Chimney Draft fob 13 Ft Brick Chimney*' b * Square Flue Liner 6J z. 65 in. inside. b Barometric Pressure 29.92 in. Hg. Air Temperature 60F. and with internal cross-section areas from 35 to 55 sq in., with a maximum probable error of 15 percent at the same flow and temperature con ditions. This method is based on the chimney eflicieneies7 shown in Fig. 7 and the ideal draft computed from the chimney inlet temperature. The available draft may be expressed as: > = nj)i (13) where nc = chimney efficiency taken from Fig. 7 at the desired conditions of tempera ture and flow. D-, = ideal draft, calculated from Equation 14, assuming that the barometric pressure is 29.92 in Hg, and the ambient temperature is 60 F. D, 0.2554BJS (14) ' where Bo = barometric pressure, inches of mercury. B Derived from temperature plots. Liner 8 x 8 in. outside, 6f x 6} inside. Height 13 ft. are often made so low in height for architectural reasons that they produce insufficient draft for some kinds of heating systems. Gas-burning devices do not necessarily require a chimney for proper combustion of the gas, but the chimney must be of adequate size and height to carry the flue gases out of the building since it is undesirable and contrary to American Standards to have the products of combustion discharged in the living space. If a natural-draft oil-burning device is operated with insufficient draft because of a short chimney, smoky combustion usually occurs, pulsations are possible in the combustion chamber, the chimney or smokepipe may become blocked with soot, and the capacity of the heating equip ment may be reduced to the point of inadequacy. Insufficient draft is not ordinarily the cause of smoky combustion in coal-burning heaters, but too short a chimney can cause slow pickup of the fire and insufficient heating capacity of the device. ' Based on the amount of draft usually required for present-day heating systems at rated output, any chimney with an effective height of less than 15 ft above the center line of the thimble should be regarded as a short chimney. In short chimneys every precaution should be taken to attain the highest possible average temperature in .the chimney and the lowest practicable friction loss. Short chimneys of conventional construction are likely to produce from 60 to 90 percent of the ideal draft and, therefore, 432 CHAPTER 17 1956 Guide the draft would only be increased from 10 to 40 percent if all friction and cooling could be eliminated. . The available draft for short chimneys can perhaps be determined most readily by using Equation 13, Fig. 8, and Table 1. Fig. 8 shows the rela tionship between effective chimney height, inlet flue gas temperature, and the ideal draft that would be produced for two values of outside temperature if there were neither friction nor cooling of the gases as they traversed the chimney. After obtaining the ideal draft for a given chimney height and entering flue gas temperature from Fig. 8 and selecting the appropriate efficiency value from Table 1, the available draft can be computed from Equation 13. Fig. 8 can be used in reverse in conjunction with efficiency Fig. 8. Ideal Draft for Short Chimneys at Outside Temperatures of 0 F and 60 F. values from Table 1 to determine what chimney height is required to produce the required draft at rated output for a given heating appliance. Fig. 7 shows that the efficiency of a given chimney varies with the mass flow-rate of gases and with the entering flue gas temperature. The effi ciency also varies with the height for a given construction and depends somewhat on the method used to connect the smokepipe to the chimney and the amount of exposure to the outdoor air. Experimental data are not sufficiently complete to tabulate efficiencies that take into account all of these variables. However, recommended values of efficiency for several sizes of domestic chimneys of masonry materials and of metal have been selected from the literature6 -7 8-9 and summarized in Table 1 for use with'. Fig. 8 in determining the available draft produced by short chimneys of 15 ft in height or lower. In parts A and B of Table 1 the value of efficiency chosen from the range cited should be increased as the chimney inlet temper ature increases over the applicable range. In part C of Table 1 the effi ciency values listed will yield the available draft for the range of mass flows, inlet flue gas temperatures, and chimney height shown within 10 percent. . In the application of short chimneys, observance of the following pre- Chimneys and Draft Calculations 433 cautions will assist in obtaining the highest practicable draft and may cure unsatisfactory operation of the chimney and heating plant in certain in stances: 1. Use a minimum length of horizontal smokepipe between the heater and chimney. ' 2. Insulate the smokepipe and the chimney itself, if made of metal. Insulation of the chimney liner in masonry chimneys reduces the heat loss from the flue gases and the infiltration of cold air. Table 1. Efficiency of Short Chimneys "j ` ` JK Li A. Mabonbt Chxmnstb Height h ft Hue Gas How Rate lb/hr IntpHwJ Liner Size. in. Dia. 7 7x7 7Kd 5 to 15 Ef Sciency, Percent 90 75-82 65-76 65-80 200 83-84 67-85 82-88 315 75-89 67-86 81-89 (Inlot Flu e Gas Temp 200 to 1000) B. Uninsulated Metal Chimnbys ' Height h ft Flue Gas How Rate Jb/hr Internal Diameter, in. 68 Efficient7, Percent j 4 to 8 90 90-100 85-95 200 a 83-88 315 a 70-80 (Inlet Flue Gas Temp. 200 to 600 F) C. Metal Chxhnets** TT1 rL J --1 Height A ft ' 8 to 14 Uninsulated / 1-in. insulation with dead air space around chimney 1-in. insulation with 1-in. open air space around chimney . Efficiency, Percent 76 | 85 ) 81 t Six-inch chimney not recommended for these flow rates. Internal dia. 6-in; flue gas flow rate 50 to 125 lb/hr; inlet flue gas temp. 200 to 1000 F. 3. Do not use an oversized chimney because larger chimneys produce greater cooling of the flue gases. # 4. Avoid downdrafts by proper construction above the roof or by the use of a suitable chimney cap. 5. Avoid the. use of barometric dampers in the smokepipe of natural-draft heat ers since most barometric dampers permit enough cold air to leak into the chimney to reduce the draft appreciably. 6. Avoid air leaks in the smokepipe and chimney. 7. Avoid connecting more than one heating device to a single chimney. . 8. Use construction materials of low heat capacity if the chimney draft must increase quickly for an intermittently-fired heating device. 9. Do not operate a kitchen exhaust fan unless an air intake of ample area is used to prevent lowering the house pressure. 10. Avoid tight utility closets so the chimney draft will not be required to do the added work of drawing combustion air into the closet from the surroundings. 434 CHAPTER 17 ' 1956 Guide DETERMINING RESIDENTIAL CHIMNEY SIZES /. - The flue sizes for small residential chimneys are governed by the National Building Code of the National Board of Fire Underwriters for gas-burning appliances. Chimney areas for liquid- and solid-fuel-buming devices are selected primarily to meet the requirements of local building codes, but these requirements are not determined by any rigorous formula based on physical principles. By calculating the available draft for the chimney in question, and comparing it with the performance values of the heating unit (either natural or forced draft type) at the desired output, it is possible to de termine whether the chimney is adequate in height for the particular heating unit it serves. For calculations where the fuel rate and the percentage C02 are the only known factors, the flue-gas rate can easily be determined for coal, oil and gas from Fig. 9. By entering Fig. 9 at the percentage C02, moving verti- FLUE CAS FLOW-POUNDS PER HR Fig. 9. Graphical Evaluation op Rate of Flue Gas Flow prom Percent CO, and Fuel Rate* * Average density gas 0.0845 lb per cu ft, 62 F. Average -weight oil 7.08 lb per gal, 60 F. caily to the curve for the type of fuel, and then moving horizontally to the fuel rate, the flue-gas rate in pounds per hour may be determined for any fuel.7 Any of the described methods of determining available draft may be used, but a graphical solution to the problem may be had for the 8 X 8-in. chimney from Figs. 6, 7 and 9. This solution can be best explained by a numerical example. Example 8: Determine whether a 13-ft, 8 x 8-in. nominal-size flue is sufficient for a coal-heating unit rated at 0.03 in. of water draft at 400 F inlet temperature, fuel rate being 10 lb per hr of bituminous coal, with 10 percent CO,. Solution: From Fig. 9, a flue-gas rate of approximately 180 lb per hr is obtainedThe available draft for a 180 lb per hr fuel rate, and an inlet temperature of 400 F, obtained from Fig. 6, is 0.056 in. of water. This indicates that the chimney is ade quate. The selection of chimney areas for liquid- and solid-fuel-buming devices is difficult because of the variability in efficiency of different models, the possibility that soot on the lining will restrict the chimney area, and the variation in combustion air requirements of different solid fuels. Figs. 6 and 7 show that a given chimney produces a maximum available draft and Chimneys and Draft Calculations 435 a maximum efficiency for some intermediate mass flow rate for any selected inlet flue-gas temperature. For mass flow rates lower than the optimum the greater cooling of the . gases in the chimney causes lower available draft, whereas for mass flow rates above the optimum the greater friction losses reduce the available draft. A chimney for a given heating system should probably be designed to operate at its point of maximum efficiency and maximum available draft for its full rated output. A chimney would have an accelerating effect10 on the combustion rate of a solid-fuel burning device if it were operating to,the left of the optimum point in Fig. 6 because an additional increment in mass flow rate would increase the. available draft a small amount and tend to increase the mass flow still more. On the other hand, a chimney operating to the right of the optimum point in Fig. 6 would tend to decelerate the combustion rate for any small increase in mass flow rate. Data are not complete for the selection of proper chimney areas, for heating plants of different capacities, but some information on the effect of cross-section area on the capacity of masonry chimneys is provided by Table 2. Approximate Flue-Gas Flow Rates for Maximum Available . Draft in Masonry Chimneys Nominal External Lineb Dimensions Internal Area of Liner, Sq In 200 Flue Gas Temperature at Chimney Inlet, Fahr. 600 1000 200 600 1000 Mass Flow Hate, LB/HR Flue Gas Vekxa^at Chimney 9 in. Dia. 38.5 170 150 130 175 250 300 9 in. x 9 in. 12 in. Dia. 49 78.5 215 306 334 290 Above Above 175 150 4_00 600 9 in. x 13 in. 77 320 320 295 Above Above 150 _ _ 320 320 recent tests8-11 on several chimneys with liners having nominal outside dimensions: 9 in. diameter, 12 in. diameter, 9X9 in., and 9 X 13 in. These tests showed that for flue gas rates up to 200 lb per hr, and entering flue gas temperatures from 200 to 1000 F, the 9-in round liner provided an available draft equal to, or greater than, that produced by the other three larger liners. When the flue gas rate was increased to 320 lb per hr, the three larger liners produced a little more draft than the smallest one for entering flue gas temperatures above 600 F. Other data9 show that metal chimneys with an internal diameter of 6 in. should not be used for mass flow rates greater than 130 lb per hr. Table 2 shows approximate values of the mass flow rates and flue-gas velocities at the chimney inlet that produce the maximum available draft for masonry chimneys8 of several conventional sizes and with an effective height of 15 ft. This table shows that a 9-in. round chimney is best suited to mass flow rates from 130 to 170 lb per hr, a 9 X 9-in. chimney performs best for flow rates from about 200 to 300 lb per hr, and a 9 X 13jn. and 12 in. round chimneys are best suited to flow rates above 300 lb per These results were obtained with clean chimneys, so that conclusions about chimney areas require some modification if soot deposits are taken mto consideration. Soot deposits in chimneys reduce the effective area of the liner and may in some cases entirely close the passage Soot deposits are likely to be 436 CHAPTER 17 1956 Guide greater in the horizontal passages in the heating plant, the breeching, and the smokepipe, than in the vertical chimney liner. An increase in the liner diameter of one inch above that required for a clean chimney will probably make adequate allowance for soot deposits in all but the worst cases. Where smoky combustion is likely to occur and the mass flow rates on a clean chimney basis approach those listed in Table 2, the next larger commercial size liner should be used. Smoky combustion with oil-burning devices, particularly with vaporizing oil burners, is likely to be caused by inadequate draft which is often due to insufficient chimney height. For coal, inadequate chimney height or chimney area may be a contributing cause, but smoky combustion with coal is related to fuel characteristics and firing methods. Therefore, an increase in chimney area will usually not cure smoky combustion of a coal-burning device, but can be expected to lengthen the interval between cleanings. New standard sizes of clay flue linings were recently developed by the Table 3. Drafts Required by Typical Residential Heating Devices or Appliances Device Draft, Inches Water Stack Tempera ture* F Deo Space Heater, Coal Burning........................................ .. 0.06 to 0.08 0.06 0.06b 0.06 0.03" 0.05" or less 0.04b 0.06b 4 Draft in firebox. ^ For chestnut sized anthracite. 0 18 in. from heater. 1000 860 900 8_60 _ 400 900 industry and approved by the American Standards Association, in order to effect economies that can be derived from coordination of the dimensions of building materials. These linings are known as modular clay flue linings, and the dimensions and tolerances are summarized in ASA Stand ard A62.4-47. As the effective areas of these liners are somewhat smaller than those of the corresponding linings used previously, they cannot be used in certain municipalities where building codes specify minimum areas based on the older dimensions. DRAFT REQUIREMENTS OF APPLIANCES Typical flue-gas temperatures and drafts required at rated output for several kinds of domestic heating appliances12 are contained in Table 3. Chimney height and chimney area for cast iron boilers are specified in the I = B = R Testing and Rating Code of the Institute of Boiler and Ra diator Manufacturers. Mechanically-fired devices such as oil burners and stokers are equipped with blowers, and therefore, the chimney is not required to overcome the resistance of the fuel bed or burner. Nevertheless, a draft in the firebox, of about 0.03 in. of water is desirable so that leakage, if any, will be into the firebox rather than outward from it. Insufficient draft for natural-draft appliances is likely with installations in attics or in one-story basementless houses. Automatic oil-burning Chimneys and Draft Calculations 437 space heaters, floor furnaces, and warm air furnaces employing naturaldraft vaporizing burners require a draft of 0.06 to 0.08 in. water for outdoor temperatures of 60 F. Coal-burning heaters and furnaces which attain design rating of 0 F would require about the same draft. For such require ments, data from Figure 8 and Table 1 show that an effective chimney height, above chimney inlet, should be a minimum of 8 to 12 ft. Because temperature drop and friction loss in the flue pipe cannot be calculated accurately,7 and the resistance of various chimney connections is uncertain, the minimum calculated heights should have a generous factor of safety applied to allow for these and other uncertainties. Where ample height cannot be provided, forced or induced draft should be provided. Extreme care should be used in the application of forced draft to avoid producing a pressure in the combustion chambers, because they are not usually de signed to avoid the leakage of toxic gases which might result. Induced draft by means of motor-driven fans or blowers will solve lowdraft problems, but would usually be employed for residential systems only as a last resort. Operation of a blower entails some cost, introduces main tenance requirements, and may be dangerous in event of power failure unless suitable protective devices are used. Induced draft fans designed to resist effects of high temperature and corrosion are available. Fans not carefully designed or modified to meet these conditions should not be ap plied to this service. CHIMNEYS FOR GAS APPLIANCES The Approval Requirements of the American Gas Association are such that a gas-fired appliance must be able to operate at its rated input (plus 10 or 15 percent) without a chimney connection, and without producing carbon monoxide. The primary functions of the chimney for the gas-fired appliance are to remove the products of combustion from the living space and to assure safety to the building. The chimney therefore becomes es sentially a vent and, in fact, the vents tested and listed by Underwriters' Laboratories for use only with gas appliances were for some time designated as Type B Gas Appliance Vents. Their use is limited to appliances ap proved by the American Gas Association and operating with flue gas tem peratures not in excess of 550 F at the inlet of the draft hood. A draft hood is always required in connection with a Type B flue. The Type B-W gas flue is further limited to the venting of wall heaters having an input of not more than 50,000 Btu per hr. Because of the low temperatures to which gas flues are limited care-should be taken to ascertain that the appliance is not convertible to fuels other than gas and that the appliance is approved by the American Gas Associa tion. It is well also to be certain that gas fuel will continue to be available to the building. . Chimneys for venting appliances designed for burning gas, can therefore be low in height, but must have adequate area. The height is usually - established by the building height. Chimney sizes are usually selected on the basis of heat input of the appliance. The chimney sizes adopted by the American Standards Association and the National Board of Fire Un derwriters in 1950 for gas appliances13 are shown in Fig. 10. Additional provisions of ASA Standard Z21.30-1950 relating to chimney size are: 1. In no case shall the vent area be less than the area of a 3-in. diameter pipe. 2. When more than one appliance vents into a flue or vent, the flue or vent area 438 CHAPTER 17 1956 Guide shall be not less than the area, of the largest flue or vent connector plus 50 per cent of the areas of the additional flue or vent connectors. 3. An elliptical flue or vent may be used provided its flue gas venting capacity is equal to the capacity of the round pipe for which it is substituted. Since Fig. 10 has been prepared for circular flues, relative capacities for rectangular and semi-elliptical flues14 are shown in Fig. 11. Heating appliances designed to bum gas, as well as appliances converted to gas biuming, except those equipped with power type burners and ex- Chimneys and Draft Calculations 439 relief opening is always open, and consequently some air is drawn into the chimney. This air lowers the gas temperature in the chimney, but it also lowers the dew-point of the gases and tends to prevent condensation. The installation of conversion burner equipment in large boilers is usually made in accordance with regulations of the local gas company. In such installations a definite chimney draft may be required for proper combustion, and consequently the foregoing reference to the use of draft hoods would not apply. The products of complete combustion of gas are water vapor (HyO) and carbon dioxide (C02). In the case of manufactured gas, the presence of organic sulfur compounds, generally between 3 and 15 grains per hun dred cubic feet, gives rise to minute percentages of sulfur dioxide and sulfur trioxide. The volume of water vapor in the flue products from natural or coke oven gas is about twice the volume of carbon dioxide. It is extremely Fig. 10. Capacity in Btu per Hour for Gas Appliance Flues or Vents cepting conversion burner installations in excess of 400,000 Btu per hour input in large steel boilers, are always equipped with a draft hood attached to the flue outlet of the appliance. This draft hood is required if the: appliance is to meet the approval requirements of the American Gas As sociation and the American Standards Association, and is essential forjsafe operation. It is designed to prevent excessive chimney draft which would lower appliance efficiency, to prevent a blocked flue or a down-draft in the chimney from impairing combustion, to provide a relief opening for, the products of combustion during down-draft or blocked flue conditions, and to prevent spillage of the products of combustion to the space surrounding the appliance, if there is a chimney draft equivalent to that provided by a 3-ft chimney. As the draft hood is designed without moving parts, the Fig. 11. Capacity of a Rectangular Flub or a Semi-Elliptical Flue, with Semi-Circular Ends Having Its Minimum Width Equal to the Diameter of a Circular Flue, Compared with the Capacity of the Circular Flue important that the chimney be tight and resistant to corrosion, not only from moisture, but also from dilute sulfur trioxide. Clay linings with joints which prevent retention of moisture and linings made of non-corrosive materials, are advantageous. The interior protec tion of unlined chimneys by applying an asphalt-chromate emulsion has been investigated by some gas companies but the material is not of current interest because insurance companies do not favor potentially combustible coatings.16 An investigation of damage occurring in 78,129 chimneys used for vent_ mg gas appliances in a severe climate has been made- by the Minneapolis Gas Company with the results shown in Table 4 taken from Reference 15. Advice regarding recommended practice and materials for flue connec tions and chimney linings can usually be obtained from the local gas com pany, and should be given careful consideration. RECOMMENDATIONS OF THE NATIONAL BOARD OF FIRE UNDERWRITERS For general data on the construction of chimneys, reference should be made to the National Building Code, recommended by the National Board 440 CHAPTER 17 1956 Guide of Fire Underwriters, Article X, Section 1001 to 1006, in which the following are some of the important provisions listed in the 1951 edition: 1. Flue Connections Required. Every heating apparatus pr heat producing ap pliance requiring a flue connection shall be connected with a flue conforming to the provisions of this article. This shall not include electric appliances; gas appliances, except as specifically required in this article; or oil fired appliances especially de signed for use without flue connection. 2. Vse of Nonconforming Flues. Flues not conforming to the requirements of this article for chimneys, metal smokestacks or vents for gas appliances, shall not be used unless listed by Underwriters' Laboratories, Inc., installed in full compliance with the listing and the manufacturer's instructions, and approved for such use by the building official. 3. Smoke Pipe Connections. a. No flue shall have smoke pipe connections in more than one story of a building, unless provision is made for effectively closing smoke pipe openings with devices made of noncombustible materials whenever their use is discontinued temporarily, and. completely closing them with masonry when discontinued permanently. b. Two or more smoke pipes shall not be joined for a single connection, unless the smoke pipes and flue are of sufficient size to serve all the appliances thus con nected. c. The smoke pipe of a heating appliance shall not be connected into the flue of an incinerator which has the rubbish chute identical with the smoke flue. 4. Construction of Chimneys. a. Chimneys hereafter erected within or attached to a structure shall be con structed in compliance with the provisions of this section. b. Chimneys shall extend at least 3 ft above the highest point where they pass through the roof of the building, and at least 2 ft higher than any ridge within 10 ft of such chimney. c. Chimneys shall be wholly supported on masonry or self-supporting fireproof construction. d. No chimney shall be corbeled from a wall more than 6 in.; nor shall a chimney be corbeled from a wall which is less than 12 in. in thickness, unless it projects equally on each side of the wall; provided that in the second story of 2-story dwellings cor beling of chimneys on the exterior of the enclosing walls may equal the wall thickness. In every case the corbeling shall not exceed 1 in. projection for each course of brick projected. e. No change in the size or shape of a chimney, where the chimney passes through the roof, Bhall be made within a distance of 6 in. above or below the roof joists or rafters. 5. Chimneys for Healing Appliances, Low Heat Industrial Appliances and Portable Type Incinerators. . a. Chimneys for stoves, cooking ranges, warm air, hot water and low pressure steam heating furnaces, fireplaces, and low heat industrial appliances, other than chimneys for incinerators of nonportable type, shall be constructed of solid masonry units or of reinforced concrete. The walls shall be properly bonded or tied with corrosion-resistant metal anchors. In dwellings and buildings of like heating re quirements, the thickness of the chimney shall be not less than 4 in. In other build ings the thickness shall be not less than 8 in., except that rubble stone masonry shall be not less than 12 in. thick. ' b. Every such chimney hereafter erected or altered shall be lined with a flue lin ing conforming to the requirements below. c. Flue linings shall be made of fire clay or other refractory clay which will with stand the action of flue gases and resist, without softening or cracking, the tempera tures to which they will be subjected, but not less than 2000 F. Flue linings may be of cast iron of approved quality, form and construction. d. Required clay flue linings Bhall be not less than f in. thick for the smaller flues, ana shall increase in thickness for the larger flues. e. Flue linings shall be installed ahead of the construction of the chimney as it is Chimneys and Draft Calculations 44.1 carried up, carefully bedded one on the other in Type A, Type B, or fire clay mortar with close fitting joints left smooth on the inside. f. Flue linings shall start from a point not less than 8 in. below the intake, or, in the case of fireplaces, from the throat of the fireplace. They shall extend, as nearly vertically as possible, for the entire height of the chimney, and be extended 4 in. above the top of cap of the chimney. g. Cleanouts for flues or fireplaces shall be equipped with cast-iron doors and frames arranged to remain tightly closed when not in use. h. When two or more flues are contained in the same chimney, at least every third flue shall be separated by masonry at least 4 in. thick bonded into the masonry wall of the chimney. Where flue linings are not so separated, the joints of adjacent flue linings shall be staggered at least 7 in. 6. Sizes of Flues. a. The cross-sectional area of smoke flues shall be designed and proportioned to Table 4. Results of Field Subvet on Chimney Damage Type of Construction Number of Chimneys Number Reported Damaged . Percent - Damaged Chimneys without liners................................... Chimneys with sewer tile construction......... Wilder metal coated with asphalt chromate emulsion............................................................ Steel coated with plastic................................... Vitreous enamel on steel.................................. Aluminum............................................. ... ......... 4720 8410 5185 9200 614 50,000 562 104 291 1928 No record 228 11.9 1.2 5.6 21.0 -- 0.45 meet the conditions of temperature, within and without flue, thickness of masonry, exposure, shape and material of flue, and other influences. The National Building Code specifies lined chimneys and metal smoke stacks for all gas appliances which may be converted readily to the use of solid or liquid fuel, and also for all boilers and furnaces, except those having a flue-gas temperature not exceeding 550 F at the outlet of the draft hood when burning gas at the manufacturer's rating and which may, therefore, be connected to Type B vent piping. Approved Type B vent piping is noncombustible, corrosion-resistant piping of adequate strength and heat-insulating value, and having bell and spigot or other acceptable joints. Fig. 10 may be used for selection of vent-pipe size. Important points to be considered in the use of Type B vent piping are: 1. Type B flues must be plainly and permanently marked at the point where the vent connection enters the flue: For Use of Cos Appliances Only. . 2. Type B gas vents shall be.installed with a clearance to combustible material or construction, whether plastered or unplastered, of not less than one inch, provided that for vents of floor furnaces, such clearance shall be not less than 3 ft from the outlet of the draft hood, measured along the center line of the vent piping. Other important points that should be considered for flues and vents for gas appliances are as follows: 1. Clearances from combustible material to gas appliance vent piping other than approved Type B gas vents shall be in accordance with the Building Code Standards 442 CHAPTER 17 1956 Guide of the National Board of Fire Underwriters for the Installation of Heat Producing Appliances, Heating, Ventilating, Air Conditioning, Blower and Exhaust Systems. 2. Every flue-connected appliance, except an incinerator, unless its construction serves the same purpose, shall be equipped with an effective draft hood which either (a) has been approved as part of the appliance or (b) complies with nationally recog nized standards for draft hoods. The draft hood shall be attached to the flue collar of the appliance as conditions permit, and in a position for which it is designed with reference to horizontal and vertical planes. The draft hood shall be so located that the relief opening is not obstructed by any part of the appliance or adjacent con struction. 3. No vent pipe from a gas appliance shall be interconnected with any other vent pipe, smpke pipe, or flue, unless such gas appliance is eauipped with an automatic device to prevent the escape of unburned gas at the main burner or burners. Where a gas appliance vent pipe is joined with a smoke pipe from an appliance burning some other type of fuel, for connection into a single nue opening, they shall be-joined by a Y fitting located as close as practicable to the chimney. With liquefied petro leum gases, the automatic device to prevent the escape of unburned gas shall shut off the pilot light, as well as the main burner or burners. Recent tests of masonry chimneys16 made of a variety of materials have developed additional recommendations regarding the construction of masonry chimneys that will decrease the hazard to surrounding combusti ble materials. GENERAL CONSIDERATIONS FOR CHIMNEYS The draft of domestic chimneys may be subject to a variety of influences not usually encountered in power chimneys17 because of the low available draft often supplied by a short chimney. Horizontal winds have an aspirating effect as they cross the chimney and are an aid to draft. How ever, surrounding objects, such as trees or other buildings, may affect the direction of the wind at the chimney top, and may even direct it down the chimney, tending to reduce the draft or even to cause it to charige to a positive pressure. It is not to be assumed that increasing the cross-sectional area of a chim ney will always effect a cure for poor draft. The opposite result may occur because of the cooling effect of the larger area, and the effect of recirculation of the flue gases. The flow of gases into the chimney top has been observed at low rates, and recirculation in small residential chimneys has been noted throughout the entire length of a chimney and smoke pipe, with the greater amount of recirculation occurring at the thimble. The effect of recircula tion decreases with chimney height and the increase in flue-gas velocity. It is also important to consider the course of the air supply for proper combustion. The boiler or furnace is usually located in the basement. In the majority of cases, the furnace room has windows and doors opening to the outside on two or more sides of the house. Through these enough air leaks into the furnace room to sustain combustion. In some cases, how ever, windows and doors are so tight as to restrict the flow of combustion air, and thereby affect the correct operation of the chimney. In case the boiler room is fairly tight and is open to the outside on only one side of the house, then the draft will be affected in windy weather even with windows or doors open. If the wind is blowing toward the boiler room, the draft will be increased, but if blowing in the opposite direction, the draft may be decreased. ' The surrounding of a heating appliance with a restrictive enclosure that will limit entrance of combustion air is more likely to occur in a small utility closet installation on the first floor than in a basement installation. An opening with a free area approximately twice the area of the smoke- Chimneys and Draft Calculations 443 pipe should therefore, be provided between the utility closet and the living space or the outdoors. If the utility closet is connected to the outdoors, greater difficulty with wind pressures will be encountered. Where a draft regulator is used it should have ample communication with the same space from which the combustion air is taken. Where forced warm air furnaces are enclosed in utility closets, care should be used to make the return air connection inside the utility closet airtight so that the blower cannot reduce the pressure in the closet and cause a downdraft in the chimney. Two or more chimneys, either large or small, should never be connected together. If connected at the bottom, hot gases in the U-tube thus formed would be in unstable equilibrium. Cold air from the top would descend through one such chimney and drive the hot gases out of the other, thus annulling the draft. .......................... More than one device can be served by one chimney. Batteries of boilers are commonly connected to a single chimney in power plants. However, if two or more chimneys are used, each chimney should be used separately for part of the boilers, and not connected in manifold with an other chimney, in order to avoid the difficulty described previously. . In domestic installations it is sometimes necessary to serve a space heater or cooking stove and a water heater with the same chimney flue. This is not desirable, especially for low chimneys, since doors left open on one device, while it is unfired, will tend to annul the draft on another device. Gas burning devices, with their draft hoods and lack of draft dampers, are. especially bad in this respect. The traditional method of avoiding this with brick chimneys has been to construct multiple-flue chimneys, so that each fuel-burning device could be served by a separate opening. If two devices must be served by one flue-opening in a chimney, their connections to the chimney should not be located opposite each other. The con nection from the larger device should be reasonably low, and that from the smaller, up near the ceiling, so that each device can be serviced as well as possible, regardless of the treatment of the other: Even where such precautions are taken, there is, under unusual condi tions, some possibility of flow of combustible gases from one appliance into another. Reverse flow of cooled gases has been demonstrated in a chimney at very low rates of flow.7 Under certain similar quiescent conditions, accidental discharge of combustible gases from a defective device into a chimney could result in flow of these gases counter current into the combus tion chamber of another device attached to the same chimney. If ignition occurred in this second device, an explosion could result. Excessive height in a chimney does no harm, but means for controlling the draft are more than ordinarily essential if the chimney is too tall. Coal-burning devices often have air leaks around the firebox, and the draft doors sometimes fit so poorly that the fire cannot be controlled at a low rate. The simplest remedy for such cases is the barometric damper which Admits air into the flue pipe and thus reduces draft. Where a chimney serves a fireplace, it is important that no other heating device be connected to it unless the fireplace is effectively sealed. REFERENCES 1 A Study of Flow Phenomena in the Wake of Smokestacks, by R. H. Sherlock and No^2<f*?94i) (ePartment f Engineering Research, University oj Michigan, Bulletin * Notes on Power Plant Design, by E. F. Miller and James Holt (Massachusetts Institute of Technology, 1930). 444 CHAPTER 17 1956 Guide J Friction Factors for Pipe Flow, by L. F. Moody (A.S.M.E. Transactions, Vol. 66 1944 p. 671). i *4 Mechanical Engineers1 Handbook, Eleventh Edition, by R. T. Kent, Editor in Chief (John Wiley and Sons, Inc.). ^ T, r* ' 6 Handbook of Building Construction, by G. A. Hool and N. C. Johnson (McGraw- Hill Book Co., Inc., New York, 1929). . e Observed Performance of Some Experimental Chimneys, by K. o. Dili, r. K. Achenbach and J. T. Duck (A.S.H.V.E. Transactions, Vol. 48,1942, p. 351). 7 Performance of Residential Chimneys, by L. B. Schmitt and R. B. Engdahl (A.S.H.V.E. Transactions, Vol. 55, 1949, p. 241). .... 8 Performance of Fourteen Masonry Chimneys Under Steady State Conditions, byP. R. Achenbach and S. D. Cole (A.S.H.V.E. Transactions, Vol. 55, 1949, p. 129). ' 9 A Theoretical and Experimental Investigation of the Performance of Some Short Flues Under Steady-State Conditions, by Robert D. Thulman and William.H. Shenkle (Thesis at Massachusetts Institute of Technology, June 1951). 10 Physics of Chimneys; by P. R. Achenbach (Physics Today, Vol. 2, No. 12, Dec. 1949). 11 Performance of Masonry Chimneys for Houses, by Robert K. Thulman (Hous ing and Home Finance Agency, Technical Payer No. IS, Aug. 1949). . ' i* National Bureau of Standards Commercial Standards: CS101-43 Oil-Burning Space Heaters Equipped With Vaporizing Pot-Type Burners, CS75-42 Automatic Mechanical Oil Burners Designed for Domestic Installations, CS(E)104-43 Warm Air Furnaces Equipped With Vaporizing Pot-Type Burners; CS109-44 Solid-Fuel Burn ing Forced Air Furnaces, CS113-44 Oil-Burning Floor Furnaces Equipped With Vaporizing Pot-Type Burners. . t _ 4 .. . ... 13 American Standard Installation of Gas Piping and Gas Appliances in Build ings (American Standards Association, Z21.30-1950). 14 Comfort Heating, 1938, p. 71 (American Gas Association). . 15 Sizing of Chimneys and Flues Used for Gas Appliances by C. G. Segeler on be half of American Gas Association for 6th International Gas Conference, 1955. 18 Fire Hazard Tests with Masonry Chimneys, by Nolan D. Mitchell (National Fire Protection Association Quarterly, Oct. 1949). 17 Chimneys and Draft (Chapter 32 in Winter Air Conditioning, by S. Konzo, pub lished by National Warm Air Heating and Air Conditioning Association, 1939). CHAPTER 18 ESTIMATING FUEL CONSUMPTION FOR SPACE HEATING Bases of Fuel Estimates; Season Efficiency; Calculated Heat Loss Method: Compu tation and Application, Examples and Solutions, Short Methods for Estimating Heat Loss; Degree-Day Method: Computation and Application, Unit Fuel Consumption per Degree-Day, Estimating Consumption for Various Fuels, Examples and Solutions, Degree-Day as an Operating Unit; Industrial Degree-Days; Maximum Demand and Load Factors IT IS often necessary to estimate the anticipated heat requirements and fuel consumptions of heating plants for either short or long terms of oper ation. There are various general methods for estimating these condi tions, and frequently the methods can be so modified as even to become useful in evaluating the effectiveness of heat production or fuel utilization during plant operation. In applying a consumption-estimating method to a particular building, it is well to note that the bases of the methods may vary as to reliability. For example: 1. Records of past heat requirements or fuel consumption of the particular build ing are a better basis for estimates than are averages from records of similar buildings. 2. In the absence of past records for a particular building, the data from similar plants in the same locality may become very helpful. 3. Averages of consumption taken from many types of plants in many types of buildings in various localities can only produce an average estimate which may prove to be very inaccurate as applied to the particular building being considered. 4. Estimates based upon computed heat losses (without benefit of operating data) are wholly dependent, of course, on the degree to which the computation represents the actual facts. Where unusual operating conditions exist due to factors such as ex cessive ventilation, abnormal inside temperatures and heat gains from external sources, or where, in the case of proposed buildings of unusual design, no information is available regarding former consumption, it is necessary to estimate fuel consumption from the computed heat losses. In preparing fuel consumption estimates it is well to realize that any estimating method used will produce a more reliable result over a long period operation than over a short period. Nearly all of the methods in common use will give trustworthy results over a full annual heating season, and in some cases such estimates will prove consistent within themselves for monthly periods. As the period of the estimate is shortened, there is ' more chance that some factor not allowed for in the estimating method will become dominant, and thus give discrepant and even ridiculous results. The Calculated Heat-Loss Method, and the Degree-Day Method of estimating fuel requirements are illustrative of all methods used. Both methods are based upon an estimate of seasonal efficiency. The former s also based upon an estimate of average seasonal temperature. Neither method takes into account factors which are difficult to evaluate, such as 445 446 CHAPTER 18 1956 Guide opening of windows, abnormal heating of the building, poor design of heat ing system, sun effect, and other variations. The Degree-Day Method is the more practical since it is based, in part, on actual consumption data. The presentation of the two illustrative estimating methods will be pre ceded by a discussion of seasonal efficiency. SEASONAL EFFICIENCY The seasonal efficiency differs from the measured efficiency of the fuelfired heating unit because it is affected by the many minor sources of extraneous heat gain and heat loss. Throughout a season, useful heat is supplied to a building not only by the heating unit, but also by the external surfaces of the heating unit, the flue pipe, and the chimney. In addition, heat is gained from lights, occupants, cooking and other appliances, and from the sun. Indeterminable amounts of heat are lost through radiation directly to basement or utility-room walls and floors, from the heating unit, the distribution system, and the flue pipe, from stand-by operation of the unit, from opening of doors and windows, and from faulty adjust ment and operation of the combustion unit. Fortunately, data which are available permit the making of reasonable estimates of seasonal efficiency for residences. The average fuel consumption of various types of approved gas-fired equipment has been obtained from a large number of heating systems.1 Corresponding seasonal efficiencies can be calculated from these data. They show a variation from approximately 72 to 88 percent, depending upon the type and size of system. Laboratory tests on a gas conversion burner in a heating boiler operated with on and off cycles gave about 72 percent efficiency.2 Other tests on coal-fired room heaters indicate sea sonal efficiencies of 65 to 75 percent, when the heat from the flue pipe was included.3 A survey of 30 residences in one locality showed a variation of 45 to 75 percent in utilization efficiency, depending upon the condition of the equipment and the fuel used.4 A summary6' 6 of many tests in two research residences at the University of Illinois, using many fuels and syterns, gave values of 67 to 90 percent for overall house efficiency (the ratio of the heat loss from the structure to the heat input to the unit for an average test day). These data were used by the Small Homes Council7 of the University of Illinois in a tabulation of the comparative costs of heating the same build ing with various fuels. The approximate seasonal efficiencies shown in Table 1 are suggested as a guide. Table 1. Approximate Seasonal Efficiency Type ofFuel-Burning Unit Approximate Sea sonal Efficiency, Percent Type of Fuel-Burning Unit Approximate Sea sonal Efficiency, Percent Gas, designed unit........................ Gas, conversion unit.................... Oil, designed unit...... ................... Oil, conversion unit...................... Bituminous coal, hand fired with controls.......................... . Bituminous coal, hand fired without controls......................... Bituminous coal, stoker-fired... 75-80 60-80 65-80 60-80 50-65 40-60 50-70 Anthracite, hand-fired with controls.............................. ,....... Anthracite, hand-fired without controls................................ Anthracite, stoker-fired............. Coke, hand-fired with con- troLs................................................ Coke, hand-fired without con- trols...;........................................ Direct electric heating............... 60-80 50t65 60-80 60-80 50-65 . 100 Estimating Fuel Consumption for Space Heaters 447" CALCULATED HEAT LOSS METHOD In the Calculated Heat-Loss Method a constant average outdoor temper ature is assumed throughout the heating season. This average tempera ture is considerably above the design temperature given in Chapter 12. The method becomes unreliable whenever data on the seasonal average temperature are not available for the particular locality. If the length of time. is shown over which the degree-day data apply in the particular locality, it is possible to calculate the average temperature from the defini tion of the degree-day (see Chapter 1). When this is done, the two meth ods described in this chapter become identical. The average temperature for the period October to April inclusive, is listed in Table 1, Chapter 12, for U. S. and Canadian cities. Computation and Application . In order to apply the Calculated Heat-Loss Method, the hourly heat loss from the building under maximum load, or design condition, is com puted following the principles discussed in Chapters 9, 11, and 12. The fuel requirement is then computed by the equation ----------- ,, Hit - ON ElU-OC . (1) where F = quantity of fuel or energy required (in the units in which C is expressed). H = calculated heat loss including infiltration loss, Btu per hour, during thf design hour, based on and (d. t = average inside temperature maintained during heating period, Fahrenheit. t = average outside temperature through estimate period, Fahrenheit (for cities with an Oct. 1-May 1 heating season--see Table 1, Chapter 12). Id = inside design temperature, Fahrenheit (usually 70 F). t0 = outside design temperature, Fahrenheit (see Table 1 in Chapter 12). N = number of heating hours in estimate period (for an Oct. 1-May 1 heating season, 212 days X 24 hr = 5088). E = efficiency of utilization of the fuel over the period, expressed as a decimal; not the efficiency at peak or rated load condition. C -- heating value of one unit of fuel or energy. Although the assumption of an Oct. 1-May 1 heating season is reason ably accurate in the well-populated New York-Chicago zone, it is not valid as far north as Minneapolis nor farther south than Washington, D. C. and St. Louis. Consequently, it is suggested that allowance be made for this variation, especially in the far north or southern cities. Example 1: A residence building is to be heated to 70 F.from 6 a.m. to 10 p.m. and 65 F from 10 p.m. to 6 a.m. The calculated hourly heat loss is 120,000 Btu per hour based on 70 F inside at --10 F outside. If the building is to be heated by metered steam, how many pounds would be required during an average heating season? Solution: The heating value of steam may be taken as 1000 Btu per lb, and since it is purchased steam, the efficiency can be assumed as 100 percent. Assume average outside temperature as 36.4 F. The average inside temperature is: (16 X 70) + (8 X 65) 68.3 F. 448 CHAPTER 18 1956 Guide 'i Substituting in Equation 1 ; = 120,000 (68.3 - 36.4) 5088 = ^ ,b i ... 1.00[70 -- (--10)]1000 Example 2: What would be the fuel cost to heat the building in Example 1 during an average heating season, using stoker-fired bituminous coal at 14.00 per ton having a calorific value of 13,000 Btu per lb, assuming that the seasonal efficiency of the system is 65 percent? Solution: Substituting in Equation 1 . 120,000 (68.3 - 36.4) 5088 F = 0.65[70 - (-10)]13,000 = 28,800 lb. The fuel cost is then (28,800 s- 2000) (14) = $201.00 Example S: What will be the estimated fuel cost per year of heating a building with gas, assuming that the calculated hourly heat loss is 92,000 Btu based on 0 F, which includes 26,000 Btu for infiltration? The design temperatures are 0 F and 72 F. The normal heating season is 210 days, and the average outside temperature during the heating season is 36.4 F. The seasonal efficiency will be 80 percent. The heating plant will be thermostatically controlled, and a temperature of 65 F will be maintained from 11 p.m. to 7 a.m. Assume that the price of gasis7.5 cents per 100,000 Btu of fuel consumption, and disregard the loss of heat through open windows and doors. Solution: The average hourly temperature is i , (72 X 16) + (65 X 8) The maximum hourly heat loss will be [: H = 92,000 Btu. I; The seasonal heat loss is , 92,000 (69.7 - 36.4) X 24 X 210 , . , ,, , M = ---------------------------------------:-- ~ 2697 hundred thousand Btu. 100,000 X 0.80 X (72 - 0) The estimated seasonal fuel cost will be 2697 X $0,075 = $202.00 It Bhould be noted that savings from night setback may not result as calculated. Room temperature may not decrease and combustion efficiency may be poor during morning pickup. See Reference 8. Several time-saving procedures have been devised for quickly estimating the hourly Btu loss of one and two-story residences in order that fuel estimates can be predicted more quickly from Equation 1. A graphical method of calculating heat losses has been developed9 which makes pos sible a quick solution if the gross wall, ceiling, or floor areas and respective transmission coefficients are known. The Federal Housing Administration has originated a short-cut formula for residential heat loss determinations which makes use of the floor area and three selected transmission coefficients. The formula was developed to apply to detached houses approximately rectangular in shape with total exterior door and window areas equal to about 25 percent of the floor area, and with a floor area not greater than about 1500 sq ft. Equation 2 is for a one-story residence, and Equation 3 is intended for two-story structures. . Hi = A (G + I7,, + U. + 17,) (fd - O . H, = A (G + 1.2 [7. + 0.517. + 0.5 U<) (fd - <.) Estimating Fuel Consumption for Space Heating 449 where Hi = heat loss from one-story residence, Btu per hour. Hi = heat loss from two-story residence, Btu per hour. A = floor area, square feet, measured to the inside faces of enclosing walls and is the sum of the following areas: (1) all the area on each principal floor level; (2) the area of all finished habitable attic rooms, including bath rooms, toilet compartments, closets, and halls; (3) all other areas intended to be heated and not located in the basement. Q = glass and infiltration factor for ordinary construction: (0.45 for no weather stripping or storm windows), (0.40 for weatherstripping), (0.30 for storm windows with or without weatherstripping). [7. = coefficient of transmission for outside wall. Uc -- coefficient of transmission for ceiling. Ut = coefficient of transmission for floor. U = inside design temperature, Fahrenheit degrees. to = outside design temperature, Fahrenheit degrees. Notes for application of Equations 2 and S. _ 1. The calculation of heat loss from heated spaces into adjacent spaces such as attics, basementless areas, and heated or unheated garages shall be based on the assumption that the temperature of such adjacent spaces is the same as the outside design temperature. 2. For all floors over basements or other warmed spaces assume Ut = 0. 3. For structures having concrete slab floors laid on the ground a modified appli cation of the formula may be made. Assume Ut = 0 and calculate the heat loss in accordance with the check formula. Then add the slab loss determined in accordance with the procedure developed by the National Bureau of Standards and described in BMS Report 103. . 4. No basement area is to be included in the formula calculation. If finished habitable rooms in the basement are to be heated, the additional heat loss should be calculated separately and added to the amount obtained by the formula. Both the graphical method9 and FHA formulas, when used within the limitations established, have been found to give reasonably accurate results' for the average residence, but if precise estimates are required, the procedure outlined in Chapter 12 should be used. In the case of gravity warm air heating installations, the load was for merly expressed in square inches of leader pipe which can be converted into Btu per hour by multiplying the square inches of leader area by 111, 167, and 200 for first, second, and third floors, respectively. DEGREE-DAY METHOD This method is based on consumption data which have been taken from buildings in operation, and the results have been computed on a degree-day basis. While this method may not be as theoretically correct as the Cal culated Heat Loss Method, it is considered by many to be of more value for practical use. The amount of heat required in a building depends upon the outdoor temperature, if other variables are eliminated. Theoretically it is pro portional to the difference between the outdoor and indoor temperatures. The American Gas Association10 determined from records in the heating of residences that the gas consumption varied directly as the degree-days, or as the difference between 65 F and the mean outside temperature. In other words, on a day when the mean temperature was 20 deg below 65 F, twice as much gas was consumed as on a day when the temperature was 10 450 CHAPTER 18 1956 Guide deg. below 65 F. For any one day, when the mean temperature is less than 65 F, there are as many degree-days as there are degrees difference in temperature between the mean temperature for the day and 65 F. De gree-days may be calculated on other than the 65 F base for use mainiy for warehouse and other industrial spaces in which temperatures to be maintained are considerably below the 68 to 72 F range. They are listed in a later section of this chapter. Studies made by the National District Heating Association11 of the metered steam consumption of 163 buildings located in 22 different cities and served with steam from a district heating company, substantiate the approximate correctness of the 65 F base chosen by the gas industry. . Table 2 lists the average number of degree-days which have occurred over a long period of years, by months, and the yearly totals for various cities in the United States and Canada. The number of degree-days for United States cities were calculated by taking the difference between 65 F and the daily mean temperature computed as half the total of the daily njaximum and the daily minimum temperatures. The monthly averages were obtained by adding daily degree-days for each month each year and dividing by the number of days in the month; then totaling the respective calendar monthly averages for the number of years indicated and dividing by the number of years. The total or long term yearly average degree-day value is the summation of the 12 monthly averages. Degree days for Canadian cities were supplied by the Canadian Meteorological Division of the Department of Transport, and were computed from the mean tem perature normals on record for the various stations. (See Note c, Table 2.) Any attempt to apply the degree-day method of estimating fuel con sumption for less than one month would be of very little value. It should be noted that this method of calculation is based on a long term average and cannot be expected to coincide with any single year in calculating fuel requirement. Individual yearly degree-day calculations may vary as much as 20 percent above and below the long term average. If the degree-days occurring each day are totaled for a reasonably long period, the fuel consumption during that period as compared with another period will be in direct proportion to the number of degree-days in the two periods. Consequently, for a given installation, the fuel consumption can be calculated in terms of fuel used per degree-day for any sufficiently long period, and compared with similar ratios for other periods to determine the relative operating efficiencies with the outside temperature variable eliminated. Computation and Application . The general equation for calculating the probable fuel consumption by the degree-day method is: F = U X N X D X Ci (4) where F = fuel consumption for the estimate period. U = unit fuel consumption, or quantity of fuel used per (degree-day) (building load unit). N = number of building load units (when available use calculated hourly heat loss instead of actual amount of radiation installed). D = number of degree-days for the estimate period. Ci = temperature-correction factor from Table 3. Values of N depend on the particular building for which the estimate is Estimated Fuel Consumption for Space Heating 451 Table 2. Average Monthly, and Yearly Degree-Days for Cities in the United States and Canada*- b- 0 (Base 65F) A ug. YEARLT T otal Stats Station X EARS No. o* Sea sons . 3 D i g oa CQ O % Q z. < da fo d< a as. < $a a g Calif... Anniston.............. A Birmingham....... A Mobile................... A Mobile................... C Montgomery....... A Montgomery....... C Flagstaff.............. A Phoenix................. A Phoenix................ C Yuma.................... A Bentonville............ 06/07-40/41 Fort Smith.......... A Little Rock......... A Eureka..............C Independence........ 98/90-40/41 Los Angeles........ A 35 43 Colo... Needles.................... 17/18-68/39 98/99-40/41 Red Bluff............ A Sacramento.... .A Sacramento..........C San Diego............ A San Francisco,., .A San Francisco.. .0 San Jose........... ..C Denver..................A Denver..................C Durango .............. 04/05-40/41 22 43 37 Leadville.................. 07/08-40/41 34 D. C... Fla-... Hartford.......... .`.A New Haven........ A Washington......... A Washington......... C A palachioola.......C -- Ga....... Thomasvilie........... 05/06-40/41 36 Idaho. in........ Ind.... Indianapolis........A Royal Center.-..... 18/19-31/32 Iowa.. Charles City....... C Davenport........... C Des Moines..........A 14 Dubuque.............. A Keokuk.................... 98/99-41/42 44 Sioux City............A 0 0 17 118 438 614 614 485 381 128 25 0 2820 0 0 13 123 396 598 623 491 378 128 30 0 2780 . 0 0 0 28 219 376 416 304 222 47 0 0 1612 . 0 0 0 23 198 357 412 m 209 40 0 0 1529 0 . 0 0 69 304 491 517 388 288 80 0 0 2137 0 0 0 55 267 458 483 360 265 66 0 0 1954 46 78 243 586 376 1135 1231 1014 949 687 465 .212 7525 0 0 0 22 223 400 474 309 196 74 0 0 1698 0 (1 0 13 182 360 425 275 175 62 0 0 1492 0 0 -0 0 105 259 318 187 88 14 0 0 951 1 1 38 216 516 810 879 718 519 247 86 7 4030 0 0 9 131 433 698 775 `571 418 127 24 0 3188 0 n 10 110 405 654 719 543 401 122 18 0 2982 267 248 264 335 411 508 552 465 493 432 375 282 4632 0 0 0 86 345 580 629 400 304 145 43 0 2532 0 0 28 216 512 778 799 619 477 267 120 18 3834 81 22 56 87 200 301 378 305 273 185 121 56 2015 0 0 17 41 140 253 328 244 212 129 68 19 1451 0 0 0 19 217 416 447 243 124 26 3 0 1495 350 336 263 282 317 425 467 406 437 413 415 ,363 4474 0 0 0 59 319 564 617 423 336 177 51 0 2546 0 0 22 98 357 595 642 428 348 222 103 7 2822 0 0 17 75 .321 567 614 403 317 196 85 - 5 2600 11 7 24 52 147 255 317 247 223 151 97 43 1574 144 136 101 174 Bit 487 530 398 378 32/ 264 164 3421 189 177 110 138 237 406 462 336 317 279 248 180 3069 7 11 26 97 270 45ft 487 342 308 229 137 46 1410 5 11 120 425 771 1032 1125 924 843 625 286 65 6132 0 5 103 385 711 958 1042 854 797 492 266 60 5673 ns25 37 201 535 861 1204 1271 1002 859 616 394 139 7143 0 0 36 333 792 1132 1271 924 402 145 23 5796 280 332 509 841 1139 1413 1470 1285 1245 990 740 434 10678 0 0 74 383 771 1051 1104 865 776 456 203 27 5709 0 14 101 384 699 1082 1178 1050 871 528 201 31 6139 0 18 93 363 663 1026 1113 1008 866 567 261 52 6Q?6 0 0 37 237 519 837 893 781 619 323 87 0 4333 0 0 32 231 510 831 884 770 606 314 80 0 4258 0 0 0 17 154 304 362 263 184 33 0 0 1307 0 0 0 16 148 309 331 247 169 23 0 0 1243 0 0 0 11 129 276 303 226 154 14 0 0 1113 0 0 0 0 0 22 34 25 8 0 0 0 89 0 0 0 0 (J 18 28 24 7 0 0 0 77 0 0 0 0 i 52 58 48 12 0 0 0 178 0 0 . 0 0 5 48 57 48 15 0 0 0 173 0 0 0 18 177 334 383 275 203 45 0 0 1435 0 0 0 0 6(1 163 201 148 102 0 0 0 674 0 0 Ji 110 392 614 632 512 404 133 20 0 2826 0 0 8 107 38"/ 611 632 515 392 136 24 0 2811 0 0 0 59 282 494 521 412 308 62 0 0 2138 0 0 0 63 280 481 497 391 275 62 0 0 2049 0 0 0 38 225 412 424 330 238 43 0 0 1710 0 0 2 43 208 361 359 299 178 52 5 1 1513 0 0 135 389 762 1054 1169 868 719 453 249 92 5890 0 0 133 406 747 961 1060 815 663 408 222 68 6483 0 0 183 487 873 1184 1333 1022 880 561 317 136 6976 0 0 28 161 492 784 866 683 623 182 47 0 3756 0 0 90 350 765 1147 1243 1053 868 507 229 58 6310 0 11 86 339 769 1128 1240 1028 828 435 192 41 6087 0 6 83 315 723 1066 1166 958 769 401 171 32 6693 0 0 56 259 666 1017 1116 907 713 350 127 14 5225 0 0 59 215 570 871 939 770 589 251 90 6 4360 0 17 107 377 759 1122 1200 1036 874 516 226 53 6287 0 0 79 306 705 1051 1122 938 772 432 176 30 5611 0 0 59 247 642 986 1051 893 725 376 140 16 5134 11 19 116 373 740 1104 1239 976 860 502 245 54 6239 0 5 77 295 681 1023 1107 913 725 371 145 24 5366 17 30 151 444 912 1352 1494 1249 1001 537 256 70 7504 0 7 79 320 756 1147 1262 1044 834 432 175 35 6091 5 12 99 355 798 1203 1330 1092 868 438 201 45 6446 0 6 89 346 777 1178 1308 1072 849 425 183 41 6274 8 28 149 444 882 1290 1414 1187 983 543 267 76 7271 1 3 71 303 680 1077 1191 1025 761 397 136 18 5663 8 17 128 405 885 1290 1423 1170 930 474 228 54 7012 Data (or United Stotea cities from a publication o( the Untied States Weather Bureau, Monthly Nor- uuxl Temperatures, Precipitation and Degree Days, 1954 are for the period 1921 to 1950 inclusive. Those United States cities for which years are given in Column 3 are not listed in the above publication and the data are those which were computed by the United States Weather Bureau in 1946 and 1947 in accordance with the requirements of the National Joint Committee on Weather Statistics. Data for airport stations. A, and city stations, C, are both given where available. c Data for Canadian cities were computed by the Meteorological Division, Department of Traneport from normal monthly mean temperatures, adjusted for the summer months by a method described by H. C. S. Thom, The Rational Relationship between Heating Degree Days and Temperature, Monthly Weather Beeiew, Vol. 82, No.-1, January, 1954. . 452 CHAPTER 18 1956 Guide Table 2. Avebage Monthly and Yearly Degree-Days fob Cities in the United States and Canada*- b- * (Continued) State Station Yeaeb No. 4 iOF Sea sons X o P < 09 f? O > o E dta Q *>< B 9ft Mar. fKt. 5 S Bfc ss D s5H TTn Ky.... La..... Me....... Dodge City......... A Iola............................ 05/06-40/41 Topeka.................. A Topeka............... .C Wichita..................A Louisville............. A Louisville............. C Lexington......... ..A New Orleans___ A New Orleans___ C Shreveport.......... A Rastport................C Greenville............... D7/08-40/41 42/43-45/46 36 38 Md.... Baltimore.............A Boston.................. A Fitchburg................ 58/99-40/41 43 Mich.. Alpena.................. C Detroit Willow Escanaba............ C Mmn.. Grand Rapids... C Houghton................ 50/01-40/41 42/43-45/46 Lansing................. A Ludington............... 12/13-40/41 Marquette............ C Sault Ste. Marie.A 45 29 Minneapolis........ A Moorhead.......... 98/99-40/41 43 Miss... Mo....... Corinth......... ........... 09/10-40/41 Meridian............... A Vicksburg............. C Columbia............. A Hannibal................. 58/99-40/41 Kansas City........A 32 43 Kalispell............... A Neb... Drexel....................... 15/16-25/26 11 Omaha............... A N.H... NJ.... N.M::. N.Y... 98/99-31/32 34 15/16-40/41 26 98/99-45/46 43 06/07-45/46 40 Ithaca....................... 99/00-42/43 44 La Guardia___A 0 0 55 277 687 1029 1144 899 725 341 146 20 5323 0 0 4(J 262 669 980 107f 840 694 347 135 15 5058 (! 1 44J 236 579 930 102{ 817 599 282 9* * 4616 U i 59 271 672 1017 1125 885 694 326 137 15 5209 0 0 42 242 630 977 1084 851 669 295 112 13 4919 0 0 32 219 597 915 1023 77* 619 280 101 7 4571 0 0 51 232 579 871 933 778 611 285 94 5 4439 0 0 41 206 549 849 911 762 605 270 86 0 4279 0 0 56 259 636 933 1001 854 710 36* 140 15 4979 0 0 0 7 169 30* 364 248 190 31 0 ` C 1317 0 0 0 5 141 283 341 223 163 19 0 0 1175 0 0 0 53 305 490 55/j 386 m 61 i 0 2117 141 136 261 521 798 1206 1333 1201 1063 774 524 288 8246 69 113 315 643 1012 1464 1625 1443 1251 842 46* 194 9439 15 58 199 515 825 1237 1373 1218 1031 693 394 117 7681 0 0 50 278 582 908 955 840 6/e 37* 115 5 4787 0 0 29 207 489 812 880 776 611 326 73 0 4203 0 7 77 315 618 998 1133 1002 849 534 236 42 i_5791 12 29 144 432 774 1139 1240 1137 94(1 672 254 70 6743 .22 34 III 372 615 924 1020 949 880 642 394 139 6102 50 85 215 530 864 1218 1358 1263 1156 762 437 135 8073 0 10 96 393 759 1125 1231 1089 915 552 244 - 55 6469 0 8 96 381 747 1101 1203 1072 923 55* 251 61 6404 62 95 24V 555 933 1321 1473 1327 1203 804 471 160 8657 14 29 144 462 822 1169 1287 1154 loot 606 301 79 7075 0 20 105 394 756 1107 1215 1086 939 546 24* 5* 6474 70 94 268 582 965 1355 1535 1421 1251 820 474 195 9030 13 33 140 455 813 1175 1277 1142 986 591 287 70 6982 41 55 182 472 794 1135 1271 1183 1056 69* 41* 15* 7458 69 87 23b 543 933 1299 1435 1291 1181 789 477 181 8529 109 126 298 639 1005 1398 1587 1442 1302 840 499 224 9475 56 91 298 651 1140 1606 1758 1512 1327 846 474 17* 9937 66 91 277 614 1092 1550 1696 1448 1252 801 487 20(1 9674 8 17 157 459 960 1414 1562 1310 1053 570 259 80 7853 20 47 240 607 1105 1609 1815 1555 1225 679 327 9* 9327 12 21 154 459 951 1401 1653 1305 1051 564 250 77 7804 0 1 13 142 418 669 696 570 396 149 32 1 3087 0 0 0 90 338 528 661 413 309 85 9 0 2333 0 0 0 51 268 456 607 374 273 71 0 0 2000 0 6 62 262 654 989 1091 876 m 326 135 14 5113 1 3 66 288 652 1037 1139 980 710 374 12* 15 5393 0 0 44 240 621 970 1085 851 666 292 111 8 4888 0 0 45 233 600 927 1017 820 64* 297 101 11 4699 0 0 38 202 570 893 983 792 620 270 94 7 4469 0 8 61 249 615 908 1001 790 632 295 128 16 4693 8 20 194 497 876 1172 1305 1089 958 564 304 119 7106 20 38 270 564 1023 1383 1513 1291 1076 597 313 .125 8213 36 66 320 617 999 1311 1469 1165 1017 654 399 197 8250 51 78 359 598 969 1215 1438 1114 992 660 427 225 8126 47 83 326 639 990 1249 1386 1120 970 639 391 215 8055 6 11 18/ 525 966 1373 1516 1257 1048 570 285 106 7850 22 57 292 623 993 1283 1414 1100 939 609 365 176 7873 4 6 95 405 788 1271 1363 1096 843 493 219 38 6611 0 12 82 340 774 1144 1271 1030 822 401 190 38 6HM 0 7 79 310 741 1113 1240 1000 794 377 172 32 6865 7 11 120 425 846 1172 1271 1016 887 489 243 59 6546 0 5 88 331 783 1166 1302 1058 831 389 175 32 6160 11 10 145 461 891 1212 1361 1100 970 543 28* 83 7075 27 61 165 443 744 986 1048 804 756 519 318 165 6036 0 5 96 422 723 995 1082 860 763 504 272 91 5813 0 17 180 508 822 1085 1153 854 794 546 299 111 6369 11 57 192 527 849 1271 1392 1226 1029 660 316 82 7612 0 0 29 230 507 831 905 829 729 468 189 24 4741 1 2 38 221 527 852 936 876 737 459 188 33 0 0 47 301 603 961 1039 932 760 450 148 11 I 2 40 268 579 921 JU16 973 833 m 206 31 5369 0 0 55 285 582 930 1004 904 735 429 133 11 5068 0 0 0 10 218 630 899 970 714 589 289 70 0 8 156 601 750 787 666 443 185 28 0 0 3424 12 15 129 451 772 1071 1094 892 786 544 297 60 0 0 24 139 443 780 1197 1318 1179 989 597 246 6 98 388 708 1113 1234 1103 905 531 202 50 31 6319 16 63 192 518 834 1228 1342 1215 1051 672 318 88 0 36 141 428 735 1113 1218 1100 927 570 240 48 6556 16 30 122 433 753 1116 1225 1128 992 636 315 72 6838 27 61 219 550 898 1368 1616 1385 1139 696 340 107 8305 17 40 156 451 770 1129 1236 1156 978 606 292 83 6914 . 0 0 28 250 546 908 992 907 760 447 141 10 Estimating Fuel Consumption for Space Heating 453 Table 2. Average Monthly and Yearly Degree-Days for Cities in the United States and Canada*- *> (Continued) State Station No. xa. *<3 Years OF Sea sons X' o bp < t6a-. e o >o da Q *< aa 9ft BS < S oas. < x< 2 a 2 "PS < e hH N.Y... New York........ C New York Cen- tral Park Obs... Oswego............. C Rochester..........A Syracuse........... A N.C... Asheville.......... C Charlotte.......... A Hatteras........... C Manteo................ >4/05-28/29 Raleigh............. A Raleigh................. C Wilmington....... A N.D... Bismarck....__ A Devils Lake...... C Grand Forks....... 12/13-40/41 42/43-45/46 Williston........... C Ohio... Cincinnati.........A Cincinnati........ C Cincinnati Abbe Obs.................. Cleveland.A Cleveland......... C Columbus........ A Columbus......... C Dayton............. A Sandusky..........C Toledo.............. A Okla.,. Broken Arrow...... 18/19-30/31 Oklahoma City .A Oklahoma City .C Ore.... Baker................C Medford............A Portland.............. A Portland............... C Pa...... Roseburg..............C Erie................ .... .C Harrisburg........ A Philadelphia..... A Philadelphia..... C Pittsburg Alle- gheny............ A Pittsburgh Greater Pitts* burgh............. A Pittsburgh.......... C Reading................ C Scranton...........C R. I. Block Island... .A 25 33 13 Pier.................. 98/99-17/18 S. C. Providence........A Providence........C Charleston........A Charleston........ C Columbia......... A Columbia......... C Due West............ 21/22-31/32 Greenville......... A Huron...............A Pierre................. 98/99-40/41 42/43-45/46 Tenn.. Rapid City....... A Chattanooga..... A Knoxville......... A Memphis.. *......A Memphis...........C Texas.. Nashville.......... A Abilene............. A Amarillo........... A Austin.............. A Brownsville...... A Corpus Christi. .A .................... A Del Rio............ A El Paso.............A Fort Worth....... A Fort Worth Amon Carter Fid....... Galveston......... A Galveston......... C Houston....... .../ Houston................G 20 11 47 0 0 . 39 263 561 908 995 904 753 456 153 18 5050 0 0 31 250 552 902 1001 910 747 435 130 7 4965 20 39 139 430 738 1132 1249 1134 995 654 355 90 6975 9 34 133 440 75911141 1249 1148 992 615 289 64 6863 0 29 117 396 714 1113 1225 1117 955 670 247 37 6520 0 0 5ft 262 552 769 794 678 672 285 105 5 4072 0 *0 7 147 438 682 704 577 449 172 29 0 3205 0 0 ft 63 244 481 527 487 394 171 25 0 2392 0 0 7 113 358 595 642 594 469 249 76 7 3109 0 0 16 149 438 701 732 613 477 202 41 0 3369 0 0 10 118 387 651 691 577 440 172 29 0 3075 0 0 0 73 288 508 533 463 347 104 7 0 2323 29 37 227 598 1098 1535 1730 1464 1187 657 355 116 9033 47 61 276 654 1197 1668 1866 1576 1314 750 394 137 9940 32 60 274 663 1160 1681 1895 1608 1298 718 359 123 9871 29 42 261 605 1101 1528 1705 1442 1194 663 360 138 9068 0 6 77 295 648 973 1029 871 732 392 149 23 5195 0 0 42 222 567 880 942 812 646 314 10* 0 4532 0 0 56 263 612 930 989 846 682 347 132 13 4870 0 10 75 340 699 1057 1132 1019 874 531 223 46 6006 0 9 60 311 636 995 1101 977 846 510 22* 49 5717 0 8 69 337 693 1032 1094 946 781 444 180 31 5615 0 0 59 299 654 983 1051 907 741 40* 15* 22 5277 0 5 74 324 693 1032 1094 941 781 435 179 39 5597 0 0 66 327 684 1039 1122 997 853 51* 217 41 5859 0 12 102 387 ,756 1119 1197 1056 905 555 245 6(1 6394 0 0 28 169 513 805 881 646 506 212 61 5 3826 0 0 14 154 480 769 865 650 490 1K 41 C 3644 0 0 12 149 459 747 843 630 472 169 3* 4] 3519 25 47 255 518 852 113* 126* 972 837 591 384 200 7087 0 0 77 326 624 822 862 627 552 381 201 69 4547 25 22 116 319 585 750 856 65* 57(1 394 242 9* 4632 13 14 85 280 534 701 791 594 615 34. 199 70 4143 14 10 98 288 531 694 744 563 50* 36{ 22* 82 4122 0 17 76 352 672 1020 112* 1039 911 57? 27? 55 6116 0 0 69 308 630 964 1051 921 750 42? 12? 14 5258 0 0 47 269 573 902 9# 87S 704 402 10' 0 4866 0 0 33 219 516 S5fi 933 837 667 361 9? 0 4523 0 6 78 336 678 1004 1073 955 784 441 161 27 5555 0 20 94 377 720 1051 1116 986 81* 486 195 34 5905 0 0 56 29* 612 924 99? 871 736 402 131 1? 5048 0 5 57 285 58* 936 1011 902 725 411 12? 11 5060 0 18 115 389 693 1057 1141 102* 859 516 196 35 6047 6 21 88 330 591 927 1026 955 865 603 335 96 5843 1 26 121 366 691 1012 1113 1074 916 622 342 113 6397 0 28 107 381 672 1035 1125 iim 874 574 251 6? 6125 0 7 6* 330 624 986 107( 972 801 507 197 31 5607 0 0 (J 52 270 45t 472 371 281 6? ( C 1973 0 0 U 34 214 4H 445 36* 2b(J 4? ( C 1769 0 0 (J 82 33* 55* . 664 46* 340 8? ( 2436 0 0 76 30* 524 53* 44* 31* 71 ( ( 2284 0 0 9 142 39* 594 651 491 411 15* 31 5 2890 0 0 u 131 411 64* 67S 552 442 161 32 3060 10 Id 141 472 975 1401 1591 132* 1032 55* 271 84 7902 4 ' 11 136 43* 887 1311 146C 125* 971 516 23* 52 7283 32 24 19* 501 891 121* 1361 1151 1045 615 361 14* 7535 0 0 24 161 471 711 725 58* 461 171 45 4 3384 4J c 3* 171 49* 744 764 63C 504 194 5( ( 3590 0 0 17 l2t 432 67S 725 574 421 131 2' 3137 .0 c IS 9* 392 631 71< 67' 42* 13 2( ( 3006 c 22 154 471 725 77* 631 49* 181 4? ( 3513 0 C 5 9* 35( 595 67: 471 34' 11? ( ( 2657 c C 37 241 594 851 921 711 584 29* 91 ( 4345 c 0 t 3 214 402 48' 322 211 54 ( ( 1713 c l 51 . 151 211 10( 74 ( ( ( 617 c ( ( IIS 252 33( 192 11* 1 4 4 1011 f t ( 5? 291 51* 60' 432 28* 71 1 4 2272 c ( 24 18* 371 411 235 141 2: ( ( 1407 c C ( 7 39( 62b 67( 44! 331 11( 4 ( 2641 c ( 51 291 53* 622 44( 30* 9( 1 4 2361 c ( ( 5- 291 52' 611 432 32( 8 4 ( 2338 { ( ( ( 132 281 362 241 17t 21 1 ( 1233 ( ( ( ( 13 27 351 241 17( 31 4 ( 1211 ( ( ( : 18 32 39 265 18' 31 ( 1388 0 0 0 0 162 303 37* 240 166 27 0 0 1276 454 CHAPTER 18 1956 Guide Table 2. Average Monthly and Yearly Degree-Days for Cities in the United States and Canada*' b' (Concluded) State or ProvXNCE Station HNo. Yeaas > Sea- g eER o dH Z aa PS CPSh a $i SONS -} < m o 'Z P *-9 S< a Texas.. Utah.. 01/02-40/41 40 00/01-45/46 46 Vt..... Va........ 98/99-42/43 45 Norfolk .... .. .C 02/03-40/41 39 0 0 0 45 260 440 531 368 265 71 0 0 1980 0 0 0 20 218 349 406 274 211 39 0 0 1517 0 0 0 8 170 315 381 258 181 27 0 0 1340 0 0 0 25 201 374 462 293 190 34 0 0 1579 0 0 2 56 234 462 494 375 214 64 8 0 1909 6 11 156 499 832 1142 1190 944 816 567 338 97 6598 0 0 R8 381 .771 1039 1194 885 741 453 233 81 5866 0 0 61 330 714 995 1119 857 701 414 208 64 5463 19 47 172 521 858 1308 1460 1313 1107 681 307 72 7865 62 112 283 602 947 1389 1524 1384 1176 754 405 166 8804 0 0 0 120 366 648 698 636 512 267 60 0 3307 (J 0 49 236 531 809 846 722 584 289 82 5 4153 . 0 0 9 152 408 688 729 644 500 265 59 0 3454 0 0 5 118 354 636 679 602 464 220 41 0 3119 0 0 33 210 498 791 828 708 550 271 66 0 3955 0 0 31 181 456 750 787 676 529 254 67 0 3720 7 13 82 352 662 916 945 836 677 410 168 35 5103 Wash.. North Head L.H. 239 205 234 341 486 636 704 585 *598 492 406 285 5211 49 45 134 329 540 679 753 602 558 396 246 107 4438 75 70 192 412 633 781 862 675 636 477 307 155 5275 Spokane___ A 17 28 205 508 879 1113 1243 988 834 561 330 146 6852 66 62 177 375 579 719 797 636 595 435 282 143 4666 295 288 315 406 528 648 713 610 629 5Z5 437 m 6724 Walla Walla.........C 0 0 93 308 675 890 1023 748 564 ddfl 171 38 4848 0 7 150 446 807 1060 1181 862 660 408 205 53 5845 W. Va.. Elkins . .A Parkersburg........ C Wis... . 9 31 122 412 726 995 1017 910 797 477 224 53 5773 0 0 56 272 600 896 949 826 672 347 lit 13 4750 32 11 13 58 20 183 152 515 447 945 1392 1516 1336 1132 921 138(J 152 1280 1035 696 652 347 25i 107 74 8259 7650 31 150 459 891 1302 1423 1207 1008 579 272 82 7417 10 30 137 419 864 1287 1417 1207 1011 573 26 79 7300 20 32 134 428 831 1218 1336 1142 983 621 351 109 7205 15/16-40/41 26 11 26 24 58 112 216 397 568 795 1184 1302 1117 961 982 1427 1594 1381 1147 506 335 315 100 100 6944 8494 Wyo... Cheyenne............ A 33 7 39 23 241 244 577 897 1125 1225 632 1050 1383 1494 1179 1045 717 687 462 39fl 173 163 7562 8303 Yellowstone Park. 04/05-40/41 37 125 173 424 759 1079 1386 1464 1252 1165 841 603 334 9605 ________ _____ ____ ----- - ____ --" -- -- -- -- ----- -- Alta... Man... N.B... Nfld... 1921-50 1921-50 1921-50 1921-50 1921-50 1921-50 1921-45 1921-50 1921-50 1926-50 1921-50 1921-50 1939-50 1921-50 1933-50 1937-50 1941-51 NWT.. N.S.... Ont-- P.E.I Quo___ Sasks . Y.T.... Dawson.................... 1926-50 1921-50 1921-50 1921-50 1921-50 1921-50 1921-50 1921-50 1921-50 1921-50 1921-60 1931-50 1921-60 1921-50 1921-50 1921-50 1921-50 1921-50 1921-50 1921-50 30 30 30 30 30 30 25 30 30 25 30 30 12 30 18 14 10 19 25 25 30 30 30 30 21 30 30 30 30 30 30 20 30 30 30 30 30 30 30 30 110 170 410 710 mo 1430 1530 1350 1200 770 460 90 180 440 750 1220 1660 1780 1520 1290 760 41C 60 100 350 620 1030 1330 1450 1290 1120 40C 20 50 300 600 1070 1440 1590 1380 1130 620 32( 180 220 440 730 1100 1450 1560 1290 1070 47C 270 60 240 60 340 200 610 410 680 620 860 790 910 850 810 710 790 650 (jisO 5m0( 160 150 230 41U 600 730 80C 660 620 470 35( 60 100 350 730 1290 1810 2010 1730 1440 42( 310 370 650 1110 1760 2300 2520 2270 2150 1590 not 40 70 300 690 1260 1770 2000 1710 1440 810 4(K 50 70 250 600 940 1410 1570 1410 1180 780 42C 40 110 80 110 240 250 680 530 890 1340 1510 1340 1160 830 1250 1400 1270 1100 780 46( 50( 90 130 140 160 320 320 640 660 890 1230 1410 1360 1240 920 1230 1430 1320 1270 900 970 64( 65( 130 170 280 220 160 460 440 840 1220 1740 2020 1710 1530 1110 77( 320 580 820 1100 1270 1230 1160 910 68( 800 1400 2040 2500 2580 2280 1690 105( 170 350 700 1220 1940 2460 2550 2190 2040 1390 73( 50 70 180 470 740 1120 1260 1180 1050 760 48t 60 80 220 510 780 1130 1310 1280 1160 850 5?< 110 120 230 480 720 1040 1180 1100 1010 756 51( 90 120 350 690 1140 1690 1780 1550 1360 56( 10 10 120 430 760 1130 1270 1160 1000 32< 110 30 70 30 170 40 40 60 410 160 150 210 780 1270 1780 2060 1770 1570 1030 500 820 1250 1420 1290 1110 710 490 840 1200 1320 1040 650 690 960 1480 1640 1480 1230 730 60( 38( 33( 34( 20 30 140 460 770 1130 1260 1160 1020 640 32( 40 60 200 610 820 1230 1430 1340 1180 840 51< 6(1 10 20 20 70 70 60 5C 110 40 70 7C 140 110 no or 330 180 250 240 410 370 380 34C 690 1100 1670 1880 1410 48( 53U 890 1370 1540 1370 1160 700 30( 610 990 1476 1640 1460 1250 810 40< 590 m 1401 1560 1410 1190 760 37( 78(1 1350 1870 2060 1750 1500 850 44( 750 1290 174C 1940 1680 1420 42C 760 1320 1791 199C 1710 1440 800 42C m 1170 1560 1710 1490 1260 730 40( 170 320 660 1170 1890 2410 2510 2160 1830 570 270 9520 220 10320 21(1 8650 181 8550 260 9500 350 6910 130 5230 230 5410 170 10930 690 16810 150 10630 150 8830 210 8700 250 8380 350 9210 381 9440 m41( 12140 8780 480 17870 281 16020 2lC 7570 m 8220 270 7520 241 10350 60 6890 24( 11790 104 7810 90 7380 M 8830 70 7020 22( 8380 I/O M UK 9070 90 8610 210 11430 190 10770 1m80 10960 9660 250 15040 Estimating Fuel Consumption for Space Heating 455 being prepared and must be found by surveying plans, by observation, or by measurement of the building. Values of U for use in this equation are the unit fuel consumptions per degree-day, obtained as a result of the collection of operating information and listed in Tables 4, 5 and 6. Atten tion is directed t<? the nature of these units in the next following sections. Unit Fuel Consumptions per Degree-Day The quantity of fuel used per degree-day in a given heating plant can be reduced to a unit basis in terms of quantity of fuel or steam per degree-day per thousand Btu hourly heat loss at design conditions. A less frequently used basis is quantity of fuel per (degree-day) (square foot of floor area). In fact any convenient unit can be used to relate the consumption to the degree-day and to the building. The choice of these units requires explanation, and some discrimination and judgment. If the volume basis is used, the net heated.space is prefer able to the gross building cubage, since gross cubage includes outer walls and certain portions of attic and basement space which are usually un , heated. In the absence of data on net heated volume, a figure of 80 per- Table 3. Correction Factors fob Outside Design Temperatures* Outside Design Temp F............................................ -20 -ib 0 +10 20 Correction Factor............................ 0,778 0.875 1.000 1.167 1.400 . * The multipliers in Table 3, which are high for mild climates and low for cold regions, are not in error as might appear. The unit figures in Tables 4, 5, and 6 are per square foot of radiator or thousand Btu heat loss per degree-day. For equivalent buildings and heating seasons, those in warm climates have lower de sign neat losses and smaller radiator quantities than those in cold cities. Consequently, the vntf figure in quantity of fuel per (square foot of radiator) (degree-day), is larger for warm localities than for colder regions. Since the northern cities have more radiator surface per given building and a higher seasonal degree-day total than cities in the south, the total fuel per season will be larger for the northern city. cent of the gross volume may be used to obtain the estimated net heated volume. The volume basis has been rather widely used primarily because it is simple to apply. In industrial buildings it is usually easier to ob tain the correct volume of a given building than to measure and evaluate the heating capacity of its heating system, or calculate its maximum hourly Btu loss. The comparison of buildings on a straight volume basis does not allow for variation in exposure, type of construction, ratio of exposed area to cubical contents, and type of occupancy. It is inaccurate for esti mating purposes unless the buildings are of very similar nature. The calculated heat loss or the heating capacity of the installed radiation may be used as the unit. The use of the heating capacity of the installed radiation is of questionable value when referring to heat transfer surfaces used in warm air furnace or central air conditioning systems. Where steam or hot water radiation is already installed, care should be exercised in using the installed radiation as the basis for estimating, since actual installed radiation may differ considerably from the exact radiation requirements. In view of all these considerations, it is believed that the unit based on thousands of Btu of hourly calculated heat loss for the design hour is probably the most desirable. ` Estimating Gas Consumption Values of the Unit Fuel Consumption Constant (U) for gas are given in Table 4 for various gas heating values, and different types and sizes of 456 CHAPTER 18 1956 Guide Table 4. Unit Fuel Consumption Constants (V) fob Gas* Based on 0 F Outside Temperature, 70 F Inside Temperature Hot Water Steam Warm Air Heatino Value or Gas Btu per Cu Ft Cu Ft Gas per Degree-Day per Sq Ft EBR Up to 600 Sq Ft 500 to 1200 Sq Ft Over 1200 Sq Ft 500 535 800 1000 0.149 0.139 0.094 0.075 0.142 0.132 0.087 0.071 0.134 0.126 0.085 0.068 Cu Ft Gas per Degree-Day per Sq Ft EDR Cu Ft Gas per DegreeDay per 1000 Btu Hourly Design Heat Loss Up to 300 Sq Ft 300 to 700 Sq Ft Over 700 Sq Ft Gravity Fan Systems 0.254 0.237 0.159 0.127 0.242 0.226 0.151 0.121 0.231 0.216 0.144 0.116 0.896 0.840 0.560 0.449 0.861 0.805 0.538 0.431 1 Therm Gas Consumption in Therms per Degree-Day 100,000 Btu 0.000743 0.000709 0.000675 0.00127 0.00121 0.00116 0.00450 0.00430 Abstracted from Comfort Heating, American Gas Association, 1938 and 5 percent added for operation without night reduction of temperature. heating plants. They are based on an inside design temperature of 70 F and an outside design temperature of 0 F, and apply only to these condi tions. For other outside design conditions corrections must be made by applying factors given in Table 3. ' The factors in Table 4, as corrected if necessary, are satisfactory for regions having 3500 to 6500 degree-days per heating season. In regions with less than 3500 degree-days the unit gas consumption is higher than given; where over 6500, the unit is less than given. Ten percent addition or deduction in these cases is recommended by A.G.A. publications. This table cannot be used for making estimates for industrial buildings where low inside temperatures are maintained. For gas heat values other than those given in Table 4, simply interpolate or extrapolate. It will also be noted that Table 4 applies only to small installations. In general, the larger the installation, the smaller the unit gas consumption becomes, and the values in the table should be used with care, if at all, in large gas-burning installations. Example 4: Estimate the gas required to heat a building located in Chicago, II]., where the heating season has 6310 degree-days and the gas heating value is SOO Btu per cu ft. The calculated heating requirements are 1000 sq ft of hot water radiation based on design temperature of --10 F and 70 F. Table 5. Unit Fuel Consumption* Constants (U) fob OiLb Based on 0 F Outside Temperature, 70 F Inside Temperature ' Unit* Gal Oil per Sq Ft Steam Radiator............................. Gal Oil per Sq Ft Hot Water Radiator..................... Gal Oil per 1000 Btu per Hour Heat Loss................ Efficiency in Percent . 70 0.00105 80 0.00092 0.00066 0.00058 0.00437 0.00383 Based on a heating value of 141,000 Btu per gallon. . , n tt b Abstracted by permission from Degree-Day Handbook (Second Edition, 1937), by C. Strock and V* t" B. Hotchkiss. Seven percent added for operation without night reduction of temperature and change heating value of 141,000 Btu per gallon. - c Per degree day. Estimating Fuel Consumption for Space Heating 457 Solution: From Table 4, the fuel consumption for a design temperature of 0 F with 800 Btu gas is found to be 0.087 cu ft of gas per (degree-day) (square foot of hot water radiation). From Table 3, the correction factor is 0,875 for --10 F outside design temperature, hence, 0.875 X 0.087 = 0.076. By Equation 4, F = 0.076 X 1000 X 6310 = 480,000 cu ft. Estimating Oil Consumption Table 5 gives unit fuel consumption factors for oil, similar to those given for gas in Table 4. The factors in Table 5 apply only to an inside design temperature of 70 F and an. outside design temperature of 0 F. For other outside design temperatures, the constants in Table 5 must be multiplied by the values -in Table 3 as explained under Estimating Gas Consumption. Values given in Table 5 assume the use of oil with a heating value of 141,000 Btu per gallon. For other heating values, multiply the values in Table 5 by the ratio of 141,000 divided by the heating value per gallon of fuel being used. Example 5: Estimate the seasonal oil consumption of a boiler, designed for oil firing, in a building located in Toledo, Ohio. The building has a calculated heat loss of 240/XX) Btu per hr. The oil heat value is 144,000 Btu per gal, and the assumed seasonal efficiency-is 80. The outside design temperature for Toledo is --10 F, and the inside design temperature is 70 F. Solution: From Table 5, under 80 percent efficiency and in the bottom line, the value of U is found to be 0.00383 gai per 1000 Btu hourly heat loss for 0 F out side temperature. The correction factor for --10 F outside design temperature from Table 3 is 0.875. Solving 0.875 X 0.00383 = 0.00335. Making a further cor rection for the heating value, 141000 0.00335 X 144' = 0.00328 gal per 1000 Btu per hr calculated heat loss per degree- day. From Table 2, the total normal degree-days for Toledo are 6394. Since V is expressed in 1000 Btu, N is equal to 240. Substituting in Equation 4 F = 0.00328 X 6394 X 240 = 5030 gal. Estimating Coal or Coke Consumption Coal or coke consumption estimates are made by following exactly the same procedure as for oil. Values of U are given in Table 6 which only apply to an inside design temperature of 70 F and an outside design tem perature of 0 F. A correction must be made for other conditions by use of the multiplying factors in Table 3. Data in Table 6 are based on 12,000 Table 6. Unit Fuel Consumption* Constants (U) fob Coal'' Unit 40 Lb Coal per Sq Ft Steam Radiator___ 0.0216 Lb Coal per Sq Ft Hot Water Radiator.. 0.0135 Lb Coal per 1000 Btu per Hour Heat Loss . 0.0889 Evttcienct nr Percent 60 60 70 0.0172 0.0143 0.0123 0.0108 0.0091 0.0078 0.0717 0.0592 0.0507 80 0.0108 0.0068 0.0444 bit"1 w a Ltcauiug vcuue ui i,uuu aalu puuuu. B tt Abstracted by permission from Degree-Day Handbook (Second Edition, 1937), by C. Strock and C. H. Hotchkiss. Eight percent added for operation without night reduction of temperature. Fer degree-day. 458 CHAPTER 18 1956 Guide Btu per lb coal, and for other heating values of coal they must be multiplied by.the ratio of 12,000 divided by the heating value of fuel used. Example 6: A building in Scranton, Pa. has a calculated heat loss of 240,000 Btu per hr based on an inside design temperature of 70 F and an outside design tempera ture of --10F. What will be the estimated normal seasonal anthracite or coke consumption for heating if 13,000 Btu per lb fuel is burned in a hand-fired boiler, with automatic control, at a seasonal efficiency of 80 percent, and what part of the total will be used during November, December, and January? - Solution: From Table 6, V is 0.0444 of coal or coke per 1000 Btu per hr heat loss per degree-day. Correcting for the outside design temperature of --10 F from Table 3, the value of U is 0.875 X 0.0444 = 0.0389. From Table 2, D is 6218 and from the problem, N is 240. Substituting in Equation 4, F = 04)389 X 240 X 6047 = 56,500 lb. Fuel used over any period is, according to the theory of the degree-day, propor tional to the number of degree-days during the period. From Table 2, the average numbers of degree-days for November, December, and January in Scranton are 693, 1057 and 1141 respectively, a total of 2953. The yearly total is 27,000, so that during these three months the estimated consumption is ocqi ~ X 56,500 = 27,000 lb. Estimating Steam Consumption In estimating steam consumption the efficiency is generally assumed at 100 percent. If for low-pressure steam an average heating value of 1000 Btu per pound of steam is used, no correction is necessary. In comparing values from different cities, correction should be made for design tempera ture (see Table 3) when the unit figures are in terms of heat loss but not when the values are in terms of building volume or floor space. Where the heat loss is calculated in Btu per (hour) (degree difference in temperature) the simple Equation 5 may be used: H X 24 X D 1000 (5)' where F = pounds of steam required for estimate period. H = calculated heat loss, Btu per (hour) (degree difference). 24 = hours in one day. D = number of degree-days for the period of estimation. 1000 = Btu delivered per pound of steam condensed. * In this method the number of degree-days automatically takes care of average inside and outside temperature difference. When degree-days are taken from Table 2, an average inside temperature of approximately 70 F is assumed throughout the period. If an average inside temperature other than approximately 70 F is to be used, the number of degree-days should be obtained for the new base. Example 7: An eight-story building in Pittsburgh is operated with a daytime temperature of 70 F. The calculated heat loss is 10,500 Btu per (hr) (degree temper ature difference). What is the estimated average yearly steam consumption for building heating? Solution: Since the average inside temperature is approximately 70 F, the degree- Estimating Fuel Consumption for Space Heating 459 days from Table 2, based on 70 F may be used. Therefore, from Table 2, Pittsburgh has 5048 degree-days per normal season. Inserting in Equation 5: = 1^,500 X 24 X 5048 = 1272,000 lb of steam. 1000 .. Consideration has been given to the difference in steam utilization of different types of buildings, and Table 7 shows actual average units for these various types. These figures were obtained from operating results in 896 buildings located in all sections of the United States. Being aver ages, and for small, groups in each type, the figures may need considerable modification to allow for local variations. It should be especially noted that the steam used for heating water for service is not included in the values given in Table 7. , : : Tabi.f, 7. Steam Consumption op Buildings with Vabious Types op Occupancy* Type op Building No. Bldgs Average Volume Heated Space 1000 Cu Ft Steam for Heating Lb per DD per 1000 ' Cu Ft Average Hours op Occupancy Office....................................................... Office, and Bank.................................. Office and Printing............................ Office and Theater................. ........... Office and Stores or Shops............. Bank..................................................... Department Store.............................. Stores.............................................. .. Loft................ ........................................ Warehouse............................................. Hotel and Club.................................. Apartment or Residence................. Theater................... *....................... Garage.................................................... Manufacturing..................................... Church.................................................... Hospital................................................. School................................................... Municipal or Federal................ J -.. Lodge, Gym, Hall or Auditorium Miscellaneous....................................... ' 334 49 8 :7 26 2160 3000 1895 4950 1615 16 806 63 3400 73 310 63 865 24 2230 73 1795 . 22 ` 13 19 1240 1540 1350 9 656 4 3306 8. 1115 15 3215 12 : . 880 7 : 1387 0.685 0.577 1.230 0.412 0.617 0.786 0.385 0.624 0.588 0.459 0.990 0.482 0.202 0:808 0.532 1.194 0.592 0.587 0.390 0.479 12.1 13.1 17.7 12.9 13.2 11.7 11.1 10.4 10.0 . 9.4 22.3 12.9 21.4 . 9-5 7.9 22.0 11.5 15.6 12.4 21.4 * Principles of Economical Heating, National Association of Building Ovtners and Managers Example 8: A store in Philadelphia with a heating system designed to maintain 70 F inside in 0 F weather has 2^3,000 cu ft of heated space. What would be the estimated average yearly steam consumption of purchased steam for heating? Solution: According to Table 7, a store would use 0.624 lb of steam per degree-day per 1000 cu ft heated space. From Table 2, Philadelphia has 4523 degree-days per normal year. Inserting in Equation 4: ' F = 0.624 X 250 X 4523 *= 706,000 ib of steam. V Degree-Day as an Operating Unit ........... The degree-day is also widely used as a means of comparing the efficiency of the fuel consumption of one period with another /or the same building. Since the fuel consumption is proportional to the weather (degree-days), and since the periods to be compared may not have the same weather con ditions, the comparison can be made only after the fuel consumptions have been computed on a comparable weather basis, that is, upon the actual number of degree-days occurring for a given month and year in the city under consideration Since fuel consumption'is proportional to the number 460 CHAPTER 18 1956 Guide Table 8. Dbgbee-Days fob Industrial Heating in Various Cities op the United States* Annual Totals for a Normal Heating Season. State Degbeb-Dayb 45F 55F Base State ClTT Degree-Days 45F 55F Base Ala....... Am...: Ark.... Cal.... Col.. Conn.: D. C,... Fla...... Ga...:.: Idaho.. ill.. e.. Ind.. la.... Kan.. Ky.. La... Me.. Md.' Birmingham................... Mobile........................ .. Montgomery.................. 853 245 504 Phoenix., Yuma.... Fort Smith.. Little Rock.. Eureka................... -Fresno......... -- Independence------ Los Angeles.......... Red Bluff.............. Sacramento........... San Diego............. San Francisco... San Luis Obispo.. "3 .519 Denver......................... Grand Junction........ Pueblo......................... 1548 1767 1499 Meriden./.............. New Haven.......... Washington.. 1769 1041 Pensacola;....................... Atlanta............................. Augusta............ Macon..'........................... Savannah........................ Boise......... Lewiston.. Pocatello.. Cairo ....... Chicago........ Springfield.. 109 1045 1034 2161 749 1969 1677 1478 Minn... 1188 1328 718 1930 17 822 803 26 -384 [Bliss.. Mo... 3440 3433 3261 734 3237 Neb..., 2487 127 iNev.... 1165 N. H... 661 711 N. 3.... 231 N. M... 2814' * 2688 |N. Y... 4140 2119 3743 3289 Houghton.............. Lansing.................. Marquette.............. Port Huron........... Saginaw............. Sault Ste. Marie.. 4029 2537 3713 2630 2312 4049 Duluth... .. Minneapolis.. Moorhead.... St. Paul......... 4419 3309 4796 2497 Vicksburg........ Columbia........ Hannibal........ Kansas City.. St. Louis........ Springfield... 1252 1635 1463 1186 Havre-----Helena-- Kalispell. 3736 2843 2874' Lincoln........................... North Platte................ Omaha............................ Valentine....................... 3023 2291 2284 Winnemucca... 1670 Concord....... 2646 Atlantic City.. 1123. Sante Fe.. 1634 Albany.......... 2018 Binghamton. 2073 Buffalo............................ 2359 Ithaca..................... -- 2412 New York......... .......... 1098 Oswego. Rochester........................ J 2274 .3341 Evansville.-... Indianapolis.- 799 1397 Charles City............ Davenport................ Des Moines............... Dubuque......................... Keokuk--.................... Sioux City......... ... 3370 '2296 2440 1628 1926 2894 Concordia. Dodge City.. Topeka......... Wichita.'....... . 1652 1385 1518. 1152 Lexington-- Louisville....... 5293 '4142 4180 4468 3579 4732 2690 2962 1811 2587 2557 2294 iN. C.. N. D.. 3hio............ Charlotte............. Hatteras............... Raleigh................. Wilmington......... Bismarck.. Williston.. Cincinnati..................... . Cleveland........................ Columbus....................... -Dayton..................... . Sandusky........................ Toledo...............-............. 172 229 3831 4616 1525 1600 1487 1949 1990 600 New Orleans.......... Shreveport.............. Eastport.. Portland.. Baltimore.. Boston.......... Nantucket.. Alpena................ Detroit............... Eecanaba........... Grand Haven.. Grand Rapids.. 2956 2530 5236 4572 1787 1514 3131 2240 3699 2405 2332 3603 3419 *5499 4089 5918 3435 4177 Portland.........................Roseburg..................... :. 2321 373 272 Harrisburg................ '... Philadelphia................... Pittsburgh...................... 2337 1565 1122 1938 1377 871 Columbia.'....................... Greenville................. ; 297 6112 4444 5842 4275 4552 6575 6774 5417 6572 5497 468. 2939 3231 2980 2745 2423 5874 5071 5131 3850 4152 3982 4801 3468 4640 2904 3106 * 4302 4296 4316 4023 .3089 4363 718 1080 729 6468 6399 3003 3795 3255 3147 3425 3757 1835 4307 1911 3837 3236 2695 3755 3028 336 759 1502 Estimating Fuel Consumption for Space Heating 461 Table 8. Deghee-Days fob Industrial Heating in Vabious Cities of the United States (Continued) Annual Totals for a Normal Heating Season. State City Degree-Days 45F Base 55F Base State City Degbee-Dayb 45F Base 55F Base S D............ 3743 3162 2590 2898 Chattanooga................... Knoxville.,..................... Memphis.......................... Nashville......................... 242 431 . 166 419 Abilene............................ 786 El Paso............................. Fort Worth...................... Galveston........................ San Antonio................. ! Utah........... 1978 Salt Lake City.............. 1475 5678 5234 4628 6045 1398 1741 1284 1678 2220 919 754 43 3981 3202 Vt................. Burlington...................... Va................ Norfolk............................. Walla Walla..................... W. Va...... Parkersburg.................... Wis............... Green Bay...................... La Crosse......................... Wyo............. Cheyenne......................... 3014 3652 4984 7121 554 1928 260 1496 549 1895 184 2062 1741 507 993 3672 2365 2565 ^ 1506 3327 1147 . 2784 3318 3034 3067 2657 5331 3992 . 4850 4617 : 2500 3208 4700 5450 & From Degree-Day Handbook, by C. Strockand C. H. B. Hotchkiss (The Industrial Press, 1937, pp. 132-134). Values are not coordinated with table 2 which is from a later source. ' of degree-days, plant operators frequently compute each month the fuel burned per degree-day by the heating plant. The resulting unit value, by eliminating the outside temperature variable, indicates whether the operating efficiency of the plant is above or below the previous month or year. INDUSTRIAL DEGREE-DAYS When estimating the heating requirements of warehouses, factories, and other buildings where the inside temperature to be maintained differs greatly from the usual inside temperature range of 68 to 72 F, it is common to use degree-days based on temperatures of 55 to 45 F. These are gen erally referred to as industrial degree-days, and are listed in Table 8 for a number of cities using both 55 F and 45 F as the base. In general, the degree-days (55 F base) are used when the temperature of the heated space is to be maintained at approximately 60 F. For an inside temperature of about 50 F, the degree-days calculated on a 45 F base should be used. ; The industrial degree-days are useful for estimating fuel consumption by comparison between localities in which the difference in degree-days is not too great, and where the known fuel consumption of one building may be used to determine unit consumption per degree-day. . MAXIMUM DEMANDS AND LOAD FACTORS In one form of district heating rates, a portion of the charge is based upon the maximum demand of the building. The maximum demand may be measured in several different ways. It may be taken as the instantane ous peak or as the rate of use during any specified interval. One method is to take the average of the three highest hours during the winter. These figures are shown for a number of buildings in Detroit in Table 9.12 462 CHAPTER 18 1955 Guide These maximum demands were measured by an attachment on the con densation meter, and therefore represent the amounts of condensation passed through the meter in the highest hours, rather, th'an the true rate at which steam is supplied. There might be slight differences in these two quantities due to time lag and to storage of condensate in the system, but wherever this has been investigated it has been found to be negligible. Table 9. Building Load Factors and Demands of Some Detroit Buildings ___. Building Classification Load Factor Lb of Demand peb ` (Hour) (Sq Ft of -Equivalent Installed Radia- tob Subface) - Clubs and Lodges.. . .......................................................;. Hotels........;................................ ................................................ Printing....................................................................................... Apartments................................................... ;............................. Retail Stores__ i............................................................... ........ Auto Sales and Service.................................................... !.... Banks............................ ................ . .. Churches...................................................................................... Department Stores.................................................................... Theaters........................................................................................ 0.318 0.316 0.287 0.263 0.255 0.238 0.223 0.203 0.158 0.138 0.126 ' 0.184 0.207 0.217 .. 0.209 0:225 - 0.182 0.248 0.158 0.152 0.145 0.151 The load factor of a building is the ratio of the average load to the maximum load and is an index of the utilization. Thus, in Table 9, the theaters, operating for short hours, have a load factor of 0.126 as compared with the figure of 0.318 for clubs and lodges. REFERENCES . I Comfort Heating (American Gas Association,.1938). . Are Automatic Air Shutters Justified on a Gas-Fired. Conversion Burner? by W. M. Myler, Jr. and H. W. Nelson (A.S.H.V.E. Transactions, Vol. 55,1949, p. 111). Efficiency of Bituminous-Coal-Burning Space Heater, by J. W. Tieman and F. L. Bagby (A.S.H.V.E. Transactions, Vol. 57, 1951, p. 89). 4 Heat.Losses and Efficiencies of Fuels in Residential Heating, by R. A. Sherman and R. C. Cross (A.S.H.V.E. Transactions, Vol. 43, 1937, p. 185). * The Stoker-Fired Warm-Air Furnace in the Research Residence, by S. Konzo (University of Illinois, Engineering Experiment Station, Circular 39, 1939,- p. 98). * Performance of a Hot Water Heating System in the / = B = R Research Home at the University of Illinois (University of Illinois, Engineering Experiment Station, Bulletin No. 349, Jan. 4, 1944). 7 Fuels and Burners (University of Illinois, Small Homes Council, Circular G3.5, July 1949). * Investigation of Oil-Fired Forced-Air Furnace Systems in the Research Resi dence, by A. P. Kratz and S. Konzo (University of Illinois, Engineering Experiment Station, Bulletin No. 318, Nov. 7, 1939). " 'Graphical Method of Calculating Heat Losses, by Paul D. Close (A.S.H.V.E. Transactions, Vol. 49, 1943, p. 345). 10 House Heating (Industrial Gas Series, American Gas Association, Third Edition). II Report of Commercial Relations Committee (Proceedings, National District Heating Association, 1932). 17 The Heat Requirements of Buildings, by J. H. Walker and G. H. Tuttle (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 171). CHAPTER 19 GRAVITY WARM AIR SYSTEMS Warm Air Leaders, Stacks, and Registers; Return Air Grilles, Ducts, and Connections; Outline of Design Procedure WARM air heating systems of the gravity type are described in this chapter.1 In these systems the motive head producing flow depends upon the difference in weight between the heated air leaving the top of the casing and the cooled air entering the bottom of the casing, while in the forced air type a fan may supply all or part of the motive head. A gravity warm-air furnace heating plant consists of a fuel-burning furnace or heater, enclosed in a casing of sheet metal, which is placed in the basement of the building. The heated air, taken from the bonnet on the top of the furnace casing, is distributed to the various rooms of the building through sheet metal warm air pipes. The warm air pipes in the basement are known as leaders, and the vertical warm air pipes which are installed in the inside partitions of the building are called stacks. The heated air is discharged into the rooms through registers which are set in register boxes placed either in the floor or in the side wall, usually at or near the baseboard. A sectional view of a typical plant showing good installation practice is given in Fig. 1. The air supply to the furnace is usually taken entirely from inside the building through one or more recirculating ducts, although in some cases an outside air supply duct is provided. WARM AIR LEADERS, STACKS, AND REGISTERS In a gravity circulating warm air furnace system, the size of the leader pipe to a given room depends upon the heat loss from the room, the equiv alent length of the leader, and the temperature of the warm air entering the room at the register. For most successful operation, the furnace should be centrally located with respect to register and stack positions so that the leaders will be of uniform length and as short as possible, in which case the frictional resistance to air flow and the temperature loss from the ducts will be about the same for all leaders and stacks. Originally, the design was based on the heat carrying capacities per square inch of leader pipe area with register air temperatures of 175 F. Later, in the revision of the entire design procedure, as shown in the section entitled, Outline of Design Procedure, the carrying capacities of leader pipes have been expressed directly in terms of Btu per hour. In general, it is necessary to use two or more leader pipes to rooms requiring more than the capacity of a 12 in. round pipe. The tops of all sizes of leader pipes should be cut into the furnace bonnet at the same elevation. Leaders over 12 ft in length, or having a large number of elbow fittings should be avoided if possible. In cases where such leaders are necessary, it is recommended that smooth transition fittings be used, and that duct insulation be applied. Asbestos paper, unless of the corrugated, type, should not be considered as insulation. To assist in balancing the air distribution of the system, a damper should be placed in each leader 463 464 CHAPTER 19 1956 Guide pipe except one. Some local regulations require that a damper be omitted in one leader connected to a room heated at all times: In a gravity circulating system, the ratio of stack to leader area is quite important, although little is gained by providing wall stacks with areas in excess of 75 percent of their connected leader pipe area. In most cases Fig. 1. A Sectional View of a Typical Plant Showing Good Installation Practice* A. House chimney, no bends nor offsets. B. Top of chimney at least 2 ft above ridge of roof. C. Flue lining, fireclay., D. All joints air tight. E. At least 8 in. brick. _ F. No other connection beside that to furnace. G. Cleanout frame and door, airtight. H. Smoke pipe, end flush with inner surface of flue. I. Draft door. J. Use flue thimble. LK.. CCaassiinngghboooddyo. r bonnet, top of all leader collars on -same level. M. Round leader, pitch 1 in. per foot N. Sleeve with air space or 1 in. of noncoznbustible insulation around leader where pass ing through wall. O. Dampers in ail leaders. F. Transition fittings. Q. Rectangular wall stack- R. Baseboard register. S. Distributes pipes equally around bonnet. T. Floor register. U. Return air face. V. Panning under joist W. Transition collar. . X. Round return pipe. YZ.. TTorapnosfitsiohnoeshaotec.asing not above grate level. Code and Manual, Fifth Edition, 1954. * From HWAHAACA Manual S: Gravity a 3]4 in- x 12 in. stack is the largest which can be installed in normal wall construction. Hence, any room having a heat loss much in excess of 9000 Btu per hr, will require two or more stacks, or one oversized stack built into a 6 in. studding space, providing the design register temperature is to be retained at the average value of 175 F, which has been recommended. Registers used for discharging warm air into rooms should have a free area not less than the area of the leader pipe to which the register is at Gravity Warm Air Systems . 465 tached. First story registers should be connected through boot and register box extensions having areas at least equal to leader areas. Upper story registers should be of the same width as the wall stack, and should be placed either in the baseboard or sidewall, preferably without offsets. First story registers may be of the baseboard or floor type, with the former location preferred. Leader pipes or stacks intended to heat two rooms are not recommended. RETURN AIR GRILLES, DUCTS, AND CONNECTIONS The placement and number of return grilles will depend upon the size, details, and exposure of the house. Small compactly built houses may be adequately served by a single return grille effectively placed in the central hall. It is usually desirable to have two or more returns, provided that in two-story residences one return is placed to receive effectively the return air at the foot of the stairs. A return air connection must be carried to any room whose floor level is below that of adjacent rooms. Return ducts from upstairs rooms may be necessary in spaces which are closed off from the rest of the house, or which have much outdoor exposure. Return grilles on different floor levels should not be connected to the same vertical return duct. The return air grilles should have free areas at least equal to the ducts to which they connect, and should be installed in the floor, or in the base board with the top edge of the grille not more than about 14 in. above the floor line. As frictional resistance in the return air system is as detrimental as resistance in the warm-air system, care should be exercised in locating return air grilles which require long return ducts. The frictional resistance of the long ducts used in parallel with short return ducts must be reduced to compensate for the length. This is ac complished by using design data given in the following section, Outline of Design Procedure. The ducts through which air is returned to the furnace should be designed to minimize resistance to air flow. They should be of ample area, with sizes selected according to capacity and construction, as specified in section, Outline of Design Procedure, and should be streamlined. Avoid fittings which would require lifting of the return air after the duct has passed under some obstacle. Ducts returning air to the furnace should be protected from heat sources tending to reheat the return air. If the duct must be run over the top of the furnace, or above the vent pipe from the furnace, insulation should be interposed between the heat source and the duct. The top of the return shoe should enter the casing below the level of the grate of a coal furnace, and not more than 14 in. above the floor of an oil or gas furnace. It must be wide enough to retain proper area. OUTLINE OF DESIGN PROCEDURE _ The data underlying the design procedure are given in detail in a circular2 issued by the University of Illinois. In this procedure the design of the warm-air duct system is considered as an entire unit, so that for a given heat loss the sizes of leaders, stacks, boots, stackheads, and registers are 466 CHAPTER 19 1956 Guide Table 1. FirstStoey Warm Ajb Ducts* Warm Air Combination No. Throat Sue Leader Pipe Diameter, Inches Pipe Area Sq In Register'Size, Inches Baseboard Size Extension Floor i 6% x 10 8 2 6% x 12 9 3 m x 12 10 4 9% x 13 12 3db 8% x 12 10 4d 10% x 12 12 50 10 x 8 2M 8 X 10 64 12 x 8 2M 9 x 12 78 12 x 9 3M 10 x 12 113 13 x 11 12 x 14 78 2(12 x 8) 2M 113 2(12 x 9) 3M * When the calculations indicate a requirement for a given room greater than Combination No. 4, two or more smaller units totalling the required capacity are recommended. b Double headers are permissible only where full throat areas are obtainable and room privacy is not essential. Use combination number representing total load. Combinations 3d and 4d have same capacities in Table 6 as combination 3 and 4 respectively. Table 2. Second Story Warm Air Ducts--Single Wall Stacks and Fittings Combi nation No. Stack, Size, Inches ' . Leader Pipe Di AMETER, Inches Pipe Area Sq In Register Size, Inches Baseboard Size Extension Floor Sidewall ii 12 14 15 16 12db 14db 10 x 3% 12 x 3% 14 x 3% 12x5M 14 x 5j 12 x 3% 14 x 3% .8 9 10 12 12 9 10 50 10 x 8 64 12 x 8 78 13 x 11 113 12 x 9 113 13 x 11 64 2(12 x 8) 78 2(12 x 8) 2 8 x 10 10 X 8 2M 9 x 12 12 x 8 m 12x8 3J4 5% 2M 2(12 x 8) 2M 2(12 x 8) * Recommended stack sizes. Tables may also be applied to 3 in. and 3 1/2 in. stack depths. b Combinations 12-d and 14-d have same capacities in Table 7 as combinations 12 and 14 respectively. Table 3. Second Story Warm Air Ducts--Double Wall Stacks and Fittings Combi nation No. Leader Pipe Di ameter, In. Pipe Area Sq In. . Stack Size, In. Internal External 21 8 50 2%` x 10 8%` x 10^ 22 8 50 3 x 10 3% xlOM 23 9 64 2M* x 12 3M* x 12% 24 9 64 3 x 12 3% *12^ * Commercial sizes vary 1/8 in. from values shown. Register Sub, In. Floor 8 x 10 8 x 10 9 x 12 9 x 12 Baseboard Size 10 x 8 10 x 8 12 x 8 12 x 8 Ex tension 2M 2M 2H Sidewall 10 x 8 10x8 12x8 12 x 8 all correlated. Similarly in the case of return ducts, the selection specifies a complete unit consisting of return grille, return duct, and shoe connection. Recommended Standard Sizes For the purpose of simplification and standardization, selected combina tions of commercial sizes of warm air pipes, return air pipes, duets, grilles, fittings, and registers are designated as Combination Numbers. The numbers assigned and the combinations selected as standard are fisted in the following Tables 1 to 4 inclusive.3 . The selected types of fittings are shown in Fig. 2, and their resistances Ax- Gravity Warm Air Systems . 467 ' Table 4. Return Air Ducts Combi nation No. Duct Dia. In. Duct Area Sq. In. When Joist -Space. .. Is Used* No. of Min.b Joists Depth Lined ' In. Metal Grille Sizes . Choose One ABC Base board - Intake for First Stobt Area at Shoe Con nection, ` Sq. In; When Duct Is Used Choose One 31 10 78 7 8 x 14 10 x 12 32 12 113 or 2 9 5 6* 30 8x24 12 x 14 14 x 10 4-In. Ext. 33 14 154 1 12 or 2 6 8x30 10x24 14 x 16 . 170 34 16 20L . .1 18 ` 10x30 12x24 or 2 8; 220 35 18 254 36 20 314 2 10 12 x 30 14 x 24 2 12.5 14x30 18 x 24 30 x 10 1 280 4-In. Ext. 340 37 22 380 2 15.0 18x30 420 33 24 -452.^ . 2 18.0 20x30 ' 500 14 x 6 12 x 8 22 x 6 16 x 8 28 x 6 22 x 8 28 x 8 22 x 10 36 x 8 28 x 10 36 x 10 30 x 12 42 x 10 36 x 12 42 x 12 36 x 14 * Based on 14 in. space between joists. - b Use full depth of joist except when joist depth is less than minimum depth required, when non must be used. -' -- . Floor ' Register G I Fig. 2. Typical Warm Air Boots 468 CHAPTER 19 1956 Guide S Gouge sheetmetal , thick/ oxtending a> beyond Cosing X f\ incombustible rotr space-open Insulated with or Space, or cov ered with magne sia. asbestos, or Sand Inner liner-from top casing ring to grate level rfeto! casing 'famoce foundation-of brick, cementor other like \ incombustible material Fig. 3. Details of Furnace Bonnet, Casing, and Foundation (Fbom NWAH & ACA Manual 5, Fifth Edition) Table 5. Resistances of Wabm Aik Boot Combinations Expressed in Elbow Equivalents Wabm Aib . Boot A: B C D E F -. Name or Combination 45-Deg Angle Boot and 45-Deg Elbow 90-Deg Angle Boot Universal Boot and 90-Deg Elbow End Boot Offset Boot 45-Deg Angle Equivalent . No. OF 90-Deg Elbowb .i i i 2 G H I J K L. Floor Register--Second Story Offset Offset Round Side Take-Off Offset Starting Collar Straight Starting Collar 2 3 2 1 1 3 Fig. 4. Details of Bonnet and Leader of Gravity Warm-Air Furnace (From NWAH & ACA Manual 5, Fifth Edition) ` Gravity Warm Air Systems 469 Table 6. Warm Air Carrying Capacity, Btuh Delivered, First Story Registers Combination N<v 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 Actual Length (Bonnet to Boot) Feet 6 No. OF 6H 4 6 8 10 4 6 8 10 12 14 7 4 6 8 10 12 14 16 18 1 2 3 ----------- 5 7H g 2. . J62 $ T * IT la 1-1' 5 a '3 4 6 8 10 12 14 16 IS 20 22 6,020 5,850 5,680 5,510 5,340 5,170 5,000 4,830 4,660 4,490 7,620 7,400 7,180 6,970 6,760 6,540 6,320 6,110 5,890 5,680 9,400 9,140 8,870 8,600 8,340 8,070 7,8I0j 7.540 7,270 7,010 13,350 12,970 12,590 12,210 11,830 11,450 11,080 10,700 10,320 9,950 5,850 5,660 5,490 5,330 5,160 5,000 4,840 4,670 4,510 4,340 7,360 7,150 6,940 6,730 6,520 6,320 6,110 5,610 5,700 5,500 9,090 8,840 8,580 8,320 8,060 7,800 7,550 7,290 7,040 6,780 12,910 12,540 12,170 11,800 11,430 11,060 10,690 10,320 9,950 9,580 5,620 5,460 5,310 5,150 4,990 4,830 4,670 4,510 4,350 4,190 7,120 6,910 6,710 6,510 6,310 6,110 5,900 5,700 5,500 5,300 8,780 8,530 8,280 8,030 7,780 7,530 7,290 7,040 6,800 6,550 12,450 12,100 11,750 11,400 11,050 10,700 10,350 10,000 9,650 9,300 5,420 5,260 5.110 4,960 4,800 4,650 4,500 4,350 4.190 4,040 6,860 6,660 6,460 6,270 6,080 5.890 5,690 5,500 5.30C 5,110 8,460 8,220 7,980 7,740 7,500 7,260 7,020 6,780 6,550 6,310 12,010 11,670 11,330 10,990 10,650 10,310 9,970 9,630 9,290 8,950 5,240 5,090 4,940 4,790 4,640 4,500 4,350 4,200 4,050 3,910 6.630 6,440 6,250 6,060 5,880 5,690 5,500 5,320 5,130 4,940 8,180 7,950 7,720 7,490 7,260 7.030 6,800 6,560 6,330 6,100 11,610 11,290 10,950 10,620 10,300 9,970 9,640 9,320 8,990 8,660 Nolee: Carrying capacity and length of run increased with basement depth.. ' ' ' Length of trunk and carrying capacity of gravity extended plenum installations should be based on the 6 ft basement depth capacities. ' pressed in equivalent elbows are shown in Table 5. It is essential that free areas be maintained throughout fittings. Figs. 3 and 4 show recommended practice as given in Manual 5 of the National Warm Air Healing and Air Conditioning Association. '' For con struction, design features, and ratings of gravity furnaces see Chapter 16. Carrying Capacity The Btu per hour carrying capacities of the selected warm air and return air combinations are shown in Tables 6, 7 and 8. The selected types of return air ducts and fittings are shown in Fig. 5. Design Procedure The steps to be taken in designing a gravity warm air duct system are: 1. Calculate the heat loss from each room as explained in Chapters 9,'ll aiid 12. 2. Prepare a layout showing (a) furnace, (6) chimney connection, (c) warm air registers (whether floor, baseboard or wall), (d) return air grilles. ' . 3. Indicate on each warm air leader (using symbols shown in Fig. 6): (a) whether the room to be heated is on first or second story; (b) the approximate length of leader pipe in the basement; (c) the number of right angle elbows and equivalent elbows (Table 5) required, including the elbow at the boot connection (see Fig. 2); (d) whether the register is to be located in the floor, in the baseboard, or in the wall. 470 CHAPTER 19 1956 Guide Table 7. Warm Aib Capacity, Btuh Delivered Second Story Registers Actual Length (Bonnet to Boot) Feet ;e ' 4 . 6 . 8 - 10 1 12 14 16 18 TION No. ; Elbows 6H 4 6 8 10 12 14'. . l46 5. 18 20 7. 4 6 8 10 12 14 16 18 20 22 . 4 6 8 10 12 14 16 18 20 22 . 24 11 or 22 12 or 24. 14-. . - 15 11 or 22 12 or 24 14 : 15. 11 or 22 . 12 or 24 14 15 il or 22 12 or 24 14 15 11 or 22 12 or 24 14 . 15 3. .4 5 - g ' ; O .: O : .o : o' T 8.370 8,140 7,900 7.670 7,430 7,190 6,950 6,710 6.470 6,240 6,000 10,040 9,760 9,470 9,190 8,900 8,620 8,330 8,050 7,770 7,480 7,200 11,710 11,380 11,050 10,720 10,390 10.060 9,720 9,390 9.060 8,730 8,400 16,200 15,750 15,300 14,840 14,380 13,920 13,460 13,000 12,550 12,100 11,640 7,940 7,720 7,500 7,280 7,050 6,830 6,600 6,370 6.150 5,930 5,700 9,540 9,270 9,000 8,730 8.460 8,190 7,920 7,650 7,380 7,110 6,840 11,120 10,810 10,500 10,180 9,870 9,550 9,230 8,920 8,610 8,290 7,980 15,400 14,970 14,530 14,100 13,670 13,230 12,800 12,360 11,930 11,500 11,070 c gj j-i ' fit! 5 vS 5 7,530 7,320 7,110 6,900 6,680 6,470 6,250 6,040 5,830 5,626 5,400 9,030 8,780 8,520 8,270 8,010 7,750 7,500 7,240 6,990 6,730 6,470 10,530 10,240 9,940 9,650 9,350 9,050 8,750 8,450 8,160 7,860 7,560 14,580 14,180 13,780 13,370 12,950 12,530 12,120 11,710 11,300 10,890 10,480 7.120 6,920 6,720 6,520 6,310 6,110 5,900 5,700 5,500 5,300 5,100 8,530 8,290 8,050 7,810 7,570 7,330 7,080 6,840 6,600 6,360 6,120 9,950 9,670 9,390 9,110 8,830 8,550 8,260 7,980 7,700 7,420 7,140 13,780 13,390 13,000 12,610 12,220 11,830 11,440 11,050 10,670 10,280 9,890 6.700 6,510 6,320 6,130 5,940 5,750 5,560 5,370 5,180 4,990 4,800 8,040 7,810 7,580 7,350 7,130 6,900 6,670 6,440 6,220 5,990 5,760 9,370 9.110 8,850 8,580 8,310 8,050 7,780 7,510 7,250 6,980 6,720 12,970 12,600 12,240 11,870 11,500 11,140 10,770 10,400 10,040 9,680 9,310 Notes: When floor registers are used on second story rooms, include the equivalent elbow resistance for the cross-over connection as shown in Fie. 2. . ... . ' Combination Numbers 21 and 23 as shown in Tables 2. and 3 are composed of narrow stacks for narrow stud spaces. _ ' . . For Combination No. 21, the capacities are the Btuh deliveries shown for Combination Nos. 11 or 22 multiplied by 0.83. For Combination No. 23, the capacities are the Btuh deliveries shown for Combination Nos. 12 or 24 multiplied by 0.83. ... . Table 8. Return Air--Carrying Capacity--Btuh Serviced Return Ant Combina tion No. 31 32 33 34 35 36 37 38 Duct Dlam. In. 10 12 14 16 18 20 22 24 Type A BTUH 11,300 16,300 22,200 29,000 36,700 45,300 54,800 65,200 Types B and C BTUH 9,500 13,700 ' 18,700 24,400 30,800 38,000 46,000 54,800 Type D BTUH 7,800 11,300 15,300 20,000 25,300 31,300 37,800 45,000 Type E BTUH 7,800 11,300 15,300 20,000 25,300 31,300 37,800 45,000 Type F BTUH 5,000 7,200 9,800 12,800 16,200 20,000 24,100 28,700 Return Air Com bination No. 31 32 33 34 35 36 37 38 4. Show the number and proposed locations of return air grilles and the type of return-air system (see Fig. 5). 5. From Table 6, for first story, or from Table 7 for second story, select the com bination number for the warm air system which will supply the heat required to each room, with the number of elbows and length of leader pipe previously deter mined. Then,.using the combination number as found, read directly in Tables 1, 2, or 3 the leader, stack, and register sizes required. #* 6. From Table 8 select the combination number for the return air system to cor- Gravity Warm Air Systems r-RETURN AIR GRILLE 471 TYPE E Nole: For Types C, D, E, and F return-air systems, reduce tbe carrying capacities shown in Table 8 by * percent for each 4 ft additional length in the horizontal run. Fig. 5, Typical Arrangements of Return-Air Duct Systems respond with the Btu per hour serviced and the type of return air system. Then from Table 4 select the duct and grille sizes, etc., corresponding to this number. 7. Select a furnace having a bonnet output, in Btu per hour, one-third greater than the heat loss from the structure, to compensate for duct heat loss. 472 CHAPTER 19 1956 Guide Fig. 7. Typical Basement Line Drawing fob Extended Plenum Gravity Warm Air Systems 473 Design of Extended Plenum Systems The extended plenum system of gravity warm air heating employs horizontal ducts in the basement leading from an enlargement or extension of the customary plenum to the risers which distribute the conditioned air to the various rooms. A typical basement plan for a system using an extended plenum is shown in Fig. 7. Extended plenum gravity systems have been satisfactorily designed and installed in small compact single-story houses where the heat losses do not exceed 65,000 Btuh. The dimension from the floor to the bottom of the joists should in every case be at least 7 ft. To design such a system the procedure is the same as for the conventional system already described in this chapter. It is understood that the length of leader pipe is the horizontal distance measured from the register to the furnace. For takeoffs, use standard fittings designed for extended plenum connection and allow the equivalent ' length of one 90-deg elbow. Sizing an Extended Plenum To size an extended plenum, proceed as follows: 1. Make a layout of the furnace, extended plenum, branches and registers, similar to Fig. 7. 2. Follow methods given in paragraphs 1,2,3 and 5, under Design Procedure for a conventional system, to determine the diameters or equivalent rectangular sizes of the branches from the extended plenum to registers. 3. Starting with the most remote branch connected to an extended plenum, write its equivalent size as if it were 8 in. in depth. For example: an 8-in. diameter branch is equivalent to a 6-in. wide x 8-in. deep duct (see Table 9). As each additional branch is reached, determine its rectangular equivalent size as if it were 8 in. deep. In the last column of Table 9 find the additional width of plenum required to supply the added branch. When all branches have been included, the sum of the widths added for each branch plus the width of the most remote branch will give the equiv alent width for a plenum of 8-in. depth. The depth of plenum to be selected should be that of the largest branch. The width selected can be determined from the lower section of Table 9 where a plenum of desired depth can be found equivalent to the size computed for an 8-in. deep plenum. For example: if the size based on an 8-in. plenum is found to be 22 x 8 in. the plenum may be 17 x 10 in. or 14 x 12 in. The extended plenum is not changed in size from furnace to end of the plenum. Return air intakes are to be sized by the same method as for conventional gravity systems. Resign Examples Examples 1 and 2 will illustrate the use of the tables in selecting warm air and return air system.sizes. Example 1: For a room which has a heat loss of 22,500 Btu per hr, select the size of first story warm-air system. There are three elbows, and the leader is approxi mately 10 ft long. Solution: Since 22,500 Btu is beyond the capacities shown in Table 6, it is neces sary to select two units of 11,250 each. From Table 6 in 10 ft leader column, and in section for three elbows, find 11,400 as nearest capacity which corresponds to Com bination Number 4 in first column. Refer'to Combination Number 4 in Table 1 and find that the leader should be 12 in. in diameter, and should be used with a 12 x 14 in. floor register or a 13 x 11 in. baseboard register with a 5J4 in. extension. Example 8: What is the size of a return air system of Type D which is to service 35,000 Btu per hr? 474 Combination i 2 3 or 3d 4 or 4d CHAPTER 19 1956 Guide Table 9. Fob Sizing Extended Plenum ___________________________________________________________________________ i_ Round Branch Diam Inches ' Rectangular Size (8-in. Depth) Inches Plenum Addition - Inches 8 6x8 4 9 8x8 5 10 11 x 8 . 8' 12 16 x 8 12 Equivalent Plenum Size for Change to Depth Other Than 8 In. 8-in. Depth Inches 16x8 18 x 8 20 x 8 22 x 8 10-in. Depth Inches 12 x 10 14 x 10 16 x 10 17 x 10 - 12-in. Depth Inches . 12 x 12 13 x 12 14 x 12 24 x 8 26 x 8 28 x 8 30x8 32 x 8 34 x 8 37 x 8 39 x 8 42 x 8 45 x 8 47 x 8 51 x 8 18x10 19 x 10 21 x 10 22 x 10 24 x 10 25 x 10 27 x 10 29 x 10 31 x 10 33 x 10 35 x 10 : 37 x 10 15 x 12 16 x 12 17 x 12 18 x 12 ' 19 x 12 21 x 12 22 x 12 23 x 12 25 x 12 26 x 12 28 x 12 29 x 12 Solution: From Table 8 find Combination Number 37 which will service 37,800 Btu per hr. Refer to Table 4 to find that Combination Number 37 will require a 22-in. diameter duct, a shoe area of 420 sq in., a metal grille 18 x 30 in., a duct 42 x 10 in. or 36 x 12 in. If joist lining is used the minimum depth should be 15 in. for two 2-joist spaces 14 in. wide, or 10 in. for three joist spaces. , REFERENCES 1 The engineering data were obtained from University of Illinois, Engineering Experiment Station Bulletins Nos. 141,188,189 and 246; Warm Air Furnaces and Heat ing Systems, by A, C. Willard, A. P. Kratz, V. S. Day, and S. Konzo. See also Manual 5: Gravity Code and Manual for the Design and Installation of Gravity Warm Air Heating Systems, 5th Edition, 1954, published by the National Warm Air Heating and Air Conditioning Association. * Simplified Procedure for Selecting Capacities of Duct Systems for Gravity Warm Air Heating Plants, by A. P. Kratz and S. Konzo {University of Illinois, Engineering Experiment Station Circular 45, Dec., 1942). 9 Gravity Code and Manual for the Design and Installation of Gravity Warm Air Heating Systems, Manual 5, 5th Edition, 1954, (National Warm Air Heating and Air Conditioning Association). CHAPTER 20 FORGED WARM AIR SYSTEMS Air Distribution, Standard Combinations of Parts, Simplified Method, of. Design, Design Procedure for Large Systems, Automatic Controls, Ceiling Panel Systems, Perimeter Systems, Summer Operation : : IN forced warm air heating systems, the air circulation is effected by motor-driven centrifugal fans, commonly referred to as blowers. The advantages of forced air systems are: 1. The furnace may be placed in any part of the structure. 2. Distribution ducts can be made small enough to be inconspicuous and out of the way, or-be completely concealed from view where desired. 3. Circulation of air is positive, and in a properly designed system, can be con trolled in such a way as to give a comfortably uniform temperature distribution. 4. Humidity control is readily attained. 5. The air may be cleaned by filters or other means. 6. The fan and duct equipment may be designed for a complete cooling and dehumidifying system for summer, using either ice, mechanical refrigeration, or low temperature water for cooling and dehumidifying, or adsorbers for dehumidifying. 7. - The use of the fan permits flexibility in the location of supply and return grilles as required to obtain proper distribution of air for comfort. 8. Ventilation air may be positively introduced and conditioned. The construction features of forced warm air furnace units and the function and selection of the various parts of a system are discussed in Chapter 16 and other publications.1 -, AIR DISTRIBUTION The conditions of comfort obtained in a room are influenced greatly by the type of register used, and the locations of the supply registers and return grilles. In general it has been found that changes in the type, air velocity, and location of the supply register affect the room conditions much more than the changes in the location of the return grilles. One method is to locate the supply register near the floor, or high in the side wall, so that the warm air. from the register blankets a cold wall, and mixes with the cold air descending from the exposed walls and glass. Another method is to locate the supply openings near the floor, or high in the side wall, on the inside wall, and the return openings near the greatest outside exposure. Still another method is to locate all supply openings around the outside wail, near the source of the greatest heat loss, usually beneath the windows, and to use grilles designed to blanket the cold area. This, causes mixing of the warm air delivered with the cool air from the heat loss area and the 475 476 CHAPTER 20 1956 Guide V. cold air from infiltration thus effectively preventing drafts. This has been called perimeter heating. In any case, the warm air registers should be located so that the air stream never discharges directly against people at rest. Tests2 in Warm Air Research Residence No. 1 at the University of Illinois, have indicated that continuous blower operation, gave better re- ' suits than intermittent operation. Register and Grille Openings . Tests also conducted in Warm Air Research Residence No. 1 have in dicated that, comparable results are obtainable with either high side wall or baseboard registers, if proper registers and air velocities are selected. Baseboard registers should be of a deflecting-diffuser type which throw the Forced Warm Air Systems ' - -- 477 of Manual 7, these manuals being publications of the National Warm Air Healing and Air Conditioning Association. . ., Registers should be well proportioned and decorated to harmonize with the trim. Air supply registers should be equipped with dampers, and all registers should be sealed against leakage around.edges. The register types shown in Figs. 1, 2 and. 3 have been recommended as standard by the National Warm Air Healing and Air Conditioning Association. . Return air. grilles may be located in hallways, near- entrance doors, under windows, in exposed comers, or inside walls, depending on location of supply registers. Baseboard returns are preferable to floor grilles where warm air registers are located on inside walls. Where perimeter heating is used, returns placed high oh inside walls are preferred. Fig. 1. Recommended Type of Baseboard and Low Sidewall Installation on ' ' Warm Wall* Vertical bars with adjustable deflection, or fixed vertical bars with deflections 1. r!gh`"d iS?-2,TM exceeding about 22 deg. For low sidewall location, the deflection for horizontal, multiple vane registers should not exceed 22 deg. For baseboard locations, the deflection for horizontal, multiple vane registers should not exceed about 10 deg. . .- air downward toward the floor and diffuse it at the same time. For base board registers, air: velocities over 500 fpm, should be avoided as they may cause discomfort. .' " ' , High side wait registers should be of such type that the air is delivered horizontally or in a slightly downward direction, and should be so located as to avoid impingement of air on ceiling or wall. Directional flow dif fusing type registers should be used to insure best results. Register air velocities should be such that the air velocity will be about 50 fpm three quarters of the distance from the register to the opposite wall. Velocities through registers may be reduced by the use of registers larger than the connecting ducts. Diffusers should be used to spread the air uniformly over the register face. Basic rules for the location and selection of registers, together with explanations of factors affecting operation, are giyeh3 in Section 6 of Manual 4, Sections 3 and'4.of.Manual 10, or Section B Fig. 2. Recommended Type of High Sidewall Installation on Warm Wall* * Horizontal vanes, in back or front, to give downward deflections not to exceed from 15 to 22 deg. Dampers Suitable dampers for air direction or volume control are essential to any duct system. Special care must be used in the design of any system, to minimize resistance. Sharp elbows, angles, and offsets should be avoided. Three types of dampers are commonly used. Volume dampers are used to completely cut off or reduce the flow through ducts. Splitter dampers are used where a branch is taken off from a main trank, .Squeeze dampers are used for adjusting the Volume of air flow and resistance through a given duct. A damper with positive locking device should be provided for each main or duct branch.' Labels placed on ducts should indicate the room being served. Damper positions should be marked to'indicate proper summer and winter settings, and to reveal tampering. Ducts ' ' The ducts may be either round or rectangular in cross section. The centerline radii of elbows should preferably be not less than one and onehalf times the pipe diameter for round pipes. The throat radius of a turn 478 CHAPTER 20 1956 Guide in! a rectangular duct should be at least one-half the duct dimension in the plane of the turn. Warm air ducts passing through cold'spaces or located in exposed walls, should have 1 to 2 in. of insulation!. . : Special attention should be given to the problem ofmoise elimination; The metal,duct connection to and from the furnace casing and fan housing should be broken by strips of fire resistant fabric. Motors and mountings must be carefully selected for quiet operation. Electrical conduit and water , piping must not be fastened to,, nor make contact with the fan housing. Installation of a fan directly'under a. return air grille is. usually avoided. . . ' .3: r - STANDARD COMBINATIONS OF PARTS ,, The combinations of parts selected as standard by the National Warm Air Heating and Air Conditioning Association are shown in Tables 1 and Fig. 3. Recommended Type of Flooh ok Low Sidewall Installation on Out side Wall* * Registers set to direct air. upward along the wall at as wide an angle as possible. > 2. A method for selecting these combinations is indicated in the following section Simplified Method of Design. . ' SIMPLIFIED METHOD OF DESIGN A simplified method for selecting the combinations of branches, boots, stacks, and registers, is given3 in Manual 7 of the National Warm Air Heating and Air Conditioning Association. In this method, the sizes of the branch ducts are obtained from two tables giving their Btu capacities. The proper combination of parts for each branch can be determined if the follow ing information is available. . Location of room, that is, whether on first or second story. . Actual horizontal length of duct from bonnet to boot, in feet. c. Btu loss from room to be heated. \ d. Equivalent lengths in feet of all .fittings and of the register. Fig. 4 shows the values of equivalent lengths of fittings commonly used for domestic.systems. ST Forced Warm Air Systems Table 1. Capacity and Sizing Table--First Story For Warm Air and Return Air Stack, Branch, and Registers Equiv. Length of Fittings and Registers Horizontal Length Furnace | to Register First Stobt Room Heat Loss--btuh 479 : Col. d Col. e Col. f Col. e Col. h Col. i Col. j 5 7,200 12,500 -9 0,700 11,700 3 0,100 10,800 8 5,600 9,900 5 4,800 5 4,100 8 3,500 5 3,000 5 5,500 9 5,100 3 4,800 8 4,500 8.500 7.400 6.400 5.500 9.900 9,200 8,600 8,100 5 3,900 5 3,400 5 3,000 5 2,600 4,600 > 4,300 1 4,100 ? 3,800 7,100 6,200 5,400 4,600 8,500 7.900 7,400 6.900 3.300 3,000 2,700 2.300 4,100 3,800 3,600 3,400 6,100 5,300 4,700 4,000 7,300 6,900 6,400 6,000 2,900 2,600 2,300 2,000 3,800 3,500 3,300 3,100 5.300 4,700 ' 4,200 3,600 6,500 6,100 5,700 5.400 2.700 2,400 2,100 1.700 4.800 4,300 3.800 3,000 Combination Number Stacksb No. Size Rectangular Branch Size Round Branch Size (Diam) Number of Joist Spaces and _ Minimum Depth-Return Air Registers: Low Wall, High Wall or Baseboard 41 10x3% 3x8 5 1 at 3 10x6 42 1 10x3% 4x8 6 1 at 3 10x6 Registers: Floor-Warm Air 8x10 8x10 16,000 15.000 14.000 13.000 11.000 9,900 8.700 7.700 13,100 12,300 11,600 10.900 9,700 8.500 7.500 6.500 11,300 10,600 10,000 9.400 8.400 7.400 6,500 5.400 9,800 9.100 8,600 8.100 7,200 6.400 5,600 4,700 8,800 8,200 7, F00 7,200 6,400 5,700 5,000 3,900 43 1 12x3% 5x8 7 1 at 4 12x6 9x12 19,100 18,000 17.000 16.000 14,200 12,500 11,000 9,600 16,300 15.400 14,500 13,700 12,200 10,800 9,500 8,300 14,300 13,500 12,700 11,900 10,500 9.300 8.300 7,000 12.300 11,700 11,000 10.300 9.100 8.100 7,100 6,000 11,000 10,500 9,900 9,300 8.300 7.300 6,400 5,100 25,000 23,400 21,600 19,800 17.000 14.800 12.800 11.000 19,800 18,400 17.200 16.200 14.200 12,400 10,800 9.200 17,000 15.800 14.800 13.800 12,200 10,600 9,400 8.000 14,600 13.800 12.800 12,000 10,600 9,600 8,400 7,200 13.000 12,200 11,400 10,800 9.600 8.600 7,600 6,000 32.000 30.000 28.000 26,000 22,600 19,800 17.400 15.400 26,200 24,600 23,200 21,800 19,400 17.000 15.000 13.000 22,600 21,200 20,000 18,800 16,800 14.800 13,000 10.800 19,600 18,200 17.200 16.200 14.400 12,800 11,200 9.400 17,600 16.400 15.400 14.400 12,800 11,400 10.000 7,800 80,000 75.000 70.000 65.000 56.500 49.500 43.500 38.500 65.500 61.500 58,000 54.500 48.500 42.500 37.500 33.500 56.200 52,600 50.200 47,300 42.000 37.000 32,400 27.000 49,200 45,800 41,900 40.300 36,000 31,800 28,100 23,500 44,100 51,500 38,800 36,000 32,000 28,200 24,700 19,500 44 1 14x3% 6x8 8 1 at 5 14x6 9x12 45 2 10x3% 8x8 9 1 at 6 or 2 at 3 (2)10x6 or (1)24x6 10x12 46 2 12x3% 10x8 10 1 at 7 or 2 at 4 (2)12x6 or (1)30x6 12x14 47 15x2 12 1 at 9 or 2 at 5 -- Registers: Floor-Return Air Trunk Duct Increase, Inches 6x10 or __ 4x14 6x10 or 4x14 2 6x12 or 6x14 3 longer 6x14 4 6x30 5 6x30 7 8x30 12 ____________.cm mku afMxces sua losuiatea auecs in unseated spaces. b Note: For return air a 14x3% in. stud space may be used instead of 10x3% in. stack. Where 12x3% in. r 14x3% in. stack is required, a 14x3% in. stud space may be used only when inside of stud space is smooth &nd without protruding plaster keys. The number o! joist spaces for combination 47 is based on 2x8 in. joists. One space may be used with 2x10 in. joists. The limiting factor for a duct combination is the stack capacity. 480 CHAPTER 20 1956 Guide 2.Table Capacity and Sizing Table--Second Story For Warm Air and Return Air Slack, Branch, and'Registers Equiv. Length or Fittings AND Registers Horizontal Length Furnace to Register ] Ducts* Attic Ducts CoL a Col. b Col. c. Col. d Up to 70 Eq. Ft. Up to 7 8-12 13-17 18-25 Up to 5 6-9 10-13 14--IS 26-35 36-45 46-55 16-25 26-35 36-45 46-55 71 to 100 Eq. Ft. Up to 7 8-12 13-17 18-25 Up to 5 6-9 10-13 14-18 26-35 36-45 46-55 19-25 26-35 36-45 46-55 101 to 130 Eq. Ft. Up to 7 6-12 13-17 18-25 Up to 5 6-9 10-13 14-18 26-35 . 36-45 46-65 19-25 26-35 36-45 .46-65 131 to 165 Eq. Ft. Up to 7 8-12 13-17 18-25 Up to 5 6-9 16-13 14-18 26-35 36-45 46-55 19-25 26-35 36-45 46-55 166 to 200 Eq. Ft. Up to 7 8-12 13-17 . 18-25 26-35 36-45 46-55 Up to 5 6-9 10-13 14-18 19-25 26-35 36-45 46-55 6,300 5,700 5,200 4,800 4.100 3,500 3.100 2,800 5.000 4,600 4,300 4.000 3,400 3,000 2,700 2,300 4,200 3,900 3,700 3.500 3.000 2,600 2,400 2.000 3,800 3,500 3,200 3.000 2,700 2,300 1,900 1,800 3,500 3.200 2.900 2.700 2.500 2,100 1,900 1.500 Col. e 10,900 10,000 9,200 8,500 7,300 6,400 5,600 5,000 9,000 8,200 7,600 7,100 6,200 5,400 4,700 4,200 7.700 7.200 6.700 6.200 5,400 4,700 4,100 3,600 6,800 6,300 5,800 5,500 4,800 4,200 3,400 3,300 6,100 5,700 5,390 5,000 4.400 3,900 3.400 2,800 Second Story Room Heat-Loss--btuh Col. f Col. g Col. h CoL i 14.000 13.000 12,100 11,400 10,000 8,800 7.800 6.800 11,900 11,000 10,300 ' 9,600 8,400 7,500 6,700 6,000 10,400 9,700 9,000 8,400 7,400 6.500 5.800 4.800 9,100 8.400 7,900 7.400 6.300 5,700 4,500 4.300 8,200 7,600 7,100 R.700 5,700 5,100 4.500 3.500 17,000 15.900 14.900 13.900 21,800 20,000 18,400 17,000 28,000 26,000 24,200 22,400 12,400 11,100 9.900 9,000 14,800 13,900 13,000 12,200 14,600 12,800 11,200 10,000 18,000 16,400 15.200 14.200 20,000 17.600 15.600 13.600 23,900 22,000 20,600 19,200 10,800 9,600 8.500 7.500 13,000 12,100 11,300 10,600 12,400 10,800 9.400 8.400 . 15.400 14.400 13.400 12.400 16,800 15.000 13,400 12.000 21,700 19,400 18,000 16,800 9.400 8,300 , 7.400 6,500 11,400 . 10,500 9,800 9,200 10,800 9,400 8,200 7,200 13.600 12.600 11,600 11,000 14,800 13,000 11,600 9,600 18,200 16,800 15.800 14.800 8,100 7,200 5,800 5.400 10,300 9,500 8,900 8,300 9.600 8,400 6,800 6.600 12,200 11,400 10,600 10,000 12,600 11,400 9,000 8,600 16.400 15.200 14.200 13.400 7,400 6,500 5,800 4,700 8,800 7.800 6.800 5,600 11,400 10,200 9.000 7.000 Col. j 70.000 65.000 60,500 57.000 50.000 44.000 39.000 34,000. 59.500 55.000 51.500 48.000 . 42.000 37.500 33.500 30.000 52,200 48,400 45.300 42.300 37.000 32.500 29.000 24.000 45.500 42.000 39,600 36,800 32.200 28.200 22,800 21,500 41,000 38.300 35.800 33,400 29,000 25.800 22.800 17,500 Stacks1* No. Rectangular Branch Size Number of Joist Spaces and Registers: Low Wall, High Wall or Baseboard: Registers: Floor, Warm Air Registers: Floor, Return Air Trunk Duct Increase, Inches 41 1 10x3% 3x8 5 1 at 10x6 8x10 6x10 4x14 l 42 10x314 4x8 6 2 at 3 10x6 8x10 6x10 or 4xl4 2 43 1 22x3% 5x8 7 1 at 12x6 44 1 14x3% 6x8 8 1 at 14x6 9x12 6x12 or 6x14 3 9x12 longer 6x14 1 4 45 2 10x3% 8x8 . 9 1 at 6 or 2 at 3 (2)10x6 46 12x3% 10x8 10 1 at 7 or 2 at 4 (2)12x6 47 15x8 ' 12 1 at 9 or 2 at 5 (1)24x6 10x12 (1)30x6 __________ - 6x30 6x30 .1 51 7 * Uninsulated ducts in heated spaces and insuiaieu (1U914 1U UUUOanou uyuwa. b Note: For return air a 14x3% in. stud space may be usedjinstead of 10x3% in. stack'. Where 12x3% ioor 14x3% in. stack is required, a 14x3% in. stud space may be used only when inside of stud space is smooth and without protruding plaster keys. The number of joist spaces for combination 47 is based on 2x8 joists. One space may be used with 2x10 joists. ` The limiting factor for a duct combination is the stack capacity. Forced Warm Air Systems 481 This simplified method is applicable to structures having heat losses not in excess of approximately 120,000 Btu per hour. The capacities shown in Tables 1 and 2 are based upon the most reliable data pertaining to fric tion losses and temperature drops in ducts. They are also based upon a 100 deg temperature rise of the air, and a static pressure available for overcoming friction losses in the external duct system alone of 0.20 in. water gage. The use of this method assumes that the fan in the fanfurnace assembly will be capable not only of overcoming the resistance of the external duct system alone, but also the resistances imposed by the blower inlet, the filter, and the furnace casing. Tables 1 and 2 are applicable for the selection of both warm air and return air branches. A depth of 8 in. has been adopted as the standard for trunk ducts, and where a branch joins the trunk the required increase shown in the last line of Table 1 or Table 2 refers to an 8-in. trunk duct. Where two branches form a trunk the farthest branch is considered to be the trunk and its equivalent width (for 8-in. depth) is increased as required. DESIGN PROCEDURE FOR LARGE SYSTEMS4 For buildings having a heat loss in excess of 120,000 Btu per hour, the design procedure6 given in Manual 9 of the NWAH & ACA, may be used. Work sheets 9a, 9b, and 9c are available to simplify calculations.4 The procedure consists of: 1. Calculation of design heat losses from individual spaces in the structure. The calculation of these losses is explained in Chapter 12. 2. Location of registers and return intakes on floor plan, showing types of registers, with distance from register to opposite wall and deflection of registers desired. 3. Laying out a proposed duct system for both warm air and return air sides of the system, and including details of types of fittings and the actual and equivalent lengths of each branch line from bonnet to register, without sizes. (See Fig. 4, Groups 1 through 6, for equivalent length of fittings.) 4. Determination of bonnet temperature. If the rating sheet for a furnace-blower unit specifies a fixed value of bonnet tem perature, locate this temperature in the left-hand column of Table 3. If not speci fied, use the following procedure: Use Table 3 for buildings having a heat loss between 120,000 and 350,000 Btu per hr, or Table 4 for buildings having a heat loss greater than 350,000 Btu per hr. Select shortest actual length, including vertical risers and read downward in nearest column in Tables 3 or 4 until lower heavy diagonal line is reached, but do not cross line. Run horizontally to first column of table and note bonnet temperature. Also select longest actual length including vertical risers, and read downward in nearest column in Tables 3 or 4 until upper heavy diagonal line is just crossed. Run horizontally to left to obtain value for oonnef temperature in first column. Select as the design bonfiet temperature any value between these two limits. 5. Determination of air vojume to be delivered through each register and the respective register air temperatures. Using Tables 3 or 4 and the design bonnet temperature selected, find the values of cfm per 1000 Btu for each duct length, and the corresponding register temperature. 6. Selection of register sizes and pressure losses to produce necessary throw, for the air volumes handled. Use Tables 5 or 6 to obtain required free area and pressure loss of register. X 482 CHAPTER 20 GROUP 1 ------------------- WARM AIR AND RETURN AIR BONNET OR PLENUM. EQUIVALENT LENGTHS BASED ON^fT DEPTH OF DUCT 1956 Guide Forced Warm Air Systems G8QUP 4. BOOT FITTINGS - FROM BRANCH TO STACK* 483 RETURN MR ONLY I NOT RCCOMMCNOCO GROUP 2 ANGLES AND ELBOWS FOR TRUNK DUCTS. INSIDE RADIUS % WIDTH OF DUCT. -= ' " EQUIVALEN T LENGTHS BASED ON 8' DEPTH OF DUCT ~ WlOTM TO i5 - 5 to. f. It TO 27 iO ' 20 TO 92-S WIOTM' TO 11 IO CO. FT. 12 TO 21 IS. 22 TO 27 20 20 TO 32*25 WIDTH' 4 TO C 20 CO. r. 7 TO M 40 12 TO IS - 50 16 TO Z> - 75 22 TO 27 100^, 20 TO 32 * 125 4 TO H 15 CO. FT. *2 TO 21 a 20 22 TO 27m 25 20 TO 92 > 40 NV GBQUg_J. TRUNK DUCT TAKE-OFFS. CO. 0-3* THROAT RADIUS NOTE: T - NO RADIUS Q NOT RECOMMENDED Fig. 4. Equivalent Length op Fittings GROUP 5.. STACK ANGLES, ELBOWS. AND COMBINATIONS A AND 6 HAVE 3* THROAT RADIUS D AND E HAVE S" THROAT RAQlUS CROUP 6. RETURN AIR SO to. rx . ' . R-A. GRILL AND FITTING. P.A. GRILL TO STUD SPACE. R.A. GRILL ONLY. FLOOR GRILL TO LINER Fig. 4. Equivalent Length of Fittings (Continued) 7. Design of duct system. A. Warm air branches. . . a. Use Table 7 to select maximum bonnet pressure usually required for the trunk carrying the maximum volume of air (cfm). If the mm-iTM..TM 484 CHAPTER 20 1956 Guide; GROUP 7. REGISTERS (INCLUDING LOSSES IN STACKHEAD AND VELOCITY PRESSURE). 25EQ.PT. FL. REC. S BOX ONLY Table 4A. Equivalent Length, fob Registers Deflection Angie A 15 22* 30 Baseboard, High or Low Sidewall Registers '______ Eq. Ft. 35 Floor Registers with Box only For 2-wayde8ection registers, sdd the vertical and horizontal deflection az^es tethMd multiply by OX sSleot closest angleTM in Table 4A. For difluser type registers see manufactures catalogs. Fig. 4 Equivalent Length of Fittings (Concluded) bonnet pressure is not' high enough to accommodate the pressure loss through the registers, use a higher bonnet pressure. If the register pre- sure is critically large, it may be necessary to reduce it by either using two registers in place of one, or using smaller deflection angles. ; b. Obtain, actual duct loss by subtracting total register pressure loss, as , determined from Tables 5 or 6, from maximum bonnet pressure. ' c. Obtain the pressure drop in each duct per 100 ft by use of Table 8. ; . d. Determine duct sizeby meansof air friction chart (suchasFig. 1, or Fig. 2, : Chapter 32), volume (cfm), and pressure drop per 100 ft of duct. ' B. Return air branches. a. Select a low value of actual duct loss obtained from step b under item A for the suction loss of return duct system. b. Proceed in sizing return air branches by the same method described for : the warm air branches. .; C. Trunk ducts for warm air and return air sides of system. a. Add air volumes of branches to be handled by each trunk duet. , 1 b. The friction loss per 100 ft of trunk duct is determined by taking the smaller of the two values for friction loss for the two ducts meeting at the junction. c. Determine trunk duct size by using an air friction chart, volume (cfm)>, and pressure drop per 100 ft of trunk duct. ` . 8. Selection of Blower. " _ A. Determine total cfm air delivery (the sum of all branch cfm values). ' B. Determine static pressure requirement. a. For furnace-blower combination units it is the sum of bonnet pressure and suction pressure. . b. For blowers separately selected from the furnace it is the sum of bonnet pressure, suction pressure, filter loss, casing loss, losses through air wash ers, coils, and other devices. 9. Selection of Furnace. A. Determine register delivery (the sum of loom Btu losses). B. Determine bonnet capacity. Bonnet capacity = (total cfm) X (temperature rise) X 1.089. C. Determine allowance for pick-up load. For buildings which are heated in termittently, such as churches and auditoriums, it is customary to add from 10 to 25 percent extra furnace capacity for wanning of the structure. Forced Warm Air Systems 485 1 230 11 87 4 2 .7 90 3 8 .6 93 3 4 .6 97 . 3 0 .5 100 ,2 8 .0 S D cKB>* 3 a Q,, E to HO 08Q _ <= to n <h * a to 8 B S* sp HS HS 8|fc <to S' a ~<5 ~ P te ^ 03$ - * HH-S to$S a^ | |-2 z| S mo ISs ^ O5 z o a A H< '5 | o85< c* Si 883 a Oi 00 CO . oooet>5 s O CO co co 00 03 CO eo H* CO .co CO .pH t> 03 CO CM co 03 , 03 tO pH co - co r- o CO : CO eo 88 to 00 OJ to SS OO 00 CM is co 2S5 CM ^ 28 |2 j as j 28 CO 28 | 2S I1 <2'* 8* CM O -- CM 2 to -- CM tol f 28 | 28 CO -- CM 28 -- CM 28 CM 28 is CM * pH -- CM eo 3 s 110 2 2 .1 112 2 1 .1 ---- HC3 f'. Ss eo*^ ss ns o Ss ns ` *^ -- -- o -- Ss CM CO CO -- ?M ^tO -- ---- 3s *H -- S8 PH pH S8 j 200 j 210 a OO 03 CO to CM C3 CO 00 00 CM . O -- CM N oeo -- CM -- CM -- goo" 88 er- -- 03 CO pH co pH' c.o 2S _ CO is O CM -- CM co1''--N .o ---22 pH pH CM CM CM CM > CM s CM 03 CO o" o CO TJ4* 03 CO CO o 8S ow 0-0 co 28 00 CM 88 28 p*. 2S is ro^i 2S 2S N* 28 2S O^. -* CM -- CM s CM ^ H -- CM --s 2 eo t-- -- H pH ^ -- OO ^H pH pH pH 88 pH ph CM 00 CM pH pH CO ---- CM pH -- H*4 c -- pH rco -- hH T#4 00 CM -- PH -- p-H eo eo CO -- pH ^ eo-*4 CM co pH pH CO W*4; ---- _eq4)l. CO t#4 ---- 9 pH pH o 03 CO 2S CM ^ -- CM 00 -- 00 F4 iH a" H PH 00 CM ---- eo-<j4 _CM g^4 -- pH o CO is g _ ^ p-4 pH pH eo N CO -4*4 pH pH ^feo pH pH Cw -- PH 88 CO .22 -- CM ^ -- o is c5o -- PH T* T~<co pH pH pH pH CM 4J4 CO PH CM oot 1 o GoO No <o0 oQ o eoo oO o "ft. \ Z 03 00 CM S85 *>! 28 o'-1* 28 to CM ssCO^ Siocf"! 2S O 00 * -- ---- sS -- CO -- --* Fl -- CM S ---- o! CO pH pH co PcOH00 co^ Nco 5 ---- O CO S4N is is *^ -- CM CM ' -- CM eo N -- . r~ -- 00 CM 00 s" ---- CM to _ CM --2 co ---- tP . CO "4 N* eo ^ -- pH CM * co ^ pH H ts CM ^ co _CM ^ CO pH eo "4*4 CO pH pH o2 CM pH pH ^CM CO CM co 3* --4 CM is a* -- d --, 00 2S 2^ -- CM 00 -4 _ ^QO to Sto to a3CM tc 2-- o co io co uo . eo to h* CO ^ o. Tj* N o> rt* CM eo **eo eo CM CM OO to * ^ 4 -- si_ D I O ] CM I -- h. P-4 CO pH 00 o . -- pH CO Ht4 CO N ^4 CM CM CM CO CM ,, H to CM ---- CM -- pH -- OO -- si pH -- _ So 88 -- PH N r- to 0 PH pH --s eo pH -- H So o pH -- t- . -- c- pH H 3 CO CO -- ss| cm 00 -- T4 H4 pH PH eo 03 5 06 B o. . a-- I sa3 a 3 *. s 486 CHAPTER 20 1956 Guide S e <=> 5 -c o 110 1 2 2 .1 ! 114 1 2 0 .3 : 118 : 1 9 .0 : 128 1 6 .4 3 8 13 5 8 eo eo - 09 : C4 cd IO 09 N ^H eo io 'CN4 . CO H C9 to pH pH o _ o 09 05 ph t-. CO eo C4 pH - CO tpH 05 cO -- - 09 CO pH pH 05 09 O pH 09 . o H H CO 05 H H* 2 00 . . <o 2 t-p 09 pH CO co pH pH eo * CO co sio - e N' id iO eo ' .h* pH pH pH e 3 g 3 8: . eo pH ' 05 H 09 00 2 pH pH 3 oo 09 pH . eo CO pH co pH id 00 .CO pH hJ< _ s2 CO s' 00 pH pH . CD 8 05 S3 pH 2 05 . 03 r 0 : 3 Hjl eo io . CO pH pH pH ' 3pH 3 ,8 2 2 . tp C5 . CO 1 SI 1 <S -* CO pH - 09 pH - ` H I pH <o <d pH i 09 eo iO pH . pH cd pH <P Hji 09 pH pH eo pH o . CO * C9 CO pH . .. 8 -. cd pH . H pL zt^ P- ; -pH 1^ Lc3 r.PH ^ cd pH T}4 . "! co . ip 0e5o . : pH pH pH cd ^H 1 hph CO . 8 05 *-\ cOu C*`- pH 05 1 . O CO CO pH 1 *H 05 iH ^ to CO pH 00 ^ pH pH cd pH ^ * 2 .o g CO pH 05 S3 CO Is* CO 09 io g 04 co eo *o ^ co h* pH IO eo HP H 09 . 05 pH tp CO . CO c$ 2 ?3 ed eo o 3' to \ eo Jo 09' o S3 O0 o ^' . 09 CO . CO . SS- o o 2 - 3. ' 8 2 c 8 cO * C4 CO <o No E5 .. co S S5 cO s o eo % o. iO oN co io - eo V eo io CeoO 00- ! 05 co ; 04 CO CO Si <d . H* 8 . 05 C4 eo ev co rd eo eo co 0 - 05 IO CO ^ CO P-H 05 CO pH ( h* CO ^ PH 09 * ^. rH 05 eo eo = ^ pH co pH ! IO * eo p-H CO* pH 05 o CO - IO . CO CO 00 io co * Hi* eo C9 eo pH H* eo pH co eo . 2 , *H eo H IO H O iO 09 10 pH IO 00 *0 co- pH H io pH pH CO eo pH. -* IO 2 O .' t-^ H IO o CO IO H .09 09 eo 10 pH pH 05 IO C9 io pH cO CO 04 2 CO 09 pH o" 04 CO pH 2 : "V 09 ' iO * . ^ ^ co . o ^ pH 5 pH - IO eo pH 8 09 ! eo g pH C5 C9 IO pH ' CO * 09 S pH ` eo . pH C9 ' tO Ci 09 pH . 5 2 pH 8 09 pH to 3 pH CO . PH o 09 . pH *H CO * :3 eo N to .- -H pH o 3 oco- pH pH r- o io . S 09 pH co .** 09 .pH T- * io 09 eo IO pH to IO 09 09 H 00 . pH _ o IO pH 09 C9 - tO pH pH pH _ IO to o t oo to . pH pH 09 ^ t- s pH pH oo oo N pH o0o9 C O* pH 'rf IO :pH ISO o to . pH s - 09 pH t-- "2-h ^I*. pH pH 2 pH ' ptOs to pH 00* O- CO :^H . to o tPH OtCp pH 'CO . o pH ; O' * N 00 '2 ,05 88 !*H |p 00 . 09 pH pH pH s I cC*oO . $>'**>- . CO Tf CO cs pH pH H H ' ' CO 00 IO pH co pH No H 0t-- pH . 50$0 pH eo* to 05 PH 00 00 A 3 >. hmeswl H It & CO IO oi 3 pH 8 o pH H H pH pH pH ** o pH pH 8 to * o.> ss2ZO (S Forced Warm Air Systems 487 488 CHAPTER 20 1956 Guide Table 6. Determination op Free Area and Total Pressure Loss of Register for No Deflection of AiR*'b'c'd'"'' Register Free Air in Square Inches (Upper value in each group) Pressure Loss in Inches of Water Column (Lower value in each group) CFM Distance from Register to Opposite Wall 19-21122-24125-27128-30131-34135-39 | 40-49 | 50-59 60-69 igo*-209 J : 62 47 37 30 24 18 0.02 0.03 0.04 0.06 0.09 0.15 CFM 660-699 Distance pbom Register to Opposite Wall 35-39140-49150-59 | 60-69 1 70-79 180-89 A B 210 143 95 69 49 0.02 0.03 0.07 0.12 0.22 210-229 76 58 45 36 29 22 0.02 0.02 0.04 0.05 0.08 0.12 700-739 236 160 107 77 54 0.02 0.03 0.06 0.11 0.21 230-249 69 53 43 34 26 0.02 0.03 0.04 0.07 0.11 740-779 262 179 119 86 61 0.02 0.03 0.06 0.10 0.18 250-269 81 63 50 40 31 21 0.02 0.03 0.04 0.06 0.09 0.18 780-819 291 198 132 95 67 0.02 0.03 0.05 0.09 0.17 270-299 93 73 69 47 36 24 0.02 0.02 0.03 0.05 0.08 0.16 820-859 320 218 145 105 74 0.02 0.03 0.05 0.08 0.15 300-339 95 77 61 46 32 0.02 0.03 0.04 0.06 0.12 . 860-899 352 240 160 115 81 0.02 0.02 0.04 0.08 0.14 340-379 129 97 77 59 40 0.02 0.02 0.03 0.05 0.10 900-939 385 262 175 126 89 0.01 0.02 0.04 0.07 0.13 3SO-419 119 95 73 50 0.02 0.03 0.04 0.08 940-979 419 285 190 137 97 0.01 0.02 0.04 0.07 0.12 420-459 149 114 88 60 0.02 0.08 0.04 0.07 980-1019 455 309 206 0.01 0.02 0.04 148 105 0.06 0.11 460-499 171 136 105 71 0.02 0.02 0.03 0.06 1020-1059 493 335 223 0.01 0.02 0.03 161 113 0.06 0.11 500-539 160 123 84 0.02 0.03 0.05 1060-1099 530 361 241 173 123 0.01 0.02 0.03 0.06 0.10 540-579 186 143 97 0.02 0.02 0.05 65 47 0.09 0.17 1100-1139 571 388 258 186 132 93 0.01 0.02 0.03 0.05 0.09 0.17 580-619 213 164 0.02 0.02 111 74 54 0.04 0.08 0.15 1140-1179 416 277 199 141 100 0.02 0.03 0.05 0.08 0.16 620-659 180 127 85 61 0.02 0.04 0.07 0.14 AB a If register selected based on distance from register to oppo site wall is unsatisfactory on account of size or pressure lo63, it is permissible to shift one or more spaces left or right in the tables to obtain a more suitable register. If requirements fall in blank space, select two registers in place of one and divide CFM capac ity between the two registers. b Total pressure (static plus velocity) loss is based on FLAT FACE ADJUSTABLE BAR TYPE and does NOT include stackhead. ` c Values on the right of line A and A'sbould not be used in ap plications such as churches, auditoriums, and concert halls. d Values on right of line B and B1 should not be used in ap plications such as residential work, motion picture theaters, court rooms and schools. For floor and baseboard registers where a velocity of ap^ 144 prorimately 300 FPM is used, the free,area * ^ or ap 1180-1219 1220-1259 1260-1299 1300-1339 1340-1379 1380-1419 1420-1459 proximately, Assume a pressure loss of .01. For any volume under 190 CFM use Table 5. 1460-1500 446 297 214 151 107 0.02 0.03 0.04 0.08 0.15 476 317 228 161 116 0.02 0.03 0.04 0.07 0.14 507 338 243 172 122 0.01 0.02 0.04 0.07 0.13 539 359 0.01 0.02 258 0.04 183 0.07 ISO 0.13 382 0.02 274* 0.04 195 0.07 138 0.13 403 290 206 146. 0.02 0.03 0.06 o.i? 308 0.03 218 0.06 155 0.10 324 0.03 230 0.06 163 0.W Forced Warm Air Systems Table 7. Suggested Bonnet Pressure Inches of water . 489 Total CFM Through Any One Duct 800-1000 1000-1200 1200-1800 1800-2400 2400 to 3500 Suggested Bonnet Pressure In. Water.' 0.10 0.10 0.10 0.13 0.14 Total CFM Through Any One Duct 3500 to 5000 5000 to 7500 . 7500 to 10,000 10,000 to 12,000 12,000 to 14,000 Suggested Bonnet Pressure In. Water 0.15 0.25 0.375 0.500 0.750 Table 8. Pressure Drop in Duct Inches of Water per 100 Feet of Duct Length Equtva- Length of Duct (Ft) 0.04 0.05 0.06 0.07 Total Pressure Drop in Duct (In. of Water) 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.20 35-44 45-54 55-54 65-74 0.10 0.08 0.07 0.06 0.13 0.10 0.08 0.07 0.15 0.12 0.10 0.09 0.18 0.14 0.12 0.10 0.20 0.16 0.13 0.11 0.23 0.18 0.15 0.13 0.25 0.20 0.17 0.14 0.28 0.22 0.18 0.16 0.30 0.24 0.20 0.17 0.33 0.26 0.22 0.19 0.35 0.28 0.23 0.20 0.38 0.36 0.25 0.21 0.40 0.32 0.27 0.23 0.43 0.34 0.28 0.24 0.45 0.36 0.30 0.2A 0.48 0.38 0.32 0.28 0.50 0.40 0.33 0.29 75-84 85-94 95-104 105-114 0~05 0.05 0.04 0.04 0.06 0.06 0.05 0.05 0.08 0.07 0.06 0.05 0.09 0.08 0.07 0.06 0.10 0.09 0.08 0.07 0.11 0.10 0.09 0.08 0.13 0.11 0.10 0.09 0.14 0.12 0.11 0.10 0.15 0.13 0.12 0.11 0.16 0.14 0.13 0.12 0.18 0.16 0.14 0.13 0.19 0.17 0.15 0.14 0.20 0.18 0.16 0.15 0.21 0.19 0.17 0.15 0.23 0.20 0.18 0.16 0.24 0.19 0.17 0.25 0.20 0.18 115-129 130-149 150-169 170-189 0.03 0.03 0.03 0.02 0.04 0.04 0.03 0.03 0.05 0.04 0.04 0.03 0.06 0.05 0.04 0.04 0.07 0.06 0.05 0.04 0.08 0.07 0.06 0.05 0.08 0.07 0.06 0.06 0.09 0.08 0.07 0.06 0.10 0.09 0.08 0.07 0.11 0.12 0.09 0.10 0.08 ,0.0ft 0.07 0.08 0.12 0.11 0.09 0.08 0.13 0.11 0.10 0.09 0.14 0.12 0.11 0.09 0.15 0.13 0.11 0.10 0.16 0.14 0.12 0.11 0.11 190-214 215-239 240-264 265-289 0.02 0.02 0.02 0.01 0.03 0.02 0.02 0.02 0.03 0.03 0.02 0.02 0.04 0.03 0.03 0.03 0.04 0.04 0.03 0.03 0.05 0.04 0.04 0.03 0.05 0.05 0.04 0.04 0.06 0.05 0.04 0.04 0.06 0.05 0.05 0.04 0.07 0.06 0.05 0.05 0.07 0.06 ft.Ofi 0.05 0.08 0.07 0.06 0.05 0.08 0.07 0.06 0.06 0.09 0.08 0.07 0.06 0.09 0.08 0.07 0.07 0.10 0.09 0.08 0.07 0.10 0.09 0.08 0.07 290-324 3a5-3/ 4 375-424 425-474 0.01 .0.01 0.01 0.01 0.02 0.02 0.01 0.01 0.02 0.02 0.02 0.01 0.03 0.03 0.02 0.02 0.02 0.02 0.02 0.02 0.03 0.03 0.02 0.02 0.03 0.03 0.03 0.03 0.04 0.03 0.03 0.03 0.04 0.04 0.03 0.04 0.03 0.03 0.03 0.03 0.05 0.04 0.04 0.03 0.05 0.04 0.04 0.03 0,05 O.Ofi 0.05 0.05 0.04 0.04 0.04 0.04 0.06 0.05 0.05 0.04 0.06 0.05 0.05 0.04 0.07 0.06 0.05 0.05 475-524 525-5/4 575-625 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.01 0.01 0.02 0.02 0.01 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.03 0.02 0.02 0.03 0.03 0.03 0.03 .02 0.03 0 03 0.03 0.03 0.03 0.03 0.03 0.04 0.03 0.03 0.04 0.03 0.03 0.04 0.04 0.03 Equiva- Length of Duct (Ft) 0.21 0.22 0.23 0.24 Total Pressure Drop in Duct (In. of Water] 0.25 0.26 0.27 0.28 0.29 0.30 0.32 0.34 0.36 0.38 0.40 0.45 0.50 35-44 45-54 55-64 65-74 75-84 85-94 95-104 105-114 115-129 130-149 190-214 290-324 375-424 475-524 525-574 5/5--025 0.53 0.55 0.58 0.60 0.63 0.65 0.68 0.70 0.73 0.75 0.80 0.85 0.90 0.95 1.00 1.13 1.25 0.42 0.44 0.46 0.48 0.50 0.52 0.54 0.56 0.58 0.60 0.64 O.fifi 0.72 0.76 0.80 0.90 1.00 0.35 0.37 0.39 0.40 0.42 0.43 0.46 0.47 0.48 0.50 0.53 0.57 0.60 0.64 0.67 0.75 0.83 0.30 0.32 0.33 0.34 0.36 0.37 0.39 0.40 0.42 0.43 0.46 0.49 0.52 0.54 0.57 0.64 0.72 0.26 0.23 0.28 0.25 0.29 0.26 0.30 0.27 0.31 0.28 0.33 0.29 0.34 0.30 0.35 0.31 0.36 0.32 0.38 0.33 0.40 0.36 0.43 0.38 0.45 0.40 0.48 0.42 0.50 0.45 0.56 0.50 0.63 0.56 0.21 0.19 0.22 0.20 0.23 0.21 0.24 0.22 0.25 0.23 0.26 0.24 0.27 0.25 0.28 0.26 0.29 0.27 0.30 0.28 0.32 0.29 0.33 0.31 0.36 0.33 0.38 0.35 0.40 0.37 0.45 0.41 0.50 0.46 0.18 0.18 0.19 0.20 0.21 0.22 0.23 0.23 0.24 0.25 0.27 0.28 0.30 0.32 0.33 0.38 0.47 0.15 0.16 0.16 0.17 0.18 0.19 0.19 0.20 0.21 0.21 0.23 0.24 0.26 0.27 0.29 0.32 0.36 0.13 0.14 0.14 0.15 0.16 0.16 0.17 0.18 0.18 0.19 0.20 0.21 0.23 0.24 0.25 0.28 0.31 0.12 0.12 0.13 0.13 0.14 0.15 0.15 0.16 0.16 0.17 0.18 0.19 0.20 0.21 0.22 0.25 0.28 0.11 0.11 0.12 0.12 0.13 0.13 0.14 0.14 0.15 0.15 0.16 0.17 0.18 0.19 0.20 0.23 0.25 0.09 U.1U 0.10 0.11 0.11 0.12 0.12 0.13 0.13 0.13 0.14 0.15 0.16 0.17 0.18 0.20 0.22 0.08 0.09 0.09 0.10 0.10 0.10 0.11 0.11 0.12 0.12 0.13 0.14 0.15 0.15 0.16 0.18 0.20 0.08 0.08 0.08 0.09 0.09 0.10 0.10 0.10 0.11 0.11 0.12 0.12 0.13 0.14 0.15 0.16 0.18 0.07 0.07 0.08 0.08 6.08 0.09 O.rffl 0.09 0.10 0.10 0.11 0.11 0.12 0.13 0.13 0.15 0.17 0.06 0.06 0.07 0.07 0.07 0.08 0.08 0.08 0.09 0.09 0.09 0.10 0.10 0.11 0.11 0.13 0.14 0.05 0.06 0.06 0.06 0.06 0.07 0.07 0.07 0.08 0.08 0.08 0.09 0.09 0.09 0.10 0.11 0.13 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.06 0.07 0.07 0.07 0.08 0.08 0.09 0.09 0.10 0.11 0.04 0.04 0.05 0.05 0.05 0.05 0.05 0.06 0.06 0.06 0.06 0.07 0.07 0.08 0.08 0.09 0.10 0.04 0.04 0.04 0.04 0.05 0.05 0.05 0.05 0.05 0.06 0.06 0.07 0.07 0.07 0.07 0.08 0.09 0.04 0.04 0.04 0.04 0.04 0.04 0.05 0.05 0.05 0.05 0.05 0.06 0,06 0.00 0.07 0.08 0.08 490 CHAPTER 20 1956 Guide AUTOMATIC CONTROLS Air stratification, high bonnet temperatures, excessive! flue gas tempera tures, and heat overrun or lag in a properly designed system, can be largely eliminated through proper care in the planning and installation of the con trol system.6 Best results are obtained when the fan is operated as con tinuously as possible, coupled with frequent, short cycles of burner opera tion. Controls usually employed are: 1. A room thermostat located in the occupied space at a point where there is good air circulation and where the temperature is representative of the area being con trolled. It is the operating control which initiates the starting and stopping of the burner. It is frequently of the timed, two-position type. Refer to Chapter 39 for more information on types of room thermostats. 2. A fan thermostat located in the bonnet of the furnace to start the fan at a bon net temperature between 110 and 130 F and stop the fan at about 15 deg below the cut-in point. The lower settings are used for high sidewall register installations and the higher settings for baseboard register installations. For most satisfactory per formance these settings should be as low as is feasible without resulting in drafts. 3. A high limit control, also in the bonnet of the furnace, to stop the burner inde pendently of the room thermostat if the air temperature exceeds 175 F. The fan thermostat and high limit control are sometimes combined into a single unit. 4. A humidistal to regulate the moisture supplied to the rooms on systems which are equipped with humidifying means. This may be of the room type, usually located adjacent to the room thermostat, or it may be of the insertion type located in the main return air duct. 5. Primary and limit controls for the various types of gas burners, oil burners and coal burners (stokers) should be provided as required, and are discussed in Chapter 39. ADJUSTMENT OF SYSTEM More even room temperatures will result if the controls are adjusted to produce long period fan operation. This is accomplished in automaticallyfired forced warm air heating systems when the control arrangement is of the type where the room thermostat controls the fire, and the blower con trol (fan switch) controls the blower operation This procedure as out lined in detail in Manual 6 of the National Warm Air Heating and Air Con ditioning Association, is as follows:7 1. Adjust the fuel input in proper relation to the heat loss of the structure. 2. Determine the temperature rise through the furnace. 3. Adjust the air volume to produce a temperature rise through the furnace of about 100 deg. 4. If adjustable, set the fan switch differential to a minimum of about 15 deg. 5. Adjust the fan switch cut-out point as low as practicable. 6. Balance the system by adjusting dampers to produce even temperature distri bution between rooms. 7. Set the room thermostat at the desired room temperature. Close control of room temperature is facilitated by the use of a room thermostat having a narrow operating differential. The heat anticipating thermostat is an example of such a device. WARM AIR CEILING PANEL SYSTEMS Warm air ceiling panel heating systems utilize a false ceiling suspended 3)4 in. from the ceiling joists which have previously been covered on the bottom with sheets of plasterboard. Special hangers are used to suspend Forced Warm Air Systems 491 the false ceiling or heating panel from the joists. Steel supporting rods are installed through these hangers and metal lath is attached to the rods. The lath is then plastered to a thickness of % in., making a completely sealed air space above the ceiling. Warm air is delivered to this: sealed space through a standard warm air duct, installed in the usual manner. . The air is then circulated over the entire ceiling being guided by sheet-metal baffles. After the air has passed over the ceiling, it is returned to the fur nace through a return air duct for reheating. The system is closed, and no air is introduced into the heated space from the panel. (See also Chapter 24, Panel Heating.) Because a warm air ceiling panel system involves a different type of ceiling construction, its installation is practically limited to new construc tion. Only automatically-fired and thermostatically-controlled furnaceblower units may be used with this system. The standard automatic heating controls consisting of . a room thermostat* temperature limit con trol, blower control (fan switch), and primary control are all that are re- Fiq. 5. Cboss-section of Slab Constbcction Containing Perimeter Duct quired. While warm air ceiling panel heating has particular advantages in one-story utility room houses, it can be just as effectively installed in one- and two-story houses with basements. Complete design and installation procedure is given8 in Manual 7-A of the National Warm Air Heating and Air Conditioning Association. WARM AIR PERIMETER SYSTEMS Perimeter heating is a method of heating residential and commercial buildings, with or without basements, in which warm air is (a) conveyed under the floor to warm the floor surface and (b) introduced into the rooms, preferably under the windows, at or near the floor, and delivered upward in a. diffused pattern blanketing the outside walls. The return air is collected through one or more grilles located high on the interior sidewalls or in the ceiling. Suggested procedures'6 for the design and installation of warm air perimeter heating systems are given in Manuals 4 and 10 and in the ac companying work sheets" of the National Warm Air Heating and Air Con ditioning Association. The furnace may be either the down-flow or the conventional up-flow 492 CHAPTER 20 1956 Guide type. For basementless houses the down-flow type is preferred since it requires a minimum amount of floor area and ductwork, and eliminates the need for a duct to bring the warm air down from the top of the furnace, or a duct to bring the return air down to the blower inlet. Several arrangements of perimeter ducts may be used to heat slabs on ground construction, but the most common is the type having a complete loop of a continuous duct around the edge of the slab, supplied by radial feeders extending from the furnace sub-floor plenum to the perimeter duct. A schematic cross-section of the slab construction, with the perimeter duct installed, is shown in Fig. 5. The slab should be constructed on a well-drained site where drainage is away from the slab, and where there is no standing water at any time of the year. With slab construction, a suitable porous fill and a waterproof membrane as a moisture barrier beneath the slab are required by the Federal Housing Administration. They are highly necessary with warm air perimeter heating. Insulation must be placed between the edge of the slab and the foundation, and must extend completely around the slab to reduce the heat losses from the edge of the slab. Fig. 5 also shows many of the essential features of the slab and under-slab construction. SUMMER OPERATION During hot summer periods a slight cooling effect, may sometimes be obtained by the circulation of basement air through the system. This beneficial effect is due to both the increased air movement in the occupied spaces and the small reduction in dry-bulb temperature brought about by passing warm air over the cooler basement walls and floor. In areas of high prevailing dew points, however, this practice may cause objection able dampness to develop in the basement. Complete summer air conditioning can be readily combined with forced warm air systems either by using factory-built units incorporating both refrigeration and heating equipment, or in some cases by adapting sepa rate refrigeration equipment or well-water coils to existing warm air systems. A more complete treatment of residential summer air conditioning is given in Chapter 50. REFERENCES . 1A* 3Yardstick for Classifying Warm Air Winter Air Conditioning Systems (National Warm Air Healing and Air Conditioning Association, Manual 8, 1948). - '' * Performance of a Forced Warm-Air Heating System as Affected by Changes in Volume and Tempera ture of Air Recirculated, by A. P. Kratz and S. Konzo (A.S.H.V.E. Transactions, Vol. 48, 1942, p. 393). ' * Code and Manual for the Design and Installation of Warm Air Winter Air Conditioning Systems (Na tional Warm Air Heating and Air Conditioning Association, Manual 7, Fourth Edition, 1963). 4 Proposed Design Procedure for Large Mechanical Warm Air Heating Systems, by S. Konzo, R. J. Mar tin, D. 5. Levinson, and R. W. Roose (A.S.H.V.E- Transactions, Vol. 53, 1947, p. 177). * Code and Manual for the Design and Installation of Large Warm Air Winter Air Conditioning Systems (National Warm Air Heating and Air Conditioning Association, Manual 9, Fourth Edition, 1950). * Automatic Controls for Forced-Air Heating Systems, by S. Konzo and A. F. Hubbard (A.S.H.VJE. Transactions, VoL 40, 1934, p. 37). * ' Service Manual for Continuous Air Circulation Technicians (National Warm Air Heating and Air Con ditioning Association, Manual 6, First Edition, 1947). . * Code and Manual for the Design and Installation of Warm Air Ceiling Panel Systems (National Warm Air Heating and Air Conditioning Association, Manual 7-A, Third Edition, 1950). * Warm-Air Perimeter Heating (National Warm Air Heating and Air Conditioning Association, Manual , 4, Third Edition, 1955). 10 Small Pipe Warm Air Perimeter Heating (National Warm Air Heating and Air Conditioning Associa tion, Tentative Manual 10, Second Edition, 1953). 11 Work Sheets for Warm-Air Perimeter Systems (National Warm Air Heating and Air Conditioning Asso ciation, Forms 41s, 41b, 42, 43 and 45). CHAPTER 21 STEAM HEATING SYSTEMS Classification of Steam. Heating Systems by Types; One-pipe; Two-pipe,. Sub-atmospheric and Orifice Systems; Siring Piping for Steam Heating Systems; Pressure Reducing Valves; Boiler Connections; Condensate Return Pumps; Vacuum Heating Pumps; Traps; Drips; Con nections to Heating Units; Control Valves STEAM heating systems may be classified according to any one of, or combination of, the following features: (1) piping arrangement, ' (2) pressure or vacuum conditions obtained in operation, (3) method of returning condensate to the boiler. ' . 1. By Piping Arrangement. A steam heating system is known as a one-pipe system when a single main serves the dual purpose of supplying steam to the heating unit and conveying Condensate from it. Ordinarily, to each heating unit there is but one connection which.jnust serve as both the supply and the return, although separate supply and return connections may be used. '. A steam beating system is known as a two-pipe system when each heating unit is provided with two piping connections, and when steam and condensate flow in sepa rate mains and branches. Heating systems may also be described as up-flow or down-flow, depending on.the. direction of steam flow in the risers; and as a dry-return or a tset-return, depending on whether the condensate mains are above or below the water line of the boiler of con densate receiver. 2. By Pressure or Vacuum Conditions. Steam heating systems may also be classi fied as high pressure, low pressure, vapor, and vacuum systems, depending on the pressure conditions under which the system is designed to operate. A system is known as a high pressure system when the operating pressures employed' are above 15 psig; as a low pressure system when pressures vary from 0 to 15 psig; as a vapor system when the system operates under both vacuum and low pressure condi tions without the use of a vacuum pump; and as a vacuum system when the system operates under vacuum and low pressure conditions with the use of vacuum pump. When automatic controls are employed to vary the pressure conditions in the sys tem in accordance with oytside weather conditions, the system may be known as a sub-atmospheric, differential, or synchronized system. These latter classifications are proprietary designations. . When orifices are employed on the inlets to the heating units the system may be known as an orifice system. 3. By Method of Returning Condensate. When condensate is returned to the boiler by gravity, the system is known as a gravity return system. In this system all heat ing units must be elevated sufficiently above the water line of the boiler, so that the condensate can flow freely to the boiler. Elevation of the heating units above the water line must therefore be sufficient to overcome pressure drops due to flow, as well ss pressure differences due to operation. . . Referring to'Fig. 1 it will be noted that the boiler and wet-return form a U-shaped container; with the boiler steam pressure on the top ol the water at one end, and the steam main pressure on the top of the water at the other end. The difference between these two preppures is the pressure drop in the system, i.e., the friction and resistance to the flow of steam in passing from the boiler to the far end of the main, and the pressure reduction in consequence of the condensation occurring in the system. The water in the far end will rise sufficiently to overcome this difference in order to balance the pressures, and it will rise far enough to produce a flow through the return pipe and overcome the resistance of check valves, if installed. If a one-pipe steam system is designed, for example, for a total pressure drop of * pn, and utilizes a Hartford return connection instead of a check valve on the return, 493 494 CHAPTER 21 1956 Guide the rise in the water level at the far end of the return, due to the difference in steam pressure, would be } of 28 in. (28 in. head being equal to one pound per square inch), or 3} in. Adding 3 in. to overcome the resistance of the return main, and 6 in. as a factor of safety for heating up, gives 12} in. as the distance the bottom of the lowest part of the steam main and all heating units must be above the boiler water line. The same system, however, installed and sized for a total pressure drop of } psi, and with a check in the return, would require $ of 28 in., or 14 in. for the difference in steam pressure, 3 in. for the flow through the return, 4 in. to operate the check, and 6 in.'for k factor of safety, making a total of 27 in. as the required distance. Higher pressure drop would increase the distance accordingly. When conditions are such that condensate cannot be returned to the boiler by the action of gravity, and either traps or pumps must be employed, the system is known as a mechanical return systemThere are three general types of mechanical con densate return devices in common use: (a) the alternating return trap, (6) the con densate return pump, and (c) the vacuum return pump. In systems where pressure conditions in the system vary between that of a gravity return and a forced return system, a boiler return trap or alternating receiver is employed and the system may be known as an alternating return system. When condensate is pumped to the boiler under pressures of the atmosphere or above, the system is known as a condensate pump return system. ' . Steam pressure at BoQef steam pressure end of main Return water f-H+t Water fine of bcfler^- -j- fine Rise.water - Level -- return Vrrt7r777777777777V Fig. 1. Difference in Steam Pressure on Water in Boiler and at End . of Steam Main Fig. 2. Typical Two-Pipe Connections to Unit Heaters in One-Pipe Air Vent Systems - When condensate is pumped to the boiler under vacuum conditions, the system is known as a vacuum pump return system. In either the condensate or vacuum pump systems it is highly desirable to arrange for gravity flow to a receiver and to the pump. The pump then forces condensate into the boiler against its pressure. ONE-PIPE SYSTEMS One-pipe systems, as previously defined, are systems in which steam and condensate flow in the same pipe. Radiators and other heating units, in general, have only one piping connection from main to unit, although it is possible to employ two connections to the same main as indicated in Fig. 2. Unit heaters in one-pipe systems may also have separate connec tions to the wet-return. There are several variations in the piping arrangement of a one-pipe system as follows: - 1. Up-feed one-pipe systems where the radiators and other heating units are lo- cated above the supply mains. The mains in this instance convey both steam and condensate. Such a system is illustrated in Fig. 3. Typical connections to radiator or risers are illustrated in Fig. 4, and method of changing sizes of mains in Fig. 5. 2. Up-feed one-pipe systems where the radiators and other heating units are lo cated above the mains, and the mains are dripped at each radiator connection to a wet- Steam Heating Systems 495 Fig. 3. Typical Up-Feed Gravity One-Pipe Air-Vent System return, so that the steam main carries a minimum of the condensate. This system is illustrated in Fig. 6. Typical connections to radiators and risers are illustrated in Fig. 7. Up-feed systems are not recommended for systems higher than four stories. 3. Down-feed one-pipe systems, where the radiators and other heating units are located below the suppfy main. In this arrangement only risers and connections to heating units convey both steam and condensate, and both are flowing in the same direction. The steam main is kept relatively free of condensate by dripping through the drop risers. '. Each radiator or heating unit in a one-pipe system must be supplied with a thermostatic air valve which functions to relieve air from the heat ing unit under pressure, and to close when steam itself heats the thermo static element of the valve. To improve steam circulation in one-pipe systems quick-vent air valves should be provided at the ends and at intermediate points where the steam' main is brought to a higher elevation, or where dropped below the water line. It is desirable to install the air-vent valves about a foot ahead of the drips, as indicated in Fig. 6, to prevent possible damage to their mechanisms by water. Air valves are of two general types, the pressure and the vacuum types. The pressure type permits the inflow of atmospheric air to the system when the steam pressure in the system falls below atmospheric pressure. The vacuum type, which contains a small check valve, prevents the air from flowing back to the system and thereby maintains vacuum condi tions in the system, and a consequent evaporation or generation of steam Up to radiator or riser,. \. pitch. in. pet ft -3 ft approximately- Fig. 4. Typical Steam Runout whei Risers Are Not Dripped Fig. 5. Method of Changing Size of Steam Main when Runouts are Taken from Top 496 CHAPTER 21 1956 Guide Fig. 6. Typical Up-Feed Gravity One-Pipe Air-Vent System or vapor at sub-atmospheric pressures, and at consequent lower tempera tures. Systems which use vacuum valves are known as vapor or vacuum one-pipe systems. The vapor or vacuum systems will maintain a more uniform temperature condition than the pressure systems. Each heating unit in a one-pipe system may also be provided with a valve on the connection to the unit, although this is not essential except to shut the unit off in case it is not desired for heating. Valves on one- pipe systems must be either fully opened or fully closed. No throttling or modulating position can be maintained since, if-a valve is partially closed, condensate will not drain from the unit. This condition is dan gerous because it may create a low water condition in the boiler with con sequent burning or cracking of the boiler, or create a hazard due to the freezing of the water-logged heating unit itself. . TWO-PIPE SYSTEMS Two-pipe systems, as previously defined, are systems in which steam and condensate flow in separate pipes. Two-pipe systems may operate under high pressure, low pressure, vapor, or vacuum conditions. Either the up-flow or the down-flow arrangement of mains may be employed. Fig. 7. Typical Steam Runout where Risers are Dripped Steam Heating Systems 497 Two-Pipe High Pressure Systems Two-pipe high pressure systems operate at pressures above 15 psig, usually from 30 to 150 psig. They are usually used in large industrial type buildings, which are equipped with unit heaters or large built-up fan units, or in which high pressure steam is required for process work. Fig. 8 illustrates a typical high pressure system. Because of the high pressures and the great differential between steam and return mains, it is possible to locate returns above the heating units and lift the condensate to' these returns. The condensate can be flashed into steam in low pressure mains if any are available, or passed through an economizer heater before being dis charged to a vented receiver. It is, of course, necessary to provide for the elimination of air from high pressure systems, the same as in low pressure systems. GATE VALVEv. pipe coil / yFLOAT TRAP CHECK VALVE FROM HIGH ____ _ } Ly t^-GATE VALVE PRESSURE BOILER ---------------------------------------------(--------------------------1---- -- f* UNIT l HEATER ECK VALVE f^GATE VALVE CHECK VALVE float trap FLOAT TRAR/y r/ ^ATE VALVE AIR VENT / \ , * ,------------------------ \ n/i--r---------- kyl------- "X. ECONOMIZER Vfc L --------- --' \|---ill I VENT** --to" BOILER FINNED RADIATOR float trap \ CHECK VALVE RECEIVER Fig. 8. Typical High Pressure Heating System Return traps used on high pressure systems are usually of the bucket inverted bucket, float or impulse type. ` Two-Pipe Low Pressure Systems Low pressure systems operate at pressures of 0 to 15 psig. The piping arrangement of both up-feed and down-feed low pressure systems is iden tical with those of two-pipe vapor systems described in the following sec tion. The only difference between the two systems is in the type of air valve used. The air valves used in low pressure systems usually do not contain the check discs and hence, the system cannot operate under a . vacuum. The low pressure systems are not as popular as the vapor sys terns, because they have the disadvantage of not holding heat when the rate of steam generation is diminishing. They also have the disadvantage of corroding to a greater extent than vapor systems, due to the continued presence pf new air in the system, Low pressure systems have the advantage, however, of returning con densate to the boiler readily and not retaining it in the piping, as may be possible in vapor systems when the system pressure exceeds the operating 498 CHAPTER 21 1956 Guide Steam Heating Systems -S-T--E-A--M--M--AvIN-y S) 499 i! ! : -: '; i . range of the average vapor system. Fig. 9 illustrates a typical low pressure system with condensate pump. Two-Pipe Vapor Systems Two-pipe vapor systems operate at pressures varying from 20 in. vacuum or more (depending upon the tightness with which the system is assembled) to 15 psig without the use of a vacuum pump. . A typical two-pipe tip-feed vapor system is shown in Fig. 10, and a typical two-pipe down-feed system is illustrated in Fig. 11. The method of dripping drop risers in a down-feed system is illustrated in Fig- 12. Rndmtors discharge their condensate and air through thermostatic traps to the dry-return main. Air is eliminated, J .End of steam.mairt fip^L*X/ may be dripped - through trap into dry return Fig. 11. Typical Down-Feed Two-Pipe System when the system is under pressure, at the ends of the supply and return mains just before they drop to the wet return. The vent valves are of the float rather than float and thermostatic type since there should be no steam in the return main so long as the thermostatic traps on-the radia tors or convectors are operating properly. The float element of the valve closes the valve when, due to pressure differences, water rises to the point of overflow in the main. The vent valves are also provided with a small check disc which closes to prevent the inflow of air to the system when the pressure drops below atmospheric pressure. ; This enables the system to operate under vacuum, conditions at lower steam temperatures for a period of four to eight hours, depending on the tightness of the system. Vapor systems may also be provided with an automatic return trap for alternating receiver which automatically returns condensate to the .boiler when the boiler is steaming under pressure conditions which would prevent the return of condensate by gravity. The typical connections for an auto matic return trap are illustrated in Fig: 13. Bottom of_ steam drop I^ Wet return-^,_______________ ^___________ / Fig. 10. Typical Up-Feed Two-Pipe System with Automatic Return Trap* Proper pipini! connections are essential with special appliances for pressure equalizing and air elimination- --Connected to dry return J (where connected to wet return, drip trap shall be omitted) ^IQ* 12. Detail of Drip Gonnec- tions at Bottom of Down*1 Feed Steam Drop Fig. 13. Typical Connections fob . i . Automatic Return Trap . 500 CHAPTER 21 1956 Guide Each heating unit in a vapor system, as in all two-pipe systems, is pro vided with a graduated or modulating valve which permits the control of heat in the radiator by varying the opening of the valve. Two-Pipe Vacuum Systems Vacuum systems operate under conditions of both low pressure and vacuum, but employ the use of a vacuum pump to insure maintenance of sub-atmospheric pressures in the return piping for all operating conditions. The system may operate transiently with sub-atmospheric pressure in the supply piping during the time the rate of steam generation is equivalent to or less than the total connected load. . A typical two-pipe up-feed vacuum system is illustrated in Fig. 14, and a down-feed arrangement in Fig. 15. The return risers are connected in the basement into a common return main which slopes downward toward the vacuum pump. The vacuum Steam Heating Systems 501'. float control for the pump at the low point of the return main, located adjacent to the vacuum pump. - When the vertical lift is considerable, several lift fittings should be used' in steps as shown in Fig. 16. This permits a given lift to be secured with a somewhat lower vacuum than where the vertical distance is served by a single lift. Where several lifts are present in a given system at different locations, the lifting cannot occur until the entire system is filled with steam. A lift connection for location close to the pump, where the size may be above the commercial stock sizes, is shown in Fig. 17. It .is desirable that means be provided for manually draining the low point of the lift fittings to eliminate danger of freezing. ` TWO-PIPE SUB-ATMOSPHERIC SYSTEMS Sub-atmospheric systems are similar to vacuum systems but, in con trast, provide control of building temperature by variation of the heat pump withdraws the air and water from the system, separates the air from the water and expels it to atmosphere, and pumps the water back to the boiler or other receiver, which may be a feed-water heater or hot well. It is essential that no connection be madefrom the supply side to the return side at any point except through a trap. The desirable practice demands a return flowing to the vacuum pump by an uninterrupted downward slope. In some instances local conditions make it necessary to drop the return below the level of the vacuum pump inlet before the pump ean be reached. In such an event one of the advantages of the vacuum sys tem is the ability to raise the condensate to a considerable height, by the suction of the vacuum pump, by means of a lift connection or fitting in serted in the return. The height the condensate can be raised depends on the amount of vacuum maintained. It is preferable to limit lift con nections to a single lift at the vacuum pump. A still more preferable arrangement is the use of an accumulator tank, or receiver tank, with a output from the radiators. The radiator heat emission is controlled byvarying the pressure, temperature and specific volume of steam in circu lation. These systems differ from the ordinary vacuum system in that they maintain a controllable partial vacuum on both the supply and return sides of the system, instead of only on the return side. .. In the: vacuum system, steam pressure above that of the atmosphere exists in the supply mains and radiators practically at all times. In the sub-atmos pheric system, atmospheric pressure or higher exists in the steam supply piping and radiators only during severe weather. Under average winter temperature the steam is under partial vacuum which in mild weather May reach as high as 25 in. Hg, after which further reduction in heat output is obtained by restricting the quantity of steam. The rate of steam supply is controlled by a valve in the steam main or hy thermostatically controlling the rate of steam production in the boiler. 502 CHAPTER 21 1956 Guide, The control valve may be of the automatic modulating or floating type governed thermostatically from selected control points in/ the building, or it may be a special pressure reducing valve which wifi maintain the desired sub-atmospheric pressures by continuous flow into the heating main. In some systems radiator supply valves include adjustable orifices, or are equipped with regulating orifice plates.. .The sizes of orifices used are larger than for other types of orifice systems because, for equal radiator sizes, the volume flowing is larger. Orifices arer omitted on some systems. Radiator traps and drips are designed to.pperate at any pressure from 15 psig to 26 in, Hg. A vacuum pump capable of operating at high vacuum is pref erable to promote accuracy in the distribution of steam throughout the system, particularly in mild weather. This vacuum is partially selfinduced by the condensation of the steam in the system under conditions of . restricted supply used for reduction of the radiator heat emission. The returns must grade downward constantly and uninterruptedly from the radiator return outlets to the inlet of the receiver of the vacuum pump. Fig. 16. Method of. Making Lifts, on Vacuum Systems when Distance is Over 5 ft Lift at Vacuum Pump One radical difference between this and the ordinary vacuum system is that no lifts should be made in the return line, except at the vacuum pump. The receivers are placed at a lower level than the pump, and equipped with float control so that the pump may operate as a return pump under night conditions. The system may be operated in the same manner as the ordinary vacuum system when desired. Steam for heating domestic hot water should be taken from the boiler header ,back of the control valve so that pressures sufficiently high for heating the. water may be maintained on the heater. The sub-atmos pheric method, of heating can be used for the heating coils of ventilating and air conditioning systems. The flexible control of heat output secured by this method materially reduces the required size of by-pass around the heaters. Some applications qf sub-atmospheric systems are proprietary. TWO-PIPE ORIFICE SYSTEMS Orifice steam heating systems may have piping arrangements identical with vacuum systems. Some of these omit the radiator thermostatic traps, but use thermostatic or combination float and thermostatic traps on all drip points. A return condensate pump with receiver vented to Steam Heating Systems 503 atmosphere, a return line vacuum pump, or a return trap, is generally used to return the condensate to the boiler or place of similar disposition, such as a feed-water heater or hot well. The heat emission from the radiators is controlled by varying the pressure differential maintained. The principle on which these systems operate is based on the fact that the steam flow through an orifice will vary with square root of pressure drop when the ratio of the absolute pressures on the two sides of the orifice exceeds 58 percent. If the absolute pressure on the outlet side is less than 58 percent of the absolute pressure on the inlet side, no further increase in. flow null be obtained' as a result of the increased pressure difference. If an orifice is so designed in size as to exactly fill a radiator with 2 psig * on one side and $ psig on the other, the absolute pressure relation is 14.7 + 0.25 q. 2 0 = 0-90 or 90 percent. . Should the steam pressure be dropped to { psig on the supply pipe, the pressure on each side of the orifice would be balanced and no steam flow would take place. From this it will be apparent that if an orifice of a given diameter will fill a given radiator with steam when there is a given pressure on the main, reducing this steam main pressure will permit filling various desired portions of the radiator down to the point where the main pressure equals the back pressure in the radiator, provided the supply pipe pressures may be controlled sufficiently close. If orifices are designed on a similar basis for a given system and proportioned to the heating capacity of the radiators they serve, all radiators will heat proportionately to the steam pressure. The range of pressure variation is limited by the per missible noise level of the steam flowing under the pressure difference required for maximum heat output. The control of the steam supply is .obtained by a valve placed in the steam main, which maintains a deter mined pressure, and by varying the vacuum in the return fines. The valves are frequently set manually from a remote location, guided by tem perature indicating stations in the building; or thermostatically controlled from a thermostat on the roof, which automatically measures the dif ferential of outside and inside temperatures. Since the range through which the pressures may be varied is usually from 0 to 4 psig, the control should be capable of maintaining close regulation to maintain the desired space temperatures, particularly in mild weather. A recommended orifice schedule is shown in Table 1. Some systems use orifices not only in radiator inlets, but also at different points in the steam supply piping for the purpose of balancing the system to a greater extent. In this manner the difference between the initial and terminal pressure in the steam main may be compensated to a great extent. For example, if the initial pressure is 3 psig and the pressure at the end of the main is 2 psig, an orifice could be used in each branch for the purpose of obtaining a more uniform pressure throughout the system. Such a provision may be particularly useful in this system for branches close to the boiler where the drop in the main has not yet been produced. Some orifice systems are proprietary. SIZING PIPING FOR STEAM HEATING SYSTEMS The functions of the piping system are the distribution of the steam, toe return of-the condensate and, in systems where no local air vents are provided, the removal of the air. The distribution of the steam should be rapid, uniform and without noise, and the release of air should be facili 504 CHAPTER 21 1956 Guide tated as much as possible, as an air bound system will not heat readily nor properly. In designing the piping arrangement, it is desirable to maintain equivalent resistances in the supply and return piping to and. from a radiator. Arranging the piping so the total distance from the boiler to the radiator is the same as the return piping distance from the heating unit back to the boiler, tends to obtain such a result. The Table 1. Obifice Capacities fob Low Pbessube Steam Systems This table is based on data from actual testa* Orifice Diameter 64ths 09 am Inch 6 in. He Differential 5 in. Hg Differential . 4 in. Hg. Differential 2 in. Hg Differential 1 IN. He Differential Capacity Expressed in Square Feet E D R 7 -8 9 10 11 12 13 14 15 16 17 18 19 20 21 . 18-23 23-29 29-36 36-44 -44-52 52-62 62-72 72-83 83-94 94-106 106-119 119-133 133-148 148-163 163-179 16-21 21-27 27-33 33-40 40-48 48-57 57-66 66-76 76-86 86-97 97-109 109-122 122-135 135-149 149-164 15-19 19-25 25-30 30-37 37-44 44-51 51-59 59-67 67-76 76-86 86-97 97-108 108-120 120-133 133-145 10-13 13-17 17-21 21-26 26-31 31-37 37-43 43-49 49-56 56-64 64-72 72-80 80-88 88-98 98-107 SWl 11-14 14-17 17-20 20-24 24-28 28-32 32-37 37-42 42-47 47-52 52-58 58-64 64-71 Capacity Expressed in Pounds per Hour' 7 4.5-5.8 4.0-5.3 3.8-4.8 2.5-3.3 8 5.S-7.3 5.3-6.8 4.8-6.3 3.3-4.3 2.0-2.8 9 7.3-9.0 6.8-8.3 6.3-7.5 4.3-5.3 2.8-3.5 10 9.0-11.0 8.3-10.0 7.5-9.3 5.3-6.5 3.5-4.3 11 11.0-13.0 10.0-12.0 9.3-11.0 6.5-7.8 4.3-5.0 12 13.0-15.5 12.0-14.3 11.0-12.8 7.S-9.3 5.0-6.0 13 15.5-18.0 14.3-16.5 12.8-14.8 9.-3-10.8 6.0-7.0 14 18.0-20.8 16.5-19.0 14.8-16.8 10.8-12.3 7.0-8.0 15 20.8-23.5 19.0-21.5 16.8-19.0 12.3-14.0 8.0-9.3 16 23.5-26.5 21.5-24.3 19.0-21.5 14.0-16.0 9.3-10.6 17 26.5-29.8 24.3-27.3 21.5-24.3 16.0-18.0 10.5-11.8 18 29.8-33.3 27.3-30.5 24.3-27.0 18.0-20.0 11.8-13.0 19 33.3-37.0 30.5-33.8 27.0-30.0 20 0-22.0 13.0-14.5 20 37.0-40.8 33.8-37.3 30.0-33.3 22.0-24.5 14.5-16.0 21 40.8-44.8 37.3-41.0 33.3 36.3 24.5-26.8 16.0-17.8 Note.--The radiator orifice plates recommended in this table are made of brass stampings 0.023 in. thick cup-shaped to be inserted in radiator valve unions. * Flow of Steam Through Orifices into Radiators, by S. S. Sanford and C. B. Sprenger (A.S.H.V.E.Tban&* actoonb, Vol. 37, 1931, p. 371). * condensate which occurs in steam piping as well as in radiators must. be drained to prevent impeding the ready flow of the steam and air. The effect of back pressure in the returns and excessive re-vaporization, such as occurs where condensate'is released from pressures considerably higher than the vacuum or pressure in the return, must be avoided. It is important that steam piping systems distribute steam not only at full design load, but during excess and partial loads. Usually the average winter steam demand is less than half of the demand at the design outside Steam Heating Systems 505 temperature. Moreover, in rapidly warming up a system even in moder ate weather, the load on the steam main and returns may exceed the maximum operating load for severe weather, due to the necessity of raising the temperature of the metal in the system to the steam temperature, and the building to the design indoor temperature. Investigations of the return of condensate have revealed that as high as 143 percent of the design condensation rate may exist under conditions of actual operation. The piping design of a heating system is greatly influenced by its operat ing characteristics. Heating systems do not operate under constant condi tions, as conditions change continually, due to variation in load. As the system is being filled with steam, the pressures existing in various locations may be different from those which exist for appreciable periods at other locations, although at equilibrium conditions the pressures are approximately the same. In designing piping it is of especial importance to arrange the system to preclude trouble caused by such pressure dif ferences. The systems which readily release the air, permit uniform pressures to be attained in much shorter time intervals than those which are sluggish. Results are given in Fig. 18 from investigations1 to deter mine the rate of condensate and air return from a two-pipe gravity heating system. Variations in the steam pressure during the warming-up period, when the rate of air elimination and condensation is high, are clearly indicated in these curves. It is evident that the condensate flow during the initial warming-up period reaches a peak, which is greater than the constant condensing rate eventually reached when the pressure becomes uniform. Moreover, the peak condensing rate is obtained when the system steam pressure is lower than that existing during a period of constant condensing rate. It will also be noted that the peak rate of air elimination does not coincide with the higher condensing rate. Steam Flow The rate of flow of dry steam or steam with a small amount of water flowing in the same direction, is in accordance with the general laws of gas flow, and is a function of the length and diameter of the pipe, the density of the steam, and the pressure drop through the pipe. This relationship 506 CHAPTER 21 Table 2. Flow of Steam in Pipes P a loss in pressure in pounds per square inch. D = inside diameter of pipe in inches. h = length of pipe in feet. d = weight of 1 cu ft of steam. W = pounds of steam per hour. IF P = 0.0000000367 ( 1 + ^ 1956 Guide Loss Ounces COL.1 1 --- --------- 4 Pips Size m Actual 5220 Nominal Internal Diameter Aaka or Pips So Inches Can. 2 Avo PEX8& pao Con. 3 Vr4r liEKOTB m Farr Can. VJlo-or 0.25 0.50 1.00 2 3 4 5 6 7 8 10 12 14 . 16 20 24 28 32 40 48 80 160 320 480 65.28 i 1.049 0.864 0.536 -- 1.0a 0.187 92.28 m 1.380 130.5 m 1.610 1.496 2.036 1.178 --0.5a 0.190 1.828 0.0 0.193 184.6 2 2.067 3.356 3.710 0.3 0.195 226.0 VA 2.469 261.0 3 3.068 4.788 7.393 6.109 11.183 1.3 0-201 2.3 0.207 291.8 319.7 m 3.548 4 4.026 9.887 12.730 16.705 5.3 0.223 23.631 10.3 0.248 345.3 369.1 4A 4.506 5 5.047 15.947 20.006 32.134 15.3 0.270 43.719 20.3 0.290 412.7 6 6.065 28.886 71.762 30.3 0.326 452.0 7 7.023 38.743 106.278 40.3 0.358 488.3 8 7.981 50.027 149.382 50.3 0.388 522.0 9 8.941 62.786 201.833 60.3 0.415 583.6 10 10.020 78.854 272.592 75.3 0.452 639.3 12 12.000 113.098 437.S03 100.3 0.507 690.5 14 13.250 137.880 566.693 125.3 0.557 738.2 16 15.250 182.655 816.872 150.3 0.603 825.4 | Column 1 X 2X3 x. 4 = .lb of steam 175.3 0.645 904.1 1167.2 1650.7 2334.5 2859.1 pipe for a given condition. 200.3 Example 1: 1 os drop -- 2 in- pipe -- 1.3 lb press. -- 100 ft equivalent length: 0.685 130.5 X 3.710 X 0.201 X 1 - 97.2 !b per hour. 97.2 X 4b a 388.8 sq ft equivalent radiation. j Table 2 does not allow for entrained water in low-pressnif | steam, condensation in covered pipe and roughness in com i merdal pipe as found in practice. 20 40 60 80 100 120 140 160 180 200 250 300 350 400 450 500 600 700 800 900 1000 1200 1500 2000 2.240 1.580 1.290 1.120 1.000 0.912 0.841 0.793 0.741 0.710 0.632 0.578 0.538 0.500 .0.477 0.447 0.407 0.378 0.354 0.333 0.316 0.289 0.258 0.224 Pounds per square inch gage = 2.04 in. Vacuum, Mercury Column. r*r hour, b 'The factor 4 is the approximate equivalent in square feet of steam radiation of 1 lb oi steam per Steam Heating Systems 507 has been established by Babcock in the formula given at the top of Table 2. In Columns 1, 2, 3, and 4 of this table, the numerical values of the factors for different pressure losses, pipe diameters, steam densities and lengths of pipe have Been worked out in convenient form so that the steam flowing in any pipe may be calculated by multiplying together the proper factors in each column, as shown in the example at the bottom of the table. Pipe Sizes The determination of pipe sizes for a given load in steam heating depends on the following principal factors: 1. The initial pressure and the total pressure drop which may be allowed between the source of supply and at the end of the return system. 2. The maximum velocity of steam allowable for quiet and dependable operation of the system, taking into consideration the direction of condensate flow. 3. The equivalent length of the run from the boiler or source of steam supply to the farthest heating unit. 4. The direction of flow of the condensate, whether against or with the steam. Initial Pressure and Pressure Drop Theoretically, there are several factors to be considered such as initial pressure and pressure required at the end of the line, but it is most impor tant that: (1) the total pressure drop does not exceed the, initial gage pressure of the system, and in actual practice it should never exceed onehalf of the initial gage pressure; (2) the pressure drop is not so great as to cause excessive velocities; (3) there is a constant initial pressure, except on systems specially designed for varying initial pressures, such as the sub-atmospheric, which normally operate under controlled partial vacua and orifice and vapor systems, which, at times operate under such partial vacua as may be obtained due to the condition of the fire; and (4) the rise in water due to pressure drop does not exceed the difference in level, for gravity return systems, between the lowest point on the steam main, the heating units, or the dry-return, and the boiler water line. The present tendency in steam heating unmistakably points toward a constant lowering of initial pressures, even to those below atmospheric, and to the use of reasonably small pressure drops because a system de signed in this manner will operate under higher pressures without dif ficulty. When a system designed for a relatively high initial pressure and a relatively high pressure drop is operated at a lower pressure, it is likely to be noisy and have poor circulation. The total pressure drop should never exceed one-half of the initial gage pressure when condensate is flowing in the same direction as the steam. Where the condensate must flow counter to the steam, the governing factor is the velocity permissible without interfering with the condensate uw. . A.S.H.A.E. Research Laboratory experiments limit this to the capacities given in Table 3 for horizontal pipes at varying grades. Maximum Velocity The capacity of a steam pipe in any part of a steam system depends upon the quantity of condensate present, the direction in which the con densate is flowing, and the pressure drop in the pipe. Where the quantity of condensate is limited and is flowing in the same direction as the steam, only the pressure drop need be considered. When the condensate must How against the steam, even in limited quantity, the velocity of the steam must not exceed limits above which the disturbance between the steam and 508 CHAPTER 21 1956 Guide the counter-flowing water may produce objectionable sounds, such as water hammer, or may result in the retention of water in certain parts of the system until the steam flow is reduced sufficiently to permit the water to pass. The velocity at which such disturbances take place is a- function of (1) the pipe size, whether the pipe runs horizontally or vertically; (2) the pitch of the pipe if it runs horizontally; (3) the quantity of condensate flowing against the steam; and (4) freedom of the piping from water pockets which under certain conditions act as a restriction in pipe size. Reaming Important Three factors of uncertainty always exist in determining the capacity of any steam pipe. The first is variation in manufacture, which appar ently cannot be avoided. The second is the care used in reaming the ends of the pipe after cutting. The effect of both of these factors increases as the Table 3. ' Comparative Capacity of Steam.Lines at Various Pitches for Steam and Condensate Flowing in Opposite Directions* Pitch of Pipe in Inches per 10 Ft. Velocity in Ft per Sec , Pitch of Pipe tf IN. H IN. 1 IN. m in. 2 IN. 3 IN. 4 IN. 5 IN. Capacity Capacity Capacity | Capacity 1 Capacity Capacity Capacity Max. Vel. CJapacity Pipe Size . Inches > *3 > "3 > . l 9 S i 3 a Ss Capacity Expressed in Square Feet EDR i H 25.0 12 30.3 14 '37.3 18 40.4 19 42.5 20 46.1 21 47.5 22 49.3 23 1 45.8 12 52.6 15 63.0 17 70.0 20 75.2 22 83.0 23 87.9 25 90.2 26 ltf 104.9 18 117.2 20 133.0 23 144.5 25 154.0 27 165.0 28 172.6 29 178.2 31 1H 2 142.6 18 159.0 21 181.0 23 196.5 25 209.3 27 224.0 28 234.8 30 242.6 31 236.0 19 263.5 20 299.5 23 325.5 25 346.5. 27 371.5 28 388.4 29 401.1 30 Capacity Expressed in Pounds per Hour H 1 6.3 12 7.6 14 9.3 18 10.1 19 10.6 20 11.5 21 11.9 22 12.3 23 11.5 12 13.2 15 15.8 17 17.5 20 18.8 22 20.8 23 22.0 25 22.6 26 lH 1H 2 26.2 18 29:3 20 33.3 23 36.1 25 38.5 27 41.3 28 43.2 29 44.6 31 35.7 18 39.8 21 45.3 23/ 49.1 25 52.3 27 56.0 28 58.7 30 60.7 31 59.0 19 65.9. 20 -74.9 23 81.4 25 86.6 27 92.4 28 97.1 29 100.3 30 Data from The Amebjcan Society of Heating and Ventilating Engineers Research Laboratory. pipe size decreases. According to A.S.HA.E. Research Laboratory tests, either of these, factors may affect the capacity of a 1-in. pipe as much as 20 percent. The . third factor is the uniformity in grading the pipe line. All of the capacity tables given in this chapter include a factor of safety. However, the factor of safety referred to .does not cover abnormal defects or. constrictions, nor does it cover pipe not properly reamed. Equivalent Length of Rim All tables for the flow of steam in pipes, based on pressure drop, must allow for the friction offered by the pipe, as well as for the additional resistance of the fittings and valves. These resistances generally are stated in. terms of straight pipe; in other words, a certain fitting will produce a drop in pressure equivalent to so many feet of straight run of the same size of pipe. Table 4 gives the number of feet of straight pipe, usually allowed for the more common types of fittings and valves. In all' pipe sizing tables in this chapter the length of run refers to the equivalent Steam Heating Systems 509 length of run as distinguished from the actual length of pipe in feet. The length of run is not usually known at the outset; hence, it may be necessary to assume some pipe size at the start; Such an assumption frequently is considerably in error, and a more common and practical method is to assume the length of- run and to check this assumption after the pipes are sized. For this purpose the. length of nm usually is taken as double the actual length of pipe. TABLES FOR PIPE SIZING FOR LOW PRESSURE SYSTEMS* Tables 5, 6," and 7 are based on the actual inside diameters of the pipe and the condensation of \ lb (4 oz) of steam per square foot of equivalent direct radiation (abbreviated EDR) per hour. The drops indicated are Table 4. Length in Feet of Pipe to be Added to Actual Length of Run--- Owing to Fittings^--to.Obtain Equivalent Length Sizs or Pifb Inchbs Length. inFset to be Added to Run Standard Elbow Side Outlet Tee - Gate Valve* Globe Valve* Angle Valve* l ih m 2 3 3% 4 5 6 8 10 1? 14 13 1.8 2.2 3.0 3.5 43 5.0 6.5 8 9 11 13 17 21 27 30 Valve in full open position. Example of length in feet of pipe to be added to actual length of run. 3 4 5 6; 7: 8 11 13 15 18 22 -- \ 27 35 45 53 63 0.3 0.40.5 0.6 0.8 1.0 1.1 1.4 1.6 1.9 2.2 2.8 3.7 4.6 5.5 6.4 14 18 23 ; 29 34 46 54 66 80 92 112 136 180 230 270 310 . 7 10 12 15 18 22 27 34 40 45 56 67 92 112 132 152 Measured Length -- 132.0 ft 4'in. Gate Valve l.Q.ft ,4--4 an 36.0 ft r--IEquivalent Length ~ 169.9 ft Y-------- jvy-- i........:............... -H drops in pressure per 100 ft of equivalent length of run. The pipe is assumed to be well reamed and without unusual or noticeable defects. Table 5 may be used for sizing piping for steam heating systems by pre-determining the allowable or desired pressure drop per 100 equivalent met of run, and reading from the column for that particular pressure drop, this applies to all steam mains on both one-pipe and two-pipe systems, vapor systems, and vacuum systems.' Columns B to G, inclusive, are used where the steam and condensate flow in the same direction, while Columns if aQd I are for cases where the steam and condensate flow in opposite directions, as in risers and runouts that are not dripped. Columns J, K, and L are for one-pipe systems and cover riser, radiator valve and vertical connection sizes, and radiator and runout sizes, all of which are based on the 510 CHAPTER 21 1956 Guide Table 5. Steam Pipe Capacities fob Low Pressure Systems (Reference to this table will be by column letter A through L) This table is based on pipe size data developed through the research investigations of. The American Society op Heating and Air-Conditioning Engineers. . . Pipe Sue In. CAPACITIES OF STEAM MAINS AND RISERS . SPEdACCAPAdTIEarOB (One-Pips Systems Only Direction of Condensate Flow in Pipe Line Radi- With the Steam in One-Pipe and Two-Pipe Systems A psi or } Ob Drop h psi or 10. Drop A PM or 1 Os Drop 1 psi or 2 0. Drop IpM or. 4 O. Drop . i pa . or 8 Os Drop Against the Steam Two-Ppe Only Supply Up- ator RadiValves ator and and Vertical ` Riser Feed Con- Run- Vertical Hori- sontal < nee- outa tions B C Z> B F O E* 1 J* K L' Capacity Expressed in Square Feet E D R 1 H 11 2 21 3 31 4 5 6 8 10 12 16 30 39 46 56 87 100 122 134 155 190 273 315 386 449 518 635 822 948 1,160 1,230 1,420 1,740 1,740 2,010 2.460 3,210 3,710 4,550 5,280 6,100 7.460 11,000 12,700 15,500 (20,000 23,100 28,300 79 173 269 546 898 1,650 2,460 3,480 6,430 10,550 21,970 40,100 111 245 380 771 1,270 2,330 3,470 4,910 9,090 14,900 31,070 56,700 30 157 56 34 346 122 75 538 190 108 1,091. 386 195 1,800 635 395 3,290 1,130 700 4,910 1,550 1.150 6,950 2,040 1,700 12.900 4.200 3.150 21,100 7.200 5,600 43.900 15,000 12,000 80,200 (28,000 23.000 25 45 98 152 288 464 800 1,140 1,520 32.000 61.000 37,100 69,700 45,500 84,800 64,300 121,000 91,000 170,0)0 129.000 (46,000 38.000 242.000 88,000|76,000 28 62 93 169 28 62 93 169 260 475 745 1,110 2,180 Capacity Expressed in Pounds per Hour _ _t 1 H U 2 21 3 31 4 5 6 8 10 12 16 88 10 12 14 22 25 31 34 39 48 68 79 97 112 130 159 206 237 291 307 355 434 435 503 614 806 928 1,140 1 320 1,520 1,870 2 750 3,170 3,880 5^010 5,790 7,090 &|040 9|290 11,400 15',100 17,400 21,200 20 28 40 14 9 43 61 87 31 19 67 95 135 48 27 137 193 273 97 49 225 318 449 159 99 411 581 822 282 175 614 869 1,230 387' 288 869 1,230 L.740 511 1,610 '2,270 -->3,210 1,050 78$ 2.640 3,730 5,280 1,800 1,400 5,490 7,770 11,000 3,750 3.000 10,000 14,200 20,000 7.000 5,700 16,100 22,700 32,200 11,500 9,500 30,300 42,400 60,500 22.000 19.000 6| 11 20 38 72 116 200 286 380 7 16 23 42 7 7 16 23 42 65 119 186 278 545 All Horizontal Mains and Down-Feed Risen Mains UpFsed. Risers and , Un|dripped Run outs UpFeed Risers Rsdistor Con nec tions Run- * oNuotst Dripped Note.--Steam at an average pressure of 1 psig is used as a oasis tor czucuiauug ....___ __ . are in psi per 100 ft of equivalent run--based on pipe properly reamed. ' * Do not use Column H for drops of 1/24 or 1/32 psi; substitute Column C or Column B as required. b Do not use Column J for drop 1/32 psi except on sizes 3 in. and over; below 3 in. substitute Column B. c Pitch of horizontal runouts to risers and radiators should be not less than 1/2 in. per ft. Where this pitch cannot be obtained, runouts over 8 ft in length should be one pipe size larger thari called for in Table 5. Steam Heating Systems 511 critical velocities of the steam to permit the counter flow of condensate without noise. Return piping may be sized with the aid of Tables 6 and 7 where pipe capacities for wet, dry, and vacuum return lines are shown for the pres sure drops per 100 ft corresponding to the drops in Table 5. It is cus tomary to use the same pressure drop on both the steam and return sides of a system: Example 2: What pressure drop should be used for the steam piping of a system if the measured length of the longest run is 500 ft, and the initial pressure is not to be over 2-psig> Solution: It will be assumed, if the measured length of the longest run is 500 ft., that when the allowance for fittings is added, the equivalent length of run will not exceed 1,000 ft. Then, with the pressure drop not over one-half of the initial pressure, the drop could be 1 psi or less. With a pressure drop of 1 psi and a length of run of 1,000 ft, the drop per 100 ft would be A psi, while if the total drop were i psi, the drop per 100 ft would be 2'o psi. In the first instance the pipe could be sized according to Column D for ^ psi per 100 ft, and in the second case, the pipe could be sized accord ing to Column C for 1% psi. On completion of the sizing, the drop could be checked by taking the longest line and actually calculating the equivalent length of run from the pipe sizes determined. If the calcinated drop is less than that assumed, the pipe size is all right; if it is more, it is'probable that there are an unusual number of fittings involved, and either the lines must be straightened or the column for the next lower drop must be used,.and the lines resized. Ordinarily, resizing will be unnecessary. TABLES FOR PIPE SIZING FOR HIGH PRESSURE SYSTEMS Many of the recent installations of heating systems for large industrial type buildings have been designed for the use of high pressure steam, that is, without the use of pressure reducing valves. Such systems usually involve the use of unit heaters or large built-up fan units with blast heating coils. Pressures on these systems vary from 30 to 150 psi. Temperatures are controlled by a modulating or throttling type thermostatic valve con trolled by the air temperature in the room, fan inlet or outlet. Tables 8 to 11 may be used for the sizing of steam and return piping for systems of 30 and 150 psi pressure at various pressure drops. These tables are based on Babcock's formula, and have been used as the basis of design for a number of years. SIZING PIPING FOR ONE-PIPE GRAVITY SYSTEMS Gravity one-pipe air-vent systems, in which the equivalent length of run does not exceed 200 ft, should be sized by means of Tables 5, 6 and 7 as follows: 1. For the steam main and dripped runouts to risers where the steam and condensate flow in the same direction, use ^-psi drop (Column D). * 2. Where the riser runouts are not dripped and the steam and condensate flow in opposite directions, and also in the radiator runouts where the same condition occurs, use Column L. 3. For up-feed steam risers carrying condensate back from the radiators, use Column J. 4. For down-feed systems, the main risers of which do not carry any radiator con densate, use Column H. 5. For the radiator valve size and the stub connection, use Column K. 6. For the dry-return main, use Column U. 7. For the wet-return main, use Column T. On systems exceeding an equivalent length of 200 ft., it is suggested that the total drop be not over J psi. The return piping sizes should corre spond with the drop used on the steam side of the system. Thus, where Vrpsi drop is being used, the steam main and dripped runouts would be  Steam Heating Systems . Cl'si ; it l 514 CHAPTER 21 1956 Guide Table 8. Steam Pipe Capacities fob 30 Psig Steam Systems* Capacity Expressed in Pounds per 'Hour (Steam and Condensate Flowing in Same Direction) Pipe Site Inches Deop in Pressure--Pounds pee 100 Ft in Length HH HH 1 2 15 22 31 38 45 63 31 ' 69 ` 107 217 358 46 100 154 313 516 63 141 219 444 730 77 89 125 172 199 281 267 309 437 543 627 886 924 1,030 1,460 651 979 940 1,410 1,330 2,000 1,630 2,450 1,880 2,830 2,660 4,000 1,390 2,560 4,210 - 2,000 3,640 6,030 2,830 5,230 8,590 3,460 6,400 10,400 4,000 7,390 12,100 5,660 10,500 17,200 12 ' 8,750 16,300 25,600 12,600 23,500 36,900 17,900 33,200 52,300 21,900 40,600 64,000 25,300 46,900 74,000 35,100 66,400 104,5Q0 * Note: Steam at an average pressure of 30 psig is used as the basis for calculating the above table. sized from Column C ; radiator runouts and undripped riser runouts from Column L; up-feed risers from Column J; the main riser oh a down-feed system from Column C (it will be noted that if Column H is used the drop would exceed the limit of fa psi); the dry return from Column R; and the wet-return from Column Q. With a ^-psi drop the sizing would be the same as for fa psi, except that the steam main and dripped runouts would be sized from Column B, the main riser on a down-feed system from Column B, the dry-return from Column 0, and the wet-return from Column N. Notes on Gravity One-Pipe Air-Vent Systems 1. Pitch of mains should not be less than } in. in 10 ft. 2. Pitch of horizontal runouts to risers and radiators should not be less than | in. per foot. Where this pitch cannot be obtained, runouts over 8 ft in length should be one size larger than called for in the table. 3. In genera], it is not desirable to have amain less than 2in. The diameter of the far end of the supply main should not be less than half its diameter at its largest part. Table 9. Steam Pipe Capacities fob 150 Psio Steam Systems* Capacity Expressed in Pounds per Hour (Steam and Condensate Flowing in Same Direction) Inches Drop in Pressure--Psi per 100 Ft in Length HX HH 1 2 5 H 1l Wyt 2 z ZYi 4 5 6 8 10 12 58 130 203 412 683 1,240 1'860 2|630 4; 860 7,960 16,600 30,800 48,600 41 82 185 287 583 959 1,750 2,630 3,720 6,880 11,300 23,500 43,400 68,800 58 117 262 407 825 1,360 2,480 3.720 5,260 9,730 16,000 33,200 61,700 97,300 71 143 320 497 1,010 1,650 3,020 4,550 6,430 11,900 19,500 40,600 75,600 119.000 82 165 370 575 1,170 1,920 3,500 5.250 7,430 13,800 22,600 47,000 87,300 138,000 116 233 523 813 1,650 2,710 4,940 7,420 10,500 19,500 31,900 66.400 123,000 194,000 184 1,290* l ,820 11,700 50,400 * Note: Steam at ar* average pressure of 150 psig is used as the basis for calculating the above table. Steam Heating Systems Table 10. Return Pipe Capacities for 30 psig Steam Systems* Capacity Expressed in Pounds per Hour 515 Inches X 1 IX iX 2 2X 3 3pi 4 5 6 H 115 230 485 790 1,580 2,650 4,850 7,200 10,200 19,000 31,000 Drop in Pressure--Pounds per 100 Ft in Length H 170 340 710 1,160 2.360 3,900 7,100 10,600 15,000 27,800 45,500 M 245 490 1,025 1,670 3,400 5,600 10,300 15,300 21,600 40,300 65,500 H 308 615 1,290 2,100 4,300 7,100 12,900 19,200 27,000 55,500 83,000 1 365 730 1,530 2,500 5,050 8,400 15,300 22,800 32,300 60,000 98,000 * Note: The above table is based on steam at pressures of 0 to 4 psig. 4. Supply mains, runouts to risers, or risers, should be dripped where necessary. 5. Where supply mains are decreased in size they should be dripped, or be provided with eccentric couplings, flush on bottom. Example 3: Size the one-pipe gravity steam Bystem shown in Fig. 19 assuming that this is all there is to the system, or that the riser and main shown involve the longest run on the system. Solution: The total length of run actually shown is 215 ft. If the equivalent length of run is taken at double this, it will amount to 430 ft, and with a total drop of i psi the drop per 100 ft will be slightly less than A psi. It would be well in this ease to use A psi, and this would result in the theoretical sizes indicated in Table 12. These theoretical sizes, however, should be modified by not using a wet-return less than 2 in., while the main supply, g-h, if from the uptake of a boiler, should be made the fiul size of the main, or 3 in. Also the portion of the main k-m should be made i in. if the wet-return is made 2 in. SIZING PIPING FOR ONE-PDPE VAPOR SYSTEMS Piping for one-pipe vapor systems is sized so as to permit only a few ounces pressure drop in the system. Otherwise, the method follows that outlined for sizing one-pipe gravity systems. Table 11. Retubn Pipe ,Capacities fob 150 psig Steam Systems* Capacity Expressed in Pounds per Hour Pipe Sub * Inches X 1 IX IX 2 2X 3 &X 4 5 6 X 156 313 650 1,070 2,160 3,600 6,500 9,600 13,700 25,600 42,000 Deop in Pekssube--Psi pee 100 Ft in Length H 232 462 960 1,580 3,300 5,350 9,600 14,400 20,500 38,100 62,500 H 360 690 1,500 2,460 4,950 8,200 15,000 22,300 31,600 58,500 96,000 H 465 910 1,950 3,160 6,400 10,700 19,500 28,700 40,500 76,000 125,000 1 560 1,120 2,330 3,800 7,700 12,800 23,300 34,500 49,200 91,500 150,000 2 890 1,780 3,700 6,100 12,300 20,400 37,200 55,000 78,500 146,000 238,000 Note. The above table is based on steam at pressures of 1 to 20 peig 516 CHAPTER 21 Table 12. Pipe Sizes for One-Pipe Up-Feed System Shown in Fig. 19 Part of System Section of Pipe Raoxation Theoretical Practical Supplied Pipe size Pipe size EDR Sq Ft (Inches) (Inches) 1956 Guide Branches to radiators.......... Branches to radiators.......... Riser.......................................... Riser.......................................... Riser.................................... .. a.to b b to c c to d Runout to riser..................... Supply main........................... Branch to supply main.... Dry return main......... '........ Wet return main................... Wet return main................... Wet return main................... /to g g to h h to / /to * k to m m to n n to p 100 50 200 300 400 500 . 600 - 600 600 600 600 600 600 600 2 . IK 2 2K 2H 3 3 3K 3 2H IK 1 1 1 2 IK -2 m 2H 3 3 3H 3 .3 2 2 2 2 3rd. ft . Horn __ *> ni Fig. 19. Rises, Supply Main and Return Main op One-Pipe System SIZING PIPING FOR TWO-PIPE HIGH PRESSURE SYSTEMS Steam supply piping for two-pipe high pressure can be sized for greater pressure drops than that of the return piping. For a system using steam at 30 psig, the total pressure drop can be 5 to 10 psi, and for 150 psig systems, 25 to 30 psi. *, It has been observed that the maximum total pressure in the returns of a 30-psig system is about 5 psig, and that of a 150,-psig system is about 20 psig. The pressure in the return mains is* of course, caused by the dis charge of traps and flashing of condensate into steam because the return line pressure is below that corresponding to the saturation temperature of the condensate. The usual practice in the sizing of high pressure returns has been to size on the basis of psi per 100 ft of pipe for 30-psig sys tems, and 1 psi per 100 ft. for 150-psig systems. This is an average figure which corresponds generally to several of the previously published tables for the design of high pressure return piping. Notes on Two-Pipe High Pressure Systems Pitch of mains should not be less than \ in. in 10 ft.1 Pitch of horizontal runouts to risers and heating units should not be less than | in. per ft. SIZING PIPING FOR TWO-PIPE LOW PRESSURE SYSTEMS Piping for two-pipe low pressure systems is sized in the same manner as for two-pipe vapor systems, except that the pressure drop throughout the system can be based on 5 psi to 1 psi drop. SIZING PIPING FOR TWO-PIPE VAPOR SYSTEMS While many manufacturers of patented vapor heating accessories have their own schedules for pipe sizing, an inspection of these sizing tables indi cates that in general as small a drop as possible is recommended, ine reasons for this are: (1) to have the condensate return to the boiler Dy Steam Heating Systems 517: gravity; (2) to obtain a more uniform distribution of steam throughout the system, especially when it is desirable to carry a moderate, or low fire; and (3) to prevent large variations in pressure which would nullify the value of graduated valves on radiators. For small vapor systems where the equivalent length of run does not exceed 200 ft, it is recommended that the main and any runouts to risers that may be dripped, should be sized from Column D, Table 5, while riser runouts not dripped and radiator runouts should employ Column 7, The up-feed steam risers should.be taken from Column H. On the returns, the risers should be sized from Tables 6 and 7, Column U (lower portion), and the mains from Column U (upper portion). It should again be noted that the pressure drop in the steam side of the system is kept the same as on the return side, except where the flow in the riser is concerned. On a down-feed system, the main vertical riser should be sized from Column H, but the down-feed risers can be taken from Column D, al though it so happens that the values in Columns D and H for small systems correspond. This will not hold true in larger systems. For vapor systems over 200 ft of equivalent length, the drop should not exceed psi to \ psi, if possibles Thus, for a 400 ft equivalent run the drop per 100 ft should be not over 3 psi divided by 4, or 3V psi. In this case the steam mains would be sized from Column B, the radiator and undripped riser runouts from Column 7; the risers from Column B, because Column H gives a drop in excess of A psi. On a down-feed system, Column B would have to be used for both the main riser and the smaller risers feeding the radiators in order not to increase the drop over A psi.. The return risers would be sized from the lower portion of Column 0 and the dry return main from the upper portion of the same column, while any wet returns would be sized from Column N. The same pressure drop is applied on both the steam and the return sides of the system. Notes on Vapor Systems . 1. Pitch of mains should not.be less than 1 in. in 10 ft. 2. Pitch of horizontal runouts to risers and radiators should not be less than 1 in. per ft. Where this pitch cannot be obtained, runouts over 8 ft in length should be one size larger than called for in the table. 3. In general it is not desirable to have a supply main smaller than 2 in. 4. When necessary, supply main, supply risers, or runouts to supply risers should he dripped separately into a wet-return, or may be connected into the dry-return through a thermostatic drip trap. SIZING PIPING FOR TWO-PIPE VACUUM SYSTEMS Vacuum, atmospheric, sub-atmospheric and orifice systems are usually employed in large installations and have total drops varying from 1 to | Psi- Systems in which the maximum equivalent length does not exceed ooa ^ Preferab'y employ the smaller pressure drop; while systems over 200 ft equivalent length of run, more frequently are designed for the higher drop, owing to the relatively greater saving in pipe sizes. For example, a system with 1200 ft longest equivalent length of run would employ a drop Per 100 ft of psi divided by 12, or ^ psi. In this case, the steam main would be sized from Column C, Table 5, and the risers also from Column L (Column H could be used a3 far as critical velocity is concerned, but the drop would exceed the limit of -jV psi). Riser runouts, if dripped, would J^e Column C but, if undripped, would use Column 7; radiator ninouts, t-olumn 7; return risers, lower part of Column S, Tables 6 and 7; return rUnouts to radiators, one pipe size larger than the radiator trap connections. 518 CHAPTER 21 1956 Guide Notes on Vacuum Systems 1. It is not generally considered good practice to exceed i psi drop per 100 ft of equivalent run, nor to exceed 1 psi total pressure drop in any system. 2. Pitch of mains should not be less than J in. in 10 ft. 3. Pitch of horizontal runouts to risers and radiators should not be less than $ in. per ft. Where this pitch cannot be obtained, runouts over 8 ft in length should be one size larger than called for in the table. 4. In general, it is not considered desirable to have a supply main smaller than 2 in. 5. When necessary, the supply main, supply riser, or runout to a supply riser should be dripped separately through a trap into the vacuum return. A connection should not be made between the steam and return sides of a vacuum system without interposing a trap to prevent the steam from entering the return line. ;. 6. Lifts should be avoided if. possible, but when they cannot be eliminated they should be made in the manner described in this chapter. 7. No lifts can be used in orifice and atmospheric systems. In sub-atmospheric systems the lift must be at the vacuum pump. _ SIZING PIPING FOR INDIRECT HEATING UNITS . Pipe connections and mains for indirect heating units are sized according to the quantity of steam condensed by each unit.' The condensation per' unit depends upon the entering temperature and the air velocity, and may be obtained from manufacturers' rating tables. Where two or more units are placed in series, the entering air temperature for any unit will be the leaving temperature for the preceding unit. . When the amount of condensation has been obtained for each unit, the pipe sizes should be based on the length of run and the pressure drop de sired, as in the case of radiators. It is generally desirable to place the indirect heating units on a separate piping system rather than to connect them to the piping which supplies direct radiation. For type of connections see section on Connections to Heating Units. PRESSURE REDUCING VALVES While the illustrations given in Figs. 2 to 17 inclusive, indicate the various systems to be supplied by separate boiler plants, it is also possible to have steam supplied at high pressure by a boiler plant remotely located. In this case steam is supplied directly to the system or through a pressure reducing valve. Condensate can either be returned to the boiler plant or wasted to the sewer. The general arrangement of the systems fed, through a pressure reducing valve will not vary from those illustrated with a boiler supply. When high pressure steam is being supplied and lower steam pressures are required for heating, for domestic hot water, for utility services,-etc., one or more pressure reducing valves (pressure regulators) are required. These are used in two classes of service, one where the steam must be shut off tight to prevent the low pressure building up at time of no load, and the other where the low pressure lines will condense enough steam to offset normal leakage through the valve. In the latter case, double seated valves may be used in a manner that reduces the, work required of the diaphragm in closing the valve and consequently, the size of the diaphragdi. These valves also control the low pressures more closely under conditions of varying high pressures. .; Valves that shut off all steam are called dead end type. They are single seated, and some of them have pilot operation that provides close control of the reduced pressure. If a thermostatically controlled valve is installed Steam Heating Systems 519 after, and near, a reducing valve in such a manner as to cut off the passage of steam, the dead end type should be used. It is common practice, when the initial steam pressure is 100 psig or higher, to install two-stage reduction. If the radiation served is cast-iron, the ASME code requires two reducing valves when the inlet pressure exceeds 50 psig. This makes a quieter condition of steam flow, as it is apparent that with one reduction, as for example from 150 to 2 psig, there is a smaller opening with greater velocity across the reducing valve and, consequently, more noise. A two-stage reduction also introduces a source of safety, since if one reducing valve were to build up its discharge .pressure, this excess pressure would not be so great as the case might be in a one-stage reduction. - If an installation requires single seated valves and the pilot type cannot be used, it is necessary to use two-stage reduction, as single seated valves require sufficient diaphragm area to overcome the unbalanced pressure underneath the single valve. In many cases the large diameter of dia phragm required would make it impractical in construction. With a twostage reduction, the diaphragm diameter required would be reduced. If a one-stage reduction is desired, it is necessary to use a pilot controlled pressure reducing valve, where low pressures are to be maintained closely. In making a two-stage reduction, allowance for expansion of steam on the low pressure side of the valve should be made by increasing the pipe size. This also allows steam flow to be at a more nearly uniform velocity. Separating the valves by a distance up to 20 ft is recommended to reduce excessive hunting action of the first valve. When the reduced pressure is approximately 15 psig or lower, the weight and lever diaphragm valve gives the best results with minimum main tenance. Above 15 psig, spring loaded diaphragm valves should be used, because of the extra weights required on weight and lever type. Pressure equalizing lines should not be connected too close to the valve. They should be connected into the bottom of the reduced pressure steam main, to allow maximum condensate to exist in the equalizing lines, or the connection can be made into the top of the main if a water accumulator is used to reduce the variation of the head of water on the diaphragm. Care should be exercised in selecting the size of a reducing valve. The safest method is to consult the manufacturer. It is essential that sizes of piping to and from the reducing valve be such that they will pass the desired amount of steam with the maximum velocity desired. A common error is to make the size of the reducing valve the same size as that of the service, or outlet pipe size. Generally, this will make the reducing valve oversized, and bring about wire-drawing of valve and seat, due to small lift of the valve seat. On installations where the steam requirements are relatively large and variable in mild weather or reduced demand periods, wire-drawing may occur. To overcome this condition, two reducing valves are installed in parallel, with the sizes selected on a 70 and 30 percent proportion of maximum flow. For example, if 50,000 lb of steam per hour are required, the size of one valve is bn the basis of 0.7 X 50,000 lb, or 35,000 lb, and the other on the basis of 0.3 X 50,000 lb, or 15,000 lb. During the mild or reduced demand periods, steam will flow through the smaller valve only. During the remainder of the season, the larger valve is set to control at whatever low pressure is desired, and the smaller one at a somewhat lower pressure. Thus, when steam flow is not at its maximum, the smaller valve is closed, but it opens automatically when the maximum 520 CHAPTER 21 1956 Guide steam demand occurs, because this maximum demand creates a slight pressure drop in the service line. / The installation of reducing valves in pipe lines requires detailed planning. They should be installed to give ease of access for inspection and repair, and wherever possible, with diaphragm downward, except in cases of pilot operated valves. There should be a by-pass around each reducing valve of size equal to one-half the size of reducing valve. The globe valve in by-pass line should be of a good type of construction, and must shut off absolutely tight. A steam pressure gage, graduated up to the initial pressure, should be installed on the low pressure side. Safety valves located on the low pressure side should be set 5 psi higher than the final pressure, but may be 10 psi higher than the reduced pressure if this reduced pressure is that of the first stage reduction of a double reduction. Strainers are sometimes installed on the inlet to the reducing valve, but are not required before a second-stage reduction. If a two-stage reduction is made, it is well to install a pressure gage immediately before the reducing valve of the second-stage reduction also. In sizes 3 in. and above, it is advisable to install a drip trap between the two reducing valves. . BOILER CONNECTIONS Steam . Cast-iron, sectional heating boilers usually have several outlets in the top. Two or more outlets should be used whenever possible to reduce the velocity of the steam in the vertical uptakes from the boiler, and thus to prevent carrying of water into the steam main. Return Cast-iron boilers are generally provided with return tappings on both sides, while steel boilers are generally equipped with only one return Steam Heating Systems 521 tapping. Where two tappings are provided, both should be used to effect proper circulation through the boiler. The return connection should include either a Hartford return connection or a check valve to prevent the accidental loss of boiler water to the returns, with consequent danger of boiler damage. The Hartford return connection is to be preferred over the check valve, because the latter is apt to stick or not close tightly and, furthermore, because the check valve offers additional resistance to the condensate coming back to the boiler, which in gravity systems would raise the water line in the far end of the wet-return several inches. In order to prevent the boiler from losing its water under any circum stances, the use of the Hartford return connection is recommended. This connection for a one- or two-boiler installation is shown in. Fig. 20. The essential features of construction of a Hartford return connection are: (1) a direct connection (made without valves) between the steam side of the boiler and the return side of the boiler, and (2) a close nipple, or preferably an inverted Y-fitting connection about 2 in. below the normal boiler water line from the return main to the boiler steam and return pressure balance connection. Equalizing pipe connections between the steam and return are given in Fig. 20, based on grate areas, but in no case shall this pipe size be less than the main return piping from the system. Sizing Boiler Connections Little information is available on the sizing of boiler runouts and steam headers. Although some engineers prefer an enlarged steam header to serve as additional steam storage space, there ordinarily is no sudden demand for steam in a steam heating system, except during the heating-up period, at which time a large steam header is a disadvantage rather than an advantage. The boiler header may be sized by first computing the maximum load that must be carried by any portion of the header under, any conceivable method of operation, and then applying the same schedule of pipe sizing to the header as is used on the steam mains for the building. The horizontal runouts from the boiler, or boilers, may be sized by cal culating the heaviest load that will be placed on the boiler at any time, and sizing the runouts on.the same basis as the building mains. The difference in size between the vertical uptakes from the boiler, which should be of same size as the boiler outlet tapping, and the horizontal main or runout, is compensated for by the use of reducing ells. Return connections to boilers in gravity systems are made the same size as the return main itself. Where the return is split and connected to two tappings on the same boiler, both connections are made the full size of the return line. Where two or more boilers are in use, the return to each may be sized to carry the full amount of return for the maximum load which that boiler will be required to carry. Where two boilers are used, one of them being a spare, the full size of the return main would be carried to each boiler, but if three boilers are installed, with one spare, the return line to each boiler would require only half of the capacity of the entire system, or, if the boiler capacity were more than one-half the entire system load, the return would be sized on the basis of the maximum boiler capacity. As the return piping around the boiler is usually small and short, it should not be sized to the minimum. With returns pumped from a vacuum or receiver return pump, the size 0` the line may be calculated from the water rate on the pump discharge when it is operated, and the fine sized for a very small pressure drop. I ne relative boiler loads should be considered, as in the case of gravity 522 CHAPTER 21 1956 Guide return connections. Boiler header and piping sizes should be based on the total load. / CONDENSATE RETURN PUMPS Condensate return pumps are used for gravity systems when the local conditions do not permit the condensate to return to the boiler under the existing static head. The return of the condensate permits the water to pass repeatedly through the cycle of vaporization, with subsequent condensation and return to the boiler. During such repeated cycles any incrustants or other substances in solution are precipitated and the water de-activated to a considerable extent, so that corrosion of a serious nature is seldom ever encountered where the condensate is repeatedly used. Serious corrosion is more frequently found in systems in which the con densate is wasted, and fresh make-up water is continually being introduced. A generally accepted condensate pump unit for low pressure heating systems consists of a motor-driven centrifugal pump with receiver and automatic float control. Other types in use include rotary, screw, turbine and reciprocating pumps with steam turbine or motor drive, and direct . acting steam reciprocating pumps. The receiver capacities of these automatic units should be sized so as not to cause too great a fluctuation of the boiler water line if fed directly to the boiler, and at the same time not so small as to cause too frequent operation of the unit. The usual unit provides storage capacity between stops in the receiver of approximately 1.5 times the amount of condensate returned per minute, and the pump generally has a delivery rate of. 3 to 4 times the normal flow. This relation of receiver and pump size to heating system condensing capacity takes account of the peak condensation rate. A typical installation of a motor driven automatic condensate unit is illustrated in Fig. 9. VACUUM HEATING PUMPS On vacuum systems, where the returns are under a vacuum, and subatmospheric systems, where the supply piping, radiation and the returns are under a vacuum, it is necessary to use a vacuum pump to discharge the air and non-condensable gases to atmosphere and to dispose of the con densate. Direct-acting steam-driven reciprocating vacuum pumps are sometimes used where high pressure steam is available, or where the exhaust steam from the pump can be utilized. In general, however, these have been replaced by the automatic motor-driven return line heating pump especially developed for this service. Steam turbine drive is also frequently used where steam at suitable pressures is available, the steam being used afterward for building heating. The usual vacuum pump unit consists of a compact assembly of exhausting unit for withdrawing the air-vapor mixture and discharging the air to atmosphere, and a water removal unit which discharges the condensate to the boiler. They 4re furnished complete with receiver, separating tank and automatic controls, mounted as an integrated unit on one base. There are also special steam turbine driven units which are operated by passing the steam to be used in heating the building through the turbine with only a 2 to 3 psi drop across the turbine required for its operation. Under special conditions such as installations where it is necessary to return the condensate to a high pressure boiler, auxiliary water pumps may be supplied. In some instances separate air and water pumps may be used. Steam Heating Systems 523 For rating purposes* vacuum pumps are classified as low vacuum and high vacuum. Low vacuum pumps are those rated for maintaining 5 in. Hg vacuum on the system, and high vacuum pumps are those rated to maintain vacuums above 5 in. Hg. Manufacturers of vacuum pumps specify that the standard capacity of pumps shall be 0.3 to 0.5 cfm of air removal, and 0.5 gpm of water per 1000 EDR served. This capacity is at 5 in. Hg of vacuum, and with con densate at 160 F. The larger air capacity is for smaller systems, and the smaller capacity for the larger systems. Some manufacturers, however, specify more air capacity than stand ard where higher vacuums are desired and where air leakage is anticipated. The vacuum that can be maintained on a system depends upon the relationship of the air leakage rate into the system to the operating air capacity of the hydraulic evacuator when operating at any given return line temperature. The hotter the returns, the lower will be the possible vacuum for a given air leakage rate into the system. It is particularly essential on high vacuum installations to. see that the entire system is tight in order to reduce the amount of inward air leakage and, further more, to see that relatively higher temperature steam is prevented from entering the vacuum return lines through leaky traps, high pressure drips, etc. It is for this reason that the condensate from equipment using steam at high pressures should not be connected directly to a vacuum return line, but should drain to a flash tank or flash leg through a high pressure trap. The receiver should have an equalizing connection to a low pressure steam main and drain through a low pressure trap to the vacuum return main, as indicated later in this chapter in section on Drips. Vacuum Pump Controls In the ordinary vacuum system, the vacuum pump is controlled by a vacuum regulator which cuts in when the vacuum drops to the lowest point desired, and cuts out when it has been increased to the highest point, these points being varied to suit the particular system or operating condi tions. In addition to this vacuum control, a float control is included which will start the pump whenever sufficient condensate accumulates in the receiver, regardless of the vacuum on the system. A selector switch is usually provided to allow operation at night as a condensate pump only, also to give manual or continuous operation when desired. There are several variations in the control of the vacuum maintained on the system by the pump. In some sub-atmospheric systems where orifices are used, the vacuum pump control maintains a pressure difference between the supply and the return piping, which is held within relatively close limits. There are other sub-atmospheric systems which utilize special temperature-pressure actuated controls for maintaining the desired condi tions in the return lines. Where various zones are connected to the same return main, the return vacuum must be controlled to meet the requirements of the zone operating at the lowest steam supply pressure. Piston Displacement Vacuum Pumps Piston displacement return vacuum heating pumps may be either elec tric or steam driven. Their piston speed in feet per minute should not exceed 20 times the square root of the number of inches in their stroke. Phey are usually supplied with an air separating tank, open to atmosphere, placed on the discharge side of the pump, and at an elevation sufficiently 524 CHAPTER 21 1956 Guide Steam Heating Systems THERMOSTATIC | OUTtT 525; Fig. 21. Single Poet Float Trap high to allow gravity flow of the condensate to the boiler. If the boiler pressure is too high for such gravity feed, then an additional steam pump for feeding the boiler is desirable. The extra pump is sometimes avoided by using a closed separating tank, with a. float controlled vent. In both arrangements, the air taken from the system must be discharged against the full discharge pressure of the vacuum pump. In the case of high or medium pressure boilers, it is better to use the atmospheric separator and the second pump. .. In figuring the required displacement for such pumps, a value of from 6 to 10 times the volumetric flow of condensate is used for average vacuums and systems. STEAM TRAPS Steam traps, as the name implies^ are automatic devices used to trap or hold steam in an apparatus or piping system until it has given up ite latent heat, and to allow condensate and air to pass as soon as it accumu lates. In general, traps consist of a vessel in which to accumulate the condensate, an orifice through whioh the condensate is discharged, a valve to close the orifice port, mechanisms to operate the valve, and inlet and outlet openings for the entrance and discharge, of the condensate from the trap vessel. Steam traps are classified according to the type of operating device by which they function. The traps which are available on the market today may be classified as (1) float, (2) thermostatic, .(3) float and thermostatic, (4) upright bucket, (5) inverted bucket, (6) flash, (7) impulse, (8) tilting, (9) lifting, and (10) boiler return trap or alternating receiver. Float Traps. Float traps operate by the rise and fall of a float due to a change of condensate level in the trap. When the trap is empty, the float is in its lowest position and the discharge valve is closed. As condensate accumulates in the trap IlG-J5- Ttpical Float and thermostatic Trap chamber, the float rises and gradually opens the valve, and the pressure of the steam pushes the condensate out of the valve. The discharge from a float trap is generally continuous, since the opening of the valve is proportioned to the flow of condensate through the trap. A gage glass may be used to indicate the height of condensate in the trap chamber. Unless float traps are well made and proportioned, there is danger of considerable steam leakage through the discharge valve due to unequal expansion of the valve and seat, and the sticking of moving parts. Float traps are made in sizes from J to 3 in., and for pressures varying from vacuum conditions to 200 psig. Float traps are used for draining condensate from steam separators, steam headers, blast coils, heating systems, steam water heaters, laundry equipment, sterilizers, and other equipment. When used for draining low pressure systems, float traps should be equipped with a thermostatic air vent (See Float and Thermo static Traps). Kgs 21 and 22 illustrate types of float traps which are in use at the present time. Thermostatic Traps. Thermostatic traps function by means of elements which expand and contract under the influence of heat and cold. Early types of thermo static traps employed carbon posts and bi-metallic elements for expansion. In general, the modem type of thermostatic trap consists of thin corrugated metal bellows or discs enclosing a hollow chamber. The chamber is either filled with a liquid, or a small amount of a volatile liquid, such as alcohol, is introduced. The liquid expands or becomes a gas when steam comes in contact with the expansive ele ment. The pressure created in either case expands the element and closes the valve of the trap against the escape of steam. When condensate or air comes in contact with the element, it cools and contracts, opening the valve and allowing them to escape. The discharge from this type of trap is intermittent. Thermostatic traps find their use generally for the draining of condensate from radiators, convectors, pipe coils, drips,' unit heaters, water heaters, cooking kettles, and other equipment. Except for radiators and convectors, it is recommended that a strainer be installed' on the inlet connection to the trap to prevent dirt, pipe scale, and other foreign sub stance from entering the trap. A cooling leg of a length of pipe should also be pro vided ahead of the trap on unit heaters and similar apparatus to cool the condensate id order to help in the trap action. Thermostatic traps are made in sizes from i | outlet |inlet Fig. 27. Inverted Bucket Trap Fig. 28. Inverted Bucket Trap with Central Guide 526 CHAPTER 21 1956 Guide to2in.,and for pressures ranging from vacuum conditions to 300 psig. Figs. 23 and 24 illustrate types of thermostatic traps which are available at the present time. Float and Thermostatic Traps. This type of trap is a combination of the float trap and the thermostatic trap, and finds its use in the draining of condensate from unit heaters, blast heaters, and coil heaters for water, oil or other liquids where there is apt to be a large volume of condensate which would not permit successful operation of thermostatic traps alone. The function of the float element of this trap is to handle the condensate, and of the thermostatic element to permit the flow of air and to prevent the flow of steam around the float valve. Float and thermostatic traps are made in sizes from J to 2 in. and usually operate under pressures varying from vacuum conditions to 40 psig, although some are made to operate at a maximum pressure of 200 psig. Fig. 25 illustrates a typical float and thermostatic trap. Upright Bucket Traps. In this type of trap, the condensate enters the trap cham ber and fills the space between the bucket and the walls of the trap. This causes the bucket to float, and forces the valve againBt its seat, the valve and ita stem usually being fastened to the bucket. When the condensate in the chamber rises above the edges of the bucket, it overflows into it and causes the bucket to sink, thereby with drawing the valve from its seat. This permits the steam pressure acting on the sur- , face of condensate in the bucket to force the water to the discharge opening. When the bucket is emptied, it rises and closes the valve and another cycle begins. The discharge from this type of trap is intermittent, and it requires a definite differen tial pressure (usually 1 psi at least) between the inlet and outlet of the trap in order to Steam Heating Systems 527 bottom of the trap to the outlet of same. Inverted bucket traps are made in sizes from i to 3 in., and for pressures varying from vacuum to'2400 psig. Figs. 27 and 28 illustrate some of the types of inverted bucket trapB which are available on the market at the present time. ` Flash Traps. These traps depend on the property of condensate at a high pressure and temperature to flash into steam at a lower pressure. Condensate flows freely through the orifice of the trap due to the pressure difference from inlet to outlet of trap until steam enters the inlet chamber and mixes with the remaining condensate, heating the condensate and causing it to flash, thereby choking the flow through the orifice and allowing more condensate to accumulate in the trap. The discharge from flash type traps is intermittent. There are no moving parts in this type of trap. The orifice, however, is adjustable for the pressure differential required. A gage glass or float indicates whether the trap is operating. These traps can be used for draining condensate from steam water and oil heaters, blast heaters, unit heaters, dryers, vulcanizers, kitchen equipment, laundry equipment, evaporators, steam lines and other equipment, where the pressure differential between Bteam supply and condensate return does not drop below 5 psi. Flash type traps are made in sizes from j to 3 in., and for pressures varying from vacuum to 450 psig. Fig. 29 illustrates a trap of the flash type. ' Impulse Traps. These traps are a modification of the flash trap, and depend on the same principle of flash for their operation. In the impulse trap the flashing action Fiq. 29. Flash Trap lift the condensate out of the bucket to the return opening. Upright bucket traps are used for draining condensate and air from blast coils, unit heaters, Bteam mains, laundry equipment, sterilizers, water and oil heaters and other equipment. This type of trap is particularly suited for use where there are pulsating pressures, such as draining steam lines and separators to reciprocating pumps or engines. It is not influenced by pulsations or wide fluctuations of pressure. Upright bucket traps are obtainable in sizes varying from i to 2J in., and for pressures varying from vacuum to 1200 psig. Fig. 26 illustrates an upright bucket trap. " Inverted Bucket Traps. In this type of trap, steam, condensate and air enter the trap under the bell or inverted bucket. Steam floats the inverted bucket and closes the valve. Condensate entering the trap enables the inverted bucket to fall, opening the valve. The condensate then discharges through the open valve until steam again enters and displaces the water contained in the bucket, thus restoring its buoyancy. The steam pressure entering through the open valve discharges the trap. Air is eliminated automatically by passing through the small vent hole located m the top of the inverted bucket. Inverted bucket traps for use on low pressure systems, par ticularly with blast coils or unit heaters, are usually furnished with a large capacity opening equipped with a bi-metallic thermostatic element which closes when heated by steam, and opens when cooled by air and condensate, allowing air to escape from the inverted bucket to the trap outlet. Inverted bucket traps are used for draining condensate and air from blast coils, unit heateTs, steam drips, laundry equipment, sterilizers, steam water heaters and other equipment. They are particularly suited for draining condensate from steam lines or equipment where abnormal amounts of air must be discharged, and where there is also foreign matter such as dirt, sludge and oil draining to the trap. The discharge from inverted bucket traps, like that of the upright bucket traps, iB intermittent and requires a definite differential pressure between the inlet and the outlet of the trap in order to lift the condensate from the Fig. 31. Tilting Trap is utilized to govern the movement of a valve by causing changes in pressure in a control chamber above the valve. A small portion of condensate, called control flow, by-passes continuously through the control chamber. At low and medium temperatures, the discharge through the center orifice reduces control chamber pressure, and the valve opens for free discharge of air and condensate. When condensate reaches near-steam temperature, part of the control flow flashes into vapor, due to reduced pressure in control chamber. The increased volume of the condensate-vapor mixture restricts the discharge through the center orifice, and therefore the reduced pressure in control chamber builds up, closes the valve, and shuts off all discharge of hot condensate, except the small amount flowing through center orifice. Under normal condensate loads, the valve opens and closes at short intervals Under heavy loads, the valve opens wide and the discharge is heavy and continuous. Impulse traps can be used for draining condensate from steam mains, unit heaters, laundry equipment, kitchen equipment, oil and water heaters, sterilizers, and other equipment where the pressure at the trap outlet is 25 percent or less than that of the inlet pressure. Impulse traps are made in sizes from j to 2 in., and for pressures ranging from one to 600 psig. Fig. 30 illustrates a trap of the impulse type. Tilting Traps. This type of trap as the name implies depends for its operation on the tilting of the trap receiver. When the receiver is in a horizontal position con densate accumulates until the weight of condensate overbalances that of a counter weight, when the receiver tilts. The tilting action opens the discharge valve, and steam pressure pushes the condensate out of the open discharge valve. When the receiver tank is emptied, except for a slight water seal, the receiver drops back to its 528 CHAPTER 21 1956 Guide Fig. 33. Boiler Return Trap or Alternating Receiver Fig. 34. Dripping Main Where It Rises to Higher Level horizontal position and closes the discharge valve, and is again in position to accumu late condensate. . Tilting traps are necessarily intermittent in operation, except that once the trap is in the discharge position, it will discharge condensate continuously as long as the flow of condensate is sufficient to overcome the balance of the counterweight. This type of trap employs packing around the trunnion and valve stem in order to prevent the loss of steam and condensate. Tilting traps are used for draining laundry and dry cleaning equipment, steam cookers, drips from steam mains, steam separators and purifiers and other equipment. They are made in sizes from 1 to 3 in., and for pressures varying from 0 to 250 pBig. Fig. 31 illustrates a type of tilting trap which is in use at the present time. Lifting Trapt. This type of trap is an adaptation of the upright bucket trap. It has the added feature of an auxiliary pressure inlet through which steam is intro duced at a pressure higher than that of the trap inlet pressure.. This high pressure, steam forces the condensate to a point above the trap, and against a back pressure higher than that which is possible with normal steam pressure. Lifting traps are made in sizes from one to 3 in., and for pressures ranging from vacuum to 150 psig. Fig. 32 illustrates a trap of the lifting type. Boiler Return Trap or Alternating Receiver. This device is not actually a steam trap in that it is not used to trap or hold steam, but is an adaptation of the lifting trap. It is used for returning condensate to a low pressure boiler, when due to excess pressure, the condensate cannot flow to the boiler by gravity without flooding the re turn mains, and endangering the boiler by permitting it to go dry. The boiler return trap is a vessel into which condensate alternately collects and is discharged into the boiler by boiler steam pressure. These traps are available jn Bizes from 1$ to 2$ in., and for pressures varying from 0 to 100 psig. A typical boiler return, trap is shown in Fig 33, and a typical connection to a low pressure heating system is indicated m Fig. 13. Steam Trap Installations The following general rules should govern the installation of traps of all types: 1. A vertical drip as long as possible and a strainer should be installed between the trap and the apparatus it drains. Exceptions to this rule are the installation of ther Steam Heating Systems 529 Acceptable method Preferred method Fig. 37. Methods of Taking Branch from Main AngaB Constant 5.126 213 30* 2JXO 45 'l.*l 60* 1.155 To find length Cmultiply A by constant lor angle B - Fig. 38. Constants for Determining Length of Offset Pipe N Fig. 39. Dirt Pocket Connection mostatic traps in radiators, convectors and pipe coils. These, in general, are at tached directly to the units without strainers. 2. Whenever it is necessary to maintain in continuous service, apparatus which is to be drained, it is advisable to install a gate valve on each side of the trap, and a valved by-pass around the trap, so that the trap may be removed and repaired and condensate drained through the throttled by-pass valve. 3, Whenever it is necessary to install traps for lift service, as when the condensate must be discharged to a main located above the trap or where the trap must discharge against a definite back pressure, a check valve and a gate valve should be installed on the discharge side of the trap, the check valve to prevent continuous pressure on the discharge side of the valve, and the gate valve to shut off pressure in case the trap is removed for service or repair. DRIPS A steam main in any type of steam heating system may be dropped to a lower level without dripping if the pitch is downward with the direction of steam flow. Any steam main in any heating system can be elevated if dripped. Fig. 34 shows a connection where the steam main is raised and is drained to a wet-return. If the elevation of the low point is above a dry-return, it may be drained through a trap to the dry-return in two-pipe vapor, vacuum and sub-atmospheric systems. Horizontal steam pipes may also be run over obstructions without a change in level, if a small pipe is carried below the obstruction to care for the condensate (Fig. 35). Horizontal return pipes may be carried past doorways and other ob structions by using the scheme illustrated in Fig. 36. It will be noted that the large pipe, in this case, runs below the obstruction, and the smaller one over it. Branches from steam mains in one-pipe gravity steam systems should use the 'preferred connection shown in Fig. 37, but where radiator conden sate does not flow back into the main, the acceptable method shown in the same figure may be used. This acceptable method has the advantage of Fig. 35. Looping Main Abound Beam Fig. 36. Looping Dbt Return Main Around Opening Fig. 40. Dripping End of Main into Wet Return Fig. 41. Dripping End of Steam Main into Dry Return Fig. 42. Dripping Heel of Riser into Dry Return 530 CHAPTER 21 1956 Guide giving a perfect swing joint when connected to the vertical riser or radia tor connection, whereas the preferred connection does npt give this swing without distorting the angle of the pipe. Runouts are usually made about 5 ft long to provide flexibility for movement in the main. Offsets in steam and return piping should preferably be made with 90-deg ells, but occasionally fittings of other angles are used, and in such cases the length of the diagonal offset will be found as shown in Fig. 38. Dirt pockets, desirable on all systems employing thermostatic traps, should be so located as to protect the traps from scale and sludge which Steam Heating Systems j?iunout above floor ]L WaO Une. Swing'/'?fr'flL.... ....til.................. f jo'iinn*t '-A,l J''~Runotlt below Boor PLAN 531 FITTINGS TO B 125 LBS. UP TO BO LBS. PRESS.- 4"SIZE Fig. 43. Flash Leg Installation for 80 psi Maximum Steam Working Pressure Table 13. Dimensions Applying to Fig. 43 Traps Con densate per Hr., Lb at 70 Psi HP Side asc 03 (*! Cl cc gs Cm O Oh LP Side cc c oi g. tc g Cm O CU *200 2 4 21-80 3 300 1 A 31-70 2 4 700 i A 31-70 2 4 1500 i A 61-80 1 2500 1 A 61-80 U A 0-20 A 0-15 i 0-15 1 0-15 1 0-15 4000 n H 61-80 2 1A 0-15 8000 2 A 61-80 21 1A 0-15 15000 21 A 61-80 21 1A 0-15 JPS 4 4 4 5 8 10 12 16 Plate A B c D E F G Thick Ft. In. In. In. In. In. In. ness, In. 3 6 8 3 2 1J 2 i3 6 8 3 j i} 3 6 8 3 1 i} 1 4 6 10 4 l ii l 5 6 10 4 i 2 H 6 6 12 5 U 21 il 6 6 12 5 2 3 2 6 8 14 6 3 3 3 __ ___ Fig. 44. One-Pipe Radiator Connections will interfere with their operation. Dirt pockets are usually made 8 in. to 12 in. deep, and serve as receivers for foreign matter which otherwise would be carried into the trap. They are constructed as shown in Fig. 39. On vapor systems where the end of the steam main is dripped down into the wet-return, the air venting at the end of the main is accomplished by an air vent passing through a thermostatic trap into the dry-return line as shown in Fig. 40. On low pressure or vacuum systems, the ends bf the steam mains are dripped and vented into the return through drip traps opening into the return line. A float and thermostatic type trap is recommended for dripping steam mains and risers as indicated in Figs. 41 and 42. The dripping of high pressure mains, or of equipment using high pressure steam into low pressure or vacuum returns, is generally accomplished by the use of a flash tank or flash leg into which the high pressure trap is arranged . to discharge. This tank provides the required space for the flashing from high temperature condensate to low pressure steam to take place. The low pressure steam therein generated is passed directly to the low pressure steam mains, and the condensate is discharged through a second trap to the Fig. 45, Two-Pipe Top and Bottom Fio. 46. Two-Pipe Connections to Opposite End Radiator Connections Radiator Hung on Wall 532 CHAPTER 21 1956 Guide Steam Heating Systems 533 Fig. 47. Typical Convectob Connections Fig. 48. Typical Connections to Finned Pipe Convector low pressure or vacuum return. A typical arrangement of a flash leg, with sizes required for varying capacities, is given in Fig. 43. CONNECTIONS TO HEATING UNITS Riser, radiator and convector connections must not only be properly pitched at the time they are installed, but must be arranged so that the pitch will be maintained under the strains of expansion and contraction. These connections may be made by swing joints which permit the ex pansion or contraction to occur under heating and cooling without bending of pipes. To take care of expansion in long risers, either expansion joints of commercial construction or pipe swing joints are used. Anchoring of pipes between expansion joints is desirable. Two satisfactory methods of making runouts for one-pipe systems -for either the up-feed or the down-feed type are shown in Fig. 44. Where the vertical distance is limited and the runouts must run above the floor, the radiator may be set on pedestals or raised by means of high legs. A method of connecting a unit heater to a one-pipe steam heating system is illustrated in Fig. 2. Fig. 51. Typical Connections, to Finned Tube Blast Heating Coils of the Steam Distributing or Non-Freeze Type Typical two-pipe radiator connections are shown in'Figs. 45 and 46. While these show top inlet supply connections which are preferred, it: is also possible to connect the supply to the bottom of the radiator.' Short radiators may he connected with top supply and bottom return on the same end. A typical method of connecting convectors is shown in Fig. 47. Some? times the supply valve is omitted on convector connections, and a damper is supplied in the outlet grille for heat control. A typical connection for finned pipe convectors is shown in Fig. 48. Typical connections to blast heaters are shown in Figs. 49, 50, and 51. Fig. 52 shows a typical return and connection for blast heaters connected to high pressure systems. A typical two-pipe connection to a unit heater is indicated in Fig. 53. CONTROL VALVES Gate valves are recommended in all cases where service demands that the valve be either entirely open or entirely closed, but they should never Fig. 49. Typical Connections to Finned Fig. 50. Typical Connections to Tube Blast Heating Coils Arranged Finned Tube Blast Heating Coils for Series Flow of Air Arranged for Parallel Flow of Air Fig. 52. Typical Return Connections to Finned Tube Blast Heaters with High Pressure Steam J 534 CHAPTER 21 1956 Guide '-M. CHAPTER 22 HOT WATER HEATING SYSTEMS Available Head; Friction Loss; Classification; System Design; Examples of Piping Design; One-Pipe Gravity, One-Pipe Forced Circulation, Two-Pipe Gravity, and Two-Pipe Forced Circulation Systems, Expansion Tanks, Installation Details, Zoning of Systems, High Temperature Systems be used for throttling. Angle globe valves and straight globe valves should be used for throttling in such-cases as by-passes around pressure reducing valves or on. by-passes around traps. . REFERENCES ' 1 A.S.H.V.E. Research Report No. 954--Condensate and Air Return in Steam Heating Systems, by F. C. Houghten and J. L. Blackshaw (A.S.H.V.E. Transac tions, Vol. 39; 1933, p. 199). 1 Pipe size tables in this chapter have been compiled in simplified and condensed form for the convenience of the user; at the same time all of the information contained in previous editions of The Guide has been retained. ' 's A:S.H:V.E. Standard Code for Testing and Rating Return Line Low Vacuum Heating Pumps (A.S.H.V.E: Transactions, Vol. 40, 1934, p. 33). '' its Ik AHEATING system is called a hot water system if water is used to convey heat by flowing through pipes connecting a boiler or water heater with radiators, convectors or other suitable heat dispensing means. There are two types: the gravity system in which the water flows by virtue of thermo-syphon action, and the forced system in which a pump, usually driven by an electric motor, sometimes by a steam turbine or other means, maintains the necessary flow. Most panel heating systems (see Chapter 24) fall into the category of forced hot water systems, and the design procedures pertaining to pipe sizing and friction contained in this chapter are largely applicable to such systems. Historically, the gravity system is much the older, and many such sys tems have been in satisfactory operation for several decades. Operation depends on the difference in density of the water due to difference in tem perature in the flow and return pipes. The available head is therefore limited, and the pipes must be ample in size to permit adequate flow of water. In the forced system, the pipes, valves and fittings can be much smaller, with a resultant saving in the cost of installation, since the available head is limited only by consideration of economy in pumping the water. With the forced system, higher boiler temperatures and automatic control of the pump or circulator make possible the use of indirect water heaters with hot water systems when that is desirable. (See Chapter 49.) AVAILABLE CIRCULATION HEAD The available head in a gravity circulation system may be found from the equation: K = PJ-rrr x 2.31 x 12,000 144 (1) where A, = available head per foot of height, milinches (1 milincb = 1/1000 of 1 in of water). Pi = average density of flow water, pounds per cubic foot, pi = average density of return, pounds per cubic foot. 144 = square inches per square foot. 2.31 = height of water column equivalent to 1 psi, feet. 12,000 = milinches equivalent of 1 ft of water column. _ The available head may also be found from Fig. 1. For example, at a now temperature of 200 F and a 35 deg drop, and with the mains located 4 ft above the center line of the boiler, the available head is 600 milinches. this is found by following the 200 F flow riser line in Fig. 1 to its intersec tion with the 165 F return riser line, and then reading, horizontally, a head 535 536 CHAPTER 22 1956 Guide of 150 milinches per foot, or 600 milinehes for 4 ft. If the first floor radi ators are located 3 ft above the mains, second floor radiators 12 ft above the mains, third floor 21 ft, and fourth floor 30 ft, the heads are 450, 1800, 3150, and 4500 milinches, respectively. In forced circulation systems flow is produced mechanically by means of a pump driven by electricity, steam, or other source of energy. As Hot Water Heating Systems Table 1. Iron and Copper Elbow Equivalents* 537 Fitting Iron Copper Pipe Tubing Fitting Iron Copper Pipe Tubing Elbow, 90-deg......................... 1.0 Elbow, 45-deg......................... 0.7 Elbow, 90-deg long turn----- 0.5 Elbow, welded, 90-deg.......... 0.5 Reduced coupling.................. 0.4 Open return bend.................. 1.0 Open gate valve...................... 0.5 Open globe valve...................I 12.0 1.0 0.7 0.5 0.5 0.4 1.0 0.7 17.0 Angle radiator valve. Radiator or convector Boiler or heater .... Tee, per cent flowine through branch:1* 100....................... 50........................ 25....................... 2.0 3.0 3.0 T ft 4.0 16.0 3 ft 4 ft 4.0 }2 4.0 20.0 Cn.mchS diridld byTs " " el0ow " Applies to conditions of flow in hot water heating system.'' > FRICTION ------- MILINCHES PER FOOT OF PIPE Fig. 1. Heads Resulting from Temperature Difference (Gravity Systems) forced circulation velocities are higher than those in gravity systems, and as the friction in a heating system varies almost as the square of the velocity, a given error in the calculation or assumption of the velocity is less im portant in a forced circulation system than in a gravity circulation system, and, consequently, it is easier to design a satisfactory forced circulation system than a satisfactory gravity circulation system. FRICTION LOSS Values of friction loss due to flow of water in the various parts of a heat ing system must be known in order to design either gravity or forced circu lation systems. The friction loss of fittings is customarily expressed in equiv- r*ojfimndd factum when temperature drop isueosthKejrmtphearnaiu2r0e dceugn. emrenncelUbpetlwyeSenacftlouwS ahne return risen, conveyed by Vactmd temp, drop/ and read the corresponding friction. Si Si !' !I; Hr.i!' |-If; i jjj i -t;! 'll !iI - `,1n1 Ijl'l' 1956 Guide Table 2. Heat-Cakbying Capacity op Standard Black Pipes with Tempehature Deop of 20 Dbg* Nominal Pipe Sizes % in. to IS in., and Friction 4 to 800 milinches per foot (A = Capacity, Mbh. B = Velocity, inches per second) (One milinch equals 0.001 in.) ' Mxijnch Frio- Nominal Pipe Size., Inches TION Lc iS PER Foot or Pipe w v> H 1 tx 2 2H 3 3X . 4 5 6 8 10 12 4 A 0.75 1.35 2.85 5.4 11.3 17.0 33.0 53.1 95 141 197 363 596 1250 2320 3730 B 1.6 1.7 2.1 2.4 2.9 3.2 3.8 4.3 5.0 5.5 6.0 7.0 7.9 9-6 11 12 6 A 0.9 1.7 3.6 6.75 14.0 21.2 41.3 66.4 119 176 248 456 748 1570 2920 4690 B 1.8 2.1 2.6 3.0 3.6 4.0 4.7 5.3 6-2 6.9 7.5 8.8 10 12 14 16 B8 A 1.05 2.0 4.2 7.9 16.4 24.8 48.4 77.9 140 207 291 .535 879 1850 3440 5520 2.1 2.5 3.0 3.5 4.2 4.7 5.6 6.3 7.3 8.0 8.8 10 12 14 17 19 10 A 1.2 2.2 4.7 8.9 18.6 28.0 54.7 88.1 158 234 329 605 997 2100 3910 `6270 B 2.4 2.8 3.4 4.0 4.8 5.3 6.3 7.1 8.2 9.1 9.9 12 13 16 19 27 13 A 1.36 2.45 5.2 9.8 20.5 31.0 60.4 97.4 175 259 364 67J 1100 2320 4330 6950 B 2.7 3.1 3.7 4.4 5.3 5.9 6.9 7.8 9.1 10 11 . 13 15 18 21 24 14 A 1.45 2.65 5.65 10.7 22.3 33.7 65.8 106 190 282 397 731 1200 2530 4730 7590 B 2.9 3.4 4.1 4.8 5.7 6.4 7.6 8.5 9-9 11 12 14 16 20 23 26 16 A 1.55 2.85 6.05 11.5 24.0 36.3 70.8 114 205 303 428 787 1300 2730 5100 8190 B 3.1 3.6 4.4 5.1 . 6.2 6.9 8.1 9.7 11 12 13 15 17 21 25 . 28 20 A B 1.75 3.25 6.85 13.0 27.1 41.0 80.0 129 232 344 484 m 1470 3100 5790 9300 3.5 4.1 4.9 5.6 7.0 7.7 9.2 10 12 13 15 17 20 24 28 32 25 A 2.0 3.65 7.75 14.7 30.6 46.3 90.5 146 263 389 548 1010 1670 3510 6570 10560 B 4.0 4.6 5.6 6.5 7.9 8.8 10 12 14 15 17 19 22 27 32 36 30 A 2.2 4.0 8.55 16.2 33.8 51.2 100 162 290 430 607 1120 1850 3900 7280 11710 B 4.4 5.1 6.1 7.2 8.7 9.7 11 13 15 17 18 22 25 30 35 40 35 A 2.35 4 4 9.3 17.6 36.8 55.7 109 176 316 469 661 1220 2010 4250 7940 12780 B 4.7 5.5 6.7 7.9 9.5 11 13 14 16 18 20 23 27 33 39 44 40 50 60 70 80 100' 150 200 300 400 500 600 800 A B A B A B A B A B A B A B A B A B A B A B A B A B n2.55 4,7 10.0 18.9 39.6 59.9 117 . 5.1 5.9 7.2 8.4 10 13 2.85 5.3 11.3 21.4 44.7 67.7 133 5.7 6.7 8.1 9.5 12 13 15 3.15 5.85 12.4 23.6 49.4 74.9 147 6.3 7.4 8.9 11 13 14 17 3.45 6.35 13.5 25.7 53.8 81.4 160 6.9 8.0 9.7 11 14 15 . 18 3.7 6.8 14.5 27.6 57.9 87.6 172 7.4 8.6 10 12 15 17 20 4-15 7.7 16.4 31.1 65.4 99.0 194 813 9.7 12 14 17 19 22 5.2 9.6 20.4 38 8 81.6 124 243 10 12 15 17 21 23 28 6.05 11.2 23.9 45.4 95.5 145 285 12 14 17 20 25 27 33 7.5 13.9 29.7 56.6 119 181 356 15 18 21 ?5 31 34 41 8.75 16.2 34.7 66.2 140 212 417 18 21 26 30 36 40 48 9.85 18.3 39.2 74.8 158 239 471 20 23 29 33 41 45 54 10.9 20.2 43.2 82.5 174 264 521 22 26 32 37 45 50 60 12.7 23.6 50.5 96.5 204 310 610 25 30 37 43 52 59 70 189 341 605 712 1320 2170 4580 8570 13780 15 18 20 22 25 29 85 42 47 214 386 572 807 1490 2460 5190 9720 15650 17 20 22 24 29 33 40 47 54 238 427 633 893 1650 2730 5760 10780 17360 19 22 25 27 32 36 44 52 60 258 465 690 973 1800 2970 6280 11760 16950 21 24 27 29 35 40 48 57 65 278 500 743 1050 1940 3200 6770 12690 20440 22 26 29 32 37 43 52 62 314 566 840 1190 2200 3630 7680 14400 23200 25 30 33 36 42 48 59 70 393 709 1050 1490 2760 4560 9650 18120 29220 32 37 41 45 53 81 74 88 461 832 1240 1750 3240 5360 11350 21320 34100 37 43 48 53 62 71 87 104 fi(577 1040 1550 2190 4060 6730 14270 26830 43300 4f 6( 71 9( IK 131 676 1220 1820 2570 4780 7910 16790 31580 51000 54 64 71 78 92 105 129 154 n765 1380 2060 2910 5410 8970 19040 35840 57880 62 80 88 104 119 147 174 846 68 1530 80 2280 89 3220 97 5990 115 9930 21100 39740 64210 132 162 193 221 992 80 1790 94 2670 104 3780 114 7030 135 11670 155 24820 191 46780 228 75620 .00 For other temperature drops the pipe capacities may be changed correspondingly. For example, with i temperature drop oi 30 deg. the capacities ip this table are to be multiplied by 1.5* Hot Water Heating Systems 539 alent number of elbows of the same pipe size which would have the same friction loss. An elbow is assumed to have the same friction loss as a straight pipe having a length equal to 25 diameters (nominal) of the elbow. The resistance of various types of fittings expressed in equivalent elbow resistance is shown in Table 1. The friction loss in pipes and tubing may be determined from Fig. 2 and Table 2 for black iron pipes, and from Fig. 3 and Table 3 for type L copper tubing. The scale at bottom of Figs. 2 and 3 is the heat carrying capacity in thousands of Btu per hour based on a 20 deg temperature difference between flow and return risers. In.order to use the scale for other than 20 deg difference, refer to footnote under Figs. 2 and 3. If the flow in a given pipe is calculated in pounds per hour, it may be FLOW OF WATER IN GALLONS PER MINUTE Fig. 3. Friction in Type L Copper Tubing T,. of chart is based on 20 deg temperature difference between flow and return risers. Y ana Inchon when temperature drop is other than 20 deg, multiply the actual heat conveyed by Victual temp, drop/ "d read corr<sPonding friction. converted to corresponding gallons per minute by dividing the flow in Pounds by 500, after which the friction may be found by entering Figs. a and 3 at the top scale reading which corresponds to the flow in gallons per minute as determined. . Orifices drilled in plates inserted in pipe unions are convenient means or introducing friction, where required to balance various circuits. The notion losses caused by various sizes of orifices are given in Table 4. CLASSIFICATION OF SYSTEMS Gravity or forced systems of piping may be classified according to piping rrangement and type of circulation as shown m Table 5. Row and V*1? ma(n Piping (gravity systems) for one-pipe, two-pipe direct return, uu two-pipe reversed return systems are shown in Figs. 4, 5, and 6, re- 540 CHAPTER 22 1956 Guide' J~ Table 3. Hbat-cabbying Capacity op Type L Copper Tubing . . with Temperature Drop of 20 Deo* ( . Nomiwql Tube Sizes f in. to 4 in., and Friction 60 to 720 milinches per foot. (A = . Capacity, Mbh. B = Velocity, inches per second) (One milinch equals 0.001 in.) Mn.ncru FRICTION LOSS PEE FOOT OF TOBB Nominal Tube Size, In. 720 600 480 360 300 240 180 150 120 90 75 60 A HB H H H 1 B A B A B A B lK 1W : 2H 4 B A B A B A B A B A B A B ' 8.9 7.8 23.6 20.8 16.7 15.0 27.6 24.8 29.0 . 26.0 32.2 28.8 43.5 39.0 34.6 31.1 93 84 43 39 160 145 49. 45 260 56 240 52 560 510 70 64 1100 89 930 75 1650 1500 94 85 2500 2250 105 94 3600 3200 116 103 7.0 5.9 18.6 15.7 5.4 14.4 4.7 < 12.5 13.0 21.5 11.2 18.5 10.0 16.5 8.7 14.4 22.5 19.0 17.5 15.0 25.0 21.1 19.4 16.6 34.5 27.6 29.0 23.1 28.5 21.1 23.0 18.3 74 63 ' 57j 50 34 29 27 23 128 107 39 33 97 .30 85 26 206 175 160 140 ; 45 38 35 30 450 380 340 300 56 47 42 37 820 700 630 55066 57 51 44 1300 1100 74 62 990 '860 56 49 2000 1750 1500 1320 84 73 63 55 2800 2400 2150 1900 .90 77 69 61 3.9 3.6 3.1 10.4 9.6 8.2 7.5 6.6 12.4 10.9 5.6 9.3 13.0 11.5 10.0 14.4 12.8 11;1 19.6 15.6 17.5 13.9 15.0 12.0 42.5 38 34 20 18 16 73 65 57 22 20 18. 118 106 26 23 93 20 250 225 195 31 28 24 470 420 ` 370 38 34 30 730 650 41 . 37 565 32 iioo- 1000 860 46 42 36 1600 1440 1250 51 46 40 2.7 2.3 2.1 7.2 6.1 .5.6 5.0 . 4.5 3.9 8.3, 7.4 6.4 8.5 7.6 6.7 9.4 8.4 7.4 13.0 10.4 12.0 9.6 10.5 8.4 28.5 13 26 23 12 11 48.5 15 44' 39 .14 12 79 ' 71 62. 17 15 13 170 150 133 21 19 17 310 280 250 25 23 20 480 430 375 27 24 730 660' 580 31 28 1150 37 950 840 31 * For other temperature drops the pipe capacities may be changed correspondingly. For example, with temperature drop of 30 deg the capacities Bhown in thi6 table are to be multiplied by 1.5. spectively. These figures would also illustrate forced circulation if a pump or circulator were shown in the return line at the boiler. One-pipe gravity systems require very precise design owing to the small circulating head available. Also, circulation in them is slow, and .tem perature drop is large toward the end of the main, and consequently these systems are usually considered impractical. ' One-pipe forced systems compared with gravity systems provide mbre rapid circulation, with consequent smaller temperature drop in mains and more uniform water temperature in all radiators, and are therefore preferred. Special flow and return fittings are available for improving the circulation to risers. Two-pipe systems have separate flow and return mains. If the return main is.direct as shown in Fig. 5 the radiator at the end of the system has Pi Pi Pi, . Pj P, R ir Fig; 4. One-Pipe System Fig. 5. A Two-Pipe Direct Return Fig. 6. A Two-Pip Reversed Return System Hot WaferiHeating Systems Table 4: Friction, (in Milinches) op Central Circular Diaphragm Orifices' . ' in Unions . .... .. (One milinch equals 0.001 in.) ' '' - - - - V Diameteb of (Inches) Velocity of Watch in Pipe in Inches peb Second ........................................ :-- - ' ' " .......... .........................- 102 3 4 f 6 | :. 12. %-in. Pipe . . 3ft .' ' . ' ~ 0.25 0.30 0.35 0.40 0.45 0.50 0.55 1300 650 330 170 2900 1450 740 380 185 5000 2500 1300 660 330 155 75 11,300 5700 2900 1500 740 350 170 20,800 10,400 5200 2600 1300 620 300 32,000 16,000 8000 4000 2000 970 480 45,000 23.000 57,000 12,000 26,000 6800 13,000 2900 6500 1400 3200 700 ! 1600 47,000 24,000 12,000 5700 2800 53,000 27,000 13,000 6400 1-in. Pipe 0.35 900 2000 3500 7800 14,000 22,000 32,000 0.40 . . -460*: "1000 rl800. .' :40<j0. :?72D0: 12;000. 17JO0D .37,000: .65,000 - 0.45 270 - 570 1000 2300 4100 6400 9300 21,000 37,000 0.50 . 160 330 580 1400 2300 3700 5400 12,000 22,000 50,000 0.55 190 . 330 750 1300 2200 3000 7000 13,000 28,000 0.60 200 440 800 1300 1800 4200 7400 17,000 0.65 120 260 460 . 720 1100 2400 4300 10,000 i 14-in. Pipe 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.55 0.60 0.65 0.70 .0.75 0.80 0.85 1000 660 430 280 190 850 600 400 260 180 2250 ' 4000 1450 2600 950 1700 630 1100 420 750 285 510 190 330 8900 5800 3800 2500 1700 1150 750 ie'ooo 10,400 6800 4400 3000 2000 1300 25,000 46,400 10,500 6900 4700 .3100 2100 36,000 23,000 15,000 10,000 6700 4500 3000 53,000 34,000 22,000 15,000 10,000 6700 60,000 40,000 27,000 18,000 12,000 60,000 40,000 26,000 13^`in. Pipe 1900 1300 850 600 400 300 200 3300 2300 1500 1100 760 540380 7400 5400 3600 2600 1800 1200 860 13,000 8600 7200 4400 3000 2200 1600 21,000 16,800 10,400 7000 5000 3200 2300 30,000 21,000 14,000 10,000 7000 5000 3000 50,000 30,000 21,000 14,000 10,200 7800 53,000 39,000 28,000 19,000 13,000 45,000 30,000 2-in. Pipe 0.70 0.80 0.90 1.00 1.10 1.20 1.30 890 1850 3500 470 975 1800 255 560 1000 160 340 610 214 375 195 7400 3900 2200 1320 850 460 275 14,000 7400 4200 2520 1600 950 525 22,300 11,700 6500 4000 2500 1360 980 33,000 17,000 9500 5800 3700 19101375 37,000 20,500 12,500 7900 4200 3100 38,000 23,000 14,000 8100 4400 49,000 30,000 16.800 8850 Nate.--`The losses of head for the orifices in the lH-in. and 2-in. pipe were calculated from these in the **aller pipes, the calculations being based on the assumption that, for any given velocity, the Iosb of head, a function of the ratio of the diameter of the pipe to that of the orifice. This had been found to be prac- true in the tests to determine the loeses of head in orifices in $-in., 1-in., and lK-in. pipe, conducted by the Texas Ei>g?muring Experiment Station, and also in the tests to determine the losses of head in ori fices in 4-in., 6-in.,and 12-in. pipe, conducted by the Engineering Experiment Station of Unxoertity of Winoie, (Bulletin 109, Table 6, p. 38, Davis and Jordan). 542 CHAPTER 22 1956 Guide the longest supply and longest return piping. The lengths of circuits to the various radiators may be equalized by using a reversed return main (see Fig. 6). In some cases reversed return mains require no more piping than direct return systems. With gravity circulation and direct return piping it is necessary to design the longest circuit for the available circulating head, and to obtain the same resistance in all other circuits by proper selection of pipe sizes, by addition of fittings, or by use of orifices. When a reversed return system is used, it is usually found that very little adjustment is required to attain uniform distribution to all radiators. . Forced circulation in two-pipe systems, because of increased available circulating head, permits design for higher velocities with a consequent reduction in pipe sizes. The increased velocity also shortens the heating-up period and facilitates control of circulation. Reversed return mains are also advantageous in forced circulation systems, in equalizing piping re sistance to all heating units. Table 5. Classification of Hot Water Heating Systems Piping Arrangement One-Pipe Two-Pipe Direct Return Two-Pipe Reversed Return Type of Circulation Gravity Forced Gravity Forced , Gravity Forced Expansion Tank Open Open Closed Closed Open Open Closed Closed Open Open' Closed Closed PIPING SYSTEM DESIGN In designing hot water heating systems certain assumptions are usually made for the purpose of simplification as follows: 1. Water temperature drop is assumed to be 30 to 35 deg for gravity systems and 20 deg for forced circulation systems. These values usually result in economical design but, particularly in large forced circulation systems, it is necessary to take into aceount the cost of pumping the water required at various velocities in relation to the annual charges in the capital cost of the system. 2. Water velocities in forced systems in excess of 4 fps in piping of 1)4 in. I. D. or less are likely to cause disturbing noises in residences. In factories or in instal lations having larger pipe sizes, velocities as high as 8 or 8.5 fps are not uncommon. 3. Design outlet water temperatures in gravity systems are generally selected be tween 140 and 200 F (with the average approximately 180 F); while forced circulation design temperatures vary from 170 to 220 F, although higher temperatures can be used if the pressure in the system corresponds. ; 4. For forced circulation systems, the allowable friction loss, which is based upon the available circulating head, is determined partially by the characteristics of the pumps available. 5. Forced hot water system friction should usually be held between 600 and 250 milinches per foot. Above 600 milinches high velocities would be encountered, and below 250 milinches circulation would become too slow, so that much of the rapid response expected from forced circulation would be lost. Hot Water Heating Systems 543- The water to be circulated is .. ' ;/ ... W = If/(C a t) " (2) where - - ' . . .. .. . W -- weight of water, pounds per hour [gallons per minute = W/(8 X 60)1, H = heat required, Btu per hour. ; -. .......... : ; C -- specific heat of water (= 1). :: . At -- drop in temperature between supply and return, Fahrenheit degrees. . ; . The following graded series of examples of the design of hot water piping systems will illustrate the fundamental principles and methods. The differences between reversed return and direct return systems are shown, and the methods of balancing the several radiators or circuits are illustrated. A simple gravity system is shown in Fig. 7, and an elementary forced circu lation system is diagrammed in Fig. 8. ' Fig. 7. Gravity System Fig. 8. Forced Cir culation System Elementary Gravity System Fig. 9. Determina tion of Required Temperature Difference Example 1: A simple gravity-circulation system is illustrated in Fig. 7 with one radiator that is giving off heat at the rate of 20,000 Btu per hr or 20 Mbh. The boiler imparts heat to the water at the same rate, and the water circulates at a uniform Vfilnoi + YP ------------ ?_ -......................... ' valve and a totaF of 24 ft of pipe. Soi-ufton: With the average water temperatures of 200 and 180 F in the supply and return risers, respectively, the head will be 90 milinches per foot of water column. This head may be found from Fig. 1. Since the center of the j thp rmnlc----flL-L.fl- - ' * ~ ' inction ot 1 It of 1 in. pipe is found from Fig. 2 to be about 46 milinches at 20 jjibh, and the corresponding velocity 9 in. per second. Note that all values in Fig. 2 are based on a temperature difference of 20 deg. . Similarly, if a 1\ in. pipe were to be used, the friction head would be about 12 milinches per foot, and the corresponding velocity about 5 in. per second, from Fig. 2. , To find the friction in the elbows, boiler, radiator, and valve, Table 1 is used, and the .entire circuit is found to be equal to 10 elbow-equivalents plus 24 ft of pipe, ^ach elbow-equivalent is equal to a pipe length of 25 times the nominal diameter. Ihen the equivalent lengths of straight pipe are 45 ft of 1 in. pipe or 50 ft of H in'. PJpe. In many cases, it is sufficiently accurate to add 50 percent to the total pipe length to correct for resistance of fittings. ... Hence, if 1 in. pipe is used, the friction of the circuit will be 45 X 46, or 2070 mil- 644 CHAPTER 22 1956 Guide inches, and if 11 in. pipe is used, the friction will be 50 X 12, or 600 milinches. A1 in. pipe would, therefore, be too small and a 1} in. pipe too large to permit the desired circulation with a flow-return temperature difference of 20 deg.' If the circuit is of 1 in. pipe, the circulation will take place with a temperature difference greater than 20 deg, and if the circuit is of 11 in. pipe, the circulation will take place with a temperature difference smaller than 20 deg. To find, for example, the temperature difference at which a circuit of 1 in. pipe would transmit the required 20 Mbh, assume the difference to be 40 deg. From Fig. 1, the head available for producing circulation would be 175 milinches per foot, or 1750 for the system, for a temperature drop from 200 to 160 F. The fric tion of the system may be found from Fig. 2; the chart of this figure is based on a tem perature difference of 20 deg; if the temperature difference were 40 deg, the heat conveyed would be twice that shown in the chart. Hence, find 10 Mbh on the lower scale, proceed vertically upward to the intersection with the 1 in. line, and from there to the left scale read 13 milinches per foot. Note that the velocity would then be only about 5 in. per second. The total friction would then be 45 X 13 or 585 milinches. Since the head would be 1750, circulation would take place with a temperature differ ence less than 40 deg. The required temperature difference may be determined by constructing the diagram of Fig. 9, from which it appears that the temperature differ ence with which the 1 in. pipe circuit would function is about 30 deg. Hence, if the Fig. 10. One-Pipe Gravity Circulation Fig. 11. One-Pipe Forced Circulation System (Example 3) System (Example 4) flow riser temperature is 200, the return riser temperature will be 170, and the average water temperature in the radiator about 185 F. Elementary Forced Circulation System Example B: Design a system for the piping arrangement shown in Fig. 8, accord- ingto one of the outlined procedures. The procedure may be as follows: Assume the head developed by the circulating pump and the pipe size and, find the flow-return temperature difference; or, assume the head developed by the pump and the How- return temperature difference, and find the pipe size; or, assume the pipe size and the flow-return temperature difference, and find the head which the circulating pump must develop. . Solution: Assume that the circulating pump will develop a head of 2 ft or 24,000 milinches and that a 1 in. pipe is to be used. The equivalent length of the circuit will then be 45 ft, as in Fig. 7, and the available head will be 24,000/45, or 533 milinches per foot. In Fig. 2, find 533 on the left scale, move horizontally to the intersection with the 1 in. pipe line, and read about 77 Mbh delivered by the pipe (with a velocity of about 35 in. per second) for a temperature difference of 20 deg. Since the circuit is to deliver only 20 Mbh, the temperature difference will be 20 divided by 77 and multiplied by 20, or 5.2 deg. Hence, if the flow riser temperature is 200, the return riser temperature will be about 195, and the average water temperature in the radia tor about 197.5 F. If a i in. pipe were used instead of a 1 in., the equivalent length of circuit would be 35 ft instead of 45; the unit head, 686 milinches instead of 533; the velocity, 27 in. per Hot Water Heating Systems 545 second instead of 35; the temperature difference, 19.5 instead of 5.2; and the average water temperature in the radiator, about 190.5 instead of 197.5 F. If the 1 in. pipe is used for the circuit, the gravity head will be 22 milinches per foot, or 220 for the circuit (Fig. 1, 200 to 195). Since this is only 1 percent of the pump head (24,000 milinches), it may be neglected in the calculation, as was done previously. However, there are cases in which the gravity head is so large compared with the pump head that it should be included in the calculation. The methods just described for the design of the two elementary systems ' are fundamental, and apply to the. design of all hot water heating systems. In every system, however large and complicated, the pipe system must be such that the head forcing the water from the boiler to any one radiator is equal to the friction in that radiator's circuit when the radiator is receiving its proper quantity of hot water, and the system is functioning at a steady rate. Other examples illustrating design of various systems follow. One-Pipe Gravity Circulation System Example S: Select pipe sizes for the one-pipe gravity system having a total load of 67,500 Btu, shown in Fig. 10. Assume: flow temperature 190 F, return temperature 160 F, mains 5 ft above datum plane of boiler, center plane of radiators 4 ft above the mains, length of main 100 ft. Solution: From Fig. 1 the available circulating head for 190 F flow and 160 F return temperature is 126 milinches per foot of height. The available circulating head for design of the main is therefore 5 X 126 = 630 milinches. The measured length of main, plus 50 percent added for resistance of fittings, equals 150 ft equiva lent length. . _ The main can then be designed for a friction loss of 630 + 150 = 4 milinches per foot. From Table 2 at 4 milinch friction loss, a 2 in. pipe will supply 33 Mbh and a 2J in. pipe will supply 53.1 Mbh at 20 deg drop. This is equivalent at 30 deg drop to 49.5 Mbh for 2 in., and 79.6 Mbh for 2J in. pipe. A 2$ in. main will therefore be selected, and the pressure drop will be somewhat less than 4 milinches per foot. The piping from main to radiators is sized in. a similar manner. Assume that water reaches point B, Fig. 10, at 190 F and has a 30 deg drop in the radiator circuit. From Fig. 1 the available head is 126 milinches per foot of height or a total of 4 X 126 = 504 milinches for the circuit (with the radiator 4 ft above the main). The measured length of piping is 11 ft and the fittings add 14 elbow equivalents (which would be equivalent to 22 ft if the pipe size is assumed to be | in.); the equiva lent length is therefore 33 ft. The circuit can therefore be designed for a friction loss of 504 + 33 = 15 milinches per foot. From Table 2 by interpolation a } in. pipe would supply 5.85 Mbh at 20 deg drop or 8.78 Mbh at 30 deg drop. Since the load is 9 Mbh, the J in. size will be satisfactory. The remaining radiator circuits may be sized in a similar manner. Allowance should be made in one-pipe gravity systems for the drop in temperature which occurs in the supply main as the cooler water returns from the radiators. The drop will be in the same proportion to the total drop of 30 deg as the load supplied to any point m the main bears to the total system load, e.g., the temperature at D will be 190 -- * 3o) = I F. At point F the temperature will be 190 -- X 30) = 181 F. . One-Pipe Forced Circulation System Example 4: Select pipe sizes for the one-pipe forced circulation system having a toad of 67,500 Btu shown in Fig. 11. Assume a water temperature drop of 20 deg. l he water temperature does not affect the size of piping, but does affect the radiator sizes required. Solution: The water to be circulated at 20 deg drop will be 67,500 + 20 = 3375 ]b per hour or --= 7 gpm. By reference to manufacturers' pump capacity charts (typical example, Fig.-12), 546 CHAPTER 22 1956 Guide it will be found that a 1 in. pump will deliver 7 gpm against a head of 4^ ft (54,000 milinches). , Since the main from A to O has an equivalent length of 150 ft (1M ft actual length plus 50 percent added for friction loss in fittings), the main may be sized for 54,000/150 = 360 milinches per foot. From Table 2 by interpolation at 360 milinches friction loss and at 20 deg drop, a 1 in. pipe would supply 62,600 Btu per hour, and a 1\ in. pipe would supply 131,600 Since the 1 in. pipe is too small, a 1J in. pipe will be used. Since the 1\ in. pipe offers less than 360 milinches resistance per foot, the velocity of water will increase until the output of the pump and the friction loss are in equi librium at some point on the pump performance curve, for instance, at 10 gpm and a * head of 4 ft or 48,000 -i- 150 = 320 milinches per foot of pipe. The friction loss in the main between flow and return connections to radiators wui be assumed to be 320 mil- inches per foot. In determining sizes for the piping from the main to any radiator, the resistance in the radiator circuit such as B-C (which has a load of 9 Mbh) is made equal to the Fig. 12. Performance Chart for Circulating Pump resistance in the main from B to C which, if there are 3 ft of main between connec tions, is 3 X 320 * 960 milinches. If the total equivalent length of the radiator cir cuit determined by use of Table 1 is 32 ft, the radiator circuit B-C will be sized for a friction loss of 960 + 32 = 30 milinches per foot, for which in Table 2 a f in. pipe is found to supply 8550 Btu per hr, and will be considered ample. Other radiator circuits such as D-E, F-G, etc., can be sized in a similar manner. Two-Pipe Gravity System (with Reversed Return) Example 6: Select pipe sizes for the two-pipe gravity Bystem shown in Fig. 13. The center plane of the highest radiator is 8 ft above the center plane of the boiler. Assume a 180 F flow temperature and a 150 F return temperature. Solution: The piping should be sized so that the frictional resistance at the de sired rate of flow & equal to the available circulating head. From Fig 1 at 180 F flow and 150 F return temperature, the available head is 118 milinches per foot of height or 8 X 118 = 944 milinches total for the highest radiator. The longest circuit from boiler to radiator and back to boiler must therefore have resistance of 944 milinches. The longest circuit (see Fig. 13) is A-D + D-H + n-i containing 38 ft of pipe and, if 50 percent is added for equivalent length of fitting the equivalent length is 57 ft, Hot Water Heating Systems 547 The circuit should then be designed for a friction loss of 944 + 57 = 16 milinches per foot (approximately). The pipe size may be found from Table 2 at 16 milinches per foot, but since the temperature drop is 30 deg, find pipe size corresponding to 20/30 of actual load for each section as follows: Section A-B B-C C-D D-E E-F Load Mbb Size op Pipe pob 16 Milinches peb Foot Section 58 31 20 16 6 1Hw 1M 1 H G-H H-K K-L L-M M-N Load Mbh Size op Pipe pob 16 Miunches peb Foot 11 10 1H 25 1)4 31 1)4 58 m . Piping to the radiators may be sized from Table 2 for the same resistance, 16 milinciiw P1Toot'j but since the temperature drop is 30 deg, find pipe Bize corresponding to 20/30 of actual load for each section as follows: Radi***............................................. Load, Mbh......................................... Pipe size. In................................... 1 U J 02 *3 04 05 06 8 6 6 24 3 } | iU J A hot water heating system will adjust its rate of flow until the friction loss bal ances the available head. It is therefore self-correcting in regard to small errors made in selection of pipe sizes. Two-Pipe Forced Circulation System Example 6: Select pipe sizes for the two-pipe forced circulation reversed return system having a total load of 159 Mbh shown in Fig. 14. Assume a difference of 20 aeg in supply and return water temperature. The total equivalent length of the longest circuit is 180 ft. The gravity circulating head due to difference in temper ature may be disregarded in design. Solution: The water to be circulated is 159,000 + 20 = 7950 lb per hr or 7--^ = 16-5 gPm- From a pump performance chart such as Fig. 12 it is found that 16.5 gpm will be delivered by a 1 in. pump against a 3 ft head (36,000 milinches) or a 11 in. pump against a 4.5 h6ad (54,000 milinches). The longest circuit, including the supply and return main and the longest radiator circuit, is 120 ft and, if 50 percent is added for friction loss in fittings, the equivalent mngth is 180 ft. If the 1 in. pump is used, the piping will be sized for 36,000/180 = 200 miunches per foot, resultingin selection from Table 2 of a 2 in. main for the Section wbich supplies 159 Mbh. The large difference in pump and main size, as well as jne low velocity resulting from the 200 milinch per foot friction loss, indicates that the ,, ,rJ* pumpshould be considered. The design friction loss, if the 1J in. pump is used, can be 54,000/180 = 300 milinches per foot and, at this friction loss, Table 2 will indi cate the pipe sizes for the various sections in Fig. 14 as follows: Section A-B B-C Supply Mbh 159 91 75 63 49 37 16 Pipe Size, In. 1H 1H m 1 1 H Section J-K K-L L-M M-N N-O O-P P-Q Return Mbh 16 28 42 54 75 91 . 159 Pipe 8ize, In. )4 IH 1)4 1H The radiator circuits may also be sized for the same friction loss, 300 milinches per h>ot, using Table 2 as follows: Radiator............................. ................. g\ g2 *3 #4 n- .M--bh.................................................................................. 16 1*2* 14H 1212 * lPe size, In......................................... j | j | 0 Where circuit divides, use | in. branch to *5 and ) in. to 06 radiator. 06 and 06 07 16 I 548 CHAPTER 22 1956,Guide ? , EXPANSION TANKS . Water heated from 40 F. to-200 F expands about 0.04 of the original volume. The expansion tank permits the change in volume of the water in the heating system to take place without producing undesirable stresses due to pressure in ahy part of the system. Expansion tanks may be open, as illustrated in Fig. 15, or closed as shown in'Fig. 16. An open expansion tank has free vent to the atmosphere and consequently, the pressure on the surface of the water ,is always that of one atmosphere. The minimum contents of an open tank should be 0.06 of the volume of the water in the system including that in the boiler, heat transmitters, pipes, etc. This capacity is 50 percent in excess of the actual increase in volume of water :nt VALVE OPEN EXCEPT WHEN DRAINING TANK . CAGE/'"! CLASS OVERFLOW PIPE , EXPAN1SSIIOON PIPE TO , tNStOE CIRCULATING PIPE SEWER ORA IN :/ PUMP-locate in POSITION RECOMMENDED BY MANUFACTURER An Open Expansion Tank Fig. 15 Fig. 16. A Closed Expansion tank Hot Water Heating Systems 549- due to increase in temperature from 40 F to 200 F. The tank should be located at least 3 ft above the highest radiator. /Provision must be made to prevent freezing of the water in the tank as well as in the pipe leading to the tank. ,, .... .......... In accordance with Paragraph H-92 of the ASME Low Pressure Heating Boiler Code 1946: "All hot water heating systems shall be so in stalled that there will be no opportunity for the fluid relief column to freeze or to be accidentally shut off.- If the system is equipped with an open expansion tank, an internal over-flow from the upper, portion of the expansion tank must be provided in addition to an open vent, the internal over-flow to be carried within the building to a suitable plumbing fixture or to the basement." (See Fig. 15.) . : .- When the vent from an open expansion tank is extended through the roof, it should be not less than 4 in. in diameter from a point below the- roof, through and beyond the roof line. This will prevent vapor, which sometimes rises from an expansion tank, from closing the vent during outside freezing temperatures. ; _: .! ' In a gravity circulation system, the pipe to the open expansion tank should be connected to the supply riser from the boiler, so that the air liberated from the water in the boiler will enter the expansion tank. In a forced circulation system, the pipe to an open expansion' taiik should. be connected on the suction.side of the circulating pump,. , A closed expansion tank is sealed against free venting to the atmosphere.. The tank may be above the highest radiator or heat transmitter, or may be below the lowest one. The minimum contents of a closed expansion tank must be such that the expansion of! the water due to increase in temperature will be cushioned against a reservoir of compressed air above, the water level in the expansion tank. The tank must; provide space not. only for the change in water volume, but also for Variations in air volume , within the tank due to changes in air pressure. If the closed expansion tank is below the heat transmitters, the tank: should be larger than if it is above them, and the higher the building, under such circumstances, the larger should be the air capacity in excess of that required for increase in water. volume due to temperature rise. . . The size of an expansion tank for installation in a closed system may be determined by the following formula: , . Pi + 0.434// P, where V = required tank capacity, gallons. E = expansion of water from cold system to flow riser temperature, gallons. . Pi = atmospheric pressure, psia. P, = maximum tank pressure specified for heated system, psia. H -- height of top of filled system above tank, feet. (Note: Top of system open to atmosphere when system is filled.) Example 7: Select a closed expansion tank for basement installation on a system containing 5000 gal and operating at 200 F flow temperature. The static head; due to the height of the system, is 70 ft. The maximum pressure should not exceed 100 psig. Solution: Assume that the system is filled at 40 F. Then . 550 CHAPTER 22 1956 Guide y E = 0.04 X 8000 = 200 gal. Pi = 14.7 psia P, = 100 + 14.7 = 114.7 psia. Substituting these values in Equation 3, _________ 200 V= 14.7 200 = 1000 gal. . 14.7 0.327 - 0.128 14.7 + 0.434 (70) 114.7 The size of a basement-located closed expansion tank should be at least equal to the following: . One story buildings: x = 0.10 V Three story buildings: z = 0.17 V Two story buildings: z = 0.13 V Four story buildings: z = 0.23 V where z =- expansion tank size in gallons. V = water volume in heating system in gallons. -This condition favors, especially in tall buildings, the placing of the closed expansion tank above the highest heat transmitter. Table 6. Required ASME Size of Closed Expansion Tank Sq Ft of Equivalent Direct Radiation Installed Gallon Tank Sq Ft of Equivalent . Direct Radiation Instated Gallon Tank Up to 350 Up.to 450 Up to 650 Up to 1100 18 Up to 1400 40 21 Up to 1600 24 Up to 1800 2--30 30 Up to 2000 2--35 35 Up to 2400 For systems with more than 2400 aq ft ol installed equivalent direct water radiation, the required P"; ity of the cushion tank shall be increased on the basis of one gallon tank capacity per 33 sq ft of additional . equivalent direct radiation. ' . It is common practice to use multiple tank installations on large systems in lieu of one tank, the required capacity of which would be beyond commer- dally available sizes. . Any closed expansion tank located above the heat transmitters of a hot water heating system should be connected by a direct pipe with the flow main leaving the boiler, in order to enable the air to pass easily to the ex pansion tank. In a closed hot water heating system the water under pres sure tends to absorb air at a rate increasing with pressure increase-and . decreasing with temperature increase. . Means must be provided to adjust and to observe the proportion of air within any closed expansion tank. This involves the provision of an air inlet valve, a water gage, and a relief valve. A source of supply of com- ` pressed air for renewing the air cushion is highly desirable, especially in large, high pressure, hot water heating systems where it is inconvenient, if not impracticable, to drain down the water in the system so as to permit introduction of atmospheric pressure air. . In smaller installations, gage fittings on the tank are usually omitted in order to prevent air loss from the tank. Occasional inspection of the tank or the necessity of adding water to the system will then indicate whether air should be added to the tank. The ASME Low Pressure Heating Boiler Code 1946, in paragraph H-92, specifies that provision must be made for draining a closed expansion Hot Water Heating Systems 551 tank without emptying the system. The Code also specifies the minimum sizes of closed expansion tanks based upon the equivalent direct radiation installed. (See Table 6.) ' For every hot water heating system, the designer should calculate the volume of water contained in the radiators, piping system, boiler, etc., in order to select the proper size of expansion tank. The water content of the piping can be obtained from Table 7. For a rough selection of size, however, it is sometimes assumed that 50 percent of the volume of water is contained in the radiators, and that the water content per square foot of radiator heating surface is 0.2 gal for column radiators,- and 0.13 gal for tube type radiators. Another rough method for determining the size of an expansion tank to be located above the highest radiator, is to divide the square feet of radiation by the factor 40 to obtain the required capacity in gallons of the tank. INSTALLATION DETAILS Items that should be considered in the design of piping for a hot water system are: All piping must be so pitched that all air in the system can be vented either through an open expansion tank, radiators or automatic relief valves. When piping must be Table 7. Volume of Water in Standard Pipe Pipe Size, In. 8f Lineal Ft of Pipe Containing 1 Gal 63.1 36.1 22.2 12.8 9.47 Pipe Size. In. 2 2K 3 4 6 6 Lineal Ft op Pipe Containing 1 Gal 6.75 4.02 2.60 1.52 0.96 0.67 run around an obstacle such as a beam, it is advisable to drop the piping below the beam. If looped over the beam, it becomes necessary to provide for venting of air from the high point of the pipe. . When changing the size of horizontal runs of pipe, eccentric fittings should be used to keep the tops of the pipes in line to permit free passage of air along the pipe. All piping must be arranged so that the entire system can be drained. Sections of piping individually valved shall have corresponding drain valves. In large buildings, the piping may be zoned, according to exposure of building, usage of building, or method of control. ' All piping must be installed so that it is free to expand and contract with changes of temperature without producing undue stresses in the pipes or connections. For this purpose it is generally sufficient to allow for a variation in length of 1 in. for 100 ft of pipe. . The pipe system should be designed so that each circuit has its correct friction for balanced water distribution. This may be done by change^of pipe size or change in piping detail. * The connections from the boiler to the mains should be short and direct, to reduce the friction, and should allow for expansion. The mains and branches should pitch up and away from the heater, generally not less than 1 in. in 10 ft. . The connections from mains to branches and to risers should be such that circula tion through the risers will start in the right direction. Hence, in a one-pipe system the flow connection must be nearer the heater than the return connection. In a correctly-designed two-pipe system, the pressure in the flow main is higher than that m the return main, and a slight variation in the distances of the flow and return con nections from the heater is not material; but it is generally best to have the two connections about equally distant from the heater. # v Generally, connections to risers or radiators are taken out of the top of mains at cither 45 or 90 deg from the horizontal plane. 4. Supply connections are usually made at the bottom of radiators so that circulation Wl" not be stopped by accumulation of air, as would be the case with a top supply 552 CHAPTER 22 1956 Guide connection. Short radiators are sometimes connected for top supply and bottom re turn on the same end. When so connected, attention must be given to venting of air from the top of the radiator somewhat oftener than when bottom connections are Unless used as heating surface, all piping, both flow and return, should be insu- Ali large systems should be provided with extra stop and drain valves, suitably located so that parts of the system may be isolated for repairs without making it necessary to dram the water from the entire system. Relief Valve. The ASME Low Pressure Heating Boiler Code requires that all hot water heating boilers shall be equipped with a tested and rated . relief valve having adequate capacity to match the gross output , of the Hot Water Heating Systems 55S pressure in the system to that caused only by the number of floors served by each section. As shown in Fig. 17 a steam boiler can conveniently be used to supply steam to the heat exchanger supplying heated water to each zone. HIGH TEMPERATURE WATER SYSTEM General Considerations The high temperature water system is a form of conveying heat using water as the medium, at temperatures well above 212 F and usually, in cur rent practice, between 300 and 400 F. Water being a most satisfactory heat carrier, will transport heat over long distances with comparatively small line losses and without expensive equipment to maintain or replace. With high temperature water the boiler, instead of generating steam, heats the water to a specified temperature and corresponding pressure. The Fig. 17. Vertical Zoning op Hot Water Heating System in a 12-Story Building (Provision should be made for expansion in each closed circuit.) boiler. In order to comply with the requirement, relief valves must beconnected to.the top of the boiler and a discharge pipe must be connected to the relief valve and so arranged that there will be no danger of scalding attendants. The proper location of the relief valve is shown in Fig. 16- ZONING In large hot water systems, improved control and economy can be achieved by separating the systems into sections or zones (vertical or hori zontal) which can be operated independently of each other. Variations in heat requirement of the different zones, as influenced by the exposure ol the building, solar heat, weather conditions, heat from processes, type ` occupancy, building chimney effect, etc., can readily be compensated lo when heat can be supplied only where needed. In tall buildings, vertical zoning such as shown in Fig. 17 not only pro vides the advantages of control and economy, but also reduces the water Water' System water thus heated is discharged under pressure from the boiler into the sys tem through a circulating pump designed forthehightemperatures involved. The water is thus circulated in a closed circuit from the central station to the extended areas requiring heat and back again to the boiler. In this way the heat, whether for space heating or process work, is distributed ef ficiently and economically since any heat not usefully employed in the sys tem is returned to the boiler for reheating and redistribution. Fig. 18 illustrates an industrial application of a high temperature water system. Fundamental Principles In high temperature water systems water is heated under pressure and its temperature is raised to that corresponding to the pressure imposed, which is above the evaporation point of water at atmospheric pressure. As the temperature of the water rises, the pressure in the system must also be raised to ensure that the pressure is always above the equivalent evapora tion pressure. In modern systems, the pressure can be maintained by using steam or a compressed inert gas. With steam, the steam space within the boiler or the steam space in an external drum or tank, which is also used as an expansion 554 CHAPTER 22 1956 Guide vessel, is utilized to produce the required pressure. By using an inert gas, the desired system pressure can be maintained while the water tempera ture can be regulated to the desired system temperature. The properties of water which must be considered in the design are: 1. Boiling point (t) vs. pressure. (See Fig. 19) 2. Density or specific volume (i1,) vs. temperature. Hot Water Heating Systems 555' hour in lieu of gallons per minute, and the accompanying charts are plotted on this basis. . Design and Economics High temperature water systems differ from conventional systems in that flow main temperatures range from 250 F to 400 F. For flow tempera tures of 250 to 350 F, temperature drops of 80 deg to 150 deg are in common1 Fig. 19. Relation of Saturation Pressure and Enthalpy to Water Temperature 3. Enthalpy or sensible heat {hi)' vs. temperature. 4. Viscosity (ji) us. temperature. Boiling point, specific volume and enthalpy are all discussed in Chapter 3, and the data for the normal temperature pressure ranges are given in Table 3 of Chapter 3. As viscosity is reduced materially with increase in temperature, the consequent reduction in pipe friction should be considered a prime asset of high temperature water systems. (See Fig. 20.) Since the specific heat of water varies only slightly with temperature, it can be ignored in normal design. But as the specific volume varies with temperature, it has been found more convenient in design to use pounds per (Friction given in feet of 62 F water per 100 ft of pipe.) use. For higher flow temperatures the drop will increase to temperatures dependent upon the requirements of the user and can be as high as 200 deg. With these higher drops and consequent decreased flows, pipe sizes are greatly reduced in comparison with those used for conventional hot water systems. Fig. 20 is based on a water temperature of 300 F and shows the friction vs. flow for water in standard good condition schedule 40 steel pipe. The temperature chosen, 300 F, is the norinal mean between flow and return. 556. CHAPTER 22 i 1956 Guide The relation between flow in thousands of pounds per .hour and friction loss in feet per 100 ft of pipe as shown in Fig. 20 is base!d on the Fanning formula (Equation 8, Chapter 4) with values of the density and viscosity of water chosen for 300 F. When corrections are desirable Fig. -21' may be used to correct the; friction loss as found in Fig. 20. . . The friction loss in fittings expressed in equivalent feet of pipe is given in Table 8. . : Gircuits Reprinted by permission from Reference 3. terns and equipment. Converters or heat exchangers are also used for building heating and domestic hot water service systems. Smaller district heating systems pressurized at 12 to 15 psig with dis tribution at 250 F are in common use. In such installations the water is drawn into the individual building systems and recirculated by means of a conventional circulator. Temperature is controlled in each system by a con trol valve at the high temperature line. The control is usually of the indoor-outdoor type, but many variations are. used. Sufficient pressure head is usually available to permit circulation Of the high,temperature water through domestic water heaters for individual supply in each building. Pumps for High Temperature Systems . .. -Circulating pumps form one of the most important components of the system, and are installed in the flow main to increase the static pressure in the main and thereby maintain a satisfactory temperature-pressure rela- Hot Water Heating Systems 557 Table 8. Head Loss in Fittings* {For turbulent flow) Fittings Feet or Same Size Pipe Having Equal Loss: 10 8 6 5 4 3 2}. 2 H H .1 i 4 Globe Valve. ......... 340 270 200 170 135 105 83 70' 55 45 36 28 21 . Gate. Valve. .;.......... 7 5.75 4.5 3.'5 3 2.2 1.7 1:5 T.2 1 : 0:8 0.6 0.5 90 Welding Elbow.... 11 8.5 6.5 5.:5 4.5 3.5 2.6 2.2 1.8 1.5 1.2 0.9 0.7 45 Welding Elbow.... 7 6 4.5 3.6 3 2.4 1.7 1.5 .1.2 l.: 0.8 0.6 0.5 2214 Welding Elbow.. 5; 4 3 2.5 2 1.6 1.3 1.1 0.9 0.7 0.6 .0.5 0.3 Lateralb........................... 26 20 16 13 11 8 6.5 5.5 .4 3.5 2.8 2.2 1.6 Lateral*........................... 17 14 10 8.5 7 5 4 3.5 2.8 2.5 1.8 1.5 1:1 Welding Tee*................. 13 10 8 7 5.5 4 3.2 2:6 2. 1.7 1.4 1.2 0.8 Concentric to Reducers \ 10 8 6 5 4 3 214 2 IX 1M 1 Vi From 10 : 1 V \ T 2.5 3 2.8 8 3.5 \ \ 1.2 2 2.2 2.2 C }NTRAC TEN G -6 10 3.5 \ \ 0.5 1.3 i:s 1.7 5 . . : 12 7.5 1.5 \ \ 0.5 1-2 1.4 1.5 4 ' ` ' 12 ' 9.5 4.5 1.5 V \ 06 .1.2 1.4 1.5 3 ' 10 7 : 5: 1.8 \ N 0 0.8 1 ' T ' . 2'A ;' -7.5 6 3.8 0.7 \" \ 0 0:7 0.8 0.75 2 ': ) 6 5 2.5 0.8 \ '> -\ 0 0.6 0.6 0.6 - 1H . 5 3.8 2.8 9 \ .0 0:5 0.5 0.5 IX 4 3 2 0:3 V \ 0 0 0.3 1 . - . Etila: tGir1G 3 2.5 1.25 0.5 \ \ 0 0.3 : :. .. 2.5 2 1.3 0:5 \ \ 0 "' x 2 1.8 1.5 0.8 \ \ * Compiled from data1 published by Tube Turns, Inc., a Division of the National Cylinder Gas Co. . Used by permission. - . . .. Water deflected'thrgtigh.brancb. . .- . ' . d Water flowing straight through fitting. Fpr eccentric reducers, the values read for concentric reducers must be increased by 331%. Equivalent length of. pipe .having a Fanning friction coefficient of 0.006. tionship and keep the pressure in the system at ail times above the evap oration temperature of the water. It is common practice to use single-inlet single-stage centrifugal pumps operating at 1750 rpm and having water-cooled bearings and glands (al though mechanical seals are coming into use). With pumps of this type the total differential head should not exceed 150 ft. Pumps for high temperature must be specially designed and constructed to withstand the higher pressure arid temperature, at which they will operate, and the higher stresses involved. For space heating loads where 558 CHAPTER 22 1956 Guide '. the flow varies greatly, it is common practice to use two or more pumps, although care should be taken in motor sizing to avoid oyerloading when one or more pumps may not be in operation. By use of multiple pumps light loads during off peak periods can be handled economically. When selecting the size of the pump, consideration should be given to the temperature conditions under which the pump will operate. To illustrate this, at 212 F the density of water is 59.88 lb per cu ft, whereas at 380 F it has dropped to 54.36. Therefore, as the weight of a gallon of water is considerably less, the pump will have to handle a much larger volume of water. On large installations the pump sizes can be kept down to practical limits by the use of multiple pumps connected in parallel to a common header. , To prevent flashing at the pump suction line, a bypass connection with valve is made between the supply and return lines to allow a small quantity of the cooler return water to mix with the supply water from the expansion drum. Thus the temperature of the water entering the pump suction line is a few degrees lower than the evaporation pressure, yet subjected to the full pressure in the drum. The valve is set manually to pass the minimum quantity of water as required above. Pipe, Fittings, and Insulation Steel pipe and fittings are generally used. An effort should be made to avoid the use of non-ferrous materials, since the action of the water at elevated temperatures on these materials is difficult to predict. Steel pipe should be used throughout, and piping external to the boiler house should be welded. Within the boiler house flanges are recom mended to facilitate inspection and provide ready access. Branches should take off with easy sweeps and full radius bends be used for all changes of direction. Provision for expansion is as important as for steam at the same temperatures. Piping should be insulated to the same thickness and stand ards as for steam at the same temperature. Valves for high temperature water should be made with cast steel bodies and stainless steel trim since these have proved far more satisfactory than bronze valves. Wedge-type gate valves are recommended for isolating and for use within the boiler house. For general use throughout the system, globe valves are preferred. Valves combining flow control and regulation are preferable for high temperature water where heat balancing is necessary, since a small quan tity of this water contains a large quantity of heat. As high temperature water is more penetrating than low temperature water, leakage due partly to capillary action should not be ignored because even a small amount of leakage evaporates immediately. This slight leakage becomes noticeable only on the outside of the gland and spindle of the valve where thin de posits of salts are left after evaporation. Control The control of temperature is usually obtained by conventional means although it is common practice to place control valves on the outletiine of the heat absorbing equipment where the temperatures are lower. In larger distribution systems means of controlling differential pressures be tween the flow and return mains are advisable. With space and process heating, temperatures can be controlled within Hot Water Heating Systems 559 close limits by the use of two- and three-way mixing valves modulating or by-passing some of the high temperature water. Such controls are essential at heat exchangers or converters. Boilers or Hot Water Generators ' Almost any high presssure boiler can be used for high temperature water systems, but certain types as, for example, the water tube boiler, are more advantageous than others. Boiler selection is important and such prob lems as frictional head loss, available water space, flue outlet, type of firing, Table 9. Properties of Wa.ter (212 F to 400 F) Temperature F Pressure* psia Density Lb/CuFt Specific Heat Btu/0b)(F) Total Heat Above 32 F Btu/Lb* Btu/CuFt 212 14.70 59.88 1.0055 180.00 10.760 220 17.19 59.66 1.0068 188.06 11.222 230 20.78 59.37 1.0087 198.15 11.764 240 24.97 59-17 1.0104 208.26 12.327 250 29.82 58.84 1.0126 218.39 12.856 260 35.43 58.62 1.0148 228.55 13.403 270 41.85 58.25 1.0174 238.74 13.912 280 49.20 58.04 1.0200 248.95 14.555 290 57.55 57.65 1.0230 259.20 14.942 300 67.01 57.41 1.0260 269.48 15.476 310 77.68 57.00 1.0296 279.80 15.955 320 89.65 56.65 1.0332 290.17 16.444 330 103.03 56.31 1.0368 300.59 16.931 340 117.99 55.95 1.0404 311.05 17.407 350 134.62 55.65 1.0440 321.55 17.899 360 153.01 55.19 1.0486 332.10 18.333 370 173.33 54.78 1.0532 342.71 18.778 380 195.70 54.36 1.0578 353.39 . 19.213 390 220.19 53.96 1.0624 364.14 19.644 400 247.25 53.62 1.0670 374.96 20.106 * Reprinted by permission from Thermodynamic Properties of Steam, by J. H. Keenan and F. G. Keyes published by John Wiley and Sons, Inc., 1938 edition. etc., need careful consideration. The larger the system, involving heat dis tribution circuits of three, four, five miles or more, the greater will be the frictional head on the pumps, so every care should be taken to reduce the head loss in the boiler to a minimum and thus reduce the pump horsepower. Frictional loss through a boiler operating with entrained steam and air in the tubes and headers, can be a serious factor. Balancing is another problem which can be made simple when the system is well designed. During the spring and autumn months and in mild weather at any time, the heat load will be low and only one boiler will be required. To put a boiler on the line or take one off is simplified if all boiler supply lines are connected into a common expansion drum. Boilers are then controlled from the pressure developed in the drum and the high temperature water supply taken through a dip pipe below the water level. Since the heat storage in the system is very high (Table 9 illustrates this in Btu per cubic foot) advantage of this high temperature water charac- 560 CHAPTER 22 1956 Guide teristic can be taken when considering the number and output of the boilers. The output of the central boiler plant can be greatly reduced and the initial cost of the system lowered accordingly if the thermal storage of the system is taken into account. Storage High temperature water systems offer the opportunity of storing heat to even out the peak loads and low loads within the 24-hour cycles. Storage is usually accomplished by means of by-passing water from the flow to the return mains and thereby storing heat in the return main for future use, dr by accumulators. Systems which experience normal peaks can obtain as much as 15 percent added capacity through this heat storage. Where peaks are more severe, this storage or thermal flywheel will allow even greater savings. Distribution The conventional conduit or tunnel distribution systems are employed with similar techniques used for installation except that grading of the piping is not important. The mains may be run at different elevations at will, although the high points should be vented by the use of air collectors and the low points should be drained. REFERENCES 1 Friction Heads in One-Inch Standard Cast-Iron Tees, by F. E. Giesecke and W. H. Badgett (A.S.H.V.E. Transactions, Vol. 37, 1931, p. 395). * Supplementary Friction Heads in One-Inch Cast-Iron Tees, by F. E. Giesecke and W. H. Badgett (A.S.H.V.E. Transactions, Vol. 38,1932, p. 111). . * Heating and Air Conditioning of Buildings, by Oscar Faber and J. R. Kell (Archi tectural Press, London). Bibliography . Hot Water Heating, Radiant Heating and Radiant Cooling, by F. E. Giesecke (Technical Book Co., P. O. Box 62, Austin, Tex. 1947). CHAPTER 23 RADIATORS, CONVECTORS, BASEBOARD AND FINNED-TUBE UNITS Definitions, Heat Emission, Radiators, Convectors, Baseboard Radiation, Finned-Tube Radiation, Ratings, Heating Effect, Effect of Operating Conditions, Effect of Paint, Enclosed Radiators, Heating the Radiator and Convector RADIATORS, convectors, baseboard, and finned-tube are the common j types of heat-distributing units used in steam and hot water heating systems. They are used to supply heat to a room by radiation and con vection. The function of these devices is to maintain occupancy comfort through the control of the mean radiant and air temperatures in the area. Since heat losses'through the various parts of the structure constantly tend to lower these temperatures below the comfort point, the room-heating unit should be so placed and regulated that its output will replace the losses when and where they occur. If 80 percent of the room heat loss occurs through a cold wall or window area, then 80 percent of the input should be introduced in or directed toward that area. The term radiator is generally confined to sectional cast-iron radiation. They emit a large part of their heat by radiation. Cast-iron radiator types may be column, large-tube, small-tube or wall. The term convector refers to a heat-distributing unit which operates with gravity recirculated room air, is surrounded on all sides by an enclosure having an air-inlet opening at its bottom end and an air-outlet opening at its top, and is installed inside the heated room or is recessed in the wall. . The terms baseboard and baseboard radiation refer to steam- or watertype heat-distributing units designed for installation along the bottom of the walls of rooms, replacing the conventional baseboard. They operate with gravity-recirculated room air, and have a substantial portion of their frontal face surface directly exposed to the room. The term finned-tube refersto steam-, orwater-type heat-distributing units composed of a finned-tube element fabricated from metallic tubing which has a plurality of metallic fins bonded to the tube. These heaters are de signed for installation without enclosure, or with open-type grilles, covers, or enclosures having top, front, or inclined outlets. HEAT EMISSION Steam-, and water-type heat-distributing units emit heat by radiation and convection. These heat-transfer processes and the factors that affect them are discussed in detail in Chapter 5. In general, those units having a large portion of their heated surface exposed directly to the room emit a larger proportion of heat by radiation than do units which have the heating sur face completely or partly concealed from view. The output of a heat-distributing unit can be measured only by the heat ' 561 562 CHAPTER 23 1956 Guide Table 1. Column-Type Cast-Iron Radiator Generally Accepted Rating pee Section* Height Inches One Column Sq Ft Btu/hr . Two Column . Sq Ft ' Btu/hr Three Column Sq Ft Btu/hr IS 18 20 m 360 2H 540 1*4 360 2 *4 480 ' 540 3 720 m 400 2*4 . 560 26 32 38 45 2 2*4 3 480 600 720 2*4 640 800 960 5 1200 3* 900 4*4 1080 5 1200 . 6 1440 Four Column Five Column Six column Sq Ft Btu/hr Sq Ft Btu/hr Sq Ft Btu/hr 13 16 18 20 3 720 3*4 900 720 45$ 1120 4*4 1080 5 1200 22 26 4 5 960 1200 7 1680 * ' 32 6*4 1560 38 1920 10 2400 45 2400 These ratings are based on steam at 215 F and air at 70 F. They apply only to installed radia tors exposed in a normal manner; not to radiators installed behind enclosures, gnlles,or under shelves For Btu per hour ratings at other temperatures, divide table values by factors found in table o. Table 2. Large-Tube Cast-Iron Radiators Sectional, cast-iron, tubular-type radiators of the large-tube pattern, that is, having tubes approximately I in /iiA ttyala, 91 in nn Mintprtt - Number of Tubes per Section Catalog Rating per Section* Sq Ft Btu/hr Height In. Width In. Section Center Spacing" Leg Height To Tapping In. Id. m 420 20 2*4 4*4 3 2 480 23 2*4 2*4 3 3*4 560 720 840 26 32 . 38 4W 2*4 2*4 2*4 4*4 4*4 4*4 4*4 4 2*4 " 540 2*4 600 2*4 660 3*4 840 4*4 ^ 1020 20 23 2*4 4*4 26 6J4-6iM 2*4 4*4 32 2*4 4*4 38 2*4 . 4*4 254 3*4 4*5 5' 640 720 840 1040 1200 20 23 26 32 8-8^6 mm2mHiiii 38 2*4d m 4*4 4*4 4*4 6. 720 840 960 1200 1440 20 23 26 * 32 38 9-10*4 2*4 2*4 2*4 2m*4 *H 4*4 4*4 4*4 4*4 2*4 600 720 3*5 880 14 2*4 17 1154-12154e 2*4 20 2*4 3 3 3 or 4*4 * These ratings are based on steam at 215 F and air at tors exposed in a normal manner; not to radiators installed 70 F behi nd enclos.u.re.s,, only to instailed raaiagri-l-l-e--s-,,orfi under shelves. For Btu per hour ratings at other temperatures, divide table values by factors,found in iable o. b Maximum assembly 60 sections. Length equals number of sections times 2 in.. ___ 7_tube c Where greater than standard leg heights art required, this dimension sM be 6 in., except for/ woe sections, in heights from 13 to 20 in., inclusive, for which this dimension shall be 4* in. Radiators may furnished without legs. .... . . ,. 4 For 5-tube hospital-type radiation, this dimension is 3 in. Radiators, Convectors, Baseboard and Finned Tube Units 563 it emits and is generally expressed in units of: Btu per hr; Mbh (1000 Btuper hr); or in equivalent direct radiation (e.g., 240 Btu per hr for steam). RADIATORS Column and large-tube radiators are no longer manufactured, but sincemany of these units are still in use, Tables 1 and 2 are included to provide principal dimensions and average ratings of them. The smatt-tube type radiators, with a spacing of If in. per section, are about the only available cast-iron radiating surface for homes and office buildings. Small-tube radiators occupy less space than the older column and large-tube radiators, and are particularly suited for installation in recesses. '. After a study of the demand for various sizes of radiators, the Institute of Table 3. Small-Tobe Cast-Iron Radiators Number Catalog . Rating op Tubes PER - per Section Section ' Section Dimensions A Height B Width ` Minimum Mariiwnm C Spacing1* Sq Ft Btu/hr In. In. In. In. D In. 3d 1.6 384- 25 3H 3W 154 2V4 4d 1.6 384 1.8 432 19 22 4*4#. 4 He 4*Me 4l5fe 154 154 2*4 2*4 2.0 480 25 4He 4iM l?i 2 5d 2.1 504 22 5fi 6Me 154 2*4 2.4 576 25 5H m 2*4 Op mm6d 2.3 552 19 3.0 720 . 25 6*M 6*M 8 8 154 2*4 154 2*4 3.7 888 32 6Me 8 m 2*4 These ratings are based on steam at 215 F and air at 70 F. They apply only to installed radia tors exposed in a normal manner; not to radiators installed behind enclosures, grilles, or under shelves. ^or Btu per hour ratings at other temperatures, divide table values by factors found in Table 6. Length equals number of sections times \lA in. . c- Overall height and leg height, as produced by some manufacturers, are one inch greater than shown m Columns A and D. Radiators may be*furaished without legs. Where greater than standard leg heights are required this dimension shall be 4*$ in. d Or equal. Boiler and Radiator Manufacturers, in cooperation with the Division of Simplified Practice, National Bureau of Standards, established Simplified Practice Recommendation R174-47 for small-tube cast-iron radiators. Table 3 shows the size and dimensions now being-manufactured. Wall radiators are hung from wall brackets and are well adapted to use m factory buildings. Tests have shown that the heat emitted from a walltype radiator may be reduced from 5 to 10 percent if the radiator is placed near the ceiling with the bars horizontal and in an air temperature ex ceeding 70 F. When radiators are placed near the.ceiling, there is usually such a large difference in the temperature between the floor level and the ceiling that it becomes difficult to heat the living zone of the rooms satis factorily. Dimensions and heat emission rates for wall radiators are given m Table 4. . CONVECTORS A typical recessed convector is shown in Fig. 1. The room air enters the convector enclosure near the floor line, below the heating element, is heated in passing through the element, and is delivered to the room through 564 :/ " " CHAPTER 23 : 1956 Guide the outlet grille located near the top of the enclosure: Factory-assembled units consisting of a heating: element,, casing, and outlet grille with damper are widely used. Grilles may be used over air inlets; In cases where enclosures are to be used but are not furnished by the heater manufacturer* it is important that the proportions of the cabinet and the grilles be so designed that they will not impair the performance. of the assembled convector. It is desirable that the enclosure or housing for the convector fit as snugly as possible so that the air to be heated cannot by-pass the heating elementrin passing through the enclosure. . Cast-iron heating units may be concealed in. a cabinet or enclosure for appearance. In such cases a greater percentage of heat is conveyed to the room by convection thereby resulting in a form of gravity convector. . : The output of a convector, for any given length, and depth, is a function of the height of the discharge grille above the heating element. The pub lished ratings are generally given in terms of Btu per hour or square feet of Equivalent Direct Radiation, EDR. For steam convectors, as for radia tors, 240 Btu per hr may be taken as an equivalent square foot of radiation. When more than one heating unit is used, one mounted above the other in Table 4. Gast-Ibon Wall Radiators Approximate Dimensions--Inches Height 13*4 13*4' 22 13*4 29 Length or Width 16*4 ' 22 - . .13*4 29 . 13*4 Thickness 3 3 3 3 3 Heat Output* Sq Ft- 6*4 8 8 11 11 Btu/hr . 1560 1920 2640 . 2640 * These ratings are based on steam at 215 F and air at 70 F. They apply only to installed radia tors exposed in a normal manner, not to radiators installed behind enclosures, grilles, or under shelves For Btu per hour ratings at other temperatures divide table values by factors found in Table 6. the same cabinet, the output of the upper unit or units will be materially less than that of the bottom unit. BASEBOARD RADIATION . Baseboard radiation is divided into three types; (1) radiant, (2) radiant- convector and (3) finned-tube.1 Radiant-type baseboard is made of cast iron or steel. This type of unit emits a large proportion of. heat to the room by radiation. These units are sometimes-suspended from the ceiling in rooms such as kitchens having little or no available wall space for floor mounted units.' For this location, as compared with" floor mounting, the amount of convected heat obtained from the unit is reduced, and conse quently 25 to 50 percent additional surface must be installed. Radiant-convector type baseboard also is made of east iron or steel. These units are provided with air openings at the top and bottom to permit circu lation of room air over the wall side of the unit where extended surface is provided to obtain maximum heat output. A large part of the heat ob tained from these units is transferred by convection. This type of base board which has a greater output per linear foot than the radiant type, has advantages where wall space is at a premium or the heat loss of the.room, is high. , Finned-tube type of baseboard has a finned-tube heating element which is concealed by a long low sheet-metal cover. A major portion of the heat is transferred to the room by convection. The output of this type of base Radiators, Convectors, Baseboard and- Finned Tube Units 565 board varies over a wide range depending on the enclosure depth and height, the diameter of the tube,: and the number and size of fins. When selecting this type of baseboard thie designer should avoid using a unit with too high an output per linear foot because performance is best when units are installed along as much of the exposed wall as possible. The basic advantage of the baseboard radiator or of the long low narrow radiator is that its normal placement is along the cold walls and under areas where the greatest heat loss occurs in a room. Other advantages claimed for the baseboard radiator are; it is inconspicuous; it is clean in operation; it offers a minimum of interference with furniture placement, and, it dis tributes the heat near the floor. -This last characteristic reduces the floor to ceiling temperature gradient to about 2 to 4 F deg, and.tends to produce uniform temperatures throughout the room. It also makes baseboard radi ators especially adaptable to basementless homes, where cold floors are prevalent.2 . " ' . .. . Heat loss calculations for baseboard heating systems are the same as those used for other types of radiation. The procedure for designing base board heating systems is given in 7 = B = R Installation Guide No. 5.1 Rat ings for baseboard radiation are expressed in Btu per linear foot. . FINNED-TUBE RADIATION The finned-tube type of radiation is always installed in the same manner as pipe or pipe coils.. It is rapidly superseding pipe coils as. much more output can be obtained per linear foot of pipe. When installed in two or three tiers in a hot-water system,-long sweep return bends may be used to connect the tiers. Header type connections are not satisfactory for long hot-water coils due to the tendency of water to short circuit along the path of least resistance. ' . Pipe coils are assemblies of standard pipe or tubing (1 in. to 2 in.) which are used as.radiators. ' In older practice these coils were commonly used in factory buildings, but are not often found in this service today. When coils are used, the miter-type assembly is preferable, as it readily permits expansion in the pipe. ! The heat emission of pipe coils placed vertically on a wall, with the pipes horizontal, is given in Table 5, which has been developed from available data and does not represent definite results of tests. For such coils the 566 CHAPTER 23 1956 Guide . heat emission varies as the height of the coil. The heat emission of each pipe in ceiling coils,. placed horizontally, is about 126 Btu, 156 Btu, and 175 Btu per linear foot of pipe, respectively, for 1-in., lj-in., and l|-in. coils. When vertical pipes leading through small rooms are left uninsulated for the purpose of supplying heat, the overall coefficient of heat transfer may be safely estimated at 2.5 Btu per (hr) (sq ft) (F deg temperature difference between the heating medium and the average air). RATINGS A standard method of testing radiators was adopted by the A.S.H.A.E. in 1927.3 This Code provides for a standard test room, the temperature of which is to be maintained at 70 F, measured in the center of the room at an elevation of 5 ft above the floor. The steam temperature in the radi ator is to be 215 F, which corresponds to 15.6 lb per sq in. absolute. The weight of condensate per hour, under these standard conditions, multi plied by the difference in the enthalpy of the steam entering the radiator and that of the condensate leaving the radiator, gives the radiator output Table 5. Heat Emission op Pipe Coils Placed Vertically on a Wall (Pipes Horizontal) Containing Steam at 215 F and Surrounded . ; with Air at 70 F Btu per linear foot of coil per-hour (not linear feel of pipe) ' ' Size of Pipe 1 In. U In. 1* In. . * 132 252 440 567 651 732 812 162 312 545 702 796 907 1005 185 348 616 793 907 1020 1135 in Btu per hour. This output divided by 240 gives the steam rating of the radiator in equivalent square feet, EDR. The method of testing and rating both ferrous and non-ferrous convec tors, which is now generally accepted, is given in Commercial Standard CS140-47, Testing and Rating Convectors,4 which has been developed co operatively by the Convector Manufacturers Association, the Institute of Boiler and Radiator Manufacturers, other members of-the trade, and the National Bureau of Standards. - The rating of a top outlet convector is established at a value not in excess of the condensation capacity (which is the heat extracted from the steam or water in the convector, under standard test conditions). The rating of a front-outlet or inclined-outlet convector includes the condensation capacity plus an allowance for heating effect5,6 in the occupied zone, based on con vector enclosure height from bottom of the enclosure to top of the outlet. The heating-effect allowance for a front-outlet convector varies from 0 percent for a 36-in. outlet height to 15 percent for an outlet height of 18 in. or less. .- For an inclined-outlet convector the heating effect allowance is obtained by multiplying the allowance for a front-outlet convector by a factor (angle of outlet to. horizontal-;-90). A Testing and Rating Code for Baseboard Type of Radiation was first adopted by the Institute of Boiler and Radiator Manufacturers in 1950. A Radiators, Convectors, Baseboard and Finned Tube Units 567 revised second edition7 of the code was published in 1952. The second edition contains test procedures for determining both steam and water capacities. The ratings are expressed in Btu per hour per linear foot, and may also be expressed in square feet of steam radiation per linear foot. Both steam and water ratings include an effective heat allowance of 15 percent of the heat capacity determined by test. Manufacturers who wish to publish baseboard radiation ratings as I=B = R ratings may submit test data to the I=B = R Baseboard Rating Committee and receive approval of test procedure and ratings. The fol lowing catalog information must be given for I=B=R Steam Ratings: (1) name or other type of designation, (2) I=B=R emblem, (3) rating in Btuh per linear ft, (4) percentage added to capacity in determining rating, (5) a statement that ratings are based on active length, (6) the difference between active and total length, and (7) if a finned tube element is used, a statement of the fin size, thickness and spacing. The following additional information must be given for I = B--R water ratings: (1) the water temperatures and flow rates for which ratings have been approved, and (2) pressure loss through the unit. Table 6. Factors to Convert I = B = K Finned-Tube Steam Ratings to Hot Water Ratings at Temperatures Indicated Average Radiator Temperature Factor Average - Radiator Temperature Factor Average Radiator Temperature Factor 150 0.45 155 0.49 160 0.53 165 0.57 170 0.61 175 0.65 ISO 0.69 185 0.73 190 0.78 195 0.82 200 205 210 215 220 ` 0.86 0.95 1.00 1.05 A Testing and Rating Code for Finned-Tube Type of Radiation8 was adopted by The Institute of Boiler and Radiator Manufacturers in 1951, and the code was amended in 1954. This code contains a test procedure for de termining steam ratings. The code contains a table of effective heat allow ances which may be added to the condensate output (corrected to standard conditions) in establishing the rating. These allowances vary from zero for an installed height of 36 in. or more to a maximum of 15 percent for an installed height of 18 in. or less. Water ratings are determined by applying the factors in Table 6 to approved I = B = R steam ratings. . Manufacturers Who wish to publish finned-tube, radiation ratings as i--B=R ratings must submit test data to the I = B = R Finned-Tube Rat ing Committee and receive approval of test procedure and rating. In their catalogs they must show information similar to that required when pub lishing ratings for baseboard radiation. Heating Effect The acceptance of heating effect allowance by the industry is the result of observation such as the following:6 1. The heating effect of a radiator cannot be judged solely by the amount of steam condensed within the radiator. 2. Smaller floor-to-ceiling temperature differentials can be maintained with long, low, thin, direct radiators, than can be maintained with high, direct radiators. 3. The larger portion of the floor-to-ceiling temperature differential in a room of average ceiling height heated with direct radiators occurs between the floor and the breathing level. 4. The comfort level (approximately 2 ft-6 in. above floor) is below the breathing 568 CHAPTER 23 1956 Guide line level (approximately 5 ft-0 in. above floor), and temperatures taken at the breath ing line may not be indicative of the actual heating effect of a radiator in the room. The comfort-indicating temperature should be taken below the breathing line level. 5. High column radiators placed at the sides of window openings do not produce as comfortable heating effects as long, low, direct radiators placed beneath windows. The application of a heating-effect allowance implies that some radiators and convectors use less steam than others for producing equal comfort heating results in the room. All authorities do not agree that the use of such an allowance is justified: No standard method for evaluating the heating effect of radiators and convectors and correlating it with comfort has yet been accepted. Table 7. Correction Factors fob Direct Cast-Iron Radiators and Convectors* Steam Pbess. (Approx.) Gage Vacuum In. Hg. Abs Lb per Sq In. Heating Factors for Direct Cast-Iron Radiators Factors for Convectors Temp F Steam or Water . Room Temperature F 80 75 70 65 60 55 50 Inlet Air Temperature F 80 75 70 65 60 55 50 22.4 20.3 17.7 14.6 10.9 6.5 Lb per Sq In. 6 15 27 52 3.7 4.7 6.0 7.5 9.3 11.5 15.6 21 30 42 67 150 2.58 2.36 2.17 2.00 1.86 1.73 1.62 3.14 2.83 2.57 2.35 2.15 1.98 1.84 160 170 180 190 2.17 2.00 1.86 1.73 1.62 1.52 1.44 2.57 2.35 2.15 1.98 1.84 1.71 1.59 1.86 1.73 1.62 1.52 1.44 1.35 1.28 2.15 1.98 1.84 1.71 1.59 1.49 1.40 1.62 1.52 1.44 1.35 1.28 1.21 l.lfi 1.84 1.71 1.59 1.49 1.40 1.32 1.24 1.44 1.35 1.28 1.21 1.15 1.10 1.05 1.59 1.49 1.40 1.32 1.24 1.17 1.11 200 1.28 1.21 1.15 1.10 1.05 1.00 0.96 1.40 1.32 1.24 1.17 1.11 1.05 1.00 215 1.10 1.05 1.00 0.96 0.92 0.88 0.85 1.17 1.11 1.05 1.00 0.95 0.91 0.87 230 250 0.96 0.92 0.88 0.85 0.81 0.78 0.76 1.00 0.95 0.91 0.87 0.83 0.79 0.76 0.81 ft.7fl 0.76 0.73 0.70 0.68 0.64 E).83 0.79 0.76 0.73 0.70 0.68 0.65 270 300 0.70 0.68 0.66 0.64 0.62 0.60 0.5i 0.7(1 0.68 0.65 0.63 0.60 0.58 0.56 0.58 0.57 0.55 0.53 0.52 0.51 0.49 [).66 0.54 0.53 0.61 0.49 0.48 0.47 * To determine the size of s radiator or a convector for a given space, multiply the heat loss of the space in Btu per hour by the proper factor from the above table and select radiator or convector having an equiva lent Btu per hour rating. An alternate method is to divide the heat loss in Btu per hour by 240 and multiply the result by the proper factor from the above table and select radiator or convector having an equivalent square foot rating. To determine the heating capacity of a radiator or a convector under conditions other than the basic ones with the heating medium at a temperature of 215 F, and the room temperature at 70 F in the case of a radiator, and the inlet air temperature at 65 F in the case of a convector, divide the heating capacity at the basio rating conditions by the proper factor from the above table. EFFECT OF OPERATING CONDITIONS The heat output of a radiator, convector, baseboard or finned-tube unit is an exponential function of the temperature difference between the air in the room and the heating medium in the room-heating unit, or, expressed as an equation where H = c(f. - 1,)" (1) H = heat output in Btu per hour. c -- a constant determined by test for each type. t9 = average temperature of heating medium, Fahrenheit. For hot water the arithmetical average of the entering and leaving water temperatures is used. tP room air temperature Fahrenheit. Air temperature 60 in. above the floor is generally used for radiators while the temperature 3 in. above the floor or at the inlet of the heating unit is used for all other types of heating units, n -- an exponent which equals 1.3 for radiators, 1.4 for baseboard radiation, and Radiators, Convectors, Baseboard and Finned Tube Units 569 1.5 for convectors. For finned-tube radiation n varies with both air and heating-medium temperatures. dorrection factors for converting outputs at standard rating conditions to outputs at other operating conditions are given in Tables 7 and 8. Effect of Paint For a radiator, the finish coat of paint affects the heat output. Oil paints of any color will give about the same results as unpainted black or rusty surfaces, but an aluminum or a bronze paint will reduce the heat emitted by radiation. The net effect may be a reduction of 10 percent or more in the total heat output of the radiator.9-10-11 Table 8. Correction Factors for Finned-Tube and Baseboard Radiation* Steam Pressure Approx Heating Medium Factors fob Finned-Tube Factors for Baseboard Temp. F Gage Abs Vac- Lb Steam Inlet Air Temperature, F Inlet Air Temperature. F uum per In. Hg Sq In. - -_ 80 75 70 65 60 55 50 80 75 70 65 60 55 50 22.4 3.7 20.3 4.7 17.7 6.0 14.6 7.5 10.9 9.3 6.5 11.5 Lb per sq in. i 15.6 6 21 15 30 27 42 52 67 150 ' 160 170 180 190 200 215 230 250 270 300 2.80 2.50 2.20 1.95 1.81 1.67 1.54 2.86 2.61 2.38 2.20 2.03 1.89 1.76 2.34 2.14 1.94 1.75 1.62 1.50 1.37 2.38 2.20 2.03 1.89 1.76 1.64 1.56 2.01 1.86 1.70 1.56 1.46 1.36 1.26 2.03 1.89 1.76 1.64 1.54 1.44 1.38 1.76 1.65 1.53 1.42 1.32 1.24 1.15 1.76 1.64 1.55 1.44 1.38 1.29 1.23 1.53 1.45 1.36 1.28 1.20 1.12 1.03 1.54 1.44 1.37 1.29 1.22 1.16 1.09 1.38 1.31 1.24 1.16 1.09 1.02 0.95 1.38 1.29 1.23 1,16 1.09 1.05 1.00 1.17 1.12 1.06 1.00 0.95 0.90 0.85 1.16 1.10 1.05 1.00 0.95 0.92 0.88 1.00 0.97 0.93 0.90 0.86 0.82 0.78 1.00 0.96 0.92 0.88 0.84 0.81 0.77 0.88 0.85 0.82 0.78 0.75 0.71 0.67 0.86 0.82 0.79 0.76 0.73 0.70 0.68 0.75 0.73 0.70 0.68 0.65 0.62 0.59 0.73 0.70 0.68 0.66 0.63 0.61 0.59 0.62 0.60 0.58 0.56 0.54 0.52 0.50 0.58 0.57 0.55 0.53 0.52 0.51 0.49 ,. To determine the heating capacity under conditions other than the basic ones with the hunting me dium at a temperature of 215 F, and the inlet air temperature at 65 F, divide the the bating capacity at the basic rating conditions by the proper factor from the above table. . ENCLOSED RADIATORS The general effect of an enclosure placed about a direct radiator is to restrict the air flow, diminish the radiation and, when properly designed, improve the heat distribution within the heated space.'19 Some commercial enclosures and shields for use on direct radiators are equipped with water pans for the purpose of adding moisture to the air in the room. Tests13 show that an average evaporative rate of about 0.235 lb per (hr) (sq ft of water surface) may be obtained from such pans, when a radiator is steam heated and the relative humidity in the room is between 25 and 40 percent. This source of supply of moisture alone is not adequate to maintain a relative humidity above 25 percent on a zero day. HEATING THE RADIATOR AND CONVECTOR . The maximum condensation occurs in a heating unit when the steam ,)s first turned on. Tests14 on an old-style column-type cast-iron radiator indicated that in the first 10 min the condensation rate reached a peak of 0.95 lb per sq ft of radiation per hour and 10 to 15 min later dropped to a 0-24 lb. In one-pipe gravity systems the rate of steam supply to the heating unit, -while heating up, is frequently retarded by controlled 570 CHAPTER 23 1956 Guide elimination of air through air valves or traps. In two-pipe systems auto matic control valves may also retard the supply of steam. Vacuum types of air venting valves may be used to reduce the length of the. venting periods. REFERENCES I I = B = R Installation Guide No. 5, Baseboard Heating Systems {Institute of Boiler and Radiator Manufacturers, Second Edition, 1953). 3 A Study of Radiant Baseboard Heating in the I=*B = R Research Home, by Alonzo P. Kratz and Warren S. Harris {University of Illinois, Engineering Experi ment Station Bulletin No. 358, 1945). 3 A.S.H.V.E. Code for Testing Radiators- (A.S.H.V.E. Transactions, Vol. 33, 1927, p. 18). . * Commercial Standard for Testing and Rating Convectors, CS.140-47 (U. S. De partment of Commerce, 1947.) * 5 The Heating Effect of Radiators, by Charles Brabble (A.S.H.V.E. Transac tions, Vol. 33, 1927, p. 33). * Investigation of Heating Rooms with Direct Steam Radiators Equipped with Enclosures and Shields, by A. C. Willard, A. P. Kratz, M. K. Fahnestock and S. Konzo (A.S.H.V.E. Transactions, Vol. 35, 1929, p. 77 or University of Illinois, Engineering Experiment Station Bulletin No. 192). Investigation of Various Factors Affecting the Heating of Rooms with Direct Steam Radiators, by A. C. Willard, A. P. Kratz, M, K. Fahnestock and S. Konzo {University of Illinois, Engineering Ex periment Station Bulletin No. 223). . 7 I = B=R Testing and Rating Code for Baseboard Type of Radiation {Institute of Boiler and Radiator Manufacturers, Second Edition, August 1952). * I = B = R Testing and Rating Code for Finned-Type Radiation. {Institute of Boiler and Radiator Manufacturers, First Edition, 1951, with Addenda, 1954). * Heat Emission from Radiators, by K. F. Rubert {Cornell University, Engineering Experiment Station Bulletin No. 24, 1937). 10 Comparative Tests of Radiator Finishes, by W. H. Severns (A.S.H.V.E. Trans actions, Vol. 33, 1927, p. 41). , II Heat Loss from Direct Radiation, by J. R. Allen (A.S.H.V.E. Transactions Vol. 26, 1920, p. 11). 11 Heat Output of Concealed Radiators, by E. A. Allcut (University of Toronto, School of Engineering Research Bulletin No. 140, 1933). . 13 Humidification for Residences, by A. P. Kratz (University of Illinois, Engineer ing Experiment Station Bulletin, No. 230, p. 20). w A.S.H.V.E. Research Report No. 1067--The Cooling and Heating Rates of a Room with Different Types of Steam Radiators and Convectors, by A. P. Kratz, M. K. Fahnestock and E. L. Broderick (A.S.H.V.E. Transactions, Vol. 43, 1937, p. 389). CHAPTER 24 PANEL HEATING Definitions; Application-Methods: Embedded Piping for Ceilings, Walls, or Floors; Warm Air and Electrically Heated Ceilings, Walls; or Floors; Output from Panel Surfaces: Radiation, Convection and Combined Heat Transfer; Floor Panel Design: Design Conditions, Calculation of Room Heat Loss, De- . termination of UMRT, Determination of Panel Output, Graphical Determination of Panel Input and Water Temperature; Ceiling and Wall Panel Design; Hot Water Piping, Installation and Control; Snow Melting: Design and Installation . IN this chapter the term, Panel Heating, is used to describe a method of space heating which employs large heated areas of interior room surfaces operating at relatively low surface temperatures (80 to 125 F). The heating elements usually consist of warm water piping, warm air ducts, or low temperature electrical resistance elements embedded in, or located behind, ceiling, wall, or floor surfaces. Panel heating may be considered as another method of convenient and effective space heating. The heat loss requirements may be calculated in. the conventional manner except that the heat loss through the area occu pied by the heated .panel need not be included. An assumed reverse heat loss from the panel, however, should be included in determining heating main size and the boiler load.'. The heat release from the panel is expressed in terms of hourly heat output per square foot of surface. The room air temperatures to be maintained are approximately the same as those main tained by heating systems employing cast-iron radiators, convectors, or warm air ducts. . This chapter does not include a separate discussion of such topics as the influence of radiation on human comfort, the mechanisms by which human beings release heat, and other similar topics that apply to all methods of heating interior spaces for -human comfort. The reader is referred to Chapter 6 for a detailed discussion of these subjects. APPLICATION METHODS The great majority of panel installations of the past 50 years (which is the period of the modern utilization of this method of heating) have used warm water as the heating medium which is circulated in embedded pip ing. More recently, the use of warm air ducts, and embedded electrical heating elements, has come into favor, especially where specific local fac tors have influenced such use. Steam has been used only occasionally because of the problems which result from its higher temperature. When the heating medium is warm water, both ferrous (steel or wrought iron) or non-ferrous (generally copper or aluminum) pipe or tube are used widely in ceiling, wall, or floor panel construction. Tube sizes used are H, Vi, % and % in. O.D., while piping is generally Yi, %, or 1 in. IPS. Where coils are.embedded in concrete or plaster, no threaded joints should be used for either pipe coils or mains. The construction should be of all-welded type. Changes in direction should be made by bending the pipe itself, rather than by use of fittings. Solder-joint fittings are used for 571 572 CHAPTER 24 1956 Guide non-ferrous heating coils and piping. It is recommended that a medium temperature solder of 95 percent tin--5 percent antimony, or capillary brazing alloys, be used. All piping is, generally, subjected to a hydrostatic test of at least three times the working pressure, but not less than 150 psig. The more common forms of application of panel heating fall into the following general categories: (1) embedded piping for ceilings; (2) em bedded piping for walls; (3) embedded piping for floors; (4) air heated ceilings, walls or floors; (5) electrically heated ceilings, walls or floors. Embedded Piping for Ceilings When piping is embedded in ceilings, the construction used is generally one of the following: a. Pipe or tube is embedded in the lower portion of a concrete slab, generally very close to its lower surface. If plaster is to be applied to the concrete, the piping supporting member* SCRATCH COAT OM 3 OR * FT CENTERS. CUBCDOINO PIPE OR STEEL plf>C5 _ / SSTTRUC..T..U...R..A...L...M...E..M.."BERS* Fig. 1.- Coils in Structural. Concrete Slab 'METAL LATH FINISHED PLASTER. CEILING Suspended Plaster Ceiling , \. SCRATCH COAT Fig. 3. Coils in Plaster Below Lath Plaster Ceiling Below Joists Fig. 2. Coils in Plaster Above Lath may be placed directly on the wood forms. If the slab is to be used without plaster finish, then the piping should be installed not less than % in. above the undersurface of the slab. Fig. 1 shows this method of construction. The minimum coverage must be in compliance with the local building code requirements. b. Pipe or tubing is embedded in a metal lath and plaster ceiling. If the lath is suspended to form a hung ceiling, both the lath and the heating coils are securely wired to the supporting members in such a way that the lath is below, but in good contact with the coils, as shown in Fig. 2. Plaster is then applied to the metal lath, care being taken to embed the coil, as shown in Fig. 2. c. Copper tubes of the smaller diameters are attached to the underside of wire lath or gypsum lath. Plaster is theD applied to the lath to embed the tube, as shown in Fig. 3. . d. Other forms of ceiling construction utilize prefabricated panels of metal, composition board, wood paneling, etc., having warm water piping, tube or channels built into the panel sections. Coils are usually of the sinuous type, although some header or grid type coils have been used in ceilings. Coils may be of either ferrous or non-fer- Panel Heating 573 Fig. 4. Coils in Floor Slab on Grade rous pipe or tube, with coil pipes spaced from to 9 in. on centers, de pending on the required output, pipe or tube size, and other factors. Where plastering is applied to pipe coils, a standard three-coat gypsum plastering specification1 is followed, with a minimum of in. of cover be low the tubes when the tubes are installed below the lath.. Generally, the surface temperature of plaster panels should not exceed 120 F, and this is usually met by limiting the water temperature in the pipes or tubes in contact with the plaster to a maximum temperature of 140 F. Insulation should be placed above the coils to reduce the reverse loss which is the difference between-the heat supplied to the coil and the' net useful output to the heated room. ' '' In order to protect the planter installation and to assure proper air dry ing of the plaster, it is,recommended that no heat be applied to the panels for two weeks after all plastering work has been completed; When the system is started for the first time, the water supplied to the panels should be at a temperature not more than 20 deg above the prevailing room temperature at; that time (but not in excess of 90 F). Water should be circulated at this temperature for about two days. Then the water tem perature should be increased at' a rate of approximately 5 deg increase per day to 140 F. ` During the air-drying and preliminary warming-up periods, adequate ventilation should be provided to carry off moisture from the panels. No paint or paper should be applied to the panels until these periods have been completed. No paint or paper should be applied while the panels are being operated. After paint and paper have been applied, a further shorter warm-up period, similar to that for the first time starting, is also recommended. . Embedded Piping for Walls ' Although not so universally used as ceiling panels, wall panels may be constructed by any of the methods outlined for ceilings. Fig. 5. Warm Air Plaster Ceiling Construction 574 CHAPTER 24 1956; Guide Fig. 6. Warm Aib Floor Panel Construction Embedded Piping for Floors , The construction for piping embedded in floors will depend upon whether (a) the floor is laid on grade, or (b) the floor is above grade. . a. Both ferrous and non-ferrous pipe and tube are used in floor slabs wwhhiicch rest on grade. The coils are constructed as either sinuous -continuous pipe coils, owr. a,,r ranged as header coils with the pipes spaced from 6 to-18 in. on centers. The coils are generally installed with 1J to 4 in. of cover above the coils. It is recommended that insulation be used to reduce the perimeter and reverse losses. Fig. 4 shows the application of pipe coils in slabs resting on grade. Coils should be embedded com pletely and should not rest on an interface. Any supports used for positioning the hbeating coils shnoulida bdec nnoonu--aabussomrubecuntt atWnIdU ilnUoUrlggaainUicV.l IAtV iAsW suggested tha.t .re__i_n__f_o__r_cing s'Ate-e-l,'a---n---g--1le- iron, "p'i"e'c'neos rotff rpiinipoe, AoFrcst.tnotnlAeAcOoTnlOc.rreftttle mounds he used. No wood, brick, concrete block or similar materials should be used for support of coils. Gen erally, a waterproofing layer is desirable to protect insulation and piping. b. Where the coils are embedded in structural load supporting slabs above grade, construction codes may affect their position. Otherwise, the coil piping is installed in the same manner as described for slabs resting on grade. - : c. A warm-up and start-up period for concrete panels should be similar to that outlined for plaster panels. _ , Air Heated Ceilings, Walls, and Floors Several methods have been devised to warm the interior room surfaces by circulating heated air through passages behind these surfaces. In some cases, the heated air is recirculated in a closed system. In others, all or a part of the air is passed through the room on its way back to the furnace to provide supplementary heating and ventilation.2 Figs. 5 and 6 indicate two common types of construction. Care must be exercised to assure com- STUD IP*CC <--INSULATION a \ LATM ^KgATIKC CABLES J (STAPLED to LAT*9 FiniShCO PLASTER Fig. 7. Electric Heating Cables in Plasteb TILLER PANEL INSULATION \w MSUkATIQM MtATlNO PANEL - INSOLATION'' IN PANCL - PREFABRICATED ATTACHED TO JOISTS PANEL ATTACHEO TO JOISTS DETAIL Fig. 8. Prefabricated Electric Panel Panel Heating 575 pliance with any building codes that might apply. (See also section on Warm Air Ceiling Panel Systems in Chapter 20.) . Electrically Heated Ceilings, Walls, or Floors Several different forms of electric resistance units are available for heating the interior room surfaces. These include: (1) resistance cables that may be embedded in a manner similar to hot water piping in concrete or plaster; (2) prefabricated electric heating panels to be attached to room surfaces; and (3) electrically heated fabrics or other materials for applica tion to, or incorporation into, finished room surfaces. Figs. 7 and 8 indi cate two methods of installation. The constructions of electric panels for ceilings, walls, and floors are described in greater detail in Chapter 42, Electric Heating. OUTPUT FROM PANEL SURFACES The heat transfer from a panel is accomplished by radiation and con vection, which are considered in following paragraphs. Radiation Transfer. The radiation transfer can be evaluated by means of the relationship set up by Stefan and Boltzmann: . -**[()-()] < where q, = heat transfer by radiation, Btu per (square foot) (hour). T, = absolute temperature of panel heated surface, Fahrenheit. T,, = absolute mean radiant temperature of all unheated surfaces, Fahrenheit. = the configuration factor (dimensionless). F, = the emissivity factor (dimensionless). For large parallel planes or large enclosed surfaces as ordinarily en countered in panel heating practice: where Ci and e, = emissivities of the respective surfaces. In heating practice ei and e2 are usually equal to 0.9 and F,, to 0.82. Also, the configuration factor F,, is equal to 1 for large parallel planes, long concentric cylinders, or smaller bodies in large enclosures. There fore, for ordinary rooms with parallel walls, regular floors and ceilings, with an emissivity factor of 0.82, Equation 1 can be simplified to: Irregularities in room surfaces and materials may introduce some error 576 CHAPTER 24 1956 Guide in the application of this radiation relationship. However, most author ities are in.agreement that the heat emission by radiation/, as calculated in this manner, can be considered accurate within 10 percent. Radiation values are shown in Fig. 9 for various surface temperatures. These values are applicable for either floor, wall, or ceiling panel radiation outputs. Convection Transfer Convection values of heat transfer are not easily established. Con vection in a panel heated space is usually considered to be of the natural type, that is, air motion is generated by the warming (by conduction) of the boundary layer of air which starts moving as soon as its tempera ture exceeds that of the surrounding air. In practice, however, there are Panel Heating 577 /,, = a coefficient (surface conductance) representing the heat transfer from' a unit area per unit difference in temperature, Btu per (square foot) (hour) (Fahrenheit degree temperature difference between surface and air). n = an exponent depending on surface position and temperature difference be tween the surface and the surrounding air. f, = temperature of the surface, F. t,, = temperature of the air, F. The value of n is usually taken as 1.25 regardless of the magnitude of the temperature difference and the position of the surface. However, Wilkes and Peterson state that a value of 1.12 for n is more appropriate for low temperature differences, with heat flow upward from horizontal surfaces, and that a value of 1.00 is best in the'case of heat flow downward from horizontal surfaces. The various investigators mentioned also indi- < " panel surface temperature Fig. 9. Heat Output by Radiation many factors interfering with natural convection. Infiltration, localized drafts, ventilation, and movement of persons are all likely to disturb this process so that it becomes difficult to determine the exact convection effect. Until results from current research become available, an interim evaluation of convection heat exchange can be determined for ordinary panel heating applications from available theoretical relationships. As investigated54-6 by Nusselt and Henky, Griffiths and Davis, Wilkes and Peterson, McAdams and others, natural convection is found to be affected by only two factors: (a) temperature difference between the heat emitting surface and the surrounding air and (b) the position of the sur face. . The basic general equation for natural convection from a flat surface is of the following form: ' ?e = Ut. - where g, = heat transfer by convection, Btu per (square foot) (hour). U = panel surface temperature ta -- inside air temperature Fig. 10. Heat Output by Convection prom Floor and Ceiling Panels cate that values of /,, vary from 0.2 to 0.38 for downward heat flow from ceilings, and from 0.38 to 0.81 for upward heat flow from floors.. The variation in the value of>/c, as reported by the various investigators, is dependent upon the temperature difference and the value of the exponent n. More recent experimental work indicates a provisional correlation be tween measured convection outputs in actual floor panel heated rooms and the laboratory values obtained by the previous investigators. This correlation indicates that the values obtained from Wilkes and Peterson's equation - <7. = 0.81 (1. - .)>" (5) tor heat flow upward from horizontal surfaces and small temperature differences, give results that check within reasonable precision the con vection output from floor panels, with temperature differences as recom mended. Curve A in Fig. 10 is based on the equation of Wilkes and 578 CHAPTER 24 1956 Guide Peterson, and gives values which may be used for convection outputs from floor panels. : . More experimental data are required on convection outputs of ceiling panels. The warming of the air by a ceiling panel does not in itself create convection currents. Instead, it is the action of cooling along the outside wall or walls which causes the air movement. In lieu of actual test data which would take this factor into account, it is recommended that the values obtained from Curve B in Fig. 10, based on the Nusselt and Henky.equa tion . ge = 0.22 (t. - <)'" - (6) be used for determining convection outputs from ceiling panels for various surface temperatures. Panel Heating 579 perature is 70 F and the mean radiant temperature UMRT of the untreated room siir- faces is 60 F. .. .. . Solution: . Radiation (Fig. 9 for UMRT of 60 F and t. of 100 F) Convection (Fig. 10, Curve B for a At of 30 F) Btu/(hr) (aq ft) 35.3 15.5 Total useful heat transfer 50.8 Since the greater number of panel installations are designed for an average room air temperature of 70 F, it is possible to present in chart form Output based on 70 F inside air temperature F:g. 11. Total Panel Output Radiation Plus Convection - Combined Heat Transfer The sum of the radiant heat transfer from Fig. 9 and the convective transfer from curve A or B of Fig. 10, gives the combined useful heat trans fer to the room for any combination of panel surface temperature, room air temperature, unheated mean radiant temperature (UMRT), and panel location. Example 1: Find the combined total useful heat transfer from a square foot of floor panel having a surface temperature of 85 F, when the average room air tempera ture is 70 F and the mean radiant temperature UMRT of the unheated room sur faces is 60 F. WlUMVf. Radiation (Fig. 9 for UMRT of 60 F and t, of 85 F) ,, ... .. ,t\ Btu/(hr)(sq 21.4 Co(nFviegc.ti1o0n, Curve A for a temperature difference of 15 deg F) 16.9 ExamTTpoolettaall: uussFeeiffnuudll hhtheeeaattcttorraamnnbssinffeeerrd total useful heat'transfer from a squa,.re3'8fo-3ot . of ceiling panel having a surface temperatui e of*100 F, wheB the average room air tem- Fig. 12. Relation of Overall Coefficient of Heat Transfer to Inside Surface Temperature (see Fig. 11) the relationship between panel output (radiation plus con vection) and the unheated mean radiant temperature for various surface temperatures and panel positions based on 70 F inside air temperature. From Fig. 11 the panel output for Examples 1 and 2 can be read directly, 38.3 and 50.8 Btu, respectively. Similarly, combined transfer rates for floor or ceiling panels operating under other conditions may be determined. from Fig. 11, or from Figs. 9 and 10. Before Figs. 9 and 11 can be used, the unheated mean radiant tempera ture UMRT of the room surface must be known. For the purpose of this work, the UMRT may be defined as the average temperature of the unheated surfaces of the space, weighted according to the areas, of the surfaces. The surface temperature of the inside walls may be assumed to be the same as the inside air temperature. The, surface temperatures of outside walls or exposed ceilings, for any combination of outside design tempera ture and transmission coefficient, may be obtained from Fig. 12. If the 580 CHAPTER 24 1956 Guide inside'design temperature is other than 70 P, the values determined from Pig. 12 must be corrected by values obtained from Fig. 13. The follow ing example illustrates the use of Figs. 12 and 13. Example S: The outside walls of a room have a coefficient of heat, transfer U = 0.15. Inside and outside design air conditions are 68 F and --20 F, respec tively. Determine the inside surface temperature of the wall. - Solution: From Fig. 12 the inside surface temperature for 70 F and --20 F, and a U value of 0.15 is found to be 61.5 F. Then from Fig. 13, for a At = -- 2 deg and a XJ value of 0.15, the correction is --1.8 deg. As the correction is negative, the inside surface temperature will then be 61.5 -- 1.8 = 59.7 F. The total panel output can then be determined from Figs. 9,10, and 11. ` - Panel Heating 581 1. Selection of Design Conditions a. Outside design temperature,1--10 F. b. Inside design room air temperature, 70 F. .. c. In this problem a floor panel heating system will be used. There is no basement. Insulation will be used between slab and fill. d. Heating medium, hot water. '. e. Floor surface temperature, 85 F (Maximum). . 2. Calculation of Room, Heal Loss .................. The heat transmission coefficients of the room surfaces are given in Fig. 14They would usually be obtained from Chapter 9. The room heat loss can be calcu- wcst Fig. 13. Inside Wall Surface Temperature Correction for Inside Air Temperatures Other Than 70 F .. Ai = ^ -- 70 . If Ai is positive: fw/ ** fw + correction If Af is negative: fw' = fv -- correction ** inside air temperature -- inside wall surface temperature based on f* =* 70 F fw* 83 actual inside wall surface temperature After the various wall surface temperatures have been determined, as described, the unheated mean radiant temperature UMRT of the space may: be calculated as illustrated in Step 3 of the following section on Floor Panel Design Illustration. Panel Edge Loss , Refer to the section, Heat Losses from Floor Slabs, in Chapter 12. These' losses will affect slab temperature and water temperature near outside, walls, and must be included in either the room loss or the panel input. In the following example, Item 5, Part 4 can be considered to include this loss, but if the edge loss exceeds the amount allowed by Part 4, the larger loss should be used. '' FLOOR PANEL DESIGN ILLUSTRATION The several steps in the design of a panel heating system are listed and illustrated in the following example of the design of a.floor panel for the room shown in Fig. 14. . . Fiq. 14. Room Plan for Illustration of Method of Designing , a Panel Heating System . . ' . Data: Values of overall heat transfer coefficients Recalculated: 1. Outside walU V =0.10 . 3. Floor 2- Ceiling XJ = 0.08 ` 4. Window V = 0.36 U = 0J55 Shown in'Tahle 1hMner\?fin Chapter 12. The calculations are medium is notincluledin"thetlculS the 8Urface areas "taining the heating The calculated rate of heat loss supplied by the heating panels to will determine the room. the . amount of heat which must be Table 1. Calculated Heat Loss of Room (Fig. 14) Surfaces outside walls....... Glass___ Inside walls....... Geilincr.. ' Floor ................. Infiltration...; Area Sq Ft 272 80 352 480 480 . ~ Total heat loss u 0.10 0.55 0.08 --' Calculation 272 x 0.10 x 80. 80 x 0.55 x.80 No heat loss 480 x 0.08 x 80 Heating panel 3,840 cu ft x 1.50 x 80 0.018 Heat Loss Bto/hb 2,176 3,520 0 3,072 0 8,295 17,063 ULLnUUUlL OJ UlVltt T facf ff,^alcU!ations/r determining UMRT are shown in Table 2. The inside sur . e temperatures shown in the fourth column were determined from Fig. 12. 582 CHAPTER 24 j-1956 Guide Table 2. Calculation op UMRT Subface 0.10 0.08 0.55 Total.................................................... Abba Sq Ft 272 352 480 80 1,184 lireide Sub- ' face* TemPEBATUBB F Product (Abba x Tempbbatube) 65 70 . 66 43 17.680 24,640 31.680 3,440 77,440 _____ Total of products 77,440 UMRT =---------------------- = 65.4 F Total area 1,184 * Values of inside wall surface temperature for various U values and outside design temperatures found in Fig. 12. 4. Determination of Panel Output Values of total panel output for various panel positions, panel surface tempera tures and unbeaten MRT aTe given in Fig. 11. From Fig. 11, with a floor panel sur face temperature of 85 F and a UMRT of 65.4 F, the total panel output is 34 Btu per (hr) (sq ft of panel surface). . Panel area = 24 x 20 -- 480 sq ft Panel output = 480 x 34 = 16,320 Btu per hr This panel output of 16,320 Btu per hr is reasonably close to the calculated room loss of 17,063, ana is satisfactory. If this value of. total heat output from panel to the room were much less, i.e., 10 or more percent less, than the calculated heat loss from the room, some method of supplementary heating would be needed. Floor panel surface temperatures exceeding 85 F are not recommended. 5. Determination of Panel Input and Water Temperature Fig. 15 presents a graphical method of determining the required water tempera ture and total heat input to a panel for various cover depths, tube or pipe sizes and spacings, and rate of heat output to the room. The panel output for this example has previously been found to be 34 Btu per (hr) (sq ft). Since some of the heat input to the panel is lost to the ground, it is necessary to supply more than 34 Btu per (hr) (sq ft) to the panel by means of the hot water heating medium. The amount of heat which must be supplied to the panel to give the required output may be determined graphically from Fig. 15. As sume that the panel has f in. pipes, spaced on 12 in. centers, and that the depth of cover from top of panel surface to top of pipes is 2.5 in. The four sections of Fig15 are marked Part 1 to Part 4 and, as will be evident by following the dashed hue on the chart, are used as follows: Pari 1. Starting from the depth of cover (2.5 in.), proceed vertically to the lioe representing pipe spacing on centers (12 in.), and then Horizontally to the first ordi' nate of Part 2. Part B. Move parallel to the nearest upward sloping line, indicating "2 in. over" cover, to intersect the ordinate representing J in. pipe, and then proceed hori zontally to the first ordinate of Part 3. Part S. Proceed parallel to and along the nearest downward sloping line to intersection with the ordinate representing the panel output (34 Btu per so ft), ana then move horizontally to the right hand scale of Part 3 and read a required average water temperature in the coil of 106 F. , .'. Part 4. From the water temperature 106 F just found in Part 3, proceed ho1"1' zontaily into Part 4 to intersect the line representing insulation between the slao and fill. Directly below this intersection read 1.09 (on the bottom scale) as tn multiplier to be used. The . required panel input is, therefore, 1.09 x panel output, or 1.09 x 34 = 37- Btu per (sq ft) (hr). The total required panel input is 37.1 x panel area -- 37.1 x 480 = 17800 Btub. Panel Heating 583 Fw. 15. Relation of Water Temperatures and Coil Outputs to Coil Spacing and Depth op Burt for Floor Coils in Slabs on Grade CEILING AND WALL PANEL DESIGN Where coils are embedded in plaster on ceilings or walls, design pro cedure is simplified considerably by the physical limitations of the space available. For tube fastened to the underside of lath, the largest practical size is f in. O.D., while for ferrous pipes above the lath, it is 1 in. I.P.S. Therefore, the actual tube or pipe size selected is usually determined by the length of coil circuit and its flow resistance in consideration of the available circulating head. In order to obtain a reasonably even heat distribution over the finished plaster heating surface, pipes or tubes should be spaced on about 6 in. centers, and not over 9 in. centers. Within these limitations it is found in practice that heat output rates do not vary too seriously with variations m pipe and tube size and tube spacing. In general, for plaster ceiling panels with tubes or pipes spaced on to 9 in. centers, the temperature of the circulating water is about 10 to z5 deg above the desired surface temperature. The hourly heat output per square foot of panel surface may be found by means of Figs. 11, 12, and 13, and the calculations for room heat loss and UMRT, as previously illustrated in the example of floor panel design. HOT WATER PIPING When water is used as the heating medium, the piping layout and ar rangement should be based on the design principles outlined in Chapter ik *0r ,r^W0`I>ipe Forced Circulation Systems. The pressure drops through the coils should be carefully calculated, and it is recommended that all branch circuits and coils be balanced to provide for uniform distribution hy means of regulating valves or tees. Generally, a 15 to 20 deg total 584 CHAPTER 24 1956 Guide temperature drop is used in determining water flow rates, and a total pump head of more than 30 ft is undesirable due to noise caused by high water velocity. Panel systems involving several rooms and panels comprising a single zone, require that all coils be selected for the same inlet water tempera tures: Panel areas and pipe spacing must be selected to make this pos sible. INSTALLATION DETAILS, ACCESSORIES, AND CONTROLS Installation details, as given in Chapter 22, Hot Water Systems, also apply to piping systems for panel heating. Control problems of panel heating systems are discussed in Chapter 39, Automatic Control. Efficient venting of air from the coils may be obtained by arranging the circulation so that the air moves in the direction- of water flow to a high point in the system where an automatic float-type vent or connection to expansion tank should be provided for its release. Coils should be installed as nearly level as possible or, if they are on sloping surfaces due to structural conditions, they should be arranged to vent air at their high points. Arrangements of pumps, expansion tanks, drainage, and flow and return maina may be generally the same as for conventional hot water heating systems. SNOW MELTING The practicability of melting snow by means of heated coils has been demonstrated in a large number of installations in sidewalks, roadways, ramps, and runways. In addition to eliminating the need for snow removal, other advantages gained are greater safety to pedestrians and vehicles, and reduction of labor in removal of slush from floors. The design of a snow-melting system involves primarily (1) a determina tion of the heat requirement which depends on snow fall and atmospheric conditions, (2) the coil and piping design which depends on heat transfer from a panel and on friction loss in piping due to the circulating medium used, and (3) the selection or design of a heat exchanger for heating the cir culating medium. DESIGN Heating Requirements The heating requirements for snow melting are affected by four atmos pheric factors: (1) rate of snowfall, (2) air temperature, (3) wind velocity, and (4) humidity. The effects of these factors can be evaluated by con sideration of the action of snow falling on a warmed surface. The first flakes fall on a dry, warm surface, and are then warmed to 32 F and melted. The water from the melted snow soon forms a film over the entire area and starts to evaporate. The evaporation of the film is a mass transfer from the surface to the atmosphere. In addition, there is a heat transfer from the film to the ambient air and surfaces. Both the mass and heat transfers attain a maximum only when the film is entirely free of snow. Theoretically this is impassible because some time will elapse while the snow is warmed to 32 F. For all practical purposes, however, it is permissible to assume the snow to be melted as fast as it falls so that the surface may be considered entirely free of snow. The ratio of free area to total area is known as the free area ratio, A rWhen Ar = 1, there is no snow on the surface and the mass and heat trans- Panel Heating 585 Table 3. Snowfall Data fob Various Cities* City Numbeb or Readings with Maximum Temfebatube in 6-Houb Period below Freezing at Various Snowfall Rates Snowfall Rate in Equivalent Inches of Water per Six Hours. Total Readings Taken Assumed. Design Rate of Snowfall6 Col.I 0.00 to 0.24 Col. 2 0.25 to 0.49 Col. 3 0.50 to 0.74 Col. 4 0.75 to 0.99 Col 5 CcA. 6 s Col. 7 Albany, N. Y...........!................................ 2052 29 5 1 3720 0.16 Asheville, N. C............................................... 463 5 1 0 3536 0.08 Billings, Mont................... . 1640 .4 0 0 3532 0.08 Bismarck, N. D................................ ........ 2838 0 0 0 3720 0.08 Boise, Idaho............................................... 1300 3 0 0 3720 0.06 Boston, Mass............................................... 1323 11 4 2 3720 0.16 Buffalo, N. Y............................................. 1871 23 3 1 3720 0.16 Burlington, Vt............................................ 2390 9 0 0 3720 0.08 Caribou, Maine.. ......... 1363 19 1 0 1672 0.16 Chicago, 111............................................. 1498 3 0 1 2976 0.08 Cincinnati, Ohio .................... Cleveland. Ohio___ ... Columhna, Ohio . . Denver, Col................................................ Detroit, Mjcb................... 1045 1569 1351 1207 1830 30 2 0 41 40 52 0 3720 0.08 0 3720 0.08 0 3720 0.08 0 3720 0.08 0 3720 0.08 Evansville, Ind............................................... 916 5 1 1 3720 0.08 Hartford, Conn..................................... 1514 44 9 3 3720 0.25 Kansas City, Mo............................................ 1189 22 2 1 3720 0.16 Madison, Wise....................................... 2370 5 2 0 3720 0.08 Minnoanolis. Minn. 2703 7 0 0 . 3720 0.08 Oklahoma City, Okla........................... Omaha, Neb.......................................... Philadelphia, Pa......... . Pittsburgh, Pa................................................ Portland. Maina 613 1795 891 1365 2054 8 8 10 6 33 4 0 3720 0.16 1 .0 3720 0.16 2 1 3720 0.16 2 0 3720 0.08 4 1 3720 0.16 St. Lotifa, Mr* 1088 5 0 1 3720 0.03 Salt Lake City, Utah........................ 1482 5 0 0 3720 0.08 Spokane, Wash................ 1545 11 1 0 3720 0.16 Washington, D. C.......................................... 533 7 2 1 3348 0.16 New York, N. Y 0.16 , Data from U. 8. Weather Bureau. Based on readings taken 1:30 a.m., 7:30 a.m., 1:30 p.m., and 7:30 p.m. oany from November 15 to February 15 from 1940 to 1949. (Where the total readings are I**** than 3720 the 4V*** record ia less than 10 years). The difference between Col. 6 and the sum of readings in Cob. 2, 3, 'and 5 is the number of readings with a maximum temperature (in the 6-hr period) above freezing. The design rate is found as follows: Proceed to left (on'line from any city) from Column 5 until the column containing the tenth reading is found. Assume that the larger value in the haadjng of the selected 0^5 maximum value, and should he multiplied by 2 to obtain the maximum rate for a 6-hour penod. This maximum rate divided by 6 is the design rate per hour. This is equivalent to dividing the Iaret value in the heading of the selected column by 3. example: For Albany, N. Y. Columns 5 and 4 total six readings, and consequently the tenth reading . "Jf* Column 3, which has the larger value of 0.49 in the column heading. Dividing 0.49 by 3, the Hpmgn "%ier equivalent of 0.16 inches per hour is found, as listed in Column 7. ,,__ NewYork City record was not used in this tabulation since the records for that station were not oom- Pz&ule with those of the other stations. fers are at a maximum. When A, = 0, the snow covers the entire area and there is no mass or heat transfer. Research on the insulating effects of snow indicate that there are just three practical values for the free area ratio, Ar; they are 1, 0.5, and 0. A general rule to follow is that emergency areas should be designed with 586 CHAPTER 24 1956 Guide A, = 1; commercial areas (e.g,, sidewalks? around stores,, etc.) may be designed with 'A, = 0.5; and private drivew'aysVor^areas where low instal lation cdsts are imperative, may ^be designed with Ar = 0. For a more complete discussion of free ares*:ratio arfddts effect on system performance, see. Reference 6. . ..The-equations for .the heating requirements of a snow melting system have been derived and thoroughly explained in Reference 7. The general equation for slab output, is : ' 5o = 9> + Jm + A,(ge + 9b) ~ (7) where - "9i'= sensible heat transferred t6 snow, Btu per (hour) (square foot). gm = heat of fusion, Btu per (hour); (square foot). A,= ratio, gf snow./reeare) to total area, dimensionless. 9, = heat of vaporization, Btu per (hour) (square foot). Qi = heat transfer by convection ail'd radiation, Btu per (hour) (square foot). nre on in- . >. -t; CINTCM _ ' ' i !--- ===== - iV-V-: .. : Fig. 16. Detail op Snow Melting Panel - F as liepth of Finish Coatr--Assumed as V^.m. f concrete'. Finish Coat may be asphalt but then cover slab should be reduced from 3 in. Depth of slab should always keep thermal resistance equal to 3 in. of concrete. S * Depth required by structural design. The sensible heat, g,, to raise the temperature of the snow to 32 F is I- ;' ' 9. = 2.6s (32 --) (8) where j ' ' . -.f.- ... - a = rate of snowfall, see Table 3, inches of water equivalent per hour, t.~ air temperature, Fahrenheit. The heat of fusion, qm, to melt the snow is . 9'=746s ' . : : (9) The heat of vaporization, <?e, (mass transfer) is 9 = 1074(0,0201t) + 0.055)(0.185 - p..)Ar - (10) where . : 1: '' p,. = vapor prdssiire of moist air, inches of mercury. - The heat transfer, (convection and radiation) is ' y ' ' ' 9S = 11.4(0.0201v + 0.055)(i, - t.)A, . (11) where v = wind velocity, miles per hour. h = water film temperature, Fahrenheit. Panel Heating 587 In addition to determining the four heating requirements, it is neces sary to make allowance for back and edge losses. These losses vary from 30 to 50 percent, depending upon the slab construction. The equation for the required fluid temperature to provide an output q,, has been derived in Reference 7. For construction similar to Fig. 16, the equation is ' . f = 0.59o + t, (12) where . .` Ua = mean fluid temperature (antifreeze solution), Fahrenheit. Equation 12 will suffice for 1 in. IPS as well as % in. -- see Fig. 16. Tabus 4: Heat Output And Fluid Temperature fob Snow Melting Systems s Rats of Snowfall At 0.08 r.o- 0O f > o.o Qo Aa (a = 0 F ^ Velocity V 5 10 15 151 205 260 108 135 162 66 66 66 66 66 66 k = 10 F Velocity 9 5 10 15 127 168 209 97 117 138 64 64 64 65 65 65 h = 20 F Velocity 9 5 10 15 102 128 154 85 97 110 62 62 62 64 64 64 k = 30 F Velocity 0 5 10 15 75 84 70 75 60 ' 60 63 63 94 79 60 63 0.16 J.O <7o >218 273 327 193 233 274 165 191 217 135 144 154 !m ' 142 169 198 129 149 170 117 129 142 100 105 109 0.0 o 133 133 133 129 129 129 125 125 125 121 121 121 5 99 99 99 97 97 97 95 95 95 93 93 93 0.25 1.0 <7o 292 347 401 265 305 346 235 261 287 203 213 221 179 206 234 165 186 206 151 163 176 134 139 144 o.o Qo > 208 208 208 202 202 202 195 195 195 188 188 188 tin 137 137 137 134 134 134 131 131 131 127 127 127 Note: This table is based on a relative humidity of 80 percent for all air temperatures. * = Rate of snowfall, inches of water equivalent per hour (See Table 3). ' Ar = Free area ratio. ?o = Slab output, Btu per (hour) (square foot). ~ Air temperature, Fahrenheit. tm = Fluid temperature, Fahrenheit. Based on construction as shown in Fig. 16. ' v = Wind velocity, miles per hour. Values for s for certain cities are given in Table 3. Using the values for s given in Table 3, the appropriate values for and v, the values for q,, may be found in Table 4. In preparing Table 4, only values of pov for relative humidities of 80 percent , were used. The variation in q,, and tm for humidities of 75, 80, 85 and 90 percent are given in Reference 6, and may be calculated by solving Equations 13 and 14. = -537 (0.0201o + 0.055) A, Pav (13) ^ = -1074 (0.02011> -f 0-055) At dpmT . (14) When selecting the heat exchanger, it will be necessary to allow for the thermal properties of the anti-freeze solution. The manufacturer should be given data on the type and concentration of anti-freeze, the tempera- 588 CHAPTER 24 : 1956 Guide tore range of operation, the source of heat (steam, hot water, etc.), and the flow rate through the exchanger. /. Hydraulic Requirements After determining the heating requirements, it is necessary to determine the hydraulic requirements of the system. This can be done by means of the procedures explained in Chapter 4, Fluid Flow, but it is necessary to use the proper physical properties of the antifreeze solution. A complete discussion of the hydraulic problem is given in Reference 8. The main consideration is the proper allowance for' viscosity. Table 5 gives viscosities for two typical fluids used as antifreezes for snow melting systems. Notice the large increase in viscosity for both fluids--about 20 times--as the fluid.temperature changes from an operating temperature Table 5. Physical Properties of Antifreeze Solutions . Solution Freezing Protection Temp., F. % By Volume Item Fluid Temperature, F 0 80 120 -160 0' 31.4 - X 10> C t# -__ -- -- 1.92 0.839 65.1 1.14 0.854 64.4 0.77 0.874 63.6 Ethyleneglycol* ; --20 42.7 . X 10* - C to 16.1 2.55 0.764 0.813 66.8 66.0 1.46 0.832 65.3 0.95 0.856 64.4 --J0 51.2 -Xio* to 21.3 3.16 0.717 0.788 67.6 66.8 1.77 0.809 65.9 1.14 0.835 65.0 Light Oilb --40 100 * X 10 c tz? 43.1 5.60 0.390 0.426 62.5 60.7 3.13 0.444 59.8 2.06 0.462 59.0 * Interpolated from Reference l0. ^ From Socony-Vacuum Oil Co. v -- kinematic viscosity, (feet squared per second) (e.g. for oil at 80 F, r = 0.000050 ft* per sec.) c = specific heat, Btu per (pound) (Fahrenheit degree). . tz? = specific weight, pounds per cubic foot. . of 160 F to the starting temperature of 0 F. This viscosity change has two effects. First, an increase in viscosity will increase the fluid friction in the piping circuit. Second, an increase in viscosity will decrease, the pump capacity--in both volume and head. The effect of viscosity on fluid friction in the piping circuit is illustrated in Fig. 17. For. large installations, the friction .losses should be calculated by the Fanning equation . . : ' }IV' hi 2gD, where hi = the loss in head of the fluid under conditions of flow, in feet. ` 1 = the length of the pipe, in feet. V -- the velocity, in feet per second. . : g -- the acceleration due to gravity = 32.174 ft per (second) (second). D = the internal diameter of the pipe in feet. PanelHeating 589. f. = a dimensionless friction coefficient which, can be determined :from Fig. 4, Chapter 4. The Reynolds number can be computed from data in Table 5. Solutions for the pipe friction should be plotted for temperatares'at the starting condition (probably. 0 F) and at the operating condition (use either 120 or 160 F). Then on the same graph plot the operating curve of the pump (see Reference 8 for such a graph). The intersection of the fluid friction curve and pump operating curve will give the operating point for the system. Use the data in Table 6 to allow for the viscosity effect on the pump. The designer must decide on the tolerable viscosity limit. Generally it is between 300 and 500 SSU, although for commercial or private systems (where Ar is 0!5 or 0) it may go to 750 SSU. - Fig. 17. Effect of Viscosity on Friction Loss (For 1-in. Pipe) Efficiency loss is not important, but head and capacity losses are. Re duced flow means a longer period of time for the system to become opera tive from a cold start. ' The viscosity , limit is controlled by means of a low-limit thermostat. For example, if. it is desired to hold the viscosity of the solution to less than 200 SSU (43.1 ft sq per sec), then for the oil shown in Table 5, the low unit control would be set at 0 F. .. For small installations, a quick method of determining the fluid friction for a one-inch IPS pipe circuit is given in Fig. 17. > ' The pump capacity, in pounds of fluid per hour is given by where r- ^ CnAt F -- pump capacity, pounds per hour. Ap = area of slab, square feet. . (15) 590 CHAPTER 24 1956 Guide qt m total heat requirement (slab output, q0, plus back and edge losses) Btu per (hour) (square foot). ; n> = specific heat at temperature tm, Btu per (pound) (Fahrenheit degree). A, = temperature drop through circuit, Fahrenheit degrees. For a temperature drop of A( = 20 F, Equation 15 becomes Apgt G= . 160utnCm (16) where G = gallons per minute. .: . u>a = mean specific weight at temperature tm, pounds per cubic foot. INSTALLATION There are certain precautions that must be taken during installation. They concern internal corrosion, flammability, toxicity, cleaning, joints, Table 6. Viscosity Effect on Centrifugal Pump Chabactebistics Kinematic Vibcositt ssu* 0 to 30 50 100 200 300 400 500 600 700 800 900 1000 Pump Head 1.00 1.00 0.98 0.96 0.95 0.93 0.92 0.91 0.90 0.89 0.88 0.87 Correction Factors Pump Capacity 1.00 1.00 1.00 0.98 0.97 0.96 0.96 0.95 0.94 0.94 0.93 0.92 Pump Efficiency 1.00 0.94 0.88 0.79 0.73 0.68 0.65 0.62 0.59 0.57 U.55 . 0.53 flSU = Universal Sayfoolt second. and hookup. A comprehensive discussion of these precautions may be found in Reference 9. Safety Since ethylene glycol and petroleum distillates, are slightly toxic, the system should be installed and maintained independently. There should lie no permanent connection between the snow melting system and the drinking water supply. Ethylene glycol is not considered flammable. In fact, aqueous solu tions of less than 60 percent glycol are used for fire sprinkler systems. These solutions do not freeze, and they are effective fire extinguishing agents. Petroleum distillates suitable for fluids in snow melting systems are classified as non-flammable, but have fire points between 300 and 350 F. When using fluids of this type, care should be taken to collect any oil drip ping from the seals on the pump. It is good practice also to provide some barrier between the oil lines and the boiler so that in the event of a leak, a flash back from the boiler will not ignite the oil. Panel Heating 591 There are other non-flammable fluids, such as those used in some trans formers, that can be used as the antifreeze. These fluids are three or four times as expensive as the glycols or oils, but combine the fire protection of the glycols with the corrosion protection of the oils. Internal Corrosion ; . : .v; \. : Ethylene glycol solutions tend to become corrosive in service; therefore, rust inhibitors are generally included. Even with an inhibitor, the solu tion should be tested annually to determine any change in acidity. If: the test indicates that the inhibitor has been exhausted, the entire system should be drained and a fresh solution installed. ... . . . To increase the life of the inhibitor, the heat exchanger surfaces should be kept below 285 F which corresponds to about 40 psig steam. Tempera tures above 300 F accelerate the deterioration of the inhibitors. Slab Construction v It has been found satisfactory to use % pipe or tubing on 12-in. centers as a standard coil. If pumping loads require a reduction in friction the pipe- size may be increased to 1-in., but the slab depth must be increased ac cordingly. ____ The piping should be supported in such a manner that there is a minimum of 2 in. of concrete above and below the pipe. This requires a 5-in. slab for ^-in. pipe and 5M-in. for 1-in, pipe. ..... If an insulating material is used, it is generally good practice to provide a moisture barrier between the insulation, and the fill. A roofing material (such as a 55 lb. felt) is often used as a moisture barrier. The joints should be mopped, and the fill; made, smooth enough so that there will be no holes or gaps for moisture transfer. ' Also, the edges `of the barrier should: be flashed to the surface of the slab so that the ends are sealed. . See Fig. 16. If the pipe must pass through an expansion joint, a protective coating should be applied to the pipe for a foot or two on both sides of the joint. If the pipe is kept dry at all times in both summer and winter, no ex ternal corrosion problems will occur. > ' : - - Thermal Stresses . . ^ i This problem is discussed in Reference 11. In general, there will be no ill effects from the thermal stresses if these rules of installation and opera tion are followed: 1. Keep the temperature difference between the fluid and the slab surface to a minimum by: . .. . : a. Close pipe spacing (see Fig. 16). . - b. Low temperature drop in fluid. At < 20 F deg. c. Continuous operation (if economically feasible). . . . 2. Keep pipe near surface--about 2 in. cover. ' ; ! : : ' :i ' 3. Use reinforcing steel designed for thermal stress if high structural'loads are expected (such as on highways).. . . .. . , . . ;.. , Testing - After installation and before pouring concrete, all piping should be tested to about-100 psi. This pressure should be maintained until all welds and connections have been checked for leaks. If an oil is used as an anti freeze, the test should be performed with air or some gas (only 50 psi re quired with an air test) but not with water. The danger of using water is that the pipe may not be thoroughly dried when the oil is introduced. 592 CHAPTER 24 1956 Guide The water will tend to collect, and when the temperature falls below 32 F the collected water may freeze and cause damage. / Draining Proper drainage is necessary for both the slab surface and the coil. The slab must be sloped so that the water from the melted snow can run off. Puddles are objectionable on sidewalks or drives. They cause splashing, and they retard heat flow from the embedded pipes. The pipes must be placed so that they may be drained. If the anti freeze becomes corrosive it must be drained. It is not good practice to rely entirely on blowing of air through the system. Drifting Snow It is quite likely that some drifting will occur on every, system that is adjacent to a wall or vertical surface. The designer should try to antici pate this condition and add extra piping in these areas. If possible, coils should be added in the vertical surface. Another expedient is to carry the drainage to the area expected to be drifted. The drainage will tend to wash away some of the snow. Design Example Example Design a snow melting system for an area of 10,000 sq ft in Pittsburgh Pa. 'using a free area ratio of 0.5. Assume an air temperature of 10 F and a wind velocity of 10 mph. Use an oil antifreeze solution. Solution : From Table 3 select a snowfall rate of 0.08. From Table 4 find the re quired heat output of top of slab as g,, = 168 for A, = 1, and g,, = 64 for A, =0. Then for A, = 0.5 use g0 = 116 because 0.5(168--64) + 64 = 116. From Equation 12 tm = 0:5g,, + t, = (0.5 X 116) + 33 = 91 F. Assume that back and edge losses are 40 percent. Then the total heat require ment on heat exchanger is Apg, = 10,000 X 1.40 X 116 = 1,624,000 Btuh. From Equation 16 q __ Aqi 160WmCm 1,624,000 160 X 60.5 X 0.431 390 gpm (Interpolating from Table 5, wm = 60.5 and cm => 0.431 for ta = 91 F.) Since a temperature drop of 20 deg was used, the fluid must enter the slab at 101 F and leave at 81 F. Assume that the coil circuit of longest equivalent length is 300 ft and has a flow of 12 gpm and the pipe is 1-in. IPS. From Table 1, Chapter 27, the I.D. = 1.049 in. = 0.0875 ft and the I. D. section area = 0.864 sq in. = 0.00600 sq ft, hence for 12 gpm, the flow is 0.0268 cu ft per sec and the velocity 0.00600 - 4.47 fps. Interpolating from Table 5, the kinematic viscosity is 4.92 X 10"s ft' per sec (An accurate interpolation requires the use of ASTM Standard Viscosity chart B.) . VD 4.47 X 0.0875 Hence the Reynolds number =----- = 4.92 X 10-` 7950 From Fig. 4 of Chapter 4, using a roughness factor of e = 0.00015, whence e/D Panel Heating 593 0.00172, the friction factor f is found to be 0.0355. Substituting in the Fanning equation L Vs ,,,, 300 4.47* h` = fxDx^-om55xtwExjr3 = 37.9 ft of fluid = 15.9 psia. The pump must deliver 390 gpm against a 15.9 psia head. The heat exchanger must deliver 1,624,000 Btuh with an inlet temperature of 81 F and an outlet tempera ture of 101 F. (Actually an allowance should be made for temperature drop in the piping between the slab and the heat exchanger.) The expansion tank should be designed in accordance with the procedure outlined in Chapter 22, Hot Water Heating Systems. The amount of expansion should be based on the change in volume from 0 F to 91 F. From Table 5, determine u> = 62.5 lb per cu ft at 0 F, and w = 60.5 lb per cu ft at 91 F. From Table 1, Chapter 27, 10,000 ft of 1-in. IPS contains 44.9 gal. Allowing another 15 gal for heat exchanger, headers, etc., assume the system contains 60 gal. Then the expansion woud be 60(62A-60j)= 248gal A quick approximation of required head can be obtained from Fig. 17. At 91 F, the oil has a viscosity of 4.92 X 10rS ft sq per sec or 35 SSU. Enter Fig. 17 at 35 SSU and rise to-the_12 gpm curve, read h = 12.5 ft per 100 ft, then hi -- 12.5 X 222 = ^ 100 37.5 ft, which agrees fairly well with the 37.9 ft obtained b y the Fanning equation. REFERENCES 1 Standard Specifications for Gypsum Plastering, including Requirements for Lathing and Plastering (American Standards Association, A42.1, 1946). ' 1 Code and Manual for the Design and Installation of Warm Air Ceiling Panel Sys tems (Manual 7-A of the National Warm Air Healing and Air Conditioning Associ ation). * Various investigations of W. Nusselt (1915-1928) as discussed in Chap. 23 and Chap. 25, and tabulated in Author Index of Heat Transfer, by Max Jakob, Vol. I, 1949 (John Wiley and Sons, New York). 4The Transmission of Heat by Radiation and Convection, by Ezer Griffiths & A. H. Davis (Special Report No. 9,1922, Department of Scientific & Industrial Research, His Majesty's Stationery Office, London, England). . 4 Radiation and Convection from Surfaces in Various Positions, by G. B. Wilkes and C. M. F. Peterson (ASHVE Transactions, Vol. 44,1938, page 513). 4Design Conditions for Snow Melting, by W. P. Chapman (.Healing and Ventilating, November, 1952, p. 88). 7 Design of Snow Melting Systems, by W. P. Chapman (Healing and Ventilating, April, 1952, p. 95). . 4 Snow Melting System Hydraulics, by W. P. Chapman (Air Conditioning, Heating and Ventilating, November, 1955). Anti-Freeze Protection for Snow Melting Systems, by P. B. Gordon (Official Bulletin, Heating, Piping and Air Conditioning Contractors National Association, February, 1950, p. 21). "Properties of Ethylene Glycol and Its Aqueous Solution, by C. S. Cragoe (National Bureau of Standards CRC Report No. 9, Society of Automotive Engineers). u Are Thermal Stresses a Problem in Snow Melting Systems? by W. P. Chapman (Healing, Piping and Air Conditioning, June and August, 1955). BIBLIOGRAPHY Trend Curves for Estimating Perormance of Panel Heating Systems, by B. FRaber and F. W. Hutchinson (A.S.HV.E. Transactions, Vol. 48,1942, p. 425). A.S.H.V.E. Research Report No 1192--Panel Heating and Cooling Performance Studies, by B. F. Raber and F. W. H.utchinson (A.S.H.V.E. Transactions, Vol. 48, 1942, p. 35). A.S.H.V.E. Research Report No. 1193--Radiation as a Factor in the Feeling of Warmth in Convection Radiator and Panel Heatid Rooms, by F. C. Houghten, Carl Gutberlet and E. C. Hach (A.S.H.V.E. Transactions, Vol. 48,1942, p. 55). 594 CHAPTER 24 1956 Guide Panel Heating and Cooling Analysis, by B. F. Raber and F.-W. Hutchinson (A.S.H.V.E. Transactions, Vol. 47, 1941, p. 285). , Operating Results of a Residence Radiant Wall Heating System, by E. J. Rodee (A.S.H.V.E. Transactions, Vol. 47, 1941, p. 123). Performance of a Residential Panel Heating System, by H. F. Randolph and J. B. Wallace (A.S.H.V.E. Transactions, Vol. 49, 1943, p. 235). Radiant Heating {Heating and Ventilating, March, 1941, p. 35). Radiant Heating and Cooling, by F. E. Giesecke {Heating, Piping and Air Condi tioning, June, July, August, September and October,c0). . Calculations for Radiant Heating, by T. Napier Adlam {Heating and Ventilating, October, 1931). ' . .' * T n Radiant Heating and Cooling, Part I, by C. 0. Mackay, L. T. Wright, Jr., R. E. Clark, and N. R. Gay {Cornell University Engineering Experiment Station, Bulletin No. 32,1943). m ^ ^ xr ^ -Design Method for Panel Heating Systems Using Copper Tubing, by R. G. Vander- weil (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, Nov. - Air .Temperature Gradients in a Panel Heated Room, by J. M. Ayres and B. W. Levy (A.S.H.V.E. Transactions, Vol. 54, 1948, p. 131). -_ Graphical Solution of Radiant Panel Areas, by W. P. Chapman and R. E. Fischer {Heating and Ventilating, Jan. 1948, p. 88). Embedding Coils in Radiant Heating Panels, by D. L. Mills and L. J. LaTart {Heating and Ventilating, Dec. 1947, p. 75). , Radiant Heat with Copper Tubing, by D. L. Mills and L. J. LaTart {Heating and Ventilating, Nov. 1947, p. 95). . . , __ _T Panel Heat with Copper Tubing--Experiment m Practice, by D. L. Mills and L. J. LaTart {Heating and Ventilating, Oct. 1947, p. 65). Experimental Studies bn Panel Heating Tube Spacing, by B. F. Raber and F. W. Hutchinson (A.S.H.V.E. Transactions, Vol. 53, 1947, p. 369). Panel Heating--A Basic Discussion, by S. Konzo {American Artisan, Oct. 1946, P Mar House Heated by a Warm. Air Floor Panel, by John E. Peterson {American Artisan, Dec. 1946, p. 83). . ` .. Design Data for a Warm Air Floor Panel, by Axel B. Algren {American Artisan Jan. 1947, p. 141). .. T .c The Mechanism of Heat Transfer, Panel Cooling, Heat Storage, by Charles fc>. Leopold {Refrigerating Engineering, July 1947, p. 33) Radiant Heating--Simplified Design and Installation {Copper and Brass Research Association 1949). Research Report No. 1387--Laboratory Studies on Heat Flow Within a Con crete Panel, by C. M. Humphreys, H. B. Nottage, C. V. Franks, R. G. Huebscher, L. F. Schutrum and D. W. Locklin (A.S.H.V.E. Transactions, Vol. 56, p. 175). . Research .Report'No. 1388--Heat Flow Analysis in Panel Heating or Cooling Sections, by L: FL Hulbert,. H.. B. Nottage and C. V. Franks (A.S.H.V.E. Trans actions, Vol! 56, 1950, p. 189). _, , ,, Ta Electric Analogger Studies on Panels with Imbedded Tubes, by Carl b. Kayan (A.S.H.V.E. Transactions, Vol. 56, 1950, p. 205). Books .............. . Hoi Water Heating, Radiant Heating and Radiant Cooling, by F. E. Giesecke (Tech nical Book Co:, P. 0. Box 62, Austin, Tex. 1947). Panel Heating and Cooling Analysis, by B. F. Raber and F. W. Hutchinson (John Wiley and Sons, New. York, 1945). Radiant Heating, by T. Napier Adlam (Industrial Press, 148 Lafayette St., New York 1947) . - - Radiant Healing, by R. W. Shoemaker, 1948 (McGraw-Hill Book Co., New York). Chapter V (pages 103-115): of Heating and Air Conditioning, by J. R. Allen, J. H. Walker, and J. W. James (McGraw-Hill Book Co., New York--Sixth Edition, 1946). Chapter 12 (pages 363-392) of Heating, Ventilating and Air Conditioning Funda mentals, by W. H. Severns and J. R. Fellows (John Wiley and Sons, New York, Second Edition, 1949). ; . CHAPTER 25 UNIT HEATERS AND UNIT VENTILATORS Definitions; Unit Heaters: Classification, Application, Ratings,.Location, Space Temperatures, Control, Piping, Maintenance, Boiler Capacity; Unit Ventilators: Ratings, Capacity Requirements, Application, Selection, Control, Location, Exhaust Flues; Window Ventilators \ THE generally accepted meaning of the word unit in the terms unit' heat ers; unit ventilators, and unit humidifiers, is that of a factory-made encased assembly of the functional elements indicated by its name.1 The term unit heater denotes ah assembly of elements, the principal function of which is heating. The essential elements of a unit heater are a fan and motor, a heating element, a housing, and outlet vanes or diffusers. Some types-arejshown in Figs. 1 to 4. 'Die term unit ventilator denotes an assembly, the principal function of which is to ventilate and cool the space by the introduction of outdoor air. It may serve to heat and circulate the air within the space; or introduce air from outdoors, or may accomplish both in varying proportions. The essential elements of a unit ventilator are fans and motor, heating element, dampers, and outlet grilles or diffusers, all encased, in a housing. Classification UNIT HEATERS The various types of unit heaters which are at present available can usu ally be classified according to one of the three following methods: 1. By tyPe f heater. Under this classification there are three types of heating elements to be considered: (o) the steam or hot water type, (b) the electric type, and (c) the direct fired type which may be gas, oil, or coal fired. 2. By type of fan. Under this classification there are two types of fans to be considered: (a) the propeller type1 and (6) the centrifugal type. Either type may be arranged for horizontal or vertical delivery of air. 3. By arrangement of elements. Under this classification there are two types of heaters to be considered: (a) the draw-through type, in which the fan draws air through, and (b) the blow-through type, in which the fan blows air through the heater. ; Unit heaters are available in any combination of the three preceding gen eral classifications. For example, the steam or hot water type may be secured with either the propeller or centrifugal type of fans, and in either the draw-through or blow-through type. Unit heaters also vary in other minor respects. For example, steam and return inlets and outlets may be located on top and bottom, respectively, or on the same side of the unit. Some units are supported by the piping and some have independent supports. The heating surface of steam or water type units is generally made up of a non-ferrous tube-and-fin assem bly; or it may be fabricated of steel, of cast in steel or iron. 595 596 CHAPTER 25 1956 Guide Fig. 1. Centrifugal Fan Type Unit Heater--Floor Mounted CEILING U OPTIOMA1 Fig. 3. Propeller Fan Type Unit Heater-Horizontal Blow Fig. 4. Propeller Fan Type Unit Heater-Vertical Blow Unit Heaters and Unit Ventilators 597 Application of Unit Heaters There are three major factors to consider in the application of unit heat ers, namely: (1) heating medium, (2) air distribution, and (3) location of unit. Steam or hot water unit healers are used principally for heating com mercial and industrial structures such as garages, factories, laboratories, and stores. They may also be used for heating finished rooms, if properly applied and concealed, and if some consideration is given to the problem of noise. . Unit heaters may also be adapted to a number of industrial processes, such as drying and curing, in which the use of heated air in rapid circulation with uniform distribution is of particular advantage. They may be used for moisture absorption, such as fog removal in dye houses, or for the pre vention of condensation on ceilings or other cold surfaces of buildings in which process moisture is released. When such conditions are severe, it is necessary that the unit heaters draw air from outside in enough volume to provide a rapid air change, and that they operate in conjunction with ventilators or fans for exhausting the moisture-laden air. (See discussion of condensation in Chapter 10.) Electric unit heaters can be used to advantage for supplemental heat in residences, for the heating of ticket booths, watchmen's offices, factory offices, locker rooms, and other isolated rooms scattered over large areas. They are particularly useful in isolated and untended pumping stations or pits where they may be thermostatically controlled to prevent freezing temperatures. Gas-fired, unit heaters find application in industrial plants, offices, stores, garages; in fact, in almost every location where steam-type units are.used. The installation cost of gas-fired units is usually less than that of a' type requiring that a new boiler be installed, unless the number to be installed would justify the cost of a boiler and steam of hot-water unit heater system. Oil-fired unit heaters are used in industrial plants, garages and commercial buildings. Coal-fired unit heaters are used principally in large industrial plants such as foundries. Outlet Velocities Outlet velocities of unit heaters vary from about 400 to 2500 fpm, depend ing upon the type of unit .and the distance (blow) to which the air to is be projected. Noise and drafts must be considered in the choice of air veloci ties, since both generally increase with increase of air velocity. In the selection of unit heaters it is important to ascertain that the blow and coverage are sufficient. The blow is dependent to a marked degree on the temperature of air leaving the heater, as well as upon its velocity. (See discussion under heading of Inlet, Outlet, and Space Temperatures with Unit Heaters.) Recommended coverage and mounting heights should be obtained from the manufacturer. In order to obtain the desired air distribution and heat diffusion, unit heaters are commonly equipped with directional outlets, adjustable louvers, - or fixed types of diffusers. . Ratings of Unit Heaters . It is standard practice to rate unit heaters .on the basis of the amount of heat delivered by the air in Btu per hour above an entering air temperature CHAPTER 25 1956 Guide Table 1. Constants fob Determining the Capacity of, Unit Heaters fob Various Steam Pressures and Temperatures of Entering Air ' (Baaed on Steam Pressure of S psig and Entering Air Temperature of 60 F) Steam Phes- PBIQ -10 0* - Temperature op Entering Air 10* 20 30 40 50" 60*- 70* 80* 90* 100* W a o a o . Eah - - .. . . 0 1.54 1.45 1.37 1.27 1.19 1.11 1.03 0.96 6.88 0.81 0.74 0.67 2 1.59 ' 1.50 1.41 1.32 1.24 1.16 1.08 1.00 0.93 0.85 '0.78 0.71 6 1.64 1.55 1.46 1.37 1.29 1.21 1.13 1.05 0.97 0.90 0.83 0.76 10 1.73 1.64 1.55 1.46 1.38 1.29 1.21 1.13 1.06 0.98 0.91 o:s4 15 1.80 1.71 1.61 1.53 1.44 1.34 1.28 1.19 1.12 1.04 0.97 0.90 20 1.86 1.77 1.68 1.58 1.50 1.42 1.33 1.25 1.17 1.10 1.02 0.95 30 1.97 1.87. 1.78 1.68 1.60 1.51 1.43 1.35 1.27 1.19 1.12 1.04 40 2.06 1.96 1.86 1.77 1.68 1.60 1.51 1.43 1.35 1.27; 1.19 1.12 50 2.13 2.04 1.94 1.85 1.76 1.67 1.58 1.50 1.42 1.34 1.26 1.19 60 2.20 2.09 2.00 1.90 1.81 1.73 1.64 1.56 1.47 1.39 1.31 1.24 70 : 2.26 2.16 2.06 1.96 1.87 1.78 T.70 1.61 1.53 1.45 1.37 1.29 76 2.28 2.18 2.09 1.99 1.90 1.81 1.72 1.64 1.55 1.47 1.40 1.32 80 2.31 2.21 2.11 2.02 1.93 1.84 . 1.75 1.66 1.58 1.50 1.42 1.34 90 2.36 2.26 2.16 2.06 1.97 1.88 1.79 1.71 1.62 1.54 1.48 1.38 100 2.41 2.31 2.20 2.11 2:02 1.93 1.84 1.75 1.66 1.58 1.50 1.42 125 2.51 2.41 2.31 2.21 2.11 2.02 1.93 1.84 1.76 1.68 1.59 1.51 150 2.60 2.50 2.40 2.30 2.20 2.11 2.02 1.93 1.84 1.76 1.67 1.59 W ' >* ` H 0 1.48 1.41 1.33 1.25 1.18 1.11 1.03 0.96 0.89 0.82 0.75 0.69 2 1.52 1.44 1.36 1.29 1.22 1.14 1.07 1.00 0.93 0.86 0.79 0.73 5 1.57 1.49 1.41 1.33 1.26 1.19 1.11 1.05 0.98 0.91 0.84 0.77 10 1.64 1.56 1.48 1.40 1.33 1.25 1.18 1.11 1.04 0.97 0.90 0.84 15 1.69 1.61 1.53 1.46 1.38 1.31 1.24 1.17 1.10 1.03 0.96 0.90 a a o aEh Be 20 1.73 1.65 1.57 1.50 1.42 1.35 1.28 1.21 1.14 1.07 1.00 0.94 .0130 1.80 1.73 1.65 1.57 1.50 1.42 1.35 1.28 1.21 1.15 1.08 i 40 1.86 1.79 1.71 1.64 1.56 1.49 1.42 1.35 1.28 1.22 1.15 1.08 50 1.93 1.85 1.77 1.70 1.63 1.55 1.48 1.42 1.35 1.28 1.21 1.15 60 1.97 1.90 1.82 1.75 1.67 1.60 1.53 1.46 1.40 1.38 1.26 K19 S' Q 70 2.02 1.94 1.87 1.80 1.72 1.65 1.58 1.51 1.44 1.38 1.31 1.24 75 2.04 1.97 1.90 1.82 1.75 1.68 1.61 1.54 1.47 1.40 1.33 1.27 80 2.06 1.99 1.91 1.84 1.77 1.70 1.63 1.56 1.49 1.42 1.35 1.29 90 2.10 2.03 1.95 1.88 1.80 1.73 1.66 1.59 1.52 1.46 1.39 1.32 100 2.15 2.07 1.99 1.92 1.85 1.77 1.70 1.63 1.56 1.49 1.43 1.36 125 2.21 2.14 2.06 1.99 1.91 1.84 1.77 1.70 1.63 1.56 1.49 1.43 150 2.28 2.20 2.13 2.05 1.98 1.91 1.84 1.77 1.70 1.63 1.56 l.M Note: To determine capacity at any steam pressure and entering temperature, multiply rated capacity at 60 F entering air and 2 psig by constant from tabce. When increasing steam pressure it is important to determine whether the heater is suitable for the increased pressure application, and whether the resulting increased outlet temperature is satis factory. . of 60 F. This applies to all types of unit heaters, the steam or hot water type, the electric type and the direct fired type. There are, however, other factors which must be taken into account, especially when an attempt is made to compare one type of heater with another. These are the tem perature of the heating element and the velocity of air through it. Con sideration is given to these factors in the discussion of ratings for each type of unit heater in the following paragraphs. Steam. Rating of steam unit heaters has been standardized by a code2 in which the following items are the basis of rating: dry saturated steam at Unit Heaters and Unit Ventilators 599 2 psig pressure at the heater coil; air at 60F (29.92 in. Hg barometric pressure) entering the heater;.and heater operating free..of external resist-: ance to air flow. ... ' ' . - ' : The capacity of a heater increases as the steam pressure increases, and decreases as the entering air temperature increases. The heating capacity for any condition of steam pressure and entering air temperature other than standard may be calculated approximately from any given rating by the use of factors in Table 1 for the blow-through or draw-through types; ' Hot Water. A standard for the rating of hot water type unit heaters has also been established by code* in which the following items are the basis; of rating: entering water at 200 F; entering air at 60 F (29.92 in. Hg baro metric pressure); and heater operating free of external resistance to air flow. This code also prescribes a method of translating the output in Btu and the temperature rise as obtained-under test conditions to stand-' ard conditions of air and water temperature. :: : Electric. Electric type unit heaters are available in sizes up to at least 60 kw capacity. They consist of resistance type heating elements combined with fan and motor, together with a suitable casing. Electric unit heaters are rated on the energy input to the heater, expressed in terms of kilowatts, Btuh or EDR (Equivalent Direct Radiation). Gas-Fired. Gas-fired unit heaters are built in both suspended and floor models, with either propeller or centrifugal type fans. They are rated in . terms of both input and output in accordance with the approval require ments of the American Gas Association. :. Oil-Fired. The oil-fired unit heater is usually equipped with a centrif ugal fan or fans and is available in either the floor-mounted or in smaller sizes in the suspended type; Ratings are based on heat delivered at heater outlet in Btu per hour. Stoker-Fired. The stoker-fired unit heater can be obtained in a wide range of capacities. Ratings are based on Heat delivered at the heater outlet in Btu per hour. , . - Effect of Resistance Upon Capacity ; ............ Unit heaters are customarily rated as free delivery type units. If out-, side air intakes, air filters, or ducts on the inlet or discharge are used, a reduction in air and heating capacity will result because of this added resistance to air flow. The percentage of this reduction in capacity will depend upon the characteristics of the heater, and on the type, design, and speed of the fans, so that no specific percentage reduction can be assigned for all heaters at a given added resistance. The heat output to be expected under other than free delivery conditions should be secured from the manu facturer. Location of Unit Heaters Care should be taken in the location of unit heaters to insure free air circulation to the intake and proper heat distribution over the working level. Manufacturers' catalogs usually give suggestions for best arrange ments of the various heaters. Types and makes of available heaters are shown in the Catalog Data Section of this volume. . . , Hot blasts in working zones should have their discharge outlets above the head line, and suspended heaters should be so adjusted that the heated air stream will not be objectionable. . : .. In connection with the use of vertical type unit heaters, care must be t 600 CHAPTER 25 1956 Guide exercised in the selection of the heater. It has been found that the higher the unit is placed above the floor, the lower must be the butlet temperature of the air leaving the heater in order that the heated air may be forced into the occupied zone. Inlet, Outlet and Space Temperatures with Unit Heaters In the selection of unit heaters for any particular design, consideration should be given to the temperature of air entering the heaters, as well as the temperature to be maintained in the working zone of the space. In general, the temperature differences per foot of elevation, when using unit heaters, are less than corresponding variations when using direct radiation.* High velocity, units will maintain slightly lower temperature differences than low discharge velocity units. Correspondingly, units with lower dis charge air temperature will maintain lower temperature differences than units with higher discharge temperatures. Directional control of the dis charged air from a unit heater can be an important factor, added to qualities of reasonably good outlet velocity and outlet temperature, in effecting satisfactory distribution of heat and reducing floor-to-ceiling temperature difference. Since the outlet temperature of air from a unit heater increases with the temperature of the heating medium, such as high pressure steam, heaters can be obtained with heating elements having less than the regular amount of heating surface in order to obtain, with the high temperature heating medium, approximately the same leaving air temperature as would be ob tained from a lower temperature heating medium. When some outside air is introduced, the temperature of the mixture of outside and recirculating air must be calculated and used as the entering air temperature at the heater. Unit heaters connected in this manner per form the function of unit ventilators. For a discussion of this function see the section of this chapter entitled Unit Ventilators. For recirculating heaters located at the floor or with intakes at the floor, the temperature of air entering the heater should be assumed to be the same as that to be maintained in the room itself. Automatic Control of Unit Heaters Thermostatic control of unit heaters may be accomplished either by starting and stopping the fan, or by controlling the flow of the heating medium to the heating element. Unit heaters may be used in summer as a means of circulating air to give some measure of comfort due to air mo tion. In such cases the heating element should be shut off from the source of heat. The thermostat should be provided with a by-pass switch which will permit the fan to be operated independently of the . room temperature. ' Piping Connections For Steam Unit Heaters Piping connections for steam unit heaters are similar to those for other types of fan blast heaters. The piping of unit heaters must conform strictly to the system requirements while at the same time permitting the heaters to function as intended. The basic piping principles for steam systems are discussed in Chapter 21. Rapid condensation of steam, especially during heating-up periods, is characteristic of this type of equipment. The return piping must be planned to keep the heating coil free of rapid condensation, while the steam Unit Heaters and Unit Ventilators 601 Fig. 5. Unit Heateb Connection to Low Pressure Steam Gravity System piping must be ample to carry a full supply of steam to the unit to take the place of that condensed. Adequate sizes of piping are especially important where a unit heater fan is operated under start-and-stop control, and where all or part of the air is taken from the outside. In such installations the condensation rate may vary rapidly, and the necessity for ample pipe capac ity is particularly important. Piping connections for unit heaters as recommended by the Industrial Unit Heater Association are shown in Figs. 5 to 9. In steam systems the branch from the supply main to the heater should pitch toward the main, and be connected to its top to prevent condensation in the main from draining through the heater where it might reduce capac ity and cause noise. The return piping from steam heaters should provide a minimum drop of 10 in. below the heater so that the head of water required to overcome resistances of check valves, traps, and strainers will not cause condensa tion to remain in the heater. Dirt pockets shown in Figs. 5 to 7 are essential, and strainers are recom mended as an additional means of retaining dirt and scale which might affect operation of check valves and traps. Return piping between the heater and strainer should be of the same size as the heater outlet. Strain ers should always be installed in the steam supply line if the heater is equipped with the steam distributing type of coils. An adequate air vent is required for closed low pressure gravity systems. The vertical pipe connection to the air vent should be at least % in. I.P.S. to permit separation of the water from the air passing to the vent. In vacuum systems, if thermostatic instead of float and thermostatic traps are used, a cooling leg must be provided ahead of the trap. Pm. 6. Unit Heater Connection fob Vacuum ob Vapob Steam System 602 CHAPTER 25 . 1956 Guide Pig. 7. Unit Heater Connection to High Pressure Steam System In high pressure systems it is customary to vent the air through a pet cock which is left slightly open at all times. Where possible it is advisable to' install, pressure reducing, valves to permit operation of the heaters at lower pressure. Traps used must be suitable for the operating pressure encountered. . In connecting piping to hot. water unit heaters, the piping should be pitched to permit escape of air to the high point in the piping where it can be vented to the atmosphere. An air vent at the heater is used to facilitate air removal or to vent the top of the heater. Provision should be made for complete drainage of the system if shutdown in freezing weather is possible. Maintenance . . Regular inspection based upon a schedule determined by the amount of dirt in the atmosphere will insure maximum economy in operation and maintenance of heating capacity. . Heating elements should be cleaned when necessary by brushing or blow ing with high-pressure air, or by using a steam spray. Removal of the heating element and washing with a mild alkali solution, followed by thor ough rinsing with water, may be necessary in certain installations. Dirty fan blades may cause unbalance and vibration with consequent noise and damage to bearings. Hence, fan blades should be cleaned when necessary. Vibration may also be caused by improper fan position or looTsheesreet isscrceownss.iderable difference in the attention required by the various types of motors used with unit heaters. This is particularly true of lubri- Fig. 8. Connection of Horizontal Unit Heater to Hot Water System Fig. 9. Connection of Vertical Unit Heater to Hot Water System Unit Heaters and Unit Ventilators. ; ;6Q3 cation, the instructions for which must be carefully followed for trouble-free operation. Excessive lubrication may cause lubricant to reach and damage the rotor. An improper lubricant may cause failure of bearings. Instruc tions for care of the motor on any unit heater should therefore be obtained from the manufacturer and should be kept at the unit. Fan bearings and drives must be given the lubrication and other atten tion specified by the manufacturer. If the unit is direct-connected, the couplings should be inspected periodically for wear and alignment. V-belt drives should have all belts replaced with a matched set if one belt; shows wear. Periodical inspection of traps, check valves, and air valves, and the replacement of worn parts are important maintenance items. Strainers should be cleaned regularly. ' . .' When filters are' incorporated in the unit, they must be cleaned or re placed when dirty. For prevention of corrosion in unit heaters, see Chapter 43, Corrosion and Water Formed Deposits, Causes and Prevention, in this edition, and also Bulletin 12, The Care and Maintenance of Steam and Hot Water Unit Heaters, published by the Industrial Unit Heater Association. BOILER CAPACITY FOR STEAM UNIT HEATERS The capacity of the boiler should be based on the rated capacity of the unit heaters at the lowest entering air temperature and highest fan speed that will occur, plus an allowance for pipe line losses. It is unwise to in stall a single unit heater as the sole load on any boiler, particularly if the ' unit heater motor is started and stopped by thermostatic control. The . wide and sudden fluctuations of load that occur under such conditions would require closer attention to the boiler than: is usually possible in a small installation. Where oil or gas fuel is used in the boiler, it is possible by means of a pressure operated switch to control the boiler, in response to this rapid fluctuation. In most cases, and particularly where the boiler is coalfired, it is advisable to use two or more smaller units instead of one large unit heater. Steam pressures below 5 lb can be used with safety for recirculating unit heaters when their heating surfaces are designed for those pressures, and when proper provision is made for returning the condensate. If units receive air that may be at a temperature below freezing, a steam pressure of not less than 5 lb should be maintained in the heating element, or a corre sponding differential in pressure between the supply and return piping should be maintained by means of a vacuum. UNIT VENTILATORS A unit ventilator as defined earlier in this chapter, has the function of introducing outdoor air for ventilation and cooling in addition to heating. The typical unit is arranged to introduce outdoor air and recirculated air to the room in varying quantities and is equipped with a system of control that permits both the heating and cooling effect to be varied while the fans are operating continuously. Either steam or forced hot water may be employed as the heating medium. Unit ventilators are intended primarily for use in schools, meeting rooms, offices, or other applications where the density of occupancy indicates the need for ventilation. In normal opera tion, the discharge air temperature from a unit ventilator is varied in 604 CHAPTER 25 1956 Guide f;f *c - . . . rS accordance with the room demands. Where a heating effect is required, |J the air delivered is above room temperature. Where . the heat generated within-the room by occupants, sun, etc., is sufficient to cause overheating, the air delivery temperature must be below that of the rooms. It is cus tomary to equip unit ventilators with control devices that prevent the ' delivery of air at a temperature that will cause cold drafts. Unit venti lators may be of the heating element or damper controlled type, constructed 'f on the blow-through shown in Fig. 10, or draw-through principle as illus- 5 trated in Fig. 11. Ratings of Unit Ventilators 7 Unit ventilators are customarily cataloged with two ratings: the anetnometer rating and the standard air rating. The anemometer air rating is ' Unit Heaters and Unit Ventilators 605 b. Total EDR at different entering air temperatures. c. Air delivered by the unit in cubic feet per minute at the standard basis of rating with the fans operated at rated speed, with all air, being blown through the heating unit, and with the standard louver and grille on the outlet. The Standard Basis of Rating shall be as follows: . Dry saturated steam at a temperature at the unit corresponding to an absolute pressure of 16.7 psi (218.5 F). . . Entering air temperature of zero Fahrenheit degrees. c. Volume delivered in cubic feet per minute converted to standard air at 70 F. Rating Tables for unit ventilators shall contain the following data in addition to the standard rating, for entering air temperatures from -30 F to +60 F: a. Inlet temperature, Fahrenheit degrees. b. Final temperature, Fahrenheit degrees. c. Total EDR at the specified entering temperature. d. Surplus or heating EDR at the specified entering temperature. Fig. 10. Typical Blow-Through Type Unit Ventilator Showing One op Many Arrangements of Dampers and Heating.Elements peculiar to school house ventilation and was for many years the standard by which school officials checked and specified unit ventilator capacities, it originated as a convenient field measurement for checking air quantities, and is the basis of rating for ventilation requirements under many state and local building codes. The anemometer rating (air capacity) is obtained by averaging the air velocities obtained by an anemometer held over, equal subdivisions of the outlet grille at a distance of 2 in. from the grille, and. multiplying the average velocity by the gross area of the grille. (The average velocity is sometimes obtained by moving the anemometer over the outlet 2 in. from its face.) The anemometer rating is based on the . final temperature of the air leaving the grille while the unit is delivering outdoor air and room air in the proper proportion and the heating- element is supplied with steam or hot water as specified. The standard air rating is obtained in accordance with the A.S.H.V.E- Standard Code for Testing and Rating Steam Unit Ventilators.6 This code requires that the following rating information be supplied: Rating Factors to be Specified. The rating of the unit ventilator shall specify: a. Final temperature at different entering air temperatures. Fig. li. Typical Draw-Through Type Unit Ventilator Showing One op Many Arrangements op Dampers and Heating Elements , Surplus or Heating Equivalent Direct Radiation for the purposes of this code shall be construed to mean difference between the total EDR at a specified inlet tempera ture and the EDR required to heat the air from that temperature to 70 F. Table 2 shows the air handling capacities by the two methods of rating and the approximate room heating equivalent in EDR of an intermediate size of heating element. Heating elements are available for either a higher or lower capacity. Heating Capacity Requirements for Unit Ventilators Since a unit ventilator has the dual function of introducing outdoor air or ventilation and maintaining a specified room temperature, the heat re quired by the unit may be similarly divided as (1) heat required for ventilajum(//,) and (2) surplus heat (H,). The surplus heat is available for main taining room temperatures. If auxiliary radiation is installed, the surplus teat requirement may be reduced by a corresponding amount. The sum of and Ha is the total heat (Ht) to be supplied by the unit ventilator. I'h !' ! 1: !i ! 606' CHAPTER 25 1956 Guide These quantities of heat are related by the following equations: Hr = :0.24 W (t -to) ' ... Ht = 0.24 W it,-to) H. = Hi - Hr = 0.24 W (tf - t) . W = d 60 Q Hi = H. + 0.24 d 60 Q (i - to). . (1) (2) (3) (4) (5) ' d = density of air, pounds per cubic foot'(0.075 lb per cu ft for Standard Air by definition). . .. ............................ ... . 71, = surplus beat, Btu per hour. .. . . Hr = heat required to warm air for ventilation, Btu per hour. . . , . Hi = total heat requirements for both heating and ventilation, Btu per hour. Q = volume of air handled by the ventilating equipment, cubic feet per minute, t = temperature to be maintained in the room, Fahrenheit degrees. to = outside temperature, Fahrenheit degrees. <r = temperature of the air leaving the unit, Fahrenheit degrees. W = weight of air circulated, pounds per hour. :- i 0.24 = specific heat of air at constant pressure (approximate value). Table 2. Typical Capacities of Unit Ventilators fob an Entering Air TV,iwnmty k 'Ml I UT? AP Zrrg Cubic Feet op Aib peb Minute Anemometer Rating Standard Air Rating . ' 750 1000 1260 1560 Total Capacity tn<Squabe Feet, Equivalent Dj- . bect Rapiation Capacity Available fob Heating the Room, Squabs Feet Equivalent Direct Radiation ; 214 320 . 427 .534 56 ...... 84 112 . : 141 Final Aib Temperature F Deo Example 1: The heat loss of a certain room is 24,000 Btu per hour, and the venti lating requirements are 1000 cfm. If,the room temperature is to be 70 F and all air is taken-from the outside at zero, what will be the total heat demand on the unit if it is required to provide for both the heating and ventilating requirements (combined system)? : Solution: Since the surplus heat is available to replace the heat loss of the room, //, = 24,000 Btu per hour.. , : Substituting in Equation 5: * H, = 24,000 + 0.24 X 0.075 X 60 X 1000 (70 - 0) = 99,600 Btu. per hour t, --' ` 24,000 ' = -------------------- ----------------------------- + 70 = 92.2 F . . 0.24 X 0.075 X 60 X 1000 If in Example 1 a 1000 cfm (Standard Air) unit Were required,' but only 25 percent of the air introduced were outdoor air, the solution is: 77,= 24,000 + 0.24 X 0.075 X 60 X 0.25 X 1000 (70 - 0) = 42,900 u = 0.24 24,000 X 0.075 X 60 X + 70 1000 = 92.2 Unit Heaters and Unit Ventilators 607 : The;only difference from Example.1 is that, in the:latter case, the ventila tion load has been reduced. :. Applications of Unit Ventilators -. - - - Items to be considered in the application of unit ventilators are: (1) combination with other means of heating, (2) selection of unit ventilator size, (3) cycle of control, (4) location of units, and (5) method of venting and exhausting. . In a split system. the unit ventilator heat output is supplemented, by that of additional radiators or convectors, and consequently a correspond ing reduction- in required unit ventilator Heating capacity may be made. With the split system, temperature control equipment should operate to close the supply to auxiliary radiation or convectors as the first step'in the control cycle on a rising room temperature. . '; ; The combined system employs a unit ventilator with sufficient heating -capacity for both ventilation and normal heat losses. In such a, case no direct radiation is required. The cost of installation of a combined system is usually less than that of a split system. The unit ventilator is normally arranged to circulate outdoor air constantly or to circulate room air con stantly up to full capacity; or to circulate mixed and variable quantities of room air and outdoor air automatically, depending on the thermal require ment of the room. The minimum amount of outdoor air for ventilation purposes may be governed by state or local codes or may be calculated by the engineer to meet the ventilating air needs of the particular application. Selection of Unit Ventilator Size The primary consideration in the selection of the size of unit ventilator is the number of occupants in the space. Other factors to be considered are state and local code requirements, volume of the room, density of occu pancy, and the usage of the room. A safe rule for: determining air. capacity is to allow a total air quantity of 30 cfm per person, or six to nine room air changes through the unit, whichever is greater. With this quantity of air handled, it is possible to obtain satisfactory cooling in mild weather. Since cooling is an important function,1 the unit ventilator must be selected to supply adequate air quantities. ; After selecting the basic size of unit, the coil capacity to meet the heating requirement can be determined from the manufacturer's tables. Control of Unit Ventilators . Three cycles of control are available for use with unit ventilators. These cycles of control determine the sequence of operation of the dampers and heating element as described in Chapter 39, Automatic Controls. Location of Unit Ventilator . The location of the unit ventilator in a room is important. Wherever possible it should be placed against an outside wall and on the center line of the room. . It is difficult.to obtain proper air distribution if the unit is installed either on an inside wall or in a corner of the room. Standard units discharge the air stream upward, but for special cases units may be installed to discharge air horizontally. Units may be set against the wall or par- 608 CHAPTER 25 1956 Guide tially recessed into the wall' to save space without materially affecting the results. , Air Exhaust Vents and Flues The size and location of the air exhaust vent* outlet are important and in many cases, are regulated by laws for public buildings. Where no codes govern, the location and size of vents are left to the discretion of the en gineer. Best results have been obtained with a velocity through the vent open ings nearly equal to that at which the air is introduced into the room, thus maintaining a slight pressure in the room. Calculated velocities at the vent openings of from 600 to 800 fpm produce the best diffusion results from this system. Many states, however, have regulations that will not permit velocities as high as 800 fpm. If a vent opening at or near the floor is near a desk or place where a person is seated, a velocity, of 800 fpm in the vent opening will produce an objectionable draft. In such a case the veloc ity in the vent opening should not exceed 400 to 450 fpm, although duct velocities may be maintained at 600 to 800 fpm if codes permit. In school buildings provided with wardrobes or cloakrooms, the vents may be so located that the air passes through these spaces, ventilating them with air which otherwise would be passed to the outside without being used to the best advantage. Many state and local codes for ventilation of public buildings make this arrangement mandatory. WINDOW VENTILATORS A window ventilator consists of filter and switch controlled motordriven fans enclosed in a cabinet to be mounted on the window sill. Such units accomplish ventilation, air cleaning, and air circulation, but have no means of heating the air. The direction of air discharge is manually adjustable for seasonal operation. . REFERENCES 1 See National Association of Fan Manufacturers standard definitions in Chapter 33. * Standard Code for Testing and Rating Steam Unit Heaters--Adopted jointly by and theThe American Society of Heating and Ventilating Bngineebs Industrial Unit Heater Association, Second Edition January 1950 (IUHA Bulletin No8. S1t0a)n. dard Code for Testing and Rating Hot Water Unit H.eaters--Adopted jointly by and theThe American Society of Heating and Ventilating Engineers In dustrial Unit Heater Association, Second Edition April 1953 (IUHA Bulletin N. 11). 4 A.S.H.V.E. Research Report No. 958--Temperature Gradient Observations in a Large Heated Space, by G. L. Larson, D. W. Nelson and 0. C. Cromer (A.S.H.V.E. Transactions, Vol. 39, 1933, p. 243). A.S.H.V.E. Research Report No. 1011-- Tests of Three Heating Systems in an Industrial Type of Building, by G. L. Larson, D. W. Nelson and John James (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 185). 5 A.S.H.V.E. Standard Code for Testing and Rating Steam Unit Ventilators (A.S.H.V.E. Transactions, Vol. 38, 1932, p. 25) (Effective Jan. 1, 1934). A.S.H.V.E. Research Report No. 936--Investigation of Air Outlets in Class Room Ventilation, by G. L. Larson, D. W. Nelson and R. W. Kubasta (A.S.H.V.E. Transactions, Vol. 38, 1932, p. 463). A.S.H.V.E. Research Report No. 1017--Air Supply to Classrooms in Relation to Vent Flue Openings, by F. C. Houghten, Carl Gutberlet and M. F. Lichtenfels (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 279). CHAPTER 26 UNIT AIR CONDITIONERS AND UNIT AIR COOLERS Definitions, Classification of Unit Type Equipment, Component Parts of Unit Type Equipment, Sound Isolation, Modifications of Remote Units, Ratings of Unit Air Conditioners, Application of Unitary Equipment, Unit Air Coolers HIS chapter presents the physical characteristics of air cooling units Tand air conditioning units; a suggested procedure for selection of units; and some'of the factors involved in the application of unitary equipment. In general, factory produced unit equipment can be obtained to accomplish all of the functions possible from field assemblies, but the advantages of unit equipment are most apparent in small and moderate capacities. Above 12,000 cfm capacity, or approximately 40 tons of refrigeration capacity, handling and assembly costs generally favor the use of field assembled units. Multiple application of unitary equipment is frequently justified for large gross tonnage installations where zoning or a minimum amount of air distributing ducts is desirable. DEFINITIONS The term air conditioning unit has been loosely used as a name for all types of factory produced air handling, cooling, or heating units.' A joint committee1'2'8 on Rating Refrigerating Equipment has defined the various types of unitary equipment: ' 1. A Cooling Unit is a specific air treating combination consisting of means for air circulation and cooling within prescribed temperature limits.1 2. An Air Conditioning Unit is a specific air treating combination consisting of means for ventilation, air circulation, air cleaning, and heat transfer, with control means for maintaining temperature and humidity within prescribed limits.1 3. A Cooling Air Conditioning Unit is a specific air treating combination consist ing of means for ventilation, air circulation, air cleaning, and heat transfer, with control means for cooling and maintaining temperature and humidity within pre scribed limits.1 4. A Self-Contained Air Conditioning or Cooling Unit is one in which a condensing unit is combined in the same cabinet with the other functional elements. Self- contained air conditioning units are classified* according to the method of rejecting condenser heat (wateT cooled, air cooled, and evaporatively cooled), method of introducing ventilation air (no ventilation, ventilation by drawing air from outside, ventilation by exhausting room air to the outside, or ventilation by a combination of the last two methods), and method of discharging air to the room (free delivery or pressure type). , 5. A Free Delivery Type Unit takes in air and discharges it directly to the space to be treated without external elements which impose air resistance.1 6. A Pressure Type Unit is for use with one or more external elements which im pose air resistance.1 7. A ForcedrCireulation Air Cooler is a factory encased assembly of elements by which heat is transferred from air to refrigerants.8 CLASSIFICATION OF UNIT TYPE EQUIPMENT Field assembled apparatus as described in Chapter 30 can be designed in shape, size, and capacity for any application, with the refrigeration and beating system exactly balanced to a specific load condition. To obtain the economies of factory production, component assemblies are available in the size ranges of greatest usage. In addition to assemblies 610 CHAPTER 26 1956 Guide of high-side equipment in condensing units, the fan-coil units are factory made in various types as indicated by the preceding definitions. If the condensing unit and cooling and heating coil surfaces are care fully selected, and if proper consideration is given.to reduction of piping losses, the performance of the combined system will compare favorably with field assembled apparatus. A system in which the air handlingunit is separated from the condensing unit, is called a remote system. The conditioning unit is designated as a remote unit. The usual capacities of remote units usually range from 2 to 100 tons. The self-contained air conditioning or cooling units are widely used in capacities through 15 tons, and are available in larger sizes. Each model is designed for a specific cooling capacity and range of air delivery. Ex perience has demonstrated that well designed and properly applied equip ment of this type.produees excellent results in commercial comfort installa tions. In most designs of the larger self-contained units, the equipment can be adjusted to approximate the load calculations through a selection of the air quantity. An increase of air quantity in this type of equipment increases the sensible heat proportion, and a decrease of air quantity tends to provide a lower leaving dew point and a high proportion of moisture removal. However, the usual field practice is to adjust the fan speed for quietness and air distribution rather than for ratio of latent to sensible loads as indicated by a load estimate. , To meet the requirements of individual comfort in small rooms, and offices, self-contained units, called room coolers, find extensive and economi cal application. These units are usually restricted to summer and inter mediate season operation, and range from ^ to 1| tons of refrigeration ca pacity. - A special application of remote units is found in the unit air cooler which is used extensively in refrigeration work. Its primary function is to reduce temperatures in insulated and sealed storage spaces, and humidity control is a secondary consideration. Because of the small temperature differences between the coil and room temperatures, unit coolers handle three to five times as much air per ton as remote units used in air con . ditioning. ; The attic fan or exhaust fan is sometimes referred to as a cooling unit; but since it contains no element of heat transfer, it is treated in Chapter 33," Fans. COMPONENT PARTS OF UNIT TYPE EQUIPMENT The unitary equipment is designed for the air conditioning loads ^of most common occurrence. Highly special projects and projects of infre quent occurrence may require field-assembled equipment for best results. Field modifications generally prove inadvisable except by the most ex perienced engineering personnel. The basic design considerations of uni tary equipment are discussed in the next following paragraphs. Remole Units. Remote units can be obtained in two general classes, horizontal as shown in Fig. 1 and vertical as in Fig. 2. Their construction is essentially the same, except for the drain pan and filter locations. Casings. Casings are generally constructed of sheet metal with angle iron frames and with removable panels for access to coil connections, blower bearings, filters, and drain. Casings should be air tight. Panels should be tight fitting with cam or similar fastenings for easy openingPanel openings at coils for heavy units should be large enough to receive coils after the casing is suspended. Frames should be fitted with lugs Unit Air Conditioners and Unit Air Coolers 611 strong enough to suspend horizontal units. Non-metallic casings are of advantage in small remote units for reducing sound, particularly when propeller type fans are used. Insulation. Remote units are available with waterproof and verminproof, sound and heat barrier insulation on the inside of the casing. They are also available with flanges and flanged access doors to permit insulation after installation. Drain Pans. Because of the corrosive effect of mild picric, carbonic, and sulfurous acids absorbed by condensate, drain pans are usually made of 14 gage or heavier metal. They should be hot dipped galvanized after fabrication, or otherwise treated to resist corrosion. Some manu facturers extend the drain pan under the entire unit, but in any case it should extend far enough to catch any condensate carried over from the coils. The drain connection should be readily accessible for cleaning and, in air conditioning work, should be generously sized and trapped. Some municipal codes require a minimum size of li IPS. Blowers. The usual practice among manufacturers is to use blowers having external resistance capacity in keeping with the size and type of application for which the unit is designed. For.example, the larger selfcontained air conditioners have blower and motor arrangements for de livering the design air quantities against the larger external static pressures that are encountered when applying these units for use with supply and return-air duct systems. In a well designed unit, the relation of the blower and the coil surface is arranged, through testing, to assure adequate uni formity of air distribution over the heat transfer surface. Some of the smaller suspended type units. Fig. 3, use propeller fans with a trailing edge blade in order to obtain required pressure character istics with quiet operation. Since most of the motors driving these fans are direct-connected and use brushes for starting, adequate access should be provided for maintenance and inspection. Cooling Coils. The cooling and dehumidifying coils used in unit air conditioners are essentially the same as those used in central station units. A proper balance of coil capacity to the other components of the packaged air conditioner is an essential of good design and performance. Ample coil capacity is a requirement for good operation at light loads and low air quantities. Where multiple circuits are used in the larger coils, equal distribution of the cooling medium to the various circuits is vital in order to develop full capacity of the coil. The cooling coils also perform the function of dehumidification. To prevent carryover of condensate, some coil designs require eliminator sections even at the normal face velocities of 400 to 600 fpm. ` In addition to condensing the moisture out of the air, the design and arrangement of the cooling coil should provide for quick and effective drain ing of the condensate into the pan. Proper manufacturing-practices to provide for uniform fin spacing and laboratory development to determine coil-surface arrangements are among the requirements for good drainage from the cooling and dehumidifying coils of self-contained air conditioners. Healing Coils. Heating coils of unit air conditioners are usually conven tional blast coils, and can be obtained with or without non-freeze steam distribution features. They usually match the cooling coils in face area, are one or two rows deep depending on the heating requirements, where coils are selected for hot water, and have more than two rows of 612 CHAPTER 26 Fig. 5. Remote Floor Ttpe Room Unit Air Conditioner 1956 Guide Unit Air Conditioners and Unit Air Coolers 613 tubes, the air resistance and the space requirements of the cooling and heating coils should be carefully checked. Humidification. Spray-type humidifiers are usually used in remote systems, but in some cases pan-type humidifiers or steam humidifiers are also used. Some condensation on the inside of the unit casing may occur with possible water damage if the unit is located in a cold space without adequate insulation. Spray-type humidifiers should be located so that no carryover of moisture occurs. Filters. It is almost axiomatic that all units should have filters. Some small suspended units of 1 ton capacity or less, with low coil-face velocities and propeller fans, are equipped only with lint screens or operate without filters, but in them the coils must be periodically cleaned and there is con stant danger of clogging of the drain, with the possibility of water damage. Filters used are usually of the throw-away type, although cleanable filters are available for most of the larger units. Care should be taken to in sure adequate filter surface, since the cross-sectional area of the unit is seldom adequate for filter area. V-shaped or staggered filter arrangements are quite commonly used to increase filter area. Motors. In some units where the motor is mounted inside, adequate access for maintenance and. clearance for tightening belts are imperative. When motors are mounted in this manner, the heat equivalent of the motor input must be added to the heat load to be absorbed by the system, and this requires a lower exit air temperature at the coils. Usually; however, the motor is located outside of the casing where it is readily accessible for service. In this case, only the brake horsepower required by the fan is transformed into heat to be included in the load calculations. In either application, motors should be selected with adequate horse power to handle the design volume of air against the resistance of the system when the coils are wet, and then checked against the possible horsepower requirements for the increased volume of air obtained when the coils are dry. SOUND ISOLATION Both suspended and vertical floor-mounted units can transmit vibra tion through the supports. Wherever such transmission of sound might be objectionable, the supports should be isolated through rubber-in-shear or other sound deadeners. (For design of suitable sound deadeners see section Controlling Vibration from Machine Mountings in Chapter 41.). OTHER TYPES OF UNITS Features of various other'types of remote air conditioners are given in the following paragraphs. Spray-Type Unit Fig. 4 shows a spray-type unit used by designers who prefer air washing and coil wetting features. These units are equipped with a pump that sprays water or brine over the coils. Due to the direct mixing of the condensate and the spray, provision must be made for overflow in summer and replacement of water evaporated in winter. Dehumidifying Units In a further modification of spray-type units, absorbent brine solutions such as lithium chloride are used to remove moisture from the air. As 614 CHAPTER 26 1956 Guide explained in Chapter 38, the latent heat of the moisture removed is changed to sensible heat, so that coils must be used as after-coolers to obtain the right dry-bulb temperatures. Factory produced units are also available for use with solid adsorbents such as silica gel. -. ... . Another recent development as a manufactured item is the small re frigeration-type dehumidifying unit for the control of moisture in residential basements. ... Remote Room Units ' For individual rooms, with cooling load requirements of to tons, remote units are available in attractive casings for installation within the FiWg.a6t.ebS-eClof-oCleodntAaiibned CONDITIONEB Fioi' 7; Self-Contained Aib-Cooled Unit AlB CONDITIONER `_ room. A suspended type is shown in Fig. 3 and a floor type, such as is usually installed in place of ah existing radiator, is shown in Fig. 5. Furnished with chilled water from a central plant, these units offer a satisfactory method of conditioning existing offices, hotel,-and apartment rooms. These units may be obtained with filters and outside air con nections, but for most satisfactory application are used as supplements to central systems that supply properly conditioned and filtered air to the areas served. . Induction type units, using primary conditioned air under pressure to induce local circulation, are described in Chapter 30. ' Self-Contained Unite A typical large self-contained unit is shown in Fig. 6. It-is essentially a remote vertical-type conditioner mounted on top of a sound-insulated enclosure containing the condensing unit. Air distribution is obtained by means of grilles mounted in the discharge plenum, when the unit is located in the conditioned area. Duct distribution of conditioned air can be Unit Air Conditioners and Unit Air Coolers 615 obtained by removing the plenum, connecting directly to the blower dis charge, and safing the top of the unit. . '. The heat generated by the compression of refrigerant gases and- that given off by the electric motor are removed from the compressor compart ment in four ways: by the use of a water coil in the compressor compart ment; by utilizing the cold suction gases; by drawing part of the return air through the compressor compartment, and finally by circulating room air through the compressor compartment by means of a fan attached to the motor shaft. . Most self-contained conditioners are constructed with enough soundisolation material for installation directly in the conditioned spaces of the higher-sound-level commercial-type of applications. Special sound treat ment means are to be supplied as part of the installation when applying these conditioners to spaces having low sound-level requirements. Con ditioners may be installed outside the conditioned area and the connecting supply and return-air ducts can be acoustically treated as required for the specific installation. Self-Contained Room Cooling Units Small self-contained units can be obtained with water-cooled conden sers, but they are generally air cooled. ' The air-cooled types are small in capacity, ranging from ^ to 1-| hp. Their principal application is for conditioning such spaces as hotel rooms, offices and residential living quarters. A duct connection between the unit and an outside window or ventilated air shaft is required to permit disposal of the heat extracted from the conditioned area. The unit may stand in front of the window or be mounted on the window sill. Various styles and types of windows encountered tend to increase the difficulty of making the window connections. The evaporation of condensate: on the condenser coils, as a means of disposing of moisture, will tend to increase the condensing capacity and reduce the operating head pressure. Connections to an electrical outlet may be made through a Conventional cord and plug or a permanent electrical Connection, depending on local code rulings pertaining to the installation of small motors. The exterior finish of the unit in metal, wood or fabric is decorated to harmonize with office or bedroom furnishings. Some room air conditioners are being made for installation in special building openings provided in the walls as part of the initial construction. A unit of the air-cooled condenser type for floor mounting is shown in Fig. 7. Of the two fans shown, the lower one acts as condenser air fan, and in some units this fan is arranged with slingers for discharging con densate on the condenser coil, while the upper fan discharges air into the conditioned area. A feature of most room air conditioners is that the condensate from the cooling coil is sprayed over the condenser surface and vaporized, thus eliminating the need for drain connections. A simple dampering arrangement is generally provided for exhausting some air from the room, in addition to introducing outside air and recirculating required amounts of air. It is possible to remove the equipment for winter storage or utilize the ventilating features for winter operation. . Controls for Room Cooling Units .. Control devices provided for self-contained cooling units generally, will include all necessary, means for automatic operation. Provision is also made for adding auxiliary external controls, when desired. Remote 616 CHAPTER 26 1956 Guide units are not generally equipped with controls. Control systems for remote units, and auxiliary controls for self-contained .units, are covered in the general treatment of Controls in Chapter 39. RATINGS OF UNIT AIR CONDITIONERS Two standards have been used for rating and testing of unit air con ditioners: (1) Standard Method of Rating and Testing Air Conditioning Equipment,1 covering all types of air conditioning units except the selfcontained type and (2) Standard Method of Rating and Testing SelfContained Air Conditioning Units for Comfort Cooling2 covering the selfcontained type. (ASRE Standard Methods of Rating and Testing Air Conditioners, ASRE Standard 16-53, covers rating and testing of all types which operate non-frosting when cooling and dehumidifying at standard rating conditions.) The standard rating of a self-contained unit for the conditions specified in Table 1, includes all items which apply to-the function of a unit as: (1) name of unit, (2) functions which unit performs, (3) data on cooling, (4) data on heating, (5) data on air flow, and (6) data on humidification. The standard rating conditions for unit air conditioners, other than the self-contained type, are identical with those in Table 1, except that entering wet-bulb temperature for cooling is expressed as 50 percent relative humidity (66.7 F wet-bulb) instead of 67 F wet-bulb temperature. In addition, the saturated suction refrigerant temperature for comfort cooling is specified at 40 F. This condition is omitted from Table 1 for self-contained units because it is not separately controlable in the testing of a unit that includes the evaporator and condensing unit. - APPLICATION OF UNITARY EQUIPMENT One of the chief advantages resulting from use of factory produced units is the saving in installation and field assembly labor, a factor that should always be kept in mind when selecting a location for these units. Because of their compactness, the tendency exists to put them in closets, storage rooms, and other inaccessible places, where installation is so difficult that much of this cost advantage is lost. Access panels are provided on units for the proper servicing and main tenance of the equipment. Adequate outside clearance at these panels is essential. Wherever there is danger of freezing of coils or clogging with dirt, sufficient clearance should be available for replacing them without removing parts of the building. The outstanding source of difficulties in unitary systems is usually dirty filters. The characteristics of the light weight fans used are such that air volume drops off rapidly with increase in static resistance. Since changing of filters is an unpleasant duty likely to be neglected unless it can be done easily, the operator should be at the same level as the filters, rather than under them, when they are being removed. Variable-pitch motor pulleys are usually provided for adjustment of the air quantity. The fans and motors of most conditioners are selected for the usual range of external resistances commonly used with the specific size of conditioner. The larger conditioners are capable of serving larger areas and therefore require fan and motor capacity for the greater external duct resistances that may be imposed on such conditioners. Where varying sizes of coils are used within the same casing, it is very important that coil safing be carefully installed to prevent bypassing of unconditioned air. If coils are not equipped with individual casings, Unit Air Conditioners and Unit Air Coolers 617 i/qnditioninq Units Functions All Cooling Tyfes of Units Rating Condition Item Description All Barometric Pressure Value 29.92 in. Hg. Water-Cooled, Air - Cooled; and Eva poratively Cooled Con densers Unit Ambient and Air Entering Room--Air Inlet (1) Dry-Bulb (2) Wet-Bulb Ventilation Air 80 F 67 F See Note Water-Cooled Condensers Water Temperature Entering Unit 75 F Air - Cooled] ^ and Evapoj atively , Cooled Con-j densers Water Temperature Leaving Unit s Air Entering Outside Air Inlet (1) Dry-Bulb (2) Wet-Bulb 95 F 95 F 75 F Heating res Pro-] Unit Ambient and Total Air . Entering Unit . 70 F video with Heating Function Heating Medium, Pressure or Temperature (1) Dry Saturated Steam (2) Water In (3) Water Out . 16.7 lb per sq in. abs 180 F 160 F Humidifying All T, Provide with Hu midifying Function Unit Ambient " Total Air Entering Unit (1) Dry-Bulb (2) Wet-Biilb 70 F 70 F 53 F Air Circula tion All Filters New and ;, . - -__________Clean I Nate: Rating shall bn based on both ventilation and recirculated room air entering at 4W) F dry-bulb and 67 F wet-bulb temperature. (The Note as given in the code has been condensed in order to remove material not pertinent to this chapter). * * ______ _ additional safing may be required on top to prevent short circuiting air down through the upper edges of the fins. In this same category is the need for careful installation of the various sections of sectionalized units, using a sealing compound if necessary to prevent air leakage into the fan section of the unit. Since the drain connection is usually made on the exit side of the coil, it is important that the drain line be properly sealed. This seal should I>e at least twice as deep as the suction on the fan in inches of water, to prevent gurgling sounds, and to insure a positive seal against infiltration of odors and moisture laden air. Drain pans should not be used to sup port the coils, unless they are designed to hold this weight without sagging. As the movement of air draws the condensate or excess humidification water toward the fan, drain connections are usually placed on the exit 618 CHAPTER 26 1956 Guide side of the.coil. The advantages of quick drainage are lost if improperly supported coils distort drain pans and cause water to, accumulate in the center or back of the pan. When the fans of vertical units are stopped, condensate that has been held up in the coils by fan suction, drops into the drain pan and splashes against the casing. If water damage is to be avoided, flashings should be provided to prevent this water from running out of the unit :at the seams. When locating unitary equipment, floor and beam loadings should be carefully checked. Suspended horizontal units can add,50 to 100 lb per square foot to the loading on the floor above. Should this floor be already heavily loaded, or be a roof structure designed for a 40 lb per square foot 'snow load, excess beam deflection may occur and cause cracking of plaster or''concrete fire-proofing. A small'fire, normally of little consequence, may cause a rupture of a heavily loaded structure and permit the equip ment to drop with extensive property damage. Self-contained units should be carefully installed since their weights run as high as 200 lb per square foot. When they are installed in street floor shops, the extra precaution of placing a column beneath them in the basement is an inex pensive method of. reducing vibration, as. well as providing insurance against overloaded floor beams. .. . i The services required for operation of unitary. equipment should conform to the many restrictive, but necessary, local municipal codes. Existing buildings seldom are wired adequately for the electrical load imposed by the starting of an air conditioning compressor on any branch circuit;, Even the smallest room cooler can draw enough current to reduce the voltage of a lighting circuit to the point where it is: visibly apparent. This voltage drbp may even affect the life of the unit due to the relatively slow, starting. The cost of a separate electrical circuit of adequate capacity from the main panel is more than justified:; it is a neces sary expense in the majority of installations. ` ; . A water supply of adequate capacity and pressure is: necessary to prevent overloading of electrical equipment by highrhead pressures. The average city water supply pressure is adequate for installations up. to the third floor. Since most water cooled units require about 20 lb pressure, including control valve losses, it is important that any units served`by gravity from roof tanks be checked carefully if located less than 40 ft below the tank. Drain connections from condensers should flow to an open and properly trapped sink as required by most city codes. This prevents back pres sures on the city water system in the event of condenser failure. .Aqheck valve should also be installed in the water supply as a further precaution against contamination. .' . When installing small remote or self-contained units with outside-air connections in buildings more than 6 stories high, the effect of wintertime stack action in elevator and stairwells requires special attention. This stack action is the cause of negative pressures on the lower floors, tending to draw cold air through the units, and positive pressures on the upper floors preventing adequate ventilation and disrupting air distribution. It can also cause annoying whistling at door openings and lead to serious complaints in,hotels and offices. Wherever the removal of such units is impracticable, it is important that carefully, fitted, felt-edged dampers be installed in the outside air intakes with adequate locking devices. One further consideration when installing self-contained units in con Unit Air Conditioners and Unit Air Coolers 619 ditioned areas is that any maintenance or repairs to be required in future years must be carried on in occupied space. UNIT AIR COOLERS Unit air coolers are intended principally for product cooling, but are often used for cooling spaces to low temperatures. They differ from normal air conditioning units only in features required to produce lower temperatures. In-using such units, dry-bulb temperatures should be considered first, after which room moisture conditions and air distribution should be considered, depending on the product being cooled or stored. In recent years the unit cooler has almost entirely supplanted the gravity type prime-surface and finned-tube coil. It provides more positive con trol of air and better-air distribution, is more efficient in performance, re quires less space, is easier and less expensive to install, and is often less expensive in first cost. Early applications of unit coolers were limited to cold storage warehouses. In recent years they have been widely used in retail and wholesale markets for meat, fruit, and vegetables. Products to be cooled or stores may be divided into four general classifi cations based on their sensitiveness to moisture loss.4,6 Selection of the proper temperature differential between storage-room air temperature and evaporating refrigerant temperature will produce adequate moisture con trol for all practical purposes. The differentials required for gravity cir culation and for forced air circulation are different, the latter requiring closer differentials. The four classes and differentials which have been successfully used are as follows: Class 1.--Products requiring high room-moisture content, which are highly sus ceptible to moisture loss and are being stored for extended periods, for example, eggs. Gravity Circulation Forced Air Circulation 18 F or less. 6 to 9 F. Class g--Products similar to Class 1 but which are being stored only for a limited time as in retail stores where the turn-over is usually 3 days or less, for example, cut meats; Gravity Circulation Forced Air Circulation 18 to 22 F. 9 to 12 F. Class S--Products requiring moderate room moisture content and which are moderately susceptible to moisture loss, for example, carcass meats and some fruits. Gravity Circulation Forced Air Circulation ' 21 to 27 F. 12 to 20 F. Class 4--Products from which there is a very low moisture'loss or none at all and where room moisture content is not important, for example, canned goods, furs, woolens, bottled goods, dried fruits, foods packaged in good moisture vapor barrier packages. Gravity Circulation Forced Air Circulation 25 F and up. 20 F and up. When using class 4 application, with finned evaporators and automatic defrosting at each cycle of the condensing unit, it is important to avoid using too wide dif ferentials with very low refrigerant temperatures. In many applications, prime surfaced evaporators prove unsuitable for this type of defrosting and will require some positive method of defrosting. Unit coolers can perform satisfactorily in installations requiring accurate control of relative humidity, air motion, and dry-bulb temperature, and 620 CHAPTER 26 1956 Guide thereby prevent excessive weight loss, mold and slime growth, and moisture absorption by hygroscopic materials such as dried fruits. Unit coolers, especially in the smaller sizes, are very similar in appear ance to unit heaters. Copper, aluminum, or steel prime or finned-surface tubes are used. Propeller or centrifugal fans either blow or draw room air over the tubes. The fan and coil are generally enclosed in a casing pro vided with a drip pan. The motor horsepower requirements are a function of resistance due to coil construction and arrangement, and air volume re quired. Fin spacing is based principally on operating temperatures. For operation below 35 F, fin spacing is preferably not more than four to the inch. Above 35 F it may run as high as 8 fins per in., depending on room temperature and refrigerant temperature used. Both direct expansion refrigerants and brine are used successfully as cooling mediums. Unit coolers may be arranged for either free or duct delivery. Face velocities vary, depending principally upon the intended application of the unit. In the larger sizes particularly, speed adjustment of the fan is generally provided to permit variation of the air delivery. While unit coolers are usually installed in the storage space, remote installation com bined with appropriate duct work may be required by space or other con siderations. Units are available for floor, wall, or ceiling mounting, thus providing an upward, downward, or horizontal discharge. Power, refriger ant, and drip pan connections are required, plus additional connections for defrosting, if necessary. For storage temperatures below 35 F, some positive means of defrosting is mandatory. At 35 F or higher storage temperatures, cycling of the con densing unit with low pressure control with proper settings will provide automatic defrosting each cycle. At above 35 F design refrigerant tem peratures, frost and ice formation will not normally occur. . Various methods of defrosting are used.' In one method, hot gas is supplied to the interior of the tubes uniformly throughout the coil. The entire refrigerant circuit is thus contacted to obtain complete delrosting of all frosted surfaces. Electric defrosting generally involves the incor poration of heating elements within the construction of the coil, or the use of strip heaters in a dampered closed-air circuit. Warm water may be sprayed over the coil surface for defrosting. With storage temperatures above 32 F, defrosting may be accomplished by shutting down the refrigera tion system and circulating the room air over the coil. In every case, de frosting requires a cessation of refrigeration on the unit being defrosted. Where continuous operation of the system is desired, a brine spray over the coil may be used unless it might damage the product in storage, or cause too much corrosion of room fittings, ducts, etc. Ratings As various means of expressing unit cooler capacity are utilized in the industry, different manufacturers suggest different methods of selection. The engineer should be aware of the conditions and factors which affect rating, selection, and performance of a cooler. These items are discussed in following paragraphs. The refrigerating capacity of the unit may be either gross or net, the latter being less than the gross by an amount equal to the heat equivalent of the input to the unit cooler motor. In either case, the capacity should be given for a particular air volume. Air throw data are also valuable. Dry or flooded rating conditions should be stated, as well as temperature level. The temperature level determines whether the coil surface is wetted Unit Air Conditioners and Unit Air Coolers 621 or frosted, and it will also establish the refrigerant side pressure drop for any given load applied to a specific unit cooler. The refrigerant-side pres sure drop increases as the evaporating temperature decreases, and thus temperature level exercises a significant effect on the average coil-surface temperature and the consequent condensing unit selection. Coil capacity rating is usually expressed as total heat absorbed with no distinction between sensible and latent heat. The rating expresses the capacity in terms of Btu per (hour) (Fahrenheit degree temperature dif ferential between the refrigerant and the air). The term basic rating may be used. This is the Btu per hour absorbed with one Fahrenheit degree differential between room air and evaporator refrigerant temperature. When the total load has been obtained from the load calculations, a tem perature differential between the air and the refrigerant is selected. It is based on product classification previously discussed. The extent of de- humidification will be a function of this temperature differential. Moisture conditions in the storage space are dependent upon the correct selection of this temperature differential. It offers a quick and sufficiently accurate practical basis for coil selection. Where close control of relative humidity is desired, heating coils or electric heaters for re-heat may have to be added. The use of air conditioning psychrometric techniques is only required for accurate humidity control. Cooling equipment is usually rated on the basis of the overall room-torefrigerant temperature differential instead of using the intermediate aver age coil-surface temperature. If the tentatively selected unit cooler does not possess the proper capacity, it may be possible to adjust the fan speed to a new air volume. At the new air volume and the new overall dif ferential, the cooler may be able to deliver the necessary cooling capacity. If not, the procedure must be repeated with another size of unit cooler, the final selection being based on the proper balance between unit cooler and the condensing unit to maintain the Btu per hour heat removal and tem perature difference at design room temperature desired.5 Procedures for rating and testing room coolers are given in an ASRE Standard3 which establishes four groups of conditions (numbered I to IV) under which units may be rated. Many manufacturers establish and publish their ratings in accordance with this standard in which forced circulation air coolers are classified according to air side surface conditions as (1) dry'coil, (2) sprayed coil, and (3) spray-no coil; or according to type of air delivery to room as (1) free delivery fan, or (2) pressure fan. Natural convection air coolers are classified according to type as (1) external baffle, (2) built-in-baffle, and (3) without baffle. Arrangement and Operation The refrigerant is usually supplied to the evaporator through a thermo static expansion valve, thus obtaining dry expansion in the evaporator. In other designs, float-valve feeding is used as a means of metering the re frigerant into the evaporator. The refrigerant circuit in the coil may be . of the continuous-flow type from inlet to outlet, or it may have means for internal recirculation of the refrigerant. The coils having the dry-expansion or continuous flow from inkl-to-oullet circuits may be of the upward feed or the downward feed arrangements. Upward flow is generally regarded as Pricing more refrigerant holding capacity and more effective use of the surface. However, with some refrigerants and in some systems, the downward-feed system has been found to produce better oil-return charac teristics. Many direct-expansion installations use liquid-vapor heat ex- 622 CHAPTER 26 1956 Guide changers to increase the coil utilization without undue risk of returning liquid refrigerant to the compressor. .. Where two or more evaporator cods are to be attached to a single con densing unit, and different evaporator temperatures are desired, a back pressure valve may be installed to limit the minimum evaporating tempera ture of the warmer coils. This valve also finds application where fluctua tion in the evaporator temperature prevents accurate control of air tem perature and humidity. . Except in product precooling, the objective of air distribution is to ab sorb the heat load as it comes into the room while maintaining a desirable degree of ventilation-air movement through hygroscopic cargos that are not vapor-barrier encased. In cold storage practice, this generally requires the securing of as uniform an air distribution as possible to every part of the product zone, with employment of diffusion of air over the product and avoiding direct blasts against the product. These requirements must be recognized when selecting the unit coolers and their outlets and when selecting the locations for the unit coolers. It is important to note that the quantity of air in motion in the refrigerated space is not only that passing through the coils. A quantity of air many times in excess of the air handled by the units is always set in motion by the induction effect of the moving cooled air. Therefore, in evaluating the velocity for any given area, the total air set in motion must be considered. It is a function of the type of outlet, the discharge air velocity, and the location of the unit relative to restrictive walls and product. Unit location is also important from the standpoint of occupant com fort, low-velocity outlets being preferred for floor type units. High-velo city outlets are acceptable in fur storage vaults, ice cream hardening rooms and other spaces where air motion is not an important factor. In general, unit air coolers should not be suspended in front of door openings, or close to them where moist warm air will be drawn directly into the unit each time the door is opened, thereby causing excessive frosting and loss of capacity. Better performance will be obtained by placing the unit air cooler in a location such that the air will be discharged toward the door. If the shape of the space is such that this location would result in excessive air velocity over the product, then the location of the unit air cooler should be changed so that the air is discharged parallel to the wall in which the door is located. REFERENCES 1 Prepared by a Joint Committee of the American Society of Refrigerating Engi neers, American Society of Heating and Ventilating Engineers, Refrigerating Machinery Association, National Electrical Manufacturers' Association, and Air Conditioning Manufacturers' Association (A.S.R.E. Circular No. 13-42).* * Standard Method of Rating and Testing Self-Contained Air Conditioning Units for Comfort Cooling prepared by a Joint Committee of the American Society of Re frigerating Engineers, American Society of Heating and Ventilating Engineers, Refrigerating Machinery Association, National Electrical Manufacturers' Association, and Air Conditioning Manufacturers' Association (A.S.R.E. Circular No. 16).* * Proposed A.S.R.E. Standard Methods of Rating and Testing Forced-CirculatioD and Natural Convection Air Coolers for Refrigeration (A.S.R.E. Circular No. 25-44). 4 Air Conditioning Refrigerating Data Book--Applications, Chapter 34 (American Society of Refrigerating Engineers). 5 Reference 4, Chapter 33, Fig. 20 and text. * ASHE has combined CirtttJan No. 13-42 and No. 16 in ASRB Standard No. 16-63, Methods ol Rating and Testing Air Conditioners. CHAPTER 27 PIPE, FITTINGS, WELDING Pipe Materials, Types-of Pipe, Commercial Pipe Dimensions, Threading Practice, Pipe Fittings, Flange Facings and Gaskets, Valves, Welding, Expansion and Flexibility, Hangers and Supports . IMPORTANT considerations in the selection and installation of pipe and fittings for heating, ventilating, and air conditioning are dealt with in this, chapter. .' PIPE MATERIALS 5 Use of corrosion-resistant materials for pipe, including special alloy steels, copper, and red brass, has increased considerably during the past few years. The following brief discussion indicates the variety of pipe materials and the types of pipe available. ., Wrought-Sleel Pipe.- Because of its lower cost, the great bulk of wrought pipe used for heating and ventilating work at the present time is of wrought steeL The material used for steel pipe is a mild steel made by the acidbessemer, the open-hearth, or the electric-furnace process. Ordinary wrought-steel pipe is made either by shaping sheets of metal into cylindri cal form and welding the edges together, or by forming or drawing from a solid billet. The former is known as welded pipe, the latter as seamless pipe. Many types of welded pipe are available, although the smaller sizes most frequently used in heating and ventilating work are made by the lap-weld, resistance-weld, or butt-weld process. While the lap-weld and resistance-weld processes produce a better weld than the butt type, lapweld and resistance-weld pipe are seldom manufactured in nominal pipe sizes less than 2 in. Seamless pipe can be obtained in the small sizes at a somewhat higher cost, and is listed as pressure tubing below 2 in. ' Seamless steel pipe is frequently used for high pressure work or where pipe is desired for close coiling, cold bending, or other severe forming op erations. Its advantages are its greater strength which permits use of a thinner wall and, in the small sizes, its freedom from the occasional tendency of welded pipe to split at the weld when bent. - . Wrought-Iron Pipe. Wrought-iron pipe may be identified by the spiral line marked into each length, either knurled into the metal or painted on it in red or other bright color. Otherwise, there is little difference in the Appearance of wrought iron and steel pipe, although microscopic examina tion of polished and etched specimens will readily disclose different grain structures. Casl-Ferrcrus Pipe. There are now available several types of cast-ferrous metal pipe made of a good grade of cast-iron with or without additions of nickel, chromium, or other alloy. This pipe is available in sizes from 1J^ 623 It 624 [ ( li i lj li i; 1 |j \\ m !i; !I>S:! 'll !|l 'l \n -p 1 iH CHAPTER 27 1956 Guide Pipe, Fittings, Welding ' 625 Table 1. Dimensions and Pbopebties op Steel Pipe (Concluded) Nom inal1 Size ASTM* Sche dule Dlameteb O. D. L D. In. In. &o . 5* 3a <g3 SUKTACE Abea Sq Ft/Lin Ft O. D. I. D. Section Abea Sq In. O. D. I. D. Abea or Metal Sq In Vol ume Gal/ Lin Ft Weight* (plain end) Lbs^Lin WoHKIKQ PbesBUBE* PflIA 20 20 fa) 20.000 19.250 0.375 5.23 4.51 314. 291. 23.2 15.2 78.6 30 fa) 20.000 19.000 0.500 5.23 4.97 314. 284. 30.6 14.7 104.2 24 20 24.000 23.250 0.375. 6.29 6.08 452. 426. 26.8 22.1 94.6 fa) 24.000 23.000 0.500 6.29 6.03 452. 415. 36.9 21.5 125.5 319 (c) 454 (c) 265 (c) 378 <c) * 3H Double extra strong is no longer considered in ASTM. specification but some pipe of this size is still manufactured. . i The sizes for wrought iron are approximately the same except wall thickness is slightly heavier. See ASTM A-72. . * American Society for Testing Materials Schedule. The numbers 30,40, etc., refer to the ASTM Schedule; the letter (s) refers to the former designation Standard Weight-, the letter (x) refers to the former designation Extra Strong; the letters XX refer to the former designation Double Extra Strong. 1 Weight per foot is based on plain end pipe. Threaded and coupled (T and C) pipe is slightly heavier. 4 Working pressure for welded joints--see formula in Table 3. (a) Working pressure based on an allowable fiber stress of 6225 psi (for. 250 F). (b). Working pressure based on an allowable fiber stress of 8400 psi (for 250 F). - (c) Working pressure based on an allowable fiber stress of 12000 psi (for 250 F). Note: Standard-weight pipe is generally furnished with threaded ends in random lengths of 16 to 22 ft., although when ordered with plain ends, 5 percent may be in lengths of 12 to 16 ft. Five percent of the total number of lengths ordered may be jointers which are two pieces coupled together, Extra-Strong pipe is generally furnished with plain ends in random lengths of 12 to 22 ft., although 5 percent may be in lengths of 6 to 12 ft. in. to 6 in., and in standard lengths of 5 or 6 ft, with external and internal diameters closely approximating those of extra strong wrought pipe. Castferrous pipe may be obtained coupled, beveled for welding, or with ends plain or grooved for the several types of couplings. It is easily cut and threaded as well as welded. The fact that it is readily welded enables the manufacturers to supply the pipe in any lengths practicable for hand ling. Allay Metal Pipe. Both iron and steel pipe are available in the alloy class. In the case of iron pipe when copper and molybdenum are added, the ma terial is known as alloy wrought-iron. By common custom steel is considered to be an alloy when the maximum range of alloying elements exceed certain limits such as 1.65 percent man ganese, 0.60 silicon, or 0.60 copper. Also, a steel is an'alloy if any of the following elements are specified in minimal quantities or within limits: Al, B, Cr (up to 3.99), Co, Cb, Mo, Ni, Ti, W, V, Zr, or any other element added to obtain a certain alloying effect. Small quantities of certain elements are present in alloy steels and are considered as incidental and may be present to the following maximum amounts: copper--0.35 percent, nickel--0.25 percent, chromium--0.20 percent, and molybdenum--0.06 percent. Commercially, steel is considered stainless when chromium exceeds 3.99 percent regardless of the inclusion of other alloying elements. With tvblnQ, however, an alloy becomes stainless when it contains a minimum of 10.5 percent chromium. The alloy and stainless steels are used for high temperature piping and for highly corrosive fluids and gases. Copper Pipe and Fittings. Owing to inherent resistance to corrosion, 626 CHAPTER 27 1956Guide Table 2: Dimensions and Properties op Copper Tube Nom:INAL rrPE Size Diameter 0. D.l I. D. In. In. Subface Wall Area Sq Thick-. Ft/Lin Ft In. 0. D. I. D. Section'Area Sq In. O. D. I. D. &REA OF Metal Sq In 0.035 1.0982 C .0798 0.110 0.0730 L 6.375 0.315 0.030 1.0982 ( .0825 0.110 0.0779 0.049 0.131 0.105 0.196 0.127 L 0.500 0.430 0.035 0.131 0.113 0.196 0.145 L 0.527 0.625 0.545 0.049 0.040 0.164 0.138 0.164 0.143 0.306 0.308 0.218 0.233 -H L 0.750 0.652 0.049 0.193 0.171 0.441 0.750 0.666 0.042 0.193 0.174 0.441 0.334 0.348 0.745 0.065 0.229 0.195 0.601 0.436 L 0.875 0.785 0.045 0.229 0.206 0.601 0.480 1.125 0.995 0.065 0.295 0.260 0.994 0.778 L 1.125 1.025 0.050 0.295 0.268 0.994 0.852 "lH K 1.375 1.245 1.375 1.291 DWV 1.375 1.295 0.065 0.055 0.042 0.040 0.360 0.326 0.360 0.331 0.360 0.338 0.360 0.339 1.48 1.48 1.48 1.48 1.22 1.26 1.31 1.32 1.625 1.481 1 625 1.505 1.527 DWV 1.625 1.541 0.072 0.060 0.049 0.042 0.425 0.388 0.425 0.394 0.425 0.400 0.425 0.403 2.07 2.07 2.07 2.07 1.72 1.78 1.83 1.86 2 K 2.125 1.959 0.083 0.556 0.513 3.56 2.125 1.985 0.070 0.556 0.520 3.56 M 2.125 2.009 DWV 2.125 2.041 0.058 0.042 0.556 0.526 3.56 0.556 0.534 .3.56 3.01 3.10 3.17 3.27 2M L 2.625 2.435 0.095 0.687 0.638 5.41 2.625 2.465 0.080 0.687 0.645 5.41 M 2.625 2.495 0.065 0.687 0.653 5.41 4.66 4.77 4.89 K 3.125 2.907 L 3.125 2.945 M 3.125 2.981 DWV 3.125 3.035 0.109 0.090 0.072 0.045 0.818, 0.761 0.818 0.771 0.818 0.78C 0.818 0.796 7.67 7.67 7.67 7.67 6.64 6.81 6.98 7.23 3H K 3:625 3.385 0.120 0.949 0.886 10.3 3.625 3.425 0.100 0.94( 0:891 10.3 M .3.625 3.459 0.083 0.949 0.906 10.3 9.00 9.21 9.40 -4 K 4.125 3.857 L 4.125 3.905 M 4.125 3.938 DWV 4.125 4.009 0.134 0.110 0.095 0.058 1.08 1.08 1.08 1.08 1.01 1.02 1.03 1.05 13.3 13.3 13.3 13.3 .11.7 . 12.0 12.2 12.6 5 K L 5.125 4.805 0.160 1.34 1.26 20.7 5.125 4.875 0.125 1.34 1.28 20.7 18.1 18.7 M 5.125 4.907 0.109 1.34 1.29 20.7 18.9 6 K L M 6.125 5.74 0.192 1.60 1.50 29.4 6.125 5.84* 0.140 1.60 1.53 29.4 6.125 5.88 0.122 1.60 1.54 29.4 25.9 26.8 27.2 DWV 6.12* 5.95 0.083 1.60 1.56 29.4 27.9 8 K 8.125 7.58.1 0.271 2.13 1.99 51.8 L 8.12* 7.72.S 0.200 2.13 2.02 51.8 45.2 46.9 M 8.12* 7.78.5 0.170 2.13 2.04 SI.8 47.6 10 K L M 10.12.> 9.44 3 10.12.> 9.62 ) 10.12. 9.70 0.338 0.250 0.212 2.65 2.65 2.65 2.47 2.52 2.54 80.5 80.5 80.5 70.1 72.8 73.9 12 K 12.12.> 11.31 1 0.405 3.17 2.96 115. L 12.12.> 11.56.5 0.280 3.17 3.03 115. M 12.12.> 11.61 7 0.254 3.17 3.04 115. 101. 105. 106. 0.0374 0.0324 0.0695 0.0512 0.0887 0.0735 0.108 0.0934 0.165 0.117 0.216 0.169 0.268 0.228 0.176 0.163 0.351 0.295 0.243 0.205 0.532 0.452 0.377 0.288 0.755 0.640 0.523 1.03 0.858 0.691 0.435 1.32 ' 1.11 0.924 1.68 1.39 1.20 0.67 2.50 1.96 1.72 3.50 2.63 2.30 1.58 6.69 4.98 4.25 10.4 6.60 14.9 10.4 9.47 Volume 3al/Lin . Ft 0.00379 0.00404 0.00660 0.00753 0.0113 0.0121 0:0174 0.0181 0.0227 0.0250 0.0405 0.0442 0.0634 0.0655 0.0681 0 0684 0-0894 0-0925 0.0950 0.0969 0.157 0161 0.164 0.242 0.247 0.254 0.345 0.354 0.362 0.376 0.468 0.489 0.607 0.634 0.656 0.940 1.35 1.42 1.55 2.34 3.65 5.24. 5-45 5.50 Vehght* Lbs/Lin Ft Vorkinq Pres sure* psia 0.145 918 0.269 988 0.344 . :779 0.418 Q.641 . 0.455 ' 0.839 643 ;S47 747 574 - 1.04 0.884 466 387 1.36 1.14 u.940 2.06 . 421 359 . 376 2.93 352 - 4.00. 3.33 - 343 . 5.12 324 6.51 . *>.38 4.66 9-67 135 217 *: ,v 307 13.9 8.92 25.9 308 190 4P.3 . 332 57.8 40.4 334 204 * Weight per foot is based on tube without couplings. . ' b Working pressure is based on the American Standard Code for Pressure Piping, published by the A* .. revised November, 1952 for plain end tubing (sweat joints). 2dm where P -- allowable pressure, pounds per square inch. . P " D --0.8/m a -- 6000 psi allowable fiber stress, pounds per square me ' lm ~ minimum wall thickness, inches. > D = maximum O. D.', inches. ' Types K and L furnished in both bard and soft temper*. Type M in hard only. Standard straight lengths are 20 ft. Standard coils (H to Hi inch) are 60 ft. Pipe, Fittings, Welding 627 copper and red brass pipe have always been used in heating, ventilating, and water supply installations, but the cost with standard dimensions for threaded connections has been high: The introduction of fittings which permit erection by soldering or sweating, allows the use of tube with thinner walls than would be possible with threaded connections, thereby reducing the cost of installations. COMMERCIAL PIPE DIMENSIONS Commercial pipe dimensions are covered in the following specifications of the American Society for Testing Materials: (1) steel--ASTM A-120 and A-53, (2) wrought-iron--ASTM A-72, and (3) copper tube--ASTM A-88. Tables 1 and 2 are based on these specifications. In addition to the specifications for these three materials, there are Table 3. Table op Availability fob Steel Pipe Material SpEarication- Available Sizes (Inclusive) Inches Diam. Allowable Flbeh Stress S* psi Butt-weld _ Lap-weld Electric-resistance Seamless A-120 A-53 A-120 A-53 A-53 Grade A A-53 Grade B A-53 Grade A A-53 Grade B A-120 M to 4 6 to 4 2 to 12 2 to 24 2 to 24 2 to 24 2 to 24 2 to 24 2 to 12 6,225 6,750 8.400 9,000 10,200* 12,750* 12,000 15,000 10.400 * For use in the equation P = 2S (fra --c) D --0.8 Um -c) See American Standard Code for Pressure Piping, pub lished by ASMS, revised November, 1952. Where P -- working pressure, pounds per square inch. S m fiberetress, pounds per square inch. lm = 0.875 x wall thickness, inches. D " O. D., inches. ' e -- joint factor = 0.05 for 1-in. and smaller size or 0.065 for larger than 1-in, size. For electric resistance welded pipe tor applications where the temperature is below 650 F, and where PJlj t*1*8 classification is subjected to supplemental tests and/or heat treatments as agreed *v suPP"8r aod the purchaser, and whereby such supplemental tests and/or heat treatments demon characteristics of the weld to be equal to the minimum tensile strength specified for the pipe, the S values equal to the corresponding seamless grades may be used. standards for copper or red brass IPS, clay or concrete, and cast-iron pipe. Copies of the following specifications may be obtained from the American Society for Testing Materials: (1) steel, wrought-iron and cast-iron--Series A-> (2) copper and red brass--Series B, and (3) clay and concrete--Series C. Table 3 lists the sizes available in each of the specifications and classes of steel pipe. Note that butt-weld is not available above 4-in. size and that lap-weld, electric-resistance-weld, and seamless are not available be low 2-in. size. . Listed in Table 3 is the formula for allowable working pressures as given in the American Standard Code for Pressure Piping.1 In this formula is a actor c, which is intended as an allowance for corrosion, mechanical inRiiy, manufacturing tolerances, etc. At times this factor seems too con servative; for example, with J^-in., Schedule 40, steel pipe, the allowable . orking pressure is 314 psi. Yet this pipe is tested at 700 psi. The reason- m ^tablishing the factor c which influences the working pressure, is hat after nominal use the pipe may not be as sturdy as it was at the time 628 CHAPTER 27 1956 Guide of manufacture. Note that the joint factor, c, is opt included for plain end non-ferrous pipe as listed in Table 2. : In addition to IPS copper pipe, several varieties of copper tubing are in use with either flared or compression couplings or soldered joints. Dimen-, sions of copper water tubing intended for plumbing, underground water service, fuel-oil lines, gas lines, etc., have been standardized by the U. S. Government and the American Society far Testing Materials. Table 4. Thbeading Data fob Pipe Nominal Size* Pipe 0. D. . . Standard Weight Sxtba and Double Extra Stbong Thbeads peb Inch5 Coupling O. D. Coupling Length Threads per Inch Coupling O. D. Coupling Length H H ......... >6 n: 0.405 0.540 0.676 0.840 : 1.050 27 18 18 14 14 , 0.563 0.719 0.875 1.063 1.313 * 1M IMs 1M m 27 18 18 14 14 0.663 0.719 0.875 1.063 1.313 lMo 194 194 294 294 i 1.316 ' 11H - 1.576 2 UH 1.576 294 W 1.660 11M 1.900 2He 11H 2.054 291 m 1.990 11H 2.200 2H* 1194 2.200 294 2 2.375 im 2.750 294 1194 2.875 2H 294 2.875 8' 3.250 3H 8 3.375 494 3 3H 4 5 ------- 6 3.500 4.000 V 4.500 5.563 6.625 8. 8 8 8 8 4.000 4.625 5.000 6.296 7.390 3H 394 394 394 4 8 4.000 494 8 4.625 4H*' 8 5.200 4H 8 6.298 494 8 7.390 494 8 10 12 . 14 16 8.625 10.750 12.750 . 14.000 16.000 _ _ -- -- '-- ---- __ -- -- --. -- 8 8 8 8 8 9.625 11.750 14.000 15.000 17.000 594 694 694 6H 694 18 18.000 ___ __ __ 8 19.000 794 20 20.000' -- -- 8 21.000 79ff " a All dimensions in inches. .. ` ' b Taper of threads is H in. per ft on diameter on all sizes of pipe, and in couplings of 2J4 in. and over. Couplings 2 in. and smaller are straight tapped. c 5.562 for copper and red brass pipe. - . Note:.The wall thickness and inside diameter shown in Table 1 do not apply to copper and red brass pipe. Copper tube is classified in accordance with the wall thickness as follows. ! Type K--Heavy Wall. . Type L--Medium Wall. = - Type M--Light Wall. Type DWV--Light Wall--for drainage, waste, and vent service. In general. Type K is used for underground services and for general plumbing service where corrosion conditions are severe. Type h is used for general plumbing and heating service where conditions may be con sidered normal. Type M is used for sanitary drainage and other non pressure applications, for heating, and sometimes for other services less severe than those for which Types K or L are recommended. Type DWy Pipe, Fittings, Welding 629 is of lighter weight than Type M, and is used for sanitary drainage and other non-pressure applications. Type DWV tube may be used for all types of fill except cinders, where Type L is recommended. Where flexi bility is essential as in hidden replacement work, or where as few joints as passible are desired as in fuel-oil lines, the soft temper is commonly used. In new or exposed work copper tube of a hard temper is generally used. All three types are extensively used with soldered fittings. Standard dimensions, weights, and diameter and wall-thickness toler ances for these classes of copper tube are obtainable from Table 2. Copper pipe is also available with dimensions of steel pipe. In refrigeration lines, used in connection with air conditioning equip ment, copper tube is used extensively. For refrigeration use where tube absolutely free from scale and dirt is required, bright annealed copper tube that has been cleaned, dehydrated and sealed is used. This tube is available in a variety of sizes and wall thicknesses. Table 5. Normal Engagement of Tight-Fit Male and. Female Pipe Thbeads ' For American Standard and API Pipe Threads Pipe Size Engaged Length* In. Pipe Sizes Engaged Length* In. Pipe Sizes Engaged. Length* In. 94 94 HH % 94 H H Me 194 194 2 2 3 3H . 94 ' 1 IMe 4 194 5 IK 6 IMe 8 1 Me 10 194 12 194 is the normal tight-fit thread engagement from the leading edge of the female thread oacjc to toe leading edge of the male thread. No allowance has been made for threading variations. THREADING PRACTICE In all threaded pipe for heating and ventilating installations the American standard taper pipe thread, ASA B2.1-1942 is used. This thread is cut with a taper of 1 in 16 measured on the diameter of the pipe so as to secure a tight joint. The number of threads per inch varies with the pipe size, threads for fittings are the same, except that it is regular practice to furnish straight tapped couplings for Schedule 40 pipe 2 in. and smaller. For steam pressures in excess of 25 psi, it is recommended that taper-tapped couplings be used to obtain a tight joint. These may be secured by order ing fine pipe2 which is used for oil piping, the couplings of which are provided with taper-tapped threads and may be used with regular mill-threaded standard weight pipe. Thread lengths should be in accordance with m f 2.1. Right-hand threads are used unless otherwise ordered, to facilitate drainage, some elbows have the thread tapped at an angle to provide a pitch of the connecting pipe of y in. to the foot. These elbows are Known to the trade as pitch elbows and are commercially available. All hreaded pipe joints should be made up with a thread paste suitable for the service for which the pipe is to be used. Table 4 contains pertinent threading data for standard weight, extra rong and double extra strong steel, and wrought-iron pipe. The normal engagement of pipe threads is given in Table 5. 630 CHAPTER 27 1956/Guide .; . Table 6. Pipe Fittings , i : ... Elbows . 90,60,45 * 22}^ Standard 90 & 45 Street . 90 & 45 Female union 90 & 45 Butt-welding 90 & 45 Flanged . 90 Side outlet 90 side Outlet rolling Base. 90 & 45 Male union 90 & 45 Socket-welding.: 90 Rolling Drop ' Tees Standard Flanged Female union Flanged base Railing Service Flanged side outlet Female union outlet Butt-welding Side outlet railing . Four-way , Male union Flanged reducing Socket-welding. Drop . ` Couplings . Wrought . . Cast Socket-welding . 5 . ^ Crosses . Screwed Flanged . Butt-welding . .... , Y-Bends 45 Screwed 45 Flanged 45 Double screwed True flanged Return Bends Butt-welding Back outlet Screwed Union end Reducers Standard Butt-welding Eccentric Socket-welding Flanged taper Eccentric butt welding Flanged eccentric Bushings Outside hexagon Caps Standard Plugs Countersunk Nipples Close Unions Female Eccentric Socket-welding Square head Long Male & female Flange Face Butt-welding ' Bar . ... Tank Tongue & groove flange Flanges Blind Floor . Screwed Slip-on Welding neck Reducing PIPE FITTINGS Pipe is joined by butt welding one length to another or by the use of fittings. Pipe fittings are made in a variety of forms (the common types are listed in Table 6), and are screwed, flanged or welded. The type of fitting to be used is determined by the pressure of the fluid being carried, or by the use of the pipe line. The materials generally used are steel, cast iron, malleable iron (heat treated cast iron), copper, brass, stainless steel, alloy steel, or'bronze. The material used also depends upon the pressure or characteristics of the fluid. Fittings are designated and sized in accordance with American Standards Association specifications and are identified by their nominal pipe sizes. In the case of reducing tees, crosses, and Y-branches (laterals), the size of the largest run opening is given first, followed by the size of the opening at the opposite end of the run. Where the fitting is a tee or Y-branch Pipe, Fittings, Welding i h j. *: h[ 4x3x2 TEE 4x4x2 Y-BRANCH ._j_. ^ \ 4X3x2 y-branch 631 CROSS 4x413x2 CROSS 40*2x13 CROSS Fig. 1. Description op Tees and Laterals (ASA B16.3--1951) (lateral), the size of the outlet is given last. Where the fitting is a cross, the largest side-outlet opening is the third dimension given followed by the opening opposite. The straight line sketches, Fig. 1, illustrate how the reducing fittings are designated. , Where an external thread is wanted the word male follows the size of that opening. Allowable procures for solder type fittings are given in Table 7. Allow able pressures for ferrous screwed, flanged, and welding fittings are covered in the following ASA specifications: Type op Fitting Specification . Saturated Steam Pressure psig* Cast Iron--Flanged................................. Cast Iron--Flanged......................................... Cast Iron--Flanged (refrigeration)................. Uast Iron--Screwed. . ............................... Malleable Iron--Screwed........................... Malleable Iron--Screwed........................... Brass or Bronze--Screwed..................... Brass or Bronze--Screwed.................................. Steel--Flanged............................................ B16.1 B16b B16bl : B16.16 . B16.4 B16.3 B16.19 B16.15 B16.17 B16.5 125 250 800 300 125 and 150 150 300 125 250 2500 r "Pressure may reduce with increasing sizes. This pressure is the maximum allowed in this specification saturated steam. Higher pressures may be allowed with lower temperatures. . Steel welding (butt or socket type) fittings may be used for the same pressure as the pipe, providing wall thickness (or schedule number), and also the material, are the same as the pipe on which they are used. Screwed fittings include: couplings, elbows (45 or 90), return bends (close and open), tees, crosses, laterals (Y-branches), plugs, caps, lock nute, flanges, bushings, and reducing fittings (elbows, tees and couplings). Reducing fittings and bushings may be eccentrically tapped to permit drainage of condensate. Sometimes nipples are erroneously called fittings. Actually a nipple is a piece of pipe less than 12 in. long that has been threaded on both ends, "ipe 12 in. or longer is regarded as cut pipe. Nipples are classified as 632 CHAPTER 27 1956 Guide close or full thread, shoulder, short, and long. A close nipple is about twice the length of the pipe thread since the threads actually meet. A shoulder nipple has a shoulder between the threads and is further classified as short or long. All shoulder nipples are cut to specific lengths and sold in that manner. As a general rule, flanged joints are used when it is expected that the line will be disassembled quite often. There are three ways to attach the flange to the pipe; screwed, welded or lapped. Types of contact surface will be discussed. . ' Tables 8 to 14 give data on various types of ferrous fittings. Fittings for copper tubing are available in soldered, flared, or compres sion types (see Figure 2). Fittings for copper pipe of IPS dimensions are Table 7. Service Pressdre Ratings fob Wrought Copper or Bronze Solder Joint Fittings* Maximum Service Pressure, psiq Type or Solder Service Temp., F J4to lln.b Water m to 2In.b 2Hto 4In.l> Steam All ( 50-50 Tin-lead (ASTMB32 Alloy Grade ) 50A) j 95-5 Tin-antimony or 95-5 Lead-tin (ASTM B32 Alloy Grade 5A) 100 150 200 250 100 150 200 250 200 150 100 ' 85 500 400 300 200 175 125 90 75 400 350 250 175 ISO1! lood 50d 300 275 200 150 -- -- -- 15 -- -- 15 ' Solders with melting point 1100 F or i above 1 350 270 190 155 120 -Note: Ratings other than specified here may be used upon the recommendation of the manufacturer as to the proper solders that should be used. Extracted from American Standard for Wrought Copper and Bronze Solder Joint Fittings, B16.22-1951- b Standard water tube sizes except 1.8 in., which is H in. OD seamless copper tubing for refrigerator serv ice, etc. (ASTM B68). 0 These pressures may be used for cast-brass fittings (ASA B16.18-1G50) for sizes 2 in. and smaller. d These pressures may be used for cast-brass fittings (ASA B16.18-1950) for sizes 2H in. and above. e Also allowable fot cast-brass fittings (ASA B16.18-I950). ' available in screwed or soldered types. Table 15 gives size data for screwed fittings and Tables 16 and 17 for solder-type fittings for copper tube and pipe. The compression type fitting is generally limited to small sizes of tubing, while the flared and soldered types are used in both large and small sizes. An American Standard, ASA 40.2--1936, has been prepared to standardize dimensions of brass fittings for flared copper tubes. Flared tube fittings are widely used in refrigeration work where SAE dimensions and a 45 deg flare render most fittings interchangeable, although for refrigeration use, thread fits and tolerances on thread gages must be maintained within close limits. Brass fittings with SAE dimensions are not interchangeable with the American Standard fittings for water tubes. FLANGE FACINGS AND GASKETS There are many types of flange facings. The simplest, and the one most commonly used, is the plain face. This type of face is used with fittings shown in Table 9. Other facings, with varying complexity, are used for Pipe, Fittings, Welding 633 Table 8, Dimensions of Screwed Cast-Iron 90- and 45-Deg Elbows, ' . Tees, and Crosses (Class. 125) . (Straight Sizes) 90*ELBOW TEE CROSS 4S* ELBOW Nominal Pipe Size Center to End, Elbows, Tees, and Crosses A to End, 45-Deg Elbows C Length op Thread, Min B Width op Band, Min e Inside Diam eter op Fitting F \fftT Min Metal Thickness Outside Diameter of-Band, Min GH H H H 1W 1H 2 2H 3 3H 4 10 0.81 0.95 1.12 1.31 1.50 1.75 1.94 2.25 2.70 3.08 3.42 3.79 4.50O.lJi tf.Wi 8.08* 9.50* 0.73 0.80 0.88 0.98 1.12 1.29 1.43 1.68 1.95 2.17 2.39 2.61 3.05 3.46 4.28 5.16 5.97 0.32 0.36 0.43 0.50 0.68 0.67 0.70 0.75 0.92 0.98 1.03 1.08 1.18 1.28 1.47 1.68 1.88 0.38 0.44 0.60 0.56 0.62 0.69 0.75 0.84 0.94 1.00 1.06 1.12 1.18 1.28 1.47 1.68 1.88 0.584 0.719 0.897 0.540 0.675 0.840 1.107 1.385 1.730 1.970 1.050 1.315 1.660 1.900 2.445 2.975 3.600 4.100 2.375 2.875 3.500 4.000 4.600 5.663 6.725 8.725 4.500 5.563 6.625 8.625 10.850 10.750 12.850 12.750 0.110 0.120 0.130 0.155 0.170 0.185 0.200 0.220 0.240 0.260 0.280 0.310 0.380 0.430 0.550 0.690 0.800 0.93 1.12 1.34 1.63 1.95 2.39 2.68 3.28 3.86 4.62 5.20 5.79 7.05 8.28 10.63 13.12 15.47 From American Standard Dimensions of Cast-Iron Screwed Fittings, Class 125. ASA B16.4-1949. All dimensions given in inches. This applies to elbows and tees only. SOLDER-TYPE FITTING REFRIGERATOR TYPE FLAREO-TUBE FITTINGS FLAREO-TUBE FITTINGS Pig. 2. Copper ob Brass Tube Fittings 634 CHAPTER 27 1956 Guide Table 9~. Dimensions of Flanged Cast-Ibon Elbows, Double Branch Elbows, Tees, Ckosses, Laterals, True Y's (Straight Sizes), and Reducers (Class 125) ' Pipe, Fittings, Welding 63S tight joints, a gasket is usually inserted between the contact faces' of the; flanges. The flange bolts then draw the faces up so tight that the gasket' deforms into the face imperfections and thereby provides a tight joint. Gaskets are made of numerous materials, such as cork, paper, fiber, asbestos, metal (iron, steel, copper, etc.), and combinations of metal and some soft material. The proper gasket material to use depends upon the service of the pipe. The material should not be detrimentally affected by the chemical and thermal conditions of the fluid being carried. Table 10. Dimensions of Steel Butt-Weldino Fittings Long Radius Elbows 180-Deg Returns Straight Tees Nominal Pipe Size Center-to-End Diameter 90-Deg at Bevel - ElbowB A 45- Deg Elbows B Outside Center- Diameter to-Center at Bevel O Back to Face K Outside Diameter at Bevel Center-to-End Run C Outlet. M 1 194 m 2 294 3 394 5 14 20 1.315 1.660 1.900 2.375 2.875 3.500 4.000 4.500 5.563 6.625 8.625 10.750 12.750 14.000 16.000 18.000 20.000 24.000 194 194 2H 3 394 5H 6 7M 9 12 15 18 21 24 27 30 36. H 1 m 1M IH 2 . 294 w 3H 394 5 694 794 894 10 I1H 1294 15 1.315 1.660 1.900 2.375 2.875 3.500 4.000 4.500 5.563 6.625 8.625 10.750 12.750 : 14.000 16.000 18.000 20.000 .24.000 3 394 m 6 794 9 1094 12 15 18 24 30 36 42 48 54 60 72 29is 294 394 494s 594s 694 794 8H lOHs 12He 18M 2094 24M 28 32 36 40 48 1.315 1.660 1.900 2.375 2.875 3.500 4.000 4.500 5.563 6.625 8.625 10.750 12.750 14.000 16.000 18.000 20.000 24.000 From American Standard for Steel Butt*Weiding Fittings, ASA B16.9-1951. All dimensions are in inches. Dimension A is equal to 9$ of dimension O. 194 194 2M 294 ; 3 394 394 4f4 494 594 7 894 10 11 12 1394 15 17 194 194 m . 294 3 394 394 4H 494 594 7 894 10 ard All dimensions given are in inches. Does not apply to true Y's or double-flanged elbows. higher pressures. They include: male and female face (an insert type face), tongue-and-groove (an adaptation of the male and female type), lapped pipe to flange, lapped pipe to pipe, and ring and groove using neck flanges. As it is too expensive to machine flange faces sufficiently to provide water- VALVES Valves are made with the same end connections as fittings. A brief description of each type follows. . 1. Flanged. Ends: Made in sizes from in. up. Used whenever line fittings are gauged and if frequent removal is contemplated. Flanged valves facilitate installa tion when large sizes are used. 2. Screwed Ends: Most common type end. Can be used for all pressures. Usually confined to smaller size because of difficulty in making large screwed joints. Welding Ends: Available in steel only. Generally employed for high tempera ture--high pressure work. Difficult to disassemble in a welded line. This type in- 636; CHAPTER 27 , 1956 Guide : eludes butt-welding or socket-welding. See Tables 10 and 13 for size of fittings avail-' able in each class. The valves are made in the same;size range./ . , c. ::il 3. Braising fcufe: These ends'wre available on brassvalves. The ends have a special* shape to facilitate use of brazing alloys. These valves are used for higher tempera tures than solder end valves. .................... ; 4. Solder Ends: For use with copper tubing in plumbing, heating and air condi-' tioning. Should not be used at high temperatures. . .' 5, Flared Ends: For use with light wall tubing--either metal or plastic--and for' 11.Table Dimensions of Steel Flanged Fittings for Primary 150Service Pressure Rating of Psi (Gage) Pipe, Fittings, Welding 637 Brass should not be used for work requiring temperatures above 550 F. The brass used in valves is similar to that used in brass pipe and contains some tin and lead as well as copper and zinc. : 11.Table .Dimensions of Steel Flanged Fittings for Primary- Service Pressure Rating of 150 Psi (Gage) (Concluded) elbow LONG RADIUS ELBOW 1 2 3 4 5 6 7 8 0 10 11 Me In. Raised Face (Flange Edge) Ring Joint .. Nom inal* Pips Size Outside Diam eter or Flange O Thick ness or Flange, Min Center to Contact' Surface of Raised Face, Elbow, Tee, Cross, and True Y Center to Contact Surface of Raised Face, Long Radius Ell Center to Contact Surface of Raised Face, 45 Ell Long Center to Contact Surface of Raised Face, Lateral Short Center to Contact Surface of Raised Face, Lateral, - and True Y Contact Surface to Contact Surface of Raised Face, Re ducer C AA BB CC EE FF GG Center to End, Elbow, .Tee, Cross, and True Center to End, Long Radios EU Y HH JJ 1 in 134 2. 2H 3 SH 4 5 6 8 10 12 14 16 18 20 24 4H m 5 6 7 7H 8K 9 10 11 13H 16 19 21 23M 25 27M 32 ` Me M Me H `He H `Me `Me 3 Mi m 4 4M 5 m 6 634 `Me 1 1H lMe 134 1H lMe lMe l`Me m 7H 8 9 11 12 14 15 16M 18 . 22 5 m 6 6M 7 734 834 9 10H 11M 14 16M 19 21M 24 26M 29 34 1M 5M 2 634 234 7 2H 8 3 934 3 10 334 11M 4 12 4M 13M 5 1434 5M 17H m 20M 7H 24M' 7M 8 8M 9M 11 27 30 32 1 35 40M i* 154 2' 2M 234 3 3 3 334 3M 4M 5 534 6 634 7 8 9 4M 4H 4M 5 5H 6 634 7 8 9 11 12 14 16 18 19 20 24 . 3M 4 4M 4M 5M 5M 6H 6H 734 8M 9M 1134 12H 14M * 15M 1634 18H 22 M 634 554 6M 634 7M 8 8M 9H 10M HM 14M 1634 19M 21M 24M 3434 From American Standard for Steel Pipe Flanges and Flanged Fittings, 150, 300, 400, 600,900, 1500 and 2500 Lb. ASA B16.5 1953. All dimensions given in inches. - Actual diameter is same for sizes 1 to 12 in. and is M in. less than nominal for sizes 14 to 24 in. sizes 2 in. and below. A flaring tool flares the tubs end, and a ring nut pulls the flared tubing up against a seat on the valve. This makes a lap joint. 6. Hub Ends: Generally used for water supply and sewage piping. This type joint is used with cast iron pipe. The joint is a socket type made by inserting the pipe in the hub, then caulking with oakum. After caulking, the joint is sealed witn molten lead. ` Valves are made of brass, iron, steel, and to some extent malleable iron. 12 13 - 15 16 17 18 19 20 Ring Joint. Diam. Base Drilling Nominal, Pipe Size Center to End, 45-Deg Elbow EK Long . Center to End, Lateral Short Center to End, Lateral, and True Y LL MM Center to Base Round Base or Width op Square Base Thick ness of Base rSt Thick ness op Ribs U Bolt Circle or Bolt Spacing W Diam. of Drilled Holes 1 262 IK 234 634 2 m 234 734 2H 2 2H 3 3K 4 254 3K 3H 3K 4K 8M m 10)i liM . 12M 234 "iH 234 4h 3>4.. - 4H 334 5K 334 5M 4H m 5 5 6 34 34 3M 34 34 m 34 m 34 34 3H 34 34 4M 34 34 54 54 34 5 6 8 10 12 4M 1354 354 5M mm ; 354 554 1754 ! 454 654 20M 5M 754 2454 654 6K k 1134 7 7 9 9 11 >34 `Mo 1 >34# 54 34 34 1 34 534 534 734 734 . 934 34 34 34 34 34 14 16 18 20 24 . 7M 8H 8M .954 11M ' 27 M 30M 3254 35K 40M 634 12K 11 1 634 1354 11 l 734 15 13M 134 834 16 13M 134 934 18M 13M 134 1m 1 9M 134 1154 134 HH 134 11M 34 34 34 34 34 Cast iron is generally provided in some alloying state, especially in the larger sizes. Cast iron is not suitable for service (above 450 F). , Malleable iron, which is a cast iron heat treated to provide some ductily, is used to some extent, primarily in place of cast iron. Steel is used either in the cast or forged state. For corrosive service, oy and stainless steel are used. Steel is used for high temperature--high ;638 CHAPTER 27 1956 Guide pressure work. Steel is the only valve material that can stand appreciable expansion stresses. . :: The characteristics of valves restrict their use. The five main uses for valves are listed below: . 1. Stoppingflow: The most general use for valves. Gate valves are generally used for this purpose. The gate valve operates by a disc moving at right angles to the T 12.ablb Dimensions of Steel Flanges for Primary Service 150Pressure Rating of Psi (Gage) ' N o m inal P ip e Size 1 2 3 4 5 6 7 8 9 10 11 12 13 14 h. O CCfdi a fe o flSz O 2 os !g Z2 M< sH H oC Bot. ' K H an ap <x Q X . gs u | Length Through Hub Y 61 * - S IB o 2|2 o ol| aas dsqoS S3 CD.* W . tOD8-5O t) &6a6 X |ol & a 2 A 09 j $ x '' o 2 >4 g o& <a a os H T .2 aa o - a* 2 Bore B e is z* aa 2^ 2^c8c.H? E J IT * 8 Cfi o4 a ^ ps a o mjl (a0 to* s SotO. j< S OP rD H H 1 1W m 2 2H 3 m 4 5 6 8 10 12 14 16 18 20 24 3W M* lM 0.84 mHm 1.05 4W Ms HM 1.32 4H H 2M 1.66 5 lH 2M 1.90 6 M 3M 2.38. 7 7A 3M 2.88 7W lM 4*4 3.50 8H lM 4M 4.00 9 Me 5*4 4.50 10' 11 13H 16 19 Me 6*4# ' 1 7*4 1H ; 9**4 lMa 12 H4 14?4, 5.56 6.63 8.63 10.75 12.75 21 23 25 27 Yi 32 m 15M 1M# 18 1M 19*4 lH 22 m 26*4 14.00 16.00 18.00 20.00 24.00 *4e M *4 1 1H 1M 1*4 1M 1*4# 1M 1M, l`M 2M 2*4 2*4 2<H 2*4 3*4 *4 H 1 Ho *M# 1*4 2*4 2M 2*4 2*4# *4 ' H >Me M *4 0.88 1.09 1.36 1.70 1.95 1 m 1*4 1*4 lM 2*4 2*4 2*4 2*4e 3 1 Hi IMs 1*4 1*4 2.44 2.94 3.57 4.07 4.57 1*4# iM 1*4 I'M 2*4 3*4 3*4 4 4 4*4 IMs 5.66 1M# 6.72 1*4 8.72 1M 10.88 2*4# 12.88 3*4 3*4# 3M 4*4# 4*4 5 5 5*4 5*4a 6 2*4 14.14 2*4' 16.16 2*4a 18.18 2*4 20.20 3*4 24.25 0.90 1.11 L38 1.72 1.97 2.46 2.97 3.60 4.10 4.60 5.69 6.75 8.75 10.92 12.92 14.18 16.19 18.20 20.25 24.25 0.62 0.82 1.05 1.38 1.61 M .H H M 2.07 2.47 3.07 3.55 4.03 Me M M M Vie 5.05 6.07 7.98 10.02 12.00 Vie Vi Vi u SssJ *s is M Vi Vi H lie H M H Me It. From American Standard for Steel Pipe Flanges and Flanged Fittings. ASA B16.5-1953. All dimensions given in inches. path of the fluid. The fluid flows straight through the valve, hence, a gate valve offers the minimum resistance when it is fully open. The gate is moved by a stem screw attached to the handle. Gate valves are poor regulators because at nearly closed position (where best regulation is obtained) the fluid velocity either causes vibration and noise, or else tends to erode the disc. 2. Throttling flow: This is best accomplished by globe or angle valves. These valves cause the fluid to change direction, and consequently, offer considerable fluid resistance even when in the open position. Both the globe and angle valves operate by closing a plug into a fitted seat. The angle valve is similar to the globe valve Pipe, Fittings, Welding Table 13. Dimensions of Socket .Welding Fittings A. Dimensions op Socket Welding Elbows, Tees, and Crosses 639 Nom inal Pipe Size Depth op Socket Min Center to Bottom op Socket Sched 40 and 80 Sched 160 Bore Diam eter op Socket, - Min Socket Wall-Thickness Min Sched 40 1 Sched Sched 80 160 Bore Diameter op Fitting Sched 40 Sched 80 Sched 160 .A B C. D; H H. M* Vi M H Vi i7Az H: : H H H- Vi M 1 1M . m; Vi Vi Vi . H 1M 2- 2V4 3 M M M . 1H 2M H 7A lM 1M 1H m 2H 0.420 0.555 0.690 . 0.855 1.065 1.330 1.675 1.915 2.406 2.906 3.535 0.125 0.125 0:125 0.136 0.141 0.166 0.175 0.181 .0.193 0.254 0.270 0.125 0.149 0.158 0.184 0.193 0.224 0.239 0.250 0.273 0.345 0.375 0.234 0.273 0.313 0.313 0.351 0.429 0.469 0.546 0.269 0.364 0.493 0.622 0.824 - . 0.215 0.302 0.423 0.546 0.742 1.049 1.380 1.610 0.957 1.278 L500 2.067 2.469 3.068 1.939 2.323 2.900 0.466 0.614 0.815 1.160 1:338 1.689 2.125 2.626 B. Dimensions of Socketc Welding 45-Deg Elbows, Couplings, and Half Couplings 640 CHAPTER 27 1956 Guide Table 14. Dimensions Malleable of 90-Deg Elbows, Deg Elbows (Straight Sizes, 150 Tees, Lb); Crosses, and 45- Nominal Pipe Size Center to End, Elbows, Tees, and Center to End, 45-deq Elbows Thread, Min Band, Min |Inside Diameteb| OF FnTlNO Metal Thickness Outside Diameter of Band, Min B Mia Max G HH H M 0.69 0.81 0.95 1.12 0.73 0.80 0.88 0.25 0.32 0.36 0.43 0.200 0.215 0.230 .0.249 0.405 0.540 0.675 0.840 0.435 0.584 0.719 0.897 0.090 0.095 0.100 0.105 1H 1M 1M 1.31 1.60 1.75 1.94 0.98 1.12 1.29 1.43 0.50 0.58 0.67 0.70 0.273 0.302 0.341 0.368 1.050 1.315 1.660 1.900 1.107 1.385 1.730 1.970 0.120 0.134 0.145 0.155 2 m 3 3H 2.25 2.70 3.08 3.42 1.68 1.95 2.17 2.39 0.75 0.92 0.98 1.03 0.422 0.478 0.548 0.604 2.375 2.875 3.500 4.000 2.445 2.975 3.600 4.100 0.173 0.210 0.231 0.248 4 5 6 3.79 4.50 5.13 2.61 3.05 3.46 1.08 1.18 1.28 0.661 0.780 0.900 4.500 5.563 6.625 4.600 5.663 6.725 0*265 0.300 0.336 From American Standard for Malleable-Iron Screwed Fittings, 150 Lb. ASA B16.3-1951. 0.693 0.844 1.015 1.197 1.458 1.771 2.153 2.427 2.963 3.589 4.285 4.843 5.401 6.583 7.767 All dimensions given in inches. Table 15. Dimensions Crosses, 45-Deg of Brass or Elbows, and Bronze Screwed 90-Deg Elbows, Couplings (Straight Sizes 125 Lb) Tees, Nom inal Pipe Size H HH HM 1 1H m 2 2tf Center to End Elbows, Tees, Crosses Cen ter to Diameter Thread, Min End 45-Deg El Wrought Coupling bows Inside Diameter Band Length, op Cast Fitting Min . " Min Max BC D E Metal Thick ness, Min Band Diam eter, Min H End to End Straight Coupling Cast Wrought W 0.54 0.71 0.82 1.01 1.18 1.43 1.69 1.84 2.12 2.70 3.08 3.79 0.25 0.32 0.36 0.43 0.50 0.58 0.67 0.70 . 0.75 0.92 0.98 1.08 0.42 0.66 0.63 0.78 0.89 1.06 1.22 1.30 1.45 1.95 2.17 2.61 hi `Me `Ha IMe IMe 0.14 0.16 0.17 0.19 0.23 0.27 0.31 0.34 0.41 0.48 0.55 0.66 0.41 0.54 0.68 0.84 1.05 0.44 0.58 0.72 0.90 1.11 1.32 1.66 1.73 1.90 1.97 2.38 2.88 3.50 4.50 2.45 2. 3.60 4.60 0.08 0.08 0.09 0.09 0.10 0.11 0.12 0.13 0.15 0.17 0.19 0.22 0.67 0.81 1.00 1.17 1.42 1.72 2.10 2.38 2.92 3.49 4.20 5.31 0.80 0.97 1.05 1.29 1.43 1.68 1.86 1.92 2.20 2.88 3.18 3.69 Fittings, 125 Lb. AS4 B16.15-1947. All dimensions oven in inches. Pipe, Fittings, Welding 641 except that the outlet face is at an angle of 90 deg from the inlet face. -An angle valye takes the place of a globe valve and. an elbow. 3. Checking flow: Preventing back flow is called checking, hence, a check valve is used. The basic principle of all check valves is that a reversal of flow will close the valve. Check valves are either swing check or lift check. With a swing check the fluid presses on a hinged flap. If the flow stops or reverses, the flap swings down and seats itself to close the valve. A lift check operates similarly except that the flap is replaced by a plug that is lifted--through guides--by the force of the fluid flow. The fluid changes direction of flow, as in a globe valve, and transmits a vertical Table 16. Dimensions of Cast Brass Solder-Joint Elbows, Tees and 45-Deg Elbows. . (Straight Sizes) Standard Water Tube Size Latino Length* Tee and Elbow Center to External Shoulder 90-Deo Street Elbow Laying Lbntgh 45-Deg Elbow Center to External Shoulder 45-Deg Street Elbow H I JQ HH H Me H Hi H Hi 1H 1M H 1M 1 , 2 134 2H m 3 134 3M 2 4 2H 5m 6 3% 8 fH H Hi Hi `Hi H 1 1H 134 1H m m Hi Hi H Me Hi -H Hi H H H- `Me IMe 134 234 From American Standard for Cast-Brass Solder-Joint Fittings, ASA B16.18-1950. All dimensions given in inches. " Not standardized for tDrought fittingB. Consult manufacturer for dimensions. Hi Hi 34 Hi Hi 34. 34 thrust. If the flow stops, gravity pulls the plug downward and closes the valve A reversal of flow will close the valve. Two other types of valves are the relief valve and the pressure regulat ing valve. Relief valves are usually spring loaded in order that some pre determined pressure can force the valve to open and relieve the pressure. Pressure regulators are used to reduce a high incoming pressure to a re quired service pressure. These valves are designed to eliminate a fluctua tion in the incoming pressure and thereby maintain a steady, lower service pressure (see Chapter 21). Table 18 contains data on the dimensions of flanged and welding end valves. Dimensions of other type valves can be obtained by writing to the Manufacturers Standardization Society of the Valve and Fitting Industry. 642 CHAPTER 27 1956 Guide WELDING : Erection of piping in heating:and ventilating installations by means of fusion welding has been commonly accepted in the past few years as an alternate method .to the-.screwed and flanged joint, l Since the. question of economy- of welding as against' the. use of screwed and 'flanged fittings is dependent on'the individual job,.the..use of welding is generally recom mended; bii the basis of; greatly reduced cost of maintenance and: repair; 17.Table Dimensions op Cast Brass Solder-Joint Couplings (Straight, Reducing and Eccentric Sizes) 77, *M COUPLING c to c REDUCING COUPLING ZZZZZZS \777m WECCENTRIC COUPLING C TO C STRAIGHT REDUCING ECCENTRIC Stanpabd ` Wateb Tube -Sub Latino : M Standabd :Vfateb Tube Sue - . . .- Latino Length* N Standabd Wateb Tube Size 94 ...............94 . 94 H, .. 1 ' 194 194 2 294 3. 3H 4 6 6 8 He He 94 H a 94 H 91# Ho He H 94 H 94 H ' Mi M 1 X 94 1H x 1 194 x 94 lHxlH 194 X 1 lHx M 2 x 194 2 x 194 2 xl 2 x 94 294 x 2 Wx 1M 2Hx 1H 294 x 1 3 x 294 3 x2 4 x3 4 x 294 4 x2 6 x4 8 x6 Me H M H % H H H H H Mo He 94 94 94 94 lH# 1H 191# IHe 194 94 x 94 1 x 94 194 x 1 Wx H IHx IH 194x1 2 x 194 2 xl94 294x2 3 x 294 3 x2 4 i3 From American Standard for Cast*Brass Solder-Joint Fittings, ASA B16.18-1950. All dimensions given in inches. - - '- * Not standardised for wrought fittings. Consult manufacturer for dimensions. Latino Length* w. . `He 94 M >H >M# 194 *91# IH# 194 lM# 2 . . '* . reduced weight resulting from the use of a lighter-weight pipe; or increased economy in pipe insulation, hangers, and supports rather than any econ omy that might be effected in actual erection by welding on low to medium pressure heating jobs. . Fusion welding, commonly used in erection of piping, is defined as the process of joining metal parts in the molten, or molten and vapor states, without the application .of mechanical pressure or blows. Fusion welding embraces^gas welding and electric arc welding, both of which are commonly i-ipe, fittings, welding Table 18. Dimensions op Flanged Cast-Iron and Steel Valves Contact Sum-ace to Contact Sdbtacn Dimknsions, (3 X AA) Nominal Pn*E Sub Cast-Ibon Steel 8001 125 17#* 2501 Hy. 1501 30G1 draulic 60P 15001 1 1H 194 2 3 > 3294 m 4 56 8 10 12 14 OD 16 OD 18 OD 20 OD 24 OD 7 7H .8 8094 10 1094 113194 14 15 16 17 18 20 7M 8 . 9H 10 1094 1194 13 MM 1694 1794 894 094 1194 11% 12 15 1594 1694 18 1094 2294 24 26 H94 13 14 7 794 8 98>4 10 .13 14 16 16 17 18 20 794 894 994 1194 11% 12 15 1694 1694 18 1994 30 *8994 994 *1194 13 14 is . 18 1994 2394 2694 3294 3594 3894 4194. 4894? 894 9 994 118194 14 10. 11 12 1494 1694 15 24 29 33 4094 4494 48 52 61 10 11 12 1494 1694 1894 2194 2694 2794 3294 39 4494 94 194 794 794 194 194 894 894 10 9 9 11 10 11 2 8 294 8H 3m 394 4 1094 1194 1094 1194 1294 1394 14 894 994 1094 UH 1094 1194 1294 1394 14 994 U94 13 .14 994 1194 13 14 12 1494 1694 15 12 1494 1694 1894 2194 5 21From 6 American 13 14 1994 Standard for 1594 1794 ^ Face-to-Fsce 14 1594 16 17J4 I .... | a1v9s9*4 | 22 | 18 1994 2394 j 26 Dimensions of Ferrous Flanged and Welding 2694 E| nd222949Va. lve| s.323A227999S444A "16.10-1939. - Ail dimensions given in inches. Where dimensions are not given, the sires either are not made or there is insufficient demand to warrant the ^pense of unification. . . a ^en&}e and groove joint facings have bottom of groove in same plane as flange edge, and center to con- surface dimensions for these facings are reduced by the amount of the raised face. end' fokesearo pressure designations which refer te the primary service ratings in lb per sq in. of the connecting * The connecting end flanges of 175 lb valves are the same aa those on 250 lb valves. ifi CnniAA* ~ - 644 CHAPTER 27 1956 Guide used to produce acceptable welds. Welding processes and procedure are described in various publications. / Welding application requires the same basic knowledge of design as do the other types of assembly, but, in addition, requires a generous knowl edge of welding principles and particularly the welding qualities of metal, its reaction to extremely high temperatures, and the ability to select and use only the best quality welding rods. This requirement applies equally to employer and employee, with the employer accepting all of the respon sibility. Thus the employer should select his welding mechanics with good judgment, provide them with first-class equipment and tools, arrange for their training and use of acceptable workmanship standards, and at regular intervals subject their work to prescribed tests. ' Rules for fusion welding of pipe joints, the qualification of welding operators, welding procedures, and testing are contained in the Stand ard Manual on Pipe Welding* and in publications of other groups.1- *5 In general, the wall thickness and chemical analysis of the pipe are the governing factors, not the working pressure. There are a number of safety codes which govern the installation of welded piping in many cities and states. A complete line of manufactured steel welding fittings is now available, and a dimensional standard has been prepared under the procedure of the American Standards Association, (see Table 10) to unify heretofore diver gent dimensions for the same type welding fittings produced by different manufacturers. Standard dimensions for steel butt-welding elbows, tees, caps, and lapped-joint stub ends are given in Table 10.- Dimensions for eccentric and concentric reducers are not shown in Table 10, but are in cluded in the standard. : Steel butt-welding fittings have beveled ends. For wall thicknesses less than He in., the bevel may be either 37K deg. or cut square. For wall thicknesses of He in, to and including K in. the bevel is 37H deg. For walls larger than K in. but not greater than IK in., the bevel is U- shaped with a slope of 20 deg. above the He in. radius fillet. For walls greater than lM in., the weldmg ends are prepared as agreed between the manufacturer and the purchaser. Flange fittings may be welded from sizes H to 24 in. inclusive (see Table 12). . Socket-welding fittings also are commercially available. These fittings have a machined recess for inserting the pipe which is attached by a fillet weld between the pipe wall and socket end. Use of socket-welding fit tings generally is restricted to nominal pipe sizes 3 in. and smaller in which range commercial fittings are available. This type of fitting has gained rapid acceptance owing to its ease of installation, low cost, and ability to make a pressure tight joint without weakening the pipe, as is the case with threading. Dimensions for socket-welding fittings, in accordance with ASA Standard B16.11-1946, are given in Table 13. EXPANSION AND FLEXIBILITY Changes in temperature cause a change in dimensions of any matter. The metals that are used for pipe have the same characteristics in that they expand with increasing temperature. If the metal is constrained so Pipe, Fittings, Welding 645 that it cannot expand, then an internal material. compressive stress is set up in the This stress can be calculated, just Law. as any other stress, by using Hooke's where eBA (1) F = Force of constraint, pounds. e = Deformation, inches. .. B -- Modulus of elasticity, pounds per square inch. A -- Area of metal, square inches. , L = Length of metal, inches. .. , ,. , . . ; . . This equation is valuable in determining the internal stress of the pipe and also the constraining force on the anchors. This equation assumes that Tableau). ^Thermal Stresses due to Total Constraint TempeBatdre* CttANOB, F Deo 20 40 60 SO 100 por temperstunes between 32 and 400'F. the stress is less than the yield strength of the metal. In other words, the metal mil return, to its original dimension: when the temperature returns to its original level. ' Materials such as cast iron are not ductile, hence the yield strength is approximately equal to the ultimate strength. These materials have ex cellent compressive strength but poor tensile strength. For this reason, it is difficult to bend these materials appreciably. Cast iron, for. example, could be put in tension and, from Table 19, it is seen that for a temperature change of .100 deg., a compressive stress of 7140 psi would be developed. If the pipe were straight, this stress would be handled easily. If, however, the stress caused a bending moment, then fracture might occur. The values of stress found in Table 19 were determined by using Equa tion 1 and substituting Equation 2 for e where *.= aL&t o = coefficient of linear expansion, inches per inch. Al = temperature change, Fahrenheit degrees. This gives Equation 3 (2) Values for a and B are given Fin=TaaEbAleA2t 0 for various pipe materials, (t3o) 646 CHAPTER 27 -. 1956 Guide facilitate determination of the stress in-ah actual pipe. The following ex ample illustrates the computation of stress. , Example: What is the force set up by a 1 in. schedule 40 steel pipe if the thermal expansion from a 100 deg temperature increase is fully constrained? Answer: From Table 1, determine that for a 1' schedule 40 steel pipe, the metal area = 0.494 sq. ins. Then, from Table 20, aE = 195 psi, and from Equation 3 F = 195 X 0.494 X 100 = 9630 lbs. It is interesting to note that length does not enter into the determina tion of the constraining force. This is so because the stress is a unit length function and so is the expansion; therefore, they cancel each other. In other words, if a weight stretches a 10-foot wire 0.10 in., then that same weight would stretch a 100 foot wire one inch. In both cases the ;elongation: was. 1 part in 1200. The realization that thermal stress is independent of length is important, but often overlooked. Nonetheless, Table 20. Physical Pbopebtibs fob Detebmining Thebmal Stbess (Temperatures between $2 and 400 F) Steel Wbought ' Ibon Cast Ibon Bbabs OB Bbonze COPPBB Aluminum Coefficient of Linear Ex- 6.5 6.8 5.95 9.85 9.3 13.5 12 10Modulus of Elasticity, E, 30 28 14 16 195 190 71.4 138 149 135 -----------------7: Example: The coefficient o! expansionlor Bted = 0.0000065 in./in. endthe modulus oi elasticity = 39.000,000 psi. Therefore ctE = 195 psi. that concept explains the feasibility of utilizing the inherent flexibility of the pipe to take care of expansion. . Regardless of the length of pipe between anchors, it is possible to take care of the expansion by putting the force of expansion into the pipe as internal stress. If the pipe is not straight, then the force of expansion will cause a bend ing moment. The pipe will then be under a combined stress. The stresses will be longitudinal and transverse, and to a small extent radial. All of these stresses tend to fracture the pipe, and therefore must be added to make up what is called allowable combined, stress. The Code for Pressure Piping, ASA B31.1, published by the ASME, sets up very definite limits for the allowable combined stresses for various pipe materials. For tem peratures below 400 F and for piping that is for neither district heating nor power, any standard pipe material may be used. For high temperature or high pressure work, some text on expansion and flexibility should be consulted. It is beyond the scope of this chapter to develop the theory of expansion caused by high temperatures. . For the simpler problems encountered for temperatures 400 F and less, which the heating engineer is more apt to encounter, there are four methods of allowing for expansion. . The first method is to use packless expansion joints. These joints in- Pipe, Fittings, Welding 647 elude types of bellows expansion joints, rubber, corrugated copper and- other metals. : . Rubber type joints are generally Used in vacuum or low pressure steam lines. Maximum temperature is generally 180 F. If oil is present in the line, rubber type joints will be attacked. Travel of these joints is up to 1 inch. The travel to be expected can be calculated by using Equation 2. The second type of expansion joint is called a slip joint. This joint' allows for expansion by a sliding of a female member over a male member. The joint is kept tight by means of packing. The packing determines the limit of the temperature to which the joint may be subjected. The main disadvantage to this joint is that it must be continually inspected for a deterioration of the packing. By using double slip joints, the travel may go to several feet, but generally a single joint allows about a foot of ex pansion. It is common practice to use slip joints up to 250 psi. The most common method of allowing for expansion in heating systems is to use the swivel joint. This is the third method. The swivel joint was first used with screwed fittings, but it is also used now with welded fittings. With welded elbows, the swivel introduces torsional stress in the elbow and in the swing piece. This type of joint is adequate for taking up the Offset U bend Fig. 3. Meastjbement of L on Vabious Pipe Bends expansion in a header, and preventing fracture of the riser or heating ele ment. ..........................` ' The fourth method is to allow the flexibility of the pipe to absorb the stress of expansion. A technique used to reduce the stress in the ex panded pipe is to cold spring it before hooking it up. Cold springing can be used to absorb about one-half the stress. The technique is to install the pipe with an opposite stress. For example, if the pipe were to have a com pression of 2000 psi, then the pipe would be installed with 1000 psi of ten sion. For refrigeration, the pipe would be cold sprung in compression. For conditions not requiring rigorous analysis, it is permissible to use expansion bends designed by means of Equation 4 where L = 6.16VdK (4) = length of pipe, feet. . = O. D. of pipe, inches. A = deformation, inches (see Equation 2) fiber stress tk 16,000 pounds per square inch. Equation 4 can be used for bends with two fittings, regular U-bend, and offset U-bend, as shown in Fig. 3. It gives the length of pipe, L, that 648 CHAPTER 27 1956 Guide flaust be used in the U-bend to take up the deformation, A. When weld ing fittings are used, the radii should be six times the outside diameter of the pipe. One other restriction is that the pipe should not be heavier than e'xMtraansutrfoancgtu. rers-of. pipe, or pipe fittings, often publish excellent treatises on the simplification of expansion problems. It is suggested that the engineer obtain such publications and also a text or handbook8 on the sub ject before attempting to solve a problem on flexibility. HANGERS AND SUPPORTS In the preceding section, Equation 3 was developed to give the force of total constraint. This equation is appropriate regardless of the sign of At, positive or negative. It did not, however, allow for any bending moment but was for straight compression or tension. 21.Table Equations foe Bending Stress and Deflection between Supports . j - . Type op Support Bendtnq Stress, psi S Deflection, Inches Y Single span (free endB). Continuous line. 0.75WLW S- I s = 0.5 WL*D 22.5 WLl Y = El 4.5 WL* El where - W = Total weight (pipe, fluid, etc) pounds per foot. D = O. D. of pipe, inches. L = Length of span, feet. E = Modulus of elasticity, pounds per square inch. I = Moment of inertia, (inches)4. / = " (OD4 -- ID4), 0. D. and I. D. in inches. 04 If the compressive force is great enough, or if the line is long enough, a slight eccentricity of the load application will cause a budding of the line. This buckling is identical with the action of a column under excessive compression. In fact, a pipe line in compression is identical to a column. Column criteria can therefore be used for selecting the action of supports toAresciosmt lamtoenrael tqhurautsiot.n for determin.i.n...g....s.a..f.e.. column loads is Euler's for mula: = (O'I TT*E (for cast iron see Equation 6) (5) vhere S= allowable column load, pounds per square inch. k = radius of gyration, inches. I = column length, inches. ,.' I OD> + ID' k1 =.-- ----------------- A 16 Pipe, Fittings, Welding 649 This equation is not used for column construction but is sufficiently accurate for the work of a heating engineer. The equation is modified for cast iron because of its poor tensile strength. It is generally acceptable to use one-half the value of S from Equation 5 for cast iron, so it becomes for cast iron. (6) It is permissible to allow the l/k ratio for steel to go as hi'gh as 120, but for cast iron the desirable maximum is taken as 70. It is not to be under stood that a fracture will occur at l/k ratios in excess of those given, rather it is to be understood that lateral support should be given for those ratios and for those magnitudes of stress. If an expansion joint is used, this will, of course, relieve the compressive stress. 1 Example: For the problem given in the above section, the constraining force for a 1 in. pipe was 9630 lb. What is a required spacing for lateral support for this pipe? Answer: Using Euler's formula, Equation 5 gives S = **E so l = -rk^/E/S - For a 1 in. Schedule 40 steel pipe k = 0.4205 inches. E -- 30,000,000 pounds per square inch. S = 9630 H- 0.494 = 19500 psi . 1 = 51-8 inches. . Therefore, lateral supports on six foot centers would be adequate. The other type of load requiring some support is the bending stress due to the weight of the pipe, its insulation, and of the fluid being carried. There is also the bending moment that may be caused by the flexure of the pipe. For this chapter however, the flexure loading will not be treated for the reason of complexity, as previously stated for the problem of ex pansion. Since hangers should always be designed to take the bending moment (including buckling) from the pipe, it is necessary to design the hangers or supports for the maximum bending stress. Even with perfect support spacing there will be some sagging; therefore, the supports should be on a gradient if it is necessary to prevent pockets. Such a condition arises for condensate piping. Typical bending and deflection equations are given in Table 21 in order that supports can be properly sized, and if necessary, pitched. These equations are typical beam equations. If more complex loadings exist, proper beam equations can be applied. Such equations are found in standard texts on mechanics of materials. By application of the equations given in this section and the section of expansion and flexibility, it is possible to determine the proper location and type of support for straight lines. The types are anchors and hangers. Anchors are used to guide the expansion (sliding anchors) or to fix the pipe. They are needed to take the stress out of the line and translate the stresses to the foundations. In that way all stress can be. taken out of 650 CHAPTER 27 1956 Guide Table 22. Application of Pipe, Tube and Fittings fob Heating and Air Conditioning , Application * ' Better Class Fob Economy Chilled W ater Small Installations Large Installations V . 4-in. and smaller 5-in. and larger Cooling Tower ' Small Installations . Large Installations . Type K or L hard copper Black steel, Sch. 40 Type-K or L hard copper Black steel, Sch. 40 Black steel, Sch.'40 Black steel, Sch. 40 . Type K, hard copper ' . Wrought iron or black steel, Sch. 40 .. Type L, hard copper. Black steel, Sch. 40 Type L, hard copper. Black steel, Sch. 40 Underground Water Small Installations 2-in. and smaller Large Installations 33^-in. and smaller 4-in. and larger City Water Inside Building Small Installations Large Installations Type K, soft copper . Type K, soft copper or Cast iron, Class 150 Cast iron, Class 150 Type L, hard copper Type K or L, hard copper Type K, soft copper. Black steel, Sch. 40 Galvanized steel, Sch. 40 Galvanized steel, Sch. 40 Galvanized steel, Sch. 40 Galvanized steel, Sch. 40 or Type L, hard copper Underground Rain Water Conductors Small Installations Under paved areas Large Installations 8-in. and smaller : . . 10- to 24-in. 30-in. and larger 5 feet outside bldg. . and under paving Vitrified clay or cast iron soil Cast iron soil Cast iron soil XH Vitrified clay , Concrete Cast iron soil XH . Vitrified clay or cast iron soil Cast iron soil Vitrified clay Concrete Concrete Cast iron soil XH Interior Rain Water Con ductors Small Installations Large Installations Black wrought iron, Sch. 40 Cast iron soil XH Black steel, Sch. 40 or Galvanized steel, Sch. Ca4s0t iron soil XH or Ga,l vanized steel, Sch. 40 Panel Heating" Small Installations I.urge Installations . 2-in. and smaller 2f^-in. and larger Hot Water Heating*1 Small Installations Large Installations . 1^-in. and smaller 2-in. and larger Type K or L soft copper. Type L soft copper. Mild Mild black steel. Wrought black steel iron Type K soft copper. Mild Type L soft copper. Mild black steel. Wrought iron black steel Mild black steel Mild black steel Type K, hard copper. Black Black steel, Sch. 40 steel, Sch. 40 Type K hard copper. Black Black steel, Sch. 40 steel, Sch. 40 Black steel, Sch. 40 ' | Black steel, Sch. 40 Pipe, Fittings, Welding 651' lABLC"i vr i irn, a uon Anu rilTlNUa Heating and. Air Conditioning (Concluded) Application - Better Class ' Fob Economy .' Refrigerant1* 3j-in. and smaller 4-in. and larger Type KorL hard copper Type L hard copper Black steel, weld , Black steel, weld Steam Heating Small Installations 90 psi and less Large Installations 100 psi and over Return Pipe All sizes , Black steel, Sch. 40 . Black steel, Sch. SO. XH fittings Black wrought iron. Stand ard fittings Black steel, Sch. 40^ Standard fittings. - Black steel, Sch. 40. XH fittings Black steel, , Sch. .40. Standard fittings Receiver Vent All Sizes Galvanized wrought iron. Black steel, Sch. 40. Standard fittings Standard fittings Sanitary* ..__ ^ Small Installations Waste: 13^-in. and smaller 2-in. and larger Vents: 2)^-in. and smaller 3-in. and larger Large Installations Waste: 2-in. and larger Vents: 2-in. and larger Galvanized wrought iron Cast iron XH Galvanized wrought iron Cast iron XH Cast iron XH Cast iron XH Galyanized.steel, Sch. 40/ Cast iron SW Galvanized steel, Sch. 40 Cast iron SW Cast iron SW Cast iron SW Gas Fired All Sizes Black steel, Sch. 40. Mal Black steel, Sch. 40. Mal leable iron fittings leable iron fittings a r:..* ~ :--- -----------^ >v. a naiu i/*k^ uu>; Lfc enuer wnjiuut copper or C&8I Grass. Refrigerant fittings on copper pipe must be wrought copper. All welded fittings should be long turn. 0 Panel heating copper fittings should be soldered with 95-5 solder. Steel fittmgs should be welded. Installation tested to 300 psi hydrostatic for two (2) hours. , _. _ d All underground feed and return lines buried in slab, should be equipped with fittings as outlined for panel heating. e Rouse sewer to main should be cast iron XH. me une Delore it can be transferred to such equipment as boilers or pumps. By means of solid anchors, the anchors can be used to divide the piping into isolated sections that cannot transmit the stresses to other sections. Hangers are used to support the piping and to take out the bending stresses. They are of the spring, roller, or rod type. Such types gen erally allow the free movement of the pipe and yet maintain full support. The Code for Pressure Piping, ASA B31.1, has strict requirements for the materials used in hangers and supports. The structural properties have a safety factor of five, and consequently there is little chance of failure due to a sudden change of load. There is a type of support for almost every conceivable requirement. Complete information can best be obtained from a hanger manufacturer. APPLICATION OF PIPE, TUBE AND FITTINGS In the application of pipe, tube and fittings it is necessary to comply Avith regulations contained in local codes and ordinances. Table 22 is i ii-!i ` ii i .! ! i 'S ; " ! ji; :i it/ ':! I! !i 1956 Guide offered as a guide to current practice in heating and air conditioning. It is based on practice ifi a number of consulting engineers' offices and infor mation extracted from Reference 7. It should be borne in mind that selection of material to be used will also be influenced by the familiarity of local artisans with methods of using different materials. . REFERENCES 1 American Standard Code for Pressure Piping, ASA B-31.1--1942,' American Standards Association. 1 See API Specification SLfor Vine Pipe, American Petroleum Institute. * Standard Manual on Pipe Welding (Healing, Piping and Air Conditioning Con tractors National Association, Second Edition, 1951). Welding Handbook (American Welding Society, 1942). . * ASMS Power Boiler Code, American Society of-Mechanical Engineers. 5 Marine Engineering Regulations of the Coast Guard, American Bureau of Ship ping. '......... . .. General Specifications for Inspection of Material, Appendix VII, Welding, U. S. Navy. Specifications for Welding, Appendix 5, Part 1--General--for Vessels of the U. S. Navy, Bureau of Ships, April, 1940. . 6 See (1) Piping Handbook, by Sabin Crocker (McGraw-Hill Co.); (2) A Man ual for The Design of Piping for Flexibility by the Use of Graphs, by E. A. Wert, S. Smith, E. T. Cope (The Detroit Edison Company). 7 Control Valves and Positioners, by C. S. Beard (Industry and Power, Vol. 64 March, 1953, p. 67-101). CHAPTER; 28 ;; PIPE AND INDUSTRIAL INSULATION Heat Losses from Bare and Insulated Surfaces and Pipes, Thermal Conductivities of Various Insulations, Low Temperature Pipe Insulation, Insulation of ' Pipes to Prevent Freezing, Economical Thickness of Pipe Insulation, Underground Pipe Insulation HEAT LOSSES from or to uninsulated surfaces of pipes, ducts, vessels, or furnaces may be of considerable magnitude if the temperature of the surrounding medium differs appreciably from that of the surface^' Losses are increased by motion of the surrounding air or by contact of the hot or cold surface with bodies of high thermal conductivity. Good design, therefore, must include careful consideration of such heat losses and provision for adequate insulation wherever indicated. HEAT LOSSES FROM BARE SURFACES The basic principles of heat loss from surfaces are discussed in Chapter 5. In that chapter radiation and convection are treated separately. Table 1, Section A, of Chapter 9 gives the surface conductance of flat surfaces of different emissivities and orientations in contact with still air, the values given including the effects of both radiation and convection. , - .-. ... HEAT LOSSES FROM BARE PIPES Heat losses from horizontal bare steel pipes, based on tests at Mellon Institute and calculated from the fundamental radiation and convection equations (Chapter 5), are given in Table 1. Heat losses from horizontal copper tubes and pipes with tarnished surfaces, are given in Table 2.1 Heat losses from bare pipe of materials having lower emissivities may be calculated from data appearing in Chapter 5. The area in square feet per linear foot of pipe is given in Table 3 for various standard pipe sizes, and Table'4 for copper tubing, while Table 5 gives the area in square feet of flanges and fittings for various standard pipe sizes. These tables can be used to advantage in estimating the amount of insulation required. , ' Very often, when pipes are insulated, flanges and fittings are left bare, so as to allow for easy, access to the fittings in case of repairs. The fact that a pair of 8-in. standard flanges having an area of 2.41 sq ft would lose, at 100 lb steam pressure, an amount of heat equivalent to more than a ton of coal per year, shows the necessity for insulating such surfaces. Examples 1 and 2 show how the annual heat loss from uncovered pipe and its dollar value may be computed from the data in Table 1. Example 1: Compute the total annual heat'loss from 165 ft of 2 in. bare pipe in service 4000 hr per year. The pipe is carrying steam at 10 lb pressure and is exposed to an average air temperature of 70 F. Solution: The pipe temperature is taken as the steam temperature, which is 239.4 r > obtained by interpolation from Steam Tables. The temperature difference be tween the pipe and air = 239.4 -- 70 = 169.4 F. By interpolation of Table 1 between temperature differences of 157.1 and 227.7 F, the heat loss from a 2-in. pipe at a *ra- Hi t\i\![ ifi i' i(! ii 654 CHAPTER 28 1956 Guide Table 1. Heat Losses from ; Horizontal Babe Steel Pipes Expressed in Btu per (hour) (linearfoot) (Fahrenheit degree difference between the pipe ---- ** alilt flit (it 70 F") . -- --------r A s; , - * Hot Water ? ' Steam f 120 F : - 150 F Nominal Pip Size , 180 F 210 F 227.1 F.: 299.7 F 337.9 F (5 psig) (50 psig) (100 psig) ' (Inches) i. i Temperature Difference--F Deo 50 80 K H 1 IK 1V4 ' y- 2 20 3 . 30 -4 5 6 8 10 12 0.455 0.495 0.555 0.605 ... '' 0.684 : 0.743 0.847 : 0.919 i 0.658 1.041 ' 1.180 . 1.400 1.680 : 1.900 2.118 11281 1.532 1.825 2.064 2.302 2.580 2.804 3.036 3.294 . 3.880 4.215 4.760 5.180 . 5.590 6.070 110 0.546 0.666 0.819 1.014 1.148 1.412 1.683 2.010 2.221 2.534 . 3.084 3.626 4.638 6.680 6.670 140 | 157.1 227.7 | 0.584 0.716 0.877 1.086 1.230 1.512 1.796 2.153 2.433 2.717 3.303 3.886 4.960 6.090 7.145 0.612 0.748 ^ 0.919 1.138 1.288 0.706 0.866 1.065 1.324 1.492 4.578 -1.883 2.260 2.552 2.850 < 1.840 2.190 2.630 2.974 3.320 3.470 4.074 5.210 6.410 7.500 4.050 4.765 . 6.100 7.490 8.800 267.9 0.760 0.933 . 1.147 1.425 1.633 1.987 2.363 2.840 3.215 3.590 4.385 5.160 6.610 8.116 9.530 : \ Table 2. Heat Loss fkom Horizontal Tarnished Copper Pipe1 Expressed in Btu per (hour} (linear foot} (Fahrenheit degree difference between the pipe ' nn/i aurraundina still air at 70 F) Hot Wateb (Type K Copper Tube) Steam (Standard Pipe Size Pipe) Nominal Pipe Size, ' (Inches) 120 F . 150 F 180 F 210 F 227.1 F ` 297.7 F 337.9 F (5 psig) (50 psig) (100 psig) Temperature Difference--F Deg ' 50 80 no. 1*0 157.1 .227.7,. 267.9 0 0.250 . 6.287 0.340 0.381 0.440 0.475 0.500 0.559 0.580 . 0.656 0.300 0.409 0.509 0.618 0.710 0.321 0.429 0.536 0.622 0.750 0.433 0.533 0.638 . 0.764 . 0.904 . 0.500 0.543 0.746 0.878 1.053 0.530 0.654 0.803 0.934 1.120 1.0002 20 3 30 4 0.730 0.880 : 1.040 1.180 . 1.460 0.825 1.175 1.350 1.500 0.890 1.091 1.272 1.454 . 1.635 6.957 1.143 1.343 1.535 1.715 1.101 1.306 1.560 1.750 1.941 1.273 1.490 1.800 . 2.020 2.240 1.364 1.605 1.940 2.170 2.430 40 5 6 8 . 1.600 1.840 2.400 1.812 2.125 2.685 1.980 2.270 2.910 2.071 2.430 3.110 2.131 2.387 2.740 3.310 2.465 2.770 3.210 4.050 2.650 2.990 3.440 4.370 Table 3. External Subpace per Linear Foot op Pipe Nominal Pipe Size (Inches) .K K 1 IK IK Surface Area (So Ft) 0.22 0.275 0.344 0.435 0.498 Nominal Pipe Size (Inches) 2 20 3 30 4 Surface Area (Sq Ft) 0.622 0.753 0.917 1.047 1.178 Nominal Pipe Size (Inches) 5 6 8 10 . 12 1.456 1.734 2.257 2.817 3.338 Pipe and Industrial Insulation 655 Table 4. External Surface per Linear Foot of Copper Tubing Outside diameter Vh in. greater than nominal size - Tube Size (Inches) 0 H 1 IK IK Surface Area (SqFt) 0.164 0.229 0.295 0.360 0.426 Tube Size (Inches) 2 2K 3 30 4 Surface Area (Sq Ft) 0.556 : - 0.687 ` . 0.818 0.949 1.080 Tube Size (Inches) ' Surface Area (Sq Ft) 65 .. . . .. 1.342 ; 1.604 " 8 , 2.128 perature difference of 169;4Fisfoundtobe 1.624Btu per (hr) (linearft) (Fdeg). The total annual heat loss from the entire line = 1.624 X 169.4 X'165 (linear ft) X 4000 (hr) = 181,600 Mb. (Mb = 1000 Btu.) . . . Example S: Coal costing $11.50 per ton and haying a calorific value of 13,000 Btu per pound is being burned in the furnace supplying steam to the pipe line given in the previous example. If the system is operating at an overall efficiency of 55 percent, determine the monetary value of the annual heat loss from the line. Solution: The cost of heat per 1000 Mb supplied to the system = 1,000,000 X 11.5 (dollars) [13,000 (Btu) X 2000 (lb) X 0.55 (efficiency)) = $0,804. The total cost of heat lost per year = 0.804 X 181.6 (thousand Mb) = $146.00. INDUSTRIAL AND PIPE INSULATIONS Insulating materials are made of various substances and are supplied in a number of different forms. Preformed insulations are made in the form of blocks for flat surfaces, segmental pieces for small cylindrical vessels and large pipes, and sectional insulation for smaller pipes. Preformed pipe insulation is regularly supplied in sectional form up to about 12-inch pipe size. Certain types up to 20-inch pipe size are available in sectional form. Sections are either split in half longitudinally or . cut through on one side and scored on the inner surface of the other to facilitate applica tion to the pipe. Blanket insulations are used to insulate flat or curved surfaces or large pipes. Pipe fittings and bends are commonly insulated with portions of standard preformed insulations,; or,, when irregular in contour, with blankets or plastic insulating cements. . ,. Insulation is secured to pipes, flat surfaces, and large vessels in a variety of ways depending on the contour of the surface and the form of the in- Table 5. Area of Flanged Fittings, Square Feet* Nominal Pipe Size (Inches) Flanged Coupling 90 Deg Ell Standard Extra Heavy Standard Extra Heavy Long Radius Ell Standard Extra Heavy Tee' Standard Extra Heavy Cross Standard Extra Heavy 1 0.320 0.438 0.795 1.015 0.892 1.0S3 1;235 1-575 1.622 .2.07 IK 0.383 0.510 0.957 1.098 1.084 1.340 1.481 1.925 1.943 2.53 10 0.477 0.727 1.174 1.332 1.337 1.874 1.815 2-68 2.38 .3.54 0.672 0.848 1.65 2.01 1.84 2.16 2.54 3.09 3.32 . 4.06 20 0.841 1.107 2.09 2.57 2.32 2.76 3.21 4-05 4.19 _ 3 30 4 0.945 1.122 1.344 1.484 1.644 1.914 2.38 2.98 3.53 3.49 3.96 4.64 2.68 3.28 3.96 3.74 4.28 4.99 3.66 4.48 5.41 5-33 4.77 6.04 5.83 . 7.07 7.03 6.95 .7.89' 9.24 40 5 1.474 2.04 3.95 5.02 4.43 5.46 6.07 7.72 7.87 10.07 1.622 2.18 4.44 5.47 5.00 6.02 6.81 8.52 8.82 10.97 6 8 1.82 2.78 5.13 6.99 5.99 7.76 7.84 10.64 10.08 13.75 2.41 3.77 6.98 9.76 8.56 11.09 10.55 14.74 13.44 . 18.97 3.43 5.20 10.18 13.58 12.35 15.60 15.41 20.41 19.58 26.26 4.41 6.71 13.08 17.73 16.35 18.76 19.67 26.65 24.87 34.11 * deluding areas of accompanying flanges bolted to the fitting. 656 CHAPTER 28 1956 Guide sulation. The manufacturer's recommendations should be followed. Pipe insulation is usually fastened with staples across' the joints between sections and with metal bands or wire rings to hold individual sections and keep all joints tight. Surface finishes used over insulations depends upon the exposure, whether indoor or outdoor, the temperature of the insulated surface, and the ap pearance desired. The insulations over flat or large curved surfaces, operating at temperatures above the ambient, are usually coated with a finishing cement when exposed to indoor conditions and by a finishing cement plus a weatherproof finish when used outdoors., The insulation over pipes operating above ambient temperature is usually coated with a canvas cover for indoor exposure and an asphalt impregnated felt for outdoor exposure. Sectional pipe covering is available with a, wide variety of surface finishes and jackets. Insulation over surfaces operating at temperatures below the ambient must be protected from water vapor penetration, whether used indoors or outdoors. The selection of an insulation for a particular service condition should be made with full consideration of a number of properties in addition to thermal conductivity. Factors which may, under certain circumstances, be of more importance than thermal conductivity are ease of application, fire resistance, heat stability, weathering stability, and resistance to deimage by physical abuse. Other factors may apply to a particular in stallation. A complete evaluation of all insulations cemnot be included here. Insulation manufacturers should be consulted with regard to the selection of insulation to meet specific requirements. In general, the use of skilled and experienced applicators will go a long way toward insuring a satisfactory installation. Elbows and fittings should be covered with an insulation of equal thick ness and material which is similar to the pipe covering. Pre-fabricated fittings are available for many types of insulation, such as cork and rock cork. Where asbestos cement or magnesia cement is used to build up the fittings, the material should be applied in layers not exceeding a, thickness of % in. The final coat should be mixed with 10 percent Portland cement and troweled smooth. After the final coat has thoroughly dried, it is recom mended that canvas of the same weight as that used on the pipe covering be pasted over the surface. This procedure will prevent the built-up portions of the covering from falling off due to a slight bump or other minor damage. On permanent installations of high quality, it is recommended that all coverings and fittings be further encased in 8-oz. canvas, drawn tight over rosin-sized paper and sewed in place, using not less than four stitches per inch. All pipe covering which has a high differential temperature between the pipe surface and the ambient air should be provided with metal pipe sleeves around the covering to support the pipe by means of hangers on the out side of the covering, thus preventing the conduction of heat through the hangers. HEAT LOSSES FROM INSULATED PIPES Table 6 lists a number of typical thermal conductivities for various insulating materials. These conductivities have been selected as average design values for engineering calculations and must not be confused with Pipe and Industrial Insulation 657 J. AiSLsEi O. AHEitMAL Conductivity (&) of Industrial and Pipe Insulations , (For Mean Temperatures Indicated) Expressed in Biu per {hour) (square foot) (Fahrenheit degree temperature difference. 1 per in.) Form Material (Composition) (mineral wool 1 {Rock. Slog, or Glass) Metal Reinforced Felt-Flexible Type < Felt-Semi-Rigid Type VEGETABLE & ANIMAL FIBER Hair Felt or Hear Felt plus Jute . ASBESTOS * Molded Amosite & Binder Laminated Asbestos Paper Q Corrugated & Laminated Asbestos Paper 4 ply 6 ply 3 CALCIUM SILICATE Q Z < CELLULAR GLASS CORKBOARD (Without Added Binder) DIATOMACEOUS SILICA 02 85% MAGNESIA o o Mag. Carb. & Asbestos MINERAL WOOL {Rock, Slag or Glass) Low Temp. (Asphalt or Resin Bonded) High Temp. (Resin Bonded) . (With Inorganic Binder) PLASTICS (Foamed) RUBBER (Foamed) ASBESTOS Molded Amosite <fc Binder Laminated Asbestos Paper Corrugated & Laminated Asbestos Paper 4 Ply per in. . 6 Ply per in. i 8 Ply per in. z o CALCIUM SILICATE Calc. Sil. & Asbestos CELLULAR GLASS CORK (Without Added Binder) DIATOMACEOUS SILICA 85% MAGNESLA Mag. Carb. & Asbestos MINERAL WOOL (Rock, Slag or Glass) Low Temp. (Asphalt or Resin Bonded) Low Temp. (Fine Fiber Resin Bonded) High Temp. Blanket-Type (Metal Rein forced) PLASTICS (Foamed) RUBBER (Foamed) VEGETABLE & ANIMAL FIBER Wool Felt Hair Felt or Hair Felt plus Jute ,Z 38 85% MAGNESIA mAsbestos WOOL {Rock, Slav or Ola,,) With Colloidal Clay Binder scutaeturer s ac?p,`ed "maximum. When recommendations should be followed. operating temperature approaches actual test data. The conductivity of any particular insulation or pip covering can only be obtained from unbiased tests, or from data guaran teed by the manufacturer. . The terms standard and double standard thickness of magnesia ano diatomaeeous silica pipe covering have been declared obsolete by the 658 CHAPTER 28 1956 Guide Magnesia Insulation Manufacturer's Association. - The new simplified nominal inch thicknesses for these insulations are 1, 1%, 2, 2)4, 3, 3)4, 4, 4)4.and 5. for most pipe sizes M to 33 in. Most of these new nominal thicknesses are slightly greater than the actual thickness. Revision of Pipe and Industrial Insulation 659 with a moderate or low temperature insulation around it as an outer layer. By this method an efficient material may be used for each of the two tem perature ranges encountered. In calculating the heat loss through such a combination the mean temperature of each layer must be .determined along with the thickness of each. This is readily done in . three, or four calculations performed as a series of approximations, in which assumptions Fig. 1. Heat Loss Through 1 In. Thick 85 percent Magnesia Ttpe Covering the heat loss charts, Figs. I, 2 and 3, will be made, but forthe present these charts may be used with the factors given in Table 7 for all of the insula tions shown in Table 6 without serious error. Pipes operating at high temperatures are frequently insulated to the best advantage by combining a high temperature insulation near the pipe Pig. 2. Heat Loss Through 1)4 In. Thick 85 percent Magnesia Type Covering of thickness and mean temperature are adjusted as indicated in the dis cussion which follows. In the case of a single thickness of pipe covering, the quantity of .heat transferred per square foot of outer surface of the insulation is given by the equation:. '1 . where Hu - U) 9o =-------------- . r, rt log, - fl (1) 9o = Btu per (hour) (square foot of outer surface of insulation). 0 = outer radius of pipe or inner radius of insulation, inches. 660 CHAPTER 28 1956 Guide >t = outer radius of insulation, inches. . . fc = thermal conductivity of insulation, Btu per (hour) (square foot), (Fahren- ' heit degree per inch). U -- temperature of inner surface of insulation, Fahrenheit degrees. f? = temperature of outer surface of insulation, Fahrenheit degrees. . , . It is convenient to work from the outer surface of the insulation, since the loss through the covering must be determined from the outer surface loss by means, of surface loss curves such as given in Fig. 4. The curves were plotted from tests conducted at the Mellon Institute. Fig. 3. Heat Loss Through 2 In'.'Thick 85 percent Magnesia Type Covering After the true heat loss is obtained, the loss per square foot of pipe sur face can be calculated from the relationship: . where ?i = gAri/n) - . q, = Btu per (hour) (square foot outer surface of pipe). The heat loss through two or more thicknesses of insulation applied to a pipe can be calculated by means'of the equation: , --U q,, = ------------------- ;------------------ r. log. - r, log. n r, (2) . where ri -- outer radius of second layer of insulation, inches, r, = outer radius of last layer of insulation, inches. The method of solving Equation 2, which is the most difficult of the two, is given in Exam-pie S. Example S: Compute the heat loss per linear foot of pipe surface per hour from a 6-in. pipe, insulated with a 3-in. thickness of diatomaceous silica, 1900 F maximum type, and a 2-in. thickness of 85 percent magnesia. The pipe is operating at a tem perature of 1200 F and is exposed to a room temperature of 80 F. Solution: In figuring the heat loss from Equation 2, it is necessary to first make an assumption for the outer surface temperature tt and the temperature between the diatomaceous silica and 85 percent magnesia insulation, so that the mean tempera ture of each material can be obtained and the thermal conductivity corresponding to the mean temperature of each material substituted in the formula. First assume an outer surface temperature of 140 F and a temperature of 570 F between the two ma terials corresponding to a mean temperature of (1200 + 570) + 2 or 885 F for the dia- Tabi.e 7, Pipe Covering Factors to be Applied to Figs, 1,: 2 and 3 Type or Pipe Insulation . Mean Temperater*, Fahrenheit 40 70 100 200 3Q0 1 too 8oMW*5>rO7%tTUTMteTLLArAD\TGFETjfNTND>EtlbAS.hTMIAVAO, SITE AND - BINDER . : ; , CLAOMRIRNUAGTAETDE. DASABNESDTOLSAMPAINPAETRE(D35rA4S0BPEeSr ITnO.)S PAPER i 1.05 1.05 1 1.05 1 0.89 1.08 1:05 0.95 1.13 1.05 1.05 1.01 1.09 1.07 ,1.24 4 Ply Per In. r. 6 Ply Per In. . .; 8 Ply Per In. . CALCIUM SILICATE ' .. CELLULAR GLASS >: DIATOMACEOUS SILICA (22 lb 1 cu ft) DIATOMACEOUS SILICA (25 lb I cu ft) : MINERAL WOOL (Rock, Slag or Glass) = f 1.49 l.&d 1.54 1.37 1.70 1,48 1.87 1.62 1 *T 1.05 1.08 1.32 0.97 1.10 i.;43 1.00 1.20 1.52 1.03 1.29 1.13 . . * *-- 1.24 Low Temp, (Asphalt or Resin Bonded) T -- 1.44 Low Temp, (Fine Fiber Resin Bonded) ; High Temp. (Blanket,. Metal Reinforced) , PLASTICS (Foamed) RUBBER (Foamed) . WOOL FELT ; '; HAIR FELT OR HAIR FELT PLUS JUTE- 0.80 0.74 0.66 0.83 0.77 0.83 0.64 0^78 0.72 0.86 0.78 0.89 0.65 0.78 0.84 0:68 0.89 0.81 0.98 0.68 0.90 -- 0.73 0.98 - 1.05 . 1.18 1.39 1.14 1.34 ---T--h^evsiearvcaulurerosmarTeasbulebs6t,itaurteed0.i7n96Eaqnud.at0io..4n6_72__Ba_t_nu_d, aretsrpiaelctcivaelclyu.latiooin and made. 355 F, For a nominal 6-in. steel pipe: rj = 3.312, r = 6.312, and r3 = 8.312. Then, : 1200 - 140 1060 onin I 6.312 8 312 ,Qg* ^ 8.3X2 log, 8.312 ~ 6.74 + 4.89 = 911 Btu` 6.312 0_._7_9__6 t0f..4W67f The temperature drop from the outer surface of the insulation to the surrounding air for a heat loss of 91.1 Btu is found from Fig. 4 to be 55 deg for a 16-in. O.D. cylin drical surface, or 55 + 80 F room temperature = 135 F surface temperature. Since a surface temperature of 140 F was assumed, it is evident that a temperature closer tp 135 F, or, for instance, 136 F should be used for recalculation: 1200 .- 136 . 9o = 6.74 + 4.89 = 91'5 Btu- Since the temperature drop through each material is equal to the heat flow times the actual resistance of each material, the temperature drop through the diatomaceous silica is 91.5 X 6.74 = 617F, or the temperature between the two insulating materials >s (1200 -- 617) = 583 F. Since a temperature of 570 F between the two materials was 662 CHAPTER 28 1956 Guide assumed; it is obvious,that a temperature closer to 583, or for instance 5821*' may be selected. The mean temperatures of the two insulations corresponding to the new assumptions are (1200 + 582) 2 = 891 and (582 4- 136) 2 = 359, and the inter polated conductivities corresponding to the new mean temperatures are 0.798-and ,0,468 .for, the diatomaceous silica and. 85 percent magnesia, respectively.. By sub stituting in Equation 2 1200 - 136 5.36 2.29 0.798 rf 0.468 1064 6.72 + 4.90 91.5 Bin- Again referring to Fig. 4, it is seen that the temperature drop from ithe face of the insulation to the surrounding air for a heat loss of 91.5 Btu - 58 deg, wmcn Flo. 4. Heat Loss from Canvas-Covebed Cylindrical Subfaces of "" Various Diameters corresponds to the surface temperature of 136 F last assumed. The temperature drop through the diatomaceous silica is 91.5 X 6.72 = 615 F, corresponding to a tem perature of 585 F between the two materials, which checks very closely with the tem perature of 582 F last assumed. The heat loss is therefore 91-5 X 8.312 -s- 3.312 or 230 Btu per soft of pipe surface. Since the surface area per linear foot of 6-in. pipe is 1.734 sq ft (Table 3), the heat loss per linear foot of pipe will be 230 X 1.734 = 390 Btu per hr. ' The rate of heat loss from a surface maintained at constant temperature is greatly increased by air circulation over the surface. In the case of well-insulated surfaces, the increases in losses due to air velocity are very small as compared with increases from bare surfaces, because of the fact that air flowing over the surface of the insulation can increase only the conductance of heat from surface to air, and cannot change the internal conductance of the insulation itself. The maximum increase in heat loss Pipe and Industrial Insulation 663 due to air velocity ranges from about 16 percent in the case of 1-in. thick . insulation, to about 5 percent in the case of 3-in. thick insulation, pro vided that the insulation is thoroughly sealed so that air can flow only . over the surface. If the conditions are such that the air may circulate through cracks and crevices in the insulation, the increases may. be far greater than those given. Therefore, it is essential that insulation be applied in such a maimer that air circulation within it, or between it and the pipe, is avoided. ` . ; . : ; Piping which is covered with a water-mixed product or insulation which will absorb moisture, particularly in damp locations, should be coated with a corrosion resisting paint, such as black asphaltum. This precaution may prevent early failure due to external pipe corrosion. . The frequent practice of omitting insulation on that portion of a pipe which passes through a masonry wall, or which may be in contact with other metals, should be avoided. Physical contact between the pipe sur face and other structural materials of high thermal conductivity will re sult in heat transfer much greater than that shown in Tables 1 and 2 for transfer from bare pipe to air. The saving due to use of insulation on piping is illustrated in Example 4 ' Example 4: If the steam pipe given in Examples 1 and S is covered with 1 in. thick 85 percent magnesia, determine the resulting total annual loss through the insulation. Also compute the monetary value of the annual saving and the percentage of saving over the neat loss from the bare pipe. : .. Solution: By referring to Fig. 1, the coefficient for 1 in. magnesia covering on a 2-in. pipe is found to be 0.300 Btu per (hr) (linear ft of pipe) (deg temperature difference) at a temperature difference of 169.4 F. Referring to Table 7 the correction factor to be applied is 1.05 X 0.300 -- 0.315. The total hourly loss per linear foot of pipe will then be 0.315 X 169.4 = 53.3 Btu- The total annual loss through the insulation = 53.3 X 165 (linear ft) X 4000 (hr) = 34,600 Mb. The annual bare pipe loss as determined in the solution of Example 1 was found to be 181,600 Mb. The saving due to insulation is then 181,600 -- 34,600 = 147,000 Mb per year. . From the solution of Example 2, it was found that the heat supplied to the system cost $0,804 per thousand Mb. Therefore, the monetary value of the saving - - 0.804 (dollars) X 147 (thousand Mb) = $118.00, or 81.0 percent of the cost when using un insulated pipe. LOW TEMPERATURE PIPE INSULATION Surfaces maintained at temperatures lower than the surrounding air are insulated to reduce the flow of heat and to prevent condensation. The insulating material should absorb a minimum amount of moisture, because the absorption of moisture substantially increases the conduc tivity of the material.. This property is particularly important in the insulation of surfaces that are below the dew-point of the surrounding air. In such cases, due to vapor pressure difference, it is necessary to seal the surface of the insulating material against the penetration of water vapor which would condense within the material, causing a serious increase in heat flow, possible breakdown of the material, and corrosion of metal surfaces. An insulating material with a high degree of moisture absorp tion might pick up moisture before application and then, when the seal is In place and the temperature of the insulated surface reduced, release that moisture to the cold surface. There are a number of methods of pro ducing vapor seals, some of which have been worked out by insulation 664 CHAPTER 28 1956 Guide manufacturers to suit their products, and others by applicators and users. Unless time-proven methods are known, specifications'of insulation man ufacturers should be obtained and followed carefully. Pipingmust be carefully protected against corrosion caused by condensa tion of water vapor. All metallic surfaces should be coated with a vapor- Pipe and Industrial Insulation 665 tion on pipes and flat metallic surfaces may be obtained from Fig. 5 in which a surface resistance of 0.606, corresponding to a film conductance of 1.65, was used in calculating the curves. This value provides a slight factor of safety and its use is known to give satisfactory field results. In using, the chart it is advisable to specify the next thicker, rather than the next thinner, commercial insulation in cases where an intermediate thickness is indicated. Heat gains for pipes insulated with a material having an installed conducitivity of 0.30 Btu per (sq ft) (hr) (F deg per in.) are given in Table 8. This table may be used for any of the commercial insulations offered for this purpose since they have conductivities very near the 0.3 value used. Table 8. Heat Gains for Insulated Cold Pipes Rales of heal transmission given in Btu per (hour) (Fahrenheit degree temperature difference between fluid in pipe and surrounding still air) Based on materials having conductivity, k 0.S0 Nominal Pipe Size (Inches) H H 1 IK 2 2K 3 3K 4 5 6 8 10 12 Ice.Water Thickness Thickness of Insulation (Inches) Bto Per Linear Foot Btu Per Surface 1.5 0.110 0.502 1.6 0.119 0.431 1.6 0.139 0.403 1.6 0.155 0.357 1.5 0.174 0.351 1.5 0.200 0.322 1.5 0.228 0.803 1.5 0.269 0.293 1.5 0.295 0.282 1.7 0.294 0.248 1.7 0.349 . 0.239 1.7 0.404 0.233 1.0 0.455 0.201 1.9 0.559 0.198 1.0 0.648 0.194 Brine Thickness Thickness of Insolation (Inches) Btu Per Linear Foot Btu Per Sq Ft Pipe Surface 2.0 0.098 0.446 2.0 0.111 0.405 2.0 0.124 0.352 2.4 0.131 0.300 2.5 0.134 0.270 2.5 0.151 0.244 2.6 0.170 0.226 2.7 0.186 0.202 2.9 0.191 0.183 2.9 0.209 0.176 3.0 0.241 0.165 3.0 0.259 0.150 3.0 0.318 0.140 3.0 0383 0.135 3.0 0.438 0.131 Heavy Brine Thickness Thickness of Insulation (Inches) Btu Per Linear Foot Btu Per Sq Ft Pipe Surface 2.8 0.087. 0.394 2.9 0.094 0.340 3.0 0.104 0.294 3.1 0;113 0.280 3.2 0.118 0.238 3.3 0.134 0.214 3.3 0.147 0.197 3.4 0.162 0.176 3.5 0.176 0.167 3.7 0.182 0.164 3.9 0.202 0.138 4.0 0.228 0.130 4.0 0.263 0.116 4.0 0.309 0.110 4.0 0.364 0.108 * Solve problems as indicated by dotted line, entering chart at lower left band scale Fig. 5. Thickness of Pipe Insulation to Prevent Condensation on Outer Surface* impervious barrier (some types of which have an asphaltic or tar base) without any breaks or openings in order to prevent corrosion. The thickness of insulation required to prevent condensation on the outer surface is that thickness which will raise the temperature of the outer surface of the insulation to a point slightly higher than the dew point of the surrounding vapor. The dew-point for various -humidities can be readily ascertained from a psychrometric chart. The external vapor barrier must be made as nearly perfect as possible in order to prevent leakage of vapor into the insulation. The approximate required thickness of insulation to prevent condensa- INSULATION OF PIPES TO PREVENT FREEZING If the surrounding air temperature remains sufficiently low for an ample period of time, insulation cannot prevent the freezing of still water, or of water flowing at such a velocity that the quantity of heat carried in the water is not sufficient to take care of the heat losses which will result and cause the temperature of the water to be lowered to the freezing point. Insulation can materially prolong the time required for the water to give up its heat, and if the velocity of the water flowing in the pipe is main tained at a sufficiently high rate, freezing may be prevented. Table 9 may be used for making estimates of the thickness of insula tion necessary to take care of still water in pipes at various water and surrounding air temperature conditions. Because of the damage and service interruptions which may result from frozen water in pipes, it is essential that an efficient insulation be utilized. This table is based on the use of a material having a conductivity of 0.30. The initial water tern- 666 CHAPTER 28 1956 Guide perature is assumed to be 10 deg above, and the surrounding air temperature 50 deg below, the freezing point of water (temperature1' difference, 60, F). ; The last column of Table 9 gives the minimum quantity of water at initial temperature of 42 F which should be supplied every hour for each linear foot of pipe, in order to prevent the temperature of the water from being lowered to the freezing point. The weights given in this column should be multiplied by the total length of the exposed, pipe line expressed in feet. As an additional factor of safety, and in order to provide against temporary reductions in flow occasioned by reduced pressure, it is ad; visable to double the rates of flow listed in the table. : It must be empha sized that the flow'rates and periods of time designated apply only for the conditions stated. To estimate for other service conditions, the following method of procedure may be used. If water enters the pipe at 52 F instead of 42 F, the time required to' Table 9. Data fob Estimating Requirements to Prevent Freezing of -nr...TM** x>tdttc wtttt Surrounding Air at --18 F cool it to the freezing point will be prolonged to twice that given in the table, or the rate of flow of water may be reduced so that the quantity required will-be one-half that shown in the last column of Table 9. How ever, if the water enters the pipe at 34 F, it will be cooled to 32 F in one- fifth of the time given in the table. It will then be necessary to increase the rate of flow so that five times the specified quantity of water will have - to be supplied in order to prevent freezing. ' If the minimum air temperature is -- 38 F (temperature difference 80 F) instead of --18 F, the time required to cool the water to the freezing point will be 60/80 of the time given in, the table, or the necessary quantity of water to be supplied will be 80/60 of that given. In making calculations to arrive at the values given in Table 9, the loss of heat stored in the insulation, the effect of a varying temperature difference due to the cooling of pipe and water, and the resistance of the outer surface of the insulation to the transfer of heat to the air, have all been neglected, - When these factors enter into the computations it is necessary to.enlarge the factor of safety. Also as stated, the time shown in the table is that required to lower the water to the freezing point. A Pipe and Industrial Insulation 667 longer period would be required to freeze the water, but the danger point is reached when freezing starts. The flow of water will stop and the entire line will be in danger as soon as the water freezes across the section of the pipe at any point. When water must remain stationary longer than the times designated in Table 9, the only safe way to insure against freezing is to install a steam or hot water pipe parallel to the cold water pipe or to place an electric re sistance heater along-the side of the exposed water pipe. The heating system and the water pipe are then insulated so that the heat losses from the heating system are not excessive, and the heating effect is concentrated against the water pipe where it is needed. For this form of protection 2 in. of an efficient insulation may be applied. ECONOMICAL THICKNESS OF PIPE INSULATION The thicknesses of insulation which ordinarily are used for various temperature conditions are given in Table 10. Where a thorough analysis Table 10. Thickness of Pipe Insulation Ordinarily Used Indoors* Steam Pressure Psig oa Condition 0to25 25 to 100 100 to 200 Low Superheat Medium Superheat High Superheat Steam Temperature Fahrenheit Decrees 212 to 267 267 to 338 338 to 388 388 to 600 500 to GOO 600 to 700 Thickness op Insulation Pipes Larger Than 4 In. 1 In. IK in. 2 in. 254 in. 3 in. 3)j in. Pipes 2 In. to 4 In. 1 in. 1 in. 1)4 in. 2 in. 254 In. 3 in. Pipes H In to 1)4 In. 1 in. 1 in. 1 in. 154 in. 2 in. 2 in. * All piping located outdoors or exposed to weather is ordinarily insulated to a thickness H in. greater than shown in this table, and covered with a waterproof jacket. of economic thickness is desired, this may be accomplished through the use of the chart, Fig. 6. The dotted line on the chart illustrates its use in solving a typical example. In using the chart, start with the scale at the left bottom margin representing the given number of hours of operation per year; then proceed vertically to the line representing the given value of heat; thence horizontally to the right, to the line representing the given tem perature difference; thence vertically to the fine representing the con ductivity of the given material; thence horizontally to the left, to the line representing the given discount on that material; thence vertically to the curve representing the required percent return on the investment; thence horizontally to the right, to the curve representing the given pipe size; thence vertically to the scale at the top right margin where the eco nomical thickness may be read off directly. A rapid method for determining the economical thickness of insulation by use of tables has been published.2 UNDERGROUND PIPE INSULATION Underground steam distribution pipes may be installed in protective structures of various types, sizes and shapes (see (Chapter 29). Detailed 668 CHAPTER 28 1956 Guide data on commonly used forms of' tunnels and conduit systems, have been published by the National District Heating Association} ! Another form of underground insulation consists of the direct burial of the pipe in a trench with a complete covering of about 4 in. of a granular bitumen which', upon heating, forms a semiplastic, waterproof covering having a very good insulating value. The pipe must be supported on a solid insulating substance such as insulating blocks or asbestos cement pipe sections filled with an insulating cement. The expansion of steam arid hot water pipes, using loop expansion joints, offers no difficulty as the plastic nature of the warm material allows free movement of the pipes. Care must be exercised in installing this material in accordance with the manufacturer's recommendations. Pipes in tunnels are covered with sectional insulation to provide maxi mum thermal efficiency, and are also fitiished with good mechanical pro tection in the form of metal or waterproofing membrane outer jackets. Table 11. Thickness of Loose Insulation fob Use as Fill in Underground Conduit Systems Steam Pressure Pbio or Condition Steam Temperature Fahrenheit Degrees Minimum Thickness or Insulation in Inches Steam Lines Return Lines Pipes Less Pipes 4 In. Pipes Larger Pipes Less Pipes 4 In. than 4 In. to 10 Id. than 12 In. than 4 In. ana Larger Hot Water, or 0 to 25 212 to 267 da 2 2H IX m 25 to 125 267 to 352 2 2V2 3 da l H Above 125, or superheat 352 to 500 2-k! 3 3H IX DA Minimum Distance Between Steam AND Return i da m In some instances, where actual submersion of hot lines may occur, it has been found good practice to fasten the covering securely with corrosion resistant wire, and then sew on a wire-inserted asbestos fabric.jacket with wire. This jacket is porous. The principle of withstanding submersion is that water may enter as water, then actually boil at the pipe surfaces and escape as steam without rupturing the insulation or jacket,. Conduit systems are in more general use than tunnels. Pipes carried in conduits may be insulated with sectional insulation; however, the more usual practice is to fill the entire section of the conduit around the pipes with high quality, loose insulating material. The insulation must be ijept dry at all times, and for this purpose effective waterproofing membranes enclose the insulation. A drainage system is also provided to divert water which may tend to enter the conduit. , The economical thickness of insulation- for underground work is difficult to determine accurately due to the, many variables which have to be considered. As a result of theories4 previously developed,-together with other experimental data which have been presented, the usual endeavor is to secure not less than 90 percent efficiency for underground pipingTable 11 can be used as a guide in arriving at the minimum thickness of loose insulation fills to use for laying out conduit systems. Other factors such as the number of pipes and their combination of sizes, as well as the Pipe and industrial Insulation 669 (L. B, McMillan, Proc. National District Heating Association, Vol. IS, p. 138). Fio. 6. Chart for Determining Economical Thickness of Pipe Insulation 670 CHAPTER 28 .1956 Guide standard conduit sizes, are primary controlling factors in the amount and thickness of insulation for use. When sectional insulation is applied to pipes in tunnels or conduits, usual practice is to apply the most efficient materials in. less in thick ness than that determined by the use of Fig. 6. The data in Fig. 6 are based on conditions of insulation exposed to the air, whereas normal ground temperature is substituted for air temperature in determining the tem perature difference for use with the chart when applying it for underground pipe system estimates. REFERENCES 1 Heat Loss from Copper Piping, by.R. H. Heilman (Healing, Pi-ping and Air Con ditioning, September 1933, p. 458). `Rapid Method of Determining the Economical Thickness of Pipe Insulation, by Utley W. Smith (A.S.H.V.E. Journal Section, Heating, Piping and Air Condi tioning, October 1947, p. 118). * District Heating Handbook of the National District Heating Association, Third Edition, 1951. Theory of Heat Losses from Pipes Buried in the Ground, by J. R. Allen (A.S.H.V.E; Transactions, Vol. 26, 1920, p. 335). BIBLIOGRAPHY Heat Emission from Iron and Copper Pipe, by F. C. Houghten and Carl Gutberlet (AH.H.V.E. Transactions, Vol. 39, 1938, p. 97). . Heat Transmission from Surfaces (Philip Carey Mfg. Co., Bulletin 102-A). Surface Heat Transmission, by R. H. Heilman (Mechanical Engineering, Sec. 1, May 1929, p. 355). Piping Handbook, by S. Crocker (McGraw-Hill Book Co., Fourth Edition, 1945). Insulation Handbook, by P. Swain {Power, Vol. 94, Nos. 2, 3, 5, 7, and 9, 1950). How to Insulate Equipment, by U. W. Smith (Plant Engineering, Vol. 1, No. 2, Dec. 1947, p. 32). . Heat Transfer Through Thick Insulation on Cylindrical Enclosures, by T. S. Nickeraon and G. M. Dusinberre (ASME Transactions, Vol. 70, No. 8, November 194A8p, ppl.ie9d03H).eal Transmission, by Herman J. Stoever (McGraw-Hill Book Co., 1941). CHAPTER 29 DISTRICT HEATING Steam Requirements, Distribution Pressures, Boiler Plants, Distribution Piping, Pipe Sizes, Conduits for Piping, Accessory Equipment, Insulation, Return of Condensate, Pipe Tunnels, Building Piping and Equipment, Zoning and Operation, Metering THE term district healing refers to the supplying of heat from a central plant to a group of buildings in a city, institution, housing development; or factory area. The heat may be used for space heating, air condition ing, processing, or other purposes. It is usually preferable that groups of industrial or institutional buildings be supplied from a central plant rather than by individual plants in order to permit use of less expensive fuel, improve efficiency of combustion, reduce the labor required, assure use of competent operators, and often decrease the investment for heating pur pose. . . .. ' Those phases of district heating which frequently fall within the prov ince of the heating engineer are outlined here, and information is given for solving incidental problems in connection with institutions, housing de velopments, and factories. Some data are included with reference to special requirements for district heating steam piping. Design of a com plete district heating installation to provide utility service in a city should not be attempted unless a thorough study of the entire problem has been made by competent men having experience in district heating. . STEAM REQUIREMENTS The first step in the design of a district heating system is to determine the maximum hourly and the annual steam requirements of each of the buildings to be supplied. Methods of determining the maximum hourly requirements, or heat load, will be found for space heating in Chapter 12, for building service-water heating in Chapter 49, and for various process applications in Table 1. Measured demands of several types of buildings are given in Table 10, Chapter 18. Methods of estimating annual steam requirements for heating various types of buildings are also given in Chapter 18. Table 7 in Chapter 18 lists average annual steam, consumption per degree day for buildings lo cated in all sections of the United States. Annual steam requirements for building service-water heating are given in Table 2. Table 1 may be used to estimate annual consumptions for process applications if the hourly requirements are multiplied by the hours per year the equipment will be in use. Additional data on steam requirements of various types of buildings in a number of cities may be found in the District Heating Handbook, Third Edition. ' STEAM DISTRIBUTION PRESSURES The pressure at which the steam is to be distributed will depend upon that available at the plant and pressure requirements of apparatus to be served. ............... The advantages of low-pressure distribution (2 to 50 psig) compared 671 672 CHAPTER 29 1956 Guide Table 1. Unit Steam Consumption op Pbocess Equipment5 Kitchen Appliances (exclusive op wateb heating) Consumption,* Lb peb Hb . Pressure, psig Stock and vegetable kettles (per 5 gal) Vegetable steamere (per compartment) Steam tables (per sq ft) Bain-Maries (per sq ft) . Coffee urns (par gal) Water urns (per gal) Soup warmers (30 X 30 X 28 in.) Egg boilers (3 compartments) Clam, lobster, and potato steamem (per compartment) Oyster pots ' Plate and cup warmers (per ft) cu It) Food-warming ovens (per 20 cu it) Silver burnisher and washers Dishwashers (per tray) Laundry Equipment . . 20.0 40.0 1.7 3.4 3.4 5.0 100.0 18.0 40.0 18.0 36.0 36.0 69.0 60.0 . 7-20 7-20 7-20 7-20 7-20 7-20 7-20 7-20 7-20 7-20 7-20 7-20 7-20 7-20 Tumblers .. 40 X 94 in. 30 X 36 in. Washers, (per gal water heated) Flatwork ironers, 100 to 120 in. chest type (per roll) 60 to 100 in. cylinder type (per machine) Standard presses Luge shirt body presses Caff and neckband presses Bleevem Steam-electric irons - Woolen pressing machines Large--electric vacuum . Small--electric vacuum Large--steam vacuum Small--steam vacuum Feather cleaning and sterilising 16 pillows per hr Hospital Equipment Sterilisers, for bottles or pasteurization (per bottle) Sterilisers, for water, (per gal) Sterilisers, for instruments and utensils, 8 X 0 X 18 in., water depth 3% in. 9 X 10 X 20 in., water depth 3}4 in. 10 X 12 X 22 in., water depth 4 in. 12 X 16 X 24 in., water depth 4 in. - 10 X 12 X 36 in., water depth 4 in. 16 X 16 X 20 in., water depth 10 in. 20 X 20 X 24 in., water depth 24 in. Sterilisers, for instruments @ 240-260 F, 12 X 20 in. 14.X 22 in. 16 X 24 in. ' 360 225 1 60 60-120 106 190 15 12 8 . . " 25 12 35 20 175 100 100 15-100 100 100 100 100 100 100 100 65 65 65 65 . 100 1 12 . 27 30 39 60 66 92 144 48 60 72 40 ' 40 40 40 40 40 40 40 40 40 40 40 District Heating 673 Table 1. Unit Steam Consumption of Process Equipment (Concluded). Hospital Equipment (continued) Consumption, Lb per Hr Pressure, psig Sterilizers, for surgical supplies 10 X 20 in. 12 X 20 in. 14 X 22 in. 16 X 24 in. 16 X 36 in. 20 X 28 in. 20 X 36 in. 20 X 48 in. 20 X 60 in. . 10 22 28 38 54 60 78 98 . ; 124 : 40 40 40 40 40 . . - 40 40 40 . * 4> ' -V \ Sterilizers, (autoclave) (240-250 F) 15.5 X 24 in. 17.5 X 26 in. 21.5 X 30 in. . 24 X 36 in. 24 32 40 . 42 40 * 40 40 40 Disinfector, mattress 30 X 42 X 84 in. 60 X 66 X 108 In. Blanket warmers 18 X 24 X 72 in. ' 42 ' 318 4 35-60 35-60 35-60 b District Heating Handbook (National District Heating Association, Third Edition. 1951). tnese values represent approximate requirements after warm-up period. with high pressure are: (1) lower heat loss per square foot of pipe surface; (2) less trouble with traps and valves; (3) simpler problems in pressure reduction at the buildings; and (4) general reduction in maintenance'costs. With distribution pressures not exceeding 50 psig, there is less danger if the full distribution pressure should build up in the radiators or heaters through the faulty operation of pressure-regulating valves. With pres sures higher than 50 psig, a second pressure-reducing valve or some form of emergency relief is required to prevent excessive pressures in the radiators or other heaters.1 : The advantages of high-pressure distribution are: (1) smaller pipe sizes; (2) availability of the steam for various other operations requiring higher pressures than the building heating system; and (3) wider flexibility in allowance for maximum pressure drop. Where distribution pressures Table 2. Annual Steam Consumption fob Water Heating fob Various Ttpes of Buildings, per Cu Ft of Volume* b Type op Building Consumption, Lb/(Yr)(Cu Ft) Consumption Lb/(Yb) (Cu Ft) (100 F deg Temp. Rise op Water) Hotel B*sidence Club Apartment House Department Store Office Theatre Parking Garage 3.20 2.56 2.41 0.95 0.85 . 0.57 0.46 2.66 2.11 1.99 0.79 0.71 0.48 0.38 i. on analysis by fourteen district heating companies from metered consumptions. Building volume afprowmate gross volume. rona District Heating Handbook (National District Heating Association, Third Edition, 1951, p. 347). 674 CHAPTER 29 1956 Guide are not as highas desired, higher pressures can be obtained by use of a steam compressor.5 ' It is .sometimes desirable to install a separate high-pressure line from the boiler plant for steam supply to laundries or other high-pressure equip ment rather than to operate the entire distribution system at higher pres sures. r BOILER :PLANTS - j; In the design of a plant for district heating, consideration should be given to the following factors: 1.Annual load factor. The ratio of the average hourly plant send-out (defined as rate of flow to the distribution system) to the maximum hourly send-out, which is a direct measure of the extent to which investment in facilities is used. Thisfactor-is often employed to determine savings by equipment offering higher efficiency . The load factor for space heating is usually between 10 and 30 percent. For space heating Table 3. Load Duration fob Typical Distbict-Heatino System {Cumulative {fours of Plant Send-out per Year at Various hoods Expressed in Percent ' of Peak Hourly Load') .. *NBoates:eAd bpnlacnutrvheavoinngpa&gpee8a9k, Ir>einsdtr-ioeui tHoefa1ti0n0g,00H0alnbdbpoeorkh, rTwhiirldt sEendditioount,8109,05010. (80- perc'ent1 of 1*00,000} .tb per hr or more for 300 hr per yr. plus additional steam requirements such as water heating, cooking, or laundry, it is between 15 and 40 percent. Load factors for various types of buildings are given in Ta2b. leDu10ra, tCiohnaopftelora1d8.. The cumulative number of hours for the various plant sendouts, is used to determine the number and sizes of boilers in order to effect most effi cient loading of individual units and of the plant as a whole. The cumulative number of hours a typical district heating plant will send out steam at various loads, with loads expressed in percentage of maximum hourly rate, is given in Table 3- It will be noted that the duration of load for the higher send-outs is very low. 3. Feed-water treatment. This is desirable in plants to prevent corrosion and scale for4m. aStimoonk.e abaternenl. This is a modern requirement. The installation of suitable fuel-burning and dust-collecting equipment to limit the emission of smoke and fly as.h5.isPulasunat llolycanteiocens. saAry.boiler plant should be situated where fuel deliveries, water supply, and other utility services are convenient and should be as near as possible to the distribution center in order to simplify and shorten the distribution piping. STEAM DISTRIBUTION PIPING The methods used in district heating: work for the distribution of steam, are applicable, to any problem involving the supply of steam to a group of buildings.; The first step is to establish,the route of the pipes which is in fluenced .by local conditions and investment. Important points in laying out distribution piping are: , 1. The depth of the conduit should bq kept at a minimum. Excavation costs are a District Heating 675 large factor'in the total cost. On the other hand, institutional lawns will be dam aged if steam conduit is too close to the surface. 2. The use of basement or sub-sidewalk space for the distribution piping where feasible may reduce the cost of installation and maintenance. . 3. In some industrial and institutional applications, the distribution piping may be installed, entirely or in part, above ground. This method of construction has the advantage of requiring no excavation and permits easy maintenance but it may in troduce freeze-up problems. Thin corrugated aluminum sheets are available for covering the insulation on lines exposed to the weather. - .' 4. Piping routed in loops with suitable valves to provide alternate feeds for major loads, allows service to be maintained despite trouble in any one feeder. PIPE SIZES After establishing the route of the pipes, the next step is to determine the pipe sizes. In district heating work it is common practice to design the piping system on the basis of pressure drop. The initial pressure and the minimum permissible terminal pressure are specified, and toe pipe sizes are so chosen that the required amount of steam, with suitable allowances for future increases, will be transmitted without exceeding this pressure drop. The steam velocity is therefore almost disregarded and may be very high. Velocities of 35,000 fpm are not considered high. By the use of high velocities the pipe sizes are kept to a minimum with consequent savings in investment. Some lines in a loop system may need to be in creased in size in order to handle reverse-direction flow in emergencies. The steam flowing through any section of the piping can be computed from a study of the hourly steam requirements of the several buildings served. Steam requirements for ventilation-air heating, water heating, laundering, cooking, or processing, should be individually calculated and added to the heating load. Unusual features, such as large heaters for swimming pools, should not be overlooked. When the lengths of pipe, steam quantities, and initial and terminal pressures have been chosen, the pipe sizes can be calculated by means of Babcock's pressure drop formula given in Table 2 of Chapter 21. The district-heating industry uses Unwin's formula for determining pipe sizes because pressure drops can be determined simply and directly from a chart. This formula has been checked by tests, and found correct within ranges of velocity used in district heating. A. convenient chart developed from this formula is available from the National District Healing Association;* and provides a simple yet accurate means for determining pipe sizes. CONDUITS FOR PIPING Conduits for underground steam pipes should be reasonably waterproof and able to withstand earth and traffic loads. Since it is difficult to make a concrete or masonry conduit absolutely watertight, provision should be made for some seepage. The pipe should he protected by a waterproof jacket over toe insulation, unless subject to actual submersion, and the seepage should be drained from the inside of the conduit. Underdrainage of the conduit is generally obtained by means of a tile drain laid in gravel underneath the conduit. The tile underdrain should discharge to a sewer or some other drainage point. Manholes are required at intervals for access to valves, traps, and some types of expansion joints. There are many types of conduits, some of which are prefabricated prod- 676 CHAPTER 29 1956 Guide ucts and some of which are built in the field. The more common forms are illustrated in Fig. 1. ' " Conduits B and C are prefabricated. In conduii C the pipe is insulated and then placed concentrically within the metal jacket. The intervening space between jacket and insulation is filled with high-melting-point as phalt which becomes the protective medium for the insulation. Conduit B has spirally corrugated galvanized ingot iron surrounding the insulation and high-melting-point asphalt is applied to the outside of the conduit. The pipe is supported by precast rings to maintain alignment and to pre vent pressure on the insulation. .. Fig. 1. Construction Details op Conduits* * From District Heating Bandbooh, Third Edition. Conduits A and D are of concrete-box construction and are typical of coCndounitdsubituEilitsooffcsoomlidm-opnoumr caotenrsiatrlsu.ction wherein concrete is poured around an insulated steam pipe, If insulation is of a rigid type it can support the pipe; otherwise, the pipe should be supported independently. A space may be left around the pipe by Using insulation larger than the outside diameter of the pipe, the space helping to avoid crushing of insulation if the pipe tends to rise .when steam is admitted to a cold line. Conduit F is made of asbestos-cement pipe joined together with special couplings and enclosed in a protective concrete envelope. The steam pip is supported within the conduit on specially-designed slip-type supports wiCthosnadduditlessGwaelnddedHtoartehecolninsetr.ucted of specially-shaped, vitrified bell and spigot tile. Conduit G is also available in cast iron. This construction District Heating . 677; is intended for the support of excessive loads and to withstand shocks, such as are found beneath railroad tracks. Conduit I is of cast-iron construction with lead-caulked joints. It is watertight and intended for special applications. There are, in addition to those mentioned, several conduits which use an insulating concrete as pipe insulation. The insulating effect of the concrete is obtained through air cells formed by a special process or by a mixture of an insulating material with cement. An insulating hydrocarbon in granular form is available for trench fill around underground lines This material fuses to the lines with application of heat, forming a semi plastic, waterproof zone next to the pipe. ACCESSORY EQUIPMENT Provision should be made to take care of expansion and contraction of the piping in order to prevent stress in the pipe or fittings. Anchors can be special fittings or U-shaped steel straps which partially encircle the pipes, and are firmly bolted to a short length of cast or stainless steel set in con crete. . . , An expansion joint, offset, or bend should be placed at or between each two anchors. Advantage should be taken of the flexibility of piping to ab sorb expansion wherever feasible. Information on provisions for expansion will be found in Chapter 27. The section on Pipe Tunnels in this chapter contains further comment on expansion joints and anchors. Manholes for expansion joints should be kept free of water by proper drainage and should be of adequate size. Small manholes discourage proper main tenance. . Pipe lines should be of welded st.eel construction, flanges being used only to permit removal of equipment in accessible places. Piping should be properly supported and equipped with guides to prevent pipe deviation from a straight line between expansion devices. . A proper hydrostatic test should be made on the assembled line before the pipe welds and other joints are insulated. The hydrostatic test pres sure should be at least one and one-half times the maximum service pres sure, and it should be held for a period of at least two hours without evi dence of leakage. INSULATION Insulating materials constitute a primary element of district steam dis tribution structures and must be suitable for underground service. In sulation should be noncombustible, vermin-proof, moisture-resistant, durable, non corrosive to steel pipe when wet, and able to retain its position in relation to the pipe line without service maintenance. It should be relatively unaffected by such chemicals as are usually found in ground or other contaminated waters. It should have the lowest practical heat con ductivity consistent with the given requirements. Underground insula tion can be applied directly to the pipe or poured as a monolithic structure ui a suitable duct. Insulation is discussed further in Chapter 28. RETURN OF CONDENSATE If the condensate can be returned to the plant to be used for boiler feed water at an overall cost less than that required to process raw water, the installation of return, lines parallel to the steam supply lines should be given consideration. . Where steam and return piping are installed in the same conduit, the 678 CHAPTER 29 1956 Guide return piping usually follows the same grade as the steam piping. Return of condensate by gravity is desirable, but usually, the condensate is pumped back under pressure. ' In a heating system the pipes carrying condensate are more subject to corrosion than other parts of the system. Care must be taken to give proper pitch to the pipes and to provide proper venting of noncondensable gases. (See Chapter 43, Corrosion.) PIPE TUNNELS Because of their relatively high first cost as compared with smaller conduits, walking tunnels are usually not provided for steam mains in the district-heating industry unless they are required, to accommodate miscel laneous other services or to provide underground passage between build ings. However, in institutions a different approach may be justified. Many institutional buildings are expected to last several times longer than the fife of underground conduit. . Adequate maintenance programs are frequently harder to initiate and keep up in institutions than in industry. As an underground steam line approaches the end of its reasonable fife, traps, threaded connections, valve bonnets, gaskets, and expansion joints may require nearly continu ous maintenance. Without walking tunnels it might be impossible to maintain steam service. When institutional appropriations for steam- main replacement are involved, some institutions try to postpone construc tion of new buildings until sufficient funds for walking tunnel extensions are available. Tunnels are usually built of reinforced concrete or brick and are water proofed on the outside. Provision for drainage is essential. Repair work along main fines may be seriously hampered if tunnels are less than 4 ft wide by 6 ft high. Tunnels with sidewalks running over the top are ef fective in melting snow. Special precautions to reduce corrosion from ceiling condensation is in order where ceilings are close to grade. Tunnel piping is generally supported on racks at the side or sides of the tunnel or by ceiling hangers. Roller frames and insulation saddles may be used, or the fines may be placed directly on horizontal pipe supports. The latter construction may cause appreciable heat loss,, due to bare pipe at the supports. Special attention should be paid to the corrosive effect of moisture in tunnels. Steel pipe supports and anchors in contact with the floor are especially vulnerable. Pipe supports made of steel pipe may be welded (using proper welding rods) to short lengths of cast-iron pipe embedded in the tunnel floor. Dipping the lower portion of supports in a protective coating before installation is helpful. Concrete mounds around the pipe supports at the floor help to divert water from the support. Pockets for supports should not extend through floors, walls, or ceilings, as entry of ground water will reduce the fife of the support. Fewer expansion loops and more expansion joints are expected in tun nels. Possibility of superheat as well as the steam pressure must be con sidered in providing for pipe expansion. Extraction steam from a turbine may be supplemented at night by steam direct from high-pressure boilers, and consequently the steam may be superheated as it passes through reducing valves at the power plant. Unanticipated superheat may cause excessive expansion which may damage anchors and the distribution piping system. Desuperheaters may be required ahead of the distribution piping. Thermometers at critical points will be helpful. District Heating 679 . Spare expansion capacity in expansion joints may be desirable due to the following: . 1. Workmen may allow unexpected tolerances in cutting and welding of lines. ' 2. Due to seasonal conditions, the temperature of the line at time: of welding may not be at the .lower design temperature or the temperature of the line may not be uniform at time of welding". .. 3. Partial failure of reducing valves may cause line pressures to exceed the de sign pressure. . , . Pipe anchors should be designed for fine thrusts occurring with valves both open and closed. Liberal factors of safety for corrosion are desirable in sizing anchors. The tendency of anchors to slip along a pipe may be reduced by welding steel lugs to the pipe on either side of the anchor. The, lugs will bear against the anchor in case slippage of U-straps or U-bolts occurs. Branch' lines will exert side thrusts on mains and produce distortion of the main and misalignment of expansion joints near the branch. Good design can be achieved by locating anchors exactly at tees and at Ybranches. Unless anchor designs are specifically detailed, workmen tend to install anchors on one side of branch tees, thereby causing distortions that the anchor was supposed to avoid. Where branches do not coincide conveniently with fixed anchors, sliding anchors may be used to prevent distortion of the main and yet allow movement of the branch with move ment of the main. Special pipe guides may be necessary to prevent dis tortion of expansion joints. Expansion joints with both an anchor base and a branch service connection can be effectively used to eliminate troubles caused by branch line thrusts. Where excessive tunnel temperatures will reduce efficiency of mainte nance personnel, extra thick insulation may be desirable. For the same reason return lines in tunnels are insulated. For further comments on- insulation in tunnels see Chapter 28. ; : Electric,conduit for tunnel lighting may not last beyond the early life of the tunnel whether Exposed or embedded in the concrete. Knob and tube wiring and bare lamps may be more satisfactory. Extensive tunnel systems effectively use 220 volt lamps to offset line loss. Tunnel heat and high humidity may make tunnels uninhabitable for workmen when steam leaks must be serviced. Portable fans to blow air into one manhole and to pull it out of another may be essential. In addi tion, general ventilation obtained by a permanent fan, continuously,operat ing, may be necessary. Perforated'manhole covers located at ends of runs allow air to enter and sweep the tunnels. Doors across tunnels may be opened or closed to force extra ventilation air through that portion of a tunnel system where repair work is being done. . '. BUILDING PIPING AND EQUIPMENT There are certain fundamental principles that should be followed in the design of a building heating system which is to be supplied from district steam mains. Although some of these apply to any building, they have been demonstrated to be particularly important when district steam is used. : Most district heating companies enforce certain regulations regarding the consumer's installation, partly to safeguard their own interests, but prin cipally to insure satisfactory and economical service to the consumer. When an installation is designed, local regulations should be observed. 680 CHAPTER 29 1956 Guide Typical service connections are shown in Fig. 2 for low-pressure service and Fig. 3 for high-pressure service. The district-heating industry refers to valves according to their functional use. The pressure-reducing valve reduces pressure to a safe point, and the pressure-regulating valve regu lates pressures to that required by equipment served. Fig. 2 illustrates the use of a pressure-regulating valve with a bypass such as generally provided for larger installations. This bypass permits the operation of the system in case of failure in the pressure-regulating valve. In the smaller sizes, the bypass is usually omitted. When servicing is required, the pressure-regulating valve can be removed, a filler installed, and the gate valves (part 7 in Fig. 2) used to throttle the flow of steam until re pairs are made. 1. Service Pipe 2. Service Valve 3. Flanged Union 4. Globe Valve . 5. Ground Joint Union 3. Bypass 7. Gate Valve 8. Pressure*Regulating Valve . 9. Pressure Gage . 10. Balance Pipe to connect into steam main not lfsn tbftn 10 ft from pressure regulating valve Fig. 2. Pressure-Regulating Valve with Bypass' * From District Heating Handbook, Third Bdition. Fig. 3 shows a typical installation where the pressure in the districtsteam main exceeds 50 psig, which pressure is usually higher than can safely, be applied to building heating systems, as much heating equipment is not intended to withstand more than 15 psig!1 The first or pressurereducing valve effects the initial pressure reduction. The pressure regulating valve controls the steam at the desired pressure. It is often advisable to install a separate pressure-regulating valve for each steam use in the building such as for water heating, building heating, cooking, so that each system may operate at the optimum pressure. Pressure-reducing valves are more fully described in Chapter 21. For use with, district heating, dead-end type valves of the pilot-operated or spring-loaded type are generally preferred where applicable. Pressure regulating valves should be sized to supply adequately the maximum steam requirements of the heating system or equipment. This is especially in portant with temperature control systems using intermittent flow of steam District Heating 681 1. Service Pipe ` 2. Service Valve 3. Strainer 4. Flanged Union 5. Gate Valve ?! . . Valve PLAN VIEW 8. Pressure Gage 9. FUot-Operated Pressure-Reducing Valve 10. Pressure Relief Valve (optional 11. vent 12. Globe Valve 13. Bypass Line Note: AU fittings should be American Standard Claes 250 cast iron. Fig. 3. Two-Stage Pressure-Reducing and Pressure-Regulating ...__ .__ Equipment* (JJsed Where High-Pressure Steam is Supplied for Low-Pressure Requirements). * From District Beating Handbook, Third Bdition. to heat the building. Pressure-regulating valve capacity recommended for use with various types of temperature control are shown in Table 4. ZONING AND OPERATION Zoning. Where the hours of occupancy or heating loads differ in various sections of the building, it is good practice to install separate supply lines to the different sections. For example, in an office building with stores or restaurants on the first floor which are open'in the evening, a separate main supplying the first floor will permit the steam to be shut off from the remainder of the building in the late afternoon. The division of the build ing into zones, each with a separately-controlled heat supply, is sometimes desirable, as it permits the heat to be adjusted according to variations in sunshine and wind. Fig. 4 shows a typical service installation with a separate line to the Table 4. Suggested Capacity OF PRESSURE-REGULATING VALVES AND Traps Type op Control . ^ teot?with on operation. intermit- witti on penoda over 3 hr in duration InberrifdHtt^mtioa Wilh M peTiods of H to 3 Intonuttent operation with on periods of H hr or Pressdbe-Regulatinq Valve Capacity, Lb/(Hb) (Sq Ft op Radiation*) Tbap Capacity, Lb/(Hb) (Sq Ft op Pipe and Radiation*) H; - ' M H H Hb h Square Feet EEjDURIV.. . <*Pi for drip traps on mains which should be lib per sq It EDR. 682 CHAPTER 29 1956 Guide F ,ig 4. Steam Supply Installation with Header fob Process and ;. Zone Connections various heating zones and process equipment. If initial pressure is below 50 psi the first stage pressure-reducing valve may be omitted. . Heal supply should be graduated according to variations in the outside tem perature. The maximum in economical operation and satisfactory heating can only be obtained by the use of automatic temperature control (see Chapter 39). : ." Rapid draining and venting of the heating system should be obtained by means of suitable traps and air vents in order to obtain rapid, circulation j and quick heating. This is particularly important with intermittent-type ' temperature-control equipment. The selection of traps is discussed in Chapter 21. Suggested trap capacities are given in Table 4. Provision should be made for conveniently shutting off the steam supply at night and at other times when heat is not needed. A considerable amount of : heat can be saved by shutting off steam at night and other times when optimum building temperatures are not required. It is necessary, how ever, to have an ample amount of heating surface in order- that the build ing may be quickly warmed after such turn-off periods. Residual heat in the condensate should be salvaged. This heat may be salvaged by means of an air-cooling coil, or as is more frequently done, by a District Heating 683 water-heating economizer, shown in Fig. 5, which preheats the hot water supply to the building. The condensate from the heating system, after leaving the traps, passes through the economizer. The water supply to the heater passes through the economizer, absorbing heat from the condensate. If the. hot-water system in the building is of the recirculating type, the recirculating line should be connected between the economizer and the water heater proper, not at the economizer inlet, because the recirculated hot water is itself at a high temperature. - Since the heating-system load and the hot-water demand are not coinci dent a greater amount of heat can be extracted from, the condensate if storage capacity is provided for the preheated water. Frequently, there fore, the economizer coils are submerged in the storage tank. METERING Meters are classified into two groups: Condensate Meters and Flow Meters. The Condensate Meter is a popular type for use where all the condensate can be brought to a common point for metering purposes. Its simplicity 684 CHAPTER 29 1956 Guide of design, ease in testing, accuracy at all loads, low cost, and adaptability to low pressure distribution have made it standard equipment with many heating companies. . Condensate meters should not be operated under pressure; they. are made for either, gravity or vacuum installations, Typical meter installa tions are shown in Fig. 6. In diagram A a continuous-flow type trap is shown installed ahead of the meter, while in diagram B an intermittent type trap is used. In the latter case, a receiving tank must be placed be tween the trap and meter to prevent intermittent overloading of the meter. When measuring the discharge from a vacuum pump, a vented receiver should always be installed ahead of the meter. Installations of meters in a vacuum return line are shown in diagrams C and D. In diagram C a master, float-type, continuous-flow trap is installed immediately ahead of the meter to prevent steam from entering it in case of leaking radiator or fixture traps. Where individual traps are reliable,! connections may be made as shown in diagram D. Flow Meters used for district heating work are of'three types: Area Meiers, Head Meters and Velocity Meiers Meters are described m Chap ter 4, Fluid Flow. Flow meters are generally used for measuring send- out from plants, high-pressure requirements in buildings, and in installa tions where all of the condensate cannot be returned to a central point. Further information on flow meters is available in the District Healing Handbook and from publications of the Fluid Meter committee of the American Society of Mechanical Engineers. , REFERENCES . American Standard Code for Pressure-Piping, ASA B31.1-1955 (American Standards Association). S * District Heating Handbook, Third Edition, 1951, p. 329 (National District Heat ing Association). : . , 3 Graphical Solution of Unwin's Formula (a chart published by National District Heating Association). CHAPTER 30 CENTRAL SYSTEMS FOR AIR CONDITIONING Features of Systems, Zoning, Humidity Control, Cooling Load, Heating Load, Air Quantity and Temperature Differential, Unitary-Central "Systems, Low- and " High-Pressure Induction Convectors, Dual-Duct Systems, Fan and Coil Units, Evaporative, Cooling,- Precooling, Sensible Cooling with Un wetted Coils, Selection of Type of System, Location of Apparatus THE term, central, applied to an air conditioning system implies that the; equipment such as fans, coils, filters and their encasement are designed for assembly in the field rather than in a factory as a unit. As a central system usually serves several different rooms, or spaces ^indi vidual controls! are required, for. each room. i ; FEATURES OF CENTRAL SYSTEMS One advantage .of a; central air supply system is that one apparatus serving many rooms may involve a lower investment cost than that for a number of self-contained plants, each serving a single room. A central system may occupy basement or attic space that is relatively unimportant, whereas individual factory-assembled apparatus placed in each room may occupy otherwise valuable space. Another advantage of a central system is accessibility for servicing, since it is possible to provide doors in, the encasement for cleaning and inspecting all of the component parts in a manner usually superior to that practicable with compact factory- assembled equipment. In addition service is concentrated in one or just a few places. . . ........... Central air conditioning systems usually are. connected-by ducts with the various rooms served, and preferably have exhaust fans that may effect complete removal and disposal of any desired proportion of the air. The return-air fan may return air to the supply system for recirculation, as a measure of economy of fuel or refrigeration. ,,' Central air conditioning systems are served by heating and refrigerat ing equipment which 'may be located at some distance from the air supply apparatus, and which may serve one or more central air supply: systems. Fig. 1 is a sketch of a typical year-round central system. 1 Outdoor air enters from an intake preferably on that side of the building least exposed to solar heat, and not close to the ground.or to a sun-heated or dust-gathermg roof. The outdoor-air damper, is split into two sections, minimum outdoor-air and maximum outdoor-air, with the maximum outdoor-air damper interlocked with the return-air damper in such a manner that as the outdoor-air volume increases the return-air volume decreases. The return air duct or connection could- come from a return-air fan. All the air passes through filters which must have ample room on both sides of the filters for servicing. The filters may be of a mechanically-cleaned type, a replaceable cell type, or may be electronic as described in Chapter 34. The cleaned air passes to the equipment that changes its temperature 685 686 CHAPTER 30 1956 Guide and humidity. Except in very warm climates, heating or tempering coils are required to warm the entering outdoor air to a' temperature above freezing, the heat being supplied by means of hot water or steam. Cooling coils provide the necessary sensible cooling and dehumidification. The coils may be chilled by direct expansion of an approved refrigerant within the tubes, or by a pump-circulated liquid such as water or brine. A water tight drainage tank must be installed under the cooling coil and should extend for a distance toward the fan. -. Reheater coils utilizing steam or hot water reheat the air in warm weather for control purposes or bring the air to its final temperature in cold weather. For humidification in dry weather, water sprays are used either separately as shown or combined with the cooling coils having the spray nozzles directed against the coil surfaces. The spray water may be circulated by a small pump from the water tank under the spray chamber. The general requirements for the control of the various components of the central station apparatus are covered in Chapter 39. The functioning of a typical set of controls as illustrated in Fig. l is as follows: Whenever .the fan is started, solenoid air valve or relay E-l, actuated by the fan motor starter, opens minimum outdoor-air damper D-1, places humidistat H in ser vice, and allows duct thermostats T-3 and T-4 to control the maximum outdoor-air damper D-2 and the return-air damper D-3. . When the fans stop, E-l is de-energized to close the outdoor-air dampers and also to close humidifier valve V-4. .. Thermostat T-l positions steam valve V-3, on the reheater coil, to maintain a constant space temperature. As the space temperature rises, T-l positions reheater, valve V-3 to a closed or to a minimum open position, as determined by low limit discharge thermostat T-5. Duct thermostat T-6, in the preheater discharge, posi tions preheater coil valve V-l to maintain a constant preheater discharge tempera- On rising outdoor temperature, between 30 F and 65 F, duct thermostat T-3 located in the outdoor-air intake, moves maximum outdoor-air damper D-2 toward the open position provided that T-l is satisfied. At 65 F outdoor, D-2 will be fully open and return-air damper D-3 will be fully closed. .. As the outdoor-air temperature rises above 65 F, duct thermostat T-3 positions V-5 in such a way as to by-pass low "limit thermostat T-5, so that reheater coil .valve Central Systems for Air Conditioning 687 V-3 is operated directly from thermostat T-l. As outdoor-air temperature" rises from 65.F to 75 F, duct thermostat T^4 gradually closes maximum outdoor-air damper D-2 and opens return-air damper D-3. ; . ,. ............... Cooling thermostat T:2 positions cooling coil valve V-2 to admit more chilled water as the space temperature rises.: . . . .. :i Humidistat H positions humidifier valve V-4 to maintain the desired humidity in the conditioned space. "- - ZONING AND ZONE CONTROL It is apparent that while an apparatus like that of Fig. 1 would be very desirable for any single room, since in that case the air could be delivered at optimum conditions, the cost of a complete individual system for each- room and the space required for the equipment generally would be pro hibitive. Economy is favored if the varying requirements of numerous rooms or zones can be simultaneously satisfied by air from a single central supply system. . .. - ': Various methods are practicable for controlling the temperature, hu midity and air movement in various rooms or zones. A measure of con trol is attainable merely by proportioning the flow of air to each room, though, usually such control by throttling dampers is difficult to maintain and should be avoided when possible. Another scheme is to install a properly proportioned coil in the branch air supply duct serving each room or zone to warm the air to suit the occu pants. For example, the air leaving the fan that serves several zones may be cooled, before entering the fan, to the condition favorable for one zone, and the air for each other zone may be reheated by the branch duct coil to the required temperature. It is also possible to circulate a heat absorbing medium in the branch duct coils to reduce the temperature of the air passing to rooms that would be overheated if they received air at the condition leaving the central air supply system. When heat transfer devices are placed in branch ducts for improved temperature control, me chanically circulated water gives excellent results as a heat carrier. The water usually is warmer than the air but it is possible to use water colder than the air. It is practicable also to use. single central air conditioning equipment similar to that shown in Fig. 1, in conjunction with several fans, one for each room or zone. In such cases there may be a separate reheater on the suction side of each relatively small supply fan. The designer must remember that the various supply fans will compete with each other for air, against the resistance interposed by the filters, coils, etc., that are used in common under such circumstances, and con sequently, unless the fans are of backward-curved blade, non-overloading type, they may alternate in carrying more than their share of the air, and thereby cause the air distribution to be chaotic and unsatisfactory. Another method of controlling temperature in various rooms served by a central air supply system is shown in the sectional elevation, Fig. 2. the supply fan is placed immediately after the humidifier. When cooling the air in hot weather, the humidifier is not operated. The fan will deliver the air through the heating coil and through the cooling coil to the two air pressure chambers A and B at the right of these coils. From these chambers many separate ducts, one of which is shown, each with a double-blade mixing damper, may. convey the air to the various, rooms, the mixing dampers, one of which is shown, are interlocked so that as the upper one closes, the lower one opens; selecting between them, air in the required quantity from either the warmer chamber A or the cooler'one B; 688 CHAPTER 30 1956 Guide In cold weather no refrigerant is required in the cooling coil, and in hot weather no heating medium is circulated in the heating coil. With this scheme, the control of relative humidity in warm,weather is not always sufficiently precise to meet requirements, since theuntreated,air delivered through the upper coil may be so high in relative humidity that it cannot sufficiently compensate for the nearly saturated air leaving the lower coil. A reheater could be placed if desired, to the right of the lower coil to bring the air in the lower chamber to the desired relative humidity. The simple arrangement of Fig. 2 is admirable in winter and, except where close control of relative humidity is important, may be acceptable in summer. . Another method of attaining temperature control in individual rooms with a year-round central air supply system, is to install a booster fan between the main air supply duct and the air delivery opening to each zone or room, as shown in Fig. 3. Air can then be delivered, from the Central Systems for Air Conditioning 689 same volume of air is handled as in summer. With a spray type dehu midifier the main sprays may be shut off and only the eliminators need be flooded; which may give sufficient moisture. In other cases, such as those in which cooling coils are sprayed, the spray water supply may be throttled. If the saturation efficiency of the .sprays is too low, the spray Water may be heated. The amount of heat put into the spray water by open or closed water heaters will be equal to that required to .bring the dew-point temperature of the air entering the sprays up to that required before entering the preheater. It is possible, where clean steam is available, to introduce steam directly into the air stream to produce the desired dew point temperature of supply air. However, the steam must be exception ally clean, or objectionable odors will result. It should be noted that the quantity of outdoor air to be introduced is affected by infiltration and leakage. Infiltration will reduce the quantity Pig. 2. Alternate Arrangement of Equipment fob Contbolling Aib Condition in Central Aib Supply System central supply fan through the main duct at some desired condition, for instance, 60 F, 45 percent relative humidity. A double mixing damper near the intake opening of the booster fan, controlled by a thermostat in the room or zone that is served by the fan, is interlocked with an outlet exhaust damper in the spent air opening, so that as more of the room air is recirculated, and as less new air from the main air supply duct is de livered into the room, the spent air outlet is throttled in proportion. In many large installations this principle is applied successfully for zoning different stories in multi-story office buildings, the main supply fan being on the roof, and each booster fan used for supplying the rooms of one orientation of each story. In other cases the booster fans serve only single offices, and therefore are small enough to be concealed above ceilings along side the main supply duct. There may be installations in which the use of recirculated air for mixing with new refrigerated and nearly saturated air to control temperature and relative humidity is objectionable. In such cases the general recircu lation arrangements of Fig. 1 may be omitted, and heat transfer coils located in the ducts may be used. In some cases where general recircu lation is not acceptable, as for all the rooms in an entire building, use of the local circulation of Fig. 3 iriay solve the problem. HUMIDITY CONTROL In winter, room relative humidities in excess of 30 percent are seldom required in a system designed for comfort conditioning only, and a 1ow saturating efficiency may be desirable, or even necessary, especially if the Fig. 3. Arrangement fob Individual Room Temperature Control, with ACentral ib Supply System to be introduced by the system, while leakage may have to be offset by an increase in the quantity of outdoor air. COOLING LOAD The method of determining the cooling load for a conditioned space or spaces is outlined in Chapter 13. As pointed out therein, many of the items of heat gain are variable and do not reach their maximum values simultaneously. Proper consideration of these peaks and the avoidance 9f pyramiding these peaks in the cooling load calculations are stressed. Maximum solar heat gain on an east exposure is seldom coincident with the maximum outdoor wet-bulb temperature. A large difference in the time-incidence of the peaks between various spaces or parts of the same space indicates the necessity for zoning. In a building having an east and west exposure, where solar heat gains forms a fair share of the cooling load, the times of individual zone peaks are apt to be some hours apart, and the peak load of one plus the off-peak load of the other will be substantially less than their combined peak loads. Proper zoning will permit operation to take full advantage of this condi tion or of similar conditions of non-simultaneous peaks, and will result m a lower total load and in saving? in equipment. A factor similar in effect and closely related to the non-simultaneous occurrence of peak loads, is diversity. Typical of this is the case of a 690 CHAPTER 30 1956 Guide large department store where the air handling equipment serving a certain Space must be sufficient to handle the load created by the throngs of 'people attending Sales in that space. Under such a condition the number -of people in other spaces is usually normal or below. While this means 'that the air handling'equipment for certain departments must be large enough to cope with the situation, the refrigeration equipment need be only large enough to handle the average maximum. If a system employ ing zone recirculating fans and a single central fan and dehumidifier were used, the saving would be reflected ini the capacity of the central fan and dehumidifier. Another example of this diversity is found in an office building having restaurants and stores of certain types in the first story and basement. At noon, when the restaurants and stores are crowded, the offices are below normal occupancy. , . Heat lag should be carefully considered in the cooling load calculations. In certain types of buildings the effect of solar radiation is still apparent several hoars after the sun has shifted from that exposure. In other types having a much lighter construction, the heat gain due to solar radiation decreases markedly with the passing of the sun. Some walls warmed by the sun, may radiate heat long after the passing of the sun, thus requiring lower inside temperatures to offset the radiant energy. Buildings have considerable heat storage capacity which can often be utilized to great advantage, and which has more than once provided an. unexpected safety factor. If a space is kept below the design inside tem perature for some time, the interior walls, floors, furniture and fixtures begin to assume the temperature of the space. Where the time is suf ficient the entire mass, rather than merely its surface, may reach the room temperature. Thus, when a space has been precooled below the design maximum temperature for a period of time prior to the advent of the peak load, and the heat gain begins to increase to peak conditions, some of the increase is used in raising the temperature of the furniture, fixtures, etc., to the design conditions and the cooling load can be reduced accord ingly. However, unless very accurate data with regard to the mass, sur face, specific heat, etc., of the items within the space are available, due caution must be used in discounting the cooling load for this storage effect. In the absence of reliable data this allowance is often a matter of experience rather than calculation., ., Where air conditioning supply and return ducts pass through uncon ditioned spaces, there will be a transfer of heat from these spaces to the air in the ducts, even though these ducts are well insulated. An allow ance should be made for this heat gain and included in the heat estimate so that air can be supplied at a temperature low enough to offset the rise caused by this heat gain (see Chapter 32). There will also be some heat gain to the air in ducts passing through conditioned spaces, but since a cooling effect is produced in the space through which the duct passes, this is not a loss and usually can be compensated for by adjustment of air quantities between the various spaces. HEATING LOAD Methods of calculating the heating load are shown in Chapter 12. Many of the factors outlined previously under Cooling Load, such as zoning, non-simultaneous peaks, and diversity, apply in.the reverse man ner due to the heating requirements instead of the cooling requirements. However, these factors affect the heating load from the standpoint of control of inside conditions, overall performance, and economy of opera Central Systems for Air Conditioning 691 tion more than from a capacity of equipment standpoint. It is not only necessary to heat; a building or space to its design conditions when there is but the merest fraction of normal occupancy, and when there are prac tically no lights, internal heat, or solar radiation, but it is also necessary to provide capacity to heat the building quickly when sudden cold follows relatively warm weather, as may occur after a week-end or holiday shut down. However, in normal operation during week-ends and holidays, buildings Eire usually kept at a holding temperature to prevent the freezing of services. In many cases, less fuel is required to operate the heat ing plant at a near-normal rate and maintain the building or space at a temperature of 50 to 65 F at such times, than to shut the system down and then bring the temperature back to normal through forced operation of the heat-generating equipment with a consequent loss in efficiency. AIR QUANTITY AND TEMPERATURE DIFFERENTIAL The difference between the room-air temperature and the supply-air temperature at the outlet to the room is known as the temperature dif ferential. In the theoretical case of a dehumidifier having 100 percent saturating efficiency, and where this air is delivered directly to the room without temperature increases due to heat gain, then the temperature differential is the difference between room temperature arid apparatus dew point temperature. If duct heat gains are considered a part of the room load, this still holds true. The apparatus dew point, as outlined pre viously, is fixed by the latent and sensible loads of the space, but in many cases, it is desirable to deliver more air to the spaces than is indicated by the difference between the room temperature and the apparatus dew point. It has been indicated that where a percentage of air is passed through the dehumidifier without being treated, the relationship is modified in direct proportion, and that if room air is passed through untreated, no effect on the heat balance results. Similarly, if room air is passed around the dehumidifier and mixed with the treated air, the heat balance is not adversely affected. Therefore, if the quantity of air passed through the dehumidifier is determined by the usual methods, room air can be passed around the dehumidifier and mixed with the dehumidified air, increasing the supply air quantity and temperature and decreasing the temperature differential. Thus if the difference between the room temperature and the apparatus dew point indicates that 10,000 cfm at 30 deg below room temperature will be required to hold conditions, that quantity can be passed through the dehumidifier and cooled to 30 deg below the room tem perature, then mixed with 10,000 cfm of room air, resulting in a supply-air quantity of 20,000 cfm and a temperature differential of 15 deg instead of 30 deg. Air supply outlets and grilles having a high induction ratio are available, and through their induction effect cause a large amount of room air to be mixed with the supply air within a short distance of the grille. A proper selection of outlets may make it possible to introduce air at low temperatures and high velocities without causing objectionable drafts or cold spots, but care must be used to see that too little air motion is not a result. Low temperature differentials may be required for this reason. While the use of a high temperature differential results in a saving in initial cost of fans arid ducts, and in the Operating cost of fans, this differential should be carefully considered. If the sensible heat load of .a space is sub jected to substantial variations, low temperature differentials should be considered, since systems employing low temperature differentials require less precision in controls. Reduction of air quantity by Blowing down the fans for the winter season, 692 CHAPTER 30 ~ 1956 Guide ' and increasing the temperature differential, often is feasible. A saving in fan-power can thus be effected, provided the air distribution remains ade quate.^- -- i == Extremes should be avoided in all cases. For primmer air conditioning, low supply-air temperatures result in larger heat gains to the air passing through" the ducts, as well as in poor control. Too high a supply-air tem perature may result in excessive initial and operating costs. Suggested Umits for`the temperature differential are from 12 to 25 deg, the actual selection being based on the requirements of the particular case. For winter air conditioning, too high supply-air temperatures result in excessive heat losses from the ducts and stratification within the room unless thorough mixing is assured, while too low supply-air temperatures may cause drafts, high operating costs, etc. Suggested limits are from 15 to 35 deg. There can be no set rule, and each case should bejudged according to its particular . requirements of the installation. : Reference may be made to Chapter 31 for further discussion of the most satisfactory design difference between the entering air temperature and volume in relation to the desired room condition. UNITARY-CENTRAL SYSTEMS Many different types of units have been developed for use in central systems where a high degree of zoning or individual room control is required, such as in hotels, hospitals and office buildings. These types of buildings are further characterized as usually having a larger1 perimeter relative to the floor area. The units usually are installed beneath the windows. Where the spaces to be conditioned extend a considerable distance from the outer wall into the interior of the building, such as might be found in office buildings, a separate system or zone for the conditioning of the interior portions may be required: In these cases the interior system handles the relatively small and steady loads, due to such items as fights and people; whereas the exterior system must cope with the relatively large and variable loads imposed by sunshine and temperature difference through walls and glass. Descriptions of four common unitary-central systems follow. Induction Convectors--Low Pressure Type Induction convectors located in the. room that is to be served, utilize a jet of primary conditioned air to mix with a stream of secondary room air as shown in Fig. 4., The mixture is discharged into the room through a grille at the top of the convector. Heating coils are located in the second ary air stream. The output is controlled either by manually or auto matically throttling the air jet. Heat may be supplied to the coil in summer as well as in winter. These induction convectors present several advantages. Since the secondary air stream is thoroughly mixed with the high velocity low temperature air stream before leaving the discharge outlet of the device, the resultant temperature of the mixture is satis factory even though the primary air is introduced at a temperature too low for ordinary methods of distribution. One of these devices usually is provided under each window in place of the customary direct radiator, 'and combines the air distribution system with the heating system. An air conditioning system without induction convectors may require in stallation of direct radiation for maintenance of minimum temperatures during air conditioning shut-down periods, but when induction convectors are used they may be selected with heating coils of sufficient capacity to maintain, by thermal circulation, a reasonable temperature when the pn- Central Systems for Air Conditioning 693 mary-air supply system is shut off. The use of low temperature, dehumidi fied air which has not been reheated or mixed with room air before delivery to the room, may permit a reduction in fan capacity and the use of smaller ducts. In some cases a bypass may be desirable in order to maintain the primary air volume and to provide additional control. This system can provide a degree of zoning that is usually difficult with conventional design since the air delivered by each unit can be controlled individually. Selection of induction convectors should be made with due regard to noise level. The inductive capacity of the device increases with the jet velocity, but high jet velocities may result in objectionable noise. . The units are supplied with primary air from one or more central stations with the primary air providing all ventilation and handling the entire cooling load. The central apparatus is arranged in general conformity to Fig: 4. Induction Unit (Low Pressure Type) Fig. 5. Induction Unit (High Pressure Type) . Fig. 1 except that the central reheater is omitted since each unit has its own reheater. The controls are arranged to maintain a substantially con stant supply air temperature equal to that required for maximum cooling. Final control is obtained by means of a room thermostat, or remote bulb thermostat in the unit having its measuring element in the recirculated air stream. The controlling thermostat operates the coil supply valye and a damper operator on the primary air damper in sequence. At maximum heating load the valve is wide open and the primary air quantity is at a minimum. As the space temperature tends to rise, the valve is first grad ually closed, then the primary-air quantity is gradually increased from minimum to maximum. Alternately the primary-air quantity can be Kept constant and all final control achieved by the individual heating coils, i variable air quantities are to be handled by the primary-air fan, some term of fan-capacity control is necessary. Induction Convectors--High Pressure Type : . Another type of induction convector, Fig. 5, employs nozzles which Produce a high velocity air jet without objectionable noise. The term, igh pressure, is to some extent inaccurate, since the air pressure at the ozzles, while several times that used with a low pressure induction eonector, is still less than the total resistance pressure of a conventional entral system. The high velocity jet of primary air induces a flow of air om Ihe room through coils located in the secondary air stream and - ttS 694 CHAPTER 30 1956 Guide supplied- with chilled water in summer and with hot water in winter. The chilled water removes a large portion of the sensible heat in summer and the hot water supplies the sensible heat loss in winter. The primary air is delivered at a sufficiently low dew point to compensate for the latent heat gain in summer; In winter the primary air is supplied at a sufficiently high dew point to take care of latent heat losses. Control of temperature is obtained by throttling the water quantity supplied to the secondary coil. The required flow of primary air is greatly reduced due to the fact that a portion of-the sensible heat load is carried by the second ary air stream. Since the primary quantity is small, very high velocities can be maintained in the supply ducts without requiring fan power in excess of that for a conventional.system. Therefore, the supply ducts or pipes can be very small and can be run in chases, or furred in at columns Central Systems for Air Conditioning' .-.v - ' 695 below~80 F thermostat T3 regulates reheater valve V2 so that warm primary air is supplied at the same time that cold secondary water is fed to the units. The change over from heating to cooling is usually manual and the exact time is not too important because both heating and cooling are available in either case. During the cooling cycle, thermostat T7 actingthrough thermostat T3 readj usts theprimary air tempera ture downward as the outdoor air temperature increases from the changeover point to about 80 F so that above this temperature the primary air is equal to the apparatus dew point. In some buildings the primary air system and water circuits are zoned according to exposure, but because both heating and cooling are available at the units whenever either is needed, such zoning is not always used. Dual-Duct System The dual-duct system conditions all the air in a central apparatus and distributes it to the conditioned areas through two parallel mains .or dual along with the water pipes. The primary air is treated in the usual man ner to reach the required dew point and a surface or spray dehumidifier or a dehydrator may be used. The primary-air quantity is sufficient for ventilation purposes and frequently consists entirely of outdoor air. Fig. 6 shows the general arrangement and control of the system. The operation of the controls is as follows: The final temperatures in the spaces are controlled by individual valves, either automatic or manual, which throttle the flow of secondary water to the unit coils. Where automatic valves are used, the thermostats are of the heating-cooling type so that a rise in room temperature opens the valve when cold water is circulated and closes the valve when hot water is being supplied. Thermostat T1 controls the pre heater steam valve VI to maintain a temperature of about 45 F leaving the preheater. Thermostat T2 controls the maximum outdoor-air and return-air dampers so that the air entering the dehumidifier is maintained at 50 F whenever outdoor air condi tionDsuprienrgmtiht.e heating cycle, thermostat T3 and valve V2 are inoperative so th.at cool primary air is supplied to the units but at the same time thermostat T6 operates valve V4 so that the secondary water is heated. Thus the combination of cool pn_ mary air and hot secondary water can provide heating or cooling as required. The priWmhaeryn pthuempouatnddoowraateirr icsonoolerloanrgeeinr ospueitraabtlievet.o provide sufficient cooling through the primary air system (typically about 50 F) the system is changed from heating to cooling operation. The primary pump is started and supplies chilled water to the dehumidifier. Thermostat T4 controls mixing valve V3 so as to maintain the sec ondary water at temperatures in the range of 50 to 55 F. At outdoor temperatures Fig. 7. Schematic Abbangement ob Dual Duct System ducts. The air supply fan, return-air fan, filters, heating and cooling means, outdoor-air equipment, dampers, and controls are located in the apparatus space. One air distribution main carries cold air while the other carries warm air at approximately room temperature in summer and at a higher temperature in winter. ' The general arrangement of a typical dual-duct system is shown in Fig. 7. In some arrangements, two supply-air fans are used with one fan supplying the cold-air duct and the other the hot-air duct. The warm-air fan handles only recirculated air so that operating economy is slightly improved. The maximum outdoor-air damper and the preheater are controlled as in pig- 1 so that when the temperature of the outdoor air is favorable it is used increasingly instead of return air. The warm-air supply-duet temperature is controlled by a thermostat, t2, Pig. 7j }n the air leaving the heating coil. Thermostat T2 is reset by thermostat T1 in accordance with variations in outdoor-air temperature. Whenever outdoor-air temperature is not low enough to accomplish the required cooling, the cold-air supply-duet temperature is regulated by the pooling coil. The final temperature in the conditioned areas is controlled by the individual air-mixing units. Air-mixing room units under control of the room thermostat draw warm d cold air from the ducts in accordance with the room requirements, affording individual room control without zoning. Fig. 8 shows schematicajly one type of room unit designed for dual-duct systems: The warm and cold air pass through the three-way mixing damper which, delivers air at- 696 CHAPTER 30 1956 Guide the temperature required by the room. Some units are placed under win dows, while others are mounted in the ceilings from which air may be delivered to the room through ceiling, wall, or window outlets. Some units are also provided with volume regulators to maintain a steady flow condition. -' This system is best suited for multi-room or multi-zone installations, and may be of either high- or low-velocity and high- or low-pressure type with substantially the same control methods. It is often applied to highvelocity systems with long distribution mains, and consequently highstatic fan pressures; although extremely high static pressures are seldom justified. With two supply mains, the system static pressures vary as a result of changing demands for heating or cooling. Thus volume regula tion often becomes necessary. Extreme variations of flow to different Fig. 8. Room Aib-Mixing Unit fob Dual Duct System rooms may be somewhat limited by static-pressure regulators and volume/ dampers at selected points along the mains. There are some installations where volume control at each room supply is desirable to maintain close, control regardless of static-pressure changes in the ducts, and incidentally to facilitate balancing of the distribution system. . , Air-capacity requirements are generally governed by summer cooling loads, and general practice is to supply the cold air to the cold-air duct at 25 to 30 deg below the established room temperature, this being satis factory with suitably designed room outlets. Fan and Coil Units Another type of room convector used in connection with central cooling and heating plants is known as the Fan and Coil Unit (see Fig. 5, Chapter 26). . These units, like induction units, are located around the periphery of a building, usually under windows, and are equipped with fans and a watertype heating-cooling coil. They normally take air for ventilation directly from outdoors, and have a manual damper for adjusting the quantity <rf outdoor air within certain limits. Positive closing of this damper when the fan stops, can be obtained by adding a damper operator actuated by the fan-motor switch. Hot water supplied during the heating season fre quently is varied in accordance with outdoor temperature. Cold water for'use during the cooling season should.be supplied at a fixed temperature low enough to provide the proper amount of dehumidification. ' Central Systems for Air Conditioning 697 These units sometimes are used with a primary-air system which supplies the outdoor ventilation air and handles the latent load. In such cases the primary air unit is controlled as explained under the section Unitary-Cen tral Systems, and may be of either the low- or high-pressure type. The combined heating-cooling coil of each unit may be controlled by a valve in the water supply line to each unit, actuated by a thermostat in the room or recirculated air of the unit. The thermostat is of the heating cooling type. EVAPORATIVE COOLING In climates where, on the hottest days, the outdoor wet-bulb depression is relatively great, it may be posible to replace mechanical refrigeration, or other cooling sources, and use the evaporative cooling effect. A welldesigned air washer using recirculating sprays will reduce the entering drybulb temperature to within a degree or two of the entering wet-bulb condi tion. Thus, it may be possible that, with air entering at 100 F dry-bulb, 60 F wet-bulb, a leaving condition of 62 F dry-bulb, nearly saturated, can be obtained. Under some conditions of latent and sensible heat load, this evaporative cooling may be adequate. At times when the outdoor wet-bulb temperature is not low enough to permit the use of straight evaporative cooling, it is still possible to use pre-cooling convectors with refrigeration, well water, or a cooling tower, as the basic source of sensible heat removal to reduce the wet-bulb tempera ture of the air before it enters the spray chamber. Where internal heat loads are high, this scheme may be more economical than one using return air. Where the required supply air dew point is too low to permit straight evaporative cooling, and Where the sensible heat load is not too great, intentional partial saturation may be employed. That is, the low dew point of the outdoor air is utilized by permitting some of this air to pass through the humidifying sprays untreated, or to bypass the humidifier. All of these remarks with regard to evaporative cooling are based on the assumption that all of the supply air will be taken from outside. Provision should be made in most cases for the return of some air from the conditioned spaces for control purposes, as well as for economy of fuel in winter. PRECOOLING Where sufficiently cold water from wells or streams is available, a saving in refrigeration may be obtained by the use, in location ahead of the de humidifier, of precooling coils through which the cold water is circulated. The resultant cooling of the air decreases the load to be carried by the dehumidifier and refrigeration plant. In normal practice the water, after passing through the precooling coils, may be further utilized in the refrig eration plant condenser. The economic advantages of this scheme are apparent, and it is frequently used. SENSIBLE COOLING WITH UNWETTED COILS . Under favorable atmospheric conditions where a large wet-bulb depres sion exists and the dew point of the outdoor air is sufficiently low at all times, acceptable cooling may be obtained by removing only the sensible heat from the outdoor air delivered to the rooms. Under this condition " a great wet-bulb depression, a temperature-reducing coil may be located in the air stream and supplied with water from a cooling tower. When humidity control is desired, sprays to saturate or partially saturate the air may be used down stream from the unwetted coil. Saturation or partial 698 CHAPTER 30 1956 Guide saturation after: the coil will reduce further the dry-bulb temperature and the air quantity required. This system has= very definite application in hot dry. climates. . SELECTION OF TYPE OF SYSTEM If the perimeter of the building is large with regard to the area, and if there are many rooms, induction convectors of either the low-or high-pres sure type may be employed. Occasionally a dual-duct system, oneductcarrying air at a warmer temperature than the other, may be considered. Low buildings with large floor areas may be divided into sections or zones with separate, central air-supply systems to facilitate temperature control. In the case of large department stores it may be possible to pro vide a single conditioner, with a fan delivering the conditioned air to local mixing fans which supply the various departments or spaces. This appli cation is limited , by the practicability of running the large conditioned air ducts to the various recirculating fans. Each vertical section of the building also may be supplied by a separate fan delivering conditioned air to local mixing fans. In many cases the most economical and satisfactory scheme may be to employ a hot-water or steam reheater in each branch duct. Where vertical sectionalizing is not indicated, the building may be divided into horizontal groups, each handled by a central system and ade quately zoned. In some large buildings, apparatus rooms for the systems may be located in the basement and attic and on intermediate floors. In high buildings the necessity for horizontal sectionalizing may be suggested by the size of air supply and return risers, and by the extent, to which they encroach upon usable space. Each story should be cut off by doors from other stories, as otherwise the cool air tends to collect in the lower story and the warm air is forced to the upper story. : Balconies and large lobbies in theatres and similar high rooms frequently justify the use of separate zoning fans, to counteract the tendency of. the heavier, cooler air to collect at the lower levels of these spaces. : Fans operate at full capacity continuously in many systems, and there fore should be selected for good efficiencies. In winter when higher temper ature differentials are used, it is sometimes practicable to deliver smaller air quantities than when cooling. In climates where winter temperatures fall below freezing, the tempering coils should be of the steam-distributing type; or if they are heated by a liquid, this liquid should contain some anti-freezing substance such as ethylene glycol. If hot water is used in cold climates, the control of air temperature should be obtained by means of face and bypass dampers rather than by throttling the valves, to prevent damage due to freezing. If zone reheaters placed in supply-duct branches are employed, they should be of such type as to be heated over the entire surface so that no temperature-stratification can occur in the delivered air. Steam-distri buting-tube coils or mechanically-circulated water coils are satisfactory in such cases, and throttling valves may be used. ' Refrigeration equipment must be carefully selected to satisfy the partic ular requirements of each installation. For some small plants the evapora tor may be placed in the air stream, when type of refrigerant and nature of- occupancy permit. In many cases, chilled water coils are required by considerations of safety. Where low temperature and relative humidity are necessary, brine, often of calcium chloride, may be indicated. . Condensing requirements must have economic analysis. Wells, public water service, cooling towers and evaporative condensers present possibili- Central Systems for Air Conditioning 699 ' ties for consideration. Condenser water may have a secondary use for roof sprays in hot weather, and is usually suitable for lawn sprinkling. Most health department rules in cities prohibit any connection from refrig erant condensers that might permit the water to be used for drinking or lavatory purposes. Practically without exception, air cleaners should be provided for both outside and recirculated air. Control of temperature and of relative humidity by automatic means is vital, if comfort and economical operation of air conditioning equipment are to be attained. The insulation of ductwork may be necessary to prevent condensation of moisture either inside or outside of ducts, housings and fan encasements or to prevent a change of temperature in ducts passing through hot or cold spaces. . In general, the apparatus should be arranged to have a straight-line air flow. Each change in direction increases air resistance and, in addition, elbows and offsets may cause eddy currents resulting in stratification. The usual order of equipment location, beginning at the outdoor-air intake, is: weather hood or louvers, outdoor-air dampers, return-air connection, filters, tempering coils, cooling cOils or sprays, bypass connection with or without reheaters, reheaters, fan and distributing ducts. Screens at the intake prevent the entry of large foreign matter, birds> etc. A hood or louver at the outdoor-air intake prevents the entry of rain and snow. Since in most climates there are many days during which use of 100 percent outdoor air unheated or uncooled may be economical, the areas of all air-passing and treating apparatus should be large enough for such a volume, and the exhaust or . spent-air equipment should be capable of discharging out of doors, all of the air admitted. The bypass connection normally connects the return-air duct system with the apparatus casing between the conditioner and the supply fan. Usually the bypass opening is sized to handle about 50 percent of the fan capacity where a variable bypass is used though extreme load variations may require a larger size. It is at times good design to locate a reheating coil in the bypass connection to .permit using some bypass air when heat ing is required. Since the relatively high resistance of the cooling coil or spray is to be balanced by the heating coil and bypass connection, enough heating surface can be provided to raise the temperature of the bypass air to the point where the mixture of bypassed air and conditioned air will have the required temperature. When a variable bypass is used, a damper working in opposition to the bypass damper should be placed across the face of the dehumidifier, for unless the resistances of the two are carefully balanced at all operating points, the proper mixtures of air will not be obtained. Outdoor air that has not been dehumidified should not b bypassed around a cooling coil or spray dehumidifier if accurate control of the delivered relative humidity is desired. Where the bypass is made a part of the dehumidifier or conditioner and is located on the top or side f it, the return-air connection should be arranged so that stratification of return air is insured, baffles being provided to accomplish this purpose if necessary. When return-air and bypass air connections are taken off a return duct system, it may be necessary to install a back-draft damper between the return-air connection and the bypass connection. When the bypass damper is at maximum opening it may be much easier for outside to pass through the return damper, into the return duct connection and through the bypass, than dor return air to pass through the bypass con- 700 CHAPTER 30 1956 Guide nection into the fan. Air. tends to take, the path of least resistance and, if the dehumidifier resistance is high, and if the return/ duct resistances are low, this situation, is apt to occur. A. recirculating air fan, instead of a back-draft damper, may be required for this case, if the failure of return au to reach the dehumidifier or conditioner is a serious matter under reduced load: conditions. .. , LOCATION OF APPARATUS In general, the outdoor-air intake, preheaters, and return air connections precede the conditioner, while the bypass, reheaters and fan follow it. .In the case of a blow-through system, where the fan is located ahead of the conditioner, the leakage of air at the conditioner is outward, instead of jnward, and may be accompanied by water leakage. The location of the complete apparatus assembly, including the dehumid ifier, will be dependent on the type of building, spaces available, structural characteristics, etc. The type of conditioner used may limit the location under certain conditions. Where cooling coils employing chilled water or brine as the cooling agent are used, there are few limitations with regard to location other than those of pumping power, working pressures, piping costs, etc. Where spray dehumidifiers are used, very definite limitations present themselves, and these may require certain extraneous equipment to make the system workable. If several spray-type dehumidifiers are located on different levels, thus involving different water pressures, a surge or storage tank, to which the return water from each dehumidifier can be taken, is required. Should the water level in the pan of the dehumidifiers be low in relation to that of the surge tank, return water pumps will be required, and these pumps will have to'be operated until the water supply lines are drained in order to prevent flooding of the lower dehuniidifiers. Where spray dehumidifiers are on the same level, equalizing lines between the pans may be required if a storage tank is not provided. It is exceed ingly important that water-tight drained floors be provided under all overhead cooling systems, since water condensed out of the air generally will be present and may damage the interior finish of the rooms below the apparatus. All of the various pieces of equipment from the outdoor air intake through the fan usually are connected together by sheet metal casings. Frequently) the building structure or specially constructed walls or partitions may be used t6 form a portion of the casing. In any case the casing or connection must be sufficiently sturdy for the required duty. Sheet metal work must be well braced not only to prevent vibration under pulsations in air flow, but also to withstand the abuse of normal usage. Casings should be braced wherever access doors are installed, and all large panels should be adequately reinforced by structural steel. Accessibility for Service . Each apparatus layout should be made with accessibility in mind- Where cooling convectors are used, space for removing and repairing or replacing them should be provided. Adequate space should be provided fcr the servicing and replacement of eliminators. Filters must be so lo cated that the proper cleaning, replacement or routine servicing can be accomplished without difficulty. Free access to the bearings of all moving machinery is a necessity. Provision should be made for the replace ment of any parts that are subject to wear, deterioration or damage, such as filters, fanwheels, motors, pump impellers, or heat transfer surface. CHAPTER 31 AIR DISTRIBUTION Definitions, Standards for Satisfactory Conditions, Principles of Air Distribution, Ventilating Jets in Air Distribution, Outlet Performance, Outlet Types, Outlet Location and Selection, Direction and Volume Control, ' Return and Exhaust Intakes, Specific Applications. ORRECT air distribution is essential in warm air heating, ventilating, Cand air conditioning systems. Even though a system delivers the re quired quantity of conditioned air to a room, unsatisfactory conditions result if the air is poorly distributed. This chapter deals with room air distribution only; the transmission of air through ducts is treated in Chapter. 32, Air Duct Design. The objectives of this chapter are to: - 1. Describe the present state of air distribution problems by discussing ventilat ing jets in room air distribution. 2. Present general information on practical air distribution problems by discuss ing outlet performance, outlet types, and also location, selection, and control of outlets. 3. Illustrate the use of the basic concepts and of the practical experience gained in air distribution by discussing specific applications. Further pertinent information on air. distribution will be found in Chapter 6, Physiological Principles; Chapter 12, Heating Load; Chapter 13, Cool-. ing Load; Chapter 19, Gravity Warm Air Systems; Chapter 20, Forced Warm Air Systems; Chapter 25, Unit Heaters and Unit Ventilators; Chapter 26, Unit Air Conditioners and Unit Air Coolers; Chapter 30, Cen tral Systems for Air Conditioning; Chapter 41, Sound-Control; Chapter 48, Transportation Air Conditioning; Chapter 52, Instruments and Measure ments. DEFINITIONS The following definitions referring to air distribution equipment have gained general acceptance. .. . 1. Supply Opening or Outlet: Any opening through which air is delivered into a space which is being heated, or cooled, or humidified, or dehumidified, or ventilated. 2. Exhaust Opening or Return: Any opening through which air is removed from a apace which is being heated, or cooled, or humidified, or dehumidified, or ventilated. 3. Outside Air Opening: Any opening used as an entry for air from outdoors. 4. Damper: A device used to vary the volume of air passing through a confined cross-section by varying the cross-sectional area, , . 5. Grille: ACovering for any opening and through which air passes. , 6. Register: A grille equipped with a damper or control valve. 7. Free Area: The total minimum area of the openings in the air outlet or .inlet through which air can pass. ' - . 8. Core Area: The total plane area of that portion of a grille, included within lines tangent to the outer edges of the outer openings through which air can pass. . 9. Free Area Ratio: The ratio of the free area to the core area. 10. Coefficient of Discharge: Ratio of area at vena contracta to area of opening. 11 Aspect Ratio: The ratio of length to width of an opening or core of a grille. 701 702 CHAPTER 31 1056 Guide 12. Vane Ratio: The ratio of depth of vane to minimum width between two adja cent vanes. * , .. :. 13. Plague: A ceiling outlet in which the supply air impinges against a plate or series of parallel plates, and is deflected horizontally in all directions. 14. Diffuser: An outlet discharging supply air in various directions and planes. 15. Primary Air: The air delivered to the outlet by the supply duct. 16. Induction: The induction of room air drawn into an outlet by the primary air stream (commonly called aspiration). : - 17. Entrainment: The entrainment of room air by the air stream discharged from the outlet (commonly called secondary air motion). - 18. Total Air: The mixture of discharged air and entrained air. 19. Entrainment Ratio: The total air divided by the discharged air. 20. Throw (Blow): The horizontal or vertical axial distance an air stream travels on leaving the outlet (grille) before the maximum velocity is reduced to 50 fpm. - 21., Drop: The vertical distance, the lower edge of a horizontally projected air stream drops between the outlet and the end of its throw. 22. Rtse: The converse of drop. .. 23. Envelope: The outer boundary of. an air stream moving at a perceptible ve locity.. 24: Spread: The divergence of the air stream in a horizontal or vertical plane after it leaves the outlet. , . 25. Diffusion: Distribution of air within a space by an outlet discharging supply air in various directions and planes. .: 26. Radius of Diffusion: The horizontal distance from the diffuser outlet to the perimeter of the space, within which air motion in the occupied zone is. reduced to 50 fpm maximum. .' 27. Outlet Velocity: The average velocity of air emerging from the outlet, measured in the plane of the opening. . 28. Terminal Velocity: The average air stream velocity at the end of the throw. 29. Temperature Differential: Temperature difference between primary and room air. , . 30. Temperature Variation: Temperature difference between points of the same space. : STANDARDS FOR SATISFACTORY CONDITIONS The object of air distribution in warm air heating, ventilating and air conditioning systems is to create in the occupied zone of the conditioned room (floor to 6 ft above floor level) the proper combination of temperature, humidity and air motion. To obtain comfort conditions within this zone, standard limits have been established as acceptable effective temperatures. This term comprises air temperature, motion, humidity, and their phys iological effect on the surface of the human body. Any variation from ac cepted standards of one of these elements may result in discomfort to the occupants. The same effect may be caused by lack of uniformity of condi tions within the space or by excessive fluctuation of conditions in the same part of the space. Such discomfort may arise due to excessive room air temperature variations (horizontally, vertically, or both), excessive air motion (draft), failure to deliver or distribute the air according to the load requirements at the different locations, or too rapid fluctuation of room temperature or air motion (gusts). ,, With reference to permissible room air motion it is not possible to es tablish a specific standard covering the entire complex problem of air dis tribution. Velocities less than 15 fpm generally cause a feeling of air stagna tion, whereas velocities higher than 65 fpm may result in a sensation of draft. Air velocities of 25 to 35 fpm in the occupied zone are most, satis factory, but air motion of 20 to 50 fpm will usually be acceptable, with the lower values used in cooling applications, and the higher values on heatmg Air Distribution 703 jobs. The permissible air motion depends to some degree oii the geographic location of the air conditioning installation. In addition the noise level1 created by the introduction of supply air should be kept within acceptable limits, ,and streaking or smudging of walls or ceilings should be prevented. Reference should be made.to Chapter 6, Physiological Principles, for. in formation on effective temperature and comfort lines, and to Chapter 41, Sound Control, for acceptable room noise levels and noise generated by air. outlets. Material in Chapter 45, Industrial Air Conditioning, covers1 temperature and humidity requirements for products and manufacturing processes, and for health, safety and efficiency of workers. PRINCIPLES OF AIR DISTRIBUTION . Conditioned air is supplied to air outlets at temperatures and velocities which differ greatly from those in the occupied zone of the room. Proper air distribution, therefore, calls for (1) entrainment of room air by the primary air stream outside of the zone of: occupancy in order that air mo tion and temperature differences will be reduced to acceptable limits be fore the air enters the occupied zone, and (2) counteraction of the natural' convection and radiation effects within the room; Practical room air distribution is predominantly an art depending upon clear recognition of physical principles, good judgment, and the cumula tive benefits of extensive experience. The characteristics and performances of air outlets are evaluated by experiment, and full-scale models are em ployed in order to develop satisfactory installation recommendations for specific applications. Frequently the performance of the air distribution system is checked in the field before the installation is turned over to the customer. Adjustments may be necessary before all requirements are met. Manufacturers' literature is available to provide data for the performance and application of various outlets which are usually based upon observa tions in full-scale test rooms: . The complexity of practical room air distribution is due to innumerable variations in building construction, system design, and operating require ments, and makes the exploration of the basic character of air distribution imperative. Research at the A.S.H.A.E. Research Laboratory1 and co operative programs at Case Institute of Technology1 since 1937 have ad vanced considerably the fundamental knowledge in air distribution. A comprehensive survey of the literature relevant to air distribution Problems was made at the A.S.H.A.E. Research Laboratory in connec tion with the experimental investigation of ventilation jets.1(b) This survey deals with fundamentals of turbulence, jet behavior, and miscellaneous Problems, and is sufficiently complete to permit the study of these problems without requiring recourse to the original papers. Therefore, the survey is" an indispensable and timesaving tool for every researcher in air distribution. VENTILATING JETS IN AIR DISTRIBUTION The theory concerning the distribution of conditioned air within an enclosure is still far from complete but a considerable fund of knowledge supported by experimental guidance is available for free jets, and par ticularly for axial-flow type free jets, both singly and in combination.2. . or many conditions of jet discharge, therefore, it is possible to analyze jet performance, and to determine (1) the angle of divergence of the jet oundary, (2) the velocity patterns along the jet axis, (3) the velocity pro any cross section in the zone of maximum engineering importance, nd (4) the entrainment ratios in the same zone. In other words, it is possi-; :i; 111 ii j! i Si ii.U- * 1 i : i .11: 704 CHAPTER 31 1956 Guide ble to answer the following questions about a jet discharged from any air supply outlet: / 1. What is the shape of the jet (spread or coverage)? 2. How can the velocity at any selected point within the jet be determined? 3. How far does the jet travel or what is its throw? A free jet is a straight-flow jet, free from pulsations or helical flow, which is discharged into a large open room in which no surfaces, objects, or con vection currents interfere with the formation of the natural flow pattern. Most of the available data refer to isothermal jets. Information given herein refers to this type unless otherwise noted. Types of Outlets Two general classes of outlets have been the subject of experimental study: Class 1. Straight-flow devices; such as ducts, nozzles, orifices, slots, straight-flow grilles and multiple openings located close together, perforated panels being an extreme example. . Class S. Annular outlets including ceiling plaques, but not including diffusers. Fig. 1. Cross-Sections op Round Ducts with Three Basic Types of Annular Outlets Fig. 1 shows three basic types of annular outlets. Outlet A is a circular slot in a wall or ceiling, and produces a jet similar to straight-flow jets. Outlet B discharges the jet radially from the axis of the approach duct, and also produces a jet quite similar to straight-flow jets. Outlet C, usually called a ceiling plaque, is a radial outlet with a plane boundary extending from one edge, but it cannot readily be correlated with outlet B. Shape of Axial Jets A surprising similarity between the shape of the -jets exists at a short distance from the outlet face, whether the outlet is round, rectangular, grille-like, or a perforated panel. Even in the case of wide-angle grilles or annular outlets, the similarities are such as to permit the same analysis of performance. The jet discharged from a round opening forms an expanding cone; whereas jets from rectangular outlets rapidly pass from rectangular to elliptical- cross-sectional Shape at a short distance from the outlet face, and then to a circular shape, at a rate depending primarily on the aspect ratio. The angle of divergence is very definite close to the outlet face, but the boundary contours are somewhat billowy and are easily affected by ex ternal influences. Here, as in air distribution generally, room air movement is replete with local eddies, vortices, and surges, which are manifestations Air Distribution 705 of unbalance in the forces acting within the air stream. These internal forces govern the air motion, yet they are extremely delicate. Measured angles of divergence (spread) for discharge into large open spaces have usually ranged from 20 to 24 deg with an average of 22 deg. Coalescing jets for closely spaced multiple outlets expand at somewhat smaller angles, averaging 18 deg, and jets discharging into relatively small spaces show even smaller angles of expansion.3 Tests indicate that in cases where the outlet area itself is small compared to the dimensions of the space normal to the jet, the jet may be considered free as long as where X < 1.5VAr X = distance from face of outlet, feet. Ar = cross-sectional area of the confined space, square feet. Four Zones in Jet Expansion In analyzing the performance of jets, four major zones can be distin guished. They may be roughly defined in terms of the maximum or center line velocity existing at the cross section being considered: Zone 1: A short zone, extending about 4 diameters or widths from the outlet face (or vena contracta for orifice discharge), in which the maximum velocity of the air stream remains practically unchanged. Zone 2: A transition zone, extending to about 8 diameters for round outlets, or for rectangular outlets of small aspect ratio, over most of which maximum velocities vary inversely as the square root of the distance from the outlet. For rectangular outlets of large aspect ratio, this zone is elongated and extends from about 4 widths to a distance approximately equal to the width multiplied by four times the aspect ratio. Zone S: A long zone,, of major engineering importance, in which the maximum velocity varies inversely as the distance from the outlet. This zone is often called the zone of fully established turbulent flow and may be 25 to 100 diameters long (or equivalent diameters of equal areas), depending on the shape and area of the outlet, the initial velocity, and the dimensions of the space into which the outlet discharges. Zone A' A terminal zone in which, in the case of confined spaces, the maximum velocity decreases at an increasing rate, or, in the case of large spaces free from wall effects, the maximum velocity decreases rapidly in a few diameters to the velocity range below 50 fpm which is usually regarded as still air. Centerline Velocity in Zone 3 . Research has shown that maximum or centerline velocities in Zone 3 of straight flow isothermal jets can be determined with good engineering ac curacy from Where V* = K'VV& = K'Q x XVT, = X'Q *vXxed xrT. U) (2) (2a) centerline velocity, feet per minute. F,, wn -X iCto = average initial velocity at discharge from open-end duct ' or across contracted stream at vena contracta of orifice or multiple opening outlet, feet per minute. 706 CHAPTER 31 1956 Guide , yc -- nominal velocity of discharge based on the core area, feet per minute. Ca = coefficient of discharge (usually between 0.65;and 0.90). . Rii-- ratio of free area to gross (core) area. ... . _ . X = distance from face of outlet, feet. -. ,. K and X' = proportionality constants, with A'-- 1.13 X . : Di,effective or equivalent diameter of stream at discharge from open-end duct or at a contracted section, feet. ' At = A,, X Ca X i?fa = effective area of stream at discharge from an open . end duct or at a contracted section, square feet. At = measured gross (core) area of outlet, square feet. <2 = discharge from outlet, cubic feet per minute. Equation 1 is nondimensional.and requires only that consistent units be used, as in the above nomenclature. Values of K and K' are listed in Table 1.2.4 K K'Table i, Recommended Values op the Centerline Velocity Constant or (See Equation 1) . Type op Outlet K ..... ' v, = 500 to 1000 Vo = 2000 to 10,000 K Fo = 500 to 1000 Fo = 2000 to 10,000 Free Openings Round or Square 5.0 6.2 5.7 7.0 Rectangular, large as- 4.3 5.3 4.9 6.0 pect ratio (<40) Annular slots axial or _ _ 3.9 4.8 radial* Grilles and Grids ; Free area 40% or more 4.1 5.0 4.7 5.7 Perforated Panels Free area 3 to 5% 2.7 3.3 3.0 3.7 Free area 10 to 20% 3,5 4.3 4.0 4.9 For radial slots use XfH instead of X/iA)1*2. H is the height or width of the slot. - . Note: K and K' are indexes of loss in kinetic energy. Interpolate as required. Departures from maxi* mum value indicate losses in first and second zones when compared with the jet from a rounded-entrance, circular nozzle. Low velocity test results, in the range Vx < 150 fpm, indicate that the normal values of K and K' should be reduced about 20 percent for Vx = 50 fpm, as used in later Equation 4b for throw. Fig. 2 gives the effective diameter Z)0 in inches for single openings and includes the coefficient of dis charge.6 Similar values for grilles are available in the literature or can be experimentally determined. Values of Ca and Ru are required for deter mining Vo, Do and A0 for orifice-type and multiple-opening outlets, and should, therefore, be included in catalog data of these outlets. In the case of multiple-opening outlets and annular-ring outlets (see diagram A of Fig. 1), the streams coalesce into a solid jet before actual jet expansion takes place. This coalescence affects the experimentally de termined proportionality constants K or K' and accounts for some of the divergence in reported values for similar outlets. Centerline Velocities in Zones 1 and 2 . Experimental evidence indicates that in Zone 2 -- V,__ . /x'ih Vt r X (3) Air Distribution 707 where ' . .. . . - 1 .: Eo = width of jet at outlet or at vena contracts. Approximately the same values of K' apply as for Zone 3 expansion from axial outlets. : ' In Zone 1, the ratio Vi/Vo is constant and equal to the ratio of the ceri- Fig. 2. Effective Diameters for Round and Rectangular Openings (Plenum Approach) , ter velocity of the jet at start of expansion to the average velocity, ranging irom approximately 1.0 for rounded-entrance nozzles to about 1.2 for T^ght pipe discharge, but with much higher values for diverging-diseharge outlets. Determining Centerline Velocities . Permit correlation of data from all four zones, centerline velocity ra08 are plotted against distance from outlet in Fig. 3 in accordance with 708 CHAPTER 31 1956 Guide the basic relation of Equation 2, and a nomogram for calculating the pa rameters and I--? V,, from X vz and Vx Vo through Ria and Cd is given in the same illustration; Fig.-3. Chart: por Determining Centerline Velocities op \' ; Axial and Radial Jets . Zones 1 and 2. Fx/Fo is plotted against X/Ha and; for a range of aspect ratios, against X/'s/A for the single value of K' = 7.0. Values of V^/Vo for_other values of K' may be obtained by direct-proportioning of VK' to V7.0. V-';;... . . The following Example 1 which is solved on Fig. 3 will illustrate the use of the chart. Example 1: A grille has a core area 12 in. x 18.75 in., it( = 0.90, Cd = 0.80, and K' = 5.0. Find Ve (velocity through core area) when V\ is 50 fpm for throw of 50 feet (X = 50). ' Solution: A, 12 X. 18.75 1.56 aq ft . 144 . . Air Distribution 709 X 50 -7= =-----= 40 VT,, 1.25 Ao = 1.56 X 0.80 X 0.90 = 1.123 X 50 VZ " i.06 " 47 2 V, K'VX 5\/n23 0.106 V,, X 50 Vx_______V_x______ 0.106 Ve 7o(Cd RJ = 0.80 X 0.90 ' 0.147 For V, = 50, 50 Vc = ,, ;= 340 fpm. 0.147 The quantity of air discharged is then, : Q = V.AC = 340 X 1.56 = 530 cfm. Throw Equation 2a'can be used to determine the throw X of an outlet, if the dis charge volume and the center velocity are known. or, if _IC Q ~ Vx Va. X Cd X fti. (4) Z = VCd X Ri. X=V Q Vx' ZVT. (4a) The maximum throw L is usually defined as. the distance from the outlet face where the centerline velocity is 50 fpm. Therefore, for V% = 50 fpm, IC Q L 50 ' ZyfZ, - (4b) Velocity Profiles of Jets, : ' In Zone 3 of both axial and radial jets, the velocity distribution may be expressed by a single curve (Fig. 4) in terms of dimensionless coordinates, and this same curve can be used as a good; approximation for adjacent por tions of Zones 2 and 4. Experiments have shown that temperature and density differences have but a small effect on cross-sectional velocity pro files. . Velocity distribution in Zone 3 can be expressed by the Gauss errorfunction or probability curve which is approximated by a simple equation using common logarithms - V 3.3 log (5) where r = the radial distance of the point under consideration from the centerline of the jet. ' 710 CHAPTER 31 1956 iGuiiil; Air Distribution 711 Fig. 4. Cross-Sectional Velocity Profiles fob Stbaightflow Turbulent Jets r0.t -- the radial distance in the same cross-sectional plane from the axis to the point where the velocity is half the centerline velocity. (V = 0.5 V,). Vx = the centerline velocity in the same cross-sectional plane, feet per minute. V = the.actual velocity at the point being considered, feet per minute., Experiments show that the conical angle for 0.5 VI and r06 is approxi-' matejy one-half of the total angle of divergence of a jet. The velocity pro file curve for one-half of a straight-flow turbulent jet (the other half being a symmetrical duplicate) is shown in Fig. 4. For multiple-opening outlets, such as grilles, or perforated panels, the velocity profiles are similar, but the angles of divergence are smaller. ., Radial Jets In the radial jet (diagram B in Fig. 1) the cross-sectional area at any dis tance from the outlet varies as the square of this distance, the same as for an axial jet. Experiments have shown that the centerline velocity gradients and the cross-sectional velocity profiles are similar to those of Zone 3 of axial jets and that the angles of divergence are about the same. In using Fig. 3, X/H should be used as abscissa instead of X/y/~A. ' Jets from ceiling plaques (diagram C in Fig. 1) have the same form as one-half of a free radial jet. The jet is wider and longer than a free jet, with the maximum velocity close to the wall. This is demonstrated in Fig. ;*> which also indicates that under the conditions shown the width of the slot Fig. 6. Shape of Aib-Stbeam Envelopes as Slot Area is Increased between ceiling and plaque has' little effect on the jet pattern or velocities at some distance from the plaque.2 Discharge from a Long Slot. . - : When a long slot receives its air supply from one end only, the important design factor is the ratio of the area of the slot to the area of the supply duct, and both the air stream profiles and the duct pressure requirements are de termined by this ratio.6 Fig. 6 shows the changing profile as the slot area is increased for a rounded entrance slot (Ca = 0,93) with constant duct cross section. ' The air discharge from a slot in a tapered duct will be uniform (Fig. 7.) for a relationship between discharge angle and slot-duct dimensions7 where .. . , cot = Ad . . .. (6) ' . .. 9 = discharge angle, degrees. ' A, = slot area, square: feet. Ad = duct cross-sectional area at upstream end, square feet. Cd = coefficient of discharge. . Perforated Panels , \ . '- When air is discharged from perforated panels of relatively large sizes, the constant velocity core formed by the coalescence of the individual jets extends a considerable distance from the panel-face.-In this: Zone 1 region the proportionality constants K and K' do not apply. Therefore, the pro portionality constants given in Table 1 should be used only \vhen the ratio (Distance from panel/v/Pancl area) is larger than 5. When the ratio is less than 5, the equation :: - ` . : : Vx = Vo-l Ca X R,. should be used for estimating centerline velocities.8 : '. (7) Fig. 5. Aib Jets from a 14-in. Ceiling Plaque fob Two Slot Widths wits Same Rate of Flow Fig. 7. Uniform Aib Flow from a Slot Supplied by a Tapered Duct 712 CHAPTER 31 1956 Guide- Fig. 8. Jet Velocity Patterns fob a Square Outlet Discharging along Wall ob Ceiling (Vo = 8880, A = 0.10, Cd = 0.78) Effect of Walls and Ceilings Jets discharging parallel to a wall with one.edge of the outlet coinciding with the wall, take the form of one-half of an axialjet discharging from an outlet twice as large, similar to radial jets from ceiling plaques. Entrain ment takes place practically only along the surface of a half cone and the rnityirnmn velocity remains close to the wall.2 (See Fig 8). .Values of K and K' are approximately those for a free jet multiplied by y/2, that is to say, the normal maximum of 7.0 for K' for free jets becomes 9.9 for a sim ilar jet adjacent to, and discharged parallel to, a wall, and in Fig. 3, ^== X should be used in place of -- V Ao When a jet is discharged parallel to, but at some distance from a wall, its expansion in the direction of the wall is reduced and entrained air must be obtained by recirculation from the jet itself instead of from ambient air.3 -9 The jet expands normally to within a short distance from the wall, which nearer to the outlet only affects velocity distribution in the outer shell of the jet, but further on also affects centerline velocities. This happens at some distance from a plane where the jet outline becomes parallel to the wall, and where the jet enters its fourth or terminal zone. Few engineering data are available on this important phase of jet expansion.3 Air Distribution 713. Effect of Resistance on Return Path of Jet Air , Laboratory experiments on jets usually involve recirculated air with negligible resistance to flow on the return path of the jet air. Experience and experiments in tunnels of small cross-sectional area in mines, where considerable resistance is offered to the return flow of jet air to outlets, show that the expansion of the jet terminates abruptly at a distance that is in dependent of velocity of discharge and but slightly affected by size of out let. Such distances are determined primarily by size and length of return path. In a long 5 ft x 6 ft tunnel, a jet may not travel more than 25 ft $ 2k :l -nr -15 -20 - -30 - -40 -50 - -60 - -JO - -SO - -80 100 - -150 - -200 - -300 - -400 -500 - -edo 10.Fig. Nomogram for Center, or Peak, Velocities for Hounded, Rectangular Jet Sources ^ereas in a relatively short opening, 25 by 60 ft, it may travel more than *50 ft. Few engineering data are available on this phase of jet expansion but it can be of great practical importance.3 Entrainment Ratios Equations for the entrainment of circular jets and of jets from long slots nave been mathematically derived.10 They are: For third zone expansion of circular-jets, = _2 <? K'' VT,, (8) 714 CHAPTER 31 1956 Guide'. For a long slot .. t! (8a) where . ' ''. ; Qx = total volume flow rate at distance X from face of outlet, cubic feet per minute. ; Qo -- discharge from outlet, cubic feet per minute. X = distance from face of outlet, feet. F . 11.ig Nomogram fob Entrainment Ratios of Rounded, Rectangular Jet Sources . K'proportionality constant. Ac - effective area of stream at discharge from an open-end duct or at a con tracted section, square feet. Ho = width of slot, feet. Equations 8 and 8a have been used in plotting Fig. 9 for entrainment ratios. '. The nomograms (Figs. 10 and -11) for center velocities ahd entrainment ratios for jets emitted from circular sources, and from rectangular sources of all aspect ratios, are based upon recently developed theory.11 Air Distribution 715 OUTLET PERFORMANCE The results of the studies undertaken in room air distribution which have been presented in the foregoing section can be used as a basis for engineer ing design of supply outlets if the following is kept in mind: 1. The method for finding jet velocities is based upon several approximations and the two recommended equations must be used with caution for extreme axial and radial distances. . 2. The characteristics of the low-velocity regions of ventilating jets are not yet well understood, and for both axial and radial jets the effect of the Reynolds number is not fully known. 3. The quantitative treatment of the forces which govern room air distribution phenomena has been limited, and non-isothermal conditions involving buoyant forces have not yet been fully explored. 4. All investigations have been concerned with free jets, whereas air streams in practical room air distribution are not free streams but are influenced by walls, ceilings, floors and obstructions. 5. The science of air distribution has not yet reached its final stage where a basic theorem permits the exact mathematical solution of all problems, and velocity pat terns in closed rooms, and of a great variety of outlets, such as radial and slotted outlets, diffusers and perforated panels, must be further studied before their per formance can be predicted with confidence. However, the air distribution research sponsored by the American Society of Heating and Air-conditioning Engineers has proved that the phenomena of room distribution are amenable to scientific research and rational interpretation, and the ventilation jet problem has reached a stage where a definite technique of experimentation in combination with semi-empirical theories can be of great help in the design of air outlets. 6. In the design of air outlets, the days of unguided and unrelated experimentation should be over. Practical room air distribution, however, is still predominantly an art, where decisions depend on isolated tests and judgments must be based on the accumulated experience of the behavior of outlets in the laboratory and in the field. In designing a satisfactory air distribution system, the engineer must make use of such tests and draw on this experience; and weigh the different factors of the outlet performance which place considerable limitations on his proceedings. A short dis cussion follows regarding some of these factors which are: (1) jet pattern, (2) capacrty. (3) temperature differential, (4) permissible room air motion, (5) permissible noise level, and (6) smudging. Jet Pattern Refer to section Ventilating Jets in Air Distribution for a general discus sion of the jet pattern. In selecting the throw and drop of outlets the follow ing considerations are important : (1) throw, (2) effect of vanes, (3) effect of type of outlet, and (4) drop. 1- Throw. The throw of a wall outlet must be sufficient to produce satisfactory conditions over the area to be conditioned. Underblowing may cause heated air to rise too rapidly above the occupied zone and thus create excessive vertical tem perature variation (stratification); in cooling operation it may cause cold air to drop mto the occupied zone before supply and room air are mixed sufficiently, and thereby create a condition of acute discomfort (draft). On the other hand, over blowing will result in objectionable downdrafts from any surface the primary air stream may strike. ' On the average, it is considered most practicable to select a throw which is threelclllrlhs of the distance toward an exposed wall or window, as shown in diagram A of Fig. 12. However, structural characteristics, mounting height of outlet, tempera ture differential, and resultant drop or rise, or location of greatest heating or cooling loads strongly affect the selection of the optimum throw. In spaces with beamed ceil'Rgs, the outlets should be located below the bottom of the lowest beam level, and Ptofotably low enough so that an upward or arched blow may be employed. The blow should be arched sufficiently to miss the beams and, at the same time, in such a man ner ss to prevent the primary or induced air stream from striking furniture and ob stacles, and producing objectionable drafts. 2. Effect of Vanes. Vanes affect grille performance if their depth corresponds at 716 CHAPTER 31 1956 Guide least to the distance between the vanes. 15 the sane ratio is less than unity, effective control of the air stream discharged from the grille by means of .the vanes is impos sible. If it is higher than two, further improvement is slight. A grille discharging air uniformly forward (vertical vanes in straight position), will have a spread o( 14 to 24 degrees, depending on type of outlet, duct approach, and discharge velocity. Turning of the vanes will influence the direction and the thrAowgroilflethWe idthisdcihvaerrggeindgaviarnsetsre(avmer.tical vanes with uniformly increasing angular de flection to a maximum at each end of 45 deg) will have a spread of approximately 60 deg and the throw will be reduced considerably. With increasing divergence the quantity of air handled by the grille for a given duct static pressure will decrease. A grille with converging vanes (vertical vanes with uniformly decreasing angular deflection) will have a slightly higher throw than a grille with straight vanes, but the spread will be the same for both settings. The air stream will converge slightly for a short distance in front of the outlet, and then spread somewhat more than the air discInhaargdedditiforonmto, avegrrtililceawl viathnesstrwahigichht vnaonremsa. lly sp. re. ad the. air horizontally, horizon tal vanes may be used to spread the air vertically. However, spreading the air verti cally entails, the risk of hitting beams or other obstructions, or of blowing primary air3a. tEefxfeccetssoivfeTvypeelocoitfieOsu,tilnetto. Ctheeilioncgcudpififeudsezrosnde.istribute th.e .ai.r with a horizontal spread of 360 deg and also have a downward air motion. Therefore, both throw (radius of diffusion) and mounting height are important and interdependent factors. Due to the 360 deg spread, the rate of induction is higher and the throw shorter than that for a wall grille handling the same air quantity at the same outlet velocity. Therefore, ceiling diffusers will frequently permit the use of higher air velocities than wall outlets, and consequently may be sized smaller to handle the same air volumes. If ceiling outlets are installed flush with the ceiling, impingement of the air stream along the ceiling surface restricts, induction of secondary air, and the throw is in creased approximately 40 percent above that of an unrestricted air stream. (Refer to Radial Jets and Effect of Walls and Ceilings in section Ventilating Jets in Air DisStrloibttuetdioonu)t.lets, due to their high aspect ratio, have higher induction than compa rable round or square vaned outlets of equal area handling the same air quantity, and their throw is shorter. (Refer to Discharge From a Long Slot in section Ventilat ingTJheetspeinrfoArairteDdisptarnibeul tisioann).excellent device for producing a large diameteT stream with a uniform velocity across its entire area. Although this type of outlet can handle the greatest amount of air in proportion to room size, jet velocities must be kept low. (Refer to Perforated Panels in section Ventilating Jets in Air Distribution). For. all types of ceiling outlets the following considerations should be noted: (1)if the temperature of the supply air is below that of the room, if should be thor oughly mixed with the room air before it enters the occupied zone; (2) air slightly above room temperature will usually be properly distributed' by outlets selected for cooling; and (3) if the temperature of the supply air is substantially higher than that of the room, it.should be projected downward in a broad diverging pattern to avoid stratification and to obtain proper mixing and controlled air flow. 4. Drop. The air discharged from a wall outlet should not reach the occupied zone until the velocity has fallen to about 50 (pm. Therefore, the outlets should be located high enough for the air stream at the termination of the throw to be not less than 5 or 6 ft.above the floor level, or in other words, the drop should not be more than the difference between mounting height and zone of occupancy (Diagram A of Fig. 12)- Air Distribution 717 As illustrated in diagram B of Fig. 12 the maximum permissible throw for a given ceiling height may be obtained by locating the outlet low on the wall, arching the blow, and sweeping the air across the flat area. The air, as it traverses, will adhere to the ceiling. The objection to this method is the possible streaking of the ceiling with dirt. ' ' ' Capacity '. . ; The quantity of air to be handled is determined by the heating, cooling, or ventilating requirements. (Refer to Chapters 11, Infiltration ahd Venti lation, 12 Heating Load, and 13 Cooling Load). Manufacturers' rating sheets are usually consulted for selection of the proper number, size, and type of outlets for a given air quantity. The basis of rating should be care fully noted to make certain that resulting velocities are suitable for the application. . ... Temperature Differential . The temperature difference between supply, and room air is highly im portant, because temperature control in the conditioned room is. strongly affected by this difference. The greater the temperature differential, the greater the change in room temperature for a given change in the heating or cooling load. The use of outlets which cause a large amount of room air to be mixed with the supply air, permits the use of greater temperature differentials. . Refer to section Air Quantity and Temperature Differential, Chapter 30, Central Systems for Air Conditioning. Room Air Motion . To achieve a constant air motion in the occupied zone without exceeding acceptable velocity limits is one of the most important problems in air distribution. Some of the factors which may cause air motion to exceed these limits are: excessive air discharge velocities; high air volume per cubic foot of space (often referred to as number of air changes per hour); pre mature drop of cold air into the occupied zone; overblow causing spilling of high velocity air into the occupied zone; heating in severe climates by means of downward projection of hot air. These factors will not affect equally the various designs and types of air outlets, and their effect will also depend on the temperature differential, the mounting height of the outlet, and other circumstances. For instance, certain outlets will handle safely more air per cubic foot of space at higher discharge velocities than others, and downward projection of air may sometimes even be necessary if the supply air temperature is substantially higher than the room tempera ture. (Refer to section on Throw). Sometimes excessive air motion may be encountered in correctly de signed air distribution systems due to drafts occurring, if stairways or exit doors are left open, or if windows are opened when design of system requires that they be closed. Discomfort is frequently attributed to drafts when it is actually due to too low room temperature. This may occur during the heating as well as the cooling season. Systems designed for heating and ventilation .only may easily cause complaints of drafts when cooling is added. -. - - ; Permissible Noise Level . . . . The increase of the noise level caused by an outlet is primarily a func tion of its discharge velocity and its size. The maximum acceptable noise level in a space may dictate completely the selection of the permissible out 718 CHAPTER 31 1956 Guide let velocity. In addition, however, noise may be caused by excessive re striction of the free outlet area due to outlet design, by unnecessary turbu lence due to one-sided air flow through the outlet, or by the impingement of high velocity air on sharp edges. The origin of excessive noise may be spotted by removing the outlet with out stopping the air supply. If noise is still evident, other elements of the air conditioning system or entirely different sources are at fault. Highpitched, rushing noise indicates that the duct systeni or excessive velocities in the duct are the cause, low-pitched rumbling noise points to the mechan ical equipment of the air conditioning plant. . When very high duct velocities are used, sound absorbing lining or special acoustical filters (sound traps) must be provided. High pressure or high velocity outlets for multi-room and other buildings are equipped with a special pressure reduction and sound attenuation box. (Refer to section Types of Air Outlets). For a general discussion of permissible room noise levels and air supply outlet noises, refer to Chapter 41, Sound Control. Smudging All air outlets have their particular smudging problems which have been studied by various investigators but cannot yet be considered solved. Smudging is due to dirt in the room air and in the air discharged by the outlets. Although the primary air may be carefully filtered, small particles of dirt and dust will-not be captured by mechanical filters, and may finally be deposited on the walls or ceiling. With ceiling outlets, dirt streaking may be minimized by carefully controlling the discharge of the outlets,,or by the use of special deflecting plates or anti-smudge rings. With wall outlets, dirt streaking may be minimized by preventing direct impingement of the air on any ceiling or room surface. Floor outlets may offer objection as dirt collectors. TYPES OF AIR OUTLETS Air supply outlets for commercial, industrial and residential applications are either side wall or ceiling type outlets. In homes, baseboard and floor type outlets are also used. (Refer to Chapter 19, Gravity Warm Air Systems, and Chapter 20, Forced Warm Air Systems). As a great variety of outlets of various design are available in these four types, the final selection of a supply air outlet depends to a large degree upon the specific problems of the air distribution system to be used. In addition to the comments which follow on use and application of out lets, reference should also be made to sections Outlet Location and Selec tion and Specific Applications of this chapter. Wall Outlets Side wall outlets in general use are (1) perforated grilles, (2) fixed and adjustable bar and vane grilles, (3) registers, (4) wall diffusers, (5) slotted wall outlets, and (6) high pressure or high velocity wall outlets. 1. Perforated Grilles. These grilles have a small vane ratio and are not adjustable. They are useful primarily where directional air Bow is unnecessary, and for applica tions where the grille size can be increased in order to provide the required free area. 2. Fixed and Adjustable Bar and Vane Grilles. Grilles with fixed bars or vanes are used for wall, floor or baseboard applications when the performance is not critical or can be adequately predicted. Adjustable grilles are equipped with either vertical or horizontal adjustable bars or vanes or both, and are used where proper control of air motion is essential. Vanes should be designed for quiet operation. Air Distribution 719 3. Registers: Grilles equipped-with dampers or adjustable valves, for controlling volume distribution of the supply air are called registers , . ...... . , 4. Wall Diffusers; These outlets incorporate derign features originaliy.develqped tor ceiling outlets, and therefore make-useof semi-conical-or semi-pyramidal-guitfe vanes instead of the straight vanes of the cqnventibnalaide-waUxaiUet. lh'fw^m air perimeter systems .they are Used to blanket ihe76uf8ide".waU^th.the warimsiipply air. . . - - - ;- -- . ----- rrc>-- ~ 7 v-':- 5. Slotted Outlets. These outlets are available in a great variety of, designs, con sisting either of elongated outlets With perforations, or flat outlets with a number Of long narrow slots or a single harrow sloL of straight long outlets with one IohgVslot or diffusing vanes. Due to their high aspect ratio, slotted outlets have higher entrain ment than comparable round or square vaned outlets of equal area and consequently, the throw is reduced.' (Refer to Discharge From' fi Long'Slot in Section Ventilating Jets in Air Distribution). . ... . / ,.. Slotted outlets are particularly useful in connection with tjie linear, design motif in architecture, for applications where it is desiredto m.fefgfe'aifOutletevmobtrusively with the room decoration. They may be used fOreither ceiling otwaH-afr distribution, including the so-called Under-the-window application. In all applications, capacity limitations, proper duct approaches and correct balancing of slotted outlets must be carefully considered, as correction after installation is difficult: / . .. ;- 6. High-Pressure or High-Velocity Outlets. Ejector nozzles operate at high-static pressure and convert this pressure into velocity pressure with resulting high indue-. tion of room air. They are mainly usrii for industrial-process installations, particu larly drying. Another type of ejector nozzle is sometimes referred to as :i louver nozzle and has a 45 to 90 deg elbow, which can be rotated similarly to ,a universal joint about an axis perpendicular to the surface to which it is fastened. These outlets give a considerable degree of adjustability and are, therefore,-useful for spotcooling in confined spaces. " 1. ' . High-pressure or high-velocity air conditioning systems installed in multi-room and other buildings; use very high velocity and pressure soThat the size of the ducts can be reduced. This in turn requires the use of high-presgure or. high-velocity air outlets which reduce the velocity and pressure and atteUuate'the sound to predeter mined values at the point where the air is discharged. It is also possible, of course, to use high velocity only in part of the system, for example in the main trunk ducts, and conventional velocities tn the branch ducts. Special high-pressure control unite are then installed at the end of the main duct, and the air ^discharged through con ventional air outlets in the various spades of the building,' . . .. Various high-pressure or high-velocity outlets of different design,'but usually consisting of a pressure reduction and sound attenuation box and a grille or diffuser, have been developed for high-velocity systems and are described in! the literature o'f the manufacturers. These outlets may be'used in the ceiling or in the wall of the air conditioned space, including under-the,window installation, or in the ceilings of corridors. ' ............... ' ...... . Refer to Induction Convectors for multi-room buildings in Chapter 30, Central Systems for Air Conditioning. .... . Ceiling Outlets ; . ; .y - - 'v 7 : - Ceiling outlets in general use are (1) ceiling plaques, (2) ceiling diffusers, (3) high pressure or high.velocity ceiling outlets, and (4) perforafed,ceilings and panels. . ...... 7 . 7 1. Ceiling Plaques. (Diagram C of Fig. 1). Plaques are of simple design. The air from the supply opening impinges on a plate and is discharged horizontally . Plaques are inexpensive, but as the air is not always uniformly,discharged in all directions, proper control is difficult. ... 7 2. Ceiling Diffuser's. Ceiling diffusers are round', square, rectangular or slotted outlets of various designs installed on, or parallel to, the ceiling: Performance of the different designs varies according to the principle employed. Some have no internal induction, but hasten external induction by supplying,air in multiple layers. Others have internal induction and distribute air over an entire hemisphere. The induction effect is greatest in the direction of the axis of the outlet, and least in the plane per pendicular to the axis and located at the ceiling level. Thus the induction is greatest jn the vertical direction Where the least throw can be tolerated, and least in the horizontal plane at the ceiling where the greatest, throw is desired. Refer to section Slotted Outlets under Wall Outlets. 720 CHAPTER 31 1956 Guide 3. High-Pressure or High-Velocity. Outlets. Refer to text in section Wall Outlets. 4. Perforated Ceilings and Perforated Panels. These devices discharge air through perforations in the ceiling or part of the ceiling, and share with slotted outlets the advantage of unobtrusive appearance. In addition, sound absorbing materials may be used for the panels, or the panels may provide a luminous ceiling. Outlet air velocities may be kept ldw by using large outlet areas, particularly in spaces with high room loads, high ventilating requirements or low ceilings. Some perforated panels have a control plate frame which is inserted in the conventional ceiling duct. Supply air enters the plenum above the distribution plates through an adjustable air valve which can be set for varying air quantities and velocities. OUTLET LOCATION AND SELECTION The design of the air conditioning plant for a building depends on the use to which the building is put,; on its size, and its construction type; the design of the air transmission and air distribution system is influenced by the same factors. Therefore, these factors must be considered in designing the air transmission system, and, in selecting the type and location of the supply outlets. The location and selection of the supply outlets is further influenced by the interior design of the building, local sources of heat gain or loss, and outlet performance and design. . Use, Size, Construction of Building " The use, size and construction of a building are three factors which may influence or even govern the selection of a particular type of air distribu tion system, as is shown by the development of special high-pressure or high-velocity transmission and distribution systems for multi-room and other buildings. Generally, the physical construction of the individual rooms of a building, such as height and shape and the location of beams and other obstructions, influences the possible location of the supply ducts which in turn influences the outlet locations. The location of the supply ducts-- above the ceiling or within the walls, in a furred space above corridors, or. in the conditioned room itself--has an important bearing, therefore, upon the design of the air distribution system. A particular method of air distri bution may be highly desirable but it may be impossible to use it, due to the location of beams and masonry walls. Refer to section Specific Applications for a discussion of air distribution methods in various buildings. Heat Gain or Loss Local sources of heat gain or loss promote convection currents or cause stratification, and may, therefore, determine both the type and location of the supply outlets. ' Generally, the outlets should be located to neutralize any undesirable convection currents set up by a concentrated heating load. If a concentrated source of heat is located at the occupancy level of the room, the heating effect may be counteracted by blowing the1 supply air toward the heat source, or by locating an exhaust or return grille adjacent to the heat source. The second method is more economical, as heat will be withdrawn at its source rather than be dissipated into the conditioned space. Where lighting loads are heavy and ceilings relatively high (five watts per sq ft and above 15 ft), the outlets should be located below the lighting load, and the stratified warm air removed by an exhaust or return fan. An exhaust fan is recommended if the wet-bulb temperature of the air is above that Of the outside temperature, a return fan, if it is below this temperature. Either method reduces the requirements for supply air. If the lights are exposed. Air Distribution 721 less saving can be realized than if they are enclosed, as a considerable por tion of the energy is radiant; An important function of any supply outlet during winter heading is to maintain the temperature difference between the floor and ceiling at the lowest possible value. Since the air within a room is never so perfectly mixed that all of it is at exactly the same temperature, a certain amount of stratification is inevitable. Unless the supply outlets are properly selected and located, the temperature difference will be large enough to result in discomfort to the occupants. , The proper selection and location of outlets is particularly difficult for rooms with large windows and exposed wall areas. Heat is lost primarily thrpugh these areas, and room air in contact with these'surfaces is chilled and flows downward, causing drafts near the exposed surfaces and floor. This condition can best be prevented by locating the air outlets under the windows, by discharging warm air across the exposed surfaces, or by providing supplementary radiation under the windows, in addition to the wall or ceiling air distribution outlets. This solution must be used for com fort installations in northern latitudes (outside temperatures below 40 F), when the building walls are uninsulated or single-glass windows are used. In buildings located in regions where winter heating is a minor problem,, high induction by ceiling or wall outlets may be employed to mix properly the entire room air with the supply air and to prevent downdrafts along the exposed surfaces. In northern latitudes, this solution can only be used if the buildings have double-glass windows and insulated walls, as otherwise the induction effort required for neutralization of the downdrafts is so great that the air motion in the room exceeds comfort limits. Where com fort conditions are not critical as in factories for heavy manufacturing, ware houses, etc., satisfactory results with high induction outlets can be obtained even in cold climates. For uninsulated walls and glass areas in these build ings some supplementary heating is often valuable. Wall diffusers, direct radiation or warm panels will satisfy these requirements for supplementary heating. . The location of exhaust or recirculating air openings at the base of large areas of glass is sometimes effective in reducing downdrafts into the oc cupied space. . . Great care should be exercised in the use of supply-exhaust air outlets for heating in northern latitudes when considerable exposed wall and window surfaces are involved. In such cases additional radiation is usually required. When the system is used for ventilating only during the heating season, direct radiation should be regulated to provide heat Until room and outside temperature are balanced. To avoid stratification; it is advisable to operate the fan continuously and to limit the temperature differential by supplying air at a high rate of change per hour. Outlet Performance and Design. .. . The physical laws of air distribution have, of course, a highly important influence upon the design of an acceptable distribution system. Refer to section Ventilating Jets in Air Distribution for a discussion of the theory, and to section Outlet Performance for some specific advice with regard to such features as throw, drop, capacity, temperature differential, room air motion, permissible noise level, smudging and their influence Upon practical air distribution. Outlets should perform efficiently and conform to the esthetic appearance 722 CHAPTER 31 1956 Guide of the room. The physical,appearance of'air outlets has been highly in fluenced by modem interior design, and to meet the demands of architects and engineers, ou tlets to be installed flush .with, the ceiling and outlets with built-in lighting as. well as square and linear-type outlets have been de veloped in the past years..Linear-type outlets and perforated ceilings or panels have the,advantage.of unobtrusive appearance. Procedure for Outlet Location and Selection . In determining outlet location and selecting the type of outlets, it is customary .to proceed as follows: .. 1. Study the plan,of the building andjnote the amount of air to be supplied to each;room.. (For computation of the required air quantity for heating and cooling refer to the formulas given in Chapters" 12, Heating Load and 13, Cooling Load. The amount of outside air introduced into the room must be checked against the ventila tion requirements of .state-or local codes).; . : ' . 2. Select number of outlets forjeach room, considering air-quantity required and distance available for throw, or. as radius .of diffusion. The same factors, as well as distance frOni floor ;level available as mounting height, structural characteristics ofthe space'and Consideration of. appearance, will determine the type of outlet used. 3. Arrange location of outlets in the room: Generally, the outlets must be evenly spiced to distribute the air uniformly throughout the room. More air, however, must be supplied and directed towards areas with exceptional heat gain or loss. An impor tant point to consider is the combination of proper outlet location and efficient duct design (see Chapter 32). Consult manufacturers' tables for recommended location and spacing of outlets. . Refer to Chapter 30 fOr a discussion of zoning and zone control. ;; 4. Select size of outlets according to air quantities handled, permissible throat or discharge velocities, or effective throw, taking into consideration other factors, such as.permissible noise level, etc. In order to determine whether the selection made will satisfy .the requirements of the job, type, size, and location of the outlet must be checked against 'manufacturers' ratings. The most important questions to be Con sidered are: '' - a. Will drafts be created because of divergence between rated throw (radius of ; diffusion) and distance between outlet and nearest obstacle of air stream . (wall, beam, column, etc.)? : b. Will drafts be created because of excessive cooling temperature differential or too low mounting height of the outlet? :; 'c.: Will drafts be created because of too low velocity energy of the air stream, . causing excessive downward air flow in cooling installations? d. Will the air pass through the outlet at too high a velocity and thereby cause an excessive increase in noise level? ' Balancing the System '.In designing a system, the engineer aims to size ducts and outlets in such a;.manner that the supply of air is properly distributed. He may, however, feel It. necessary to oversize certain trunks,-branches or outlets to allow flexibility or to permit future redistribution, so that the system as designed may not be self-balancing. Even if ducts are designed for self-balancing and outlets are properly selected, all air systems must be balanced, that is, the amount of air through supply ducts, supply outlets, outside air intakes, exhausts,^return outlets and ducts must-be properly adjusted so that the (^'quantities correspond closely with the design quantities. Balancing, therefore,,is-part of the field test procedure to which each air conditioning systern should Wsubjected in.order to determine whether the capacity and performance of the equipment'correspond with the design. For balancing, air systems may be equipped with dampers in supply, return, and outside air ducts, splitter dampers, or dampers in outlets. In selecting the desired type of damper or balancing method, the follow ing points:should be kept in mind: Air Distribution 723 1. Unfavorable effect on air stream and noise level should be avoided. This will often rule out blank-offs or dampers in .outlets, unless such dampers are of special design. . 2. It. should be possible to alter outlet volume without altering the direction of discharged air, and to measure the amount of air handled without difficulty. Blank ing off part of the area of supply outlets makes this difficult, ' Generally speaking, it is most satisfactory to install dampers at some distance back of outlets so as to avoid disturbing the air flow. Dampers in both supply and return ducts form the most flexible means of controlling supply of air to the room and static pressure within the room. (Refer to section Directional and Volume Control for discussion of various air distri bution control devices.) . Instruments for balancing include instruments for measuring air quan tities, static pressure, temperature and humidity. Commonly used instru ments are the rotating vane anemometer, deflecting vane anemometer, thermal anemometer, smoke gun, clamp type ammeter-voltmeter, sling psychrometer and thermometers. Pressure, humidity and temperature recorders are sometimes useful. The Pitot tube and a manometer may be used on higher velocities, but only with the technique prescribed for its use by the manufacturer forthe tube used. (See Air Flow Measurement in Chapter 52.) : The following balancing procedure is recommended for air systems: 1. Open all duct and outlet dampers. 2. Measure fan capacity. This can most often be done with a rotating vane ane mometer inside the fan inlet* plenum. For exhaust fans the discharge outlet will often serve. - 3. Measure fan motor input. 4. Determine approximate flow at each outlet. 5. Adjust outlets or branches so that outlet deviation (from design quantity) is approximately the same (percentagewise) as fan capacity deviation (from total design quantity). 6. Recheck fan capacity. 7. Adjust fan speed or main trunk damper to make fan capacity equal to design (ihe fan laws apply when changing speeds; quantity varies directly with speed,-- power input as the cube of speed). Use power input readings to check possibility of overloading the motor. The procedure outlined may be shortened depending on the type of in stallation. For instance, where many outlets serve one room, exact balancing of each outlet may not be required, so long as drafts, noise and temperature differences are checked. Experience and judgment are valuable in determin ing how carefully or thoroughly a system must be tested and adjusted. DIRECTIONAL AND VOLUME CONTROL Duct Approaches to Outlets The importance of the manner in which the air stream is introduced into the outlet cannot be overestimated. To obtain correct air distribution, the velocity of the air stream must be as uniform as possible over the entire connection to the duct, and perpendicular to the outlet face. No air outlet can compensate for improper duct approach. '\wa^ SriUe installed at the end of a horizontal duct and a ceiling outlet at the end of a vertical duct receive the air perpendicularly and at (for practical purposes) uniform velocity over the entire duct cross-section, provided the system is carefully designed. However, very few outlets are installed in this manner. Most- side wall outlets are installed either at the end of vertical ducts or in the side of horizontal ducts, and most ceiling 724 CHAPTER 31 1956 Guide outlets'are attached either directly to the bottom of horizontal ducts or to special vertical take-off-ducts which connect the outlet'with the horizontal duct. In all these cases, special devices for directing and equalizing the air flow,are necessary to obtain, proper, direction and distribution of the air. The influence of the duct approach on outlet performance has been in vestigated for vertical stack heads with plain openings12 or equipped with grilles13 and for side outlets on horizontal ducts.14 In the tests conducted with the stack heads it was found that it is necessary to provide splitters or guide vanes in the elbows at the top of the vertical stacks regardless of the shape of the elbows, whether, of rounded, square or expanding types. Cushion chambers at the top of the stack heads have no beneficial effect. Fig. 13 shows the direction of flow, distribution and velocity (measured 12 in. from: Opening) of the air for various types of stack heads tested, expand ing from a 14 x 6 in. stack,tb a 14 X 9 in. opening, Without grille. The air velocity for each was 500 fpm in the stack below' the elbow, but the direc- 'tion of flow, and the distribution pattern are generally indicative of per- Air Distribution 725 if the ducts are shallow and the connection areas are comparatively large. This will be the case when more than one outlet is installed on one duct run, and restrictions of duct areas must be avoided. In such cases good results have been obtained by using a series of vertical guide strips, installed at right angles to the direction of air approach in the outlet connection where it leaves the horizontal air duct. . Volume Control . Various methods are used to regulate volume of supply and return (ex haust) air. Some of these accomplish only minor changes in volume; most of them however permit a range of adjustment from maximum air supply to complete shut-off, , When selecting type and location of such dampers, the following points must be considered, especially when the volume control feature is to be located near the air outlet itself: (1) deflection of air stream by the damper; Fig. 13. Outlet Velocity and Air Direction Diagrams for Stack Heads with Expanding Outlets ' " , ' Stack 14 in. x 6 in. Outlets 14 in. x 9 in. Stack Velocity 500 fpm A. Rounded Throat and Hounded Back. * - C. Square Throat and Back and 6 Guide Vanes. B. Hounded Throat and Back and 2 Splitters. . ' formance obtainable, with nonexpanding elbows of similar shapes for a range of velocities 200 to 1400 fpm. In tests conducted with 3 x 10 in., 4x9 in., and 6 x 6 in. side outlets in a 6 x 20 in. horizontal duct at duct velocities of 200 to 1400 fpm (in the 6 x 20 in. section) it was found that multiple curved deflectors produced the best flow characteristics. Vertical guide strips in the outlet were not so effective as curved deflectors. A single scoop type deflector at the outlet did not improve the flow pattern obtained from a plain outlet, and was there fore not found to be desirable. Directional Control - '- Many devices for directing and equalizing air flow in side wall and ceil ing outlets are now commercially available, and should be used whenever necessary. They are indispensable for all side outlets in horizontal ducts and for most ceiling outlets. . . Ceiling outlets are usually installed below horizontal supply ducts so that the supply air has to make a 90-deg turn before entering the outlet itself. The shorter the connection between bottom of duct and outlet, the greater is the heed for directive devices, to obtain uniformity of flow. Generally speaking, conditions and remedy in such cases strongly resemble those for side outlets in horizontal air ducts. Ceiling ducts often have a rectangular cross-section, while the connections to the ceiling outlets are circular. It will then be quite difficult to install turning vanes successfully, particularly Fig. 14. Effect of Various Damper Arrangements Designed, for Straight Blow . (2) need and feasibility of directional control; (3) increase of noise level due to irregular and localized high air velocities caused by damper operation; The following types of volume control are most frequently encountered: 1 - Slide Damper. A single plate which can be pushed across the duct. Since its operation changes the free area of air passage in a one-sided manner, it should not be located near any air outlet, and its use is practicable only where no intermedi ate setting between full open and closed is required, ' 2. Bit-and-Miss Damper. Two slotted plates or discs, closely adjacent; by moving one of the two plates the respective slots may be opened or closed. This type of volume control may be installed- close to an air outlet and it is easy to operate, but its main disadvantage is that even in the open position the air passage area is blocked by at least 50 percent. This requires oversizing of the air outlet in order to avoid excessive increase of noise level. 3. Splitter Damper. A single blade sheet metal plate hinged at one edge, usually located at the branch connection of a duct or outlet. It is easy to operate, but often causes irregular air flow in the duct. When used in connection with, and near an out let, additional directional control is required. 4. Butterfly Damper. A single blade sheet metal plate hinged in the middle, usually located in a straight duct run. It is easier to handle than a splitter damper, since only half the motion is necessary to change its setting. However, if located too close to an air outlet, it is objectionable because its operation frequently results in a condition whereby two high velocity jets are created along the sides of the duct, or the air spills immediately downward into the occupied zone (see C Fig. 14). 5. Louver Dampers. Numerous designs have been developed incorporating a series of splitter or butterfly dampers across the duct or air outlet. Their main advantage consists in retaining greater uniformity of air flow, and in requiring lesB depth for installation. Some designs provide for louver blades moving in opposite directions, and while decreasing free air passage area, retain a constant air flow direction along the axis of the duct air outlet connection (see A and B in Fig. 14). 726 CHAPTER 31 1956 Guide Table 2. Recommended Return Intake Face Velocities .- ' Intake Location- ' ; ' Velocity ' Over Gross Area Fpm Within occupied zone, not near seats.......................... Undercutting of doors (through undercut area)____ 800 up 600-800 400-600 200-300 . 200-300 RETURN AND EXHAUST INTAKES The selection of return and exhaust intakes depends on: (1) velocity in occupied zone near intake; (2) permissible pressure drop through intake; and (3) noise. .. . 1. Velocity. The control of the room air motion for the maintenance of comfort conditions depends on the proper selection of the supply outlets. The effect of air flow through return intakes upon air movement in the room is slight. Air handled by the intake approaches the opening from all directions and its velocity decreases rapidly as the distance from the opening increases. Therefore, drafty conditions will rarely be encountered near return intakes. Recommended return intake face veloci ties are given in Table 2. ' " >. . 2. Permissible Pressure Drop. The permissible pressure drop will depend on the choice of the designer. Table 3 gives pressure drop through plain lattice intakes as a function of free area and face velocity. Proper pressure drop allowance should be made for control or directive devices. 3. Noise. The problem of noise generated by return intakes is the same as that for supply outlets. In computing resultant room noise levels from the operation of an air conditioning system, the return intake must be included as a part of the total grille area. The major difference between the supply outlets and return intakes is the frequent installation of the latter at ear level. When so located, it is recommended that the return intake velocity be not in excess of 75 percent of the maximum per missible outlet velocity. . i The location of return and exhaust intakes does not critically affect air motion, unless room air velocities .in the occupied zone near the intake exceed comfort limits. The locations of return or exhaust intakes are, how ever, important for obtaining the desired room temperature equalization. Ceiling locations for exhaust outlets are recommended for bars, kitchens, lavatories, dining rooms, club rooms, etc. where warm air will rise to the ceiling level. In heating installations, location of the return grilles in the ceiling or high on the wall is not recommended, as it may result in stratifica tion of the conditioned air, and--depending on the relative location of supply and return outlets--in short-circuiting. (Refer to section Outlet Location and Selection). Some ceiling outlets combine the supply and return openings in a single Table 3. Approximate Pressure Drops for Lattice Return Intakes Inches Water Gage--Standard Air ____ Per Cent Free Area 50 60 70 80 400 0.06 0.04 0.03 0.02 . Face Velocity, Fpm 500 . 0.09 0.06 0.05 - 0:03 600 0.13 0.09 0.07 0.05 700 0.17 0.12 0.09 0.07 800 0.22 0.16 0.12 0.09 900 0.28 0.20 0.15 0.11 . 1000 0.35 0.24' 0.18 0.14 Air Distribution Bo--- 727 Rear wall distribution '-Ceiling distribution Fig. 15. Air Distribution Methods for Theaters, Churches, and Auditoriums unit. This method is used for heating as well as. for cooling applications. However, the application for heating is more critical and requires considera tion of ceiling height, amount of outside wall area, and number of air changes required. In some cases, stratification iof warm air may cause shortcircuiting. (Refer to section Outlet Location and Selection). Floor locations of returns are used in heating installations for ceiling or side wall supply. When located so that air is draivn across exposed walls, the performance of the system may be somewhat improved. In general, floor locations tend to collect dirt and refuse.; --' ' ; Wall and door locations of exhaust outlets depending on their elevation, have the characteristics of either floor or ceiling returns. In large buildings with many small rooms, the return air may be brought through door grilles or door undercuts into the. corridors, and then to a common return or ex haust. The pressure, drop through door returns should not be excessive; otherwise the air distribution to the room may be seriously unbalanced with the opening or closing of the doors. Outward leakage through doors or windows cannot be counted upon for dependable results. . if-: SPECIFIC APPLICATIONS For theaters and auditoriums the air distribution methods used are the downward distribution system with ceiling diffusers, and the horizontal distribution system with ejector nozzles or wall diffusers. Fig. 15 shows both methods. Ceiling distribution is accomplished by ceiling outlets under main ceiling and balcony. It is indicated whenmain ceiling or balcony is cut up by architectural treatment or beams. The only critical points are under the balcony, and (occasionally) above the very, rear of the balcony, where ceiling heights are low and where direct impingement of air is some times a hazard. Wall or ejector distribution is particularly applicable for relatively long and narrow theaters. It is essential with this type of distribution that there , -o*- Winter convection current . Fig. 16. Distribution Methods for Small Rooms -: ' is iv)" afUslMtory for cooling. Unsatisfactory for heating in severe climates where the outside temperature consistently below 40 F, and single glass and uninsulated walls are prevalent. ` .... - B. Performance approximately that of A when small diffusers are used in bottom-of the duct! . v C. Satisfactory for cooling. Satisfactory for heating if direct radiation is properly controlled. -. An^Pf for both cooling and heating. The air should be discharged slightly away from the wall "u lor low velocities, should be fanned out parallel to the wall. ' - 728 CHAPTER 31 1956 Guide be no interference with the. movement of air throughout its entire path from the high velocity nozzles to.tlie front of the theater. The ceiling should be smooth, without projecting beams or obstructing ornamentation. For large theaters, relatively high velocities can be used. These will work satisfac torily if adjustable outlets are used to avoid areas, of local turbulence. In small or medium size theaters, it is sometimes practicable to use side . wall or front wall distribution. For the satisfactory operation of such a ro ll-* Ii- _ A. Rear Wall. High outlet velocity, satisfactory if properly designed; possibility of excessive air motion and drafts if used for wrong application. .. . B. Front Wall* High outlet velocity, results same as A. C. Front and Rear Walls. Moderate room air motion, outlet blows should sot impinge giving rise to down* drafts in center. . .. D. Center. Moderate air motion, no impingement of air streams. Good results. E. One Side. Moderate room air motion; should blow toward exposed wall. Good results. F. Ceiling. Low room air motion. Good results. Outlets should be selected of sufficient site to allow for blocking when not located in perfect squares. , . system during the winter heating period, the returns should preferably be located at the floor level andmear the front of the theater to prevent cold spots resulting from exposed wall convection or infiltration from exits. For multi-room buildings diagrams shown in Fig 16 illustrate distribution methods for small rooms with exposed wall, such as offices, hotel (guest) rooms, hospital (patients) rooms, apartments, etc. For o small store the cooling performance of various distribution methods is illustrated in Fig. 17. REFERENCES 1 Ventilation Jets in Room Air Distribution, by H. B. Nottage. Originally sub mitted as a Ph.D. thesis to Case Institute of Technology. (3 volumes) Loan copies available from A.S.H.A.E. Research Laboratory. (a) Volume I: Data and interpretations of tests for ventilation jets discharging horizontally into a large confining space. 131 pages + 67 fig. + 9 tables. (b) Volume II: Appendix A. Survey of the literature on the problems of ventila tion jets and the related fundamentals of turbulent flow. 499 pages incl. figs- (c) aVnodlutmabeleIsI.I: Appendixes B to H. General features of the experimental in.stalla tions, instrumentation, and operations, boundary-layer theory and work- energy treatment. (142 pages incl. figures). * A.S.H.V.E. Research Report, No. 1476--Air Velocities in Ventilating Jets, by G. L. Tuve (A.S.H.V.E. Transactions, Vol. 59, 1953, p. 261). : * Air Flow at Discharge of Fan-Pipe Lines in Mines, by G. E. McElroy (U- Bureau of Mines Report of Investigation R. I. 3730. November 1943, p. 19.) Air Distribution 729 * A.S.H.V.E. Research Report No. 1404--Comparative Study of Ventilating Jets from Various Types of Outlets, by Alfred Koestel, Philip Hermann, and G. L. Tuve (A.S.H.V.E. Transactions, Vol. 56, 1950, p. 459). * Throw of Air from Slots and Jets, by R. D. Madison and W. R. Elliot (A.S.H.V.E. Journal Section, Healing, Piping & Air Conditioning, November 1946, p. 108). * A.S.H.V.E. Research Report No. 1328--The Discharge of Air from a Long Slot, by Alfred Koestel and G. L. Tuve (A.S.H.V.E. Transactions, Vol. 54, 1948, p. 87). 7 A.S.H.V.E. Research Report, No. 1429--The Control of Air Streams from a Long Slot, by Alfred Koestel and C. Y. Young (A.S.H.V.E. Transactions, Vol. 57, 1951, p. 407). 5 A.S.H.V.E. Research Report No. 1366--Air Streams from Perforated Panels, by Alfred Koestel, Philip Hermann, and G. L. Tuve (A.S.H.V.E. Transactions, Vol. 55, 1949, p. 283). ' A.S.H.V.E. Research Report, No. 1443--Isothermal Ventilation--Jet Funda mentals, by H. B. Nottage, J. G. Slaby and W. P. Gojsza (A.S.H.V.E. Transactions, Vol. 58, 1952, p. 107). 10Entrainment in Ventilating Jets, unpublished paper (Case Institute of Tech nology). u Computation Charts and Theory for Rectangular and Circular Jets, by Harold G. Elrod, Jr. (A.S.H.V.E. Transactions, Vol. 60,.1954, p. 431). 17 A.S.H.V.E. Research Report No. 1155--The Performance of Stack Heads, by D. W. Nelson, D. H. Krans and A. F. Tuthill (A.S.H.V.E. Transactions, Vol. 46, 1940, p. 205). u A.S.H.V.E. Research Report No. 1206--Performance of Stack Heads Equipped with Grilles, by D. W. Nelson, D. H. Lamb and G. E. Smedberg (A.S.H.V.E. Tbansactions, Vol. 48, 1942, p. 279). M A.S.H.V.E. Research Report No. 1226--Performance of Side Outlets on Hori zontal Ducts, by D. W. Nelson and G. E. Smedberg (A.S.H.V.E. Transactions, Vol. 49, 1943, p. 58). BIBLIOGRAPHY Note: Many theoretical papers on air jets have been published which--though highly interesting and even fascinating to the specialist--are of little value to the practicing engineer. This guide to the literature on air distribution is, therefore, purposely restricted to papers resulting from research sponsored by The American Society op Heating and Air-Conditioning Engineers and other papers of inter est to engineers which are easily accessible to them. For an excellent survey of the entire literature the reader is referred to Reference 1. A.S.H.A.E. Research Laboratory A.S.H.V.E. Research in Air Distribution and Air Duct Friction, by Cyril Tasker. (A.S.H.V.E. Journal Section, Healing, Piping & Air Conditioning, April 1948, p. 125). A.S.H.VJD. Research Report--Ventilation Jets in Air Distribution, by H. B. Nottage (See Reference !) The following papers based on this report have been published: , A.S.H.V.E. Research Report No. 1360--Turbulence--A Fundamental Frontier in Air Distribution, by H. B. Nottage (A.S.H.V.E. Transactions, Vol. 55,1949, p. 193). A.S.H.V.E. Research Report No. 1402--A Simple Heated-Thermocouple Anemometer, by H. B. Not" (A.S.H.V.E. Transactions Vol. 56, 1950, p. 431). A.S.H.VJ2. Research Report No. 1443--Isothermal Ventilation-Jet Fundamentals, by H. B. Nottage, * G. Slaby, and W. P. Gojsza (A.S.H.V.E. Transactions, Vol. 58, 1952, p. 107). A.S.H.V.E. Research Report No. 1441--A V-Wire Direction Probe, by H. B. Nottage, J. G. Slaby. Md W. P. Gojsza (A-S.H.V.E. Transactions, Vol. 58, 3952, p. 79). - A.S.H.V.E. Research Report No. 1458--Outlet Turbulence Intensity as a Factor in Isothermal-Jet by H. B. Nottage, J. G. Slaby. and W. P. Gojssa (A.S.H.V.E. Transactions, Vol. 68, 1952, p. 343). t, A.S.H.V.E. Research Report No. 1461--A Smoke-Filament Technique for Experimental Research in Air Distribution, by H. B. Nottage, J. G. Slaby, and W. P. Gojsza (A.S.H.V.E. Transactions, Vol. 687 1952, p. 399). w A^S.H.V.E. Research Report No. 1459--Exploration of a Chilled Jet, by H. B. Nottage, J. G. Slaby, and w* P. Gojsza (A.S.H.V.E. Transactions, Vol. 58, 1952, p. 357). A-S.H.A.E. Cooperative Research at Case Institute of Technology A.S.H.V.E. Research Report No. 1140--The Use of Air Velocity Meters, by G. I>. Tuve, D. K. Wright, r- ad L. J. Seigel (A.S.H.V.E. Transactions, Vol. 45, 1939, p. 645). ._jA.S.H.V.E. Research Report No. 1162--Air Flow Measurements at Intake and Discharge Openings ana Grilles, by G. L. Tuve and D. K. Wright, Jr. (A.S.H.V.E. Transactions, Vol. 46,1940, p. 313). 730* CHAPTER 31 1956 Guide A.S.H.V.E. Research Report No. 1204--Eotrainment and Jet-Pump Action of Air Streams, by G. L. T.uve, G. B. Priester, and D. K. Wright, Jr. (A.S.H.V.E. Transactions, Vol- 48', 1842, p. 241). . A.S.H.V.E. Research Report.No; 1248--Control of Air Streams in L&rge Sp&ces, by G. L. Tuve and G. B. Priester (A.S.H.V.E. Transactions, Vol. 50, 1944,-p. 153). . ' A.S.H.V.E. Research Report No.^ZS-^-The Discharge of Air from a Loiig Slot, by Alfred Koestel and G. L--Tuve (AfS.H.V.E. Transactions, Vol. 54, 1948, p. 87).' ' ' A.S.H.V.E.'Research Report No; i366--r-Air Streams from Perforafced Panels, by Alfred Koestel, Philip Hermann and G. L. Tuve (A.S.H.-V.E. Transactions, Vol. 55,1940, j?. 383). - ' A.S.H.V.E. Research Report No. 1404--Comparative Study of Ventilating Jets from Various Types of Outlets, by Alfred Koestel, Philip Hermann, and G. L. Tuve (A-S.H.V.E. Transactions, Vol. 56, 1950, p;'459). "' '' . .............................. '- A.S.H.V.E. Research Report No.-1429--Thie Control of Air. Streams from a Long Slot, by Alfred Koeste, and C. Y. Young (A-S.H.V.E. Transactions, Vol. 57, 1951, p. 407). . A S.H1V.E. Research Report No. 1475--Air Velocities in Ventilating Jets, by G. L. Tuve (A.S.H.VE. Transactions, Vol. 59, 1953, p. 261). . A.S.H.A.E. Cooperative Research at Kansas State College A.S.H.V.E. Research Report No 1327--Downward Projection o! Heated Air, by Unn Helnnder and C. V.Jakowatz(A.S:H.V.E. Transactions, Vol* 54; 1948ip. 71); A.S.H.V.E. Research Report No. 1475 (In Cooperation with the Industrial Unit Heater Association)-- Maximum Downward Travel of Heated Jets from Standard Long Radius ASMS Nozzles, by Linn Helander, S: M. Yen, and R. E. Crank-(A.S.H.V.E. Transactions, VoLaQ, 1953, p. 241). A.S.H.A.E. Cooperative Research--General A.S.H.V.E. Research Reports No. 857, 911 and 965--Measurement of the Flowof Air Through Registers and Grilles, by E. L. Davies (A.S.H.V.E. Transactions, VoL 36, 1930, p. 201; Vol. 37, 1931, p. 619 and Vol. 39, 1933, p. 373). ......... : -' .. . A.S.H.V.E. Research Report No. 1076--Air Distribution from Side Wall Outlets, by D. W. Nelson and D. J. Stewart (A.S.H.V.E. Transactions, Vol. 44, 1938, p. 77). : A.S.H.V.E. Research Repqrt'No.1092--The-Flow of Air Through Exhaust Grilles, by A. M. Greene, Jr. and M. H. Dean (A.S.H.V.E. Transactions, Vol. 44, 1938, p. 387). -' A.S.H.V.E. Research Report No. 1155--The Performance of Stack Heads,-by D. W. Nelson, D. H. Krans, and A. F. Tuthill (A.S.H.V.E. Transactions, Vol. 46,1940, p. 206). . A.S.H.V.E. Research Report No. 1165--Development of Instruments for the Study of Air Distribution in Rooms, by A. P. Kratz, A. E. Hershey, and R. B. Engdahl (A.SJH.V.E. Transactions, Vol. 46, 1940, p 351). . A.S.H.V.E. Research Report No. 1206--Performance of Stack Heads Equipped with Grilles, by D. W. Nelson, D. H. Lamb and G. E. Smedberg (A.S.H.V.E. Transactions, Vol. 48, 1942, p. 279). A.S.H.V.E. Research Report No. 1226--Performance of Side Outlets on Horizontal Ducts, by D. W. Nelson and G. E. Smedberg (A.S.H.V.E. Transactions, Vol. 49, 1943, p. 58). Other Papers Presented at'A-S.H.A.E. Meetings A.S.H.V.E. Research Report No. 1051--The Noise Characteristics of Air Supply Outlets, by D. J. Stewart and G. F. Drake (A.S.H.V.E. Transactions, Vol. 43,1937, p. 81). A.S.H.V.E. Research Report No. 1158--Dirt Patterns on Walls, by R. A. Nielsen (A.S.H.V.E. Trans actAio.nSs.H, V.Vo.lE. .46R, e1s9e40a,rpc.h 247), Report No. 1361--Ba- lancing Air Delivery.of a System of Manifold Air Diffusers, by G. S. Dauphinee and Peter Argentieri (A.S.H.V.E. Transactions, Vol. 55, 1949, p. 213). ' A.S.H.V.E. Research Report No. 1362--Air Distribution and Draft, by John Rydberg and Per Norbfick (A.AS..SH..HV..VE..ET.rRanesseaacrtciohnRs,eVpoolr. t55N, 1o9. 4194,7p1--. 2R25o)o. m Air Distribution Research for Year 'Round Air Cwndi* turning. Part I--Supply Outlets at One High Sidewall Location, by S. F. Gilman, H. E. Straub, A. E; Her- shey, and R. B. Engdahl (A.S.H.V.E. Transactions, Vol. 59, 1953, p. 151). A.S.H.V.E. Research Report--Room Air Distribution Research for Year 'Round Air Conditioning, Part II--Supply Outlets at Three-Floor Locations, by H. E. Straub and S. F. Gilman (A.S.H.V.E. Transactions, Vol. 60, 1954, p. 248). Miscellaneous Articles Measuring Air Distribution and Grille Performance in Air Conditioning, by G. L. Tuve (A.S.H-V.E- Journal Section, Heating, Piping & Air Conditioning, November 1937, p. 700). .' Air Discharge from Narrow Slots, by F. F. Stevenson (Heating, Piping & Air Conditioning May 19^L P 308, and June 1941, p. 368. Discussed by J. R. Fellows and D. W. Nelson, loc. cit., September 1941, P- andV5e5r9t)ic. al Air Distribution in Tall Buildings, by Sturm (Heating, Pipin. g <fc Air Conditioning, June 1947, P 69 aEnfdficSieepnttemAbireDr 1is94tr7i,bpu.ti9o3n). in The atre. (Heating, Pipin'g and Air Conditioning, Question of the Month- August 1947, p. 107; September 1947, p. 113; November 1947, p. 103). Test Every Air Conditioning System, by L. T. Avery and J. Black. (Heating and Ventilating, June p. 9B6)a.lancing an Air Conditioning System,- by L. R. Phillips. (Refrigerating Engineering, July 1950, p- HDWhat is a Draft? (Heating. Piping dr Air Conditioning, Open for Discussion. May 1951, p. 67, July 19M F 71, SSeevpet.n1Q95u1e,spti.o6n9s, oJnanDuuacryts1a9n5d2, Gp.ri1ll1e3s,.M(Harecahtin19g5,2P, ipp.in73g).cfc Air Conditioning, Question of the Month. May 1952A, ipr.D1i0s6traibndutJiounlyS1tu95d2ie. sp,, b1y11R).. V. MarteHi and H. O. Scarlett (Heating, Piping <t Air Conditioning, No vember 1952,'p. 77. Discussed by W. O. Huebner, loc. cit. Jan. 1953, p. 119 and by the Authors, March 'W" p. 85). CHAPTER 32 AIR DUCT DESIGN Pressure Changes, ^Friction Losses,..Circular.Equivalents of Rectangular Ducts, Dynamic Losses, Pressure .Losses in Elbows, Pressure Losses in Divided-Flow Fittings, Losses Due to Area'Changes, Pressure Changes, Duct Design . Methods and Examples, Duct Construction Details, Heat Losses from Ducts IN THE design of air duct systems, the objective is to provide a system that, within prescribed limits of noise and space available for ducts, efficiently transmits the required flow rate of air (cfm) to each space while maintaining a proper balance between investment and operating cost. When the heating,1 cooling or ventilation load is established, the total flow. rate of air required can be determined by methods shown in Chapters 12 and 13. The problem is then to distribute the supply air properly among the spaces. ----- ; ; ; j . PRESSURE CHANGES ; Ductwork imposes resistance to air flow which must be overcome by the expenditure of mechanical energy; this energy is ordinarily supplied by a fan. The portion pf the air flow rate from the fan that is transmitted to a particular space is governed by the law that the loss in total pressure from the fan outlet must be the same along each air path. This also holds for the return-air system except that the loss in total pressure refers to the fan inlet. In air conditioning and ventilating work, the pressure differences are ordinarily so small that the equations for incompressible flow can be applied. Additional simplicity is obtained by considering the air to be at the standard density of 0.075 lb per cu ft. ' At any cross section in a. duct .the total pressure H is the sum of the static pressure P and the velocity pressure iK - Thus, . . ; .. . // = /> +II, ' (1) Pressures are considered in units of inches of water. The velocity pres sure is then given by ; ' Y(4005/ where V is defined by the equation (21 where . (3) y = mean velocity of flow, feet per minute. . Q -- air flow rate, cubic feet per minute. . A = cross-sectional area of duct, square feet. The total pressure H is a measure of the total mechanical energy at a cross section. In any duct system, the total pressure always decreases in ' 731 732; CHAPTER 32 1956 Guide the direction of the air flow. Static and velocity pressure are mutually convertible and either can increase or decrease in the direction of flow. Typical pressure changes in;a duct system are illustrated in Fig. 1. Be tween Sections A and B, the static and total pressures decrease uniformly because of friction between air molecules along the sides of the duct. Pressure losses in straight pipes are termed friction losses and are charac terized by dependence upon Reynolds number. : (See Chapter 4.) Section BC is a converging section. The duct area is reduced, and con sequently the flow is accelerated. This is a stable and efficient process and Fig. 1. Pressure Changes During Flow in Ducts the loss in total pressure is seen to be small. The marked decrease in static pressure is caused by conversion of static to velocity pressure in accordance with the equations above. . Section CD presents the friction loss in the section of smaller duct. Since friction losses increase with nearly the square of the velocity, the, pressure line falls much more rapidly than in Section AB. ' An abrupt expansion occurs at DE. The duct area is abruptly increased and the flow decelerated. The process is an inefficient one and the loss in total pressure is therefore large. The velocity pressure is decreased at E in accordance with Equations 2 and 3, and the static pressure rises. This and the pressure loss at BC are termed dynamic losses, and are characterized by being essentially independent of Reynolds number. Dynamic losses occur because of changes in the direction or velocity of the air, and hence, occur at duct transitions, bends (elbows) and obstructions such as dampers. As will be shown later, dynamic losses can be specified in terms of a con stant times the velocity pressure at a reference cross section. Beginning at Section E the velocity pressure is constant, and the static, and total pressures again decrease uniformly due to wall friction. The static pressure at F is zero, as referred to atmospheric. The total pressure is the velocity pressure and is a measure of the kinetic energy of the stream as it discharges from the duct. . The distinction between static and total pressure is important, because the former is conventionally used as the basis for system design, but.the,, latter dictates the actual mechanical energy that must be supplied to the Air Duct Design 733 system. Note in Fig. 1 that the static pressure decreases and then increases in the direction of. flow. Moreover, it even becomes negative (below at-, mospheric). Therefore, in dealing with static pressures, distinction must always be made between static pressure loss (Section AB) and static pres sure change as a result of conversion of velocity pressure (Section BC). . FRICTION LOSSES Pressure drop in a straight duct is caused, by surface friction, and this friction loss is most readily calculated by means of the Air Friction Charts, Figs. 2 and 3, covering volume ranges of 10 to 2000cfm, and 1000 to 100,000 cfm, respectively. These charts were developed by; the A.S.H.A.E. Re search Laboratory.1 . :. ; : ' The charts, Figs. 2 and 3, were constructed from the basic flow equation for the pressure loss in circular ducts (see Chapter 4): , . "> = /(!) ; ' ' . (4) where ;' Ht = head loss due to friction, inches of water. . / = a non-dimensional friction coefficient, which for air conditioning work de- pendsTlpon Reynolds number and the relative roughness of the conduit. Approximate values of / were taken from the work of Moody* where e = 0.0005 ft. (See Chapter 4, Fig. 4, Relation Between Friction Factor and Reynolds number.) It is numerically equivalent to the reciprocal of the number of duct diameters required to cause.a pressure loss equivalent to one velocity pressure. ' l = length of conduit, feet. D = inside diameter of conduit, feet. Hr = velocity pressure of mean velocity, inches of water. The air friction chart is bared on standard air with a density of 0.075 lb per cu ft, flowing through average, clean, round, galvanized metal ducts having approximately 40 joints per 100 ft. Fig. 2 should not be used to obtain values below the charts by extrapolation, because critical flow would occur in this region and values so obtained would be unreliable. For the average application, values from the charts should have sufficient preci sion, without corrections, for any; air temperature from 50 F to 90. F, for any relative humidity, and for any normal variation in barometric pressure. For widely varying air pressures or temperatures, or for unusual duct con ditions, the friction values obtained from the chart should be corrected.3 For ordinary ventilating work, friction may be assumed to vary directly as the density without serious error, and therefore where ho = friction loss under actual .operating conditions, any consistent units. A, = friction loss under standard conditions,, any consistent units. . Po = density of air under actual operating conditions, any consistent units. p = density of air under standard conditions, any consistent units. For ducts of other than standard sheet metal construction, correction 734 CHAPTER 32 1956 Guide Air. Duct Design - 7o5 CU FT OF AIR PER MINUTE CU FT OF AIR PER MINUTE Fig. 2. Friction of Air in Straight Ducts For Volumes of 10 to 2000 cfm (Based on Standard Air of 0.075 ib per cu ft densityflowing through average, clean,round, galvanised metal acts having approximately 40 joints per 100 It.) Caution: Do not extrapolate below chart. _ Fig. 3. Friction of Air in Straight Ducts For Volumes of 1000 to 100,000 cfm (Baaed on Standard Air of 0.075 lb per cu ft density flowing through average, clean, round, galvanized metal dueta having approximately 40 joints per 100 ft.) factors may be obtained from Fig. 4.3 Most ductwork today is fabricated from galvanized iron or aluminum sheet metal, or flexible tubing. Fig. 5 presents in graphical form the recommended correction factors for alumi num ductwork.4 The correct friction loss for ducts other than sheet metal 736 CHAPTER 32 1956 Guide tained from Fig. 4. construction may be determined by multiplying the losses obtained from Figs. 2 and 3 by these factors. . Accurate experimental data on the absolute roughness for flexible tubing are not yet available. Example 1 illustrates the use of Fig. 3 to determine friction loss in a galvanized sheet metal duct. Examples 2 and 3 illustrate the use of Figs. 4 and 5 in applying correction factors for ducts of other than sheet metal construction.; , Example l: Determine the friction loss when circulating 10,000 cfm of air through 75 ft of 24 in. diameter galvanized duct. Solution: Find 10,000 cfm on the left scale of Fig. 3 and move horizontally right to the diagonal line marked 24 in. The other intersecting diagonal shows that the velocity in the pipe is 3200 fpm. Directly below the intersection it is found that the friction per 100 ft is 0.50 m.; then for 75 ft the friction will be 0.75 X 0.50 = 0.38 in. In a like manner, any two variables may be determined by the intersection of the fines representing the other two variables. too Fig. 5. Correction Factors for Aluminum Duct Air Duct Design 737 axu.mpie z: n uie auct in itxample 1 is very rough, instead of galvanized, with 40 joints per 100 ft, find the total friction. Solution: On Fig. 4 find (by interpolation between 12 in. and 40 in. pipe) the intersection of the 24 in. very rough pipe line and the 3200 fpm velocity ordinate, and at the left margin read a correction factor of 2. The friction loss in the rough duct is therefore 2 X 0.38 = 0.76 in. Example S: If the duct in Example 1 is made of aluminum, instead of galvanized iron, find the total friction. Solution: On Fig. 5 find (by interpolation between 12-in. and 36-in. pipe) the intersection of the 24-in. line and the 3200-fpm velocity ordinate, and at the left margin read a correction factor of 0.91. The friction loss in the aluminum duct is therefore 0.91 X 0.38 = 0.35 in. CIRCULAR EQUIVALENTS OF RECTANGULAR DUCTS An air handling system is usually sized first for round ducts. Then, if rectangular ducts are desired, their sizes are selected to provide air carry ing capacities equivalent to those of the round ducts originally selected. A recent comprehensive study at the A.S.H.A.E. Research Laboratory proved that for most practical purposes rectangular ducts of aspect ratios not exceeding 8:1 will have the same static friction pressure loss for equal lengths and mean velocities of flow as a circular duct of the same hydraulic diameter. When duct sizes are expressed in terms of hydraulic diameter, and when equations for friction loss in round and rectangular ducts are equated for equal flow rate and equal length. Equation 6 giving the circu lar equivalent of a rectangular duct is obtained.5 where (oft)0* 1.30 (a -f ft)-> = 1.30 (aft)5 (o + 6) (6) --- ' *wuttuguwr uuut, inenes. ft = length of adjacent side of rectangular duct, inches. d, = circular equivalent of a rectangular duct for equal friction and capacity, inches. Table 1 gives the circular equivalents of rectangular ducts for equal friction and capacity for aspect ratios not greater than 11.7:1 based on Equation 6.5 . Multiplying or dividing the length of each side of a duct by a constant is the same as multiplying or dividing the equivalent round size by the same constant. Thus, if the circular equivalent of an 80- x 24-in. duct is required, it will be twice that of a 40- x 12-in. duct, or 2 x 23.0 = 46.0 in. Table 1. Circular Equivalents of Rectangular Ducts fob Equal Friction Dimensions in Inches OIDE Rectan 4.0 gular Duct 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 -------- 3.0 3.5 4.0 4.5 5.0 5.5 3.8 4.1 4.4 4.6 4.9 5.1 4.0 4.3 4.6 4.9 5.2 5.4 4.2 4.6 4.9 5.2 5.5 5.7 4.4 4.8 5.1 5.4 5.7 6.0 4.6 5.0 5.3 5.6 6.0 6.3 4.8 5.2 5.5 5.9 6.2 6.5 4.9 5.3 5.7 6.1 6.4 6.8 5.1 5.5 5.9 6.3 6.7 7.0 5.2 5.7 6.1 6.5 6.9 7.2 5.4 5.8 6.3 6.7 7.1 7.4 5.5 6.0 6.4 6.9 7.3 7.6 5.6 6.1 6.6 7.0 7.4 7.8 5.7 6.3 6.8 7.2 7.6 8.0 taw .lii,.:': 738 CHAPTER 32 1956 Guide Table 1. Circular Equivalents of Rectangular Ducts for Equal Friction. and Capacity (Continued) , - Dimensions in Inches Side RECTAN- 10.0 10.5 nj> 1U . 12.0. 12.5 .13.0 13.5 14.0 14.5 .15.0 15.5 16.0 dtfLAB-DUCT .. 3.0 . 5.7 5.9 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 7.0 - 3.5 . 6.3 6.4 6.5 6.7 6.8 6.9 7.0 7.1 7.2 7.3 7.4 7.5 .7.6 4.0 6.8 6.9 7.1 7.2 7.3 7.5 7.6 7.7 7.8 7.9 8.1 8.2 8.3 4.5 7.2 7.4 7.5 7.7 7.8 8.0 8.1 8.2 8.4 8.5 8.6 8.7 8.9 5.0 7.6 7.8 8.0 8.1 8.3 8.4 8.6 8.7 8.9 9.0 9.1 9.3 9.4 5.5 8.0 8.2 8.4 8.6 .8.7 8.8 9.0 9.2 9.4 9.5 9.6. 9.8 9.8 Side .. TAN- 6 7 8 9 10 11 12 13 14 15 16 17 18 19 GUIiAR Duct __ .6 '7 8 9 6.6 7.1 7.7 7.5 8.2 8.8 8.0 8.6 9.3 9.9 . 10 8.4 9.1 9.8 10.4 10.9 11 8;8 9.5 10.2 10.8 11.4 12.0 12 9.1 9.9 10:7 11.3 11.9 12.5 13.1 13 9.5 10.3 11.1 11.8 12.4 13.0 13.6 14.2 14 9.8 10.7 11.5 12.2 12.9 13.5 14.2 14.7 15.3 15 10.1 11.0 11.8 12.6 13;3 14.0 14.6 15.3 15.8 16.4 16 10.4 11.4 12.2 13.0 13.7 14.4 15.1 15.7 16.3 16.9 17.5 17 10.7 11.7 12.5 13.4 14.1 14.9 15.5 16.1 16.8 17.4 18.0 18.6 18 19 20 22 11.0 11.2 11.9 12.2 12.9 13.2 13.7 14.1 14.5 14.9 15.3 15.6 16.0 16.4 16.6 17.1 17.3 17.8 17.9 18.4 18.5 19.0 19.1 19.6 19.7 20.2 >0.8 11.5 12.5 13.5 14.4 15.2 15.9 16.8 17.5 18.2 18.8 19.5 20.1 20.7 21.3 12.0 13.1 14.1 15.0 15.9 16.7 17.6 18.3 19.1 19.7 20.4 21.0 21.7 22.3 24 12.4 13.6 14.6 15.6 16,6 17.5 18.3 19.1 19.8 20.6 21.3 21.9 22.6 23.2 26 28 30 J2.8 13.2 14.1 14.5 15.2 15.6 16.2 17.2 16.7 17.7 18.1 18.7 19.0 19.8 20.6 21.4 19.6 20.5 21.3 22.1 22.1 22.8 23.5 24.1 22.9 23.6 24.4 25.0 13.6 14.9 16.1 17.2 18.3 19.3 20.2 21.1 22.0 22.9 23.7 24.4 25.2 25.9 32 . 14.0 15.3 16.5 17.7 18.8 19.8 20.8 21.8 22.7 23.6 24.4 25.2 26.0 26.7 34 36 38 14.4 14.7 15.7 16.1 17.0 17.4 18.2 18.6 19.3 19.8 20.4 20.9 21.4 21.9 22.4 23.0 23.3 23.9 24.2 24.8 25.1 25.8 25.9 26.6 26.7 27.S 27.4 28.3 15.0 16:4 17.8 19.0 20.3 21.4 22.5 23.5 24.5 25.4 26.4 27.3 28.1 29.C 40 42 44 15.3 15.6 15.9 16.8 17.1 17.5 18.2 18.5 18.9 19.4 19.8 20.2 20.7 21.1 21.5 21.9 22.3 22.7 23.0 23.4 23.9 24.0 24.5 25.0 25.1 25.6 26.1 26^0 26.6 27.2 27.0 27.6 28.2 27.9 28.5 29.1 28.8 29.7 29.4 30.4 30.0 iji c 46 16.2 17.8 19.2 20.6 21.9 23.2 24.3 25.5 26.7 27.7 28.7 29.7 30.6 31. 48 50 52 54 16.5 16.8 17.0 17.3 18.1 18.4 18.7 19.0 19.6 19.9 20.2 20.5 20.9 21.3 21.6 22.0 22.3 22.7 23.1 23.4 23.6 2410 24.4 24.8 24.8 25.2 25.6 26.1 26.0 26.4 26.8 27.3 27.2 27.6 28.1 28.5 28.2 28.7 29.2 29.7 29.2 29.8 30.3 30.8 30.2 30.8 31.4 31.9 31.2 32.5 31.8 32. 32.4 33.4 32.9 33.9 56 58 60 62 17.6 17.8 18.1 19.3 19.5 19.3 20.1 20.9 21.1 21.4 21.7 22.4 22.7 23.0 23.3 23.8 24.2 24.5 24.8 25.2 25.5 25.8 26.2 26.5 26.9 27.3 27.6 27.7 28.2 28.7 29.0 28.9 29.3 29.8 30.2 30.1 30.5 31.0 31.4 31.2 31.7 32.2 32.6 32.4 32.9 33.4 33.8 33.4 34. 33.9 35.0 34.5 35.! 35.0 36.0 64 66 68 70 18.6 18.8 19:0 19.2 20.3 20.6 20.8 21. 22.0 22.3 22.5 22.8 23.6 23.9 24.2 24.5 25.2 25.5 25.8 26.1 26.5 26.9 27.3 27.6 27.9 28.3 28.7 29.1 29.3 29.7 30.1 30.4 30.6 31.0 31.4 31.8 31.8 32.2 32.6 33.1 33.1 33.5 33.9 34.3 34.2 34.7 35.1 35.6 35.5 36.5 35.9 37.0 36.3 37.5 36.8 37.9 for E q u a l F r ic tio n an d Ca p a c it y (C o n c lu d e d ) ISSK SRSS iiii `'NNt. ie^=--g-_ ----------- - a' R2gg Sggg gsg SS5 *>*'* cthow" I"88 -oSSS SSSS Sg- - jjjjg - **. -P""" -ogsg SSSS fesgg g-rfg . ** <oco ei?p?eO WWTON -r>"ngo~S--y3S. S__S__S_Sfeg ggg~ jjjjji 22 |^cOo>(3 a V S=SS SSSS SSSS gg;; ^^oso idnoi && =5'<? . <e>-r^--oT=;--5T7S-;--------------- SSSS sssi SSm __ Oi,-. S__g--SS----g---TMg---g-o--g---_------fo-e->-g--os sssgOCg&C4 SSSS 6**8 SSSS SSS sss siss ^555 5"55 -l"gg 8WS.8SSS SSSS SSS -o.--6---Os.Os--soc.sb -os-ops.ms- Vs, ,m_ --- *j--w------^; -wS---S--2~-- SmSIS59r*s-^*-oeorcooro~tSexo-rt td NCQOoi ._eo_____eo8 C5 J* CQ m 228 2222 t^ooooo* KOSS-- aei SfSS'P --- STS *cae ___ : oo fiasco e SSeS^MS S53S g::g:s:t -2r^2jj~2g"5s2 2ss5s2s" s~:e qc<?; Craoo^. ~o.ao- o.^<,CT ^ J ?sss SSSS gggg =vv: isis SSSS SSSS' 5552 2""~ """ SS3SS SSSS SSSS SSSS SSgg ggsg ggg, gggs ssss sss 740 CHAPTER 32 1956 Guide Table 2. Pressure Losses due to Elbows (Additional Equivalent Losses in Excess of Friction to Intersection of Center Lines) TYPE N-DEG. ILLUSTRATION 90-0EC. ROUND - SECTION . : 90-OEG. : RECTANGULAR SECTION 90-DEC. SQUARE SECTION . WITH HHI- 5PLITTCR VANES MITER ', WITH . TURNING VANES ^ FORMED - PRESSURE LOSS CONDITIONS c* 1 Wo 1 -/w RECTANGULAR OR ROUND; WITH OR WITH 90 T9'0- i VALUE "OR >EG EL0Crw* SIMILAR OUT VANES MITER 1.30* 65* fi/0=0.5 0.90 0.7S 0.45 23 . 1.0 1.5 2.0 0.33 17 0.24 12 0. 19 10 H/w R/W 'MITER 0-3 0.25 0.75 1.0 . .1.5 MITER 0.5 < t.u h 'MITER 0.5 ,0 0.75 1.0 O.S 'MITER O.S 4.6 0.73 li.a fW H*M MITER O.S 0.5 0.4 0.7 0.6 (.0 (.0. 1.3 MITER O.S O.S 0.5 0.2 0.4 0.75 0.4 0*7 1.0 0.7 1.0 1.5 1.3.1.6 1.25* 1.25 0.60 0.37 0.19 1.47 1.10* 0.50 0.26 0.13 1.50 1.00 0.41 0.22 0.09 1.36 0. 96 0.37 0.19 0.07 0.70* 0.13 0. 12 0.45 0.12 0.10. 0.15 25* 25 12 7 4 49 40 16 9 4 7S 50 21 .11 . 4.5 HO 65 43 17 6 28TM 19 12 7.2 22,e 16 PLATE VANES 0.35* KORUEO VANES 0.10* MITER TEE WITH VANES - RADIUS CONSIDER EQUAL TO A SIMILAR ELBOW. BASE LOSS ON ENTERING VELOCITY. . ' a Values based on / values of approximately 0.02. . . b Values calculated from L/D and L/W values of Reference 6 for / = 0.02. ' Note: Superscript numbers refer to references at end of chapter. DYNAMIC LOSSES . Wherever eddying flow is present, brought about by sudden changes in .the direction or magnitude of .the velocity of the air flowing, a greater loss in pressure takes place than would occur in a steady flow through a similar length of straight duct having a uniform cross section. The amount of this loss,' in excess of straight duct friction, is termed dynamic loss. Al though dynamic losses may be assumed to be caused by changes in area actually occupied by the air flow, for convenience they are divided into two ..general classes: (1) those caused by changes in direction of the duct and (2) those caused by changes in cross-sectional area of the duct. Air Duct Design 741 where =4--yHi V.4005/ . (7) Hd = dynamic pressure loss, inches of water. V = mean velocity of air flow, feet per minute. C = an experimentally determined constant (dynamic loss coefficient). Where different areas are involved, subscripts are used to denote the area to which the coefficient applies, as Cj for inlet area, Ci for outlet area, and Co for orifice area. . .. The dynamic loss coefficient C is dimensionless and represents the num ber of velocity heads lost at the conduit transition or bend. Values of the dynamic loss coefficient for elbows and other duct elements have been de termined experimentally and are given in Tables 2 and 3. It should be 742 CHAPTER 32 : 1956 Guide Air Duct Design 743 LossFig. 8. in 90-Deq Elbows of Round Cross Section for which the dynamic losses are often grouped with the friction losses to facilitate design calculations. An A.S.H.A.E. survey6 of available data has indicated that the method of expressing the combined dynamic and friction losses due to an elbow as equivalent to the loss in a length L of similar straight duct is justified for design purposes, owing to the relation of the loss to the corresponding friction factor,/. Fig. 7 gives the additional equivalent length of duct in terms of widths IF for elbows in rectangular ducts; Fig. 8 gives the equivalent length of duct in terms of diameters 2).for round ducts. When these curves for additional equivalent length are used, the straight lengths of duct between elbows should be measured to the intersection of 'their center lines. Example 4: (Use of Fig. 7 for the calculation of elbow losses.) Given the portion of a duct system shown in Fig. 9, it is required to determine the pressure loss between points A and D. Air at standard conditions is being supplied at the rate of 2000 cfm in a 6- by 24-in. galvanized duct of average construction. El bows No. 1 and 2 have centerline radii of 18 and 9 in., respectively. Solution: For elbow No. 1 the radius ratio is ^ = ^7 = 0.75 and the aspect ratio a 6 W i -24 is yy- = -- = 0.25. The additional equivalent length for elbow No. 1 in terms of W Fig. 9. Portion op Duct System fob Example 4 744 CHAPTER 32 1956 Guide is obtained from Fig. 7: (L/W)i = 11.5. Thus Lt = 11.5 X 24/12 = 23 additional equivalent feet. Similarly for elbow No . 2, the ratio radius is R 9^ = 1.5 and IT OA the aspect ratio is ^ = -g- = 4.0; Fig. 7 gives (L/W)t = 6, so ij = 6 X 6/12 = 3 additional equivalent feet. The total length of the straight runs from A to D is 1 = 1a-b + 1b-c + 1c-d = 7 -f 20 + 5 = 32 ft and the additional equivalent length due to the elbows is L = Li + it = 23 3 = 26 ft. Thus the equivalent length of the system from A to D is 1 + L = 32 -f 26 = 58 ft of 6 by 24 in. duct: The diameter of a.circular duct, equivalent in friction and capacity to this rec tangular duct, is 12.4 in. as given by the table of circular equivalents, Table 1. At a delivery rate of 2000 cfm, the A.S.H.A.E. Friction Chart, Fig. 3, gives a loss of 0.6 in. of water per 100 ft. of 12.4-in. diameter duct. Thus the loss from A to D is 0.6 X 58/100 = 0.348 in. of water. The use of elbows of radius ratio, R/W = 1.5, is considered good practice with respect to both installation and operation. In a given rectangular duct 6 by 24 in., for example, the elbow loss will be greater for a flat bend where the aspect ratio, H/W = 1/4, then if the bend of the same radius ratio had been made in the plane of the narrow dimension giving an aspect ratio, H/W = 4. Data now available for losses in compound bends,1 8 where two or more elbows are close together, do not warrant refinement of design calculations beyond use of the sum of the losses for the individual elbows. Actually, the losses are somewhat less than for two bends when they are placed to form a TJ bend, and somewhat more when they form a reversed, or S bend. Where angles of other than 90-deg bend are encountered, the loss may be considered as directly proportional to the angle of bend. Losses8 for elbows discharging air directly into a large space are higher-than those given for elbows within duct systems. Turning vanes may be advantageously employed in elbows, both to re duce the pressure loss and to provide a more uniform velocity distribution downstream from the bend8-10. Vanes and concentric splitters are par ticularly recommended where miter elbows are used, because even the simplest vane forms will produce a substantial saving in pressure loss. Pressure loss data for elbows, both with and without vanes, are tabulated in condensed form, in Table 2. , PRESSURE LOSSES IN DIVIDED-FLOW FITTINGS Data for losses at branch take-offs are quite meager and therefore an A.S.H.A.E. cooperative investigation is under way for the purpose of ob taining additional data on losses for typical take-off fittings. Analysis11 of available data indicates that the loss in the straight-through section is about 35 percent of that for abrupt expansion (see next section, Losses Due to Area Changes) involving the same ratios of velocities; that the loss in the diverted-flow section depends on the ratio of the velocity of diverted flow to total flow and on the angle the take-off makes with the main, and is at a minimum for a natural relation that exists between these two variables.' That is, there is a natural angle of efflux corresponding to the velocity-, ratio. Some representative branch losses are given in Table 4. LOSSES DUE TO AREA CHANGES Area changes in ducts, generally unavoidable, are necessitated frequently by the building construction or changes.in the volume of air carried. (Ex perimental investigations18 13 14 15 of pressure changes, and pressure losses Air Duct Design 745 Table 4. Ratio of Pressure Loss to Branch Velocity Pressure Tark-off Angle 90-deg 60-deg 45-deg orRatio Velocity in Bbanch to Velocity in Main Doer 0.4 0.6 0.8 1.0 1.5 2.0 3.0 6.5 5.0 3.5 3.1 2.2 1.3 2.0 1.3 0.64 1.5 0.77 0.43 0.95 0.47 0.40 0 74 0 47 0.45 0.62 0.58 0.54 ,,,, ui uixo iott oi uucl cross sections, indicate that the excess pres sure loss over the normal friction loss is a dynamic loss due to a faster stream expanding into a slower stream, as determined by the actual areas occupied by the flow rather than the areas of the duct. No perceptible dynamic loss is due to the converging of the air stream itself where the flow is contracted, but the air stream continues to converge beyond the edge of the contraction and reaches a minimum at the vena contracta. For contraction, therefore, the dynamic loss is caused by expansion from the vena contracta to the full area following the contraction. Abrupt contraction in area may therefore be considered.as a special condition of abrupt expansion. Fig. 10 illustrates (a) abrupt enlargement and (b) abrupt contraction. For a sudden symmetrical enlargement, a theoretical expression for the loss is H. where (Vi - V,) 4005 (8) Bm = pressure loss due to sudden enlargement, based on standard air, inches of water. Vi = velocity of standard air in the inlet duct, feet per minute. Vi = velocity of standard air in the outlet duct, feet per minute. Ai = area of the inlet duct, square feet. At = area of the outlet duct, square feet: Ci = loss coefficient based on area A . Ci = loss coefficient based on area A j . For a gradual symmetrical enlargement, Equation 8 changes to where (9) = pressure loss due to gradual enlargement, inches of water. Ct = coefficient of loss, as ratio of loss to loss for abrupt expansion, dependent upon the total angle included between the sides of the duct. 10. Air Flow at Abrupt Enlargement or Contraction of Air Stream 746 CHAPTER 32 1956 Guide The Joss for a sudden symmetrical contraction can be expressed as where He =* pressure loss due to sudden contraction (Fig. 10b) Co = loss coefficient based on orifice area A0 Vo -- velocity of air through orifice, feet per minute. . The loss for a gradual symmetrical contraction can be similarly expressed as . - '(;*)' <n> : where the coefficient of loss, C2, depends on the included angle of the sides of the duct and the sharpness of the edges at the junction of taper to follow ing duct section. Pressure loss data for a variety of duct elements are given in Table 3. DUCT DESIGN The following discussion refers to ducts for commercial and industrial heating, ventilating, and air conditioning systems of the central station type. The design procedures given yield the static pressure required to ` overcome the resistance of the ductwork, including the supply outlets and return intakes. The fan selected for the duct system must not only pro duce this pressure but also the additional pressure required by the central equipment such as washers or spray chambers, heating or cooling coils, and filters. Pressure losses of these components should be obtained from the manufacturers' catalogs. - Special duct design procedures for heating ducts used in residences can be found in Chapter 19, Gravity Warm Air Systems, and Chapter 20, Forced Warm Air Systems. The design of ducts in industrial exhaust systems is discussed in Chapter 46. . General rules which should be followed in the design are: 1.The air should be conveyed as directly as possible at the permissible velocities to obtain the desired results with minimum noise and greatest economy of power, material and space. . 2. Sudden changes in the direction or velocity of the air should be avoided. When sudden changes are necessary at bends, turning vanes should be used to minimise the pressure loss. 3. Diverging transition pieces should be made as gradual as practicable. As shown in the section on area changes, losses in abrupt enlargements are high and therefore such transitions should be avoided. The included angle of divergence for enlargement should not exceed 20 deg. Losses in contractions are low but the in cluded angle of convergence should not be greater than 60 deg. 4. Where the greatest air carrying capacity per square foot of sheet metal is desired, rectangular ducts should be made as nearly square as possible. Aspect ratios (ratio of width to depth) greater than 10 to 1 should be avoided. 5. Ducts should be constructed of smooth material, such as steel or aluminum sheet metal. For ducts made from other materials, proper allowance for the change in roughness should be made.* . 6. Through the design procedures which follow, a reasonably precise estimate of. the flow resistances offered by the system can be obtained. However, it should be recognized that in actual installations, resistances may vary considerably front the Air Duct Design 747 calculated values because of variation in the smoothnessiof materials, types of joints used, and the ability of workmen to fabricate the system in accordance with the de sign. Fans and motors should therefore be selected to provide at least a slight factor of safety, and dampers should be installed in each branch outlet for balancing the system. . . Procedure for Duct Design The general procedure is as follows: __________ j-------uuiiuiu5 uu arrange LUC pUblViOUS UI me SUppiy OUtletS to provide proper distribution of air within each space. Select outlet sizes from manufacturers* catalog data. . .: :. 2. Draw a sketch of the most convenient system.of ductwork, connecting the supply outlets and return intakes with the.central station apparatus, taking cog- Table 5. Recommended and Maximum Duct Velocities Recommended Velocities, fpm Maximum Velocities, fpm Designation Outside Air Intakes* Filters* Heating Coils* Air Washers Suction Connections Fan Outlets Main Ducts Branch Ducts Branch Risers Residences Schools, Theaters, Public Buildings Industrial Buildings Residences . Schools, : Theaters, Public 'Buildings; Industrial Buildings 500 250 450 500 300 500 '500 350 600 800 300 500 : 900 350. 600. 1200 350 700 500 500 500 : 700 . 800 1000 1000-1600 1300-2000 1600-2400 500 900 1700 500 `500 1000 1400 ' 1500-2200 1700-2800 700-900 600 500 1000-1300 1200-1800 600-900 800-1000 600-700 800 800-1200 1100-1600 1300-2200 700-1000 800-1300 1000-1800 650-800 800-1200 1000-1600 * These velocities are for total face area, not the net free area: other velodtiea in table are for net free area .__ ______ ...........avwiuiug an uustructions m sieei worK and equipment, and at the same time maintaining a simple design. ' . ' . 3. Calculate the sizes of all main and branch ducts by one of the procedures given in the following section. 4. Determine the total pressure requirement of the supply and return duct sys tems. Although the loss in total pressure of each duet run connecting the fan and each supply outlet (or return intake) should be calculated and made the same for all runs, ordinarily only the pressure loss of the duct run apparently having the greatest resistance is referred to as the pressure loss of the duct system. Dampers are relied upon for balancing the system. Design Velocities .. It is not possible to give specific rules for selecting duct velocities. Since the fan horsepower increases approximately as the square of the velocity, and noise generation increases with static pressure, velocities should, be kept low for quiet and economical operation. On the other hand, from Equation 3, at a given flow rate the duct size increases with decreasing velocity. For multi-story buildings, it is sometimes possible to reduce the height between floors by using very small ducts, thereby effecting, a con querable reduction in building investment cost. Velocities as high as hOOO fpm in main ducts have been used in high-velocity duct systems. Spe cial outlets for such systems have recently been marketed; they incorporate a device for reducing the pressure and attenuating the noise before intro ducing the supply air into the conditioned space. High-velocity duct sys- 748 CHAPTER 32 1956 Guide . terns are becoming increasingly numerous and design experiences reported are the present best guide.16-23 ,' For residences and low pressure commercial systems, the values given in Table 5 may be used. As a general guide, design velocities in main ducts are frequently 1000 fpm in residences and 2000 fpm in commercial build ings. For the branch ducts and branch risers, design velocities are usually about two-thirds and one-half, respectively, of the main duct velocity. DESIGN METHODS In the design of air duct systems, three methods are employed: (1) velocity reduction, (2) equal friction, and (3) the static regain. The three methods and their refinements represent different design levels of accuracy and complexity, and they should be selected, therefore, to suit the applica tion. Simple duct systems may be designed as -quickly and easily as possible, but for large installations the system static-pressure requirement -must be determined as precisely as possible, the most accurate method being recommended. Velocity Reduction Method This method consists of selecting the velocity at the fan discharge and designing for progressively lower velocities in the main at each branch duct. With the selected velocities and known air-flow rates, the various duct diameters are read directly from Figs. 2 or 3, and the equivalent rec tangular sizes are obtained from Table 1. The pressure loss of the run having apparently the highest resistance is determined by adding the straight pipe, elbow, and transition losses; this total value represents the fan static pressure required for-the supply-duct system. The return-air system is sized similarly, starting with the lowest velocities at the return intakes and increasing them progressively in the direction of the fan inlet. Dampers are relied upon for balancing the system. . A refinement is to size the several branch ducts to dissipate the pressure available at the entrance to each. The pressure loss of the duct work be tween the fan inlet and first branch.,take-off is subtracted; from the now known fan static pressure to obtain the available pressure at each junction. By trial, a branch velocity is found that results in the branch pressure loss being equal to, or- somewhat less than, that available. The procedure is repeated for each branch. ., If the fan is specified so that the static pressure available for the duct work is known, the method consists of finding, by-trial, the velocities in the main duct that will require a pressure loss equal to that available. The branch ducts are then sized as previously explained if such a refinement is deemed necessary. - The merits of the velocity reduction method are that (1) duct sizes are determined very easily; and (2) velocities can be limited to those known to be safe from causing noise problems. Its weaknesses are: (1) proper choice of velocities requires experience and judgment; and (2) the designer cannot always determine by inspection which run probably has the highest re sistance. Equal Friction Method The principle of this method is to make the pressure loss per foot of length the same for the entire system. With this method little balancing is required for symmetrical layouts in which all runs have about the same Air Duct Design 749 resistance. For layouts having, both short and long runs, the shortest run will require considerable dampering. . Usual practice is to select the velocity in the main duct near the fan from the standpoint of noise for the particular application. Since the flow rate (cfm) is known, this establishes a value of friction loss per 100 ft of duct in Figs. 2 or 3. This same friction loss value is maintained throughout the design. For example, the flow rate in the main after the first branch take off is reduced by that handled by the branch. Therefore, proceed ver tically downward in Figs. 2 or 3 to the flew flow rate value, and read the velocity and diameter. Note that the velocity is reduced by this procedure; a merit of this method is that it automatically reduces the duct velocities in the direction of flow, thereby insuring that noise will not be a problem. The equivalent rectangular size of any diameter is obtained from Table 1. By continuing the procedure, all sections, including branch ducts, are sized from Figs. 2 and 3 at the same friction loss per foot of actual length. After sizing the system the pressure loss of the run having apparently the highest resistance is calculated, In so doing, the pressure losses of all elbows and transitions are included, and are expressed in terms of equivalent length of straight pipe. . The principal limitation of the equalfriction method is that it does not differentiate between runs having several transitions, elbows, etc., and runs having none. Only the actual length of duct is considered; this and the flow rate fix the duct size. Moreover, when computing the system resistance, care must be exercised that the pressure losses, of transitions, elbows, etc., are included and added to the straight pipe losses. . If the pressure available for the duct work is known, as it is for packaged equipment, this pressure can be divided by the total equivalent length of the run apparently having the highest resistance to obtain a design friction loss value per foot, for use with Fig. 2 or Fig. 3. Hence, for these applica tions, it is not necessary, to select an initial velocity. However, the method then has the weakness that the resistances of fittings must be expressed in terms of equivalent length. Since transitions, elbows, etc., have predom inantly dynamic losses, the equivalent length of a particular fitting varies considerably with its actual size. Note, for example, that the values for elbows in Fig. 4 of Chapter 20 and also that the elbow losses in Fig. 7 of this chapter are given in terms of the number of diameters. Hence, when the available pressure is known, the method requires that the duct size be esti mated in advance. The calculated duct size should therefore be compared with the initial estimate, and if considerably different, a recalculation should be made using the calculated size. Less dampering is required if the method is modified so that only the main duct is sized by the equal friction method. The fan is selected for this total duct resistance and the pressure available at each branch take-off is found in the manner described for the velocity reduction method. The pressure available at each branch is divided by its equivalent length, in hundreds of feet, to obtain a design friction loss value for use with Fig. 2 or Fig. 3 in conjunction with the branch flow rate. The branch ducts are therefore sized as nearly as possible to dissipate all of the available pressure. When using this modified method, care should be exercised that the velocities in short branches do not become excessive from a noise stand point. This is easily guarded against during the design process, because the velocity can be read directly from the friction chart. If it is excessive, move horizontally to the left on the chart and select a diameter which yields a reasonable velocity. The damper for this run will have to dissipate '750 CHAPTER 32 - 1956 Guide OUTLET NO. 2 the excess pressure.. Since duct work attenuates noise to some extent, the damper should be located as close to the main as possible. Sound treat ment for this branch should also be considered. An. alternative solution may. be to revise,the duct layout to increase the resistance of the run, for .example, by relocating the branch take-off so that the total duct length is increased. ' " -. .' Example 6: (Equal Friction Method). A duct layout is shown in Fig: 11. Out lets Nos..1 and 2 deliver 750'cfm each and outlet No. 3 delivers 1000 cfm. Selecting a velocity of 1600 cfm in Section; A; size the duct system and.determine-its static pressure requirement. , Solution: The total cfm to be handled is 2500 cfm. From Fig. 3, with 2500 cfm and 1600'cfm velocity, read a diameter of 17 in: and a friction.loss of 0.2 in. of water per .100 ft. By subtraction, the flow-rate in Section B is 1750 cfm. Along the 0.2 friction line in Fig. 3, all of the ducts can be sized immediately because the flow-rates are known. Results are presented in Table 6. ,. ' 1 : The rectangular equivalents were selected from Table 1 with the objective of having the same duct depth for all three branch runs. - : Theduct run to outlet No. 3 has the highest apparent resistance. It is decided to fabricate, the elbow in Section C with a radius ratio of 1.2; hence, from Fig. 7 with 71IW, = 1.9, L/W = 8. Since W =' 1.25 ft (15 in.), the additional equivalent length due'to the elbow L is 10 ft. The total equivalent length of the run is therefore (20 4- 10 + 15 + 10 + 15) = 70 ft. Therefore, at 0.2 per 100 ft the duct resistance is 0.2 x 70.?* 0.14 in. of water. Adding to this the outlet pressure of 0.12 in., the static pressure requirement of the duct system is 0.26 in. of water. The design is now complete, and dampers will be relied upon for adjusting the outlets to the design flowrates. . : : If refinement is deemed necessary, the modified method can be applied to Sections D_ and E. First, the static pressures available at the junctions with the main of the Section D and E branch ducts are obtained. For Section D it is the system pressure of 0.26 minus the friction pressure loss in Section A. The latter is 0.20 X (20/100) = 0.04; hence, the pressure at the entrance of Section B is 0.22 in. of water. Deduct ing the outlet pressure loss of 0.12, that available for the duct work is 0.10. Assume Section A B G D E Table 6. Tabulation of Results (Example 6) Flow Hate cfm Friction per 100 rr, in. op Water Doer D1AM INCHES Velocity fpm 2500 1750 . 1000 750 750 0.2 0.2 0.2 0.2 0.2 17.0 14.8 12.0 10.7 10.7 1600 1480 1290 1190 1190 Bectanodi-ab DUCT INCHES 20 x 12 . 15 x 12 15 x 8 12 x 8 12 x 8 Air Duct Design 751 the equivalent lengths of the branch take-off and the elbow to be 10 ft each. The total equivalent length of Section D is then (10 + 10 + 10 -1- 5) = 35, and the fric tion loss per 100 ft required to dissipate 0.10 in. of water is 0.10 X (100/35) = 0.29. With this unit friction loss and a flow rate of 750 cfm. Fig. 2 yields a diameter of 10.0 in. and a velocity of 1380 fpm. .. Section E is sized in a similar manner. The pressure available is 0.26 minus the friction loss in Sections A and B; hence, 0.20. With the outlet pressure loss of 0.12. deducted, the available duct-work pressure loss is 0.08 in. Assuming that the branch take-off loss is equivalent to 10 ft of duct, the total equivalent length is 20 ft. Hie required friction loss is 0.08 X (100/20) = 0.40. With this unit friction loss and a flow rate of 750 cfm. Fig. 2 yields a diameter of 9.4 in. and a velocity of 1580 fpm. An equivalent rectangular size is 9 X 8 in. Comparing these results with those in Table 5, it is evident that the modified method has reduced the size of Section D somewhat and that of Section E consider ably. The reduced sizes accomplish more economically what'would otherwise have to be done with dampers. Static Regain Method . Consider a straight run of duct with several branch take-offs attached. The flow rate of air along the run is progressively reduced by the amount diverted into each successive take-ofF. If, for example, the size of the run were the same throughout its length, the velocity would become progres sively less in accordance with Equation 3. When velocities are reduced, a conversion of velocity pressure into static pressure occurs (as well as a loss in total pressure). The principle of the static regain method is to size a duct run so that the increase in static pressure (regain) at each take-off junction just offsets the pressure loss of the succeeding section of the run. The method provides a convenient means of designing a long run of duct having several take-offs so that essentially the same static pressure exists at the entrance to each branch. If, instead of branch ducts, supply outlets are connected directly to the run, then essentially the same static pressure will exist behind each outlet. As a consequence, outlet selection and sys tem balancing is simplified. The method is particularly suited to large installations having several long runs of duct, with each run having many take-offs or supply outlets attached. For this type of application, little or no dampering is ordinarily required to balance the system. The initial velocity in the main duct is selected from noise and pressure loss considerations, and the branch ducts are sized by the modified equal friction method. If the distance between branch take-offs is either very small or very great, it may not be feasible or economically desirable to design for the same static pressure at each junction. In such cases, the method can be used to size the main for either a progressively lower static pressure (net static pressure loss) or a progressively higher pressure (net static pressure gain). If no friction or dynamic losses occurred at the junction, there would be no loss in total pressure, and the change in velocity pressure would be com pletely converted into a regain (rise) in static pressure, which for standard sir would be: where P= \ _ /ZiY ` \4005/ \4005/ Ft = theoretical static pressure regain, inches of water. 11 = velocity in main upstream of branch, feet per minute. Fi = velocity in main downstream of branch, feet per minute. 752 UJU.U) zS sz,-1l CHAPTER 32 ' -3*^ *Wv-i- 1956 Guide -Air Duct Design to _ z ; 753 Design charts based on Equation 13 and rectangular ducts having aspect ratios of 3 to 1 or less are presented in Figs. 12 and 13. The duct length of any section should include the equivalent length o any elbows or transitions within the section. The charts apply to construc tions where regain takes place unaccompanied by radical change in direc tion; namely, to straight-through sections of divided-flow fittings. i \ farwVlr!^ "aOrfTJ"E ttegain Method). A duet layout is shown in Fig. 14. The 0utlets *> 2' 3 and * deliver 1500 cfm each, and outlet 5Inc troXSi ' The P,erating pressure loss at all outlets is 0.12 in. water. Initial sqft and ?S ass-V,n?ed as ls59 fPm; the area of the trunk duct will then be 5.33 able tomainfin *llJ -be f M6 ra` ,?*" turned "that for this example it is desir- Sectiom^B P r> uV' ueth ? al1 <Juet sections Determine the sizes of duct obtained at .-aW iif *, 9 80 * substantially the same static pressure will be at each of the outlets, and find the total pressure loss of the system. Solution: frictionZlo^eoC=in F byA thec,equal friction method so that it has the same rate of and the mif section A. Section A is equivalent to a 29.2 in. round duct (Table 1) rate of . ei1<>SS f5?m.Plg-.3 18 013 in- Per 100 ft- For 2000 cfm flowing at this p esBure loss, the indicated round duct diameter for Section F is approxi- 754 CHAPTER 32 :: 1956 Guide mately 17 in. (Fig. 3). This is equivalent to a 15 x 16 in. duct, which will be used for Section F. The velocity in Section F will be 1200 fpm. 2. Determine the pressure loss in Section F. Actual length of duct is 10 ft; equiv alent length of elbow take-off is assumed as 10 W, or 12.5 ft. Therefore, the total 22 5 equivalent lengthis 22.5 ft. The pressure loss in F = 0.13 in. X = 0.03 in. water. 3. Using Static Regain Chart, Fig. 13, size Section B for a net pressure loss equal to TthheeloospseirnatFio,noisr 0in.0d3iciant.ewd abtyeraarrsofwolhloewadss: on the dotted line on Fig. 13. On Fig. 13, start at the velocity in Section A (1500 fpm) at left margin. Proceed horizontally to 6000 cfm ordinate, and then run parallel to the curved lines to intersect the di agonal Base Line. From this point, rise vertically to the 0.03 net static pressure loss line, and from this intersection proceed horizontally to the Air Velocity Base Line. Proceed parallel to curved lines to intersect ordinate for 25 ft equivalent duct length, and then move horizontally to left margin and read the velocity (1500 fpm). ` Since Section B carries 6000 cfm, the area required will be low = 4 sq. ft, and the4s. izUesionfgdSutcattiwc iRll ebgea3in6 Cx h1a6ritns. (Figs. 12 and 13) determine size of Sections C, D, E and G, but instead of allowing 0.03 in. net loss, which was used for Section B, proceed from the diagonal Base Line vertically to the no gain or loss diagonal. The procedure for Section E is shown by the dotted line and arrows on Fig. 12: starting from 1040 fpm velocity, which is the velocity in Section D. Duct sizes determined by the given procedure are listed in Table 7. Section A B C D E F G Table 7. Tabulation of Results (Example 6) Axa Volume- cfm Equiva lent Length ft Velocity fpm Rectangular Duct ia Diam. in. Fbictxon Pen 100 rt in. Hrf) NnPa' BUSS Poec ,. HiO 8000 6000 4500 3000 1500 2000 1000 40 25 15 26* 15 22.5 15 1500 1500 1300 1040 860 1200 900 48 x 16 36 x 16 31 x 16 26 x 16 16 x 16 15 x 16 10 x 16 29.2 0.13 .05 .03 .0 0 0 17. 0.13 .03 0 ,5.5 F. w "samed' Air Duct Design 755 5. Total pressure loss of the system is the loss in Section A, plus the loss in Section F (or B), plus the loss in the outlet as follows: : ... 4Q ` ` ' Loss in Section A = 0.13. in. X 1--00 = 0.05 . Loss in Section F (or B) = 0.03 , Outlet Loss =0.12....... - Total Pressure Loss = 0.20 in. , DUCT CONSTRUCTION DETAILS Straight sections of round duct are usually formed from sheets, rolled to the proper radius with a longitudinal grooved seam. Each section is swaged 1.5 in. from each end and assembled with the larger end of the adjoining section butting against the swage. The sections are held in .place by rivets, sheet metal screws, or by soldering. Rectangular ducts are generally constructed by breaking the comers and grooving the longitudinal seam, although some fabricators still use the standing seam. Elbows and transformation sections are generally formed with Pittsburgh corner seams because this seam is easier to lock in place than the double seam, but complicated' fittings such as double compounded elbows are usually constructed with double seam corners. The construc tions of these various seams, as well as the types of girth connections, are shown in Fig. 15. The application of the various slips and connec tions is outlined in Table 8. The end slip may be used wherever S slips are recommended. Where drive slips are used, the end slip may be ap plied on the narrow side of the duct, and the drive slips on only the maxi mum side. Designs M to P of Fig. 15 are for flush type seams on ductwork where joints are to be concealed. For smooth appearance the seams may be soldered flush or filled with auto body filler. Screws or rivets used should be of flat-head type. : Ducts 25 to 30 in. in size should' be reinforced .between the joipts, but not necessarily at the joint. Ducts 31. in. and up should be reinforced at the joint and between the joints; if drive slips are used the angles are usually riveted to the duct about 2 in. from the slips. It is good practice to cross-break or kink all flat surfaces to prevent vibratiou or buckling due to the air flow and accompanying variations in internal pressure. The construction of elbows and changes of shape cannot be definitely outlined, because of the varied conditions encountered in the field, but in general, long radius elbows and gradual changes in shape tend to maintain uniform velocities accompanied by decreased turbulence, lower resistance and a minimum of noise. : Heavy canvas connections (asbestos cloth if there is a fire hazard) are recommended on both the inlet and outlet to all fans. Self-vulcanizing udhesive tapes are available for this purpose and for sealing joints in duct Work. The fan discharge connections shown in Fig. 15 are marked good, fair, and poor in the order of the amount of turbulence produced. An 1spection of the heater connections shown in Fig. 15 will readily show that uniform velocity, through the heater cannot be expected in the diagram uoted poor. When obstructions cannot be avoided, the duct area should never be decreased more than 10 percent, and then a streamlined collar ?hould be used. Larger obstructions require an increase in the duct size 10 order to maintain as nearly uniform velocity as possible. Branch take-  75.6 CHAPTER 32 '-1956 Guide A GROOVED SEAM STANDING SEAM S SLIP DRIVE SUP Tp ~T9 _;JL, -JL. J. E END SLIP DOUBLE SEAM PITTSBURGH SEAM BAR.. SLIP REINFORCED BAR SUP POCKET SLIP ANGLE CONNECTION -\ i ^~30' a45- GOOD fA1R , HEATER, FILTER, AND WASHER CONNECTIONS SMALL LARGE EASEMENT AROUND OBSTRUCTIONS DIVERTER TYPE CLINCH COLLAR (PREFERRED) TYPE BRANCH TAKEOFFS Fig. 15. Sheet Metal Duct and Arrangement Details offs should always be arranged to cut or slice into the air stream in order ,to reduce as far as possible the losses in velocity head, ' . . ' Wherever ducts pass through fire walls or connect two fire areas of a building, automatic fire dampers should be provided. For design of such dtunpers and other fire protective details, see Pamphlet No. 90 of the National Board of Fire Underwriters.2* .: The recommended gages for steel (or iron) and aluminum sheet metaj rectangular ducts are given in Table 8. Steel or iron sheets are specified Air Duct Design 757 according to th? manufacturers or U. S. Standard Gage System. Alu minum sheets are specified according to the American or Brown & Sharpe Gage System. Weights of black and galvanized steel and iron sheets per square foot of surface for various gages are given in Table 9. Similar data for 2S aluminum sheets will be found in Table 10. Weights of standard copper sheets are given in Table 11. In calculating the total weight of a given length of duct work from these tables, it is customary to add 20 percent for the weight of joints and bracings. - Aluminum sheets of the 2S and 3S type alloy and % hard temper, are Table 8. Recommended Sheet Metal Gages for Rectangular Duct Construction* Alu` MINUM B.&S. Gage Steel U. 8. Std. Gage Maximum Side, orType Transverse Joint Connections1* Inches Bracing 24 26 Up to S. Drive, Pocket or Bar Slips, on None 12 7 ft 10 in. centers 13 to 24 S, Drive, Pocket or Bar Slips, on None 7 ft 10 in. centers 22 24 25 to 30 S, Drive, 1 in. Pocket or 1 in. Bar 1 x 1 x f in, angles Slips, on 7 ft 10 in. centers 4 ft from joint 31 to 40 Drive, 1 in. Pocket or 1 in. Bar l x 1 x | in. angles 20 22 Slips, on 7 ft 10 in. centers 4 ft from joint 41 to 60 1 in. Angle Connections, or 1$ in! 1$ x 1$ x in. angles . Pocket or in. Bar Slips with. 4 ft from joint If in. x l in. bar reinforcing on ' 7 ft 10 in. centers 18 20 61 to 90 11 in. Angie Connections, or 1$ If x If x J in. diagonal in. Pocket or If in. Bar Slips angles, or If x If x f 3 ft 9 in. maximum centers with in. angles If x f in. bar reinforcing 2 ft from joint 16 18 91 and 2 in. Angle Connections or If in. If x If x f in. diagonal up Pocket or If in. Bar Slips 3 ft angles, or If x If x f 9 in. maximum centers with in. angles If x f in. bar reinforcing1* . 2 ft from joint' For normal pressures and velocities (see Table 5) utilised in typical ventilating and air conditioning sys- tf-rns. _ Where special rigidity or stiffness is required, ducts should be constructed or metal two gages heavier. All uninsulated ducts 18 in. and larger should be cross-broken. Cross-breaking may be omitted on uninsu lated ducts if two gages of heavier metal are used. . Other joint connections of equivalent mechanical strength and air tightness may be used. . . . e Duct sections of 3 ft 9 in. may be used with bracing angles omitted, instead of 7 ft 10 in. lengths with Joints indicated. Ducts 91 in. and larger require special field study for hanging and supporting methods. ' - readily workable, and can be used.for practically all duct work. The 2S type (commercially pure aluminum) is suitable for all, except very large ducts. For large ducts, where more strength is desired, the 3S alloy with % or hard temper is frequently used. The higher tempers, particularly full hard, do hot have the formability of the lower tempers. For very furge ducts, where considerable strength is required, aluminum sheets should be 2 gages heavier than indicated in Table 8, and should be amply stiffened. Joints can be of any of the standard designs, and can be fabri cated in the same manner as iron. Repeated sharp bending and rebending should be avoided, as aluminum has a tendency to crack under such treat- 758 CHAPTER 32 1056 Guide Table 9. Weights op Black and Galvanized Sheets . Black Sheets Galvanized Sheets* U. 8. . .Sn>., ' Gage . Approximate .. , . Weight Per .. Thickness, In. Square Foot Steel ,;. Iron - ' Ounces. Pounds Approximate -. . .Weight Per Thickness, In. ` Square Foot Steel . - . Iron : Ounces.: Pounds 30 28. 26 ' 24 22 20 78 16 14 12 11 10 0.0123 <*.0153 0.0184 5-0245 00306 (T.0368 0.0490 00613 010766 0.1072 0.1225 0.1379 0.0125 0.0156, 0.0188 0.0250 0.0313 0.0375 0.0500 0.0625 0.0781 0-1094 0.1250 0.1406 8 10 12 16 20 24 32 40 50 70 80 * 90 0.500' 0.625 0.750 1.000 1.250 1.500 ' 2.000 2.500 3.125 4.375 -6.000 5.625 0.0163 0.0193 0.0224 0.0285 0.0346 0.0408. 0.0530 0.0653 0.0806 0.1112 0.1265 0.1419 0.0165 0.0196 0.0228 0.0290 0.0353 0.0415 0.0540 0.0665 0.0821 0.1134 d.1290 0.1446 . i0.5 12.5 14.5 18.5 22.5 , 26.6 34.5 42.5 52.5 72.5 82.5 92.5 0.656 0.781 0.906 1.156 1.406 1.656 2.156 2.656 3.281 4.531 5.156 5.781 Thanked ,,heet are gaged beta* gaWanUiaTTmi ^ therefore 0.004 in. thidcex. Table 10. Weights and Thicknesses op 2S Alpminpm- (DensityQ.098 lb/cp inJ B. A S. Gage ' ' 28 26 24' 22 20 ...........18 ` 16 14 - Thickness, Inches Oedmal ' 0.012 0.016 0.020 0.025 0.032 0.040 0.051 0.064 _ Nearest Fraction 1/64 1/64 1/64 1/32 1/32 3/64 3/64 1/16 Weight peb Sqtjabb Foot Ounces ' Pounds 2.7 3.6 4.5 5.4 7.2 9.0 11.5 14.4 0.169 0.226 0.282 0.353 0.452 0.563 0.720 0.903 Table 11. Weights and Thicknesses of Standard Coppeb Sheets* Rolled to Weight "________________ Weisht tea Souabe Foot ---------------------. Ounoes Pounds Thickness, Inches Equivalent Nearest Fraction Neabebt Gage No. B. AS. Stubs U. S. Std. 10 12 14 16 18 ` 20 24 ; 28 . . ... - 38 ... 32 r .40 f 44 . :** 48 56 ` ' 64 . 0.625 0.750 0.875 1.000 1.125 1.250 1.600 1.750 2.000 2.250 2.500 2.750 3.000 . 3.500 4.000 0.0135 0.0162 0.0189 0.0216 0.0243 0.0270 0.0324 0;0378 0.0432 0.0486 0.0540 0.0594 0.0648 0.0756 0.0864. it. Mi Mi Mi. Mi Mi Mi Mi Mi . Mi - H* M He n Variations from these weights must be expected in practice. 2276 25 23 23 2210 . J9. 17 16 15. 15 14 1131 I 2297 26 24 23 222210 19 18 17 17 16 15 . 14 28 26 25 24 17 17 : 16 . . 14. 13 . Air Duct Design 759 ment. Aluminum of 16 B. & S. gage or heavier can readily be welded by the metallic arc or acetylene process. Soldering is difficult and is not gen erally recommended. Riveting is done in the same manner as in iron or steel sheet. Self-tapping screws tend to loosen because of the softness of aluminum. 1 HEAT LOSSES FROM DUCTS In designing duct systems, the heat gains or losses of the ducts can be quite considerable, not only if the duct passes through unconditioned space, but also on long duct runs within conditioned space. Proper insulation will remedy this situation considerably, but sometimes a redistribution of the supply air is necessary in order to compensate for the heat exchanges that occur. The heat loss from a given length of duct can be expressed by: Q,= UPl [(^Hp) ~ <>] 04) where <?. = heat loss through duct walls, Btu per hour. P ~ perimeter of duet, feet. ' i length of duct, feet. <i = temperature of air entering duct, Fahrenheit. It = temperature of air leaving duct, Fahrenheit. <a = temperature of air surrounding duct, Fahrenheit. To obtain the temperature drop in warm air for a given distance of trans mission, or the temperature rise if the duct carries air cooler than the room through which it passes, the following formulas can be used: tt(y + 1) -- 21, U (y - i)" (15) a --' t(y -- 1) -1-2tt (v + i) (16) where _ for rectangular ducts or, v VPl ....................... = 7--.-2-D---V--p- fo, r round, d,ucts. , y Ul A = cross-sectional area of duct, square feet. p = density of air, pounds per cubic foot. V = mean velocity of fluid, feet per minute. > ~ diameter of round duct, feet. . In using Equations 15 and 16, one of the duct air temperatures will be unknown and will be obtained by substitution of the other known or as sumed values. Heat loss coefficients for insulated duets with various conductivities are given in Fig. 16. The conductivities of various materials, which are based on mean temperatures, about 70 F, will ba found in Table 2 of Chapter 9. For cases where the mean temperature is other than that at which the test' was conducted, a correction should be made. However, in most cases the effect of this factor will be small and may be neglected. " Example 7: Determine the entering air temperature and heat loss for a duct 24 X 760 CHAPTER 32 1956 Guide : below. Thickness of Insulation (Inches) t 1 11 2 5% . 2% 7% 3% 4% 36 in. cross section and 70 ft in length, insulated with J in. of a material having a conductivity of 0.35 Btu at 86 F mean temperature, carrying air at a velocity of 1200 fpm, measured at 70 F, to deliver air at 120 F with air surrounding the duct at 40 F. Solution: Referring to Fig. 16, the overall heat transmission coefficient is found to be0.49 Btu. From Table 1, Chapter 3 the density of air at 70 F and 29.921 in Hg- is found to be 1/13.348 = 0.0749 lb per cu ft. Substituting these and the other given values in Equation 16, y and ti will be as follows: ' V = 28.8 X 6 X 1200 X 0.074-9 0.49 X 10 X 70 = 45.3 Air Duct Design 120(45.3 + 1) - 80 t, = 123.7 F 45.3 - 1 Substituting in Equation 14: Q. - 0.49 X 10 X 70 ^(--2+ 120^ - 40J = 28,100 Btu per hr. 761 For special considerations which apply to insulation of ducts in' marine installations see Chapter 48. REFERENCES 1 A.S.H.VJE. Research Paper No. 1280--A New Friction Chart for Round Ducts, by D. K. Wright, Jr. (A.S.H.V.E. Transactions, Vol. 51,1945, p. 303). * Friction Factors for Pipe Flow, by L. F. Moody (A.S.M.E. Transactions, Vol. 66> 1944, p. 671). * Friction Charts for Gases Including Correction for Temperature, Viscosity and Pipe Roughness, by R. D. Madison and W. R. Elliot (A.S.H.VJE. Journal Section, Beating, Piping and Air Conditioning, October, 1946). 4 A.S.H.V.E. Research Report No. 1469--Friction Losses in Round Aluminum Ducts, by F. W. Hutchinson (A.S.H.VJE. Transactions, Vol. 59, 1953, p. 127). 5 Friction Equivalents for Round, Square and Rectangular Ducts, by R. G. Hueb- scher (A.S.H.V.ErTnANSACTioNS, Vol. 54, 1948, p. 101). . * A.S.H.V.E. Research Report No. 1405--Energy Losses in 90-Degree Duct Elbows: A Survey and Analysis of Available Information, by D. W. Locklin (A.S.H.V.E. Transactions, Vol. 56,1950, p. 479). 7 Pressure Loss in Ducts with Compound Elbows, by J. R. Weske (National Ad visory Committee for Aeronautics, Advance Restricted Report W-39, February 1943). * Pressure Losses in Rectangular Elbows, by R. D. Madison and J. R. Parker (Heating, Piping and Air Conditioning, July, p. 365, August, p. 427, September, p. 483, 1936). 7 Modern Air Conditioning, Heating and Ventilating, by W. H. Carrier, R. ECherne and W. A. Grant, 2nd edition, 1950, p. 248 (Pitman Publishing Corp.). 10 A.S.H.V.E. Research Report No. 1216--Effect of Vanes in Reducing Lobs in Elbows in Seven-Inch Square Ventilating Duct, by M. C. Stuart, C. F. Warner, and W. C. Roberts (A.S.H.VJE. Transactions, Vol. 48, 1942, pp. 409-424). 11 Pressure Losses of Divided-Flow Fittings, by S. F. Gilman (A.S.H.A.E. Trans actions, Vol. 61, 1955, p. 281). 17 Pressure Losses Due to Bends and Area Changes in Mine Airways, by G. E. McElroy (I/. S. Bureau of Mines, Information Circular I.C. 6663, p. 4). u Pressure Losses Resulting from Changes in Cross-Sectional Area in Air Ducts, by A. P. Kratz and J. R. Fellows (University of Illinois Engineering Experiment Station, Bulletin No. 300). 14 Fan Engineering, (R. D. Madison, Editor) 5th ed., 1948, p. 124 (Buffalo Forge Company). "Design of Power Plant Installations: Pressure-Loss Characteristics of Duct Components, by J. R. Henry (National Advisory Committee for Aeronautics, Advance Restricted Report L4F26, June 1944, L-208). 14 Installing Ducts for Higher Pressures and Why Higher Duct Velocities?, by P 109)*^ ^eating, Piping and Air Conditioning, April 1953, p. 98 and Feb. 1954, 17 Modern Trends in Air Distribution, by R. D. Tutt (Refrigerating Engineering, May 1953, p. 509). 17 Design Factors in High Velocity Air Distribution, by W. W. Kennedy (Healing <tnd Ventilating, January 1954, p. 83. 47 Can Air Conditioning be Simplified in Large Buildings?, by J. W. Kreuttner (Beating, Piping and Air Conditioning, August 1954, p. 94). . 70 Air Conditioning an Operating Hotel, by Gardner Savage (Healing & Ventilattng, September 1954, p. 100). 71 Handbook on High Velocity Air Distribution, by C. M. Wilson (Heating, Piping vnd Air Conditioning, November 1954, p. 94 and discussions Dec. 1954, p. 73. Feb. 195S, p. 69, March 1955, p. 99, June 1955, p. 82). CHAPTER 32 1956 Guide 762 ** Air Conditioning of Multi-Room Buildings, by R. W. Waterfill (A.S.H.A.E. Transactions, Vol. 61, 1955, p. 233):. / u Air Conditioning Multi-Story Buildings, by P. B. Gordon (Heating Piping and Air Conditioning, April 1955, p. 112. Discussed loc. cit. May 1955, p. 103). S1 Standards of the National Board of Fire Underwriters (N B.F.U. Pamphlet No. 90, p. 21). FLUID FLOW [SaUhapOri) BIBLIOGRAPHY . ' ' Elementary Mechanic# of Fluids, by Hunter Rouse, 1946. (John Wiley & Sons, Inc.). . Engineering Applications of Fluid Mechanics, by J. C. Hunsaker and B.G. Rightmire, 1947 (McGr&w- Hi))FBluoidokFCloowmipnaPniyp,eIsn,cb.)y. Clifford McClain, 1952. (The Industrial Press, New York). Flow and .Fan-?Principles of Moving Air Through Ducts, by Harold C. Berry, 1954. (The Industrial Press, New York). .: ' - . ' ' ; ' The Flow of Fluids in Closed Conduits, by R. J. S. Hfcott (Meckonicol Engineering, Vol. 55, 1933, p.4?7). . - . - .. : . .' v A Study of the Data on the Flow of Fluids in Pipes, by E. Kemler (ASMS Transactions. Vol. 55, 1933, Hydraulics, p. 7). . <PLOAW.S.OHF.VA.EIR. RIeNseaDrUcCh TRSeport No. 1105--Fri'ctional Resistance, to the F.low of Air in Stra. ight Ducts, by F. C- Houghten, J. B. Schmieler, J. A. Zalorcik, aod N. Ivanpvio (A.8.H.VJ3. Transactions, Vol. 45, 1939, P.,3A5-)S.,.H..V-E. R.es. earch Repost No. 1154--Analysis of Fac.toreAf.fectingD' uctFriction, by J.B.: Schmieler F. C. Houghten, and B. T. 0l3oa (A.S.H.V-E. Transactions, Vol. 46,1940, p. 193). - : Pressure Loss Characteristics of Small Diameter Round Duct Systems, by G. R. Wlutnah and 3. V. Borry. (A.S.H.VJ2. Journal Section, Beating, Piping & Air Conditioning, November 1952, p. 111). . - . A.S.H.V.E. Research Report No. 1470--'Pressure Losses in 4-Inch Diameter Galvanized Metal Duct and Fittings/ by H. G. Conn, W. G: CoJborae, and W. G. Brown. (A.S.H.VJ5. Transactions, Vol. 59, 1953, p. 139). . - .; . 1 ` .PRLEoSssSUofRPEreLssOuSreSDIuNe tEoLEBlOboWwSs in the Transmission of ;Air Th.rough. Pipes or Ducts, by Frank L. Busey '('A.SN.eHw.VD.Ea.tTa rfoarntshaectDioensisg,nVoofl.E1lb9o,Jw9s1i3n,pDp.u3c6t6S-3y7s6te).ms, by Loriag. W. ir.t {General Electric. Revieto, Vol. 30. vJiunAen19In27v,epspti.g2a8ti6o-n29o6f).Pressure Los. se.s in A.ir D.. uct- E.lbowsi-, by Oliver E. - P- arker (Northeastern Univer sit- yInthveessisti,gMataioyn28o,f 1A9i3r4F).low in Right Angle Elbows in a Rectangular.Duct, by Charles H. . McDe. Uan and Walter A. Bartlett, Jr.. {National Advisor? Committee for Aeronautics, Advanced Restricted Report L-328, Oc t.-oi ibAerJ,31.H94.V1)J. 2. Rese'ar' ch Rep! ort No. 1211--pressure Loss.Caused by Elbows in Eight-Inc.h Round Venti lating Duct, by M. C.. Stuart, C. F. Warner and W. C. Roberts (A.S.H.V~E. Transactions, Vol. 48, 1942, pp. 335-350).' \ . ' . * ; ' .. / .' ErperimentaMhvestigation of Velocity Distributions Downstream of Single Duct Bends, by John R. W'eske {National 'Advisory Committee for Aeronautic*,Technical Note 1471, January, 1948)'. . Investigations of the Flow in Curved Ducts at Large Reynolds Numbers, by John R. Weske {Journal of.Applied Mechanics, December, 1943, pp. 344-348).. . ' : How Much Pressure Loss in Round Elbows?, by. R; K. Guthrie {Heating, Piping <fc Air Conditioning, March 1955, p. 130and discussions'by R. D. Madison and R. M. Conner, April 1955, p. 89, and by the author, June 1955, -p. 8J>. . 'PRAE.SSS.HU;RVE.EL. ORSeSseIaNrcDh IRVeIDtoErDt-NFoL.O1W392--FIFTiTttIinNgGLSosses for Extended-Plenum Forced Air Sy, stem, s-, b.y H. H. Korst, H. A. Buckley, S. Konso, and R. W. Rouse. (A.S.H.VJ3, Transactions, Vol. 56, 1950, p. 259)* A-S-H-V-EL Research Report No. 1430--Pressure Losses of Take-Offs for Extended-Plenum Duct Sys tems, by J. W. Holl, S. F. Gilman, R. J. Martin, and S. Konio. (AB.H.V.E. Transactions, Vol. 57,1951. P- 419).. . D UAC.ST.HD.EVSrEIG. RNesear-ch R- e.tort No. 1050--A.Ratio.nal Me.thod of Lhict Design, by L. G. Miller. (A.S. H.VM.Eod. eTrrnaTnhsaincktiinognsA, pVpolile. 4d3t,o19D37u, cpt. D71e)s. ign, by K' irby Wa.lker, (He.atin,g, Piping- <fc' At.r Conditioning, March 1949, p/S5; April 1949, p. 104; May 1949; p. 91; July 1949, p. 95; September 1949, p. 96; November 1949, p. 9P7o; iMntaerrcsho1n9A50i,rpC:o9n7daitniodnMinagyD1u95c0t,Dpe. s9ig4)n. and In- stallation (Beating ondVe-nlilating's Reference. Section. .H' eaErcinognaonmdicVael DntuilacttiLnagy,oOucttso,bbeyr,P-1e9t5e1r)F. ranck.(Beati.ng, Piping <fc`A ir Conditioning, Dec'embe;r 1952, p. lW). . .The Design of Aluminum Duct Systems, by F. W. Hutchinson, 1954 (KaiserAluminum A Chemical Sales, Inc., Oakland, Cal:)'. ...................*' ' . - MISPCerEfoLrLmAaNncEeOTUesSts of Aab,estoe.InsulatingAir Ducts, by R. . H' ; He1ilman an. d R. A. M' cA. rth. ur (A.S. .H.VJS- Transactions, Vd.44, 1938, j>. 197),,- / , : . . . CHAPTER 33 FANS Types, Fan Performance, Fan Laws, Fan Performance Curves, System' Characteristics, Fan Arrangements, Fan Control, Motive Power, Fan Selection, Fan Installation, Fan Applications IN HEATING, ventilating and air conditioning practice, the devices used to produce air flow are variously known as fans, blowers, exhausters or propellers. The A .S.M.E. Test Code1 limits fans to those in which the fluid density change does not exceed 7 percent (one psi at atmospheric pressure) and labels as compressors those devices operating beyond that pressure range. Since air conditioning rarely requires pressures of over J psi, all such devices will be known as fans and the air will be considered non-compressible, Types Fans are divided into two general classifications: (1) centrifugal or radial flow in which the air flows radially through the impeller within a scroll type housing, and (2) axial flow in which the air flows axially through the impeller within a cylinder or ring. Centrifugal fans are further subdivided into types denoted by the curva ture or slope of the impeller blades, the angle of which largely determines the operating characteristics. For a given output, a forward inclination of blade indicates a relatively low speed of operation, and a backward in clination, a relatively high speed of operation. Many intermediate forms are also found. Axial flow fans are subdivided into types differentiated mainly by their enclosures and refinements of impellers and appurtenances. All types vary in shape, number and angles of blades; ratios of hub diameter to im peller diameter; materials and methods of fabrication, depending upon de sign and preference of manufacturer. Tubeaxial and vaneaxial fans, usu ally vised against appreciable resistance, commonly have relatively large hubs and helical blades (the angle varies radially along the blade). The blades may be of uniform thickness, either flat or cambered, and either cast or made of plates; or they may be of air foil sections, either cast or of double thickness sheet. Streamlining of both impeller and enclosure is common practice. Vaneaxial fans incorporate guide vanes to modify per formance and increase efficiency. Propeller fans customarily used for free delivery, or against low resistance, also are found with a variety of blade conformations, but are simple in construction. They are merely mounted within a plate or ring. The fan nomenclature in Fig. 1 has been standardized by the National Association of Fan Manufacturers.* . FAN PERFORMANCE Fan performance is a statement of volume, total pressures, static pres ses, speed, power input, mechanical and static efficiency, at a' stated density. These terms are defined by the National Association of Fan Manufacturers* as follows: 1. Volume handled by a fan is the number of cubic feet of air per minute expressed lan outlet conditions. 763 764 CHAPTER 33 1956 Guide 2. Total pressure of a fan is the rise of pressure from fan inlet to fan outlet. 3. Velocity pressure of a fan is the pressure corresponding to the average velocity determination from the volume of air flow at the fan outlet area. ' 4. Static pressure of a fan is the total pressure diminished by the fan velocity pre5s.suProew. er output. of a fan is expressed in horsepower and is based on fan volume and the6.faPnowtoetrailnppreuststuorea. fan is expressed in horsepower and is measured horsepower del7iv.eMreedchtoantihcael feafnficsiehnacfyt.of a fan is the ratio of power output to power input. 8. Static efficiency of a fan is the mechanical efficiency multiplied by the ratio of static pressure to the total pressure. ' 9. Fan outlet area is the inside area of the fan outlet. 10. Fan inlet area is the inside area of the inlet collar. . While the total pressure truly represents the actual pressure developed by the fan, the static pressure may best represent the useful pressure for overcoming resistance.. In many installations, since the outlet velocity of the fan is greater than the duct velocity, some of the velocity pressure may be utilized by conversion to static pressure within the system. How ever, due to the uncertainty of the flow at the points of velocity change, the amount of conversion is seldom known and therefore, most fan tables list only the static pressure' as available to overcome the system resistance. Fig. 1. Names and Definitions op Types of Fans . Propeller Fan . A propeller fan consists of a propeller or disc wheel within a mounting ring or plate- Tubeaxlal Fan A tubeaxial fan consists of an axial flow wheel within a cylinder. Vaneaxial Fan A vaneaxial fan consists of an axial flow wheel within a cyl inder, combined with a set of air guide vanes located either before or after the wheel. Centrifugal Fan A centrifugal fan consists of a fan rotor or wheel within a scroll type of housing. Fans 765 -According to the Standard Test Code3 the efficiencies may be determined by the formulas: : Mechanical (total) Efficiency = 0.0001573 X (efm) X total pressure (inches, water) horsepower input 0.0001573 X (cfm) X static pressure (inches water) Static Efficiency = horsepower input As the static pressure is often more useful than total pressure, static efficiency is likewise many times more useful than mechanical efficiency. However, where a high outlet velocity can be effectively utilized, the static efficiency fails to be a satisfactory measurement of performance; also when a fan operates against no resistance, the static efficiency becomes zero and is meaningless. Under such circumstances, many engineers prefer to use mechanical efficiency. Sound developed by a fan is a characteristic which is becoming increas ingly important.^ Unfortunately, no method has yet been devised for accurately measuring the sound actually discharged into a duct system. The A.S.H.A.E. Research Laboratory, in cooperation with the U. S: Navy, has a program underway seeking to find a method. Many manufacturers list the average sound (for various fan operating conditions) measured at seven stations near the fan. These stations, as specified in the N.A.F.M. Test Code,4 are located in a horizontal plane passing through the fan shaft, and are at a distance of one wheel diameter (but not less than 5 ft) from the fan. Such values are useful in comparing the relative sound generated by various types and sizes of fans under comparable operating conditions. ' FAN LAWS6 The performances of fans of all types follow certain laws which are useful in predicting the effect upon performance of changes in the conditions of operation, the duty required of the installation, or the size of the equipment due to the space, power, or speed limitations. In the following laws, groups 1 to 6, Q -- air volume and P = static, velocity or total pressure. The laws pertaining to fan size apply only to fans geometrically similar, i.e., those in which all dimensions are proportional to some linear dimension denoted as size. If the size number is also linearly proportional, it may be used; otherwise, wheel diameter is commonly used as a size criterion. 1. Variation in Fan Speed: Constant Air Density--Constant System () Q; () P: . (c) Power: Varies as fan speed. Varies as square of fan speed. Varies as cube of fan speed. Variation in Fan Size* Constant Tip Speed--Constant Air Density Constant Fan Proportions--Fixed Point of Rating (fl) Q: Varies as square of wheel diameter. (&) P` Remains constant. (c) RPM: Varies inversely as wheel diameter. (d) Power: Varies as square of wheel diameter. 766 CHAPTER 33 3. Variation in Fan Size: . At Constant RPM--Constant Air Density Constant Fan Proportions--Fixed Point of Rating (a) Q: (f>) P: Varies as cube of wheel diameter. Varies as square of wheel diameter. (c) Tip Speed: Varies as wheel diameter. (d) Power: Varies as fifth power of diameter. 1956 Guide 4. Variation in Air Density: Constant Volume--Constant System Fixed Fan Size--Constant Fan Speed fa) Q: Constant. (6) P: Varies as density. (c) Power: Varies as density. 5. Variation in Air Density: .' Constant Pressure--Constant System . Fixed Fan Size--Variable Fan Speed (a) Q: Varies inversely as square root of density. (b) P: . Constant. ,. (e) RPM: Varies inversely as square root of density: (d) Power: Varies inversely as square root of density. ' ........ 6. Variation in Air Density: Constant Weight of Air--Constant System ' Fixed Fan Size--Variable Fan Speed () Q: Varies inversely as density. () P: Varies inversely as density. (c) RPM: Varies inversely as density. (d) Power: Varies inversely as square of density. . . : 1 Examples 1 to 4 illustrate the application of the preceding fan laws. Example I: A certain fan delivers 12,000 efm at a static pressure of 1 in. of water when operating at a speed of 400 rpm and requires an input of 4 hp. If in the same installation 15,000 cfm are desired, what will be the speed, static pressure, and power? 15,000 Speed = 400 X = 500 rpm Static pressure = 1 X 5--00VI = ,1.,,56 .in. 400/ Power = 4 X = ?.81 hp Example B: A certain fan delivers 12,000 cfm at 70 F and norma) barometric pres sure (density 0.075 lb per cubic foot) at a static pressure of 1 in. of water when operat ing at 400 rpm, and requires 4 hp. If the air temperature is increased to 200 F (den sity 0.0602 lb) and the speed of the fan remains the same, what will be the static pressure and power? . u.uou- . Static pressure = 1 X --rrr = 0.80 in. 0.0602 Power = 4 X ---- = 3.20hp 0.075 Example S: If the speed of the fan of Example is increased so as to produce a static pressure of 1 in. of water at the 200 F temperature, what will be the speea. capacity, and power? Fans Speed = 400 X A /-5^5^ = 446 rpm V 0.0602 767 Capacity = 12,000 X i /?~-- = 13.392 cfm (measured at 200 F) y 0.0602 Power = 4 X a/^1 = 4.46 hp y 0.0802 Example 4; If the speed of the fan of the previous examples is increased so as to deliver the same weight of air at 200 F as at 70 F, what will be the speed, capacity,, static pressure, and power? . Speed 400 X 0.075 0.0602 ' 498 rpm Capacity = 12,000 X 0.075 0.0602 = 14,945 cfm (measured at 200 F) 0.075 Static pressure = 1 X = 1-25 in. " ;. / oT()75 V Power = 4x[~j =6.20 hp . , The fan laws stated may be combined to give other overall values. One useful combination is the product of laws 1 and 3 which gives the following relations: . Capacity varies as the ratio of size cubed, times the ratio of the rpm. Pressure varies as the ratio of size squared, times the ratio of the rpm squared. Horsepower varies as the ratio of the size to fifth power, times the ratio of the rpm cuhed. ' . Example 5: Assuming that a fan with a 36 in. diameter blast wheel will deliver 12,000 cfm at 70 F at 1 in. static pressure, requiring 4.0 brake hp when operating at 400 rpm, what is the capacity, pressure and horsepower of a homologous fan having a 45 m. wheel at the same speed? /45V /400\ Capacity = l-j X f -- I X 12,000 = 23,400 cfm Static pressure = 1/4--5VJ X /(4--00\J* XI* 1.56 in. ,,Horsepower =/4( 5--VI X/I400V1X4 = 12.2 hp . \36/ \400/ FAN PERFORMANCE CURVES Fan performance curves are the graphical presentation (for constant speed and air density) of the relation of total pressure, static pressure, power teput, and mechanical and static efficiency, to actual volume, for the de- s[red range of volumes. Figs. 2, 3 and 4 illustrate performance (some times called characteristic) curves of various types of fans. ' - Centrifugal fans* may be roughly divided into three classes: (1) those Jiuth the tip of the blades curved forward in the direction of rotation; (2) those with straight radial blades; and (3) those with the tip of the blades in- fiiir 768 CHAPTER 33 1956 Guide* clined backward away from direction of rotation. They are also character ized as slow speed, moderate speed and high speed types,, respectively, al though the actual speed range of each may be wide and overlapping. The highest speed type may operate as high as 200 percent of the speed of the lowestspeed type, to deliver the same volume of air and the same pressure. The differentiating curvature is always the tip of the blade, since the inlet edge, if inclined, is always curved forward to minimize the shock loss at en trance. Straight radial blades are most frequently found in pressure fans and material handling fans. Centrifugal fans produce pressure from two independent sources: (1) from the centrifugal force created by rotating the enclosed air column, and (2) from the kinetic energy imparted to the air by virtue of its velocity Fans ' 769 having straight blades it is roughly constant. Thus the shape of the horsepower curve definitely identifies the blade angle. Performance curves of a typical forward-curved blade centrifugal fan are shown in Fig. 2. The pressure rises from free delivery toward no delivery, with a characteristic drop at low capacities, because a large share of the pressure is being generated by conversion of velocity, which is small at low capacity. The maximum efficiency occurs at approximately maximum pressure. The horsepower curve reflects the increase in energy by rising rapidly from no delivery to free delivery. The sound is a minimum at maximum efficiency, and rises toward free delivery as the velocities in crease. Performance curves of a typical backward-curved blade centrifugal fan are 3hown in Fig. 3. The pressure is constantly rising from free delivery ' |: '! H;jii \ ;.E . ji ;jj; 'I :! * i ?! jji i ?l |; I if! ;j I j[: ! f| '! |; S! Fig 2 Percentage Performance Corves of a Forward-Curved Blade '' Centrifugal Fan _ leaving the impeller. This velocity in turn is a combination of rotative velocity of the impeller and air speed relative to the impeller. When the blades tip forward, these two velocities are cumulative, and when back ward, oppositional. Thus a fan with forward-curved blades depends less on centrifugal force for its pressure, and more on velocity pressure eonversion in the scroll, with the result that it may run at relatively low speed. Conversely, a fan having backward-curved blades builds up more of its pressure by centrifugal force (a more efficient form of energy transfer) and less by velocity conversion and, therefore, must run at a higher speed. Likewise, a fan having forward-curved blades will produce the greatest caparity of any type of the same size when operating against no resistance. Since the energy imparted to the air depends on the velocities,1 and since the velocities are cumulative with a fan having forward-curved blades, the theoretical energy per pound of air rises rapidly with an increase of ajf delivery. With the velocities oppositional in the fan having backward curved blades, the energy per pound of air may decrease, and in a fan PER CENT OF WIDE OPEN VOLUME Fig. 3. Percentage Performance Curves of a Backward-Curved Blade Centrifugal Fan nearly to point of no delivery. The horsepower reflects the energy-velocity relationship by rising to a maximum value as the capacity increases, and then decreasing with further increase in capacity to give a self-limiting horsepower characteristic. The maximum horsepower coincides approxi mately with the maximum efficiency. The sound is again a minimum near maximum efficiency, but is little or no higher at free delivery than at low capacities.- ,. Between the extremes of forward and full-backward-curved blades, there exists a number of intermediate designs which show varying degrees of similarity to the curves in Figs. 2 and 3. A common variation is a fan having modified backward, single or double-curved blades and equipped with fixed inlet vanes. Such vanes applied to a partially backward-curved nnpeller give the steep, constantly rising pressure characteristic, and the self-limiting horsepower feature of the full-backward-curve. They also 770 CHAPTER 33 1956 Guide stabilize, the flow entering the impeller when adverse flow conditions exist in the approach to the inlet. ;; < Axial flowTans develop none of their static pressure by centrifugal force, but all from the change in velocity in passing through the impeller, and its .conversion into static pressure: They are thus inherently high velocity fans, and are very dependent on blade conformation for good characteristics. For that reason, an air foil section, such as developed in wind tunnels for aircraft, work8 is frequently used. Since any shape of blade can only be correct for a narrow range of capacity at constant speed, the performance curves for any blade show definite characteristics. To absorb energy, the air must be given a tangential motion in passing the impeller,7 and when operating against higher pressures, must have guide vanes (see vaneaxial fans) to obtain best efficiencies. Fans 771 downward trend from no delivery to free delivery with the maximum at no delivery, contraiy to that of a centrifugal fan. The type of guide vanes in a vaneaxial fan has a distinct bearing on the shape of the horsepower curve. The maximum efficiency tends to occur at a percentage of free delivery capacity higher than for a centrifugal fan. . The sound curve, which may have a minimum value comparable to centrifugal fans, is again lowest near maximum efficiency, but has a charac teristic rise when the fan is operating at low capacities and the staU point of the blade section is reached. Since propeller fans are designed for operation near free delivery, less attention is given the regaining of velocity to static pressure, and the pressure curve rises constantly from free delivery to no delivery. The Fiq. 4. Percentage Performance Curves of an Axial Flow Fan While axial flow fans are inherently a higher capacity type than centrif ugal fans, they, too, may be designed with widely varying characteristics. As with a centrifugal fan, the pressure rises generally from free delivery to no delivery, but tubeaxial and vaneaxial fans may have a drop in pressure when the capacity decreases below a certain volume, a condition also found in the case of the centrifugal fan having forward-curved blades. The pressure drop is caused by the same condition for both fans, t.e., the static pressure is largely dependent on conversion of velocity pressure, and velocity pressure is small at low capacity. Tubeaxial and vaneaxial fans may also have performance curves resembling somewhat those of a centrif ugal fan with backward-curved blades. Fig. 4 shows the performance curves for a typical design. The horsepower curve may be flat with a self-limiting characteristic as in a'backward-curved blade centrifugal fan, or it may have a generally Fig. 5. Parabolic Stbtem Characteristic Curves horsepower is highest at no delivery, and decreases toward free delivery, in contrast to a centrifugal fan. Maximum total efficiency is obtained at a higher percentage of free delivery than for other types. SYSTEM CHARACTERISTICS Any ventilating system consisting of duct work, heaters, air washers, niters, etc., has a system characteristic which is individual to that system, and is independent of any fan which may be applied to the system. This characteristic may be expressed in curve form in exactly the same manner that fan characteristics may be shown. Typical system . characteristic curves are shown as A, B and C in Fig. 5. These curves are drawn to follow the simple parabolic law in which the static pressure or resistance to flow of air varies as the square of the volume flowing through the sys tem. Heating and ventilating systems follow this law very closely and n serious error is introduced by its use. When a constant speed fan curve for a given size fan is super-imposed 772 CHAPTER 33 1956 Guide No 1 -SW, SI No 2-SW, SI No 3 - SW, SI No3-OW,D1 Counter-Clockwise Top Horizontal Clockwise Top Horizontal Clockwise Bottom Horizontal Counter-Clockwise Bottom Horizontal No 7 - SW, SI No 7 -DW, 01 ': ' NoS-SW,Sl ' Fig. 6. Arrangement of Fan Drives Air. 1, SW, SI. For belt drive or direct connection. Wheel overhung. Two bearings on base. ' Arr. 2, SW, SI. For belt drive or direct connection.. Wheel overhung. Bearings in bracket sup ported by fan housing. .' Arr. 3, SW,' si; For belt drive or direct connection.' One bearing on each side and supported by fan housing. Not recommendedun sizes 27 in. diameter wheel and smaller. Arr. 3, DW, DI. For belt drive or direct connection. One bearing on each side, and supported by fan housing. . Arr. 4, SW, SI. For direct drive. Wheel overhung on prime mover shaft. No bearings on fan. Base or equivalent for prime mover. '. - Arr. 7, SW,.SI. For belt drive or direct connection. Arrangement No. 3 plus bsse for prime mover. Not recommended in sizes 27 in. diameter and smaller.. . Arr. 7, DW; DI. For beltdrive or direct connection. Arrangement No.,3 plus base for prime mover. Arr. 8, SW, SI. For belt drive or direct connection. Arrangement No. 1 plus base for prime mover. Arr. 9, SW, SI. For belt drive. Arrangement No. 1 designed for mounting prime mover on side of upon a system characteristic curve, the relation between the two is at once apparent. The only point common to the two curves is the point at the intersection of the system characteristic curve and the fan character istic curve, and it is at this point that the combination will operate. In Fig. 5, system characteristic curves A, B and C cross the fan character istic curve at points X, Y and Z. The fan whose curve is shown, when applied to systems having characteristic curves A, B and C, will deliver 10,000, 13,000 or 16,400 cfm, respectively. The curves in Fig. 5 also illustrate the effect of errors which may be made in calculating the resistance of a ventilating system. For instance, if a given system requires 13,000 cfm, and the resistance to flow of the system has been computed as 1.25 in. static pressure, such a system would be represented by system characteristic curve B in Fig. 5. If a 100 per cent error had been made and the resistance were 2.5 in. instead of 1-25 in., then the system characteristic would'be as shown in curve A, and would cross the fan curve' at 10,000 cfm. Such an error would cause the flow of air to be decreased from a design volume of 13,000 cfm to 10,000 cfm. If the resistance to flow had been over-estimated and the resistance Clockwise Up Blast Counter-Clockwise Up Blast Counter-Clockwise Down Blast Clockwise Down Blast Counter-Clockwise Top Angular Down ' Clockwise Top Angular Down Clockwise Bottom Angular Up Counter-Clockwise Bottom Angular Up Counter-Clockwise Top Angular Up Clockwise Top Angular Up Clockwise - Counter-Clockwise Bottom Angular Down - Bottom Angular Down Fig. 7. Designation of Direction of Rotation and Discharge Note: Direction of Rotation is determined from the drive side for either single or double width or single or double inlet fans. (The driving side of a single inlet fan is considered to be the side opposite the inlet regardless oi the actual location of the drive.) For fan inverted for ceiling suspension, direction of rotation and discharge is determined when fan is resting on floor. actually were 0.625 in., the system characteristic curve would be as shown in curve C, and the fan would deliver 16,400 cfm to the system instead of the design volume of 13,000 cfm. . In this example, extreme errors have been selected to emphasize the effect the square function of the system characteristic has in maintaining the fan performance within comparatively narrow limits. In the first example, a system estimated at half what it should have been resulted in n drop of 23 percent in volume; and in the second example, a system es timated at twice what it should have been resulted in an increase of 26 percent in volume. . In some instances fans may be applied to variable flow systems. In ?nch cases, the limiting systems may be plotted and the effect on fan per formance examined. For instance, a system might have a characteristic jjrve between A, shown in Fig. 5, as one limit, and B as the other limit. Ine fan performance Will then fall between points X and Y on the fan curve at a point determined by the system characteristics at that particular ;774 CHAPTER 33 1956 Guide time. If A and B are the limiting characteristic curves of the systems, the fan performance will never be outside the points X or Y. FAN ARRANGEMENTS Centrifugal fan arrangements have been standardized by the National Association of Fan Manufacturers. Figs. 6, 7 and 8 show the accepted designation as to arrangement of drive, rotation, discharge and motor position, for belt drive. Axial flow fans are either belt driven or direct connected, in accordance with individual manufacturer's arrangements. Usually a choice of anti-friction or sleeve bearings is available. FAN CONTROL In some heating and ventilating systems it is desirable to vary the volume of air handled by the fan, and this may be accomplished by a Location of motor is determined by facing the drive side of fan or blower and designating the motor s sitionbyletlere'W,X,X or Z, **>- Fig. 8. Motor Position, Belt ob Chain Drive number of methods. Where the change is made infrequently, the pulley or sheave on the driving motor, or fan, may be changed to vary the speed of the fan and alter the air volume. Dampers may be placed in the duct system to vary the volume. Variable speed pulleys or transmissions, such as fan belt change boxes, or electric or hydraulic couplings, may be used to vary the fan speed. Variable speed motors and variable fan inlet vanes may also be used to adjust the fan volume. All of these methods will g've control. From a power consumption consideration, a reduction of fun speed is most efficient. Inlet vanes save some power, while dampers save the least. From consideration of first cost, dampers usually are the lowest in cost. In some installations, adjustments of volume are desirable at various times during the day, or continuously. In others, an increased supply of air in summer, over that needed in winter, is demanded. The demands in each case will dictate which type of control is most desirable. Where noise is a factor, lowering the fan speed if possible is preferred as a control means, because of the resulting reduction in sound level. In addition to the above types of control, tubeaxiaL and vaneaxial fans Fans 775 are sometimes made with adjustable blades to permit balancing the fan against the system, or making seasonal adjustment. MOTIVE POWER :y Heating, ventilating and air conditioning fans are usually driven by electric motors, although other prime movers may be used. The small sizes of fans, and especially those operating in the higher speed range, are equipped with direct-connected motors. For larger size fans, and those operating at lower speed, V-belt drives are generally used. In selecting the size of -motor for operating a fan, it is advisable to se lect at least the standard size next larger than the fan requirements. Di rect-connected motors do not require so great a safety factor as belted units. Justification for liberal power provision exists only in systems where it is possible that larger volumes of air may be required at intervals, and made available by use of by-pass dampers, thus greatly reducing the system resistance. If such a system includes a fan with forward-curved blades, it would be necessary that the motor be sized for the maximum volume and duty. If such a system includes fans with backward-curved blades, the volume peak would not make it necessary to provide addi tional motor power. In selecting fans for such a system,- -sound ratings should be given careful consideration. - Where a system is constant, and has no provision for volume change that would materially reduce the resistance, and when the resistance calculations are reasonably precise, there is no necessity for too liberal a motor allowance (even where fans with forward-curved blades are used) if the fan has been properly selected. Fig. 5 shows that the system re sistance varies as the square of the volume, and the fan static pressure varies approximately inversely as the volume, thus greatly offsetting the trend toward both1 increase in air delivery and motor load. Reference to Fig. 5 indicates that there is no justification for allowing large spare motor . capacity. It is generally more economical to operate motors well loaded. Since the power consumption of fans varies as the cube of the speed, very little starting torque is required of the motor. Refer to Chapter 40 for characteristics of various types of motors. : ', ' FAN SELECTION The following information is required to select the proper type and size- offan: .. - 1-Capacity in cubic feet per minute. 2. Static pressure or system resistance. 3- Air density if other than standard. ; Type of application or service. 5. Arrangement of system. 6. Prevailing sound level or use of space served. . 7. Nature of load. . ' " 8- Type of motive power available. ; " ' . .. \ . .. ._ 1, . ...... In order to facilitate the choice of apparatus,.the various fan manu facturers supply fan tables of curves which usually show the. following factors for each size of fan operating against a wide range of static pres- fhfes: (1) volume of air in cubic feet per minute (68 F,; 50: percent -relatlVe humidity,-0.075 lb per cubic foot); (2) outlet velocity; (3) revolutions Per minute; (4) bra.ke horsepower; (5) tip or peripheral speed; And (6) efatic pressure. The most efficient operating point is usually shown by' either bold-face or italicized figures in the capacity tables.' ^ - 776 CHAPTER 33 1956 Guide Often the service determines the type of fan. When operation occurs with little or no resistance, and particularly without a duct system, the propeller fan is indicated for convenience and low c6st. When resistance is low the power required is low, and efficiency becomes a secondary im portance. When a duct system is involved the choice is usually made between a centrifugal fan and a tubeaxial or vaneaxial. At times the capacity-pressure-speed relationship (specific speed)9 dictates a choice. Usually, space, efficiency, sound, cost and serviceability must all be con sidered.10 In general, centrifugal and axial fans are comparable in effi ciency and sound, but the latter are lighter and require considerably less space, especially if arranged for straight-through operation. The compari son cannot be made on the cost of fans only, but the difference in cost of ductwork, mounting and servicing must be included. A vaneaxial is more efficient and quieter than a tubeaxial, but is more expensive, and frequently requires more space. While requiring less space than the centrifugal, the Table 1. Good Operating Velocities and Tip Speeds for Ventilating Fans Static Forward Curved Blade Fans Backward Tipped and Double Tubeaxial and Curved Blade Fans Vaneaxial Fans Inches op Water Outlet Velocity Feet per Minute Tip Speed Feet per Minute Outlet Velocity Feet per Minute Top Speed. Feet per Minute Wheel Velocity Feet per Minute 4 1000-1100 1520-1700 800-1100 2600-3100 1100-1500 iooo-uoot 1000-1200 1760-1900 1970-2150 800-1150 900-1300 3000-3500 3400-4000 1250-1700 1400-1900 i 1200-1400 2225-2450 1000-1500 3800-4500 1500-2100 i 1300-1500 i 1400-1700 2480-2700 2660-2910 1100-1650 1200-1750 4200-5000 4500-5300 1650-2350 1800-2500 ii 1500-1800 2820-3120 1200-1900 4800-5750 1900-2700 nnu2 1600-1900 1800-2100 1900-2200 2000-2400 3162-3450 3480-3810 3760-4205 4000-4500 1300-2100 1400-2300 1500-2500 1600-2700 5300-6350 5750-6950 6200-7550 6650-8050 2150-3000 2350-3300 2500-3550 2700-3800 21 21 2200-2600 2300-2600 4250-4740 4475-4970 1700-2800 1800-2950 7050-8550 7450-9000 3 2500-2800 4900-5365 2000-3200 8200-9850 ______________________ Wheel velocity ie the axial mean air velocity through the inBide diameter of the housing cylinder at the point of wheel location. axial flow fan is inherently less accessible for service. When high-tempera ture air or air containing corrosive elements is being conveyed, motors and bearings should be located outside of the air stream. This requirement may determine the type of fan to be used. Where the system resistance is indefinite or variable, the pressure, horsepower and noise characteristics of centrifugal fans usually indicate their selection. Under such conditions, a steep and constantly rising pressure curve permits less variation in air delivery when the resistance varies. Likewise, a flat sound curve mini' mizes the change of moving into a region of increased noise. A fan having a high efficiency over a wide range is more desirable than one which reaches an even higher maximum efficiency, but decreases more rapidly on either side of a narrow range. A self-limiting horsepower curve may permit more accurate selection of motor size. The selection of size of fan usually involves balancing cost and space against sound and efficiency. Unless the pressure involved is so high that a smaller fan running at greater speed requires a higher class2 of construc tion, the smallest fan is the cheapest in first cost of the fan only. However, as the cost of the driving equipment is also involved in the total installation Fans 777 cost, fan efficiency must be considered for that reason as well as its bearing on the cost of operation. In some cases where large fans operate long hours per year, selection at absolute maximum efficiency is indicated. Generally, however, the power saving by selecting for optimum efficiency does not justify the extra cost, and a slightly smaller fan gives the best balance of cost and efficiency. Reference to Figs. 2 to 4 shows that all types tend to have a minimum sound near maximum efficiency so, when noise is a con sideration, selection approaching maximum efficiency is indicated. Too large a fan may not only mean an unnecessary investment and an increased power consumption and sound, but may also give faulty performance if of . a type having an unstable pressure characteristic at low capacity. Table 1 shows the outlet velocities and impeller tip speeds recognized as good practice for various static pressures for centrifugal, tubeaxial and vaneaxial fans applied to average heating, ventilating and air conditioning applications. Fans for churches, schools, residences and other buildings having a low prevailing noise level should be selected for lower than average outlet velocities. FAN INSTALLATION In designing heating, ventilating and air conditioning systems, the characteristics of the fans available for use therewith should not be ignored. If double inlet fans or multiple fans in parallel are used, care must be taken that both inlets have the same free area and general approach conditions. The dimensions of the ductwork and the size of the various devices whose individual resistances determine the static pressure, dictate the fan selec tion. Often a minor, modification of the system may permit use of a smaller motor, and even a lower elass2 of fan, with considerable saving of cost. Invariably, the sound generated is affected, as fans operating at high pressure produce more noise than at lower pressure (see Chapter 41). Minimizing the resistance may be the best insurance against noise. On the other hand, sometimes the lowest overall cost results from selecting the minimum size of system equipment, and then installing adequate acoustical and vibration treatment. All ducts should be connected to fan outlets and inlets by means of un painted canvas or other flexible material. Access should be provided in the connections for periodic removal of any accumulations tending to unbalance the rotor. When operating against high resistance, or when ambient noise levels are low, it is preferable to locate the fan in a room removed from occupied areas or acoustically treated to prevent sound transmission. The lighter building constructions which are common today, make it desirable to mount fans and driving motors on resilient bases designed to prevent transmission of vibrations through floors to the build-. mg structure. Conduits, pipes and other rigid members should not be attached to fans. Noises due to high velocities, abrupt turns, grilles and other items not connected with the fan, may be present. Treatment of such problems, as well as the design of sound and vibration absorbents, are covered in Chapter 41. FAN APPLICATIONS Many fan applications and the corresponding types of fan commonly m>ed are listed in the following paragraphs. Reference is also made to the chapters where the applications are discussed. Central System Supply Fans (Chapter 30) are usually of the centrifugal 778 CHAPTER 33 1956 Guide type, since this application requires a wide range of satisfactory and quiet operation against relatively high pressures. They can re'adily be connected to apparatus of large cross-section on the inlet side, and to relatively small ducts on the outlet side. Comparative sizes have been standardized among manufacturers, and most rating tables cover a range of 700 to 500,000 cfm, and static pressures from j to 15 in. of water. Central system exhaust fans are predominately centrifugal, but the space conservation of the axial is being increasingly utilized. Tubeaxial and vaneaxial fan sizes are not yet standardized, but several manufacturers list capacities from 2000 to 100,000 cfm, and static pressures up to 3 in. of water. . Exhaust fans are found in all types. Wall fans are predominantly of the propeller type, since they operate against little or no resistance. They are listed in capacities from 1000 to 75,000 cfm. They are sometimes in corporated in factory-built pent houses or roof caps, or are provided with matching automatic louvers. Hood exhaust fans (Chapter 46) involving ductwork, are predominantly centrifugal, especially if handling hot, cor rosive or erosive fumes, where it is best to keep the bearings and drive remote from the air stream. Otherwise, axial fans are applicable, and where little or no ductwork is involved, propeller fans are suitable. Spray booth exhaust fans (Chapter 46) are frequently centrifugal, especially 5 built into self-contained booths. Tubeaxial fans lend themselves particu larly well to this application where ease of cleaning and of suspension in a section of ductwork are advantageous. For such application built-in clean out doors are desirable. Material handling fans (Chapter 46) are always straight radial (or modified) blade centrifugal type. They are of heavier construction, and have fewer blades and greater clearances than ventilating fans. Many characteristics are compromised to provide wear resistance and ease of maintenance. They are commonly listed in capacities from 600 to 60,000 cfm, and static pressures up to 15 in. water. Mine fan applications11 vary greatly and require fans ranging from small portable units for local ventilation, to immense slow speed centrifugal fans, often steam engine driven, for general or emergency ventilation. Vaneaxial fans are well suited to mine ventilation. For underground location, their compactness saves on cost of excavations, and above ground, their ready reversibility is valuable in emergencies, even if reversal causes a reduction in capacity. Marine fans (Chapter 48) are of both centrifugal and vaneaxial types. The latter are particularly well adapted to both combatant and non combatant ships, where compactness and fight weight are invaluable. Unitary systems, i.e., unit heaters, unit ventilators, unit humidifiers, unit air conditioners, unit air coolers and unit evaporative condensers are equipped with centrifugal or propeller fans, the latter usually being limited to the relatively small suspended type where no ductwork is involved. Fans for units having considerable internal or possible external resistance, are mostly of the forward-curved blade, or so-called mixed flow centrifugal type. The latter is really a centrifugal type with axial inlets, having a pressure curve resembling a backward-curved blade centrifugal fan. Both of these types have the high capacities (in relation to displacement) requi site for a compact unit. Ratings are frequently given for these units as separate fans, as well as in conjunction with the various internal resistances- Fans ' 779 In multiple units on a common shaft they are fisted up to 40,000 cfm capacities. ' Cooling tower fans (Chapter 35) are predominantly of the propeller type, but axial types are also used for packed towers, and occasionally a centrif ugal fan is usedto supply forced draft. Circulating fans are invariably of propeller or disk type, and are made in a vast variety of blade shapes and arrangements. They are designed for plearing appearance, as well as utility. General purpose fans are centrifugal fans of conventional design, built for service in the lower capacity ranges. They are built with the fan wheel mounted on the motor shaft, or connected to a self-contained belt driven arrangement. They are listed in capacities from 100 to 20,000 cfm, and static pressures up to 1J in. water. Kitchen fains for domestic use are small propeller fans arranged for win dow or wall mounting, and with various useful fixtures. Their capacities range from 300 to 800 cfm. . Attic fans are used during the warm seasons to draw large volumes of outside air through a house or. other building whenever the inside tempera ture exeeeds the outside, and thereby utilize the cooling effect of the rela tively cool evening or night air. Research by the A.S.H.A.E.12 indicates that a two to three-minute air change is desirable in the North; in the South, a- one-minute change is-.recommended to provide the additional cooling effect of air motion. . - . -. Fans may be centrally located in an attic or other unused space, or in a hallway, and arranged to draw proportionately from several rooms; or local window units may be installed in a single room. Central units draw from the living quarters and discharge into the attic, whence the air escapes through windows or grilles; or the air may be drawn through grilles into the attic with the fan discharging directly outdoors. Discharge openings on the lee side are preferred. Attic fans are usually of propeller type, and should be selected to operate at low velocities to minimize noise. Noise is more of a problem on local units, but care should be taken to prevent transmission of noise or vibration on all installations, because they operate during sleeping hours. Central units are available in sizes from 3,000 to 30,000 cfm, and window units up to 8,000 cfm. Fans For Special Applications Fans are used to handle many gases other than air at normal tempera ture. These range from heated air to many types of fumes, vapors, and industrial gases which may be corrosive, explosive, toxic, radio active or merely noxious. For handling corrosive gases fans should be constructed of a material suitable for the particular gas being handled, although at times it is more Practicable to plan on replacing a unit of standard material at more fre quent intervals. Explosive combinations usually dictate a non-sparking . fan in which either all of the fan, or only those parts which might strike to gether if mal-adjusted, are built of non-sparking materials. Noxious, to*'c, radio-active or pure or valuable gases call for special construction to Prevent leakage. This usually consists of a welded gas-tight housing, uswg flanged inlet and outlet, and some form of shaft seal. In most of these special applications, since it is desirable to keep all bear- 780 CHAPTER 33 1956 Guide mgs, drives and motors outside the gas stream, centrifugal fans are usually used and in arrangements 1, 2, 4, or 8 (Fig. 6). The exception is in the case of fans handling explosive mixtures, where propeller or axial fans are per missible when built with explosion-proof motors and non-ferrous wheels. Fans handling hot air or gas are generally of the centrifugal types and follow arrangements 1 or 8 so that bearings, drives and motors are remote from the heat. If of double inlet type, they have inlet boxes and long shafts to keep the bearings outside the stream. Propeller or axial types are rare when the temperature exceeds 150 F. With temperatures above 600 F special heat resistant materials may be required for the rotors. In addition to a remote location for the bearings, external cooling is fre quently required when the temperature exceeds 200 to 250 F. This is often obtained by use of air cooled or water cooled jackets. With anti friction bearings a heat radiating disk or a small circulating impeller between the fan and the nearest bearing is sometimes sufficient. Oil lu brication rather than grease lubrication is commonly recommended. REFERENCES 1 A.S.M.E. Test Code for Fans (American Society of Mechanical Engineers, PTC 21__1946) ' * Standards, Definitions and Terms in Use by the Fan and Blower Industry (National Association of Fan Manufacturers, Bulletin No. 110, 1952, pp. 2-5). 8 Standard Test Code for Centrifugal and Axial Fans (A.S.H.V.E. and the Na- tional Association of Fan Manufacturers, NAFM Bulletin No. 110, 1952, p. 18). * Sound Measurement Test Code for Centrifugal and Axial Fans (National Asso ciation of Fan Manufacturers, Bulletin No. 110, 1952, p. 33). Noise Ratings of Ventilating Fans, by W. H. Hoppmann II and Fred Lager (A.S.H.V.E. Transac tions, Vol. 51, 1945, p. 271). ,, ` Fan Laws Simplify Performance Calculations, by R. D. Moyer (Power, August 1946) The Centrifugal Fan, by Frank L. Busey (A.S.H.V.E. Transactions, Vol. 21, 7 Energy Transfer Between a Fluid and a Rotor for Pump and Turbine Machinery, by Sanford A. Moss, Chester W. Smith and William R. Foote {American Society of Mechanical Engineers Transactions, 1941). _ . , ,r . U1 * The Characteristics of 78 Related Airfoil Sections from Tests m the Variable Density Wind Tunnel, by Eastman N. Jacobs, Kenneth E. Ward and Robert JVi. Pinkerton {National Advisory Committee for Aviation Report No. 460). Aerodynamic Characteristics of a Large Number of Airfoils Tested in the Variable Density Wind Tunnel, by Robert M. Pinkerton and Harry Greenberg {National Advisory Committee for Aeronautics Report No. 678). , _ _ T , onwF a The Specific Characteristics of Fans, by M. C. Stuart and J. B. Lusk (A.S.H.V .u. Transactions, Vol. 43,1937, p. 57). . , ,,. _ j4 v 10 The Axial Flow Fan and Its Place in Ventilation, by W. R. Heath and A. a- Criqui (A.S.H.V.E. Transactions, Vol. 50,1944).. 17 "Mine Ventilation, by J. J. Walsh (A.S.H.V.E. Transactions Vol. 23, 1917, P 659). Mine Ventilation and Its Relation to Health and Safety, by D. Harrington (A.S.H.V.E. Transactions, Vol. 51,1945, p. 243). .,, Comfort Cooling with Attic Ventilating Fans, by G. B Helmnch mid U Tuttle (A.S.H.V.E. Transactions, Vol. 40, 1934, p. 155). A.S.H.V.E. Research Report No. 979--Study of Summer Cooling in the Research Residence for. the bum mer of 1933, by A. P. Kratz and S. Konzo (A.S.H.V.E. Transactions, 'Vol. 40, p. 167). A.S.H.V.E. Research ReportNo. 1198--The Effect of Attic Fan Opera ^ on the Cooling of a Structure, by W. A. Hinton and A. F. Poor (A.S.H.V.E. Tr tions, Vol. 48, 1942, p. 145). The Installation and Use of Attic Fans, by Badgett (Agricultural and Mechanical College of Texas Bulletin No. Some Effects of Attic Fan Operation on Comfort, by W. A. Hinton and W. O. wa maker (A.S.H.V.E. Transactions, Vol. 50,1944, p. 371). bibliography The Centrifugal Pumps and Blowers, by A. H. Church (John Wiley & Sons). Fan Engineering, Buffalo Forge Co. _T.,,, Fans, by Theodore Baumeister, Jr. (McGraw-Hill). ,. The Theory and Performance of Axial Flow Fans, by Curt Keller, Ad p Lionel S. Marks and John R. Weske (McGraw-Hill). by CHAPTER 34 AIR CLEANING Atmospheric Air Cleaners: Airborne Particulate Matter, Viscous Impingement Filters, Dry Air Filters, Electronic Air Cleaners, Air Filter Performance, Selection, Maintenance, Installation, Adsorption of Vapors; Industrial Air and Gas Cleaners: Degree of Cleaning, Selection, Types, Application, Inertial Separators, Scrubbers, Wet Collectors, Filters, Electronic Precipita tors, Adsorbers, Absorbers, Combustion Devices AIR cleaning devices remove contaminants from an air or gas stream. A They are available in a wide range of designs to meet various air cleaning requirements. Degree of removal required, quantity and char acteristics of the contaminant to be removed, and conditions of the air or gas stream will have a bearing on the device selected for a given applica tion. Definitions and a discussion of contaminant characteristics are given in Chapter 8, together with some consideration of their origin. Air cleaning devices are divided in this chapter into two basic groups: Atmospheric Air Cleaners, described in Part I, and Industrial Air and Gas.Cleaners, described in Part, II. Atmospheric Air Cleaners are ordinarily used to remove particulates such as are found in outside air, and are employed in ventilation, air conditioning, and heating systems where dust content seldom' exceeds 4 grains per 1000 cu ft of air. Industrial Air and Gas Cleaners are ordinarily used for the heavier concentrations encountered in local exhaust ventilation where the particu late content (loading) ranges from 100 to 20,000 grains per 1000 cu ft of an-. Because of these heavier loadings, atmospheric air cleaners can seldom be used for the control of process aerosols in industrial applications. PART I--ATMOSPHERIC AIR CLEANERS Conventional air filters and electronic air cleaners are installed in air handling systems to remove dusts. These dusts constitute a mixture of particle sizes within the classification of temporary and permanent im purities listed in Fig. 1, Chapter 8, including bacteria, pollens, house dusts, and similar allergens which motivate attacks on persons of allergic sensitivity.1- * Since the purpose of the filter or cleaner is to free the air of as much existing contamination as practicable, the degree of air cleanliness required should influence the choice of apparatus. Atmospheric dusts are mixtures of particles in all sizes. The removal of these particles and fractions becomes progressively difficult as the particle size decreases. Smoke Prides are of major importance in many applications. Air cleaners Wld justify their cost through a reduction in housekeeping expense in the 781 782 CHAPTER 34 1956 Guide ventilated space, by the protection of the equipment in the ventilation system itself, and by providing relatively dust-free air for critical manu facturing processes. Cleaning devices for atmospheric air are classified by the principle employed to collect dirt particles:' i.e. impingement on viscous coated media, filtration through porous media, or electronic air cleaning. In some cases a filter may display a combination of these principles. Bach type of air cleaner has certain advantages. There are applications where it is desirable to pass air through a series of two or more different types to obtain optimum results. AIRBORNE PARTICULATE MATTER Suspensions of particulate matter in the air are called aerosols and con sist of smokes, dusts, mists, and fumes. The characteristics of the aerosols which affect the performance of an air cleaner include particle size, con centration, shape, density, velocity, and surface characteristics. One of the most important of these is size. . The rate of settling of particles varies approximately as the square of the diameter. Particles larger than 10 microns in diameter settle so rapidly that the concentration of such particles decreases rapidly as the distance from the source increases. Particles less than 1 micron in size settle so slowly that the ordinary convection currents prevent sustained downward motion, and consequently such particles remain in the air for long periods. If particles could be examined through a super microscope having a magnification of 250,000 diameters, a tobacco smoke particle of 0.1 micron would appear to be 1 in. in diameter, or approximately the size of a golf ball; a soft coal smoke particle 0.3 micron in diameter would appear like a baseball; a ragweed pollen grain of 20 microns in diameter would appear 16.5 ft in diameter, while the 50 micron particle (just visible to the naked eye and able to pass through a 270 mesh screen) would appear to be 50 ft in diameter. Consideration of this range in particle size from a golf ball to a sphere 50 ft in diameter will emphasize the difficulty of devising any single test to measure adequately the performance of air cleaning devices under all conditions of service. The particles in the atmosphere can range in size from less than 0.01. micron up to things which are caught by an ordinary fly screen, such as lint, feathers, and insects. Almost all conceivable shapes and sizes are represented. The material is very commonly soot, ash, soil, lint, smoke, and fumes, but may include particles of almost any inorganic or organic material and even such living organisms as virus, bacteria,3 and fungus spores. This wide variety makes it impossible to design one type of cleaner which will be best for all applications. Mechanical filters of the low pres sure type can remove large particles effectively. Other mechanical filters can remove extremely fine particles, but may be handicapped somewhat by high pressure drop and cost. Electronic air cleaners have the ability to give high effectiveness on normal atmospheric contamination, with a low operating pressure drop. As a general rule, the removal of the coarser dust particles and lint from the ventilating air produces tangible results in so far as cleanliness m a house or building is concerned, because much of the finer dust remains Air Cleaning 783 suspended in the air and is removed from the building by the circulating air. However, since some of the fine dusts, especially smoke and fume particles, are undoubtedly deposited by means other than settling, such as electrical or thermal precipitation4'6 and by contact, the ability to re move small particles is desirable in an air cleaner if it can be obtained at not too great a cost. VISCOUS IMPINGEMENT TYPE FILTERS The viscous impingement type of filters 1 consist of relatively coarse media constructed of a suitable fiber, screen, wire, mesh, metal stamping or plates, or a combination of medias. The filter may be of the unit type manually-cleaned, the replaceable type, or the self-cleaning type. The medium in a viscous impingement type filter is usually a fiber pack for non-automatic types, or a series of metal plates for automatic self cleaning types. In either case, the medium is treated with a viscous substance, often an oil or grease, called the adhesive or the saivrant, in tended to retain dust particles which come in contact with it. Also, in either case, the arrangement is such that the air stream is broken up into many small air streams, and these are caused to change direction abruptly a number of times in order to throw the dust particles, by momentum, against the adhesive. Several desirable characteristics of an adhesive for air cleaners of this type are: (1)' its surface tension should be such as to produce a homogeneous film or coating on the filter medium; (2) the vis cosity should vary only slightly with normal changes of temperature; (3) it should prevent the development of mold spiores and bacteria on the filter medium; (4) the liquid should have high capillarity, or ability to wet and retain the dust at all operating temperatures; (5) evaporation should be slight; (6) it should be fire resistant; (7) it should be odorless. . Various fibrous materials have been used as filtering media in unit filters of the viscous impingement type. These include glass fiber, steel wool, similar wool of non-ferrous metals, wire screen, animal hair, hemp fibers, and other materials. In such filters, the medium is often packed more densely on the discharge than on the approach side, in order to increase the dust holding capacity. This results in a selective arrestance of dust with the larger particles nearer the approach face. The arrangement also permits some penetration of lint into (but not through) the filter, so that the amount of lint which can be tolerated on the filter is also increased, fhxe to plane surface area the viscous impingement type filter, however, ay be inferior to some dry types if the air carries a high percentage of lint. . The resistance of air filters obviously increases with the rate of air flow through them. Face velocities of about 300 fpm, and resistances in the range from 0.1 to 0.2 in. water, when the device is new and clean, are usual for ventilation system filters. . Filters designated as high velocity units are also available. In most rostances these filters employ a uniform media pack and give best per formance at velocities about 500 fpm. Impingement type air filters should hold a substantial amount of adhesive so that the dirt collected by the filter will be retained. The design and construction should also provide a goodly proportion of free space through the media so that high velocities ^n be used without excessive resistances. The design should assure that the media throughout the thickness of the filter will be effectively utilized 784 CHAPTER 34 1956 Guide and therefore, the filter should be designed to minimize the formation of a clogging dirt mat on the filter face. High velocity filters are apt to be adversely affected if the amount of lint in the air to be cleaned is excessive. ' The resistance of filters increases with dust or lint loading, and it is the resistance due to this cause which ordinarily necessitates servicing. The rate of loading obviously depends upon the amount as well as the kind of dust in the air, and for this reason, periods between servicing cannot be predicted with certainty. Manometers are often installed to indicate the pressure drop across filter banks, and they serve to indicate when the filter requires cleaning. The pressure drop tolerated differs between operators and system designs. The resistance of a filter, bank can be kept desirably low by periodically servicing some, but not all,'of the units in the bank at one time. It is to be noted that a decline in efficiency may be the limiting factor in filter life, rather than increased resistance due to load. - The method of cleaning viscous impingement unit filters differs for differ ent types of filters and kinds of dust. Much dry dust or lint can often be removed by rapping the filter. Throw-away filters are constructed of inexpensive materials, and are designed to be discarded after one period of use. The frame is frequently a combination of cardboard and wire. Cleanable filters usually have metal frames. Various cleaning methods have been recommended including: air jet, water jet, steam jet, washing in kerosene, and dipping in an oil. The last may serve both to clean the filter and add the necessary adhesive. . It is not mandatory that unit filters be removed from their metal frames for cleaning outside of thesystem. Cleaning of unit filters in place isfeasible by means of hot water sprayed from a hose or by means of fixed nozzles to accomplish washing and adhesive application. Where filters are cleaned in place, provision should be made to collect and drain the water so as to prevent leakage from the filter housing. Moving-Curtain Viscous Filters In the moving-curtain air filter, means are provided to remove the dust from the medium mechanically. Filters with moving cloth media are available essentially for lint removal. The medium in a typical moving-curtain filter at present consists of a series of specially formed metal plates mounted on a pair of chains. The chains are mounted on sprockets located at the top and bottom of the filter housing, so that the filter medium can be moved as a continuous curtain up one side and down the other side of the sprockets. The arrange ment is such that, at the bottom, the medium passes through a bath of special oil which both serves to remove the dirt from the plates, and acts as an adhesive when the cleaned plates next pass through the air stream,. The plates forming the filtering medium or curtain usually overlap each other, and due to their special shape, many small air passages are formed between them. These air passages turn abruptly one or more times m order to give the impingement effect. An electrically driven rotating device is usually supplied with a moving- curtain filter. The device may be set to move the curtain periodically! or a special switch, actuated by pressure drop, may be used to govern its motion. In operation, the resistance of an automatic filter will remain Air Cleaning 785 approximately constant as long as proper operation is obtained. A resistance of }4 in. water at a face velocity of 500 fpm is typical of this class. . DRY AIR FILTERS The media in such filters are usually fabrics or fabric-like materials. Media of wool felt, cotton batting (both, glazed and unglazed), cellulose fiber and other materials have been used commercially. The medium in a filter of this class is usually supported by a wire frame in the form of pockets or V-shaped pleats in order to increase the area exposed to the passage of air. A 2-ft square unit may contain from 15 to 30 sq ft. of medium. . Dry air filters, by virtue of the large area of medium used, have a'com paratively high lint holding capacity. The efficiency of dry type filters is usually higher than that of viscous impingement filters, while the life of the former based on dust holding capacity, may be lower. Dust tends to clog the fine pores or openings of dry filters more quickly, thereby causing a higher rate of resistance rise than for viscous impingement filters. Effi ciency with very fine particles equivalent to that of electronic air cleaners is not uncommon with certain types of dry filters. A comparatively deep bed, H to 1 in. thick, of filtering media having individual fibers in the order of 1 micron in diameter, is required for such high efficiency. Dry filters may consist of a cleanable medium held in permanent frames, or a throw-away or replaceable filtering medium held in permanent frames, or the entire filter may be of the throw-away type. Usually the filter ing medium alone is replaced after having collected its full dust load. ELECTRONIC AIR CLEANERS Two principal types of electronic air cleaners are available for air filter application: (1) ionizing type collectors where particles are given a definite charge by passing through an ionization zone, and (2) charged media type collectors where the energized, collecting medium induces a charge on the particles.' Ionizing Type Electronic Air Cleaner Electronic air cleaners use electrostatic precipitation principles to collect particulate matter, see Fig. 1, but operate on much lower voltages than the type commonly used on industrial stacks. The designation Electronic Air Cleaner has been standardized to distinguish the class of electrostatic precipitator which alone is suitable for cleaning ventilating air. In a typical case, a potential of 12,000 volts may be used to create the ionizing field, and some 6000 volts between the plates upon which the precipitation of dust occurs. These voltages, which are capable of mo mentary shock to personnel similar to that of a spark plug, necessitate some safety measures. A typical arrangement provides means for making the equipment inoperative when any door affording access to high voltage parts is opened. Operation can be resumed only after all doors are closed. The voltages necessary for operation of the equipment are usually obtained by means of electronic high voltage direct current power packs operating from a 110-120 volt, 60 cycle, single phase building service. Electric power consumption is about 10 watts per 1000 cfm, plus the approximately 40 watts required to energize the rectifier tube heaters. . Air cleaners of this type offer negligible resistance to air flow and, 786 CHAPTER 34 1956 Guide therefore, care must be exercised in arranging the duct approaches on the entering and leaving sides of the cleaners in order that the air flow may be distributed uniformly over the cross-sectional area. The efficiency of the electronic air cleaner is sensitive to air velocity, and the device itself has much less tendency to rectify the air stream than filters which have higher resistances. In most systems, resistance is deliberately added in the form of a perforated plate, pre-filters or after-filters for the purpose of obtaining a uniform distribution of air. The resistance, including the baffles or after-filters, is constant and generally ranges from 0.15 to 0:25 in. of water at the usual velocities of 300 to 400 fpm. Such plates or filters, however, cannot compensate for defects in the duct layout ahead of the cleaner. Suitable screens of no coarser than 16 mesh should be installed across all Air Cleaning 787 means are employed. The dielectric filtering medium may consist of glass fiber mat, cellulose mat or other similar material, and is supported on or in contact with a gridwork consisting of alternately grounded and charged members, the latter usually being held at a potential of 12,000 volts d.c. An intense and non-uniform electrostatic field is thus created through the dielectric medium. Airborne particles approaching the field are polarized and drawn toward filaments or fibers of the media. The general arrange ment illustrating this type of filter is shown in Fig. 2. . The precipitator of this type offers resistance to air flow, when clean, on the order of 0.10 in. of water at 250 fpm velocity and, unlike the ionizing type, the resistance of the charged media type electronic cleaner rises as dust is accumulated on the media. Because of these characteristics the filter tends to equalize the air distribution over the face of the filter. Like Fig. 1. Diagrammatic Cross-Section of Ionizing Type Electronic Air Cleaner outside air entrances to prevent insects, leaves, bits of paper and similar material from entering the cleaner. Where lint is present in appreciable quantities, devices for lint removal should be installed ahead of the cleaner. Electronic air cleaners of the ionizing type are efficient, low pressure drop devices for removing fine dust and smoke particles. They are avail able in fixed collector-plate and moving collector-plate types. The fixed collector plates are often coated with a special oil as an adhesive. Cleaning is generally accomplished by washing the cells in place with hot water from a water hose or by means of fixed or moving nozzle systems. The bottom of the equipment is made water tight and provided with a drain. In one moving-plate type, the grounded elements on which the dirt collects are mounted on chains, and are alternately dipped in oil and exposed to the air stream. Charged Media Electronic Air Cleaners The charged media type air cleaner consists of a dielectric filtering medium, usually arranged in pleats as in typical dry filters. No ionization Fig. 2. Cross-Section Diagram of Charged Media Type i^LECTBONIC AlB CLEANER typical replaceable media mechanical filters, the charged media precipitator is serviced by replacing the'filtering medium. The dielectric properties of the media are impaired when the relative humidity exceeds 70 percent. AIR FILTER PERFORMANCE AND TESTING Air filters are generally rated in terms of the total air flow for which they are designed, expressed in cubic feet per minute. Face velocity is defined as the average velocity of the air entering the filter, and it is determined by taking the air flow and dividing it by the area of the duct connection h> the cleaner in square feet. Filters are often rated at a face velocity in the range of 250 to 500 fpm. Resistance to air flow is usually measured in inches of water column. The resistances of filters when new and clean, and when operated at rated capacity, are generally available from the manufacturer (see Catalog Data Section). A suitable allowance should be made in system design for increase of filter resistance due to the accumu lation of dust. The ability of air cleaners to clean air is called the efficiency or the arrestance, and may be denoted by the symbol E. The efficiency of an air , , i j i 788 CHAPTER 34 1956 Guide cleaner differs with the size and nature of the dust on which the cleaner operates. The efficiency of an air cleaner, algebraically expressed, is . Di ~ D, E- = D, (1) where Di = amount of dust per unit volume in uncieaned air. Di = amount of dust per unit volume in cleaned air. Several methods have been investigated for evaluating Dj and Dj>. The particle count method is not used for efficiency evaluation, except in in vestigation of filter performance on specific particles such as pollen, or on certain industrial dusts harmful to health. Dust particles can be captured on microscope slides by means of one of the various kinds of impingement devices. The process is useful if inspection and analysis of dust are de sired, but particle counting is not sufficiently precise for evaluating the efficiency of a cleaner operating on a heterogeneous dust. A weight method of evaluating efficiency was described in a former code of the American Society of Heating and Air-conditioning Engineers and incorporated in a code.6 For this test, a known weight of a prepared dust is injected into air supplied to the filter, and the quantity of dust in the cleaned air is determined by extracting and weighing the dust from a known volume of the cleaned air. Dust ex traction from the air is accomplished by drawing the air through a po rous crucible or thimble by means of a high vacuum. . Caution is to be exercised in interpreting published air filter arrestance data, since the test efficiency may be somewhat higher than that which will be obtained in an installation with respect to the ventilated space. The dust-spot or blackness test for cleaner efficiency was developed at the National Bureau of Standards.' The test consists of drawing samples of cleaned air and of uncleaned air through filter papers simultaneously. One 6uch test apparatus consists of a means of drawing samples of air simultaneously through two filter papers, one on each side of a light cham ber. The intensity of light from a single bulb passes through these papers and falls on two photo-cells. The cells are connected to the same gal vanometer and if the light falling on one cell decreases faster than the light falling on the other, the galvanometer moves off the zero position. The flows of air through the filter papers are kept in such ratio as to keep the galvanometer on the zero position, showing that the papers are be coming dirty at equal rates. The ratio of the sampling rates is then an index to the efficiency of the filter under test.7 Actual atmospheric contami nation is commonly used as the basis of test. The National Bureau of Standards has also used prepared dust and lint, in its air cleaner testing apparatus, two injectors for contaminant being used. One injector is used to contaminate the air stream with Cottrell precipitate, previously described. This dust is used to make both effi ciency determination and dust-holding capacity tests. The.other injector contaminates the air stream with cotton linters with which lint-holding capacity tests are made. The curves in Fig. 3 illustrate the difference in the characteristics of two filters, one a viscous-impingement type and toe other a dry filter with a cellulose fiber medium. The two injectors can be operated either separately or simultaneously. Air Cleaning 789 Dust-holding capacity is defined as the amount of dust which a filter can retain and have a resistance less than some arbitrary value. The term applies only to fixed type air cleaners. Determination of dust-holding capacity is an objective of each test under the former A.S.H.V.E. Code.6 Curves are obtained during such tests to show the relation between dust load and resistance. Fig. 4 indicates the range of resistance to air flow found in tests of four unit air filters. Type A is a dense pack used in bacterium control; Type B is a medium pack used for general ventilation work; Type C is a low re sistance unit, for use where low resistance is the important factor and maximum cleaning efficiencies are not essential; and Type D is a high- velocity viscous-impingement filter. Fig. 3. Dust and Lint Holding Capacity of Two Filters SELECTION AND MAINTENANCE To evaluate filters and air cleaners properly for a particular application, two factors should be carefully weighed: (1) the degree of air cleanliness required and (2) disposal of the dirt after it is removed from the air. These factors affect initial costs, operating costs and the extent of maintenance that will be required. Savings that accrue through reduction in house keeping expenses, protection of valuable property and equipment, ability to carry on dust-free manufacturing processes, improved working condi tions, and even health benefits should be credited against the cost of installing and operating an adequate system. The capacity and physical size of the unit required may emphasize the need for self-cleaning features. Operating costs, predicted life, and efficiency are more important than first cost, because air cleaning is a continuing process. While electronic air cleaners have a higher first cost, they exhibit very nigh efficiencies in cleaning atmospheric air, due largely to their ability to remove fine dust which shows no gravitational effect. They are equally effective on coolant oil mists from high speed cutting and grinding machines. System resistance remains unchanged as dirt is being collected, and the 790 CHAPTER 34 1956 Guide ' resulting residue is disposed of directly to prepare the equipment for further duty. The charged-media type cleaners are less effective than the ionizing type, but are appreciably better than -mechanical filters in the matter of small particle collection. The advantage of the moving-curtain impingement type filter consists in the small amount of attention which it requires. Such devices are therefore to be recommended where labor is scarce, or where reliable and frequent attention to filters cannot be assumed. The constant pressure drop of this type of filter is an advantage. The first cost is substantially greater than that of unit filters, and the dust arrestance may not be any higher. ' Unit filters constitute the majority of air cleaners now in use, and some choice is possible between the types available. Where lint in an eminently dry state predominates, a dry filter obviously may be preferable to other '600~--------TOO 800 900 IOOO "00 AIR THROUGH FILTER - CUBIC FEET PER MINUTE 1200 Fig. 4. Resistance to Aib Flow of Foub Unit Air Filters types because of its lint-holding capacity. If the lint is greasy, or if oil vapor exists in the air, the dry filter, if it is of the cleanable type, may be troublesome, since grease tends to make it difficult to clean. Most dry types, however, employ a throw-away type of medium which is held in permanent metal frames so that the difficulty of cleaning the medium is avoided. Some dry filters are capable of high efficiencies, compared to other unit filters on fine particles, but their dust-holding capacity for such dust may be inferior to that of the viscous impingement type. Viscous impingement unit filters are practically standard in size, and their overall dimensions are small when compared with their ratings. Throw-away units are often installed in series so that the one in front, which usually becomes plugged with lint, can be discarded, after which the downstream unit is moved to the front and replaced by a new unit. Viscous impingement unit filters do not have efficiencies as high as can be expected with some other types of unit filters, but their first cost and upkeep are generally lower, whether of the cleanable or the throw-away type. , They require more careful attention than the moving-curtain type if the resistance is to be maintained within reasonable limits. FILTER INSTALLATION Many air cleaners are available in units of convenient size for handling when installing, cleaning, or replacing. Such units are usually designated Air Cleaning 791 as filters or unit filters. A typical unit filter may be 20 in. square and from one to several inches thick, depending on the manufacture and proposed use. In large systems, a number of such units are installed adjacent to each other and collectively called a bank of filters. Air cleaners are commonly installed in the outdoor air intake ducts of buildings, and generally in the recirculating and by-pass air ducts as well. Cleaners are logically placed ahead of heating or cooling coils and other air conditioning equipment in the system to protect them from dust. The character of the dust arrested by the filters in an air intake duct is likely to be mostly particulate matter of a greasy nature, while lint may pre dominate in dust from within the building. . The published performance data for all air filters are based on straight through unrestricted air flow. Filters should be installed so that the face area is at right angles to the air flow whenever possible. Eddy currents and dead air spaces should be avoided, and air should be distributed uni formly over the entire filter surface, using baffles or diffusers if necessary. Failure of air filter installations to give satisfactory results can, in most cases, be traced to faulty installation or improper maintenance or both. The most important requirements of a satisfactory and efficiently oper ating air filter installation are: 1. The filter must be of ample size for the amount of air it is expected to handle. An overload of 10 to 15 percent is regarded as the maximum allowable. When air volume is subject to increase, a larger filter should be installed. 2. The filter must be suited to the operating conditions, such as degree of air cleanliness required, amount of dust in the entering air, type of duty, allowable pressure drop, operating temperatures, and maintenance facilities: 3. The filter type should be the most economical for the specific application. The first cost of the installation should be balanced against efficiency and depreciation as well as expense and convenience of maintenance. The following recommendations apply to filters installed with central fan systems: 1. Duct connections to and from the filter should change size or shape gradually to insure even air distribution over the entire filter area. 2. Sufficient space should be provided in front as well as behind the filter to make it accessible for inspection and service. A distance of two feet may be regarded as the minimum. 3. Access doors of convenient size should be provided in the sheet metal connec tions leading to and from the filters. 4. All doors on the clean air side should be lined with felt to prevent infiltration of unclean air. All connections and seams of the sheet metal ducts on the clean air side should be as air-tight as possible. 5. Electric lights should be installed in the chamber in front of and behind the air filter. 6. Filters installed close to an air inlet should be protected from the weather by suitable louvers, in front of which a large mesh wire screen should be provided. 7. Filters, other than electronic air cleaners, should have permanent indicators to give a warning when the filter resistance reaches too high a value. Safety Requirements An investigation of safety ordinances should be made by the engineer when the installation of an air cleaner of any considerable size is contem plated. It is possible that combustible filtering media may not be per mitted in accordance with some existing local regulations. Combustion 792 CHAPTER 34 1956 Guide of dust and lint on a filtering medium is possible/though the medium itself may not bum. , ADSORPTION OF VAPORS OTHER THAN WATER Many of the foreign gases in the atmosphere are selectively adsorbed by charcoal. Included are many of the organic gases, such as those emanating from animals and people, some of the gaseous constituents of combustion, alcohols, ketones, esters, and gaseous products of putrefaction. Charcoals differ widely in their adsorptive capacity. Those which have marked adsorption characteristics, such as properly prepared coconut shell charcoals, are sometimes called activated, charcoals or activated carbon. These materials can adsorb approximately 50 percent of their own weight of many organic gases at 70 F. The charcoal may be used for a long time by reactivation at high temperatures, under which condition it gives up the adsorbed gases. Temperatures of approximately 1000 F are desirable for reactivation. Charcoals for use in air handling systems should be able to stand physical handling, including reactivation, without excessive loss by breakage or dusting. As applied in air handling systems, the charcoal is placed in perforated metal containers which are grouped in frames and set in the air stream. The percentage removal of an organic gas, such as carbon tetrachloride; is 95 percent or above, when placed in intimate contact with the carbon at 70 F. In commercial apparatus there -may be a by-pass effect which depends on the physical arrangement of the charcoal containers. This by-passing reduces the percentage removed in the total gas passing through the adsorber. Resistance to air flow is usually selected within the general range of resistance of impingement filters. . The required quantity of recirculated air to be treated is determined by dividing the requirements for contaminant-free air, minus the outdoor air, by the fraction denoting the percentage removal of the gas in question in the adsorber bank which is to be used. Adsorbers may be applied to reduce objectionable gases entering through the outdoor air inlet. They may also be used to reduce the odors caused by exhausts from processing. Adsorber beds, in all cases, should be pro tected from dust, free oil and grease. . PART H--INDUSTRIAL AIR AND GAS CLEANERS Industrial development and growth of industrial areas have had a cumulative effect upon the problem of controlling contaminants. Not only has the atmosphere in many cities become more polluted, but the intensity of pollution at the points of control has increased. Accompanying this increase in pollution there has been a growing consciousness of the need for more effective air cleaning among housewives; store managers, industrialists and legal inspectors, and this has resulted in increasing severity of regulations pertaining to collection of dust and contaminants. Air cleaning for the supply system is usually accomplished by means of some type of air filter. To prevent escape of industrial dust into the at mosphere, some type of collector is required. An industrial air clean ing installation is designed to perform one or more of the following 6 functions: 1. Prevent a nuisance or physical damage to an individual, a plant, or adjacent property. Air Cleaning 2. Prevent re-entry of contaminants to working Bpaces. 3. Reclaim usable material. 4. Reduce fire, explosion, or other hazards. 5. Permit recirculation of cleaned air to working spaces. 6. Allow utilization of cleaned gases for processes. . - . 793 ' " DEGREE OF AIR CLEANING REQUIRED The amount of material which can be discharged is established by local or state regulations prepared by pollution control, labor or health depart ments. Standards are established to prevent injury to persons or property. The need for control within the plant is often of prime interest to the industrialist for protecting his equipment, improving his product, and providing a clean. working environment. The re-entry of contaminants to working spaces is prevented by effective air cleaning devices since only a clean effluent is discharged to the ambient atmosphere. Public nuisance complaints often occur even when the effluent concentration discharged to the atmosphere is below the permissible limits of concentration and visi bility. Plant location, contaminants involved,, and meteorological condi tion of the areas must be evaluated in addition to existing regulations or codes of good practice. Fire and explosion hazards are created by combustible dusts, vapors, or gases. Safety may be affected by loss of visibility, settlement, or accumulation of various materials. The cleaning: device can .prevent these hazards by providing an effluent below the inflammation limit, visibility index, and point where settlement or accumulation will occur. ' The degree of air cleaning for the recovery of useable material -.is. a matter of economic evaluation which will vary with such factors as quantity and value of material collected, capital cost, and operating cost. .' . .. Air cleanliness must be of the highest order where toxic materials are involved and the cleaned air is recirculated to the workroom., ; Such recirculation is considered poor practice and is prohibited by many regular tions where toxic materials are involved, except for those cases. :where discharge to atmosphere is impossible or decidedly impracticable; . Where air is recirculated, its contamination must not exceed . the established maximum allowable concentrations listed in Chapter 8. Usual require ments are a fraction, often ^ to of this standard, depending.on: regu lation involved, air quantities recirculated in relation to the cubical content of working space, and the presence of other exhaust systems discharging to the atmosphere. .. Cleaning requirements for the utilization of cleaned gases are dependent on the process and are generally of the highest order (usually comparable to atmospheric air cleanliness). Regardless of standards it is good practice to install the most effective collection equipment available in the light of practical operation features, installation, and equipment costs. This is. warranted because the required degree of cleaning is increasing continually. . FACTORS AFFECTING SELECTION Selection of an industrial air cleaner for a giyen application requires an evaluation of the following 5 considerations: .' 1- Concentration, particle size, and size distribution of the contaminant. 794 CHAPTER 34 1956 Guide 2. Degree of cleaning.required. 3. Conditions of air or gas stream with reference to temperature, moisture content, and chemical composition. ' 4. Characteristics of the contaminant, corrosiveness, solubility, adhesion, or packing, and its specific gravity, surface, and shape. 5. Methods of disposal or salvage that<meet the conditions imposed by material, process, or plant location. . In view of the range of these variables, all available test, data, applica tion experience, and manufacturers' performance data should be considered. TYPES AND APPLICATION There are a number of principles involved in the operation of industrial air and gas cleaners. They are illustrated by the following types of cleaners: . . 1. Inertial Separators (Gravitational or inertial force principle): Baffle Chambers, Centrifugal Collectors. 2. Scrubbers and other Wet Collectors: Air Washers, Wet Filters or Packed Towers, Spray Towers, Centrifugal or Inertial Scrubbers, Venturi Scrubbers. 3. Filters: Fabric Filters, Ultra or Absolute Filters. 4. Electrostatic Precipitators. 5. Adsorbers, Absorbers, and Combustion Devices. Units employing these principles may apply them singly or in. combina tion. The important characteristics of any unit are: its collection effi ciency, resistance to air or gas flow (power requirements), ability to maim tain specified air or gas flow during its operating cycle, and maintenance requirements. In relation to industrial air cleaners, efficiency of collection is generally presented on a basis of weight removal. In many instances, collection efficiency is expressed in terms of weight removal in specific particle size ranges. Occasionally efficiencies are given in terms of visibility or photo metric evaluation. Under other circumstances efficiencies are stated by particle count. For most process recovery problems and air pollution control, the weight basis has been adequate. When loss of visibility is the major problem, light opacity measurements may be required. From a hygienic viewpoint where air is to be recirculated, only the contaminant concentration in the recirculated air stream, rather than the correction efficiency, should be considered. Correlation between the various efficiencies is poor due to the wide variation in particle size, size distribution, and shape. Resistance or pressure drop through any given collector is related to the operating principle, and varies about as follows: low resistance col lectors--up to 2 in. water; medium resistance collectors--2 to 8 in. water; high resistance collectors--8 to 25 in. water. In mechanical centrifugal collectors of the wet or dry type (power driven impellers or rotors) resistance alone is not of significance since these devices are also air movers and therefore the factor of paramount importance is the overall power consumption of the unit. This is also true of certain types of wet collectors which require auxiliary pumping power. ' The ability of any unit to maintain specified air or gas flow during it5 - operating cycle is also a function of its operating principle. For example; Air Cleaning 795 inertial collectors of the simple and centrifugal type are able to maintain constant resistance regardless of concentration and particle size. However, adhesive materials may collect at the entry, throughout the unit, and at the exit, and thus cause a reduction in air flow and serious maintenance problems. With the exception of packed towers and wet filters, wet collectors operate at constant resistance throughout their operating cycles. However they may also be adversely affected by adhesive or corrosive materials. Wet filters or packed towers will eventually become clogged because of retention of inert dusts. Units employing fabric or other filter media will have resistance influenced by the concentration, particle size, shape and packing characteristics of the aerosol. Their overall resistance during the operating cycle may increase gradually over a known or determined period. Auxiliary cleaning devices such as separate compart ments, alternately shaken, reverse air flow, or reverse jet air flow may main tain constant or nearly constant resistance or insure only small fluctuations in air or gas flow. Electrostatic precipitators have the outstanding char acteristic of maintaining a constant air flow with an accompanying low resistance. Adsorbers behave similarly to packed towers in that they provide constant resistance until dhe voids become seriously plugged with inert dusts. This generally requires a matter of several months on normal applications;-- It has been found that inertial separators require the least maintenance. Simple wet collectors rank next in this respect. Complex wet collectors and fabric arrestors require maintenance on a definitely scheduled basis. Electrostatic precipitators require the usual maintenance connected with high voltage equipment and may vary widely. The maintenance of adsorber type unite is minimal and is based primarily on the amount of inert material encountered. INERTIAL SEPARATORS There are many types in this group. These range from simple settling chambers utilizing gravitational forces, to complex centrifugal devices using abrupt directional changes or motor driven rotors. They all have the desirable features of constant resistance during their operating cycle and do not require any special construction for temperatures under 750 F; Usually they require less maintenance than other types of collectors. On the basis of their important characteristics inertial separators may be classified according to Table 1. SCRUBBERS AND OTHER WET COLLECTORS In these collectors many methods are used to wet the contaminant and remove it from the air stream. A number of wet collectors are similar in design to dry collectors with the addition of sprays or liquid contactors. The mechanism of separation in wet collectors depends on inertial forces such as impaction and impingement, and in some cases, diffusion. Wet collectors do not require any special construction for high temper atures. They are suitable for use> on mixed contaminants such as gases and solid or liquid particles. The collection of dust in a wetted form elimi nates a secondary dust problem in disposal of collected material. Pro tection against corrosion and freezing may be necessary and disposal of waste liquids may become a problem. With the exception of the packed 796 CHAPTER 34 1956 Guide towers and wetted filters they all have a constant resistance during their operation. . . On the basis of their important characteristics wet collectors may be classified according to Table 2. ' FILTERS Filters for industrial air and gas cleaning consist primarily of cloth dust collectors and the ultra or absolute type of filter. Cloth dust collectors are generally constructed in the form of housings with cloth envelopes drawn over wire screen frames or with vertical cloth Table 1. Inertial Separator Characteristics- Efficiency Pabticle Size Range In Microns >100 100-10 <10 Resist ance (Pressure Drop) Description and Remarks Settling and baffle chambers Medium Low Low Low A large chamber to reduce velocity to permit settling. Auxiliary baffles are sometimes used to improve performance Requires large space Large diameter cyclones High Medium to Low Low Low Considered.as single body over 3 ft in diam eter Gases and material must be dry. Air-tight dust bins or continuous removal of mate rial must be provided. Space require ments moderate Refined design centrifugals High High Medium to low Medium Available as multiple small diameter tubes, scroll shaped bodies, and multiple louvers Gases and material must be dry. AH'-tight dust bins or continuous removal of mate rial must be provided. Space require ments moderate Integral rotor type High High - Medium to low See remarks Rotor acts as air mover and separating ele ment Usually limited to dry granular materials and dry gases. Low space requirements No external pressure loss involved but power requirements are higher than usual ex hauster Slotted scroll fan High Medium to low Low See remarks Separation takes place in fan scroll . No external loss involved but power require ments are higher than usual exhauster bags or tubes. Cloth filters depend to a great extent on the accumulated dust layer for their effectiveness. Their basic or initial efficiency depends upon .the type of fabric employed; felted media such as wool gives higher initial removal than woven fabrics. The increase in resistance to air flow, resulting from the accumulated dust layer; is related to rate of flow, con centration, and characteristics of the contaminant. Removal of the col lected material is accomplished through periodic shaking by single mecha nisms or combinations of them employing rapping, or through reversal of air flow, or by means of high velocity reverse air jets. With shaking or rapping, air flow is not constant and filtering velocities are usually held under 6 fpm. With reverse jets or reverse air flow, substantially constant air flow is maintained and filtering velocities are generally higher (up to 35 fpm). Filtering velocities in all fabric collectors are highly dependent upon the aerosol, fume, or dust being collected. The ultra or absolute type of filter8 may consist of pleated cellulose as- Air Cleaning 798 CHAPTER 34 1956 Guide bestos paper, deep, sand beds, composite glass wool layers, compressed glass fiber- in the form of paper or batts and resin wool. ; The use of this type of filter is limited to concentrations in the range of outdoor air where very high' efficiencies, greater than 99.95 percent are required. ' Fabric filters are not suitable for high temperatures, above 300 F, acid mists or vapors, or mixed contaminants such- as wet corrosive gases and solid or liquid particles. Cotton fabrics are limited to 180 F, whereas wool is limited to temperatures under 200 F.: A wide variety of natural and synthetic filter medias is available for various temperature and corro sion conditions but caution must be exercised relative to rupture, high temperatures, and corrosive gases. When properly selected, efficiencies are often high enough to permit recirculation of air except, possibly, when handling toxic contaminants. Table 3. Chabactebistics op Fabbic Filtebs Efficiency Particle Sue Range in Microns Resistance In Water >10 Cloth collector (shaken or rapped)* High Cloth collectors ' High (ireverse air or ! jet cleaning)* Absolute type0 High 10 to 1 High <1 Moderate to high Medium High Moderate to Medium to high high High High Medium Filtering Velocity fpm Maintenance 1-6 10-35 3-14 Medium to high (periodic) Medium to low None (see remarks) 6 SSppaaccee rreeqquuiirreemmeennttss lmaregdei.umR.eqCuilreeasnsincghecdounlsetdancltedaunriningg. operating cycle. A. dded horsepower used far reveerSsepajecet arecqtiuoinre. ment small. Requires replacement of unit when predetermined resistance is attai_nedj . Ordinary cleaning not possible. On the basis of their important characteristics, fabric filters may be classified according to Table 3. ' ELECTROSTATIC PRECIPITATORS Electrostatic precipitators for industrial air and gas cleaning differ ma terially from the low voltage designs described in Part I- of this chapter, although the principles of operation are similar. For industrial concen trations, it is obvious that more severe demands are made upon methods of cleaning the collector, disposal of collected material, and servicing prac tices. Low voltage cleaners for industrial loadings to date dp not have sufficient inherent dust holding capacity. One exception in the field of ex haust systems is that of the oil mist collector, which functions satisfactorily on a liquid aerosol with the conventional low voltage type (2 stage) electro static precipitator. Industrial precipitators employ an assembly of parallel collector elec trodes of various constructions, including corrugated plate, rod curtains, or perforated plate. Air flow is usually horizontal, although special con struction may permit vertical air flow. High voltage collectors were made in the form of vertical pipes, and are used for high operating pressures and for wet collector designs where water continuously flows downward inside Air Cleaning 799 the pipe walls of the collector electrode. The negative discharge elec trodes or rods are accurately centered between the usual 9 in. collector electrode spacing, the latter being of positive charge. Precipitation occurs in a single stage wherein ionization and collection are carried on simul taneously throughout the unit, and depend on high potentials of 25,000 to 75,000 volts. The high voltage direct current is supplied by either mechanical or electronic rectifiers. High efficiencies are obtained by allowing suitable time for contact in the collector zone, and by proper ratio of air flow velocity to that of transverse velocity of the negatively charged particles toward the positive charged collector plates. ' Air velocities vary from 240 fpm to 480 fpm with a constant pressure drop of less than Yi in- water. Since the maximum efficiency is ob tained with the finer particles at low concentrations, and the precipitation is not effective for large particles, inertial separators are frequently used in series with these units. Attention should be directed to the prohibition of air recirculation to occupied spaces. High voltage cleaning equipment produces ozone and nitrogen oxides in excessive quantities. The major source of maintenance usually will be in conjunction with the high voltage rectifying equipment rather than the collector. Although usually used for elevated temper ature work, unless the gases are pre-conditioned, temperatures in excess of 700 F should be avoided. Collector electrode cleaning is accomplished by a rapping device, either electrical or pneumatic, without interrupting operation. The dry plate surfaces release the dust into hoppers below the plates. Some wet cleaning methods are also used. Electronic precipitators require large spaces, maintenance may vary widely, and initial costs are high. Efficiency is a function of the aerosol encountered and usually ranges above 90 per cent. ABSORBERS, ADSORBERS, AND COMBUSTION DEVICES One of the important problems in industrial air and gas cleaning is the removal of soluble, insoluble, or combustible gases and vapors from fluid streams before their discharge to the atmosphere. These contaminants may create problems which are distinct from the particulate removal dis cussed previously. It has been pointed out that scrubbers and other wet collectors may remove gases and particulate matter from contaminated air streams. However, the units described are intended primarily for particulate removal with the exception of the spray or packed towers or wet cell devices. Absorption devices are intended primarily for the removal of readily soluble gases which can be removed by simple absorbing agents such as water or alkali; for example, the removal of hydrochloric acid gas by a caustic spray. Adsorption apparatus is intended primarily for removal of organic vapors in either high concentration (solvent recovery) or low concentration (odor removal). The first process is usually carried on as a matter of economic recovery. In the second process, the concentration of the contaminant must be low enough so that the adsorbent will have a reasonable life before replacement or reactivation. Combustion, either total or catalytic, may he used to destroy organic 800 CHAPTER 34 1956 Guide compounds, either gaseous or particulate, which create odor problems. The use of catalysts to-reduce the temperature-needed for combustion is comparatively recent in this field. -In some, instances the heat of combus tion may be recovered for utilization. -The temperature necessary: for destruction of compounds- varies with the nature of the contaminant; However, partial combustion may alter the compound to render it in nocuous. The temperature required for complete destruction is usually above 1100 F. Catalysts may only require heating to 500 F or may oper ate without heating if .the gas temperature is above 500 F. Absorbers < These may consist of spray chambers, packed towers, or wet cell washers .through which an absorbing agent is recirculated. The gases collected may be converted to insoluble salts or usable acids and other compounds. The performance of these devices depends upon several factors such as the solubility of the gas, its vapor pressure, its rate of reaction with the ab sorbent, the velocity through the collector, area of the absorbing surface either as spray droplets or wetted, media. These are generally designed for the specific purpose intended. They usually are intended to collect over 95 percent of the contaminant. Resistance depends upon the par ticular design and ranges from 1 to 10 in. of water in most installations. Their resistance during their operating interval is constant unless serious plugging of packing occurs. Spray units are seldom affected by plugging. Packed absorption devices require a precleaner to remove particulates if long trouble-free service is desired. Maintenance of spray nozzles is a function of the degree of atomization used and of conditions encountered, such as purity of spray liquids. .. . Protection against corrosion and freezing may be necessary and disposal of waste liquids may create secondary problems. Adsorbers These units consist of a chamber filled with a granular adsorbent. The adsorbent may be activated charcoal, silica gel, alumina and other treated solids. Activated charcoal is the most common and has the highest re tention per unit weight for organic solvents. Performance of adsorbent beds depends upon their thickness, velocity of the gas passing, mesh size (surface area) of adsorbent and temperature of the vapor being removed. They can be designed to obtain almost complete removal of organic vapors and some inorganic gases. They may be reactivated by the use of steam or heat. Resistance depends upon the adsorbent mesh size, depth and velocity. It may range from less than one inch of water to several inches of mercury. Adsorbent beds are usually limited, because of their cost, to applications where recovery may be economically feasible. Removal of particulate matter by use of precleaners is necessary if significant loadings are involved as the adsorbent voids are readily plugged. They are not suitable for high temperature conditions. Silica gel and alumina exhibit a strong preference for water vapor whereas charcoal does not. Combustion Devices This group of industrial air cleaners entails the nse of high temperatures or catalysis combined with some elevation in temperature to destroy or de compose organic and some inorganic gases which create obnoxious odors. Air Cleaning 801 The devices are divided into those in which combustion is dbtained by use of liquid or gaseous fuels and the secondary air for combustion is provided by the contaminated air. In essence, the simplest form involves passing the contaminated air through the combustion chamber of: a boiler or fire box. Special fire boxes or brick. checkerwork may also be employed. Catalytic devices consist of noble metal packed into frames in the form of ribbons or screens or may be ceramic granules coated with noble metal catalysts. The frames or packing are placed in a housing over which the gas stream to be decontaminated is passed. The contaminants break down and are reduced to elemental gases of an innocuous nature. .Catalysts reduce the amount of heat necessary but may become contaminated by sulfur or other elements. The performance of a combustion device is dependent upon the reten tion period of the contaminant in the high temperature zone. Removal or destruction is thus dependent on velocity and surface area of-the heat transfer device. If properly designed, obnoxious odors are removed. . The resistance of the direct combustion unit is negligible since it is an integral part of the fuel combustion system. Catalytic devices behave in a manner comparable to packed beds or filters except that they are not plugged by organic particulates but may be affected by inorganic solids. Maintenance of these types of units is essentially dependent upon the contaminants encountered. The direct combustion system requires, little care other than that required by ordinary fuel burning equipment. ' Cata lytic units become contaminated slowly and will require removal for re activation at certain intervals depending upon the application:;. Economic factors may limit the use of direct combustion methods unless there is a demand for the heat generated. They may best be applied to processes employing combustion. Catalytic units require temperatures of at least 500 F and consequently it may be necessary to preheat the con taminated air to this value. REFERENCES 1 Bronchial Asthma and Allied Allergic Disorders, by S. S. Leopold and C. S. Leopold (Journal of Ike American Medical Association, March 7,1925, VoL 84, p. 731 734). . * Air Cleaning as an Aid in the Treatment of Hay Fever and Bronchial Asthma, by Leo H. Criep, M.D., and M. A. Green, M.D. (Journal of Allergy, St. Louis, Janu ary, 1936, Vol. 7, No. 2, Page 120). 3 The Bacterial Filtration Efficiency of an Electrostatic Air Cleaner, by O. M. Lidwell (Journal of the Institution of Healing and Ventilating Engineers, 75 Eaton Place, London, S.W.I., June 1951, Vol. 19, No. 190, Page 139). ! * Dirt Patterns on Walls, by R. A. Nielsen (A.S.H.V.E. Transactions, Vol. 46, 1941. p. 247). 5 Industrial Dust, by Philip Drinker and Theodore Hatch (McGraw-Hill Co., New York, N.Y.). . . * A.S.H.V.E. Standard Code for Testing and Rating Air Cleaning Devices Used in General Ventilation Work (A.S.H.V.E. Transactions, Vol. 39,1933, p. 225). ,, 7 A Test Method for Air Filters, by Richard S- Dill (A.S.H.V.E. Transactions, Vol. 44, 1938, p. 379). .. 3 Laboratory Design for Handling Radioactive Materials; Research Conference Report, Building Research Advisory Board, National Research Council, Washington, D. C. 1952. . BIBLIOGRAPHY .- and Application of Oil-Coated Air Filters, by H. C. Murphy (A.S.H V E I Ransactions, Vol. 33,1927, p. 73). ^ j .js. 802 CHAPTER 34 1956 Guide . Operation and Maintenance of Air Filters, by W. G. Frank (Heating, Piping and Air Conditioning, May, 1931, p. 378). , ' Size and Characteristics of Air-Borne Impurities, by W. G,!Frank (Heating, Piping and Air Conditioning, January, 1932, p. 35). Fundamental Principles in the Design of Dry Air Filters, by Otto Wechsberg (A.S.H.V.E. Journal Section, Healing, Piping and Air Conditioning, April, 1933, p. 217). The Economic Factors in Converting Recirculated Air for Ventilation, by H. E. Ziel and Henry Sleik (A.S.H.V.E. Journal Section, Heating, Piping and Air Condi tioning, July, 1943, p. 367). A.S.H.V.E. Research Repobt No. 1094--Air Filter Performance as Affected by Kind of Dust, Rate of Dust Feed, and Air Velocity Through Filter, by F. B. Rowley and R. C. Jordan (A.S.H.V.E. Transactions, Vol. 44,1938, p. 415). A.S.H.V.E. Research Report No. 1122--Air Filter Performance as Affected by Low Rate of Dust Feed, Various Types of Carbon, and Dust Particle Size and Den sity, by F. B. Rowley and R. C. Jordan (A.S.H.V.E. Transactions, Vol. 45, 1939, p. 339). A.S.H.V.E. Research Report No. 1145--The Effect of Lint on Air Filter Perform ance, by F. B. Rowley and R. C. Jordan (A.S.H.V.E. Transactions, Vol. 46, 1940, p, 25). . ... .; ' A.S.H.V.E. Research Report No. 1169--Comparison of the Weight, Particle Count and Discoloration Methods of Testing Air Filters, by F. B. Rowley and R. C. Jordan (A.S H.V.E. Transactions, Vol. 47, 1941, p. 29). . A.S.H.V.E. Research Report No. 1187--Economical Air Velocities for Meehanical Air Filtration, by F. B. Rowley and R. C. Jordan (A.S.H.V.E. Transactions, Vol. 47, 1941, p. 391). A.S.H.V.E. Research Report No. 1218--Overloading of Viscous Air Filters Dur ing Accelerated Tests, by F. B. Rowley and R. C. Jordan (A.S.H.V.E. Transactions, Vol. 48, 1942, p. 437). A New Electrostatic Precipitator, by G. W. Penney (Electrical Engineering, Jan uary, 1937, p. 159). Electrostatic Precipitation for Aircraft, by Howard E. Corbitt and Norman J. Clark (Aero Digest, December, 1940, p. 132). Pointers on Selecting Equipment for Industrial Gas Cleaning, by C. E. Miller (Chemical and Metallurgical Engineering, 46, March, 1938, p. 132-5). Electrical Precipitation, by W. A. Schmidt and E. Anderson (Electrical Engineer ing, 57, August, 1938, p. 332-338). Electrical Precipitation, by A. W. Simon and L. C. Kron {Electrical Engineering, 51, February^ 1932, p. 93-5). Some Factors and Principles Involved in the Separation and Collection of Dust* Mist and Fume from Gases, by Evald Anderson {Transactions, American Institute of Chemical Engineers, 16, 1924, Pt. 1, p. 69-86). Electrical Precipitation of Solids from Smelter Gases, by Ross B. Rathbun {Trans actions, American Institute of Electrical Engineers, 41, 1922, p. 815). Characteristics of Unit Dust Collectors, by Arthur C. Stern, Jack BalifL Arthur E.Perina, Robert Crowley, Benjamin Feiner and Arthur A. Urbano (A.S.H.V.E. Transactions, Vol. 52, 1946, p. 237). Operation, Application and Effectiveness of Dust Collection Equipment, by John M. Kane {Heating and Ventilating, Reference Section, August 1952). Air Pollution Abatement Manual--Chapter 9, by C. A. Lapple {Manufacturing Chemists Association). Handbook on Air Cleaning, by Sheldon K. Friedlander, Leslie Silverman, ITilip Drinker and Melvin W. First. (U. S. Atomic Energy Commission, Washington, D. w- Performance of Wet Cell Washers for Various Aerosols, by M. W. First, R. chella, L. Silverman, and E. Berly {Industrial and Engineering Chemistry Vol. 4o> 1951, p. 1363). Chemical Engineers Handbook, by John H. Perry. (McGraw-Hill Book Co., 3rd Edition 1950). American Industrial Hygiene. Association Quarterly, March 1950. Design Factors in Catalytic Fume Elimination, by R. J. Ruff (Healing and Venti lating, September 1953, p. 84). CHAPTER 35 SPRAY APPARATUS Air Washers, Humidification with Air Washers, Dehumidification and Cooling with Air Washers, Well and Water Main 'Temperatures, Apparatus for Direct Humidification, Unit Humidifiers, Water-Cooling Towers, Water Use and Conservation, Rivers and Lakes, Spray Cooling Ponds, Atmos pheric and Mechanical Draft Cooling Towers, Mechanics of At- mospherie Water-Cooling, Design Conditions, Water-Cooling Tower Design, Selection of Water-Cooling Towers, Operation and Maintenance ' IR humidification is effected by the vaporization of water, and always A requires heat from some source.. This heat may be added to the water prior to the time vaporization occurs, or it may be secured by a transformation of sensible heat of the air being humidified to latent heat as the vapor-is-added to the air. The thermodynamics of the process are discussed in Chapter 3. The removal of moisture from air may, or may not, involve the removal of heat from the air-vapor mixture. With spray equipment, dehumidification of air always necessitates the removal of heat. AIR WASHERS An air washer consists essentially of a chamber or casing in which is provided a spray nozzle system, a tank at the bottom of the chamber for collecting the spray water as it falls, and an eliminator section at the leaving end of the chamber for removal of drops of entrained moisture from the delivered air. Air is drawn through the casing of the washer, where it comes into intimate contact with the spray water. A heat trans fer takes place between the air and water, resulting in either humidifica tion or dehumidification of the air, depending upon the method of operation and the relative temperatures of air and spray water. To prevent backlash of spray ahead of the washer chamber, and to aid m more uniform air distribution, inlet diffusion plates or eliminator baffles, where necessary, are provided in the air entrance end of the air washer. Inlet diffusion plates are used when the air flow and water spray are in the same direction; eliminator baffles of special design are used where one or more of the water sprays opposes the air flow. At the out let end of the washer suitable flooded eliminator plates are used. These plates, for the removal of entrained moisture, usually cause four to six changes in direction of the air flow. Kgs. 1 and 2 show the essential construction features of conventional mr washers. Intimate contact between the air and the water is secured U) by breaking the water into fine drops; (2) by passing the air over sur faces continuously wetted by water; or (3) by a combination of the two. The wetted surfaces in an air washer may be of fiber glass, metal or scTMbber plate construction: Scrubber plate types of washers are generally used to wash reclaimable products from the air, and are composed of several baffle type plates located across the air stream. Water is supplied at the top of the washer to spray over these plates. In the case of the her glass or metal surfaces, the water spray is usually rather coarse and at 803 804 CHAPTER 35 1956 Guide low pressure. In many cases these sprays are set at -an angle with the air flow. Air washers of this type not only perform necessary heat transfer functions, but also are effective removers of dust and dirt from the air strEeasmse.ntial requirements in the air washer operation are.: uniform distri bution of the air across the chamber section; moderate air velocity of from 250 io-600 fpm in the washer chamber; an adequate amount of spray water , broken-up into fine droplets throughout the air stream, at pres sures of from 15 to 30 psig; sufficient length of travel through the water spray and wetted surfaces; and the elimination of entrained moisture from the outlet air. Expected performances, physical size, length, number of sprays, etc., vary greatly, depending upon the functions of the installation. In general, the width and height of an air washer are dictated by the space available. Washers of nearly equal height and width are desirable from an air flow and economic standpoint, although not necessary. The length of washers varies considerably. A space of approximately 2| ft between spray banks is used, and the first and last banks of sprays are located about 1 ft to ft from the entering or leaving end of the washer. In addition, air washers are very often furnished with cooling coils or heating coils within the washer chamber, and the use of these coils affects the overall length of the washer. Where increase of overall heat transfer between the air and water is required, multistage washers are used. These washers are equivalent to a number of washers in series, and the water is often pumped from one stage to the other where conditions permit. ' ' The resistance to air flow through an air washer varies with the tyf? pf eliminator and wetted surfaces, number of banks of spray and their Spray Apparatus 805: direction, air velocity, size and type of other resistances such as cooling and heating coils, and other factors such as air density. Resistances vary from as low as j in. to higher than 1 in. water column, and it is therefore necessary that the manufacturer be consulted in regard to the resistance of any particular washer design involved. HUMIDIFICATION WITH AIR WASHERS Air humidification can be accomplished in three ways with an air washer. These are: (1) use of recirculated spray water without prior treatment of the air; (2) preheating the air and washing it with recirculated spray water; and (3) using heated spray water. In any air washing installation the air should not enter the washer with a dry-bulb temperature less than 35 F in order to eliminate danger of freezing the spray water. . Method, 1. Except for the small amount of energy added from outside by the recirculating pump in the form of shaft work, and for the small amount of heat leak from outside into the apparatus, including the pump and its connecting piping, the process would be strictly adiabatic. Evapo ration from the liquid spray would therefore be expected to bring the air immediately in contact with it to saturation adiabatically; and, since the liquid is..recirculated, its temperature would be expected to adjust to the thermodynamic wet-bulb temperature of the entering air. It does not follow from the foregoing reasoning that the whole air stream is brought to complete saturation, but merely that its state point should move along a line of constant thermodynamic wet-bulb temperature as explained in Chapter 3. The extent to which the final temperature ap proaches the thermodynamic wet-bulb temperature of the entering air, or the extent to which complete saturation is approached, is conveniently expressed by a ratio known as humidifying effectiveness or saturating effec tiveness, and is defined as where eh = humidifying effectiveness, percent. <i = dry-bulb temperature of the entering air, Fahrenheit degrees. = dry-bulb temperature of the leaving air, Fahrenheit degrees. V = thermodynamic wet-bulb temperature of the entering air, Fahrenheit de grees. The following may be taken as representative humidifying or saturating effectiveness of an air washer for the conditions stated: 1 bank--downstream............................ .................................... 2 banks--1 upstream and 1 downstream.............................. 99-95 percent 2 banks-upstream.................................................................. 90"95 Percent The humidifying or saturating effectiveness of a washer is dependent upon the essential items of design mentioned under Air Washers. Other conditions being the same, low velocity of air flow is more conducive to higher humidification effectiveness. Method 2. The preheating of the air increases both the dry- and wetbulb temperatures, lowers the relative humidity, but does not alter the humidity ratio (pound water vapor per pound dry air). At a higher wet- 806 CHAPTER 35 1956 Guide Table 1. Avebage Maximum Wateb Main Temperatures* Ark. An*. Calif. ...... %uoemx... Tucson...."' Anaheim ........... Berkeley ............. Fresno.. ........... ullerton ............ Glen<Uie ......... (SLuST,&! Ontario ........... Faaadena... " Fomona.............. Riverside........... Sacramento'....... $2 **' Colo. Conn. D. C. Del. Fla. Ga. Idaho 111. Ind. Ky. La. Me. Md. Denver ' New Ilavea'"'' w!f,rbury...... Wilmington JA^onviUe ..." Tanona .- Atlanta............ Macon......... ` Boise ....... " Chicago ' .. Licero. Evanston" Moline. Peoria.. JStopcrikn'fgoSrdeld' ^vansvihe. Pf7 Indianapolis Sfftpssi-* >oui City.. Upocordia. ^""sasCity.' Ivzt... . >uisvilie"' BSa?to"nORrioeuagSe Shreveport. Augusta.... Baltimore... Mich. Boston ....... Cambridge.. Fall River.. Lowell........ Lynn.. New Bedford.. Salem.. Worcester. I Detroit__ Flint......... Grand Rapids.. Highland Park.. Jackson............. . _ ,, Kalamazoo...........^ .1 53 II S. D. Tulsa.. Eugene... Portland. Altoona... Erie.. Johnstown.............. McKeesport............ Philadelphia.......... Pittsburgh............ Providence............ Charleston......... Greenville............. Spartanburg........ Rapid City.......... Lansing...................| 64 |) Tenn/ Chattanooga........ Nev. N. H. N. J. N. Y. Saginaw............ Duluth........... Minneapolis-- St. Paul............ Jefferson City.. Kansas City - Springfield....... St. Joseph....... St. Louis......... Springfield -- Lincoln............ Omaha............ | Reno.. Manchester............ . ,, 1 Jersey City..............I 53 || Utah Newark......... Paterson........... Trenton............ j Albany.......... :. Buffalo.............. Jamaica___*-- Mt. Vernon----New Rochelle.. New York-..............., _ . .. Rochester- ............. I ?<? ||'W. Va. Knoxville.............. Memphis................ Nashville.............. Amarillo................ Austin................... Beaumont............. Dallas..................... El Paso................ Fort Worth......... Galveston............ Houston.............. Port Arthur___ `. San Antonio___ Wichita Falls.:.. Logan................... Salt Lake City.. Fredericksburg.. Lynchburg......... Norfolk --------- Richmond........ Olympia............ Seattle................. Spokane............. Tacoma.............. Charleston........ Schenectady -- Syracuse............ Utica................... Yonkers.............. Asheville............ Charlotte........... Huntington -- Wheeling............ LaCrosse............ Madison............. Milwaukee........ Racine...'.......... Raleigh.............. Winston-Salem.... Albuquerque.......... 65 II Akron.. 1 11 Okla. Canton.. . Cincinnati. Cleveland.. I Columbus... Dayton Lakewood.. Springfield. Toledo.. Oklahoma City. Alta. B. C. Ont. P.E.I. Que. Calgary.......... Vancouver....... London............. Toronto............ Charlottetown.. Montreal.......... Quebec.............. * These averages taken from various city water main locations, with some actual values slightly higher and some lower than values shown. Some values were supplied by H. E. Degler, Marley Company. Some were obtained from City Water Department records. The highest values given by the various authorities are usually those listed.. . bulb temperature, but the same humidity ratio, more water can be ab sorbed per pound of dry air in passing through the washer, assuming that the humidifying effectiveness of the washer is not adversely affected by operation at the higher wet-bulb temperature. The analysis of the process occurring in the washer itself is the same as that explained under Method 1. The final desired conditions are secured by adjusting the amount of preheating to give the required wet-bulb temperature at en traMnceethtood t3h.eEwvaesnheifr.heat is added to the spray water, the mixing occur ring in the washer itself may still be regarded as adiabatic. The state Spray Apparatus 807 point of the mixture should move in a direction determined by the specific . enthalpy of the heated spray as explained in Chapter 3. It is possible, by elevating the water temperature, to raise the air temperature, both dry-bulb and wet-bulb, above the dry-bulb temperature of the entering air. In each of the methods, 1, 2 or 3, the air leaving the air washer may require reheating to produce in the conditioned space the required drybulb temperature and relative humidity. DEHUMIDIFICATION AND COOLING WITH AIR WASHERS Cooling of the wet-bulb temperature of an air vapor mixture can be accomplished by an air washer if the temperature of the spray water is lower than the wet-bulb temperature of the air. Moisture removal is obtained when the spray water temperature is lower than the dew-point of the entering air. In these cases the final dry-bulb temperature and relative humidity of the leaving air are dependent upon the design factors . of the air washer. Both sensible and latent heat are removed in the process of dehumidi fication by cold spray water. Abstraction of sensible heat occurs during . the entire time that the air is in contact with the spray medium. Latent heat removal takes place as condensation occurs. Therefore, the lower the spray temperature, the greater the amount of moisture removal per pound of dry air, all other conditions remaining the same. Washers with two or more banks of spray are usually selected for dehumidifying installations, whether for comfort or industrial installations. Generally such air washers cool the air to within one or two degrees (Fahren heit) of the leaving spray water temperature; this differential will increase , somewhat when the difference between the entering wet-bulb and leaving ; dew-point is relatively large. Where a limited supply of cold water is available, multiple stage washers may be used to great advantage. In such washers the cool water is pumped through the multiple spray systems in series and counterflow to the air flow. Such an arrangement brings the delivery air in contact with the coldest water, securing a maximum amount of cooling and saving water. When using cold well water or water from city water mains, care should be used to secure accurate data on the water temperatures. Table 1 lists . some approximate water main averages which may be used as a guide, but they should be verified from local records. This is particularly true with city water main temperatures. In the case of well water temperatures, Fig. 3 shows the approximate temperatures of water to be expected from wells at depths of 30 to 60 ft. Air washers for dehumidifying and cooling usually have separate recircu lating pumps. These pumps deliver a mixture of cold and recirculated water under the control of a three-way valve. The valve may be actuated either by a thermostat in the washer outlet, or by a humidity or other con- : troller in the space being conditioned. Air washers for dehumidifying are very often furnished with direct expansion or water cooling coils within the washer space, in which case water for the washer sprays is entirely recirculated. APPARATUS FOR DIRECT HUMIDIFICATION Humidifiers may be divided into two general types which are, according the method of operation: (1) indirect, such as the air washer, which 808 CHAPTER 35 1956 Guide F ig . 3. A p p r o x im a t e W e e e W a t e r T e m p e r a t c r e s a t D e p t h s o p 30 t o 60 F t > introduces moistened air; and {2) direct which sprays moisture into the room or introduces moisture by means of steam J As in the cases of humidification by sary for the vaporization of the moisture added to the aijbytSi ct Son is secured either from heat stored in the spray water or by a tra - Spray Apparatus 809 formation of sensible to latent heat in the air humidified. In the latter case, the enthalpy of the air remains constant, but the dry-bulb tem perature of the air is reduced. " Direct humidification is usually preferable where high relative humidi ties must be maintained, but where there is little cooling or ventilation required. In comfort- air conditioning, where both humidification and ventilation are required, the indirect humidifier is preferable. In indus trial applications, where the cooling or ventilation load is large and where very high relative humidities must be maintained, a combined system employing both direct and indirect humidifiers is sometimes used. Spray Generation Spray generation is obtained by (1) atomization, (2) impact, (3) hy draulic separation, and (4) mechanical separation. Atomization involves the use of a compressed air jet to reduce the water particles to a fine spray. With the impact method, a jet of water under pressure impinges directly on the end of a small round wire. Where hydraulic separation is employed, a jet of water enters a cylindrical chamber and escapes through an axial port with a rapid rotation which causes it immediately to separate in a fine cone-shaped spray. In the mechanical separation process, water is thrown by centrifugal force from the surface of a rapidly revolving disc and separates into particles sufficiently small to be utilized in certain types of mechanical humidifiers. Spray Distribution Spray distribution is obtained by (1) air jet, (2) induction, and (3) fan propulsion. . The air jet which generates the spray in atomizers also carries the spray through a space sufficient for its distribution and evaporation, and this method of distribution is termed air jet. Where distribution is obtained by induction, the aspirating effect of an impact or centrifugal spray jet is utilized to induce a current of air to flow through a duct or casing, and this air current distributes the spray. Fan propulsion obviously consists of the utilization of fans to entrain and distribute the spray. . Industrial type direct humidifiers are commonly classified as (I) atomiz es, (2) high-duty, (3) spray and (4) self-contained or centrifugal. Atomizing Humidifiers. Several types of atomizing humidifiers employ nozzles placed within the room and rely upon compressed air to effect com plete atomization of the water which is converted to vapor by the heat of the room air. Some of these nozzles depend upon an aspirating effect to draw the water into the nozzle and atomize it; others operate on a com bined air and water pressure. It is usual for nozzles of the water pressure type to be controlled by a diaphragm valve actuated by the pressure of the atomizing air. . High-Duty Humidifiers. Water is supplied under high pressure (usually nbout 150 psi) through pipe lines from a centrally-located pumping unit, the spray-generating nozzle, which is of the impact type, is located in a .cylindrical casing. A drainage pan provides for the collection and return of unevaporated water which flows through a return pipe to a filter tank, from which it is recirculated. A powerful air current is forced through the humidifier by means of a fan mounted above the unit. The air enters from above, is drawn through the head, charged with moisture, and cooled. It then escapes from the opening below at a high 810 CHAPTER 35 1956 Guide velocity in a complete and nearly horizontal circle. The spray is evapo rated and the resulting vapor diffused. This distribution of fine spray over the maximum possible area promotes complete and rapid vaporization. Spray Humidifiers. This type consists of an impact spray nozzle in a cylindrical casing with a drainage pan below it. The aspirating effect of the nozzle induces a moderate air current through the casing which dis tributes the entrained spray. The general method of circulating and returning the water is similar to that employed for high-duty humidifiers. A suitable pump and centrally-located filter tank are required. Self-Contained Humidifiers. The self-contained or centrifugal humidi fier has the ability to generate and distribute spray without the use of air compressors, pumps, or other auxiliaries. These may be used either singly or in groups. In large installations, where suitable connections are pro vided to permit the cleaning and servicing of individual units without af fecting the room as a whole, group control of the water and power may be employed. ' UNIT HUMIDIFIERS The term unit humidifier denotes an assembly of elements the principal function of which is to humidify. The essential element of a unit humidi fier is an atomizer or evaporator. To this may be added a fan, a heater, outlet vanes or diffusers, and a housing to enclose the various parts. Unit humidifiers fall into four general classifications, depending on the method of causing evaporation. These are as follows: (1) Nozzle Type, (2) Rotary Type, (3) Cascade Type, and (4) Heater Type. In the nozzle type of humidifier water is sprayed into the air and evapo ration is effected by adiabatic exchange of energy. Units of this type in simplest form, spray a fine mist of water directly into the air in a space. They are used to a great extent in the textile industry. In the rotary type of humidifier the spray is created by rotating vanes or discs which throw the water by centrifugal force, and in so doing break it up into a fine mist. In all other respects, this type of humidifier is similar to the nozzle type. It has the advantage over the nozzle type of being less liable to become clogged. In the cascade type the humidification takes place by water falling in sheets over a series of baffles or trays. This type is usually furnished with a fan, air heater, and air filter all enclosed in a housing. In the heater type of humidifier the water is heated either to the boiling point or to a temperature at which the water vapor readily passes into the air stream. There are many variations of this type of humidifier. In the simplest form the heating element using steam, hot water, gas, oil, or elec tricity is placed in a pan or vessel of water, and the vapor passes from the surface of the water to the stream of air. A modification of this type of humidifier is the combination of spray nozzle and heater type in which the water is sprayed over a hot surface and evaporated. It has the disadvantage of accumulating scale on the surfaces of the vessel or heating surface. WATER-COOLING TOWERS The removal and dissipation of heat from a compressed refrigerant or from exhaust steam are important factors in the efficient operation of & refrigerating plant or an electric steam-generating station. This heat removal is generally accomplished by first transferring the heat of the S05 Spray Apparatus 811 to cooling water in a heat exchanger. The water, if cheap or plentiful, may be wasted to the nearest sewer or open waterway, such as a river or lake. Where water usage is restricted or expensive, or where the available water contains dissolved salts which would form scale on the heat-exchange apparatus, it is necessary to recirculate the water, and to cool it, after each passage through the heat-exchanger, by contact with moving air in some type of water-cooling apparatus. Water Use and Conservation Many communities have found that present water systems are not sufficiently large to satisfy the increasing demands of domestic and indus trial users. The reasons for such shortages are primarily: (a) inadequate purification and water-distribution systems; (b) inadequate sanitary and storm-sewer disposal.systems; or (c) inadequate sources-of water. Even when an adequate supply of water is available from the water mains or private wells, many cities do not have sufficient sanitary or storm sewer facilities to handle increasing demands. The sanitary systems are usually limited because of the capacity of the filtration plants, and therefore many cities restrict the use of the sanitary system to sewage. Rivers and Lakes ...... Until the year 1920, large generating stations were usually located on the banks of rivers, lakes, or artificial ponds. The-removal and dissipation of the heat from the Diesel cylinder or the exhaust steam of a turbine was accomplished by taking in the circulating water at a considerable distance from the discharge, thus preventing mixing of the heated discharge with the inlet water. The use of water from streams for this purpose.has the following disadvantages: the site may be far removed from the fuel source or from power consumers; water supply may limit plant expansion; munici pal restrictions on use of water may hamper operation; costly intake struc tures with screens and sediment basins may be required; drastic flood or drouth conditions, the vagaries of most rivers, upstream pollution, scale forming constituents, debris, sand, algae, and formation of troublesome ice may cause operating difficulties. When lakes and cooling ponds have been used as a source of circulating water, the hot water is discharged close to the surface, at the shore line. Natural air movement over the surface of the. water causes evaporation over that area, thus carrying the heat away at a rate of about 4 Btu per (hr) (sq ft) (F deg temp difference between air and water). Increased density of the water due to loss of heat, causes the cooled water to sink to the bottom of the pond. The suction connection is therefore located as far below the surface as possible, and at as great a distance from the dis charge as practicable. The area required by such cooling ponds is about 50 times that of a spray pond, or about 1000 times that of a water-cooling tower to dissipate the same quantity of heat and achieve equal operating costs. If the surfaces of such ponds were below the level of surrounding terrain, and the shore were wind-sheltered by trees or other vegetation, so that natural air movement across the surface of the water would be re tarded, the use. of a spray pond or water-cooling tower would be indicated. SPRAY COOLING PONDS The spray pond consists of a water collecting basin, above which spray nozzles are located in an arrangement such as shown in Fig. 4 to spray 812 CHAPTER 35 1056 Guide the water upwards into the air. Properly designed spray nozzles break the water into small drops, but not into a mist. Since the objective is to cool the pond water, the individual drops must be heavy enough to fall back into the pond and must not float away in the air. The water surface exposed to the air passing over the pond becomes the integrated area of all the small drops. The spray pond requires about one-fiftieth of the space required by the cooling pond to dissipate the same quantity of heat with equal results, due to four factors: (1) the speed with which the drops are propelled into the air and fall back into the water basin; (2) the increased wind velocity at a point above the surrounding obstruction; (3) the in creased volume,of air delivery due to the greater vertical cross-section of air permissible; and (4) the vastly increased area of contact between water and air.2 , Spray pond effectiveness is increased by: (1) elevating the nozzles to a higher point above the surface of the water in the basin; (2) increasing the spacing between nozzles of any one capacity; (3) using smaller capacity nozzles to decrease the concentration of water per unit area; and (4) using smaller nozzles and increasing the pressure to maintain the same concen tration of water per unit area. It is usual practice to locate the nozzles from 5 to 12 feet above the surface of the water (dependent also upon depth of water and curb level) with water supply at 5 to 7 psig pressure at the nozzles. Nozzles spray from 25 to 60 gpm each, and the nozzles are spaced so that the average water delivered to the surface varies from 0.1 gpm (small ponds) to 0-4 gpm (large ponds) per square foot. See Table 2 for additional spray pond design data. Best results are obtained by placing the nozzles in a long, relatively narrow area, located broadside to the wind. Louver fences, to prevent the carrying of entrained water beyond the edge of a spray pond by the air on the leeward side, are required for all roof locations and for ground locations where space is restricted; the outer nozzles should be located at least 20 ft from the edge of the basin. Such fences up to 12 ft in height usually are constructed of horizontal overlapping louvers supported between vertical posts. The air, in passing between these louvers, tends to be freed of the larger drops of water. The louvers Spray Apparatus 813 also restrict the flow of air, particularly at the higher wind velocities, thus reducing the possibility of water being carried from the spray cloud. The height of an effective fence should be equal to the height of the spray cloud. Algae formations may be a nuisance in a spray pond. Such growths are minimized by the periodic addition of bromine, chlorine, chlorinated lime, copper sulfate, or various blends of chlorophenates (see Chapter 43). The performance of a spray pond is limited because of space requirements and the probable high cost of piping and pumping. Water-cooling towers, however, allow the designer a wider range of performance within a given space because of the possibility of altering the smaller physical dimensions or varying the water concentration, measured in gallons per (minute) (square foot of tower area). In most cooling towers the water is broken up into drops many times, whereas with the spray pond it is broken up only once and, consequently, in the latter the rate of cooling diminishes rapidly as the temperature of the surface of the drop approaches the wet-bulb temperature of the ambient air. Table 2. Spray Pond Design Data Conventional Up-Spray System Water capacity per nozzle............................... Nozzles per 12 ft length of pipe.................... Height of nozzles above water level............ Nozzle pressure......................... .............................. Size of nozzles and nozzle arms....................... Distance between spray lateral piping-- : Distance nozzles from pond side unfenced. Distance nozzles from pond side fenced-- Height of louver fence...................................... Depth pond basin............................................... Friction loss allowed per 100 ft pipe............ Design wind velocity...................... .................. Unitb gpm ft psig in. ft ft ft ft ft ft mph Standard Minimum Maximum 35 to 50 6 6 6 2 25 25 to 35 15 to 20 12 4 to 5 1 to 3 5 25 4 5 5 li 13 20 15 12 2 3 60 6 12 7 2 38 50 25 12 -- -- __________ _ Spray-filled almospheric cooling towers are used for open-area installations because of their dependence upon the velocity and direction of the wind. Operation is not so Emited as with spray ponds, but the design is generally based on a 3 mph wind, and the performance falls off rapidly as the ambient air velocity decreases. These towers require less basin area, less piping, and no more mechanical equipment than spray ponds, but these savings may be largely offset by the extra cost of the structure. The drift nuisance is similar to that of spray ponds. The word tower used in this connection is a misnomer, as the design simulates a narrow spray pond with length twice the width, or more, having elevated nozzles and a high louver fence. As usually built, the nozzles spray downward from the top of the structure, and the distance from the center of the nozzle system to the louvers on either side is not more than half the distance that the nozzles are elevated above the water-collecting basin. Heights range from 6 to 15 ft, with the total width of the structure usually not greater than the height. Loadings range from 0.6 to 1.5 gpm per sq ft of tower area, and hence require about one-fourth the area of an equivalent spray pond. As the louvers are wetted continuously, they add to the surface of water exposed to the cooling air. The spray-filled atmospheric tower is shown in Fig. 5. 814 CHAPTER 35 1956 Guide S: Much of the atmospheric water cooling for refrigeration work during' >; the past 30 years has been done with natural-draft deck type .towers, also referred to as atmospheric deck towers, see Fig. 6, These towers consist - , of a sturdy wooden or steel frame 20 to 50 ft high and 8 to 16 ft wide, carrying open horizontal wooden latticework or decks at regular intervals from top to bottom. The hot water is distributed over the upper part of the structure by means of troughs, splash heads, or nozzles, and drops from deck to deck enroute to the basin. The purpose of the decks is primarily to arrest the fall of the water, to break and re-break it into drops so as to present the most efficient cooling surface to the air which is passing through the tower transversely to the decks. The wooden decks also add to the area of water surface exposed to the air, but since they offer resistance to the flow of air, the number and arrangement of the decks depend upon baTsioc tpersetvseanntdloosps eorfawtinagteerxopnertiehnecele.eward side of the tower, wide louvers (drift eliminators) are attached at regular intervals from top to bottom; these louvers extend outward and upward at an angle of 45 to 50 deg. In most designs the top edge of each louver extends above the bottom edge of the one above. These louvers serve the same function as a louver fence around a spray pond, namely, to stop the water drops carried by the air beyond the open area of the tower, and to control the quantity of air peTrmheitteefdfictioenpcayssotfharoduegchk ttohweetor wiseirm. proved primarily by increasing length or height, or both, within limits; the length and height increase the area of tower exposed to the wind. The improvement is not directly propor tional to the change made in either case. Neither does a certain percentage Spray Apparatus 815 change of one dimension make an equal improvement in efficiency on two equal towers of different original lengths or heights. Since the range of efficiency varies through wide limits, it is impracticable to attempt to list data here on the area required per unit quantity of water. Improved efficiency, due to added height, is obtained at the expense of additional pumping head and increased weight per unit of area, whereas improvement gained by greater length or width will increase the area and, consequently, the foundation required. Drift loss in a properly designed deck tower is considerably less than in the spray pond, but the drift nuisance may be considerable, and for this reason atmospheric deck towers are unsuitable for downtown building roofs, locations adjacent to buildings, or near expensive mechanical equip ment in industrial plants. They must be located in an open area, broad side to the prevailing wind. They are inefficient with less than 3 mph wind velocity and with wind directions other than broadside. These towers are long and high in proportion to width, and must be securely anchored to prevent uplift or overturning during high winds. High pump ing requirements (30 to 60 ft) and total dependence upon atmospheric caprice, especially wind (quantity and direction), are disadvantages. Due to new uses and growth of demand in recent years, requirements for water-cooling equipment have become increasingly varied and exacting, necessitating refinements and specialized adaptations. The principal de mand for large water-cooling systems in recent years has come from the petroleum industry and steam power plants. Refrigeration, air condi tioning, and engine-jacket cooling service today employ a large percentage of the medium sized and small water-cooling towers installed. MECHANICAL DRAFT TOWERS The mechanical draft tower consists usually of a vertical shell constructed of wood, metal, transite, or masonry. Water is distributed near the top, uniformly over the area, and falls to the collecting basin in the bottom, passing through air which is being circulated in the tower from bottom to top by forced or induced draft fans, or which is circulated horizontally in crossflow towers by induced draft fans. In vertical towers the air passes counterflow to the water and is in con tact with the hottest water just before leaving the tower; hence, a given quantity of air picks up more heat than the average equal quantity of air on natural draft equipment. This permits the water to be cooled with the least quantity of air required by any type of cooling equipment. As movement of air through the towers is obtained by power-consuming fans, it is essential that this air quantity and the draft loss be reduced to a mini mum so as to secure low operating cost. The inside of a mechanical draft tower may be spray filled, i.e., the water surface is presented to the air by filling the entire inside -of the structure with water droplets from the spray nozzles, or it may be packed with wood filling, over which the water cascades from top to bottom. In many cases, a combination of the spray-filled and wood-filled design is used. The forced draft type of tower (Fig. 7), has the advantages of being suit able for corrosive waters, and having the fan mounted near the ground level on a rigid foundation where it is easily accessible. The heated air leaves the top of a forced draft tower at a low velocity and may be subject to recirculation to the fan inlet, with consequent reduc- 816 CHAPTER 35 1956 Guide tic in performance. This reduction could be as much as 20 percent under certain conditions. During cold weather, recirculation may cause ice formation on adjacent equipment and buildings, as well as in the tower fan ring, with possible resultant fan breakage. Fan sizes are limited to 12 ft or less, and therefore more fans, motors, starters, and wiring are needed than for induced draft towers. Induced draft towers, since fans and motors are not visible, are therefore somewhat more adaptable to arcInhittehcetusrparlatrye-failtlmedenmt.echanical draft tower, the area presented to the air is the combined surface area of the small drops present in the tower at any one time. The net free cross-sectional area of the air spaces in. a spray-filled tower is greater than that of the wood-filled tower for the same plan. area. Before discharging to the atmosphere, the water-laden exhaust air passes through a drift eliminator to remove entrained moisture. This Spray Apparatus 817 this air is in contact with the water. The surface area of water in contact' with the air is increased in both cases. Increasing the air quantity. de-! creases the time the air is in contact with the water, but since a greater quantity of air is passing' through, the average differential between the water temperature and wet-bulb temperature of the air is increased, and this speeds up the heat transfer rate. Increased air quantities are obtained only at the expense of increased fan power, which, for fans of the disc type, increases approximately as the cube of the air handled. ' The performance of mechanical draft towers is independent' of wind velocity; hence, it is possible to design them for more exacting performance. Fig. 7. Forced Draft Cooling Tower type of tower is particularly applicable for installations in restricted areas where city ordinances require, fire-proof construction. In the wood-filled tower, lumber of various cross sections is laid hori zontally across the space on as close centers, horizontally and vertically, as required, without introducing too great a resistance to air flow. The water is distributed over the top layer by means of spray nozzles, troughs, splash heads, or through evenly spaced nozzles located in the floor of an overhead open-type water distribution basin, and drops from piece to piece of the wood filling as it progresses downward. As the air moves upward or across the wood filling, the latter presents a large wetted surface, repeatedly breaks up the falling drops of water, and continuously provides new drop surfaces whose integrated areas are several times that of the wood-fill area. ' The efficiency of a mechanical draft tower is improved by increasing the amount of filling, height, area, or air quantity. Increasing the height increases the length of time the air is in contact with the water, without affecting seriously the fan power required, but increases the pumping power. Increasing the area while maintaining constant fan power increases the air quantity somewhat and, because of lowered velocity, increases the time Si--\\m~y/~\\ AM IMTAflC LOUVERS ir~Vv-~n 7/ i COW CRETE tASlN Fig. 8. Counterflow Induced Draft Cooling Tower They require less space and less piping than atmospheric deck towers, and the pumping head varies from 11 to 26 feet, depending upon the design. Overall plant economy, due to colder water temperature, usually more than offsets the additional operating expense and initial cost as compared with those of atmospheric towers. . The counterflow (conventional) type of induced draft tower hss the fan located at the top, Fig. 8, to provide vertical air movement across the filling. Air is discharged upward at a high velocity to prevent recircula tion. Another type, for small requirements, has the induced draft fan' in one end (see Fig. 9) to provide horizontal flow. Another induced draft tower, developed for the purpose of obtaining compactness, larger capacity, increased flexibility and improved per formance, is the crossflow type. This type of tower employs multiple fans centered along the top, each fan drawing air through two cells paired to the suction chamber which is partitioned midway beneath the fans and fitted with drift eliminators that turn the air upward toward the fan outlet. This tower obtains a horizontal air movement as water falls in a cascade 818 CHAPTER 35 1956 Guide of small drops over the filling and across the air stream with less resistance to air flow. The air travel is longer than with the conventional design. Air velocities through mechanical draft towers vary from 250 to 400 fpm over the gross area of the. structure. The air requirements are approxi mately 300 to 400 cfm of air per ton of mechanical refrigeration, and about 100 to 150 cfm of air per gallon of water passing through the tower. Cool ing tower calculations are based upon the fact that mechanical refrigera tion requires approximately 30 gallon-deg of cooling water per minute per ton of refrigeration. In atmospheric cooling towers, if 5 gpm were circulated, the water-cooling range would be 6 deg; with mechanical draft towers, 3 or 4 gpm are usually circulated for a desired water-cooling range of 10 or 7^ F. Some designs of mechanical draft towers are limited to 6 or 7 gpm per sq ft because of blanketing effect, while the capacity of the most efficient types ranges up to 9 or 10 gpm. When an inside cooling tower is required, some adaptation of a spray filled or wood filled induced draft tower is often used, and occasionally an Fig. 9. Small Horizontal Induced Draft Cooling Tower for 3 to 50-ton Refrigerating Units air washer is converted to this service. In this type of application pre cautions must be taken to prevent the discharged air from short circuiting to the intake. . MECHANICS OF ATMOSPHERIC WATER-COOLING The heat exchange in atmospheric water-cooling equipment is accom plished partially by a transfer of sensible heat which raises the wet-bulb temperature of the moving air; but most of the cooling is due to an exchange of latent heat resulting from the evaporation of a small part of the water. If all of the water were cooled by evaporation, the rate of evaporation would.be approximately one percent for each 10 deg of cooling. In prac tice, the loss of circulating water by evaporation will approximate 1 per cent for 12 to 14 deg of actual cooling due to the additional amount of cooling by sensible heat transfer, and the rate of evaporation will vary from about 0.64 percent of the water circulated in the winter to 0.88 percent in the summer for a water-cooling range of 10 deg. The lowest temperature to which water may be cooled in atmospheric Spray Apparatus 819 cooling equipment is the temperature of adiabatic saturation, which is at the wet-bulb temperature of the air. ' Performance is measured in terms oi approach (5 to 10 F deg, with 7 F deg average) of the cooled water to the wet-bulb temperature of the ambient air when cooling the water through some desired range. The water-cooling range in some installations will vary from 10 to 12 F deg when a spray pond is used, and from 5 to 17, F deg (with 10 F deg average) for a mechanical draft cooling tower. Heat absorption by the moving air in an atmospheric wAter-cooling tower continues as long as the wet-bulb temperature of the air is lower than the temperature of the water. The rate of heat transfer depends upon: (1) the area of water in contact with the air; (2) the relative velocity of the air and water during contact; (3) the difference between the wet-bulb temperature of the air .and the initial temperature of the water; and (4) the time of contact of the air with the water. The rate of heat dissipation is also influenced by many' other lesser factors8 which further complicate the cooling tower design. Ultimate selection of water-cooling equipment for any specified service depends on overall economic considerations estab lished from correlated performance data. As the enthalpy of the moving air increases, its wet-bulb temperature rises (see Chapter 3). Since it is impracticable to allow the air to be in contact with the water for a long enough time to permit the wet-bulb temperature of the moving air and the temperature of the water to reach equilibrium, atmospheric water cooling equipment aims to circulate only enough air to cool the water to the desired temperature with least expenditure of power! DESIGN CONDITIONS FOR WATER-COOLING The maximum wet-bulb (design) temperature at which the total quan tity of circulating water must be cooled through a specified range by water cooling equipment is never selected as the highest wet-bulb temperature ever known to have occurred for some locality, nor the average wet-bulb temperature over any period of time. The maximum basis would require cooling equipment several times larger than normal capacity, and the average basis would result, for a large part of the time, in higher condenser temperatures than those for which the plant was designed. Accepted design practice for water-cooling towers, evaporative con densers, and spray ponds, is to use the maximum hourly outdoor dry-bulb temperature which will be exceeded no more than 2j percent of the time for the months of June to September; also, to use the maximum hourly, wet-bulb temperature which will be exceeded no more than 5 percent of the total hours for the same period. Tabulation of these data has not been completed. The limited portion of such data as are available is given in Table 2, Chapter 13 for airport weather stations; for other locali ties design dry-bulb and wet-bulb temperatures in use locally are tabulated as a guide to design temperatures. More complete summer weather data, statistics, charts, maps, and technical analysis have been prepared by Albright.4 Equipment for steam turbine condensers and internal combustion en gines, is usually based upon somewhat lower design temperatures if peak loads occur at night or during winter months when outdoor temperatures are lower. Knowing the hot water temperature and the wet-bulb temperature for which the equipment must be designed, the cold water temperature must be chosen to place the requirement within the effectiveness range of the 820 CHAPTER 35 1956. Guide; type of atmospheric water cooling apparatus to be used. This effective-'; ness is expressed as the percentage ratio of the actual cooling effect to the maximum possible cooling effect. Since the wet-bulb temperature of the entering air is the equilibrium temperature to which the water could be copied, the effectiveness of water cooling apparatus can be indicated thus: g (hot water temperature -- cold water temperature) X 100 hot water temperature -- wet-bulb temperature of entering air where Ei = water cooling effectiveness, percent. Magnitudes of this effectiveness ratio will vary through wide limits in accordance with construction and conditions of operation. Values indica tive of the commercial range of the effectiveness ratio are given in Table 3, although unusual designs may operate outside these ranges. Example 1; A mechanical refrigeration installation requires 3 gpm of cooling water, per ton of refrigeration, with the hot-water temperature at 95 F and the coldwater at 84 F, with a design wet-bulb temperature of 78 F. Find the water-cooling effectiveness of a mechanical draft tower for the above conditions. Solution: Substituting known conditions in Equation 2, Water-cooling effectiveness = 9j--5-------8--4 X 100 = 64.7 percent (typical). 95 -- -78 From a consideration of the factors which include the water-cooling range and the design wet-bulb temperature of the ambient air, the quan tity of water required can be calculated from the amount of heat to be rejected. The average quantities of heat to be removed from various types of mechanical equipment that require cooling are listed in Table 4. WATER-COOLING TOWER DESIGN Because of the many variables3 in water-cooling tower calculations and performance, it is difficult to provide simple handbook equations and tables whereby an engineer can readily select the type and size of unit for a definite requirement. Each manufacturer has a semi-confidential method of sizing a tower, based largely upon research and actual performance correlated with definite requirements; selection of water-cooling equipment for any specified service must ultimately depend upon overall considera tions established from reliable design and performance data. Some of the variables encountered in water-cooling tower work are: continuously changing air and water temperatures throughout the struc ture; varying moisture content, pressure, and volume of the moving air; caprice of the weather, ambient air changes in temperature, humidity, wind velocity and direction, and the amount of sunshine. Other less important physical properties of the air and water affecting tower per formance are: density, specific heat, conductivity, viscosity, vapor pressure, surface tension, latent heat, coefficient of expansion, vapor diffusivity, emissivity, and molecular weight. The air velocity, overall and in dif ferent parts of the tower, and also the type of air movement provided by natural draft, forced draft, induced draft, counterflow, or crossflow design have an important effect on heat transfer. Different features of construc tion will produce dissimilar velocities of water, and will affect its distribu tion and diffusion as well as the size of drops, jets, sprays, and sheets. The pressure and elevation of the water supply system, as well as the adsorption Spray Apparatus 821 Table 3. Effectiveness op Water Cooling Equipment Cooling Equipment Spray Ponds............................... Spray Filled Atmospheric Towers.. Atmospheric Deck Towers.... Mechanical Draft Towers....... Water Cooling Effectiveness--Percent Minimum 30 40 50 50 Typical 40 to 50 45 to 55 50 to GO 55 to 75 Maximum 60 60 90 93 auu niueiiaciai sunace tension oi the wetted tower areas also affect dis tribution. - Dissolved gases and other impurities in the water influence the water cooling process. Additional cooling tower variables affecting its perform ance include: location (ground, roof, nearby obstructions, wind orienta tion), dimensions, relative proportions (contour) of tower structure, ma terials, type and arrangement of interior surfaces; the louver and drift- eliminator designs as they facilitate the air flow to and from the tower; temperature of the structure at different points as influenced by the external and internal conditions. Other cooling tower factors to be considered are: loss of water by entrainment (drift loss), design and location of water collecting basin, and surface evaporation therefrom; also the noise generated by the air, water, fan, and structure vibration. . Basically, a water-cooling tower is a heat exchanger in which heat flows from the water to the air (1) by a flow of sensible heat from the warm water to the cooler air, and (2) by an exchange of, latent heat resulting from the evaporation of a small part of the circulating water to increase the humidity ratio of the air by a corresponding amount. The general principles involved are similar to those encountered in the processes of diffusion in absorption and.extraction equipment.5,6 Details of the application of the process to water-cooling tower perform ance have been published by various authorities,7 -a ao .u ,n an(j those interested in the derivation of the various equations should refer to these references, as listed at the end of this chapter. The approach in each case is based on a heat balance in which the total heat given up by the water equals the total heat absorbed by the air. These derivations are also based on certain assumptions, viz: that the specific heat of water is unity at the temperatures encountered; that there is no loss in weight of the by Cooling Water Mechanical Equipment Btu per Min per Ton Refrigeration Compressor................... Refrigeration, Absorption System... Steam Turbine Condenser.................. Steam Jet Refrigerating Condenser. Diesel Engine Jacket & Lube Oil: Four-cycle, Supercharged. Ffoouur-rc--ycle, NXTon-superc*harged.................. Two-cycle, Crank-case Compressor.......... - Two-cycle, Pump Scavenging, Large Unit. Two-cvcle, Pump Scavenging, High Speed Natural Gas Engine: '1 Four-cycle........................................................ Two-cycle....................................................... 250 550 -- 550 -- ------ -- ' -- Btu per Lb of Steam --L 1000 1100 -- -- -- -- -- -- BHP-HR __ __ -- 2600 3000 2000 2500 2200 4500 4000 822 CHAPTER 35 1956 Guide circulating water as a result of evaporation; that the water suspended in the tower is surrounded by a film of air which is saturated with water vapor and at the temperature of the water surrounded; and that the basic theory of cooling tower operation proposed by Lewis13 and developed by Merkel14 is applicable. This theory refers to the fact that the numerical value of the coefficient of sensible heat transfer, when divided by the numerical value of the coefficient of diffusion, equals the specific heat (at constant pressure) of air. The reader should observe that this relationship refers to the numerical values of three distinct constants, the units for each being different. The above relationship makes it possible to simplify the heat transfer equation by combining the two driving forces into one potential represented as the difference between the enthalpy of the air film (at water temperature) surrounding the water, and the enthalpy of the main air stream. conditions 1 WATER . L FLOW LB PER HR ACTIVE TOWER VOLUME V ^ AIR FLOW ii G^ LB PER HR CONDITIONS 2 Fig. 10. Operations in a Typical Water Cooling Tower Tower Performance Factor The operations taking place in a typical water-cooling tower are shown in Fig. 10. If the reduction in water flow rate, due to evaporation within the volume, is neglected, and the usual concepts of heat flow and mass heat transfer are applied, the equations typifying cooling tower operation are: . _ f1 dh a J2 w -- k (3) and KoF = r1 da L J2 h' -ft. (4) where a = overall average wetted area (surface of water drops plus wetted tower sur face), square feet per cubic foot of active tower volume. G -- weight rate of flow of air, pounds of dry air per hour. h = enthalpy, Btu per pound of dry air. Spray Apparatus 823 ft. = enthalpy of air-vapor mixture, Btu per pound of dry air.' . h" = enthalpy of saturated air-vapor mixture at water temperature, Btu per pound of dry air. K = overall energy unit.conductance, Btu per (hour) (square foot overall average wetted area) (Btu enthalpy difference per pound of dry air). L = water rate, pounds per hour. B = temperature of water in tower, Fahrenheit. ' 0, = temperature of inlet water, Fahrenheit. Bi = temperature of outlet water, Fahrenheit. V = active tower volume, cubic feet. Either term --yy-- or may be called the Tower Performance Factor G.L or Number of Tower Units (NTU). ,, Fig. 11. Temperature-Enthalpy Diagram for Air-Water Vapor Mixture Showing Operating Lines for Example 2 These equations indicate that the rate of heat transfer from the water to the air depends primarily upon the enthalpy of the air, the latter being dependent only on the wet-bulb temperature of the air. This explains the common observation that cooling tower performance is independent of inlet dry-bulb air temperature, and that adiabatic conditions exist. The integration of Equations 3 and 4 must be performed by mechanical or graphical means, because direct mathematical integration would be accurate only within narrow temperature limits. The temperature en thalpy diagram in Fig. 11 represents the conditions for either of the above equations. The water is cooled from the temperature Q\ to 02, and the enthalpy of the air film surrounding it follows the saturation line h". Air enters the tower at a wet-bulb temperature of ti, and an enthalpy of hi. It is heated to an outlet wet-bulb temperature of t{, with an enthalpy of hi. Since the heat rejected by the water equals the heat absorbed by the air, the heat absorbed per pound of air is a function of the pounds of water per pound of air going through the tower, and the slope of the air operating line is the L/G ratio. . 824 CHAPTER 35 1956 Guide Example S: It is desired to cool 150,000 lb of water per hour (about 100 tons of mechanical refrigeration) from 110 to 84 F with 125,000 lb of dry air per hour, with a design wet-bulb air temperature of 75 F. These conditions could prevail with a steam-turbine driven centrifugal refrigeration compressor. Determine the Tower Performance Factor; show in tabular form the successive steps for this mechanical integration by selecting two-degree intervals of the water-temperature range. Solution: The accompanying Table 5 shows the sequence of mechanical integration for the ipven water and air temperatures. The first column shows the water temper ature 6 m increments of two degrees (AS = 2 5? deg). Column 2 gives the enthalpies of the saturated air-vapor mixture at the water temperature, Btu per pound of dry air. The enthalpy of air, A in column 3, has an original value of 38.61 Btu per lb corresponding to the 75 F entering wet-bulb temperature of the ambient air; this value of A increases in equal increments of 1.2 ^gyatio^ Btu per F deg, hence, Ah = AS X Lg = 2 X 1f2550Q0Q00Crlibt) = Ptent`al fr mass heat tran sfer is (h" -- A,,) as shown in column 4; this is frequently called the tower driving force po tential. The values in column 5 for each increment are determined by dividing 2.4 Btu per F deg by the average value of (h* -- A,); and column 6 is calculated in a similar manner, except that the increments are two degrees instead of 2.4 Btu. Table 5. Sequence of Mechanical Integration Toweb PerfobmanceFactob Water Temp. e 2 Enthalpy op Film h" 3 A Enthalpy op. ir A. 4 Enthalpy Dippbrbnce (A" -- Ao) A6A (A* -- Aa) (avg.) 6 AH (A' - A.) (avg.) 84 86 88 90 92 94 96 98 100 102. 104 106 108 110 48.22 50.66 53.23 55.93 58.78 61.77 64.92 68.23 71.73 75.42 79.31 83.42 87.76 92.34 38.61 41.01 43.41 45.81 48.21 50.61 53.01 55.41 .57.81 60.21 62.61 65.01 67.41 69.81 9.61 9.65 9.82 10.12 10.57 11.16 11.91 12.82 13.92 15.21 16.70 18.41 20.35 22.53 0.249 0.247 0.241 0.232 0.221 0.208 0.194 0.180 0.165 0.150 0.137 0.124 0.112 0.208 0.206 0.201 0.194 0.184 0.173 0.162 0.150 0.137 0.125 0.114 0.103 0.093 Tower Performance Factor = 2.460 or 2.050 Hence, the mechanical integration for the above conditions gives two results ^a-- = y ------. = 2.46, Tower Performance Factor G ^ hr ~ K and KaV = 2.05, Tower Performance Factor The results obtained in Example 2 are designated as the Tower Per formance Factor (TPF) or the Number of Tower Units (NTU); these figures represent correlated values that are directly proportional to the performance being considered. Similar calculations could be made for other quantities and temperatures of air and water. It should be noted that this factor is not related to the equipment doing the cooling, that any numerical value may represent an infinite number of possible performance conditions, that any cooling tower arrangement may give almost any performance under certain conditions. Also the mechanical integration Spray Apparatus 825 procedure used above applies only to counterflow apparatus. However, the same principles may be applied to crossflow atmospheric water-cooling towers, although the method is more involved. The basic mathematical theory for water-cooling towers is now well established and recognized, hut each manufacturer relies upon experimental results and practical experience with his own tower designs to establish a system for rating each unit that he builds. The problem of cooling tower design or selection is based on a knowledge of the characteristics of the equipment being considered. The Tower Performance Factor is a variable which is a function of the design; it also varies with the water loading and air velocity. Experimental data indicate that it varies with the heat load, although this variation may be due to deviations from the theoretical calculations which become more pronounced at the higher temperatures. The reference literature contains Tower Performance Factors which have been reported by various investigators, but the reader should be warned that the use of such factors, without a full understanding of the source, may lead to erroneous results. SELECTION OF WATER-COOLING TOWERS The correct type and size of water-cooling equipment for a given service cannot be determined intelligently without considering the characteristics of the various types, together with the many correlated requirement factors. Very few installations are exactly alike in details of requirements, hence, conditions affecting performance and operation of the several types of water-cooling equipment vary widely because of the many diversified applications and wide-spread geographical locations. Before the characteristics of a specific water-cooling apparatus can be judged desirable or undesirable for a given heat load and wet-bulb tem perature, a survey should consider the importance of each of the following items: first cost including all necessary auxiliaries, area, height, weight, effect of wind velocity and direction, rigidity of structure to withstand high winds, safety, conformity to building codes, drift nuisance, make-up water requirements and cost of chemical treatment if needed, total power for pumping (plus fan operation in the case of mechanical draft), maintenance, available locations (with due thought to possible future expansion, mnd restrictions, space cost, proximity and accessibility, etc.), appearance, the equipment's operating flexibility for the most economical conformance to varying loads or seasonal changes, and other considerations occurring with regard to a specific application. For a definite heat-load dissipation, the type and size of a water-cooling tower is primarily affected by the following conditions: 1- Gallons per minute of cooling water. 2. Geographical location of the tower installation. 3. Wet-bulb design temperature of ambient air (see Table 2, Chapter 13). 4. Temperature of the hot water entering the tower at normal rating. 5. Temperature of the cold water leaving the tower at normal rating. 6. Ground, roof, or sub-structure installation. 7. Area available for cooling tower. 8. Proximity to other structures. 9. Surface of water exposed to each unit quantity of air. 10. Time of contact of the air with the water; this depends upon height (or length) of tower, and upon the relative velocity of air and water. 826 CHAPTER 35 1956 Guide The selection of a proper water-cooling range depends upon: (1) type of. service--refrigeration, internal-combustion engine, or /steam condenser; : (2) wet-bulb air temperature at which the equipment must operate; and (3) type of condenser or heat exchanger employed. Because the design of an entire plant is usually affected by the quantity and temperature of the cooling water supply, plants should be designed for cooling water conditions which can be most efficiently attained. The first consideration is usually the limiting temperature of the plant. For example, if an ammonia compressor refrigerating plant is to be designed for 185 psig head pressure as a normal maximum, the limiting temperature of the ammonia in the condenser is 96 F. Should the ammonia tempera ture go above this figure, the head pressure will exceed 185 psig and the power consumption increase. To obtain this head pressure, the tempera ture of the circulating water leaving the condenser must always be less Table 6. Condenseb Design Data Gas Desired Pressure in Condenseb Gas Temperature Leaving Hot-Water . Temperature, Fahrenheit Fahrenheit Best Average Condenser Condenser Design Design Steam.................................. Carbon dioxide................. Dichlorodifluoro- methane 28 in. vacuum 27 in. vacuum 26 in. vacuum 185 psi* 1030 psig* 102 psig* 117 psig* 126 psig* 136 psig* 101.2 115.1 125.4 96.0 86.0 100.0 100.0 105.0 110.0 97 93 no 105 120 114 92 88 83 80 96 92 96 93 100 97 .104 101 * Head pressure. than 96 F by an amount depending upon the size and design of the con denser, the quantity of water being circulated, and the refrigerating tonnage being produced. A condenser having a large surface per ton of refrigera tion may be designed to operate satisfactorily with the leaving hot-water temperature within 3 or 4 deg of the ammonia temperature corresponding to the head pressure, while a small condenser may require a 10 deg dif ference. Table 6 lists several gases with data for the temperatures and pressures for which commercial condensers are designed. Careful evaluation of costs of water and electrical power should be made before deciding to use city water for jacket water and condensers. Economy of operation gen erally indicates the use of either a water-cooling tower or an evaporative condenser for most refrigeration installations of five tons or more capacity. Refer to Chapter 37, for information on Evaporative Condensers. In ternal-combustion engines have limiting hot water temperatures of 140 to 180 F for closed systems, and 110 to 130 F for open systems, depending upon the quality of the cooling water. The cooling of such fluids as milk or wort has variable requirements, and is usually accomplished in counter flow heat-exchangers in which the leaving circulating water is at a much higher temperature than is the leaving fluid. Spray Apparatus 827 OPERATION AND MAINTENANCE Water Treatment. The amount of make-up water required by a cooling tower depends upon evaporation loss, drift loss, and blow-down. Evapora tion losses average 0.80 percent of the water circulated for each 10 F deg range. Drift loss is the water carried out of the tower by the air currents in the form of droplets or mist. In properly designed induced draft towers this loss normally approximates one-tenth of one percent, and most cooling tower manufacturers will guarantee a drift loss not to exceed twotenths of one percent. The amount of blow-down water wasted, depends upon the hardness of the circulating water, type of water softening used and the amount of. drift loss. Blow-down is normally controlled to main tain the concentration of soluble and scale-forming solids below the point where the formation of scale would occur or would be caused by corrosion. Algae formations will plug nozzles and prevent proper distribution of the water over the tower filling. This growth may also collect on equip ment served by the cooling tower, and thereby reduce the heat transfer rate. Algae should be held at a minimum or eliminated by use of bromine, chlorine, chlorinated lime, copper sulfate, or various blends of chlorophenates (see Chapter 43). Although some scale-forming materials are found in practically all water, those which cause trouble ip water-cooling systems are normally calcium and magnesium carbonates. Scale formation in equipment served also reduces heat transfer rates. Scale can be reduced materially or prevented by softening the make-up water with lime and soda ash, zeolite, or sulfuric acid, or by use of small amounts of sodium hexametaphosphate. Water softening or treatment requires close regulation and control by a competent chemist. Too high a concentration of soluble solids in cooling tower water may raise the temperature of the water leaving the tower, and may cause sludge deposits or corrosion in the system. Concentration of solids is normally controlled by either blowing down or by a continuous overflow to the sewer. Refer also to Chapter 43. Delignification. The presence of sodium carbonate in the circulating water results in delignification of any wood with which water comes in contact. This chemical dissolves lignin which binds the wood fibers to gether and leaves the wood surface in a white fibrous condition. Prolonged exposure reduces the structural strength of the Wood. Delignification first appears on parts of the tower that are alternately wet and dry, since evaporation at such points rapidly increases the concentration of dissolved solids. The presence of sodium carbonate in harmful amounts is generally indicated by a high pH of 9 to 11. The effect of the sodium carbonate may be neutralized by the use of sulfuric acid. It is desirable to have the pH value of the water at 7 to 7.5 (7.2 pH value is neutral for redwood). Two-speed, Motors. For readily adapting tower performance to tempo rary or seasonal decreases in heat load, and especially for winter operation, the use of two-speed motors (for fan drives) is recommended. The chief advantage is that when operated at half-speed, fans require only about 15 percent of the power used at full speed. Particularly in multi-fan towers, the ready flexibility provided by two-speed motors results in considerable savings, even though load reductions may sometimes call for only one or a few fans to be operated at half speed. Cold-weather Operation. Extremely cold water normally does not in- S28 CHAPTER 3S 1956 Guide crease performance to any great extent, but increases operating hazards considerably. Water-cooling towers operated in sub-freezing weather are subject to ice formation on the louvers and the outer portion of the filling. To prevent icing in cold-weather operation, the' cold raw water (tower circulating water) temperature should be maintained as high as practicable, taking into consideration the effect upon the economy of the equipment served. One or more of the following procedures are recommended for induced draft towers: (a) run two-speed motors on low speed, or shut off some of the fans; (b) shut down some cells completely and put all of the water over the remaining cells; (c) reduce water flow to the tower and shut off some of the cells; (d) by-pass the cooling tower with part of the water and shut off some of the fans or cells of the tower. , If ice should form on the louvers and filling, one of the following methods of removal can be used: (a) reversing (for not more than 10 minutes) the rotation of the motor driving the fan and thus blowing the warm air out through the louvers; (b) shutting down fans on some sections tem porarily, but not the water. When these cells have thawed out, use the same procedure on other cells. Where intermittent operation of a system is employed, water in outside basins may cause considerable damage due to freezing. To prevent this, such basins are drained when out of service and therefore in some small roof installations a tank large enough to hold all the water in the system may be installed inside the building. Maintenance, Well-maintained equipment provides the best operating results and the least overall maintenance cost. A regular schedule should be set up for the structural and mechanical upkeep of water-cooling towers. The life and continued utility of any cooling tower is directly dependent upon its inherent qualities, climatic environment, type of service, severity of operation, and general care and maintenance. '- REFERENCES 1 Temperature of Water Available for Industrial Use in the United States, by W- D. Collins (U. S. Geological Survey, Water Supply Paper No. 520 F). 1 A.S.H.V.E. Research Paper--Design of Spray Cooling Ponds, by S. Hori, U. A. Patchett and L. M. K. Boelter (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, October, 1942, p. 624). * Cooling Tower Performance Studies, by L. M. K. Boelter (A.S.H.V.E. Transac tions, Vol. 45, 1939, p. 615). * Summer Weather Data; Statistics, Charts, Maps, and Analysis, by J. C. Al bright, 1939. (The Marley Company, Inc., 1944). 8 Principles of Chemical Engineering, by W. H. Walker, W. K. Lewis, W. H. Mc Adams and E. R. Gilliland (McGraw-Hill Co., 1937, p. 480). 8 Absorption and Extraction, by T. K. Sherwood (McGraw-Hill Co., 1937, p. 91). 7 Heat Transmission, by W. H. McAdams (McGraw-Hill Co., 1933, p. 157). 8 Performance Characteristics of a Mechanically Induced Draft, Counterflow, Packed Cooling Tower, by.. A. L. London, W. E. Mason and L. M. K. Boelter (A.S.M.E. Transactions, January, 1940, Vol. 62, p. 41). 8 Determination of Unit Conductances for Heat and Mass Transfer by the Tran sient Method, by A. L. London, H. B. Nottage and L. M. K. Boelter (Industrial and Engineering Chemistry, April, 1941, Vol. 33, p. 467). 10 Graphical Method of Determining Number Transfer Units, by T. Baker (In dustrial and Engineering Chemistry, August, 1935, Vol. 27, p. 977). " Performance and Selection of Mechanical-Draft Cooling Towers, by Joseph Lichtenstein {A.S.M ,E. Transactions, October, 1943, Vol. 65, No. 7, p. 779). 17 Performance of Small Mechanical Draft Cooling Towers, by W. M. Simpson and T. K. Sherwood (Refrigerating Engineering, December, 1946, p. 535). 13 The Evaporation of a Liquid into a Gas, by W. K. Lewis (A.S.M.E. Transac tions, Vol. 44, 1922, p. 325). 14 Verdustungs Kiihlung, by H. Merkel (Forschungsarbeiten, No. 275, 1925). CHAPTER 36 AIR HEATING AND COOLING COILS Uses for Coils; Coil Construction and Arrangement: Steam Coils, Water Coils, Direct-Expansion Coils, Flow Arrangement, Applications; Coil Selection: Heating, Cooling and Dehumidifying Coils; Heat Transfer and Air Flow Resistance; Performance of Heating and Dry Cooling Coils; Overall Coefficient of Heat Transfer; Performance of Dehumidi- . fying Coils; Determining Refrigeration Load COILS described in this chapter are used for heating or cooling an air stream under forced convection. Surface coil equipment may be made up of a number of banks assembled in the field, or the entire assembly may be factory constructed. The applications of each type of coil are limited to the field within which it is rated. Other limitations are imposed by code regulations, by proper choice of materials for the fluids used and the condition of the air handled, or by an economic analysis of the possible alternates on each installation. USES FOR COILS For heating service, coils are used as tempering coils, preheaters, reheaters or booster heaters. The function of the coils is air heating only, but the apparatus assembly may include means for humidification and air cleaning. Steam or hot water are the usual heating media, although others are used in special cases, such as reheating by means of discharge gas from a refriger ating system. Coils are used for air cooling with or without accompanying dehumidi fication. Examples of cooling applications without dehumidification are precooling coils using well water or other relatively high temperature water to reduce the load on the refrigerating machinery , or water cooled coils re moving sensible heat in connection with chemical moisture-absorption apparatus. A major portion of coil equipment is designed to handle both sensible cooling and dehumidification. The assembly usually includes air cleaning means to protect the coil from accumulation of dirt, and to keep dust and foreign matter out of the conditioned space. Although cooling and dehumidification are the usual functions, cooling coils are additionally and purposely, wetted to aid in air cleaning and odor absorption. The usual cooling media used in surface coils are cold water or Group I (ANA Classification) refrigerants, but others are used in special cases. Brines are seldom required for the range of applications covered by this chapter, although there are cases where Tow entering air temperatures with large latent heat loads require a refrigerant temperature so low that use of water becomes impracticable. Sometimes, also, brine from an industrial system already installed is the only convenient source of refrigeration. For combined cooling and dehumidifying, surface coils present an alter nate to spray dehumidifiers. For many applications it is possible, by proper selection of apparatus, choice of air velocities, refrigerant tempera tures, etc., to perform the same duty with either. In a few cases both sprays and coils are used. The coils may then be installed within the spray 829 830 CHAPTER 36 1956 Guide chamber, either in series with the sprays or below them. In making the selection between spray and surface dehumidifiers, certain advantages of each should be considered. The fact that a spray dehumidifier is usually designed to deliver nearly saturated air, tends to simplify the control prob lem. In this case the dry-bulb temperature is also the dew point, and hence, a dew point control can be arranged by using a simple duct thermo stat. Spray dehumidifiers have an advantage over unwetted coils of ob taining some air cleaning and odor absorption. On the other hand,. Coils make possible a closed and balanced cooling water circuit, obviating the unbalanced pumping head, the complication of water level control, and danger from possible floods incidental to multiple spray dehumidifiers, especially if located on different levels. The use of coils often makes it possible for the same surface to serve for summer cooling and winter heating by circulating cold water in the one season and hot water in the other, with consequent saving in apparatus and piping. Another advantage is that where the surface coil system can be used with direct expansion of refrig erant, it is comparatively low in initial and operating costs. For comfort conditioning applications, the regulations of the applicable national and local safety codes should be consulted by the design engineer. COIL CONSTRUCTION AND ARRANGEMENT Coils are basically of two types, those consisting of plain tubes or pipe, and those having extended surfaces. The former are little used for the applications covered by this chapter, but are often employed where condi tions cause frost accumulation, and for cooling within spray dehumidifiers. The heat transmission from air passing over a tube to a fluid flowing within it is impeded by three resistances. The first is that from the air to the surface of the tube and is usually called the outside surface resistance or air-film resistance. The second is the resistance to the conduction of heat through the metal itself. Finally there is another surface or film resistance to the flow of heat between the inside surface of the metal and the fluid in the tube. For the applications under consideration both the resistance of the metal wall to heat conduction, and the inside surface or film resistance are usually low as compared with the air-side surface resist ance. Economy in space, weight and cost makes it advantageous to de crease the external surface resistance, where it is proportionately large, to approach that of the tube wall, and that from the tube to refrigerant. This may be accomplished by increasing the external surface by means of fins. Sometimes water spray is applied to the same type surface as would have been used without it. The overall heat transfer is not necessarily increased much, but the water spray may serve other purposes than to increase the flow of heat, such as air and coil cleaning. In fin or extended-surface coils the external surface of the tubes is known as primary, and the fin surface is called secondary. The primary surface consists generally of round tubes or pipes which may be staggered, or in some cases placed in fine with respect to the air flow. The staggered arrangement is usually preferred because it obtains a somewhat higher heat transfer value. Numerous types of fin arrangement are used, the most common of which are spiral, flat and flat-crinkled or corrugated, all as shown in Fig. 1. While the spiral fin surrounds each tube individually m all cases, the flat types may be continuous (including several rows of tubes), or they may be round or square, with individual fins for each tube. All of these, as well as other less common types, are in use, the selection for a particular installation being based on economic considerations, space re Air Heating and Cooling Coils 831 quirements and resistances of individual designs of coils. A most impor tant factor in the performance of extended-surface coils is the bond between the fin and the tube. An intimate contact between the tube and the fin must be maintained permanently in order to assure a continuing rated performance after the heating units have been in service for a period of time. In some coils, fins are wound on the tubes under pressure, in order to upset the metal slightly at the fin root, and then are given a coating of solder while the fin and tube are still revolving, for the purpose of assuring a uniform coating of solder. In other types, the spiral fin may be knurled into a shallow groove on the exterior of the tube. The tube may be ex panded after the fins are assembled, or the tube-hole flanges of a flat or corrugated fin may be made to override those in the preceding fin and so compress them upon the tube. There are also types of construction where the fin is formed out of the material of the tube itself. For heating coils, materials most generally used are copper and aluminum. Steel is occasionally used where sodium or calcium chloride brine is circu lated in the tubes. Aluminum fins on copper tubes are a common con- OO OO Hat continuous fins oo OO oo flat corrugated fins o flat square tins Fig. 1. Types op Fin Coil Arrangement o struction. Generally speaking, brass does not serve as a satisfactory fin material because of corrosion difficulties. Cooling coils for water or for volatile refrigerants most frequently have copper fins and tubes, although aluminum fins on copper tubes are also used. There are many makes of heating and cooling coils of the light weight extended surface type for both heating and cooling with tubes commonly -J-, A, and 1 in. outside diameter, and with fins spaced three per inch up to eight per inch. The tube spacing generally varies from about 1-j to. 2^ in. on centers, depending upon the width of individual fins and on other considerations of performance. Fin spacing should be chosen for the duty to be performed, with special attentmn being paid to possibility of lint accumulation and, especially in dehumidifying, the consideration of frost accumulation. Steam Coils For proper performance of steam heating coils, condensate and air must be continuously eliminated and the steam must be evenly distributed to the individual tubes. This distribution is usually accomplished by indi vidual orifices in the tubes, by distributing plates and orifices in the steam header, or by perforated internal steam-distributing pipes extending into t v, *n^v^ua* tubes. The latter arrangement has the advantage of dis tributing the steam throughout the length of each tube, and is conducive to uniform temperature of delivered air. The tendency of condensate to freeze at the bottom of the coil with cold entering air and light heating 832 CHAPTER 36 1956 Guide loads, is also minimized. This is especially valuable for outside air pre heaters. / Water Coils . The performance of water coils, for heating or cooling, depends on the elimination of air from the system and proper distribution of water. Air elimination is taken care of in the system piping as described in Chapter 22. To assure a pressure drop sufficient for adequate distribution, but at the same time to provide against excessive pumping head where large water quantities are handled, water coils are provided with various water circuit Water ouflet f Air Heating and Cooling Coils 833 sion valve system depends upon the thermal valve automatically feeding just as much liquid to the cods as is required to maintain the superheat at the coil suction outlet within predetermined limits, which vary' from about 6 to 10 deg. The thermal valve arrangement is in common use for the type of coils covered by this chapter, while the flooded system is rarely used. With the flooded system the refrigerant distribution through the tubes depends on properly selecting the length of the feeds, and the head of liquid imposed upon the liquid inlets. No auxiliary distributing devices are re quired. With the thermal valve system, there are two factors to consider. There must be, generally, more than one refrigerant feed: through the coil per thermal valve to keep the pressure drop through the refrigerant circuit within practical limits, and to reduce the corresponding penalty in increased Fig, 2. Various Water Circuit Arrangements arrangements. For instance, a typical coil 18 tubes high and 6 tubes deep in the direction of air flow can be arranged for 6, 9, 18, 24, or 36 parallel water circuits, as conditions may require. Orifices in individual tubes are occasionally employed, but are usually unnecessary as the resistance of individual water circuits is generally sufficient to effect a satisfactory distri bution. In precooling coils using well water, where there may be consider able sand and other foreign matter in the water, provision for cleaning of individual tubes is of advantage. It is important to arrange water coils for complete drainage (see Fig. 2). The drains are usually provided in the water piping at the coil header. Direct-Expansion Coils Coils for volatile refrigerants present more complex problems of fluid distribution than do water, brine or steam. It is desirable that the coil be effectively and uniformly cooled throughout, and necessary that the compressor be protected from entrained, unevaporated refrigerant. There are two types, namely, flooded systems, and thermal expansion valve sys tems, as shown in Figs. 3 and 4. In a flooded coil, the circulation is similar to that in a water tube boiler. The liquid is maintained at the proper level by the action of a float regulator as shown in Fig. 3. The thermal expan- Fig. 3. Direct-Expansion Coil with Flooded System Fig. 4. Direct-Expansion Coil with Thermal Valve System evaporating temperature. At the same time the coil must be so arranged that the required suction superheat can be attained with a minimum sacri fice in the performance of the coil as a whole. It is general practice to attain this superheat within the coil itself, and not by the use of external heat exchangers or other auxiliary devices. With thermal expansion valves it is advantageous to keep the pressure drop through the refrigerant feeds as low as possible. The feeds are laid out to expose each to the same mean temperature difference so that it handles the same refrigerating load. Here, a distributing means is imposed between valve and coil liquid inlets to divide the refrigerant equally among the feeds. Such a distributor must be effective for distributing both liquid and vapor, because the entering refrigerant is a mixture of the two. Fig. 5 shows three typical types of distributors. In distributor A the liquid and gas mixture from the thermal valve is led tangentially into a chamber. The coil feed connections extend outward radially at the top of this chamber. In distributor B the refrigerant is discharged at a high velocity through a central jet against the end plate, forming a uniform mixture of gas and liquid within the distributor, from which individual connections are led as shown. In type C the refrigerant enters at high velocity from the thermal valve and is discharged against the end plug in which the indi vidual liquid feeds are closely arranged. These distributors can be used in either vertical or horizontal position. There are also other types of headers such as the centrifugal and weir type. The individual liquid con nections from the distributor to the coil inlet are commonly made of small diameter tubing, and are all of the same length and diameter in order to impose the same friction between the distributor and the coil; Since the 834 CHAPTER 36 1956 Guide thermal valves act in response to the superheat at the coil outlet, this super heat should be produced with the least possible sacrifice 'of active evaporat ing surface. Sometimes a single thermal valve is used per coil. In other cases, multiple valves are used, with the coil divided across the air flow or parallel to the air flow as shown in Fig. 6. The arrangement of Fig. 7 should be avoided, since it offers the disadvantage of unequal load on the two parallel circuits. Flow Arrangement In all heat transfer processes, the relative directions of flow of the fluids influence the performance of the heat transfer surface. In air-heating and cooling coils, the air usually flows at right angles to the tubes. In a coil having only one row in the direction of air flow, the relative directions of Air- Heating and Cooling Coils .835 C Fig. 5. Types op Refrigerant Feed Distributing Heads flow would all be at right angles. In coils having more than one row in the direction of air flow, the media in the tubes may be variously circuited as illustrated for water or steam coils in Fig. 8. It is the usual practice to designate a coil that is circuited and employed as in Fig. 8A as a parallel flow coil. Figs. 8B and 8C show the general arrangements that are termed counter-flow and cross-flow respectively. Cross flow is common in steam heating coils, the temperature within the tubes being substantially uni form, and the mean temperature difference the same whatever the direction of flow, relative to the air. The parallel and counter-flow arrangements as illustrated in Figs. 8A and 8B are common in brine or water coils, with the counter-flow arrangement being the preferred arrangement to secure the advantage of highest possible mean temperature difference. Most directexpansion coils also follow the general scheme of counter flow but the cir cuiting requirements for proper loading sometimes result in a combination of the other flow arrangements with counter flow in the same coil. Cross flow is generally avoided in the volatile refrigerant coils because of the un equal loading of the parallel circuits. Applications Heating coils in field-assembled banks are used for a number of purposes as described in Chapter 30. They may be arranged with the air flow vertical or horizontal, although the latter is more common. For steam heating, the coils may be set with the tubes vertical or horizontal. In the latter case the coil should be sloped to provide for condensate drainage. Because of the multi-circuit feed arrangement and the necessity for avoid ing air and water pockets, water heating coils are generally arranged with the tubes horizontal. Certain precautions must be taken against freezing. Where steam coils are used with entering air below freezing temperature, throttling the steam supply may cause, freezing of the condensate in the bottom of the coil, if the tubes are of the variety not provided with internal distributing pipes or an equivalent arrangement. There are coils available having inner distributing tubes, and having the supply a,nd return. headers cast in one piece. In this type of coil the condensate that forms in the outer tube has resulted from steam fed from Sr3 Fig. 8. Flow of Media in Tubes in Relation to Air Flow 836 CHAPTER 36 1956 Guide the inner tube orifices. This condensation flowing back along the warm inner tube is prevented from freezing. A wide range of modulation at very low temperatures without danger of freezing, is therefore obtained. As an added precaution, with both steam and water coils, the outside air inlet dampers are often closed automatically when the fan is stopped to avoid trouble caused by very cold outside air drifting in during off periods. A typical arrangement of coils is shown in Pig. 9. All of the air should be filtered to prevent dirt, insects and foreign matter from accumulating on the coils. The cooling coil and humidifier must be provided with a drip pan to catch the condensate formed during the cooling cycle and the excess water from the humidifier. The drain connection should be on the down stream side of the coils, made of ample size (not less than 11^-in. pipe), provided with accessible clean-outs, a deep seal trap, and discharge to an indirect waste, so that there will be no-possibility that sewer gas may enter Air Heating and Cooling Coils 837 from one coil to the next one. In such cases, drip troughs as are shown in Fig. 10 are used to collect the water and conduct it to the drain pan. The enclosure around a coil or filter bank should be corrosion resistant and should have adequate access doors to provide for changing of air filters, cleaning of coils, adjusting expansion valves, oiling motors, etc. Sometimes cooling and dehumidifying coils are sprayed with water to increase the rate of heat transfer and to provide leaving air approaching saturation. This arrangement requires a collecting tank and recirculating pump to maintain water circulation whenever the apparatus is in operation. Fig. 11 illustrates this arrangement with a bypass around the coil. This bypass is often used to facilitate thermostatic control. It is advantageous Fig. 9. Typical Arrangement of Cooling Coils in. a Central System the system. Precautions against freezing must be taken with the hu midifier piping and drain connections. Water coils and large steam coils are also subject to freezing. Cold out side air must be provided with tempering coils or mixing vanes. They must be installed to insure thorough mixing of the outside and return air to prevent this hazard. Face and by-pass damper have proven to be satisfactory means of ca- pacity reduction for cooling coils using non-volatile refrigerants. The use of such face and by-pass damper arrangements on volatile refrigerant.coils poses difficult refrigerant control problems which are most severe when a change of setting at the thermostat imposes a rapid change in the dampers at the coils. On many installations, the coil bank is divided into 2, 3, or 4 sections and each section is connected to an individual compressor, or connected to a modulating compressor or compressors which will adjust to the load as each succeeding coil section is cut out by the thermostat. The design features of the coil (fin spacing and type of fins, whether circular fins or plate) determine at what air velocity condensed moisture will be blown off the coil. Water blows off some coils below 400 fpm face velocity, while this does not occur on others at face velocities in excess of 500 fpm. Where there is a likelihood of water being blown off the coil face, eliminator plates should be placed on the down-stream side of the coil. Plate coils are most frequently installed without eliminator plates. When a number of coil sections are stacked one above another, there is a tendency for the condensate to be carried out into the air stream as it drips Fig. 10. Coil Arranged with Drip Trough Fig. 11. Recirculating Spray System for Cleaning Coils to direct only return air through the bypass rather than a mixture of return and outdoor air in order to hold the humidity ratio under thermostatic control. Although both heating and cooling coils are made of sufficient strength to take up expansion and contraction arising within themselves, care should be taken to avoid imposing strains from the piping on the coil connec tions. (See Chapter 21.) COIL SELECTION In the selection of a coil it is necessary to consider various factors: 1. The duty required:heating, cooling, dehumidifying, and the capacity required to maintain balance with other system components such as'-compressor equipment in the case of direct expansion coils. 2. Temperature of entering air--dry-bulb only if there is no dehumidification; dry- and wet-bulb if moisture is to be removed. 3. Available heating and cooling media. 4. Space and dimensional limitations. 5. Air quantity limitations. 6. Allowable resistances in air circuit and through tubes. 7. Allowable resistance betwen the inlet and the outlet of the coil tubing circuits. 8. Characteristics of individual coil designs. 9. Individual installation requirements, such as, for example, the type of auto matic control to be used. The duties required may be determined from information in Chapters 9, 838 CHAPTER 36 .1956 Guide 11,12,13 and 30. There may, or may not, be a choice of cooling and heat ing media, as well as temperatures available, depending upon whether the installation is new or is in combination with present, sources of heating or cooling. Space limitations are dictated by the requirements of individual cases. The air quantity is influenced by a number of considerations. The air quantity through heating coils is often made the same as that necessary to handle the summer cooling load. The air handled may be limited by the use of old ventilating ducts as the air distribution system or may be dictated by requirements for satisfactory air distribution or ventilation. The resistance through the air circuit influences the fan horsepower and speed. This resistance may be limited to allow the use of a given size of fan motor, or to keep the operating expense low, or it may be limited be cause of sound level requirements. The allowable friction through the water or brine circuit may be dictated by the head available from a given size of pump and pump motor. The performance of a surface heating or cooling coil depends upon correct choice of the original equipment, and upon proper application and maintenance. Coil ratings are based on a uniform face velocity. Interference with uniform air flow through the coil will affect performance. Such air flow interference may be caused by air being brought in at odd angles or by inadvertent blocking of a portion of the coil face. To obtain rated per formance it is necessary that the air quantity be adjusted on the job to that used in determining the coil selection, and that it be kept at this value. The most common causes of a reduction of air quantity are the fouling of the filters and collection of dirt in the coils. These difficulties can be avoided by proper design and regular servicing. There are a number of ways in which coils may be cleaned. A common method is to wash them with water. They can sometimes be brushed and cleaned with a vacuum cleaner. In bad cases of neglect, especially on restaurant jobs where grease and dirt have accumulated, it is sometimes necessary to remove the coils and wash off the accumulation with steam, compressed air and water, or hot water. The best practice, however, is to keep the filters serviced, and to inspect and wash the coils at regular intervals. The proper selection of coils requires an understanding of the require ments of each case, and should be based on an economic analysis of the plant design as a whole. While no general rule can be established for the selection of heating or cooling coils, it is possible, however, to point out the limits of usual practice and to indicate the influence of the variables involved in the coil selection. Heating Coils Steam and hoi water healing coils are usually rated within these limits: Air Face Velocity--200 to 1200 fpm, sometimes up to 1500 fpm. Steam Pressure--2 to 200 psig, sometimes up to 350 psig. Hot Water Temperature--150 to 225 F. Water Velocity--2 to 6 fps. ' Individual cases may deviate widely, but the tabulation given herewith will serve as a guide to usual healing installation practice: Air Face Velocity--500 to 800 fpm face, 500 being a common figure. Delivered Air Temperature--varies from about 72 F for ventilation only, to abou 150 F for complete heating. ' Steam Pressure--2 to 10 psig, 5 psig being common. Hot Water Temperature--150 to 225 F. Water Velocity--2 to 6 fps. Air Heating and Cooling Coils 839 Water Quantity--Based on about 20 deg temperature drop through a hot-water coil. Air Resistance--The total resistance through heating coils is usually limited to from % to % in. of water for public buildings, to about 1 in. for'factories. The selection of heating coils is relatively simple as it involves dry-bulb temperatures and sensible heat only, without the complication of simul taneous latent heat loads, as in cooling coils. For a, given duty, entering air temperature, and steam pressure, it is possible to select several arrange ments of the same design of coil depending upon the relative importance of space, cross-sectional area, and air resistance. Cooling Coils Cooling and dehumidifying coils are usually rated within these limits: Entering Air Dry-Bulb--60 to 100 F. Entering Air Wet-Bulb--50 to 80 F. Air Face Velocities--300 to 800 fpm'(sometimes as low as 200 and as high as 1200). Volatile Refrigerant Temperatures--25 to 55 F, at coil suction outlet. Water Temperatures--40 to 65 F. Water Quantities--2 to 6 gpm per ton, or equivalent to a water temperature rise of from 4 to 12 deg. Water Velocity--2 to 6 fps. The ratio of total to sensible heat removed varies in practice from 1.00 to about 1.65, i.e., sensible heat is from 60 to 100 percent of total, depend ing on the application. (See Chapter 30.) Since required ratios may de mand wide, variations in air velocities, refrigerant temperatures, and coil depth, general rules as to their values may be misleading. On most com--fort installations air face velocities between 400 and 600 fpm are frequent, 500 being a common value. Refrigerant temperatures ordinarily vary between 35 and 50 F where cooling is accompanied by dehumidification. Water velocities range from 2 to about 6 fps. When no dehumidification is desired, for which condition the dew point ` of the entering air is equal to or lower than the cooling coil surface temper ature, the coil selection is made on the basis of dry-bulb temperatures and sensible-heat transfer only, the same as with heating coils. It is possible also to choose various arrangements of face area, depth, air velocity, etc., for the same duty. Dehumidifying Coils . The performance of coils accomplishing both cooling and dehumidifi cation is determined by a series of tests carried on under laboratory con ditions. Coil ratings can be prepared from such laboratory test data to facilitate the selection of coils for cooling and dehumidifying duty. The coil capacity should be in balance with the capacity of related equipment, such as compressors, and the temperature of the circulating medium. The selection of cooling coils for factory-assembled self-contained air conditioners is generally accomplished in conjunction with laboratory test ing. The current industry standards call for ratings at 33.4 cfm per thousand Btu of cooling capacity and this is approximately 400 cfm per ton of refrigeration. The use of an entering air condition of 80 F dry bulb and 67 F wet bulb is representative of the entering air conditions actually encountered in many comfort operations because, while the indoor con ditions are usually lower than 67 wet bulb, the introduction of outside air will usually bring the mixture of air to the cooling coil up to an approxi mation of the 67 wet bulb entering air condition at design conditions. The selection of cooling coils for field assembled projects is usually ac- 840 CHAPTER 36 1956 Guide complished by the use of coil rating tables. The practice of selecting coils from the load division indicated by the load calculation ' has worked out satisfactorily for the usual human comfort applications. Additional de sign precautions and refinements are being used for more exacting indus trial applications and for improved results on all types of air conditioning in the more humid areas. One of these refinements is the use of a separate cooling coil to cool and dehumidify the ventilation air before admixture with recirculated air. This procedure takes care of one of the main sources Of moisture in the usual application. Provision for reheat is required for some industrial applications, and is used for better results on very special commercial applications. In checking the operating results obtained from cooling coils in various air conditioning installations, it is necessary to keep in mind the influence of the climatic conditions of the various areas encountered. The majority of problems are encountered at light load conditions when the cooling re quirement is considerably less than at design conditions. In the hot dry climates, where the outside dew points are so constantly low that dehumidifying is not generally a problem, the light load condition does not pose any special problems. In the hot humid climates, where the outside dew points are generally high and close to the dry-bulb temperatures, the light load condition has a higher proportion of moisture and a correspondingly lower proportion of sensible heat. These climatic conditions result in higher dew points in the conditioned spaces during the light load conditions unless some of the special means for controlling the inside dew points are used. In the geographic locations where warm weather occurs with both high and low dew points, such as around the Great Lakes, the light load operating conditions with the-higher percentage of moisture loading will be encountered less frequently and consistently than in the south coastal areas. Care should be taken to avoid freezing at light loads. In general, freez ing occurs when the coil surface temperature falls to 32 F. With usual coils for comfort installations, this does not occur unless the evaporating tem perature at the coil outlet is about 20 to 25 F. The exact value depends on the design of the coil and the amount of loading. Although it is not customary to choose coil and condensing units to balance at low tempera tures at peak loads, there is danger of this occurring when the load decreases. This is further aggravated if a by-pass is used so that less air is passed through the coil at light loads., HEAT TRANSFER AND AIR FLOW RESISTANCE The transfer of heat between the heating or cooling medium and the air . stream is influenced by several variables: 1. The temperature difference. 2. The design and surface arrangement of the coil. 3. The velocity and character of the air stream. 4. The velocity and character of the medium in the tubes. The driving force is usually taken as the logarithmic mean temperature difference for heating or cooling without dehumidification. The rating of cooling coils for combined cooling and dehumidification is discussed later in this chapter. With volatile refrigerants there is often an appreciable pressure drop and corresponding change in evaporating temperature through the refrigerant circuit. The problem is further complicated by the fact that the refrigerant is evaporating in part of the circuit, and super heating in the remainder. In the case of volatile refrigerants, a cooling coil is tested and rated in conjunction with a specific distributing and liquid Air Heating and Cooling Coils 841 metering device, and the capacities are stated for a given superheat con dition of leaving vapor. . The design and surface arrangement of the coil include such items as materials, type, thickness, height, and spacing of the fins, and the ratio of this surface to that of the tube, the use of the staggered or in-line tube arrangement, and provisions to increase the air turbulence such as the use of corrugated as against flat fins. Staggered tubes increase the total heat transfer, as against the in-line arrangement, and corrugated fins may be more effective than flat. This design and surface arrangement has a large effect on the air film heat transfer resistance. The velocity of the air usually considered is the coil face velocity. This bears a varied relation to the actual velocity over the surface, depending upon the individual coil design. As long as a fixed design of coil is under con sideration face velocities may be used, but they may be unsatisfactory in comparing different designs, as it is the actual surface velocity that is signifi cant. The air volume is often based on standard air at 70 F and a baro metric pressure of 29.92 in. Hg. At the same mass air velocity, varying performance can be obtained depending upon the turbulence of the air flow into the coil, and upon the uniformity of distribution of air over the coil face. The latter is very im portant in obtaining reliable test ratings, and in realizing rated performance in practical installations. The resistance through the coils will assist in distributing the air properly, but where the inlet duct connections are brought in at sharp angles to the coil face, the effect is frequently bad and there may even be reverse air currents through a portion of the coils. This reduces the capacity, but can be avoided by proper layout or by the use of vanes or baffles. Heat transfer information on plain pipe coils has been developed and verified through many tests. In the case of finned coils, the heat transfer from the cooling or heating medium to the air stream is dependent on so many factors that reliable rating and performance information for any de sign of coil must be based upon actual tests of the specific coil. Mathe matical comparisons of different designs of coils on a square foot of surface and face area basis may be misleading. The selection of finned coils should be made from curves or tables of coil performance prepared from a series of adequate and reliable tests. There are cases in which the engineer must extend available data or design for a single unique installation. For such purposes the following coil calculations will be useful. PERFORMANCE OF HEATING AND DRY COOLING COILS The performance of heating and dry cooling coils depends in general upon: . 1. The overall coefficient of heat transfer from the fluid within the coil to the air it heats or cools. 2. The mean temperature difference between the fluid within the coil and the air flowing over the coil. 3. The physical dimensions of the coil. Thus, for any one definite operating condition, the heating or cooling capacity of a given coil is expressed by the following basic formula: where qt = U X (Aim) X A X N (1) qt -- total heat transfer the coil, Btu per (hour) (square foot of coil face area). 842 CHAPTER 36 1956 Guide V = overall coefficient of heat transfer, Btu per (hour) (square foot of external coil surface) (Fahrenheit degree temperature difference between the fluid within the coil and the air flowing over the coil). = mean temperature difference, Fahrenheit, degrees,-between the fluid within the coil and the air passing over it. (This is commonly taken as the loga rithmic mean temperature difference). A = external surface area of the given coil, square feet per (square foot of coil face area) (row of coil depth).. N = number of rows of coil depth. Overall Coefficient of Heat Transfer . While the overall coefficients of heat transfer for plain pipe coils have b.een defined by numerous tests within close limits, the verification of a plain coil design by a series of tests is an accepted commercial practice. The overall coefficients of heat transfer for finned coils should always be obtained from tests. The data from a series of tests may be used for pur poses of extending coil data beyond test range but such data should later be verified by test. Considering any coil, whether of bare pipe or of finned type, the overall heat transfer coefficient for a given size and design of coil can always be considered as a combined effect of three individual heat transfer coef ficients, namely: 1. The film coefficient of heat transfer between air and the external surface of the coil, usually given in Btu per (hour) (square foot external surface) (Fahrenheit, degree mean temperature difference). 2. The conductivity of the coil material---tube wall, fins, ribs, etc., usually given in Btu per (hour) (square foot of surface) (Fahrenheit degree per inch). 3. The film coefficient of heat transfer between the internal surface of the coil and the fluid flowing within the coil, usually given in Btu per (hour) (square foot internal surface) (Fahrenheit degree mean temperature difference). These three individual coefficients acting in series result in an overall coefficient of heat transfer in accordance with the basic laws given in Chap ters 5 and 9. For a bare pipe coil the overall coefficient of heat transfer, whether for heating or for cooling (without dehumidification), can be ex pressed by a simplified basic formula as follows: ELI f, + k+fo (2) where U = overall coefficient of heat transfer, Btu per (hour) (square foot external surface) (Fahrenheit degree mean temperature difference between air and fluid within the coil). /, = film coefficient of heat transfer between the internal surface of the coil and the fluid flowing within the coil, Btu per (hour) (square foot internal sur face) (Fahrenheit degree mean temperature difference between that surface and the average fluid temperature). /o = film coefficient of heat transfer between air and the external surface of the coil, Btu per (hour) (square foot external surface) (Fahrenheit degree mean temperature difference between the mass of air and the external surface). k p conductivity of material from which the bare pipe is constructed, Btu per (hour) (square foot) (Fahrenheit degree per inch thickness). Air Heating and Cooling Coils 843 L -- thickness of tube wall inches. B = ratio between external and internal surface of the bare tube, usually vary ing from 1.03 to 1.15 for the tube used in typical heating or cooling coils. This ratio R is inserted in the formula in order to place internal fluid co efficient of heat transfer on the basis of external surface. Frequently, when pipe or tube walls are thin and of material having, high conductivity (as is the case in construction of typical heating and cooling coils) the term L/ic in Equation 2 becomes negligible and is gener ally disregarded. (The effect of the term L/k in typical bare pipe heating or cooling coils seldom exceeds 1 to 2 percent of the overall coefficient). Thus, in its simplest form, for bare pipe: , i /> h (3) For finned coils the formula'" for the overall coefficient of heat transfer an be conveniently written: /i+n/. *n which the term y, called the fin efficiency, is introduced to allow for the resistance to heat flow encountered in the fins. The term B, in this case, is the ratio of total external surface to internal surface. For typical designs of finned coils for heating or cooling, this ratio varies from 10 to 30. Term R is again introduced to place the internal surface coefficient of heat transfer on a basis of external surface. The performances of all heating and dry cooling coils are influenced by these same factors. But, when cooling coils operate wet or act as dehumidifying coils, the performance cannot be predicted on the basis of overall coefficients. PERFORMANCE OF DEHUMIDIFYING COILS When the dew point of the air leaving a cooling coil is lower than the dew point of the air entering the coil, some moisture removal has been ac complished: A coil that normally accomplishes (or is designed to accom plish) moisture removal in addition to sensible heat cooling is termed a dehumidifying coil. In most air conditioning processes, the air may be considered as a mix ture of water, vapor and the dry components. Both dry components and the water vapor enter an air conditioning coil at the same dry-bulb tem perature; both the dry components and the water vapor lose sensible heat during the contact with the first portion of the cooling coil in the same manner as in a dry cooling coil. As the dry-bulb temperature of the mix ture approaches the dew point of the water vapor components, moisture removal starts. The psychrometric path of air through a cooling coil is generally agreed. to follow a path similar to that shown in Fig. 12. When the dry-bulb _ * Rational Development and Rating of Extended Air Cooling Surface, by H. B. Pownall (Refrigerating Engineering, October, 1935, p. 211). 844 CHAPTER 36 1956 Guide temperature of the air mixture in the coil falls below the entering dew point temperature, moisture removal proceeds. The indications are that the lower the leaving dry-bulb temperature below the entering dew-point temperature, the l^ss will be the difference between the leaving dry-bulb temperature and the leaving dew-point temperature. The first portion of a cooling coil (in the direction of air flow) may func tion in the same manner as a dry cooling coil. Where the moisture removal starts, the cooling surfaces also continue the removal of sensible heat, thereby carrying the load due to both. As saturation is approached in the cooling coil, each degree of sensible cooling is approximately matched by a Air Heating and Cooling Coils 845 impose a test on the distributor to provide equal distribution and on the control to modulate without hunting at the lower capacities. The higher capacities result in a greater pressure drop through the coil system and a test of the maximum feeding capacity of the flow control device at various head pressures. Most coil manufacturers have their own methods of producing perform ance rating tables from a suitable number of coil performance tests. Sev eral such methods have been reported in the literature of the industry. A standard titled Standard Methods of Testing and Rating Forced-Circu lation Air-Cooling and Air-Heating Coils has been completed by the Heating arid Cooling Coil Manufacturers' Association and the Air-Conditioning and Refrigeration Institute. Fig. 12. Performance of Dehumidifying Coil corresponding degree of dew point decrease. However, while the sensible heat removal from the dry air remains approximately constant per degree change, the amount of latent heat removal per degree of dew point change varies considerably because moisture content varies widely at different temperatures. For example, the following tabulation compares the amount of moisture removal involved in a reduction of one degree of dew point from 60 to 59 F with the removal from 50 to 49 F: Dew Point IF. X 10" lb/(lb) Dew Point Wb x 10> Ib/(lb) 60 11.080 50 7.658 59 10.690 49 7.374 , Difference 0.390 Difference 0.284 The above values are given in Table 2, Chapter 3. When cooling coils act as dehumidifying coils, the performance can be predicted accurately only from tests at a sufficient number of points to establish the definite performance characteristics of the coil under varying conditions of loading and of entering air. Dehumidifying coils employing volatile refrigerants are generally rated in conjunction with specific re frigerant distributing and flow control equipment. The combination of the coil with its refrigerant control equipment (such as distributor and expansion valve, and capillary tube or float valve) must be tested at both the higher and lower capacities of its rated range. The lower capacities Fig. 13. Psychhometric Arrangement of Cooling Coil in Central ' System DETERMINING REFRIGERATION LOAD The following determination of the refrigeration load shows a division of the true sensible and latent heat loss of the air, which is accurate within the limitations of the data. These divisions will not correspond to load de termination obtained from approximate factors or constants. The total refrigeration load qt of a cooling and dehumidifying coil (or air washer) is indicated on Fig. 13 and consists of the following components: 1. The sensible heat q. removed from the dry air and moisture in cooling from entering temperature h to leaving temperature U . 2. The latent heat qc removed to condense the moisture at the dew-point tempera ture U of the entering air. 3. The heat of subcooling g,, removed from the condensate in cooling it from the condensing temperature << to the leaving condensate temperature U Items 1, 2, and 3.may be related by qt5t = g. + + ?w (5) If only the total heat value is desired, it may be computed by g, = (Ai - As) - (tti - where hi and hi = enthalpy at points 1 and 2 respectively. (6) . 846 CHAPTER 36 -V ' ~ 1956 Guide W] and Wt -- humidity ratio at points 1 and 2 respectively. hy,% = enthalpy of saturated liquid at the final temperature, Is . If a breakdown into latent and sensible heat components is desired, the following relations may be used: The latent heat may be found from ' . = OP, - WMfcr,. G) where h!e, = enthalpy at the condensing temperature, t, . The sensible heat may be shown to be <?a + ~ {hi -- 5l) -r (Wj -- Ws)5g4 + (Wi -- W l) (5w4 hw,) (8) where 5,4 = enthalpy at the condensing temperature, U 5,, = enthalpy of saturated liquid at condensing temperature, U . The last term in Equation 8 is the heat of subcooling the condensate from the condensing temperature t, to its final temperature t3. Then, qw = (Wi - IF,) (5,,, - Ks) (9) All values for solving the foregoing equations may be found on the ASHAE Psychrometric Chart and Tables 2 and 3 of Chapter 3. Example 1: Ait enters a coil at 90 F dry-blilb, 75 F wet-bulb; it leaves at 61 F dry-bulb, 58 F wet-bulb; leaving water is assumed to leave at a temperature between the leaving air dew point and coil surface temperature of 54 F. Find the total, la tent, and sensible cooling loads on the coil. Solution: From the ASHAE Psychrometric Chart, find the following: hi = 38.42 Btu per lb of dry air. hi = 25.10 Bfcu per lb of dry air. Wi = 0.01525 lb per lb of dry air. Wi = 0.00960 lb per lb of dry air. (4 = 69 F wet-bulb of entering air. From Table 3, find: 5.4 = 37.11 Btu per lb. A.s -- 22.12 Btu per lb. 5,,4 -- 1054.27 Btu per lb. 5,4 = 1091.34 Btu per lb. The total heat from Equation 6 is o, = (38.42 - 25 10) - (0.01525 - 0.00960) X 22.12 = 13.32 - (0.00565 X 22.12) y = 13.32 - 0.12 = 13.20 Btu per lb dry air. The latent heat from Equation 7 is qc = 0.00565 X 1054.27 = 5.96 Btu per lb of dry air. The sensible heal by difference; is <7. 4- q* = <7t - <7. = 13.20 --`5.96 = 7.24 Btu per lb of dry air. Or the sensible heat may be computed from Equation 8 as p, + bw = (38.42 - 25.10) - (0.00565 X 1091.34) + 0.00565 (37.11 - 22.12) = 13 32 - 6.16 + 0.00565 X 14.99 = 13.32 -- 6.16 + 0.08 -- 7.24 Btu per lb of dry air. The sub-cooling of the condensate as a part of the sensible heat is indi cated by the last term of the equation, 0.08 Btu per lb of dry air. CHAPTER 37 REFRIGERATION Refrigeration Theory: Definitions and Basic Concepts, Refrigerants, Vapor Compression Refrigeration Cycles, Clearance and Volumetric Efficiency, Complex Refrigeration Cycles, Air Cycle, Steam Jet, Absorption and Ice Systems, Heat Pump; Basic Refrigeration Equipment: Compression Machines, Condensers, Evaporators and Coolers; Refrigeration Controls, Piping and Accessories; Equipment Characteristics and Selection WITH the increasing use of all-year comfort air conditioning instal lations, the importance of refrigeration to the air conditioning engineer has been greatly magnified. The details of equipment operation, mainte nance and design remain problems for the refrigeration engineer, but the air conditioning engineer does retain a responsibility to the customer which requires on his part some knowledge of the different refrigeration cycles and the relative merits of each. In order to assist in meeting this need, the present chapter has been divided into four parts, the first covering the fundamental technical relationships which govern the selection and analysis of an operating cycle, the next two presenting brief discussions of basic refrigerating equipment and auxiliaries, and the last, information on selec tion criteria. REFRIGERATION THEORY Definitions and Basic Concepts The ton of refrigeration is a quantity unit which originated in the days when harvested ice was the principal source of summer cooling. By defi nition the ton is the cooling effect realized when one ton of 32 F ice melts to water at 32 F; since the latent heat of fusion of ice is 144 Btu per pound, the ton represents a unit cooling effect of 144 X 2,000 = 288,000 Btu. In common practice the ton is usually considered a rate (rather than quantity) unit, and is taken as 288,000 Btu per day (24 hours), or 12,000 Btu per hour, or 200 Btu per minute. Thus for air conditioning calculations, the size of the requisite refrigeration machine, expressed in tons, can be obtained by dividing the heat gain of the structure, expressed in Btu per hour, by 12,000. In equation form: . where Hi = (Btu per hour heat gain) + 12,000 (1) Ht = load in tons. The working substance, or refrigerant, is the fluid which carries heat through the refrigeration cycle from the evaporator, where heat enters the refrigerant, to the condenser where the heat is discharged to some cooling medium. The great majority of modern refrigeration systems use a liquefi able vapor as the working substance. By altering the pressure of the refrigerant its boiling temperature is changed, allowing the material to boil in the evaporator at a temperature sufficiently lower than that of the con ditioned space, to insure maintenance of an effective heat transfer rate from 847 848 CHAPTER 37 1956 Guide the space (or in some cases from a secondary cooling fluid such as brine or cold water) to the refrigerant. The vapor formed in the-evaporator is then raised in pressure (by a compressor, oi by the absorber-generator com bination of the absorption system) until its new boiling temperature exceeds the temperature of the available cooling medium. Under these conditions, heat transfer is established from the refrigerant vapor to the cooling medium with resultant condensation of the refrigerant. When condensed, thehighpressure liquid refrigerant is reduced in pressure and again allowed to boil in the evaporator. In order to permit evaluation of the effectiveness with which any given cycle operates, some term is desirable which would be comparable to the efficiency that is used for heat engines. In refrigeration the desired effect is heat extraction, and the cost of achieving this extraction is the amount of energy which must be supplied as shaft work. Thus the ratio of refrig erating effect to the heat equivalent of the compressor work is used as a measure of effectiveness, and is defined as the-coefficient of performance. If the desired effect is the rejection of heat through the condenser instead of heat extraction through the evaporator, the refrigeration system is then termed a heat pump. In this case the coefficient of performance is the ratio of the heat rejected from the condenser to the heat equivalent of the compressor work. The coefficient of performance for the heat pump is. greater than that for a system operating as a refrigerating machine, because all mechanical shaft work required to operate the compressor is dissipated as useful heat through the condenser. The Carnot cycle, an ideal, thermodynamically reversible cycle consisting of an adiabatic expansion and an isothermal expansion, followed by an adiabatic compression and an isothermal compression to form a closed cycle, may be shown to be a measure of the maximum possible conversion of heat energy into mechanical energy. In its reversed form it is a measure of the maximum performance possible for any refrigeration cycle operating either as a refrigerator or as a heat pump. Although it cannot be applied in an actual machine because of the impossibility of obtaining complete reversi bility, it is, nevertheless, extremely valuable as a criterion of inherent limitations. The coefficient of performance (CP) of a reversed Carnot cycle system operating as a refrigeration system is (OP)-^ where T, = evaporator temperature, Fahrenheit tiegrees, absolute. Tc = condenser temperature, Fahrenheit degrees, absolute. With the ideal Carnot cycle operating as a heat pump, the coefficient of performance is (CP) = (3) The Carnot cycle coefficient of performance for both a refrigerating machine and a heat pump increases as the spread between the evaporator and the condenser temperatures decreases. In general, the same is true for an actual system operating as either a refrigerating machine or a heat pump. Refrigeration 849 Refrigerants A desirable refrigerant should possess chemical, physical, and thermo dynamic properties which permit its efficient application in refrigerating systems. In addition, when the volume of the charge is large, there should be little or no danger to health or to property in case of its escape. Thermodynamically, a material for use as a refrigerant should have a large latent heat of vaporization since it is this heat quantity--subject to minor variations--which constitutes the working effectiveness of the refrig erant. Further, since the work required to compress a vapor increases rapidly with the pressure ratio, the thermodynamic characteristics of the fluid should be such that the required low-to-high temperature range can be achieved with only a moderate change in ratio. A further consideration, from the standpoint of practical operating effectiveness, is that the suction pressure should not be below atmospheric (to prevent leakage of air into the refrigerant lines) nor should the condenser pressure be excessively high (to prevent need for extra-heavy construction). The specific volumespecific enthalpy relationship is also important because some materials would have such low density, when in vapor form, that impractical com pressor displacements would be needed to handle the suction vapor. Properties of refrigerants are usually given either in tabular or graphic form. In contrast to the temperature-entropy plotting which is used almost exclusively in steam-power work, refrigeration problems are usually referred to a pressure-enthalpy chart. The advantage of pressure-enthalpy plotting is that linear distances on the chart correspond to energy gains or losses, and the two types of processes, constant-pressure and constant-en thalpy, which occur most frequently in refrigeration cycles, can both be represented by straight vertical or horizontal lines. Figs. 1 and 2 present pressure enthalpy charts for dichlorodifluoromethane, CCljFj, and monochlorodifluoromethane, CHClFs, respectively. Although tabular ar rangements of refrigerant properties require interpolation between values, they have the advantage of an accuracy greater than that obtainable from a chart. Tables 1, 2, and 3 give the thermodynamic properties of three of the more common refrigerants used in air conditioning installations: dichlorodifluoromethane, monochlorodifluoromethane and monofluorotrichloromethane, CC13F, the first two of these are commonly used in reciprocating compressors; the last refrigerant is used in centrifugal machines. Referring to Table 1, the first column gives the range of saturation tem peratures likely to occur in practice. The second column gives the satura tion pressure expressed in pounds per square inch absolute corresponding to a given temperature, while the next six columns give the three funda mental specific properties, volume, enthalpy, and entropy, of the saturated liquid and saturated vapor, respectively. The last four columns give values of enthalpy and entropy for gases with 25 deg and with 50 deg of superheat; note particularly that the column heading 50 F superheat means, not that the gas is at a temperature of 50 F, but that its temperature exceeds by 50 deg the saturation temperature corresponding to its actual pressure. Thus, CC12F2 vapor at 38.0 psig and 91 F possesses 50 deg of superheat, since its saturation temperature corresponding to 52.7 psia is 41 F. The tabular arrangements of refrigerant properties are literally for satu rated or superheated materials only. In many cases, however, the engineer must work with sub-cooled liquids. With an accuracy sufficient for all practical purposes, the specific volume and the enthalpy of any sub-cooled 850 CHAPTER 37 1956 Guide refrigerant can be taken as equal to the values read from the tables for a saturated liquid at the same temperature. Thus, if CC12F2 at 121 psia and 40 F is passing through a pipe, its volume and enthalpy can be determined from Table 1 as 0.0116 cu ft per pound and 17.0 Btu per pound. Frequently it is necessary to determine the properties of a wet vapor or of a mixture of liquid with some added vapor, such as is found at discharge from an expansion valve. This can be done from the tables by noting that the specific enthalpy of the mixture must be equal to that of the saturated liquid, plus a fraction of the latent heat of vaporization equal to the fraction Refrigeration 851 (CCUF,)Table 1. Phqpebties or Dichlorodifltjobomethane Sat. Temp. P . Abs. Press. VOLUME liquid Vapor- Enthalpt and Entbopt Taken From --40 F . Enthalpy . Entropy -'25 F Superheat 50 F Superheat. liquid Vapor Liquid Vapor , EatropyEutludpy Entropy 0 2 4 5 .6 8 10 12 14 16 18 20 22 24 26 ,28 30 32 34 36 38 39 40 41. 42 44 46 48 SO 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100 102 104 106 108 110 112 114* 116 118 120 122 124 126 128 130 132 134 136 138 140 23.87 24.89 25.96 26.51 27.05 0.0110 0.0110 0.0111 0.0111 . 0.0111- 28.18 29.35 30.56 31.80 33.08 CjOllt 0.0112 0.0112 0.0112 0.0112. 34.40 35.75 37.15 38.58 40.07 0.0il3 0.0113 0.0113 0.0113 0.0114 41.59 43.16 44.77 46.42 48.13 0.0114 0.0115 0.0115 0.0115 0.0116 49.88 50.78 51.68 52.70 53.51 0.0116 0.0116 "0.0116 0.0116 0.0116 55.40 57.35 5945 6149 63.49 65-63 67.84 70.10 72.41 74.77 0.0117 0.0117 0.0117 0.0118 0.0118 0.0118 0.0119 0.0119 0.0119 * 0.0120 77.20 79.67 82.24 8442 87.50 0.0120 0.0120 0.0121 0.0121 0.0121 90.20 93.00 9545 98.76 101.70 0.0122 0.0122 0.0123 0.0123 ' 0.0123 104.8 107.9 111.1 1144 117.7 0.0124 0.0124 0.0124 0.012S 0.0125 121.0 1244 125.0 131.6 1354 0.0126 0.0126 0.0126 0.0127 04127 139.0 1424 146.8 150.7 154.8 0.012S 0.0128 0.0129 0.0129 0.0130 158.9 163.1 167.4 171.8 176.2 0.0130 0.0131 0.0131 0.0132 0.0132 1804 185.4 190.1 194.9 1994 0.0133 0.0133 0.0134 0.0134 0.0135 2044 209.9 215.0 220.2 0.0135 0.0136 0.0137 0.0133 1.637 1474 1414 - 1.485 1.457 8.25 8.67 9.10 942 943 7841 78.44 78.67 78.79. 78.90 0.01869 0.01961 0.02052 0.02097 0.02143 0.17091 0.17075 0.17060 0.17052 0.17045 81.71 0.17829 81.94 - 0.17812 82.17 0.17795 82.29 0.17786 82.41 0.17778 85.26 8531 ' 85.76 8539 86.01 0.18547. 0.18529 0.18511 0.18502 0.18494' 1.403 1451 1401 1.253 1.207 . 9.96 1049 10.82 11.26 11.70 79.13 7946 79.59 7942 80.05 0.02235 0.02328 0.Q2419 0.02510 0.02601 0.17030 0.17015 0.17001 0.16987 0.16974 82.66 82.90 83.14 83.38 ,83.61 0.17763 0.17747 0.17733 0.17720 0.17706 86.26 8631 86.76 87.01 ; 97-26 0.18477' 0.18460 0.18444 0.18429! 0,18413. 1.163 1.121 1.081 1.043' 1.007 12.12 1245 13.00 13.44 13.88. 8047 80.49 80.72 - 80.95 81.17/ 0.02692 0.02783 0.02873 0.02963 0.03053 0.16961 0.16949 0.16938 0.16926 0.16913 83AS, 84.09 84.32 84.55 84.79 0.17693 0.17679 0.17666 0.17652 0.17639 87At .87.76 88.00 88.24 88.49 0.18397 0.18382 0.18369' 0.18355 0.18342 0.973 0.939 0.908 0477 0448 1442 14.76 15.21 15.65 1610 81.39 8141 81.83 82.05 8247 0.03143 0.03233 0.03323 0.03413 0.03502 0.16900 0.16887 0.16876 0.16865 0.16854 85.02 85.2S 85.48 85.71 85.95 0.17625 0.17612 ai7600 0.17589 0.17577 88.73 88.97 89.21 89.45 ' 8938 0.18328 0.18315 ai8303 0.18291 0.18280 0419 0406 0.792 0.779 0.767 . 1645 16.77 17.00 1743 17.46 8249 82.60 82.71 8242 82.93 0.03591 0.03635 0.03680 0.03725 0.03770 0.16843 0.16838 0.16833 0.16828 0.16823 86.18 86.29 86.41 86.52 86.64. 0.17566 0.17560 0.17554 0.17549 0.17544 89.92 . 90.04 90.16 . 9038 90.40 0.18268 0.18262 0.18256 0.18251 0.18245 0.742 0.718 0.695 0.673 0.652 17.91 1846 1842 1947 19.72 43.15 83.36 8347 83.78 83.99 0.03859 0.03948 0.04037 0.04126 0.04215 0.16813 0.16803 0.16794 0.16785 0.16776 86.86 87.09 87:31 87-54 87.76 0.17534 0.17525 0.17515 017505 0.17496 90.65 90.89 . 91.14 91-38 . 91,61 6.18235* 0.18224 0.18214 0.18203 ai8193 0.632 0.612 0.593 0475 0457 20.18 20.64 21.11 21.57 22.03 84.20 84.41 84.62 8442 85.02 0.04304 004392 0.04480 0.04568 0.04657 0.16767 0.16758 0.16749 0.16741 0.16733 87.98 83.20 .88.42 88.64 88.86 0.17486 0.17477 0.17467 0.17458 0.17450 91.83 92.06 92.28 9231 92.74 0.18184/ 0.18174 0.18165 0.18155 0.18147 0.540 0424 0408 0.493 0.479 22.49 22.95 23.42 23.90 2447 85.22 85.42 85.62 8542 86.02 0.04745 0.04833 0.04921 0.05009 0.05097 0.16725 0.16717 0.16709 0.16701 0.16693 89.07 89.29 89-50 89.72 89.93 0.17442 0.17433 0.17425 0.17417 0.17409 92.97 9330 93.43 93.66 93.99 0.18139. ai8130 ai8122 ai8H4 0.18106 0.464 0.451 0.438 0.425 0.413 24.84 25.32 25.80 2648 26.76 8642 86.42 86.61 86.80 86.99 0.05185 0.05272 0.05359 0.05446 0.05534 0.16685 0.16677 0.16669 0.16662 0.16655 90.14 90 36 90.57 90.78 90.98 0.17402 0.17394 0.17387 0.17379 0.17372 94.12 9434 94-57 9430 95.01 0.18098 0.18091 0.18083 0.18075 0.18068 0.401 0.389 0.378 0468 0.357 2744 27.72 2841 28.70 29.19 87.18 8747 8746 87.74 87.92 0.0562! 0.05708 0.05795 0.03882 0.05969 0.16648 0.16640 0.16632 0.16624 0.16616 91.18 9137 91-57 91.77 9L97 6.17365 0.17358 0.17351 0.17344 0.17337 95.22 95.44 95.65 9536 96.07 0.18061 0.18054 0.18047 ai8040 0.18033 0.347 0438 0428 0419 0410 29.68 30.18 30.67 31.16 31.65 88.10 88.28 88.45 8842 88.79 0.06056 0.06143 0.06230 0.06316 0.06403 0.16608 0.16600 0.16592 0.16584 0.16576 92.16 9246 9255 92.75 92.93 0.17330 0.17322 0.1731S 0.17308 0.17301 9638 9630 96.71 96.92 97.12 0.18026 0.18018. aison 0.18004 0.17998 0402 0.293 0.285 0.277 0.269 32.15 32.65 33.15 33.65 34.15 88.95 89.11 8947 89.43 89.58 0,06490 0.06577 0.06663 0.06749 0.06836 0.16568 0.16560 0.16551 0.16542 0.16533 93.11 9350 93.48 93.66 9342 0.17294 0.17288 0.17281 0.17274 0.17266 9732 9733 97.73 97.93 98.11 0.17993 0.17987 0.17982 0.17976 0.17969 0.262 0454 0.247 0.240 01233 34.65 35.15 35.65 36.16 36.66 89.73 8947 90.01 90.15 90.28 0.06922 0.07008 0.07094 0.07180 0.07266 0.16524 0.1651S 0.16505 0.16495 0.16484 93.98 94.15 9451 94.47 94.63 0.17258 0.17249 0.17241 0.17233 0.17224 98.29 98.48 98.66 98.84 99.0! 0.17961 0.17954 0.17946 0.17939 0.17931 0.227 0.220 0.214 0.203 0.202 37.16 37.67 38.18 38.69 39.19 90.40 9042 90.64 9C.76 9046 0.073S2 0.07437 0.07522 0.07607 0.07691 0.16473 0.16462 0.164SO 0.16438 0.16425 94.78 94.94 95.09 95.25 95.41 0.17215 0.17206 0.17196 0.17186 0.17176 99.18 9935 9933 99.70 9937 0.17922 0.17914 0.17906 0.17897 0.17889 0.196 0.191 0.185 0.180 39.70 40.21 40.72 4144 90.96 91.06 91.15 91.24 0.07775 0.07858 0.07941 0.08024 0.16411 0.16396 0.16380 0.16363 95.56 95.72 9547 96.03 C.17166 0.17156 0.17145 0.17134 100.04 100.22 10039 10036 0.17881 0.17873 0.17864 CU7856 852 CHAPTER 37 H3N1 2UVnOS Hid SGNHOd - TtfrtTSTtM 3J/r*OSS* 1956 Guide Pm O ao . a z aaaaCaaO} Ph o (S of refrigerant which is present in vapor form. Consider, for example, CCI2F2 with a quality (the percent in vapor form) of 30 percent; the en thalpy of this material would be equal to where hm ftt 0.30 (Av -- hi) (4) hm = specific enthalpy of the mixture. hi = specific enthalpy of the liquid. A. = specific enthalpy of the saturated vapor. Temperature--F ; Volum e-- Cu F t per L b ; E n tro p y--B tu p e r(L b )(F deg). Refrigeration Table 2. Properties of Monochlorodifluoromethane (CHC1F,) 853 Sat Teue Ads Pres Sq In Volume Enthalpy and Entropy Taken prom ~4o p Enthalpy 50 Deg Superheat 100 Dec Superheat Liquid iVapo Liquic 1 Vapoi Llquit Vapoi Enthal] rvy tropy Eotbal] V 9 Edtropy 0 38.7C 0.01192 1.373 10.6C 105.0S 0.024() 0.2293 112.3s 0.244(i 120.0C 0.2590 2 4 5 6 8 111420 16 18 4420..1443 00..00111109S5 .4433..9012 00..0011220010 45.74 0.01205 5544553791.....7665696389 . 00..0011221018 0.01215 00..0011222128 11..237200 11..224216 1.175 1.130 0111....9000704829881 n.n 111112...792C33> 12.76 111000555...452564 105.66 105.87 000...O00222665S5 00..0022784* 000...22222288839a 00..22227860 112.6? 111111232...890C37 113.31 0.2442 000...222444333S64 0.2430 111112222200100.....26706C5542 0.2586 0000....2222555578771279 1111154433.....4392846092 1110006661..062089 110066..7912 00000.....000003323334901G1679 0.2272 0000....2222222266667403 111111114433....02572559 114.48 00000.....22222444441221160284 111222111...835266 112222.,3083 0.2568 0000....2222555556662406 20 57.98 0.01225 22 2264 28 66664702....94264305 0000....00001111222223339269 3333348260 77675729....29591733 80.81 -.0000....00001111222245547403 0.01258 4420 444486 8998892663.....7816748092 0.01262 000...000111222767460 0.01278 50 52 555864 11109009926....84820 113.5 . 0.01282 000...000111222089460 0.01299 6620 64 111221417...920 66 128.9 68 133.0 00000.....0000011111333332100102376 7720 7746 78 137.2 111155445051....4095 0.01325 0000....00001111333343334490 80 8842 159.7 116694..45 86 88 117749..56 0.01349 00..0011335538 00..0011336638 9999948620 221110099861054.....81268 00000.....0000011111333338997746094 110042 110088 221182..66 223204..76 237.0 00000.....0000011111444442120046082 112 111146 118 2:222>>4467539306.....49436 00..0011443430 00..0011445447 0.01461 77.3 0.01469 00000.....88989310739030680279 15.98 111767...660126 18.17 107.13 111100007777....37953333 0.0352 000...000333677458 0.0398 0.2253 00..22224496 0.2242 0.2239 114.71 111154..1947 111155..6420 0.2406 00..22430928 00..22339915 111122223232....38514590 123.60 0000....2222555534447840 0.2533 0.7816 0000....6777720598341323 1198..3724 2109..4990 21.09 111100008888....73511323 108.90 00..00442019 00..00443435 0.0457 0000....2222222232232855 0.2222 111111116656....25809427 116.74 0000....2222333378886307 Q.2373 111122224443....51389055 124.84 00.22552259 0.2622 00..22551185 0.6569 000...566931232296 0.5726 2222242231.....1295719000 110099..0297 110099..4635 109.80 0.0469 0000....0000545419086351 000...222222111158 00..22220058 111111111177776,....8461912086 00000.....22222333335656663969 111122225555....58306028 126.04 0000....2222555500101148 0.2497 00000.....54555083151458349547 24.73 .22226755....52392845 111111100009....14394780. 110.63 0000....0000555565424208 0.0576 0.2201 002.22119984 0.2191 0.2188 111111311188888.....6842022222 00000.....22222333334455403307 *111112222276666.....1975296307 00..22449941 000...222444888148 r 00000.....44444125462640994635 2287..4863 322099...307592 111111010...907838 111111..3252 00000.....00000666652301848028. 00000.....22222111118777812585 111199.2011 111111999...754790 00..22333347 00..22333217 0.2324 127.42 112277..8675 112288..3120 000...222444777528 0.2469 0.2466 0.4000 0000....3333576825376485 33332201....29969495 33.61 111.49 111111112111....07861583 00000.....00000666669687461438 0000....2222111165662885 0.2155 111212090...391265 112200..6570 0.2321 0000....2222333301119528 111222888...957476 112299..4109 00000.....22222444445556627350 0.3417 00..33321132 00..33101139 34.27 33336645....92964820 111111112222....42317463 112.57 0.0708 000...000777423402 0.0756 000...222211454418 00..22114307 111112222211110.....3105842850 0000....2222323309003760 0.2294 111112332390090.....6248013322 00..22444496 00..2244441S 0.2438 00000.....22222586799475241258 37.61 43330988....36922578 111122..7676 111122..9835 113.00 00000.....00000887770198635208 00000.....22222111112123329630 111222111...986726 112222..1226 00000.....22222222227889892518 113300..8633 111333111...420233 00..22443325 00..22442297 0.2424 0.2517 009...222343047130 3.2233 4444432201.....6939668285, 111111333...110266 111133..2240 0009....0000888850231279 1.0874 00..22113115 00..22110047 0.2100 122.40 111122222222....97562396 00..22227736 0.2270 00..22226647 111113333322111.....3169851970 0.242i 0000....2222444411111386 333...222101046473 33..1199S263 44445654....74034445 47.14 111133..2394 11111333...434826 <<((11111.....00000998982390813689 0.2096 00..22009839 00..22008815 11112222233333.....5024114806 0.2261 0000....2222222255553508 111133332232....78058135 133.22 00..22440085 <000...222443009308 .1871 47.85 13.52 C .0945 (>.2078 23,62 (X2247 J 33.39 (0.2395 Data from Kinetic Chemicals, Inc., 1945. 854 CHAPTER 37 1956 Guide Table 3. Properties of Monofloobotrichlobomethane (CCIjF) Sat.. Temp. F .. AB8. PBEdS. Lb peb Sq In. Volume . Liquid Vapor tEnthalpy and Entropy Taken From --40 F . Enthalpy Entropy 25 F Superheat 50 F Superheat Liquid Vapor Liquid Vapor En thalpy En tropy En thalpy En tropy ' 0. ,6 10 15 20 25 30 35 40 -'4550 55 60 65 70 75 80 85 90 95 100 105 2.59 2.96 3.38 3.85 4.36 4.94 0.01020 0.01024 0.01028 0.01032 0.01036 0.01040 5.57 6.27 7.03 7.88 8.79 0.01045 0.01049 0.01053 0.01057 0.01062 9.80 ' 10.90 12.10 13.40 14.80 0.01066 0.01071 0.01076 0.01081 0.01086 16.30 17.90 19.70 21.60 23.60 25.90 0.01091 0.01096 0.01101 0.01106 0.01111 0.01116 13.700 12.100 10.700 9.530 .8.490 7.580 7.81 8.819.82 10.80 11.90. 12.90 90.4 91.2 92.0 92.8 93.7 94.5 6.770 6.080 5.460 4.920 . 4.440 13.90 14.90 16.00 17.00 18.10 95.3 96.1 96.8 97.6 98.4 4.020 3.640 3.300 3.000 2.740 19.10 20.20 21.30 . 22.40 23.50 99.2 100.0 100.8 101.5 102.2 2.500 2.280 2.090 1.918 1.761 1.620 24.50 102.9 25.60 103.6 26.70 104.4 27.80 105.1 28.90 : 105.7 30.10 106.4 0.0178 0.0200 0.0222 0.0243 0.0264 0.0286 0.1975 0.1974 0.1973 0.1971 0.1970 0.1969 93.9 94.7 95.5 96.3 97.2 98.0 0.2049 0.2047 0.2045 0.2043 0.2041 0.2039 97.4 97.2 99.0 99.8 100.7 101.5 0.0307 0.0328 0.0349 0.0370 0.0391 0.1969 0.1968 0.1968 0.1967 0.1967 98.8 99.6 . 100.3 . 101.1 101.9 0.2038 0.2037 0.2036 0.2035 0.2034 102.3 103.1 103.8 104.6 105.4' 0.0412 0.0432 0.0453 0.0473 0.0493 0.1967 0.1967 0.1967 0.1967 0.1967 102.7 103.5 104.3 105.0 105.7 0.2033 0.2033 0.2032 0.2032 0.2031 106.2 107.0 107.8 108.5 109.2 0.0513 0.0533 0.0553 0.0573 0.0593 0.0613 0.1968 0.1966 0.1966 0.1966 0.1965 0.1965 106.4 107.1 107.9 108.6 109.2 109.9 0.2030 0.2029 0.2028 0.2028 0.2027 0.2026 109.9 110.6 111.4 112.1 112.7 113.4 0.2120 0.2117 0.2114 0.2111 0.2109 0.2107 0.2105 0.2103 0.2101 0.2099 0.2098 0.2097 0.2096. 0.2094 0.2093 0.2092 0.2090 0.2089 0.2088 0.2087 0.2085 0.2084 Values'of v, and i>d for use in Equation 4 can be obtained directly or by calculation from the tables of properties of refrigerants. By a reversal of this same procedure the tabular data can be used to determine the state of a mixture leaving an expansion valve. Consider a valve to which saturated liquid at pressure p, is admitted, and a mixture of saturated liquid and vapor at pressure pd is discharged. The quality of the material at discharge is then determined by making use of the fact that the expansion process is completely irreversible, is a throttling process, and hence, occurs without change in enthalpy. Thus, the enthalpy of the mix ture, hm, is e'qual to the enthalpy of the saturated liquid at the entrance state, hi,, and can therefore be read from the table. Thus, '' : `. Afi Am " Avd (1 It) (Avd -- Afd) 1 (5) or, : * . where x = (ha -- Afd)'+ (Avd -- Afd) (6) hi. = enthalpy of saturated liquid at entrance to expansion valve. Am = enthalpy of mixture. Avd = enthalpy of saturated vapor at discharge. Afd = enthalpy of liquid at discharge. x = proportion of liquid in the mixture, decimal. Vapor Compression Refrigeration Cycle Simple Cycle. The refrigerant cycle is the series of state changes (which occur in the conditioning processes) needed to restore the refrigerant to a condition in which it will possess the ability to extract heat from the space to be cooled. For all compression-type systems the cycle consists of four processes: heat gain in the evaporator; pressure rise in the compressor; Refrigeration 855 heat loss in the condenser; pressure loss in the expansion valve. The com pression process is accomplished at the expense of energy added to the compressor in the form of shaft work, and the expansion process could be carried out, if the economics of the system would permit, in an expanding engine with consequent release of energy as shaft work. In ordinary sys tems, however, the additional first cost and maintenance costs of an expand ing engine so greatly exceed the advantage resulting from the work realized, that such engines are not used, and the pressure reduction is allowed to occur irreversibly in an expansion valve. Basically, then, a refrigeration cycle consists of two heat transfer processes and two pressure change proc esses, no work entering into the heat transfer processes and--in the simple cycle--no heat transfer occurring during the pressure-change processes. The most common and least complicated type of refrigeration cycle is called the simple saturation cycle, and is shown diagrammatically in Fig. 3 and plotted upon pressure-enthalpy coordinates in Fig. 4. For this system, Low Pressure Saturated Gas Heat of Compression TAdded to Gas ----- Compressor------- High Pressure Superheated Gas 1/ . Heat Added to Refrigerant by Substance Cooled Evaporator or Cooler ml ^Expansion Valve for Reducing Pressure Condenser Cold In Heat Taken from Refrigerant by Condensing Medium Hot Out High Pressure Saturated Liquid Fig. 3. Mechanical Refrigeration System saturated vapor flows without gain or loss of heat from the evaporator to the suction of the compressor. During passage through the compressor the energy added as shaft work goes entirely to increase the enthalpy of the refrigerant, and the compression process, which is assumed to occur irreversibly and without external heat transfer, is characterized by constant entropy. Thus, the state of the superheated vapor leaving the compressor can be determined from the tables of thermodynamic properties by noting the discharge pressure and fixing, also, the entropy of the saturated vapor at entrance to the compressor. Superheated vapor from the compressor flows to the condenser where de-superheating and condensation take place. From the condenser the re frigerant flows to the expansion valve, undergoes a constant-enthalpy pres sure reduction, and returns to the evaporator where it again removes a quantity of undesired heat. When the evaporator is arranged to permit direct cooling of room air by the refrigerant, the system is said to be of the direct expansion type, while a system in which the evaporating refrigerant cools water or brine, which in turn cools the air, is said to be indirect. Although many differences exist between most actual systems and that of the simple saturation cycle, this latter is, nonetheless, of great value in that it provides an extremely simple method of rapidly achieving an approximate u UP 856 CHAPTER 37 1956 Guide analysis of probable power requirements, compressor size, etc. Further, the equations used in analysis of a simple saturation cycle form the basis of the more complex treatments required for compound refrigeration cycles. For these reasons a typical simple saturation problem will be worked in detail. 1 w Example 1: A simple saturation cycle carries a 7 ton load when operating between suction and discharge pressure of 52.7 psia and 121 psia with dichlorodifluoromethane, CCljFi, as the refrigerant. Determine: (o) the cooling effect provided by each pound of refrigerant; (5) the refrigerant circulating rate; (c) the horsepower required; (d) the quantity of heat to be dissipated from the condenser; (e) the required conden ser cooling water, in gallons per minute, if temperature rise of water passing through the condenser is 8 deg; (/) the bore and stroke of a double acting cylinder (neglecting the effect of the piston rod) if speed of compressor is 500 revolutions per minute; (g) coefficient of performance. . Solution: (a) Saturated liquid CCljFj at 121 psia leaves the condenser and enters the expansion valve. The enthalpy of this material (from Table 1) is 29.68 Btu per pound, and this must also be its enthalpy at entrance to the evaporator. Leaving the evaporator as a saturated vapor at 52.7 psia, its. enthalpy is 82.82, so the re frigerating effect must be 82.82 -- 29.68 = 53.14 Btu per pound. Fig. 4. Pressure-Enthalpy Diagram for Simple Saturation Cycle (b) The refrigerant circulating rate is equal to the total heat to be picked up in unit time, divided by the pick-up per pound of refrigerant or, W, = (7 ton X 200) -4- 53.14 = 26.3 lb per minute. (c) The horsepower required is equal to the increase irf energy of the refrigerant passing through the compressor (expressed in Btu per minute) divided by the con version factor 42.42, which is the number of Btu per minute corresponding to 1 lip,' (hp) = Wr (Ad -- ATM) + 42.42 (7) where hp = horsepower. Wr = refrigerant circulating rate in pounds per minute. hi = enthalpy of vapor at condition of discharge from compressor. h,, = enthalpy of saturated vapor entering compressor. Wt is known from (6) and Av is the enthalpy of refrigerant as it enters the com pressor in a saturated vapor state at 52.7 psia; thus = 82.82. In order to determine hi, the state of the refrigerant must first be determined at the compressor discharge. At the known suction state the entropy (from Table 1 for saturated vapor at 52.7 psia) is 0.16828 and, since the compression is assumed to occur isentroDically, it therefore follows that the discharge stage must have the same entropy at 121 psia. From the table the entropy of vapor superheated 25 deg is Refrigeration 857 0.17330, so the superheat, Ua, possessed by the actual gas discharged from this com pressor can be obtained by interpolation as; . t,d 0.16828 - 0.16608 25 " 0.17330 - 0.16608 . from which Ua = 7.6 deg. As the saturation temperature at 121 psia is 94 F the actual temperature, la, of the vapor leaving the compressor is, ta = 94 + t,,i = 94 + 7.6 = 101.6 F. By the same kind of interpolation the enthalpy of the discharged vapor can be determined from the enthalpies given for vapor superheated 25 F and for saturated vapor, (ha - 88.10) _ (0.16828 - 0.16608) . (92.16 - 88.10) ~ (0.17330 - 0.16608) from which, ha = 89.34 Btu. per pound. Then substituting in Equation 7, , (hp) = 26.3 (89.34 - 82.82) -s- 42.42 = 4.03. (<f) The rate of heat loss from the condenser, Qc, must be equal to the sum of the energies picked up by the refrigerant in the evaporator and the compressor, . Qc = 53.14 + (89.34 - 82.82) = 53.14 + 6.52 = 59.66 Btu per pound or 26.3 X 59.66 = 1569 Btu per minute. This same figure can, of course, be determined more directly by subtraction of the enthalpy of liquid leaving the condenser from the enthalpy of superheated vapor going into it, thus, Qc = 26.3 (89.34 -- 29.68) = 1569 Btu per minute. . (e) The cooling water rate (based on a gallon as 8.34 lb) is 1569 -f- (8 X 8.34) = 23.5 gpm. (ft The compressor size is fixed by the volume of gas which must be drawn into the machine per unit time. Saturated vapor at 52.7 psia has a specific volume, from Table 1, of 0.779 cu ft per pound, hence 26.3 X 0.779 = 20.49 cfm of gas must be handled. Assuming a volumetric efficiency of 90 percent, the compressor must then displace 20.49 + 0.9 = 22.8 cfm. The speed is given as 500 rpm and, as the unit is known to be double-acting, the displacement is therefore (22.8 X. 1728) -s- (2 X 500) = 39.4 cii in. If the unit were designed so that bore d and stroke were the same, - (P) -h 4 = 39.4 (g) (CP) = (h,, - h,c) + (ha - he) d = 3.69 in. = (82.82 - 29.68) + (89.34 - 82.82) = 8.17 where Au is the specific enthalpy of liquid at discharge from the condenser. The coefficient of performance of Example 1 may be compared with that of an ideal system operating on the Carnot cycle between the same tempera-. ture limits. Then Te = 501 F (which is 41 F + 460) and Tc = 554 F (which is 94 F + 460) and, ' 501 (CP) = 554 - 501 = 9.6 The actual cycle is therefore 8.17 -f- 9.6 or 85 percent.as effective as a Carnot cycle between the same temperature limits. Influence of Suction Pressure Brief consideration of the analytical procedure used in discussion of the simple saturation cycle will bring out the need for maintaining the suction pressure on any refrigeration system as high as the load will permit. As the suction pressure increases, for fixed discharge pressure, the enthalpy 858 CHAPTER 37 1956 Guide of refrigerant entering the evaporator remains unchanged, but the leaving enthalpy increases and, hence, the refrigerating effect increases. Further, compressor energy input is reduced not merely because of the greater enthalpy of the gas at suction, but also because of a reduction in the en thalpy of the superheated gas at discharge. Since the refrigerating effect is greater and the work less, it is obvious that there will be a substantial gain in the coefficient of the performance. The actual value of suction pressure on any system is obviously de termined by the required temperature which must be maintained in the conditioned space. For a direct expansion system the evaporator can be held at a temperature not much less than that of the conditioned enclosure, except in cases where lower temperatures may be needed in order to es tablish a desired ratio of dehumidifying to cooling load. When dehumidi fication requirements dictate the use of unusually low evaporator temperatures, the increased operating cost should properly be charged against the dehumidification rather than the sensible cooling. Influence of Discharge Pressure In contrast to the suction pressure, the compressor discharge pressure should be kept as low as operating conditions will allow. This pressure must be high enough to provide a saturation temperature of refrigerant within the condenser which is greater than the exit temperature of the cooling water. The discharge pressure therefore is a direct function of the temperature of the cooling fluid, and will automatically rise whenever the temperature of cooling water (or air) rises; it will also rise when the flow rate of the cooling medium is decreased. Increase in discharge pressure (for fixed suction pressure) raises the enthalpy of the gas leaving the compressor; hence, increases the work of compression. Further, as the enthalpy of saturated liquid leaving the con denser increases with pressure, the refrigerating effect must decrease. Thus the effect of such a pressure rise is to require more work per pound of refrigerant handled, and at the same time to necessitate an increase in the refrigerant flow rate. Influence of Water Jacket The preceding discussion has, in every case, assumed isentropic com pression. Where exact performance data are not available, this assumption is a desirable one since it leads to a conservatively large determination of the power required. In most actual systems, the compression process departs from isentropic due to irreversible heat transfers which occur between the vapor in the cylinder and the cylinder wall, and also because of intentional heat dissipation from the outsidfe of the cylinder walls to the surroundings, or to a cooling fluid passing through a water jacket around the cylinder. Compressor cooling is highly desirable as a method of re ducing power consumption. Influence of Superheating and Subcooling The most common departure from conditions of the simple saturation cycle is that resulting from admission of superheated vapor to the com pressor. Thermodynamically, superheat is undesirable because the en thalpy increase required to compress a vapor through a given pressure range increases with superheat. Further, superheated vapor leaving an evapo rator is usually an indication that the suction pressure is lower than Refrigeration 859 necessary. Under practical operating conditions, however, superheat is almost universally used as a means of assuring complete vaporization of the refrigerant going to the compressor. With modem compressors operating at high speed, and with relatively small clearance space, it is particularly necessary to avoid admission through the suction valves of liquid refrigerant. Another common departure of actual systems from the simple satu ration cycle occurs because of subcooling of refrigerant in the condenser. Thermodynamically, such subcooling is advantageous since it increases the refrigerating effect without affecting the unit energy requirements of the compressor. Further, it can be shown that for a fixed ratio of con denser cooling water to refrigerant circulating rate, the total compressor power requirements will be greater when operating at simple saturation than when operating with maximum sub-cooling. What is even more surprising is that condenser pressure may be lower for the sub-cooling cycle than for the saturation cycle. This condition results from the fact that. Cycle with Subcooling and Superheating . for the same capacity on a heavily loaded condenser, the refrigerant flow rate is less when there is sub-cooling. Because of the advantages attendant upon the use of sub-cooling, many methods are in use for obtaining some sub-cooling effect outside of the condenser. One common procedure is to use the cold vapor leaving the evaporator to cool the liquid flowing from condenser to expansion valve. Another somewhat unusual sub-cooling cycle allows cold refrigerant from the downstream side of the expansion valve to cool liquid refrigerant from the condenser down to the evaporator temperature. Fig. 5 shows the pressure-enthalpy diagram for a typical refrigeration cycle operating with both sub-coolirig of the refrigerant from the condenser and superheating of the refrigerant leaving the evaporator. Clearance and Volumetric Efficiency Clearance, like displacement, is a characteristic--usually fixed--of a given compressor. In some cases clearance pockets are provided which place within the operator's control the ability to alter the clearance of the machine, but most moderate size compressors are built with fixed clearance. By definition, the clearance is the percentage of the volume swept by the piston, which is represented by spaces in the end of the cylinder (including valve spaces, etc.) when the piston is at the end of its stroke. Because of the trapping of high pressure vapor in the clearance space, and its subsequent re-expansion, the suction valves of the compressor 860 CHAPTER 37 1956 Guide do not open until the piston has completed part of its stroke. Hence, the volume of fresh vapor introduced into the compressor per stroke is less than the volume swept by the piston. The ratio of actual volume of fresh gas to swept volume is, by definition, the clearance volumetric effi ciency, CVE. In equation form, (CVE) = 100 - Fejj^ - lj (8) where CVE = clearance volumetric efficiency. yc -- clearance, percent of volume swept by piston, which is contained in spaces at end of cylinder when piston is at end of stroke (clearance includes valve spaces, etc.). v. = specific volume of gas at compressor inlet, ca = specific volume of gas at compressor discharge. Values of v,, and vd can be obtained directly or by calculation from the tables of properties of refrigerants. In addition to clearance, there are several other factors which tend to reduce the volumetric efficiency. The suction gases from the evaporator are heated and expanded upon contact with the hot cylinder walls during the suction stroke. This results in a reduction of the actual charge drawn into the cylinder. Wire-drawing through the suction and discharge valves reduces the suction pressure in the cylinder below that in the evaporator, and increases the discharge pressure above that in the condenser. Leakage of gases around the pistons also decreases the volumetric efficiency. The total volumetric efficiency (TVE) includes all of these factors and is reliably obtained only by laboratory measurements. It is too difficult to predict the effects of these factors to any degree of accuracy comparable to actual tests. ' Complex Refrigeration Cycles The preceding sections have dealt only with refrigeration systems in which there is but one evaporator; compression is accomplished through but a single stage, and expansion proceeds through a single expansion valve. In large systems or in low temperature systems in which the compression ratio is high, the compression process can be carried out in stages, with the refrigerant passing through several cylinders arranged for operation in series. The thermodynamic advantage of such compound compression arises from the fact that intercoolers can be placed between the stages of compression to extract heat from the vapor, and thereby cause the overall compression process to approach more closely the ideal condition of iso thermal compression. Essentially, such intejcoolers serve the same pur pose as a cooling jacket, but with greater effectiveness because of the more satisfactory heat transfer conditions. In the simple saturation cycle the saturated liquid entering the expansion valve commences to vaporize as soon as its pressure starts to drop. The vapor produced during the expansion process has no further use, in terms of refrigerating effect, since it has already picked up its latent heat of vaporization as a result of heat which it has extracted from the unvaporized residue. Thus the instant such vapor forms, its usefulness is at an end, and to allow such material to undergo a further drop in pressure is uneconomical. With compound compression, there is at least one intermediate pressure Refrigeration 861 at which flash vapor can be extracted. In such cases several expansion valves can be utilized with all of the refrigerant from the condenser passed through a first expansion valve to the higher suction pressure, and the flash vapor then extracted and returned to the condenser through the high compression stage. The remaining refrigerant can then pass through a second expansion valve where the pressure is dropped to that corresponding to the low-pressure evaporator. The number of expansion valves is limited by the number of stages of compression. Further cycle complications may arise if more than one evaporator is to be operated with a single compressor, and particularly, if the pressures in these evaporators are to differ. The most common solution is to operate the compressor at the suction pressure of the lowest pressure evaporator, and to equip all other evaporators with back-pressure regulating valves or throttling devices between the evaporator and the compressor suction. The Air Cycle System Fundamentally, the air cycle1 is essentially the same as the vapor cycle. Compression is accomplished by a reciprocating or centrifugal compressor, and, since there is no change of phase of the refrigerant upon expansion, an air cooler replaces the condenser, and a refrigerator, the evaporator. Although some cooling would result from the expansion of the gas through an ordinary expansion valve, a much greater drop in air temperature is accomplished if the expansion is controlled to approach the isentropic by replacing the valve with an expansion engine or turbine. Furthermore, the work recovered by such an expansion engine can be utilized to supply part of the work of compression or to drive other devices. The Steam Jet System The steam jet system, under certain circumstances, is desirable for use in air conditioning.2 Steam supplies directly the power used for com pressing the refrigerant, thus eliminating the losses connected with other methods of supplying energy. As the compression ratio between the evaporator and condenser under normal circumstances is large, the mechan ical efficiency of the equipment is somewhat lower than that of the positive mechanical type compressor. The condensing water requirements are considerably greater, as both the refrigerant and the impelling steam must be condensed. The steam jet system functions on the principle that water under high vacuum will vaporize at low temperatures. Steam jet boosters or com pressors of the type commonly used in power plants for various processes, will produce the necessary low absolute pressure to cause evaporation of the water. A diagrammatic representation of a typical steam ejector water cooling system is shown in Fig. 6. The figures correspond to an average repre sentative system. The water to be cooled enters the evaporator and is cooled to a temperature corresponding to the vacuum maintained. Be cause of the high vacuum, a small amount of the water introduced in the evaporator is flashed into steam. As this requires heat, and the only source of heat is the rest of the water in the evaporator tank, this other water is almost instantly cooled to a temperature corresponding to the boiling point determined by the vacuum maintained. The amount of water flashed into steam is a small percentage, of the total water circulated through the evaporator, amounting to approximately 11 lb per (hr) (ton) 862 CHAPTER 37 1956 Guide of refrigeration developed. The remainder of the water at the. desired low temperature is pumped out of the evaporator and used at the point where it is required. The ejector compresses the vapor which has been flashed in the evapo rator, plus any entrained air taken from the circulated water, to a some what higher absolute pressure. The vapor and air mix with the impelling steam oh the discharge side of the jet, and the total mixture then passes from the ejector into the condenser. ' . The slight amount of air winch may be entrained in the cooled water is removed by a small secondary ejector which raises the pressure sufficiently so that the air can be discharged to the atmosphere. A secondary con denser is then necessary to condense the steam in the secondary jet. While a single booster of smaller than 15 tons capacity is difficult to build, steam jet vacuum cooling units have been built for as small as 5 to 6 tons capacity. They can readily be built for steam-pressures of from Refrigeration 863 The Absorption System The absorption and compression refrigeration cycles differ only with respect to the method of compression. Each cycle requires a condenser, expansion valve, and evaporator, but the absorption cycle utilizes three major equipments in place of the mechanical compressor; these equipments are the absorber, the pump, and the generator. Vapor from the evaporator is absorbed by a low temperature absorbent fluid which is then pumped to the generator where heat is supplied to boil off the refrigerant. The ab sorbent is now cooled and readmitted, through a pressure-reducing valve, to the absorber. In addition to the three primaiy equipments of the absorption cycle it is necessary to provide auxiliary equipment, usually an analyzer and a rectifier, to remove from the refrigerant leaving the generator, insofar as is possible, the absorbent which vaporizes and leaves the generator with the refrigerant. Removal of this material is of great importance to effec tive operation of the system, since even a small concentration of absorbent Fia. 6. Diagrammatic Arrangement of Steam Jet Vacuum Cooling Unit 5 to. 200 psig, and condenser water temperatures as high as 90 F. The steam consumption in pounds per hour per ton of refrigeration increases rapidly as the booster steam pressure is lowered. For example, the lower ing of the booster steam pressure from 200 to 90 psig results in an increase in steam consumption of approximately 5 percent, whereas a further decrease in booster steam pressure to 10 psig increases the steam consump tion by approximately 72 percent over that required at 200 psig. The capacity of a steam jet system is usually controlled by controlling the number of boosters in use since the unit usually has several boosters operating on the same evaporator. Usually one booster is automatically controlled, whereas the others are manually operated. The capacity is dependent, as for all compressors, upon the evaporator temperature, or in other words, the suction pressure. For example, the capacity is lowered approximately 17 percent if the evaporator or chilled water temperature is lowered from 50 to 45 F. The capacity therefore can be controlled to some extent by regulating the evaporator temperature. Fig. 7. Closed Absorption System in the refrigerant will suffice to reduce greatly the evaporator pressure required for maintenance of a given evaporator temperature. Thermo dynamic analysis of absorption cycles is relatively complex, and requires the use either of tables or graphs showing the equilibrium relationships and thermodynamic properties of the refrigerant-absorbent combination. Data of this kind are given in the first book in the bibliography. A discus sion of various absorbents is given in the sixth book. Thermodynamically, the effectiveness of a refrigerant-absorbent combination increases directly with its negative deviation from Raoult's Law. ' Fig. 7 shows a typical absorption cycle flow diagram. Cooling water firat goes through the absorber (where it extracts the heat of absorption which is liberated by the refrigerant vapor as it goes into solution), then through the condenser, and finally through the rectifier. Refrigerant from the evaporator enters the absorber where it goes into solution in the absorbent; the high concentration solution is then pumped to the generator where heat is supplied; the refrigerant (with some absorbent vapor) leaves for the rectifier and the warm low concentration solution is returned to 864 CHAPTER 37 1956 Guide the absorber. In the rectifier selective condensation occurs, the concen tration of the absorbent in the condensate being much greater than1 its concentration in the entering vapor mixture; rectifier condensate is dripped back to the generator. The ratio of refrigerating effect to heat input (the performance ratio or commonly used efficiency measure of absorption machines) is only 40 to 45 percent with the ordinary ammonia absorption system and, aside from the inherent disadvantages involved in the use of a toxic and explosive refrigerant, this is not sufficiently high to make it competitive with other types of systems when used in air conditioning applications. Therefore, recently, several absorption systems using hygroscopic brines of salts such as lithium chloride or lithium bromide5 (solids in the pure state) as absorb ents and water as the refrigerant have been developed. Such systems are limited to higher temperature applications but, thermodynamically, have HIGH PRESSURE SHELL ' Fig. 8. Diagram op Lithium Bromide Water Absorption System the advantages of a refrigerant with a high latent heat of vaporization and nonvolatile absorbents with a large negative deviation from Raoult's Law. None of the absorbent is carried off with the refrigerant from the generator and the performance ratio ranges as high as 75 percent. Both the refriger ant and the absorbent are non-toxic and non-explosive and the performance ratio does not vary greatly between 20 percent of capacity and full load. This increased efficiency places operating costs in competition with other forms of refrigeration in many high temperature applications such as air conditioning. ' One form of lithium-bromide-water absorption system is shown sche matically in Fig. 8 with the generator and condenser shown located in a high pressure shell and the evaporator and absorber in a low pressure shell. The water to be cooled flows to the evaporator 1 from the load where a small portion of it is flashed into vapor thus cooling the remaining water which is then returned by pump 2 to the load. The pressure in the low side shell and, therefore, the temperature of the water passing through the shell is controlled by the temperature and concentration of the lithium Refrigeration 865 bromide brine sprayed over absorber coil 3. The water vapor flashed in the evaporator chamber is absorbed by the strong salt solution to form a weak solution which drains from the low pressure chamber and passes through solution pump 4. From pump 4 a portion of the weak brine is delivered through the heat exchanger 5 to the high pressure shell and the remainder is mixed with the strong solution through eductor 6 and delivered back to the low pressure shell. Heat applied at the generator 7 boils off the water vapor earlier condensed in the absorber and returns the brine to its original concentration. The condenser 8, also located in the high pres sure shell, liquifies the water boiled off by the generator and this condensate is returned through a liquid loop to the evaporator. The re-concentrated solution is returned from the high pressure shell through the heat exchanger 5 to the eductor 6 where it is mixed with a portion of the weak solution and pumped to the absorber with the mixture at a still relatively high concentra tion. Ice Systems Cold water systems using ice as the cooling agent have been installed in some theaters, restaurants, funeral homes, churches and other places where short hours of operation and high peaks of cooling demand make this type of system desirable. A comparatively small quantity of ice in the water cooling tank of such a system can release refrigeration at a rela tively rapid rate. For instance, neighborhood theaters having a peak demand of 1,200,000 Btu per hr (100 tons refrigeration) have found 8 ton capacity ice bunkers satisfactory. In operation, the water in the air conditioning system is circulated over ice placed in an insulated box, and is cooled to the 38 or 40 deg range or higher, if desired. This cold water is pumped from the ice bunker to air cooling coils or spray type air washers. The blowers, coils, air washer or air handling sections are the same as those parts in any system employing cold water as a refrigerant. The ice water cooler or ice bunker is usually built at the installation in a location where it can easily be iced. It can be constructed of any de sired material such as concrete, steel, or wood with an adequate amount of insulation to save the ice from one period of use to the next. The basic requirement is that the tank be durable and water-tight. The temperature of the water is controlled at a predetermined point by a thermostat in the supply line. If the temperature drops too low, a part of the return water is by-passed directly to the sump and is not cooled over the ice. In the larger systems it is customary to install an overflow ' control which, as the ice melts, discards the excess water through an econo mizer coil, the surface of which is large in relation to the flow so that the water is warmed to 60 F or more as it is discharged from the system. In an attempt to lower initial equipment cost and operating expense, or increase the refrigeration capacity of an existing air conditioning system, storage refrigeration has been utilized in a few applications. Some of the methods which have been adopted include the storage of refrigeration in the form of chilled water, chilled brine, ice on evaporator coils4 and the accumulation of thin sheets of ice on copper plates'in a steel tank.6 If the peak load factor is low as compared with a long period of operation, such as in a restaurant, or if the hours of operation are short but the usage factor high, as in a church, then it is possible to consider storage refrigeration. This method of accumulating refrigeration frequently makes it possible to use low cost off-peak electric power. Power costs may also be reduced by 866 CHAPTER 37 1956 flf tp< i if |rr l *> / <t .. tt: : 'l kW, \1Mt\l: o a " -a --. _ o>rtbS.S*so . i^i mil! if If ;Jr*iii | H O . w g 15 pis ss >*JS 8 S' irtSat 1_b' -S 3 ** 3& SSg,. b.S** l.2* TOl '2g'-o*dB<5 u ll!ip fiil-t Mh-3 a * S g Mij^ "3 2 8-a 3 3 1188-3 g ( ; if-SJIs,,. i|.B 1 lc351Ia *o 2 *8 1 - * 'i 3 s'l-l-s-S 3 . . > ~`-3 g.S> g.S 5 5S ^ S3l S _nK=,, o0x t^3--"a 32(3?wa ^g5 aS(8 SpSoI8&5S.sf3c-SoSb5 a< > fills . ^sg2fio--so-s's g.lSS**s--- >?8ll8 lain? & b S I * *2 M Soft S* >,3-o . S Q-1? 6*5 gg =*5 **3 Ns9i*8|Qa`S=O,--1> I * fa 2 w **6C08 O* j.a9zS* T*3 w8 1-. >.8 8 ^ pa *So3o -M8M5 ggO-I8S| "^SS-rSa^ aoa ao,, *2tro 3 3 _o*o. t^> 2aso^oa---o a O |1 | 0 O I5 soa*a c.- 8 8 -a g 0 P o a>> aa J2 SS>, Ilfl ao &oJs ;S | !5 "J|3oEnsH. ft T3 pa a*a* alpl -- S-- 3o .8 s6.s BB 3ff 84 I *2 2 Psio l; 3a -8 xS8 j-1 2 i it `58.*2c ^*5` o ` -2 ~o 10^2 13m* i0ct!n*S*^-aO --i. *isi*co^^ia,ii--> W < CD &-S il ^=3>s ^t2a**9 ^ gj 4 sa as (2 h a >*,,, 8 Sgl8S|-i-3 5&j>S!'Pj ?tj-^.SSS>3 ! I If a 5-till ag|2 "gSlsSp-lS fill Ill's 1 p Is ' I5 ^ ! ,j|,, g3j<i| || 6 16.6=338? (2 ^ < oo 3 a >~5 I? Sd 3'3cr ^ o6. ^a">c w* 4 5 3 Ef-6 s f|Sl 3 ai Refrigeration 867 installing a smaller refrigeration plant, augmented by a storage system, and by operating it for longer periods. The Heat Pump It has been almost 100 years since Prof. William Thomson (Lord Kelvin) first proposed the use of a compressor as a "warming engine" and as a means of heating buildings to replace equipment for direct burning of fuels. Several early working models were constructed, but the device has remained essen tially of laboratory interest until the last 20 years. Although frequently referred to incorrectly as the reverse cycle system, the heat pump cycle is identical with the ordinary refrigeration cycle, and differs only in the sense that the desired effect is rejection of the heat from the condenser rather than absorption of heat in the evaporator. A discus sion of the coefficient of performance for the heat pump is found earlier in this chapter. The first actual residential heat pump installation was probably made in Scotland in 1927 and since that time, a number of commercial and residen tial systems have been made in this country. Both progress and growth of interest have been particularly rapid in recent years and, consequently, at the present time there are several hundred residential installations and probably a greater number of commercial systems. However, much re search is needed before the residential heat pump installation can success fully emerge to compete economically and with equal reliability with the more common forms of heating and fuels. . From an analysis of the equation for the coefficient of performance, it is evident that the economical adaption of the heat pump as a practical means of heating, requires that the temperature of the source from which the heat is extracted be as high as possible, and that the temperature of the sink to which the heat is rejected for heating purposes, be as low as possible. Thus, with a small temperature spread between the evaporator and the con denser, six or more times as much heat may be obtained theoretically (and three to five times practically) as the heat equivalent of the work necessary to operate the system. There are a number of limitations, however, the most serious of which is the lack of ready availability of a practical source of heat. One of the major problems in the development of the heat pump involves research on, and the compilation of reliable design data for, the various heat sources and sinks available. ' The four principal potential sources of heat are air, water, earth, and solar energy. Of these, the first three are primary sources of heat which may be used alone. The fourth, solar energy, while of tremendous potentiality, will probably be developed in most localities as auxiliary to the other three. In addition, there are other minor sources such as process waste heat, sewage, etc., which may be used under special circumstance. There are also a number of industrial applications of heat pumps, for purposes other than space heating, which are practical largely through economic considerations of the particular process involved. Table 4 pre sents a summary of the advantages and disadvantages of each of these major heat sources. By reference to Table 4, it will be seen that, to date, the most satisfactory heat sources are air, water, and earth, and that air and water are the most satisfactory heat sinks. There are, therefore, six possible combinations of source and sink in application: air to air, air to water, water to air, water to water, earth to air, and earth to water. In addition, it should be recog- If 1 Bff lit' * ** 4 Vft .-#i-1 'll" 868 CHAPTER 37 1956 Guide nized that heat storage devices may be used with any of these systems involving either a single or a dual heat source. One promising possibility involves the utilization of a storage pit or cistern operating upon a heat of fusion cycle and supplied by supplementary heat from air or solar sources. Heat of fusion may, for example, also be utilized with city water and sewage disposal to increase the practicability of these sources. When heat is to be obtained from a ground coil it should be emphasized that, in general, the heat extracted must be replaced by heat from the sun, received by radiation to the ground or by heat carried into the ground by rain. Combinations of heat sources, such as air and water, air and ground, air and solar energy, or ground and solar energy, may also be used and will frequently improve the coefficient of performance over an entire heating season; but they will probably result in considerably greater initial cost. A typical arrangement of a heat pump system with air as the heat source is shown in Fig. 9. Both water and air are practical media to which the condenser heat may be rejected; but the generation of steam requires too high a condenser temperature. Practical operation, therefore, dictates that the heat pump i be used in conjunction with either an air or water heating system with actual distribution of the heat to the rooms through either air ducts, convection radiators, or panels. In general, it is believed that the future of this device is very promising, i and it is recognized that there are a number of practical and economical systems in operation at the present time. However, design data for the majority of types of systems are inadequate, and it is therefore recom ii mended that the enthusiasm and the interest which have greeted the emergence of the heat pump from the category of a scientific toy to one of practical application, should be tempered with caution, since it will probably be several years before proper development and design in formation will enable the widespread satisfactory application of the heat pump. It is for this reason that no design information is presented at this time in The Guide. A wealth of literature concerning individual installa tions is available, and reference to the many articles which have appeared :i ;I Refrigeration 869 in current technical magazines should form sufficient information for those interested in the development of this type of heating. BASIC REFRIGERATION EQUIPMENT Compression Refrigeration Machines Compression of the refrigerant gas drawn from the evaporator may be accomplished by one of several means. Positive displacement may be used as in the reciprocating, rotary or gear types of compressors; centrif ugal force may be applied as in the centrifugal compressor; an ejector may be used as in the steam jet refrigeration cycle ; or absorption of a low pressure refrigerant gas in a secondary fluid, followed by the absorbent's release upon application of heat, may be utilized. A detailed discussion of the equipment required for each of these types of systems is beyond the scope of this chapter. For a more comprehensive treatment, reference may be made to the bibliography. The present discussion is limited to positive displacement reciprocating compressors, rotary compressors and centrifugal compressors. Reciprocating Compressors Reciprocating compressors may be classified according to (a) cylinder design, (b) compressor drive, (c) valves, and (d) lubrication and cooling. Cylinder Design. Cylinder design may vary as to number, arrangement, and action (*.., single-acting or double-acting). Single-acting compressors usually have their cylinders arranged vertically, radially, or in a V or W shaped arrangement. Double-acting compressors, with refrigerant gas drawn in, and compressed on both the head and crank ends of the cylinder, are usually arranged horizontally. Re ciprocating units are available with from one to sixteen cylinders with the V, W, or radial arrangements best adapted to the greatest numbers. The present trend is toward higher operating speeds with a low displacement per cylinder, together with an increase in the number of cylinders. Whereas the original reciprocating com pressors were slow speed (50 to 55 rpm) steam driven devices, modern electric motordriven compressors range up to 3500 rpm. Cylinder heads are usually bolted tight to the cylinders, but in some large compressors where there is danger of wet com pression or of foreign materials entering the compressor space, a secondary head known as a safety head, may be seated at the end of the cylinder and held in position with heavy springs. Normally, this head remains stationary, but excessive pressures in the clearance space are relieved by movement of the safety head, and thus prevent damage to the cylinder. Compressor Drives. Reciprocating compressors may be subdivided on the basis of source of motive power, and whether they are open or hermetic. Practically all modern compressors are electric motor-driven, although a few large, steam-driven compressors are still being installed where steam forms the most economical source of energy. In a few cases, as with truck transportation, the compressor may be driven by an internal-combustion engine. The division of compressors into open or closed types is dependent upon whether the motive power is received from an external source, or whether the motor is direct drive and sealed within the housing. In the open type, power is received from an external source with, one end of the compressor crankshaft extending through the crankcase, and usually V-belt driven. The point of emergence of the shaft from the crankcase forms a weak point of refrigerant leakage, and is most frequently sealed with a bellows type crankshaft seal. Horizontal double-acting compressors operate with a sliding piston rod, moving back and forth through a stuffing box. If the motor is direct-drive and enclosed within the compressor housing, the compressor is classi fied as closed or hermetic. This eliminates the necessity of any shaft seal, and not only prevents refrigerant leakage at this point, but reduces operating noise. One disadvantage is the inaccessibility of moving parts for repairs, but lubrication is greatly simplified since both the motor and compressor operate in a sealed space with the lubricating oil. Compressor Valves. All refrigeration compressor valves are dependent for their 870 CHAPTER 37 1956 Guide operation upon a difference in pressure between the inside of the cylinder and the suction or discharge line. Although mechanically-operated valves might have some advantage, they have proved unsatisfactory because each change'in the evaporator or condenser-operating pressures requires a change of valve setting. The pressure differentials required for operation of the valves depend upon the valve design and the compressor speed. The suction and discharge valves may be arranged with both located in the compressor head, or with the suction valve on the top of the piston and the discharge valve in the compressor head (uniflow arrangement). The valves themselves are usually classified as either poppet, ring-plate or flexing. Lubrication and Cooling. Lubrication of modern compressors is accomplished by either splash lubrication or forced lubrication. The latter is used on large com pressors, while Bimple splash lubrication is used in the smaller units. Large compressors are usually water cooled with the water jacket either cooling the cylinder walls, or both the cylinder walls and the compressor head. Small com pressors are either water cooled or air cooled with extended finned surfaces cast on Refrigeration 871 Centrifugal Compressors Centrifugal compressors are used with very low pressure refrigerants; usually both evaporator and condenser work below atmospheric pressure. Water and monofluorotrichloromethane (CCUF) are the refrigerants com monly used in centrifugal machines. Compression of the refrigerant is accomplished by means of centrifugal force; therefore, this type of compressor is inherently suitable for large volumes of refrigerant at low pressure differentials. Two or more stages are usually required and high speeds are necessary to obtain good efficiency. The evaporator is usually constructed as an integral part of the centrif ugal type condensing unit, to chill water which is then circulated to the 2 n& stage compressor Condenser the exterior of the cylinder. In a few cases small compressors may be found in which there is no attempt to add anypurposive cooling other than through non-finned surfaces to the lower temperature air. Water cooling is more effective than air cooling, but even under the best condi tions cylinder cooling removes only a portion of the superheat in the refrigerant gas. This removal of heat from the cylinder results in some decrease in the work of compression, as well as reduction in condenser load. Rotary Compressors In recent years rotary compressors, usually hermetically sealed, have become quite popular for fractional tonnage applications and are being designed in increasingly larger sizes. Of the various designs attempted, the single blade rotary compressor, shown diagrammatically in Fig. 10, is the most popular. An eccentric driven rotor revolves within a housing in which the suction and discharge passages are separated by means of a sealing blade. When the rotating eccentric first passes this blade and the suction opening, the compressor suction space is very small. As the ec centric rotates, this crescent-shaped space becomes increasingly larger, thereby drawing in a charge of suction gas. When the eccentric again passes the blade, the gas charge is cut off from the suction inlet, compressed, and discharged from the compressor. Such rotary compressors are quiet in operation and reasonably free from vibration. In common with other types of hermetically sealed units, they have the advantages of compara-, tively low loss of refrigerant and sealed-in lubrication. ! Fig. 11. Enclosed Type Centrifugal Condensing Unit air conditioning system. This is done because it would not be economical to pipe these large volumes of refrigerant any distance. Centrifugal compressors, like reciprocating compressors, can be divided into two general types, open and enclosed. In general, the open type com pressor is geared to the driving mechanism, and operates at higher speed than the driving motor or turbine. A modem, completely enclosed, directdriven centrifugal compressor is illustrated in Fig. 11. Centrifugal refrigeration compressors are particularly well suited to direct steam turbine, drive because of their high operating speed. Water cooling equipment of one design is operated between 3500 and 4000 rpm for units developing 1000 to 2000 tons capacity, and from 7000 to 8000 rpm for units developing 100 to 200 tons capacity. However, a great many applications, particularly in the smaller sizes, are electric motor-driven and equipped with standard gear-type speed increasers. Centrifugal systems are particularly well adapted to large capacities (up to 3000 tons) although it is also possible to secure units as low as 50 tons in rating. Because cen trifugal units operate best with refrigerants possessing a high specific vol ume, and because of the simplification of lubrication difficulties, they are frequently used for extremely low temperature applications. They are adaptable to a wide range of temperatures from --130 F to 50 F. One im portant advantage is their flexibility under varying loads, since units may be 872 CHAPTER 37 1956 Guide designed to operate with reasonable efficiency at capacities as low as 20 per cent of normal load. / Condensers Condensers used for liquefying the refrigerant are of three general de signs: (1) air cooled, (2) water cooled, and (3) evaporative (combination air and water). 1. Air cooled condensers are seldom used for capacities above 3 tons of refrigeration, unless an adequate water supply is extremely difficult to obtain, as, for instance, in railway air conditioning. Even on fractional tonnage installations, air is used as the condensing medium only where water is expensive, or where simplicity of instal lation warrants the higher condensing pressure and consequent power costs higher than would be obtained using water as the condensing medium. The conventional air cooled condenser consists of an extended surface coil across which air is blown by a fan. The hot discharge gas enters the coil at the top and, as it is condensed, flows to a receiver located below the condenser. Air cooled con densers should always be located in a well ventilated space so that the heated air may escape and be replaced by cooled air. The principal disadvantages of air cooled condensers are the power required to move the air, and the reduction of capacity on hot days. This loss of capacity, due to high condensing pressures on hot days, requires that equipment of increased capacity be selected to meet the peak load. Thus at normal loads the equipment is oversized. The principal advantages are low installation costs and simplicity, and for these reasons they are frequently used in small self-contained units. ' 2. Water cooled condensers are commonly used with compressors of one horsepower or larger in size, and they are found almost exclusively on large installations. They usually prove to be the most economical choice if an adequate water supply and means for its disposal are available. Although water cooled condensers may be of many designs, the shell and coil and the shell and tube are most commonly found in present day practice. The amount and temperature of the condensing water determine the condensing temperature and pressure, and indirectly the power required for compression. It is therefore necessary to determine a balance so that the quantity of water insures economical compressor operation. Because there is a decided tendency to conserve the water in city mains, and because most large cities are restricting the use of water for air conditioning and refrigeration equipment, it is often necessary to install cooling towers or evaporative condensers. Cooling towers, unfortunately, produce the warmest condensing water at the time when the load on the system is greatest, so that the refrigeration equip ment must be designed to meet the maximum load at abnormal condensing water temperatures. If properly designed, this makes little difference in the efficiency of operation throughout the year, except at those times when the condensing water temperature is highest. As this occurs only for 5 percent of the entire cooling period, it can be disregarded as a factor in establishing yearly operating costs. For further information on cooling towers, reference may be made to Chapter 35. 3. Evaporative condensers were developed to alleviate the over-burdened water supply and drainage facilities of communities where many small air conditioning systems using water cooled condensers were applied. The adaptation of cooling towere to small installations is not practicable. The evaporative condenser combines the functions of the two by using a minimum amount of water on a finned surface, cooling it to approximately the wet-bulb temperature of the surrounding atmos phere. . The end view of a typical evaporative condenser is shown in Fig. 12. The fan draws the air over a finned tube condenser which is kept wet by a water spray. The discharge refrigerant gas from the compressor enters the top of the condenser coil, and the liquid refrigerant is drained from the bottom of the coil into a liquid receiver, and then circulates through the remaining portion of the system in the usual way. | The water is circulated through the spray nozzles, and the level is maintained in the sump by means of a float valve. The eliminator plates are placed in the path ofj Refrigeration 873 the water-air mixture so as to remove the entrained water. The air leaving the unit is almost completely saturated, so that care must be taken in locating discharge ducts to prevent condensation. Evaporative condensers arc available in sizes up to 100 tons or more. These units use only a small portion of the water required for a water cooled condenser. The water is vaporized by the heat of the refrigerant so that each pound of water used extracts approximately 1000 Btu from the refrigerant, whereas under standard rating conditions where the water temperature rise is 20 F, each pound of water extracts only 20 Btu from the refrigerant. Including the water lost by entrainment Fig. 12. Schematic View op an Evaporative Condenses . >' '. m the discharge air, by overflow and stand-by evaporation, the water used is about 3 to 5 percent of the amount that would be required for a water cooled condenser. The evaporative condenser requires more maintenance, occupies greater space (must be located where air is available), and has a higher first cost than the water cooled condenser, but where the use of water is restricted or expensive, the evapora tive condenser has become widely accepted. Compared with a water cooled con denser and cooling tower, which combination uses about the same quantity of water, the evaporative condenser has the advantage of lower cost and smaller space re quirements. Evaporators and Coolers Refrigeration evaporators must be designed for efficient removal of heat from the medium being cooled, as well as effective boiling of the refrigerant and a minimum drop of pressure through the coil. There are two general types of evaporators, dry and flooded. In the dry evaporator the re frigerant enters in the liquid state, and the design provides for complete 874 CHAPTER 37 1956 Guide evaporation with the vapors leaving slightly superheated. In flooded evaporators not all of the refrigerant is evaporated, the liquid-vapor mix ture leaving the evaporator flows into a surge drum from which the vapors are drawn into the compressor suction line, and the liquid is recirculated through the evaporator. The types of coolers used in connection with air conditioning work fall into three general groups: (1) direct water coolers, (2) direct air coolers, and (3) brine coolers for circulation of the brine in a closed system, and thus cooling indirectly either water or air. 1. Water coolers. One method of the direct cooling of water is to install direct expansion coils in the spray chamber so that the water sprayed into the air comes in direct contact with the cooling coils. Another common and efficient method of cooling spray water is to use a Baudelot type of heat absorber where the water flows over direct expansion coils at a rate sufficiently high to give efficient heat transfer from water to refrigerant. Another type of spray water cooler is the shell and tube heat exchanger in which the refrigerant is expanded into a shell enclosing the tubes through which the water flows. The velocity of the water in the tubes affects the rate of heat transfer, and as the refrigerant is in the shell completely surrounding the tubes at all times, good contact and a high rate of heat transfer are insured. The disadvantage of such a system is that with the falling off of load on the compressor, the suction tempera ture or the temperature in the evaporator drops, and there is a possibility of freezing the water in the tubes, which, of course, might split the tubes and allow the re frigerant to escape into the water passage. This danger can be eliminated by auto matic safety devices. Another system of cooling spray water is to submerge coils in the spray collecting tank, or in a separate tank used for storage. The heat transmission through the walls of the coils, however, is low and a great deal more surface is required than for any other type of cooler. However, with large Btorage tanks this type of cooling can be utilized to advantage. 2. Air coolers. When direct cooling of air is employed, the refrigerant is inside the coil and the air passes over it. Cooling depends upon convection and con duction for removing the heat from the air. The type of coil used can be either smooth or finned, the finned coil being more economical in space requirement than the smooth coil. The fins, however, must be far enough apart so as not to retain the moisture which condenses out of the air. When refrigeration evaporators are used for cooling air or other gases by forced convection, they are usually termed blast coils or unit coolers. A blast coil may be placed in a duct or in an assembled unit, and the air forced across the coil and dis charged through distributing ducts or directly into the space to be conditioned. Unit coolers, designed much like unit heaters, consist of a finned coil, propeller fan, and controls suspended directly in the space to be cooled. 3. Indirect brine coolers. The indirect cooler, where brine is cooled by the re frigerant and the resulting cold brine is used to cool either air or water, introduces several other considerations. It is not the most economical from a power consump tion standpoint, as it is necessary to cool the brine to a temperature sufficiently low so that there is an appreciable difference between the average brine temperature and that of the substance being cooled. This requires that the temperature of the refrigerant must be still lower, and consequently the amount of power required to produce a given amount of refrigeration increases due to the higher compression ratio. There are other considerations which make such a system desirable. In the first place, where a toxic refrigerant is undesirable or cannot.be used because of fire or other risks, especially in densely populated areas, the brine can be cooled in an isolated room or building and can then be circulated through the air conditioning equipment. This arrangement eliminates any possibility of direct contact between the air and refrigerant. REFRIGERATION CONTROL In addition to the compressor, evaporator, and condenser, several auxili aries are required for proper operation of a refrigeration system. Some device must be supplied for the controlled expansion of the refrigerant from Refrigeration 875 the high condenser pressure to the low evaporator pressure; controls are required for the on-off operation of the compressor, the flow of the con densing medium, and for safety devices; proper piping is required for connecting the various portions of the systems. Where refrigerating appa ratus is used for the cooling of rooms, additional controls are required. Expansion Devices Some form of expansion device must be provided to control the rate of flow of the liquid refrigerant between the high and low side pressures of the system. This device is usually an expansion valve and may be either manual or automatic; however, with few exceptions, manual valves are obsolete and no longer used. Automatic Expansion Valves. An automatic or pressure controlled expansion valve operates to maintain a constant pressure in the evaporator. The liquid re frigerant passes through an orifice, the opening size of which is controlled by means Fig. 13. Typical Thermostatic Expansion Valve of a needle valve connected to a flexible bellows. This bellows expands or contracts with variations in the evaporator pressure transmitted to the expansion chamber through the refrigerant outlet from the evaporator. The position of this needle valve is controlled by the degree of compression in an adjustable spring, balanced against the bellows, and these two forces operate to maintain a constant pressure in the evaporator by increasing or decreasing the flow of liquid refrigerant. Such an expansion valve is usually applied to evaporators of the airect expansion type, but is not satisfactory for fluctuating loads such as are encountered in air conditioning installations. Thermostatic Expansion Valves. A thermostatic expansion valve controls the flow of liquid refrigerant to the evaporator so as to maintain the entire coil filled with evaporating refrigerant, and to keep a constant superheat in the refrigerant gas leaving the coil. The construction of such a valve is shown in Fig. 13 and is similar to that for an automatic expansion valve but incorporates, in addition, a power element responsive to changes in the degree of superheat of the refrigerant gas leaving the coil. This power element consists of a bellows connected by means of a capillary tube to a feeler bulb fastened to the suction line from the evaporator. The bulb, bellows, and tube are usually charged with the same liquid refrigerant used in the evaporator itself. A starved condition in the evaporator results in a greater superheat in the gas leaving the evaporator, and this in turn operates through the power element to increase the flow of liquid refrigerant. A flooded evaporator reduces the discharge superheat, and thus tends to reduce the flow of liquid re frigerant. Such an expansion valve is satisfactory for operation with fluctuating loads since this type of control tends to keep the evaporator filled with refrigerant at all times. Low-Side Float Valves. A liquid refrigerant control of the low-side float valve type consists of a ball float located in either a receiver or the evaporator itself on 876 CHAPTER 37 1956 Guide the low pressure side of the system. A needle valve, operated through a simple lever mechanism attached to the float, permits the passage of more or less refrigerant, as the level in the receiver or the evaporator fluctuates. Such a control must be used in conjunction with a flooded evaporator, and has been applied extensively to household refrigerators and, to some extent, in commercial and industrial instal lations. Bigh-Side Float Valves. A high-side float valve differs from a low-side float valve in that the float is located in a receiver or container on the high pressure side of the system. Proper operation again depends upon metering of the refrigerant through a controlled opening, depending upon the level of the liquid refrigerant in the con tainer. Such a control has the disadvantage that the evaporator must be placed directly adjacent to the float container, or some intermediate pressure device must be applied to prevent flashing of the refrigerant upon pressure drop. Capillary Tubes. A capillary tube may be used as a liquid refrigerant expanding device. Such a device consists of an extremely small bore tube (in the order of 0.04 inch in diameter) of five to twenty feet in length. Although such a restricting device operates as a very simple means of expanding the liquid refrigerant, it has the disadvantage that no modifications are possible to adjust the rate of expansion under various operating conditions. The bore and length of the tube, as well as the proportions of the rest of the system, are critical. It is for these reasons that its application has been limited to factory assembled domestic and commercial units. Refrigeration Control Devices In addition to automatic control of expansion of the liquid refrigerant, a completely automatic refrigeration system requires (1) some means for on-off operation of the compressor motor, (2) control of the flow of the con densing medium, and (3) safety devices for prevention of damage to the equipment. In addition, special controls designed for specific applications are-frequently required. The various types of devices used to accomplish these purposes are so numerous that it would be impossible to describe all of their modifications. Only the general purposes and operating char acteristics of the more typical mechanisms are here discussed. Compressor Motor Controls. Two types of controls are used for intermittently starting and stopping compressors. The first of these is a pressure motor control responsive to the evaporator pressure, and the second a thermostatic motor control responsive to the temperature of the load surrounding the evaporators. In the first case the compressor operation is indirectly dependent upon the temperature of the load, and is controlled by the refrigerant pressure at the point of control location. The second type is dependent upon the temperature of the load being cooled. With the pressure actuated device, the control is frequently located directly on the condensing unit, and the low pressure in the suction line or the crankcase of the compressor is used to control motor operation. Such a control usually consists of a low pressure bellows, connected through tubing directly to the low pressure control source, and an electrical switch operated through linkage by the movement of the bellows. The electrical circuit is closed on rising pressure, and opened on falling pressure. The thermostatic type of motor control is usually similar in construction to the pressure control, with the exception that a temperature bulb and capillary tube replace the pressure line, and the temperature bulb is located adjacent to the evaporator itself. In this case motor control is directly responsive to changes in the temperature of the load surrounding the evaporator. Frequently, a high pressure safety cutout switch is combined with the motor control, and operates to cut off the power from the motor in case the high side pressure exceeds a predetermined limit. Solenoid Valves. Solenoid or magnetic stop valves are frequently used in re frigeration systems for control of gas and liquid flow. When applied as liquid stop valves, they are placed in the liquid line between the condenser or receiver and the evaporator, and the line is open to passage of the refrigerant only when the com pressor is in operation. When the compressor is not in operation, leakage of liquid refrigerant in the evaporator is prevented. In some cases such a magnetic stop valve is operated directly by a thermostat located at the point of the load, and the compressor motor operation is controlled independently by a low pressure switch. Refrigeration 877 Magnetic liquid stop valves are also widely used for the control of the refrigerant flow to individual evaporators in a multiple evaporator system operated by one compressor. In some installations magnetic liquid line and suction line valves are usea to isolate completely an evaporator for defrosting purposes. . A magnetic valve may be installed in a by-pass around one or more cylinders of a multiple cylinder compressor; and thereby be used to unload a compressor during starting to reduce load. Additional applications are found in control of the circulation of brine in a secondary refrigeration system. Suction Pressure Valves. Suction pressure control valves, frequently called back pressure regulators or two-temperature valves, are sometimes placed in the. suction line to prevent the evaporator pressure and temperature from dropping below a pre determined level. Typical applications of such controls occur in water cooling or milk cooling systems, where freezing and other damage would result if the evaporator pressure dropped too low, or in multiple systems where several evaporators are supplied by one condensing unit. Thus, different evaporators may be kept at different temperatures by maintaining a pressure drop between the evaporator and the suction line. Condensing Water Control. The majority of the refrigeration systems, other than fractional horsepower, use water cooled rather than air cooled condensers, since the lower condensing temperatures result in more economical operation. Automatic control of the water flow to the condenser must be maintained if water wastage is to be eliminated. Such control may be provided through the use of either an electric solenoid water valve or by means of a pressure control valve. With a solenoid valve, the flow is two-position, either off or on, and its operation is simultaneous with starting and stopping of the compressor motor. With a pressure operated valve, the flow is modulated and is dependent entirely upon condenser pressure rather than condensing unit operation. Similar water valves controlled thermostatically by the temperature of the water discharged from the condenser are also available. Safety Controls. Many controls are designed not to aid in proper operation of the system, but to prevent damage in case of improper operation. One such safety control is the high-pressure cutoff frequently combined with the low-pressure motor control as previously described. Another safety control often used is a low voltage cut-off which shuts down the system automatically in case the line voltage drops below a minimum value. High pressure relief valves are used for safety purposes to prevent damage in case excessive condensing pressures are encountered. Refrigeration Control for Air Conditioning Equipment When refrigerating equipment is used for space cooling, two major control problems exist: one is control'of the temperature and the other, control of the humidity. In some applications the amount of latent heat to be removed is small compared with the sensible heat. In such cases, sufficient dehumidification will usually occur without any special provisions. In other cases, such as theaters, where the latent load is relatively high, the air must be cooled below its dew-point temperature, and sometimes re warmed to return it to the comfort range. Chapter 39, Automatic Control, discusses, among other topics, control systems for unit coolers, well water and ice cooling systems, central fan systems, and all-year air conditioning systems. REFRIGERATION PIPING The pressure drop which occurs during passage of the refrigerant through connecting piping is similar in effect to that which occurs through suction and discharge valves of the compressor. Thus, the effect of the pressure drop in the suction line between evaporator and compressor requires that a lower pressure be maintained inside the compressor during suction than is maintained in the evaporator. The pressure drop through the connect ing piping between the compressor and the condenser requires that a higher pressure be maintained inside the compressor during discharge than in the 878 CHAPTER 37 1956 Guide condenser. ' These losses result in a greater compression ratio, and therefore greater power requirements, as well as a lower volumetric efficiency and higher displacement requirements. Pressure losses in the liquid line between condenser or receiver and the expansion valve may result in some flashing of the liquid refrigerant, unless the liquid is subcooled. In all cases, frictional losses should be kept to a minimum, and piping should be selected which will give the smallest loss consistent with overall economy in the system. .. Refrigerant liquid lines from the receiver to the expansion valve should be preferably designed with a pressure drop of less than 5 psi, and with 10 psi as the maximum. A velocity of 100 to 250 fpm is recommended to prevent a pressure drop great enough to cause vaporization of the refriger ant ahead of the expansion valve. If the evaporator is to be located at a higher elevation than the condenser or receiver, account should be taken Table 5. Dichlobodifluobomethane (CCIjF,) Liquid Lines, Tons Capacity peb 100 Ft Equivalent Length Line Size, Inches 100Pbessube Dbop per Ft Equivalent Length, Psi 3 5 10 20 - !OD \ OD i IPS 1 OD i IPS i OD 1 IPS li OD H IPS 11 OD H IPS If OD 2 IPS 21 IPS 3 IPS 31 IPS 4 IPS 0.88 2.89 4.86 4.86 9.73 10.5 21.4 21.4 36.9 36.9 62.0 62.0 124. 230. 364. 539. 753. 1.14 3.64 6.81 6.81 12.6 14.1 28.2 . 28.2 48.1 48.1 80.2 80.2 161. ' 297. 469. 704. 972. 1.80 5.56 10.2 10.2 18.5 21.8 41.3 41.3 70.5 70.5 114. 114. 231. 426. 676. 1005. 1385. . 2.58 8.50 15.8 15.8 27.0 33.0 60.8 60.8 101. 101. 160. 160. 328. 607. 972. 1430. 1945. Note: Tonnage values above those underlined give velocities of 300 fpm or less. of the pressure drop for each foot of static liquid lift. Approximate values are 0.26 psi per foot for ammonia, 0.57 psi per foot for dichlorodifluoromethane, 0.51 psi per foot for monochlorodifluoromethane, and 0.64 psi per foot for monofluorotrichloromethane. Where there is a possibility of va porization of some of the liquid before reaching the expansion valves, means for subcooling should be provided. Since a reduction of suction pressure at the compressor results in an appreciable reduction in capacity and more power input per ton of refrigera tion, great care should be given to the proper sizing of suction lines between the evaporator and the compressor. Although comparatively high veloci ties, 500 to 5000 fpm, may be used, the optimum value wall depend upon the refrigerant and the operating pressure range. Since return of the oil to the compressor must be considered in the case of the fluorinated hydro carbons and methyl chloride, for these refrigerants the minimum velocity should be 500 fpm for horizontal runs and. .1000 fpm for vertical runs. For the former, the usual design velocities range between 1000 and 2000 Refrigeration 879 Table 6. Maximum Tons op Compbessob Capacitt fob CCIiF, Lines (Only for temperatures indicated) Line Size Inches ' Suction Lines Based on 105 F Condensing Temperature . Psi Pressure Drop per 100 Ft Equivalent Length at 40 F Saturation i 234 5 Discharge Lines Condensing Temperature 115 F 90F i OD i IPS i OD I IPS IA7 OD IPS n OD i IPS 0.14 0.17 0.25 0.35 0.55 0.68 1.26 1.43 0.20 0.24 0.35 0.45 0.76 0.94 1.80 2.01 0.28 0.34 0.51 0.65 1.10 1.35 2.57 2.89 0.35 0.42 0.62 0.79 1.34 1.65 3.17 3.54 0.41 0.49 0.73 0.93 1.58 1.92 3.76 4.17 0.45 0.54 0.81 1.03 ' 1.75 2.12 4.15 4.60 1.43 1.87 2.97 3.26 5.05 5.29 1.15 1.50 2.38 2.62 4.05 4.25 it OD H IPS H OD li IPS 2.21 2.70 3.40 4.05 3.12 3.82 4.78 5.75 4.45 5.37 6.79 8.10 5.50 6.72 8.42 10.12 6.38 7.68 9.77 11.6 7.05 8.48 10.8 12.8 7.72 9.16 10.92 12.5 6.19 7.35 8.75 10.0 2* OD--- -- 6.12 2 IPS 7.66 2i OD 12.0 2i IPS 12.0 8.60 10.9 17.1 17.1 12.1 15.3 24.0 24.0 15.1 19.2 30.1 30.1 17.4 32.2 34.6 34.6 19.2 24.5 38.2 38.2 19.2 20.6 32.2 32.2 15.3 16.5 25.9 25.9 31 OD 3 IPS 3f OD 3i IPS 19.1 20.9 27.8 30.2 27.2 29.4 39.7 43.2 38.2 42.3 55.7 61.0 47.8 51.8 69.8 76.1 55.0 60.0 80.3 87.0 60.7 66.2 88.7 96.0 51.5 54.5 72.0 78.8 39.8 43.8 57.6 63.3 4i OD 38.6 55.2 78.0 97.3 111 123 95.8 77.1 4 IPS 40.7 . 58.6 83.0 103 118 130 101.6 81.6 5 IPS 71.3 100 141 176 2C3 224 171.5 137.8 6 IPS 126 183 257 322 366 403 266 214 8 IPS 211 297 422 523 602 664 461 370 10 IPS 352 503 712 887 1024 1130 725 582 12 IPS 550 780 1106 1373 1582 1748 1041 836 fpm. Too high velocities create noise problems and excessive pressure drops. The total pressure drop in the suction line should be between one and two psi, if the velocity can be kept to within the specified limits. Compressor discharge or hot gas lines may be designed with velocities from 1000 to 5000 fpm, except for dense gases such as carbon dioxide, where noise considerations will reduce the upper limit. A pressure drop of 2 to 4 psi is recommended for the discharge lines. Extensive tables are. available in the literature for the determination of pressure drops through refrigerant lines with various refrigerants. The capacities listed in Tables 5, 6 and 7 are published in ART Equipment Standards-1946, of the Air Conditioning and Refrigeration Institute, and are used by permission. Table 7. Appboximate Suction-line Capacity Factobs fob Equal Pbessube Dbop of CCIiFj Saturated Suction Temperature, F. 50 40 30 20 ' 10 0 -10 Factor. .. ------ ' 1.09 1.00 0.92 0.86 0.80 0.74 0.66 880 CHAPTER 37 1956 Guides Table 5 shows the tonnage capacity normally allowed for CCl2F2 liquid lines per foot equivalent length of pipe, and Table 6 the maximum tonnage for suction and discharge CC12F2 lines. Table 7 presents suc tion-line capacity factors for equal, pressure drop. ACCESSORIES Dehydrators, oil separators, strainers, vibration eliminators, sight glasses, and various types of valves are accessories frequently needed for the proper Refrigeration 881 in water lines, leading to water cooled condensers. Sight glasses which permit visual inspection of the condition of the refrigerant are sometimes installed on factory assembled commercial unit systems. . It is particularly advisable to place such a fitting before the expansion valve, if the evaporator is located above the condenser. Flexible vibration eliminators, usually consisting of a bellows design covered with woven copper wire, are sometimes installed in copper lines where units such as compressors are installed on flexible mountings, or where vibration is otherwise a problem. Packed or packless shut-off valves are necessary where it may be required to isolate portions of a system. Machines at Constant Speed installation and operation of refrigeration systems. Refrigerant-line de hydrators or dryers usually consist of copper containers fitted with tubing connections at either end, and contain a desiccant such as silica gel, acti vated alumina, or calcium chloride. The liquid refrigerant is circulated through the dryer during operation of the system, and the moisture content of the refrigerant charge is thus kept to a minimum. ' Oil separators are installed between the compressor and condenser to prevent excessive oil removal from the compressor crankcase and its passage into the condenser and evaporator. The oil is separated from the gaseous refrigerant by gravity during its passage through a chamber of sufficient size to reduce the velocity. A float-operated valve maintains a maximum oil level in the separator, and additional oil is forced by pressure difference through a line back to the crankcase. ". . Screen strainers are frequently installed in the liquid line piping" before solenoid valves and expansion valves, as well as before regulating valves Fig. 15. Performance Characteristics of Compression Refrigeration Machines at Constant Speed EQUIPMENT CHARACTERISTICS AND SELECTION The various types of compression systems have quite different charac teristics of capacity and power with varying evaporator and condenser temperatures, as may be noted from curves in Figs. 14 and 15. From Fig. 14 it may be observed that power requirements for the centrif ugal compressor increase much more rapidly than for the reciprocating compressor, with increase in evaporator temperature. Similarly, the ca pacities of the steam ejector and centrifugal compressors increase more rapidly than those of the reciprocating compressor with increase in evapo rator temperature. Thus, both the steam jet and centrifugal machines tend to be more self-regulating than the reciprocating. It is also evident from Fig. 14 that the steam jet equipment is best suited for operation at high evaporator temperatures. The effect of condenser temperature upon the power and capacity of the different types of compressors is shown in Fig. 15. It may be noted 882 CHAPTER 37 1956 Guide that the power required by the reciprocating compressor increases rapidly with increase in condenser temperature, while the power curve for the centrifugal compressor is relatively hat. It. is also evident that the, ca pacity of the steam jet compressor is independent of condenser temperature until a certain point is reached, where it drops to zero. As previously stated, steam jet equipment requires more , condensing water than other types of compression systems. Consequently, steam jet systems are well, suited to those applications where condensing water is cheap, of where condensing water is rather high in temperature. The selection of proper refrigeration equipment for any air conditioning Table 8. Basis op Equipment Selection Capaott Tons Majobitt Used Sous Used Few Used 0 to 5 Unit systems in con Unit central systems Built up central sys ditioned space. using duct distri tems. bution. 5 to 25 Built up central sys Unit central systems tems using recipro using' duct distri cating compres bution. sors. Unit systems in con ditioned space. Built up systems us ing absorption and adsorption sys tems. 25 to 50 Built up central sys tems using recipro cating . compres sors. Built up central sys tems using centrif ugal compressors. Central systems us ing adsorption sys tems. 50 to 400 Built up central sys tems using recipro cating compres sors. Built up central sys tems using steam jet and centrifugal compressors. Built up central sys Built up central sys 400 and Over tems using centrif tems using steam ugal compressors. jet. job is of utmost importance for satisfactory results. The most important factors in the selection of the equipment are: 1. Loads (as determined by the conditions of the space to be cooled). 2. Economics (both initial and operating costs). 3. Codes (local safety codes must be adhered to and influence the type of system to be used). A broad division of equipment to be used for a particular installation or application may be made on the basis of the magnitude of the load. Cur rent general practice is outlined in Table 8. Unit or packaged systems, consisting of a reciprocating compressor, condenser, evaporator, and fans, are generally used in the smaller sized jobs where electric power is available, as they are manufactured complete, ready to install, and are the most economical (see Chapter 26). The reciprocating, compressor in the built-up central system (see Refrigeration 883 Chapter .30) covers the widest range of application since it is applicable to either the direct expansion or indirect systems, and can be driven by steam or gas engines, or by electric motors. The quantity of condensing cooling medium required is also less than for any other system, with the exception of the centrifugal compressor, which uses the same amount. : Centrifugal compressors are used for large installations, and usually where the indirect system is required. The driving mechanism can be a steam turbine or electric motor. The steam jet system is used where steam is available and cooling water can be had in large quantities!......... It will be noted by referring to Fig. 14 that all systems using compressors have a common characteristic, namely, that the capacity varies with the evaporating temperature. Not only can the equipment be selected to S? 3 ui i/t z 3 16.Fig. Compressor and Coil Performance produce a given result, but the performance can be predicted under vary ing load conditions by the simple expedient of using the variable of evapo rating temperature as the abscissa, and the load or capacity as the ordinate in a series of curves. , Manufacturers of compressors and cooling coils furnish performance data for apparatus that can be plotted in the form of curves similar to those shown in Fig. 16. The performance of a compressor is plotted as a series of curves, each curve being drawn for a given condensing pressure. The performance of a direct expansion coil at two different air velocities ,is plotted on the same graph. The operating point will be, of course, where the two curves cross. Data given in Table 9 illustrate two types of conditioned enclosures having the same total load of 148,000 Btu per hour, but with two different ratios of sensible to total heat. In the case of the office with a ratio of 82 percent sensible to total heat, the operating point A in Fig. 16 is found to be 42.2 F evaporating temperature, with a face velocity of 500 fpm. In the case of the restaurant, with a ratio of 69.5 percent sensible to total heat, the air velocity is lowered to 300 fpm, and the evaporating tempera- 884 CHAPTER 37 1956 Guide Thri/r 9. Typical Opebatino Conditions fob Two Types of Load ' ---- ------------------------------------- ----------- ;--------- - i------- --7!~>'------------ ; Load, Btu peb Boub Aib Entebino Opebatino Balance Point Con* Ratio Type op Enclosubb Sensible Latent Total Sen sible TO Total F Deg Per ' Cent R.H, Evapo rator Temp F Deg Con denser Per Cent Pressure Sensible Lb per Heat 8q In. Restaurant.... 103,000 45,000 148,000 0.695 Office.................. 121,000 27,000 148,000 0.820 82 82 45 34.4 123 45 42.2 100 69.9 82.1 ture is lowered to 34.4 F as shown in point B of Fig. 16. In order to obtain the same capacity, a larger condensing unit is used. This illustration assumes zero pressure drop through the suction line. The pressure drop can be taken into account by shifting the compressor performance curves by the amount of pressure drop expressed in .Fahrenheit degrees. REFERENCES 1 Air Cycle Refrigeration, by Paul C. Scofield {Refrigerating Engineering, Vol. 57 No. 6, June 1949, p. 558). . * Application and Economy of Steam Jet Refrigeration to Air Conditioning, by A. R. Mumford and A. A. Markson (A.S.H.V.E. Transactions, Vol. 44,1938, p. 33). 3 A New Development in Absorption Refrigeration, by A. A. Berestneff {Re frigerating Engineering, Vol. 57, No. 6, June 1949, p. 553). 4 The Application of Storage Refrigeration to Air Conditioning, by C. F. Boester (A.S.H.V.E. Transactions, Vol. 45,1939, p. 675). 3 Use of Cold" Accumulators in the Air Conditioning Field, by R. W. Evans and C. J. Otterholm (A.S.H.V.E. Tbansactions, Vol. 48, 1942, p. 123). BIBLIOGRAPHY Refrigerating Data Book, Vol. 1 {American Society of Refrigerating Engineers). Refrigeration Engineering, by H. J. Macintire (John Wiley <fe Sons). Theory of Mechanical Refrigeration, by N. R. Sparks (McGraw-Hill Book Co.). Refrigeration and Air Conditioning Engineering, by B. F. Raber and F. W. Hutchinson (John Wiley & Sons, 1945). Refrigeration, by J. A. Moyer and R. U. Fitts (McGraw-Hill Book Co.). Refrigerants and Absorbents, by W. R. Haineworth {Refrigerating Engineering, August and September, 1944). Air Conditioning and Refrigeration, by B. H. Jennings and S. R. Lewis (Inter national Textbook Company, 1944). Refrigeration and Air Conditioning, by Jordan and Priester (Prentice-Hall, Inc., 1948). - Meat Pumps, by P. Sporn, E. R. Ambrose and T. Baumeister (John Wiley and SonHse, a1t9P47u)m. p Applications, by E. N. Render and S. Oglesby, Jr. (McGraw Hill Book Co., 1950). . CHAPTER 38 DEHUMIDIFICATION BY SORBENT MATERIALS Definitions and Principles, Adsorbents, Dehumidification by Solid Adsorbents, Dehumidification Equipment Using Solid Adsorbents, Absorbents, Dehumidification by Liquid Absorbents, Dehumidification Equipment Using Liquid Absorbents, Calculation of Moisture Load, Vapor Transfer to Dehumidified Space DEHUMIDIFICATION as used herein is the reduction of the water vapor content of a given volume of air or other gas. The term thus describes a special case of dehydration which covers the removal of moisture in any form from matter. The degree of dehumidification required varies greatly with different applications, and is one of the prime considerations influencing the choice of a method. Dehumidification may be accom plished by latent heat removal, together with sensible heat removal, as described in Chapters 30, 35, and 36, or by the use of sorbents. ' Sorbents are substances which have the property of extracting and hold ing other substances (usually gases or vapors, e.g., water vapor), brought into contact with them. All materials are sorbents to a greater or lesser degree. The weight of water held by a substance will increase or decrease, depending upon whether the vapor pressure of the water held by the sub stance is less or greater, respectively, than the partial pressure of water vapor in the surrounding atmosphere. As generally used, however, the term sorbents refers to those materials having a capacity for moisture which is large compared to their volume and weight. Such materials are divided into two general classifications: 1. Adsorbent--A sorbent which does not change physically or chemically during the sorption process. Certain solid materials, such as activated alumina, silica gel, activated bauxites, and activated charcoal have this property. The action of adsorb ents, most of which adsorb some gases and condensible vapors besides water vapor, is selective. Thus, in the case of a mixture containing both water and organic vapors, silica gel would remove the water vapor in preference to the organic vapors, while the reverse would be true in the case of activated carbon. The selective property of adsorbents is made use of in some instances for the removal of objectionable and con taminating vapors from an air or gas mixture. (See Chapter 8.) 2. Absorbent--A sorbent which changes either physically, chemically, or both, during the sorption process. Calcium chloride is an example of a solid absorbent, while liquid absorbents include solutions of lithium chloride, calcium chloride, lith ium bromide, and the ethylene glycols. - ADSORBENTS The ability of an adsorbent to remove water vapor from a gas is explained by the fact that the vapor pressure of the water in the adsorbent (when in the reactivated condition) is less than the partial pressure of the water vapor in the surrounding atmosphere. For instance, when an active ad sorbent is brought into contact with a gas of high humidity, there is a tendency for the vapor pressure of the water in the adsorbent to reach equi librium with the partial pressure of the water in the surrounding gas, with 885 886 CHAPTER 38 1956 Guide Dehumidification by Sorbent Materials 887 the result that water is extracted by the adsorbent and its weight increased, Silica Gel while the moisture content of the gas is correspondingly reduced. (The Silica gel is a prepared form of silicon dioxide (silica) having an ex adsorbent is said to be saturated for a given condition when equilibrium is tremely porous structure which makes it an efficient adsorbent. It is attained.) The weight of water a given adsorbent will extract is dependent made by mixing predetermined concentrations of an acid, such as sulfuric upon the relative humidity (ratio of the partial pressure in the gas to the acid, and a soluble silicate, usually sodium silicate, and allowing the mix saturation pressure at a given temperature) and the temperature of the ture to set to a jelly-like mass called hydrogel. The product takes its adsorbent. The process is reversible; if the temperature of the adsorbent name from its condition as a colloid at this stage of its manufacture. After is raised until the vapor pressure of the adsorbed water becomes greater setting, the hydrogel is broken into small lumps, washed, dried/crushed, than the partial pressure of the vapor in the surrounding atmosphere, water and screened to the desired particle sizes and then given a final heat treat will be released by the adsorbent. After the adsorbent cools to room tem ment or activation. The surface area of silica gel has been found to be perature, for instance, the vapor pressure of the water in the adsorbent falls in excess of 50,000 sq ft per cubic inch of product. Silica gel has high below the partial pressure of the vapor in the atmosphere, and the adsorbent adsorptive capacity per unit weight, and may be reactivated repeatedly at . will again start extracting water. The elimination of water by the addition temperatures up to 600 F. Reactivation is generally accomplished by of heat is known as reactivation, and is a means of regenerating the ad- . blowing gases through the silica gel at approximately 300 F, or by heating sorbent so that it may be used repeatedly. in a well vented oven maintained at this temperature until no more mois !' Adsorption is proportional to the amount of surface (internal and exter ture is given off. Silica gel is a high purity, rugged, non-toxic, heat-stable nal) of the sorbent. The materials that are used commercially as solid material, having a specific heat of 0.2, and is most inert. There is no adsorbents have a porous structure of sub-microscopic dimensions, which change in the size or shapie of the particles as it becomes saturated, and no gives them extensive surface area. An adsorbent should meet the follow corrosive or injurious compounds are given off. It is available commer ing requirements in order to be satisfactory for dehumidification purposes: cially in a number of grades, ranging in particle size from a 3 to 8 mesh product to an impalpable powder passing through a 325 mesh screen. The 1. Have a high adsorptive capacity under normal atmospheric conditions. product generally used for dehumidification applications has a particle size 2. Be chemically stable, resisting contamination from impurities. of 6 to, 12 mesh, and a bulk density of between 40 and 45 lb per cubic foot. 3. Be physically rugged to resist breakdown from handling and use. 4. Be capable of reactivation at temperatures generally obtainable. Activated Bauxite ' 5. Be heat-stable at reactivation temperatures. 6. Have a weight per unit Volume such as. to avoid excessive bulk. 7. Be available at reasonable cost. Activated bauxites are certain natural products which, after controlled heat treatment, have properties which make them suitable for use as solid adsorbents. They are marketed under different trade names by several Activated Alumina Activated alumina is a granular porous material which removes by ad sorption substantially 100 percent of the moisture from gases, vapors, and certain liquids. Regeneration or reactivation may be accomplished by em ploying a heating medium at temperatures ranging from 350 to 600 F. After many cycles of adsorption and reactivation it is substantially as effective as originally, and retains its original size and shape. Activated alumina is produced by chemically controlled precipitation from a sodium aluminate solution resulting from the extraction of alumina from bauxite by the Bayer process. By subsequent processes this pre cipitate is converted into a highly porous adsorptive material. It is low in iron and silica, each normally less than 1/10 of 1 percent. Commer cially produced material is uniform in analysis and physical form. Activated alumina is a partially dehydrated aluminum trihydrate con taining about 7 percent water and small amounts of soda, oxides of iron, silicon, and titanium, as well as very minor amounts of other elements indicated spectrographically. Substantially all of the soda is. combined with silica and alumina as an insoluble constituent. Activated alumina is inert chemically to most gases and vapors, is non toxic, and will not soften, swell or disintegrate when immersed in water. High resistance to shock and abrasion is one of its more important physi cal characteristics. Commercial sizes range from a powder passing through 300 mesh screen to particles 1 in. in diameter. The sizes commonly used are 8-14 mesh and. in. to 8 mesh. The average weight for most forms is 50 lb per cubic foot. Its high degree of purity warrants classification among commercially pure chemicals. processors. The activated bauxites consist primarily of AI4O3, Fe^Oi, SiOi, TiOi, and H/) in varying percentages. The surface area, adsorptive capacity, and other properties of the several products differ to some extent, depending upon the source of the original material and its subsequent treatment. The available activated bauxites are durable products having a specific heat of about 0.24, and can be regenerated at temperatures be tween 300 F and 500 F. They are usually supplied in a number of particle sizes, and have a bulk density of between 55 and 65 lb per cubic foot. There are other solid substances having marked adsorbent properties, but details concerning them are not available. DEHUMIDIFICATION BY SOLID ADSORBENTS Since adsorption is primarily a condensation process, heat, equivalent to the latent heat of evaporation of the vapor, plus the heat of wetting (which is an additional amount of heat, depending upon the vapor being adsorbed and the adsorbent used) is liberated. The sum of the latent heat of evap oration and the heat of wetting is known as the heat of adsorption. During - adsorption it might be said that latent heat is transformed into sensible heat, which is dissipated into the adsorbent, into the metal of the adsorbent, container, and into the gas mixture, resulting in a rise in temperature. Fig. 1 shows the relationship between temperature, vapor pressure, and moisture content of a solid adsorbent. These curves indicate the general performance of solid adsorbents, although the exact values vary for the different adsorbents, and may vary even for different types of the same compound. The effects of vapor pressure and temperature upon the mois ture content of an adsorbent may be observed by referring to Fig. 1. When the given type of sQlid adsorbent is in equilibrium with air having a dry- I ! 888 CHAPTER 38 1956 Guide bulb temperature of 70 F and 70 percent relative humidity, that is, having a dew-point of 60 F or a water vapor pressure of 13.2 mm Hg, the water content of the adsorbents 33 percent. With air having the same dry-bulb .i temperature and a dew-point of 37 F, or a vapor pressure of 5.6 mm Hg, i]1 the water content is 20 percent. The increase in weight for an activated solid adsorbent, after it reaches equilibrium with a gas of any given water vapor content, may be found by subtracting the residual water content (for example 6 percent) from the equilibrium value. In the case of the two examples cited, the actual water gain would be 27 percent and 14 percent, ' '#* & *(*( Fig. 1. Temperature--Vapor Pressure--Concentration Characteristics for a Typical Fig. 2. A Typical Solid Adsorbent Debumidification Unit Air Flow Diagram Solid Adsorbent respectively. The effect of temperature upon the adsorptive capacity may !i be observed by following the 5.6 mm Hg vapor pressure line. At a tem perature of 70 F, the moisture content of the adsorbent is 20 percent, while at 100 F, the equilibrium water content is 11 percent. ' In practice, the temperature rise in the dehumidified air caused by the i adsorption heat, is approximately 10 deg F for each grain of moisture re moved per cubic foot of air at atmospheric pressure. This temperature i rise occurs progressively through the adsorbent bed, and is an important consideration in predetermining the performance of a given design of ap paratus. Data such as these, together with information covering other characteristics such as specific heat, resistance to air flow, etc., are of value in the basic design of adsorption apparatus. In the solution of air con ditioning problems, however, reference must be made to performance data on established apparatus designs. DEHUMIDIFICATION EQUIPMENT USING SOLID ADSORBENTS A typical solid adsorbent dehumidification unit air flow diagram is shown in Fig. 2. The apparatus consists of two adsorbent containers (adsorbers) Dehumidification by Sorbent Materials 889 with necessary interconnecting piping, valves, and auxiliaries consisting of filters, fans, activation air heater, controls, and, in some instances, a cooler for the dehumidified air. Before entering the adsorber, the air to be de humidified is drawn into a filter to remove dust and other impurities. In passing through the adsorbent bed, the moisture content of the air is reduced and the dehumidified air is then introduced into the space or proc ess requiring it. While, the first adsorber is dehumidifying the air, the second adsorber is being reactivated by means of outside air drawn through a filter and heater in which its temperature is raised to 300 F. The heat may be supplied by electric heating elements, steam coils, the direct prod ucts of combustion of gas, oil, waste heat, or any other convenient source. In passing through the adsorbent bed, the hot gases supply the necessary heat for releasing adsorbed water from the adsorbent, and then carry it out of the adsorber to the activation gas outlet, where it is exhausted to the outside atmosphere. In some instances a thermostat placed in the acti vation outlet connection shuts off the activation fan and heater when the adsorbent is completely reactivated, as indicated by a rapid rise in the temperature of the outlet activation gas. The length of the adsorption period may be controlled by a timing device which changes the Valves or dampers from the adserbing to the activating position, or by a humidistat located in the dehumidified air connection or in the dehumidified space. The majority of commercial units are time controlled. In applications where a continuous stream of dehumidified air is not required, a single adsorber type unit may be used, while in other cases where a continuous stream'of dehumidified air is required, a multiple num ber of adsorbers, or even a continuously rotating system, may be used. If the air to be dehumidified is very warm, and especially where exceed ingly low dew-point dehumidified air is required, it is advantageous to install a pre-cooler to reduce the temperature of the inlet air. In this way the working temperature in the adsorber is lowered, and the overall per formance appreciably increased. Some equipment manufacturers install cooling coils in the adsorbent beds for the same purpose, while others divide the adsorbent bed and install coolers between the sections. Dehumidification equipment is employed to the best advantage where the air conditioning problem is primarily one of obtaining low relative humidity control rather than temperature control. This requirement is found in the case of the preservation of inactive naval vessels where the interior of the ship must be kept at a relative humidity below 30 percent to avoid corrosion, mold, mildew, and other moisture damage that occurs at humidities substantially in excess of this figure. Other advantageous applications for dehumidification systems are found in industrial processes where low relative humidity atmospheres are required during the manufac ture, as well as for preservation of the finished products. Dehumidification with cooling may be used to advantage in work-rooms or other spaces occupied by humans, where the moisture load is high in comparison to the sensible heat load. In many instances, where independent control of tem perature and humidity is important, dehumidification is used to advantage in conjunction with cooling. ABSORBENTS Any absorbent substance may be used as a dehumidifying agent if it has a vapor pressure with respect to water lower than the partial pressure of the water vapor in the mixture from which the moisture is to be removed. Solid Absorbents. The substances used are generally the solid forms of the liquid absorbents. At present they are used principally in small desiccating chambers 890 CHAPTER 38 1956 Guide and in small dryers of the cartridge type, through which air is forced under presure. Calcium chloride is frequently used because of low cost. , Liquid Absorbents. These are primarily water solutions of materials in which the vapor pressure is reduced to a suitable level by controlling the concentration and temperature of the dehumidifying solution. Water solutions of the chlorides or bro mides of various inorganic elements and certain organic compounds, are the liquid absorbents used in air conditioning. In addition to having suitable water vapor pressure characteristics, an absorbent, to be satisfactory, should also meet the following requirements: . 1. Be widely available at low cost. 2. Be non-corrosive, odorless, non-toxic, and non-inflammable. 3. Be chemically inert against any impurities in the air stream. 4. Be stable over the range of use. 5. Must not precipitate at the lowest temperature to which the apparatus is exposed. 6. Have low viscosity, and be capable of being economically regenerated or con centrated after having been diluted by the moisture absorbed. DEHUMroiFTCATION BY LIQUID ABSORBENTS In liquid absorption systems the air-vapor stream is brought into intimate contact with the absorbent solution by passing the air stream through a tower into which the brine is introduced as a finely divided spray, or by passing the air through a tower or contactor which is continuously sprayed with the brine, thereby presenting a large surface of absorbent to the air to be dehumidified. The difference in the partial pressure of the water in the concentrated brine and the partial pressure of the water vapor in the air, causes the water, vapor to be given up by the air to the brine until equilib rium is approached. The water vapor is condensed during this operation, and its addition to the absorbent solution results in a decrease in the concentration of the solution. As the water vapor condenses, the latent heat of condensation is released in the absorbent solution. An additional, frequently appreciable, quantity of heat known as the heat of solution or heat of mixing, is also released. The heat released as the result of conden sation and mixing, is directly transferred to the liquid absorbent, equip ment, and air being dehumidified, thereby causing a rise in temperature. A modified system includes means for removing heat from the absorbent solution, either within the contactor or externally. Thus the temperature of the solution may be higher than, equal to, or lower than that of the air, depending on the chemical employed and the ultimate use of the dehumidi fied air. Fig. 3 shows the relationship between temperature, vapor pressure and moisture content of a typical absorbent of the inorganic type. These curves indicate the general performance of such absorbents, although the exact values vary for the different compounds. When the given absorbent is in equilibrium with air having a dry-bulb temperature of 70 F and a relative humidity of 70 percent, i.e., having a dew-point of 60 F, or a water vapor pressure of 13.2 mm Hg, the water content of the solution is 4.8 lb water per pound of anhydrous absorbent. With air having the same dry-bulb temperature and a dew-point of 37 F, or a vapor pressure of 5.6 mm Hg, the water content is 2.1 lb per pound of absorbent. Therefore, when a solution of 2.1 lb water per pound of absor bent is exposed to an atmosphere of 70 F and 70 percent relative humidity, it will absorb an additional 2.7 lb of water in reaching equilibrium. The effect of temperature on the absorptive capacity may be observed by following a constant vapor pressure line in Fig. 3. At a temperature of 70 F and a vapor pressure of 13.2 mm Hg, the moisture content is 4.8 lb Dehumidification by Sorbent Materials 891 water per pound of absorbent. At 100 F, the moisture content is 1.8 lb water per pound of absorbent. " Fig. 4 shows the relationship between temperature, vapor pressure, and moisture content of a typical liquid absorbent of the organic type. DEHUMIDIFICATION EQUIPMENT USING LIQUID ABSORBENTS One type of system utilizing liquid absorbents includes an external inter changer having essential parts consisting of a liquid contactor, a solution Fig. 3. Temperature--Vapor Pressure--Concbntration Characteristics for a Typical Inorganic Absorbent (Halogen Salt Group) Fig. 4. Temperature--Vapor Pressure--Concentration Characteristics for a Typical Organic Liquid Absorbent concentrator, a solution heater and a cooling coil, all as shown in Fig. 5. The contactor and cooling coil are located in the wet air stream. The air to be conditioned is brought into contact with a liquid absorbent having a vapor pressure below that of the entering air, resulting in a transfer of moisture from the air to the brine solution. This results in a conversion of latent heat to sensible heat, which raises the solution temperature and consequently, the air temperature. The temperature change of the air being processed is determined by the cooling water temperature and the amount of moisture removed in the equipment. Control of leaving air temperature may be obtained by precooling the absorbent solution in a suitable surface cooler, by tap, well, or. chilled water. The excess water of condensation, which dilutes the liquid absorbent, is removed in the solution concentrator. This is a low pressure steam heat exchanger which over-concentrates a portion of the weak liquor, and re turns it to the main reservoir for re-cycling. The concentrator operates m the manner of an evaporative condenser, whereby moisture is evaporated from the liquid absorbent by the heating coils into a stream of regeneration air taken from, and rejected to, the outside atmosphere. Low pressure 892 CHAPTER 38 1956 Guide steam is normally used for heating the liquid absorbent. When it is de sirable or necessary to use gas or electricity, an auxiliary low pressure steam boiler is usually added to the equipment. Concentrators operating on a simple boiler principle have not as yet been commercially practical. It should be noted that the solution concentration phase is the reverse of the absorption process. During concentration, the aqueous vapor pres sure of the solution is greater than that of the surrounding.air, while during dehumidification, the reverse is the case. Utilization of this principle per mits winter humidification by heating (instead of cooling) the solution pumped to the contactor. Water is thereby evaporated into, rather than condensed out of, the conditioned air stream. This requires dilution of the liquid absorber externally to the contactor. CALCULATION OF MOISTURE LOAD Calculation of the dehumidification required to maintain' lower than nonnal'moisture content in a given room begins with determination of the Cooling coil and Fio. 5. Liquid Absobbent Equipment in Which Solution Cooleh and Contractor are Combined rate of moisture gain in the room from all sources. It is common practice, when maintaining a low humidity ratio, to recirculate a large percentage of the air in the room through the dehumidifier, and to add only enough out side air to meet the needs of the problem. The humidity ratio of the mixture of outside and recirculated air and the dehumidifier performance data can be used to calculate the humidity ratio of the air leaving the de humidifier. The difference between the humidity ratio of the air in the room and that of the dehumidified air entering the room represents the effective dehumidification per pound of air. The rate of internal moisture gain in grains per minute, divided by the effective dehumidification in grains per pound of air, equals the air quantity required in pounds per minute. The following typical example using arbitrary values shows a general method of determining the dehumicfifying requirements. Sensible heat determination considerations are discussed in other chapters, and are pur posely omitted here. Example 1: A solid absorbent dehumidifier having performance characteristics as shown in Fig. 6 is to be used to maintain inside conditions of 73 F and 20 percent rela tive humidity, 24.1 grains per pound of dry air, 30 F dew-point, in a room 20 ft x 30 ft x 10 ft high, having a total wall, ceiling, and floor surface area of 2200 sq ft. Outside design conditions are 72 F dew-point (118.4 grains per pound). Dehumidification by Sorbent Materials 893 Internal sources of moisture are: 4 occupants; an open natural gas burner using 15 cu ft of natural gas per hour; an open top water tank, having an area of 2 sq ft ex posed surface, in which water is maintained at 87 F, with air movement over the water surface being 100 fpm. Determine the quantity and condition of the dehumidified air to be supplied to the room. Solution: The internal moisture gain consists of items 1 to 5. 1. From occupants: 4 X 1800/60 = 1800 grains per person per hour is obtained from Fig. 7, Chapter 6, by interpolation between curves C and D. 2. From burned gas: . 15 X 650/60 = 1 cu ft natural gas produces approximately 650 grains of moisture. Crains per Mi1n2u0te 162 3. From exposed water surface: 2 X 20 = Evaporation from water surface is assumed to be 20 grains per (minute) (square foot) at 87 F water with air movement of 100 fpm. 40 4. From infiltration: __ X (118.4 -- 24.1) = vl) 1C li>w * One air change, 6000 cu ft, assumed per hour (see Chapter 11). ------------ 5. Moisture transmitted through room surface: 2200 6U X 3 X (0.783 - 0.176) = Permeability assumed to be 3 grains per (square foot) (hour) (inch Hg vapor pressure difference on two sides of wall). 696 . 67 Total moisture gain,from internal sources 1085 Let q be the air delivered to the room, pounds per minute. Let it be assumed for this problem that 85 percent of the air is recirculated and 15 percent is outside air. Enough air must be supplied to replace leakage from the system or to satisfy normal ventilating requirements for the occupants of the room as given in Chapter 6, which ever is greater. The amount is estimated from experience or obtained by test. The humidity ratio of the mixture of recirculated and outside air entering the dehumidifier is then : 0.85?(24.1) + 0.15?(118.4) 0.85? + 0.15j 38.3 grains per pound entering dehumidifier. For the dehumidifier whose performance is shown in Fig. 6, for 38.3 grains per pound in entering air, the leaving humidity ratio will be 6.5 grains per pound. Effective dehumidification in the room is 24.1 -- 6.5 or 17.6 grains per pound of supply air. ,m,,, en q -- 11-078-.5g6-gg--rraaii:n--nss pp-ee--rr--mp--o-i-ni-m-u3dt-e = 61.6 lb air per mi.nut,e .. minimum th.,at,must, b,e supplied to the room to maintain 30 F dew point. . Note that this figure represents the minimum requirement for the arbitrary condi tions set forth and that in practice, safety margins should be added to the outside air percentage figure and to the calculated internal moisture gain. VAPOR TRANSFER TO DEHUMIDIFIED SPACE The walls enclosing a dehumidified space are subjected to a vapor pres sure differential. The pressure of the vapor outside the walls tends to force moisture' through the walls into the dehumidified zone of relatively low vapor pressure. As this .process can be an unnecessary load on the CHAPTER 38 1956 Guide 894 Fia. 6. Performance Data fob Typical Commercial Solid Adsorbent Dehumidifieb dehumidifying equipment, provisions should be made for keeping the vapor transfer to a minimum. Also, if the space is cooled below the ambient dew point, there is a possibility that condensation may occur within the walls, unless vapor transfer is_controlled. For these reasons a vapor bar rier should be located within the wall construction as near to the high vapor pressure side as feasible. To be effective, a barrier must be continuous and should be so located within the structure that it mil be protected from rupture. (See Chapter 10, Moisture In Building Construction). BIBLIOGRAPHY Design and Use of Adsorptive Units, by R. C. Amero, J. W. Moore and R. G. Capell (Chemical and Engineering Progress, Vol. 43, No. 7, July 1947, pp. 349-370). Note: A .fulAl bnibAlnioaglyrasipshMyeisthiondclufodrePdriendtihctiisngarBtieclhea.vior of Solid Adsorbents in Solid Sorption Dehumidifiers, by W.'L. Ross and E. R. McLaughlin (ASHAE Transactions, Vol: 61, 1955,p. 321). CHAPTER 39 AUTOMATIC CONTROL Fundamentals: Type of Control Systems and Action, System Components, Controlled Devices, Auxiliary Control Equipment; Control Applications: Automatic Fuel Burning, Residential Heating and Air Conditioning, Zoning, Individual Room Control, Central-Fan Systems, Outdoor Air, Reheater Coil, Humidity, Cooling and Dehumidification, Static Pressure, Space Condition, Typical System, Unit Heaters, Unit Ventilators; Design Coordination: Size of Controlled Area, Equipment Selection and Layout, Location of Space Controllers, Control of Steam or Water Flow. PRESENT-day standards of comfort combined with the capacity and rapid response of modem heating and cooling equipment make auto matic controls an essential part of heating, ventilating, and air conditioning systems. These automatic controls respond to variables such as tempera ture, relative humidity, and pressure. They operate individually or in sequence to maintain the desired conditions throughout the system and in the occupied space. A factor which has made the subject of automatic control somewhat confusing has been the matter of terminology. Many different expressions or words have sometimes been used to convey a single idea or concept. This chapter, therefore, attempts to use and define the terms which are most common and suitable so that they will be more pre cise and readily understood. The terms and definitions used are also se lected so as to conform, as nearly as possible, to automatic control termin ology used by engineers in other realms of engineering endeavor. PART I--FUNDAMENTALS OF AUTOMATIC CONTROL A control system, Fig. 1, consists essentially of (1) a controller, (2) a con trolled device, and (3) a source of energy. A controller is a device which measures a variable condition such as temperature, humidity, pressure, and liquid level, and produces a suitable action or impulse for transmission to the controlled devices. Thermostats, humidistats, and pressure con trollers are examples. A controlled device reacts to the impulse received from a controller and varies the flow of the control agent. It may be a valve, damper, electric relay, or a motor driving a pump, fan, etc. . The control agent is the medium manipulated by the controlled device. It may be air or gas flowing through a damper, gas, steam, water, etc., flowing through a valve, or an electric current. The controlled variable is the condition such as temperature, humidity, or pres sure, being controlled. Most control sytems, of which Fig. 1 is typical, form a closed loop. That is, the controller measures and responds to changes in the controlled vari able and actuates the controlled device to bring about an opposite change which is again measured by the controller. This system of transmitting information about the results of an action or operation back to its origin is known as feedback, and makes true automatic control possible. An open-loop system is sometimes employed in control circuits, but it does not provide complete control. An outdoor thermostat arranged to control the flow of heat to a building in proportion to the load caused by 895 ! I i I-!! f( !t changes in outdoor temperature is an example. This system depends for its operation on a prearranged relationship between outdoor temperature and heat input to the building, and room temperature has no effect on the controller. As there is no feedback, the control corrects only for those disturbances of room temperature caused by changes in outdoor temperature. TYPES OF CONTROL SYSTEMS Control systems are divided into five main groups according to the pri mary source of energy: 1. A self-contained system combines the controller and controlled device in one unit and employs the power of the measuring system to effect the necessary corrective action. The measuring system derives its energy from the process under control without amplification by any auxiliary source of energy, and may be of the sealedbellows or remote-bulb type as described under Types of Measuring Elements SOURCE OP ENEROY CONTROLLER (thermostat) CONTROLLED . ''variable (air temperature) MEASURING ELEMENT (REMOTE BULB) /fFeEED BACK CONTROLLED ni DDiEVICE (VALVE) CONTROL AGENT (STEAM) Fig. 1. Essentials op a Control System Temperature changes at the bellowsur the remote bulb result in pressure or volume changes of the enclosed media which are transmitted directly to the operating device ) of the valve or damper. 2. A pneumatic system utilizes compressed air, usually at a pressure of 15 to 25 psig, as a source of energy. This is supplied to the controller which in turn regulates the pressure supplied to the controlled device. 3. A hydraulic system utilizes a suitable liquid under pressure as the source of energy. The pressure often is considerably higher than in a pneumatic system, but in other respects the systems are similar. Hydraulic systems find their chief use in applications where large forces are required for operation of the controlled devices, 4. An electric system utlilizes electric energy, either low or line voltage as the energy source. The electric energy supplied to the controlled device is regulated by the controller either directly or through relays. 5. Ah electronic system also utilizes electric energy, but employs an electronic amplifier to increase the minute voltage variations of the measuring element to values required for operation of standard electrically-controlled devices. Measuring elements usually are of the resistance type, but thermocouples also are employed. Combination electronic-pneumatic systems utilize compressed air for operation of the controlled device by converting the output of the electronic amplifier into suitable air pressure changes by means of an electronic-pneumatic transducer. . - ` \ ... ' - :: `C. y TYPES OF CONTROL ACTION ^ Control action may be divided into five types: ;"` 1. Two-position action, Fig. 2, is the type in which the controlled device can be positioned only to a maximum or minimum position, or can be either on or off. A thermostat which opens and closes a valve, or starts and stops a burner, is an example. 2. Timed two-position action is a common variation of two-position control action in which the time of on periods are prematurely shortened. This type of action usu ally is employed only in room thermostats, and is accomplished by a heater element .. " -' Automatic - Control 897 in the thermostat which is energized during the on periods. The percentage of time on is varied in proportion to the system load. . Controller differential applying to two-position control action, is the difference between the setting at which the controller operates to one position and the setting at which it operates to the other position. As an example, if a pressure controller starts a pump at 12 psi and stops it at 15 psi, the differential is 3 psi. It is sometimes APF ACE APW Fig. 2. Two-Position Control Fig. 3. o k ec oo z_PjFfE.BENTIAL Floating Control Showing Variations in Controlled Variable as Load Changes Pig. 4. Proportional Control Showing Variations in Controlled Variable as Load Changes uesirabie to have a controller in which the differential can be changed by manual ad justment. This is designated as an adjustable differential. 3. Floating action, Fig. 3, is the type, as with two-position action, where the con troller can perform only two operations: moving the controlled device usually at a constant rate either towards its open or its closed position. Generally there is a neutral zone between the two positions which allows the controlled device to stop at any position whenever the controlled variable iB within the differential of the con troller. When the controlled variable gets outside the differential of the controller, the controller moves the controlled device in the proper direction. An example of floating control is a fire box draft controller positioning a damper in the breeching of a boiler. 4. Proportional action, Fig. 4, is the type where the controlled device is positioned proportionately in response to slight changes in the controlled variable. It does not run through its complete stroke, as is the case with two-position control, nor does it continue to move until the change in the controlled variable resulting from that movement is felt by the controller, as is the case with floating control, but it immedi ately assumes a position in proportion to the system requirement. . An example of porportional control is a thermostat in a fan discharge duct actuat ing an automatic valve in the steam supply to a coil to regulate the air temperature leaving the coil. This control would be similar to that shown in Fig. 1. Throttling range is the total amount of change in the controlled variable required 898 CHAPTER 39 1956 Guide to move the controlled device through its complete stroke, from one extreme to the other. It is often adjustable to meet job requirements. ! Set Point is the value at which the controller is set and represents thedesired value of the controlled variable. Control Point is the actual value of the controlled variable at which the instrument is controlling. It will vary within the throttling range of the controller according to the demand on the system and other variables. Offset is the difference between the set point and the actual control point under stable conditions. This is sometimes also called drift, deviation, or droop. 5. Proportional plus Automatic Reset Action, Fig. 5 combines floating action with proportional action to achieve both the stability of proportional control, with a relatively wide throttling range, and the invariable control point of floating control. The system functions the same as proportional action, the automatic reset serving to shift the control point back to the set point whenever any offset occurs. Reset rale is the number of times per minute the proportional action is duplicated by the reset action, and usually is expressed as repeats per minute. The reset rate in most controllers is adjustable and must be carefully matched to the system charac teristics to avoid unstable operation. Because automatic reset is necessarily slowacting, it should be used only when load changes are of reasonably long duration and when the maximum offset resulting from proportional control alone is outside of acceptable limits. Figs. 4 and 5 show the results of rather abrupt demand changes, which usually result in two or three cycles before stability is restored. More gradual demand changes will result in a smoother curve. AUTOMATIC CONTROL SYSTEM COMPONENTS In addition to controllers and controlled devices, many control systems include auxiliary apparatus such as switches and relays of various kinds, clocks or timers, thermometers, gauges, pilot lights, and other indicators for observing the operation of the system. Only those more commonly used will be described here. Controllers Automatic controllers have both a measuring element and a controlling element. The measuring element measures changes in the controlled variable and produces a proportional effect on the controlling element. This effect usually is a. change in position, force or electrical resistance. The controlling element converts the effect produced by the measuring element into an effect suitable for operation of the controlled device. (In self-contained controllers the measuring element produces a force which is directly applied to the controlled device. In pneumatic or electric con trollers the controlling element, regulates the application of energy such as compressed air or electricity.) Types of Measuring Elements Temperature measuring elements usually consist of (1) a bimetal strip, (2) a rod and tube of dissimilar metals, (3) a sealed bellows, with or without a remote bulb or (4) an electrical resistance. 1. A bimetal element is composed of two thin strips of dissimilar metals fused to gether. Because the two metals have different coefficients of thermal expansion, the element bends as the temperature varies and produces a change in position. De pending on the space available and the movement required, it may be in the form o a straight strip, U-shaped, or wound into a spiral. This element Ends its most com mon application in room thermostats, but is also used in insertion and immersion thermostats. .. 2. A rod-and-tube element consists of a high-expansion metal tube inside of which is a low-expansion rod with one end attached to the rear of the tube. The tube changes length with changes in temperature, causing the free end of the rod to move, the Automatic Control . . . - 399 rod-and-tube,element is commonly employed .on certain types of insertion and im mersion thermostats. ....... . 3. A sealed bellows-element is either vapor filled, gas filled, or liquid filled, after being evacuated of air. Changes of temperature cause changes in pressure or volume of the gas or liquid, resulting in a change in force or a movement. This element is often employed in room thermostats. ... . . A remole-bulb element is a sealed bellows or diaphragm to which a bulb or capsule is attached by means of a capillary tube, the entire system being filled with vapor, gas or liquid. Changes of temperature at the bulb result in changes of pressure or volume which are communicated to the bellows or diaphragm through the capillary tube. The remote-bulb element is useful where the temperature measuring point is remote from the desired thermostat location. It usually is provided with fittings suitable for insertion into a duct or into a pipe or tank. * 4. A resistance element is made of wire whose electrical resistance changes with temperature changes. It is used with electronic controllers. It is available in forms suitable for measuring room temperature or for insertion into a duct or into a pipe or tank. ^^CONTROL POINT set POINT ---------- TIME------- -- r THROTTLING RANGE t Fig. 5. Proportional Plus Automatic Reset Control Showing How Control Point is Returned to Set Point after a Load Change Humidity measuring elements are made of (1) hygroscopic organic ma terials or (2) an electrical resistance. 1. An organic element usually is made of human hair, wood, paper, or animal membrane. Changes in relative humidity cause the element to expand and contract. 2. A resistance element, for use with electronic controllers, frequently consists of a thin coating of hygroscopic salt on an insulating form. The resistance of the salt varies with the relative humidity. Pressure measuring elements can be divided into one of two general classes depending upon pressure range. 1 For pressures or vacuums measured in pounds per square inch or inches of mer cury, the element usually is a bellows, diaphragm, or Bourdon tube. One side of the element may be open to atmosphere in which case the element responds to pressures above or below atmospheric. A differential pressure element has connections to both sides so that it will respond to the difference between two pressures. 2. For low ranges of pressure or vacuum which are usually measured in inches of water, such as the static pressure in an air duct, the measuring element may be an inverted bell immersed in oil, a large slack diaphragm, or a large flexible metal bel lows. The element usually is of the differential type, and when employed in con junction with orifices, pitot tubes, and similar accessories, may be used to measure now, velocity or liquid level as well as static pressure. Measuring elements for other purposes, such as flame detection or for measuring smoke density, specific gravity, C02, CO, etc., often are neces sary for the complete control of a heating, ventilating or air conditioning system. Types of Controlling Elements Controlling elements differ because some regulate the application of pneumatic energy while others regulate the application of electrical energy, they also differ according to the type of control action produced. 900 CHAPTER 39 1956 Guide An electric controlling element is used in several of the common types of control action. , ' For two-position control it may simply make and break an electrical contact, to start a burner, motor, etc., or to actuate a spring-return valve or damper operator. Another type makes one contact while breaking another and is used to control uni directional valve or damper operators. Either type may be used for timed two-posi tion action by the addition of a small resistance heater. Forfloating control two contacts are employed, but there is a neutral zone between the two contacts where neither is made. This type is commonly used with reversible valve or damper operators. For proportional control a contact is moved across a potentiometer to vary the volt age applied to a relay. The relay controls the operation of a reversible valve or damper operator and is re-balanced as the controlled device is positioned. In another arrangement the controlling element has two contacts and a neutral zone as de scribed for floating control and is re-balanced by a small solenoid which is energized by a variable voltage feedback from the reversible valve or damper operator which it positions. _ An electronic controlling element consists of an electronic amplifier and an electric relay or relays. The amplifier receives the minute electrical signals from the meas uring element and amplifies them sufficiently to actuate the relays. The electronic controlling element may be two-position, floating, or proportional, depending upon the amplifier and relay arrangement. A pneumatic controlling element is most often of the proportional-action type but may also be used for the other types of control action. It may be classified as non relay type and relay type. A non-relay type of penumatic controlling element is the simplest form and em ploys a restricted air supply and a nozzle or control port. The measuring element varies the opening of the nozzle and the resulting variable pressure is applied to the controlled device. This type is limited to applications requiring small volumes of air. . In a relay-type pneumatic controlling element the relay contains both a supply and an exhaust valve usually arranged so that the exhaust valve must close before the supply valve opens. Both valves are closed except when the control pressure is required to change. The variable force for operating the valves may be supplied directly by the measuring element or it may be supplied by a diaphragm actuated by air pressure from a very small nozzle and restrictor arrangement, this air pressure being varied by the measuring element. In either case the control pressure, operat ing on a diaphragm within the relay, produces a force which balances the force pro duced by the measuring element. Pneumatic controllers may be either direct or reverse acting. A direct-acting controller increases the control air pressure as the controlled vari able increases. For example a direct-acting thermostat increases the air pressure as the temperature increases. A reverse-acting controller decreases the control air pressure as the controlled vari able increases. A reverse-acting thermostat decreases the air pressure as the tem perature increases. Indicating and Recording F eatures Controllers may be of the indicating or recording type. The non-indicating controller is most common in heating, ventilating, and air con ditioning work, and includes all those in which the measuring element does not pro vide a visual indication of the value of the controlled variable. If an indication is desired, a separate thermometer, relative humidity indicator, pressure gauge, etc, is required. With room thermostats, for example, a separate thermometer often is attached to the cover. An indicating controller has a pointer added to the measuring element or attached to it by a linkage so that the value of the controlled variable is indicated on a suitable scale. A recording controller is similar to an indicating controller except that the indicat ing pointer is replaced by a recording pen which provides a permanent record on a chart driven by a clockmotor. Proportional band is a term used in connection with indicating and recording con- Automatic Control 901 trollers and has the same meaning as throttling range. It is usually expressed in per cent of the scale or chart range of the controller. Types of Controllers '' Controllers are mainly (1) thermostats, (2) humidistats, and (3) pres sure types. 1. Many thermostats are of the simple, single-purpose type, but there are many others for various special purposes. Various types are indicated in paragraphs (a) to (k) which follow. a. The room type is designed for mounting on a wall and responds to room tempera ture. b. The insertion type is designed for mounting on a duct with its measuring ele ment extending into the duct. c. The immersion type is designed for mountingon a pipe ortank. It has a fluid-tight connection to allow the measuring element to extend into the fluid. A separable socket or well is often used with immersion thermostats to avoid the need for draining the system when removal of the thermostat is required. Since the separable socket will reduce the response rate of the thermostat, the socket should be no heavier than necessary and should fit snugly around the element. d. The remote bulb type is designed for applications where the point of temperature measurement is at some distance from the desired thermostat location. It is often used for centralized panel mounting of the controller. The remote bulb element may be of either the insertion or immersion type. e. The surface type is designed for mounting on and measuring the temperature of a pipe or similar surface. f. The day-night, or dual room thermostat controls at a reduced temperature at night. It may be indexed (changed from day to night operation) individually or in groups from a remote point by a manual or time switch. Some electric types have an individual clock and switch built into the thermostat. g. The pneumatic day-night thermostat uses a two-pressure air supply system, the two pressures often being 13 and 17 psi or 15 and 20 psi. Changing the pressure at a central point from one value to the other actuates switching devices in the thermostat and indexes them from day to night or vice versa, Supply-air mains often are divided into two or more circuits so that switching can be accomplished in various areas of the building at different times, in accordance with use. For example a school build ing may have the separate circuits: for classrooms, offices and administrative areas, auditorium, and gymnasium and locker rooms. h. The heating-cooling or summer-winter thermostat can have its action reversed and, if desired, have its set point changed by the indexing means. It is used to actuate controlled devices, such as valves or dampers, that regulate a heating source at one time and a cooling source at another time. It is often indexed in groups man ually by a switch or automatically by a thermostat measuring the temperature of the control agent, the outdoor temperature, or other suitable variable. i. The pneumatic healing-cooling thermostat uses a two-pressure air supply system as described for day-night thermostats. j. A two-stage thermostat is arranged to operate in two successive steps. k. A submaster thermostat has its set point raised or lowered over a predetermined range in accordance with variations in output from a master controller. The master controller can be a thermostat, manual switch, pressure controller or similar device. For example, a master thermostat measuring outdoor air temperature can be used to readjust a submaster thermostat controlling the water temperature, in a heat ing system. Master-submaster combinations are sometimes designated as single cascade action. When such action is accomplished by a single thermostat having more than one measuring element, it is known as compensated control. 2. Humidistats are of either the room or insertion type. Submaster humidistats of either type are sometimes used in conjunction with an outdoor master thermostat to reduce the humidity in cold weather and prevent condensation on windows. A wet-bulb thermostat is often used for humidity control in conjunction with proper control of the dry-bulb temperature. A wick or other means for keeping the bulb wet is required, and rapid air motion to assure a true wet-bulb measurement is es sential. 3. A pressure or static-pressure controller is made for mounting directly on a pipe 902 CHAPTER 39 1956 Guide or remotely on a panel or wall. A small pipe or tube may be used for transmitting the pressure signals to the instrument. , Controlled Devices Controlled devices consist of (1) automatic valves (2) valve operators, (3) automatic dampers, and (4) damper operators. Other controlled devices include electric heaters, and motors on such equipment as fans, pumps, burners, refrigeration compressors and similar apparatus. 1. An automatic valve is designed to control the flow of steam, water, gas, and other fluids and may be considered as a variable orifice which is positioned by an electric or pneumatic operator in response to impulses from the controller. It may be equipped with a throttling plug or v-port of special design to provide the desired flow characteristics. Renewable composition discs are common. They are made of materials best suited to the media handled by the valve, and its temperature and pressure. For high pres sures or for superheated steam, metal discs are often employed. Internal parts of valves such as the seat ring, throttling plug or v-port skirt, disc holder, and stem sometimes are made of stainless steel or other hard and corrosion resistant metals for use in severe service. Automatic valves should be properly selected and sized for the specific applications. See the section on Design Coordination in this chapter for further details. The functions of various types of automatic valves are as follows: a. A single-seated valve is designed for tight shut-off. Appropriate disc materials' for various pressure ranges and media are used. b. A pilot piston valve utilizes the pressure of the control agent as an aid in operat ing the valve. It usually is single-seated and is used where large forces are required for valve operation. c. A double-seated or balanced valve is designed so that the media pressure acting against the valve disc is essentially balanced thereby reducing the force required of the operator. It is widely used where the fluid pressure is too high to permit a singleseated valve to close. It cannot be used where tight shut-off is required. d. A three-way mixing valve has two inlet connections and one outlet connection and a double-faced disc operating between two seats. It is used to mix, as required, two fluids entering the inlet connections and leaving through the common outlet. e. A three-way diverting valve has one inlet connection and two outlet connections and two separate discs and seats. It is used to divert the flow to either of the outlets or to proportion the flow to both outlets. f. A butterfly valve consists of a heavy ring enclosing a disc which rotates on an axis at or near its center, and in principle is similar to a round single-blade damper. The disc usually seats against a ring machined within the body. 2. Valve operators are of three general types: a. A solenoid consists of a magnetic coil operating a movable plunger. It is used for two-position operation. The most common use of a solenoid-operated valve is to control the flow of gas, water, air and refrigerants and generally it is limited to relatively small sizes. b. An electric motor operates the valve stem through a gear train and linkage. Electric motor operators are classified in three distinct types. Unidirectional, for two-position operation. The valve opens during one-half revolution of the output shaft and closes during the other one-half revolution. Once started, it continues until the half revolution is completed, regardless of subsequent action by the con troller. Limit switches built into the operator stop the motor at the end of each stroke. If the controller has been satisfied during this interval the operator will continue to the other position. Spring-return, for two-position operation. Electric energy drives the value to one position and holds it. When the circuit is broken, the spring returns the valve to its normal position. Reversible, for floating and propor tional operation. The motor can run in either direction and can stop in any posi tion. It is sometimes equipped with a return spring. For proportional control applications, a potentiometer for rebalancing the control circuit is also driven by the motor. c. A pneumatic operator consists of a spring-opposed flexible diaphragm or bellows attached to the valve stem in such a way that an increase in air pressure moves the valve stem and at the same time compresses the spring. Springs of various ranges in terms of air pressure can be employed, to provide sequence operation of two or more Automatic Control 903 devices by proper selection or adjustment of the springs. Springless pneumatic operators, using two opposed diaphragms or two sides of a single diaphragm, also are used but generally are limited to special applications involving large valves or high pressures. Pneumatic operators are designed primarily for proportional control. Two-position control is accomplished by use of a two-position controller, or a two- position pneumatic relay to apply either full air pressure or no pressure to the valve operator. . Pneumatic valves and valves with spring-return electric operators can be classified as normally open or normally closed. remAovneodrm. ally-open valve will assume- an open position when all operating force is A normally-closed valve will assume a closed position when all operating force is removed. 3. Automatic dampers are designed to control the flow of air or gases and function like valves in this respect. Steel blades and frames are most common, but other materials are used for special applications such as those involving corrosive fumes. Large dampers often are made in two or more sections for strength and convenience in handling, the sections being inter-connected so as to operate as a unit. The damper types commonly used are: a. Single-blade, which is generally restricted to small sizes because of the difficulty of securing proper operation with high velocity air. b. Multi-blade or louver damper which has two or more blades linked together. It may be arranged for (a) parallel operation, in which all blades rotate in the same direction or-(b) opposed operation, in which adjacent blades rotate in opposite direc tions and provide more linear air flow characteristics than obtained with parallel operation. c. Mixing dampers, composed of two sections interlinked so that one section opens as the other closes. . 4. Damper operators of the electric type may be unidirectional, spring-return, or reversible similarly to electric-motor valve operators. Pneumatic damper operators are similar to pneumatic valve operators except that they usually have a longer stroke or the stroke is increased by means of a multiplying lever. Damper operators are mounted on the damper frame and are connected with linkage directly to a damper blade or are mounted outside the duct and connected to a crank arm attached to a shaft extension of one of the blades. On large dampers two or more operators may be required, and usually are applied at separate points on the damper. Normally- open or normally-closed operation is obtained according to the method of mounting tne operator and connecting the linkage. Auxiliary Control Equipment In addition to the conventional controllers and controlled devices de scribed, many control systems require auxiliary devices to perform various functions. Auxiliary controls for electric systems include: 1. Transformers to provide current at the required voltage. 2. Electric relays for control of electric heaters or to start and stop oil burners, refrigeration compressors, fans, pumps, or other apparatus for which the electrical load is too large to be handled directly by the controller. Other uses include time delay, circuit interlocking safety applications, and similar functions. 3. Potentiometers for manual positioning of proportional controlled devices or for remote set point adjustment of electronic controllers. . 4. Manual switches for manually performing a variety of operations. These may be of two-position or multiple-position type or may be of single or multiple-pole type. 5. Auxiliary switches on valve and damper operators for providing a selected se quence of operations. - Auxiliary control equipment for pneumatic systems include: 1- Air compressors and accessories, to provide a source of air at the required pres sure. . 2. Electro-pneumatic relays, w'hich are electrically-actuated air valves for operat es pneumatic equipment when an electrical circuit is energized or de-energized. 904 CHAPTER 39 1956 Guide 3. Pneumalic-eleciric relays, which are actuated by air pressure and make or break an electrical circuit. / 4. Pneumatic relays, which are actuated by the pressure from a controller and perform numerous functions. They may be divided into two groups: a. Two-position relays, which permit a controller actuating a proportional device to also actuate one or more two-position devices. They also are used in various auto matic switching operations. b. Proportional relays, which are used to reverse the action of a proportional con troller, select the higher or lower of two pressures, average two or more pressures, respond to the difference between two pressures, add or subtract pressures, amplify or retard pressure changes, and perform other similar functions. 5. Positioning relays, which are devices for assuring accurate positioning of a valve or damper operator in response to changes in pressure from a controller. They are affected by the position of the operator and the pressure from the controller, and whenever the two are out of balance will change the pressure applied to the operator until balance is restored. . 6. Switching relays, which are pneumatically operated air valves for diverting air from one circuit to another or for opening and closing air circuits. - 7. Pneumatic'switches, which are manually operated devices for diverting air from one circuit to another or for opening and closing air circuits. They may be of two- position or multiple-position type. . 8. Gradual switches, which are proportional devices for manually varying the air pressure in a circuit. , Auxiliary control devices common to both electric and pneumatic systems include: 1. Sequence controllers for operating a number of electric switches in sequence by means of a proportional electric or pneumatic operator. They are commonly used for controlling a number of steps of refrigeration capacity and may be arranged to pre vent simultaneous starting of compressors and to alternate the sequence to equalize wear. They may also be used for sequence operation of electric heaters and other equipment in response to the demands of a proportional controller. 2. Clocks or timers for turning apparatus on and off at predetermined times, for switching control systems from day to night operation, and for other time sequence functions. PART H--CONTROL APPLICATIONS Applications of controls to systems or apparatus of a general nature will be found in this chapter. Applications pertaining to specific systems or apparatus will be found in the chapters covering those subjects. CONTROLS FOR AUTOMATIC F.UEL BURNING EQUIPMENT Controls for the automatic fuel burning equipment described in Chapter 15 are outlined here. The basic requirements for oil burners, gas burners and coal burners (stokers) are included and the term burner refers to all three types of fuel burning equipment. Controls for these burners can be classified as operating controls, limit controls and primary controls. The sche- matic diagrams shown in Fig. 6 indicate the relationships of the basic com ponents. The power supply may be line voltage for each type of burner. 'j In control systems for domestic burners the line voltage may be stepped , down by means of a transformer for those portions of the circuits indicated by dotted lines. Such transformers are usually built into the stoker and oil burner primary controls. Control systems for domestic gas burners fre- - quently use a separate transformer as shown. There are domestic gas burner control systems which obtain their electrical power supply from the conversion of heat to low voltage electrical energy, in which case no trans former would be required. As the burner sizes increase, the tendency to use all line voltage controls increases in each of these general categories. Automatic Control 905 Operating Controls Operating controls initiate the starting and stopping of the burner and on larger burners they usually vary the fuel and air input to the combustion chamber in response to varying load demands. For residential and small, commercial heating plants with fuel inputs up to approximately 500,000 Btu per hour, the operating controller is usually some form of room thermo stat which automatically starts and stops the burner through the primary control as the limit controls permit. As the size of the heating system in creases, the use of a room thermostat as the operating controller for the burner becomes less common. An insertion thermostat (for furnaces), immersion thermostat (for hot water boilers) or pressure controller (for steam boilers) may be applied as an operating controller. Also, such STOKER OIL BURNER GAS BURNER Fig. 6. Schematic Diagrams of Some Typical Burner Control Systems (O = Operating Control; P = Primary Control; L '= Limit Control) devices as submaster and compensated controllers (which are reset from outdoor temperature for governing the bonnet temperature in large fur naces or the water temperature in a boiler) come into more frequent use on the larger installations. The still larger burners are usually equipped to vary the rate of fuel and-air input in response to varying load demands. Limit Controls Limit controls guard against unsafe temperature, pressure or water level to assure that safe conditions prevail for the operation of the burner. Draft controls protect the firebox against excessive drafts, regardless of the type of fuel being burned, to increase combustion efficiencies and re duce stack losses. For fuel input requirements above approximately 1,000,000 Btu per hour some additional'factors become common to all types of burners. For example, the draft in the firebox is controlled at a suitable constant for all firing rates, including the off period, by measuring the draft conditions in the firebox and actuating a damper operator to posi tion the damper at the boiler outlet. Where necessary, provision may be made to open the boiler outlet damper wide before permitting the burner to start and then return this damper to automatic control after the burner has been started. Also, the firing rate of these larger burners is frequently automatically adjustable and provisions are made for always starting the burner on its low firing rate, with facilities for increasing the firing rate slowly after the burner has been started. It is not recommended and codes seldom permit the use of one and the same instrument as both an operating controller and a high limit control. In such cases an operating controller will be adjusted to control at the desired set point while the high limit 906 CHAPTER 39 1956 Guide control will be adjusted to stop the burner at some higher point in the event that the operating controller fails to stop the burner before the higher shut off point is reached. For example, to maintain a constant water tempera ture in a hot water boiler, the operating controller may be set to stop the burner when the boiler water temperature reaches 180 F. The high limit control should then be set to stop the burner at a higher temperature, say 200 F. - Various interlocks or limit controls are usually included to assure safe operation of these larger burners. A latch switch interlock prevents burner operation if the burner is not in its proper firing position. Another inter lock must prove that the burner is in its low-fire position before the burner can be started. Safe draft conditions should be proved before the burner can be started or allowed to run, especially where induced draft fans are involved. A smoke detecting device may sound an alarm and stop the burner if excessive smoke is produced. Also, protection against electrical overloads must be provided. . Primary Controls Primary controls,provide for the safe start and operating procedure of the burner. They are somewhat different for each of the three types of fuel, burners. .... ...... 1. Stokers. Stokers are equipped with refueling, or hold-lire, controls. These pri mary controls cause the stoker to intermittently feed a predetermined amount of coal during the long off periods of the operating controller to maintain ignition and to re duce the possibility of having idle fuel beds damage stoker castings. In some cases the primary control system includes an out-fire feature which stops the feeding of coal into the firebox if the fire goes out. 2. Oil Burners. Primary controls required for oil burners depend on the size and type of burner. Some of the more common primary controls are discussed in follow ing paragraphs a to d. a. Domestic oil burners of the vaporizing type usually require a primary control which will (1) meter the correct amount of oil into the burner to maintain the pilot flame; (2) regulate the required amount of oil into the burner for its high flame op eration; and (3) completely shut off the flow of oil in the event of a flame failure. b. Domestic oil burners of the pressure atomizing type require a primary control which will (1) energize the burner motor and electric ignition; (2) test for the estab lishment of main burner flame and stop the burner and ignition if flame has not been established; (3) cut off the ignition after a safe burner flame has been established . (does not apply to constant ignition type burners); (4) monitor the flame continuously during burner operation and stop the burner in the event of flame failure (manual reset is necessary following a flame failure lock-out); and (5) stop the burner when either the operating controller or limit control requires it. c. Commercial and industrial oil burners of the pressure atomizing type have pri mary controls that are essentially the same as those outlined for domestic oil burners of the pressure atomizing type. In addition, some models are equipped with a sole noid oil-shut-off valve to provide a pre-purge period, if desired, and a quick shut-off of the oil flow when the burner is stopped. d. Commercial and industrial oil burners of the horizontal rotary cup type are usually equipped with a more elaborate primarycontrol system. The primary control is often described as a programming combustion safety control. Its most important operations include (1) starting the burner upon a call for heat; (2) providing a pre purge period before activating the gas-electric ignition; (3) proving the presence of proper ignition before permitting the flow of oil to the main burner; (4) proving the presence of a stable main burner flame within a predetermined period of time; (5) shutting off the gas-electric ignition after a predetermined length of time has elapsed; (6) monitoring the main burner flame during its entire on period and stopping the burner quickly in the event of a flame failure (it is usually required that the flow of oil through the burner be stopped within four seconds following a flame failure); (7) stopping the flow of oil through the burner when either the operating controller or a limit control requires it; (8) operating the burner for a predetermined length of time Automatic Control 907 after the main fuel valve has been closed; and (9) locking out on a flame failure shut down (the programming control then must be manually reset prior to a restart). When steam, air or mechanical atomizing burners are automatically controlled, their sequence of control is similar to that described for horizontal rotary cup burners. 3. Gas Burners. Some of the more common primary controls for gas burners are as follows. a. Domestic gas burners of the'atmospheric type require a primary control, to in sure safe starting and operating conditions, which will (1) prevent opening of the gas valve unless the pilot is operating properly, and (2) stop the flow of gas through the burner if safe ignition conditions do not prevail at all times. b. Commercial and industrial gas burners of the atmospheric type require a pri mary control whose function is similar to that for domestic sizes of these burners ex cept in the rate of response to a pilot flame failure. The pilot flame bums constantly and, in general, the primary control system will (1) assure operation only when ig nition of the main burner will be safe; (2) start and stop the main burner when re quired to do so by either the operating controller or a limit control; and (3) close the safety shut-off valve in the gas supply line to the burner upon a flame failure or an electrical power failure. c. Commercial and industrial gas burners of the power type equipped with electric ignition require a primary control whose most important operations include: (1) starting the burner motor upon a call for heat by the operating controller; (2) provid ing a pre-purge period before activating the gas-electric ignition; (3) proving the presence of proper ignition before.allowing gas to flow to the main burner or shutting off the electric ignitor; (4) closing the safety shut-off valve in the event of a flame fail ure (it is usually required that the flow of gas be stopped within four seconds following a flame failure); (5) stopping the burner when either an operating controller or a limit control requires it; and (6) locking out on a flame failure shut-down (the programming control then must be manually reset prior to a re-start). RESIDENTIAL HEATING AND AIR CONDITIONING The control equipment function in the residence may vary from the regu lation of a coal fired heating plant to the completely automatic control of a year-around heating and cooling system. Regardless of the type of heating or air conditioning system used, the control system should be selected care fully to insure safety and comfort of the occupants as well as economy of operation. . The simplest type of domestic control is one in which the room thermostat starts and stops the burner, as described in the preceding section. It may be used on gravity or forced warm air, hot water or steam systems. In forced warm air or forced hot water systems the fan or circulator usually is controlled by a thermostat in the furnace or boiler and runs whenever the air or water temperature is above a minimum value, as discussed in Chapter 20. If straight two-position control is used for this application, the on and off periods are relatively long and there is a tendency towards cold drafts on the floor during off periods. If timed two-position control is used, the burner may be cycled (started and stopped) often enough to provide results very comparable to proportioning control. The heat input to the home is proportioned continuously to the heat loss from the home. The fan of a forced warm air system or the circulator of a forced hot water system may be run almost continuously, thus minimizing the possibility of cold drafts. Proportional control is used on residential applications when provisions are made for it in the design of the system. Face and bypass dampers on warm air systems, throttling valves on steam systems and three-way mixing valves on hot water systems are typical examples of controlled devices which permit proportional control. With these arrangements the burner usually is controlled by a thermostat in the furnace or boiler. Proportional control will permit nearly continuous circulation of warm air or hot water, thus reducing cold drafts. Automatic night set-back through the use of a day-night type room 908 CHAPTER 39 1956 Guide thermostat is a refinement frequently added to residential control systems. Though opinions vary regarding the amount of fuel that/ can be saved by automatic night set-back, tests made both in the warm air heating research residence and the I = B = R research home at the University of Illinois indicate that, on thermostatically controlled systems, a possible fuel saving of from 7 to 10 percent may be obtained by reducing the house temperature 6 to 10 F from about 10:00 p.m. to 5:30 a.m. It is often desirable to divide the house into two or more zones for greater accuracy of control and comfort. Each zone may then be main tained individually at the desired temperature level. The division into zones should be based upon exposure or occupancy; the most common division is usually found to be (1) the living section such as living room, dining room, den; (2) the sleeping section; (3) the service section such as kitchen, pantry, servants' quarters; and (4) the recreational areas. Further discussion of zone control will be found in the following section on Zone Control and Zone Control Systems. Year-round residential air conditioning systems which provide for heat ing in winter and cooling in summer should be given the same consideration in selecting the control system as required for commercial air conditioning systems. See Chapter 30. The basic principles are the same and the final results must provide for the comfort of the occupants. A reduction in investment for automatic controls may result in wasteful operation of the system and discomfort for the occupants. Special thermostats have been designed to take care of the year-round residential air conditioning systems. These thermostats offer manual, semi-automatic, and automatic changeover from heating to cooling as selected by the unit manufacturer. Generally speaking, the heating unit is controlled by timed two-position action and the cooling unit by straight two-position action. Some form of humidity control may be added. . When an add-on unit is installed to obtain a year-round air conditioning system by change of straight heating system, it may be controlled separately or integrated with the heating control system. However it is accomplished, the control system should be simple enough for the user to understand how to operate it effectively. ZONE CONTROL Zone control for any heating, ventilating or air conditioning system is employed where it is desired to control the heating or cooling effect in a number of rooms or areas, having similar orientation or occupancy, through one set of controls. For zone control to be successful the requirements must be approximately consistent throughout the extent of the zone. Whether zoning a building for heating or cooling the following factors should be considered in determining the number and arrangement of the zones:1 2 3 4 1. Exposure. Solar effect, prevailing winds, and the shelter afforded by sur rounding structures affect the heat gain or loss. . 2. Occupancy. Indoor temperature requirements for the various activities carried on in different portions of the building and the hours of occupancy of the various spaces impose definite control problems. 3. Building Structure. The physical characteristics of the building will influence the subdivisions of the system into zones since satisfactory temperature conditions throughout a single zone of given extent may not be enjoyed equally in buildings of dissimilar types of construction. Other factors are the height of the building and its horizontal extent and form. . 4. Floors. Even though several floors have the same wall exposure, it is advisable Automatic Control 909 to have separate zones on the lowest and highest floors due to variations of basement or ground floor requirements and those with roof exposure. It is also desirable to have a separate zone or zones for the intermediate floors. . The initial investment will often influence the decision as to the final number of zones to be employed. In larger buildings accepted practice is to have at least one zone for each'exposure. Each exposure may require subdivision vertically into two or more zones for the higher structures. Also, the presence of two or more wings having the same general exposure may suggest the desirability of more restrictive zoning. When the street floor or any other portion of the building is used for public occupancy or activities which differ from those carried on in the remainder of the build ing, it is desirable to provide separate thermostats and controls for each individual area. Zone controls alone may not provide satisfactory temperature conditions in all rooms or areas within the zone because occupancy, lighting load, space arrangements and similar factors cannot always be predicted with accuracy. A combination of zone controls with individual room control in critical areas may be necessay to achieve, complete satisfaction. ZONE CONTROL SYSTEMS This section is concerned with zone controls for steam or hot water heat ing systems. Most zone control systems are designed to supply heat to a zone at a rate equal to the heat loss. This rate of heat input may be established by room thermostats, by controllers responsive to outdoor conditions, or by a combination of both. The outdoor controller responds to temperature and may respond to solar radiation and wind velocity and direction. Fea tures which may be added to the basic zone control system include: 1. Means for automatically or manually varying the heatinput tothe zone to com pensate for variations in internal heat gain. The automatic arrangement requires a thermostat at a representative location within the zone. The manual arrangement usually consists of a switch located where convenient. 2. Means for maintaining a lowered economy temperature or shutting off the heat completely at night or at other times when the zone is unoccupied. This may be accomplished manually or by means of a clock. 3. An arrangement providing rapid warm-up following a period at the non-occu pancy temperature. During this warm-up period full heat may be admitted to the system or the heat input may be controlled at a higher-than-normal rate. The warm up may be accompished by a manual switch or may be part of the clock program. A warm-up thermostat located within the zone may be arranged to terminate the warm-up period independently of the switch or clock when the zone approaches the desired occupancy temperature. 4. A manual switch to provide full heat or no heat independently of other controls and to permit manual selection of the various clock functions. 5. Means for shutting off the heat completely when the outdoor temperature reaches a point where heat no longer is needed. 6. A high limit thermostat in the zone to shut off the heat completely when the zone becomes overheated. Steam Heating Systems In continuous-flow steam systems the quantity of steam supplied to the zone is varied in accordance with the demands of the control system. To obtain equalized distribution of the steam, metering orifices are generally required on the inlets to all radiators or convectors. Supplementary con trols for low heat output are often desirable. The following two arrange ments are common: 1. Varying the difference in pressure between the supply and return which results T Mp*i*1 jjivtp1 ! ii n< <i tjill' Wt>pl fJ : . I 5 l 910 CHAPTER 39 1956 Guide in partially filling the heating units in accordance with demand. This method can be used on atmospheric or vacuum return systems. , 2. Varying the pressure in the system while maintaining a constant differential pressure between the supply and return. This results in the heating units being filled with steam at a temperature which is proportional to demand. A vacuum pump maintaining a vacuum slightly below the supply pressure is required, and vacuums as high as 20 in. Hg during mild heating weather are common. In intermittent systems steam at full pressure is supplied intermittently to the zone, the length of the on and off periods being varied in accordance with the demands of the control system. Two common arrangements are: 1. A timing device controlled by an outdoor thermostatic element which can be used to vary the on-off periods of boiler operation or the opening and closing of a steam valve as a function of outdoor temperature. 2. A control responding to an outdoor element and an element attached to a radiator or convector, so that it varies the length and frequency of the on-off intervals in such a way that the radiator or convector temperature is varied in accordance with outdoor temperature. 0 OUTDOOR CONTROL n SPACE CONTROL Y 10PTI0NA,-1 TO HOT WATER HEATING SYSTEM --& CIRCULATOR Fig. 7. Control op Hot Water Heating Without Domestic Hot Water Service (Limit and primary controls not shown) For proper operation of zone control equipment the heating system must be carefully designed and installed, and maintained in good operating con dition. Vents, traps, vacuum pumps and valves must be given a careful inspection and repaired or replaced when required.' Piping must be of adequate size graded and dripped. Return piping must be vented and any pockets or lifts removed. Hot Water Heating Systems A common method of obtaining zone control of hot water systems con sists of varying the temperature of water supplied to the zone inversely as the outdoor temperature varies. This may be accomplished by a submaster thermostat in the zone supply line readjusted by an outdoor master thermo stat, or by a single controller having one measuring element in the supply line and another compensating element outdoors. On single zone installa tions the controller may actuate the burner directly as shown in Fig. 7. If the boiler is also used for domestic hot water the controls may be arranged as in Fig. 8. In this case the boiler is controlled at a fixed temperature and the zone controller is arranged to operate a valve to proportion hot water from the boiler with cooler return water to obtain the desired zone water temperature. On multiple zone installations the boiler usually is controlled at a fixed temperature, and each zone is controlled by a separate valve and outdoor compensated controller. Each zone should be equipped with a Automatic Control 911 separate pump because in many cases the return water from some zones is warmer than the required supply water for other zones. By using indi vidual zone pumps the returns can be separated and thus prevent overheat ing that would otherwise occur. To compensate for variations in internal load, the action of the zone control may be modified by a room thermostat in each zone which either starts and stops the zone pump, modifies the relationship between outdoor temperature and water temperature, or operates an automatic valve in the zone supply or return line. Each zone may be further subdivided by pro viding a separate thermostat and valve for each subdivision. Another zone control method for hot water systems consists of maintain ing a constant water temperature and varying the volume of water supplied to the zone by means of a room thermostat which either starts and stops the zone pump or operates a two-position valve in the zone supply or re turn line. Whenever flow control valves are employed in water circuits it is neces sary to employ a relief valve or pressure-regulating valve in a bypass con-nection around the pump. OUTDOOR CONTROL SRACE CONTROL D wSfER^pi u?j"}--(OPTIONAL) control LnP------ i-------------- r- BOILER /CONTROL f _31--_r---Ai umivixikiwng. I iH-r VALVE TO HOT WATER HEATING SYSTEM &-J- CIRCULATOR Fig. 8. Control op Hot Water Heating With Provisions for Domestic Water Heating (Limit and primary controls not shown) PANEL HEATING SYSTEMS Automatic controls for panel heating differ somewhat from those de scribed for convective heating because of the thermal inertia characteristics of the panel heating surface and the increase in the mean radiant tem perature within the space under increasing loads for panel heating. How ever, many of the same control principles for hot water heating systems will also apply to panel heating. Panels such as concrete slabs have large heat storage capacity and con tinue to emit heat long after the room thermostat has shut off the supply of heating medium. In addition, there is a considerable time lag between thermostat demand and heat delivery to the space due to the large part of the heat which must first be stored in the thermally heavy radiant surface. This inertia will cause uncomfortable cycling of space conditions unless controls for detecting load changes as early as possible are provided. In general, the temperature of the heating medium supplied to the panel surface should be varied in accordance with outdoor temperature, as de scribed in the first paragraph under Hot Water Heating Systems in the section on Zone Control Systems. Controls indicated in Figs. 7 and 8 apply and, in addition, consideration should be given to preventing the introduc tion of excessively hot water in the event of control failure which might I n, ! I il 11 !! !U i ; ` ; i { i ! 1 I.! !!i I ' I : 912 CHAPTER 39 1956 Guide damage the panels, and to a manual boiler bypass or other means of re ducing the water temperature to prevent too rapid drying out of new panels (see Chapter 24, Panel Heating). Due to the increase in MRT (mean radiant temperature) within a panel heated space which necessarily takes place as the heating load increases, the air temperature under such conditions, theoretically, should be lowered in the order of 1 or 2 degrees to maintain comfort. In ordinary structures with normal infiltration loads the required reduction in air temperature is small and, consequently, a con ventional room thermostat may be used. In panel heating systems, lowered night temperatures will produce unsatisfactory results with heavy panels such as concrete floors. These panels cannot respond to either quick increase or decrease in heating de mand within the relatively short time required, with the result that there will be a very slow reduction of space temperature at night and a cor respondingly slow pick-iip in the morning. Panels of light weight construc tion, such as plaster or metal ceilings and walls, may respond to changes in demand with sufficient rapidity that moderately satisfactory results can be expected from lowered night temperatures. However, very little fuel saving can be expected even with the light panels unless the lowered tem perature is maintained for long periods. If reduced non-occupancy tem peratures are employed, some means of providing a higher-than-normal rate of heat input for rapid warm-up is necessary, or a long warm-up period should be provided for, as explained under Zone Control Systems. INDIVIDUAL ROOM CONTROL The ideal temperature control system for any building is one that pro motes maintenance of the desired temperature in every room at all times regardless of location and occupancy. Individual room temperature con trol is desirable for securing proper thermal environment in schools, hos pitals and offices. Control of the temperature in each room, or possibly of adjacent rooms having the same orientation (as in an apartment), overcomes many of the problems encountered when attempting to regulate the temperature of a building as a whole or of large areas or zones. Each individual thermostat controls the heat input to its particular space regardless of occupancy or exposure to sun and wind. The advantage of individual room control is in fuel economy and comfort for the occupants. Each room should have a thermostat that controls valves or dampers on all the controllable sources of heating and cooling. One such uncontrolled source may prevent proper operation of the control system. CONTROL OF CENTRAL FAN SYSTEMS Local practice, local climatic, conditions and economic factors influence control system design. The following sections describe some of the more common methods of controlling the different pieces of equipment used in central fan systems. The complete control system is made up by combining the selected method for each item into an integrated arrangement with proper consideration being given to the interrelation of the several parts, necessary sequence of operations, etc. Outdoor Air Damper Control Outdoor air for ventilation is usually controlled by a damper arrangement to provide a homogeneous mixture of outdoor air and recirculated air. Outdoor air to meet minimum ventilation requirements should be available Automatic Control 913, whenever the fan is running and is usually provided in one Of the following ways: a. By a minimum outdoor-air damper which opens when the fan is started. A maximum outdoor-air damper may also be provided if additional outdoor air for nat ural cooling is desired. b. By an outdoor-air damper opening to a minimum position when the fan is started. Additional outdoor air is provided by further opening of the damper under automatic control. Recirculated-air and exhaust-air dampers are synchronized to operate with the outdoor air dampers. Mechanical interconnections are preferable but separate operators on each of the dampers can be used when mechanical interconnections are impractical. Control of outdoor air quantities beyond the minimum amount can be accomplished by: a. A thermostat set for about 55 F and having its bulb located where there is a true mixture of outdoor air and return air; b. A thermostat in the outdoor air which will gradually open the outdoor-air damper as the outdoor-air temperature increases during mild heating weather. c. A combination of outdoor-air and return-air thermostats operating to select the cooler source of air when cooling is required. d. The preheater thermostat, arranged so that after the preheat valve is closed the outdoor-air damper gradually opens. . e. The apparatus dew-point thermostat, arranged so that the outdoor-air damper opens before mechanical cooling is used. In most arrangements provisions are made to prevent admission of more than minimum outdoor air required for ventilation both during heating operation and when the outdoor-air temperature is too high to provide some natural cooling. Provisions should also be made to close the outdoor-air damper and open the return-air damper whenever the fan is stopped. Preheater Coil Control The function of a preheater is to temper the outdoor air to prevent the possibility of freezing beyond the coil. Care must be taken to avoid freez ing in the coil itself. The proper selection, installation and sizing of steam traps are very important to assure rapid elimination of condensate to pre vent freezing. : Steam-distributing-type coils usually are controlled by a thermostat lo cated downstream from the coil and operating a valve in the steam supply line. Where a large temperature rise is required, two or more coils in series should be used, each having a separate valve. The valves should be ar ranged to operate in sequence, with the valve on the upstream coil opening first. Non-distributing-type coils should be controlled by a thermostat located ahead of the preheat coil and adjusted to completely open the valve before the incoming air temperature drops to 35 F, to avoid freezing in the coil. It is important that the preheat coil and its valve be selected so as to prevent overheating the conditioned space when the valve is fully open at 35 F incoming temperature. The use of preheat coil-face and bypass dam pers will permit proportional control from a thermostat located beyond the preheat coil, and will prevent such overheating. The coil valve should be wide open whenever the incoming air temperature is below 35 F. Hot water preheat coils should be controlled by face and bypass dampers operated by a thermostat downstream from the coil, with continuous water circulation when the outdoor air is below freezing. A pressure switch to stop the fan in case of pump failure is often employed. Further freeze protection can be accomplished by a thermostat in the coil outlet arranged 914 CHAPTER 39 1956 Guide Automatic Control 915 to stop the fan-if the water temperature approaches 35 F. In all applica tions where face and bypass dampers are used, precautionary measures must be taken to prevent stratification of the mixture beyond the coil, - three-way mixing valve; position face and bypass dampers at the coil; or position a return-air bypass damper. An apparatus dew-point thermostat may also be used to control the cooling coil valve. Reheater Coil Control Reheat coils when used for tempering air for ventilation can be controlled by a proportional insertion thermostat, preferably located in the fan dis charge to minimize the effect of stratification. This thermostat operates the reheat coil valve or valves, or face and bypass dampers, to maintain a constant discharge air temperature. When face and bypass dampers are used it is good practice to have a valve on the coil which closes after the face damper is closed to prevent overheating due to radiation from the coil or to damper leakage. When used for space heating, reheat coils are con trolled by valves or face and bypass dampers actuated by a thermostat in the space or the return air. Usually a low-limit discharge thermostat is used in conjunction with the space or return-air thermostat.to maintain the delivered air temperature above the design minimum. To avoid the lag associated with room or return-air control of the reheat coil, it often is preferable to use a controller in the fan discharge which is compensated by Air Washers. Since the air leaving an efficient washer is practically saturated, the temperature of the spray water will determine the dew-point temperature of the air leaving the washer. With this condition it is possible to maintain very accurate dew-point temperatures and consequently accurate relative humidities under a given ratio of sensible-to-latent heat gain in the conditioned space, provided the space drybulb temperature is accurately controlled. In general, the water pump operates continuously and a thermostat measuring the dew-point temperature is used to posi tion a three-way valve to mix refrigerated water with bypassed washer water. To compensate for variations in latent load, a humidistat measuring the space relative humidity may be employed as a master controller to readjust the set point of a dew point submaster controller. Static Pressure Control Since fans are selected to produce the desired results for a certain system characteristic, any change in the system characteristic will change the output of the fan. Such changes occur, for example, on single-duct systems in which the volume of air delivered is varied and in double-duct systems where quantities of air are shifted from one duct to the other to obtain space temperature. Humidity Controls . Steam-pan or grid type humidifiers usually are controlled by a valve actuated by a proportional room or return air humidistat or wet-bulb - final space control. System characteristics may also change when the relative quantities of outdoor air and recirculated air are varied, when exhaust fans are run intermittently, and for other reasons. Such changes result in a changing static pressure in the system, a changing noise level, and changing velocities at air outlets which upset the air flow patterns. thermostat. The valve should close when the fan stops. Single-bank sprays, when used primarily for humidification, are usually controlled by a two-position room or return-air humidistat or a wet-bulb thermostat operating a valve in the water line or starting and stopping the pump. Air washers should be run continuously and are usually controlled by varying the temperature of the washer water or the air entering the spray chamber. An apparatus dew-point thermostat with its measuring element located in the air washer water, or in the outlet of the washer be yond the eliminator plates, may be used to (1) operate a mixing valve, or a Static pressure control of some form is usually required on such systems, and it is accomplished by a static pressure controller measuring the pres sure at a selected point in the system with respect to an atmospheric refer ence point or some other point inside the building. It can be used to ac tuate a damper operator on fan inlet vanes, on a multi-blade damper on the suction or discharge side of the fan, or on a damper in a bypass connection between the fan discharge and the fan suction. Control of Final Space Conditions steam valve on the water heater, to control the washer water temperature; (2) control a valve on the tempering coil ahead of the washer; (3) operate outdoor-air and return-air dampers to control the mixed air temperature entering the washer; or (4) operate a combination of these arrangements. It is sometimes satisfactory to control the entire area or zone served by a central fan system from a single point as described in previous sections re lating to reheat coils, humidifiers and to cooling and dehumidification. The factors to be considered in properly zoning the building are discussed in the section on zone control. Where the entire area does not meet the require Cooling and Dehumidification Controls ments of a single zone, it may be subdivided so that the air distribution i Dehumidification by condensation is so closely related to sensible cooling system can be arranged for individual control of each smaller area. This that it is convenient to discuss them together. Three typical applications may be accomplished by a thermostat in each space operating warm- and of controls are discussed. cold-air mixing dampers in the duct serving the space, or operating valves Direct Expansion Systems. A thermostat measuring the space temperature may be used to open and close a solenoid refrigerant valve on the coil inlet; control the .starting and stopping of one or more refrigerating compressors, or otherwise control on individual reheat or cooling coils for each space. By providing a suffi cient number of subdivisions of the area served by a central fan system, individual room control can be achieved. the compressor capacity; position face and bypass dampers, or a return-air bypass damper, in combination with the opening and closing of the refrigerant coil valve or Control of a Typical System the starting and stopping of the compressor; control a back pressure regulating valve with proportional action; or control a liquid-refrigerant valve on the inlet to the coil with proportional action. The positive opening and closing of the refrigerant valve Fig. 9 shows a complete control arrangement for a typical central-fan air conditioning system in which individual room control is not provided. The or the starting and stopping of the refrigeration compressor will result in wide varia tions in discharge temperature and dehumidification. When such variations are ob controls can be pneumatic, electric, or electronic. jectionable, it is desirable to employ proportional damper controls or proportional When the fan is started relay E-l, actuated by the fan-motor starter, opens out control of refrigerant flow in conjunction with refrigeration equipment capacity controls as discussed in Chapter 37. Chilled Water and Brine Coils. A thermostat measuring the space temperature may be used to control a valve on the inlet or outlet of the cooling coil; control a door-air damper D-l, places humidistat H in service, and allows insertion thermostat T-l to operate preheat coil valve V-l, maximum-outdoor-air damper D-2, return-air damper D-3 and exhaust damper D-l. When the fan stops, E-l is de-energized and closes the outdoor-air dampers and humidifier valve V-4. The sequence of operation described will in general also apply to high-pressure 11 fl***-! <' ` r si***' * lS*a*', 1 il*-"*-1 If|jp! * ' : v1 Ilf* 916 CHAPTER 39 1956 Guide fan systems except that it is considered desirable to open the outdoor-air damper be fore starting the fan. With this arrangement, a manual switch operates damper D-l. A mercury contactor mounted on the damper starts the fan when the damper is fully open. It also stops the fan when the damper starts to close. Insertion thermostat T-l maintains a temperature of 65 F at the preheat coil dis charge by operating preheat coil valve V-l. This serves as a low limit for the fan discharge temperature during heating operation. When V-l is closed, thermostat T-l then gradually opens maximum-outdoor-air damper D-2 and closes return-air damper D-3 proportionately. At 65 F outdoor temperature D-2 is wide open and D-3 is closed. Exhaust air damper DA opens and closes in synchronization with D-2. At 75 F outdoors, when the outdoor air is no longer useful for natural cooling, T-2 closes D-2 and DA and opens D-3. Reheater coil valve V-3 is controlled by submaster thermostat T-3 in the fan discharge. This thermostat is automatically readjusted over an appropriate range of temperature by room thermostat TA so that the discharge temperature matches ROOM HUMIDtSTAT I ' ROOm"THERMOSW I iir' i Fig. 9. Control Diagram for Typical Central Fan Air Conditioning System the space requirements. When the room temperature tends to rise above a pre determined value, T-3 has been readjusted downward far enough to keep reheat valve V-3 closed. TA then controls cooling coil valve V-2 directly to maintain the desired space temperature. , Humidistat H operates humidifier valve VA to maintain the desired humidity in the conditioned space. It is usually adjusted to maintain 30 to 40 percent relative humidity, and therefore keeps the humidifier off during cooling operation when the humidity is higher. AUTOMATIC CONTROL OF UNIT HEATERS The controls for a unit heater can either provide (1) on-off operation of the unit fan or (2) continuous fan operation with modulation of the heat output. For on-off operation a room thermostat is used to start and stop the fan motor. A limit thermostat, often strapped to the supply pipe, prevents fan operation in the event heat is not being supplied to the unit coil. Continuous fan operation practically eliminates the intermittent blasts of hot air resulting from on-off operation, and the stratification of tempera- Automatic Control 917 ture from floor to ceiling which often occurs during the off periods. In this arrangement a proportional room thermostat controls a modulating valve in the steam or hot water supply line to the coil. A limit thermostat or auxiliary switch stops the fan when the valve is closed. Unit heaters may be used in summer as a means of circulating air to give some measure of comfort due to air motion. In such cases the source of heat should be shut off and the thermostat should be provided with a by pass switch which will permit fan operation independently of the controls. AUTOMATIC CONTROL OF UNIT VENTILATORS Many different control cycles are available. The principle difference in the various cycles pertains to the amount of outdoor air delivered to the room during normal periods of heating. The choice may be governed by compulsory ventilation codes. Usually a room thermostat controls both a valve to regulate the heat supply and a damper to regulate the supply of cool outdoor air. An in sertion thermostat at the unit ventilator prevents the discharge of air below the desired minimum temperature. Any auxiliary heating devices in the same room should be controlled, by the room thermostat, in the proper sequence to fit into, the unit ventilator cycle during the following stages: Warm-up Stage. All control cycles function to provide rapid warm-up by having all heating valves wide open and the outdoor damper closed. Thus 100 percent room air is recirculated and heated until the room temperature approaches the desired tem perature level. Healing and Ventilating Stage. As the room temperature rises into the operating range of the thermostat, ventilation is accomplished by the partial or complete opening of the outdoor damper according to the cycle used. Valves on auxiliary heating devices are often closed at about the same time. As the room temperature continues to rise the unit ventilator valve is throttled as required to control the heat supply. . Cooling and Ventilating Stage. When the room temperature rises above the normal level, cool air is discharged into the room. The room thermostat accomplishes this by throttling the valve further, and then closing it and opening the outdoor damper, if necessary, to prevent the room from overheating. The insertion thermostat fre quently takes control during this stage to prevent the discharge of objectionably cold air. , The three basic control cycles commonly used are as follows: Cycle X. A fixed percentage (often 100 percent) of outdoor air is admitted at all times except during the warm-up stage. Cycle Y. A minimum amount of outdoor air (normally 25 to 50 percent) is ad mitted during the heating and ventilating stage. This percentage is gradually in creased to 100 percent, if needed, during the cooling and ventilating stage. Cycle Z. Except during the warm-up stage a variable amount of outdoor air is ad mitted as needed to maintain a fixed temperature of air entering the heating coil. This is controlled by the insertion thermostat which must be set low enough (often 60 F) to provide cooling when needed. Day-night thermostats are often used with unit ventilators. Separate switching circuits are used to permit daytime temperatures in some areas and lowered temperatures in others for maximum economy. Several daynight arrangements are in common use. One uses the unit as a convector. Another turns the fan on and off like a unit heater. More elaborate ar rangements are available. PART m--DESIGN COORDINATION nearing or cooling system is designed to meet maximum conditions but Junctions at partial capacity much of the time. The ability to properly 918 CHAPTER 39 1956 Guide control the system at all times is one of the most important factors having to do with the design of the system and for this reason the proper use and application of controls should be considered at the time the heating or cool ing system is being designed. Wherever possible the system should be designed to facilitate control operation. This section includes. factors which should be considered in the design of a new heating or cooling system, or the modernization of an existing one, to enable the control system to produce the best possible results. The design of the system and its controls should take into consideration the nature and type of the building in which it is to be used and the results it is desired to accomplish. Quality of the control equipment should be consistent with the accuracy of control required. Where results more pre cise than those for normal comfort applications are required, such as in certain manufacturing areas, constant temperature rooms, etc., both the air conditioning system and the control system should be given special consideration so that the required results can be produced. Controls can be made to produce almost any degree of accuracy required, but it is useless to provide such controls unless the air conditioning system is capable of properly responding to the demands of the controllers. For example, it is virtually impossible to maintain close control of temperature and humidity by starting and stopping a refrigeration compressor or opening and closing a refrigerant valve. It is necessary instead to employ refrigeration equip ment which will permit proportional control by one of the methods dis cussed in Chapter 37, or to use a chilled-water system with a cooling coil or air washer that will permit proportional control. Neither is it good prac tice or economical to select equipment capable of producihg far more pre cise control than the application requires, or to unnecessarily complicate the system to obtain special sequences or cycles of operation. It is well to . remember that the system must be adjusted and maintained in operation for many years, and the simplest system that will produce the necessary results is usually the best. SIZE OF CONTROLLED AREA No individually controlled area should be excessively large because the difficulties of obtaining good distribution and of finding a representative location for the space controls become greater as the area increases. Each individually controlled area must have similar load characteristics through out and otherwise should conform to the recommendations given in the section on Zone Control. For uniform conditions throughout the area equitable distribution must be provided by competent engineering design, careful sizing of equipment and proper balancing of the system. The control can measure conditions only at the point where it is located, and it cannot compensate for variable conditions throughout the area caused by improper distribution or inadequate design. Areas or rooms having dis similar load characteristics, or having different conditions to be maintained, should be individually controlled. The smaller the controlled area the better will be the control obtained and the more nearly will the system approach the optimum in performance and flexibility. Even when individual room control is employed it often is well to consider some form of overall zone control of the whole system in accordance with the major factor influencing system load. Thus the water temperature in a hot water heating system, the steam temperature or pressure in a steam heating system, or the delivered air temperature in a central fan system may be varied inversely as the outdoor temperature varies. This obtains a fair share of the necessary control on the system as a whole, relieves the indi Automatic Control 919 vidual space controls of a part of their burden and makes more accurate space control possible. Furthermore, modifying the basic rate of heating or cooling input to the system in accordance with system load reduces Josses in the distribution system. The cost of the additional controls is often justified by the reduction in operating costs. Where such overall system controls are employed, accurate zoning, while desirable, is not necessary. The system must always.be able to satisfy the area or room having the greatest demand. The individual controls take care of the variations in demand within the area served by the system. The more accurately the system is zoned the larger will be the share of the control accomplished by the overall system controls, the smaller will be the system distribution losses, and the more accurately will the individual space con trols be able to maintain the space conditions. EQUIPMENT SELECTION AND LAYOUT Heating and cooling coils should be carefully selected to avoid oversizingA coil that is too large is not only more difficult to control but may increase air temperature stratification. When temperature measuring elements are to be placed between coils, ample space between the coils must be provided. The measuring element should be located as near as possible to the coil it is controlling. For example, ah idle water coil interposed between a ther mostat and the coil it is controlling introduces enough thermal inertia to make it difficult to produce stable control. me ciiiiiuinLmn U1 StiUlUIUttUUU wu uu uc*uuuug ojovcui ID CfiDCIitliU JLLUu only in producing good control but in obtaining equitable distribution of heating or cooling. Outdoor-air and return-air dampers should be arranged in such a way as to help blend the outdoor air and return air. Face dampers should be placed far enough from coils to allow for equalization of air flow over the coil surface. The controller for face and bypass dampers must be located far enough downstream so that the air has become thor oughly mixed before reaching the controller. Other sources of stratification are coils which heat or cool unevenly and coils arranged in parallel and con trolled in sequence. Whenever stratification cannot be eliminated by proper design or arrangement of equipment, special baffles, mixing cham bers or other mechanical devices should be used for this purpose. If stratifi cation still exists at a point where the measuring element of a thermostat is to be located, the use of a long averaging element, or one made up of a number of small elements, may make a suitable temperature measurement possible. This does not solve the other problems relating to stratification which can cause discomfort dr, in extreme cases, freezing of equipment. Good air distribution and properly spaced diffusers and grilles will greatly assist in maintaining even temperatures throughout an area. A space temperature controller cannot prevent drafts. This can be accomplished only by proper attention to such factors as balancing the system, by intro-ducing air in the correct manner, and by providing a suitable low-limit control on the delivered-air temperature. A system that employs constant air volume with variable air temperature results in more uniform distri bution than one which requires variations in air volume to achieve tem perature control. Varying the volume of air affects both ventilation and distribution, two factors which usually have little relation to thermal re quirements. Return air grilles usually can and should be located so as to aid both the distribution and control of the system. A further aid to both distribution and control is the provision of ade quate facilities for exhausting air from the building. The larger the per centage of outdoor air introduced the more important becomes the provi- 920 CHAPTER 39 1956 Guide sion for adequate exhaust. To prevent drafts due to infiltration, it is quite common to provide for positive exhaust of less air than is brought in. On systems where the quantity of outdoor air is large but constant, this may be accomplished by use of a properly sized exhaust , fan. Systems having large internal heat gains, or large solar gains, may use a variable amount of outdoor air up to 100 percent when cooling is required during cool weather. In such cases the outdoor-air quantity may be controlled from space con ditions and the quantity of exhaust air may be controlled by a static- pressure controller set to maintain the space under a slight positive pressure. LOCATION OF SPACE CONTROLLERS Space controllers such as room thermostats must be placed where they will measure the variables they are to control and where the condition is representative of the whole area served by the controller. If the return-air duct is used to represent space conditions, the controller should be located as near the space as possible to eliminate the effect of any heat gain or loss in the duct. . Room thermostats should usually be placed in occupied areas on inside walls or columns. They should never be placed in spaces such as corridors, lobbies, and foyers unless they are used for the control of these areas only. In a typical home which is not zoned a satisfactory location for a room thermostat can usually be found on an inside wall of the living room or dining room. It should always be located toward the center of a relatively open room on the coolest rather than the warmest side of the building. It should not be mounted on an outside wall or other cold surface where it is exposed to cold drafts from an outside door. Neither should it be mounted where it will be affected by direct rays of the sun, by heat from a nearby warm surface such as a chimney, pipes or ducts in the wall, or radiators, or by direct air currents from a register. The location should provide ample air circulation unimpeded by furniture or. other obstructions, and should afford protection from mechanical injury. ' THE CONTROL OF STEAM FLOW The size of an automatic steam vaive is based on the required capacity at maximum load, under the conditions which will exist at that time. Equation 52, Chapter 4, for mass flow through an orifice or nozzle can be rewritten as w = CxVPi - P* (1) where w the flow of steam in pounds per hour. A = the area of the port opening in square inches. Pi = the steam supply pressure, pounds per square inch, absolute. Pi = the downstream pressure, pounds per square inch, absolute. C = a constant for a given steam supply pressure and a given valve body. Valves for two-position operation usually are selected of a size adequate, to supply the required maximum capacity with a reasonably low pressure drop (Pi -- P2). It is necessary only to be sure that the valve will close against the system pressure and will have ample capacity when fully open. Proportional valves for steam service must be carefully sized if stable control is to be achieved. In general the tendency is to oversize such valves and no controller can produce its best results if handicapped by a valve which is too large. The function of the valve is to vary the value of Automatic Control 921 area A in Equation 1 and it is desirable that the flow vary in proportion to the value of A. The correct maximum required capacity must first be determined. There should be no factor of safety in this determination, and it should be based on actual heating requirements rather than on the condensing capacity of the coil, since the coil may be larger than necessary. It is also necessary to base the valve size on the actual supply pressure (Pi) which will exist at the valve, since this supply pressure affects both the density of the steam and the pressure drop which will be selected. Selecting the proper pressure drop (Pi -- P2) across the valve when it is wide open and is supplying the maximum steam requirement is the most important consideration in determining the valve size. For purposes of discussion it will be assumed that Pi is constant and that the valve is sup plying steam to a heating coil which has air entering at a constant temperature and velocity. Any pressure drop between the valve and the coil will be neglected so that P2 represents the pressure in the coil. The condensing capacity of the coil varies with changing values of P2. When the valve is fully open, P2 assumes a value such that the capacity of the valve and the condensing rate of the coil are in balance. If this value of P2 is relatively large, then as the valve is partially closed P2 will decrease until the capcaity of the valve and the condensing rate of the coil are again in balance. Re ducing the value of A in Equation 1 results in an increase in the value of \/Pi -- P2 and partially offsets the. effect of closing the valve. This effect is greatest when P2`is nearly equal to Pi and diminishes as P2 decreases. The minimum value which P2 can assume is established by the return line pressure (or vacuum) of the system. However, P2 may reach a value which results in the critical velocity through the valve before it has been reduced to its minimum value. If so, any reduction of P2 beyond this value has no further effect on the valve capacity. The critical velocity exists when P2 is approximately 58 percent of Pi. The undesirable effect caused by variations in P2 can be eliminated by selecting a valve size such that P2 is at or near its minimum value, or the value corresponding to the critical velocity, whichever is higher, when the valve is wide open. _ On low pressure steam applications it is good practice to base the valve size on a pressure differential equal to 75 or 100 percent of the gauge supply pressure. When the supply pressure is high enough so P2 at the critical velocity (58 percent of Pi) is above atmospheric pressure, the valve size can be based on a pressure differential of 42 percent of Pi absolute. All valves of the same size do not have the same capacityfor a given pressure differential. Having established the supply pressure and the pressure differential, the valve manufacturer's tables or charts should be consulted in selecting the proper size of valve for the required capacity. It is important that the supply pressure to an automatic steam valve be constant because it is difficult for a thermostat to produce stable results if the pressure is constantly changing. This situation arises, for example, when a steam boiler is operated by a two-position pressure controller. A pressure reducing valve, which will supply a constant pressure to the steam mains while permitting the boiler pressure to fluctuate between the limits of the pressure controller, is recommended. Lacking this, the differential of the pressure controller should be set as narrow as is consistent with efficient boiler and burner operation. On vacuum return systems the vacuum pump also should operate on a narrow differential. The use of two automatic control valves in parallel will often provide more stable control than a single larger valve, especially on large coils or steam-to-water heat exchangers. The valves should be sized so that one 922 CHAPTER 39 1956 Guide valve bandies about one-third of the total capacity and the other about two-thirds. They are controlled in sequence so that the small valve oper ates during periods of light load and the large valve begins to open only after the load exceeds the capacity of the small valve. . ' The steam piping from the valve to the coil inlet, and from the outlet to the trap should be the full size of the coil tapping or size specified by the manufacturer of the coil and.should conform to good standard, practice as illustrated in Chapter 21. It is very important that condensate be promptly drained from the coil. When the coil is at reduced pressure, as it will be much of the time, there will not be sufficient difference in pressure between the coil and the return line to obtain any lifting of the condensate. THE CONTROL OF WATER FLOW The capacity of a proportional valve for water service is not influenced by the supply water pressure but only by the pressure differential. If a certain water circuit has a total resistance of 30 psi at maximum flow, of which 1 psi is through the valve, the resistance of the rest of the circuit is 29. psi. When the valve is closed and there is no flow, the entire 30 psi resistance is across the valve. Thus the pressure drop across the valve in creased by a ratio of 30:1 as the valve closed. This increase in pressure drop as the valve opening is decreased offsets partially the effect of closing the valve. It is obviously impracticable to design a water system such that there will be no increase in pressure drop across the valve as it closes. However, it is important to design the system, including the valve, in such a manner that the ratio of this increase in pressure drop as the valve closes is kept as low as possible. Thus, if the design pressure drop across the valve is 5 psi instead of 1 psi, the ratio of increase is only 6:1 instead of 30:1 and the performance of the valve will be improved accordingly. This discussion assumes a circuit in which the entire flow is controlled by a single valve. The same reasoning will apply to the more complicated systems in volving a multiplicity of parallel circuits, each having a valve. In general it can be said that the pressure drop across a water valve at full flow should be a reasonable percentage of the resistance of the circuit in which the valve controls the flow. Due consideration should be given to any re sultant increase in pumping head and operating costs. Water circuits involving variable flow are subject to variable pressures in accordance with the pressure vs flow characteristic of the pump. On suchcireuits it is desirable to provide pressure control by means of a bypass connection around the pump. This bypass connection either has a spring- loaded relief valve, subject to the system pressure difference, or an auto matic control valve operated by a differential pressure controller. The total resistance through the bypass connection at full flow should be equal to the total system resistance. ; . BIBLIOGRAPHY Automatic Control Terminology (American Society ofMechanical Engineers, 1954). .. An Introduction to the Theory of Control in Mechanical Engineering, by R. H. Mac Millan (Cambridge University Press, 1951). Instrument and Control Manual for Operating Engineers, by Eugene W. F. Feller (McGraw-Hill Book Co., 1947). Automatic Control of Heating and Air Conditioning, by John E. Haines (McGraw- Hill Book Co., First Edition, 1953). Save Fuel for Victory (University of Illinois, Engineering Experiment Station Cir cular Series No. 47,.p. 31). . .Air Temperature Gradients in a Panel Heated Room, by J M. Ayres and B. W, Levy (ASHVE Transactions, VoI. 54, 1948, P. 131). CHAPTER 40 MOTORS AND MOTOR CONTROLS Fundamentals of Motor Selection; Alternating Current Motors, Types and Control Equipment; Motor Rating; Functions of Motor Control Equipment; Glossary of Motor Terms, Enclosures, Speed Classification and Mounting THE electric motor, available in many different types suitable for vari ous services, is now the most widely used form of motive power. The equipment for starting, controlling and protecting these motors varies with the type and with the functions it is. desired to attain. Motors are divided into two general classifications, alternating-current or direct-current, depending on the power source to be used. FUNDAMENTALS OF MOTOR SELECTION The following"characteristics of the power supply should be determined: (1) whether current is alternating or direct, (2) voltage, (3) alternating current phase, (4) alternating current frequency, (5) voltage regulation, (6) continuity of power. 1. A-C vs. D-C Systems. For most applications, a-c supply is satisfactory since suitable performance can usually be obtained with a-c motors and control. Where special characteristics, such as an extra wide speed range and Bevere accelerating or reversing duty are involved, conversion by means of motor generator sets, by rec tifiers, or in special cases by converters, may be justified. 2. Voltage. Standard conditions of voltage and frequency are the values listed on the name plate of the motor. Reasonable horsepower design limits are given in Table 1. Power lines are often given voltage ratings known as nominal system voltages which are numerically slightly different from the standardized motor voltages. 3. Phases. Three-phase power supply is most desirable, but only single phase is offered for most residential and rural districts. 4. Frequency. Sixty-cycle systems predominate in the United States. In foreign countries, 50-cycle systems are common and nominal system voltages are frequently different. 5. Voltage Regulation. The voltage regulation of the power supply should be known in order to select motors which will deliver sufficient torque even with the probable drop in voltage, to start and carry the load. All induction motor torques and synchronous-motor starting and pull-in torques vary as the square of the voltage. 6. Continuity of Power. Dips in voltage from switching or other line disturbances may necessitate time-delay undervoltage protection, anil, in case of synchronousmotors, high torque designs and resynchronizing control. Sustained low voltage may necessitate higher torque motors. The following characteristics of the driven machine should be determined: (1) mechanical arrangement including position of motor and shaft, porta bility desired, drive connection, and space limitations; (2) speed range de sired; (3) horsepower requirement; (4) torque; (5) inertia; and (6) frequency of starting. .1. Mechanical Arrangement. Arrangement of the driven machine usually deter mines whether a horizontal or vertical motor is needed. Horizontal motors are more generally available and less expensive; most grease-lubricated ball-bearing motors will operate in either position. Fractional-horsepower waste-packed sleeve-bearing 923 *Sn-- hi. wg', 'i |*u l| fK*s'i htrt 924 CHAPTER 40 1956 Guide Table 1. Reasonable Horsepower Design Limits for Standard Motor Voltages / Power Supply Standard Motor Voltage Suggested Minimum Horsepower Suggested Maximum Horsepower Alternating 1-phase Alternating 3-phase 115 230 HO 220 440-560 2300 4600 6600 None None None 50 100 250 400 1 15 15 200 1000 6000 7500 ' 8000 None motors are satisfactory for short periods of vertical operation where no thrust is involved. If shaft is tilted for momentary operation, special construction of bearing housings will be required for oil-ring-lubricated sleeve-bearing motors, to avoid loss of lubri cant. In case of long periods of tilted operation, bearings suitable for end thrust may be necessary. Ball-bearing motors with grease lubrication are suitable for tilted operation. Most motors are suitable for mounting with base above a horizontal shaft or to one side of the shaft, provided the end shields are rearranged. If, during operation, the angle of the motor (with regard to the horizontal shaft) changes more than 10 or 12 deg, a ball-bearing motor will usually be required. Sleeve-bearing motors are also applicable within the angle given if modified oil gages are provided. On portable machines, motors of greater compactness and less weight than stand ard may be required, and special bearing construction may be needed, except for ball-bearing motors. Direct connection should always be considered where machine speed coincides with available motor speed. Maintenance, efficiency, power factor, space and initial cost, will determine the choice between direct connection and other methods, such as belt, chain or gear drive When direct connection is possible (where parts of the driven machine, such as shaft or bearings, are common with the motor structure) a built-in construction may be advantageous. Belt Drive. Diameters and widths of pulleys or sheaveB and center distances are factors in determining motor-bearing pressures and shaft deflection. Flat belts should not run at greater speeds than about 5000 fpm. Application of flat belting to vertical-shaft motors is difficult. Chain Drive. The chain manufacture should be consulted so that the best drive on a basis of quietness and economy of operation may be selected. Gear Drive. Compactness and arrangement of drive often indicate gear motors, which are obtainable in a variety of mechanical constructions with speed ratios of 3 to 1 upwards, and are generally limited to about 75 hp maximum. Where the pinion of ordinary spur gearing is mounted on the motor shaft, two-bearing motors Table 2. Speed Ranges for Various Types of Motors Power Supply Type Single Phase a-c Poly phase a-c d-c Brush-shifting repulsion motor _ . * Capacitor-motor with tapped winding Multi-speed capacitor-motor . ' Multi-speed squirrel-cage Wound-rotor motor 2-speed wound-rotor motor Brush-shifting shunt motor Brush-shifting series motor . Squirrel-cage motors with variable frequency supply Motor-Generator Set--D-c Drive Motor Rectifiers--D-c Drive Motor Shunt-wound standard constant-speed motor with field control * D-c motor with armature control Adiustable-epeed motor Shunt motor with adjustable voltage supply 'Speed regulation relatively wide. Unsuitable for Bome loads. Speed Range 3:1 2:1 . 2 or 3 fixed speeds 2, 3 or 4 fixed speeds 2:1 4:1 20:1 3:1 Very wide range Very wide range Very wide range 2:1 in some cases Wide From 3:1 to 6:1 Very wide Motors and Motor Controls ' 925 are limited in horsepower ratings. Maximum pitch-line speed with steel pinions is about 1400 fpm. The selection of the motor part of a gear-motor is the same as for a conventional motor. Space limitations may affect the choice of motor and require (a) built-in construc tion; (b) a gear-motor; (c) forced ventilation using an external blower; or (d) a small frame with Class B or H insulation permitting higher temperature rise. 2. Speed Range. Where more than one speed or a range of speeds is required, one of the motor types listed in Table 2 may be applicable, depending upon the power supply and the speed range required. 3. Horsepower Requirement. The horsepower required by the driven machine determines the motor rating. Where the load varies with time, a horsepower vs. time curve will permit determination of the peak horsepower required. The Calcu lation of the root-mean-square (rms) horsepower indicates the proper motor rating from a heating standpoint. In case of extremely large variations in load, or where shut-down, accelerating, or decelerating periods constitute a large portion of the cycle, the rms horsepower may not give a true indication of the equivalent continuous load, and the motor manufacturer should therefore be consulted. ` Where the load is maintained at a constant value for an extended period (varying from 15 min to 2 hr, depending on the size), the horsepower rating required will usu ally not be less than this constant value, regardless of other parts of the cycle. If the. driven machine is to operate at more than one speed, the horsepower re quired at each speed must be determined. 4. Torque.. The torque required to. operate the driven machine at every moment between initial breakaway and final shutdown is important in determining the type of motor. A torque-speed curve is desirable and sometimes essential. The starting torque or breakaway torque required by the driven machine may be as low as 10 percent, as in the case of medium-sized centrifugal pumps, or as high as 225 to 250 percent of full-load torque, as in the case of a loaded reciprocating twocylinder compressor. The breakaway torque may vary greatly at different times because of frequency of start, temperature changes, type and amount of lubricant, etc. The motor torque available at the shaft must be well above the torque required by the driven machine, taking into consideration these variables as well as the pos sibility of low voltage and the type of starter used. The torque required after breakaway for acceleration to full speed varies with dif ferent driven machines, remaining at a rather high value throughout acceleration for such machines as loaded compressors and plunger pumps. The torque delivered by the motor must at all points, up to full speed, be in excess of the torque required by the driven machine. The greater this excess torque, the faster will be the ac celeration. The approximate time required for acceleration from rest to full speed is: where Time in seconds = (rpm) X WRi -t- (T X 308) (1) (rpm) = full-load speed in revolutions per minute. T = average torque available for acceleration, foot-pound. WR* = inertia of rotating parts, pound-foot square. If the time to accelerate on full voltage is greater than about 20 sec, special motors or starters may be required to avoid overheating. 5. Inertia of Driven Machine. The inertia or flywheel effect WRl of the rotating parts of the driven machine affects the accelerating time and, therefore, the heating of motors and control, particularly where reversing duty or frequent starting is in volved. Where synchronous motors are applied, the JFA* must be known, since the pull-in torque required of this motor varies approximately as the square root of the total IVR1 of motor and load. The Wit* of a rotating member of the driven machine which operates at a speed different from that of the motor may be converted to an equivalent value at the motor shaft by multiplying by [(rpm of rotating member) -f- (rpm of motor)]* (2) 6. Frequency of Starting. The frequency of starting the driven machine affects the motor and control by increasing their heating, particularly where accelerating 926 CHAPTER 40 Table 3. Classification of Motobb 1956 Guide Type Speed Character istics Full Voltage Starting Torque Starting Current HP Kangs Application See Footnotes (a) to (e) Constant Speed Drives Squirrel-cage generel Constant purpose Design A Squirrel-cage Design Constant Normal 1-2.5 TTigh 5-8 times'* tunes All N Normal 5-6 Medium times Small S^uirrel-cag Design Constant I times' Sc^.irrel'Cage Design Constant 1Low 1.25 Wound rotor Constant or ttgh 1~2. variable times Normal 5-6 Medium times Small Low 4 times Medium Large Low 1-3 times Synchronous high speed Synchronous low speed Exactly con stant 0.75-1.75 times Exactly con Low 0.3-0.4 stant times Normal 5-7 times Low 3-4 times Medium Large Medium large (a) Fans and (e) centrifugal pumps and centrifugal compressors (a) Fans and centri- . fugal pumps and centrifu gal compres-. sore (5) Reciprocating pumps . (e) and compressors started loaded Fans, centrifugal puippa and compressors (a)Hoists 1 (5) reciprocating pumps and compressors (e) and frequent () or hard start (a) Fans and centri fugal pumps and centrifugal compressors (a) Reciprocating compressors starting un loaded Two value capacitor Permanent split capacitor Capacitor start Constant Constant Repulsion Induction Constant High Low Moderate High Split phase Constant and ad justable Normal Normal Normal Normal Normal Norms! Small Fractional (6) pumps and com pressors (o) Fans, Blowers Small Frac tional Medium Small Fractional (a) Fans and pumps (a) . (b) pumps and compressors (o) Fans (b) pumps and compressors (d ) fans--direct ______ 8 i n ^ 1 Single phase a*c | Adjustable Speed Drives Squirrel-cage high . Variable slip. Transformer! adjustment 1 Squirrel-cage sepa rate winding or regrouped poles Wound rotor Constant multi- speed Variable 1 Normal Normal Normal or high Normal or low ^mtb secondaLryowcontrol) Medium Small All j (a) Fans (o) Fans (b) pumps and ' ` compressors Fans centrifugal pumps and compressors I Repulsion J Variable High Normal Low and Fractional (o) Fans, centrifugal pumps (b) compressors Capacitor low torque' Variable tapped winding two speed Capacitor low torque Variable Low Low Normal Low Fractional Fractional (d) Fans, drect (d) Fans transformer ad justment Split phase re Constant Normal Normal Fractional (d) Fans -g-r-o--u-p-e-d- poles , . a. Drives haring medium or low starting torque and inertia (WR*) such as fans and centrifugal pumps * or rle.ciprocatin~g s_. _ sigahnsdtacrotimngprteosrsqoursess,tasurtcehd ausnrloeacidperdo.cating pumps and compressors started loaded. cept where frequent or hard starting (large WJi*) requires a higher starting and accel erabtin~g torque. d. Fans direct connected. e. Stoker drives. /. Torque depends on bp rating and speed. See NBMA Standard MG 1-4.10 on Motors and Generators. Motors and Motor Controls 927 time is prolonged by high WRT and high load torques. in general, driven machines; starting more than 4 to 6 times per hour may require special motors and control. ALTERNATING CURRENT MOTORS . Alternating current motors are divided into two main classifications: polyphase and single phase (see Table 3), according to the type of power supply. They are further subdivided by type of motor winding. When polyphase power is available it is usually found more economical to apply polyphase motors in preference to single phase motors. A typical 5 hp, 1200 rpm capacitor start-induction run single phase motor, for .in-' stance, will cost approximately twice as much as the corresponding three phase Design B squirrel-cage motor. In addition, the polyphase motor' has the advantage of higher efficiency. : : : ' . : . Table 4. Locked-Rotob Current of Thbee-Phase, 60-Cycle Motors: \ .Y .' at 220 Volts" b ; .... HP .. Design B. C, and D Amperes Design F Amperes HP Design B, C'AND D : DESioif F Amperes Amperes 1 or less 1H _ ~ 2 3 5 m 10 15 20 25 24 35 45 60 90 120 150 220 290 365 30 435 40 580 50 725 60 870 75 1085 100. 1450 125 * 1815 " 150 2170 200 2900 .. 270 360 450 540 675 900 v 1125 1350 1800 * The locked-rotor current of three-phase, 60-cycle, constant-speed, induction motors, measured with rated voltage and frequency impressed and with rotor locked, shall not exceed the tabulated values. b Locked-rotor current at other voltages shall be inversely proportional to the.voltage, For 1 hp or less the value is given per hp. ' Polyphase Motors -- ; The three types of polyphase motors are: squirrel-cage induction motors, wound rotor induction motors, and synchronous motors. Squirrel-cage motors are specific by NEMA standards, providing a variety of speed and torque characteristics. Design A motors provide normal starting torque at starting current in excess of Design B motors, and are suitable for constant speed application to equipment such as fans and blowers. Design B motors provide normal starting torque with NEMA starting current values shown in Table 4, which are acceptable by many power companies for full voltage starting. They are used forithe same type of application as Design A. Design C motors provide high starting: torque with starting current same as Design B, and are used on compressors started without unloaders, and on reciprocating pumps. Design D motors have high slip* and are used with flywheels for widely; pulsating loads onequipment such as reciprocating compressors and pumps where other motors would draw high peak currents. Design F Motors have.low start., ing current and low torques. They are used on power systems of limited capacity. Careful application must be made since the low breakdown; torque provides only limited safety margin for overload or low voltage conditions. A drop in voltage, for instance, could cause the motor to stall.- Figs. 1 and 2 illustrate the characteristics of squirrel-cage motors. The; motor operates under load from near synchronous speed at light Toad to: * Refer to Glossary at end of chapter, ' ' ' 928 CHAPTER 40 1956 Guide about 95 percent synchronous speed at full load. Overloads decrease the speed further until the maximum torque point is reached.' If the load torque exceeds this point the motor will stall.- The motor torque varies as the square of the voltage. If the voltage drops 10 percent, the motor torque will :be only 81 percent of rated value. Both power factor and efficiency are improved if the motor is operating as near rated load as pos sible. In addition, as: shown in Fig. 2, power factor and efficiency are better for higher speed motors. : Wound Rotor motors are used for applications requiring high starting torque at-low starting current, because a wound rotor motor with its con troller and resistance can develop full load torque when starting with about full load current. For comparison, a squirrel-cage motor would require from 3 to 5 times as much current to develop full load torque at starting. The wound rotor motor is also used for varying speed service to drive fans, blowers, and other continuous duty apparatus: The addition-of resistance to the secondary winding of the wound rotor motor changes the speed torque characteristics; The motor speed, with Motors and Motor Controls 929 is desirable to determine what advantages may be gained by improving the. power factor. With purchased power, if the rates include a clause embodying a penalty for low power factor, or a bonus for high power factor, the saving in power costs may often make a very good return on the investment required for the corrective equipment. : : .- ' Synchronous ipotors are used to drive fans, blowers, pumps, compressors and other applications: Compressor applications having a high peak torque require the use of flywheels to smooth out power peaks, and should always be referred to the electrical manufacturer for recommendations. Synchronous motors are provided with built-in damper windings on the rotor and operate during the starting period similarly to squirrel-cage the resistance added, is dependent on. load, and consequently, the motor has very poor speed regulation when secondary resistance is added to re- uce the speed to values below 50 percent. Fig. 3 illustrates the character istics of wound rotor motors. Synchronous motors are used for continuous duty applications at constant speed where efficiency and power factor are important. Another advantage of. these motors is that of lower initial cost in large sizes and for low speeds when- compared with squirrel-cage type motors. The outstanding advantage of the synchronous motor is that its power factor can be changed to compensate for the low power factor of other drives in the same location. Lagging power factor is an inherent charac teristic of all induction apparatus, such as induction motors and neon sighs. Unless synchronous motors or capacitors are installed, the plant power factor may be comparatively low. This does not necessarily mean that corrective equipment must always be installed, but in most cases, it * Refer to Glossary at end of chapter. Fig. 2. Efficiencies and Power Factors for Squirrel-Caoe Induction Motors motors. After the motor is nearly up to speed, field excitation is. applied and the motor draws into step at synchronous speed. After excitation is applied, the motor runs at exactly constant speed and will remain at this speed until a load approaching the pull-out load is reached, whereupon the motor pulls out of synchronism and stops., : : .,. In applying synchronous motors consideration must be given to the torque the motor can develop on pull-in, that is, at the instant when field excitation is applied.. Table 5 shows typical application requirements of synchronous motor drives, listing starting, pull-in, and pull-out torques. MriUi-Speed motors provide flexibility in many types of drives.' Syn chronous motors can be furnished only with a 2 to 1 ratio in speed,, single 1930 CHAPTER 40 1956 Guide winding.' Squirrel-cage induction motors may be 2, 3 or 4 speed. Twospeed induction motors are usually of single winding type, having a 2 to 1 speed ratio such as 600 rpm and 1200 rpm, or may be double winding. Three-speed induction motors are always two winding, and four-speed motors are usually two winding with a 2 to 1 speed ratio in each winding. Motors can be provided in constant torque, varying torque, or constant horsepower ratings. The constant horsepower type of rqotor is consider ably larger than the constant torque motor, due to the fact that the same horsepower must be developed at either reduced speed or high speed. - In selecting two-speed motors for fan, pump, blower, or compressor .applications, it is usually found that two winding motors.are more expensive than the single winding type. The control cost for two-speed, two wind ing motors, however, is more economical, and therefore the combined Fio. 3. Speed-Torque Speed-Current Characteristics of Wound '" Rotor Motors price of both motor and control for the two winding motor is only slightly higher. Because of the improved performance of the two winding motors, and because of the factor of safety provided by two independent windings, the increased cost is frequently worth the difference. Single Phase Motors Single phase induction motors have auxiliary windings or devices for starting, and are classified by the method used. Capacitor start motors develop high starting torque in fractional horse power ratings, and moderate starting torque in larger ratings. They are used for constant speed drive such as fans, blowers and centrifugal pumps. ' -Duringthe starting period, a winding with a capacitor-in series is connected to the motor circuit and when the motor comes up to speed, a centrifugal switch cuts the. capacitor and second winding out of the circuit. --Two-valve capacitor.motors develop high starting torque employing a starting capacitor and a running.capacitor. . The starting capacitor gives -high starting ability, but is suited for short time operation only, and is cut out for the running condition by a centrifugal switch. The running ca Motors and Motor Controls 931 pacitor gives high efficiency at full speed. These motors are used on compressors, reciprocating pumps and similar equipment which may start under heavy load. Permanent split capacitor motors have low starting torque and are ideally suited for small fan drives. Operation is similar to the capacitor start motor, except that the capacitor is not cut out when running. Repulsion-Start Induction-Run motors develop high starting torque. The motors have a wound rotor connected to a commutator for starting. A centrifugal switch shorts the commutator bars when the motor comes up to speed to obtain a winding approximately like the squirrel cage in its function. Repulsion-Start Induction-Run motors are suitable for applications, such Table 5. Typical Application Requirements op Synchronous Motor Drives Showing Starting, Pull-In and Pull-Out Torques Application Method op Connecting Motob to Load Starting Conditions Torques Start Pull- Pull ing in Out Remarks 5 fa Exhaust and venti Coupled or belted lating Usually loadet 50 60-125 150 WR* of fan must be considered Cycloidal positive P Coupled or engine Unloaded type 40-60 40-60 150 Two-speed motors sometimes used 1 Blowing engines re Engine type c ciprocating 5 Unloaded 40 40-60 150 Turbo high speed Direct connected or Unloaded (in 30 step up gear take closed) 50 150 WR* of blower must be considered Air Engine type Unloaded 40 30 150 Flywheel effect im portant Ammonia and am monia booster High 8peed--belted Low speed-^engine type occasionally coupled Unloaded (by by-pass) 40 30 150 Flywheel effect im portant Freon Gas reciprocating High speed--belted Low speed--engine High speed--belted low speed--engine Unloaded (by by-pass) Unloaded (by by-pass) 45 40 50 150 Flywheel effect im portant 30 150 Flywheel effect im portant Compressors as industrial compressors, requiring high breakaway toTque, and where commutator and brush noise are not factors. Split Phase motors have a high resistance auxiliary winding which is in the circuit during starting, but is disconnected through the action of a centrifugal switch as the motor comes up to speed. Under running condi tions it operates as a single phase induction motor with one winding in the circuit. These units are available for the small horsepower ratings, and when equipped with a high slip rotor, may be used for adjustable varying speeds through line voltage control. The motors are ideally suited for fan duty. Speed-torque characteristics of single phase motors are shown in Fig. 4. Full voltage starting of single phase motors is general practice, but since most of these motors are connected to secondary distribution systems located in light load density areas, power companies check carefully, the starting currents in order to prevent objectionable voltage dips. This is particularly important for motors started frequently, such as those con trolled by pressure or temperature sensitive devices and applied to re frigerators, stokers, oil burners, and water pumps. 932 CHAPTER 40 1956 Guide The report of a joint committee of AIEC-EEI-NEMA* recommended three application rules taking into account the greater annoyances re sulting from frequent motor starting during lighting hours against infre quent starting at any time. Table 6 shows typical applications of these rules which are becoming widely accepted for full voltage starting. Rules 1 and 2 apply to general use. Rule 1 limits the locked-rotor current to 20 amp at 115 volts, and 25 amp at 230 volts when automatically controlled (usually frequently started) motors are used. Rule 2 permits twice these values when manually con trolled (usually infrequent starting) motors are used. . Rule 3 applies to F . 4.ig Speed-Torque Characteristics op Single Phase Motors special conditions where larger currents may be allowed above Rules 1 and 2 upon approval of the electric company. Hermetically enclosed single-phase a-c motors are widely used in appli ances such as domestic and commercial refrigerators, room air conditioners, beverage coolers, freezer chests, and water coolers. In such appliances, the motors are sealed inside the compressor, and the gas and oil circulate freely within and around the motor. Centrifugal starting switches are not used on such motors because any arcing in the gas and oil atmosphere would be detrimental, and also because the units are permanently sealed and cannot be serviced or repaired in the field. In place of a centrifugal switch, an external relay is used to start hermetically enclosed motors. Hermetically enclosed motors for refrigeration compressors will, in the future, have the horsepower rating eliminated. The full load current is to be the operating current in amperes, when the compressor is deliver- Refer to Glossary at end of chaste*-' Motors and Motor Controls 933 ing rated output. The motors for hermetically enclosed service are usually of the split-phase type or of the eapacitor-start (or two-value capacitor) type. . For starting the split-phase type of motor, two methods are generally acceptable. In one method a thermally-operated time delay is used. When the motor is started, a contact which is normally closed applies power to the starting winding. A thermal element which controls these contacts is in series with the motor and carries line current. Due to the current flow through this element, it is heated until, after a definite period of time, it is warmed sufficiently to open the contacts and remove power from the starting winding. The running current then heats the element enough to keep the contacts open. The setting of the time for the starting contacts to open is determined by tests on the system components, i.e., Table 6. Recommended Single Phase Motor Ratings for Full Voltage Starting HP Rating Locked-Rotob Current* at 25 C Amperes General Use (Rules 1 & 2) Special Conditions (with Uttlitt Permission) (Rule 3) ' 115 V 230 V 115 V 230 V 115 V 230 V Ho hi hi H hi hi % 1 1 hi 5 20 20 20 23 31 45 61 70 10 10 10 11.5 15.5 22.5 30.5 35 A-M A-M A-M A-M M M A-M A-M A-M A-M A-M A-M M M A-M A-M A-M A-M A-M A-M A-M A-M A-M A-M A-M A-M A-M A-M A-M A-M 40 M A-M 50 M A-M 70 A-M 100 A-M A refers to automatically controlled devices. M refers to manually controlled devices. These values of Locked-rotor current are the same as the NEMA standard for single-phase Design M the relay, the motor, and the compressor, and is based on a prediction of the amount of time delay required to bring the motor up to speed. The second method of starting split-phase motors utilizes a series-coil or current-operated relay. This device is affected indirectly by motor speed. In this type of connection, a relay coil carries the line current going to the motor. When the motor is started, the inrush current to the running winding, passing through the relay coil, causes the contacts to close, and applies power to the starting winding. As the motor comes up to speed, the current decreases until at a definite calibrated value of current corre sponding to a pre-selected speed, the magnetic force of the coil diminishes to a point which allows the contacts to open, removing power from the starting winding. Capacitor-start and two-value capacitor hermetically seeded motors are usually started with a voltage-type relay. In this method of starting the relay coil is connected in parallel with the starting winding. When power is applied to the line, the relay does not operate because it is calibrated to operate on a higher voltage. As the motor comes up to speed, the voltage across the starting winding and relay coil increases in proportion to the motor speed. At a definite voltage corresponding to a pre-selected speed, the relay operates and opens its contacts, thereby opening the starting 934 CHAPTER 40 1956 Guide . winding circuit. The relay then keeps these contacts open because there is sufficient voltage induced in the starting winding, when the motor is running, to hold the relay in the open contact position. CONTROL FOR ALTERNATING CURRENT MOTORS Squirrel-Cage motors are usually linestarted where power company limitations permit. In sizes up to 5 hp at 220 volts, or 7| hp at 440 volts, polyphase motors may be started by means of manual switches having overload current elements for motor protection. In larger ratings a linestarter is usually provided with either an additional safety switch or circuit breaker for disconnecting and short circuit protection. Reduced voltage starting may be used when the current inrush on full voltage ex ceeds the limitations set by the power company. The magnitude of this inrush current is entirely independent of the load on the motor, and is the same whether the motor is lightly loaded or heavily loaded. Table 7. Comparison op Squirrel Cage and Synchronous Motor Starting Methods Type op Starter Full Voltage Starter . Percent op Motor Rated Values Line Voltage 100 Starting Torque 100 Line Current 100 Autotransformer 80 percent tap 65 percent tap 50 percent tap Resistor, single step 80 64 68 65 46 50 25 30 80 64 80 Reactor 50 percent tap 45 percent tap 37.5 percent tap Part Winding * 50 45 37.5 60 25 20 14 50 50 45 37.5 .60 Restrictions on starting current may limit the maximum current inrush or may limit the increments of current inrush which may be drawn on each step. Table 7 shows a comparison of the various methods of reduced voltage starting. The choice may depend upon the limitation to be met. Fig. 5 shows examples for maximum current limitations. Fig. 6 shows examples for increment limitations. The increment starters would not be satisfactory for meeting maximum current limitations as they exceed the maximum value before the motor reaches full speed. Both Curves B and C of Fig. 6 would be satisfactory if the increment limitation were 400 per cent but only the starter illustrated by Curve C would meet a limitation of 200 percent increments. When increment starters are used the motor may not develop enough torque to start until the last step. Fig. 6 shows that with the resistor step starter the motor does not start until step 3 or after 2 seconds on Curve C. Part-winding motors may start and then stall at about half speed until the second step which applies full torque. The load inertia (WK2) may also affect the selection of reduced current starting method since the reduced torques may not be sufficient to accel erate the load without overheating the motor or in the case of synchronous motors, may not reach sufficient speed to pull into synchronous speed. Motors and Motor Controls 935 Curve A Full Voltage Starter Cubve B Reactor . 50 Percent Tap Cubve C Autotranspormeb 65 Percent Tap . Fig. 5. . TIM -- SCCONOS ' Starters for Maximum Current Limitations In these cases the solution may be to use the wound-rotor induction motor or some means of reducing the load such as suction dampers on compres sors. Fig. 7 illustrates recommended control practice for squirrel-cage motors. Wound,-Rotor motors require control of both primary and secondary circuits. The primary* control may be the same as for squirrel-cage motors, manual or magnetic, at full voltage. Secondary* control pro vides means of varying secondary resistance for starting and speed control. The secondary controller should be specified for starting duty only, or for speed regulating duty. If the secondary controller is to be used for speed regulating duty, the percent speed reduction, the number of speed control points, and the type of load (variable or constant torque) should be speci fied. Fig. 8 illustrates recommended control practice for wound rotor motors. Synchronous, motor starters should provide pull-out protection, auto matic synchronization or automatic stopping of the motor after pull-out, and insurance of complete starting sequence, as well as overload and low voltage protection. The control may be either magnetic or semi-magnetic, at full or reduced voltage. Semi-magnetic starters provide automatic field control, but require hand operation for closing the line contactors to start and transfer to full voltage. Curve A Full Voltage Starter- Cubve B Part Winding Starter Curve C 4-Step Resistbb Increment Starter 0 Fig. 6. I ? i4 4 Tint -- SECONDS Starters for Increment Limitations * Refer to Glossary at end.of chapter. 4 ; ** ` 936 CHAPTER 40 1956 Guide In applying reduced voltage starters to synchronous motors it should be remembered that, since these motors are started on damper windings and function during, the acceleration period similarly to squirrel-cage motors, the starting torque varies as the square of the applied voltage. Consideration should be given to insure development of sufficient motor torque to accelerate the load. \ Multi-Speed control may he either manual or magnetic, and at full or reduced voltage.. When using automatic magnetic control with two-, three-, and four-speed separate winding or consequent pole motors, con trol may be obtained from a remote point by means of a push button master switch. The various speeds of the motor are obtained from the master switch by simply depressing the correct push button. This is known as selective speed, control. It is commonly used in the smaller theater installations where the fan and motor are located backstage and the speed control is located in the lobby. ACROSS THE LINE STARTING IKIW' 'I' ! REDUCED VOLTAGE STARTING 1j' li! : |; I ;j |; ; ij ] f :| 1 :! ; < ![ . |j .h |;j ` j'j '1 I. i ! Arrangements 2, 4 and 5 provide automatic push-button starting. Fig. 7. Recommended Controls for Squirrel-Cage Motors Multi-speed motor controllers may be provided with compelling relays which make it necessary for the operator to press the first speed button before regulating the motor to the desired speed. This insures that the motor is always started at low speed before adjusting to a higher speed. Timing relays which provide for automatic acceleration may be used for control. With this feature the motor will always start at low speed and automatically accelerate to the desired speed". Decelerating relays may be used to reduce the shock effect of the braking action on the motor and drive when the speed is reduced from a higher to a lower speed. Single Phase motor control usually consists only of a linestarter, either manual of magnetic. In some cases it is desirable also to provide a disconnect switch. Fig; 9 illustrates the recommended controls. MOTOR RATING The rating of an electric motor depends upon the total temperature which the motor attains under operating conditions. This total temperatore depends on both the ambient temperature and the temperature rise of the motor. As motor temperature rise is in turn determined by the ability of the motor to dissipate heat, circulation to the motor should hot Motors and Motor Controls 937 be restricted. Improper selection of motors with regard to temperature ratings may. result in high motor operating temperatures and accompany ing reduction in motor life. FUNCTIONS OF CONTROL EQUIPMENT FOR MOTORS In general, control equipment for all types of motors should provide (1) means of disconnecting the motor from the power supply, (2) means for starting the motor, (3) overload protection for the motor, (4) protec tion against low voltage, and (5) means for varying the motor speed. Full voltage starting for motors is preferable because of its lower first cost and simplicity of control. Except for d-c machines, most motors are mechanically and electrically designed for full voltage starting. The starting inrush current, however, is limited in many cases by regulations of power companies because of the voltage fluctuations which may be caused by heavy.current surges. It is therefore often necessary to reduce 1 O SAFETY M SWITCH M LINESTARTER | RHEOSTAT MOTOR LINE 3 O SAFETY LJ SWITCH m SPEED 111 REGULATING Up CONTROLLER [*] COMBINATION |o| LINESTARTER T I RHEOSTAT 161 MOTOR LINE m UNIT |V 1 ASSEMBLED [J CONTROL iSFfir MOTOR 4tafir motor Fig. 8. Recommended Controls for Wound Rotor Motors the starting current , below that obtained by across-the-line starting. The power supplier should be consulted to determine the allowable inrush cur rent for any given location. The choice between full voltage and reduced voltage starting is governed almost entirely by inrush cun-ent limitations. The starting torque of all motors varies with the starting current, and it is therefore necessary to insure that the motor is supplied with sufficient current to develop enough torque to accelerate the load. In present practice overload protection of motors is obtained by use of thermal overload inverse time limit type protection. The usual setting of such protection devices is not to exceed 125 percent of rated full load current for open 40 C rise motors, and not to exceed 115 percent of rated full load current for all other motors, the element tripping after a definite interval of time. The National Electrical Code requires the addition of uses or circuit breakers to protect the overload elements from severe short circuit currents. Two types of protection are available against low voltage at the motor terminals. One type, called low voltage release, permits the motor line contactor to drop out on low voltage and to close again when the voltage feturns to normal, thereby restarting the motor when the abnormal condi- 938 CHAPTER 40 1956 Guide tion is ended. The second type, called low voltage protection, causes the motor line contactor to drop, out on low voltage, but prevents restarting when the voltage returns to normal except by the action of an operator. This latter type of protection is desirable where it is necessary for the operator to make initial starting adjustments on the machine. Manual control for an alternating or a direct current motor is usually located near the motor. When so located an operator must' be present to start and stop or change the speed of the motor by operating the control mechanism. Manual control is sometimes employed only as a device to give overload protection, and another device is employed to start and stop the motor. Manual control is used particularly on small motors which operate unit heaters, small blowers, and room coolers in an air conditioning system. In other cases manual control in the form of drums, when used with multi-speed motors, is used only as a speed setting device, while the Arrangementa 2, 3 and 4 are optional for motors up to 1Yi bp, 220 volts. Fig. 9. Recommended Controls for Single Phase Motors starting and stopping functions operate automatically through thermostats and pressure switches. Because of the increasing complexity of air conditioning systems, the-, , equipment is operated preferably by automatic control, and less dependence? is placed on manual operation and regulation. : Automatic control of motor starters may be accomplished by the use of remote push button stations, by a thermostat, float switch, pressure. ; regulator, or other similar pilot devices. An added advantage of auto-: : matic control is that the main wiring for the starter may be installed nearthe motor, while the starter may be operated by a remote control device:'.* GLOSSARY General Definitions ' NEMA is the abbreviation for the National Electrical Manufacturers Association _ AEIC is the abbreviation for the Association of Edison Illuminating Companiesity_ EEI is the abbreviation for the Edison Electric Institute. Speed Regulation (d-c motors) is the change in speed between no-load and r load, expressed in percent of full-load speed; for example, a motor having a no-load^,' speed of1200 rpm and a full-load speed of 1140 rpm would have a speed regulation of \. 5.26 percent. Slip (a-c induction motors) is the difference between the motor speed and ayn-/^* chronous speed expressed in percent of synchronous speed, e.g., a 1200 rpm motor-v- operating.at 1140 rpm would have a slip pf 5 percent, `tS&ai iis Is Motors and Motor Controls * 939 Torque is an expression of the turning effort developed by the motor at the shaft, and is usually expressed in ounce-feet for fractional horsepower motors, and in poundfeet for motors of larger ratings. Primary is the term usually applied to the high voltage or line side of a transformer or motor. In the case of the wound rotor motor the primary is the stator winding. Secondary is the terra usually applied to the low voltage or load side of a trans former or motor. In the case of the wound rotor motor the secondary is the rotor winding. : NEMA Classification of Motor Enclosures . Open motors (40 C rise, rated load, 50 C rise, service factor load) are self-ventilated machines having no restriction to ventilation other than that necessitated by me chanical construction. Guarded motors (50 C Rise) have all ventilating openings limited in size by either' design of structural parts, perforated covers or screens preventing direct access to live or rotating parts. . Semi-Guarded motors (50 C rise) have the ventilating openings in the top half of the frame only protected by perforated covers. Drip Proof motors (50 C rise) are so constructed that drops of liquid or solid par ticles falling on the machine at any angle not greater than 15 deg from the vertical, cannot enter the machine either directly or by striking and running along a hori zontal or inclined surface. Splash Proof motors ,(50 C rise) are so constructed that drops of liquid or solid particles falling on the machine or coming toward it in a straight line at any angle not greater than 100 deg from the vertical, cannot enter the machine either directly or by striking and running along the surface. Totally Enclosed Non-Ventilated motors (55 C rise) are so constructed as to pre vent exchange of air between inside and outside of the case, but are not air tight and are not equipped with external cooling means. Totally Enclosed Fan-Cooled motors (55 C rise) are similar to totally enclosed, nonventilated machines, except that exterior cooling is provided by means of a fan or fans integral with the machine. Explosion Proof motors (55 C rise) have an enclosing case designed to withstand an explosion of a specified gas or vapor which may occur within it, and to prevent ignition of the gas or vapor surrounding the motor by sparks, flashes, or explosions of the gas or vapor which may occur within the machine casing. Dust Explosion Proof motors (55 C rise) have an enclosing case designed and con structed so as not to cause the ignition or explosion of an atmosphere of the specific dust, or to cause ignition of dust on or around the machine. (Proper overload pro tection and cleanliness are required for successful operation). - Water Proof motors (55 C rise) are so constructed as to exclude water applied in the form of a stream from a hose. Motor Speed Classifications A Constant Speed motor is one in which the speed remains practically constant with changes in load; e.g., a d-c shunt wound motor or a-c squirrel-cage motor with low A Varying Speed motor is one in which the speed varies with the load, usually decreasing when the load increases; e.g., a d-c series motor or an induction motor with large slip. An Adjustable Varying Speed motor is one in which the speed can be adjusted l^dually, but when once adjusted for a given load will vary in considerable degree with change in load; e.g., a shunt wound d-c motor adjusted by armature resistance control. An Adjustable Speed motor is one in which the speed can be varied gradually over * considerable range, but when once adjusted remains practically unaffected by the ad; e.g., a d-c shunt motor with field resistance control. The standard ratings for pen type, adjustable speed motors, having a speed range of 3 to 1 and greater are 11 accordance with the following: (1) A standard continuous horsepower rating at 150 percent of minimum speed with a temperature rise of 40 C. (2) The next higher standard continuous horsepower rating at 3 times minimum speed with a temperature rise of 40 C. 940 CHAPTER 40 1956 Guide (3) Between 150 percent of minimum speed and 3 times minimum speed, the stand ard continuous horsepower rating with a temperature rise of 40 C will vary with the speed along a straight line connecting these two horsepower ratings. No further increase in horsepower is recognized above 3 times minimum speed. (4) Below ISO percent of minimum speed the lower continuous horsepower rating (see preceding item 1) will apply with a temperature rise of 50 C. Example: 20/25 hp, 400 to 1600 rpm. This motor may be rated 20 hp, 40 C at 600 rpm and 25 hp, 40 C from 1200 to 1600 rpm. Between 600 and 1200 rpm the rated horsepower increases directly with speed from 20 to 25 hp. (5) Motors may also be rated 1 hour with temperature rise of 50 C with the higher horsepower rating (see preceding item 2) throughout the entire speed range. Example: 20/25 hp, 400 to 1600 rpm. This motor may be rated 25 hp, 50 C 400/1600 rpm; 1 hour. Mechanical Modifications Vertical Mountings are available for such applications as pumps and agitators. This type of application may require a special umbrella-type hood to prefect against dripping liquids. Flanged Mountings are available for use where motors are built in as part of ma chines. Motors may also be supplied with flush plate mountings, suitable for close coupled pump and similar applications. CHAPTER 41 SOUND CONTROL Unit of Noise Measurement, Apparatus for Measuring Sound, General Problem, Kinds of Noise, Noise Transmitted Through Ducts, Design Room Noise Level, _ Noise Generated by Fans, Natural Attenuation of Duct System, Duct Sound Absorbers, Air Supply Noises, Cross Transmission Between Rooms, Controlling Vibration from Machine Mountings IN ventilating and air conditioning a building or a room, consideration must be given to the effect of the mechanical system on the acoustics of the space conditioned. It is important to consider also that the use of air conditioning often permits keeping the windows closed, thus giving relief from certain external noises, but at the same time increasing the necessity of providing adequate sound control. It is assumed that in a given space the architect and acoustical engineer have produced a room or rooms which are satisfactory for speech, music, or other uses. The ventilating engineer's sole function is to ventilate and air condition these rooms properly so that they will be physically comfortable without adding any acoustical hazards. UNIT OF NOISE MEASUREMENT According to an international standard, the decibel (db) is the unit for expressing sound pressure levels. The sound pressure level, in decibels, is given by the relation: d6 = 201oe'(o-i) (1) where P = the sound pressure in dynes per square centimeter. The reference pressure (0.0002 dynes per square centimeter) is a sound pressure which is slightly less than the threshold of audibility, at the frequency of 1000 cycles per second, for the person of average hearing. This reference point is approximately the minimum sound pressure that would be audible in a very quiet room to an observer having acute hearing. The ear is essentially a pressure operated device; hence, the sensation of loudness, or magnitude of sound is governed by. the sound pressure existing at the point of reception. The sound level meter measures sound level pressure, the measurement being expressed as sound level on a decibel scale with zero corresponding to the reference pressure of 0.0002 dynes per sq cm at 1000 cycles. In the higher ranges of the decibel scale, approaching 120 db, the sensation is one of feeling, and at higher levels the sensation becomes painful. Associated with sound pressure level is the sound intensity level, expressed m decibels above a standard reference intensity. Sound intensity is the average rate of sound energy transmitted through a unit area normal to the direction of propagation, commonly expressed in watts per square centimeter. The sound intensity level, in decibels, is given by the relation: 941 -V# 942 CHAPTER 41 1956 Guide db = 10 log,, , (2) where I = the sound intensity in watts per square centimeter. The reference intensity is 10~16 watts per square centimeter, coinciding with the reference pressure of 0.0002 dynes per sq cm or 2 X KT-4 microbar. A microbar is the unit of pressure commonly used in acoustics, one micro bar being equal to one dyne per sq cm. The relationship of the decibel scale to sound pressure and sound in tensity is shown in Table 1. A stated sound level in decibels, under standardized procedure, will thus be related to a threshold of 0.0002 dynes per square centimeter, or to a threshold of 10~16 watts per sq cm. The standardization upon terminology, procedures and reference levels may be found in Standards1 published by the American Standards Association. APPARATUS FOR MEASURING SOUND The measurement of sound or noise is conventionally made by means of a sound-level meter2 consisting of a microphone, an amplifier, a variable attenuator, weighting networks, and an indicating meter which reads directly in decibels. The approved sound-level meter must comply with the specifications of the American Standard for Sound Level Meters for Measurement of Noise and Other Sounds, Z24.3-1944, approved and published by the American Standards Association. The meter is designed to indicate sound level above the standard reference level. Three measur ing networks are generally provided: (1) flat response, (2) 70 db network and (3) 40 db network. The various networks are approximations of the equal-loudness contours relating intensity and frequency sensation response of the normal human ear.1 Where there are no specific codes which specify the particular .network to be used, general practice would indicate use of the 40 db network for sound levels up to about 55 db, the 70 db network for sound levels from about 55 db to 85 db, and the flat response network for higher levels. When sound level measurements are stated, the specific weighting network used, i.e., 40 db, 70 db or flat response, should always be reported. Complexity in design and calibration, and variations in component parts of the sound level meter impose some deviation from design objective response. Allowable deviations in response or accept able tolerations recognized in the Standard, vary from 2 db in the 1000 cycle range to 5 db, or more, below 100 cycles and above 1200 cycles per second. GENERAL PROBLEM OF SOUND CONTROL The problem confronting the air conditioning engineer is to design a system which will operate without increasing the noise level in the con ditioned space. It is therefore necessary: 1. To determine the noise level existing without the equipment. 2. To ascertain the noise level which would exist if the equipment were installed without sound control. 3. To provide as a part of the installation, sufficient sound control appliances and treatment to reduce the sound level due to the installation to a sound level at least three decibels, and preferably five decibels, below that found in Item 1. To accomplish this the engineer should have information of three kinds: . 1. A knowledge of the noise levels currently considered acceptable in various rooms, in order that he may Have a basis on which to proceed. Sound Control 943 Table 1. Decibel Scale vs. Sound Pressures and Sound Intensities Decibel . Level Pressure dynes per sq cm Intensity watts per sq cm Decibel Level 0 0.000200 1.000 X 10-> 40 i 0.000224 1.259 X 10-'6 50 2 0.000252 1 585 X 10-" 60 3 0.000282 2.000 X 1(T" 70 4 0.000317 2.520 X 10-" 80 6 0.000399. . 4.000 X 10-" 90 8 0.000503 6.310 X 10-" ' 100 10 0.000631 1.000 X io-" 110 20 0.00200 1.000 X 10"" 120 30 0.00631 . 1.000 X 10"" Pressure dynes per sq cm 0.0200 0.0631 0.200 0.631 2.00 6.31 20.0 63.1 200.0 Intensity watts per sq cm 1.000 x 10-" 1.000 X 10-" 1.000 X 10-" 1.000 X 10" 1.000 X 10-* 1.000 X 10"7 1.000 X 10-' 1.000 X 10" 1.000 X 10-* 2. A knowledge of the nature and intensity of the noise created by the various parts of the equipment. 3. A knowledge of how, when necessary, to vary and control the noise level be tween the equipment and the conditioned space. In addition, the engineer should have sufficient information to predict the levels produced by noises which may be transmitted by the duct system from one conditioned space to another, or from an outside space to the conditioned space. In either case, the designer must know the proto able noise level at the point where the noise originates. From this he can compute the attenuation or transmission loss required in order to bring this level down to that required in the conditioned space. If there is likelihood of direct transmission through a duct, the attenuation required may be computed as shown in section Noise Transmitted Through Ducts. If the transmission is through dividing walls, it will be necessary to refer to published data on losses through standard building constructions.5 Information concerning the sound levels created by ventilating and air conditioning equipment such as fans, motors, air washers and similar items, has not yet been completely established. However, numerous manufacturers are in a position to supply such data for many of their products. Additional information is being collected. Uniformity in method of test and presentation of sound measurement data for fans, has been standardized in the Sound Measurement Test Code for Centrifugal and Axial Fans, developed by the National Association of Fan Manufac turers. The Code prescribes that the sound level shall be measured by the flat response network of the sound-level meter. Readings on the 40 db and 70 db networks may also be taken and reported, but the flat response reading is required to comply with the Code requirement. General prac tice is to use the slow or damped needle reading of the meter. The fast or undamped needle of the indicating meter generally reads one to two db lower than the slow or damped meter needle. The same Code prescribes a method of determining the sound level reading at each of seven stations, spaced at 5 ft from the outside of the fan housing, and located in a hori zontal plane passing through the fan shaft. The sound level of the fan 18 ,^e average of the seven readings. The level so determined is valuable primarily for comparative purposes rather than absolute values. Of more value to the design engineer would be the sound level at the fan outlet and at the beginning of the distribution duct system. . ., The technique of sound measurement in a moving air stream of ap- 944 CHAPTER 41 1956 Guide preciable velocity has not yet been mastered, although it is a subject of current investigation. Development tests indicate that the sound level at the fan outlet is in the order of 10 to 15 db higher than the average value determined by the seven-station traverse around the fan. Where sound treatment of a distribution duct is required, the initial level should be taken as approximately 12 decibels higher than the reported Code rating sound level. KINDS OF NOISE In solving a sound problem, it is desirable to consider, separately, the several means by which noise reaches the room. This avoids to some.ex tent the necessity of knowing the noise level at the source, and instead, places the emphasis on ascertaining the level at the point where the sound enters the room. . . The noise introduced into a room or building by ventilating or air conditioning equipment may be divided into two general kinds, depending on how it reaches the room: ' 1. Noise transmitted through the ducts. a. From equipment such as fans, motors, pumps, sprays, etc. ' b. From outside, and transmitted through duct walls into air stream. c. From duct wall vibrations, transmitted into air stream. d. From air currents, including eddying noises. r- e. Cross talk and cross noises between rooms connected by. the same duct sys tem. , /. Noise produced by the grilles. . - 2. Noise transmitted through the building construction. , a. From machine mountings as vibration. b. From equipment through'room wall surfaces. J ' The next step in the solution of this problem is to; present data and discuss methods whereby solutions of the noise problem can be obtained when the allowable room noise level, and the path through which the noise reaches the room, are known. ; NOISE TRANSMITTED BY AIR THROUGH DUCTS - Operation of an air distribution system results in the generation of noise which may be transmitted by air through the ducts to the ventilated or conditioned room. The transmission of this noise may be controlled by the proper application of sound absorptive material within the^ ducts. The application of the absorptive material is a problem in balancing the room noise level requirements against the intensity of the noise generated. The four steps in the problem are: 1. Determination, of acceptable room noise level resulting from the operation of the equipment. 2. Determination of noise, level generated by the equipment. Add 5 decibels to the difference between items 1 and 2 to obtain the overall noise reduction required between the equipment and the room. In the discussion whicn follows, reduction of noise will be referred to as attenuation of noise. - 3. Determination of the natural attenuation of the duct system. 4. Selection of the proper sound treatment for the duct system. The difference in decibels between the overall attenuation required and the nat ural attenuation (3) is the additional sound attenuation to be provided by absorp tive materials installed in the duct system, or by special constructions designed to absorb sound. Experience has shown, for example, that where ventilating require ments permit, introduction of an expansion chamber or a change in area in the duct will frequently provide further reduction in low frequency noise. Sound Control 945 , Table 2. Typical Sound Levels* Weighted Network Response Sound Level in Decebexb to be Anticipated Sound Film Studios.............. Radio Broadcasting Studios Planetarium............................. Residence, Apartments, etc. Theaters, Legitimate............. Theaters, Motion Picture__ Auditoriums, Concert Halls, etc. Churches.................................... Private Offices, Acoustically Untreated...................... General Offices................................................................... Hospitals.............................. ....... ........................................ Class Rooms ...............:...............................................' ' '. Libraries, Museums, Art Galleries................................ Public Buildings, Post Offices, etc................................ Court Rooms.......... ............................................................ Small Stores'Trr;.--.......................................................''. Upper Floors Department Stores.................................. Stores, General, Including Main Floor Dept. Stores.. Hotel Dining Rooms.................................. :;.................. Restaurants and Cafeterias........................................... Banking Rooms.................................................................. Factories....................................................................... ' ' ' Office Machine Rooms...................................................... Min, Represent ative Max. 10 14 20 10 14 20 15 20 25 33 40 . 48 25 30 35 30 35 40 25 30 40 25 30 35 30 38 45 35 43 . 50 50 60 70 25 40 55 30 35 45 ' 30 40 45 45 55 ' 60 30 35 45 40 50 60 40 50 55 50 60 70 40 50 60 50 60 70 50 55 60 65 77 90 60 70 80 Vehicles Railroad Coach .. Pullman Car......... Automobile.......... Vehicular Tunnel . Airplane............... 60>> 70 80 55b 65 75 50 65 80 ' 75 85 95 75 80 90 * These values are tentative. More detailed measurements by D. F. Seacord, Bell Telephone Labora- . n ('Wnial Acoustical Society of America, Vol. 12, pp. 183-187, 1940) give average values and standard oeviatwns of room noise in residences, offices, stores, factories, etc., in large American cities. tor tram standing in station, a level of about 45 db is the maximum which can ordinarily be tolerated. DESIGN ROOM NOISE LEVEL . Measurements of sound levels in various types of rooms andi locations have been observed by numerous investigators. However, close agree ment upon these values has not been realized, and more detailed measure ments are needed to accurately establish the normal sound levels in occupied spaces and enclosures subject to sound analysis and control Typi cal sound levels, of a tentative nature, based upon earlier determinations, Are listed in Table 2. The levels listed are; weighted levels by the 40 db or 70 db network, depending upon the. range of level, existing. Levels taken upon the flat response network, may be from 5 db to 20. 4b higher, as governed by the predominating frequencies which may influence the weighting level. .' Table 3 lists sound levels based upon more recent surveys than. Table 2, and upon the basis of the flat response network. The flat response net-, work offers a more logical correlation of space sound level to fan sound level which, under present practice, is reported upon basis of the flat response reading. .. . - The values listed were determined with the air conditioning or ventila- 946 CHAPTER 41 1956 Guide Table 3. Avebage Sound Conditions in Vabious Types op Rooms and Buildings* ! Flat Response Network ' Type or Room ok Building Decibels 20-30 (very quiet) Residences, churches, libraries, apartments, auditoriums, execu- 40-55 . (quiet) Hospitals, court rooms, quiet offices, show rooms, small retail stores, tea rooms, hotel dining rooms, foyers, upper floors of department stores, recreation rooms............................................. 45-60 (moderately (quiet) Banking rooms, beauty salons, barber shops, general offices, 55-70 restaurants, main floors of department stores, cocktail lounges, . (average) dairy bars, tap rooms, billiard halls......................................... . Gymnasiums, transportation waiting rooms, drug stores, grocery stores, cafeterias, super markets, recreation halls, post offices, swimming pools, locker rooms, garages, service stations, dance halls, laundries, dry cleaners, bowling alleys............. ................ 65-80 (moderately . noisy) Warehouses, office machinery, field houses, hangars, skating rinks, loading platforms, packing plants, factories, machine shops, foundries, forge shops, round houses, steel mills......... 75-100 (noisy) Values based on recent surveys. tion equipment out of operation, unless such. equipment presented no acoustical addition to normal conditions. The windows and doors were closed to simulate the conditions of normal occupancy. In Table 2, minimum, representative and maximum levels are given for each type of space, classified as shown in the following paragraph. In Table 3, the minimum to maximum range is shown, with the same general classification. Minimum sound level refers to spaces within well-constructed buildings, typified by double windows, carpeted floors, and acoustically-treated walls and ceilings. In such spaces heavy upholstered furniture is also usually used. Representative sound level refers to spaces within average construction with average furnishings, and exposed to external sounds typical of the locality in which the space is usually found. ' Maximum sound level refers to (1) any space within inexpensive con struction where bare furnishings are used, and where noise is normally not an important factor, or (2) spaces in close proximity to very intense street- traffic or industrial noise. In general, if the sound level in the space resulting from the operation of the air conditioning equipment only, is equivalent to, or less than, the typical level (from Tables 2 or 3 or, better still, determined by actual site measurement) the installation will prove satisfactory. If the space level and the equipment level are equal and heard together, the resultant level vill be 3 db higher than either space or equipment level alone. However, to minimize possible annoyance due to introduction of single or distinctive frequency components from the equipment, it is desirable to design for an equipment sound level of at least 5 db below the typical space level. NOISE GENERATED BY FANS Noise generated by fan wheels may be divided into two classifications, rotational noise and vortex noise. The rotational noise may be described . Sound Control 947 as that due to the thrust and torque applied to the air. Vortex noise is that due to the shedding of vortices from the blade, and is dependent on the angle of attack, velocity, air turbulence, and blade shape. Vortex noise is due to pressure variations on the blade as a result of variations of air circulation. Given the noise level at the outlet or inlet of one type of fan construction under specific conditions of size, tip speed, and total pressure, the noise levels at other values of tip speed, total pressure, and size may be approximated by the relationships: . 1. For constant size and point of rating, the noise level of a fan will increase with increasing speed. `'*1/ . 2. For constant pressure and tip speed, the noise level of a given type < increase with increasing fan size. db (change) = 20 logio (4) Fan size refers to wheel diameter, housing height or some dimension that is di rectly proportional to linear units. Fan sizes based on arbitrary systems or systems i preferred numbers, have no significance. The noise of a given fan is not constant at constant speed if the air delivery changes due to change of resistance. In general, a backward curved blade fan is lowest in noise at or near the point of maximum effi ciency; a forward curved blade fan at or between the point of maximum efficiency and shut-off; an axial flow fan at or between the point of maximum efficiency and free delivery. The noise level of a double width fan may be taken as 3 db higher than for a similar single width fan operating under the same conditions of speed and pressure. The sound level characteristic curve of a typical ventilating fan of the centnfuga] multi-blade type is shown in Fig. 1. The accented portion el the curves denotes the range of minimum sound emission. The selecjon and application of the fan should be made within such good applicalon range where quietness of operation is of major consideration. The anous types of fans available possess individual sound level character istics throughout their range of possible operation. Recourse to standard 948 CHAPTER 41 1956 Guide': Sound Control 949 Fig. 2. Sound Level Characteristics of Typical Vaneaxial Fan test rating information should be made to arrive at the sound emission of a particular type. In general, that size of fan which is so selected as to operate at or near peak static efficiency, will also provide the lowest sound level attainable with the particular type and design of fan. The characteristic trend of the sound level curve of a typical vaneaxial fan, adaptable to moderate pressure ventilation requirements, is shown in ; Fig. 2. The sound level of a particular fan is primarily governed by the operating speed required to produce a desired delivery against the system static pressure. Fig. 3 illustrates the variation of fan sound level in deci bels with operating speed, the fan operating in connection with a conven tional fixed system. The influence of high static pressures is evident in increased operating speed and higher sound level. The range of sound levels to be experienced in fan application is wide spread due to volumetric and pressure requirements which extend over a broad field. Fig. 4 illustrates the general scope of sound levels of centrif ugal ventilating fans over a wide range of volumetric capacities and static Fig. 3. Relation of Sound Level to Operating Speed of a Centrifugal Ventilating Fan Fig. 4. 3 4 5 6 7 8 9 10 20 30 40 5060 80 100 AIR VOLUME-THOUSANDS' OF CLFM. 150 200 . Typical Sound Levels at Point of Minimum Sound Emission for Centrifugal Ventilating Fan pressures. The sound levels are based upon a general average of the sound emission that can be anticipated from the several types of fans adaptable to ventilating and air conditioning duties. The sound levels are typical of the centrifugal fans as a class, and specific types may exhibit sensible de parture from the charted values. Exact application' should be based upon applicable test data derived from the particular equipment under consi deration. . NATURAL ATTENUATION OF DUCT SYSTEM Straight Sheet Metal Ducts. The attenuation of sound in straight sheet metal ducts is a function of the length, shape, and size of the duct.4 Attenuation values are given in Table 4. In general this attenuation is so negligible, except for long runs, that it may be disregarded for all practical purposes. Elbows and Transformations. Due to reflective interference, attenuation will take place at elbows and transformations. The magnitude of the attenuation will depend on the size and abruptness of the elbow or trans formation as shown in Table 5. When the area of a duct increases abruptly, an attenuation of noise level takes place in the duct. In duct design practice the total area of the branch ducts is greater than the supply duct. Similarly with outlets, the area of the outlet, plus the area of the duct after the outlet is greater than the duct area before the outlet. Therefore in an outlet run, attenua tion occurs in the duct as it passes each outlet. Table 6 gives the db reduction for various ratios of total branch duct and outlet area to supply duct area. Grilles to Room. The large abrupt change in area between the grilles and the surfaces within a room results in an appreciable noise attenuation. Table 4. Attenuation in Straight Sheet Metal Duct Runs Duct Small_________-- ---- Medium _____ i-anre.._......... Sub, In, 6x6 24 x24 72x72 Attenuation per Ft, db 0.10 0.05 0.01 :ij I. j \ S i 'i ; 11 i : ii ! ` !i I }ij: j i i \ i ! :) 1 i 950 CHAPTER 41 1956 Guide Table 5. Attenuation of Elbows* Elbow Size In.1* Attenuation pee Elbow, db Large.................................................................. 3 to 15 15 to 36 36 plus 3 2 1.5 1 * The attenuation in vaned elbows should be considered the same as in elbows having the same dimen sions as the radius of curvature of the vanes. If the vanes are lined for the purpose of damping any vibra tions in them, one third may be added to the attenuation values listed. k These attenuation values are based on elbows having a center line radius 1.5 to 2 times the diameter or width of the duet. The attenuation will be greater ii the ratio is less than 1.6 and less when the ratio is greater tbun 2. This attenuation is a function of the total grille area (supply and return) and the total sound absorption of the room in sdbins. (The sound absorp tion of a room in sabins is the summation of the products of each surface of the room measured in square feet multiplied by its corresponding absorption coefficient. The sabin is a unit of sound absorption equivalent to the absorption of one square foot of a totally sound-absorbent surface). The attenuation is given in Equation 5 as: ,, /Attenuation between \ , Total Room Absorption in Sabins grilles and room / = 10 lo& Total Grille Area ,rt (5) Values in Table 7 approximate the attenuation for various rates of air change, and general types of room surfaces. DUCT SOUND ABSORBERS The difference between the required sound attenuation and the natural attenuation must be supplied by the proper sound treatment of the ducts. Selection of the Absorptive Material When a sound wave impinges on the surface of a porous material, a vibrating motion is set up within the small pores of the material by the alternating sound waves. As the ratio of the cross-sectional area of the pores to their interior surface is small, the resistance to the movement of air in the pores is large. This viscous resistance within the pores of the material, converts a portion of the sound energy into heat. The decimal fraction representing the absorbed portion of the incident sound wave is called the absorption coefficient. Considerable absorption may also result, particularly in the low frequency range, from the flexural vibrations of the duct. In the selection and application of the absorptive material, the following points should be considered: Table 6. Attenuation at Duct Bbanches ob Outlets Ratio Branch Duct + Outlet Area _ Sum of Branch. Areas Supply Duct Area OIt Supply Duct Area 1.00 1.20 1.35 1.50 1.75 2.00 Attenuation PER Transformation, db 0.0 0.8 1.3 1.8 2.5 3.0 Sound Control 951 1. For the absorption of the low frequencies below 500 cycles per second the material should be at least 1 to 2 in. thick. Thin materials, particularly when mounted on hard solid surfaces, will absorb the high frequencies and reflect the low. 2. In order to provide as much low frequency noise absorption as possible by means of flexural vibration, it is desirable to fasten the absorptive panels discon tinuously. This result may be attained to some extent by spot cementing, but better results are obtained when it is possible to fasten the absorptive panels to fur ring strips, leaving an air space behind. However, the exact resonance character istics of the panels, and thus their absorption, are so unpredictable that flexural vibration cannot be relied upon for a specific value of attenuation. Requirements for a good sound absorption material are: (1) high absorption at low frequencies f (2) adequate strength to avoid breakage; (3) fire resistance and compliance with national and local code require ments; (4) low moisture absorption; (5) freedom from attack by bacteria Table 7. Appboximate Attenuation Between Grilles and Room - Outlet Velocity PPM 500 750 1000 1250 Am Change Mik. ------ 5 10 15 20 5 10 15 20 6 10 15 20 5 10 15 20 Live Room1* * 0.05 db ii 14 16 17 13 16 18 19 14 17 19 20 15 18 20 21 Medium aRoom* - 0.15 db - 16 19 21 22 18 21 23 24 19 22 24 25 20 23 25 26 Dead Room4 o 0.25 db 18 21 23 24 20 23 25 26 21 24 26 28 22 25 27 28 f Average absorption coefficient for the room'. ' . Live room-average absorption coefficient 0.05. Bare wood or concrete floor--hard plaster walla and ceiling--minimum of furniture. . Medium room-average absorption coefficient 0.15. Carpeted floor, upholstered furniture, hard plaster walls and ceiling or bare room with acoustically treated ceiling. * Dead room-average absorption coefficient 0.25. Heavy carpeted floor. Walls and ceiling acoustically treated. Upholstered furniture. ..' and algae; (6) low surface coefficient of friction; (7) particles should not fray off at the higher design velocities; and (8) freedom from odor when either dry or wet. With every application, the use of sound absorptive material should be considered in the dual function of insulation and sound absorption. It has been shown theoretically* that the reduction (in decibels per. linear foot) of sound transmitted through a duct lined with sound absorbing material, is related in a rather complicated manner to the size and shape of the duct, to the frequency of the sound, and to the sound absorbing char acteristics of the lining. Experimental evidence likewise indicates that there is no simple formula involving the variables which will apply , accu rately to all cases. However, it may be stated generally that the attenua tion in decibels at a given frequency is directly proportional to the length of rtf 1: ! If f 952 CHAPTER 41 1956 Guide 1 lined duct. It decreases as the cross-sectional area increases, and increases as the aspect ratio is increased. ' The noise reduction varies to a considerable extent with the frequency of the sound. In calculating noise reduction, consideration should be given both to the comparative efficiency of the duct lining material at different frequencies, and to the frequency distribution of the noise to be quieted. In the case of fan noise, it is recommended that calculations be based upon the predominant frequency component in the fan sound level spectrum. Normally, most of the sound energy is in the region of this frequency, which generally corresponds to the blade frequency and is equal to rpm X no. of blades -5- 60. Where the noise reduction is calculated upon the basis of the funda mental frequency component, the treatment indicated as required should be ample for the harmonics which are more easily absorbed than the funda mental. In quieting noise due to air turbulence and eddy currents where high frequencies predominate, the frequency 1024 should be used. Since ventilating system noise contains many frequencies, an exception should be noted to the previous statement that attenuation in decibels is directly proportional to length of duct. Most sound absorbent materials are more efficient at high frequencies than at low frequencies. In con sequence, the attenuation in the first five or ten feet of lined duct will be greater because the high frequencies are being absorbed. Thereafter, since low frequencies will be predominant, the overall noise attenuation per foot will gradually be less. Duct Lining By far the most commonly used method of obtaining sound absorption in ventilating systems is to line the duct with absorbing material. It is. usually more convenient to line all four sides of the duct, but a lining on one side over a longer length of the duct will, in general, give the same effect for the same area of applied acoustical material. Subject to certain restrictions, the attenuation of a fully lined duct to single-frequency sounds may be expressed by the approximate Equation 6:7 where R = 12.6L - a1-4 A (6) R = attenuation, decibels. L = length of lined duct, feet. ' P = perimeter of duct, inches. A -- cross-sectional area of duct, square inches. a = absorption coefficient of lining. This formula was empirically developed for a set of duct sizes ranging from 9 x 9 in. to 18 x 18 in., for cross-sectional dimension ratios of 1:1 to 2:1, for frequencies between 256 and 2048 cycles, and for absorption coefficients between 0.20 and 0.80. The duct lining material' used was 1 in. rock wool sheet. In Table 8 are listed the absorption coefficients of a material of this type in one-half and one inch thickness. It is also possible to calculate the absorption by a very complicated mathematical theory.8-9 Such calculations are in substantial agreement with Equation 6. This equation may be in error when applied to other . Sound Control 953 Table 8. Attenuation Data fob Typical 1 in. and \ in. Thick Duct Lining Board 1-InchThickness 1-Inch Thickness cycles per second Absorption Coefficient a o* Attenuation db Absorption Coefficient a a*-4 Attenuation db P 128 0.29 0.17 2.1 A 0.13 0.06 0.8 L A~r 256 0.51 0.39 4.9 hEP , 0.25 0.15 1.9 512 1024 2048 0.70 0.80 0.79 0.60 ' 0.73 0.72 7.6 A? '. . A P 9.2 L~ A p 9.1 L-r 'A 0.40 0.72 0.78 0.28 0.63 0.71 3-5 P 7.9 L~A p 8.9 L=j A types of duct lining and to duct sizes arid shapes greater than those specified. An empirically-derived chart10 representing the average experimental data on a number of different types of materials, is11 shown in Fig. 5. Since individual materials vary, the curves of Fig. 5 are given only as repre.. senting the best available averages for duct sizes of cross-sections from 6 x 6 in. to 48 x 48 in. The dotted lines are plotted from Equation 6 and show that the slope is materially different from the average values. ' Rectangular Cells (Plate or Cell Absorbers) If the length of duct from the main duct to the grille is shorter than the length of lining indicated by Equation 6, the duct may be subdivided into smaller ducts as shown in Fig. 6, or it can also be even more subdivided by an egg-crate construction. In such a construction in which all the sub divided ducts are the sairie size, sound will be equally absorbed down each channel. It is, therefore, only necessary to calculate the sound attenuation of an individual channel. For this, Equation 6 is adequate. When the number of splitter plates or cell partitions is large, the percent age free area of the gross duct size may be materially reduced. This leads to a further sound attenuation. Values of the attenuation, possible, due to this cause, are given in Table 9. Fig. 5. Sound Attenuation fob Various Absorbing Duct Linebs 954 CHAPTER 41 1956 Guide Sound Control 955 Fig. 6. Acoustic Treatment op Ducts A. Unlined metal duct. B. Absorption lined duct (Case 1). C. Splitter plate type absorber (Case 2). (Channels 20 in. x 3.33 in. inside). D. Cell type absorber. (Cells 5 in. x 3.33 in. inside). 2 in. thick absorption material in all cases. Sample Calculations for Duct Treatment Example 1: An air conditioning installation is to be installed in a small theater. Determine the necessary sound treatment for the air distribution system to provide a satisfactory noise level in the theater utilizing these conditions: Fan tip speed 4000 fpm, total pressure 1.25 in.................................. 77 db Acceptable room noise level (Table 2) ................................................ 40 db Required attenuation......................................................................... 37 db Solution: Natural attenuation of supply duct. Sheet metal duct 50 ft long 48 in. x 36 in. (Table 4) 50 x 0.01........ 0.5 db Elbows, two size 48 in. x 36 in. (Table 5) 2x1............................ '. 2.0 db Attenuation grilles to theater air change 10 min (Table 7) outlet velocity 1000 fpm............................................................. .................... . 22.0 db Total natural attenuation..................................................... ..... 24.5 db Difference between required and natural attenuation, 37 minus 24.5, is 12.5 db. This attenuation must be supplied by sound treatment in the duct, either in tbe form of duct wall lining or rectangular cells of the plate or cell absorber arrangement. A similar analysis of the return duct system shows that 15 db attenuation is to be furnished by absorptive material. An inspection of the installation shows that the lining of the plenum on the suction side of the fan would prove the most eco nomical, where it would secure the dual function of heat insulation and sound ab sorption. Example 4: A 10 x 20 in. duct is connected to a private office space in a quiet lo cation. Determine the length of lining necessary to attenuate average fan noise satisfactorily, using a lining material of a type to which Equation 6 applies, and having an absorption coefficient of 0.40 at 256 cycles. Assume that tbe duct is only 12 ft long as shown in Fig. 6, and that a 30 db reduction is required in this length. Solution: Cate /. (No splitters, duct lining only). From Equation 6, 60 R = 1.2.6 X 12 X 2--00 X 0.40" = 13 db. Table 9. End Reflection of Plate ob Cell Absorbers Percentage free area of absorber.............................. 50 40 30 25 Attenuation db............................................................. 1 2 4 5 6 Fig. 7. Absorption Plenums With and Without Sound Cells Case 4. (Two 1 in. splitter plates, 3 channels each 20 in. X V in.). From Equation 6, 46.7 R = 12.6 X 12 X -- X 0.40*4 - 29 db. 00.7 ' Additional attenuation-may be obtained by using additional splitter plates or use of egg-crate arrangement of absorbing material and application of Equation 6. Plenum Absorption In systems where individual ducts are directed to a number of rooms, and sound treatment is required in every duct, a sound absorption plenum on the fan discharge as shown in Fig. 7 will often prove the most economical arrangement. The absorption in the plenum may be approximated by Equation 7. . db (Attenuat.i.on). = 10 ,log,,,P--l-e--n--u--m---A---b--s-o--r-p-t-i-o--n--i--n---S---ab:i--ns Area Fan Discharge (7). The area of the plenum should be at least ten times as great as the fan discharge area. The plenum should be lined with 2 in. of muslin covered rock wool blanket, or 1 in. sound absorbing board preferably nailed to wood strips on the inside of the plenum. With such a lining the plenum is particularly effective in reducing low frequency fan noise. The absorp tion of the plenum in sabins is the sum of the products of each interior area of the plenum measured in square feet multiplied by its corresponding absorption coefficient. Outlet Sound Absorbers Outlet sound absorbers are rectangular or plate cells installed directly behind an outlet or they may be the lining of a pan or plaque outlet. They are particularly effective in the elimination of high frequency whistles which are generated by air flow in the ducts. They are also employed in large systems with long runs where only a few outlets near the fan require treatment. Frequently outlet cells are the only means of correcting existing noisy installations, as the duct sections directly behind the outlets may be the only sections accessible for treatment. (See Fig. 8). AIR SUPPLY OPENING NOISES When air is introduced into a room' through a grille or register at a constant velocity, sound energy is being introduced into the enclosure at 956 CHAPTER 41 1956 Guide Sound fthstfctiw tows Kusfei cowedTort oot or bowd j' mmSECTION A-*" Ptrta absorber* Fio. 8. Outlet Cells fob Pan Outlets ob Gbilles a constant rate.11 Due to partial reflection at the boundaries of the en closure, the intensity of sound at any point in the space builds up to some maximum value. In a large room at a point remote from the source of sound (the supply opening) the intensity can be shown to be substantially proportional to the rate at which sound energy is generated, and inversely proportional to the number of sound absorption units (sabins) in the room. It would thus appear that doubling the sound absorption of the room would halve the intensity and result in a noise level decrease of 3 db. Grille noise is similar in character to fan vortex noise. Knowing the noise level at the face of a grille for a given grille blade setting, the noise will vary as given in Equation 8 where V is the velocity of the air through the grille. db (change) = 50 log!, (t) (8) For a change in blade setting Equation 9 applies, and in this case the total pressure is measured directly behind the face of the grille. For a typical air conditioning grille the noise level at the grille face may be approximately 48 db with a total pressure behind the grille of 0.1 in. (Total Pressure^ [db (change) = 25 logio (Total Pressure)! (9) The resultant room noise level can be approximated by Equation 10. Noise Level at"] _ 10, Room Level = Face of GrilleJ Total Room Absorption in Sabins (10) Total Grille Area Grille Selection In practice the allowable total sound and the required air flow are usually known, and it is desired to determine the maximum allowable velocity. In comparing sound ratings of various grilles several factors must be known if the information is to be properly applied: . 1. The threshold intensity on which the decibel ratings are based. 2. The distance from the grille at which data were taken. 3. If stated as sound level versus velocity for a given grille, the core area (not nominal area) must be known. . 4. The sound absorbing characteristics of the test room. . 5. Whether or not corrected for test room sound level; if not, the room level (with out grille noise) must be known. 6. Methods used for recording data. (Characteristics of sound meter). Since total sound and air flow are both functions of velocity and area, the solution of the problem implies a trial and error method. It has been Sound Control 957 AFig. 9. ib Flow and Sound Level Chart found possible to present these data with sufficient practical accuracy as a family of uniform curves; as illustrated in Fig. 9, which are based on these assumptions: 1. Threshold intensity = 10-1 watts per square centimeter.1 2. Microphone location 5 ft from lower edge of supply opening on a line down ward at 45 deg, and in a plane bisecting thesupply opening perpendicularly. 3. Where data are given as sound level versus velocity, the rating is per square foot of core area. 4. The room is assumed to have 100 sabins absorption. 5. Plotted data are sound levels of supply openings onlyt correction having been made for test room level. 6. Lata taken with a direct reading sound-level meter with frequency weighing network intended to approximate the response of the human ear. If the published ratings are in terms of decibels per square foot, correc tion must be made for area to secure the total sound level of supply open ings of more or less than one square foot area from Equation 11. where Lecibel Addition = 10 login A (n) . A = core, square feet. With Fig. 9 it is possible to find directly the velocity in feet per minute which will give a predetermined total sound at a predetermined rate of flow expressed in cubic feet per minute. The values used are arbitrarily chosen for the purpose of discussion, and do not necessarily represent data referring to any particular design of air supply opening. A correction chart is shown in Fig. 10 for a room having a sound absorption other than 100 sabins. Example S: Determine the core area (see Chapter 31) of an air supply grille which W"1 maintain a noise level of not more than 40 db in a room having 100 sabins of sound absorption, if an air volume of 2400 cfm is required to maintain the proper air conditioning. . Solution: Assuming a grille noise rating of at least 5 db below the noise level of the room, Fig. 9 shows that the limiting grille velocity for a total sound level of 35 oo is about 725 fpm, and the core area becomes fixed at 2400 + 725 or 3.31 sq ft. If the room absorption had been greater, the previously selected velocity of 725 Pui would be safe, since the sound level reduces. If the room absorption had been Sabins, a correction of plus 1.3 should be made by reference to Fig. 10, and the I.: 1 ! i| . (i j I i! ' l! f : j: ! a; t ti I ! > X t permissible velocity becomes that corresponding to a total sound level of 36.3, or approximately 800 fpm. / If the room had been highly reflective with an absorption of less than 100, the correction would be much more important. For instance, for a room of 35 sabins, a correction of minus 3 db should be made, and the maximum velocity corresponding to the 32 db total sound level would be approximately 600 fpm.. " Where more than one supply opening must be considered, the problem is more complicated. If a similar supply opening is added in a far comer of a highly absorbent room, the change in noise level at the 5 ft station at the first supply opening is small; however, if the room is small, or highly reverberant or both, the intensity at the 5 ft station may be almost doubled and the noise level increased nearly 3 db thereby. The simplest method of handling this problem is to treat the room as though all the air were being supplied by one supply opening. Thus, if. two outlets, each supplying 1000 cfm are used, the value 2000 cfm should be used with Fig. 9. Although this method may place an unwarranted.limit on velocity when used in a large room, it is seldom that such a room has a noise level low enough to justify a more complicated, though more exact procedure. . In general, return grilles are selected for velocities about half the supply velocity, and when this is done, they may be neglected in sound computa tions. However, if supply and return grilles are the same size, resulting in the same face velocity, they must be treated as two supply openings. That is, if 1000 cfm are supplied and exhausted through grilles of the same area, 2000 cfm must be used in the solution with Fig. 9. _ CROSS TRANSMISSION BETWEEN ROOMS Ducts serving more than one room permit cross talk between the rooms and should be lined with acoustical material. Where the rooms are close together and the ducts short, the ducts should be sub-divided to provide ample acoustical treatment. Lagging material similar in character to acoustical board, when placed on the outside of ducts, serves to prevent noise, originating outside the ducts, being carried inside the ducts and into the air stream. . A case where outside lagging is desirable occurs when ducts originate at the fan in the equipment room and pass through this room on the way to the room being conditioned or ventilated. Unless the ducts are lined, some of the mechanical noise from air in the equipment room may be trans mitted through the wall of the duct into the air stream, and thereby carried into the room. In such cases, that portion of the duct which is exposed to the sounds in the equipment room should be lagged with material, such as cork, pipe covering or other sound damping material, to prevent the sound from entering the duct at this point. Numerical data are not available to permit a simple and practical calculating procedure to determine thickness of covering which should be used for this purpose. Laboratory measurements have shown that the loss through a sheet of No. 22 gage metal is 24 db. When a sheet of rock wool insulation 1 in. thick and weighing 1.4 lb per square foot is added to this, the insulation value is increased to 29 db. In general, however, adding a layer of insula tion or pipe covering does not materially increase the sound insulation value unless the material is dense, or unless it is surfaced with another sound impervious layer such as metal or board. Standard reference books should be consulted for sound insulating properties of various materials. Inside lining material, used in the case previously mentioned, would serve as an absorber of the sound transmitted through the duct walls, and thus act as a Sound Control 959 Fio. 10. Room Absorption Correction Chart means of preventing the transfer of noise into the air stream. Inside lining may also be used in ducts to absorb noise which reaches the air stream from equipment such as fans, sprays and coils; noise due to eddying currents set up by elbows, dampers' and similar obstructions; arid noise transmitted from room to room where there is a coriunon duct system. CONTROLLING VIBRATION FROM MACHINE MOUNTINGS It is impossible to select equipment which will operate without producing some mechanical noise and, since the equipment must be mounted in a building, it is probable that a part of this noise will be transmitted to the building to such a degree as to make noisy conditions in the rooms which are to be air conditioned. Much of this noise may be transmitted by the duct if it is rigidly con nected to the fan outlet. It is common practice to make the connection between the fan and the duct with a canvas sleeve which effectively restricts noise at this point. Noise may also enter the building through the mount ing of the motor and the fan. Flexible mountings should be provided in all installations, but these mountings must be carefully designed so that they will actually reduce the energy transmitted between the machinery and the supporting floor. If a'flexible material is used, it is desirable to investigate the installation so that it is not short-circuited by through bolts which are improperly insulated, and by electrical conduit which is not properly broken and is attached both to the equipment and to the building. The flexible mounting, if improperly engineered, may actually increase the energy transmitted between the equipment and the supporting floor. In the proper isolation of vibration, which-is usually in the lower range 960 CHAPTER 41 1956 Guide of frequencies and does not include the airborne vibrations known as sound, there is one basic formula which is important in the solution of the problem. It is the formula of transmissibility as governed by the equation: T= (12) where T = transmissibility of the support. / = frequency of the vibratory force. fa = natural frequency of the machine unit on its support (damping = 0). Equation 12 shows that the transmissibility approaches unity for disturbing frequencies considerably lower than the natural frequency of the mounting. As the disturbing frequency is increased, the transmis sibility is also increased until at the reasonant frequency, where / = /,, the transmissibility becomes infinite. This is not true in practice because all materials have some internal damping effect. However, operating at or very close to the reasonant frequency is always serious as forces and stresses may be multiplied 10 to 100 times. As the disturbing frequency becomes greater than the natural frequency, the transmissibility becomes a smaller quantity, and at the value of ///,, = V2 it again has the value of unity. Beyond this point true isolation is first accomplished.^ At a ratio of 3 to 1 for / to fa the isolation is effective enough for practical application, and experience and economical design have shown that a ratio of 5 to 1 is good. For high speeds, higher ratios for / to /,, are easily attained and give better results for effective vibration control, but for the lower speeds as experienced with compressor work the higher- ratios become uneconomical. For a given installation, the speed of the compressor is fixed by the speci fications; therefore the value of / is fixed. That leaves only /,, to be de termined, and that is accomplished by the choice of mounting material and design for the support of the machine. It is well to keep in mind that when trying to isolate vibration, no attempt should be made to isolate the driving and driven piece of equipment separately. The two should be mounted oh a rigid frame, and then the entire assembly isolated according to the rules presented in this chapter. ' The value of /,, can be controlled by the flexibility of the machine support, and when the deflection of the machine support is proportional to the load applied (such as with springs or nearly so with rubber in shear) the value of fa can be determined by Equation 13: 2ry d (13) where . g = gravitational constant. d -- static deflection of supporting material. . fa = natural frequency of the machine unit on its support (damping = 0). By the use of Equation 13 a set of curves may be plotted as shown in Fig. 11. The first line AB, plotted as the critical frequencies for the vari ous static deflections, is a curve showing the worst possible conditions or resonant conditions. . Plotting another curve CD, which is \/2 times curve AB, shows the area MCDN in which the resilient material or mounting does more harm Sound Control 961 11.Fig. Static Deflection for Various Frequencies than good. Plotting curves EF (3 times curve AB) and GH (5 times curve AB) shows area EGHF which represents efficient and economical isolation. Area GPOH is excellent isolation, but for all except the highest speeds, becomes rather uneconomical because of the large deflections required. ' Example 4: An electric motor driven compressor .unit is to be isolated. The com pressor is partially balanced and operates at a speed of 360 rpm. The speed of the motor is 1160 rpm, and it is-belt connected to the compressor. Total weight of the compressor and motor is 4500 lb. Solution: The minimum disturbing frequency to be isolated is 360 cycles per minute. Assume that the desired ratio of forced to natural frequency is 3 as a mini mum, and that 5 is desired. The desired natural frequency of the mounting is 360 + 5 = 72 cycles per minute. From Fig. 11 a deflection of 7 in. is required to attain a natural frequency of 72 cycles per minute. This value may be obtained from critical curve AB for 72 cycles, or from curve GH (5 times critical) for 360 cycles. For the minimum ratio of 3 the deflection would be 2.5 in. The next step is to determine the total weight to be supported by the springs. For low speed partially balanced compressors, it has been found necessary-to add a foundation weighing 2 to 3 times the weight of the motor and compressor, in order to maintain the machine movement below 0.03 in. Compressor and motor..............;.................................................................. 4,500 lb Concrete foundation.............................. .'...................................................... 9,000 lb Total.............................................. ................................................ 13,5001b Practical application dictates the number of springs to be used, which is based on the design of the machine foundation mid the supporting floor structure. However, it is desirable to design for at least 8 springs and one or two spares for cases of un known weights. As many as 50 springs have been used on one installation. The '^ributin of the springs must be balanced against the masses to be supported, otherwise the foundation design and supporting structure determine the location of the springs. The choice of the material used in the design of the resilient mounting is also important. For the slow-speed type compressor, a common speed found in practice is 360 rpm. For speeds below this, isolation should not be attempted except under careful supervision. Referring to Fig. 11, it is 962 CHAPTER 41 1956 Guide found that for 360 rpm the static deflection required for a ratio of ///,, of 3 to 1 (line EF) is 2.5 in., and for a ratio of 5 to 1 (line1 GH) it is 7 in. For these values of deflection the only choice of material is the coil spring. This is also true for speeds up to about 700 rpm. In consideration of the transverse spring constant (so as to maintain good ratios among the various degrees of freedom) experience has shown that the spring should be designed with a working height equal to 1.0 to 1.5 times the outside diameter. A long spring of small outside diameter has very low transverse rigidity, and therefore requires some additional means of preventing side drift of the unit, and on very sensitive applications this may tend to destroy the isola tion efficiency. For speeds of 700 to 1200 rpm the required deflections range from 0.22 in. to 1.75 in. For these conditions rubber in shear serves as a rather satisfactory material if protected from oil. For speeds higher than 1200 rpm cork specially made for vibration damping, can be applied with good results. These limitations are by no means absolute, because certain liberties may be taken without impairing the result if all possible degrees of freedom have been taken into account in the design of the installation. When a machine unit is properly isolated it will have a definite amount of movement which is determined by the ratio of the imbalanced forces to the total mass of the machine. If this resultant machine movement is too great for the necessary connections or the satisfaction of the customer, it can be reduced only in two ways without destroying the quality of the isolation; first, adding mass or dead weight to the machine (such as concrete) common in the application of low speed, partially balanced machinery; second, accurately balancing (both statically and dynamically) all moving parts so as to eliminate the vibration at the source. This latter method is the best engineering practice and is the modem trend. However, even with well balanced machinery, installed in the vicinity of quiet offices, it is usually necessary to isolate properly the equipment to prevent the transmission of vibration likely to cause complaints. Where limitation of machine movement is desired during the starting and stopping periods, the application of friction or hydraulic damping will serve without seriously interfering with the efficiency of the isolation. REFERENCES 1 American Standard for Noise Measurement, Z24.2-1942, American Standard* Association. * American Standard for Sound Level Meters for Measurement of Noise and Other Sounds, Z24.3-1944, American Standards Association. - 1 Sound Insulation of Wall and Floor Constructions ( U. S. Department of Commerce, National Bureau of Standards, Building Materials and Structures Report BMS17 and Supplement). 4 A.S.H.V.E. Research Report No. 1205--Determining Sound Attenuation in Air Conditioning Sys tems, by D. A.^ Wilbur and R. F. Simons (A.S.H.V.E. Transactions, Vol. 48, 1942,-p. 267)- . * For coefficients of commercial sound absorbent materials see Bulletin Acoustical Material* Association, 919 No. Michigan Ave., Chicago, 111. ' - * SoundPropagation inDucts Lined with Absorbing Materials, by L. J. Sivian (Journal Acoustical Society of America, Vol. 9, 1937-38, pp. 135-140). 1 The Absorption of Noise in Ventilating Ducts, by Hale J. Sabine (Journal Acoustical Society of America, Vol. 12, p. 53. 1940L * Sound Absorption in Rectangular Ducts, by L. L. Beranek (Journal Acoustical Society of America, Vol. 12. pp. 228-37, October, 1940). # The Transmission of Sound Inside Pipes, by Philip M. Morse (Journal Acoustical Society of America, Vol. 11, pp. 205-210, October, 1939) '' ^ 10 The Prediction of Noise Levels from Mechanical Equipment, by J. S. Parkinson (Heating and Venti lating, March. 1939, pp. 23-26). Methods of Rating the Noise from Air Conditioning Equipment, by J. S. Parkinson (A.S.H.V.E. Jour nal Section. Heating, Piping and'Air Conditioning, July, 1940, p. 447). ' u The Noise Characteristics of Air Supply Outlets, by-D. J. Stewart and G. F. Drake (A.S.H.V.E. Trans actions, Vol. 43, 1937, p. 81). CHAPTER 42 ELECTRIC HEATING Resistors,'Heating Elements, Electric Heating Units, Applications of Electric Heat, Types of Electric Heating Systems, Equipment and Installation Methods, , Calculating Capacities, Heating Water by Electricity, Induction and Dielectric Heating, Power Problems ELECTRICITY as a source of heat represents thermal energy in a re fined form, easily applied to space heating by a variety of methods, and readily distributed and controlled. However, it usually is more expensive on a direct-heat-equivalent basis than heat from conventional fuels, and for economical service requires careful application in the design of system, adaptation of building structure, choice of control devices, and in method of operation by the user. For special applications and particularly when used to supplement heating systems of other types, the compactness, simplicity, responsiveness, accuracy of control, safety, and other charac teristics of electric heating may carry greater weight in choice of method, than operating expense or initial investment. The basis of all electric heating methods and devices, except so-called heat pumps, is in the power-to-heat conversion constant: 1 kilowatt equals 3413 Btu per hr. Because ratings of electric heating equipment are ex pressed in terms of watts input and volts at the terminals, heating capacity calculations are translated directly to electric power requirements without the necessity of considering ampere currents or ohm resistances. Definitions of Resistor, Healing Element, Electric Heating Unit and other terms applying to heating practices will be found in Chapter 1. . It is strongiy recommended that compliance with the National Electrical Code and approval by Underwriters' Laboratories Inc., or other recog nized certifying agency, be required in the specifications for all equipment, materials, and construction used in electric heating systems. RESISTORS AND HEATING ELEMENTS Electric resistors usually are composed of metal alloys such as nickelchromium wire or ribbon, or non-metallic compounds containing carbon formed into rods or other shapes. Heating elements may have resistors eithef in the form of exposed coils mounted on insulators or of metafile conductors embedded in a refractory insulating material, encased in a protective sheath of metal. Fins or extended surfaces may be used to add heat-dissipating area. Elements are made in many forms, such as wires, strips, rings, tubes, plates and panels. Strip elements are used for clamping to surfaces requiring heat transfer by conduction, in some types of con vection air heaters, and in low-temperature radiant heaters.. Ring and plate elements are common in electric ranges and many small air heaters. Metal or oxide conductive films on glass and ceramics have been applied, usually in the form of panels. Tubular elements may be immersed in liq uids, and when cast into metal or formed into coils, are used in water heaters, electric ranges and air heaters. Cloth fabrics, woven from flexible resistor wires and asbestos or glass 963 964 CHAPTER 42 1956 Guide fiber thread, are employed for many low-temperature purposes such as heating pads, blankets, aviators' clothing, and some radiant panel heating installations. Special incandescent lamps are used as heating elements in certain ap plications where radiant heat alone is desired. These may have tungsten or carbon filaments as resistors, and are designed to produce maximum energy in the infra-red portion of the spectrum. ELECTRIC HEATING UNITS In general, an electric heating unit is considered to be a structure con taining one or more heating elements, electric terminal connections or leads, electrical insulation, and a frame, casing or other supporting means, all assembled together into a unit. There are many varieties, designated by such characteristics as shape and size of housing, material and arrange ment of heating elements, operating temperature of resistors, ratio of radiant to convective heat delivery, directional control for radiation, natural or forced convection air circulation, thermostatic or manual con trol, and electric load-limiting features. So-called electric unit heaters include a built-in fan which circulates room air over heating elements; they are employed for the same uses as other forms of unit heaters (steam, hot water, gas, oil), if conditions are favorable to electric heating, yhey are especially adaptable for supple mental heating, for small occupied rooms in otherwise unheated buildings and for unattended equipment enclosures in which temperature must be maintained above freezing. Location and arrangement of such unit heaters are discussed in Chapter 25. The typical wiring connection for a heater with single-phase power supply, shown in Fig. 1, has a safety thermal trip wired in series with the magnetic contactor, thermostat, and manual switch. Forced-air duct heaters have collar frames designed to fit into rec tangular cross-section ducts, within which are mounted closely nested resistors all wired to the terminal connections. Choice of resistor type and spacing depends on requirements for heat transfer to the air and on ob taining low air-flow resistance. APPLICATIONS OF ELECTRIC HEAT Until recently the predominating applications of electric space heating have been for convenience service, such as: (a) to supplement an existing system, locally, at times when the main system is shut down, (b) for local use, where the main system may be inadequate, (c) for temporary service requirements, (d) for special conditions involving separateor.remote control, (e) for isolated locations, (f) where minimum initial cost is the dominant factor. Some of these requirements are readilj satisfied with portable heating units. However, complete electric heating systems are now finding wide application, mainly in residences, but also in many commercial and and industrial establishments. Small electric duct heaters or compact strip heaters are useful in balancing heat distribution in central fan heating systems operated with steam and hot water, and in improving temperature and humidity control for summer air conditioning. Such heaters can be installed in branch ducts or behind the air inlet grilles in each room. In control of heating systems, employing electric units of the forced-air duct or similar types, a basic difference between electric heating and Electric-Heating 965 steam should be taken into account. Steam is approximately a constanttemperature source of heat, at any given pressure, and a change in air quantity flowing over steam coils does not greatly alter the temperature of the coil surface. The amount of steam condensed (heat input) varies in proportion to the air volume, but the surface temperature of the steam coils remains about the same. Electric heat is quite different, having a constant rate of energy input. If the air flow over electric heating elements is changed, but no change is made in the electric power input, there will be a corresponding change in temperature of the air delivered. This occurs because the electrical energy input remains constant, and the surface temperature of the heating elements will vary as is necessary to compel the air to accept all the heat. . Thus, with electric heat the total heating effect is constant unless some compensating action is performed by controls. Automatic variation of Power supply *' Fig. 1. Wiring Diagram for Unit Heater the electrical heat input synchronized properly with the air flow, can be successfully accomplished by certain special methods of control. By-pass dampers as used with steam units cannot control electric heat. TYPES OF ELECTRIC HEATING SYSTEMS The principles employed in electric house heating for heat transfer and distribution, and for temperature control and cyclic operation, and the variety of equipment that has found application, outnumber those for systems utilizing fuel. This can be ascribed to the inherent adaptability of electric energy for transmission, conversion and regulation, and more importantly to the relatively high unit cost in terms of thermal equivalent as compared with fuels traditionally used for house heating; this necessi tates and justifies greater attention to efficient utilization. Types of electric heating equipment and complete heating systems in current use. are listed in Table i. The sequence shown is for convenient reference only, and does not indicate the relative extent of use, quality of performance, or installation cost and operating expense. Installations of all types listed are in successful operation, but performance and cost depend in large measure on proper application to the local conditions. EQUIPMENT AND INSTALLATION METHODS Convector with Metallic Resistors Standard heating units for wall mounting, of either recessed or surface type, are made with resistors of incandescent bare-wire or low-temperature 966 CHAPTER 42 1956 Guide? > (black) types and the general construction already described. A metal " inner liner or reflector, usually placed between resistors and casing, pro vides a secondary air passage to promote circulation and reduce casing surface temperature at the rear. Depending on ratio of horizontal to Table 1. Pbincipal Types of Electbic House Heating Systems A. Radiators, Convectors, Unit Heaters--Built-In and Portable 1. Metallic resistor, high- or low-temperature 2. Glass unit with metal frame . 3. Baseboard-type resistor 4. Resistor with fan, including unit heater 5. Resistor with focusing radiation reflector 6. Steam radiator with immersion electric element 7. Resistor unit placed in window-type air-conditioner . B. Panel-Type Installations 1. Ceiling panel a. Rigid composite panels containing electrically conductive rubber . b. Flexible composite sheets containing embedded metallic filaments or con ductive rubber c. Electric conductors embedded in plaster on lath 2. Wall panel a. Rigid panels, as for ceilings b. Flexible sheets, as for ceilings 3. Floor panel a. Electric conductors embedded in concrete slab b. Soil heating cable under ceramic tile C. Central Hot-Water Systems 1. Water from electric heater pumped to radiators or convectors in rooms 2. Same, with thermal storage for off-peak operation 3. Fuel-fired boiler converted to electricity D. Central Warm-Air Systems 1. Resistance-element bank in housing or air duct 2. Fuel-fired furnace converted to electricity E. Heat-Pump Systems 1. Warm-air distribution through ducts, like D-l 2. Hot-water distribution, like C-l or 2 3. Radiant panels, like B-l or 2, but with embedded tubing to act as refrigerant condenser 4. Modification of window-type air conditioner by addition of refrigerant revers ing valve and controls vertical dimension, pattern of face grille, and arrangement of resistors and deflector, the convection heat delivery constitutes between 40 and 60 , percent of total output. Ratings usually are from 1000 to 8000 watts (3400 to 27,300 Btu per hr) with some models down to 500 and up to 15,000 watts. Voltages are the standardized values between 110 and 240. Similar models equipped also with air circulation fans of axial type, are available; these give con vection heat delivery up to 80 percent. Other types, using the same components but without a fan, are arranged as floor furnaces to be installed Electric Heating 967 between floor joists. A manual switch and thermostat integral with the unit are optional. Portable units of the foregoing types, except floor furnaces, are ob tainable with plug-in extension cords for convenience and occasional ser vice. Ratings are 500 to 1200 watts at 110 volts; special models rated up to 5000 watts are also made, but can be used only on branch circuits having special wiring and receptacles. " ". ' Convector Type Unit The location of built-in electric heating units of convector type, generally along the exterior walls beneath or alongside windows, is governed by the same principles that determine arrangement of steam and hot-water con vectors, with respect to movement of warm and return air. Positions on interior walls are sometimes permissible, so long as interference from opened doors and from furniture placement is avoided. A thermostat of highsensitivity type and a conveniently located manual, switch are recom mended for each unit or at least each room. Radiant Convector Unit . Glass electric heating units, sometimes designated as radiant panels, depend on the heating effect produced by passage of current through a thin coating of conductive material fused to one face of a panel of J-in. thick special glass. The conductive layer may be sprayed-on aluminum or printed metallic oxide patterned to form a grid several thousandths of an inch thick, or fused-on material to give a uniform coating less than 0.0001 in. thick over the entire active face of panel.' Normal glass operating temperatures are 300 to 400 F, with maximum permissible temperature around 650 F. . Electric wiring connections are made to the panel coating at its oppo site extremities by wires soldered to the coating, by metal strips held in place with springs, or by other methods that assure low electrical resist ance. The panel is supported on insulators within a metal frame which also carries a reflector behind the glass and is arranged to provide space for air circulation. A protective guard prevents accidental contact with the hot glass. . Glass units have standardized ratings, usually 1000 watts, with smaller units extending down to 200 watts, for the common voltages ranging be tween 110 and 240 volts. Starting current for some types exceeds running current by 10 and by 50 percent. Frame sizes vary from about 30 x 24 in. for 1000-watt size to 42 x 6 in. for 300-watt baseboard model; frame types are for either recessed or surface mounting. Thermostats integral with the frame assembly are optional. Portable units equipped with plug in extension cords are of similar construction. Baseboard Type Unit Metal casing proportioned to resemble and replace the conventional wood baseboard along plastered or masonry walls, contains 2 or 3 resistors placed horizontally, one above another. These usually are of low-tem perature type, with ratings 80 to 120 watts (270 to 400 Btu per hr) per linear foot of baseboard unit, at 240 volts. The maximum surface tem perature is 140 to 160 F. The vertical dimension is 6 to 8 in. above floor line, and the projection from face of plaster about 1.5 in. Placement within the room and method of control follow the same principles that apply to hot-water type baseboard installations described in Chapter 23. 968 CHAPTER 42 1956 Guide/*' Another type of baseboard unit has glass panels 6 to 8 in. high and 30 to *: 42 in. long, with surface operating temperature kept 'below 250 F. Resistor with Focusing Reflector . An example of the foeusing-reflector-type heating unit is the copperbowl parabolic or circular glow heater for portable use. This has an incandescent wire-coil resistor on a conical ceramic core, screwed into a lamp- type central receptacle. Usual ratings are 600 and 1000 watts for 110 or 120 volt service. Heat emitted by radiant effect is 75 to 85 per cent of total delivery. . ' For permanent installation, low-temperature focusing units are made with tubular resistors mounted within sectional trough-type reflectors resembling industrial fluorescent lighting fixtures. They may be sus pended from ceiling or bracketed from a wall. Rated capacities are 500 to 1500 watts per linear foot of unit. Installations of this kind are mainly in public and industrial buildings, to handle the perimeter heat loss at windows, doors or wall openings. In a modified form, such units are employed for infra-red heating and drying in industrial processes. Steam Radiator with Immersion Element For portable use, radiators (convectors) of light-weight 2-column con struction are equipped with an immersion element screwed into a bottom opening at one end. Usually, after charging with water and antifreeze compound the radiator is sealed. A safety valve or thermal relief plug is , provided, to protect against excessive pressure in case heat dissipation is' unduly curtailed by clothing, bedding or other insulating material placed over the unit. The steam-and-water intermediate heat-transfer medium has no effect on overall thermal efficiency, but gives the unit operating characteristics adapted for certain applications. Many recent models of window-type air conditioners are provided with resistors, enabling them to be used also for heating service in moderate weather. Electric input for heating is usually kept the same as for cooling. Consequently, the units normally give only convenience heating and are intended for use at times when the main heating system is shut down. Ceiling Panel-Type Installations with Conductive Rubber Panels of laminated construction containing electrically conductive rubber, with rating of 22 watts (75 Btu) per sq ft, for 115 and 230 volt service, are built in standard sizes 3 x 4 ft, 4 x 4 ft, and 4 x 6 ft. They consist of a layer of special rubber about in. thick sealed between layers of phenolic resin-impregnated electrical insulating paper. The assembly is covered on each side with a sheet of aluminum foil. Overall thickness is it in-5 weight is 0.4 lb per sq ft. Metal strips embedded along edges of the rubber sheet serve as potential leads. Electric terminal blocks are provided on each panel and standard raceway mouldings are furnished for wiring connections. An earlier type of construction using asbestos-board backing to form rigid panels in. thick has been discontinued. Under normal operating conditions that cause cycling under thermo static control, the surface temperature is about 100 F. When panels are turned on in a cold room or with continuous operation, the maximum temperature reached is 120 F. The position of panels on the ceiling of a room should be as near as pos sible to exposed walls, especially at windows and doors, to counteract Electric Heating 969 cold-wall effect and to keep the occupants never farther than 3 ft horizon tally from a heated area. The preferred location is with the terminalblock edges close to the walls and with 1-ft spaces between panels. Since it is not permissible -to cut heating panels, the entire pattern for ceiling must be planned in advance both for appearance and for economy. At tachment to ceiling plaster, plaster-board or other smooth surface is made by a special adhesive applied on the ceiling along a 1J in. fastening margin, provided around the four sides of each panel, which carries a dry adhesive tape bonded to the panel. Lighting fixtures must not be fastened or cut into the active area of a panel. Adequate thermal insulation above panels is mandatory to protect all wiring from excessive temperature and to assure economical heating service. The minimum thickness of mineral or fiber insulation (glass or rock wool, cellulose fibers, loose asbestos, etc.) is 4 in. at top story and 2 in. for inter mediate floors, whereas 6 in. and 3 in., should be the minimum correspond ing thicknesses of expanded mica insulation. A thermostat of high sensitivity type with an integral manual cut-off device should be provided in each room. To obtain economy of operation, a time switch or clock is advocated for lowering the room temperature to 55 F at night'or when rooms remain unoccupied. Ceiling Panel-Type Installations with Embedded Conductors Resistors or cables for embedding in plastered ceilings to form panel-type heating installations are electrically insulated with a special compound resistant to high temperature, water absorption, aging effects, and chemical action with plaster, cement and soil. Cable units are furnished in stand ardized lengths between 20 ft and 1000 ft, rated from 50 to 3000 watts per unit, for 120, 220 and 240 volts. They have an outside diameter about | in., the maximum safe operating temperature is about 165 F, and the test voltage is 2500. Non-heating leads 8 ft long are attached to each unit, allowing the unit to be terminated at thermostats or in switch boxes with out causing erratic operation of thermostat by heat from cable. Units are identified in regard to rating, by label and by color code. It is not per missible to alter the length of cable or leads, nor to install any cable unit lacking a visible identification label. For plastered ceilings, the lathing used is of gypsum or other nonmetallic fire resistant type. The cable is temporarily secured to lath with strips of J-in. cotton tape spaced not over 16 in. apart. Each element is tested immediately after fastening on lath, for completeness of circuit and for insulation resistance of at least 100,000 ohms measured to adjacent plaster or structural members. The minimum spacing between cable passes or turns should be 1 in. Leads from cable to junction boxes should be placed in loom. A clearance of at least 2 in. is required from any metal lath, such lath being permissible only for reinforcement along comers at walls. Clearance is likewise neces sary at any metal objects, and this applies also to non-heating leads, as a precaution against magnetic hum. Cables must be kept away from local areas of ceiling that would be additionally heated by recessed or surface- type lighting fixtures. All general wiring for power and light is run above thermal insulation over the heat panel areas, or at least 4 in. above the heated ceiling surface. _ Plaster should be applied in three coats with the first coat trowled in the same direction as the elements. A superfine sand finish is recom mended, since a putty finish coat has a tendency to crack. While new 970 CHAPTER 42 1956 Guide plaster is drying out, the range and rate of temperature changes (either increase or decrease), should be kept low. Vermicuhte or other insulating plaster must not be used, since it causes cables to overheat. Thermostats should be of high sensitivity type with a manual switch and have other, characteristics like those described for conductive rubber panel installations. Electric Wall Panels Although less common than ceiling or floor panel systems, walls may similarly be utilized for electric panel heating. However, possibility of damage to the electrical conductors or to their insulation, from nails driven for hanging pictures and from building alterations, as well as radiation interference caused by furniture placement and interior decorations, re quires consideration. Care must be exercised to assure compliance with any applicable codes or safety regulations. Electric Floor Panels Resistor cables of the same types which are used for ceiling panels are employed also for floor panel systems in concrete slabs. The thickness of the concrete slab is usually made a minimum of 3 in. when placed directly on soil. Precautions to be observed in construction of floor slabs for panel heating are covered in Chapters 12 and 24. Cement finish If in. thick is poured and trowled above the cables. They are stapled at the specified spacing to wood nailing strips laid on the rough concrete slab. It is desirable that cables be secured in place either with a f to |-in. layer of eement wash or thinned grout before the final lf-in. cement or terrazzo finish is applied, or by tacking at 2 ft intervals with daubs of cement, plaster-of-Paris, strips of masking tape or other non-conductive material. When the slab is made of light-weight insulating concrete, cables should be secured by tape or cord stapled directly to the slab as in the case of plastered ceilings. With monolithic finish, nailing strips are omitted and the cable is strung on frames with nail spacers; frames are removed when enough concrete has been poured to hold the cable in place. If desired, magnesite flooring, asphalt tile or wall-to-wall carpeting may be used on the floor. Spacing between adjacent turns or loops of cable, and clearance from reinforcing steel bars or other metal bodies embedded in concrete, for prevention of magnetic hum, are the same as- for plaster ceilings. Non heating leads should have rigid conduit between the wall outlet box and floor. They terminate beneath the surface of the final coating. Porce lain or phenolic bushings to separate the leads should be placed with the leads pass from raceway into the slab. Cable circuits should be tested for continuity during the time they are being laid and again while the top concrete layer or cement finish is being poured. Under ceramic tile floors, the cables are embedded in grout before tiling is laid. In the case of bathrooms, laundry rooms, basements subject to flooding, or other locations where wet floor conditions are likely, soil heating cable of lead-sheathed or other special water- and corrosion-re sistant types may be required under local regulations. Central Hot-Water Systems Heating systems of hot-water type using conventional radiator or con vector units, discussed in Chapter 22, may be operated electrically by means of heat exchangers containing immersion elements (resistors) of Electric Heating 971 the required capacity. Control of the resistor circuit by a thermostat within the exchanger is usually desirable. The water holding capacity of exchanger should be made sufficient to minimize frequency of cycling of the heavy electric load from the resistor, and for safety. Resistors may be interlocked with the circuit of the water circulating pump, so that they can be energized only when circulating pump is in operation under control of the room thermostat. . For off-peak operation, where rate schedules for electric power mafo this desirable, a water heating tank of large storage capacity is employed. The system may be designed for a maximum water temperature of 250 to 275 F at pressures of 60 to 75 psig. An automatic valve is required to provide 140 to 160 F temperature at the pump, by mixing hot water from the tank outlet with cool water from the return main. Another method for heat delivery employs the flash principle, withdrawing water at high storage temperature into a low-pressure separating chamber where steam is obtained as a result of the pressure reduction; however, power for pump ing is substantially greater with this steam-accumulator method. . In practice, tanks up to 1200 gal with immersion elements of 25 to 30 kw have been used for-installations with design heat requirements up to 90,000 Btu per hr. . Thermal insulation on the tank piping must have low heat transmission in order to cut down the daily and seasonal standby losses. Design of such off-peak systems requires careful analysis of all factors, both thermal and economic. High investment, space required for equip ment, and other practical considerations tend to limit the application of this type of electric heating. . Central Warm-Air Systems ., These systems usually employ heaters consisting of resistors mounted in a frame or housing, as mentioned under Electric Heating Units earlier in this chapter. In many cases, arrangement of the supply and return duct system can be planned advantageously to facilitate future addition of equipment for summer air conditioning. Conversion of Existing Heating Systems Changeover of existing conventional fuel-type house heating systems to electric operation, by substituting resistors in place of the fuel equipment in the combustion chamber of a warm-air furnace or boiler, is seldom de sirable. Excessive thermal losses from such central equipment and lack of adequate refinements in the distribution facilities and controls, will usually cause high operating Cost. However, where heat delivery into the system is accomplished by a steam or hot-water coil assembly located within a duct system, replacement or supplementing with a bank of resistors like those employed in electric unit heaters is sometimes advantageous. A case of this kind occurs where standby heating is needed to maintain safe or comfortable temperature in isolated rooms, during emergency conditions or when the normal electric service for lighting and motors is not in use. Heat Pump Systems Where summer air conditioning is wanted in addition to heating, the heat-pump type of all-year system, which utilizes a refrigeration com pressor unit in conjunction with a central-plant installation, is finding a number of applications. It reduces electric input demand and consumption ,?r heating to about one-half or one-third that with the resistance method, e reduction depending mainly on temperature level of the heat source '15 972 CHAPTER 42 1956 Guide used and on the type of heat distribution system and its controls. In general, the conditions most favorable to heat pumps occur where, due to climate or operating requirements, the compressor capacities needed both for heating and for cooling service are the same, or nearly so. Customary methods of conveying the heat output from heat pumps to the space served are indicated in Table 1. The main types of heat pumps and the characteristics of heat sources utilized are discussed in Chapter 37. Some recent models of window-type air conditioners are being equipped for operation as heat pumps. They have refrigerant reversing valves and controls, provided either at the factory or optionally by the installing contractor. Such units are intended for between-season or convenience heating only, since they do not give good performance when the outdoor temperature falls below 35 to 40 F, and they lack means for defrosting the evaporator coil. In the case of heat pumps using air as heat source, it is shown theoretically and found in practice that heat delivery capacity falls off rapidly as out door temperature decreases, whereas the heat requirement increases di rectly with indoor-outdoor temperature difference. Deficiency at tem peratures below the balance point can be made up by supplementary electric resistance elements, but this adds disproportionately to power demand. Moreover, seasonal energy consumption by such resistance heating, per kilowatt of demand established, is much less than for the heat-pump cycle itself, and the combination gives load characteristics unfavorable to the utility company for rendering low-cost electric service. An alter native provision for cold-weather peaks is thermal storage in chemical salts and by other devices; such processes are still in the development stage. The installed cost of residential heat-pump systems is two to three times that of resistance types. However, in practically all cases the summer air-conditioning service obtained with conventional heat pumps is as valuable to the user as the winter heating. Resistance heating systems, except the minority using mechanical air circulation through ducts, do not lend themselves to consolidation with summer air conditioning features, and consequently, an independent cooling installation is necessary. Heat pumps thus have an advantage over such dual systems. CALCULATING CAPACITIES The procedure outlined in Chapter 12 for calculating the heating load should be used for electric systems. Load expressed in Btu per hour is converted to kilowatts by the divisor 3413 Btu per kilowatt. All the energy applied to a resistor transforms itself into heat, unaffected by tem peratures of the surrounding air and of surfaces receiving radiated heat. However, both electric power input and heat output are directly affected by voltage at the resistor terminals, being proportional to square of the voltage. Thus, a resistor rated 1000 watts at 240 volts, if used on a circuit at 220 volts, delivers 840 watts or 16 percent under the rated value, while at 208 volts the shortage is 25 percent. Selection of proper indoor and outdoor temperatures for design of electric heating systems is more critical than for those using fuel, since in case the installed heating capacity is found deficient, the only recourse is to add more electric heating units or to bring the supply voltage up to the permis sible maximum. On the other hand, fuel-operated systems ordinarily Electric Heating 973 permit raising the rate of combustion somewhat above the nominal rating, although there may be some penalty on efficiency, operating or maintenance expense, or overall performance. Indoor temperatures usually specified are shown in Table 2 of Chapter 12, subject to the indicated notation concerning effect of radiant or panel heating. Moreover, allowance is required for radiation effect of cold surfaces if there are large windows, and for the continuing trend toward adoption of higher indoor temperatures. Concerning outdoor temperature for design, attention is directed in the case of electric heating systems to the cautionary remarks relating to winter climatic conditions in Table 1 of Chapter 12. Judgment must be exercised in choice between values In Common Use and TAC 97.5 Percent Basis, which show differences as large , as 15 deg for some cities. If indoor temperature is taken at 70 F, it may be inadvisable to select outdoor temperature as high as the TAC 97.5 percent value. The arbitrary addition of a percentage safety margin on the calculated heating load or on the specified rated capacity of heating units to be in stalled, is not recommended, especially in case the outdoor temperature for design is taken at or near the In Common Use value instead of TAC 97.5 Percent Basis. Such practice increases the peak electric demand and usually the cost of electric service. It also tends to produce excessive onand-off cycling, impaired temperature regulation, and needless voltage variation or flicker disturbances with bad effect on lighting and other electric devices. Many electric heating systems are of decentralized type, with a thermo stat provided on each convector or for each room as recommended by manu facturers of such heating equipment. This practice compensates for varia bility of heat contributed by auxiliary sources such as sunshine, lighting and appliances. It also gives opportunity for diversity of power demand, i.e., the non-coincidence of electric load from all the convectors, panels or heating units of an installation. Manual switches are also commonly provided in such decentralized installations to permit cutting off heat or reducing temperature in rooms when not occupied. Such decentralized operation, advocated as an economic measure with electric heating, re quires that consideration be given to adequate capacity for warm-up, as against the uniform-temperature operation with a fully centralized system. It is essential that buildings intended to be heated electrically should be well constructed, with adequate thermal insulation having impervious vapor barriers, and with storm windows or double-glazed window units and weather stripping to minimize heat loss and air infiltration. Open fire places should be eliminated wherever possible, because they induce ex cessive infiltration. The relatively high electric cost for thermal energy, about $6.00 per million Btu at $0.02 per kwh, for example, as compared with about $1.20 for oil at $0.12 per gal when utilized with 70 percent efficiency, gives economic justification for substantial expenditure to reduce heat consumption. The large majority of dwellings heated economically by electricity have heat factors (quotient of seasonal energy consumption in kilowatt hours, divided by degree-days and by volume of gross heated space expressed in thousands of cubic feet) between 0.2 and 0.3. The features necessary to hold consumption within these limits result in con- struetion that for 5000 degree-day climate with 0 F outside design tem perature, gives a calculated heating load of 4000 to 5000 Btu per hr per 1000 cu ft gross volume. Heat factors up to 0.4 are not uncommon, but . 974 CHAPTER 42 1956 Guide experience shows that such high heat requirement may result in excessive operating cost. HEATING WATER BY ELECTRICITY Electric water heaters for hot-water service in residences and commercial buildings are predominantly of the automatic storage type. These- generally have a cylindrical tank mounted vertically, with a primary electric heating element or resistor near the bottom and a secondary unit located within the upper one-quarter of the tank. Water heaters of single-heating- Jp a s unit type have an element only at the bottom. The first cost of automatic electric heaters is somewhat higher than that of fuel-fired types, owing to '(' the need for.larger tank storage to compensate for the limitation of recovery ,r rate, since for economical electric service the connected load should be kept , low. Large tank capacity is necessary also with off-peak operation, where there are low electric rates for this class of service. .- Instantaneous heaters are used in special cases only, because of the high electric power input required, for example, 15 kw to deliver 1 gpm with 100 - deg temperature rise. .' Capacities of household automatic storage-type water heaters, as par tially standardized within the electrical industry, range from 30 to 140 gal nominal tank capacity with input 1600 to 7000 watts. Wattage input ratings of two-unit heaters are based on approximately 30 watts per .gallon of tank capacity for secondary unit and 20 watts for primary unit. Single unit heaters have tank sizes up to 80 gal with an input of 4000 watts, the ratings being based on 50 watts per gallon. The schedule of heater capaci ties shown in ASA Standard C72.1-1949 is reproduced in Table 2. The wattages listed in Table 2 are minimum recommended values for con tinuous service. Some departure from the standardized watts-per-gallon ratios is to be expected, as experience indicates that increased hot-water use with automatic laundry machines and dishwashers may call for larger heating units than have heretofore been found desirable. With off-peak operation the watts-per-gallon ratio likewise must be raised. Rated voltage for water heaters is 240 volts, with a range 220 volts minimum to 248 volts maximum, but specified test performance is required to be met only at the 236 volts taken as normal design voltage. Thermo stats controlling the heating units are normally set for 150 F, with upper limit of adjustment range of 170 to 180 F. Heating units are of three general types, all of which give approximately the same service efficiency if selected to suit the operating conditions, as follows: 1. Immersion element, inserted horizontally through a threaded or flanged opening in side of tank. 2. Strap-on unit, externally mounted directly against the tank shell and held in close contact by a band or strap encircling the tank. 3. Side-arm or outside circulation unit, consisting of a vertical cylindrical housing or heat exchanger which contains an immersion heating element, connected by pipes into top and bottom of the storage tank. For the third type, which is less commonly used, thermostats separate from the heating unite are mounted within the storage tank. A fourth type of heater, applied only in exceptional cases and for large installations with alternating current, employs the water itself as a re- Electric Heating 975 sistor in which electrodes are immersed. Close temperature regulation and compensation for the effect of variable amount and composition of solids and gases in the water are difficult to obtain with small unattended heaters of this kind. The electrode type of construction has in the past been used also for generating steam in so-called electric boilers, mainly for industrial plants; however, in only few instances today is electric energy obtainable at cost low enough to make it competitive with fuel-fired boilers for steam pro duction. . Tanks of electric heaters are regularly constructed to withstand a 300 psig hydrostatic test pressure and are rated for a safe working pressure of 127.5 psig. Materials in contact with the water are selected to resist corrosion caused by solid and gaseous impurities occurring in some locations. It may be desirable also to provide sacrificial metal anodes of magnesium, zinc or alloys, to protect the tank and its piping connections. A safety relief valve of pressure-actuated type must be included; it may optionally be actuated also by internal temperature. A heat trap at the hot-water Table 2. Standard Rated Capacities op Electbic Water Heaters Tank Size Gallons Nominal 30 40 52 66 80 110 120 140 Range 30 to 35 35 to 45 45 to 55 55 to 70 70 to 90 90 to 115 115 to 135 135 to 175 Rated Input, Watts _ Two-Unit Heater Primary Secondary 600 750 1000 1250 1500 1000 1250 1500 2000 2500 2000 2500 3000 3000 4000 4000 Single-Unit Heater 1500 2000 2500 3000 . 4000 outlet, if not provided by manufacturer within or outside the tank shell and inside the insulated jacket, may be placed in the external piping. The trap consists of vertical pipe at least 6 in. long having downward flow, to retard circulation of hot water within the distribution piping system under standby conditions. Occasionally, an uninsulated tempering tank is installed ahead of an electric water heater, enabling the cold inlet water to absorb heat from the basement or room air--if conditions are such that objectionable sweat ing does not occur. The practice' of connecting a tempering tank with a fire-box coil, the electric heater then furnishing heat only when there is deficiency from the boiler or furnace, is not recommended. Delivery performance efficiency of heaters meeting the electrical-industry standard 24-hour operation test is 90 percent minimum, which allows 10 percent for thermal loss through the jacket insulation. In service, the quantity of water withdrawn from an automatic storage heater has con siderable influence on overall efficiency. With increasing quantities, seryice efficiency rises and approaches the upper limit fixed solely by the jacket thermal loss; on the other hand, if little or no water is drawn, ef ficiency approaches zero since no useful work is done. Hence oversizing 976 CHAPTER 42 1956 Guide a water heater by having too large a tank impairs the service efficiency. Excessive heating-unit wattage causes undesirably high electric demand. Undersizing of heaters obviously results in inadequate and unsatisfactory hot-water service. Selection of electric heater capacity for residences is made by reference to rating tables which take into account the number of occupants, number of bathrooms or plumbing fixtures, and presence of appliances such as laundry equipment, dishwashers, and the like. Information of this kind is in Chapter 49 and in design manuals issued by the electric utility industry and by heater manufacturers. For commercial applications, the hourly hot-water requirements must be analyzed and the best combination of t..nk capacity and heating element rating determined, with due considera tion of electric power demand created in relation to the user's other electric demands. A common type of electric service for water heating is the so-called Fig. 2. Domestic Hot-Water Heater fob Off-Peak Service off-peak service under which the charge for energy consumed during desig nated hours is lower than for normal or unrestricted service. With this system, the operation of heaters is confined to such hourly intervals during the 24 hours as will (a) avoid creating peak electrical demands by the customer in excess of the demand resulting from the customer's other uses of electricity, or (b) keep the water heating load off the electric utility system during peak hours.v In general, Case (a) occurs where rate schedules contain a demand charge component, and Case (b) where a special low rate applies to off-peak consumption. Water heater circuits are controlled with relays actuated by an electric-clock mechanism or by a carrier-current impulse impressed at suitable intervals on the electric distribution system, or by an automatic load-limiting type of control. One arrangement of domestic hot-water heater for off-peak service, shown in Fig. 2, has the lower heating unit under control of an off-peak switch. Upper unit is connected directly to the line, so that in case the reserve of hot water becomes depleted, the top thermostat brings its heating unit into operation only until the upper portion (usually about 25 percent) of tank contents reaches the thermostat temperature. Water heaters employing the heat-pump principle are now in limited trial use, obtaining annual performance factor (sometimes called coefficient Electric Heating 977 of performance) approaching 2.5. This value represents the ratio of useful heat delivered, to the direct heat equivalent of total electric input. The predominant models have tank capacity of approximately 55 gal, hermetic type compressors rated 4 or i hp, and small circulating fans. So-called vagrant heat occurring within the basement or utility room is generally the heat source. In some cases there is secondary benefit from dehumidifying, and an appreciable cooling effect is produced. Present limitations include high initial cost, low recovery rate, restricted maximum temperature, and necessity of condensate drain connections, compared with conventional electric resistance-type and fuel-fired water heaters. INDUCTION AND DIELECTRIC HEATING These methods, employed for industrial processes requiring extreme speed or close control of heat location, do not lend themselves to space or water heating. However, since they are sometimes proposed for con sideration, the operating principles are described briefly. Any electrically conducting material placed in an alternating magnetic field develops eddy currents that generate heat. The rate of internal heating is so high that conduction away from the zone to be treated does not unduly lower the temperature. The field is created by coils connected to an alternating-current power source such as motor-generator set, a mercury arc, or an electronic-tube or spark-discharge oscillator, producing frequencies usually between 250 and 10,000 cycles per second, but for some applications up to 500,000 cps. The coils are generally copper tubes through which cooling water is circulated. Induction heating apparatus must be specifically designed for each application such as melting metals, brazing, heat treating internally or in zones, and surface hardening without oxide scale formation or distortion. Dielectric heating, for materials that are non-conductors of electricity and are poor thermal conductors, requires a high-frequency electrostatic field produced at high voltage and very high frequencies reaching 50 mil lion cps. The method is well adapted to continuous-flow production process including manufacture of bonded plywood, drying of deep-pile fabrics, dehydration of granular or crystalline materials, and sterilization of foods. POWER PROBLEMS Rates for Electric Service The cost of electricity varies due to several factors. The main elements are the annual charges, including taxes, on capital invested and those ex penses necessary to keep the electric utility system at all times-in a state of readiness to serve the load. The cost of generating the energy is secondary. Electricity is not stored, but must be produced instantaneously when and as required by the user. Consequently, the time of power use, both daily and seasonally, and relation between rate-of-use or demand and the energy consumed within a period (load factor) have large effects on costs and the rates charged. Special low "rates sometimes are available during certain prescribed off-peak hours of use, when the system load is low. ' Space heating is a load whose magnitude is determined basically by weather, and is affected to a much lesser extent by the electric customer's use of his premises. Most of the heating loads in a region occur simul taneously, thereby tending to create peaks for which the capacity of the electric system must be adequate. Accordingly, rates contain in one way 978 CHAPTER 42 1956 Guide or another, charges both for demand and energy. Demand may be in dicated directly by a demand meter or be derived from manufacturers' rating data shown on nameplates of the heating equipment. In block-type rates, where demand is not specifically mentioned, it is in part reflected by higher charges per kilowatt-hour in the earlier blocks. Control of Electric Demand To obtain electricity for space heating at minimum cost, it is necessary to keep the user's kilowatt demand as low as possible, by provisions in original design of the installation and by judicious methods of operation. Excess heating capacity should be avoided, but without jeopardizing satis factory performance in cold weather. A variety of control methods can be applied to minimize both demand and consumption. Decentralized con trol with a thermostat in each room or on each heating unit, together with manual switch to cut off any unoccupied room, is one method. Sequence switching whereby electric service to individual rooms or circuits is shifted in rotation by an automatic timing device and sequence is modified by out door thermostat or by total electric load, is another. Load-limiting controls of several types have come into use. These are generally arranged to measure the customer's total power demand, which for a residence may be grouped as lighting and miscellaneous ap pliances, refrigerator and water heater, cooking range, and the space heating system. When the demand exceeds a preset value, one or more heating circuits are cut off progressively in rooms least affected by the inter ruption. Experience shows that with electric floor or ceiling panel heating, temperature drop occurs slowly, at the rate of about 1 deg per hour for concrete slabs and 2 deg for plaster construction or rigid panels properly backed with thermal insulation. Moreover, electricity consumed by light ing, appliances and cooking ranges is contributing some useful heat at such times. Another form of limiting control for 120/240-volt 3-wire circuits pro vides complete or sequence transfer of space heating units from 240 volts to 120 volts, thereby reducing the electric input to one quarter whenever the total load or general-service component exceeds a preset limit. This method lends itself to use of an outdoor thermostat actuating a relay, whereby in mild weather the entire heating system operates at 120 volts and with lengthened cycles obtains more uniform room temperature. For reducing temperature at night, if desired, a clock-operated master thermo stat can be provided to lower the heating-system voltage. On some electric utility systems, centralized control by means of a pilot-wire or carrier-current actuating a relay is. applied to house-heating installations. With any type of control, time-delay relays should be used in order that upon restoration after an emergency service interruption or whenever a master thermostat calls for heat, the individual circuit or units will come on non-simultaneously over a period of a few minutes. This is advisable especially for types of resistor units that have a power input, when cold, as much as 50 percent above the rated value at normal operating temperature. Operating Costs The range of electric costs for house heating, on residential rate schedules typical of country-wide conditions, is from something over tvvo cents per kilowatt-hour where house-heating consumption comes mainly on the Electric Heating 979 bottom step of a block-type residential rate, to as little as half that figure in areas served by large hydroelectric systems. Since the range of heat factors for houses of differing construction types with various methods-of resistance electric heating and with a variety of occupancy is likewise more than 2-to-l, costs of house heating for dwellings of the same size in similar winter climates may vary through a range of nearly 5-to-l. However, an Table 3. Relation op Resistor Voltage to Heat Delivery Condition VOINO Electric system, nominal value................................................... For design of equipment, at terminals................................ Range, as basis for design Minimum. . .................................................. ........................................... Maximum............................ On secondary distribution system Favorable zone, as to voltage conditions Minimum............................................................................. Maximum........................ Tolerable zone Minimum......................................................................... : Maximum........................................ ;............................ . Emergency conditions..................................................... . 120/240 118/236 110/220 124/248 110/220 125/250 107/214 127/254 90/180 Heat Dehttebed % 103.3 100 . 86.8 110.5 86.8 112.0 82.2 116.8 58.3 8000-cu ft house can be heated with 8000 kilowatt-hours of electrical energy annually in 5000 degree-day climate, if a heat factor of 0.2 is attained by means of good construction and adequate insulation. Voltage Requirements The preferred nominal system voltage at point of electric utilization by equipment, for single-phase 3-wire systems necessary with space heating, is 120/240 volts, as stipulated by standards of the electrical industry (EEI publication R-6 and NEM~A publication No. 117 issued May 1949). For household heating appliances mentioned in the standards, such as air heaters, water heaters, and cooking ranges, the equipment voltage rating for design is specified as 118/236 volts, and the range of voltages to be used as a basis of design extends from 110/220 minimum to 124/248 maximum However, naturally variations exist from time to time in the conditions at different points in any secondary distribution system and will affect both voltage level and range of fluctuations. Under emergency conditions on electricity supply systems, voltages of the order of 90/180 may be encountered. Heat delivery by resistors with these voltage values, ex pressed in percent of rated delivery with the normal 118/236 volts (at terminals) is given in Table 3. Voltages stipulated for secondary distribution systems are a point of service entrance to the building; the drop of voltage in the house supply wiring to terminals of the heating equipment may be 2 to 3 percent, thus re ducing heat delivery by some 5 to 8 percentage points below the favorable zone and tolerable zone values included in the last column of Table 3. Ac- 980 CHAPTER 42 1956 Guide cordingly, it is necessary the designers of electric heating installations obtain specific information from the local electric utility company on both existing and anticipated future conditions at the location, before specifying the capacity and voltage for equipment, wiring and controls. BIBLIOGRAPHY Electric House Heating--Load Characteristics and Economics, by W. F. Friend {Proceedings of Midtvest Power Conference, April 1951). Electric House Heating, by E. E. Parks {Electrical Engineering, August 1951). Electric House Heating, issued by Rural Electrification Administration {REA Bulletin 142-1, November 1952). . Complete Electric House Heating, by F. A. Compton {Edison Electric Institute Bulletin, May 1950). Experience with Electric Space Heating, by R. H. Giedd {AIEE Conference Paper, January 1953). House Heating Experience, by C. E. Simpson {Electrical World, October 9, 1948). Heating by Electricity in Tennessee Valley Area, by B. H. Martin and T. W. Newberry {Heating and Ventilating, May 1948). Longview House Heating Data, by H. G. Kelsey {Electrical West, September 1945). Electric Storage Heating Serves New Oregon School, by W. Bruce Morrison, {Heating, Piping and Air Conditioning, June 1949). _. Electric Space Heating and Resulting System Load Factors, by T. H. Allen and C. D. Anderson, Jr. {AIEE Conference Paper, January 1953.) Electric House Heating Load Characteristics, by R. E. Sinclair {Electrical West, September 1950). House Heating Load Characteristics as They Affect Wiring Costs, by J. B. Cochran {Electrical World. April 12, 1947). - Heat Factor Formula to Calculate Electric House Heating, by H. C. Bender {Electrical World. May 12, 1945). Modulating and Load-Limiting Controls for Electric House Heating, by W. F. Friend [Proceedings of American Power Conference, March 1953, also Heating and Ventilating August 1953, p. 82). Progress Report on the Heat Pump, by W. F. Friend (Refrigerating Engineering, January 1951). ' Methods Developed for Built-In Radiant Heat {Electrical West, December 1948). Performance of Electrical System of Panel Heating with Four Stages of Insulation, by R. J. Lorensi and J. F. Schreiber {Heating, Piping and Air Conditioning, January 1949). Radiant Heating by Electricity, by L. N. Roberson (Heating and Ventilating, September 1946, p. 89). Low-Voltage High-Current Radiant Heat, by R. S. Tice {Electrical West, December 1947). Applications of Radiant Energy {Lighting Handbook, Illuminating Engineering Society, 1952, Section 18). Radiant Glass Heating Panels (Technical News Bulletin, National Bureau of Standards, May 1953). Radiant Glass Heating Panels by P. R. Achenbach (Heating and Ventilating, January 1953, p. 83). American Standard--Household Automatic Electric Storage-Type Water Heaters, ASA C72.1-1949 {Na tional Electrical Manufacturers Association Publication No. WH1-1949). . Federal Specification for Domestic Electric Storage Water Heaters, W-H-196, amended May 1949. Application of Electric Water Heaters to Domestic Service, by C. G. Hillim- (Heeding, Piping and Air Conditioning, November 1946). Industrial Electric Resistance Heating, by Lee P. Hynes (American Institute of Electrical Engineers, Paper No. 48-247). Induction and Dielectric Heating, by Kennard Pinder (Electrical Engineering, February 1947). _ EEI-NEMA Preferred Voltage Ratings for A-C Systems and Equipment (Edison Electric Institute Publica tion No. R-6, May 1949, also National Electrical Manufacturers Association Publication No. 11, May 1949). Standard Handbook for Electrical Engineers (McGraw-Hill Book Co., 1952). CHAPTER 43 CORROSION AND WATER FORMED DEPOSITS, CAUSES AND PREVENTION Definitions, Classification and Characteristics of Water, Causes and Prevention of Scales and Sludges, Causes and Prevention of Slimes, Underwater Corrosion, Atmospheric Corrosion, Buried Pipe Lines, Handling Water Treating Chemicals, Legal Regulations THE surfaces of heating and ventilating equipment that are in in timate contact with water sometimes are affected by the chemical characteristics of contacting waters to such an extent that prohibitive amounts of insoluble materials are formed or corrosion ensues at an in sufferable rate....To avoid or to correct such troubles, it is desirable that heating and ventilating engineers have a general appreciation of industrial water chemistry. The principal purpose of this chapter is to provide those criteria by which the average engineer may judge whether a problem is one that will yield to rather simple remedies, or will require the skill of an experienced water technologist. DEFINITIONS The following definitions for water-formed deposits, corrosion, and closely allied terms have.been proposed: Water-Formed Deposits. A water-formed deposit1 is any accumulation of in soluble material derived from water or formed by the reaction of water upon sur faces in contact with water. Deposits formed from or by water in all of its phases may be further classified as scale, sludge, corrosion products, or biological deposits. Scale. Scale1 is a deposit formed from solution directly in place upon a confining surface. It is a deposit which will retain its physical shape when mechanical means are used to remove it from the surface on which it is deposited. Scale, which may or may not adhere to the underlying surface, is usually crystalline and dense, fre quently laminated, and occasionally columnar in structure. Sludge. Sludge1 is a - water-formed sedimentary deposit. It usually does not cohere sufficiently to retain its physical shape when mechanical means are used to remove it from the surface upon winch it deposits. Sludge is not always found at the place where it is formed. It may be hard and adherent, and baked to the surface on which it has been deposited. Biological Deposits. Biological deposits1 are water-formed deposits of biological organisms or the products of their life processes. Biological deposits may be mi croscopic in nature, such as slimes, or macroscopic, such as barnacles or mussels. Slimes are usually composed of deposits of a gelatinous or filamentous nature. Corrosion. Corrosion* is destruction of a metal by chemical or electrochemical reaction with its environment. In the corrosion process, the reaction products formed may be soluble or insoluble in the contacting environment. Insoluble cor rosion products may deposit at or near the attacked area, or be carried along and deposited at a considerable distance from the attacked area. Corrosivity. Corrosivity* is the capacity of an environment to bring about de struction of a metal by the process of corrosion. Corrosivity is a property of the environment, but it has no significance until the metal in question is specified. 981 982 CHAPTER 43 1956 Guide CLASSIFICATION AND CHARACTERISTICS OF WATER For industrial use there is no accepted conventional classification of water. Rather, each industry usually develops a body of ideas applicable to its own water, problems.4 For heating and ventilating engineers, it is perhaps most convenient to distinguish between mineralized waters and condensates. . Mineralized Waters All the waters found in streams, wells, lakes, and the ocean are min eralized. The same is true of all municipal supplies even though they may have been treated. For a given area, ground waters are likely to be more highly mineralized than are surface waters. Conversely, surface waters Table 1. Mineral Analyses Typifying Composition of Waters Available and Used Industrially in the USA Substance Unit Location ob Abba*'1* 0) (2) (3) (4) (5) . (6) (7) (8) (9) SiOt Fe Ca Mg Na K HCOi so Cl NO* CaCO* Non-Carbonate Hardness. .............. - CaSOt 2 0 6 1 2 1 14 10 2 1 31 12 5 6 12 00 5 36 28 67 11 13. 119 2 22 10 13 0 66 165 11 98 7 18 37 10 10 62 92 18 34 44 8 1 202 339 135 84 13 10 2 13 426 434 165 287 40 58 .9 0. 96 27 183 18 22 0 3 2 215 10 334 549 121 11 280 22 01 983 564 274 8 54 0 14 2 155 400 46 1.300 78 11,000 3 400 210 . 150 389 2,700 117 19,000 3 948 35,000 172 125 295 5,900 a All values are parts per million of the unit cited to nearest whole number (see Reference 5). b Numbers indicate location or area as follows: . (l) Catekfll supply--New York City (2) Swamp Water (Colored) Black Creek, Middleburg, Florida ' (3) Niagara River (Filtered) Niagara Falls, New York (4) Missouri River (Untreated) Average (5) Well Waters--Public Supply--Dayton, Ohio--30-60 ft. (6) Well Water--Maywood, Illinois-- 2090 ft. (7) Well Water--Smithfield, Va.--330 ft. (8) Well Water--Rosewell, N. Mexico (9) Ocean Water--Average are more likely to be contaminated with municipal sewage and trade wastes. Virtually all mineralized waters also contain biological organisms. Mineralogical Characteristics. The character and amount of extraneous inorganic materials--including deleterious gases--dissolved and sus pended therein, describe the mineralogical characteristics of any water. Revealing such information is the function of a mineralogical chemical analysis. . The analyses in Table 1 disclose the composition of the public water supplies used by about 45 percent of the total population of the cities, in the United States, having more than 20,000 inhabitants.6 All values recorded are in terms of parts per million.* This is the approved standard terminology for reporting the results of mineral analyses.6 Values reported in the other terms commonly used may be converted into the standard form by using the factors listed in Table 2. Data for dissolved gases or pH values have been omitted in Table 1 because even waters of the same mineral contents may vary widely in these respects. Unpolluted natural waters usually have pH values within the range 5 to 8, depending upon their free COt contents. Polluted waters, * Parts per million are hereinafter abbreviated ppm. A part per million signifies a unit weight of mate rial per million unit weights of the solution. Corrison and Water Formed Deposits, Causes and Prevention 983 Table 2. Conversion Factors for Water Analyses To CONVKBT Into Multiply by . Grains per U. S. gallon.......................................... Grains per Imperial gallon................. ................ Grams per liter........................................................ Mg per liter.......... ..................................................... ppm ppm ppm ppm 17 14M 1000 1 which include those derived from wells or swamps in marshy ground, may have pH values well below 5. Biological Characteristics. The slime-forming organisms are mostly lower plants, grouped by botanists into the phylum thallophyta. This group is distinguished by the absence of leaves, roots, or stems from the mosses, ferns, and seed plants which comprise the three other phyla of the plant kingdom. ' The thallophyta (see Table 3) are divided into algae, which can syn thesize chlorophyll for the production of sugar, and the fungi which lack chlorophyll, and must therefore secure already synthesized carbohydrates. All thallophyta are of universal distribution and many of them are slime formirig. Of the five divisions of algae, only three (the green, the blue-green, and the diatoms) are found in fresh water. Of the five di visions of fungi, all may occur in fresh water, the principal slime formers being indicated in Table 3. The methods of analysis commonly used in the sanitary examination of a water have, as their principal object, to identify and count pathogens. Most slime-forming organisms are not pathogens. When a water is subjected to a biochemical analysis for the purpose of evaluating its slime producing characteristics, tests, widely different from sanitary bacterio logical tests, must be made. Tests upon the water itself are seldom satis factory, and true indications of the sliming characteristics of a water can only be determined by the analysis of deposits on surfaces having a tem perature close to the temperature of the final design equipment. The results of such a test are commonly reported in the manner illustrated in Table 4. - Condensates All condensates result from the chilling of water vapor. Such chilling may result from natural causes, thus producing dews, sweats, rain, and snow, or from artificial causes, as in steam condensing equipment, pro ducing condensate or return water. Table 3. Principal Slime Formers Phyla Rough Division op Phyla Algae Fungi Single celled, sometimes forming slimy sheets. Many ceiled in either sheets or fronds. Bacteria (Schizomycetes) frequently forming slimy surface coatings. Slime Molds (Myxomycetes) forming slimy sheets as one stage of their life history. Sac fungi (Ascomycetes) of which one division, the yeasts, occasion ally form slimy aggregates. The alga-like fungi (Phycornyceles) and the stalked fungi (Basidomycetes) rarely form slimes uut their filaments may hold together the slimes of other organisms. 984 CHAPTER 43 1956 Guide Table 4. Plant Water Supplied for Examination WATER SUPPLY-- . 200 feet deep well--average water temperature 53 F-- water is producing a brown stain in plumbing fixtures. SAMPLE-- ^ The sample was scraped from the surface of the shell and tube condenser of No. 2 Freon Compressor on the meat chilling room. The sterile sample bottle was filled one-half with deposit and the balance with circulating water. No preservative was added--pH at time of col lection was 7.4. ANALYSIS REQUIRED- MACROSCOPIC L4 BACTERIOLOGICAL (VI MICROSCOPIC bfl ORGANIC CONTENT IVJ PROBLEM- A 25-ton Freon-12 Compressor has head pressure about 10 lb higher than during initial operation, without change in water temperature. Deposits have been observed on heat exchanger surfaces. It is desired to know the nature of these deposits and if they are the cause of this increased head pressure. MACROSCOPIC EXAMINATION-- MICROSCOPIC EXAMINATION-- Heavy brown flocculant material settles rapidly in clear water. pH--7.3 Odor--woody, mouldy. Inorganic Material--small amount white crystals. Amorphous Material--small amount--brown. Iron Bacteria--profuse growth of crenothrix--(Photo usually included). CULTURAL EXAMI NATION . TOTAL COUNT Sabouraud's Agar . 1. Aerobic gram positive spore-forming rod with mu coid sheaths. (Photo usually included). 2. Short gram negative coccibacilli (Photo usually in cluded) . 100,000 organism/cc. ORGANIC CONTENT (by WEIGHT, DRY BASIS)--60% DISCUSSION-- The presence of common slime-forming organisms in the deposit combined with high organic content indi cates that the deposit is bacterial in origin. Heat transfer reductions would be caused by such a deposit. These deposits, combined with crenothrix, can cause corrosion of both ferrous and non-ferrous metals. RECOM MENDATIONS-- It is recommended that the water be treated at the suc tion side of the deep well pump with chlorine in quanti ties sufficient to maintain a free chlorine residual of 1.0 ppm at the discharge of the shell and tube cooler. This treatment can be scheduled on an intermittent . basis. In the heating and ventilating field, the biological characteristics of condensates are likely to be of concern only where the condensate is used as cooling water in recirculating systems. The deleterious gas contents of condensates, however, very often create serious corrosion troubles. The data in Table 5 typify the chemical composition of the atmosphere in rural and metropolitan areas, and of stack gases when various types of common fuels sire used. The curves in Fig. 1 disclose the solubility of the major deleterious gases present in such atmospheres in otherwise pure water, when the partial pressure of the gas is one psia. The most common deleterious gases entrained by steam are oxygen and Corrosion and Water Formed Deposits, Causes and Prevention 985 Table 5. Data Typipting the Deleterious Gas Content of Different Atmospheres . Aik Flub Gases Name of Gas Chemical Formula Rural % by Vol ume Partial Pres sure psia Metro politan Bitum. Coal Fuel Oils % ume Partial Pres % by sure Vol ume psia Partial Pres % by sure Vol ume psia Partial Pres sure psia Natural Gab ' ume Partial Pres sure psia Carbon Dioxide... Sulphur Dioxide.. O. COj so, 21 0.03 None 3.143 0.004 None . 21 3.143 . 2 0.06 0.009 15 0.003 0.004 0.07 0.299 2.245 0.010 7 13 0.03 1.048 1.946 0.004 10 10 0.0001 1.497 1.497 0.0015 carbon dioxide. In rare instances, hydrogen sulphide, sulphur dioxide, or ammonia are present. In most steam condensing equipment,7'8 the non-condensable gases entrained with steam accumulate so that the amount present in the vapor space is several hundred times higher than in the incoming steam and the amount dissolved in the condensate may therefore approach, of even exceed for short periods, the amount entrained by the steam. CAUSES AND PREVENTION OF SCALES AND SLUDGES Scales may be formed on surfaces of equipment in contact with water, and sludges in the body of the water, by the separation from the water of dissolved or suspended solids. According to the nature of a particular 986 CHAPTER 43 1956 Guide piece of equipment and the method of its operation, such separation may be promoted by one or more than one, of several factors: ; a. The concentration of solids may be increased by the evaporation of water. b. The dissolved solids may be rendered less soluble in the water by changes in temperature. c. Conditions may favor the decomposition of unstable compounds with the formation of less soluble compounds. Figs. 2 and 3 show that the solubilities of both calcium carbonate and calcium sulphate decrease with the rising temperature within a moderate range of temperatures. Surfaces transferring heat into water, such as Corrosion and Water Formed Deposits, Causes and Prevention 987 at decreasing pH values (increasing concentration of hydrogen ion) shown in Fig. 2, the carbonate really going into solution largely as bicarbonate. In special cases, primarily with well waters possessing a high natural iron content, deposition of iron oxide from the decomposition of ferrous bicarbonate takes place according to the following reaction: 4 Fe(HC0,)t +0, - 2 FeA + 8 CO, + 4 H> Ferrous , Bicarbonate + 0yg Iron . Carbon , . Oxide + Dioxide + water Low water velocity in heat transfer equipment often causes, sludges to settle out in the tubes. This has the same effect on heat transfer as scale Fig. 2. Solubility op Calcium Carbonate in Distilled Water .Containing Carbon Dioxide (pH Val-ues 'at Approximately 73 F) Fig. 2 Adapted from (1) Ind. & Eng. Chem., 20 (1928) 1197-r-by Baylis. (2) J.A.C.S. 50 (1929) 2086--Frear St Johnson. condensers and coolers, are more susceptible to scale and sludge formation than are the cold parts of the same system using the same water. The most common of the unstable soluble salts are the bicarbonates of calcium, magnesium, and occasionally iron. Under conditions favoring the removal of carbon dioxide, as when the water is strongly aerated or when it is boiled, the bicarbonates are readily converted to the relatively insoluble carbonates. The type of scale most usually encountered is calcium carbonate (often called alkalinity) from the decomposition of calcium bicarbonate according to the following chemical reaction: Ca(HC0,)i + heat -> CaCO, , + CO, + HtO Calcium + heat Bicarbonate Calcium , Carbon + water Carbonate ' Dioxide Conversely, carbonates are readily converted to the more soluble bi carbonate by the addition of carbon dioxide or other acidic materials. This explains the increase in the apparent solubility of calcium carbonate Fig. 3. Solubility of Caixrum Sulfate and of Calcium Carbonate for Comparison . (CaCOi in Equilibrium with Normal COt Content of the Atmosphere) Fig. 3 Adapted from Bulb No. 15, Unto, of Mich. Formation and Properties of Boiler Scales by P. E. Cartridge. formation. When this occurs, increasing the water velocity often cures the condition. It is sometimes desired to evaluate the tendency in a particular water toward the separation of calcium carbonate, which may be desirable as a means of establishing a corrosion-resistant film on metal surfaces, or in other circumstances may be undesirable because of the impedance of the calcium carbonate film to heat transfer. This tendency is indicated approximately by the Langelier Index,5 which is obtained by subtracting the actual pH of a particular water from the pH at which it is estimated precipitation of calcium carbonate would just begin. This estimate may be made by the use of Fig. 4. There are various expedients which may be employed for avoiding or mitigating difficulties due to scales: a. The water may be treated before use to remove elements such as calcium, mag nesium, and iron, which form relatively insoluble compounds. In the various softenmg processes this removal of these elements is accompanied by the addition of other elements, particularly sodium, the compounds of which are relatively soluble. b. The water may be treated within the equipment to promote the separation of 988 CHAPTER 43 19S6 Guide dissolved solids as sludges, rather than as scale which is, in most cases, more ob jectionable. | c. The increase in total solids, due to the evaporation of water, may be controlled by the displacement, continuously or intermittently, of some of the used water by fresh supply. d. Substances, such as the polyphosphates, having the property of inhibiting the precipitation of calcium carbonate from solutions supersaturated with it, may be added. e. The pH of the water may be lowered (hydrogen ion concentration raised) to reduce the tendency for precipitation of carbonate. This is permissible only to such an extent as will not cause a serious increase in rate of corrosion. The choice of the best expedient or combination of expedients must be made for each type of equipment, and will be affected by operating and water considerations. Item c above must be used, regardless of which other items are used, for all recirculating water systems from which evapora tion takes place. . Once-Through Equipment Where abundant supplies of water are available at low cost, the cooling water may pass through the equipment once, undergoing a rise in tempera ture. Little difficulty from scale should be encountered if the Langelier Index is lower than +0.5, based on the highest water temperature en countered in the system. This often corresponds to a carbonate hardness of less than 200 ppm when water temperatures are lower than 100 F. However, since many municipal supplies are softened so that incipient calcium carbonate precipitation is induced, the Langelier Index is a more reliable indication of scaling tendency. Prevention of scale in once through systems is based primarily on the adjustment of pH, the application of surface-active agents, or a combina tion of the two. Normally the addition of a few parts per million of a surface-active agent such as a polyphosphate10 fed proportionately to a water with a scaling tendency is all that is required to control scale. Where a given water does not respond satisfactorily to surface-active agents, reduction of pH with sulfuric acid or carbon dioxide is often em ployed. The pH is reduced only sufficiently to have it fall within the effective range of the surface-active agent. The use-of acid or carbon dioxide is sometimes permitted without polyphosphates when corrosion will not be severe. In this case the pH is reduced so that the Langelier Index is less than +0.5. The acid or carbon dioxide must be added with care.' Use of automatic pH controllers is required if corrosion is to be pre vented. A special case of scale from ferrous bicarbonate decomposition was men tioned previously. Ferrous bicarbonate is considerably less stable than calcium bicarbonate. The prevention of this decomposition can be ac complished by the addition of polyphosphate in low concentrations.11 The use of polyphosphate in the ratio of two parts by weight to one part by weight of iron is usually most effective. The polyphosphate must be added to the water before exposure of the water to air or chlorine if ef fective stabilization of the iron is to occur. . Closed Recirculating Systems The closed recirculating system is one in which water circulates through one heat exchanger where it absorbs heat, has its temperature elevated, and circulates through another heat exchanger in which its temperature is lowered. In cold water or chilled water systems scaling is seldom a Corrosion and Water Formed Deposits, Causes and Prevention 989 I 1 -S If I f I -9 |! 3 a 1 - is - 3 S 3 J*s 1 I 3,1 3- j I* s-s. Z< I*r 3* 1! ! ?5 III go. E-I a u 8, H 0 eo ^ 3 IP s P0S "I I I I I H||i`'HU"m ' | I|1|i|||||||nii|nnp|in MI|'|I|I|I|.| , m BA* >) 4 A(D O O -- 0)00000000 -- n run qoo OqOOOOOOO now ooo oo *P*PS -- - n D#) q o o a -3 fat0! Si 8 w 0 s 03 I 0 > Kb 2 a*3 .5 8o 4 -"o a g p.9 S i||l 0 0 000000-0 I** o ' W O o I...11, Hill min.. I *Jr- 1-0n n. -o - _NO ?* n nC. n i*-* o_o o-NW-oom2 a<5w -ooow *ow oooo# 3 I 1N |*) |a |V) i0llQio|-Trn|-HoWo--[ i -to1o-1 io-n|. oIIo'l'lo'~l1 -oo- ooI ooToo'I o o ft to* oo 9 ^ i 11ii r i y ixrrp 4 z W --- 1 <?j p g> S AH 02 ^ . Jq |S sgl ft8 . 5 -S-3 z -? -3 ? IF? 41 + ~<0a0 *a5S o {4 --< CO ! o a t .-a% ,20.25^ OO SggS 3<,+1>3at I, co 0} *3 2 g1 Q R-'S -^"la PooS art *j. Is a s ao cS 55 Q .at t a3 Z< apt* 2a J-3 f2a 0o5 - PS o o&a *3 S-o I T3 6Hf <<00 O3* fo S'3 *2 OS 0bfl 83 Bo 33 .2 * JS t9o a o"(O-> 0 S-j 4o o. a Iaf~ ga 0T3- 21 Ilif r.15! a ^ Q **.2 990 CHAPTER 43 : 1956 Guide problem. In hot water systems scaling is seldom a problem unless there is a large amount of makeup water.1* In these cases the use of surface- active agents such as polyphosphate are used. Open Recirculating Systems . Where water from condensers and similar equipment is passed through a spray pond or cooling tower and then returned to the equipment, there is an increase in the concentration of solids because of the evaporation of some of the water into the cooling air, and, moreover, the aeration removes carbon dioxide. Both factors promote the tendency to deposit scale. This condition is also true for air washers during periods of operation when air is humidified. Evaporation of recirculated water occurs, causing concentrations of scale forming minerals. (There are cases, such as in New York City, where water supplies have extremely low solids content. Aeration in air washers and cooling towers causes absorption of acid gases f </ a c1 7 nos HAT : tw ATM 7 1TTT.. _ 50 OO 150 200 250 300 PPM ALKALINITY AS CtCo, OP MAKE-UP WATER Fiq. 5. Relation of Bleed-Off Requirement to CaCOj in Make-Up Water such as sulfur dioxide, S02, from the air. Serious corrosion rather than scale occurs.)13 The concentration of scale-forming minerals in open recirculated cooling water is limited by natural drift or windage loss. This is the loss of water droplets from the system. Windage losses from typical systems may be classified as follows, based on recirculating rates: Evaporative Condensers and Air Washers Mechanical Draft Cooling Towers.............. Atmospheric Cooling Towers......................... Spray Ponds........................................................ Percent of Recirculat ing Rate . 0 to 0.1 . 0.1 to 0.3 . 0.3 to 1.0 . 1.0 to 5.0 To show the effect of concentration in a typical mechanical draft system assume: 1. Recirculating Rate = 100 gpm. 2. Drift loss = 0.2 percent of recirculating rate = 0.2 gpm. 3. Evaporation Rate = 1 percent of recirculating rate = 1.0 gpm. 4. Calcium bicarbonate in make-up water = 100 ppm. ' 5. Calcium bicarbonate in evaporated water = 0 ppm. Corrosion and Water Formed Deposits, Causes and Prevention 991 Let K = concentration of calcium bicarbonate in recirculating water = concen tration of calcium bicarbonate in drift loss. The process of concentration in the system may be represented dia grammatically as follows: ' Make up = 1.2 gpm Ca(HC03)t = 100 ppm Evap. = 1 gpm Ca(HCOi)i = 0 ppm t__________ Recirculating Water System A = Ca(HC0i)2 cone. Drift 0.2 gpm Ca(HC0i)i = K ppm The concentration may be obtained from the equation (Make Up) [Ca(HCOi)j cone.] = (Evap.) [Ca(HCO)i cone.] + (Drift)[Ca(HCOj)i cone.] (1.2) (100) = (1)(0) + (0.2) (K) substituting, whence, 120 = 0 + 0.2 K K = 600 ppm Therefore the concentration of calcium bicarbonate in the recirculating water equals 600 ppm. This far exceeds the allowable concentration of 170 ppm at which scaling will occur. To correct this situation, it is imperative to provide a continuous bleedoff or blow down from the recirculating water circuit. Typical bleed-off requirements are shown in Fig. 5. Reference to the No Treatment curve shows that a bleed-off rate of 1.2 times the evaporation rate is required when a make-up water contains 100 ppm calcium bicarbonate (or alka linity) if scale is to be prevented. Calculation by a material balance will show that the bleed-off plus drift loss will limit the calcium bicarbonate to 171 ppm. It can be seen from Fig. 5 that very large amounts of bleed-off are re quired as a make-up water approaches or exceeds 150 ppm of alkalinity. When alkalinity exceeds 175 ppm, bleed-off alone is no longer effective. The use of 5 ppm or less of polyphosphate is extremely effective in reducing the required bleed-off and making possible the use of make-up waters which will not respond to bleed-off alone. Occasionally, waters are encountered which have exceptionally high alkalinities or which develop high pH values when recirculated. The use of sulfuric acid is common in these cases to maintain pH values between 7 and 8. Polyphosphates are most always used when acid is required. It is very important to control acid feeding carefully to avoid serious corrosion. Automatic pH controllers are often employed for such purpose. Heating System In hot water heating systems or in steam heating boilers where all con densate is returned, troubles from scaling should not be severe. If neces sary, sodium phosphate or sodium carbonate may be added to the watei to prevent the formation of adherent calcium sulphate scale. 992 CHAPTER 43 1956 Guide Boilers and High Temperature Equipment Where temperature exceeds 250 F, complete softening of the water is the only practical method for minimizing sludge formation. This is usually accomplished by artificial or natural zeolites (called also ion-ex change materials) or by hot-process precipitation softeners. In boilers operating at pressures above 100 psig virtually all the calcium, magnesium, sihca, iron, and manganese salts entering with the feed water are potential scale or sludge formers. In boilers operating at 100 to 250 psig, the formation of .adherent cal cium, sulphate (anhydrite) scales is most to be feared. Such deposits form on the hottest evaporative surfaces. The scale has a low heat con ductivity. Even a layer of egg shell thickness may so impede the rate of heat transfer as to bring about over-heating of the metal. The ortho-phosphates of sodium are most frequently used to prevent sulphate scales. The concentration of phosphate required is such as to cause the precipitation of calcium phosphate as sludge, thus keeping the boiling water under-saturated with respect to calcium sulphate. To a lesser extent, sodium carbonate (called also soda ash and sal soda) is also used. Most of the effective boiler compounds contain either phosphates or soda ash, or both. Certain organic materials and colloids are some times found to minimize scale formation. . Where chemicals are introduced directly into the boiler in amounts adequate to prevent scale, sludge is formed in amounts proportionate to the calcium and magnesium salts entering with the feed water. To prevent troublesome accumulation of this sludge, as well as soluble salts, as evaporation occurs, some blowdown of boiler water is necessary. CAUSES AND PREVENTION OF SLIMES . A water containing slime-producing organisms will produce prohibitive amounts of slime only when the conditions of use are such as to propagate their life processes. Whenever sufficient food material from normal water or from airborne dust combines with optimum temperature conditions, such as exist on cooling surfaces and air washers, serious quantities of slime will be produced. ' Some natural well waters do not contain sufficient foods to support luxuriant slime growths. Algae, which require fight for carrying on their life processes, are hkely to cause difficulty in cooling towers and other areas where sunlight is abundant. The ordinary slime-forming, bacteria are capable of using a wide variety of nitrogenous and cellulose material as food sources. These bacteria thrive best under dark conditions such as exist in condensers and other heat transfer surfaces. Other organisms capable of causing similar difficulties use such a wide variety of food material as algae,14 iron compounds,15 and inorganic sulphates.16 At present, the use of toxic chemicals and irradiation are the two general means employed in slime control. The value of ultra-violet fight, used so broadly in the beverage industry, is somewhat in dispute. Anti-fouling paints have been developed and are fairly satisfactory for the prevention of the growth of macro-organisms such as barnacles and mussels, but these paints must be renewed at frequent intervals, and are not applicable to inaccessible areas such as the inside of pipe lines and cooling towers. Satisfactory anti-sliming paints have not been found. Names and other pertinent data relating to some of the more common chemicals used in shme control are shown in Table 6. Corrosion and Water Formed Deposits, Causes and Prevention 993 Chlorine is the only chemical to which is attributed the ability to de stroy slime-forming organisms. The others are presumed to poison marine organisms, most of which recover when the chemical is not used regularly. While chlorine is the most generally used chemical, the use of others may occasionally prove to b.e more practicable. Choice of the nhemionl is conditioned largely by the design and operation of the system. Open Recirculating Systems In spray ponds and cooling towers of the open type, light-loving algae growths are likely to cause blocking of the distribution piping and troughs. These organisms are most troublesome in areas accessible to sunlight. Algae shmes are usually stringy in character. In open recirculating systems, continuous use of small quantities of chlorine is generally most satisfactory. In once-through systems, where Table 6. Common Chemicals Used fob Slime Contbol Chemical . ' Trade Name Physical State* Chlorine Chlorinated Phenols Sodium-- Potassium Permanganate Copper Sulphate . Chlorine Calcium Hypochlorites Sodium Hypochlorites . Chlorophenylphenate . Tetrachlorophenate Pentachlorophenate Permanganate of Potash Blue Vitriol Gas Crystalline Briquettes Briquettes Briquettes Crystalline Crystalline * As Shipped. large quantities of water are used, intermittent treatment a few times each day wifi usually result in satisfactory shme removal and chemical economies. Neither the phenols nor copper sulphate may be used for the removal of slime already formed. For this purpose, chlorine gas is used. After being cleaned, the other chemicals may be used to prevent the reestablish ment of shme in the system. The removal of green algae from a cooling tower should never be used as an indication that the true slime-forming organisms on heat exchanger surfaces have been removed. The more resistant slime formers, which so materially reduce heat transfer efficiency, will often be unaffected by treatment which completely eliminates algae. Copper sulphate must be used with care because it can cause serious corrosion of steel in a system. It is also ineffective in alkaline water be cause the copper is precipitated from the water. Closed Once-Through Systems In equipment where light is excluded, slime formations are due to fungi. Usually, they predominate on the heat exchange surfaces. Bacteria form thick, soft slime. Yeast and molds form tough rubbery shmes. Chlorine and hypochlorite solutions, fed intermittently, are usual preventatives. UNDERWATER CORROSION When deleterious substances are present in water, the corrosivity of the solution is increased in proportion to the amount of deleterious substances present, the temperature, and usually the rate of flow of the solution over 994 CHAPTER 43 1956 Guide the metal surfaces. There are other relevant factors, but their influence in general is subordinate to those mentioned. Dissolved oxygen, acid gases, and chloride salts are the corrosion accelerators most frequently encountered. Neutral and slightly alkaline waters saturated with air, corrode iron at a rate about triple that for the same water free of air. Hot water containing oxygen will corrode iron at a rate three to four times that for the same water when cold. Corrosion of iron decreases as the pH of water solutions increases, and practically ceases at a pH of 11. If the metal contains film forming agents, such as chromium, nickel, and silicon, or if the water contains inhibitors such as silicates and chromates, corrosion may in some instances be minimized. Soft water, as for example the effluent from zeolite softeners, is likely to be several times more corrosive to iron than hard waters. In small installations, the use of copper or brass pipe usually is a practical ex pedient. Cement-lined pipe and tanks suitably resist attack. Where the water contains slime-forming organisms, especially those bacteria that thrive on iron, chlorination of the water is imperative to inhibit tuberculation and subsequent pitting. Bitumastic paints, applied at regular intervals upon well cleaned sur faces, will measurably prolong the life of equipment handling cold waters. Pipe Materials. Brasses with 60 to 67 percent copper are dezincified in some corrosive waters, and in certain localities are not much more service able than galvanized iron or steel pipe. The zinc in brass pipes is leached out locally, leaving a plug of porous copper. The weakening of such pipe is especially noticeable under the threads. Dezincification is retarded by the use of silicate of soda (8 ppm added silica).17 In salt or fresh water, there is no material difference in rate of pitting of wrought iron, steel, low metalloid steels, or copper bearing steels. This is contrary to the relative performance of these metals in atmosphere. Once Through Systems Corrosion prevention in once through systems is obtained by any one of or a combination of the following methods.12 1. Forming a protective film of calcium carbonate on the metal surfaces. 2. Mechanical or chemical deaeration, or both, of the water. 3. Use of organic or inorganic corrosion inhibitors, or both, in low concentrations. Formation of a thin protective calcium carbonate film is accomplished by adjustment of the water until the Langelier Index has a value greater than +0.5. This is rather difficult in systems which have a wide varia tion in temperature. Since the Langelier Index is dependent on tempera ture, when a water is adjusted to form a protective film on those surfaces of higher temperature, no film will form on colder surfaces. Therefore, this method of corrosion control is more applicable to large municipal distribution systems. Where heat transfer is involved, the method is usually impractical except under unusual circumstances. When this method is used, pH is increased by using an inexpensive alkali such as lime, caustic soda, or soda ash. Lime is usually used for waters of low calcium content. Caustic soda or soda ash are used for waters of high calcium content. Mechanical18 and chemical deaeration are not often used in once through Corrosion and Water Formed Deposits, Causes and Prevention 995 systems because of relatively high operating costs. Mechanical de-. aeration also requires the use of costly equipment. Chemical deaeration is usually accomplished by raising pH with caustic soda and by continu ously feeding catalyzed sodium sulfite in proportion to water flow. The use of catalyzed sulfite is not permitted in water to be used for potable purposes. . There are several corrosion inhibitors such as chromate, polyphosphates, and silicates which are effective in once through systems.19 Chromates are not usually used because, when maintained at an effective concentra tion of 300-500 ppm, their cost is prohibitive. It has been found that the use of polyphosphate at a concentration of 2-5 ppm is effective in controlling tuberculation of iron pipe and in reducing overall corrosion. The use of chromate-polyphosphate concentrations at less than 60 ppm has also proved effective. Under no circumstances may chromates be used in potable water systems. Sodium silicate is often used in relatively soft waters by increasing the silica content about 8 ppm. It is used primarily to reduce corrosion in potable water supply systems. Open Recirculating Systems Corrosion in open recirculating systems, such as air washers, and cooling towers, is usually controlled by use of corrosion inhibitors such as chromates polyphosphates, a combination of chromate and polyphosphate, and nitrites.20'21 Mechanical or chemical deaeration is not practicable in open systems because of the high rate of aeration. It is not practicable to use high pH values of 11 or more in systems containing wood. High pH will cause serious delignification of wood. High pH values also pre vent control of scale. Corrosion control is usually carried out in the pH range of 6.5-8. Chromates are by far the most effective corrosion inhibitors. It is extremely important, however, to maintain an adequate concentration of 300-500 ppm, which is effective for most systems. If for economic reasons substantially lower concentrations are used, serious pitting corrosion may occur. Polyphosphates are most effective in reducing tuberculation. It is not usually possible to reduce overall corrosion to anywhere near the degree possible with chromate. Where economy of treatment is of primary importance, a substantial reduction of pitting and overall corrosion can be obtained by using as little as 60 ppm of a mixture of polyphosphate and chromate. Close control over pH is a requirement for good corrosion control by this process. Sodium nitrite has not had widespread use as a corrosion inhibitor in open recirculating systems. It has been reported that difficulty may be encountered in maintaining effective concentrations. Considerable field experience is heeded to further qualify this inhibitor. Closed Recirculating Systems The term Closed Recirculating System is in reality a misnomer. Except for relatively small systems, most closed systems are open because they most usually require make-up water.. Recently, tests conducted on 84 closed systems indicated that more than 50 percent of the systems had one or more water changes per month because of leakage. Weekly water changes were found in more than 10 percent of the systems.22 Continuous make up, of course, replenishes oxygen in the system, thus promoting 996 CHAPTER 43 1956 Guide corrosion. It is imperative, therefore, that corrosion control be provided for most closed systems. The age old assumption that closed systems are closed is no longer valid. . Corrosion control is usually accomplished by (1) mechanical or chemical deaeration or (2) use of corrosion inhibitors such as chromates and nitrites. The use of polyphosphates is not generally recommended for closed systems because they will revert to ineffective orthophosphates unless there is a large replacement of water containing polyphosphate. Higher concentrations of chromate are usually maintained in closed systems as compared with open systems. This is primarily due to the fact that, since water losses are usually small, the cost of maintaining excess chromate as a safety factor is small. Treating Chemicals Whenever chemicals are used to control scale, corrosion, algae, and slime, competent advice from a water chemist is desirable. Often factors considered irrelevant to the layman, will be of much importance in secur- Table 7. Quantities op Sodium Dichromate to be Added to Maintain Initial Concentration Specific Gravity of Brink to be Strengthened Lb Sodium Dichkomats per 100 Lb CaCli Added 1.16 1.18 1.20 1.22 1.24 0.695 0.621 0.556 0.502 0.455 Lb of Sodium Dichromate per 100 db NaCI Added 1.12 1.14 1.16 1.175 1.79 1.47 1.32 1.18 ing effective treatment. Very often troubles are created through im proper use of chemicals and are more serious than if they were not used-23 Refrigerating Systems Corrosion in refrigerating systems is confined to surfaces in contact with brines or those in contact with the refrigerant. . Brines. Refrigerating brines usually are comprised of sodium chloride, calcium chloride, or calcium and magnesium chlorides. The corrosivity of dilute brines is higher than their more concentrated solutions. The corrosivity of sodium brines, other conditions being fixed, is about 1.5 times greater than brines of the alkaline earth metals. Brines are excellent electrolytes. Contact of dissimilar metals of wide potential differences, when in contact with brines, results in rapid corrosion by galvanic action. ' The leakage of air, acid refrigerants, or both, accelerates the corrosivity of brines. Ammonia precipitates calcium and magnesium salts, thus clogging the system at restricted points. The addition of caustic soda and sodium dichromate to brine solutions to inhibit corrosion of iron, is a more or leis general practice. Sodium sili Corrosion and Water Formed Deposits, Causes and Prevention 997 cate and sodium phosphate are also used at times, but tests indicate they are not as effective as is sodium dichromate. It has been suggested24 that 125 lb of sodium bichromate per 1000 cubic feet of calcium chloride brine, and 200 lb per 1000 cubic feet of sodium chloride brine, be added to inhibit brines; that when salt or calcium chloride is added to "strengthen" brine, sodium dichromate also be added in the amounts shown in Table 7. Refrigerants. The common refrigerants, except those of the hydro carbon type, will attack the common metals and alloys if moisture is ;present. Even a very small amount of water may cause severe corrosion with certain refrigerants. The amount required need only be sufficient to produce a water film on the metal surface. With the halogenated hydrocarbons, complete elimination of water is much to be desired. Where ammonia is used, copper and its alloys, aluminum and zinc, are attacked especially at elevated temperatures. When.sulphur dioxide is used, more than 50 ppm (0.005 percent) of water will cause appreciable corrosion of virtually all the common materials. Minimizing Condensate Corrosiveness There are four expedients that may be utilized to minimize corrosion in steam condensate systems: (1) treatment of the boiler feedwater so as to eliminate deleterious gases entrained with the steam, (2) design of the condensing equipment to minimize dissolution in the condensate of the deleterious gases entrained with the steam, (3) chemical treatment of the condensate, (4) use of resistant metals. Boiler Feedwater Treatment. Elimination of oxygen from boiler feed water and, therefore, from the steam developed, can be accomplished either mechanically or chemically. In some steam generating stations, both ' expedients are employed. Tests25 have indicated that in small low-pressure heating boilers, where the boiler input contains less than about 50 ppm of carbonate hardness, the CQi in the steam can be controlled by adding calcium hydroxide to the boiler. In Fig. 6 are shown the equilibria conditions proposed for boilers operating at pressures up to about 5 psi gage. This expedient may not be used in higher pressure boilers, because of the possibilities of scale and sludge formations. In the latter, the only method used to date for treating the feedwater consists of removing the' alkaline earth salts, i.e., softening, and subsequent acidulation followed by deaeration at tempera tures near the atmospheric boiling point of water.26 Design of Condensing Equipment. In the design of water heaters and comparable types of condensing equipment,27 it is possible to shift the accumulation of non-condensable gases to a location away from the con densate level and, subsequently, vent these gases to the atmosphere. Venting an amount of steam equal to about one-half percent of the total steam entering the condenser is the optimum vent rate. Venting is of little practical value when the COi content of the in coming steam is below about 5 ppm. When the steam contains more than 5 ppm, venting provides a means of producing a condensate containing a minimum of about 3 ppm. However, even as little as 3 ppm of dissolved COi can produce active corrosion if large amounts of condensate are flowing. Chemical Treatment of Condensate. Condensates containing compara tively large amounts of oil, are practically non-corrosive, due to the pro tective film provided by the oil. When oil is intentionally added to con- 998 CHAPTER 43 1956 Guide densate,28 inadequate quantities may accelerate rather than decelerate corrosion on those surfaces not covered by the oil. Sodium silicate added to CO^bearing condensate has been shown to decrease, but not entirely prevent, corrosive action. It is not known whether the protection af forded by silicate solutions is due to the establishment of a protective film on the metal surface or to neutralization of the CO2 by the alkali in the silicate solution. It has been postulated that ammonia,29 cyclohexylamine,30 ethylene diamine, and morpholine31 will retard corrosion of condensate lines. Tests with benzylamine have also been reported.32 Where copper and its alloys are involved, the use of alkaline inhibitors is believed inadvisable. The use of small amounts of sodium hexametaphosphate has been. suggested -r f i if" rtf! IW4| <*1 i*l`i j Fiq. 6. Relation of Hydrate/Cabbonate Content in Bard Boileb C02 5 PsiWateb and in Steam at About Operating Pressube 1l=*i (All analytical values are ppm by weight) too, but tests33 indicate that this salt accelerates rather than decelerates, the rate of attack of steel by condensate containing C02 and oxygen. Whether chemical treatment of steam or condensate is feasible, must be determined not only upon the basis of the acuteness of corrosion troubles, but also upon the uses to which the steam or condensate is put. Use of Resistant Metals. For economic reasons, the metals known to resist corrosion can seldom be used exclusively for condensate lines in any sizable enterprise. Nevertheless, there may be instances where the use of a limited amount of the more costly, but resistant, materials can be justified. The data in Fig. 7 are the results of tests34 designed to reflect the corrosion resistance of the more commonly used metals to attack by condensate containing oxygen and C02. In contemplating the use of a resistant metal, as a section jf a conden sate line, it should be remembered that, if other conditions are 'right, corrosive attack will merely be transferred down stream in the system. Galvanic corrosion resulting from the contact of dissimilar metals in a condensate line seldom occurs. No paint or similar protective coating Corrosion and Water Formed Deposits, Causes and Prevention 999 has thus far proven satisfactory. Tests of cement-lined and vitreouslined pipe have shown the linings to be readily dissolved by hot condensates. ATMOSPHERIC CORROSION Most of the problems originated by atmospheric corrosion occur in connection with the fire-side of boilers and furnaces (including their flues and stacks), sewer vents, air ducts, coal and ash handling equipment. Usually such equipment is fabricated from common types of ferrous metals. Generally little or no atmospheric corrosion occurs at temperatures higher than the boiling point of water, because at such temperatures little or no condensate is formed. If it does form at the higher temperatures, only negligible amounts of carbon dioxide and oxygen present in the b8ESSOJER STEtL N B LREO BRASS AT : rr PHOSPHORIZCO COPPER PHOSPHORIZCO ADMIRALTY V PHOSPHORIZCO AOMIRALTT *8* Bt ARSENICAL COPPER ARSENICAL AOMIRALTT CUPRO NICKEL 00/20 TIN COATCO COPPER ALUMINUM VSTAINLESS STEEL STAINLESS STEEL *8* INCONEL 1 90 0A1 TEST 1 0 OAT Tl JT l l mt30 TE, T 2A IImcoi 1 1U sR 0 12 19 20 WLE10 SIEC ME NS tLEC SI*ECJINC NS MCASLIRAI VAI-UE 28 O 4 8 12 16 20 24 28 0 4 B 12 16 20 24 28 32 36 40 AVCRACe PENETRATION IN INCHES PER TEAR X lOOO Fiq. 7. Comparative Corrosion Resistivity of 10 Materials Exposed to Condensate atmosphere, will dissolve in the hot liquid, but sulphur gases may dissolve and cause rapid attack; Oxygen, sulphur dioxide, sulphur trioxide, and carbon dioxide are the deleterious gases most frequently accountable for corrosion in moist atmospheres. Coal Storage and Handling Equipment Virtually all coals contain sulphur in the form of pyrite, and some moisture. In storage, the pyrite is likely to be decomposed by oxidation. Moisture dissolves the products of decomposition forming sulphurous and sulphuric acid. The acid solutions vigorously attack the supporting metal. Rubber linings have been developed for coal chutes and bins to ef fectively resist corrosion and the abrasive action of the coal, but they are expensive.35 Concrete linings for steel bunkers have also been ef fectively employed.36 The use of high chromium steels is not always a sure cure, especially with coals treated with dust allaying agents high in chlorides. Flues, Stacks, and Fire-side of Boilers The surfaces of flues and boilers contacting the products of combustion, seldom experience corrosive attack when the- equipment is in operation. ! ' ! ; tag. !> i 1000 CHAPTER 43 1956 Guide Breechings, smoke hoods and canopies in contact with flue gas may, how ever, be subject to attack during the warming-up period of an appliance, or when the rate of operation is so low that the temperature of the flue gas is below the dew-point. It is common practice to use cast-iron or acid resistant vitreous enameled steel in flue gas connections to appliances, to prolong the life of these parts. The shut-down period, when condensation of moisture occurs on the metal surfaces, is usually the time when most damage is done." In those sections of the stacks where flue gas tempera ture drops below the dew-point, corrosion is inevitable during operation. It is clear that where long shut-down periods are anticipated, a practical method for mitigating corrosion is to clean the surface thoroughly and to provide adequate clean, dry air circulation to prevent condensation. (See also Care of Idle Heating Boilers, Chapter 16). Protective coatings with organic binders are destroyed rather rapidly above 400 F because of the decomposition of the organic materials. The surfaces of metals, whose temperature does not exceed 400 F, may be pro tected by periodically applying paints such as those specified in the fol lowing paragraphs entitled Air Ducts. . Air Ducts The most practical method for protecting air duct surfaces made of steel from atmospheric corrosion, is to apply protective paints. One of the most effective protective coatings is red lead paint. Three coats of paint should be applied, of which the first two coats should be rust inhibitive paint such as red lead paint, with the second coat tinted to a light brown color with carbon black, and the finishing coat may be red lead paint tinted to a black or brown color, black paint made according to Federal Specification TT-P-61,' red iron oxide paint con forming to Federal Specification TT-P-31, or white or light tinted paint made according to Federal Specification TT-P-40. Another paint which has had some use fob priming iron and steel is zinc chromate paint. Under some conditions, a chlorinated rubber base paint made according to Federal Specification TT-P-91 may be used for the finishing coat, particularly where the presence of highly corrosive gases or contact with strong alkaline water would injure the standard paints. Rubber base paints should be used only for the finishing coat over regular jpriming and second coats. . BURIED PIPE LINES Lines that are cold and in intimate contact with the earth are corroded from the same causes as in mineral waters, but pitting is usually more intense due to variations in concentration of salts and oxygen in solution, acidity, drainage, and presence of solid materials (such as cinder) in contact with metal pipe. Galvanic currents, induced by contact of certain dis solved constituents in the soil, often act over a large area, and accelerate .corrosion where they leave the pipe line. Certain bacteria that thrive in the absence of oxygen have the power to obtain hydrogen and dissociate sulphates in the soil, with a resultant pro-, duction of hydrogen sulfide which attacks the iron to form iron sulphide. Stray electric currents from electric power generating stations, some times find their way into buried steel structures, and do damage in pro portion to the current density where the current leaves the metal to enter the ground. Corrosion and Water Formed Deposits, Causes and Prevention 1001 Pipe Materials Under many conditions where steel would be corroded, the use of corrosion-resistant metals other than steel may be desirable, even if greater in first costs. Wholly austenitic stainless steels are very resistant to under ground corrosion. In most environments copper, red brass, and copper- silicon alloys will resist corrosion and may, at times, be used to advantage. However,88 soils with a high content of organic matter, or alkaline soils in which the ratio of chlorides and carbonates to sulfate is high, may be corrosive. Copper should not be embedded directly in cinders or in tidal marshes where it may be subjected to attack by sulfur compounds. Lead" corrodes chiefly in soils deficient in oxygen or containing cinders. Because lead is corroded to a considerable extent in most soils, lead coatings applied to steels are not adequate for underground use. . Galvanized iron pipe will resist corrosion for various periods of time, depending on the soil and how long the galvanized coating lasts. The zinc used for the galvanized coating is on the electrochemical protective side of the iron, and the zinc is corroded and changed to zinc compounds before the iron is attacked. This accounts for the protection afforded by gal vanized iron. Even if some protection is obtained, eventually the gal vanized coatings are destroyed by chemical action and the corrosion .of the steel begins. Protective Coating Protective coatings for buried pipe lines are in a class by themselves because of the unusual service conditions, and because it is not possible to maintain them by recoating when necessary. Buried steiel pipe lines have been protected against corrosion with considerable success by the use of very thick bituminous coatings applied in molten condition. The best results are obtained by applying the bituminous coatings over a standard priming coat such as red lead or a bituminous paint, and for long service it has been found that after the bituminous coatings are applied, a wrap ping of asbestos fabric saturated with bitumens will prevent movement and displacement .of the bituminous coatings, and add greatly to the length of time satisfactory protection will be maintained. Cathodic Protection Protection is obtained by rendering the structure cathodic, to the sur rounding water or soil by means'of a controlled difference of potential. This method, which has proved satisfactory and economical on a number of gas and oil pipe lines underground, has also been applied with some success to the protection of the inside of water storage tanks and other structures that are in contact continuously with water. Protective coatings that insulate a large portion of the metal surface will reduce very materially the total amount of protective current that must be impressed on bare anodic areas to arrest corrosion. * Because of differences in environmental conditions, it is-necessary to determine or estimate the minimum current density required for each structure, and design the anode or anodes so that the necessary protection can be obtained most economically. In water having relatively high electrical conductivity such as in sea water, this is comparatively easy compared with fresh water. In the latter, the composition of the water is a major factor. It is therefore desirable to obtain an accurate estimate of the minimum current density required. The current is then controlled by the potential between the anode and the structure to be protected. 1002 CHAPTER 43 1956 Guide Rectifiers have generally proved to be the most practical m^ans for supplying the necessary current for protection of surfaces in contact with neutral waters.40 ' HANDLING WATER TREATING CHEMICALS Virtually all the chemicals used in water conditioning are injurious if taken internally in large doses. Many also cause severe skin irritation. Thus, they should be handled with caution. Caustic soda, lime, and concentrated sulphuric acid will bum the flesh. In addition, if mixed with small amounts of water, sufficient heat may be generated so that spattering occurs or the container becomes too hot to handle. . The chlorophenol compounds, even in the low concentrations used in water conditioning, have been reported41 to produce dermatitis. Chrom- itch is not uncommon among workers handling chromates. The amines are said to be absorbed through the skin.42 Morpholine is said to cause kidney and lung trouble when so absorbed. Chlorine gas irritates the skin, eyes, and mucous membranes. Concen trations as low as 0.004 percent by volume in air cause dangerous illness in 0.5 to 1 hour. When relatively large amounts of the non-gaseous chemicals are to be handled, protective clothing, including goggles, should always be pro vided, and a shower head or its equivalent provided at or very near the point where the chemicals are mixed. Chemicals should always be washed from the skin with large volumes of water. For the handling of chlorine and chlorinators, the U. S. Public Health Servicea stipulates the following safety requirements: 1. Suitable gas masks and a smalt bottle of ammonia for testing for leaks should be kept at convenient points immediately outside the room or enclosure in which chlorine is being stored or is in use. Gas masks should be inspected at regular inter vals and kept in serviceable condition. Note:--All-purpose masks offer adequate protection only when the concentration of acid gases does not exceed two percent-- see Safe Practices Pamphlet #64 National Safety Council. 2. Chlorinating equipment and cylinders of chlorine should be housed preferably in separate buildings above the ground level. 3. The room or building housing chlorinators in service should be maintained at a temperature above 60 F, but never in excess of the normal summer temperature. The cylinders of chlorine should be shielded, where necessary, from excessive heat or cold. Direct heat should not be applied to cylinders of chlorine, nor should hot water be poured over them or come in contact with the cylinder valve. 4. Adequate ventilation should be provided for all enclosures in which chlorine is being fed or stored. 5. All joints of tubing connecting chlorine cylinder and chlorinators should be kept absolutely tight and inspected frequently to insure tightness. Tubing should slope upward from the cylinder. LEGAL REGULATIONS In a number of states, the water used for humidification, even in in dustrial plants, is required to meet drinking water standards insofar as bacteriological quality is concerned. A ruling of the JJ. S. Department of Agriculture, Meat Inspection Division, prohibits the use of chromate in water used for air washing when the air later contacts foodstuffs.44 There is an ever growing consciousness oh the part of public health officials, of the necessity for regulations to protect potable water supplies. Attesting this is an ordinance46 now in effect in Detroit, Michigan, which stipulates in part : Corrosion and Water Formed Deposits, Causes and Prevention 1003 "No physical connection shall loe maintained between lines carrying city water and pipes, pumps, or tanks supplied from any other source. Where dual supplies are necessary or desired, lines carrying city water must be protected against back flow of polluted water by an atmospheric gap. Secondary supplies and emergency sources shall include: surface waters from rivers, lakes, ponds, lagoons, and reser voirs; well waters both deep and shallow; any supply of water which has been stored iT- reserved after being used for industrial purposes; cooling water, or water which has in any way been treated, processed, or has been subjected or exposed to any contamination of a bacteriological or chemical nature; and water from any other source than the city supply." The XJ. S. Public Health Service stipulates: "Salts of barium, hexavalent chromium, heavy metal glucosides, or other sub stances with deleterious physiological effects, shall not be allowed in the water supply system. The same agency recommends that the concentration of the substancea listed be held below the values cited in Table 8. The Board of Directors' Table 8. Recommended Maximum Allowable Content in Water Supply* Substance Max. Concen tration, ppm Substance Max. Concen tration, ppm Copper...................................... Iron & Manganese (Total) . Magnesium. ..... Zinc................... Lead.............................. Fluorine................................. 3.0 0.3 125 0 15 0 0.1 1.0 Selenium.................. Phenols (Total)......... Poly-phosphate of Sodium. 0.05 0 05 o.ooi 10.0 10.6 a U. S. Public Health Service. of the American Water Works Association has accepted these values as standard for all public water supplies in the United States.46 While their action is not binding, prudence dictates that no form of treatment should be used that will result in raising the concentration of the substances listed above the value cited. Since virtually all of the permissible chemicals used for scale, slime, and corrosion control have deleterious, physiological effects if taken internally in relatively large doses, they should always be carefully proportioned. To msure this, the Detroit ordinance stipulates that the chemical feeding device must have the following major characteristics: "}. There shall be a visible means of checking the quantity of material being applied by the feeding device. 2. A water metering device, sealed to prevent tampering, shall be installed to measure the flow of water being treated. 3. The device shall be constructed so that in the event of back-flow or vacuums, tne maximum amount of material that may be possibly back-siphoned from the device or any of its attachments or parts shall not exceed one fluid ounce. 4- Should there be a failure of the water metering device or the water supply, me feeding device shall automatically cease operating.tf 1 Annual Report (1947) Committee D-I9 (American Society for Texting Material*). . * Corrosion Handbook, edited by H. H. Uhlig (John Wiley & Sons, p. 27). * Discussion, Corrosion and Material Protection, May 1945, p. 2. fPrlfjnd TaAble on Organising the Classification of Industrial Waters, by W. C. Schroeder UToceedings, American Society for Testing Material*, VoL 44, 1944, p. 1057). . * Typical Water Analyses for Classification with Reference to Industrial Use, by W. D. Collins (Proceed tng*, American Society for Testing Materialt, Vol. 44. 1944, p. 1057). cornua irroceeo 1004 CHAPTER 43 1956 <3uide 9 A.S.T.M. Standard D-596--41 (American Society for Testing Materials). t Discussion on Preventing Solution of CO* in Condensates* by E. W. Guernsey (A.S.H.Y.E. Trans actions, Vol. 51,1945, p. 69). * Studies of the Mechanism of Solution of CO* in Condensates Formed in Steam Heating Systems of Buildings, by L. F. Collins (A.S.H.V.E. Transactions, Vol. 51, 1945, p. 39). The Analytical Control of Anti-Corrosion Water Treatment, by W. F. Langelier (Journal, American Water Works Association, VoL 28, 1936, p. 1500). CHAPTER 44 OWNING AND OPERATING COSTS 19Surface-Active Properties of Hexametaphosphate, by G. B. Hatch and Owen Bice (Industrial and Engineering Chemistry, Vol. 31, 1939, p. 51). u Threshold Treatment of Water Systems, by G. B. Hatch and Owen Rice (Industrial and Engineering Fixed Charges: Amortization, Interest, Taxes, Insurance, Rent; Maintenance Costs; Labor for Operation; Energy and Water Costs: Operating Refrigerating Chemistry, Vol. 37, 1954, p. 710). n Betz Handbook of Industrial Water Conditioning, Fourth Edition (W. H. & L. D. Beta Co.), M Equipment, Condenser Water, Heating u Cooling Water Problems in the New York Metropolitan Area, by Sidney Sussman (Industrial and Engi neering Chemistry, Vol. 44, Aug. 1952, p. 1740). 4$ THE total cost for the use of heating, ventilating, and air conditioning u slime Control in Cooling Equipment with Phenol Derivatives, by J. A. Holmes (Proceedings, Annual systems may be divided into two classifications. The first of these is Water Conference, Engineers' Society of Western Pennsylvania, 1944, p. 61). ' W the relatively fixed and unvarying expense of ownership, and the second it Tuberculation of as Affected by Bacteria, by H. G. Reddick and S. E. Linderman (Journal, Nera Ij England Water Works Association, VoL 46, 1932, No. 42). it Microbiological Anaerobic Corrosion of Steel Pipe Lines, by R. F. Hadley (The Oil and Gas Journal, is the variable and somewhat controllable expenditure for actual operation of the equipment. Owners and prospective purchasers of this equipment oip-i rM "Mi K| npo. *W, i September, 1939). u Refrigeration Data Book (American Society of Refrigerating Engineers, 1936, p. 404). is Cold Water Vacuum Deaeration, by S. T. Powell (Proceedings, Water Conference, Engineers' Society of Western Pennsylvania, 1945, p. 51). is Corrosion Control with Threshold Treatment, by G. B. Hatch and Owen Rice (Industrial and Engineer ing Chemistry, Vol. 32, 1940, p. 1572). Tests of Corrosion Inhibitors for Water Treatment in Air Conditioning Equipment, by James H. Wil son and E. C. Groesback (Research Paper 1305, National Bureau of Standards Journal of Research, Vol. n, 1940, p. 665). . The Control of Corrosion in Air-Conditioning Equipment by Chemical Methods, by C. M. Sterne (Pro ceedings, American Society for Testing Materials, Vol. 38, 1935, Part 2, p. 261). n Corrosion in Closed Recirculating Water Systems, by Sidney Sussman and James B. Fullman (Heating and Ventilating, October 1953, p. 77). n Corrosion--Causes and Prevention, by F. N. Speller (McGraw-Hill Book Co., 1951, pp. 805, 905, 910 and 912). . u Engineering Problems of Water Treatment, by L. F. Collins (Power Plant Engineering, Vol. 50, July 1946, p. 78-81, 120). u See p. 470 of Reference 19. .. Studies in The Detroit Edison Co. (Unpublished). n Preventing the Solution of CO* in Condensates by Venting of the Vapor Space of St^m Heating Equip ment, by D. ST McKinney, J. J. McGovern, C. W. Young and L. F. Collins (A.S.H.V.E. Transactions, Vol. 51, 1945, p. 53). *8 Corrosion in Steam Heating Systems, by Leo F. Collins and Everette L. Henderson (Heating, Piping and Air Conditioning, October 1939, p. 620). U.S. Patent 1,395,730. U. S. Patent 2,053,024. U.S. Patent 1,903,287. "Treating Steam Chemically to Reduce Return Line Corrosion, by A. A. Berk (Industry and Power, Vol. 53, Nov. 1947, p. 79). are particularly concerned with both since the actual expenditure is gen erally predicated upon the possible return on the investment resulting from increased patronage, greater efficiency on the part of the employees, meeting of .competition, or the improvement and maintenance of quality in a manufactured product. These costs may be grouped under four headings: (1) Fixed-Charges, (2) Maintenance Costs, (3) Labor for Opera tion, and (4) Energy and Water Costs. . FIXED CHARGES . Fixed charges are the annual expenses arising from the ownership of the installation,. including use of the owner's money, and protection of the equipment in the form of insurance. Such costs are usually unchanged from year to year regardless of whether the equipment is in or out of serv ice. Fixed charges may be grouped under five headings: (1) Amortization, (2) Interest, (3) Taxes, (4) Insurance, and (5) Rent. Amortization As air conditioning equipment becomes older, its ability or capacity to perform present and future service is reduced. Provision must be made for the owner to recover each year a portion of the initial value of the equipment as an expense to be charged against revenue, or to amortize the cost. This decrease in the value of property is usually determined by m Tests in The Detroit Edison Co. (Unpublished). 94 More Information Concerning Corrosion in Steam Heating Systems, by L. F. Collins (Proceedings, Water Conference, Engineers* Society of Western Pennsylvania, 1943, p. 37). u Rubber Linings and Coatings, by J. J. McNeil (Corrosion and Material Protection, March-April, 1947). i 99 Protection of Steel Bins from Corrosion, by J. V. Schaefer (Power Plant Engtneenng, Vol. 26, 1922, p. Ij 632). . .. 97 Some Notes on Corrosion of Cast-Iron Sectional Boilers, by E. R. Walters (The Institution of Heating and Ventilating Engineers, Preprint, 1944). 99 See p. 67 of Reference 2. > Soil Corrosion Studies, 1941, by K. H. Logan and M. Romanoff (National Bureau of Standard, Journal of Research, Vol. 33, 1944, p. 145). ` an accountant or engineer using some theoretical method and will depend upon (1) the total first cost, and (2) the amortization period. The total first cost of an installation is the actual capital expenditure required to buy and install the air conditioning, heating, or ventilating system ready for operation. It represents the first cost of the equipment combined with additional costs incurred because of the installation of the system. The first cost of air conditioning, heating, or ventilating systems includes the following: 49 Cathodic Protection of Steel Equipment Submerged in Water, by L. P. Sudrabin (Proceedings, Water Conference, Engineers' Society of Western Pennsylvania, 1944). 4i A discussion by D. W. Haering (See p. 66 of Reference 14). 41 Cyclohcxylamine and Dicyclohexylamine, by T. S. Carswell and H. L. Morrill (Industrial and Engi neering Chemistry, Vol. 29, 1937, p. 1247). . 49 Drinking Water Standards, etc. (Reprint No. 2440, Public Health Reports, Vol. 58, No. 3, January 15, 1943). 1. Heat producing equipment including boilers, burners, controls, etc. 2. Heat distributing equipment including direct radiation, piping, etc. 3. Air handling equipment including fans, air heaters, air conditioners, filters, controls, etc. . 4. Air distribution system including ducts, outlets, grilles, etc. 44 Discussion of Ref. 21, by R. M. Palmer. i f 49 Official Plumbing Code of the City of Detroit, Article V. i; "Private Communication from H. S. Jordan, A.W.W.A. . 5. Refrigerating equipment including piping, pumps, etc. 6. Water conservation devices including towers, evaporative condensers, etc. 1005 1006 ' E q u ip m e n t , T e m p e r a tu r e C o ntro ls, e tc T a b l e 1. C o s t D o l l a r s p e r T o n f o r a C o m p l e t e S y s t e m , I n c l u d in g H e a t in g a n d C/ o o l in g C o il s , F a n , D u c t s , R e f r ig e r a t io n _______________ ________ ' - _________ . g s n CHAPTER 44 CO 1956 Guide S3 2 52.00 50.00 48.00 46.00 44.00 42.00 40.00 PTCeoorowTleiron 190.00 155.00 . 120.00 90.00 60.00 A as g as BOOggOH 3 a |5 g os H a >. 1.55 1.43 1.38 1.33 1.30 1.28 1.25 1.23 1.17 1.14 = 1 ' Oo I- P er Sq Ft Floor K as 8 51 -Asi > W^- 775.00 730.00 690.00 664.00 650.00 641.00, 628.00 612.00 585.00 568.00 2.32 2.15 2.07 1.99 1,95 1.93 1.88 1.84 1.76 1.71 > a3 n oI? 8a 13,100 19,350 24,500 35,700 35,700 51.600 46.000 66.400 68,200 97.400 90.000 ; 128,200 110,000 156,800 129.000 ` 183.600 168.000 234.000 205,000 284.000 o t a l C o s t T T otal e ii sb,. 2ash" SB Ila H 6,250 11,200 15,900 20,400 29.200 38.200 46,800 54,600 66,000 79,000 8 e H 5. e a- fS S s .f.l J 11 1 t- S.s H % f-S -s- IS--a -"L>*8 to q.9 -jS.sg & U n it C osts 1.05 0.98 0.95 0.92 0.91 0.90 0.88 0.86 0.84 0.82 macs lO teg Oo &-<>! "a s| i | S' s - Its 5 as gc" HOS OiOC'f*N-HflOflONGNONOIOOO OCOOiO S!8a S ts-3.il- .Ssg aJltl P5 H 58 0a,0-aO-o-g9 gSo ^fik2o8 CO -- b afll *a* e D is tr ib uted ^8g-fa*aa ll||5?5 8,333 : 12.500 16,666 25.000 25.000 37.500 33.332 . 50,000 50.000 75.000 66,664 100,000 83.333 125.000 100.000 150.000 133,328 200.000 166,666 250,000 cu it 1 A ir A rea gi-alTs! SQFT n S-oSya-S** F loor BS - 2o S g5 B P$ 25 50 75 100 150 200 250 300 400 500 *' - c --r d Q j88QS83 S$oQ8.'J.T23S|SJS--332S' --EO_sso0_|>^29Oc>o E- "-^hO Q oSQ 8 Owning and Operating Costs 1007 7. Insulation of pipes, ducts and equipment. . 8. Building alterations, furring-in ducts and pipes, structural work, etc. To estimate the first cost of any system prior to installation, the best procedure is to determine the heating and cooling load, and then after thorough engineering study, select the type of system. The installed cost . of systems will vary widely, depending upon the type of equipment se lected, and the design of the distribution system, equipment and labor costs in the locality, demands for the particular installation, etc. A rea sonable approximate cost may be determined for a selected design in a given locality from the sum of the estimated unit costs of the component parts of the system. A reasonably precise estimate of the cost of the com ponents may be obtained from cost records of recent installations of a comparable design, or from quotations submitted by manufacturers and contractors. Approximate costs are given in Table 1 for mechanical air handling sys tems including heating and cooling coils for distributing I% cfm per square foot of floor area and refrigeration equipment based upon a requirement of one ton for every 333 sq ft of floor area. Different types of service de mand may change the floor area per ton of refrigeration and air volume per square foot between_wide limits and, consequently the table should be used with caution. Other first costs may be incurred because of the installation of the air conditioning or heating and ventilating system. These will include such items as electrical work, plumbing, miscellaneous piping, building altera tions, cutting, patching, furring-in of ducts or pipes, foundations, struc tural supports, remodeling or redecorating after installation, consulting engineer's fees, licenses, and permits. As these costs vary widely no ap proximations are practicable. Therefore, each case must be considered individually. If a quotation can be secured from a manufacturer or con tractor covering the complete job, it will usually include the items which have been mentioned. ' The length of the amortization period to be used depends upon (1) the type and remaining life of the building or space for which the system i& to be used; (2) the type of equipment to be employed as a part of the sys tem; (3) the character of the business; and (4) the lease or ownership conditions. Depreciation, due to deterioration or obsolescence, must be considered in arriving at the amortization period. Maintenance and deterioration usually have the effect of offsetting one or the other. If a long deprecia tion period is to be used, then the item for maintenance, repair, and the replacement of wearing parts must be greater than for a short deprecia tion period. In determining the length of the amortization period, the owner's ac counting practices will have considerable bearing upon the number of years used in the calculation. For taxation purposes, this period depends upon the use and the service to which the equipment is placed. At the present time indications are that varying interpretations on depreciation will be made by the Bureau of Internal Revenue. While most air conditioning equipment may be considered as having a normal, useful life of 20 years for depreciation purposes, no final value for depreciation should be deter mined without consultation with the owner's tax consultant or perhaps 1008 CHAPTER 44 1956 Guide referral to Schedule F which is issued by the Bureau of Internal Revenue and summarized in Table 2. / Interest The interest charged to the cost of ownership may be based upon the average interest rate for the period during which the first cost of the equip ment will be amortized. While some accountants do not include interest in the annual fixed charges and consider it a negligible item, the money invested in air conditioning, heating, or ventilating equipment, must be either borrowed or diverted from the owner's funds and converted to the Table 2. Probable Useful Life of Equipment* Life in Yeaba 1. Heat Producing Equipment . () Boilers............................................................................................................................................. () Stokers and burners.................................................................................................................. 2. Heat Distributing Equipment . (a) Piping--copper............................................................................................................................ (6) Piping--iron................................................................................................................................. (e) Radiation--concealed........................... /............^................................................................... (d) Radiation--direct...................................................................................................................... (e) Valves and specialties............................................................................................................. 3. Air Handling Equipment (o) Filters--automatic..........................................................................,,........................................ (6) Heating and cooling coils.................................................... ................................................... (e) Spray humidifiers and dehumidifiers............................................................................... (d)-Fans................................................................................................................................................. () Air conditioning units.............................................................................................................. (f) Motors.............................................................................................................................................. (g) Electrical starting equipment................................... .......................................................... (A) Pneumatic control systems................................................................................................... () Electric control systems.......................................................................................................... 4. Aib Distributing Equipment (o) Ductwork...................................................................................................................................... (b) Outlets, grilles............................................................................................................................. (c) Duct insulation........................................................................................................................... 5. Refrigerating Equipment () Centrifugal refrigerating machines.................................................................................... (&) Reciprocating refrigerating machines...............................................................'............. (c) Motors and starters................................................................................................................... (d) Piping--copper......................................................................................................................... (e) Piping--steel................................................................................................................................. (J) Pumps..............................................................;........................................................................... 6. Water Saving Devices (o) Evaporative condensers.................................................... -- ............................................. () Cooling towers................................................................................................................ ............ <c) Wells................................................................... '........................................................................... 20 20 same as bldg. ' 20 25 25 10 20 20 10 15 10 - 20 20 15 15 same as bldg. 20 15 ' 20 20 20 20 20 20 15 15 25 a Taken from U. S. Bureau of Internal Revenue Schedule of Probable Useful Life, revised 1942. purpose of making the installation. Whether it is borrowed or taken from surplus funds, the money that might have `been earned as interest is prop erly chargeable to the operation of the system. The formulas for computing interest and amortization are given in Ta ble 3. This table also serves as a check list for the various items to be considered in calculating the cost of ownership and operation. Taxes The taxes which may be charged to the property as a result of the im provement due to the installation of an air conditioning system will vary according to the practice of the official agencies levying property taxes. Owning and Operating Costs 1009 Insurance Insurance against losses by fire is ordinarily secured by irurpasing the building fire insurance coverage to cover all or part of the first cost of in stalling the air conditioning and other mechanical systems. Various types of extended coverage are available for protection against a number of other types of losses. ^. . . Boiler insurance may be extended to cover the air conditioning equip-' ment to protect against losses due to explosion, rupture of piping, and similar hazards. Since insurance rates vary widely depending upon the type of structure in which the equipment is located and the nature of the owner's business, the rates are usually set by rating organizations specializ-' Table 3. Owning and Operating Cost First Cost Annual Service Cost Cost of mechanical system. Other costs................................ First Cost (FC)--Total. Annual Fixed Charges Amortization--Depreciation..period Y years................................................ Interest rate i%.................................... Amortization and Depreciation FC _ . Y" ........................................... Interest: 1 X i X cost = ,.......... Taxes............... !.................................... Insurance................................................ Rent...............-......................................... Annual Fixed Charges: (Total)......................... ................. Annual Maintenance Costs Replacement. or servicing of air filters.......................................................... Outside Maintenance service............. Water Treatment...................................... Lubricating oil and grease.................... Painting for corrosion protection or other purposes........................................ -Replacement of worn parts................. Refrigerant.................................................. Wages of engineer or operator............ Annual Maintenance Cost-- - Total...'........................................... Electric Power Costs Coal.................................... .Oil--for boilers or Deisel engines.:. 'Steam . ' For Ventilation--reheaters. For Turbine driven equipment.!. For Engine driven equipment... . Sewera *. - Charges for discharging water into public drainage systems... Annual Service Costs: -- Total;.............................. .................. Summary Annual Fixed Charges........................ Annual Service Costs.......................... Annual Maintenance Costs.............. . Annual Owning and Operating Costs--Total......................................... ; ing in this work.. Exact figures on insurance cannot be determined with out consultation with the owner's underwriter. . ' Rent .- If the equipment under consideration's to be located in rented or leased quarters, or if additional space must be rented, such expense becomes a fixed charge. .............. MAINTENANCE COSTS Maintenance charges consist of expense for labor and material necessary to make repairs and replace parts, as well as cleaning, painting, inspection, etc. for the purpose of eliminating or minimizing the need for repairs. Generally, routine maintenance labor requirements will be the function of an operating engineer or staff. If the responsibility of this group may 1010 CHAPTER 44 1956 Guide extend to other facilities beyond the equipment being discussed here, it is important that only an equitable share of the group's time be charged to maintenance. . " . Extraordinary repairs are quite often handled by separate maintenance divisions and the expense charged back to air conditioning, heating, and ventilating! In other cases, all maintenance is handled'by outside service . firms and the cost considered as maintenance. These costs vary consider ably with factors such as the type of system and the proficiency of the installing and servicing organization. Therefore, any forecast of main tenance costs should include consideration of the equipment as a part of the engineering study. The charges should be based upon the entire period under study rather than the early years of operation when repairs may be expected to be at a minimum. . Various estimates of maintenance costs vary from 5 percent to 10 percent of the installation cost. Table 4 is based upon an average of 7| percent for about a 75-ton installation. This probably would apply to most in stallations using high quality equipment. The maintenance cost must be Table-4. Approximate Maintenance Cost fob Large Air Conditioning ....... Installations, Using High Quality Equipment* ------- . ----------- ... Dollars per (Ton)(Year) Total................ ................................ :------ '........................................... 1.07 0.40 0.11 ' 0.45 1.50 0.26 1.38 5.17 * Estimated for 1955. modified for size of job and quality of equipment. With lower cost equip ment, higher maintenance costs can be expected. The accounting practices of the owner and the rules of the Bureau of Internal Revenue affect the charges for major overhauling or complete re placement which may restore the capital value of certain equipment items. In these cases the expenditure may not necessarily be charged as mainte nance but will become a fixed charge spread over the remaining years of equipment life. Table No. 4 gives some approximate costs for maintaining large air conditioning installations using high quality equipment. , LABOR FOR OPERATION ',, In some cases with the installation of automatic equipment, operating labor may be non-existent, but where such labor is required, the cost is readily calculated. Where operators are. required, the expense is often considered maintenance, but since they may have other functions which are not properly charged to operation c5f the air conditioning, heating, or ventilating installations the charges should be properly allocated. The cost of experienced and competent operators is well justified in medium and larger plants by economies that can be achieved in maintenance and energy costs. ' Owning and Operating Costs 1011 ENERGY AND WATER COSTS Energy costs include the costs for power, water, steam, coal, oil, etc. consumed to operate the system. From the selected equipment and type of installation, it is possible to segregate the relatively constant power loads and the total brake horse power. Annual power cost can then be figured from the following formula: , . 0.746(bhp)RR annual, power cost -- ---------------------- . .. ... ... .. i) . .. (1) . Table 5. Equivalent Full Load Operating Hours of Refrigeration Equipment Used fob Summer Cooling May 15 to Oct. 15* . Application Hr Open . FOR Business Atlanta Boston Chicago Detroit Los New Angeles Oblban Barber Shops............................... Department Stores........................... Drug Stores..................................... .. Funeral Parlors.................................. Offices..................................................... Restaurant (Short Hour):........ .. Restaurant (Long Hour)......... Specialty Shops (5 A 10).............. Theaters--Continuous.................... Theaters--Neighborhood............... 1280 940 2100 600 940 1290 2100 1090 1500 900 1010 840 1630 440 870 970 1510 800 1010 640 650 560 ' 950 300 580 535 820 530 700 420 720 610 1060 330 620 620 030 590 750 450 730 610 1060 330 . 620 ' 620 930 690 750 450 680 1080 580 890 980 1790 810 470 580 900 570 1060 850 1690 660 860 720 1080 430 650 Application Hr Open FOR Business Nsrw Yore Phila delphia Oklahoma Cm St. Louis . Wash . INGTON D.C. Barber Shops.................... Department Stores....... Drug Stores........................... Funeral Parlors................... Offices...................................... Restaurant (Short Hour) Restaurant (Long Hour). Specialty Shops (5 & 10). Theaters--Continuous___ Thearers--Neighborhood. .1280 940 2100 600 940 1290 2100 1090 1500 900 830 700 1280 370 710 760 1170 670 850 500 860 720 1330 380 740 800 1210 690 870 620 1020 840 1650 440 880 . 980 1530 810 1020 650 890 .750 1420 . 400. 770 830 1300 720 910 550 940 780 1530 410 810 . 880 1400 750 950 580 * Modem Air Conditioning, Heating and Ventilating, by W. H. Carrier, R. B. Cherne and W. A. Grant Pitman Publishing Corp. 1940, p. 73). where : bhp = brake horsepower. H = annual operating hours. R = power rate, dollars per kwhr. v = motor efficiency (decimal). , In using Equation 1 it must be pointed out that the electric rate, R must reflect the proper combination of energy and demand rates. These vary widely between the utility companies, and sometimes the rate struc ture is such that it is largely the demand charge which determines the proper value of R to use in Equation 1. Operating Refrigerating Equipment In an air conditioning system the refrigerating equipment is usually the largest power consuming item to be considered. Also, the prediction 1012 CHAPTER 44 1956 Guide of operating cost is more difficult because the power required for summer cooling is affected by many factors of a variable nature. , Table 5 gives the equivalent full load operating hours of refrigerating equipment used for summer cooling for the period of May 15th to Octo ber 15th. This table was calculated from the following equation: H. = m(6 + cf) (2) where f, = equivalent full load operating hours of refrigeration equipment used for Bummer cooling during period May 15 to October 15. m = total hours during period May 15 to October 15 that the establishment is open for business. . 6 = fraction of maximum load from internal heat under average operating con ditions. c - fraction of maximum load which is due to external sources .at maximum . design conditions. . / = ratio of the number of hours for a particular city, when the outside wetbulb exceeds 65 F, during the period June 1 to October 1 to the total number of hours during that same period. Total hours are assumed as 8 hr per day period for barber shops, department stores, funeral parlors, offices, short hour restaurants, and specialty shops, and 12 hr per day period for drug stores, long hour restaurants, and theaters. It should be pointed out that certain southern cities may have seasons longer than the 5-month period indicated in Table 5. If it is desired to consider a longer season of operation, the ratio of full load operating hours to hours open for business is smaller; in other words, the refrigeration load factor is lower. This is true because the extra increment of days added will be a relatively light load, since the table already includes the more severe part of the season. The season electrical power cost for refrigerating equipment is then given by the following equation: 0.746 (bhpt) THe B season power costs = --*---------------------- * w where bhpt = brake horsepower per ton (see Fig. 1) for average load during period. (Due allowance should be made for poorer compressor efficiency at light load.) T = maximum refrigeration design load, tons. = equivalent full load refrigeration operating time, hours (from Table 5). R = power cost, including demand and energy charges, dollars per kwhr. i) = motor efficiency at average load (decimal). In considering refrigeration power consumption, it should be noted that the use of weather records for a specific year may lead to large inaccuracies in estimating operating costs, since there may be wide variations from year to year, and therefore, average yearly weather records should be used rather than those for any individual year. If the refrigeration compressor is steam turbine driven, the same general method can be followed, taking into account average water rate per brake horsepower-hour and the cost of steam. Owning and Operating Costs 1013 Condenser Water Condenser water cost estimates can also be based on equivalent full load operating hours of the refrigeration equipment. The varying temperature of the water at its source, as well as the temperature of the discarded water, must, however, be taken into account. In general, when water is pur chased, control is provided to hold the leaving water temperature (or condensing temperature) constant; and in such case the entering water temperature becomes the major variable, and the gallons per minute per ton can readily be calculated for any water temperature rise. CONDENSER TEMPERATURE, FAHRENHEIT DECREES Fig. 1. Typical Brake Horsepower Requirements for Refrigeration* * given are representative of dichlorodifluoromethane reciprocating machines of about 25 tons capacity in air conditioning applications. Requirements of smaller machines are usually higher, and for jarger machines may be lower. Values shown are for liquid refrigerant at condenser temperature (no sub- bubcooUng of the liquid may decrease these values approximately 0.3 percent to 0.5 percent for eacn rahrenheit degree the liquid temperature is lowered. The following equation for cost of condenser water is useful: where B = 0.060 aTHe C (4) B = cost of water for refrigeration during period, dollars. a = average gallons per (minute) (ton). T = tons of refrigeration at maximum design load. H. = equivalent full load refrigeration operating hours (Table 5). C = water cost, dollars per 1000 gal. . The average gallons per minute per ton must take into account the variable water temperature. When well water is used as a source, and entering and leaving temperatures are considered constant, the average gallons per minute per ton obviously are equal to the design gallons per minute per ton. However, when the source is river or lake water, its max imum seasonal temperature will generally be reached at the same time that 1014 CHAPTER 44 1956 Guide the refrigeration load factor is highest. The average gallons per minute per ton should be calculated from known or estimated water temperatures, be cause they vary through the season. Maximum water main temperatures are given in Chapter 35, but should always be verified locally. In lieu of this tedious work, the average gallons per (minute) (ton) may be taken as 80 percent of design gallons per (minute) (ton) with reasonable accuracy, for the condition of variable temperature of entering water obtained from rivers and lakes. Cooling towers and evaporative condensers virtually eliminate condens ing water charges since the windage and evaporation losses are seldom over - two or three percent of the water circulated. The savings in water consumed often times will not in itself justify the installation of water economizing equipment since the cost for pumping and the fixed or ownership charges may be in excess of the annual cost for once through condensing operation. If operating costs are to be the basis for selection, then fixed charges should be determined when studying ap plication of this equipment which usually has a shorter life than the other components. Usually the primary factors influencing, the installation of water con servation equipment are the lack of an adequate water supply or local regulations intended to conserve an existing water supply. Another factor influencing the installation of such equipment is the in creasing trend toward the enactment of taxes and service charges for con densing water wasted into city sewers. Certain municipalities will remit the sewer taxes or service charge if the condensing water is submetered and discharged into a storm sewer or used for process purposes. Heating The method of estimating fuel consumption to balance the building heat loss is given in Chapter 18. It is important to include the fuel required to heat ventilation air as used in ventilating and air conditioning systems. In estimating fuel consumption for ventilation air, the tendency of the conventional control systems to use less than the estimated quantity of out side air in cold weather should be considered in its effect in lowering fuel consumption. In addition, the heat required to accomplish winter humid ifying must not be neglected, when this feature is included in the equip ment. BIBLIOGRAPHY Modern Air Conditioning, Healing and Ventilating, by W. H. Carrier, R. E. Cherne, and W. A. Grant--Chapter IV (Pitman Publishing Corp., 1950). Predicting Operating Hours of Refrigeration Equipment Used in Air Condition ing, by W. A. Grant (Refrigerating Engineering, July, 1941). . Cost of Operation of Refrigeration Used for Air Conditioning, by R. E. Cherne {Refrigerating Engineering, December, 1943). ASRE Data Book, Applications Volume, 1954-55, Section VII, Chapter 45, Ta ble 3, 1949 Cost Data on Variety Chain Store Installations (American Society of Re frigerating Engineers). CHAPTER 45 INDUSTRIAL AIR CONDITIONING General Requirements for Manufacture, Processing and Preservation; Design Coni ditions and Application Data; Classification of Problems; Moisture Content and Regain; Conditioning and Drying; Chemical and Biochemical Reactions; Crystallization; Control for Machining, Polishing, and for Static Elec tricity Elimination; Laboratory Conditions; Calculations; Safe guarding Health and Maintaining Safety; Contaminant Con ' trol; Dilution Systems for Contaminants; Heat Storage; Radiation; Local Relief and Spot Cooling; Odors INDUSTRIAL air conditioning is concerned with the design and ap plication of equipment for obtaining proper conditions for (1) the manufacturing, processing, and preserving of material, equipment, and commodities; and (2) maintaining the health, safety. and efficiency of workers. This chapter includes a general discussion of these conditions, and also a comprehensive list of specific requirements for various types of products. GENERAL REQUIREMENTS FOR MANUFACTURE, PROCESSING AND PRESERVATION In order to apply air conditioning to industrial processes, the air condi tioning engineer must have a thorough understanding of the processing problems involved. Individual processes and machines are changing rap idly, and air conditions must be revised constantly to meet the new conditions. Table 1 lists the temperatures and relative humidities required for storage of certain commodities, and for manufacturing and processing of others. In some cases the temperatures and relative humidities fisted in Table 1 have no direct influence upon the product itself, but do affect the efficiency of employees, and in turn affect workmanship, uniformity and the cost of production. Sometimes, a compromise between the known optimum condition for processing and that required for worker comfort is unavoidable. Air conditioning for industrial processes is so extensive and involved that a detailed treatment is beyond the scope of this chapter. It is possible to cover only a few salient points of the general subject. In many in dustries the exact conditions to be maintained are determined and known only by the manufacturer who specifies them. In other industries there is a wide variance between manufacturers' requirements, depending on results desired, experience, and cost considerations. CLASSIFICATION OF PROBLEMS In general, any industrial air conditioning , problem in processing may be classified under one or more of the following: 1. Control of regain. 2. Control of rate of chemical reactions. 3. Control of rate of biochemical reactions. 4. Control of rate of crystallization. 5. Control of temperature for close tolerance machining and grinding. (Continued on page 1026.) 1015 1016 CHAPTER 45 1956 Guide TaBLB 1. . TEMPERATUBE8 AND HUMIDITIES APPLICABLE TO InDUSTKIAL AlB Conditioning* ' Process j. Temp. F R.H. % BAKERY 75-80 75-80 92-96 375-450 300-430 70-75 40-45 75-80 70-75 95-110 60-65 60-65 70 30-45 65-80 45-70 80 32-35 70-80 ' 40-50 70-75 80-85 80-85 65-70 65 50 60-65 65-65 80-85 50-65 55-65 35 40-50 methods of mixer cooling 1. 35-40 F water circulated through mixer jacket. 2. 15-25 F brine. 3. Direct expansion, refrigerant circulated through mixer jacket. 4. Cracked ice added to dough in mixer. 5. Cold air introduced into mixer during mixing process. 6. Cooled agitators are used in mixers. . . . MIXER LOAD CALCULATIONS . Refrigeration is required to remove: excess ingredient, if any; heat generated by the beating and mixing of dough; excess heat m mixer body; heat of hydration of flour and water; and heat absorbed by mixer from 'atmosphere during mixing process. . Additional factors are the design and speed of mixer, consistency, kind and mass of dough. Data Used in Calculations: 1 bbl. flour = 2001b Heat of hydration TM 6.5 Btu per lb of flour Specific heat of flour = 0.42 Btu per lb Water is 65% of weight of flour - Flour is 65% of baton ' Sponge is 60% of batch Total motor output is converted to heat in the mixer. In fermenting rooms recent practice is to use direct radiation for heating, atomising sprays for humidify* Ing, and gravity convection cooling surfaces for temperature reduction and dehumidifying thereby eliminat ing objectionable air currents. Proof box and bread cooler conditions vary slightly for dark bread. ' Cakes are sterilised by ultra-violet rays before wrapping. ' Process Temp. F R.H. % . BANANAS Ripening.................................................................................................. Storage ...................................................................................................... Shipping...................................... ;.......................................................... 68 60 54 to 56 90 to 95 85 to 90 85 to 90 Forced ripening is accomplished in 4 to 5 days while slow ripening is extended to 7 to 9 days with lower temperatures. . The green fruit with a pulp temperature of 56 F is placed in a ripening room at 68 F and 90 to 95 percent relative humidity until it begins to change color. The temperature is then lowered sharply to 60 F (or slightly less) dependent upon how quickly the fruit is to be moved. Typical refrigeration load for ripening room per carlot, with an 85 F ambient temperature: Insulation & electric load = 0.4 ton . Live load = 0.9 ton Pull down load (from 68 F to 60 F) => 1.6 ton Minimum carlot--20,000 lb which represents about 300 stems. . Since bananas give off minute quantities of ethylene and possibly other gases necessary for ripening, ventilation daring the early stages of ripening is undesirable. Cooling unit to be sized to provide a complete air change every 1| to 2 min. * Information in Table 1 is drawn from many sources. See bibliography at end of chapter. Industrial Air Conditioning 1017 Table 1. Temperatures and Humidities Applicable to Industrial Air Conditioning--(Continued) BANANAS (Contmued) Provide a heating system with a rated capacity to warm the fruit at a.rate of not less than 2 deg per hr Specific heat--0.9 Btu per (lb)(F deg). Approximate rate of evolution of heat by bananas when stored at temperatures indicated: Bananas at 54 F => 3,300 Btu (per ton) (24- hr), green at 68 F *= 8,360 Btu (per ton) (24 hr), turning at 68 F 9,240 Btu (per ton) (24 hr), ripening at 68 F -- 8,360 Btu (per ton) (24 hr). Room BREWING Temp. F R.H. % Ale........................................................................................................... * If wooden .tankage is used, otherwise humidity con trolled to prevent condensation on walls and ceiling. 30 to 32 32 to 34 32 to 34 40 to 46 40 to 45 55 32 to 35 55 to 62 60 max.. 75 mfn.* 75 Wort cooled to 47 F for lager, 54 to 59 F for ale, by evaporative cooling or use of double pipe or plate type coolers with counter flow of cooling medium. Fermentation produces 250 Btu per lb of sugar fermented. Lager fermented five days at 55 to 60 F, ale at 68 to 75 F, then cooled to storage temperature. . Bottled beer pasteurized by heating to 140 F in twenty minutes, maintaining temperature Sor eighteen minutes, then cooling to 80 F in twenty minutes. Canned beer requires one-third less time. Cold water, brine, direct expansion ammonia or propylene-glycol and water solutions may be used as the cooling medium. ' Process Temp.F CANDY (CHOCOLATE) R.H.% Enrobing Tempering room = Ventilation only 80 to 85 60 to 65 75 to 80 80 90 70 40 to 45 65 70 to 75 65 to 70 : 40 to 50 50 to 55 55 to 60 50 13 40 to 50 55 45 40 to 50 - Tunnel discharge room requires a dew point lower than the temperature of the product leaving the tunnel; ^ During the summer months the product is usually held in the tempering room for 24 hours prior to ship ping. . . Recovery of sugar fly in coating kettle rooms is accomplished with the use of cyclone type dust collecting devices. Supply air to coating kettles is maintained at 85 F dry-bulb and 61 F wet-bulb temperature. Bacteriological control is employed. .' Load calculations for hand dipping rooms are baaed on 100 lb of 90 F chocolate per (worker) (hr). Specific heat of chocolate = 0.30 to 0.56 Btu per (lb)(F deg). Latent heat of fusion = 34 to 40 Btu per (lb)(F deg). Freezing point -- . , Sweet milk chocolate = 86 F. - Dark chocolate = 90 to 92 F. .. . Process GANDY (HARD) Tunnel Packing Storage.. ....................................................................... V" .- tempering * (Ventilation only) Temp. F 76 to 80 76 to 80 55 65 to 75 65 to 75 R.H.% 30 to 40 40 to 45 40 to 45 45 to 50 1018 CHAPTER 45 1956 Guide Table 1. Temperatures and Humidities. Applicable to Industrial Air Conditioning--(Continued) ; CANDY (HARD) (Continued) Hot rooms used in the drying of jellies and gums are maintained at 120 to 150 F. A purge system using 100 percent outside air, bypassing the heating coil, is incorporated to produce rapid cooling of both the proouct and the room. '- Cold rooms for cooling marshmallows and cast creams are maintained at 75 to 80 F with a relative hu midity of 45 to 50 percent. Uniform air distribution is essential. Standard starch drying equipment is employed. - . Filtration of air is required. Process Manufacturing........ Rolling .. Striping...................... Breaking.................... Wrapping................... CHEWING GUM Temp. F 77 68 72 74 74 R.H.% - 33 63 53 47 58 Process CERAMICS Temp. F R.H. Decorating room..................................:................. ............................ 110 to 150 80 60 to 80 75 to 80 75 to 80 50 to 90 60 to 70 35 to 65 48 48 Relative humidity has no effect on the manufacture of the products. . , Temperature and humidity must be controlled in the decorating shop in the whiteware plants, and the decalcomania production room. ` ... Oust control is essential, and the dust count must be held down to four million particles per cubic foot due to the danger of silicosis. . Process - CEREAL Packaging................................................................................................ Temp. F. 75-80 R.H.% 45-60 , Process Temp. F R.H. % . CITRUS FRUIT * Prior to transcontinental shipment 58 84 to 88 60 86 to 88 Careful consideration must be given to air volumes, cur temperatures, humidity, ventilation and dis tribution. In regions where end rot is prevalent, it may be necessary to store grapefruit at temperatures of 32 to 34 F for a period not exceeding six weeks. * Lemon and grapefruit storage requires an air conditioning system to (1) maintain a constant temperature, (2) maintain a high relative humidity, (3) ventilate to maintain 0.1% CO* content, (4) obtain uniform air distribution, and (5) provide air washing or air filtration. Load calculations include (1) transmission losses, (2) internal load-fruit cooling and respiration, cooling fruit boxes, electric load, and people, and (3) outside air load--J2 cfm per carlot. . Specific heat--Btu per (lb) (F deg): Lemons 0.94, Grapefruit 0.87, Boxes 0.40 Temp. 32 40 60 80 HEAT OF EVOLUTION IN Btu Peb (tow) (24 hb) Lemons Grapefruit 580 810 2070 6200 460 1070 2770 4180 Industrial Air Conditioning 1019 Table 1. Temperatures and Humidities Applicable to Industrial Air Conditioning--(Continued) ....... ................... CITRUS FRUIT (Continued) Approximately 10 percent of the cooling load is considered as latent heat load. In a conventional system the air required is one cfm per storage box or 650 cfm per carload, resulting in a small temperature rise in the supply air making possible the required high humidities. In a combination system the air required is one cfm per sq ft of floor area or 300 cfm per carlot with the addition of auxiliary humidifying nozzles to maintain the required high humidities. Installation of metal ducts is required. Ductwork made of insulation board is sometimes preferred. . Process Temp. F ` 1 R.H. % DISTILLING Storage: -- Grain..................................................................................................... Liquid Yeast........................................................... .-........................ General Manufacturing:.................................................................... Aging....................'...............;.................................. ................................ 60 32 to 34 60 to 75 65 to 72 . 35 to 40 45 to 60 50 to 60 Mashing done at 150 to 155 F, then cooled to 64 to 68 F. Yeast culture fermented at 170 F, then cooled to 70 to 72 F. Yeast propagated at 150 to 154 F. Mash heated to 165 F and then cooled to 80 F-, then pitched with yeast and fermented at maximum tem perature of 85 F. Cooling for variousdistilling.. processes normally accomplished by use of river or well water depending on temperatures and availability. Low humidity and dust control important where grains are ground. Viscous filters preferred as mold spores and bacteria are trapped in the viscous film, preventing propaga tion. . Process ELECTRICAL PRODUCTS Electronics and X-Ray: Coil & transformer winding........................... Tube assembly......................................................... Electrical Instruments: . Manufacture and Laboratory............................... Thermostat assembly A calibration............... Bumidistat assembly A calibration................. Small Mechanisms: Close tolerance assembly.................................... Meter assembly and test.................................... Switchgear: Fuse and cutout assembly..................................... Capacitor winding..................................................... Paper storage............................................................... Conductor wrapping with yarn............................... Lightning arrestor assembly..................................... Thermal circuit breakers assembly and test.. . Water wheel generators: . Thrust runner lapping........................................... Rectifiers: Processing selenium and copper oxide plates. Dust control is essential in these processes 72 68 70 76 76 72 74 to 76 73 73 73 75 68 76 70 74 R.H.% 15 40 50 to 55 50 to 55 50 to 55 40 to 45 60 to 63 50 50 50 65 to 70 20 to 40 30 to 60 30 to 50 30 to 40 Process Temp. F FLOOR COVERING R.H.% linoleum: Stoving pjprpaa * grains per pound abs. hum. 90 to 100 80 160 to 250 20 to 28 60 gr* Some operations are stabilized against possibility of mold growth. Precise control of temperature and humidity is required for mechanical oxidizing of linseed oil. The rate of flow and the temperature of cooling water in the jacket surrounding the tank must be controlled. Air filtiation is recommended for the stoving ptocess- 1020 CHAPTER 45 1956 Guide Table 1. Temperatures and Humidities Applicable to Industrial Air Conditioning--(Continued) . Peooiss FOUNDRIES Temp.*F Mold making: w Winter design temp. 60 to 70 60 to 70 55 to 65 40 40 to 50 55 to 65 The charging room is usually unheated. In core making fume exhaust hoods are required for oven and for cooling areas adjacent to ovens. In mold making provide hoods at transfer points with wet collector dust removal system. Use 600 to 800 cfm per hood. Pouring rooms require two-speed powered roof ventilators. Design for minimum of two cfm per sq ft floor area at low speed. Shielding is required to control radiation from hot surfaces. Proper introduction of air will minimise preheat requirements. In shakeout room provide hoods with wet collector dust removal system. Exhaust 400 to 600 cfm per sq ft grate area. Roof ventilators are generally not effective. . In cleaning room provide hoods for grinders and cleaning equipment with dry cyclones or bag type col lectors. * Winter ventilation (preheated) is required to the extent of replacing exhausted air. Summer ventilation is usually supplemented by use of pedestal fans. .' . Spot coolers are sometimes used in larger installations. , Process I Temp. F . R.H. % FUR 110 18 to 20 40 to 50 55 to 65 Shock treatment, for eradication of any insect infestations, requires the lowering of the temperature to 18-20 F for 3 to 4 days, then raising it to 60-70 P for 2 days, then lowering it once again to 18-20 degrees for 2 days and raising it to the storage temperature. J . Furs remain pliable, oxidation is reduced and color and luster are preserved when stored at 40 to 50 F. Mold growth is prevalent with humidities above 80 percent, while hair splitting is common where hu midity is lower than 55 percent. ' Process LEATHER Temp. F R.H. % ' Drying: 70 120 50-60 75 45 40-60 After leather is moistened in preparation for rolling and stretching, it is placed in an atmosphere held at room temperature with a relative humidity of 95 percent. * Leather is usually stored in warehouses without temperature and humidity control. However, it is necessary to keep humidity below 85 percent to avoid mildew. Air filtration is recommended for toggle machines. . Process Temp. F LENSES (OPTICAL) ns 80 R.H. % 45 80 The air must be free of dust and temperature held constant. To acquire desired cleanliness of air a combination of impingement and electrostatic filters are used. Dust collectors are required for grinding operations. Industrial Air Conditioning 1021 Table 1. Tempebatures and Humidities Applicable to Industrial Air Conditioning--(Continued) Rooms Temp. F LIBRARIES AND MUSEUMS R.H. % 70-80 70-80 40-50 Spray type dehumidifiers used to eliminate 80s. Water treatment is wcntia.l to maintain between 8.5 and 9.0 pH. Reheat is usually needed for refrigeration cycle due to the low sensible heat load. In extremely cold weather a lower relative humidity is required to prevent condensation on walls. Positive high and low limit relative humidity controls are used. Do not locate water or steam piping where leakage can cause damage. Cheek Figures fear Cooling Estimates: Low 40 20 30 0.73 0.92 Medium 60 0.83 1.60 High 80 45 75 0.90 0.40 2.10 MALTING (BREWING) Steeped 24 to 72 hr in 45 to 65 F water* Germinated six days at 55 to 75 F. Kilned at temperatures of 120 to 175 F. MALTING (DISTILLING) Germinated twenty days at 63 F. Germination produces total heat of 16,000 Btu/bushel at varying rate depending upon grain and process. Process MATCHES Temp. F R.H. % 72 to 74 70 to 75 60 to 62 50 40 50 Water evaporated is 18 to 20 lb per million matches simultaneously with the setting of the glue. The match machine will turn out about 750,000 matches per hour. Process MUSHROOMS Temp. F R.H. % Stoner. ...................................................................................... 32 to 35 nearly sat. moderate 80 to 85 As spawn starts to grow, it is necessary to abruptly cool the mushroom house by 15 deg in a 12 hr period (approx.). Usually, this is the controlling factor in selection of refrigeration equipment, unless -there is portable equipment available for such a purpose. Ductwork is usually of wood, due to the deterioration of ferrous metals during sweating-out period. , Air filtration is essential in spawn rooms. Yisoous filters are preferred, as mold spores are trapped in the riscous film. Odorless oil should be used. Heat of emission is 4 Btu per (hr)Oaq ft of growing surface). 1022 CHAPTER 45 1956 Guide Table 1. Tempebatubes and Humidities Applicable to Industbial Aib ' Conditioning--(Continued) , Process Temp. F PAINT APPLICATION R.H.% Lacquers: Oil Paints 70-00 180-300 60-90 75 60 60 Spray booths to have 100 fpm face velocity. Make-up air must be preheated. Ovens must have air removed to keep fumes below explosive concentration. Equipment must be explosion-proof throughout Room or Process Temp. F R.H. % PHARMACEUTICAL Cough syrups.................................................... ........................... Small Animal rooms............................................................................ 70 to 80 75 to 80 80 70 to 80 80 90 75 to 80 70 80 78 to 80 80 78 75 80 80 . . 70 to 80 74 to 78 75 to 80 75 to 78 30 to 35 15 to 35 35 40 35 15 30 30 to 50 ; 40 5 to 10 35 40 to 50 35 to 40 50 35 20 to 30 .50 40 47 to 48 Gelatin capsules require varying relative humidities, depending upon size of capsule'. Moisture content should not exceed 0.25 gr per cu ft. Various kinds of gelatin require different temperatures. Penicillin incubation process requires holding temperature within J deg F, with temperatures and hu midity rigidly controlled during all manufacturing phases. - Ampule filling requires a 20 percent relative humidity when especially fine powders are used. ' Unooated tablet manufacturing requires accurate oontrol of temperature and relative; humidity, since low relative humidity causes formation of a hard outer layer, and high relative humidity retards drying at the proper rate. Liver extracts require a low relative humidity after they are dried. Temperatures higher than 80 F will cause the extracts to deteriorate. . Tablet coating requires the control of the temperatures of all ingredients and the temperature of air in troduced to coating pans. . Sterile conditions are essential in many pharmaceutical processes. Provide suitable air exhaust to re move surplus material from tablet compressing machine. Air filtration generally required, with positive air filtration in some areas. Animal Booms in Pharmaceutical Laboratories In the following tabulation each of the items mentioned is equivalent in metabolism to one man: Quantity Animal Weight Each 672 White Mice 21 g 110 Rats 200 g 73 Rats 400 g 70 Guinea Pigs 410 g 21 Rabbits 2.6 kg 16 Cats 3.0 kg 16 Monkeys 3.0 kg 5 Dogs 14.0 kg Dogs are generally the worst offenders as far as odor generation is concerned. Decontamination of exhaust air is recommended in populated areas. For good air quality conditions the following space per animal and total air circulation (all outdoor or in) should be provided: Animal cu ft cfm Mice 3 0.5 Rats 4 0.75 Guinea Pigs 6 1.0 Rabbits 10 1.9 Hamsters 8 1.5 Cate 35 10.0 Doga 150 28.0 Table 1. ATemperatures and Humidities Applicable to Industrial ib Conditioning--(Continued) ' Process Dressing Room ... Drying Room................................. Setting Room Developing Room Storage Room PHOTO STUDIO Temp. F ..................... ......................... ................................... ......................... 74 75-80 70 72 60 R.H. % 30-40 . , 70 65 60 45 ~ .-------------nouses ana dryer ho( Dust control is essential, and absolute filtration is required w some areas. Drying ..................... Cutting * Packing................. Film Base & Paper Storage... Coated Paper A Film Storage Safety Base Film Storage Nitrate Film Storage . taraZSL""* Positive dust In nitrate film area take proper precautions against fires. Recirculated air used for film drying is passed through activated carbon filters. Relative humidity for film storage should never exceed 60 percent with a minimum of 25 percent. Process Manufacturing areas: Thermo setting moulding compounds v/euopnane WraDDinff ' plastics ........... Absolute filtration is required in some areas. Collection and removal of dust and fumes is essential. Temp. F 75rn 80 R.H.% ---------------------------------------- - 25 to 30 45 to 65 ---------------- Hot Pressing (resin) Cold Pressing............ Process Incubator........ Brooder: 1st week.... 2nd week.. . Battery room: Starting........ Growing___ Egg storage ... _1 PLYWOOD Temp. F POULTRY RAISING 90 90 70-75 70-75 50-60 70 50-60 45-60 R.H. % 60 15 to 25 30-60 60 70-75 50-60 70-80 uMuuioin a temperature 10 /W ,>,, Z* ?~r. -- eosation on the esterior wells. T&s applies to hoi^n -*** oumuier montns, wtitle an atiemnt in _ Process | Temp. F PRECISION MACHININr. Spectregiaphic analysis.... cSLTsmbe8 4 8p<*ial Msemb* room............... feregungio?n *pa*r't"s m*ac&h>in.i.n..g....::::::::::::.:...:..:..:............................................................. 75-80 75-80 100 75 r r.h.% 45-50 60 40 45-60 1024 CHAPTER 45 1956 Guide Table 1. Temperatures and Humidities Applicable to Industrial Air Conditioning--(Continued) , Process ' j Temp. F RJL % PRECISION MACHINING (Continued) . Precision parts--honing..................................................................... 75 68-75 72 76 78 75-80 45-50 45-50 42-50 45 50 35-45 For product improvement and increased personnel efficiency some manufacturing areas are being pro vided with summer air conditioning. Where air conditioning is not provided, an ample supply of outdoor air and air motion are relied upon to provide acceptable working conditions. Low relative humidity is usually maintained to prevent corrosion. Temperature control within a narrow range is more important than temperature maintained.' Dust control is required wherever polishing operations occur. Air distribution is important to maintain constant conditions throughout the area. Process PRINTING Temp. F R.H. % Pressroom: Stock room: ' * 5 to 8% above pressroom b same as pressroom . 75-80 75-80 - 75-80 73-80 70-80 70-80 73-80 46-48 45-50 50-55 a 5-8% above pressroom b 45-50 50 Lithography requires constant humidity control of entire pressroom with paper conditioned 5 to 8 percent higher relative humidity at start. All printing requires conditioned paper otherwise it will not lie flat, with 40 to 45 percent R.H. low limit'to eliminate static electricity; and 60 percent R.H. high limit to prevent swelling of the rolls and slow ink drying. Temperature is not critical, but extremes should be avoided due to softening of the rolls at high temperature and improper ink distribution at low temperatures. Hoods must be provided for gas dryers, with solvent recovery recommended for all except job shops.Exhaust system with dust collectors incorporated is required for type and plate cleaning areas. Check use of gasoline and other solvents. Normal air cleaning is adequate. Air distribution must prevent drafts on paper in storage or process. Gas flame dryers impose unusual loads. Air from press and storage rooms should not be recirculated through office areas. Process Temp. F - REFRIGERATION EQUIPMENT Valve Manufacturing.. Compressor Assembly. Refrigerator Assembly. Testing.............................. 75 70 to 76 75 65 to 82 R.H. % 40 30 to 45 30 to 50 47 Process RUBBER DIPPED GOODS Laboratory (ASTM Standard).......................................................... 90 80 75-90 60-75 73.4 25-30 25-30 40-50 50 Solvents used in manufacturing processes are usually explosive and toxic, requiring positive ventilation. Volume manufacturers usually install a solvent recovery system. . Industrial Air Conditioning 1025 ATable 1. Temperatures and Humidities Applicable to Industrial ir Conditioning--(Continued) Process TEXTILES Temp. F R.H. % Cotton: Opening................................................................................... Picking.................................................................................................. Carding, Winter................................................................................ Carding, Summer..................................... ...................................... Carding, Summer.......................... ;.......................................... or Carding, Summer.......................................................................or . Drawing................................................................................................ Roving................................................................................................... Ring Spinning Conventional....................................... -......................................... Long Draft................................................................1.'................. Frame Spinning................................................................................ Spooling & Warping........................................................................ Weaving........................................................................................ . Cloth Room........................................................................................ Combing............................................................................................... Linen: Carding...................................................................................... Spinning............................................................................................... ' Weaving............................................................................ .................. Woolens: Pickers.................................................................................... Carding..................... ;.......................... ............................................... Spinning................. ..................................................... ;......... ........... Dressing................................................................................................ Weaving --____ Light goods........................................7........................................... . Overcoating (32 oz.)..................................................................... Drawing................................................................................................ Worsteds: Carding................................. ............................................... Combing............................................................................................... GilCng.................................................................................................... Top Storage........................................................................................ Drawing................................................................................................ Cap Spinning..................................................................................... Spooling <k Winding............................. ............... ......................... Weaving................................................................ :.............................. Finishing................................................................ .............................. Silk: Preparatory............................................... .....'........................ Weaving................................................................................................ Dressing................................................................................................ Spinning................................................................................................ Throwing.............................................................................................. Rayon: Spinning................................................................................... Throwing........ ..................................................................................... Weaving Regenerated.................................................................................... Acetate.................................................................................... ......... Spun rayon...................................................................................... Picking................................................................................................... Carding, roving, drawing.............................................................. Knitting Viscose or cuprammbnium...................................................... Acetate.............................................................................................. Laboratory (ASTM);............................................................. .-... Rayon synthetic fiber processing: ' Viscose Preparatory..................................................................................... Weaving............................................................................................ Celanese.......................................................................................... .... Preparatory..................................................................................... Weaving...................................... ............................................... Nylon . Preparatory..................................................................... .............. Weaving............................................................................................ 70-75 75 75-80 83 85 87 80 80 80-85 80-85 80-85 78-80 78-80 75 75 75-80 75-80 80 80-85 80-85 80-85 75-80 80-85 80-85 75 80-85 80-85 80-85 70-85 80-85 80-85 75 80 75 80 80 80 80 80 80-90 80 80 80 80 75-80 80-90 80-85 80-85 70 55-60 55-60 55 90 80 70 60 60 70 55 55-60 65 70-85 65-70 50-65 60 60 80 60 65-70 50-60 60 60 60-65 50-60 65 65-70 65-70 75-80 65 50-55 65-70 55-70 60 60-65 60-70 60-65 65-70 . 60 50-60 55-60 50-65 55-60 80 50-60 50-60 65 .60 65 80 80 80 80 80 80 ` 60 . 60 70 . 70-75 50-60 50-60 Cotton: Relative humidity maintained in ring spinning depends on staple, twist and whether leather aprons are used, for conveying long draft stock. Aprons readily absorb moisture causing cotton to stick when relative humidity is above 55 percent. - With conventional 3 or 4 roll spinning, relative humidity may be as high as 78 percent dependent upon draft, twist and staple. . Relative humidity carried in cotton weaving depends upon construction of the cloth. When automatic machines are to be tended and the warpsare heavily sised, it may be as high as 90 percent. Woolen.* In woolen spinning, the relative humidity maintained for mules is generally 55 percent, with conditions over frame spinning at 55 to 60 percent. Both types of spinning depend on the class of stock Pun, also the regain in the roving. . .. 1026 CHAPTER 45 1956 Guide Table 1. Temperatures and Humidities Applicable to Industrial Air Conditioning--(Concluded) / TEXTILES (Continued) Worsted! Top storage temperature depends on whether cellar long period conditioning at low temperature or quick conditioning at high temperature fa used. Weaving relative humidity depends upon staple, quality and construction. , .............. Filtration of air is essential. .. . Ration manufacture: The steeping room, where sheets of raw material are dipped in caustic soda then broken into a fine matted crumb, is held at 70 F and 55 percent relative humidity. Relative humidity is held down to prevent condensation on cold pipes and jackets. . In chum room, where sodium cellulose fa converted into cellulose xanthate, temperatures of 75 to 80 F are maintained while humidity control fa not important. Room temperatures are held below 85 F during the summer months. \_ ^ _ The crumb is dumped into aging tanks located in a room held at 73 F with no humidity control. For spinning operations it is desirable to limit the temperature to 90 F with a minimum relative humidity of 70 percent for the summer, while 70 percent and 75 F are desirable for the winter months. The storage room, where the material is held for later processing design conditions, are 85 F and 100 per cent relativehumidity. The material is washed, desulfurized, bleached and then washed again. It is then placed in a drieu where controlled conditions of 100 deg and 65 percent relative humidity are required to bring the rayon back to the proper regain. . . .- ` In the coning room, where winding machines place the rayon yarn on cones, temperature is held at a (unn'mnm Qf 80 F. Relative humidity is held at 55 percent. Process . Temp. F R.H. % TOBACCO Cigar and cigarette making............................... Softening...................... ;.......................................... Stemming and stripping.................................... Packing and shipping...............;............... Filler tobacco casing and conditioning........ Filler tobacco storage and preparation .... Wrapper tobacco storage and conditioning 70 to 75 90 75 to 85 74 to 78 75 78 75 55 to 65 85 to 88 70 to 75 65 75 70 75 In preparation for stripping, the tobacco undergoes a softening operation, whereby it is automatically heated, moistened and then cooled. * (s Control of moisture regain, and of chemical and biological reactions is required in tobacco processing. Exact temperature and humidity conditions maintained are usually trade secrets as they affect the fin- shed product. . _____________________________________ ' _________________ . (Continued from page 1015). " 6. Control of dew-point for protection of highly polished surfaces. 7. Control of humidity for static electricity elimination. 8. Control of conditions for material test laboratories. Moisture Content and Regain In the manufacture or processing of hygroscopic materials such as tex tiles, paper, wood, leather, tobacco and foodstuffs, the temperature and relative humidity of the air have a marked influence upon the rate of pro duction and upon the weight, strength, appearance, and general quality of the product. The moisture content of materials having a vegetable or animal origin, and to a lesser extent minerals in certain forms, comes to equilibrium with the moisture of the surrounding air. This moisture con tent is known as regain. Standards of regain are fixed in the trade, and are the fundamental basis for the control of certain physical qualities of the material during manufacture. . Manufacturing economy requires that the moisture content be main tained at a level favorable to rapid and satisfactory manipulation, a.nd to a minimum loss of material through breakage. A uniform condition is desirable in order that high speed machinery may be adjusted permanently for the desired production with a minimum loss from delays, wastage of raw material, and defective product. Moisture content refers to free mois ture (as in a sponge) and to hygroscopic moisture (which varies with at mospheric conditions). It is usually expressed as a percentage of the Industrial Air Conditioning 1027 total weight of material. Regain is more specific and refers only to hy groscopic moisture. It is expressed as a percentage of the bone-dry weight of material. For example, if a .sample of cloth weighing 100.0 g is dried to a bone-dry weight of 93.0 g, the loss in weight, or 7.0 g, represents the weight of moisture originally contained. This expressed as a per centage of the total weight (1O0.O g) gives the moisture content of 7 per cent. The regain, which is expressed as a percentage of the bone-dry weight, is (7.0/93.0) X 100 = 7.5 percent. The use of the term regain does not imply that the material as a whole has been completely dried out and has re-absorbed moisture. A basis for calculating the regain of textiles is obtained by drying, under standard conditions, a sample from the lot, and the dry weight thus ob tained is used in the calculations to determine the regain. Table 2 shows the regain or hygroscopic moisture content of several organic and inorganic materials when in equilibrium at a dry-bulb temper ature of 75 F and various relative humidities. The effect of temperature as compared to the relative humidity is comparatively unimportant, al though sudden changes in temperature cause a slight change in regain even when the relative humidity remains stationary. Changes in tem perature do, however, affect the rate of absorption or drying, although this property generally varies with the nature of the material, its t.hwVupgg and density. When hygroscopic materials absorb moisture from the surrounding air, they deliver to the air sensible heat equivalent to the latent heat released by the moisture to the material. This amount of heat should be included in the load estimate. Conditioning and Drying In general, the materials may be exposed to desirable humidities for treatment coincidentally with the manufacture or processing of the mate rials, or they may be treated separately in special enclosures. This latter treatment may be classified as conditioning or drying. The usual purpose of conditioning or drying is to establish a desired condition of moisture content and to regulate the physical properties of the material. When the final moisture content is lower than the initial one, the term drying is applied (See Chapter 47). If the final moisture content is to be higher, the process is termed conditioning. In the case of some textile products and tobacco, for example, drying and conditioning may be combined in one process for the dual purpose of removing undesirable moisture, and accurately regulating the final moisture content. Frequently, condition ing or drying is made a continuous process in which the material is con veyed through ah elongated compartment by suitable means, and subjected to various controlled atmospheric conditions. Control of Rate of Chemical Reactions A typical example of control of the rate of chemical reactions occurs in the manufacture of rayon. The pulp sheets are conditioned, cut to size, and passed through a mercerizing process. It is essential that, during this process, close control of both temperature and relative humidity should he maintained. The temperature controls the rate of reaction directly, while the relative humidity maintains a constant rate of evaporation from , the surface of the solution, and maintains a solution of known strength through out the mercerizing period. Another well-known example in this class is the drying of varnish which 1028 CHAPTER 45 1956 Guide Table 2. Regain of Hygroscopic Materials Moisture Content Expressed in Percent of Dry Weight of the Substance at Vjarious Relative Humidities--Temperature, 75 F ClassifiCATION Material Description Relative Humidity--Percent . Author ity 10 20 30 40 50 60 70 80 90 Cotton Cotton Natural Textile Fibers Cotton Wool Silk Linen Linen Jute ' Hemp Sea island-- roving American-- cloth Absorbent Australian me- rino--skein Raw chevennes --skein Table cloth Dry spun-- yarn Average ofsev- eral grades Manila and sisal--rope 2.5 3.7 4.6 5.5 6.6 7.9 9.5 11.5 14.1 Hartshome 2.6 3.7 4.4 5.2 5.9 6.8 8.1 10.0 14.3 Schloesing 4.8 9.0 12.5 15.7 18.5 20.8 22.8 24.3 25.8 Fuwa 4.7 7.0 8.9 10.8 12.8 14.9 17.2 19.9 23.4 Hart- shorne 3.2 5.5 6.9 8.0 8.9 10-2 11.9 14.3 18.8 Schloes-- ing 1.9 2.9 3.6 4.3 5.1 6.1 7.0 8.4 10.2 Atkinson 3.6 5.4 6.5 7.3 8.1 8.9- 9.8 11.2 13.8 Sommer 3.1 5.2 6.9 8.5 10.2 12.2 14.4 17.1 20.2 Storch 2.7 4.7 6.0 7.2 8.5 9.9 11.6 13.6 15.7 Fuwa Rayons Viscose Nitrocellulose Cupramo- Average skein Celulose Acetate 4.0 5.7 6.8 7.9 9.2 10.8 12.4 14.2 16.0 Robertson 0.8 1.1 1.4 1.9 2.4 3.0 3.6 4.3 5.3 Robertson Paper M. F. Newsprint H. M. F. Writing White Bond .Com. Ledger Kraft Wrapping % Wood pulp-- 24% ash Wood pulp-- 3% ash Rag--1% ash 75% rag--1% ash Coniferous 2.1 3.2 4.0 4.7 5.3 6.1 7.2 8.7 10.6 NBS 3.0 4.2 5.2 6.2 7.2 8.3 9.9 11.9 14.2 NBS 2.4 3.7 4.7 5.5 6.5 7.5 8.8 10.8 13.2 NBS 3.2 4.2 5.0 5.6 6.2 6.9 8.1 10.3 13.9 NBS 3.2 4.6 5.7 6.6 7.6 8.9 10.5 12.6 14.9 NBS Leather Misc. Organic Materials Catgut Glue Rubber Wood Soap Tobacco Sole oak-- tanned Racquet strings Hide Solid tires Timber (average) White Cigarette 5.0 8.5 11.2 13.6 16.0 18.3 20.6 24.0 29.2 Phelps 4.6 3.4 0.11 3.0 1.9 5.4 7.2 4.8 0.21 4.4 8.6 10.2 12.0 14.3 17.3 19.8 21.7 5.8 6.6 7.6 9.0 10.7 11.8 12.5 0.32 0.44 0.54 0.66 0.76 0.88 0.99 5.9 7.6 9.3 11.3 14.0 17.5 22.0 3.8 5.7 7.6 10.0 12.9 16.1 19.8 23.8 8.6 11.0 13.3 16.0 19.5 25.0 33.5 50.0 Fuwa Fuwa Fuwa Forest P. Lab. Fuwa Ford Foodstuffs White Bread Crackers Macaroni Flour Gelatin 0.5 1.7 3.1 4.5 6.2 8.5 11.1 14.5 19.0 Atkinson 2.1 2.8 3.3 3.9 5.0 6.5 8.3 10.9 14.9 Atkinson 5.1 7.4 8.8 10.2 11.7 13.7 16.2 19.0 22.1 Atkinson 2.6 4.1 (5.3 6.5 tf.O 9.9 12.4 15.4 19.1 Bailey 2.2 3.8 5.2 6.4 7.4 8.3 9.2 10.6 12.7 Atkinson 0.7 1.6 2.8 3.8 4.9 6.1 X.6 9.3 11.4 Atkinson Asbestos Fiber Misc. Inorganic Materials Coke Activated Charcoal Sulfuric Arid Finely divided 0.16 0.24 0.26 0.32 0.41 0.51 0.62 0.73 0.84 Fuwa 5.7 9.8 12.7 15.2 17.2 18.8 20.2 21.5 22.6 Fuwa 0.20 0.40 0.61 0.81 1.03 1.24 1.46 1.67 1.89 Selvig Steam activated HtSOt 7.1 14.3 22.8 26.2 28.3 29.2 30.0 31.1 32.7 Fuwa 33.0 41.0 47.5 52.5 57.0 61.5 67.0 73.5 82.5 Mason Industrial Air Conditioning 1029 is an oxidizing process dependent upon temperature. High relative hu midities have a retarding effect on the rate of oxidization at the surface, and allow the internal gases to escape freely as the chemical oxidizers cure the varnish from within. This produces a surface free from bubbles and a homogeneous film throughout. Desirable temperatures for drying varnish vary with the type. A relative humidity of 65 percent is beneficial for ob taining the best processing results. Control of Rate of Biochemical Reactions In the field of biochemical control, industrial air conditioning has been applied to many different and well-known products. All problems involv ing fermentation are classed under this heading. As biochemistry is a sub division of chemistry, subject to the same laws, the rate of reaction may be controlled by temperature. An example of this is the dough room of the modem bakery. Yeast develops best at a temperature of 80 F. A relative humidity of 70 percent is maintained to hold the surface of the dough open to allow the carbon dioxide gases formed by the fermentation to pass through and produce a loaf of bread, when baked, of even, fine texture without large voids. The curing of fruits, such as bananas and lemons, also comes under this classification. Bananas require a cycle of temperatures and relative hu midities for ripening. The starches in the pulp of the fruit must be changed and the skin cured and colored, after which the fruit is cooled to maintain as low a rate of metabolism as possible. Ideal storage conditions range between 56 and 60 F, with about 85 percent relative humidity, and ventilation at the rate of three or four air changes per hour. The curing of lemons is an entirely different problem. Bananas are cured for a quick market, while lemons are held for a future market. The process, therefore, varies in the temperature used. Temperatures from 54 to 59 F have been found to be best suited for this process. A high rela tive humidity of 84 to 88 percent is necessary to hold shrinkage to a mini mum, and, at the same time, develop the rind so it will be sufficiently tough to permit handling.. Tobacco from the field to the finished cigar, cigarette, plug or pipe tobacco, offers another interesting example of what may be done by indus trial air conditioning in the control of color, texture and flavor. In the processing of tobacco, control of moisture regain, and of chemical and bio chemical reactions, is involved, and only through close atmospheric control can the best quality of leaf be developed. Control of Rate of Crystallization The rate of cooling of a saturated solution determines the size of the crystals formed. Both dry- and wet-bulb temperatures are of importance, ae the one controls the rate of cooling, while the other, through evapora tion, changes the density of the solution. In the coating pans for pills, gum, and nuts, a heavy sugar solution is added to the tumbling mass. As the water evaporates, each separate piece is covered with crystals of sugar. A smooth, opaque coating is only accom plished by blowing into the kettle the proper amount of air at the right dry- and wet-bulb temperatures. If the cooling and drying are too slow, the coating will be rough and semi-translucent, and the appearance un sightly; if too fast, the coating will chip through to the interior. Only by balancing temperature, relative humidity, and volume of air to the sugar solution, can the proper rate be obtained and a perfect coating assured. 1030 CHAPTER 45 1956 Guide Control of Temperature for Close Machining Tolerances Where tolerances must be held within 2 or 3 ten-thousands of an inch, as in the manufacture of precision' instruments, tools, and high quality lenses, temperature variations may cause expansion and contraction of material to an extent that will seriously affect the quality of the work. This type of work usually requires close temperature control to assure accuracy and uniformity of the product. Usually the temperature level writh respect to the product is not as important as controlling the temperature within close limits. For . this reason, conditions are usually selected within the comfort range. Control of Dew-Point for Protection of Polished Surfaces In the manufacture of certain metal articles, the presence of finger prints, tarnish, or etching can not be tolerated in the finished article. If these articles are manufactured under conditions of effective tempera tures that will cause the.hands to perspire, an unsatisfactory product will result. The salt and acid contained in body perspiration, when deposited on the highly polished article, can show corrosion and rust within a few hours if examined under a microscope. .. . It is therefore important to maintain temperatures and relative humidi ties (dew-point) low enough to prevent sweating of the hands. In addi tion, the manufacture of polished surfaces usually requires a better-than- average job of air filtering to avoid abrasion of the surfaces. . Control of Humidity for Reduction of Static Electricity The presence of static electricity is often detrimental to the satisfactory and economical processing of many light materials, such as textile fibers, paper, etc. It is also extremely dangerous where explosive atmospheres or materials are present. Fortunately, this hazard is minimized by in creasing the relative humidity to at least 55 percent, if the material being processed is not damaged thereby. It must be borne in mind that for successful elimination, .the air that actually comes in contact with the material in the machine must be at a relative humidity of 55 percent or more. As some machines consume a great deal of power, which is converted directly into heat, the tempera ture in the machine may be considerably higher than the temperature adjacent to the machine where the relative humidity is normally measured. In such cases, the relative humidity in the machine will be appreciably lower than that elsewhere in the room, and it may therefore be neces-. sary to maintain a room relative humidity of 65 percent, or even more, to maintain the desired humidity. : Control of Conditions for Material Test Laboratories Laboratories having controlled conditions of temperature and humidity, are becoming more common, not only for the purposes of scientific re search, but also for routine testing and for quality production control. A control of temperature and humidity within fairly close plus or minus limits is usually required. Laboratories designed for scientific research may require control of conditions over a wide; range, whereas the routine testing laboratory or quality control laboratory will usually be designed to maintain the A.S.TM. Standard Conditions of 50 percent relative hu midity and 23 C (73.4 F) temperature. Industrial Air Conditioning 1031 CALCULATIONS The methods for determining the heating and cooling loads for the various industrial processes are similar to those outlined*in Chapters 12 and 13. Some factors affecting heating or cooling requirements are given in Table 1. Because of the large number of motors and heat producing units usually found in an industrial application, it is particularly important that operating allowances, for the latent and sensible heat loads, be defi nitely ascertained and used in the calculations to determine the total design load. GENERAL REQUIREMENTS FOR HEALTH, SAFETY AND EFFICIENCY Control of Atmospheric Contaminants Safeguarding the health and maintaining the safety and efficiency of workers, require control of dusts, fumes, smokes, mists, fogs, vapors, and gases, and control of the effective temperature, which includes tempera ture, humidity and motion of air about the worker. General ventilation may be relied upon in some cases to control ailcontaminants. Chapter 11 gives information on natural ventilation. If mechanical ventilation is to be used, Chapter 33, Fans; Chapter 31, Air Distribution; Chapter 32, Air Duct Design; Chapter 34, Air Cleaning; and Chapter 35, Spray Apparatus, furnish information on a broad range of industrial design conditions. Specialists in the field of industrial hygiene should be consulted in case of doubt concerning the presence of airborne industrial hazards to health. Chapter 8, Air Contaminants; Chapter 6, Physiological Principles; and Chapter 7, Air Conditioning in the Prevention and Treatment of Disease, will be of help in determining the atmospheric conditions which should be maintained around the worker. Local codes, ordinances, or state labor laws must likewise be observed, particularly for ventilation requirements for hazardous trades. Comfortable conditions are desirable because they are likely to increase the efficiency of woikeTs. For purposes of analysis, both sensible and latent heat should be included as contaminants of in dustrial atmospheres. A recent small scale survey has indicated that more than half of the air conditioning and ventilation installations in a typical industrial plant were concerned with removal of either sensible or latent heat as a source of air contamination. Contaminant Control Systems In general, systems for control of atmospheric contamination in industrial plants will be of three types: 1. Local exhaust systems will be indicated where the contamination originates at concentrated areas and is characterized by low or imperceptible air motion, or where the contaminant is a dust, mist or fume requiring a capture velocity exceeding 25 fpm. Design of this type system is discussed in Chapter 46, and will not be further treated in this chapter. , . 2. A system employing the dilution method will usually be indicated where the contamination originates at scattered points dispersed generally throughout the area. 3. Combination of local exhaust and dilution methods is often economical, since well designed exhaust hoods or openings, removing from the space that portion of the contamination load which is susceptible to such treatment, wifi often reduce greatly the air volumes required for dilution purposes. The choice of the type of system should be made on the basis of economic comparisons. 1032 CHAPTER 45 1956 Guide Design of Dilution Systems The first step in the design of a system employing the dilution method is to determine as exactly as possible the nature and extent of the contami nating load. This will often be difficult, and may require construction of pilot production models. Often, however, the required data will be avail able from production records, showing the weight or volume rate of loss of the contaminating agent to the atmosphere, or it may be estimated from parallel operations in other plants, or by applying experienced engi neering judgment. However obtained, the determination of the nature and magnitude of the contaminating load is an indispensable step in the proper design of the corrective system. Designs based on number of air changes per hour, or other rule-of-thumb methods, are hopelessly inade quate, and lead either to unsuccessful operation or to excessive and un necessarily high cost of installation. 1. Oases and Vapors. Once having established the nature and magnitude of the contamination load, it is rarely necessary to completely remove contaminating agents, from the atmosphere. For cases involving diffusible vapor or gas contami nants, maximum allowable concentrations (MAC) of commonly encountered gases and vapors have been established, and these data are tabulated in Chapter 8. From these data, and the previously established rate of addition of the contaminant to the space, the volume of air required to dilute the addition to a tolerable level can be calculated by the equation: V X 10` (MAC) - (SAC) (1) where Q = quantity of air circulated, cubic feet per minute. V = rate of generation of contaminant, cubic feet per minute. MAC = maximum allowable concentration, ppm by volume. SAC = concentration in supply air, ppm by volume. The rate of generation of the contaminating vapor will often be available as a weight or volume of liquid evaporated into the space per unit time. These may be converted to the units of Equation 1 by applying the principle that a pound-mol of a gas or vapor will occupy approximately 359 cu ft at standard pressure and tempera ture. Thus, cfm (vapor) W t + 460 X 359 X Mw 492 (2) where IF = rate of generation of contaminant, pounds of liquid solvent per minute. Af,, = molecular weight. t = air temperature, Fahrenheit. A special case occurs where local concentrations of solvent vapors at the breathing zone, resulting from concentrated sources of contamination, are intolerably higher than the average design concentration when using dilution methods. Data are available for calculations, but involve many assumptions regarding boundary condi tions, such as convection area and random air movement in the vicinity. 2. Dusts and Fumes. Maximum allowable concentration of various dusts, fumes and mists are also tabulated in Chapter 8. However, the dilution method as a means of treating particulate contaminating agents should be used with care, since the allowable air movement in spaces will ordinarily be lower than the capture velocity required for such particles. Exhausting at the source (see Chapter 46) will generally be the recommended treatment for these particulate contaminants. Industrial Air Conditioning 1033 3. Sensible Heat. Excessive sensible heat contamination is subject to treatment, similar to that for vapors, by the dilution method, the difference being that the rate of generation of the contaminant must be expressed in units of energy rather than volume or weight, and that the effect will be expressed as excessive tempera ture. In this case, the circulated air required will be: H (ti - to) X d X c where ' Q -- quantity of air circulated, cubic feet per minute. H = rate of generation of heat, Btu per minute. 11 = allowable temperature in the space, Fahrenheit. t0 = temperature of supply air, Fahrenheit. d = density of air in pounds per cubic foot. c = specific heat of air. (3) . . ' In some cases, such as ventilation systems not employing refrigeration, unusually large and uneconomical air quantities may be required when the desired or tolerable temperature ti approaches too closely the temperature to of the dilution air. This condition may sometimes be corrected by a combination of treatment by dilution and central exhaust, large sources of heat load being eliminated by exhaust through hoods at the source. Heat Storage in Structure ,. A special condition is sometimes encountered in large masonry struc tures when, due to the heat storage capacity and time lag of the structure, a prolonged period of hot weather may cause storage of such large quanti ties of heat in the structure that they continue to be a source of heat load after the outside weather has moderated. ': : In general, the solution to ventilation problems by the simple dilution method is limited to cases where a practical and economical equilibrium may be established between the maximum rate of generation of the con taminant distribution and cost of the air required for its removal. .; LOCAL RELIEF IN HOT AND HOT HUMID INDUSTRIAL ENVIRONMENTS In many areas in industrial buildings, it is not economically feasible to provide acceptable working conditions by the conventional means of venti lation and air conditioning. In such cases, local control of the environment (spot cooling) may be provided by means of shielding, air cooled booths; and spot cooling by means of air motion to provide a relatively cool area for the worker. These methods of local control may be used in conjunc tion with the natural or mechanical ventilation systems of the building to obtain the desired conditions for the worker, process or equipment. Spot cooling may be defined for the purposes of industrial environment control as heat relief of a local area within a larger space, independently of the general surroundings; a so-called oasis to provide conditions of relative comfort. Environmental Considerations In the preliminary design for hot environments the following should be considered: 1. Estimate the conditions of dry-bulb temperature, humidity, air motion, radiant 1034 CHAPTER 45 1956 Guide heat, effective temperature, and body heat balance. For buildings with low ceiling heights, the possibility that heated air may accumulate under the ceiling dr that the ceiling may absorb heat and become a radiant heating panel should be explored. (See Chaps. 5 and 24.) Such radiant heat loads may represent other heat loads con sidered but not dissipated to the outside. In addition to the pertinentchaptersin The Guide, the designer should refer to the articles by Small1, and Haines and Hatch1 on the subject of heat relief in industry, in evaluating the above factors. 2. Consider the practicability of reducing the heat loads imposed on the area and worker by: . a. Designing a building structure of adequate height, reducing the glass areaexposed to sun radiation, and utilizing heat-reflecting glass to shield the high intensity radiant sources. b. Changing the process in such manner as to provide lower operating tem peratures, thereby lowering the heat release to the area. c. Providing air cooled booths, possibly in conjunction with remote operating controls and visual aid devices, so that the hot areas may be avoided except for short exposures. d. Insulating all surfaces above 125 F in temperature where these surfaces are extensive enough to add appreciably to the ambient air temperature or mean radiant temperature. e. Using canopy hoods for hot equipment or providing local hoods at flues and doors of furnaces and similar hot equipment to reduce the heat dissipated to the work area. f. Shielding hot equipment (often used in conjunction with hoods) so as to reduce sources of radiant heat. 3. Give careful consideration to the type of clothing used by the workers.3 Light weight, open-weave fabrics in white, will frequently reduce the heat received by the worker to a small extent and will materially increase the workers' ability to lose heat by convection and evaporation. Also, reflective clothing can be provided, as noted hereinafter under the heading Radiation Shielding. - 4. Heat removed from exchangers, motors, generators and similar equipment can be used to temper necessary make-up air or to heat the building in the winter. This heat can be discharged outdoors in warm weather. Physiological Considerations , , In hot environments, the major physiological considerations are the de gree of activity of the occupants (this affects their metabolic rate or rate of heat production), the length of the period of activity and occupancy, and the ambient environmental factors (dry-btilb temperature, mean radiant temperature, humidity and air motion) which control the dissipation and reception of heat by the occupants. The subjects of work activity, and the correlated effective temperature limitations are covered in detail in Chapter 6. While effective temperature is a good index for hot areas (when mean radiant temperature effects are included), it must be realized that the allow able effective temperature which can be considered for a particular area must be dependent upon the degree of activity or work rate, and, conse quently, on the body heat balance. It is essential that body heat balance (metabolic rate plus heat received by the body, versus the heat dissipated by the body) be maintained except for relatively short exposures to hot environments. The subject is treated to some extent in Chap. 6, but Haines and Hatch1 have recently provided detailed data for estimating the maximum heat removal that can be expected for various environmental conditions. These data and calculations will also provide a means of estimating the maximum practical work rate for the area under considera tion, and will indicate the best means for providing relief for the worker. Too little information is available on the effect of air motion (draft) on human comfort. An understanding of the subject is of great importance in designing areas for local cooling. The comlort reaction to a draft is a function of (a) the physiological factors of work activity, position, age, sex, health and acclimatization; and (b) the environmental conditions of Industrial Air Conditioning 1035 temperature, air movement (over the body), and humidity. ' In hot at mospheres with high mean radiant temperatures and with high degrees of activity, a draft may be pleasant. In cooler conditions with less active work, a draft may be unpleasant. The body extremities are sensitive to draft arid the head, neck, and shoulders have been found particularly sensitive if sub jected to continued or excessive air movement in conjunction with low, humidity, sweating, and the impingement of low temperature air. The position of the worker is important. A person sitting, at rest, will produce less heat than a person standing, but because of the increased con vection and evaporation surface .exposed, the latter can lose more heat. Likewise, a person whose job requires him to stay at a fixed point, cannot be comfortable under the same conditions of air movement as a person who is moving about and exposed intermittently to the same air movement. . Yaglou4 among others, has pointed out that minimum body stress occurs with uniform cooling or heating over the body area. On the basis that the maximum work rate which can normally be maintained for an 8 hr day is 88 Btu per (sq ft) (hr) or 1700 Btu per hr for a surface area of 19.5 sq ft, the following stress factors may be used as guides in determining the design of local relief areas in hot industries. 1. The effective temperature should be maintained below 85 F, (See Ref. 2 also.) - 2. The relative humidity should not exceed 80 percent for normal temperatures nor should the wet bulb temperature exceed 83 F. (See Chap. 6, Fig. 9.) 3. The skin temperature should not exceed 95 F. 4. The pulse rate should not exceed 125 beats per minute (from an initial rate of 70 to 80). 5. The rectal temperature should not exceed 100 F (from an initial level of 98 to 99 F) . These are neither rigid nor exact limitations but do provide guides for design purposes. Generally, the designer will do well to stay reasonably below these limits. If the limits of paragraphs 3,4, and 5 are not exceeded within the first two hours of work they probably will not be exceeded during the work day provided there is no change in the rate of work or the en vironmental conditions. Radiation Shielding Shielding is an all-important method for reducing radiant heat exposures and the one technique that has been largely neglected in industry. A shield consists of a sheet of suitable material placed between a hot ob ject, such as a furnace, and its cooler surroundings. The closer it is placed to the hot. object, the greater the effective coverage. Hot surfaces emit infra-red waves which reach all objects within visible range. Essential to all shielding is the presence of an air space between the hot object and the shield to avoid conduction to the shield or a thermal short circuit. Radiation shields in the following forms are very effective: l' ^eets of reflective metal or insulating board, either semi-permanently at tached to the hot equipment (such as furnace buck stays) or arranged as semi-port able floor stands. 2. Aluminum foil faced cloth curtains which can be raised or lowered on spring rolls. ?' transparent shields, including heat reflecting tempered plate glass, reflective metal chain curtains and close mesh wire screens. These have lower efficiency than opaque shields described in preceding paragraphs 1 and 2. 4. Reflective garments, such as aprons, or in the form of a sandwich in cases of 1036 CHAPTER 45 1956 Guide continuous front and back exposures. For continuous wear the apron or sandwich width should be limited to 14 to 18 in. to assure adequate continuous side openings for air circulation and body ventilation. In addition gauntlets and face shields are particularly applicable to operations such as the pouring and casting of hot metal. Supply houses dealing in.safety clothing for industry offer suitably lightweight flame proofed foil-faced cotton drill or denim of excellent reflectivity. For repairs inside hot coke ovens and industrial furnaces, a complete suit is avail able using forced ventilation from a small blower or a compressed air source. These suits may be made of asbestos cloth, faced with a reflective metal in atomized form. If the shield is a good reflector, it will remain relatively cool in the presence of severe radiant heat. This reflectivity is a surface characteris tic. Hence a thin sheet is as effective as a thick one. Tinplate, stainless Fig. 1. Directional Outlets for Spot Cooling steel and ordinary flat or corrugated aluminum sheets are efficient and long-lived. Foil-faced plaster board, though less durable, obtains good reflectivity on one side. Spot Cooling By Air Motion The previous-paragraphs have described the steps which should be taken to reduce the heat load on the worker or the work area. When these fac tors have been considered and the heat load has been minimized to a practi cal degree, the designer may then resort to spot cooling by air motion to cool the worker himself. Such cooling may be provided by supplying air to the local areas or into suitable working enclosures or booths, or to venti lated coverall suits. The air supplied should be at such conditions of temperature, relative humidity and air motion as to provide a cooling effect on the worker. . These systems may also be used to provide make-up air for industrial exhaust systems, or to provide spot heating in the winter time. Such installations may be provided to improve the conditions around the Industrial Air Conditioning 1037 worker continuously, or else to provide-a relief area where-the worker will be in a cool zone intermittently. The designer should keep 'this in mind in selecting the proper method of air cooling. . Spot cooling may be provided by means qf recirculated (man-coolers),- direct outside, dehydrated, evaporatively cooled or mechanically cooled air, the solution depending upon the environmental-conditions existing in the working area, and the economic factors/ Generally, recirculated air will be effective only for areas of moderate heat release. Other systems will be required for areas having high heat release. . ' A great variety of outlets may be used for spot cooling. Several dif ferent types are shown by Fig. 1. In addition, several manufacturers make remotely adjustable ceiling diffusers'such that the air patterns may be altered from horizontal (parallel to the ceiling) to vertical, down'. A number of manufacturers also make double deflection grilles that are good for this service. Such outlets, can be provided in conjunction with an elbow type outlet and slip joint (see lower right diagram in Fig. 1) so as to provide directional discharge at any desired angle. The latter is very important to the worker because he may frequently want the air discharging into the space but may not want it to blow on him........ .. _ Perforated'panels may also be used for the supply air. Such panels have low induction characteristics and, used in conjunction with a booth could provide a low velocity blanket of air which should be effective for local heat relief, if supplied with cooled air. A booth would shield the worker from radiant heat and would permit effective cooling by means of the air supplied through the panel. The outlet air velocities used for spot cooling systems may vary from 50 to 2000 fpm. The higher velocities are frequently used but should be used with caution as noted hereafter. The data in Chap. 31 Air Distribution, should be studied in determining the required outlet velocities correspond ing to the desired velocity at the worker or the operating station. The following items are particularly important in designing spot cooling installations: 1. Where the personnel are engaged in work requiring little activity and where the exposure is continuous, the air velocity at the personnel should be low, approach ing the normal room velocities. The maximum velocity for such cases is sometimes given as 200 fpm. With greater worker activity, and where the worker is in the air current intermittently, higher velocities may be used. See Chap. 6, Effective Tem perature Chart, Fig. 9. 2. Generally the temperature of the air impinging on the worker should exceed 80 F. - 3. When the temperature of the air impinging on the worker exceeds the skin tem perature the critical point is approached where too high an air velocity will add to the body heat load and too low a velocity will fail to remove the sweat, and thus fail fPmvide the. maximum evaporative cooling for the existing conditions. (See 4. The outlets should be placed as close as practicable to the worker in order to take advantage of the lower discharge air temperature and the relatively larger core of air at the discharge air temperature. Installations in which the air is discharged ou*'^e^s 4 to 8 ft. from the worker are effective with small volumes of air, 200 to 1000 cfm. per outlet. At hot metal furnace working stations, 2000 to 3000 cfm. will be adequate. At greater distances more air is required due to the increased entrain ment of room air. However, the effect of the lower velocity air would be more toler able. 5. In selecting the outlets it should be kept in mind that large outlets have greater cooling effect because of the larger core of cool air. Slot outlets by comparison have high induction ratios, thus higher impinging temperature (at the worker). Per- 1038 CHAPTER 45 1956 Guide forated panels have low induction ratios and thus will provide lower impingement temperatures.* See Chap. 31. ' 6. Generally the outlets should have remote directional or volume control or, preferably, both. The worker should be able in most cases to operate the outlet damper, vanes or louvers (or to turn the outlet) from the floor by some convenient means. _ The damper control should provide at least 80 percent reduction in velocity. The workers may desire the full air velocity in hot weather, but may wish to reduce the velocity or to direct the air above the head zone in cold weather. 7. Generally the spot cooling air should be directed to the front and to the torso of the worker. If possible the air should not be directed at the head, shoulders or the back of the worker. 8. When providing spot cooling with evaporatively cooled air, be sure that con ditions of high humidity will not exist and cause conditions detrimental to the com fort of the personnel or cause rusting or other difficulty with the equipment or proc- Generally the evaporatively cooled air should be limited to 20 to 50 per cent of the total outside air circulated through the building. Odors There is little information available either on the rate of generation of common odors, or on the maximum concentration which would be tolerated by a majority of persons. Thus a quantitative specification covering systems for locker rooms and toilet rooms, or other applications where odors constitute the contaminant, is not now possible. Pending research in this important field, it is suggested that the data in Table 1, Chapter 6, showing the outside air supply required per person, at various socio economic levels, be used. . REFERENCES 1 Heat Relief in Industry, by Bartlett R. Small (Iron and Steel Engineers Maga zine, April, 1952). .T * Industrial Heat Exposures--Evaluation and Control, by George F. Haines, Jr. and Theodore Hatch (Healing and Ventilating, Nov. 1952, p. 94). 3 Physiology of Heal Regulation and the Science of Clothing, by L. H. Newburgh (W. B. Saunders Co.). . 4 Thermal Standards in Industry--C. P. Yaglou, American Public Health Asso ciation Yearbook, 1949. T _ _ . , ,,. * Temperature and Human Life--C.-E. A. Winslow and L. P. Herrington, Prince ton University Press. ," , * Private Discussion with G. L. Tuve and Alfred Koestel (Case Institute of tech nology, May 31, 1952). BIBLIOGRAPHY Peocessinq When Is Complete Air Conditioning of the Modem Factory Advisable? by H. A. Mosher (Heating Piping and Air Conditioning, June, 1945, p. 305 and July, 1945, p. 385). ' ., _T ... , , Air Conditioning Design Conditions for Various Industries, by N. N. Wolpert (Heating and Ventilating, May 1949, p. 70; June 1949, p. 73; July 1949, p. 79; Aug. 1949, p. 102). . .. ,, -m i * Air Conditioning Design Data for Commercial Applications, by N. W. Wolpert (Heating and Ventilating, Feb. 1950, p. 68). . ASRE Data Book 1950 (American Society of Refrigerating Engineers). Refrigeration of Oranges in California, by H. M. Hendrikson and J. R. MacRul, Refrigerating Engineering Application Data, No. 17-R (American Society of Refriger ating Engineers). .... .. _ Refrigeration of Lemons and Grapefruit, by H. M. Hendnkson and J. R. MacKill, Refrigerating Engineering Application Data No. 18-R (American Society of Re frigerating Engineers). ,,_ Air Conditioning in the Bakery, by W. L. Fleisher (A.S.H.V.E. Transactions, Vol.37,1931,p. 141). Industrial Air Conditioning 1039 . Air Condition the Bakery Throughout, by W. W. Reece (Heating, Piping and Air Conditioning, August, 1936, p. 419). The Air Conditioning of Processes in the Bread Bakery, by H. R. Gable (A.S.H. V.E. Journal Section, Heating, Piping and Air Conditioning, October 1947 p. 107) Air Conditioning in Candy Manufacture, by H. C. Hoffmann (Section 39, Refriger ating Engineering Application Data, Refrigerating Engineering, April, 1947). Proper Air Conditions for the Manufacturing of Confections, by A. E. Stacey, Jr. (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, October" 1937, p. 640). . Air Conditioning for Sausage Manufacturing Plants, by M. G. Harbula (A.S.H.V.E. Transactions, Vol. 28, 1922, p. 343). Relation of Air Conditions to Tobacco Curing, by J. Johnson and W. B. Ogden (Wisconsin Agricultural Research Bureau 110:1-48, 1931). Heating, Air Conditioning and Insulation for Penicillin Production, by J. C. Siegesmund (Heating, Piping and Air Conditioning, August, 1944, p. 475). Air Conditioning in Textile Mills, Research Department Technical Report, Textile Workers Union of America, C.I.O. Air Conditioning for Textile Plants Making and Using Synthetic Yarns, by L. L. Lewis (Rayon Textile Monthly, July, August, September, 1930). Refrigeration for Textile Mill Air Conditioning, by P. L. Davidson (Heating and Ventilating, May, 1947, p. 57). . u ?,urS,au Standards Studies Determine Press Room Conditioning Requirements, by C. G. Weber (Heating, Piping and Air Conditioning, March, 1936, p. 137). Humidity in the Pressroom (Heating and Ventilating, May, 1932, p. 35). Dehumidifying with Gas in a Printing Plant (Heating and Ventilating, May, 1935, p. 31). .* Air Conditioning the Newspaper Plant, by R. T. Williams (Heating and Ventilat ing, September, 1937, p. 63). Air Conditioning in the Paper Industry (Heating and Ventilating, October, 1935, p. 23). ^ Air Conditioning Requirements of Multicolor Offset Printing, by C. G. Weber (Refrigerating Engineering, December, 1936, p. 6). , . Reactions of Lithographic Papers to Variations in Humidity and Temperature by C. G. Weber and L. W. Snyder (U. S. Bureau of Standards Journal of Research' January,1934). . J' ' The Treatment of Offset Papers for Optimum Register, by C. G. Weber and M. N. V Geib (U. S. Bureau of Standards Journal of Research, February, 1936). Silica Gel Air Conditioning System Serves Rotogravure Printing Plant, by H. E. Ryerson (Heating, Piping and. Air Conditioning, August; 1937, p. 497). Air Conditioning for Clothing Research Laboratory (Healing and Ventilating July, 1943, p. 69). - Befrigeration Insures Quality of Clothing for the Army, by A. J. Mallinckrodt (Healing and Ventilating, March, 1944, p. 79). Controlled Air Supply for Supercharger, Carburetor and Engine Testing, by C. S. Leopold (Refrigerating Engineering, August, 1943, p. 85). Close Machine Tolerances Possible Through Temperature Control, by R. P. Dewey (Heating and Ventilating, April, 1944, p. 60). . Moisture Control by Liquid Absorption Offers a Useful Air Conditioning Tool, by F. M. Johnson (Heating, Piping and Air Conditioning, December, 1938, p. 782). Air Processing Needs of Plywood Plane Parts, by F. O. Jordan (Heating and Ven tilating. April, 1944, p. 67). The Engineering Control of Some Solvent Hazards in War Industries, by S. C. Rothman (A.S.H.V.E. Transactions, Vol. 50,1944, p. 319). . Air Conditioning as Applied in Theatres and Film Laboratories, by D. C. Lindsay (Transactions Society of Motion Picture Engineers, April, 1927, Vol. XI, No. 30 p. 335-365). Industrial Air Conditioning, by F. F. Stevenson (Heating, Piping and Air Condi tioning, May, 1948, p. 100; June, 1948, p. 94; and Jack F. Salsburg, July, 1948, p. 88, and Oct. 1948, p. 93). v' Industrial Air Conditioning, by Charles S. Cave (Industry and Power, July 1945 P- 67; Sept. 1945, p. 57). , . Reducing Heat Loads in Industrial Air Conditioning, by L. R. St. Onge (Refrigeratihg Engineering, January 1946, p. 35). Air, Light, and Sound Controlled in Western Electric's New Plant (Heating'Piping and Air Conditioning, Nov. 1948, p. 79). New IBM Plant Addition, Poughkeepsie, N. Y., by J. T. Browne (Heating, Piping and Air Conditioning, Jan. 1949, p. 111). 1040 CHAPTER 45 1956 Guide Photo Studios Need Conditioning fori Both Processing and Comfort, by E. E. Herbacek (Beating, Piping and Air Conditioning, June, 1949, p. 85). .i Foundry Ventilation; by Jim Black and Lester Avery (Heating, Piping and Air Conditioning, March, p. 71, April, p. 78, and May, p. 89,1947). Dust Control for Foundries, by B. F. Postman (Heeding and Ventilating, Dec. 1948, p. 65: Jan. 1949, p. 78). Foundry Cuts Its Dust (Editorial, Heating and Ventilating, Feb. 1949, p. 85). Fog Removals in Industrial Plants, by R. C. Soronen (Heating, Piping and Air Conditioning, April, 1949, p.72). ' Air Conditioning Crane Cabs, by R. D. Darrah (Refrigerating Engineering, May, 1949 p. 440). . Air-Conditioned Crane Cabs, by B. R. Small (Industrial Hygiene Foundation, Pre ventive Engineering Series, Bulletin No. 4,1947). Health, Safety and Efficiency . Lectures, The Inservice Training Course in Environmental Controls for Industrial Processes, University of Michigan School of Public Health, 1946: Environmental Controls in Industrial Health, by R. R. Sayers; Principles of Industrial Process Ventilation, by W. N. Witheridge; The Selection and Maintenance of Equipment for Process Control, by R. P. Warren; Environmental Control of Industrial Processes as Affected by Foundry Lay-out, by John Linabury; Foundry Ventilation, by J. M. Kane; Control of Welding Hazards, by W. C. L. Hemeon; Environmental Control of the Metal Cleaning Processes, by F. A. Patty; Painting, by T. F._Mooney; Health Hazards in the Electroplating Industry, by William Blum; Industrial Housekeeping and Sanitation, by John Soet. . _ Air Sanitation and Industrial Ventilation, by W. N. Witheridge, Detroit, 1945. An Investigation of the Bacterial Contamination of the Air of Textile Mills with Special Reference to the influence of Artificial Humidification, by W.F. Wells and E. C. Riley (The Journal of Industrial Hygiene and Toxicology, Vol. 19, No. 10, De cember, 1937). ... _ ,, . . T , T7 Industrial Cooling as a Production Aid, by J. Partington, Jr. (Heating and Ven tilating, April, 1944, p. 47). . , . . , . ,, ,, ,. c XI industrial Exhaust Ventilation in Industrial Hygiene,-by A. D. Brandt )A.b.ri. V.E. Transactions, Vol. 50,1944, p. 331). m Control of Industrial Atmospheres, by W. N. Witheridge (A.S.H.V.E. Transac tions, Vol. 51,1945, p. 227). .. Mine Ventilation and its Relation to Health and Safety, by D. Harrington (A.8.H.V.E.Transactions, Vol. 51,1945,p.243). ,,- w Ventilation Requirements for Industrial Solvents, by W. C. L. Hemeon (Healing and Ventilating, December, 1945, p. 95, January, p. 69, March, p. 82, and April, p. 79 1946). .... 'Guides for Industrial Ventilation, by Allen D. Brandt {Heating and Ventilating, ^Industrial Dust Explosions, by Hylton R. Brown {Heating and Ventilating, March, ^Supply*Air in Plant Ventilation, by J. B. Skinner and William M. Pierce (Heating and Ventilating, May, 1946, p. 57). . . ,, . ,, , What Air Conditions Make for Comfort in Industry?, by H. A. Mosher (Healing, Piping, and Air Conditioning, April, 1946, p. 106). , Air Conditioning Requirements for Workers m Factories, by H. A. Mosher (Heat ing, Piping and Air Conditioning, August, 1946, p. 82). . ... Hot Weather Limits Hard Work. (Brief summary of investigation done for Army Quartermaster Corps, by Department of Physiology, Medical School, University of Indiana. Healing and Ventilating, August, 1947, p. 110). . Methods Used in Determining the Health Hazards Arising from the Inhalation ol Various Chemicals, by Francis F. Heyroth (A.S.H.V.E, Transactions, Vol. 53,1947, ^ Air Recirculation from Exhaust Systems, by John M. Kane (Heating and Ventilat ing, April, 1947, p. 75). ,,, . ,, ,, ,, ,. Should Air Be Recirculated from Industrial Exhaust Systems? by Allen D. Brandt (Heating, Piping and Air Conditioning, August, 1947, p. 69). Dehumidification Methods and Applications, by Jphn Everetts, Jr. (A.b.H.V.B. Transactions, Vol. 53,1947, p. 91). . . n ,,, w Rating Dynamic Dehumidification Equipment, by E. R. Queer and E. it. McLaughlin (A.S.H.V.E. Transactions, Vol. 53,1947, p. 101). CHAPTER 46 INDUSTRIAL EXHAUST SYSTEMS Elements of Exhaust Systems, Hoods or Enclosures, Capture Velocities, Air Volume, Duct System Design, Calculations, Construction of System, Materials, Details, Air Flow Producing Equipment, Air Cleaning ' Equipment, Make-Up Air, Maintenance of Performance, Materials for Corrosion Resistance IN industrial plants, some type of exhaust system designed to collect and remove dusts, fumes, mists, vapors, and gases is installed to protect,health and safety of industrial personnel, promote worker efficiency, salvage usable material, or improve plant housekeeping. This chapter will not include consideration of systems similar in design, but used to convey heavy loadings (100 or more grains per cu ft) of materials. Definitions of various air con taminants, their particle sizes, maximum allowable concentrations, and upper and lower explosion limits are included in Chapter 8, Air Con taminants. Exhaust systems are extensively used for control of contaminants from: 1. Mechanical cutting and abrading operations including abrasive blasting and rock cutting. 2. Fuel burning and exhaust gas producing operations. 3. Molten materials handling operations. 4. Welding, burning, and soldering operations. 5. Fiber handling operations. ; .. 6. Volatile and gaseous material handling operations. 7. Chemical processes. Local exhaust systems should be considered whenever possible rather than general ventilation methods which allow contaminants to be dispersed within the workroom. More positive control, great reduction in exhaust volume handled, and reduced cost of air cleaning equipment will result. ELEMENTS OF EXHAUST SYSTEMS An exhaust system will consist of (1) hoods or enclosures at all sources of air contamination, (2) branch and main ducts through which an air stream trans ports the contaminant to air cleaning device or to the outside atmosphere, (3) air moving equipment to produce required air flow into hoods or en closures, and (4) air cleaning equipment when required. See Chapter 34, Part II, for discussion of types, applications, and principles of operation. HOODS OR ENCLOSURES11010 Basically, hood design requires sufficient knowledge of a process or opera tion so the most effective hood or enclosure can be installed to provide mini mum exhaust volumes for effective contaminant control. The more com plete the enclosure, the more economical and effective will be the installation. Many designers develop their hoods by mentally enclosing the operation completely and then providing access and. working openings as indicated. From this complete enclosure concept are developed the familiar hood shapes like booths, side or downdraft hoods (with or without side shields). All 1041 1042 CHAPTER 46 1956 Guide openings are kept to a minimum size and are placed away from the natural path of the contaminant travel wherever possible. Inspection and/main tenance openings are provided with doors whenever practicable. Capture Velocities and Air Volume Exhausted Only after the hood design has been determined can exhaust volume requirements be calculated. With enclosures, volumes are calculated from the known open area of the hood and the selection of the capture or indraft velocity sufficient to .prevent outward escapement. Where enclosure of the process is impracticable, the air flow pattern in front of the hood must be such that selected capture velocities will be maintained in the area of generation, conveying the contaminant to the hood opening. Usual-capture velocities for typical operations are listed in Table 1 and Table 1. Minimum Air Velocities Required at Point of Origin to Capture , Contaminant Effectively .Condition of Generation of Contaminant Minimum Caftube Velocity, FPM Released without- no ticeable movement Released with low veloc ity 50-100 100-200 Active generation 200-500 Released with great force 500-2000 ' Process Evaporation of vapors, exhaust from pick ling, washing, degreasing, plating, weld ing, etc. , ,. . Paint spraying in booth; inspection, sort ing, weighing, packaging, low speed (less than 200 fpm) conveyor transfer points, blending, mixing, barrel filling. Foundry shakeout, high speed (over 200 fpm) conveyor transfer points, crushers, screens. Grinding, tumbling mills, abrasive cleaning. refer in the case of remote hoods to the air movement required at the zone of air contaminant generation. Required capture velocities for any opera tion will vary with the magnitude of the air volume handled, with uncon trolled air movement in the area, and oftentimes with the location of the process or operation and size of the workroom. Larger remote hoods ex hausting large air volumes will provide effective control at lower maintained capture velocities than in the case of small remote hoods handling lower exhaust volumes. A hood at one end of a small narrow room with air supply at opposite end will provide control with lower capture velocities than that required from the same hood in a large room where no perceptible air flow will be obtained except in the immediate area of the hood. . The method for determining, approximately, the quantity of air that must be exhausted from an unobstructed hood, without flanges, to produce these capture velocities at the point of origin, is given in Equation 1: Q = V(10A* + A) (1) where . Q = quantity of air exhausted, cubic feet per minute. V = air velocity in feet per minute at X distance in feetfrom the hood and on the centerline of the hood. X = distance in feet, along the hood centerline, from the face of the hood to the point where the air velocity is V feet per minute. A = area in square feet of the hood opening. Industrial Exhaust Systems 1043 Eig. 1 shows lines of equal velocities (velocity contours) for a rectangular hood opening with a side ratio of one-half. The velocities are expressed as percentages of the velocity at the opening. Studies have established the principle of similarity of contours which states that the positions of the ve locity contours for any hood (when the contours are expressed in terms of the average velocity at the hood opening) are purely functions of the shape of the hood. Extensive studies2-11 12 have revealed variations in values of such velocity contours for long narrow slots and for hoods with one or more planes shielded against air flow.' . For smaller hoods, flanges which are usually 3 to 6 in. wide surround ing the hood opening usually will improve the air flow in front of the hood Velocity at the Opening and will reduce the air volume required to provide desired capture velocity by as much as 25 percent. Special Exhaust Requirements It is important to note that certain operations may require exhaust volumes in excess of the quantities based on design data from Table 1 and Equation 1. Typical reasons for increased ventilation rates include: , ' Induced air flow caused from falling granular material in large quantities through considerable height, or from internal rotating parts like some types of crushers, knives, macerators. 2. Induced air flow caused by the thermal or stack effect from sources of ex treme heat. 1044 aa H .0 b63. PS O 5 95 0 sH Pi s i 3 "a Is 3 73 M 0 au *J If 'a e O > u ~0 ^TJ * CHAPTER 46 i 0 .3 n *5 *,Q5 -s^ a ?l 1 > i b Mia 0a H 2cC*O,,0 a 20 0 -* 0 g 59 ** S| Is ITT a b l e 2 . A G u i d e t o V e n t i l a t i o n R a t e s f o r y p ic a l n d u s t r i a l E q u ip m e n t . Slate or L o ca l R egulations Should be Consulted and Followed Where H ig h e r V e n tila tio n Rates are Specified fOc H 0 |fe 0H ?- e * A . 'its s| CO ^ m' O (2' 'S 3 *3 1 * Jj 0. as .is If Sj > 3 3 -oa K o ft H o & 0 z 13 s BEbSd <D > 1 A S-o . 3 0-- be 0 OA O0 OS 3 a Abrasive blast rooms 1 shot) Abrasive blast oabine Asbestos Carding .. Spool w inding Barrels--Drums (fillr ing m aterial b y sco B e lt conveyors B ins %(olosed top) B ucket elevators Ceramics D ry pan D ry press Aerographing F ettling, brushing, and unload .0 3 <0 b be .0bO 1 T ig h t enclosure (usually in roo T ig h t enclosure openings Enclosure Local Hoods B ooth or enclos spillage hoppe Local Hood Booth Connect to bin l feed point Local Hood Booth w ith saw Enclosure Local a t die Local at die A t supply bin Booth Downdraft or s s3 b e0e o A 3 ^O0 0 7eL3a S 0 >> O a g S3 >J 83&s 0 '0 t0do "3 73 8 a 0 2^ 00 A *f "3 73 > 2 A us -- cs c >0 >o 1 O 2 0 PhD to to^-*33 a j0s*a bO 2s 703 a S3 oSO. 21 2a If 0 .5 ' |0 cfm per mac! i cfm per spool . a a 0 30 0a0 a00 30l. cc - a 4) 0 aa 3 aj 00 00 7T aa a 8 ^ * I 8a d I x 0 e lt speeds less t foot of belt wi< fpm through over 200 fp m width but not open area 50-200 fp m th points 0 cfni per sq ft section 00 cfm 50 fp m a t face 00 fp m througt 00 cfm 00 cfm 00 cfm 00 fp m (face) 00-150 cfm per producing ope si 0 ft a 's a e| 0 s O > . AMSO O 11 3 0 t0e 1 0 8 0 fpm-350 cfm per not lesB th a n 150 | ea. B e lt speeds 1 per foot of belt 200 fp m through 0 3 73 . 73 i L* +> to s ig la ** 0 if o0 7S3 00 A = i 3500 3500 3000 3000 3500 . 3500 3500 3500 3500 Ref. ini co Con CO O MC |J| O--O 0Si"5. - o S3 t-" (2 PS ' <3 g.2 8 8 QO * a 3500 3500 3500 3500 3500 3500 3500 3500 3500 0-3?a0 s0 - 00 -01 1 0"533 ' r-*f 0 CO N *C'C Ref Ref 18. For porta C 1n o t as effective 3 73 0 1956 Guide i 2 -2 &0 o0 A 3 9a 3 _g `5 ao 0 e s 1 .rfi &' P~ a H* < 5 *f H <a> to p fcg %t *3 H Jp o to S he 5^ a < *4 " OO R O OO 1 3*0 0 H be .2 0 00, 0 S >s 73 03O S 2C H *tce 7003 Ae Furnaoes Stationary m elti ferrous T iltin g or rocki non-ferrous Electric Aro for 1 Forge (hand) arage (ta il pipe a tion) ranite cutting an Pneumatic hand Surfacing machii rinders Polishers, buffers Portable Swing fram e itchen range iboratory hood door) 0 1 3 3 Sa "1 .02 VObn . M a1 & a be be 5 be 8 00 Enclosure | Enclosure Enclosure Canopy Hood attao Canopy Local hood pipe 1 Local hood Local hood Booth Booth Canopy Booth type Local hood Booth 1 8 AA AA, ^32 1*0 IB la 3 0 A0 a $ 73 tc .O 73 10 -d . 0 .2 -- 3 V entilatio n * .*4 | 200 fp m through openings 100-200 fp m a t hood opening 3000-6000 cfm 2500 cfm per ton charged 200 fp m a t faoe 100 cfm th r u 3*in. flexible duct fc 200 cfm th ru 4-in. flexible duct 300 cfm th ru 4f>in. flexible duot f engines 500 cfm ' 500 cfm for tools u p to 2 -f in . dia 1000 cfm fo r 2-} to 2-} in. diamet See Table 3 Bench type, 2-400 c fm per sq f t 1 g rille b u t no t less than 150 cfm of plan working area. ' 100 fp m a t face 100-200 fp m in d ra ft through op booth face . 100 fp m a t hood face 50-100 fp m 200 fp m a t hood face 125-200 fp m a t booth face ---------- 3 9 *9 9 O O s Ml 0 0 0 2 Sa' a 0 00 w s 3? b bas |-3 ?2 s"Q 3^ .2 00 SS S05 0000 00 ' * 7 ? 000 V) 1 06O1 263 00 h a PS 0 2 0 a 0 0 a 0 f$ s 02 H**e- ' g8 P 63 D> o N .3 S3,S1 S S eo a S3 IS ft" O (S g5 g-i g^.a-g t> > 0 & <CN4 --3 3500 i, 21, 23, 2 ventilat rate for toxic >-l rate can >h more c tilation of tuted bu ventilatio 0 2* S S m a te ria lly re* lete enclosures ting room may volves g re a tly be - 2000 0 CO 5 `s be .2 a0 1 H (Q eo "a -d * si f sill uia0o O0O NcbOhO --* CO II 0 QO s 3500 3500 3000 1500 tooo hb (S" & ggs "03 Is bTS 2.2 73 fe 73 11 ga a 8g (SB a a g-s b0 23. 29. bic&l 3M-la < i 8 b 11 ap. 3 nterlor vertical grease. (Ref. location very d for toxio maates for toxio If ' .---73V js 73 . . 38 1 -Si A 1 73 0> a be .*53' 1 w J 3 2a a 5. a^ ssfiTs S3 81 T a b l e 2. A G u id e t o V e n t il a t io n R a t e s f o r T y p ic a l n d u s t r ia l E q u ip m e n t (Continued)I State or L o c a l R egulations Should be Consulted and Followed Where H ig h e r V e n tila tio n Rates are Specified 1046 fcCLi A'-'ag s| CHAPTER 46 21 a as A-f II O he If 1| S s" gta *T3 5 'IS 3 `3 nog S*8.s& *g".a _ 3 ax>*fl*3 A* g'JJ 5fl ft. ao ** ss O W Q, h fl s3f *3 2 o c*3 *0M c >.S 52? a* 5 -g C JiSi 3 .8 8's'S s 1956 Guide ff ggs S-Sfl Sis e S "C ** M. 5d!* ?8 3.1 f1 Su O tso*c? *sfl a .S2 *Q o-- o 8o gw co &* a-a 3T.3J Ifl3I-. t- 43 8b 41 fl '** Msa 2S *>tao gS 5a Oa .8 a -= a| u H3 la II " cd* sj i Iis.i*, fal.c*> 5o 3oja2 `e e: 2 -sa H3 fl.2' tea fl 8t* fui cB ^" 8fc I iijgi 5 .o33W3 sS.Ca-a >S 33*iftl O fal JjAagfMcO. CD T a b l e 2. A G u id e t o V e n t il a t io n R a t e s f o r T y p ic a l n d u s t r ia l E q u ip m e n t (Concluded)I State or Local R egulations Should be Consulted and Followed Where H ig h e r V e n tila tio n Rates are Specified Kef. 3600 00-401 2000 2000 3000 3000 3500 Industrial.Exhaust Systems . a aa . ha X 2 k; < aa a? 1 i e !? ~ a. c> ^r* u Oa' T C4 co 1 f&S-g 'aS2s fl * 5 s'fl O .sisi j s 1 .2 --oS S3 g S-Ofl !?S8fl co 3 3 fl g ^"If-l 2m`.?2 2^1 . s* m2 fol ao eoo . ` * X CCOO o : 'S' 00 100-400 fp m ind ra ft through inspection 100 fp m a t boot h face 8-10 in . from arc--425 cfm 6-9 in. from arc--275 ofm 6 in . fro m arc--160 cfm V e n t il a t io n A ir Flow ' -6 g ' . | B H >e<* o <a > ooo -ooo oO7oo7oeol* --- ' ao eo 11 83 2Q O"MM g 111 .0.0 5 fl a*a aaaa aa oOCj) oCoVJooCQ OoOoOo o" . Otoo1 - CO o o bFeo rl ISsJ .jaK**ffll Sc fl. 3p; L. 2 i i. lal*oij <M Hill lenings b u t not less than plan area - IO oC JP :9 m ills branchi side dimem outlet. should 5a . oo' - , c fro fm pmerarsoa f--t60g0rilclfemarea king per o aq p f e t nin of gs, b u t <enolosed not plan less area than oK 2 cfm cfm Use branch dia 50-150 75-160 10-12 in 150-250 wor cfm o fl 8 3*3 B ; .S h l. P o a> Sg 2g-3a a 5.0^ H TfT 535 8OO P303CQ CD f3l a > X) .2 " . ad . . * . I I-. -gj w . o_ 3 8 fl a $he 8 a 8fl ao w 3 -- sfl . fl g a Ca s s o J3 fl a 3-o3 =O: Sf3fl CD E- H a3 a* . bling m ills, drums, xela he fl . . ,J3 3 - -1 8 $ " 11 M -O a om o 3 a 5 *3 3 -a 3S qIo 00 3 21 o So O Q . E3s pi |.|1 fli i0S | % | '8 hfle g i. a 2 he he hfle 3 f8l.See-O .hSe.2. i S3M3 % 3 8 S S 3 O p e r a t io n ppeerrssclqf tf to of f open face area dust' producing p i area it\ :. | *>i * | *11 + kU * j *'! * 3. Exhaust volumes insufficient to dilute mixtures of combustible vapor and air to less than 20 percent of the lower explosive limit of the combustible. 4. Room air currents caused by cross drafts, spot cooling, motion of machinery or operators. ; 5. Local or State regulations may specify larger exhaust volumes for specific opera tions. . Exhaust volume requirements for many specific operations have been listed in Tables 2, 3, 4, and 5. Table 3. Exhaust Requirements" for Grinding, Polishing, Buffing, Scratch Brushing Abrasive Cut-Off Wheels, Grinding and Polishing Belts (Air Volume: lfiOO fpm in all branches.) (2 in. water suction at average hood) Grinding or Cut-Off Wheels Buffing, Polishing, and Scratch Brushing Wheel Diam, Max. Branch In. Width, In. Diam, In. -9 10-16 U3 24 17-19 3 4| 20-24 4 5 23-30 5 6 31-36 6 7 CFM 225 390 500 610 880 1200 Wheel Diam, Max. Branch In. Width, In. Diam, In. CFM -9 10-16 17-19 20-24 25-30 2 3S 300 3 4i 500 45 610 5 5i . 740 6 61 _ 1040 Riff! ml 1; ] m\ Horizontal Single Spindle Disc Grinders Horizontal Double Spindle Disc Grinders Vertical Single Spindle Disc Grinders Wheel Branch Diam, In. Diam; In. CFM Wheel Branch Diam, In. Diam, In. CFM Wheel Branch Diam, In. Diam, In. CFM -12 13-19 20-30 31-36 3. 225 -19 1-5 610 -20 1-4* 500 4 390 20-25 1-6 880 21-30 2-4 780 5 610 26-30 .1-7 1200 ; 31-53 2-6 1760 6 880 31-53 : 2-6 1760 54-72 2-8 3120 - 54-72 4-8 6240 Grinding ob Polishing Belts: '' To 3 in. wide--3 in. branch, add } in. to branch diameter for each' 2 in. or fraction increase in belt width over 3 in. . * Increase branch diameter 0.3 in., but not less than J in., for each 1 in. increase in width over dimension noted. Duct System Design The duct system will 'Consist of branch ducts connected to a main duct which will convey the air from the hoods to the exhaust fan and the air cleaning equipment, if used. Round ducts should be used wherever pos sible. Their gage size and construction differ from air supply practice due ! to the rougher usage encountered, and in the case of dusts, to the abrasive effect. (See later section on Exhaust System Design and Construction Fea tures.) Usual conveying velocities are shown in Table 6. Where solid con ! taminants are handled, recommended velocities must be maintained through out the system to prevent material from settling in the ducts and obstructing the air flow. For conveying of solid particles, velocities shown in Table 6 include a reasonable factor of safety, and design velocities may therefore be adjusted to use commercial pipe sizes which are available generally in 5-in. diameter steps through 6-in. diameter and 1-in. steps through 16-in. diameter or larger with 2-in. diameter steps for large diameters. For con i i taminants that are not solids, conveying velocities are based on a balance i Industrial Exhaust Systems 1049 Table 4. Ventilation Rates for Open Surface Tanks94'" Process Minimum Ventilation Rate CFM Per Sq Ft Hood Opening Minimum Ventilation Rate CFM Per Sq Ft Tans Area Lateral Exhaust (Note 1) Enclosing Hood Canopy Hood One Open Side Two Open Sides Three Four Open - Open Sides Sides W/L 0-0.24 AB W/L 0.25-0.49 AB W/L 0.50-1.0 AB Plating Chromium (Chromic Add . Mist)............................................. 75 100 Arsenic (Arsine)........................... 65 90 Hydrogen Cyanide.................... 75 100 Cadmium.......... ......................... 75 : 100 nodising............................ ........... .. 75 100 Metal Cleaning (Pickling) Cold Acid.............. ^.................. 65 90 Hot Acid......................................... 75 100 Nitric and Sulphuric Acid... "75 ' 100 Nitric and Hydrofluoric Acid.. 75 100 Metal Cleaning (Degreasing) See Note 2 and Ref. 43 and 44- Metal Cleaning-(Caustic or trolytic) ---- Not Boiling 65 " 90 Boiling..................................... 75 100 Bright Dip (Nitric Acid). . 75- 100 Stripping '. Concentrated Nitric Acid 75 " 100 Cone. Nitrio and Sulphuric . Acid................................................ Salt Baths (Molten Salt).............. 75 50 100 75 Salt Solution (Parkerize, Bond- erize, etc.) Not Boiling................................... 90 90 Boiling............................................... 75 100 Hot Water (if vent, desired) Not Boiling..................................... 50 75 Boiling............................................... 75 100 125 100 125 125 125 100 125 125" 125 100 . 125 . 125 125 125 75 100 125 75 125 175 150 175 175 175 150 , 175 175 175 150 175 175 175 175 125 150 175 125 175 125 175 150 90 130 110 125 175 150 125 175 150 125 175 150 90 130 no 125 175 150 125 175 150 125 175 150 90 130 no 125 175 150 125 175 150 125 176 150 125 175 iso 60 90 75 90- 130 125 * 175 60 9a 125 175 110 150 75 150 200 175 150 : 130 200 175 200 175 200 175 150 200 200 200 . 130 175 175 175. 225 170 225 225 225 170 225 225 225 150 130 170 200 175 225 200 175. 225 200 175' 225 200 175 225 100 90 110 150 130 170 200 175 225 100 90 no 200 175 . 225 Note 1--Column A.refers to tank with hood along one side or two parallel sides when one hood is against a wall or a baffle running length of tank and as high as tank is wide; also to tanks with exhaust manifold W - along cento* line with ^ becoming tank width in W/L Ratio. . Column B refers to free standing tank with hood along one side or two parallel sides. - ^ Note 2--Complete control of the vapors and mist from degreasing operations requires the same ventila tion rates as recommended for pickling. However, the solvents employed in degreasing operations are rela tively volatile, and the solvent loss caused by evaporation increases rapidly as the exhaust rate at-.the tank increases. For this reason perfect control is usually sacrificed in favor of lower solvent.evaporation rates. Where solvent loss does not present an important cost or operating problem,.the exhaust rates given for pickling should be adhered to, but where solvent loss must be kept at a -minimum, an exhaust rate of 50 cfm per sq ft of tank area is commonly employed. Where this rate is used, cqntrol wtil be adequate only if the tank is located in an area free of drafts and if the degreasing operations are carried out in accordance with a rigid schedule.** - between the higher resistance and lower first cost of smaller diameter ducts against higher first cost and lower resistance of larger diameter ducts. Main ducts connecting two or more branches are sized by the same pro cedure. The main should be designed for the total exhaust volume to be handled through all branch ducts. Where exhaust systems handling solids are to provide for a substantial increase of future capacity, required conveying velocities can be maintained by: . . . 1. Providing open end stub branches in main through which air will be admitted into system until future connection is made. The volume admitted into the main 1050 CHAPTER 46 1956 Guide Table 5. Exhaust Requirements for Woodworking Operations*1 (Air Velocity: 4000 fpm in all branches unless noted otherwise) ; Self Feed Table Rip Saw Use 1-5 in. branch at bottom pulley; 1-4 in. branch at saw head. Lane Self Feed Rip Saws Other Than Table Saws Use 1-6 in. branch at bottom; 1-5 in branch at top. Swing Saws Up to 20 in. use 1-4 in. branch; over 20 in. use 1-4)4 in. branch. Circular Saws . Up to 12 in. diam...................................................................................................... ......................................... 1-4 in. branch Over 12 in; diam....................................................................................................... Dado head saws......................................................................................................... Gang Circular Saws - . - - . .Ventilation rate depends on effectiveness of hood and maximum number and diameter of saws. Disc Sanders Up to 12 in. diam.....................................:............................................................... 12 in. to 18 in. diam................................................................................................ 18 in. to 26 in. diam................................................................................................. 26 in. to 32 in. diam............................................................................................... 32 in. to 38 in. diam................................................................................................ ... 1-4 in. branch and 1-5 in. branch 38 in. to 48 in. diam................................................................................................ ... 1-5 in. branch and 2--4 in. branch Multiple Dnim Sanders (over the table) - Up to 31 in. wide................................................................................................................................. 5 in. branch (see note) 31 in. to 49 in. wide.......................................................................... '..................... .......................... 6 in. branch (see note) Over 67 in. wide.................................................................................................................................... 8 in. branch (see note) Note: One branch of size indicated required for each drum. Fewer branch pipes may be used as long as total branch pipe cross sectional area is not reduced. Some manufacturers use I extra branch of equal size on feed side. 1-4 in. branch may be required for exhausting bed rubber cushions or mechanically operated brush. Single Drum and Spindle Type Sanders ' Up to 50 sq in; sanding surface.................................................................... .......................................... 50 to 200 sq in. sanding surface.......................................... ......................... 200 to 400 sq in. sanding surface................................................:.................. .......................................... 400 to 700 sq in. sanding surface.............................................. ...................... 700 to 1400 sq in. sanding surface.............................................. :.................... 1400 to 2400 sq in. sanding surface..................................................................... 1-3 in. branch 1-5 in. branch Horizontal Belt Sander or Edge Sander (see note) , . Drive Pulley Idler Pulley Up to 6 in. wide............................................................................................................ .: 1-4)4 in. branch 1-4 in.branch 6 in. to 9 in. wide.............................................. '.......................................................... .. 1-5 in. branch 1-4 in.branch 9 in. to 14 in. wide............................ . .................................................................... .. 1-6 in. branch 1-4 in.branch Over 14 in. wide............................................................................................................ .. 1-7 in. branch 1-5 in.branch Note: Where more than one belt is used, the pipe sizes specified shall be required for each belt. Where a common hood is used for more than one belt, a single pipe of an area not less than the sum of the areas of the pipes specified may be used. -. . .. Where belt is reversible, pipe at idler pulley shall be the size specified for the drive pulley.' Vertical Belt Sanders (rear belt and both pulleys enclosed) Up to 6 in. wide......................................................... -.............................................. .......... -........ 4)4 in. branch on bottom 6 in. to 9 in. wide...................................................................................................... ........ ...........5 in. branch on bottom 9 in. to 14 in. wide................................................................................................... Over 14 in. wide........................................................................................................ Band Saws and Resaws -' Up to 2 in; wide.......................................................!.....................................: ___ 2 in. to 3 in. wide...... ............................. ;.............................................................. .... 3 in. to 4 in. wide.'.................................. ....-.............................................................. 4 in. to 5 in. wide.......................................................................................................___ Over 5 in. wide.......................................................................................................... .... Bottom 1-4 in. branch 1-5 in. branch 1-6 in. branch 1-7 in. branch 1-8 in. branch Top 1-4 in. branch 1-4 in. branch 1-5 .in.branch 1-5 in. branch 1-5 in. branch Jointers .' Up to 6 in. knives................................................................................................... 6 in. to 12 in. knives.............................................................................................. 12 in. to 20 in. knives.................. :........................................................................ Over 20 in. knives.................................................................................................... Industrial Exhaust Systems 1051 Table 5. (Concluded)Exhaust Requirements fob Woodworking Operations (Air Velocity: 4000 fpm in aU branches unless noted otherwise) Single Planers or Surfacers . t ._ Up to 20 in. max. working width.................................................................................................................. 1-6 in. branch 20 in. to 26 in. max. working width.................................................................................. 1-7in.branch 26 in. to 32 in. max. working-width............................................................................................... 1-8in.branch 32 in. to38 in. max. working width................................................................................................................ 1-0 in. branch Over 38 in. max. working width............................................................................................................. '... 1-10 in. branch Double Planers or Surfacers ' Upper head Up to 20 in. max. working width............................................................................. 1-6 in. branch 20 in. to 26 in. max. working width........................................................................ 1-7 in. branch 26 in. to 32 in. max. working width..................................................................... 1-8 in. branch 32 in. to 38 in. max. working width........................................................................ 1-9 in. branch Over 38 in. max. working width.............................................................................. 1-10 in. branch Lower 1-5 in. branch 1-6 in. branch 1-7 in. branch 1-8 in. branch 1-8 in. branch Moulders, Matchers, Sizers' (see Note) ' ;. Matcher head Top ' Bottom Up to 4 in................................................................................. 2-4 in. branch 1-5 in. branch 1-6 in. branch 4 to 6 in....................................................................................... 2-5)4 in. branch1-6 in. branch , 1-6 in. branch 6 to 8 in....................................................................................... 2-6 in. branch 1-7 in. branch 1-6 in. branch 8 to 18 in...................................................................................... 2-6 in. branch 1-8 in. branch 1-8 in. branch Note: Where profiler is used, provide additional pipe not lessthanthatspedfiedfortop head. Wood Shapers 1-4)4 to 10 in. branch for each spindle according to size and character of work. Tenoner ---------- For cutoff saws: Up to 12 in. diam............................................................................................................... Over 12 in. diam............................................................................ ;.................................... Use 1-5 in. branch minimum for each top and bottom tenon, cope and dado head. _ 1-4 in. branch 1-5 in. branoh Automatic Lathes Use 1-3 in. to 1-10 in. branch according to work length. Hogs ... .. Air volume based on 50 cu ft per lb of refuse conveyed. Use 4500 fpm minimum oonveying velocity. Floor Sweeps ` Use 6 in. branch for fine dust to 8 in. branch for coarse material. ' Mouth at floor, 10 X 4 in. to 12 X 5 in. . Note: Area of floor sweep pipe need not be included in computing main pipe area. Miscellaneous Equipment ' _# Pulley pockets and chain mortises-3 in. branch; dovetail and lock corner machines, dowel machines, duplex molding sanders, forming lathes, panel raisers (each head), ploughs, rail shears, routers, sash stickers (each head) 4 in. branch; pulley stiles-5 in. branch; glue jointer-6 in. branch. can be adjusted to required airflow rate, cfm, by use of a blast gate or orifice plate in such stub branch. 2. Arranging system layout so future points can be picked up by a separate main which will run directly to the fan or air cleaning equipment inlet. CALCULATION OF SYSTEM PRESSURE LOSS The pressure loss of the system includes entrance loss37 as air is accelerated through the hood to a branch duct connection, resistance loss of ducts,38 elbows, and junctions, and acceleration or deceleration losses from velocity changes within the system. Chapter 32 includes data on duct resistance and on resistance of elbows, and provides sample calculations. In exhaust sys tems, either the equal friction method (illustrated in Chapter 32) or the use of blast gates in the branches to equalize pressure loss of all runs is em ployed.8' 11 13'18 Data on losses for hood entrance and branch entry, transitions and weather hoods-are given in Fig. 2. The static pressure in branch ducts close to the hood connection is frequently referred to as hood suction. It is the sum of the velocity pressure in the branch and the hood entrance loss. 1052 ;. CHAPTER 46 1956 Guide Table 6. Approximate Conveying Velocities Material Conveyed Design Velocity FPM 2,000 3,000 3.500 3,500-4,500 4.500 and over 3- He 0.9S VP Ce 0.72 PLAIN DUCT END ;=*- FLANGED DUCT END h- ZH-- Hm * 2.3 VP DUCT; OP BETTER; . 1.78 VP ORIFICE 049 VP DUCT . Ce 0.5S ORIFICE PUJS FLANGED DUCT 0ANY SLOT TTPC5) . '-Ce ____ He* rCeS x vp c Q*4003ACeVvF He * 0.50 VP C = 0.82 DIRECT BRANCH He = 0.85 VP Ce s 0.78 STANDARD GRINDER HOOD - " F ENTRY LOSS FACTOR VP VELOCITY PRESSURE W DUCT X-rtc \ TWC SP* STATIC PRESSURE AT THROAT, INS. WATER CAGE He* ENTRY LOSS, INS. WATER GAGE . Q - AIR VOLUME, CFM - A * CROSS SECTION AT THROAT, SO FT. C* COEFFICIENT OF ENTRY ' ENTRY LOSS FOR COMPLICATED HOOO SHAPES L BREAK HOOD INTO SIMPLE COMPONENTS 2. CALCULATE He FOR EACH COMPONENT 3. ADD VALUES OF He HOOD ENTRY LOSS Ce0.82- 098 TAPERED HOODS FLANGED OR UNFLANGED; ROUND SQUARE OR REC TANGULAR. 8 IS THE MAJOR ANGLE ON REC TANGULAR-HOOOS- -CEO- ai> ---j2D UWf-*-- TAPER R, (REGAIN) L, (LOSS) ANGLE. FRACTION OF FRACTION OF DEGREES VP DIFFERENCE VP DIFFERENCE 3.S 0.78 0.22 5 0.72' 0.28 10 O.S6 2IS0 0.42 0.28 0.44 0- 58 0.72 2S 30 OVER 30 00..1030 0.00 01..6070 . 1.00 OTCELERATIQN LOSS L REGAIN TAPER L, (LOSS) ANCLE, FRACTION OF DECREES VP DIFFERENCE 1S0 O.OS 0.08 2IS0 00..1008 23 0.11 30 4S 00..1230 60 as ACCELERATION LOSS ANGLE LOSS FRACTION 8. OF VP IN DECREES BRANCH BRANCH ENTRY LOSS -S EQUALLY SPACED BRACKETS AS SHOWN WEATHER HOOD LOSS Fig. 2. Exhaust System Design Data13 Tapered hood data from Reference 37 Weather hood data from Reference 38 Industrial Exhaust Systems 1053 EXHAUST SYSTEM CONSTRUCTION SPECIFICATIONS AND DESIGN DETAILS15 Correct design and competent installation of sheet steel ducts and hoods are necessary for the proper functioning of any exhaust system. The follow ing specifications are mainly those recommended in the manual Industrial Ventilation.15 . .......... ' . General Requirements All exhaust systems shall be constructed with the materials recommended here with and shall be installed in a permanent and workmanlike manner. The interior of all ducts shall be smooth and free from obstructions; with joints either welded, flanged, or soldered air-tight. Materials a. Ducts shall be constructed of black iron welded or of galvanized sheet steel riveted and soldered unless the presence of corrosive gases, vapors and mists makes use of such material impracticable. Galvanized construction is not recommended for temperatures exceeding 400 F. Welding of black iron of 18 gage and lighter is -not recommended for-field fabrication. ' b. For average exhaust systems on non-corrosive applications the metal thickness in the following table shall be supplied. Diameter of Straight Ducts (Inches) U. S. Standard Gauge fob Steel Duct Class I 24 ' 22 20 . 18 Class II 22 20 18 16 .Class III 20 18 16 : 14 Class 1. Includes ducts non-abrasive applications such as for paint spray, wood working, pharmaceutical, and food products. Class II. Includes ducts for non-abrasive material in high concentration flow pressure pneumatic conveying); moderately abrasive material; and highly abrasive materials in light concentrations. Typical examples are chemicals and wood dust; exhaust of foundry shakeouts and sand handling systems, grain dusts; coal crushing and screening; exhaust of grit blast cabinets; and grinding, buffing and polishing. Class III. Includes ducts for conveying all highly abrasive materials in moderate to heavy concentrations and moderately abrasive materials in heavy Concentrations as in: low pressure conveying of tobacco; and exhaust systems from abrasive cleaning operations, rock and ore screening and crushing, dryers and kilns, and flyash from boiler stacks. Where aluminum duct is indicated, the following equivalent B & S gage thickness of sheets should be used: Steel--U. S. Standard Gage Aluminum--B & S Gage . 26 24 22 20 18 24 22 20 18 16 c. Elbows and angles shall be a minimum of two gages heavier than straight lengths of equal diameter. d. Hoods shall be a minimum of two gages heavier than straight section of con1 necting branches. , e. Where flexible piping is necessary, a non collapsible type of flexible piping shall be used and its length shall be kept at a minimum. '/ Construction a. Longitudinal joints of ducts shall be lapped, and riveted or spot-welded on 3-in. centers, maximum. b. Girth joints of ducts unless flanged or butt welded shall be made with lap in direction of air flow with not less than 1-in. lap. 1054 CHAPTER 46 1956 Guide c. Elbows and angles should have an inside dr throat radius of two pipe diameters whenever possible, but the radius shall never be less than one pipe diameter. Large radii are recommended for heavy concentrations of highly abrasive dusts. Con struct elbows 6 in. or less in diameter of at least five sections, over 6 in. diameter of seven sections. Angles shall be pieced proportionately. d. Hoods must be free of Bharp edges or burrs and shall be reinforced to provide necessary stiffness. e. Provide dead end caps within 6 in. from last branch of all mains and sub-mains. f. Provide cleanouts every 10 ft and near each elbow, angle, or duct junction in horizontal sections. g. Support ducts sufficiently to prevent placing of any load on connecting equip ment and to carry weight of system if plugged with material. Use maximum sup porting interval 12 ft for 8 in.or smaller ducts and 20 ft for larger ducts. h. Provide 6 in. minimum clearance between ducts and ceiling, wall, or floor. i. Rectangular ducts can be used only when clearances prevent the use of round construction. Rectangular ducts must .be as nearly square as possible. Weight of metal, lap and other construction details are to be the equal of round duet construc tion whose diameter equals the longest side. j. All branches shall enter the main at the large end of the transition at an angle not to exceed 45 deg (30 deg is recommended). Connect branches only to top or sides of main, with no two branches entering diametrically opposite. System Details a. Connect duct to fan inlet with split sleeve drawband one pipe diameter long but not less than 5 in. b. Transitions in mains and sub-mains are to be tapered; taper 5-in. long for each 1-in. change in diameter is recommended. c. Place blast gates for adjustment of system near connection of branch to main. Provide means for locking gates after adjustments have been made. . d. Fire dampers, explosion vents, etc., should be installed in accordance with NFPA Codes or local fire ordinances. Deviation From Specifications Where State or local laws conflict with the specifications given, the more stringent regulation shall be followed. Any other deviation must be approved before instal lation. AIR FLOW PRODUCING EQUIPMENT The principal types of air moving equipment are centrifugal fans, axial flow fans, and venturi ejectors. Chapter 33 includes information oh fan types, arrangements, and application. Gravity stacks have application for some systems handling higher air temperatures or steam where no air cleaning equipment is installed. Centrifugal fans are most frequently used for the bulk of exhaust system applications due to the system pressures involved. Where air cleaning equipment is included, fans are usually located on the clean air side. The paddle wheel or modified paddle wheel designs are heavily constructed and have few blades to make them more suitable if wear, corrosion, or ac cumulations are a factor. The higher efficiency backward curved blade designs find application where relatively clean, non-corrosive air is handled. Forward curved blade designs have limited application due to the number, shape, and metal thickness of the short curved blades. . Belt driven fans are recommended by many designers because a change in fan speed is often needed where future changes of the system may be involved, where added pressure losses from air cleaning equipment improve ments are anticipated, or where the fan may be used at some later date for another application. The axial flow fan is used for systems having low pressure losses. Pro- Industrial Exhaust Systems 1055 peller or disc designs develop pressures under 1 in., the yanerA^jal,d^.igns develop higher pressures but seldom Are used where pressures ^exceed 3 in. .......... ......... .... " .. ...." ' ' ....i'.' `: The venturi ejector39 is an inefficient method of air moyementj:butJhias the advantage of causing air flow without the exhaust air passing[through the air flow producing equipment. It minimizes the explosion or corrosion potentialities in certain types of system. ; . Fans, motors, and drives should be located so that safe and easy access for periodic inspection, servicing, and maintenance is possible. AIR CLEANING EQUIPMENT ......... .... j As discussed in detail in Chapter. 34, air cleaning equipment should: be considered in all-systems to prevent property damage, neighborhood - pollution, re-entry to the working space; to salvage usable material, reduce: fire and explosion hazards or to make possible some'recirculation of-air-to the working spaces. The present growing emphasis on air pollution control, makes it desirable to remove all contaminants to-the greatest practical de-\ gree based on reasonable cost and maintenance. ..... ........... MAKE-UP AIR REQUIREMENTS ............. A correctly designed exhaust system may be ineffective during periods . when windows and doors are closed. This condition should be anticipated and prevented by making provision for an adequate air supply. Poor per formance of exhaust hoods is caused by: absence of air supply systems; cold drafts due to high indraft velocities through cracks and openings in building construction especially at windows and doors; reverse air flow through low pressure systems of roof ventilators or general ventilation systems; downflow through heater vent stacks preventing exhaust of flue gases to the outside. Systems for conditioning make-up air do not necessarily increase heating requirements for the space, as cold air due to infiltration from the outside must be heated somehow to maintain comfortable temperatures in the area.' The cost will depend on the ratio of exhaust air to that required for ven tilation of the space occupied. MAINTENANCE OF PERFORMANCE Periodic inspection and checking of exhaust systems are necessary if con trol is to be maintained at the effective level of the original installation. Continued effectiveness depends on maintained design air volume flowing through the exhaust hoods. A checking procedure, therefore, must in clude some data to indicate at least relative air flow through the hoods. The static pressure or hood suction measurement will prove useful for such checking if data are available on air volumes and pressures at the time the system was installed. Testing and recording of such data for each new installation are of the utmost importance. : While hood suction readings have rightfully been discarded as a means of measuring air flow, they do offer a quick and accurate method of measuring relative air flow. If the hood suction is known while an exhaust system is functioning properly, its continued effectiveness can be assured so long as the hood suction is not reduced from its original value. Unless the hood design is altered or there are accumulations in the hood or branch pipe between hood and point of hood suction reading, the air volume a b l e 7. R e s is t a n c e t o C o r r o s io n o p M a t e r i a l s U s e d f o b H o o d s a n d u c t s 40DT 1056 CHAPTER 46 1956 Guide exNiOf ousvh bua . an<i avto aauxauA. .. HW WB B'H W H & '/. .8 EP . S 8 AHrv'd SAix Kisag. axniNiA ' = r S: . oa - nanj, so asyog ' -. -- xn3hb) soxsaaay .. g ` h , to ; ' w _ .. xzsag ievo artog so `aasvg fl J B co t& ' ' aooAiaag so aooAULag aaaxog iKiyj aooAi . asBsasg asxKivg <ioom so aviaw no -asj/iaj aeano^-g nosi-attvo NO .. . J 002-081 '>h . .. xovTfr so Aivn HOSI NO INIVg .2 o' d ,1 Py fa 03 , -fa fa . :. - 00 OO 00 CO A a p h a li : . 'fa W CQ fa CQ fa H ' CO B. ' - fa fa fa - 00 CO 'fafaoofaoofafafafafafafafa co fa Tvasoaojj . . ' S TNng aivij atraaj, aNasaoa^ aM sassaaj ... sasoag 'ivsniv^j aasang osth .. ' . HONmaiy . CO fa' 0Q 00 fa fa fa fa fa cq co a SP P S E fa CO w ` fa . . w h" .. ' o CQ onintj ayag 00 > . to fa fa fa OO fa ' . S'fc ' | d" . |S IS. 83 "111 2 > fl JUS* 5 3 |l| 6 * S fl C4. fl cc ;a d & 2 .2 o fl ..'.2 n m'.S . . T3NOft aaaxg esaTNirig GO CO fa "H H S a H . fa : S- CO C c2 a.3.35 <S - -g * nosi aovag nosj aaaiNVATVQ ' ' ; v axONxooj aag fa fa fa afa fa 'fa fa fa fa fa fa fa fa fa CO fa CQ fa 00 CQ fa fa OO ^ fa fa fa . CO fa CO fa fa fa fa CO 00 OQ , ' ~ | 8.2 1J S I'!h^ 2 fl ~ to .5. {g co .2 8I 2. S a S "* fa T3 5 fl r*o4 a1-1 5 oCPu3 2>PS <U3 f* >, l _ o o S35a-2 83. <3. KoOfafacS -* o li 08 .s a 23 e.* o *3 te S* r .a.! .2 t`B 3 . %S a 5'Sig 6'? 56 sIS a *JfaS s | 2 .d O s s aT3 "3 C ^C --c ,,S o .d afl 2 *fl T5 X >* K T3 T3 *S *3 < <5 .2 S .tJ 2) rw .j *3 <J cq ra q 3 a ^ o 3 .5 w w oo to O a 9 t t3 Q It O * ?S.ga fl '3 .2 5 s-s^ i3 1.2 55 a 053* *f2l Q roa . aaw w- *w ea* fa. aa o .e .2 '3 s II j -s S 9 t: 3 <! P. fl fl fl s&g gJ 9 <5* a IS ,S0 3i'9 3 W fal QQH ?i iii 1a. 1S13 0 00 M 1 55 '8 fafl 0a0 fE5? ins fl *T fl a^i-g .9 fl .. -cea 4C^O.W'* -Ccf**t b ' 5 * f o. . Iss 3J.O w d s*| - -5 7! 3 ' 8 E2 * * pl Si & T a b l e 8 . R e s is t a n c e t o C o r r o s io n o f M a t e r i a l s U s e d f o r E x h a u s t a n s 40F A d d D ip p in g , P io k lin g a n d S tr ip p in g ..................................... A lk a lin a C le a n in g .................. .............................................. ........... A n o d iz in g ................................................... .......................................... C o a tin g --E n a m e l a n d L a c q u e r ................................................... D e c a rb o n iz in g .......................................' .............; ............; ................ D egreasing a n d M e ta l C le a n in g ................................................... H a rd e n in g a n d Q u e n c h in g .. . . . .................................................... P la t in g .................................................................. ................................. W ashing a n d R in s in g ........................ .................................. ..........i 1 Industrial Exhaust Systems 32Noag aioy fa- 918 I8IV . - fa ; ' <ioM tiassaSjj . , . ' fa ovaoaog fa fa ' fa ' saaaaAg fa fa . 1 fa - aNaaaoa^ fa fa fa . fa fa a ' saHsag xaog CO .. . ' ., . OK1NFX aaaang asvg omxyoQ aasyg Nieag onoNaag aaa a ` ' '- OQ 00 fa CO fa . aa CO fa. XTVHdsy xog OQ xKirg avag aag- 7-fa. fa ' XNrvg Nieag tania fa . - . XNrvjj xiYHdsy CL fa GO fa fa ' fa avag a . . . OQ - OQ CL a - 3( suvag . . a a a . NOSJ XSYQ fa h h. fa aaaxg aaziNVATVo r-i B CO CO WH FJQNmmy CO 0Q . OQ fa 0Q fa Gaaxg ` fa fa 'fa fa. Cl, 3 fa 03 . 03 00 - fa fa. fa fa fa fa fat a s a. s*|l a a a Sadr .Sh' S2< S &-s o In* al S o 3 ia 29 d ^ -d o *3. *3 >! 3 i 3 . p. E S " 2 8? 5 jj 1 6 I a- -3^; 8 '3 -o I 1 g fl M 2j | a g a 1 i 5 fl O 1 g.S . aO *73 J9 a ^ . o sfl *"' ' fl a S *2 *d JRU .O > ,, SI 8.S 3 ..S 2-0 3222 - oA M o 3 2 2 *-5 & 1057 .S .H Oo fl fa ab 5g g3 S |g s K2 2 Ptt , > fl JS js zs s a| Odr 3.3. 8 ^ .sj o S frlff'l rf"''#r^i W 00 feO 1058 CHAPTER 46 1956 Guide exhausted from a hood cannot change without a change in hood suction reading. . The Pitot tube can be used for routine check purposes instead of the static pressure method. Difficulty from plugging may be encountered where heavy dust loads or moist air is encountered. In any case, the hood suction method of checking can more readily be delegated to an assistant having no technical training, whereas the Pitot, tube method requires care in reading velocity pressures in an exact position with the tube paralleling the flow of air. U-gages have been standard plant equipment long enough to eliminate any feeling of un . certainty in their use. Since pressure readings vary as the square of the velocity or volume of flow, a slight change in flow is magnified by a comparison of gage readings. Nor mally, a reduction of volume qr velocity of 10 to 15 percent will not be suf ficient to reduce the effectiveness of the exhaust system. This range is equivalent to a reduction in static pressure readings of 19 to 30 percent. A marked reduction in hood suction can often be traced to one or more of the following items: 1. Reduced performance by the exhaust fan caused by reduced speed due to belt slippage, wear on rotor or casing, or an accumulation of material in the rotor or casing, obstructing the air flow. 2. Incorrect direction of exhauster rotation. .1 3. Reduced performance caused by defects in the exhaust piping, such as accumu lations of material in branch or main ducts due to insufficient conveying velocities, condensation of oil or water vapors on duct walls, adhesive characteristics of material exhausted. 4. Leakage losses caused by loose clean-out doors, broken joints, holes worn in duet (most frequently in elbows), or poor connection to the exhauster inlet. 5. Losses in suction due to additional exhaust points added to the system or a change of setting of blast gates in branch lines. 6. Increased pressure loss through the dust collector due to lack of maintenance, improper operation, wear, etc. MATERIALS REQUIRED FOR CORROSION RESISTANCE In many cases, exhaust systems including hoods, ducts, air flow producing equipment, and air cleaning equipment will require protective coatings if carbon steel is used, or other materials of construction will be required. Need for such materials will be determined by (a) the corrosion rates on interior or exterior duct surfaces, (b) protection against product contami nation, and (c) explosion hazards. Of the above groups, construction for corrosion protection is the most dif ficult due to the complex factors that influence rate of corrosion. It is seldom possible to predict the concentration, composition, and dry- and dew-point temperatures that will exist in actual operations. A guide for selecting corrosive resistant materials based on a survey of actual expe riences has been reproduced in Tables 7 and 8.40 REFERENCES ' The material in this.chapter is based largely on the recommendations of the American Conference of Gooernmenlal Industrial Hygienists as published in the Industrial Ventilation Manual, 1952 Edition. * The Determination and Control of Industrial Dust, by J. J. Bloomfield and J. M. DallaValle (Bulletin in, U. S- Public Health Service, 1935). . * Exhaust Hoods, by J. M. DallaValle (Industrial Press, New York, 1952). . * Design of Exhaust Hoods for Dust Control Systems, by T. Hatch (Journal of Industrial Hygiene and Toxicology, VoL 18, 1936. p. 595). Industrial Exhaust Systems 1059 * Air Dilution in Industrial Ventilation, by W. C. L. Hemeon (Heating and Ventilating, February 1941). (Practical-Application of Industrial Exhaust Ventilation for the Control of Occupation Exposures, by B. F. Postman (American Journal of Public Health, Vel. 30, 1940; p. 149). .' ' Principles of Industrial Process Ventilation, by W. N. Witheridge (University of Michigan Inservice Train ing Course, October 1945). ' . T Industrial Dusts, by Philip Drinker and Theodore Hatch (McGraw-Hill Book Co., New York, 1936).' Design of Industrial Exhaust Systems, by J. L. Alden (Industrial Press, New York, 1948). ' . Ventilation, by W. N. Witheridge (Industrial Hygiene and Toxicology, Vol. I, Chap. 10, Edited by F. A. Patty. Interscience Publishers, New York, 1948). . io Transport Velocities for Industrial Dusts, by A. C. Stem et al (American Industrial Hygiene Associa tion Quarterly, December 1948). . .. . 11 Industrial Health Engineering, by A. D. Brandt (John Wiley and Sons, New York, 1947). ' i* Velocity Characteristics of Narrow Exhaust Slots, by Leslie Silverman (Journal of Industrial Hygiene and Toxicology, November 1942, p. 267)* i, i* Industrial Ventilation Manual, (American Conference of Governmental Industrial Hygienists, 1952 Edition). ` Code of Recommended Good Practice for Meted Cleaning Sanitation (American Foundrymen's Association). 18 A Study of Asbestosis in.the Asbestos Texile Industry, by W. C. Dressen et al (II. 8. Public Health Serv ice, Bulletin 241, 1938). A Study of Dust Control Methods in an Asbestos Fabricating Plant, by R. T. Page and J. J. Bloom field (U. S. Public Health Reports, Reprint No. 1883, Nov. 26, 1937). i Rules Relating to the Control of Silica Dust in Stone Crushing Operations (New York State Depart ment of Labor, Industrial Code Rule No. 34, July, 1942). " Design of Exhaust Systems, by J. M. Kane (Heating and Ventilating, November 1945, p. 68). i* Foundry Ventilation, by J. M. Kane (The Foundry, February and March, 1946). Pottery Dusts: Their Collection and Removal, by W. M. Oddie (Pottery Gazette, Vol. 53, 1928, p. 1280). n Scrapbook of Exhaust Hoods, by J. M. Kane (Heating and Ventilating. Portable Grinding--July 1950; Grinding, Polishing, Buffing--August 1950; Foundry Shakeout--November 1950; Melting Furnaces--Feb ruary 1951; Pottery--March 1951; Mixers--April 1951; and Woodworking--June 1951). ** Design of Exhaust Ventilation for Solid Material Handling, by R. T. Pring et al (Industrial and Engi neering Chemistry, November 1949). ** HarlzeU Blowers: Engineering Data <fc Installation (Hartzell Propeller Fan Company, Bulletin 1001). ** The Application of Local Exhaust Ventilation to Electric Melting Furances, by J. M. Kane (Transac tions, American Foundrymen's Association, Vol. 52, 1945, p. 1351). ' u Control of Silicosis Hazard in the Hard Rock Industries. II. An Investigation of the Kelley Dust Trap for Use with Pneumatic Rock Drills of the Jackhammer Type, by T. Hatch et al (Journal of Industrial Hy giene, February 1932, p. 69).# * Modified Design of Hay Dust Trap, by P. S. Hay (Journal of Industrial Hygiene, January 1930, p.?8). n American Standard for Grinding, Polishing and Buffing Equipment Sanitatioi (American Standards Association, Z 43-1941). ** Swing Frame Grinder Dust Control, by J. M. Kane (The Foundry, August 1944). ** What We Make (B. F. Sturtevant Co., Catalog No. 500). M Ventilation of Motion Picture Booths, by P. Drinker and J. R. Snell (Journal of Industrial Hygiene and Toxicology, April 1938, p. 321). 81 How to Justify an Industrial Air Conditioning Investment, by P. J. Marschall (Heating, Piping and Air Conditioning, February 1952, p. 71). How to Design Exhaust Hoods for Quartz-Fusing Operations, by E. C. Riley et al (Heating and Ven tilating, April 1940, p. 23). 1060 CHAPTER 46 1956 Guide u a stnHv of Ouartz-Fiisine Operations with Reference to Measurement and Control of Silica Fumes by E.C. Riley and J. M. DallaVafie (U. S. Public Health Reports, Vol. 54, 1939, p. 532). u Ventilation of Open Tanks, by A. C. Stem (American Industrial Hygiene Association, Industrial Hy giene Quarterly, Sept. 1950). . . American Standard for Safety in Electric and Gas Welding and Cutting Operations (American Stand ards Association, Z 49.1). ' ' m Rules Relating to the Removal of Dust, Gases, and Fumes (New York State Department of Labor, In dustrial Code Rule No. IS, Jan. 1931). ri Energy Losses'at Suction Hoods, by A. D. Brandt and R. J. Steffy (A.S.H.V.E. Transactions, Vol. 52, 1945, p. 205)* . . a R^istance Test on Pipe, by A. Nutting (MecAantcoI Engineering, May 1938). * Design.of Injector for Low Pressure Air Flow, by G. E. McElroy (17. S. Bureau of Mines, Technical Pa per 678). o American Standard Safety Code for Ventilation and Operation of Open Surface Tanks (American Stand ards Association, Z 9.1-1951). . ' Design of Kitchen Range Hoods, by J. M. Dalla Valle (Heating and Ventilating, August 1953, p. 95). Tabulation of Atmospheric Contaminants Released by Open Surface Tanks, by Irving I^ssley (New York State Department, of. Labor,, Division of Industrial Hygiene, Engineering Unit Plates 161, 162, 163). u Chlorinated Solvent Exposures at Degreasing Operations, by K. M. Morse and L. Goldberg (Industrial Medicine, October 1943, p. 706). . . Ventilation of a Trichlorethylene Degreaser, by W. N. Witheridge and H. T. Walworth (Journal of Industrial Hygiene and Toxicology, May 1940, p. 175). -- - CHAPTER 47 INDUSTRIAL DRYING SYSTEMS Drying Terminology, Mechanism of Drying, Internal and External Conditions, Periods of Drying, Approximate Equations for Estimating Drying Time, Equi librium Moisture Content, Applications of Hygrometry to Drying, Dryer ' Calculations, Drying Methods and Equipment; Radiant, Conduction . and Convection Drying; Solution of Drying Problem THE term drying, in a broad sense, encompasses the removal of water, and occasionally other liquids, from gases, liquids, or solids. How ever, the common usage of the word confines the meaning principally to the removal of water or solvent from solids by thermal means. Dehumidi fication is the term that is commonly assigned to the drying of gases. This is usually accomplished by condensation or adsorption by various drying agents, and is treated in Chapter 38; Distillation, and more particularly fractional distillation,-is_&ssociated with the drying of liquids. It is usually more economical to employ, whenever possible, mechanical means of separating as much water as is practicable from the solid mate rials before undertaking drying or dehydration steps. These mechanical methods such as filtration, screening, pressing, centrifuging, or settling usually require much less power, and frequently less capital outlay, thereby making the operation cheaper in terms of cost per pound of water removed.' DRYING TERMINOLOGY1 The generally accepted definitions of terms used in drying technology follow; . ' Bound moisture refers to liquid (held by a solid) which exerts a vapor pressure.less than that of the pure liquid at the same temperature. Liquid may become bound by retention in small capillaries, by solution in cell or fiber walls, by homogeneous solution throughout the solid, and by chemical or physical adsorption oh solid sur faces. Bound moisture can be removed from a solid only under specific conditions of humidity in the external surroundings. Capillary flow refers to the flow of liquid through the interstices and over the sur face of a solid. It is caused by liquid-solid molecular attraction. Commercial-dry basis expresses the moisture content of a product as pounds of water per pound of solid as it leaves the dryer, per pound of commercially dry solid. The constant-rate period is that drying period during which the rate of water re moval per unit of drying surface is constant. The critical moisture content is that obtaining when the constant-rate period ends and the falling-rate period begins. Dry basis indicates the moisture content of a wet solid as pounds of water per pound of bone-dry solid. The advantage of using this basis is that the absolute amount of moisture loss is obtained simply by subtracting the moisture contents before and after drying. (See definition of Wet Basis.) Dryer efficiency is that fraction of the total heat, supplied by fuel, used to evaporate water. Overall efficiency is sometimes used to distinguish overall system efficiency from the efficiency of the drying space or evaporative efficiency. Equilibrium moisture content is that to which a given material can be dried under specific conditions of air temperature and humidity. Evaporative efficiency compares the amount of evaporation actually obtained in a dryer with that which would obtain by saturation of the air. " Thefalling-rate period is that drying period during which the instantaneous drying rate continually decreases. 1061 1062 CHAPTER 47 1956 Guide Fiber saturation point is the moisture content of cellular materials (wood, etc.) at which the cell walls are completely saturated while the cavities are liquid-free. It may be defined as the equilibrium moisture content as the humidity of the sur rounding atmosphere approaches saturation. ' ' Free moisture content is that liquid content which is removable at a given tempera ture and humidity. Free moisture may include both bound and unbound moisture. The funicular state is that condition in drying a porous body when capillary suction causes air to be sucked into the pores. Humidity denotes the amount of water vapor actually present in a gas, and is generally expressed as weight of vapor per unit weight of any gas. A hygroscopic material is one that may contain bound moisture. Initial moisture distribution refers to the moisture distribution throughout a solid when drying begins. Internal diffusion. Diffusion is a single-phase phenomenon; internal diffusion must therefore occur as solid through solid, liquid through liquid, or gas through gas. Internal diffusion occurs when the moving phase.obeys the fundamental laws of diffusion. The moisture content of a solid is usually expressed as moisture quantity per unit weight of volume of the dry or wet solid. A weight (dry or wet) basis is preferred. Moisture gradient refers to the internal distribution of water in a solid at a given moment in the drying process, the nature of which depends on the characteristics of the solid involved. A non-hygroscopic material is one that can contain no bound moisture. Pendular stale is that state of a liquid in a porous solid when a continuous film of liquid no longer exists around and between discrete particles and, therefore, flow by capillarity cannot occur. This state succeeds the funicular state. Unaccomplished moisture change refers to the ratio of the free moisture present at any time to that initially present. Unbound moisture in a hygroscopic material is that moisture in excess of the equi librium moisture content corresponding to saturation humidity. All water in a non-hygroscopic material is unbound water. Wet basis expresses the moisture in a material as a percentage of the weight of the wet solid. This basis is less satisfactory than the dry-weight basis on which the percentage change of moisture is constant for all moisture contents. Fig. 1 shows the relationship between the dry- and wet-weight bases, and indicates that when the wet-weight basis is used to express moisture content, a 2 or 3 percent change at high moisture content (above 70 percent) actually represents a 15 to 20 percent change in evaporative load. An evaporative increase of this amount might well increase the load above the capacity of a dryer. MECHANISM OF DRYING1 When a solid dries, two fundamental processes are involved: (1) the transfer of heat to evaporate the liquid, and (2) the transfer of mass as vapor and internal liquid. These two processes occur simultaneously, and the factors governing the rate of each process determine the rate of drying. In any commercial drying problem, a principal objective is to supply the required heat in the most efficient manner. Consequently, heat trans fer may occur by convection, conduction, or radiation, or by any com bination of these mechanisms. The various types of industrial dryers may be shown to differ fundamentally with respect to the method used for transferring heat to the solid. In general, heat must flow first to the outer surface of the solid and then into the interior. An important ex ception is drying with high frequency electrical currents where heat is generated within the solid, producing a higher temperature at the interior than at the surface, and consequently, causing heat to flow from inside the solid to the outer surfaces. Mass transfer in drying occurs as liquid or vapor flow, or both, within Industrial Drying Systems 1063 the solid, and as vapor flow from the external wet surfaces. The nature of liquid concentration gradients in solids during drying depends on the mechanism of internal liquid flow, and this mechanism, in turn, depends to a large extent upon the physical and chemical characteristics of the solid being dried. .: Internal vs. External Conditions A study of how a solid dries may be based on the interned mechanism of liquid flow, or on the effect of the external conditions of temperature, humidity, air flow, state of subdivision, etc., On the drying rate of the solid. The former procedure involves a fundamental study of the liquid flow conditions within a solid during drying. The latter procedure, al though less fundamental, is more generally used because the effects are z--- - ^1 J 40 / t /Z 30 1 . O 50 100 ISO 200 250 300 350 400 450 500 550 600 PER CENT MOISTURE-DRY BASIS . Fig. 1. Relation between Wet-Weight and Dry-Weight Bases easier to establish and the results have greater immediate application in dryer design and operation. ', Internal Mechanism of Liquid Flow. Internal liquid flow may occur by several mechanisms, depending on the structure of the solid.. Several mechanisms of flow are as follows: 1. Diffusion in continuous, homogeneous solids. 2. Capillary flow in granular and porous solids. 3. Flow caused by shrinkage and pressure gradients. 4. Flow caused by a vaporization-condensation sequence. 5. Flow caused by gravity. . . 6. Flow caused by an electrical potential, electro-osmosis. 7. Flow caused by temperature' gradients, thermal diffusion. Although more than one of these mechanisms of flow may be effective at one time, only one predominates as a rule at a given time in a solid during drying. However, a different mechanism may predominate at a different time in the cycle. The mechanism of moisture flow is usually established experimentally from a study' of moisture gradients. External Variables. The principal external variables involved in any drying problem are:. temperature, humidity, air flew, state of subdivision of the solid, agitation of the solid, method of supporting the solid, and the contact between hot surfaces and wet solid. All these variables do not necessarily occur simultaneously in one problem. 1064 CHAPTER 47 1956 Guide Industrial Drying Systems 1065 The curved portion of Fig. 2 is termed the falling-rate period, and, as shown in Figs. 3 and 4, it is typified by a continuously changing, rate. Point A, where the constant rate ends and the drying rate begins to de crease, is termed the critical moisture content. ... . The portion of the curves designated by CB represents a warming-up period, and it may, or may. not, be a significant item depending on the b' total time involved. Constant-Rate Period. Drying during the constant-rate period is equiv alent to evaporation from ,a free-water surface on the surface of the solid. The rate of drying in this period is determined by the rate of diffusion of water vapor through an air film at the wet surface of the solid. A con c; l stant rate of evaporation on the surface of the solid maintains the surface at a constant temperature, which, in the absence of other heat effects, is very nearly the wet-bulb temperature of the air. . If heat flows, to the surface of evaporation by radiation and . conduction, or both, in addition Time Fig. 2. Moibtube Content W vs. Drying Time 9* y Periods of Drying1 A typical drying time curve for a wet solid is shown in Fig. 2. This curve is a plot of the moisture content at any time in a solid undergoing drying. It is the usual method of presenting experimental drying data. Although Fig. 2 shows that the moisture content is subject to a continuous variation with time, a more precise illustration of the nature of this varia tion can be obtained by differentiating the curve and plotting the drying rate (pounds of water per hour per pound of dry material) against the moisture content (pounds of water per pound of dry material) as shown in Fig. 3, or plotting the rate of drying against time as shown in Fig. 4. These rate curves show that the drying process is not a smooth, continuous one in which a single mechanism controls throughout. The rate curve in Fig: 4 has the advantage of showing how long each drying period predom inates. . . Section AB on each curve represents a constant-rate period. In Fig. 2, it is shown by a straight line of constant slope dW/dff, which becomes a horizontal line on the rate curves in Figs. 3 and 4. ' TIME Flo. 4. Rate of Dbying, '. ` dW -jt vs. Time 6 UV . to convection, the surface temperature will be constant at some value between the air temperature and the wet-bulb temperature. This higher temperature in turn produces a higher constant rate of evaporation. In those dryers in which heat is transferred to a wet solid by conduction through hot surfaces, and heat transfer by convection is not a factor, the wet surfaces approach the boiling point temperature rather than a wetbulb temperature. When all the heat for evaporation in the constant-rate period is supplied by a hot gas, a dynamic equilibrium is established between the rate of heat transfer to the materia) and the-rate of vapor removal from the surface. This equilibrium between heat and mass transfer rates can be expressed as follows: . . ' v * n \ i i i iv\ dw h,AM de = x ksAAp where dw # =* drying rate, pounds of water per hour. (1) 1066 CHAPTER 47 -. 1956 Guide fc. .= total heat transfer coefficient, Btu per (hour) (square, foot) (Fahrenheit degree). .i A = area of heat transfer and evaporation, square feet. / X = latent heat of evaporation at ta, Btu per pound. k. = mass transfer coefficient, pounds per (hour) (square foot) (atmosphere). At = (t. -- U) = temperature difference between air and surface of evaporation, Fahrenheit degrees. U = air temperature, Fahrenheit. ' t. = temperature of surface of evaporation, Fahrenheit. . . AV = (p -- pi) = vapor pressure difference, atmospheres. , - V = vapor pressure of water at U, atmospheres. . Pt = partial pressure of water vapor in air, atmospheres: . When ht = hc, the coefficient of heat transfer by convection only, then t, under equilibrium conditions becomes U,, the wet-bulb temperature of the air, and p. is the vapor pressure at this temperature. If heat is also supplied by radiation, then ht is the sum (hc + hr) where.hT is the radia tion coefficient and hc is the convection coefficient, and t, becomes higher than the wet-bulb temperature. A similar result occurs when heat reaches the surface of evaporation by convection and conduction. When the surface is at the wet-bulb temperature; the value of Ap in millimeters of mercury, is almost exactly one-half the wet-bulb depression (t,, -- U,), in Centigrade degrees. Effect of Air Velocity. The principal effect of air velocity is on hc and k,,, since the rate of transfer of heat and mass in the constant-rate period depends mainly on the rate of diffusion of heat and vapor through the air film at the surface of the solid, and air velocity is the chief factor affecting the thickness of this film. The influence of air velocity may be expressed by the following relationship:3 . fto = 0.0128 <?-* (2) where ho = convection heat transfer coefficient, Btu per (hour) (square foot) (Fahren heit degree). G = mass velocity of dry air, pounds per (hour) (square foot). For estimating the constant rate in drying from plane surfaces with air flow parallel to the surface of evaporation and with no radiation or conduction effects, the following heat transfer expression can be used; dw de 0.0128GI)IIA (la X Ur) (3) where ( = wet-bulb temperature of the drying air, Fahrenheit degrees. Heat transfer coefficients, rather than mass transfer coefficients, should be used to estimate drying rates, because heat transfer coefficients are generally more reliable, and, unless the temperature of the drying surface is measured, it must be calculated from heat transfer considerations before mass transfer coefficients can be applied for drying-rate predictions. The assumption that the surface of drying is at the wet-bulb temperature of the air, introduces a more serious error in the computation of mass transfer than of heat transfer. Determination of True Surface Temperature. Frequently, radiation and conduction are of sufficient magnitude to cause the temperature of evap oration to exceed the wet-bulb temperature of theair.: When this occurs, it is necessary to estimate the true surface temperature in order to calculate Industrial Drying Systems 1067 the constant rate. This may be done by means of a heat balance equating the total heat transferred by convection, conduction, and radiation to the latent heat of evaporation. Constant-Bate Period in Through-Circulation Drying. The equation for estimating the rate of evaporation when air flows across a free water surface must be modified for the case of air-flow through a permeable bed of solids. The constant rate in through-circulation drying depends on the air rate, air temperature, air humidity, size of the particles making up the permeable bed, and physical characteristics of these particles.4 The following general expression for the constant rate in through-circula tion drying for the system water and air, was developed6 from experiments on the rate of evaporation of water from the surface of wet spheres and cylindrical particles with through-circulation of air: where dW 0.42aG"-"(aR) 0.37e,aG"Ati. DJ" - Xp.D" . W dW _ de ~ constant rate, pounds of water per (hour) (pound of dry stock). a -- drying area, square feet per cubic foot of bed volume, G = superficial mass velocity, pounds of dry air per (hour) (square foot), AHm logarithmic mean of inlet and outlet, humidity driving force across the air film adjacent to the particle through which the water vapor diffuses, pounds per pound (the surface humidity is taken as the humidity corres ponding to the wet-bulb temperature of the drying air), pi = bulk density of dry granular bed, pounds per cubic foot. Dv = average diameter of particle, feet. Atm = logarithmic mean difference between temperature entering and leaving the bed and the wet-bulb temperature, Fahrenheit degree). c, = humid heat, Btu per (pound of dry air) (Fahrenheit degree). X = latent heat of evaporation, Btu per pound. Equation 4 applies when the Reynolds number DPG/y is greater than 300, where a is the viscosity of the air stream. For values less than 300, a modification of Equation 4 has been presented.6 Evaporation from Liquid Drops. For the important problem of spray drying, evaporation rates of liquid drops must be estimated. Below a value of Reynolds number (DpG/y) of 10 for spherical particles, the heat transfer coefficient across the gas film surrounding the drop is given by where 2k, h Dr (5) h = film heat transfer coefficient, Btu per (hour) (square foot) (Fahrenheit de gree). fci = thermal conductivity of gas film, Btu per (hour) (square foot) (Fahrenheit degree per foot). Equation 5 is applicable when the Reynolds number for. liquid drops is less than 10. Drop diameters are almost always less than 500 microns, and usually in the range of 20 to 150 microns. The rate of evaporation of drops may be expressed in terms of heat transfer or mass transfer. In terms of heat transfer, the evaporation rate is given by the equation: 1068 CHAPTER 47 where da x - ~da = evaporation rate, pounds per hour. A similar expression based on mass transfer is . ; dtp 2rilfd,Zip` / - \ 1956 Guide (6) (*(i7\ ) where Af = molecular weight of the diffusing vapor. . d = diffusivity of the vapor, square feet per hour. T = absolute temperature of the gas, Fahrenheit degrees. R = gas constant, (cubic feet) (atmosphere) per (Fahrenheit degree), p. = vapor pressure at the particle surface corresponding to the liquid tempera ture, atmospheres. ' p. = vapor pressure of liquid in the drying medium, atmospheres. Both Equations 6 and 7 are based on the assumption that Equation 5 applies. If Equation 6 is integrated for a constant drop diameter (i.e., if it is assumed that the solid being dried in the liquid drop creates a struc ture which becomes rigid at a fixed Dp) and evaporation proceeds as from a pure liquid drop, an expression for the time of evaporation is obtained as follows: = W\PjD% _ (g) 12kf(td - J.) . where S = time, hours. W = water content of the drop as it enters the drying chamber, pounds per pound. p, = density of dry particle, pounds per cubic foot. The temperature difference between drop and gas (<0 -- Q is essentially constant for a single drop evaporating in a large mass of gas. However, in spray dryers this is not true, and an overall average temperature differ ence must be used in Equation 8 in this case. When the drop diameter varies as evaporation proceeds, the expression for the time of evaporation becomes mAI(P,,) - tfU'l 8fcf(( t) (9) . where pL = density of the evaporating liquid, pounds per cubic foot. Dpi = drop diameter at the start of evaporation, feet. Dpj = drop diameter of dry particle, feet. Equation 9 assumes that the drop density is essentially that of the liquid. Drying at Air Temperatures above the Boiling Point of the Liquid. When the temperature of the drying air is maintained above the boiling point of the liquid being evaporated, or when superheated vapors are used for drying, the usual equations for mass transfer, expressing rate of evaporation Industrial Drying Systems 1069 as a function of the vapor pressure difference, lose significance, since large errors are introduced in the expression for vapor pressure driving force due to its apparently small value. Such cases can be treated conven iently on a basis of heat transfer, since a temperature difference must always exist in order that drying may proceed. At drying temperature above 260 F, recirculation has no retarding effect on the drying process. Constant-Rate Period When Head, Transfer Depends on Conduction and Radiation. In indirect drying, where heat transfer and drying do not depend on the flow of heated gases, the drying rate depends either on heat conduction through retaining walls to wet material in contact with such sur faces, or on radiation, or both. This applies to drum dryers, agitated pan dryers, indirect continuous sheeting dryers, steam tube rotary dryers, vacuum rotary and vacuum tray dryers, and infra-red dryers. A principal difference between indirect drying and direct drying is that, with the former, the material is usually at a higher temperature than the surrounding air, so that heat is actually transferred to the air instead of from the air. Generally, the individual heat transfer coefficients for indirect dryers are difficult to determine or estimate, and therefore, an overall coefficient, as defined by Equation 10, is generally used: 5 = UA (/,, - t.) (10) where ? = rate of heat transfer, Btu per hour. U = overall heat transfer coefficient based on the temperature difference between the heating medium and the product, Btu per (hour) (square foot) (Fahren heit degree). . ft = temperature of the heating medium, Fahrenheit. . t, = temperature of the solid, Fahrenheit. The overall coefficient is a function of dryer type. Thus,, in agitated pan dryers, U depends on the degree of agitation, temperature of the sur face, physical properties of the wet material, etc., and will sometimes vary throughout a drying cycle as the physical properties of the solid vary with a changing moisture content. As long as U and the temperature difference in Equation 10 remain constant, a constant drying rate will be maintained. However, as drying proceeds the material temperature will begin to increase after some critical moisture content is reached, and, as in the case of direct dryers, a fallingrate period is encountered. U is frequently defined, for the entire drying period, on the basis of an overall mean temperature difference. There fore, q = UA (Aik (11) The Falling-Rate Period. In the discussion of the periods of drying, it was shown that the drying process is discontinuous, consisting of a period f a constant rate of evaporation and a period in which the rate contin uously decreases. (See Figs. 3 and 4). This latter period is usually designated as the falling-rate period. It begins when the constant-rate period ends at the critical moisture content. If the critical moisture con tent is less than the required final moisture content, the constant-rate period will constitute the whole of the drying process. On the other hand, ff the initial moisture content is less than the critical moisture content, as \\v *\i 1070 CHAPTER 47 1956 Guide in the case of some slow-drying materials, such as soap and wood, then no constant rate will appear, and the whole of the drying process will be in the falling-rate period. This period, in the most general case, can be divided into two zones which may be termed (1) the zone of unsaturated surface drying, and (2) the zone where internal liquid flow controls. The zone of unsaturated surface drying follows immediately after the critical point and results from a progressively decreasing wetted surface. With the surface no longer completely wetted, dry portions of the solid protrude into the air film, so that the rate of evaporation per unit of total surface is reduced. The effective wetted surface in this zone is frequently k a linear function of the water content, so that the curve representing rate of drying vs. water content of the solid is straight in this region, as shown ,i by line AD in Fig. 3. The mechanism of drying is essentially the same as during the constant-rate period. The zone where internal liquid flow is in control, is usually the second zone of the falling-rate period. In this phase the rate of internal liquid movement controls the drying rate, and in drying to low moisture contents, this period may be the principal factor determining the drying time. Studies of internal moisture flow have indicated the possibility of several controlling mechanisms, the more significant ones having been postulated previously as diffusion, capillarity and pressure gradients due to shrinkage. Of these mechanisms, internal moisture movement by diffusion has been treated extensively, while capillary flow and flow caused by shrinkage and r"'< ""l pressure gradients, have received only preliminary consideration. When diffusion does control in the falling-rate period, it obeys the same fundamental laws of diffusion as those applying to the diffusion of heat. On this basis, the integrated diffusion equation for the falling-rate period (for the case where the surface is dry or at its equilibrium moisture content and the solid has a uniform initial moisture distribution) expresses the average moisture content as a function of time as follows: W~ = -- g-tHoHLI1 4. - e-9d<,/JI,>* 4. -- g-tltH./tL)* 4- ... 1 - (12) W,,-W. 9 25 J I where W, Wo, Wo = the moisture contents, on a dry basis, at any time 0; at $ = 0, the start of the diffusional flow period; and in equilibrium with the external conditions, respectively, pounds of water per pound of dry solid. d = the liquid diffusivity, square feet per hour. L -- one-half the thickness of the solid layer through which the liquid is diffusing, feet. " In Equation 12 it is assumed that evaporation is occurring from two opposite faces of the solid. When evaporation occurs from only one surface, substitute the total thickness of the solid layer for L in Equation 12. Equation 12 is based on the assumption that d is constant. However, this is rarely true, and d has been shown to vary with moisture content, t temperature and humidity.7 ') When the time becomes large, a limiting form of Equation 12 is obtained as follows: W - Wo Wo - Wo IT* (13) Industrial Drying Systems 1071 From Equation 13 an expression for the rate of drying may be derived to give dW de,^ vM (w - Wo) 4b* wfiere dW/de = drying rate, pounds per (hour) (pound dry material). (14) Equation 14 states that the rate of drying, when internal diffusion con trols for long times, is directly proportional to the free moisture content (W -- IFe), the liquid diffusivity d, and that the time of drying varies as the square of the material thickness. However, Equation 14 holds only when (W -- We)/{Wa -- Wo) <0.6. When this ratio exceeds 0.6, the curve of drying rate vs. moisture content is concave upward. Equations 12, 13, and 14 hold only for a slab-shaped solid, the length ,of which-.is large compared with its thickness. .: The falling rate frequently can be expressed with fair accuracy over the required range of,moisture content by an equation similar to Equation 14: _ (?),= ~KOr-^) (15) where K is a function of the constant rate as follows: where - (dW/da)o (Wo - Wo) (16) (dW/de), = the constant drying rate, pounds per (hour) (pound dry material). Wo = the critical moisture content, poundB per pound dry material. Substituting in Equation 16 the proper expression for {dW/ddc) the value of K becomes ., ,, htitp -- to) " P^UWo - Wo) (17) and hence, the falling rate for this case is given by (W\ = _ *<* - Q(W - Wo) \de)! = p.L\(Wo - We) (18) For materials obeying Equation 18, the drying time varies directly as . the thickness. When the surface temperature in the constant-rate, period is at the wet-bulb temperature, C can be substituted for t, and 0.0128 Go s can be substituted for h, in Equations 17 and 18. ' The drying time for each case of the falling-rate period may be obtained by integration of Equations 14 and 18, respectively, to give: 1. Diffusion law 4b* (Wo - :d~?'g' \w - Wo) 2. Proportional-to-thickness law (19) ihLUWq - W.) . - log. Wo )Wo (20) & i tj : ! f; rf IH *i m*y f?1 i! .t 1072 CHAPTER 47 1956 Guide Table 1 gives an approximate classification of materials which are most likely to obey Equations 19 and 20. ( Equations 18 and 20 hold for cross-circulation drying. When through- circulation drying is involved, the appropiate constant-rate expression given by Equation 4 must be used to determine K in Equation 16. Thus, for through-circulation drying in the falling-rate period when Equation 15 holds, the rate is given by 0.37c,oG-e'(At)E - OP - OP.) p,\Ds?m{W' - TPJ (21) where the symbols have been defined for Equations 4, 12, and 16. Critical Moisture Content. In order to use the above equations for estimating the drying time in the falling-rate period, it is necessary to know values of the critical moisture content. Such values are usually difficult Table 1. Approximate Classification of Materials Most Likely to Obey ' Equations 19 and 20 Materials Obeying Equation 19 Materials Obeying Equation 20 1. Single-phase solid systems such as soap, gelatin, glue. . 2. Wood and similar solids below the fiber saturation point. ,, 3. Last stages of drying starches, textiles, paper, clay, hydrophilic solids, and other materials when bound water is . being removed. 1. Coarse granular solids, such as sand, paint pigments, minerals, etc. 2. Materials in which moisture flow occurs at concentrations above the equi librium moisture content at atmos pheric saturation, or above the fiber saturation point. to obtain without making actual drying tests which, in themselves, would give the required drying time and thereby obviate the necessity of the calculations. It appears that the constant-rate period ends when the moisture content at the surface reaches some specific value. If the rate of drying is great, the moisture gradients within the solid will be steep and the average moisture content considerably greater than that at the surface. It is for this reason that the critical moisture content (average through the ma terial) increases with increase in rate of drying,, and with an increase in thickness of the layer being dried. , Approximate Equations for Estimating Drying Time An estimate of the overall drying time for a given drying problem usually involves an estimate, of the time required for the constant-rate period, plus an estimate of the time for the falling-rate period. An ap proximate equation for the overall drying time applicable to the cross circulation drying of materials of the type listed in Table 1 as obeying Equation 20, may be written as follows: . (Wo - BQxLp. pJaOF, - Wo) Wo - W. Si -- So + Si -- hiUo-u) + ht(to-u) - og* w -- w. Wo - Wo Wo - Wo =B + log. Wo - Wo W. -- Wo (22) Industrial Drying Systems 1073 where . n poL\(.Wo " If.) 1' " h,(to - U) = K' . .. '' . ~- ` ' " = total drying time, hours. . ; Bo = drying time for constant-rate period, hours. . St = drying time for falling-rate period, hours. ,. . .. W0 = initial moisture content, pounds per pound of. dry solid. . Wo = critical moisture content, pounds per pound of dry solid. Wo -- equilibrium moisture content, pounds per pound of dry solid. W = moisture content at time St, pounds per pound of material. . ht =, total overall heat transfer coefficient Btu per (hour) (square foot) (Fahren heit degree). . to = -air temperature, Fahrenheit. . . . Y., to = temperature of surface of material, Fahrenheit. L = depth of material in tray, feet. . - v ' X = latent heat of evaporation at t,, Btu per pound. p, = density of dry solid, pounds per cubic foot. :, . : . Equation 22 will apply to those materials satisfying Equation 20 when drying to very low moisture content is not involved. For through-circulation drying, an expression similar to Equation 22 is obtained. Thus, the total drying time for through-circulation drying is given by c.aGp t'iAt)m ' The drying times estimated from Equations 22 and 23 apply only to cross-circulation drying and through-circulation drying, respectively. Drying times for other methods, such as rotary drying or drum drying, must be estimated by other methods.. Equilibrium Moisture Content In the drying of solids it is important to distinguish between hygroscopic and' non-hygroscopic materials. A hygroscopic material is one which retains a definite'percentage of moisture under definite conditions of air humidity. This bound moisture is in a state of equilibrium with the water vapor in the surrounding air, and a decrease in the water vapor content will decrease the. amount of equilibrium bound water. Water so retained by a solid in equilibrium with the humidity of the surrounding air, is designated as the equilibrium moisture content. Such moisture may be held as adsorbed surface films or condensed in fine capillary structures at reduced vapor pressure. '. ." The equilibrium moisture content varies with the temperature and humidity of the surrounding air. 'Consequently, any correlation of equili brium moisture content should take these two factors into account/ .. How ever, at low temperatures, e.g., 60 to 120 F, a plot of equilibrium moisture content'us. percent relative humidity, expressed as 100 (p/p,), is essentially independent of temperature. Such a plot usually results in a curve of double curvature with a point of inflection (see Fig. 5). . . The equilibrium moisture content at a given relative humidity is not 1074 CHAPTER 47 1956 Guide independent of temperature, for all temperature ranges. As the tempera ture increases at a given relative humidity, the equilibrium moisture con tent tends to decrease. A limiting condition exists when temperatures above the boiling point of the adsorbed liquid are encountered. In such cases, relative humidity loses its significance with regard to equilibrium moisture content, and complete dryness of most hydroscopic materials is possible, even when a large amount of vapor exists in the atmosphere. This makes possible drying by means of superheated vapors. In the special case of the dehydration of hydrated inorganic salts, such as copper sulfate, sodium sulfate, and barium chloride, temperature and humidity , are very important in obtaining the desired degree, of dehydra tion. Thus, in the drying of wet salt crystals to obtain a product with the maximum number of molecules of hydrate water, it is necessary to dry under closely controlled conditions of air temperature; and humidity. Generally, the temperature is low and the humidity is high.; " The equilibrium moisture content of a hydroscopic material may be determined in a number of ways. The requirement for any method is a Industrial Drying Systems 1075 conditions of air humidity and temperature. Drying costs can be un necessarily high if a material is dried to a moisture content less than.that which it normally possesses in equilibrium with atmospheric air. For example, if a dryer dries a material to 1 percent final moisture, and on standing under normal atmospheric humidities it regains moisture to 5 percent, the material is considered to be overdried, so that probably the dryer would be capable of a considerably higher capacity and efficiency with a 5 percent final moisture content. Applications of Hygrometiy to Drying Drying of a-solid by hot air or hot gases may be divided into two proc esses: (1) transfer of heat to evaporate the water, and (2) removal of the Fio. 5. Typical Equilibrium Moisture Content Curves1 source of constant humidity and constant temperature air into which the sample may be placed. The determination may be made under either static or dynamic conditions, the latter being preferred if the data are to be used for drying calculations. ' Probably the simplest static procedure is to place a series of samples in ordinary laboratory desiccators over sulfuric acid solutions of known concentration, which thereby produce atmospheres of known relative humidity. The sample in each desiccator is weighed periodically until a constant weight is Obtained. The moisture content at this final weight represents the equilibrium moisture content for the particular relative humidity involved. The value of equilibrium moisture content so ob tained will depend on whether it is reached by losing moisture, as in drying, or by gaining it, i.e., whether the sample is at a moisture content higher or lower than the equilibrium value. The equilibrium moisture content reached by losing moisture, i.e., by drying, is generally higher than that reached when moisture is adsorbed, as shown in Fig.. 5. . The equilibrium moisture content of a solid has particular significance in drying because it represents a limiting final moisture content for specific vapor by the air or gas stream. Likewise, two processes are involved in the design and operation of direct.dryers: (1) the estimation of the drying rate.or drying time, and the effect of the external variables on the drying rate; and (2) the calculation of the heat and air quantities required. The first estimates concerning drying time have been considered in the first part of this chapter. The second calculations are based on the use of the psychrometric chart, Fig. 6. In drying, the humidity chart finds its greatest utility in analyzing the operation of existing dryers, in making design calculations, and in checking calculations of air quantities, it is equally useful in interpreting the humidity-temperature relations within the dryer. The adiabatic cooling fines on the humidity chart indicate the relation between the temperature and the humidity which are present in air passing through an adiabatic dryer, i.e., one in which all of the sensible heat given up by the air in cool ing is used to evaporate water from the wet stock. Referring to the section of the humidity chart shown in Fig. 7, where AB is one adiabatic satura tion fine, it follows that air entering an adiabatic dryer at temperature ti 1076 CHAPTER 47 . - 1956 Guide and a humidity Hi will cool, following this cooling line toward point A. Air leaving with a humidity Hz will consequently have cooled to t*, the wet-bulb temperature of the air throughout the dryer being U,.- When heat is lost to the surroundings, the operation is somewhat lower than ts, so that the actual humidity-temperature relation is represented by the line Bb, having less slope than the adiabatic saturation line. The ratio (ti -- tj)/(ti -- t3) then gives a measure of the evaporative efficiency of the dryer. For the case of dryers containing steam coils maintained at a con stant temperature, the humidity-temperature relation is obviously repre sented by the vertical line Be, assuming the initial and final humidities to , be Hi and H2 as before. The heat supplied within the dryer itself is usually less, but may be greater, than the total heat requirements of the dryer. If less, the cooling is indicated by some such line as Bd, and if greater, by a line such as Be having a positive slope. ' Industrial Diying Systems 1077 The use of Fig. 8 in practical drying problems is as follows: Since the drying conditions of temperature and relative humidity are fixed, the corresponding absolute drying rate is read from Fig. 8. This value is then multiplied by the correction factor corresponding to the air velocity employed. The rate so obtained, however, does not include any effects of radiation or of conduction through unwetted surfaces. These effects tend to increase the rate of evaporation so that the chart is conservative.3 It has been demonstrated empirically for certain materials that the rate of drying during the falling-rate period is approximately proportional to the free water content of the material. Actual calculations of drying time ' Fio. 7. Humiditt-Temperatube Relations in Dryers1 DRYER CALCULATIONS As shown in the foregoing part of this chapter calculations for drying during the constant-rate period are different from those applying to the falling-rate period, and in contrast are subject to relatively simple mathe matical analysis. , The constant rate of drying by convection is directly proportional to the temperature difference between air and wet solid, and also proportional to the 0.8 power of the air velocity as shown by Equation 3. Usually the wet surface is assumed to attain the wet-bulb temperature of the air passing over it, and evaporation takes place at a constant rate under equilibrium conditions. This is a conservative assumption, however, and when con duction and radiation effects occur, the constant rate may be increased by 30 to 60 percent over that for pure convection. Fig. 8 permits a ready estimate of the constant drying rate for various air temperatures and humidities. The chart is based on the difference between the dry-bulb and wet-bulb temperatures of the entering stream of air, and on an air velocity of 300 fpm. It may be assumed satisfactory for tray drying of any material in the constant-rate drying period. It does not apply to rotary or through-circulation drying. A curve for correcting the air velocity in any given problem is incor porated in Fig. 8. This curve is based on the variation of drying rate with the 0.8 power of the velocity, as given by Equation 3. during the falling-rate period for this case require only a knowledge of the critical moisture content and the constant rate. For other cases of the falling-rate period, calculations are not feasible. Consequently, it is best to determine drying times for design purposes by means of pilot tests. However, when tests are not feasible, drying times may often be estimated approximately from Equations 22 and 23. ' The following nomenclature will be used in the discussion of design cal culations: H = humidity ratio of air, pounds of water vapor per pound of dry air. A, = pounds of dry air supplied to the dryer per unit of time. S = pounds of stock dried per unit of time in a continuous dryer. S' = pounds of stock charged per batch to a discontinuous dryer. 8 = time, hours. Q = total heat supplied to the dryer, Btu. 1078 CHAPTER 47 1956 Guide t = air temperature, Fahrenheit. . t' = stock temperature, Fahrenheit. i t" = average stock temperature over short time interval, in a batch dryer, Fahr enheit. . tw -- wet-bulb temperature, Fahrenheit. Si = specific heat of the stock, Btu per pound. . Q,, = total radiation and conduction losses, Btu per hour. W = pounds of water per pound of dry stock. r X = heat of evaporation of water, Btu per pound. c. = humid heat of air, t .e., heat necessary to raise 1 lb of dry air + H lb of Bteam 1 F deg. Subscript (1) designates conditions at the point where the material in question (air or stock) enters, and (2) where it leaves the dryer. Air dryers may be divided into two classes, batch, and continuous. In any continuously operating dryer, the relation between moisture content of the stock and quantity of air required for the drying operation is given by the equation N* (H, - Hr) = S(JF, -- Wi) (24) where H? is constant. In discontinuous dryers, the drying operation is given by the equation dW . NJLHr-Hr) = S'--d$ . (25) where Hi is a variable during a portion of the cycle. , J| |p % & 0 ' ftft kv In the continuous dryer, the heat consumption per unit time is ? = N.C.r(ti - k) + N.(\i + i, - - Hr) + S(fr - J',)(s, + IF,) + Q,,.(26) 9 .. p Equation 26 assumes continuity of operation. For charge or batch 0 operations, the total time of the drying cycle may be broken up into a number of periods, sufficiently short so that over each period average values of. t, t' and H may be employed, provided the third term of the .0; right hand member of the equation is modified to read: - t'r) (s, - Wr) and in the second term t'i be replaced by t'l + t"r 2 Theoretically, these periods should be very short and the equation inte grated. Practically, the error introduced by using a small number of long periods and employing average values of the variables over each, is not serious. The evaluation of Equation 25 may be approximated in a similar manner. . The first term of the right hand member of Equation 26 represents heat lost as sensible heat in the effluent air. In many drying operations this becomes excessive. Each pound of air supplied should remove the maxi mum amount of moisture. This is best accomplished by bringing the air into contact with the stock with sufficient intimacy so that the air leaving Industrial Drying Systems 1079 the dryer is saturated, or nearly so. Counter-current, as against parallel, flow of air and stock gives rise to optimum operating conditions, resulting in a minimum quantity of air required (1V,,), and a corresponding minimum loss, as sensible heat, in the exit air. Similarly, continuous operation is superior to intermittent operation. Despite the fact that the sensible heat loss increases with the rise in temperature' of the air, the percentage of heat lost from this source de creases if the increase in moisture carrying capacity of the air (due to high, temperature) is actually utilized. To secure maximum thermal effi ciency in drying, a high drying temperature and high saturation of the outlet air are imperative. . . . . . The second term of the right member of Equation 26 represents the latent heat of evaporation of the water plus the heat to raise this water to the temperature of evaporation. The third term of the equation represents heat to raise the temperature of the stock plus the water which remains unevaporated in the stock. . The changes taking place in the air during the drying process can be illustrated on the skeleton psychrometric chart, Fig. 9. The case illus- Fig. 9. Changes in Aib DubingDbying Pbocess trated is typical of tunnel and rotary dryers where heat is applied to the aar at one point only. After the first adjustment stage, during which both the material and the dryer reach the working temperature, the only heat losses from the dryer are those of radiation and conduction from the hous ing, and these are practically negligible for an insulated dryer. Hence, the drying process can be considered to be adiabatic.' If 100 percent outside air is used, the air can be considered to enter at point A, Fig. 9 (the prevailing outside air condition), and be heated to point B (the maximum permissible temperature fm or the temperature determined by previous test). As the air evaporates moisture, it cools along the constant wet-bulb line BD to point C. The difference between f /no*?*'ure content of air at B and at C represents the moisture pick up of the air. The maximum possible pick up from B to D is never achieved in practical dryers, the actual pick up being anywhere from 10 to 75 per cent of the maximum. J-n.or^er to. conserve heat and to control the wet-bulb temperature at winch the drying takes place, recirculation is used. The process is shown on Fig. 9. The outside air at A is mixed with recirculated air until the moisture level is raised to the desired point. The mixture is represented lit point M, the heaters heat the mixture to the desired dry-bulb temperature/n, at point S. The moisture is picked up from S to L. Point L is the condition at which air is exhausted. 1080 CHAPTER 47 1956 Guide Actual dryer operation is somewhat more complicated because even if radiation and conduction losses are neglected, the wet-bulb temperature of the air remains constant only as long as surface evaporation of water is taking place. When. sub-surface evaporation is occurring, some heat from the air is used to heat the material and hence, there is a drop in wetbulb temperature. Fig. 10 illustrates the drying process in a tunnel dryer in which the air is flowing parallel to.the product.2 In' design calculations using Equation 26, the following steps outline the procedure: < .; . 1. The unit drying rate, pounds of water per hour, is determined from the experi mental drying time curve and the amount of product to be dried per hour. The drying time may also be approximated from previous experience. 2. The experimental data or experience also determine the drying condition, i.e., point L Fig. 9. This fixes Hj. Where experimental data are lacking L may be ap proximated from RegainTables (see Chapter 45 Industrial Air Conditioning) since the relationship between the vapor pressure in the product and in the air at equilibrium for the desired final moisture content must prevail in the dryer. The air temperature must be not greater than the maximum permissible product temperature. Fig. iu. 'FEMPEKATuaii AIN U 1*AUJOiUlVil Parallel Flow Air and Product . 3. The rate of air circulation N must be determined and also the supply air con dition S. In the design of some dryers, such as rotary or tunnel types, it is customary to determine S first and then to calculate the air rate N. In other types of dryers, such as tray dryers or through circulation dryers, where a fixed air velocity is main tained, N. is calculated first and then point S is found. Because of the many vari ables involved, it is generally not possible to select S except, on the basis of past ex perience or on the basis of experimental drying tests. . . " 4. The prevailing outside air conditions establish point A and hence, the line AL. The.percent of recirculated air can then be calculated. 5. The physical arrangement of the dryer must then be selected to handle the desired quantity of product, and at the same time circulate the calculated air quantity at the desired velocity. . 6. Equation 26 can then be used to calculate the heat requirements. DRYING METHODS AND EQUIPMENT Drying systems are sometimes classified according to the method of heat transfer that is employed, since the entire problem of drying resolves itself into individual problems of heat transfer and the thermodynamics of air and water vapor. The methods of heat transfer are radiation, con duction and convection. Many types of dryers have been built on these principles for different purposes. . . . Drying systems can also he classified, according to the method of product handling, as batch operation, semi-continuous and continuous. Radiant Drying Sun drying, the oldest form known to man, is still practiced where the material is amenable to such treatment, where the necessary time can be allowed, and where there is little danger of rain or atmospheric pollution. Industrial Drying Systems 1081 In artificial systems, radiating surfaces, heated by steam, electricity or other means, afford a good method of heat distribution and control. Ra diant heating sets up convection currents, and in low-temperature dryers only about one-third to one-half of the total heat for evaporation is actually supplied to the material by radiation. At high temperatures the radiation output increases rapidly, according to the fourth-power law. The total radiation may be computed by the equations and tables given in Chapter 5. In general, fins and irregular surfaces do not increase radiation, hence, the area to be used in calculations is the area of a smooth-surface envelope enclosing the radiating elements. A certain amount of air circulation is required through a radiant dryer in order to carry off the vapor. Radiant heat from infra-red lamps has been accepted by certain in dustries as practicable for their specific problems. An example of success ful application is found in the drying of lacquers. Lacquers and similar surface films can be very effectively dried by radiation. Special electric lamp units have been developed which give off a high percentage of infra-red and similar heat rays. For continuous manufacturing processes these units are mounted in tunnels through which conveyors pass. For- local applications, as for example paint drying in automobile repair shops, they may be mounted on portable racks. Ob jects of relatively large surface area in proportion to their weight, and fabricated materials having a rather high heat absorption, may be: satis factorily heated by such a source. For drying, baking, pre-heating and de-hydrating, where a low tem perature infra-red heat source is desired, or where use of glass-enclosed radiant lamps is objectionable for safety reasons, electric heating units employing low temperature metal sheathed resistors, are available. . Conduction Drying Drying rolls or drums, Fig. II,8 flat surfaces, open kettles and immersion heaters are examples of the direct-contact method. Intimate contact of the material with the heating surface is important, and in some cases agita tion is desirable tp increase the uniformity of heating or to prevent over heating. Greatest resistance to heat transfer occurs on the air side of the material being dried. The rate of heat transfer from the surface of the heated material to the air, and Hence the rate of drying, may be increased by (a) forced convection or air circulation, and (b) vacuum operation to lower the boiling point of the liquid being evaporated. A rather interesting method of conduction drying was put into practical use during the war for the drying of blood plasma, and has since been expanded to other fields such as the preservation of bacteria and other micro-organisms. This has come to be known as freeze drying or drying by sublimation. The material to be dried is first frozen and then placed in a high vacuum chamber connected to extremely low temperature con densers. The water is removed by vaporizing from the solid directly to the gas without ever becoming liquid. Convection Drying (Direct Dryers) A limited amount of convection drying takes place in almost any dryer such as those described in the preceding paragraphs. However,-to be 1082 CHAPTER 47 1956 Guide Industrial Drying Systems Cxmaust 1083- classified as a convection dryer the principal squrce of heat is the heated air or- other gases circulated in the dryer. There are a number of mechan ical means of accomplishing this circulation of air or gases, each of which has some particular virtue. Brief descriptions of some important types of convection dryers follow: Rotary Dryers. These dryers are cylindrical drums which cascade the material being dried through the air stream. (See Fig. 12). The driers may be heated directly or indirectly, and the air circulation may be paral lel or counter-flow. A variation is the rotating louver type diyer, which introduces the air beneath the flights thus securing very intimate contact. Cabinet and Compartment Dryers. These are generally considered batch dryers wherein each charge is dried to completion before, removal.8 A wide range includes types from the heated loft with only natural con vection, and usually poor and non-uniform drying, to the self-contained units with forced draft and properly designed baffles which give positive results. It is also possible to evacuate some of the systems for low tem perature drying of delicate or hygroscopic materials. These dryers are usually loaded with material spread in trays to increase the exposed surface. The trays are loaded directly into the diyer or may be stacked on trucks which are wheeled in. (See Fig. 13) . 1 ' ' '' ' Tunnel Dryers. Tunnel dryers are a modification of the compartment dryer, and as a rule are continuous or semi-continuous in operation. Heated air or combustion gas is usually circulated by means of fans, although a few natural draft units are still in use. The material is handled on trays or racks on trucks, and moves through the dryer either intermittently or continuously. The air flow may be parallel, counter-flow or a combina tion of the two, obtained by center exhaust. Further, the air flow may be across the surface of the trays or up or down through the bed, or in any wcr MATtftiat 13.Fig. Compabtment Dbyek, Showing Tbucks, with Aib Circulation8 combination of directions. By reheating the air in this type of dryer or recirculating it, a high degree of saturation is achieved before exhausting the air. This reduces the waste of sensible heat. A variation of this type dryer is the strictly continuous type having one or more mesh belts which travel through the dryer carrying the prod uct, such as Fig. "14. Innumerable combinations of temperature) hu midity and air direction and velocity are possible. The labor requirement is low on such a dryer, as it can be loaded and unloaded mechanically. There is the disadvantage of hot air leaks at the entrance and exit, although these can be minimized by means of baffles or inclined ends where the material enters.and leaves from the bottom. Spray Dryers. In recent years the spray dryer has become important for the drying of liquids in many fields, especially in the food industry. The liquid is atomized by means of pressure nozzles, air jets or centrif ugal bowls into the air stream of a tower or chamber. Inlet air tempera tures may run from 250-300 F up as high as 1200 F. Drying times are very short because of the minute particle size. Particles as small as 5 to 10 microns are formed in spray dryers. The dry powder is separated from the air by cyclone separators which are sometimes followed by cloth bags or scrubbing towers. Because of the high inlet temperatures and the relatively large volume of air required, the efficiency of the spray dryer is not too good and, conse quently, is seldom used for dilute solutions (less than 30 percent solid). Fig. 15 shows a typical arrangement for a spray drying system.* A common and important feature of all spray processing is the direct conversion of the spray liquid to a granular product suitable for packaging Fig. 12. Cboss Section and Longitudinal Section Thbough Cikculation Dbybb* Fig. 14. Section op Continuous Dbteb, Blow-Thbough Type 1084 CHAPTER 47 1956 Guide Industrial Drying Systems Step 1: Let x = pounds moisture at final condition. Then, jjjjg = 0.005 1085 or, x = 4.5 lb moisture and therefore the solid will amount to 895.5 lb. Likewise the weight of the initial moisture x can be found from x 895.5 + x 0.19 i; or, x = 210 lb. The weight of moisture to be removed is 205.5 lb per hour, and wet material enter ing dryer is 1105.5 lb per hr. without grinding or other intermediate handling. Another aspect is the unusually high rate of drying attained. In a well designed system 15 to 30 seconds is a fair time for the passage of the sprayed particle through the drying zone; the particle temperature need riot rise materially above the Step 2: Previous tests indicate that a I in. layer of powder gives satisfactory re suits, and that a desirable air velocity is 50 fpm applied at a right angle to the belt. Based on :45 min (J hr) drying time, thoeortdryer holding capacity will have to be 1105.5 X 0.75 = 830 lb of wet material or = 8.45 cu ft of material. wet-bulb temperature of the drying air. This makes the process partic ularly adaptable to the drying of heat-sensitive material, some of its Assuming a 48 in. wide belt with an effective 42 in. width for the product, each foot of belt length carries 0.146 cu ft or 14.3 lb of wet material. Hence, the linear feet of most important applications being the drying of milk, eggs, potato flour, belt must be = 58_ftand the total area of exposed product is 232 sq ft. Based on soap and blood.9 50 fpm velocity directed at a right angle to the belt the total air circulation will be SOLUTION OF TYPICAL DRYING PROBLEM 232 X 50 = 11,600 cfm. . For space economy and in order to expose periodically fresh layers of powder to air, >MMI1' Since there are so many types of dryers which may be used, and so many special conditions surrounding each particular problem, it is usually a multiple vertical belt arrangement (Fig. 16) with belts traveling in opposite direc tions, is selected. Three belts each 19.4 ft long will be required. Fig. 16 illustrates recommended that those having experience with the dryer to be used be consulted. The following example, however, will serve as a guide for typical dryer calculations.10 / the physical arrangement of the dryer.10 The housing will be about 25 ft long, 8 ft wide and 7 ft high. Step S: At the drying conditions of 160 F dry-bulb and 100 F wet-bulb, the air moisture content (from Fig. 6) is 0.028 lb per pound of air. Make-up air will be Example 1: Assume 900 lb per hour of ceramic powder is to be produced. The powder has a specific heat of 0.22 and density of 98 lb per cu ft, wet. Initial moisture assumed at 80 F dry-bulb and 72 F dew-point (summer weather), or a humidity of 0.0168 lb per pound of air. The pick-up is therefore 0.0280 -- 0.0168 or 0.0112 lb per content iB 19 percent on a wet basis; final moisture content is to be one-half of one pound of air. Then q = 1^400 lb of air per hour or 307 lb per inin. percent on a wet basis. .^ A continuous belt dryer is a logical choice, and previous experience indicates that At the elevated temperature, the total air quantity of 11,600 cfm represents 675 lb rubber belts will withstand temperatures up to 200 F, which is also about the highest . of air per min. Hence, desirable product temperature. Experience also indicates that a drying time of 45 min is possible at about 160 F dry-bulb and 100 F wet-bulb. Make-up air = 46 percent Recirculated air = 54 percent Load -7 ' ^ , Fffeciivt Belt Lenath A~\ QspsCJ cppp c^p ,, iv 1 1 --------- , |L-0) Step 4' Although the drying condition and drying rate should preferably,be de termined from experience or test results, the drying conditions can sometimes be estimated if the regain characteristics of the product or a similar product-are'known*. In this case the regain characteristics of clay could be used as a guide. Inspection of regain data for typical clays indicates that at about one-half of one percent the vapor pressure of the moisture in the product is about 0.7 in. Hg less than the vapor pressure of free moisture at the product temperature. An assumption is made that the product temperature approximates the air wet-bulb temperature. If an assumption is made regarding the percent recirculated air the desired vapor pressure in the dryer can be estimated. For example assume a use of 46 percent outside air or 307 lb per min. Then the moisture pick-up -- = 0.0112 lb per pound of air, with a consequent F . 16.ig Continuous Belt Dryer fob Ceramic Powder total of 0-0168 + 0.0112 == 0.0280 lb of moisture per pound of air in the leaving outside ir, which has about 1.25 in. Hg vapor pressure. This is assumed to be the vapor presure of the moisture in the product, and thus the vapor pressure of free water at prod uct temperature can be 1.25 + 0.7 = 1.95 in. Hg. The temperature corresponding to w-f !?'iu 118 ^ ^ anc* ^us the air wet-bulb can be estimated to be 100 F. At 100 F et-bulb temperature and 0.028 lb moisture per pound of air, the dry-bulb tempera- anff 18 j F* Obviously, the assumed percentage of recirculated air affects the re ts, and therefore it is important that it be based on experience. About 50 percent circulation is reasonable for the type dryer considered in this example. I } t I' -5 f, -1086 CHAPTER 47 1956 Guide Steps; The pick-up of moisture per pound for the total air circulated is 6Q y 675 " 0.0051 lb. 0.0280 -- 0.0051 = 0.0229 lb moisture per lb of air for the supply air. Assuming an existing wet-bulb of 100 F, the supply air dry-bulb will be 182.F. The mixture of recirculated air at 160 F dry-bulb and 100 F wet-bulb, with outside air at 80 F dry-bulb and 72 F dew-point, will be at approximately 120 F dry-bulb and 89 F wet-bulb. ' Step 6: The heat required may be determined from Equation 26 by substitution of the following values: AT. = 307 X 60 = 18420 lb of air per hr; iS = 900 lb; c. = 24 + 0.45(0 028 ^ 0 022g) = 0.251:4. = 80F;42 = 10OF;42' = 100F;X = 1100 (approx.); W = 0.005 lb; s. = 0.22. Q = 18420 (0.251) (160 - 80) + 18420 (110 + 160 - 100) (0.028 - 0.0168) + 900 (100 - 80) (0.22 + 0.005) + QrC = 609,000 Btu per hr + .QTM The heat input requirement is therefore 609,000 Btu per hr plus radiation and con. vection losses (Qtt) which may. be computed .from the known construction of" the dryer surfaces and the heat transfer coefficients. . Summer conditions were used in Example 1 in order to obtain the maximum heat requirement which would be the case, except under the unusual condition where radi ation and conduction losses are a large percentage of the.total. In winter it is usually possible to take advantage of drier makeup air, and either speed up the process or operate at a lower dry-bulb temperature. Controls for the system selected for Example 1 would consist of a thermo stat in the main return air duct controlling the heat input to maintain constant dry-bulb temperature. A wet-bulb controller in the return cir culating, duct would maintain constant desired wet-bulb temperature by simultaneous positioning of three sets of dampers in the makeup air, the exhaust air and the recirculated air ducts. - LETTER SYMBOLS USED IN CHAPTER 47 A = area of heat transfer and evaporation, square feet, a = drying area, square feet per cubic foot of bed volume. B = a constant (for use in Equation 22). B' = a constant (for use in Equation 23). c, = humid heat, Btu per (pound of dry air) (Fahrenheit degree), d = diffusivity of the liquid or vapor, square feet per hour. Dp = average diameter of particle, feet. Dp. = drop diameter at start of evaporation, feet. Dp, = drop diameter of dry particle, feet. e = Naperian base of logarithms = 2.718. G = mass velocity of dry air, pounds per (hour) (square foot). AHm -- logarithmic mean of inlet and outlet humidity driving force across the . air film adjacent to the particle through which the water vapor diffuses, pound per pound. (The surface humidity is taken as the humidity cor responding to the wet-bulb temperature of the drying air). Ht = humidity ratio of entering air, pounds of water vapor per pound of dry air. . Hi = humidity ratio of leaving air, pounds of water vapor per pound of dry air. h = film heat transfer coefficient, Btu per (hour) (square foot) (Fahrenheit degree)* he = coefficient of heat transfer by convection, Btu per (hour) (square foot) (Fahrenheit degree). .,, ,, , , r h, = coefficient of heat transfer by radiation, Btu per (hour) (square foot; (Fahrenheit degree). , ht -- total gas film heat transfer coefficient, Btu per (hour) (square foot; Fahrenheit degree). K = a constant (a function of the constant drying rate). Industrial Drying Systems 1087 ki = gas film thermal conductivity, Btu per (hour) (square foot) (Fahren heit degree per foot). *. = mass transfer coefficient, pounds per (hour) (square foot) (atmosphere), L = material thickness, feet. M = molecular weight of the diffusing vapor. Nt = dry air supplied to the dryer, pounds per. hour. . . Ap =* P. -- P* = vapor pressure difference, atmospheres. . ' vapor pressure of water at 4,, atmospheres. . vapor pressure at the particle surface corresponding to the liquid tem perature, atmospheres. '- Pi = partial pressure of water vapor in air, atmospheres, P* = vapor pressure of liquid in the drying medium, atmospheres, Qrt = radiation and conduction loss, Btu per hour, Q = total heat supplied to dryer, Btu. q = rate of heat transfer, Btu per hour. R = gas constant (cubic feet) (atmospheres) per (Fahrenheit degree), S = weight of stock dried in a continuous dryer, pounds per hour, S' = weight of stock charged in a discontinuous dryer, pounds per batch, 3 = specific heat of stock, Btu per pound, T = absolute temperature of the gas, Fahrenheit, 4, = air or gas temperature, Fahrenheit, 4h = temperature of the heating medium, Fahrenheit, 4. = temperature of particle, solid or surface of evaporation, Fahrenheit, 4 wet-bulb temperature of drying air, Fahrenheit, 4i = entering air-temperature, Fahrenheit. 4. = leaving air temperature, Fahrenheit, - h' = entering stock temperature, Fahrenheit, w = leaving stock temperature, Fahrenheit. t" = average stock temperature over short interval, of time, in batch dryer (4i" = entering, 4j" = leaving) Fahrenheit. A4 = (4.4.) = temperature difference between air and surface of evapora tion, Fahrenheit. A4m = logarithmic mean between temperature entering and leaving the bed and the wet-bulb temperature, Fahrenheit. ' ' U = overall heat transfer coefficient, Btu per (hour) (square foot) (Fahren- ' heit degrees temperature difference between heating medium and prod uct). W : moisture content on dry basis at any time 9, pounds of water per pound, Wt cri tical moisture content, pounds water per pound dry material, Wi water content, dry basis, of the drop as it enters the drying chamber, pounds per pound of dry solid. ' w. moisture content at equilibrium with external conditions, pounds per pound dry material. Wo = initial moisture or moisture content at start of diffusional period pounds per pound. . ' w = pounds of water. dW da = drying rate, pounds of water per (hour) (pound dry material). (). = constant drying rate, pounds per (hour) (pound dry material). (S), = falling rate, pounds water per (hour) (pound of dry stock). dw He = drying rate or rate Of evaporation, pounds of water per hour (Eq. 1). time, hours. = drying time for constant rate period, hours. = drying time during falling rate period, hours. e% total drying time, hours. x : latent heat of evaporation at 4,, Btu per pound, /* : viscosity of the air stream, pounds per (hour) (square foot), PL density of evaporating liquid, pounds per cubic foot, p* : bulk density of dry granular bed, density of dry particle, pounds per cubic foot. . 1088 CHAPTER 47 1956. Guide REFERENCES 1 Drying, by W. R. Marshall, Jr. and S. J. Friedman, Perry's Chemical Engineers' Handbook, McGraw-Hill Book Co., Inc., New York, 3rd Edition, 1950. Indicated material supplied by W. R. Marshall, Jr. and S. J. Friedman, authors of the Section on Drying in the Third Edition of the Chemical Engineers' Handbook. Permis sion to use this material has been kindly granted to The Guide by the Editor, John H. Perry, and by McGraw-Hill Book Company, publishers of the Chemical Engineers' Handbook. ' * The Drying of Foods, by W. R. Marshall, Jr. (Heating, Piping and Air Condition ing, September to December, 1942, and November and December, 1943). 'Drying Materials in Trays, by C. B. Shepherd, C. Hadlock and R. C. Brewer (Industrial and Engineering Chemistry, April, 1938). `Drying of Solids by Through-Circulation, by W. R. Marshall, Jr. and O. A. Hougen (Transactions, American Institute of Chemical Engineers, 1942). 'Heat, Mass and Momentum Transfer'in the Flow of Gases through Granular Solids, by B W. Gamson, G. Thodos and O. A. Hougen (Transactions, American Ins`tiMtuatsesoTfrCanhesmfeircainl EthneginFeloewrs,o1f9G43a)s.es throu. g.h Granular. Solids .E. xtended to Low Modified Reynolds Numbers, by C. R. Wilke and O. A. Hougen (Transactions, Ameri can' LInimstiittuatteio,nosf CofheDmifficuaslioEnngEinqeueartsio, n1s94in5).Drying, by'O. A. Hougen, H. J; McCauley and W. R. Marshall (Transactions, American Institute of Chemical Engineers, 1940). 'What the Air Conditioning Engineer Should Know About Drying (Heating and Ve9nStilpartainygD, Dryeincegm, bbeyr,B1e9n42B).. Fogler and .Robert V. Klein- schmidt (Industrial and En1g0iAneneIrnintgroCduhcetmioisntrtyo, December, Convection 1938). Drying and Drying Calculations, by V. P. Victor (Heating and Ventilating, Vol. 41, Dec. 1944, p. 67). BIBLIOGRAPHY The Temperature of Evaporation, by W. H. Carrier (A.S.H.VE. Vol.Transactions, 24,1918, p. 25). Thermodynamic Properties of Moist Air, by John A. Goff and 8. Gratch (A.S.H.V.E. Transactions, VolF. a51ct,o1r9e45In. fplu.e1n2c5)in. g the Performance of Rotary Dryere, by C. F. Prutton and C. O..Mil,ler (Transactions. American Institute of Chemical Engineers, Part 1, February, 1942; Part 2, August, 1942).* . . Drying of Solids by Through Circulation, by W. R. Marshall and O. A. Hougen (Transaction*, American InsFtitauctteorosf TChheamt iIcnaflluEenngcieneDerr*y,e1r94P2e).rformance, by A. Weisselberg (Chemical and Metallurg, ical Engineering, AugTuyspt,ic1a9l32D).ryer Calc- ulations, .by O. A. Hougen (Chemical an d Metallurgical Engin' eer'ing, January and MarScyhm, 1p9o4s0iu).m on Drying, Articles by W.- K. .Lewis, W. H. Carrier, A. E, Stacey, Jr., R.8. Fleming, R. G Meta. G. B. Ridley, C. U. Lavett, D. J. Van Marie (Industrial and Engineering, Chemistry, May, 1921, pp. 4.27S-4t6u0d)i.es in Rotary Drying, I. and II, by S. J. Friedm. an and W. R. . Marshall, Jr. (Ch.emical Engineering ProgSPryerimsnscp,ipo1ls9e4ius9m)o. foDn rDyrinygingLu(mInbdeurstarined! aHndumEnidgiintyeeDriinaggrCahme,mbisytryH, .19D8' .8)T. i_em'ann (For.est . Semee Bulletin, 104, 191T2)h. e Drying of Solids, by T. K. Sherwood (Bulletin, Massachusetts Institute `of Technology, Noa. 237, 247, andR2a5d8i)a. nt Energy Drying with Heat Lamps, by T. P, Brown (Met'al Industry, Vol.. 37, Dec. 1939, p. 607). EDvraypinograbtiyveSuDbrlyiminagtiSonys, tbeymE, b. yWF, .FHlo.sdSolardf e(F(oFoododInMduasnturyfa,cVtuorli.n1g7,,VJoaln..1189, 4M5,aprc.h6,0179)4.3, p. 70). High Frequency Methods in Gluing and Drying Wood, by I. R. Berkness (Wood Products, Vol. 45, 1940, p. 1D2e).velopment of the Unit Operations of Chemical Engineer,ing: Dryi;ng, by T` . K. Sherwood (Chemica,l & MTehtealSluprgraicyalDErnygeirn--eeItrsingP,oVssoibl.il4it2ie, sp.in21I4n)d. ustry, by D. W. Biocheno .(Food Manufacturing, Vol. 19, June, 1944M. epc.h1a9n5i)s.m and Rate of Drying by Near-infra-red Radiation, by L. E. Stout, K. J. Caplan an d W. G BaiSrdom(TeraEnsnagcintieoenrsinAgmePrricoabnlemInsstitouftethoef ChNeemwicaVl eEgnegtianbeleers,DVeohly. d41ra,1ti9o4n5, pIn.d2u83s)t.ry, by W. B. Van Arsdel (A.ESl.eHc.tVro.En.icTDreahnysdacrattiioonnso, Vf Fool.o4d9s,, 1b9y43V, p. .W4.9)S. herman (Electronics, Vol. 37, 1944, p. 94). Air Conditioning and Engineering, American Blower Co., 1935. EDlreyminegntisnoInf CduhsetmriiaclaPl Elanngtsin,eJe.rOin.gR, obsysBCaodmgepraannyd. McCabe (McGraw-Hill. C o., 1931)...... . FDaien TErnogcinkeeenrteincgh,nBiku,ffbayloMF.orHgieraCcoh. (Julius Sprin'ger, Berlin, 1932). . .- Drying (Kent's Mechanical Engineers Handbook). Drying, by W. H. Carrier (Mark's Mechanical Engineers Handbook). Kiln Drying of Lumber, by A. Koehler and R. Thelen.'New York, 1926, .. ' Kiln Drying of Lumber, by H. D. Tiemann (Lippincott, 1920).............. CHAPTER 48 TRANSPORTATION AIR CONDITIONING Railway Passenger Car Air.Conditioning; Streetcar and Trolley Coach Heating and Ventilating; Passenger Bus Air-Conditioning; Automobile Air Conditioning; Aircraft Air Conditioning; Ship Air Conditioning, Heating and Venti lating, Air Conditioned Space Treatment, Systems and Controls THE principles of air conditioning applying to stores, restaurants, hos pitals, theaters, and homes are applicable to railway passenger cars, passenger buses, automobiles, streetcars, trolley coaches, airplanes and ships. However, equipment used for mobile applications differs from that used for stationary purposes in that it must meet additional requirements. Equipment must be compact, accessible for quick inspection and servicing, light-weight and unaffected by vibration and impact. Freedom from vi bration which could be transmitted to supporting vehicle and thus to pas sengers, is essential. RAILWAY PASSENGER CAR AIR CONDITIONING The railway passenger car represents a very difficult air conditioning problem. Space is strictly limited so that all equipment and ducts must be reduced to minimum size. Electric power supply and water supply also are limited. All equipment must withstand severe vibration and shock, and must be very, reliable since servicing points are frequently far apart. During the heating season it is necessary to heat conventional cars with steam from the locomotive at pressures that may vary from 250 psig to only 5 or 10 psig on the last car in long trains.. Passengers in window seats must sit only a few inches from cold outside walls and windows, and must also be very close to standing radiation installed along sides of cars. Sud den changes in load may be caused by changes in sun, wind, or train move ment. Even in coldest weather, outside doors must be opened frequently. During the cooling season, the problem is further complicated by a high concentrated internal load due to the passengers. Also, air distribution problems are increased by low ceilings and short air throws. Heating The heating of passenger cars is accomplished by using a split system consisting of an overhead air circulating system with heating and cooling coils, and standing radiation (floor heat) along car sides. The floor heaters, which usually consist of finned ^tubing, may be made more efficient by using covers designed to increase gravity air circulation, and to direct the warm air from finned heating surface along cold outside walls and car windows. In some new cars, wall convector panels are used and extend the full length of the car, with air intakes along the floor and outlets at win dow sill height and at window head height in dead-light panels. The heated panel protects passengers from cold outside walls, and the chimney effect of the panel duct increases air flow and improves heating surface efficiency. Floor heat is supplied by introducing steam into an inner tube within a finned tube or by means of a separate steam-to-liquid heat exchanger. .. 1089 1090 CHAPTER 48 1956 Guide The liquid (usually an antifreeze) is mechanically circulated through plain finned tubing. When steam is used directly, the tube-within-a-tube construction makes it possible to obtain uniform distribution throughout the length of the car. It is achieved by means of heat transfer between the steam within the inner tube and the condensate returning in the annular space between the tubes. .. The finned tubing at the floor must have sufficient capacity to offset ef fects of cold walls and windows during normal operation, and to heat the entire car to a minimum temperature of 60 F during standby when the over head system is not operating. The maximum capacity required (deter mined by standby requirements) varies with car construction and design temperatures, but is approximately 90,000 Btu per hour. This requires a heating capacity in finned tube of approximately 650 Btu per linear foot. The overhead air heating coil must have sufficient capacity to heat the outside air brought into the car for ventilation, and to supply approximately 20 percent of the internal heat loss of the car so as to permit supply of floor heat at all times at an output that will not be objectionable to passengers sitting near it. The usual capacity of the overhead heating coil is approxi mately 100,000 Btu based on 2400 cfm of circulated air, with 600 cfm of this . being outside air for ventilation. All Btu figures are approximations of actual heating requirements, and do not include heat losses in the trainline (or leakage) or losses in the undercar piping. Recent car designs have enabled the car builder to run the steam supply lines in recesses within the car body, thus greatly diminishing under-car losses. Refrigeration For cooling and dehumidification during summer, refrigeration may be obtained from ice bunkers, steam jet systems, or mechanical compressors (driven directly from car axle by electric motors or by gas engines). Re frigeration required varies with load conditions, but 7 tons per car is one capacity frequently used. Evaporative type condensers are sometimes used in combination with the usual air condenser on either steam jet or mechanical refrigeration. When an electric motor (approx. 10 hp) is used to drive the air condi tioning compressor, the electric power source is a problem. If the power source is an axle-driven generator, there is an appreciable increase in the drag on locomotive, and the power available for refrigeration, when train is stopped at a station, is limited to storage batteries. One solution to this problem is to use a d-c generator driven by a gas engine. Another is to use a Diesel-driven alternator in a special head-end car to furnish power to the entire train. Recently there have been installations in which a Dieseldriven alternator is mounted on an individual passenger car to supply the power requirements of the car. The attractiveness of this type of installa tion can be increased by utilizing spare alternator capacity in winter for electric heating. If this capacity is supplemented by exhaust heat from the Diesel engine, there is sufficient capacity to heat the entire car and to pro vide hot water for wash rooms when outside temperatures are above ap proximately 30 F. This feature is important on trains using Diesel loco motives, since it eliminates the need for firing the steam heating boiler in the locomotive during a portion of the year. Air Distribution and Cleaning Railway cars present critical problems in air distribution because air space per passenger is small (60 to 190 cu ft), and the sun load is great. Transportation Air Conditioning 1091 An average passenger car contains approximately 5000 cu ft of air, and may seat as many as 80 passengers. The occupants are continually liberating heat, carbon dioxide, moisture, odors, and some organic matter from their breath, skin and clothing. The heat and moisture can be removed by cooling and dehumidification, but other constituents can be successfully handled only by proper ventilation and air cleansing. In an average car, from 2000 to 2500 cfm are circulated by the air conditioning unit. Some of this air may be recirculated, but a portion of it should always be brought in from outside. The amount of outside air desirable depends upon the type of car, number of passengers, air temperature, humidity, odors, and whether or not the occupants are smoking, and will vary from 15 to 90 percent of the total air circulated. Careful attention must be exercised in specifying the .rate of outside air taken in so as to fit the type of service adequately, and yet not supply more ventilation than is necessary. Conditioning of this outside air is a major factor in determining size of both summer and winter equipment. For normal conditions, 10 cfm of outside air per passenger are provided. When smoking is permitted, at least 15 cfm should be admitted. In some dining cars, and deluxe sleeping cars, outside air rates as high as 20 to 30 cfm per occupant are -used. A ceiling duct lengthwise along the center of the car is usually used to distribute the air to the interior by fans or blowers. A perforated ceiling supplied from an overhead duct, or delivery grilles and plaques designed to give considerable entrainment and mixing, are used to deliver air to the car space. - Smoking rooms present a special problem. The cloud of smoke that usually hangs near the ceiling can be broken up by directing incoming air along the ceiling at a velocity somewhat higher than that used for the rest of car. The air is exhausted through the washroom or lavatory. For compartments, provision is made in the door or partition for removal of used air. Lower berths are provided with a low velocity air outlet. Recirculating air grilles are usually of straight flow types. Outside air intakes are usually located in the vestibule, on the side of the car, or on the roof, depending upon location of the cooling coils. On many recently airconditioned cars, there are no dampers or shutters at the outside air in takes; the percentage of the outside air is controlled by adjusting flow through the recirculating grille. A considerable number of coach cars are now being equipped with return air ducts fitted in the structure of baggage racks. Part of the air circulated is returned to the blower unit through these ducts, and part through the car body. This arrangement reduces quantity and velocity of air returning through the car body, and removes smoke fumes at the source. This, and any other design features aimed at taking recirculated air at the floor and adjacent to both end doors (rather than drawing all recirculated air to one end of the car) also reduces infiltration of cold air in ankle height strata, when doors are opened during the heating season. All air circulated by the blower is filtered before passing over the cooling and heating coils. In some cars outside air and recirculated air are filtered separately before mixing, while in others air from the two sources is mixed before passing through a common filter. Filters in use are combinations of metal, wool, cloth, spun glass, hemp, paper, hair and wire screen. Most filters have a viscous coating of oil for greater cleaning efficiency. Some types may be cleaned, re-treated, and re-used, while other types are dis carded when dirty. Applications are also being made of electric precipita tion for air cleaning. In this system the coarser particles are removed 1092 ' CHAPTER 48 1956 Guide from the air by mechanical separation; finer materials, by electrostatic action. ' Activated carbon units sometimes are used in addition to the regular filters for adsorbing odors and other impurities, thus reducing the amount of outside air necessary for ventilation. Temperature and Humidity Control Controls in a passenger car should be as automatic as possible. The regular train crew cannot be relied on to make adjustments for the comfort of passengers. For this reason the latest systems of temperature control have only an off-on switch to be operated by the train crew. When the system is in operation, heating or cooling is provided automatically as required. When heating, it is important that floor-heat finned tubing be controlled at stable temperatures. Wide fluctuation in its temperature is highly ob jectionable because of location close to the passengers. Stable operation may be secured by cycling the floor heat on the basis of inside conditions in conjunction with an overhead air-circulating system to maintain final car temperatures. Because of window condensation and other problems, usually no attempt is made to raise relative humidity in a railroad car in winter time. When cooling, the steam jet refrigeration system is controlled in an on-off manner. Some means are ordinarily provided for operating mechanical compressor systems at partial capacity. In this case split evaporators are used, so that evaporator surface and compressor capacity can be reduced together under light load conditions. Attempts have been made in the past, largely on an experimental basis, to control the relative humidity in railway cars! This was done by op erating the air conditioning equipment according to outside temperatures and then re-heating the air to an acceptable temperature. This was found to be an expensive method of operating and the results did not justify the cost. A common method of controlling heating and cooling is to provide a thermostat to control heating only and a separate thermostat set at a slightly higher temperature to control the cooling equipment. This gives heating control, ventilation-, and, cooling control and the reverse, as the case may be. A car in service can go from heating into cooling in a very short time. An example of this is found on the full-dome cars in service on several railroads in the country. In the early mprning hours before sunrise, the car may be requiring a considerable amount of heat. Shortly after sunrise, the car may go into the ventilating cycle and as the sun load increases, cooling may be required. On the majority of car heating sys tems, frequent cycling of the compressor is prevented by the one degree difference between the heating and cooling control points and by lag im posed on the system by applying artificial heat to the heating thermostat when cooling is required. On some car heating systems, a degree of modu lation is obtained by the use of split evaporation. This requires two cooling thermostats with one of them set at a somewhat higher temperature than the other. The lower temperature cooling thermostat controls a portion of the cooling capacity and, if unable to maintain the car tempera ture, the higher thermostat adds the remaining capacity. Transportation Air Conditioning 1093 STREETCAR AND TROLLEY COACH HEATING AND VENTILATING Streetcars. and trolley coaches present a special problem in the main tenance of satisfactory comfort conditions because of the frequent opening of the doors and highly fluctuating passenger load. Space limitations for ducts, and a desire to keep outlet grilles well above the floor to facilitate car cleaning, add further problems to the distribution system. Maintain ing comfort conditions at the driver's station cannot be overlooked, since his term of occupancy is considerably longer than that of any passenger, and because he is usually dressed more lightly than passengers. A separate source of heat is usually provided for the operator, and is under his control. Heating and Ventilating Recently-built streetcars and trolley coaches obtain heat from air blown over the main accelerating resistors and track switch resistors, to heat the passenger space. In the modem streamlined streetcars, designated P.C.C., approximately 2400 cfm are drawn from the car and blown over these re sistors to dissipate their heat. In trolley coaches, an amount of 800 cfm is customary. The heated air is then delivered to the passenger space or diverted to the outside by means of dampers, as required. If available heat from this source ^insufficient, auxiliary electric heaters in the supply ducts may be cut in. The air distribution system is 100 percent recirculat ing when the maximum heating requirement is being met. At conditions other than maximum heating demand, part of the air drawn from the car is exhausted to the atmosphere. Outside air enters the car, under these con ditions, by infiltration at all cracks and through doors when opened at stops. The most recently-built streetcars have added ventilating fans in the roof structure to introduce outside air through ceiling diffusing grilles. By governing the outside air volume introduced through these roof fans in coor dination with the heated air distributing system, it is possible to maintain a slight pressurization of the passenger space and avoid inrush of air when the doors are opened to load passengers. The roof fans also provide an effec tive means of maintaining lower inside temperature during summer opera tion. Ventilation tests on P.C.C. streetcars indicate that with 90 F outside temperature and above, 12,000 cfm are required to provide sufficient air change to keep inside temperature within a few degrees of outside air tem perature, and to provide enough air movement over passengers for comfort. The best results have been obtained by operating the ventilating fans and keeping the windows closed. New cars provided with adequate ven tilating capacity have been built with fixed sash. Control Temperature control, consisting of equipment especially designed to withstand the vibration present on transportation equipment, is used. Automatically operated dampers are used to control flow of heated air to the passenger space, or to direct heated air to the atmosphere. An automat ically operated rheostat or multi-point switch is used to vary the speed of the ventilating fans. Recent control system applications employ one thermostat to operate both heating dampers and ventilating fans in a modulating or graduated manner, with a compensating thermostat in the heat supply duct to correct for wide fluctuations in temperature of airleaving the resistors. Ventilating fans are usually stopped or operated at lowest speed during the heating cycle, and then their speed is gradually increased ns the car temperature rises above the heating-cycle control point. 1094 CHAPTER 48 1956 Guide PASSENGER BUS AIR CONDITIONING The passenger bus designed for urban transportation operation presents a greater problem to the designer of heating systems than does the interurban bus. More frequent stops, and rapidly changing passenger load create this problem on urban vehicles. Provision of heat for the driver independent of the passenger heating system, is a further problem. The inter-urban bus, however, is usually a deluxe vehicle and may require a comfort cooling system. Space and weight limitations and vibration must be considered. Heating ' Recent designs of bus heating systems obtain improved air distribution. Heat in the engine coolant liquid is used to warm air by means of suitable finned coils and this heated air is distributed throughout the passenger space by ducts and outlets directed toward the floor. Some designs include finned surface near the floor in an application similar to that in railwaypassenger cars. Forced air circulation over this finned floor heating surface has been provided to increase its effectiveness. Oil burning booster heaters have been applied to many Diesel-powered buses to raise the temperature of the engine coolant for maximum engine operating efficiency, and to provide sufficient heat for the passenger space. Ventilation Air for ventilation is usually brought into a bus at the front, and dis tributed throughout the length of the passenger space by a duct or ducts near the ceiling. Except for a few designs employing 100 percent outside air for heating, no heating of the ventilating air has been provided. One recently designed distribution system for an inter-urban bus provides for a fixed minimum of outside air, and is arranged to increase the percentage of outside air to 100 percent when the heating or cooling load diminishes. The distribution ducts and diversion damper arrangement of this system make available two supply ducts and one return duct for heating and for cooling, with a changeover to all three ducts to supply air during the inter mediate ventilating cycle. This system permits utilization of atmospheric cooling and ventilation to the greatest degree when it can be most econom ically employed in the interval between the heating and cooling demand. Conventional throw-away type filters or renewable filters are used in intake air ducts for many vehicles. Electrostatic filters have been success fully used in some installations. The need for elimination of dirt is great, but the problem is complicated by space limitations and limited power. Refrigeration Summer conditioning systems for inter-urban vehicles range in cooling capacity from 36,000 to 48,000 Btu per hour. Mechanical compression systems using refrigerants are used, and are powered by water-cooled gasoline engines of approximately 14 hp. Complete systems add from 800 to 1300 lb to weight of the coach. Some-, times an auxiliary generator driven by the refrigeration system engine is used and serves to help charge the bus battery, thereby offsetting power drain imposed by the ventilating blower. Belted reciprocating compressors and direct-driven V-type and rotary compressors are used, with engine speeds up to about 1800 rpm. Air-cooled condensers for this service re Transportation Air Conditioning 1095 quire about 5000 cfm of outdoor air, and this is provided by either centrif ugal or propeller type fans belted or direct-driven by the air conditioning engine. Preventing noise and vibration from affecting passengers is of vital importance.. Installations must be made for quick daily engine servicing. In all cases fuel is obtained from the main bus tanks, and in some, the main engine cooling system cools the air conditioning engine. Control ' Automatic temperature control is.receiving more attention in the design of new vehicles.. Some municipalities and states, have enacted laws re quiring that buses operated on their streets and roads be so equipped. The simplest control systems for heating of urban buses consist of a single thermostat to start and stop the blower of the heater unit. Improved heating systems employ a thermostat to control liquid flow to the heater cores by means of modulating valves, in combination with a means of stop ping the heating blower when no heat is required. Heating and ventilating control is accomplished by controlling the volume of outside air, over and above the minimum required in accordance with the temperature in the passenger space, by means of automatic modulating dampers in the out side air intake, or by varying the speed of the ventilating air blowers. In a large proportion of inter-city buses equipped with mechanical re frigeration, a single thermostat is used to start and stop the cooling opera tion. This may be accomplished by automatically starting an enginedriven compressor on the cooling demand or by engaging a clutch to drive the compressor. Modulated or graduated control of engine-driven com pressors may be accomplished by automatic regulation of the engine throttle controlled from a thermostat in the passenger space. Complete control systems are available to coordinate operation of the heating, ventilating and cooling equipment from a single thermostat, with automatic-change over from heating to ventilating to cooling. AUTOMOBILE SUMMER AIR CONDITIONING The first attempts to cool automobiles mechanically were made in south western United States 1930-1940 with systems assembled from commercial components. Between 1939 and 1942 one car manufacturer built about 1500 cars equipped with a mechanical system. Customer acceptance was mixed .and the project was dropped to be reactivated again in 1953. In 1952 the major automobile manufacturers decided that time was ripe to offer summer comfort cooling in their higher priced cars. The 1953 models were introduced and well accepted. In 1953 and 1954 about 125,000 units were sold. In 1955 some of the lower priced cars were available with summer cooling systems. The basic components used are fundamentally the same as in any station ary air conditioning system using the vapor compression cycle. The en gineering problem is to design for automobile application in which case the source of power is always a major obstacle to overcome. The best solution to date for automobile applications is to operate the condensing unit by -belt drive from the car motor and then control the variable refrigerating capac ity caused by the variable car motor speed by suitable means. One to seven or more horsepower are required. Compressors must be capable of operating at speeds of 4000 to 5000 rpm to last in this service. Refrigeration capacity required is about 1J to lj tons. Radiant heat, as well as high conduction heat gain due to single-glazed large glass areas, and 1096 CHAPTER 48 1956 Guide lack of adequate insulation in car bodies require this much capacity. Proper air. distribution to avoid undesirable drafts on-passengers also re quires careful design. Air distribution fans and electrical controls secure power from the car's electrical system which in some, cases may require heavier generators and batteries to handle the load. Most systems weigh' about 200 lb or less. . Early installations, and many current ones, have the cooling units in stalled in the rear of the car with the cooled air introduced through the package shelf at the rear of the passenger compartment. Cooled air is then distributed with,or without ducts. Warm air is returned through a grill in the package shelf, or below the rear seat, thence through a filter into the cooling units. Refrigerant lines from condensing unit to cooling unit are carried'from the engine compartment to the luggage compartment along the car frame under the body. , . .Current design objectives are to reduce weight and first cost, simplify nstallation, increase reliability, and improve performance, especially pull- Fig. 1. Typical Front End System (All components ahead of.fire wall\ down from a hot car standing in the sun. Recent systems have shown such improvements. Performance at open-road speeds have been very satisfactory (even with early systems--when they were operating properly). Twenty percent or more outside air should be supplied, especially if passen ger smoke. This air is picked up by scoops oq the side of the car or cowl (See Fig. 1) and carried into the cooling unit and mixed with returned warm air from the car. . Car temperature control, compressor capacity control to compensate for the variable compressor speed,-and prevention of ice formation on the evaporators (a common fault of early systems) are accomplished by by passing compressor discharge gas into the low pressure side, of the system, or cycling the compressor with a magnetic clutch. The solenoid bypass valve or a magnetic clutch is electrically operated by a thermostat, usually controlled by the return air to the cooling unit. The bypass is opened or the compressor stopped when the air gets too cold. . Transportation Air Conditioning 1097 A recent development is a complete factory-assembled system, charged with refrigerant and ready to run, which is dropped into position ahead of the firewall of the car and bolted into place (see Figure 1). Flexible suction,, liquid, and discharge lines are used to connect the refrigeration components, together. This facilitates initial installation. It also simpli fies removal for service and maintenance and eliminates the .necessity to open the refrigeration components to the atmosphere with resultant loss of refrigerant or infiltration of moisture into the system. This system combines winter heating with summer, cooling.. It also permits use of all or limited quantities of outside air, with or without heat ing or cooling. Outside air is taken in through cowl openings. This air is then pulled through a combined heating and cooling coil assembly by a fan inside the car on the fire-wall. Cooled air is discharged from adjustable nozzles on the dash inside the car. Hot air for heating is discharged onto the floor as with conventional car heaters. Dampers change the air dis tribution from heating to cooling, and dash controls activate or shut off either heating or cooling. -= Temperature control, prevention of evaporator icing and compensation for variable compressor speed are controlled by a thermostat with bulb in the air leaving-the evaporator. This cycles the compressor on a magnetic clutch. Public acceptance of current offerings has been excellent. Performance has been very satisfactory. What service difficulties have been encoun tered have been readily cared for by car dealers who have trained personnel to render this type of service, or by competent refrigeration service organi zations. , Future demand is estimated' As high as 10 percent of total car production by one major manufacturer, while another estimates a million or more of its cars will be equipped in the not too distant future. AIRCRAFT AIR CONDITIONING In the space of a few years, heating, cooling and ventilating of airplanes has progressed from comparatively simple systems 40: Inghly complex multi-pUrpose designs. The attendant control problem has become cor respondingly complex. On older, non-pressurized planes, the heating sys tem consisted either of a steam boiler and radiator or a single stage or double stage heat exchanger. On both types, the cabin temperature was adjusted by positioning the face and bypass dampers. While these were sometimes moved by an automatic modulating control, in the majority of cases they were positioned by one of the ship's crew, with results which, while not satisfactory, were passable. As these planes cruised at less than 200 mph and normally operated at low altitudes, changes in outside air temperatures were generally gradual enough so that manual readjustment of controls could maintain reasonably comfortable cabin conditions. Nearly all of these heating systems were marginal in respect to heat available, and the main problem was lack of heat, rather, than inadequate control. Non-Pressurized Cabins With the advent of the combustion type heater, and use of larger and faster planes, use of manual controls became impracticable. The com bustion type heaters reach full rating in less than a minute after being turned on, and as they are rated at 100,000 Btu per hr and up, and since several heaters are generally used, it would take full time of one crew 1098 CHAPTER 48 1956 Guide member to keep cabin temperature regulated. As ships of this type are not pressurized, the heating system is still comparatively simple. In one type, two 100,000 Btu heaters are placed in parallel positions and the ram air from an external scoop is passed through the heaters and dis charged through a series of distributing outlets located in the cabin ceiling. The cabin air is discharged through grilles located in the bottom walls of the cabin. An auxiliary nose heater is used by the crew to obtain additional heat for the cockpit or for windshield defrosting. The cabin is maintained at the desired temperature by means of an auto matic control which operates both heaters simultaneously. This control consists of two duct thermostats, one being mounted in the air inlet duct between the air scoop and the heaters so that it is affected by outside ambi ent temperatures, and the other being mounted in the heater outlet , duct so that it is affected by the discharge air temperatures. A thermostat in the cabin is so located that a continuous stream of cabin air passes through it. This type of control has been found to respond to a 1 deg temperature change in less than a second. Its theory of operation follows. As the outside temperature starts to drop, the outside air duct thermo stat decreases in resistance, unbalancing an electronic bridge. This un balance is amplified by vacuum tubes and causes a power tube to'close a relay, turning on the combustion heaters. The resulting increase in tem perature is sensed by the warm air duct thermostat which increases in resistance, thus re-balancing the bridge and causing the relay to open. If there were no loss by radiation or convection from the aircraft cabin, these two duct thermostats would be sufficient for adequate control. However, the cabin thermostat is given approximately 30 times more influence than the duct thermostats and so acts as the master controller, and the duct thermostats prevent over-heating or under-heating and keep the discharge air from alternating between extreme cold and extreme heat. In a slightly more elaborate system, two combustion heaters supply a plenum chamber which is maintained at a constant temperature.. Air from the plenum chamber is then mixed with outside air to maintain desired cabin temperature. All of the warm air is discharged into the cabin through the walls. The discharge grilles are located on the floor under seats, and a modulating type controller varies proportions of heated and outside air necessary to maintain desired cabin temperature. The same type of control system as previously described is used, except that an ampli fier operates a two-phase motor capable of positioning control dampers instead of operating a relay which would merely open and close the fuel valve. An auxiliary duct, running from the plenum chamber, is used by the pilot as a source of windshield defrosting air. Pressurized Cabins With the advent of the new high speed pressurized transport planes, and the addition of cabin cooling in addition to heating, the control problem becomes more complex. On all of these airplanes, the heat'of compression from cabin supercharger must be controlled, the air cycle or expansion turbines must be turned on and also, the heat exchanger or combustion heaters, which are used in the system when cooling is required for additional heat, must be automatically controlled. Assuming that one of these airplanes is operating in an extremely cold climate, the sequence of operation would be as follows: The automatic controller for the supercharged-air inter-cooler would be in full Transportation Air Conditioning 1099 closed position, so that none of the heat of compression would be removed, and the air would by-pass the expansion turbine and its compressor and the secondary after cooler. An additional automatic controller would be operating the combustion heater and supplying the additional heat necessary to maintain the desired cabin temoerature. If a heat exchanger were used as a supplemental source, of heat, a modulating control operating a damper, on this exchanger would run towards full heat position. ' As the airplane enters a warm climate and heat requirements drop, the combustion heater would cease operation or the heat exchanger would go to full cold position, and the modulating control on the supercharger compressor would move towards the cold position. When the outside ambient temperature rises so high that cooling is. desired, the cabin supercharger intercooler would be opened wide. If further cool ing were required, the air would go into an air cycle turbine, which is modulated to deliver the required amount of cold air to maintain a comfortable cabin temperature. Pressure in the cabin is maintained by providing a controlled, constant rate of air flow into the cabin sufficient to maintain ventilation, and adjust ing the cabin-pressure relief valve setting, by means of a cabin pressure se lector, to maintain the desired cabin pressure. Limits on maximum inside to outside pressure may be of the order of 4 or 5 psi, and safety controls should be provided to prevent exceeding this limit. There is a maximum rate at which the cabin can change to a newly selected value, this rate being in some cases also adjustable. The requirements for controls of this nature are extremely rigid. It is commonplace for ships of this type to experience changes in outside ambi ent temperatures of as much as 100 deg in a space of 5 min. For this reason, speed of . sensing a change and rapidity of response in the control system is essential if satisfactory control is to be accomplished. The older type thermostats cannot be used in airplanes, due to mass of the thermo stat and to vibration experienced on all airplanes. All modem controls use some type of bridge system with temperature sensitive resistors as sensing elements. In some types of controls, the bridge system feeds a sensitive balanced relay, which in turn runs a modulating motor or controls an on-off power relay. A recent sensitive and quickly responding type uses an electronic amplifier, which in turn controls a two-phase motor, or, through relays, controls a d-c motor, or merely closes and opens a power relay for on-off applications. In addition to extreme speed and accuracy which are required of all air craft temperature controls, they must be able to operate under great ex tremes of temperature, pressure and humidity, and also withstand contin uous extreme vibration. Heaters should have, in addition to control from thermostats, suitable limit controls to prevent over-heating due to failure of air supply, or any other cause. Also, there should be safety devices to shut off fuel in case of flame failure. On the latest high speed jet airplanes, the temperature control problem is still more severe than on the latest transports; as in addition to the accuracy required, control response must be phenomenally fast. For example, on some, the air going to the cabin from the jet engine compressor can change the temperature at the rate of 150 deg per second. This, coupled with the fact that on smaller size pursuit ships air is changed in the cabin as much as four times per minute, makes the instantaneous sensing of change and an extremely rapid control movement essential. Also, in airplanes operat ing at Mach numbers in excess of 0.7, the control must react to the large adiabatic temperature rises encountered. Some of these problems are so new that controls still have not been developed to meet all of the desired conditions. However, present studies being made by control manufac turers should result in developments of such controls in the near future. 1100 CHAPTER 48 1956 Guide SHIP AIR CONDITIONING In air conditioning a ship, the designer is faced with all problems that would normally arise on shore installation plus additional factors. Mechanical ventilation is an absolute necessity for the comfort of passengers and ships' personnel, and for utility and preservation of cargo and stores. Ships are constructed with water-tight bulkheads dividing the vessel into several compartments. This complicates the running of duct work and results in a multiplicity of both supply and exhaust fans. Temperature and humidity requirements of various spaces aboard ship vary widely. Passenger staterooms and public spaces must have year-round air condiditioning with is also being applied more and more to the quarters of the officers and crew* Boiler rooms, galleys, laundries, etc., must have venti lation, and some must have tempered air. Cargo spaces are quite likely to need dehumidification in addition to ventilation. Inasmuch as ventilation is such a necessary factor aboard a ship, the majority of recently built vessels have been utilizing the air distribution system for heating purposes. ' A ship is a self-contained structure quite likely to be away from repair ports for long periods. Adequate spare parts, therefore, form an integral part of equipment furnished. The same type of equipment should be used in as many places as possible throughout the ship, in order to reduce the number of spare parts to be carried. Preliminary system design is simplified by uniformity of conditions, which apply to most ships. Among such conditions are: (1) the necessity for the vessel to supply its own power, (2) the availability of an unlimited supply of low cost steam at suitable pressure, (3) limitations of available space and permissible weight. . The problem of heat transfer and insulation must be given careful con sideration. The thermal conductivity of ship building material, such as steel, copper and brass, is many times the value of building material used ashore. The length of ducts between heat sources and fans necessitates extra duct insulation. Hull insulation must be of high quality, with attention given to fireproofness, low density, low thermal conductivity, ruggedness, vermin resistance, and ease of application. Board types are most common. Duct insulation must have the same characteristics as hull insulationSemi-rigid and rigid board are most common. Corrugated asbestos is not used because in the presence of moisture, it tends to disintegrate. There is a growing use of natural cork on chilled air ducts because of great diffi culty in applying an adequate vapor seal due to space limitations. SHIP HEATING AND VENTILATING It is usually most economical in weight and space to use steam duct heaters for heating spaces served by mechanical supply systems. .Spaces which do not have mechanical supply, or do not require ventilation in cold weather, are heated by steam convectors or, where the load is large, by unit heaters. Ventilation air, except that supplied to auxiliary and main machinery spaces, is usually preheated to temperatures of 50 to 70 F. No recirculation is used in ventilation and heating systems, but a manual reduction (25 to 50 percent) of air quantity is made during the heating cycle. ' All heaters are automatically controlled, and preheaters are de signed and installed to minimize possibility of freezing of condensate. Transportation Air Conditioning 1101 Preheaters are frequently located close to the outside air intake in order to conserve insulation and, for the same reason, zone reheaters are located as close as possible to each zone. Where a reheater serves only one space, it is commonly located in the space. ' Combinations or variations of duct type and convection or radiant heaters are used, depending upon basic, design requirements, such as weight and space limitations, and the economic justification of the cost of the type selected. Because of many different requirements of various spaces aboard ship, some design temperatures and humidities are given in Table 1. The resulting quantities of air should be checked against typical heating and ventilation practices for ships.* Table 1. Design. Conditions fob Ships Absa . Heat* ing Outside Design. Temperatures ' Ventilating . Cooling FF Living Quarters. .. ... Public Spaces........ 0 0~ 95 Naval Vessels.... . +10 88(DB) 80(WB) F 95(DB) 80(WB) 95(DB) 80(WB) 88(DB) 80(WB) . Inside Conditions . DB & R.H. Effective. Temp. F% 80 50 80 55 85 50 .F 73-74 731-741 75-78 Living Spaces The minimum quantity of ventilation air required for any sleeping or office space, including hospital space, should be that which will limit the temperature rise over the outside air to not more than 10 deg (a rise of .7 deg is more satisfactory), or a minimum of 30 cfm per person, whichever is the greater. In spaces fitted for eating, recreation, or manual work, the rise may be taken at 10 deg with not less than 20 cfm per person. The same require ment applies to mechanical exhaust, although natural exhaust may be used where only a short run of duct exists. . Heat should be furnished to maintain the following temperatures: Staterooms, Berthing, Messing and Office Spaces.......................... 70 F Working Spaces and Shops..................................................................... 60 F Hospital Spaces......................................................................................... 75 to 78 F Machinery Spaces The prime purpose of machinery space ventilation is to maintain a habitable temperature for the operating personnel. It is more practicable to use spot cooling of personnel at working areas than to attempt to obtain uniform ambient temperature. The permissible temperature rise (above outside) at working stations is usually 15 deg, while the overall temperature rise is usually between 30 and 50 deg. These spaces must be exhausted adequately, preferably by mechanical means. Every attempt should be made to remove air at or close to the heat sources. The capacity of the mechanical exhaust systems should be greater than the supply, taking into consideration the expansion of the supply air, to insure an indraft through access openings to the space. Heat is not required for machinery spaces, except for those fitted with Feb. 1943, p. 333). 1102 CHAPTER 48 1956 Guide electrically operated equipment, which may remain inactive during periods while in port when heating to about 50 F will be required. ` Storerooms and Cargo Spaces The ventilation provided for these spaces depends on the type of vessel, location of space, and nature of cargo. Ventilation is required for all closed spaces. Even if ventilation is not necessary to preserve the stores or cargo, it is required to prevent the accumulation of toxic or combustible gases and odors. One air change in 15 to 30 min is common practice, except where inflammable liquids or proximity to hot spaces requires additional ventilation. Mechanical sup ply and natural exhaust are usually used. However, where inflammable gasps may exist, natural supply and mechanical exhaust are provided. Many ships are fitted with dehumidification facilities for eliminating damage to the dry cargo by preventing condensation and dampness. The dehumidification load consists of moisture removed from the ventilation air passed through the dehumidifier, plus the moisture on, or given off by, the cargo, packaging, dunnage, battens, and other materials in the ship's holds. The most severe outside condition requires a moisture removal of 90 grains (140-50) per pound of dry air, with 88 F cooling water. The largest cargo ships are provided with equipment for removing about 250 lb of water per hour. . The dehumidification systems generally utilize silica gel or lithium chlo ride with inhibitor. (See Chapter 38). In most cases central drying equip ment is provided. On large passenger ships consideration is given to the use of two dehumidifying units, because the cargo-carrying spaces are usually concentrated at the extreme ends of the vessel. A simple duct system distributes the dry air to the hold supply ventilation system. These ventilation systems use outside air when weather conditions are favorable. Recirculation and dehumidification are used only when neces sary, i.e., when the weather dew-point approaches or exceeds the temper ature in the hold. Two control stations are generally provided, one in machinery space, and one in chart or wheelhouse. These stations are arranged so that either may change the cargo conditioning system controls from use of outside air to use of conditioned air. AIR CONDITIONED SPACE TREATMENT FOR SHIPS The application of air conditioning to new American passenger ships is well established. All passenger staterooms, except steerage and third class, are usually air conditioned. This includes staterooms for ship's personnel and offices within conditioned passenger areas. Third, class staterooms are air conditioned on some ships, depending on the particular trade. Theaters, lounges, smoking rooms, beauty shops, barber shops and similar closed public spaces aTe usually air conditioned. All messrooms, recreation rooms, officers' offices, crew's inboard rooms, and those having fixed portlights are usually air conditioned on passenger vessels. The treatment depends on the requirements of the operator and the proposed itinerary of the vessel. SHIP SYSTEMS AND CONTROLS The types of comfort conditioning systems used to date generally have followed conventional lines, except for those serving staterooms, offices, and similar small spaces. Large public spaces are fitted with individual Transportation Air Conditioning 1103 systems which supply dehumidified and cooled air during the cooling cycle, and warm air during the heating cycle. In many cases these rooms are fitted with large glass windows and doors, and require direct radiation to offset the downdraft which would occur in cold weather. Finned-tube radiation running the full length of the glass area is commonly used for this purpose. Introduction of warm air at the sill, in lieu of direct radi ation, is also used. Systems serving most public spaces are designed to provide all outside air as long as the refrigeration load is less than the capacity of the cooling equipment. Many central systems are simplified by using 100 percent outside air all-year-round. The important problem in ship air conditioning concerns the treatment of the small spaces such as passenger staterooms, offices, and crew quarters. Low headroom, congested quarters, double berths, and unsymmetric arrangements make each space a problem in air distribution and treatment. The simplest system used for small spaces consists of a central filter bank, supply fan, preheater, and cooling and dehumidifying coil. The preheater steam valve and cooling coil water valve are controlled in sequence by a duct thermostat, in the fan discharge, set to maintain a constant outlet air temperature. Zone reheaters are provided to take care of variations in heating loads. The reheater steam valve is controlled by a sub-master thermostat at the reheater outlet. Control of room tem perature is obtained by operating manual dampers in the air supply to the space. A recirculation exhaust fan is frequently provided, and operates in conjunction with automatic dampers to utilize the maximum quantity of outside air consistent with capacity of the cooling coils. One system utilizes the same central supply equipment and recirculation exhaust system as the one just described, except that zone reheaters are replaced by individual space' hot water reheaters. Each reheater is pro vided with a control valve, controlled by room thermostat. Generally, a forced circulation single pipe hot water system is used. This system is generally used for staterooms and small spaces devoted to first and second class passengers. The average total air per person is about 60 cfm, and average outside air per person is about 18 cfm. A third system, used to a limited extent, is similar to the system just described, except that each room is provided with an induction unit (floor type where possible) which reheats the primary air supply. Control of heating coil in the induction unit is the same as noted for the system de scribed in the previous paragraph. The average primary air supply is about 40 cfm per person. Recirculation is not always used. The amount of induced air varies with unit design. A fourth less common arrangement is similar, but makes use of hot water in the induction unit in winter and cold water in the induction unit in summer. Control of the valve on the unit is obtained by use of a summerwinter type thermostat. The unit is provided with drip pan and drain piping to remove condensation. No recirculation is used. On cargo ships, tankers and vessels not carrying passengers or not having air conditioning, heating of crews' spaces and officers' staterooms is usually obtained through a central system having filters, preheaters and reheaters. A minimum temperature of air leaving the preheater is controlled by a duct thermostat. The reheater is controlled by a sub-master discharge-duct thermostat, reset by outside master control. Relationship between sub master and master control (wherein discharge temperature is raised as 1104 CHAPTER 48 1956 Guide outdoor temperature drops); is set according to a schedule based on the ship's itinerary: ' Duct work for all systems described is designed for -conventional velocity. However, if power is available, and suitably strong duct construction and adequate sound absorbing facilities are provided; high velocity systems may be used. '' BIBLIOGRAPHY ; Railway Passenger Cars Report on Performance and Cost of Operation of 1937 Internal Combustion Engine Mechanical Compres sion Equipment for Air Conditioning Railroad Passenger Cars, by Division of Equipment Research, Asso ciation of American Railroads, May 1,1937. Report on Relative Performance of Air Filters, by Mechanical Division, Association of American Rail roads, January 15, 1938. -- Air Conditioning of Railroad Passenger Cars, by L. W. Wallace and G. G. Early, Jr. (A.S.MJ2. Trans "It: actions, November, 1937). ._ ' "Passenger Car Cooling Methods, by Kenneth Cartwright (Refrigerating Engineering, February, 1936, p. 83 and March, 1936, p. 168). .. ,, Diesel Drive for Passenger Air Conditioning, by J. R. Hornaday (Refrigerating Engineering, March, 1942, p.439). ` .................... .; .. : ' Railroad Air Conditioning, by Gordon T. Wilson (Refrigerating Engineering, May, 1943,p. 323). -Railway Air-Conditioning, by M. R. Eastin (Railway Elec. Engr.; August-December, 1942). Head-End Power for Railway Cars, by F. L. Sahlmann and E. M. Bill (Railway Elec. EMay, ngr., 1939). Head-End Power f or Streamlined Passenger Trains, by J. D. Loftis (AJS.M.E. Raleigh Section, October 26, 1946). ., P.C.C. Car Ventilation, B-3697 Westinghouse Electric Corp., September, 1946. . ' Buses and Automobiles Bus Heating, by E. T. Todd and F. O. Gadd (Heating and Ventilating, Dec. 1946 p. 83) . Air Conditioning of Automobiles and Buses, by L. W. Child (Society of Automotive Engineers Journal, June, 1938). Bus Air Conditioning, by Jerry Hicke (Heating, Piping and Air Conditioning, October, 1938, p. 639). Bus Air Conditioning, by A. J. Mallinckrodt and Lars Hanson (Refrigerating Engineering, June, 1939, p. 388). - ,, . . .. ' What Has Been Done in Auto Air Conditioning by O. G. Tmkey (Refrigerating Engineering, January I95Cara That Beat the Heat, by M. W. Baker, D. C. McCoy, H. V. Joyce and P. J. Kent (Journal, Society of Automotive Engineers, July 1953, p.19). ^__ __ _ ' ... Automobile Air Conditioning--Progress and Problems, by P. J. Kent (A.S.H.V.E. Transactions Vol. 60,1954, p. 37). . Passenger Automobiles, M. W. Baker and D. C. McCoy (A.S.R.E. Air Conditioning Refrigerating Data Book, 1954-55; Chapter 50). . '. Airplanes Comfort in High Altitude Flying, by D. W.Tomlinson (A.S.H.V.E. Transactions, Vol. 47, 1941, p. 57).- Heat Exchangers for Aircraft, by Arthur J. Hess (Refrigerating Engineering, September, 1944, p. 192). Heat ing and Ventilating for Transport Airplanes, by B. M.Brod (A.S.H.VK. Transactions, Vol. 52,1946). Comfortiiation of Aircraft, by Albert A. Arnbym (Pitman Publishing Corp., New York, 1945). Refrigeration for Air Conditioning Pressurized Transport Aircraft, by B. L. Messinger (Heating and Ven tilating, January, 1946, p. 63). ' * ' ' . . Ships Ventilation and Air Conditioning of the S. S. Panama (Heating and Ventilating, September, 199. p. 47)- Air Conditioning the New Mauretania (Heating, Piping and Air Conditioning, July, 1939, p. 4331). Heating, Ventilating and Air Conditioning on Shi pboard, by J. H. Clarke (Heating, Piping ona Air Con ditioning, August, p. 467; September, p. 529; October, p. 610, 1940). ,. Care of Cargo at Sea, by O. D. Colvin, W. H. E. Habne, and M. R. Colby (Transactions of the Society of Naval Architects and Marine Engineers, Part I, Vol. 46, 1938, p. 109; Part II, Vol. 49,1941. p. 208).- . Modern Marine Engineers Manual, Vol. II, Sections 16 to 19, Inc. (Cornell Maritime Press, 1943). Warship Ventilating, Heating and Air Conditioning, by Comdr. T. H. Urdahl, U.S.N.R., and W. C., Whittlesey (A.S.H.VJ2, Transactions, Vol.49, 1943, p. 35). . . __ TT , TT 0 XT t> Standardized Heating and Ventilating Equipment fo r Fighting Ships, by Comdr. 1. xi. Uraanl^U^.iNJt. and Lt. John Everetts, Jr.. U.S.N.R. (Heating, Piping and Air Conditioning, July. 1943, p. 333). Daigmpg Warship Ventilation with Standardised Equipment, by Comdr. T.'H. Urdahl, U.S.N.R., and W. C. Whittle sey (Heating, Piping andAir Conditioning, August, 1943, p. 419). VT , M cdern Air Conditioning, by J. W. Markert (Marine Engineering and Shipping Review, November ,1945, ^ ModernMarine Refrigeration andAir Conditioning, by W. H. Carrier and L-E. Starr (Marine Engineering and Shipping Review, April, 1946, p. 132). -- ~ , ,, , Dehumidification Protects U. S. Navy's Inactive Fleet, by Capt.T. H. Urdahl and Comdr. E.R. Queer, Heating, Piping and Air Conditioning, March. 1946, p. 71). ...................... ,w .. _ , ' "Reconversion of LinerS. S. Lurline, by Robert Tate (Society of Naval Architects and Marine Engineers, May 12, 1949). - Air Conditioning of P-2 American President Liners, by J. W. Markert (Pacific Marine Review, August, 1946). '' Export Lines Air Conditioning of Four Aces, by J. W. Markert (Marine Engineering, March,-1949). CHAPTER 49 WATER SERVICES Sizing Cold Water Supply Piping, Procedure for Sizing Cold Water Systems, Cool ing Water Piping, Estimating Heating Load and Storage Capacity, Methods of Heating Water, Computing Heat Transfer Surface, Hot Water Supply Piping, Control of Service Water Temperature, Safety Devices, Solar Water Heaters, Domestic Hot Water by . Heat Pump PROPER design of the water distributing system in a building is neces sary in order that the various fixtures may function properly. The amount of either hot or cold water used in any building is variable, de pending on the type of structure, usage, occupancy, and time of day. It is necessary to provide piping, water heating, and. storage facilities of sufficient capacity to meet the peak demand without wasteful excess in either piping or equivalent cost. SIZING COLD WATER SUPPLY PIPING One of the important items that must be determined'before any part of the water-piping system can be sized, is the probable rate of flow in any particular reach of piping. The rate of flow in the service line, risers, and main branches, however, will rarely be equal to the sum of the rates of flow of all connected fixtures. In fact, the probability that every fixture in a large group will be in use at the same time is so remote that it would be very poor engineering practice to design the piping to take care of such simultaneous flow. The demand load in building water supply systems cannot be deter mined exactly and is not readily standardized. The two main problems to be considered are: (1) the satisfactory supply of water for a given fixture, and (2) the number of fixtures which may be assumed to be in use at the same time. The minimum flow that will be satisfactory to the consumer depends greatly on the consumer, .hi's standard of living, his-professional needs, size of family, garden requirements, and similar factors. Depending on these factors, the per capita water consumption for domestic use usually varies between 20 and 80 gal per day. Experience indicates that the type of dwelling also has considerable influence on the water consumption. In apartment houses the per capita daily water consumption is generally higher than in single-family houses. This is due to the use of a central metering system which is not conducive to the saving of water, and to the long hot water lines which cause high heat losses and an increase in the wasting of the cooled water. In designing water supply systems for apart ment houses, a daily per capita water consumption of 50 gal may be con sidered a safe design figure. . Although a considerable number of housing projects have been developed throughout the United States, conclusive water consumption data have not yet been gathered. Nevertheless, it seems that the daily per capita water consumption in housing projects falls in between the consumption in apart ment houses and that in single dwellings at the same geographical location. $ 1105 :-yX 1106 CHAPTER 49 1956 Guide Table 1. Propeb Flow and Pressure Required During Flow for Different Fixtures / Fixture Flow Pressure Flow gpm Ordinary basin faucet................................................................. Self-closing basin faucet............................................................ Sink faucet--| in........................................................................... Sink faucet--| in..................................................... ................. Bathtub faucet.............................................................................. Laundry tub cock--\ in....................................................... Shower.......................................................................... . Ball-cock for closet...................................................................... Flush valve for closet............................................................... Flush valve for urinal.................................................... - 8 12 10 5 5 5 12 15 10-20 15 30 , 3.0 2.5 4.5 45 6.0 5.0 50 3.0 is-io* 15 0 5.0 " Flow pressure is the pressure in the pipe at the entrance to the particular fixture considered. b Wide range due to variation in design and type of flush-valve closets. . In general, a daily per capita water consumption of 40 gal can be used as a safe design figure for housing projects. Table 1 gives the rate of flow desirable for many common types of fixtures, and the average pressure necessary to give this rate of flow. The pressure necessarily varies with fixture design; with some, a much greater pressure is necessary to give the same rate of flow than with others. In general, the lower the quality of the faucet the greater will be the pressure required. ' In estimating the load, the rate of flow is frequently computed in fixture units. One fixture unit is equivalent to 7.5 gal per min. Table 2 gives the demand weights in terms of fixture units for different plumbing fix tures under several conditions of service, and Fig. 1 gives the estimated demand in gallons per minute corresponding to any total number of fix ture units. Fig. 2 shows an enlargement of Fig. 1 for a range up to 250 fixture units. Table 2. Demand Weights of Fixtures in Fixture Units* Fixture os Group* Occupancy Ptthlir Type op Supply Control Faiw*t - Weight in Fixture " Units* 10 10 5 3 2 4 3 4 6 3 .1 2 2 8 6 2 2 3 3 *For supply outlets likely to impose continuous demands, estimate continuous supply separately and add, to total demand for fixtures. b For fixtures not listed, weights may be assumed by comparing the fixture to a listed one using water in similar quantities and at similar rates. The given weights are for total demand. For fixtures with both hot and oold water supplies, the weights for maximum separate demands may be taken as $4 the listed demand lor the supply. ' Water Services 1107; No. 1 for system predominantly for flush valves. No. 2 for syBtem predominantly for flush tanks. Fig.-I. Estimate Curves fob Demand Load The estimated demand load for fixtures used intermittently on any supply pipe will be obtained by multiplying the number of each kind of fixture supplied through that pipe by its weight from Table 2, adding the products, and then referring to the appropriate curve of Figs. 1 or 2 to find the demand corresponding to the total fixture units. In using this method it should be noted that the demand for fixture or supply outlets other than those listed in the table of fixture units is not yet in cluded in the estimate. The demands for outlets (such as hose connec tions, air conditioning apparatus, etc.) which are likely to impose con tinuous demand, during times of heavy use of the weighted fixtures, should be estimated separately and added to the demand for fixtures used in termittently, in order to estimate the total demand. So far, the information presented makes possible the determination of the design rate of flow in any particular section of piping. The next general step is to determine the size of piping. As water flows through a pipe, the pressure continually decreases along the pipe, due to loss of energy from friction. The problem is then one of ascertaining the minimum pressure in the street main, and the minimum Fig. 2. Section of Fig. 1 on Enlabged Scale 1108 CHAPTER 49 1956 Guide FRICTION LOSS IN HEAD IN LBS. PER SO. IN. PER 100 FT LENGTH Water Services FRICTION LOSS IN HEAD IN LBS. PER SQ. IN. PER 100 FT. LENGTH 1109 Fig. 3. Flow Chart for Copper Tubing pressure required for the operation of the topmost fixture. (A pressure of 15 psi is ample for flush valves, but reference should be made to the manufacturers' requirements. A minimum of 8 psi should be allowed for other fixtures.) The pressure differential thus obtained will be available for overcoming pressure losses in the distributing system, and in over coming the difference in elevation between the water main and the highest fixture. The pressure loss, in pounds per square inch, caused by the difference in elevation between the street main and the highest fixture, may be ob tained by multiplying the difference in elevation in feet by the conversion factor 0.43. When water flows through a pipe, friction occurs as the result of the sliding of water particles past one another. If the pipe wall is rough, the roughness projections cause additional friction, owing to the develop ment of increased turbulence in the flowing water. As the water flows along a uniform pipe, the pressure decreases as a result of a dissipation of FRICTION LOSS IN HEAD IN LBS. PER SQ. IN. PER 100 FT. LENGTH Fig. 4. Flow Chart for Fairly Rough Pipe energy arising from the internal friction set up by viscosity of the water. This loss in energy is shown by the loss of pressure. The pressure loss is proportional to the length of straight uniform pipes, and varies greatly with flow velocity, pipe, diameter, roughness of pipe, and water tempera ture. On the basis of inside surface conditions, pipes may be classified as smooth, fairly rough and rough, as follows: Smooth. The pipe surface shows no perceptible roughness. Pipes made of copper, brass, or lead may usually be classified as smooth. ' Fairly Rough. All ordinary pipes, such as wrought iron, galvanized iron, steel and.cast-iron, after a few years of usage, may be called fairly rough. Rough. Pipes that have deteriorated fairly rapidly for some 10 or 15 years after being laid, are classified as rough. Figs. 3, 4 and 5 give the pipe friction losses corresponding to these three types of pipes for various nominal diameters for a water temperature of 50 F.1 Example 1 will illustrate the use of the charts. .. 1110 CHAPTER 49 19S6 Guide Water Services 1111 c- J i *'*'*' pounds per square inch for any given rate of flow. Experience has shown, however, that the simplest method of expressing losses in fittings and valves is to use the concept of an equivalent length of straight pipe. Thus it has been found, for example, that a 1 in., 90 deg elbow introduces a loss equivalent to 2.2 ft of straight 1 in. pipe. Therefore, for each 1 in., 90 deg elbow, 2.2 ft of 1 in. pipe are added to the total length of 1 in. pipe. Estimated pressure losses for pipe fittings and valves in terms of equiva lent pipe length are shown in Table 4. Table 5 lists the equivalent lengths for various special types of ap paratus and fittings. The loss in water meters varies considerably with the design even in meters of the same nominal size. The values given in Table 5 are ample for the well-known meters now on the market. Example 1: A 2J in. fairly rough pipe supplies 100 gpm of water. Find the fric tion loss in head if the pipe length is 200 ft. . - Solution: Enter Fig. 4 at 100 gpm, and move along-this line until it intersectsithe 2$ in. diameter line. From this intersection point, move vertically down and read 4.5 psi friction loss per 100 ft of pipe length. Then the total friction loss will-be 2 X 4.5 = 9 psi. ' r The pressure losses in the distributing system will consist of the pressure losses in the piping itself, plus the pressure losses in the pipe fittings, valves and the water meter, if any. Estimated pressure losses for disc-type `meters for various rates of flow are given in Fig. 6. Flow limits for disc-type meters, which may be regarded as the limits of recommended ranges in capacities, are given in Table 3. For informa tion on other types of meters, the manufacturers should be consulted. Fig. 7 shows the variation of pressure loss with rate of flow for various types of faucets and cocks, based on experimental data obtained at the ;i State University of Iowa. ;! The loss of pressure through any fitting or valve can be expressed in PRESSURE LOSS -POUNDS PEP SO. IN. Fig. 7. Variation of Pressure Loss with Rate of Flow for Various Faucets and Cocks A. J in. laundry bibb (old s^fle). t>. Laundry compression faucet. K. Combination compression sick faucet F. Basin faucet. t j* ^"Pression sick "aucet (Mfr. 1). G. Spring self-closing faucet. m. compression sink faucet (Mfr. 2). H. Slow self-closing faucet. L>. Combination compression bath tub faucets (both open). (Dashed lines indicate recommended extrapolation) 1112 CHAPTER 49 1956 Guide Table 3. Performance :Requirements of Water Meters* Size In. Normal Test-Flow Limits .................. GPM IS Xi ------------------------------- 1 to 20 _ .. 2 to 34 3 to 53 .. 5 to 100 2. " .......... .. ... 8 to 160 a - - - ........................ 16 to 315 4 ' ' * '1 ! - .. ....... . .28 to - 500 ft ' ; 48 to 1,000 ' Minimum Test-Flow GPM if M IJi 2 4 7 12 ' . * American Water Work* Association Standards.* ' ,, , ,, Registration. The registration on the meter dial shall indicate the quantity recorded to be not less than 98 percent nor more than 103 percent of the water actually passed through the meter while it is being tested at rates of flow within the specified limits herein under normal test flow limits: There shall be not less than 90 percent of the actual flow recorded when a test b made at the rate of flow set forth under minimum test flow. The water demand for hose bibbs or other large demand fixtures taken off the building main is frequently the cause of inadequate water supply to the upper floor of a building. This condition may be prevented by sizing the distribution system so that the pressure drops from the street main to all fixtures are the same. It is good practice to maintain the building main of ample size (not less than 1 in. where possible) until all branches to hose bibbs have been connected. Where the street main pressure is excessive and a pressure reducing valve is used to prevent water hammer or exces sive pressure at the fixtures, it is frequently desirable to connect hose bibbs ahead of the reducing valve. The principles involved in sizing either up-feed or down-feed systems are the same. The principal difference in procedure is that in the downfeed system, the difference in elevation between the house tank and the fixtures provides the pressure required to overcome pipe friction. Procedure for Sizing Cold Water Systems - The recommended procedure for sizing piping systems is outlined in fol lowing paragraphs 1 to 6, inclusive. 1. Draw a sketch o{ the main lines, risers, and branches, and indicate the fixtures to be served. Indicate the rate of flow of each fixture. ' Table 4. LossAllowance in Equivalent Length op Pipe fob Friction in Valves and Threaded Fittings Equivalent Length op Pipe for Various Fittings Diameter of Fitting In. 90 Deg Standard Ell Ft ^ ..... 14 ...... 1 H ... 1J4 . 114 ............ 9'" ................ 3' " ... m4 --------------------.-.-.S ....... 6~.------------------------------- 1 2 2.5 3. 4 5 7 8 10 12 14' 17 20 45 Deg Standard Ell Ft 0.6 1.2 1.5 1.8 2.4 3 4 5 6 ,7 8 10 12 90 Deg Side Tee Ft Coupling or Straight Run of Tee Ft 1.5 0;3 3 0.6 4 0.8 5 0.9 6 1.2 7 1.0 . 10 2 12 2.5 15 3 18 3.6 21 4.0 25 5 30 6 Gate Valve Ft 0.2 0.4 0.5 0.6 0.8 1.0 1.3 1:6 2 2.4 2.7 3.3 r 4 Globe Valve Ft 8 15 20 25 35 45 55 65 80 100 125 140 165 Angle Valve Ft 4 8 12 15 18 22 28 34 40 50 55 70 80 Water Services 1113 2. Using Table 2, compute the demand weights of the fixtures in fixture units. 3. Determine the total demand in fixture units and, using Fig. 1 or Fig. 2, find the expected demand in gallons per minute. 4. Detennine the equivalent length of pipe in the main lines, risers, and branches. Since the sizes of the pipes are not known, the exact equivalent length for various fittings, etc., cannot be made. Add the equivalent lengths, starting at the street main and proceeding along the service' line, the main line in the building, and up the riser to the top fixture of the group served. 5. .Determine the average minimum pressure in the street main and the minimum pressure required for the operation of the topmost fixture. This latter pressure should be 8 to 15 psi. 6. Calculate, by means of Equation 1, the approximate design value of the average pressure drop per 100 ft of pipe in the equivalent-length determined in paragraph 4. p = [P - 0.43H - 10] ^ where p = average pressure loss per 100 ft of equivalent length of pipe, psi. P = pressure in street main, psig. - (1) Table 5. LossEquivalent Lengths op Ikon Pipe to Give Same as Special Fittings and Apparatus Fitting Apparatus 30-gal Vertical hot-water tank, % in. pipe. . . 30-gal Horizontal hot-water tank, % in. pipe:. Water meters (No valves included) % in. with }4 in. connections....................... . H in. with in. connections..................... ,. M in. with % in. connections......................... 1 in. with 1 in. connections............................. 1)4 in. with 1 in. connections......................... Water softener.................. ...................................... Nominal Diameter of Pipe--Inches HH 1 4 17 56 1.2 5 16 6.7 28 90 4.8 20 64 --3.4 14 45 9 30 -- 4.4 14 -- 50-200 lH -- __ __ __ 115 54 H = height of highest fixture above street main, feet. L = equivalent length determined in paragraph 4, feet. , If the system is of the down-feed supply from a gravity tank, the height of water in the tank, converted to pounds per square inch by multiplying by 0.43, replaces the street main pressure, and the term 0.43 H in Equation 1 is added instead of sub tracted in calculating the term p. In this case, H will be the vertical distance of the fixture below the bottom of the tank. 7. From the expected rate of flow, determined as in paragraph 3, and the value of P, calculated as in paragraph 6, choose the sizes of pipe from Figs. 3, 4 or 5. Example 2: Assume a minimum street main pressure of 55 psig; a height of topmost fixture above.street main of 50 ft; a developed pipe length from water main to highest fixture of 100 ft; a total load on the system of 50 fixture units; and that the water closetsare flush-valve operated. Find the required size of supply main. Solution: From Fig. 2 the estimated peak demand is found to be 51 gpm. From Table 3 it is evident that several sizes of meters would adequately measure this flow. For a trial computation choose the 1% in. meter. From Fig. 6 the pressure drop through a 1J in. disc-type meter for a flow of 51 gpm is found to be 6.5 psi. __ Then the pressure drop available for overcoming friction in pipes and fittings is 55 - (15 + 50 X 0.43 + 6.5) = 12 psi. At this point it is necessary to make some estimate of the equivalent pipe length of the fittings on the direct line from the street main to the highest fixture. The exact equivalent length of the various fittings cannot now be determined since the Pipe sizes of the building main, riser, and branch leading to the highest fixture are not known as yet, but a first approximation is necessary in order to make a tentative selection of pipe sizes. If the computed pipe sizes differ from those used in deter mining the equivalent length of pipe fittings, a recalculation will be necessary, using i ' ,i,i ! j . ,;*jj ";l i;> "*'i ...; f*' Ji 1114 CHAPTER 49 1956 Guide . Table 6. Computation op Branch Size in Example 2 Fixtures No. and Kind Fixture Units (From Table 2 and Note c) Demand (From Fig. 2) Gpm Pipe Site (From Fig. 4) In. 3 x 6 = 18 } (2 x 2) = 3 }(3xl) = 2.25 23.25 38 h the computed pipe sizes for the fittings. For the purposes of this example assume that the total equivalent length of the pipe fittings is 50 ft. , Then the permissible pressure loss per 100 ft of equivalent pipe is 12 X 100/ (100- + 5b) * 8 psi. _ Assuming that the corrosive and caking properties of the water are such that Fig. 4 for fairly rough pipe is applicable, a 2 in. building main will be adequate. The sizing of the branches of the building main, the risers, and fixture branches follow the principles outlined. For example, assume that one of the branches of, the building main carries the cold water supply for 3 water closets, 2 bath tubs, and 3 lavatories. Using the permissible pressure loss of 8 psi per 100 ft, the size of branch determined from Table 2 and Figs. 1 and 4 is found to be 1J in. Items entering the computation of pipe size are given in Table 6. , COOLING WATER PIPING Water is very frequently used in refrigeration systems, cooling towers and other similar installations. In designing the piping system of such installations, the principles of hydraulics, as already outlined, are em ployed. Nevertheless, there are several practical items having particular . application to cooling installations. They are outlined in the following paragraphs, and it is important that the designer be familiar with them. In choosing pipe material, the problem of corrosion should be kept in mind to prevent defects in the system. If the water does not have drastic corrosion characteristics, wrought iron or steel piping may be used; otherwise, galvanized steel piping may be preferred. If sea water is used as the circulating medium, it is advisable to use alloys such as admiralty metal in pipe and tubing. In refrigeration condensers where water is the cooling medium, iron pipe is commonly employed. In regard to assembly, cast-iron flanges or welded joints are to be pre ferred to screwed joints wherever possible. Valves used in circulating systems may be of the globe, gate, or angle Table 7. Pipe Sizes for Cooling Towers* Rated Tons op Reprig. Cooling Water GPM Pipe Sizes (Nominal Inches) Inlet to Tower Outlet from Tower 3 to 5 7 to 15 20 25 35 50 75 100 150 200 250 10 to 18 20 to 45 65 86 115 170 225 300 460 600 750 n' 2 2i 2i 3 3 5 5 5 6 8 li 2 3 4 4 4 6 6 8 8 8 Water Services 1115 types. If water is the circulating medium, brass valves are usually used. However, if the circulating medium is an electrolyte, such as brine, then it is preferable to use valves made of the same material as the piping itself. The friction loss in the piping may be determined from Fig. 4 for fairly rough pipe. If the coolant is brine, a correction for the proper density must be made. Experience indicates that in sizing piping for cooling sys tems, a pressure drop of the order of 2 to 3 psi per 100 ft of pipe length, and a fluid velocity of 3 to 8 fps, yield most economical results. In the case of cooling towers, the amount of circulating water is about 3 gpm per ton of refrigeration, when based on a design wet-bulb tempera- Table 8. Maximum Daily (24-Hr) Requirements for Hot Water in Gallons Apartments , and Private Homes Hotels Office Buildings Hospitals No. op Rooms 10 11 12 13 14 15 10 17 18 19 20 1 60 70 80 90 100 120 140 160 180 200 -- -- -- -- -- -- -- -- -- Number op Bathrooms 23 4 __ __ 120 140 160 180 200 220 240 260 280 300 -- -- -- -- -- -- __ __ __ __ 200 220 240 260 280 300 325 350 375 400 -- --. -- -- . - .-- __ __ __ __ __ __ 250 275 300 340 380 420 460 500 540 580 620 -- -- Room with basin ... Room with hath--transipTtt Room with bath--resident.............. 2 Rooms with bath ..................... 3 Rooms with bath.................................................... Public shower.............................................. Public basins................................. Slop sink.......................................................... White collar worker Coer oeraon) Other workers (per person)........ Cleaning per 10,000 sq ft........................... . . Per bed................................................. .. 5 __ __ __ __ __ __ __ __ __ __ 450 500 550 600 650 700 750 800 850 ah ture of about 76 F. Table 7 gives pipe sizes frequently used for various sizes of cooling towers, assuming a hot-water temperature of 95 F and a cold-water temperature of 85 F.2 ESTIMATING HEATING LOAD AND STORAGE CAPACITY The maximum daily and the maximum hourly hot water demand form the basis for the selection of the heater and the storage tank. In general, two thirds of the total daily water consumption is hot water. For residential dwellings, a design value of about 20 to 30 gal per capita per day may be assumed, but it should be remembered that the hot water used will depend on the number of rooms and the number of bathrooms in 1116 CHAPTER 49 1956 Guide any house or apartment. Table 8 gives estimates of the maximum hot water requirements in 24 hr in various types of buildings. In estimating the size of hot water storage tank required, and the heating capacity to be provided, either from the boiler or from an independent domestic hot water heater, it is necessary to know the total quantity of water to be heated per day, and the maximum amount which will be used in any one hour, as well as the duration of the peak load. . In cases where the requirements for hot water are reasonably uniform, as in residences, apartment buildings, hotels, and the like, smaller storage capacity is required than in the case of factories, schools and office build ings, where practically the entire day's usage of hot water occurs during a very short period. Correspondingly, the heating capacity must be pro portionately greater with uniform usage of hot water than with inter mittent usage, where there may be several hours between peak demands during which the water in the storage tank can be brought up to tempera- Table 9. Estimated Hot Water Demand Characteristics for Various Types of Buildings Type op Building Hot Water Required Max. Hourly Demand in Relation to Day'b Use Duration op Peak Load Hours Storage Capacity in Relation to Day's Use Heating Capacity in Relation to Day's Use Residences, apartments, hotels," etc. . Office buildings Factory buildings 40 gal per person per day* 2 gal per person per day* 5 gal per person per day* Restaurants v 1/7 1/5 1/3 # 4 2 1/5 1/5 2/5 1/10 1/7 1/6 1/8 i/io Restaurants 3 meals per day Restaurants 1 meal per day 1/10 1/5 8 1/5 2 . 2/5 1/10 1/6 At 140 F ture. As a general rule, it is desirable to have a large storage capacity in order that the heating capacity, and consequently the size of the heater, or the load on the heating boiler, may be as small as possible. . In estimating the hot water which can be drawn from a storage tank, it should be borne in mind that only about 75 percent of the volume of the tank is available, since, by the time this quantity has been drawn off, the incoming cold water has cooled the remainder down to a point where it can no longer be considered hot water. Where steam from the heating boiler is used to heat domestic hot water, the computed load on the boiler should be increased by 4 sq ft EDR (equiva lent direct radiation) for every gallon of water per hour heated through a 100 deg rise. The actual requirement is (100 X 8.33)/240 = 3.48 sq.ft per gal heated 100 deg. The value of 4 allows for transmission losses. There are two methods in common use for estimating the hot water requirements of a building: (1) by the number of people, and (2) by the number of plumbing fixtures installed. Where the number of people to be served can be reasonably estimated, the data in Table 9 may be used. Example S: Determine the heater size and storage tank capacity for a residence housing five people. Solution: From Table 9, a residence housing five people would have a daily re Water Services 1117 quirement of 5 X 40 = 200 gal. per day, and a maximum hourly demand of 200 X 1/7 = 28.5 gal. The heater should have a storage capacity of 200 X 1/5 = 40 gal, and a heating capacity of 200 X 1/7 = 28.5 gal per hr. The conditions given in Example S may be cited as average. It is pos sible to vary the storage and heating capacity by increasing and decreasing one over the other. Such a condition is illustrated in Example 4- Example 4: Determine the required heater capacity for an apartment housing 200 people, if the storage tank has a capacity of 1000 gal. What heater capacity will be required if the storage tank is changed to 2500 gal capacity? Solution: Assume an apartment house housing 200 people. From the data in Table 9: Daily requirements = 200 X 40 = 8000 gal. Maximum hours demand = 8000 X 1/7 = 1140 gal. Duration of peak load = 4 hr. Water required for 4-hr peak = 4 X 1140 = 4560. If a 1000 gal storage tank is used, hot water available from the tank = 1000 X 0.75 = 750. Water to be heated in 4 hr = 4560 -- 750 = 3710 gal. Heating capacity per hour = 3710/4 = 930 gal. . If instead of a 1000 gal tank, a 2500 gal tank had been installed, the requiredfieat- m g capacity per Vhour wou,ld, ube4--5--6-0--------(-2-5-0--0---x----0--.7--5- )- = 671 ga,l. -------- ' Table 10 may.be used to determine the size of water heating equipment from the number of "fixtures. To obtain the probable maximum demand, multiply the total quantity for the fixtures by the demand factor in line 11. The heater or coil should have a water heating capacity equal to this probable maximum demand. The storage tank should have a capacity equal to the probable maximum demand multiplied by the storage capacity factor in line 12. Example 5 will illustrate the procedure. Example S: Determination of heater and storage tank size for an apartment build ing from number of fixtures. 60 lavatories............................................. ...................... X 2 = 120 gal per hr 30 bathtubs...............................:............... ...................... X 20 = 600 gal per hr 30 showers.................................................. ..................... X 75 = 2250 gal per hr 60 kitchen sinks......................................... ...................... X 10 = 600 gal per hr J5 laundry tubs......................................... ...................... X 20 = 300 gal per hr Possible maximum demand........................................... = 3870 gal per hr Probable maximum demand.......................... = .3870 X 0.30 = 1161 gal per hr Heater or coil capacity................................. ................. = H61 8al Per hr Storage tank capacity................................... = 1161 X 1.25 = 1450 gal Although, in private dwellings a water temperature of 140 F is reason able for dishwashing, in public places sanitation regulations call for 180 F water. Most of the dishwashing machines now available on the market require 180 F water. The amount of 180 F water needed in restaurants per day may be determined according to the method outlined by the American Gas Association,! in the following paragraphs: 1. Multiply the number of meals per day by the number of dishes per meal (6 for low-price restaurants, 8 for medium-price restaurants, and 10 for high-price restau rants) to determine the total number of dishes per day. 2. Divide the total number of dishes per day, as determined by method in para graph 1, by the average number of dishes per rack to find the number of racks per day. 3. Multiply the number of racks per day by the gallons of 180 F water (using 1.5 for single tank machines and 0.75 for two tank machines). This product will give the gallons of 180 F water per day for rinse sprays. . 4. Multiply the number of meal periods per day (one, two or three) by the dish- 1118 CHAPTER 49 1956 Guide washing tank capacity in gallons, giving the gallons of 180 F water per day necessary to fill the tanks. / 5. Add values from paragraphs 3 and 4 to obtain the total number of gallons of 180 F water required per day. For purposes other than dishwashing, a considerable amount of 140 F water is also used. To find the daily 140 F water requirement in a res taurant, multiply the total number of meals served per day by the gallons of 140 F water per meal. Low priced restaurants on the average utilize 0.9 gal of 140 F water per meal, while medium- and high-price restaurants use 1.2 and 1.5 gal per meal, respectively.1 - METHODS OF HEATING WATER Hot water may be heated either by the direct combustion of fuel, by an intermediate carrier such as steam or hot water, or by electrically heated 10.Table Hot Water Demand per Fixtures for Various Types of Buildings Gallons of water per hour per fixturet calculated at a final temperature of 14-0 F Apart MENT House Club Gym Hos nasium pital Hotel Indus trial Plant Office Build-' ING Pri vate Resi dence School y.m: oa. 1. Basins, private lavatory 2. Basins, public lavatory 3. Bathtubs........................ 4. Dishwashers................... 5. Foot basins.................... 6. Kitchen sink.................. 7. Laundry, stationary tubs.............................. 8. Pantry sink.................... 9. Showers........................... 10. Slop sink......................... 11. Demand factor.............. 12. Storage capacity factor* 22 46 20 20 15 50-150 33 10 20 20 5 75 20 0.30 1.25 28 10 150 20 0.30 0.90 22 2 2 8 6 8 12 30 20 20 30 50-150 50-200 20-100 12 3 3 12 20 20 20 225 0.40 1.00 23 10 75 20 0.25 0.00 23 10 75 30 0.25 0.80 225 20 0.40 1.00 2 .2 6 20 15 3 10 22 15 8 30 20-100 20-100 3 12 10 20 15 0.30 2.00 20 5 _ . io 75 225. 15 20 0.30 0.40 0.70 1.00 28 10 225 20 0.40 1.00 * Ratio of storage tank capacity to probable maximum demand per hour. surfaces. The simplest method is to have the fire on one side of a metal barrier and water on the other. In such a method, if the surfaces foi transferring heat are small, and if the water carries a heavy proportion of precipitable salts, the water passages may soon become clogged with re sultant cracking or burning of the surface. A familiar example of such trouble is the water back in the kitchen stove, or the pipe coil inserted into the firebox of a warm air furnace or small boiler. The critical water tem perature at which the lime, magnesia, etc., collect on hot surfaces, varies with the character and proportions of the solids, but generally such deposits are not a serious trouble below 140 F. Coal-burning, direct-fired water heaters may be constructed of cored cast-iron sections, or of steel. In some cases the external appearance of the cast-iron sections is the same as in heating boilers, but internally the cores are changed to enable the sections to withstand the city water pres sure. In small capacity water bieaters, efficiency is not considered so important as low first cost and ability to maintain a fire at a low rate of combustion, and consequently, such beaters are generally built with a dry Water Services 1119 section or fire-brick lining at the base of the fire-pot to prevent too much chilling of the fuel. While mud and scale will eventually clog the water ways of any direct-fired heater, increased life may be obtained by pro viding a three-way cock in the return line between the heater and the bottom of the storage tank, so that water can be blown through the heater or the tank separately, at full line pressure, to clean out loose sediment. Clean-out openings in the bottom of the heater are advantageous, if used by operators of water heaters for periodic cleaning out of sediment. Oil-burning, direct-fired water heaters usually are of steel, and operate with higher flame temperature and better efficiency than commensurate sized coal-burning heaters. As they have the same tendency as coal boilers to accumulate lime deposits, the water passages should be large in cross-section and accessible for periodic cleaning. Gas-burning, direct-fired water heaters may be: of the instantaneous or storage type. Instantaneous heaters are generally constructed of spiral water tubes of copper, around which the products of combustion circulate upward from high capacity burners. Storage-type heaters may include Fig. 8. Indirect Water Heater in one unit an insulated storage tank, a combustion chamber, flues, burner equipment, and controls, or may consist of a separate storage tank and external direct-fired water heater, which may be a so-called side-arm heater for small capacity, or a gas-fired boiler for larger capacity. Gas boilers used for direct hot water supply must be able to withstand the city water operating pressure. While direct-fired gas heaters are used generally for residences and small installations of 100 gal storage capacity or less, indirect heaters are recommended for larger installations. Chimney connections for all direct-fired, fuel burning water heaters are an important consideration. Refer to Chapter 17. Electric water heaters for domestic hot water supply are described in the section Heating Domestic Water by Electricity in Chapter 42. In the indirect method, either steam or hot water is used for heating the water. With steam, the water to be heated is preferably circulated around the outside of the steam tubes which are submerged within a tank. A typical indirect heater using steam is shown in Fig. 8. The coils usually are of copper, and are U-shaped to permit expansion and contraction. The shell may be of steel, with a protective coating or with a special inside protective lining, or may be of copper or copper alloy. Where straight heating tubes are used, one end of the tube is usually expanded into a floating head to take care of expansion. The coils should be capable of I'hot water to fixtures Fig. 9. Indirect Water Heater Mounted on Side op Boileb . easy withdrawal for inspection and for removal of scale. Instead of steam, the heating medium may also be hot water inside the tubes. Another method of transferring heat from a heating boiler to the domestic water is illustrated in Fig. 9. The water heater is generally a cast-iron shell within which there is located a spiral copper coil. Hot water from the boiler circulates inside the shell and around the coil, and returns to the boiler, while domestic water from the storage tank circulates inside the coil. The storage tank should be installed with the bottom of the tank as far above the boiler as possible. Horizontal storage tanks of less than 18 or 20 in. diameter are not recommended because of the difficulty , of preventing the hot and cold water from mixing, and especially is this an important consideration when large quantities of water are withdrawn. In Fig. 10 the heat transfer surface is placed inside the boiler instead of in a . separate vessel, but otherwise the operation is similar to that of Fig. 9.' This arrangement with vertical tank is commonly used for small domestic installations. Sometimes the heating element is located inside of the larger type fire tube boilers and small residential boilers. In this case the heat transfer sur face is in the form of a number of straight copper tubes, with rear U-bends or' a floating head, inserted through a special opening in the boiler. While the coil may be placed in the steam space above the water line of a steam boiler, it is usually placed below the water line. Long coils of small diam eter tubing, immersed in the water, are widely used without storage tanks. The rate of flow through the coil is limited by the friction loss in the coil, Fig. 10. Indirect Water Heater Placed in Boiler Water Services 1121 and by fittings and restrictions, so that the water attains the desired temperature in one passage through the coil. This arrangement is fre quently found in oil burner installations where the heating boiler, either steam or hot water type, is used to supply hot water during the summer. A thermostatic three-way mixing valve is frequently used to maintain a uniform temperature of the hot water supply to the plumbing fixtures. In order to reduce clogging by precipitated solids, water heating plants sometimes develop steam in a closed circuit, transferring the heat through a tubular heater to the domestic water. The water in the primary heater, exposed to the high temperature of the fire, is repeatedly used and hence, has no appreciable tendency to deposit scale,; while the domestic water, heated by steam at a much lower temperature than that of the fire, also exhibits a much reduced tendency to precipitate dissolved salts. Water . characteristics, the effect of impurities and means of improving the quality of the water are important items, as brought out in Chapter 43. COMPUTING HEAT TRANSFER SURFACE The area of the inside surface of a heating coil may be determined from Equation 2. Q X 8.33(1, - I.) U Xtm (2) where A = surface area of coil, square feet. Q = quantity of water heated, gallons per hour, fi = hot water outlet temperature, Fahrenheit, ti = cold water inlet temperature, Fahrenheit. , U = coefficient of heat transmission, Btu per (hour) (square foot) (Fahrenheit de gree logarithmic mean temperature difference). For copper or brass coils U = 240 (steam) and 100 (hot water). For iron coils V = 160 (steam) and 67 (hot water). tm logarithmic mean of the difference between the temperature of the heating medium and the average water-temperature, and is approximately: (ft ~i~ ti) U- 2 t, = temperature of the heating medium, Fahrenheit. Equation 2 may be used to check the heating coil ratings under tempera tures other than those stated in the manufacturer's published ratings. Example 6: What area of copper transfer surface will be required to heat 70 gal of water.per hour from 40 to 180 F with boiler water at 220 F? Solution: t, (180 + 40)~ 110 70 X 8.33(180 - 40) 7.42 sq ft 2 100 X 110 For instantaneous submerged heaters, the surface required will depend upon (1) the velocity of water in the tubes, (2) the boiler water tempera ture, (3) the inlet water temperature, (4) the outlet water temperature, (5) the cleanliness of the coil surface, and (6) the condition of the boiler water surrounding the coil. If the heater is located in the water of an ac- 1122 CHAPTER 49 1956 Guide lively steaming part of a boiler, the heat transfer may be twice as great as would be obtained if the water surrounding the coil were circulating slowly. Ratings of instantaneous water heating coils will therefore vary greatly, depending upon the assumptions made regarding the conditions of operation.; The values of the coefficient of heat transmission for in stantaneous heaters, shown in Table 11, are conservative. For a' coil in which heat is transferred from steam to water, the value of V = 300 s/v may safely be used (v = velocity of water in feet per second). The rate of heat transfer, between steam or water as the carrier, and the domestic water, is influenced by the rate of movement of both the carrier and the water which receives the heat. For this reason, where the transfer occurs from heating system water to domestic water, it is good practice to install a circulating pump to insure rapid movement of the boiler water. In view of the high condensation rates obtained when steam is used with gravity circulation from the boiler, as when there is a sudden demand followed by an inflow of cold water, the bottom of a steam heating transfer element always should be at least 30 in. above the boiler water line, and the steam and condensate return pipes should be of liberal size. Otherwise,. Table 11. Coefficient of Heat Transfer of Instantaneous Water Heaters U = Btu per (hr) (sq ft) (Fahrenheit degree logarithmic mean temperature difference) Boiler water temperature...................... 210 200 180 225 175 150 water hammer and reduced capacity may result, due to imperfect drainage of condensate. When connecting a transfer-type hot water, heater below the. waterline of a cast-iron steam boiler having vertical sections, there should be.a sepa rate tapping for water circulation into every section of the boiler, as shown in Fig. 9, unless the boiler has large top nipple ports providing inter-sec tional circulation. If the top nipples are entirely within the boiler steam space, no internal circulation occurs between sections. Steaming may then occur in the boiler sections not connected to the heater and, further, the unconnected sections will not deliver any heat to the water heater. HOT WATER SUPPLY PIPING It is common practice to provide circulating piping in all hot water supply systems in which it is desirable to have hot water available continuously at the fixtures. In average-sized and small residences and systems, in which the piping from the heater to the fixtures is short, return circulating piping is generally omitted in order to reduce installation cost, and to reduce heat loss from the piping, particularly during periods of no water demand. The hot water supply may be distributed by either an up-feed or downfeed piping system. Three common methods of arranging the circulating lines are shown in Fig. 11. Although the diagrams apply to multi-story buildings, the arrangements (a) and (6) are sometimes used in residential designs. A check valve should be provided in the run-out from each return riser to prevent temporary reversal of flow in the piping when a faucet is open. Proper air venting of a circulating system is extremely important, particu larly if gravity circulation is employed. In Fig. 11 (o) and (6), this is ac Water Services 1123 complished by connecting the circulating line below the top fixture supply. With this arrangement, air is eliminated from the system each time the top fixture is opened. Where an overhead supply main is located above the highest fixture as in Fig. 11 (c), an automatic float type air vent is installed at the highest point of the system, or a fixture branch is connected to the top of the main- where air venting is desired, and then dropped to the fixture outlet. . It is sometimes necessary to make an allowance for pressure drop through the heater when sizing hot water lines, particularly where instantaneous hot water heaters are used and the available pressure is low. The principles involved in the sizing of the hot water supply pipes are the same as those for the sizing of cold water supply lines. For small and medium sized installations a %-in. hot water return will be ample. For larger installations, the size of the hot water return may be computed from considerations of the heat losses in the hot water piping.4 A throttling J (a) Fiq- 11 Methods of Arranging Hot Water Circulation Lines valve should be placed in the hot water return pipe so that the rate of cir culation may be adjusted. Where the hot water piping system is exceedingly long, a water circu lator is frequently installed and controlled from an immersion thermostat (in the return line) set to start and stop the pump over approximately a 20 F deg temperature range. CONTROL OF SERVICE WATER TEMPERATURE Coal-fired boilers are usually controlled by an immersion thermostat (located in the heated water) which opens or closes draft dampers at the boiler to adjust the rate of fuel combustion. With oil or gas-fired boilers, the immersion thermostat controls the oil burner pr the automatic gas valve. The gas pilot flame usually bums continuously. With electric heaters, the immersion thermostat operates a switch on the source of energy. When steam or hot water is the medium for heating the water in the tank, an immersion thermostat 'is used to control a valve in the steam or hot water supply line. In small residence installations, using water as the carrier, a combined immersion thermostat and butterfly valve in one simple m 1124 CHAPTER 49 1956 Guide fitting may be installed in the transmitting circuit to prevent over-heating of the service water. < In residences heated by pump circulated hot water, the house tempera ture is controlled by operating the circulating pump intermittently, while domestic hot water is warmed by transfer from the house boiler, inde pendent of the pump operation. The domestic water is heated from the heating boiler the year 'round. Under such an arrangement, to prevent overheating the house by thermal circulation when the pump is not running, it is usual to insert a weighted check-valve in the house heating main so that no circulation to the house heating system can occur unless the pump operates. In summer the fire may be controlled to maintain a boiler water temperature lower than , when heating, and generally about 20 F warmer than that desired in the domestic hot water system. The immersion thermostat in a hot water storage tank should be located no higher than the center of the tank, and possibly should be even closer to the bottom, since water in a tank stratifies proportionally to the tem perature;- When hot water is removed, the cold water entering to replace it quickly reduces the temperature in the lower parts of the tank. V Water Services 1125 * Qm = 0.000056 (3) where b is the heat input of heater in Btu per minute. To prevent danger of overheating, temperature-relief devices should be used. One type of such a device has a fusible plug of metal which melts at about 212 F. The hot water' then runs from the opening until the device is serviced. A better type of relief device is one which incor porates a bellows or bimetallic disc, which opens at a temperature of 210 F and closes when the temperature drops to approximately 160 F. Another type of safety , device is a fuel cutoff switch or valve in which a fusible plug is melted by excessive water temperature. The fuel supply is cut off until the fusible plug is replaced. SAFETY DEVICES FOR HOT WATER SUPPLY SYSTEMS f* There are still numerous plumbing codes which do not have regulations for the prevention of hot water storage tank explosions. An ordinary storage tank is under certain water pressure, depending on the static pressure in the system. When the water in the tank is heated, by circulation through an external heater, or by heating units in the tank, it gradually expands. For instance, if the entire contents of a 30-gal storage tank are heated from 70 F to 160 F, there will be an in crease in volume of about one-half gallon. If the tank is connected to some supply without any intervening check valve, the increase in volume A. I causes part of the water to be pushed back into the supply line. If the * hot water reaches the water meter, it may ruin the composition discs. If back-flow cannot occur, as for example, due to the use of a check- f valve or a pressure:reduction valve.in the line, or because of temporary p shut-off of the cold-water line, the pressure in the tank rises as heating continues. Such a pressure rise, if the heating continues for any. length of time, may result in rupturing of the tank. If the tank water is not confined, continued heating would, of course, cause no increase in pressure beyond ordinary line pressure. However, the temperature would continue to increase.. If this should happen at elevated temperatures, the flashing of the water into steam might cause a serious tank explosion. In order to guard against the development of excessive pressure inside a hot water storage tank (owing to the thermal expansion of the water), it is customary to install a spring-loaded pressure-relief valve which is set to open at a pressure about 20 psi higher than the normal line pressure. The amount of water discharged by any pressure-relief device is usually quite small, since it takes' only a small quantity of water to relieve any pressure rise due to the thermal expansion of the water. The rate of discharge should be such as to limit the pressure rise for any given heat input to 10 percent of the pressure at which the valve is set to open. For any given installation, the discharging capacity should be in excess of the water to be discharged by the heater. The heater discharge Qm in gallons per minute may be computed by Equation 3: The capacity of temperature relief devices may be calculated by Equa tion 4: . Qm = 0.00086 (4) where Qm and b denote the same quantities as in Equation 3. Pressure relief valves should be installed in the cold water line near the tank out of contact with the hot water in order to prevent excessive cor rosion and lime deposit on the valve seat. Temperature relief valves, in general, must be installed at the point of maximum water temperature. SOLAR WATER HEATERS Solar heaters utilize the energy of the sun for heating water. The suc cessful operation of such heaters requires the availability of sunshine practically every day in the year, which has limited their use to Florida and the southern portions of California. When supplemented with some other means of gas, coal, or oil water heating, solar heaters may be used in climates where sunshine may be more or less intermittent. They have been used in summer homes as far north as Chicago. When properly installed and proportioned, solar water heaters render satisfactory service, especially in climates where the outside temperatures are high and ex tremely hot water is not necessarily desirable. Such installations consist essentially of a storage tank, heating coil, and hot box. The coil is installed m the hot box, and is arranged to circulate water to and from the storage tank. The advantage in the use of this type of heater is the fact that it i i| i- :i f: ;i : i If; ; i ! ii. 1A1X2A6U CHAPTER 49-------------- ---------------- 1956 Guide requires no fuel. The same materials should be used for the coil, circula tion lines, and tank. A copper coil is more efficient in absorbing heat in the.box, but galvanized iron or steel may be substituted, depending on the local water conditions, cost, and other considerations. The storage tank must be able to store sufficient heated water for the night period of about 16 hr when the coil is not functioning, or is operating under such poor sun conditions as to make its heating effect negligible. Due to the fact that the no sun period includes the night period when little or no hot water is used, an available storage of 50 percent of the average daily usage is considered adequate. Since about 25 percent of stored hot water cannot be drawn out of a storage tank before the incoming cold water reduces the temperature of all of the water in the tank to an unsatisfactory point for usage, the equation for calculating the storage capacity of the tank becomes: ' ,, Qd X 0.50 o= = 0.666Qd 0.75 (5) where S = storage capacity of tank, gallons. Qd = average daily usage, gallons. Thus, for a family of four persons using an average of 40 gal of hot water per (person) (day), the size of the tank would be 4 persons x 40 gal x 0.666 or 106 gal, and the nearest standard size of tank would be used. The tank should be well insulated to prevent undue loss of heat during the 16-hour period when the coil is inoperative, and it should be located as high as possible in the building (under the peak of the roof if such exists) so as to secure a maximum circulation head from the coil. The hot water supply line to the house;-as shown in Fig. 12, is connected to the top of the tank and serves to vent the air from the tank through the hot water faucets as fast as it accumulates. . The coil should be of the return-bend type (square or slightly rectangu lar in form), and should have the pipes running east and west, with the coil on the south side of the building where it can receive the full sun effect all day long without shadows from the building itself, or from the adjacent ob structions such as trees or other structures. The coil should be placed as low as possible in relation to the storage tank level, such as on a porch roof, the roof of a one-story extension or, if necessary, even on the ground. Both the coil and the circulation lines should be designed to facilitate the circula tion flow as much as possible, using long radius copper fittings or recessed galvanized iron fittings to match the materials of the coil, circulation lines, and tank. The coil should be inclined, as shown in Fig. 13, so that the north end is raised above the south end to secure an angle with the hori zontal of about 53 deg. This will result in the inlet end of the coil being on the south side (or bottom), and the outlet end being on the north side (or top). This will satisfy conditions along the 30-deg N latitude, which includes the portions of Florida and Southern California where these heaters are most frequently used. The hot box is usually constructed of wood on the four sides and bottom, and is insulated. Glass sash are placed oyer the top of the box, and the box should be constructed as air-tight as possible. The interior surfaces should be painted white to reflect the heat, while the coil should be painted black to absorb the heat. The box need not be deeper than necessary to house the coil and to protect it from the weather. Water Services 1127 Table 12. Suggested Solar Heateb Design Data* Design Item Based on Rate of SO Gat peb Day peb Pebson Based on Rate of 40 Gal peb Dat peb Person No. of Occupants in Residence.. J 5 Hot Water Used at Night, gal 45 67812 a45C 78 mper Derson........ HottoWtaalt.e..r..U...s.e..d...a. t Night, gal Retained in Tank, 25 per cent, gal Tank Capacity Required, gal... Hot Water Used During Day, gal Total Water to be Heated: 15 15 4 20 15 15 30 8 40 30 15 45 11 59 45 15 60 15 75 60 15 15 15 15 75 90 105 120 19 23 27 36 94 113 130 150 75 90 105 120 20 20 '5 25 20 20 40 10 50 40 20 20 20 20 20 20 60 80 100 120 140 160 2015 25 30 35 ,4> 75 100 125 150 200 60 80 100 120 140 160 Gal per 8 hr period__ Gal per hour............ Copper Coil Required: 35 4.5 70 104 135 169 203 235 270 9 13 17 21 26 29 34 45 6 90 135 180 225 270 315 360 12 17 23 28 34 39 45 Surface area, sn ft Equivalent length 1 in. coil, ft Box Size: 25 100 50 200 75 300 100 400 121 484 145 580 168 664 192 768 32 128 64 256 96 384 128 512 160 640 192 768 224 256 896 10?4 Area, sn ft Width, ft... Length, ft....... 2125 4 6 50 6 8 75 100 121 145 168 192 7 8 9 10 10 11 11 2.5 3.5 4.5 6.5 17.5 32 4 8 64 6 10 96 128 160 192 224 256 8 9 10 11 12 12 12 14 16 18 19 I31)\SUn ESeCt "d of Heatera, by H. L. Alt (A.S.H.V.E. Teanbactions. Vol. 41,1935, p. ___ , .._____ uuvvum ui uuc uujl, ui a ngnr, gage copper plate to which the pipe of the coil is soldered for good metallic contact, will add to the amount of heat received by the coil, due to the fact that this plate will receive all of the sun's rays which fail to directly strike the coil. The heat from this source is transmitted to the coil through the plate rather than from the heated air surrounding the coil. Otherwise, only part of the heat enters the coil, the balance being transmitted through the glass. Design data given in Table 12 may be used with judgment in selecting the size of solar heater coil and box for a particular application. These data are based on consumptions of 30 and 40 gal of hot water per day per person. DOMESTIC HOT WATER BY HEAT PUMP Hot water may suitably be obtained by using a heat pump installation. The hot water heater may be either a heat exchanger installed just ahead of the compressor of a heat pump installation, or may be a self-contained domestic-water heat pump. Various designs of self-contained domestic water heat pumps are avail able, and one particular arrangement is shown in Fig. 14. Hot water heating by means of a heat pump is not yet advisable where Fig. 14. Heat Pump Ahhangement fob Hot Wateb Supply *3 Ff'f ;gfi if '.! 'ift ; ! / l!` M ' (p I Wsli 11 ^IJ! JJJU " 1i] j; :l iili-lJ I `ll'ii i| 'i ji 'll d 1128 CHAPTER 49 1956 Guide high water temperatures are desired. This is due to the fact that higher water outlet temperatures result in lower coefficients of performance. For coefficients of performance of 4 or higher, the heat pump water heater may be more: economical to operate than a conventional water heater. ' Although the first cost of domestic hot water heat pumps is somewhat high, they have the advantages of eliminating products of combustion, odors and soot, and not needing a chimney. A further advantage is that they may be used for cooling purposes. With a coefficient of performance of 2| to 3, water temperatures of 140 to 150 F may be obtained.6 REFERENCES 1 Water Distributing Systems for Buildings, by R. B. Hunter (National Bureau of Standards, Report BMS79, p. 6-9). (Charts extended to flow of 0.39 gpm). * Private communication from Howard E. Degler. * Enough Hot Water--Hot Enough, by J. Stanford Setchell (American Gas Asso cia4tiPonlu,m19b5in0)g. Practice and Design, by Svend Plum (John Wiley and Sons, Inc., 1943). * Progress Report on a Heat Pump Water Heater, by P. Sporn and E. R. Ambrose (Heating and Ventilating, February, 1949, Vol. 46, p. 78). BIBLIOGRAPHY Laundry, Kitchen and Hospital Equipment, by H. C. Russell (A.S.H.V.E. Trans actions, Vol. 35, 1929, p. 45). Water Consumption, Cost and Savings, by G. C. St. Laurent (American Hotel Association, Hotel Engineering, Vol. 1, 1940). Water-Supply Piping for the Plumbing System, by F. M. Dawson and A. A. Kalinske (Technical Bulletin No. 3, National Association of Master Plumbers). Use of Solar Energy for Heating Water, by F. A. Brooks, Smithsonian Institution, WaMsheitnhgotdosn,oDf E. Cst.imating Loads in Plumbing Systems, by R. B. Hunter (Nati-onal Bureau of Standards, Report BMS65, 1940). Plumbing Manual, Report of the. Sub committee on Plumbing, Central Housing Committee on Research, Design and Con struction (National Bureauof Standards, Report BMS66, 1940). Water-Distributing Systems for Buildings, by R. B. Hunter (National Bureau of Standards, Report BMHSo79t ,W19a4te1)r. Requirements, by M. B. Mackay (Modem Sanitation, August, 1949, VoUl. r1b,apn. D30o)m. estic Water Consumption, by M. A. Pond (Journal of the American Water Works Association, Vol. 31, No. 12,1939, p. 2003). CHAPTER 50 RESIDENTIAL SUMMER AIR CONDITIONING Equipment Capacity Selection, Types of Equipment, Types of Application, Room .. Air Conditioners, Central Systems for Summer, Central Systems for Heating and Cooling, Location of Cooling Equipment, Noise, . Air Distribution Methods, Operating Costs, Effects on Future House Design IN RECENT years, summer air conditioning in residences has developed to the stage where it has become a major factor in the air conditioning field and has created a heavy interest among home-owners, builders, architects and business men. Residential cooling, particularly for the small home, received its initial impetus when equipment specifically designed for such purposes became available in the 1930's. Recently it has caught the public fancy resulting in a tremendous increase in the number of sales and installa tions. The first installations were made by using the commercial and industrial methods as the estimating basis and did not prove as satisfactory as the installer or designer desired. Actually, the difference between estimating the residential summer air conditioning and commercial summer air condi tioning loads is in the design temperature differences used, the type of internal load in the conditioned area, and the method of calculating equip ment size. -. EQUIPMENT CAPACITY SELECTION With cooling, as with heating, the proper equipment capacity selection is that which, when properly installed, maintained, and operated, will satisfy the customer. Although at present an indoor design temperature of 75 F is used only on deluxe installations, it is felt that eventually this temperature will be used as the basis for design for both heating and cooling systems. At the present time, however, most summer air conditioning installations are designed on the basis of an 80 F indoor temperature. The outdoor design conditions commonly used in each locality are those listed in Chapter 13. In calculating residential cooling loads, internal loads are not taken into consideration as much in domestic summer air conditioning as in commercial or industrial summer air conditioning. Lighting, electrical appliances, and so on, are not considered except in the cases where unusual loads are added to the conditioned area by means of certain types of appliances. These appliances, such as clothes dryers, and water heaters, should be vented to the atmosphere in order to limit their effect on the summer cooling load. - Although the methods of calculating the cooling load which are presented in Chapter 13 may be used for calculating residential cooling load, it has been found1 that the load so calculated is much greater than that which is actually' experienced in most residences. This is objectionable from at least two viewpoints: (1) it increases the capacity and consequently the 1129 if-r! 1 !J n I'fT m r>-i s :,i ! :jj ; | ^jl| Irn! t4i 231 i; i 1130 CHAPTER 50 1956 Guide . cost of the equipment installed, and (2) because of the increased size it re sults in less desirable humidity conditions within the residence. A number of manufacturers, as well as several organizations, have been working on methods of, calculating summer air conditioning loads for do mestic applications. One of these is the method developed by the National Warm Air Healing and Air Conditioning Association in conjunction with the Air-Conditioning and Refrigeration Institute. This method is based on a load at a particular time of the day and takes into consideration the amount of solar radiation and heat gain due to the temperature difference between the conditioned area and the outside area on the assumption that the peak cooling load occurs from 3:00 to 4:00 o'clock in the afternoon. Another method2 evaluates the daily average cooling load on the design day rather than the maximum instantaneous heat gain. During the time the peak load occurs the room air temperature is allowed to rise from 72 F to about 78 F, thereby taking advantage of thermal storage in the structure and furnishings. TYPES OF EQUIPMENT Low Side Three types of low sides (the equipment that actually removes the heat from the conditioned space) have been developed for residential work as follows: (1) water-cooled coil, (2) chilled-water coil, and (3) refrigerated coils. . The water-cooled coil using water directly from the supply sources, such as city water or a well is the'most simple type of installation. Cold water is circulated directly through the coil while air from the conditioned space is passed over the coil to remove heat and moisture. After the water has passed through the coil, it is wasted. To operate satisfactorily, an installa tion of this type requires water of sufficiently low temperature to chill the air enough to remove the desired amount of heat and moisture. Where a large supply of water at a cold temperature is obtainable, the water-cooled coil will operate with satisfactory results. As a general rule a water-cooled coil should not be used unless there is a supply of 52 F or colder water at the peak of the cooling season and in sufficient quantities to take care of the cooling load with a temperature rise of no more than 10 deg. Where water is not obtainable in sufficient quantities or at the required temperatures, it is necessary to chill the water to the desired temperature by using mechani cal refrigeration. This is known as a chilled-water system. In a chilled-water system, water is circulated through a closed circuit containing two coils. In one coil the water removes heat and moisture from the air in the conditioned space. In the other coil (water chiller) the heat is removed from the water by mechanical refrigeration. This type of system is called a duplex system in that the heat is picked up by chilled water and later removed from the water by means of a refrigeration system. The third method of absorbing heat from the conditioned air is by means of direct evaporation of the refrigerant in a coil with the air to be condi tioned passing over the outside of the coil surface. The heat is passed directly from the air into the refrigerant for removal. . High Side The high side of a conditioning system, the section of equipment that removes the heat from the refrigerant and reclaims the refrigerant for further use in the system may be either the air or water-cooled type. The air-cooled high side is so constructed that the heat is removed from the Residential Summer Air Conditioning 1131 compressed or hot refrigerant by passing it into a cooling coil over which outside air (air taken from outside the conditioned area and returned to outside of the conditioned area) is circulated. The major advantage of air-cooled equipment is that no water is required to accomplish the removal of heat from the refrigerant and only an electrical supply is needed. The disadvantage is that operating pressures are higher because of the inability to cool the refrigerant as much by air as by water. This results in an increase in electrical input to the compressor motor. Water-cooled equipment can be of two types. In one type the water drawn from a well or from city mains is passed through the condenser of the high side and is allowed to flow to a drain, swimming pool, a wetted roof, or to other means of disposal. Where the water supply is sufficient and at low cost, this type of water-cooled unit is the better type installation be cause of lower equipment cost and lower operating costs and quieter opera tion. In a second type, if water is in short supply or is expensive, about 95 per cent of the cooling water can be reclaimed by evaporating sufficient water to rid the remaining water of the heat picked up in the condensing unit. This can be done by the use of an evaporative condenser or a cooling tower. These units are described in Chapters 35 and 37. TYPES OF APPLICATION The common methods of cooling residences today make use of room air conditioners, central systems for cooling only, or central systems de signed for both summer cooling and winter heating. The choice between these methods is largely one of cost and the relative heating and cooling loads. . ROOM AIR CONDITIONERS Window and cabinet-type air conditioning units can be used to cool small sections of a house. The window units fit into an opening of a standard double-hung window and vary in size from % to 1 ton of cooling capacity. Room air is circulated through the unit where it is cooled, dehumidified, and filtered. No water pipes are necessary since the condenser is air-cooled; nor is a drain necessary inasmuch as the moisture condensed from the air is evaporated into the outdoor air. Electrically operated, the units can generally be plugged into existing electrical outlets although a voltage of 220 is required for units having one-horsepower motors. Cabinet units stand on the floor and require an opening in the wall through which air to cool the condenser is brought in and discharged. The room cooler is popular for use in offices or residences where the exist ing heating system does not contain provision for summer cooling or where cooling is not required in the entire space. CENTRAL SYSTEMS--SUMMER ONLY In some areas there is little or no need for heating but there is a distinct need for summer cooling. Both air- and water-cooled package cooling units are available for such installations, ranging in size from one ton to at least 15 ton capacity. To install these units it is only necessary to make plumbing and electrical connections and add the duct work required to convey air to and from the conditioned space. These units can also be used to provide r !! SI 1132 CHAPTER SO 1956 Guide central air conditioning to residences having heating systems which do not contain provision for attaching summer cooling equipment. / CENTRAL SYSTEMS--HEATING AND COOLING A summer air conditioner can be installed beside or near an existing warm-air furnace and can be connected to. the duct work if the duct system has ample capacity for the cooling operation. If it does not, additional ducts and supply outlets will be required. The conditioner is about the same size or slightly smaller than a conventional forced warm-air furnace. Year-round air conditioners require less space than a separate heating plant plus a separate summer conditioner. Usually the heating and cooling portions of a year-round air conditioner operate independently of each other. The air circulated by the fan passes through the cooling or heating portion of the equipment, only one of which is in operation at any one time. Cool air supplied to rooms is usually 15 to 25 deg lower than the tempera ture of the rooms to be cooled. The size of the ducts of year-round air condi- tioning systems are often larger than those of equivalent winter heating systems because large quantities of cool air at 55 F to 65 F must be circu lated through them. Duct systems should be designed and installed by com petent engineers in accordance with such authoritative information as the design manuals of the Air-Conditioning and Refrigeration Institute and the National Warm Air Heating and Air Conditioning Association,A. The cooled air is admitted to the room from the ducts through supply outlets. Since this air is colder, and therefore, heavier than the air within the room, it has a natural tendency to fall toward the floor. Unless the supply outlets are properly selected, located, and adjusted, the air distribu tion is likely to result in (1) a low velocity of cool air. falling on the occu pants, or (2) a high velocity stream of cool air striking a wall or other ob- struction and splashing on the occupants. Research is being conducted to determine the most advantageous type and location of supply outlets. The most commonly used outlets are registers with either fixed or adjust able vanes, and diffusers. Registers distribute the cooled air throughout the room. They are usually located either high or low in the sidewall or in the baseboard. , The diffuser type of outlet can be used in ceiling, wall, or floor. Different designs are available for each of these locations. The floor, baseboard, and sidewall diffusers blanket the walls with a curtain of cool air (or warm air in winter); the ceiling diffuser blankets the ceiling. . . . Air conditioning can be installed in homes having a hot-water heating system either by use of: 1. Room units resembling convectors and containing both heating and cooling coils. These units are used in place of the conventional radiator or convector. They can be installed in all rooms of the house to provide complete summer cooling, or they can be used in only one or two rooms. This arrangement is shown in Fig. 1. 2. A split system. The cooling coil is located in a duct through which air from the rooms is circulated, cooled, and returned to the rooms. The coil can be used for winter heating, or conventional radiators, convectors, or panels can be used to bring the heat to the rooms. The cooling equipment is located in the basement or utility room near the boiler. Valves are provided so that the same piping system can be used, to circulate heated water in winter and chilled water in summer.The piping must be insulated to prevent sweating when circulating cold water. Residential Summer Air Conditioning 1133 LOCATION OF COOLING EQUIPMENT The location of the summer cooling equipment will depend upon the type of unit. In a combination self-contained type unit, the location will depend upon accessibility to the duct system, the fuel supply, and the electrical supply. Too often, a heating or cooling unit is located by giving considera tion to installation only, without considering the usability of the basement. This may result in breaking up the basement area to such an extent that it becomes practically useless for other purposes. In a remote type combina- Fig. 1. Combination Summer Air Conditioning and Hot Water Heating System tion unit, consideration must be given to the location of the condensing unit, whether it is located in the basement area or whether the unit is lo cated in a remote area such as the garage breezeway. Preferences of the family and their habits of living must be given consideration so as to keep all space as useful as possible and still locate the equipment in such a place that it can do its intended job and be accessible. NOISE One of the prime problems of domestic air conditioning is operating noise. Due consideration must be given to location of summer air conditioning equipment, with respect to areas under bedrooms or other rooms requiring very low noise levels. Equipment is often installed without due considera tion to blower and duct sizes, with a resulting increase in noise level. Con sideration should be given to the use of vibration absorbers in refrigerant and water lines, to anti-vibration padding under equipment, and to flexible duct connectors to isolate operating sounds.. , AIR DISTRIBUTION METHODS Where cooling is installed with ducts and air outlets which serve the cooling function only, the practice and experience of comfort air condition ing for offices and commercial buildings apply directly to residential installa tion. Although cooling and heating by means of the same duct work and air outlets has been common practice in commercial and industrial-applica tions, greater care must be taken in residential applications. It has been found that low air-flow rates are desirable for warm-air heating systems,6 much lower than would be used for cooling systems. It is therefore recom mended that in a residence located in a moderate or cold climate, provision be made for different air-flow rates for summer and winter. In warmer 1134 CHAPTER 50 1956 Guide climates, however, where air conditioning is the primary consideration, the summer air-flow rate may be used the year around. . The registers may be placed either in the high sidewall or in the perimeter location. For the high sidewall applications, it is necessary that the deflec tion of the air be different for summer than it is for winter to prevent the jet from dropping into the living zone, (60 in. above the floor and below) where the velocity should be not greater than 35 fpm. For registers located at the perimeter of the residence,6 it is not necessary to change the deflec tion from summer to winter. The air distribution system should be designed for the largest air-flow rate which is to be used, as outlined in Manual No. II4 of the National Warm Air Heating and Air Conditioning Association. For small-pipe perimeter systems, it is necessary to have more outlets than for the larger duct systems. In some applications, it may be necessary to close off some registers during the winter so that adequate register-air velocities will be obtained. These registers would then be opened during the summer to give a sufficient number of outlets. ' . Recent investigations have shown7 that the use of perimeter duct systems for air conditioning gives excellent results, and that objectionable air motion does not occur within the living zone except in the immediate vicinity of the registers. Care must be taken, however, to use only registers or diffusers that are specifically designed for perimeter application. This is necessary to permit the introduction of the air into the room in a pattern which does not cause drafts. Floor diffusers which distribute the air in a fan-shaped pattern along the wall or low sidewall diffusers which blanket the wall are recommended. For supply-air temperatures not more than 15 deg below room-air temperatures, diffuser face velocities of 500 fpm are recommended.8 For supply-air temperatures 20 deg below room-air temperature, the dif fuser face velocity should not be less than 700 fpm. . OPERATING COSTS The operating cost of residential cooling equipment during a particular summer depends on variables such as the amount of sunshine and rain, the number of abnormally hot or cool days, the efficiency of the equip ment, and the local power rate. It is also influenced by human factors such as operation of equipment only during the hottest weather, opening windows at night9, and difference in preferred indoor temperatures. Never theless, it is important that lending agencies and prospective buyers of equipment be given a reasonably accurate estimate of the operating cost during normal summer weather and under usual operating conditions. Adjustments can then be made for any special conditions anticipated. The basis of a method reported10 is that the power cost S of residential cooling* equipment, expressed in dollars, is predicted from the equation where R = power rate, cents per kilowatt hour. . P = average power input to the equipment over the season, kilowatts. T = predicted total operating time of equipment, hours. Note: Symbols for Equations 1 and 2 are those used in paper.10 . For a given application, the power rate is obtained from the local public utility. The average power input depends on the particular make of Residential Summer Air Conditioning 1135 equipment and condensing method, and consequently must be obtained from the manufacturer. . The operating time T to be used in Equation 1 is found from the equation where T = 24110 C (<,, - 70) (2) D = number of cooling degree-days above 70, Fahrenheit. H = average hourly cooling load over the 24 hours comprising the design day, Btu per hour. C -- average total cooling capacity (sensible plus latent) of equipment over the season, Btu per hour. . Un -- design mean temperature = design outdoor dry bulb minus one half the daily range, Fahrenheit. Tabulated values of cooling degree-days above 70 F for various localities are not yet available. Until they are, approximate values can be obtained from degree-day maps.11 12 Values of C must be obtained from the equip ment manufacturer, whereas values of the daily range for computing tm are given in the literature.13 .. It is emphasized- that the value of H in Equation 2 is not the maximum instantaneous heat gain but the overage hourly cooling load over the 24 hours comprising the design day. Consequently, it should be evaluated by a method similar to the one reported.2 To facilitate application of the method, the original paper10 contains charts from which values of T and S can be obtained directly. - If the evaporator fan cycles with the compressor, the power cost S also represents the total operating cost for air-cooled condenser applications. For continuous fan operation the value of T is subtracted from the number of hours in the cooling season to obtain the extra hours of fan operation. Equation 1 is then used with the appropriate value of P for the fan motor only, and the result is added to the power cost during compressor operation. For water-cooled condenser applications the water cost, as determined from the operating hours, water rate and manufacturer's data on equip ment water usage, is added to the power cost to obtain the predicted total operating cost. EFFECTS ON FUTURE HOUSE DESIGN Air conditioning, like automatic heating, has brought about improved practice in residential construction, particularly in those regions where cool ing is of primary importance. Although it is true that construction practices which reduce the heating load also reduce the cooling load, there are certain considerations which are unique in their effect upon the cooling load. Special attention must be paid to window orientation and means of shading the windows. South windows may be shaded by awnings or roof overhangs, but it is not practicable to shade large window areas having an east or west orientation except by exterior solar screening of some type. The use of insulation in the walls and ceiling of the residence will reduce the cooling load appreciably. In addition, attention should be paid to adequate ventila tion of theatric. Double-glazed and weatherstripped windows, heat-absorb ing glass, planned shade tree locations, and light colored exterior wall and roof surfaces, also help to reduce the cooling load. 1136 CHAPTER 50 1956 Guide REFERENCES 1 Cooling a Small Residence with a Two-Horsepower Mechanical Condensing Unit, by H. T. Gilkey, D. R. Bahnlleth, and R. W. Roose, (A.S.H.V.E. Trans actions, Vol. 59,1953, p. 283). .' * Calculating Residential Cooling Load, by E. P. Palmatier and A. W. Carroll (Air Conditioning and Refrigeration News, April 13, 1953, p. 42). * Application Engineering Standard for Year 'Round Residential Air Conditioning (Air-Conditioning and Refrigeration Institute, 1953). .. . 4 Summer Air Conditioning, Manual No, 11 (National Warm Air Heating and Air Conditioning Association, 1953). 5 Continuous Air Circulation, Manual No. 6 (National Warm Air Heating and Air Conditioning Association, 1947). 6 Comparative Performances of Two Warm Air Perimeter Systems and Three Convection Systems, by M. E. Childs, R. W. Roose, H. T. Gilkey and S. Konzo, (University of Illinois, Engineering Experiment Station Bulletin 403, 1942). 7 Cooling a Small Residence Using a Perimeter-Loop Duct System, by D. R, Bahn- fleth, C. F. Chen and H. T. Gilkey, (A.S.H.V.E. Transactions, Vol. 60, 1954, p. 271). 8 Room Air Distribution Research for Year 'Round Air Conditioning, Part II-- Supply Outlets at Three Locations, by H. E. Straub, and S. F. Gilman. (A.S.H.V.E. Transactions, Vol. 60,1954, p. 249). * Investigation of Summer Cooling in the Warm Air Heating Research Residence, by A. P. Kratz, M. K. Fahnestock and S. Konzo, (University of Illinois, Engineering Experiment Station Bulletin 290, 1930). 10 The Operating Cost of Residential Cooling Equipment, by S. F. Gilman, L. A. Hall and E. P. Palmatier (A.S.H.V.E. Transactions, Vol. 60, 1954, p. 525). 11 Relative Cooling Requirements for American Homes, by S. S. Visher (The Scientific Monthly, November 1945, p. 211, Map 6). 18 Heat Pump Applications, by E. N. Kemler arid S. Oglesby (McGraw Hill Book Co., First Edition, 1950, p. 246, Fig. 13.7). 18 Summer Weather Data (published by The Marley Co., Kansas City, Kan., 1939, Chapter VI). . CHAPTER 51 SCHOOLHOUSE HEATING AND VENTILATING General Considerations; Factors Affecting Design: Classrooms, Other Spaces, Government and Fire Safety Regulations, Economic Considerations; Systems in Use: Open Window, Gravity and Mechanical Exhaust, Forced Air, Unit Ventilators, Panel Heating; Maintenance and Operation SCHOOL buildings present. certain special problems due to diversity of use of various spaces, differing times of occupancy, recent trends in building construction, and additional sources of odors. A school is generally a composite building, containing classrooms, large public meet ings rooms which also serve as teaching spaces, offices and administrative areas, health departments, locker rooms, toilet rooms, laboratories, shops, cafeterias, and miscellaneous other spaces such as corridors, stairways and service areas. The heating and ventilating requirements are different for each type of space. \ , GENERAL CONSIDERATIONS The uses of spaces in schools vary widely in normal operation. The usual classrooms, assembly rooms, lecture halls, auditoriums, and other similar areas have occupants of relative inactivity. Consideration must also be given to areas such as music rooms, laboratories, shops, basketball courts and gymnasiums where various degrees of activity are found. All of these areas have different temperature and ventilation requirements. Most state laws require relatively large glass areas in classrooms, thereby imposing a real heating problem upon the designer. The lower mean radiant temperatures make these rooms particularly susceptible to objec tionable drafts which the heating and ventilating system should be de signed to combat or overcome. . The areas having higher levels of activity will require lower temperatures and, due to the increase in body odor, should have relatively more ven tilation. A major aspect of time of use of the various spaces is the dual use of the building by the school and by the community, not only of the auditorium and gymnasium, which may be planned for physical segregation during the evening, but also of any of the classrooms or the cafeteria. The room used by the board of education may be in use-at any hour or time, and may require air conditioning. .......... ....... The type of construction and its effect on comfort and condensation must be considered. The tendency, particularly in the Southern States, to. encourage the use of one-story schools with outside corridors and con crete slabs on the ground has introduced many new heating problems. This construction greatly enhances the use of natural or window ventila tion because the rooms are equipped with high windows on one side, usu ally the north or northeast, and low windows on the opposite side. The amount of ventilation air is thus regulated by the adjustment of the win dows. In the extreme South there is some tendency to design schools with very light wall construction and tp omit any wall insulation, thus producing a 1137 1138 CHAPTER 51 1956 Guide wall having a low heat capacity to obtain a fairly rapid heat dissipation. This results in more comfortable conditions on warm sunny days, but also imposes a requirement for more heating capacity on cool cloudy days. The roof constructions for these buildings are also designed for low heat capacity, but do require insulation because of the extended period of sun exposure. The exposed surfaces should be light in color for maximum reflection, and the under surfaces must be arranged so that the ventilation will remove the heat which penetrates through the construction. All parts of the structure must avoid high heat retention so that the heat of the afternoon sun will not be released into the building during the following morning. The time of use, number of occupants, temperatures required, and de gree or quantity of ventilation-to be provided should of necessity be studied for each space, and equipment provided to maintain proper conditions. A complete analysis should be made of the requirements, and methods should be adopted that will provide for as many of the following functions as are indicated to be necessary: heating, ventilating, cooling, odor con trol, humidity control (to prevent or limit condensation). Schools are usually constructed only after permissive referendums ap proved by the taxpayers. School districts are mostly local public enter prises under state regulation but operating more or less individually in raising funds by taxation for school construction and operation. Most school district boards of education consider one of their greatest problems that of having the citizens of their communities vote the necessary taxes. Most boards are very susceptible to criticism from their constituents for seemingly (if not actually) spending large sums of money for luxury items. This one consideration alone has been a great factor leading to economy in construction and design. Heating and ventilating design is still strongly influenced by this consideration. It should also be remembered by the designer of heating and ventilating equipment for school buildings that such equipment requires maintenance. The maintenance required may vary from merely dusting and cleaning to wholesale replacement of parts. The trend of modem architecture to reduce wasted space is frequently over-emphasized, and causes the spaces wherein mechanical equipment is to be installed to be so classified and con sequently inadequate or inaccessible. The designer should always bear in mind that lengthy repairs to heating and ventilating equipment are always considered expensive nuisances. FACTORS AFFECTING DESIGN Some of the factors affecting design are the type and use of classrooms, types of other spaces, governmental and fire safety regulations, and eco nomic considerations. Classrooms The number of occupants and sudden changes in occupancy should re ceive adequate consideration. In departmentalized schools, rooms may be unoccupied for a period and then be filled to over-ideal capacity within a few minutes. All rooms should be at the desired temperature when the students enter at the start of the school day. They should maintain such temperature when an internal heat gain is suddenly introduced in the form of body heat and lights. Lighting in a typical classroom can be the equivalent of at least 8150 to 10,000 Btuh, depending on the type of lighting. Maximum heat gain from Schoolhouse Heating and Ventilating 1139 lighting will not coincide with maximum sun load, but the modem tendency is to keep at least the row of lights farthest from the window on in order to compensate for loss of illumination. Because of the large glass areas, solar heat is usually the largest single item of heat gain. Classrooms usually have separate shades for tops and bottoms of windows. In the South sunshades are increasingly being pro vided in the budding construction. These shades often take the form of horizontal louvers, particularly on south exposures, and are so arranged that little, if any, direct sun rays reach the glass surfaces. The louver windows on. the south exposure are often shielded from the sun by an out side corridor. Tinted glass, heat reflective glass, and glass blocks arranged with light reflective prisms are used to some extent. The orientation of these windows requires careful study in order to take the greatest advantage of the shading devices during the normal period of occupancy. Some serious consideration must be given to the direction of the prevailing wind during the shool term. Where there is a wide varia tion of direction during the school months, provision should be made to take avantage of the changes in wind direction. In all climates the problem of compensation for lighting loads, sun loads, and occupant loads imposes a variable demand on all heating and ventilating . systems. These can only be compensated for by adequate thermostatic controls. It should be noted that while the heat gains are not too much affected by the passage of the seasons the heat losses mentioned are for the design condition only. Due to the fact that there is no sun load on cloudy days and that before schools opens in the morning there are no lights' or occupants, none of the heat gains mentioned can be deducted from the required design load. It is very desirable to have a classroom at required temperature when school starts, but these loads must be compensated for by control of the heating and ventilating equipment or by manual adjustment of windows. Humidity conditioning is typical of dense occupancy applications, except that larger than average areas of low temperature surfaces make failure to control in cold weather more serious. Even in a room with an ideal occu pancy of about 25, an hourly moisture gain of almost 26,000 grains must be removed. Odor control is also required of dense occupancy applications with the additional sources of wet coats and packed lunches, if brought. It is ad visable to locate exhaust inlets or relief openings adjacent to coat racks. Where wardrobes are used, their doors are undercut, and these inlets should be located in the wardrobes. This problem is particularly acute in schools of the campus plan type. For the foregoing reasons classrooms should be provided with heating and ventilating installations that will respond rapidly to rapid changes in Other Spaces Auditoriums, laboratories, shops, office areas, service areas, kitchens (cafeteria and home economics), janitor's closets, swimming-pool rooms, toilets and locker rooms, present problems that are typical of similar spaces in other types of buildings. Chemical laboratories in high schools usually are equipped with-fume hoods and have storage rooms that should be adequately ventilated. Shops in high schools may have special require 1140 CHAPTER SI 1956 Guide ments, such as dust-collecting systems in woodworking shops, explosionproof exhaust systems in wood-finishing rooms, and underfloor exhaust gas conveying systems in autbmobile shops. Locker rooms and toilets may be used in connection with outdoor sports activities during the summer. Gymnasiums require lower temperatures and adequate ventilation with out drafts. Ventilating and heating systems should take into account the ability to divide the gymnasium in half by means of folding partition, if provided. High school gymnasiums are often furnished with collapsible bleachers, indicating a greater occupancy and higher levels at which drafts should be avoided. Combination gymnasium-auditoriums (general pur pose rooms) and gymnasium-cafeterias (eating space) should be treated so as to meet the requirements of each use. Football uniform drying rooms present a special problem of drying and odor control. ' Listening rooms (for listening to records), an adjunct to the library, are usually interior rooms and, because of sound transmission, must be sound proofed as well as ventilated. Visual-aid rooms should receive careful attention in ventilating or air conditioning because of the necessity for excluding light during use. Panel heating is frequently used in kindergarten floors, since so much of the activity in these rooms takes place on the floor. The room used by the board of education for its meetings is often air conditioned even in the northern part of the country, and even when it is the only space so treated. This is necessary because the board works during all months of the year. This room should be ventilated as recom mended elsewhere for smoking conditions. . Governmental Regulations Almost every state or territory, and in some cases counties, cities, and towns as well, as its own set of regulations governing the heating and ven tilating of school buildings. Unfortunately, most of these regulations have not been coordinated through any one central source, and consequently they vary tremendously. Each designer of heating and ventilating instal lations for schools should completely familiarize himself with the regulations of the locality in which the building is to be built and satisfy these regu lations. ! The regulations usually specify the minimum requirements. The de signer can refer to Chapter 6, Table 1, for recommended air changes, to Chapter 11 for other ventilation requirements, and to Chapter 13, Table 3 and page 278 for recommended air changes for various types of occupancy. Fire Safety Regulations Many states have fire safety regulations which limit the routing and ar rangement of ducts and vary the requirements of fire dampers. Most of these regulations are based upon the National Board of Fire Underwriters' Pamphlet No. 90 which covers the regulations for -the installation of air conditioning, warm air heating, air cooling, and ventilating systems. All installations should be made in accordance with these requirements. Economic Considerations School building program budgets' are often extremely marginal, es pecially if a succession of increases in building costs have occurred since the appropriation was voted. Under such circumstances, the board of educa tion, its architect, and its engineers, in order to get the school built, are not Schoolhouse Heating and Ventilating 1141 infrequently forced to adopt courses of action that are obviously not the most desirable or the most economical over the life of the building. Need less to say, the design of the mechanical systems should be consistent with the budget. However, the board is entitled to know precisely what penalty it will be paying for each departure from the optimum design. SYSTEMS IN COMMON USE There are several different methods- of complying with the foregoing requirements. All methods are not acceptable in all states, but all methods have been used in one form or another in this country. Open Window Ventilation The term open window ventilator usually means that there is no mechan ical or gravity ventilating equipment. Air movement is caused by openingone or more windows at the top and raising some windows at the bottom. Where classrooms have windows only bn one side this is not very effective and cannot be recommended for any part of the country. When the class room has windows on two sides, particularly when they: are at different levels, satisfactory conditions can be maintained if the teacher acts as the thermostat. In climates-where heating is required for a large percentage of .the time, open window ventilation should not be used. Gravity Exhaust Ventilation . This is the next step in producing satisfactory conditions.. Exhaust grilles are placed in the ceiling or wall away from the windows, and are connected to exhaust ducts or plenum spaces connected to roof ventilators. Due to the differential pressure, air is exhausted through these ventilators. It is, of course, necessary to open the windows in order to replace, the. ex hausted air and the heating system must be designed to heat the air as it enters the windows. Satisfactory air changes can be obtained'by this method, but it usually results in objectionable drafts. This type of system is reasonably satisfactory in mild climates but cannot be recommended where the design temperature is lower than 10 F. Mechanical Exhaust Systems ' A reasonably satisfactory arrangement for any mild climate can consist of a mechanical exhaust system where motor driven exhaust fans are con nected to the exhaust grilles as previously described. With this, arrange ment, the fans can be operated on a schedule depending upon the outside temperature. When windows are closed the replacement air is drawn from the corridor or is greatly reduced. This method usually consists of providing direct radiation along the window wall of a space to be heated and ventilated, and providing some means of positively exhausting air from the space to obtain ventilation. To make up the exhausted air, the windows are usually opened. To mini mize drafts from open windows they are constructed with inside hoppers or baffles at the bottom to cause the incoming air to deflect upward and avoid blowing directly on the room occupants at desk level. To provide sufficient heat for tempering the incoming air, the radiation is designed for the total of the normal transmission plus the amount needed to offset the chilling effect of the entering air. The air quantity calculated to require such tempering is assumed to be the same amount as the amount exhausted. The amount of air exhausted from each space is established in each state code. The control of these systems is usually all manual or a combination 1142 CHAPTER 51 1956 Guide of manual and automatic operation. When they are all manual, the ex haust fans are started from some remote point, the teacher Controls the opening and closing of the windows, and the radiation is either left uncon trolled or is manually controlled, again by the .teacher. "When controls are manualrautomatic, all of these functions are controlled as described except that an automatic valve is installed to control the steam or hot water flow to the radiation in an attempt to maintain room temperature conditions. With this system, odors and humidity are presumed to be controlled by increasing or decreasing the window opening to admit more or less outdoor air (up to the amount being exhausted). Cooling is provided in a similar manner. The results, while passable, are frequently haphazard, drafty, or stuffy, and depend to a great extent on the individual preference of the teacher. Direct Radiation Many schools employ direct radiation or, in some cases, convectors or continuous fin-type heating pipes in connection with all of the systems of ventilation described. The radiation should be well distributed along the outside wall. Where possible a radiator should be placed under each win dow or made practically continuous. Unless thermostatic control is to be installed, hand valves must be provided so that each teacher can regulate the amount of radiation being used. The automatic control of these types of heating systems can be arranged by zones (where rooms have common orientation and common use) with the disadvantage of attempting to find the room with the average condi tions, or by separate control for each room. Forced Air Systems (Central Direct-Fired) Since schools require forced ventilation in many areas, many different types of central systems have been utilized. All of the available warm air furnaces have been used. These systems for schools are divided into as many zones, each having its own control, as possible. In addition to the common central system similar to the type used in homes without zoning, the two types most frequently used in school building have been: . 1. The type which takes a mixture of outdoor and return air through a fan and filter, and discharges it in either of two paths, over the surfaces of a warm air heater ot through a by-pass around the heater, with mixing at the outlet of the heater to control the temperature of the air supplied to the rooms. This requires one supply duct from the heater to each room or zone so controlled. 2. The type of system known as the double duct system which has in it one main duct from the heater and another one which has by-passed the heater, both ducts being run parallel to each other to a point just behind the room supply outlet where dampers are installed to mix warm air and cool air to obtain the desired outlet temperature. ' These systems usually operate with a fixed (manually variable) outdoor , air quantity, the balance of the air being obtained by returning it from the spaces. The air is released into the spaces either through wall grilles, ceil ing outlets, or outlets in the window sills discharging upward. Excess air is removed from the spaces, or rather is allowed to escape from the spaces in many instances, through relief grilles into the corridors, the corridors returning the air to central points where connections are made to the suc tion side of the central fan unit. In some states return of air is not permis- Scoolhouse Heating and Ventilating 1143 sible. Under these conditions the excess air is removed from the build ing through either gravity ventilators or power exhaust fans. - There have been some installations in which the return air is allowed to escape from the room, through wall grilles, into the corridors and thus back to the unit. While this arrangement is less expensive, it is not recom mended because in case of fire all the smoke is drawn through the corridors which should be kept clear for the escape of the students and teachers. Corridor return is prohibited in many states and cities. Proper design should avoid drafts from cold wall surfaces and from duct outlets. Air discharged toward cold surfaces should be designed for a terminal velocity of 50 fpm at approximately one-quarter the distance from a cold wall. Grille outlet velocities in excess of 600 fpm under 9 and 10 ft ceilings are likely to cause drafts at some points in the occupancy zone. . Forced Air Systems (Central Steam) In these systems the air supplied for ventilation is tempered by auto matically controlled steam coils and the normal heat loss for each room is supplied by direct radiators or convection. Provision is made for exhaust equal to the amount of outdoor air supplied. There are many variations of these systems, and they may include any features of central systems described in Chapter 30. Hot water may also be used as the heating medium. This type of system can also be designed to provide the entire heating requirement without using any direct radiation. This arrangement is quite satisfactory, but must be controlled for zones of similar occupancy which have exactly the same orientation. Where used as a two-duct sys tem as described under Forced Warm Air Systems in preceding section, much more satisfactory results can be expected. Unit Ventilator Systems Unit ventilators are used for supplying heat and ventilation for individual classrooms. These units and their controls are described in Chapters 25 and 39. They can be combined or furnished with storage cabinets, book shelves, extensions for additional direct radiation, and extended grilles to discharge upward along the window sills. As in previous systems described, the excess air must be provided a means of escape. Panel Heating Systems A number of schools have employed panel heating of various designs. It is particularly adaptable in the slab-on-ground type of school to overcome the cold floor. It is also quite adaptable to the open corridor type of school using natural or window ventilation in the warmer climates. In the cold climates it should be augmented by a tempered-air ventilating system as previously described. Design data are given in Chapter 24, but the designer must include ample thermostatic control which employs some means of varying the water temperature in inverse ratio to the outside temperature. With well-insulated walls and ceilings this feature usually results in an appreci able anticipation of the beating requirements. Several control systems are outlined in Chapter 39. Individual room control is desirable but not mandatory. A separate zone control for each exposure and for each floor is absolutely necessary for satisfactory results. 1144 CHAPTER 51 1956 Guide When coils are installed in the floor slab, these systems must be operated continuously (day and night). Night setback is not desirable, but when used it must be placed on the room thermostats and the setback must not exceed 10 deg. Generally room temperatures, read on wall thermometers placed 60 in. from the floor, can be one to two deg lower than with other types of systems for equal comfort. Floor temperature must not exceed 85 F on design days except that a perimeter band, not exceeding 15 in. from the walls, may have a surface temperature of 100 F. Floor panels should not be expected to warm the large volumes of air required for school ventilation, and for this reason a tempered air supply is required in all except mild climates. MAINTENANCE AND OPERATION Controls, boilers and combustion equipment, fans and mechanical heat ing devices, traps and valves, all need attention at least annually. Every designer must use extreme care in selecting equipment that will require a minimum of attention, and see that it is accessible for service. While school custodial forces may be competent, they frequently have more work than can be handled during normal working hours. Unusual maintenance problems may therefore result in deterioration of equipment and systems. While first cost is important, final selection of equipment should not be made without consideration of the overall cost which, in cludes maintenance and service. CHAPTER 52 INSTRUMENTS AND MEASUREMENTS Temperature Measurement, Pressure Measurement, Air Flow Measurement, Air Change Measurement, Humidity Measurement, Heat Transfer Through Building Materials, Evaluation of Thermal Environment, Combustion Analysis, Smoke Density Measurements, Determination of Air Contaminants, Sound and Vibration Measurements HEATING and air conditioning engineers and technicians require instruments for both laboratory and field use. Somewhat more pre cision is attainable and'essential in the laboratory, where research and de velopment are undertaken, than in the field, where acceptance and adjust ment tests are conducted. Some instruments have attained an adequate state of development, while others fall far short of the desirable. For in stance, temperatures can now be measured readily with ample accuracy for most purposes, while a convenient and precise method for determining or comparing the dustiness of atmospheres is lacking, and improvement in existing hygrometers and humidity controllers is essential. Codes and standards covering different types of heating and air condi tioning devices and apparatus have been promulgated by various authori tative organizations, and instruments essential for performance or com pliance testing are enumerated in the relevant publications.1' * *. The present purpose is to discuss the use and characteristics of the more im portant instruments. . ; TEMPERATURE MEASUREMENT6-6 Thermometers , Any device capable of indicating temperature is a thermometer, but in common usage the term thermometer without qualification has come to signify the ordinary mercury-in-glass temperature indicating device. This type has a useful range from --40 F, the freezing point of mercury, to.about 1000 F, at or near which the glass usually softens. Lower temperatures can be measured with alcohol-filled thermometers for which the range is about --94 F to +248 F. The better thermometers have their scales, either Fahrenheit or Centigrade, etched with acid into the glass which forms thesr stems. The probable error for etched stem thermometers is plus or minus one scale division, and calibration is desirable for much test work. Thermometers are calibrated during manufacture at not less than two temperatures--the freezing and boiling points of water--and calibration is often accomplished with the instrument completely immersed in a bath at the known temperature. The intervening scale divisions are then ap plied to the stem. When such a thermometer is used with the stem in completely immersed, a correction known as the stem correction is neces- 1145 1146 CHAPTER 52 1956 Guide sary for accurate measurements, and its magnitude is usually computed by means of the following formula: ' K = 0.00009 D (J, - h) (1) where K = correction to be added, Fahrenheit degrees. D = number of degrees on the thermometer scale which are not immersed, h = temperature indicated on the thermometer, Fahrenheit, u = temperature of the non-immersed mercury column, Fahrenheit, 0.00009 = difference in the coefficient of expansion of the mercury and glass. - When a thermometer is used in a liquid or in air or gas near room tem perature, the effects of radiation can often be ignored, but when the tem perature of hot air or gas is desired, means are usually provided for mini mizing the effect of radiation.7 These include bright metallic shields around the thermometer bulb, and the use of aspirated thermometers in which a stream of the air or gas is drawn at considerable speed across the bulb and increases the influence of the gas temperature on the thermom eter indication. In any case, to prevent errors in temperature measure ments, there should be ample circulation so that the thermometer will indicate a true temperature of the medium under observation, and ample time should be allowed for the thermometer to reach the same temperature as the medium. In reading a thermometer the eye should be at the same level as the top of the liquid to avoid parallax. Industrial-type thermometers are available for permanent installation in. pipes or ducts. These instruments are fitted with metal guards to prevent breakage, and are useful for many purposes. However, the con siderable heat capacity and conductance of the guards or shields prevent such thermometers from following closely the fluctuations in a medium of varying temperature. Thermocouples When two wires made of dissimilar metals are joined by soldering, weld ing or merely by twisting, a thermocouple or thermo-junction is formed. An electromotive force, which depends upon the temperature of the junc tion, is found to exist between the wires. When the wires are joined at two points a thermocouple circuit is formed. If one junction is kept at a temperature different from the other, an electric current flows through the circuit due to the difference in emf developed by the two junctions. This phenomenon is employed for temperature measurements in thermocouple systems, one junction being ordinarily kept at a constant temperature, as in an ice bath, while the other junction is placed at a point at which it is desired to observe the temperature. In practice it is desirable to utilize emf to indicate temperature because, at small or zero current flow, the resistance of the circuit is unimportant. A high resistance millivolt meter is useful in some cases but the potentiometer yields better results. In the potentiometer the electromotive force generated by the thermocouples is balanced against an electromotive force from the battery so that observa tions are made with no flow of current through the thermocouple circuit. A conventional arrangement is illustrated in Fig. 1. The thermocouple leads A-B are so connected that their polarity opposes that of battery G. If the position of E on the graduated slide wire rheostat DF is adjusted until galvanometer G shows no current flowing, resistance DE will indicate directly the voltage generated by the thermocouple. In order to calibrate n- 1 Instruments and Measurements 1147 the instrument, switch S is thrown over to the standard cell .circuit while rheostat R is adjusted so that the galvanometer shows zero current. Bat tery C then exerts the known voltage of the standard cell at DH. The act of adjusting rheostat D-F (Fig. 1) for zero current flow is known as balancing the potentiometer. Automatic self-balancing instruments of both the indicating and recording types are on the market. They usu ally contain an automatically compensating cold junction to avoid the use of an ice bath,' and special thermocouple wire is furnished with them from the factory. The choice of materials for thermocouple wire is determined by the range of temperature to be measured, the protection from corrosion afforded the couple, and the precision and service life required. In general, copper vs. constantan is suitable for temperatures up to 700 F, iron vs. constantan up to 1500 F, 'and -ehromel vs. alumel up to 2i200 F. Higher temperatures re-1 Fig. 1. Basic Circuit and Connections for Thermocouple and Potentiometer quire the use of noble metal thermocouples (platinum vs. platinum-rho dium). In addition to the higher initial cost of a noble metal couple, it does not develop as high an emf as the base metal couples do. Impurities make large differences in the performance of thermocouple wires and for this reason calibration of samples from each spool of wire is essential for precise work. Data on wire can usually be obtained from the manufac turer. With a suitable potentiometer, small wires serve as well for thermo couples as large ones, and the fineness of the wires is limited only by consid eration of mechanical strength and convenience in handling. Small couples respond more promptly to changes in temperature and are less affected by radiation than large ones. Heavy gage couples, however, are necessary for high temperature work where corrosion of the wire is a problem. For use in heated air or gases, thermocouples are often shielded,8 as are ther mometers, and aspirated thermocouples are sometimes used. An arrange ment has been described for avoiding error due to radiation. It involves several thermocouples of different sizes, the true temperature being esti mated by extrapolation of readings to zero diameter.9 By the use of thermocouples, temperatures at remote points may be indi- 1148 CHAPTER 52 1956 Guide eated or recorded on conveniently located instruments; average tempera ture may be readily obtained by connecting several couples in parallel or in series; and temperatures may be obtained within thin materials, narrow spaces, or otherwise inaccessible locations. Thermocouples in series with every alternate junction maintained at a common temperature will give an emf which, divided by the number of couples to give the average emf10 per couple, may be used to find the aver age temperature; This series arrangement of thermocouples, often called a thermopile, can have extreme sensitivity and is useful in detecting very small changes in temperature. . . . Thermocouples in parallel, having the similar metals of a number of couples connected together and run to a common cold junction, will cause an indication on a potentiometer which is the true average emf only if the electrical resistances of the parallel junctions are the same.10'11 Temperatures of surfaces below red heat are difficult to determine by any other means than thermocouples. For this pin-pose, a thermocouple of fine wires is preferable to minimize the possibility of error due to the conduction of heat along the wires. It may be attached to a metal surface in any of several ways. For permanent installations, soldering, brazing or peening may be desirable. A small hole is drilled for the peening opera tion; the thermocouple is inserted and the metal is peened to retain it. The fact that the thermocouple is in electric contact with the surface is unimportant in usual circuits. For temporary arrangements, couples may be attached by means of surgical or cellophane tape. For many boiler or furnace surfaces, furnace cement serves very well. The thermocouple may be attached by means of the cement when the surface is cold, and must be treated gently and usually supported until the cement dries, due to heat, and hardens--after which it has ample strength. It is good practice to use as little cement as possible, and also to plaster the wires to the surface for an inch or so from their junction to avoid errors due to heat conduction along the wire. Electric insulation between the wires should be perfect except at the junction since, otherwise, the indicated emf will be between those existing at the junction and at the short circuit. Resistance Thermometers Resistance thermometers depend for their operation upon the change of electric resistance of metal with change in temperature. The resistance generally increases with rising temperature. Their use largely parallels that of thermocouples, although readings tend to be unstable above 950 F. Two-lead temperature elements are not recommended, since they do not permit correction for lead resistance, Three leads to each resistor are necessary to obtain consistent readings. A typical circuit used by several manufacturers is shown in Fig. 2. In this design a differential galvanometer is used, in which coils L and H exert opposing forces on the indicating needle. Coil L is in series with the ther mometer resistance AB; and coil H is in series with the constant resistance R. As the temperature falls, the resistance of AB decreases allowing more current to flow .through coil L than through coil H. This causes an in crease in the force exerted by coil L, pulling the needle down to a lower reading. Likewise, as the temperature rises the resistance of AB increases, causing less current to flow through coil L than through coil H. This forces the indicating needle to a higher reading. Rheostat S must be ad justed occasionally to maintain a constant flow of current. Instruments and Measurements 1149 As compared to the thermocouple,' the resistance thermometer does not require a cold junction, and it can be simply scaled for more accurate meas urements; but, generally because of its construction it is more costly and is apt to have considerable lag. It gives best results when used to meas ure steady or slowly changing temperature; For accurate results the entire thermometer coil must be exposed to the temperature to be measured. Pyrometers ... . The pyrometer is the usual instrument for measuring high temperatures such as those of incandescent bodies or furnace interiors. There are two. types. In the radiation pyrometer the radiant energy from an observed surface falls on a thermopile, and the emf generated by the pile, measured Fig. 2. Typical Resistance Ther mometer Circuit and Connections by a galvanometer or potentiometer, is an index of the surface temperature. With the optical pyrometer a narrow spectral band, usually red, emitted by the surface, is matched visually with the filament of a special electric lamp. The emf necessary to cause the'filament to match the surface in brightness is the index of the temperature of the surface. Pyrometers are calibrated by means of various metals with known melting or freezing points. Portable as well as laboratory models are manufactured. Color Indicating Crayons Crayons are available, the marks of which change color or melt at speci fied temperatures. Such crayons have been sold in boxes covering, the range from about 100 F to about 800 F in 100 deg steps; with a precision of some 10 deg. They are' a rough but convenient means of determining temperatures, and of locating isothermal lines on surfaces below red heat. Pressure Gages PRESSURE MEASUREMENT The Bourdon is the most common type of pressure gage, and its appear ance probably is familiar to any one having an acquaintance with power plants or laboratories. The essential element of such a gage is the Bourdon 1150 CHAPTER 52 1956 Guide tube, a metal tube of oval cross-section curved along its length to form al most a complete circle. One end is closed and the other is connected to the vessel in which the pressure is to be measured. With an increase of pres sure, the tube tends to straighten, and vice versa. The resulting motion of the closed end is communicated by suitable linkages to a needle moving over a graduated dial. If the range is above about 20 psi, such gages are' usually calibrated by means of a dead weight tester, whereby known pressures are produced in a fluid by imposing known weights on a piston of known area. Gages are commonly set to read accurately at or near the pressure of probable use. Gages of several different types or qualities are available on the market.12 Suction gages and pressure gages with ranges below about 20 psi are ordinarily calibrated against mercury manometers. Manometers The manometer is a simple and useful means for measuring partial vacuum and low pressure. It is, moreover, a primary instrument; it does not require calibration, and it is often used as a standard for the calibration of other instruments. It is so universally used that both the inch of water and'the inch of mercury have become accepted units of pressure measure ment. In its simplest form, the manometer consists of a' U-shaped glass tube partially filled with a liquid. A difference in height of the two fluid columns denotes a difference in pressure in the two legs, which is propor tional to the difference in height. For converting manometer readings into other pressure units, certain proposed standard factors are applicable for precise work. These are based on a standard gravitational acceleration of 32.1740 ft per (sec) (sec) and are as follows: 1 Standard Atmosphere = 14.696 lb per sq in. = 29.921 in. mercury at 32 F = 33.96 ft water column at.68 F For most ordinary purposes, the following figures are of ample accuracy. 1 Atmosphere = 14.7 lb per sq in. = 29.9 in. mercury = 34.0 ft (408 in.) water column Manometer tubes should be chemically clean. The bore is not impor tant, except insofar as it affects the meniscus through wetting or surface ten sion. Bores of at least ^ in. for rough, and \ in. for more precise, measure ments are recommended. Liquids other than water are sometimes used for low pressure measurement and, when this is done, the readings must be corrected for the density of the fluid used. For measuring pressure differences of a few inches of water, or less, U- gages are often set at an angle for scale amplification. In many gages of this type, commonly termed draft gages or inclined manometers, only one tube of small bore is used and the other leg is replaced by a reservoir. The scale is calibrated to read in inches of water, and it is necessary to use a fluid having the same gravity as that for which the gage was originally calibrated, or to apply a correction if another fluid is used. Such gages may be checked one against another. For more accurate calibration the gage may be checked against a micromanometer or a calibrating device known as a hook gage.13 The accuracy of a draft gage is dependent on the slope of the tube, and consequently the base of the gage must be leveled carefully. It is not desirable to use a slope of less than 1 in 10. Where pressures are read under extreme conditions of temperature, and calibration is possible only at nor mal temperature, it is necessary to correct for the change in density of the Instruments and Measurements 1151 liquid in the manometer.14 For measuring low pressure differences to within 0.001 in. of water, very sensitive micromanometers are available, such as the Illinois or Wahlen, the Meriam, the Trimount, and the Emswiler.13 16 When using a manometer or other pressure gage for measuring air flow, by means of orifices, the type of duct openings used for manometer con nections and their location are important. Where velocities are low, as in some plenum chambers, or where the flow is free of large eddies and parallel to the walls of a duct, a drilled hole cleared of burrs and at right angles to the stream, is satisfactory.17 For higher velocities, it is common practice to provide four holes or taps around the periphery of the duct; Diamet rically opposite pairs of taps are connected together, and then such pairs are manifolded together. An alternate method involves the use of the Pitot tube, shown in Fig. 3. This instrument should be pointed up-stream, parallel with the air flow. .Where the flow is not axial or parallel to the side walls of the duct, a very close approximation of the static pressure and the flow direction can be obtained by a Fechheimer tube.18 Barometer The simplest and earliest type of barometer consists of a glass tube some what more than 30 in. long filled with mercury, and inverted in a cup par tially filled with mercury. The height of the mercury column in the tube above the mercury surface in the cup is a measure of the existing atmos pheric pressure, except for the slight pressure of the mercury vapor in the space above the mercury in the tube. This can ordinarily be ignored. Elaborate mercury barometers, fitted with vernier scales, are available. For precise work, corrections must be made for the thermal expansion of the mercury and of the scales.19 The instruments are usually cali brated for 32 F mercury and 62 F scale temperature, and the correction 1152 CHAPTER 52 1956 Guide C to be subtracted from the observed barometer's height is obtained by means of Equation 2. . = h(t - 28.630) (1.11231 --10978) where . .. . C = correction to be subtracted, inches of mercury. . h = observed height, inches of mercury. . 1 = observed temperature of the barometer, Fahrenheit degrees. . Standard atmospheric pressure at sea level is 29.921 in. Hg, . and since normal atmospheric pressure decreases about 0.01 in. Hg for each 10 ft increase in elevation, it is important to make a correction if the elevation of the barometer is not that of the test apparatus. In many cases the barometric reading may be obtained from a nearby Weather Bureau Station, in which case inquiry should be made as to whether the value is for station or sea level pressure. Atmospheric pressure may also be measured by an aneroid barometer which is easily portable. In this type, variations in atmospheric pressure deflect the thin surface of a sealed diaphragm capsule. Most commercially available aneroid barometers are not as accurate as the mercurial type, and the best require occasional recalibration. Open-scale aneroid barometers are more expensive than common mercurial barometers. Most of the pres sure gages used in engineering work indicate gage pressures, that is, the difference between the pressure being measured and the atmospheric pres sure. Such pressures are called gage pressures. Absolute pressure may be obtained by adding barometric pressure and gage pressure algebraically. AIR FLOW MEASUREMENT The theory of various means for measuring the flow of fluids is discussed in Chapter 4, Fluid Flow. Heating and air conditioning engineers are called upon to measure the flow of air more often than that of other gases, and usually the air is measured at or near atmospheric pressure. Under this condition, the air can be treated substantially as an incompressible fluid which implies that simplified formulas can be used with sufficient accuracy for the solution of many problems.20 The Pitot Tube The construction of the Standard Pitot Tube13 is shown in Fig. 3. formula for velocity used in conjunction with it, is as follows: The , = 1096.5 (3) where . Va= velocity, feet per minute. h,, = velocity pressure (Pitot tube manometer reading), inches of water, p = density of air, pounds per cubic foot. ' , '. - Since the velocity in a duct is seldom uniform across any section, and since a Pitot tube reading indicates a velocity at only one location, a traverse is usually made to determine the average velocity so that the flow can be computed. Suggested Pitot tube locations for traversing round and rectan- Instruments and Measurements 1153 gular ducts are shown in Fig. 4. In general, the velocity' is lowest near the edges or corners, and greatest at or near the center. For this reason a large number of readings should be taken (in the case of round ducts not less than 20) along two diameters at centers of equal annular areas. In rectangular ducts the readings should be taken in the center of equal areas over the cross-section of the duct. - The number of spaces should not be less than 16, and need not be more than 64. When less than 64 are taken, the number of equal spaces should be such that the centers of the areas are not more, than 6 in. apart. In determining the average velocity in the duct from the readings given, the calculated individual velocities or the square roots of the velocity heads must be averaged. It is incorrect to use the average Fio. 4. Pitot Tube Traverse fob Round and Rectangular Ducts velocity head for this purpose. Pulsating or disturbed flow will give er roneous results and therefore, if possible, the Pitot tube should be located at least 1\ diameters down-stream from a disturbance such as that caused by a turn; or a criss-cross type of flow straightener should be installed in the duct 1 diameters ahead of the Pitot tube.13 Flow straighteners do not equalize flow velocity across a duct. They merely serve to improve the precision of measurements. Equalization can be effected, if desirable, for measuring purposes by the use of wire netting, perforated plates or cloth screens across the duct. Many forms of Pitot tubes, other than the one described, have been used and calibrated.21 A double-ended tube,22 one end pointing down-stream, and one up-stream, is sometimes used for low velocities, but it should be carefully calibrated for accurate results. A special form of this tube design consists of two straight J in. tubes soldered together, closed at the end, and with a 0.04 in. hole in each tube opposite the line of contact. This tube is useful in exploring velocities in exhaust inlets, such as hoods placed around grinding wheels. To meet special conditions, different sized Pitot tubes which are geometrically similar to the standard tube can be used. Plate Orifices Application of the Pitot tube is often inconvenient when velocities are low, because the resultant velocity pressures become so small that extra ordinary means are necessary for measuring them. In addition, velocity 1154 CHAPTER 52 1956 Guide surveys of the whole cross-sectional area of a duct are inexpedient when numerous test runs are in prospect. Chiefly for these reasons orifices are favored for much test work. There are two types: the plate orifice and the shaped orifice or nozzle. Plate orifices are simple to construct and con venient to use, in that a frame can be made to support them in the duct such that one can be removed and another inserted when it is desirable to use an orifice of a different size. Formulas for Orifices . In the heating and air conditioning fields it is usually convenient to obtain orifice pressure drops in inches of water column, temperatures in Fahrenheit degrees and barometric pressure in inches of mercury. The air flow is usually desired in cubic feet per minute at the existing condition, so that velocities in various ducts can be computed, and in pounds per hour so that computations of heat transferred by the air can be based on weight, tem perature change and specific heat. Equation 4 is applicable. Qa = 5.2KYD* 4/Z hw (4) where Qm = air flow, cubic feet per minute* K = orifice coefficient. Y = expansion factor, see Fig. 5. D = orifice diameter, inches. d = pipe diameter, inches. Tt -- temperature of air at orifice, Fahrenheit, absolute. B{ = absolute pressure ahead of orifice, inches of mercury. 3^ -- absolute pressure after orifice, inches of mercury. hw = pressure drop through orifice, inches of water. . As most laboratories are less than 1000 ft above sea level, precision is adequate in many cases if standard atmospheric pressure, 29.92 in. Hg, is assumed. Equation 4 then becomes Qu = 0.95 KYD1 y/TtK (5) After the flow in cubic feet per minute is determined, it can' be expressed in pounds of air per hour by means of the relation . W = 60 RTt - P = pressure, pounds per square inch, absolute. R = 53.3, the gas constant for air. Tt = temperature of the flowing air, Fahrenheit, absolute. <6) The thin-plate square-edged orifice often has a discharge coefficient K near 0.60. The exact value depends on the location of the connections, the pressure drop, the diameter ratio of orifice to pipe, and the sharpness of the edge.43' 24 Other information.on orifices.and their use is contained in Chap ter 4, Fluid Flow. Shaped orifices or nozzles have the advantage, if well made, that their discharge coefficients are close to unity so that the probability of large errors is less. Orifices of this type have been adopted for several specific Instruments and Measurements 1155 purposes, and designs are described in the Unit Heater Code1 and Unit Ventilator Code,2 and in A.S.R.E. Circular 133 entitled Standard Methods of Rating and Testing Air Conditioning Equipment. In some instances nozzles are used in multiple so that the capacity of the testing equipment can be changed by shutting off the flow through one or more nozzles. An apparatus designed for testing the air flow and capacity of air conditioning equipment is described by Wile25 in an article in which pertinent informa tion on nozzle discharge coefficients, Reynolds numbers, and the resistance of perforated plates is also presented. Such apparatus in some laboratories is commonly referred to as a code tester. The Venturi meter is like the nozzle, except for the addition of a down stream transition section that reduces the pressure drop through the meas uring apparatus. In some cases air velocity through a duct, heater coil, or heating unit may Fig. 5. Expansion Factor fob Air and Other Diatomic Gases Applicable to Flange, Radius and Vena Contracta Taps be most conveniently estimated by computation from the heat given up by the coil, and the temperature rise (measured by thermocouples) of the air passing through. It is essential to have a uniform flow over the entire inlet and outlet of the heater at the plane of temperature measurement. Propeller or Revolving Vane Anemometer The propeller or revolving vane anemometer consists of a light revolving wind-driven wheel connected through a gear train to a set of recording dials that read the linear feet of air passing in a measured length of time. It is made in various sizes, 3 in., 4 in., and 6 in. being most common. Each instrument requires individual calibration. At low velocities the friction drag of the mechanism is considerable. In order to compensate for this, a gear train that overspeeds is commonly used. For this reason the correc tion is oftqn additive at the lower range and subtractive at the upper range, with the least correction in the middle range of velocities. Most of these are not sensitive enough for use below 200 fpm. Anemometers of this type are practically standard for wind measurements, and may be used in large 1156 CHAPTER 52 1956 Guide ducts where the air flow is not seriously altered by the presence of the instrument itself. ' I Deflecting Vane Anemometer The deflecting vane anemometer consists of a pivoted vane enclosed in a case. Air exerts a pressure on the vane as it passes through the instrument from an up-stream to a down-stream opening. The movement of the vane is resisted by a hair spring and a damping magnet. Tim instrument gives instantaneous readings of directional velocities on an indicating scale. With fluctuating velocities, it is necessary to average visually the swings of the needle to obtain average velocities. This instrument is very useful for studying motion of the air in a room,26 and in locating objectionable drafts. Various attachments are available, such as the double tube arrangement for determining velocities in ducts, and a device for measuring static pres sures. Each instrument, and the attachments for it, must receive indi vidual calibration. For determining average velocity in a duct, it is neces sary to traverse the duct as Is done when using the Pitot tube. Measurement of Velocities at Inlets and Outlets of Ducts In the field it is often desirable to make volume measurements at the face of the supply openings. It is rare to have access to the interior of duct sections where the flow is sufficiently uniform for measurement. For ac curacy, the instrument and its application should be checked on a similar approach and grille in the laboratory before use in the field. Tests have shown that the propeller type anemometer can be used suc cessfully on most of the common types of supply grilles.27, 28 The core area is divided into equal squares, and the anemometer is held against the face of the grille for the same length of time in each. To obtain the air volume in cubic feet per minute, the average corrected velocity in feet per minute thus obtained is multiplied by the average of the gross and net free area of the grille (core) in square feet. On exhaust openings, the anemometer traverse is made as described previously. The air volume may be determined by multiplying the cor rected velocity in feet per minute by the gross core area of the grille in square feet, and by a coefficient for average conditions of 0.85.2 When a propeller type anemometer is held in a stream of varying veloc ities, it tends to indicate higher than the true average, that is; the speed of the propeller is nearer to the top velocity in its area than it is to the mini mum velocity. This is the main reason for the large difference in ratings of unit ventilators by the anemometer method, and by air volume measure- ments in a duct approach to the inlet.30 Anemometers can be used within their range at the face of supply grilles when properly applied. In principle, it is a case of finding the velocity at many points, and using the average thus found with the correct discharge area at that cross-section. The deflecting vane anemometer equipped with, a jet on the end of a rubber tube has been found especially convenient and accurate on supply grilles.3* On modern air conditioning grilles, the`core, area is used without a correction coefficient when the jet is held one inch away from the face of the grille. At this distance, the constriction due to the thin bars has disappeared, since the small air jets have reunited and the air stream has not yet spread beyond the core dimensions. With deflecting grilles the exploring jet should be turned to the angle giving a maximum reading. With suitable traversing tips and calibration, this instrument Instruments and Measurements 1157 may also be used on exhaust grilles if proper grille factors are applied.32 Those contemplating such measurements should consult the references cited. . Smoke is a qualitative tool which is very useful in studying air move ments. Satisfactory smoke can be obtained from titanium tetra-chloride (which, however, is very irritating to nasal membranes) or by mixing potassium chlorate and powdered sugar (a non-irritating smoke) and firing the mixture with a match. This latter process evolves considerable heat, and it should be confined in a pan away from flammable materials. The titanium tetra-chloride smoke lends itself to spot determinations, particu larly for leakage through casings and ducts, as it can be easily handled in a small pistol-like ejector. The fumes, of aqua ammonia and of sulfuric acid, if permitted to mix, form a white precipitate which is useful for some purposes. Two bottles, one containing ammonia water and the other acid, are connected to a common nozzle by means of rubber tubing. Air is forced over the surfaces of the liquids in the bottles by means of a syringe, and the two streams, upon mixing at the nozzle, form a white cloud. The Kata Thermometer '' The measurement of air current velocities within enclosed spaces, such as the rooms of a house, is usually a tedious undertaking. However, useful data can be obtained by using the instruments described in following para graphs if they are maintained in calibration, and the user understands the operation and limitations of the instruments.33 One of the instruments useful for determining the velocity of air currents in free spaces is the Kata thermometer which is essentially an alcohol thermometer with a large bulb. The instrument is heated above 100 F, and then the time in seconds required for it to cool from 100 to 95, when located in the air current, gives a measure of the air speed. It is important to have the Kata thermometer dry before taking the reading. Each Kata has its own factor etched on the stem, and this factor must be used with its cooling formula or chart for obtaining the velocity. The Kata thermom eter is useful in exploring ventilated spaces to determine whether the proper air movement and distribution are being maintained. It is also used in determining the cooling power of the atmosphere, since it loses heat by radiation and convection when dry, and by radiation, convection, and evaporation when the bulb is equipped with a wetted cloth covering.34 Thermal Anemometers If a suitable sensing element is heated electrically at a fixed rate and exposed to an air stream, the temperature' difference between the element and the stream becomes a measure of velocity by calibration. In the hot-wire anemometer, a very fine heated wire is employed as a resistancethermometer element whose temperature may be determined accu rately 30 In the heated-bulb thermometer type, a heating wire is wound around the bulb of a mercury-in-glass thermometer, and the temperature difference between this thermometer and a similar unheated one serves as an index of air speed.37 The heated-thermocouple anemometer is cali brated to give velocity in terms of the differential emf between heated and unheated thermo-junctions exposed to an air stream.35, 38 Combined measurements of air temperature and velocity are particularly useful for air distribution studies, and automatic recording potentiometers or resist ance-thermometer devices facilitate spatial traverses. A correct calibra- 1158 CHAPTER 52 ? ! r 1956 Guide tion of thermal anemometers requires consideration of .the effects of tem perature, humidity and pressure upon the air properties which influence convective heat transfer.38 With sensing elements of simple shapes, for which convection data are known, thermal anemometers may be designed, both thermafly and electrically, for desired characteristics. Directional sensitivity is controllable. Thermal anemometers are convenient and practical for low velocities. n . Infiltration or Air Change Measurement .. - The total air leakage into an existing building caused by wind, and tem perature difference forces can be determined with considerable accuracy by determining the decrease in concentration of a tracer gas. Hydrogen and helium have both been used rather successfully as tracer gases in corn junction with a sensitive thermal .conductivity comparator.39 About one percent of tracer gas by volume is .introduced into the room or building, and the tracer gas is thoroughly mixed with the air. Tim decrease in con centration of the tracer gas. is observed at regular time intervals with a thermal conductivity meter as infiltration dilutes the mixture. The fol lowing formula is used to calculate the infiltration from the observed concentration measurements: ; Y - V (7) where ; C0 = initial tracer gas concentration, percent. C = concentration of tracer gas after t minutes, percent. v -- volume of room or building, cubic feet. k = infiltration rate, cubic feet per minute. e = 2.718, for natural logarithms. . Closets and cupboards should be left open during such infiltration tests so the entire space will have the same rate of change of tracer-gas concen tration. . HUMIDITY MEASUREMENT - ' Psychrometers Any instrument capable of measuring the humidity or hygrometric state of the air is a hygrometer. A psychrometer is a particular kind of hygrom eter which consists of two mercury thermometers, one of which has a cloth wick or sock applied to its bulb. For use, the wick is wetted with water and ventilated with air moving at a recommended rate of 900 fpm or more, rela tive to the instrument.40 In the simpler and more common type, known as the sling psychrometer, the two thermometers are mounted side by side on a frame fitted with a handle by which the device can be whirled through the air. The motion is arrested for reading the thermometers, and contin ued until the thermometer readings become steady. Due to evaporation, the wet-bulb thermometer will indicate a lower temperature than the drybulb thermometer, and the difference is known as .the wet-bulb depres sion. Charts and tables are available showing the relation between the thermometer readings and the humidity.19,41 Data are usually based on a total pressure of one standard atmosphere. For precise work, a correction is necessary for barometric pressure and is usually made by multiplying the observed relative humidity by the ratio of the observed to the standard atmospheric pressure. For air temperatures below 32 F, the water on the wick may either freeze or super-cool, and its state must be known and a proper table or chart used, Instruments and Measurements 1159 since the wet-bulb temperature is different for ice and for water. Some operators remove the wick from the wet-bulb for freezing conditions and dip the bulb in water a few times, allowing the water to freeze on the bulb between dips and to form a film of ice. Since wet-bulb depression is slight at low temperatures, precise temperature readings are essential. In the ventilated or aspirated psychrometer, the thermometers remain stationary, and a small fan or blower or a syringe is used to move the air across the thermometer bulbs. Various designs have been employed in the laboratories, and several commercial models are available. The Dew-Point Hygrometer In the usual form of these instruments, means are provided for cooling, and of observing the temperature of, a surface which is exposed to air. The temperature at which visible condensation occurs on the surface is con sidered the dew-point of the air. With the dew-point temperature known, the relative humidity and other properties of the air can be taken from tables and charts (See Chapter 3). A bright surface or metallic mirror is usually employed to improve the visibility of the dew deposit, and various means are used to cool the mirror from the back, including evaporating ether or another, refrigerant, or a stream of air passed through dry ice. Dew-point temperatures, in some cases, are observed by means of thermom eters in fluids in contact with the back of the mirror, but in modem instru ments thermocouples are used, and are soldered or welded to the mirror itself. The dew-point apparatus is not so commonly used as the psy chrometer, probably because it is less convenient. It is usable, however, for higher temperatures than the wet- and dry-bulb psychrometer, and should be considered for dew-points near or above the boiling point, as in the case of flue gases. Special apparatus for high precision has been con structed, in which the photronic cell and a light source are used for dew or frost detection instead of visual inspection. Hair Hygrometers Many materials, especially organic materials, change in dimensions with changes in humidity, and many devices have been designed in efforts, to utilize this action in simple and effective humidity indicators, recorders and controllers. Unfortunately, no material has been found which can be relied upon to perfectly reproduce its action when exposed to repeated identical changes in humidity. The field has been well explored, and in strument and control manufacturers are practically unanimous in the selection of human hair for this service. The hair hygrometer consists of from one to several strands of hair with a mechanism whereby changes in length of the strands, due to changes in humidity, cause an indicator to move across a dial. In the recording instru ment, a pen is moved across and marks a moving paper ribbon, indexed in relative humidity. In a controller, or humidistat, the motion makes or breaks an electric contact governing the air conditioning equipment. Such devices require initial calibration and, for precise work, frequent recalibra tion or setting, especially if they are exposed to extremes of either high or low humidity. For continuous operation, with only slight changes in humidity, some operators report satisfactory reproducibility of results. Electrolytic Hygrometers The dampness, and therefore the electrical resistance of a salt film, varies with the humidity of the atmosphere to which the fijm is exposed, and at 1160 CHAPTER 52 1956 Guide least two types of instruments based on this fact have been developed. The Dunmore hygrometer was originally designed for use in radio-sondes or small balloons, and means were devised whereby the device transmits humidity data back to earth in the form of a radio signal. In the more usual form, this hygrometer consists of a dual 'winding of small wire on a non-conducting tube. The whole is coated with an electrolytic film, usually containing a salt such as lithium chloride, which forms an electric connec tion between the windings. Means are provided for determining the elec trical resistance of the film, which is an indication of the humidity. In the radio-sonde, variations in the resistance of the film affect the frequency of an oscillating circuit. These hygrometers are usually calibrated by com parison with a wet- and dry-bulb psychrometer. For calibration for some purposes, particularly for use at sub-zero temperatures, means have been provided for producing atmospheres of known humidity.42 Advantages of instruments of this type for some scientific and industrial purposes are becoming apparent, and some forms of them are on the market. The Weaver type hygrometer is particularly useful for determining the humidity of air or other gas in pipes or closed vessels at various pressures and temperatures. It consists of a threaded plug carrying a central elec trode insulated from the plug, except for a gelatinous electrolytic film. The film is exposed to the air or gas from the pipe or vessel, and provision is made for determining its electrical resistance. The hygrometer, or detector, is mounted in a manifold equipped with valves whereby the film can be alter nately exposed to the test gas, and to a standard gas having a known abso lute humidity. The pressure of the standard gas is varied until contact with it establishes the same resistance in the film as the test gas, and the humidity of the test gas is then determined by computation based on the gas laws. Chemical Hygrometry The humidity of an atmosphere can be measured directly b^ extracting and weighing the water vapor from a known sample. For precise labora tory work, powerful desiccants such as sulphuric acid and phosphorus pentoxide are used for the extraction process, whole for some purposes, calcium chloride, lithium chloride or silica gel are satisfactory. Freezing the water vapor out of a measured stream of air or gas with solid carbon dioxide, and weighing the resulting ice, is a similar operation. A thermal conductivity method for gas analysis can be used for temperatures above 212 F, or for very low humidities.43 HEAT TRANSFER THROUGH BUILDING MATERIALS I ii % V. .V-, 1 If hi! % y Thermal Conductivity y? The thermal conductivity (k value) of an insulation, as defined in Chap- V ter 9, is a unit heat transfer factor. Practically universally accepted for the conductivity determination of flat insulation is the guarded hot plate, which is described in ASTM test method C-177.44 In its simplest form it ; . consists of an electrically heated plate and two water cooled plates. Two -.- identical specimens or slabs of a material are required for a test,, and one is mounted on each side of the hot plate. A cpld plate is then pressed against the outside of each specimen by a clamp screw. The heated plate is divided . into two portions: the central or measuring section, and the outer or guard . ^ section. During tests the two sections are maintained as nearly as possible at the same temperature. The purpose of the guard section is to minimize c. errors due to edge effects. The electric energy required to heat the meas- Instruments and Measurements 1161 uring section is carefully observed and, converted to Btu per hour, is divided by the area and the temperature gradient to obtain the conductivity of a material tested. Hot plate apparatus accommodating specimens on the order of one foot square and an inch or more thick, is common. The apparatus at the National Bureau of Standards takes specimens 8 in. square, while plates as large as 3 ft square have been used. The thermal coni ductivity of cylindrical or pipe insulation (Chapter 28) is determined in a similar manner except that an equivalent thickness must be calculated to accountfor the cylindrical shape.45 Recently there has been considerable development of transient state conductivity apparatus-utilizing a slender probe.46'474849 These instru ments are commercially available and have the advantages of rapidity and requiring a small test specimen. While useful as research and develop ment tools, the probe has not been generally accepted as have the guarded hot plate and pipe insulation apparatus. Wall Conductances .. The thermal conductances (C values) of many walls can be satisfactorily estimated from the conductivities of their components and their dimensions, but some walls are complicated by the inclusion of metal, for instance, and tests for conductance are required. The apparatus is required to accom modate large specimens representing actual construction. The shielded hot box apparatus was developed for this purpose.60 Specimens for the apparatus at the National Bureau of Standards are 5 ft long and 8 ft high, while others require different sizes, some larger, others smaller. The guarded hot box is described in the ASTM Standard Test Code for Built-up Sections, C-236-54T.60 The apparatus consists essentially of three boxes: a cold box, cooled by a refrigerating machine; a hot "box, heated electrically; and a metering box also heated electrically. Each box has an open side to be placed against the specimen. The cold box is clamped against one side of the specimen, and the hot box against the other. The hot box encloses the metering box and is kept at the same temperature to minimize heat exchanges to or from the metering box, except through the specimen. The electric energy necessary to heat the metering box is measured, converted to Btu per hour, and divided by the area and the temperature difference through the wall, from surface to surface, to yield the conductance of the wall. The transmittance or U-value of the wall is then computed by means of the surface coefficients from Chapter 9. A heat flow meter is sometimes useful for measuring steady heat flow through a wall or other building member.51'62'63 In essence, this meter consists of a plate or slab of material of known thermal resistance having attached thermocouples on both sides. For use, the device is pressed against or cemented to the wall to be tested. At steady state, the tempera ture difference through the slab, measured with the thermocouples, with the known thermal resistance of the slab, indicates the heat flow through the slab and hence, through the wall covered by it. For best results, such meters are calibrated by means of a guarded hot plate or other suitable apparatus. The chief precaution is to assure that the heat flow is steady at the time of measurement. EVALUATION OF THE THERMAL ENVIRONMENT Advocates of radiant heating emphasize the fact that comfort depends on radiant heat exchanges, as well as air temperature. For this reason sev- 1162 CHAPTER 52 1956 Guide ,eral instruments have been devised to evaluate the comfort or warmth of rooms, taking radiant as well as convective effects into account. 'Prom inent among, these are the eupatheoscope, the globe thermometer, the thermal integrator and the heated globe.64 , 65 Descriptions are contained in the references, and are omitted here because these devices are not widely . used in America for several reasons, among which is the fact that radiant heating with high temperature sources is not a chief method of comfort heating in this country.. :' . ;. . COMBUSTION ANALYSIS . There are two approaches to the problem of measuring the capacities of fuel burning devices, such as boilers and furnaces. The direct or calori metric test consists in measuring the change in enthalpy or heat content of the fluid, air or. water, heated, by the device and multiplying by the flow rate in pounds per hour to arrive at the capacity in Btu per hour.66 The indirect test, consists in determining the heat lost in the flue gases and deducting it from the heat evolved by combustion of the fuel.67 A heat balance consists in the simultaneous application of both tests to the same device. The indirect test almost invariably indicates the greater capacity, and the difference is credited to radiation from the boiler or furnace casing and unaccounted for loss. . In the case of some small equipment, the expense of the direct test is not considered justifiable, and the indirect test is relied upon with an arbitrary radiation and unaccounted for factor.67 Flue Gas Analysis . The Orsat apparatus is commonly used for analyzing flue gases. In its ordinary form, it consists of three pipettes and a means for isolating a sample of flue gas in a graduate. After measuring, the sample is expelled from the graduate into the first pipette where the carbon dioxide is ex tracted by potassium hydroxide.' The sample is then remeasured and successively passed into the second and third pipettes, where the oxygen and the carbon monoxide are respectively extracted by potassium pyrogal- late and cuprous chloride. For field testing and burner adjustment, simpler portable devices are available for carbon dioxide determination only. From curves, based on typical hydrogen content of several common fuels, efficiencies may be estimated from the carbon dioxide value obtained. . More elaborate labora tory equipment is sometimes provided for precise determination of carbon monoxide content by burning the carbon monoxide to carbon dioxide in presence of a catalyst.68, 69 In large plants, carbon dioxide recorders'are used to obtain a continuous indication of the plant's efficiency.60 SMOKE DENSITY MEASUREMENTS Ringelmann charts are widely used for evaluating the density of smoke discharged from chimneys or stacks, and smoke ordinances are based on them in some cities. Each chart is composed of a series of crossed black lines on white paper which, at a distance of about 50 ft, is visually compared with the smoke under observation. Four charts are used with different degrees of blackness as shown in Table 1. The smoke density is specified by Ringelmann numbers from 1 to 4. The photoelectric cell is used in some apparatus developed for smoke density recording in large plants. The same device is included in the test instruments and Measurements ' 1163 ing equipment for domestic oil burners described in National Bureau of Standards, Commercial Standard CS75-42.61 Under Laboratory Tests this publication contains the following section: "Smoke Determination.--After combustion has reached equilibrium, the amount of smoke in the flue gases, when viewed lengthwise through 4 feet of.the smoke pipe in accordance with the Underwriters' Laboratories, Inc., Standard for Domestic Oil Burners (Subject 296), March 1934 and subsequent revisions, shall not reduce the output of a standard photoelectric cell from 9 microamperes, with a clear smoke pipe, to less than 8 microamperes." The Commercial Standard also requires that during a test after installation, the burner shall operate with out visible smoke at the chimney top. A method of evaluating smoke produced by pot type oil burners was developed for the Institute of Cooking and Heating Appliance Manufac turers by R. N. St. John. A glass rod is interposed between a light source and a photo-sensitive cell, both before and after being exposed to the flue Table 1. Ringelmann Smoke Chabt Spacings Number of Card i 2 3 4 ~~ Thickness op Lines, mm 1.0 2.3 3.7 5.5 Distance in Cleab Between Lines, mm 9.0 7.7 6.3 4.5 gases from a heating device. The diminution of the light transmitted by the rod, due to the deposit of soot on its surface,,causes a reduction in the cell emf which is taken as an index of the concentration of smoke in the flue gases. A description of the method is contained in National Bureau of Standards Commercial Standard CS104-46.67 DETERMINATION OF AIR CONTAMINANTS Two measures of air dustiness are in use: particles per unit volume of air, and weight per unit volume of air. A comparative method consists in drawing known samples of air through a known area of filter cloth or paper, and comparing the density of the resulting spots with blackness charts or with spots from other sources. For counting, particles are captured in a device such as the SmithGreenburg impinger, the Owens jet dust counter, or in an electrostatic or a thermal precipitation device designed for the purpose.62 Counting is done with a microscope, and the method yields important results when the nature or constituents of the dust are of interest. For. a weight determination, a known volume of air is drawn through a porous crucible or thimble, and the weight gained by the thimble during the operation is the weight of the dust captured from the air sample.68 For precise work, the thimble must be dried in a desiccating chamber before weighing each time. A test method based on weight determination was used in the A.S.H.V.E Code for Testing and Rating Air Cleaning Devices Used in General Ventilation Work.64 This code was withdrawn by the Society in 1955 when it was evident that no manufacturer of filters was using equipment .such as that specified in the code. This withdrawal was ac companied by a statement that it did not imply that any other code 1164 CHAPTER 52 1956 Guide was recommended to take its place. The subject of air cleaning is un der; investigation in cooperative research now being conducted-' at the University of Minnesota. -. At the National Bureau of Standards a test method was developed for interested Government agencies, under which measured samples of the un cleaned air and of the air cleaned by a device under test are passed through filter papers.66 The ratio of the flow rates through the two filter papers is adjusted during successive tests, until the resulting dust."spots approach equality in density as shown by a photometer. The ratio of the flow rates is then indicative of the effectiveness "of the cleaner in arresting dust. A statement of an air cleaner's efficiency by any test'method, is meaningless unless the test dust is specified. Other instruments for determining gaseous and particulate air contaminants are described in industrial hygiene litera- tlir6 66 r 67, 68 ... ... . ~ ., . ' ; SOUND AND VIBRATION MEASUREMENTS ......... Approximate measurements of sound intensity can be made by aural methods. The ear is used to compare the measured noise with sounds of known strength. -'- Electrical devices, in which the ear plays no part, furnish the most satis factory means of measuring noise intensities. The sound meter consists essentially of a microphone coupled to an amplifier designed with an ear-like response. The output of the microphone is read on a sensitive direct current milliammeter graduated to read directly in-decibels. Instruments of this type, if connected with suitable band pass filters, can be used to study the intensity of the sound" over Its entire; range of frequehcies. . Electrical instruments are available for measuring the frequency,, ampli tude and acceleration of a vibrating mass. :iThey are usually more con venient and accurate than the vibrating reed tachometer, the seismic type displacement meters or the accelerometer^ 'which can also be used for this purpose. Sound level meters are discussed in several text books69-70 and standards.71 . . .... .. .. .- " REFERENCES x Standard Code for Testing and Rating Steam Unit Haters (adopted jointlyby TpeAmerican Society op Heatingand Ventilating ENGiNEBBS'and the Industrial Unit Heater AasdetationrJa'fiuary 1950;'second edition). -' " i '` * A.S.H.V.E. Standard Code for Testing and Rating Steam.Unit Ventilators (A.S.HViE. Transactions, Vol. 38, 1932, p. 26), adoprted June, 1932. : / .; ; "' 8 A.S.R..E; Standard Methods of Rating and Testing Air. Conditioning Equipment, A.S;R:.E. Circular No; 13. - , '' " '. 'c ..........' . '"A Survey of Testing Methods and Rating Limits, for Domestic Hedting Devices, by R. S. Dill (A.S.H.V.E. Transactions, Vol. 51, 1945, p. 185).. ' : * For a comprehensive treatment of temperature measurement thfe'reader is referred to Temperature, Its Measurement and Control in Science and Industry, a symposium sponsored by the American Institute^of. Physics and published by Reinhold Publishing Corp. . -- ' Temperature Measurement in Engineering, by H. D. Baker, E. A. Ryder,And N. H. Baker (John Wiley and Sons, New York). ' ' 1 . ' ._ : 7 Temperature Measurement (A.S.M.B. Power Test Code, Part 3). ^ Errors m the Measurement of the Temperature of Flue Gases, by:P. Nicholls and.W. E. Rice (A.S^H.VJS- Transactions, Vol. 35, 1929, p; 473). . * Investigation of Warm Air Furnaces and Heating Systems,'by A". C. Willard, A. P. Krats and V; S. Day. (Illinois Engineering Experiment Station, Bulletin.No. 120)... . 19 Measuring Heat Transmission in Building Structures and a Heat Transmission Meter, by P. Nicholls (A.S:H.V.E. Transactions, Vol. 30, 1924, p. 94). . ..... - / 11 Parallel-connected Thermocouples for the Testing of Gas Appliances, by Walter B. Kirk and George J. Pacanovsky (Gas, September, 1939, p. 51). Instruments and Measurements 1165-'-' u American Standard for Indicating Pressure and Vacuum Gages, Round Dial Type, with Elastic Pres sure Chamber. B. 40.1-193&-(Amervcan Standards Association). ' ** Standard Test Code for Centrifugal and Axial Fans, 1938 (A.8.H.VJZ. and N.A.F'M.) published by. NA-F.M. as Bulletin No. 110. * " x* Fan Engineering, Buffalo Forge Company, 5th Edition, p. 165. - 19 Illinois Micromanometer ( University ofIllinois, Engineering Experiment Station Bulletin No. 120, p. 91). 14 The Weathertightness of Rolled Steel Windows, by J. E. Emswiler and W. C. Randall (A.S.H.Y.E Transactions, Vol. 34, 1928, p. 527). ' '" xx Pressure Measurement (A.S.M.E. Power Test Code 1930, Part 2, Chapter 2)., -. "The Measurement of Static Pressure, by ,C. J. Fechheimer (Mechanical Engineering, August,.1927). Psychrometric Tables for Vapor Pressure, Relative Humidity and Temperatures of the Dew-Point (U. S. Department of Agriculture, Weather Bureau, Washington, D. C.). 10 For technical data refer to Fluid Meter Reports, Parts 1--1937, 2--1931; and 3--1933 (American Society of Mechanical Engineers). . .. . . 11 Technical Notes No. 546 (National Advisory Committee for Aeronautics, November^1935). . .. . ** The Characteristics of Double Pitot Tubes, by F. R. Ingram, E. Diez-Canseco and L. Silver man (A.S.H.V.E, Journal Section, Heating, Piping and Air Conditioning, November, 1942, p. 708). . ** Discharge Coefficients of Square Edged Orifices for Measuring the Flow of Air, by H. S: Bean, E.Buck- ingham and P. S. Murphy (Bureau of Standards Journal of Research, Vol. 2, 1929, p, 501). ,: Flow Measurement by Nozzles and Orifice Plates (AJo.MJI. Power Test Codes, Chapter 4 of Part 5, 1940). ' '. . .' u Air Flow Measurement-imthe Laboratory, by D. D. Wile (Refrigerating Engineering, June, 1947, p. 515). *x A.S.H.V.E. Research Report No. 1204--Entrainment and Jet-Pump Action of Air Streams, by G. L; Tube, G. B. Priester and D. K. Wright, Jr. (A.S;H.V.E. Transactions, Vol..48, 1942, p. 241). . A.S.H.V.E. Research Reports Nos. 857, 911 and 966--Measurement of the Flow of Air Through Reg isters and Grilles, by L. E. Davies (A.S.H.V.E.,Transactions, Vol. 36, 1930, p. 201, Vol. 37,1931, p. 619, and Vol. 39, 1933, p.373). x> A.S.H.V.E. Research Report No. 1162--Air Flow Measurements at Intake and Discharge Openings and Grilles, by G. L. Tuve and D. K. Wright, Jr. (A.S.H.VJ5. Transactions.-VoI. 46, 1940, p. 313). * A.S.H.V.E. Research Report No. 1092r-The Flow of Air Through Exhaust Grilles, by A. M. Greene, Jr. and M. H. Dean (A.S.H.V.E. Transactions, Vol. 44, 1938, p. 387). , .- * A.S.H.V.E. Research Report No..93(h-Investigation of Air Outlets in Class Room Ventilation,- by G. L. Laraon, D. W. Nelson and R. W. Kubasta (A.S.H.V.E. Transactions, Vol. 38, 1932, p. 463). . . ' *x A.S.H.VJE. Research Report No. 1070--Air. Distribution From Side Wall Outlets, by D. W. Nelson and D. J. Stewart (A.S.H.V.E. Transactions, Vol. 44, 1938, p. 77). :. * Measuring Air Flow, by G. L. Tuve (Heating, Piping,and Air Conditioning, December, 1941).- . ** A.S.H.V.E. Research Report No. 1140--The .Use of Air Velocity Meters, by G: L. Tuve,"D. K; Wright, Jr. and L. J. Siegel (A.S.H.V.E. Transactions, Vol. 45, 1939, p. 645) . ; ; '- 84 Temperature, Humidity and Air Motion Effects in Ventilation, by O. W. Armspach and Margaret Ingels (A.S.H.V.E. Transactions, Vol. 28, 1922, p. 103).. . ..... * A.S.H.V.E. Research Report No. 1165--Development of Instruments for the-Study of Air Distri bution in Rooms,- by A. P. Krats, A. E. Hershey and R. B. Engdahl (A.S.H.V^E. Transactions, Vol. 46, 1940, p. 351). " ........... . . ` * Development of-Testing Apparatus for Thermostats, by-D. D. Wile.(A.S.H.V.E. Transactions, Vol. 42,1936, p. 349). `\ . 17 The Heated'Thermometer Anemometer, by C. P.. Yaglou (Journal Industrial Hygiene and Toxicology, Vol. 20, October, 1938, No. 8). . ., A Simple Heated-Thermocouple Anemometer, by H. B. Nottage (A.S.H.V.E. Transactions, Vol. 56, 1950, p. 431).. 7 * ** Measurement of Ventilation Using Tracer Gas Technique, by J. Bi Dick (A.S.H.V.E. Journal Sec-, tion, Heating, Piping and Air Conditioning, May, 1950, p. 131). `' - 40 The Temperature of Evaporation, by Willis H. Carrier (A.S.H.V.E. Transactions, Vol. 24,1918, p. 25). 41A Review of Existing Psychrometric Data in Relation to Practical Engineering Problems, by W. H. Carrier and C. O. Mackey (AJSM.E. Transactions, January, 1937, p. 33; Discussion A.S.M.E. Transactions, August, 1937, p. 528). 4* Divided Flow Low Temperature Humidity Test Apparatus, by Arnold Wexler (National Bureau of Standards, Research Paper No. 1894). 48 Gas Analysis by Measurement of Thermal Conductivity, by H. A. Daynes (CambridgePress, 1933). 44 Standard Method of Test for Thermal Conductivity of Materials by Means of the Guarded Hot Plate adopted July, 1942, by A.S.H.VJE. (AJ3.TJJ. Designation C177 - 45). 1166 CHAPTER 52 1956 Guide 4S Tentative Method of Testfor Thermal Conductivity of Pipe Insulation {AJ5.TM. Designation C 335 - 54T). .. 48 A Study of Transient Heat Method for Measuring Thermal Conductivity, by D. D'Emtachio and R E. Schreiner (A.S.H.VJ3. Transactions, VoI. 58, 1952, p. 331). .. 47 Transient Heat Flow Apparatus for the. Determination of Thermal Conductivity, by F. C. Hooper' and F. R. Lepper (AJ3.H.V.E. Transactions, Vol. 56, 1950, p. 309). Development of Thermal Conductivity Probe, by F. C. Hooper and S. C. Chang (A.S.H.V.E. Trans actions, Vol. 59,1953, p. 463). 48 A Transient Heat Flow Method of Determining Thermal Conductivity: Application to Insulating Ma terials, by C. P. Lents (Canadian Journal of Technology, June 1952, Vol. 30, p. 153). bo Tentative Method of Test for Thermal Conductance of and Transmittance of Built-up Sections by . Means of Guarded Hot Box (Amerieon Society for Testing Malerials, ASTM-C - 236-49T). A.S.H.VJ3. Research Report No, 685--Measuring Heat Transmission in Building Structures and a Heat Transmission Meter, by P. Nicholls (A.S.H.V.E. Transactions, Vol. 30, 1924, p. 65). 88 A Low-inertia Low-resistance Heat Flow Meter, by R. G. Huebscher, L. F. Schutrum, and G. V. Panne- lee, (A.S.H.V.E. Transactions, Vol. 58, 1952, p. 275). ' 88 Using the Heat Flow Meter to Study Heat Transfer, by J. T. Gier and R. V. Dunkle (Refrigerating Bngineering,Vol. 62, No. 10, Oct. I954, p. 63). `` : M Instruments and Methods for Recording Thermal Factors Affecting Human Comfort, by C. P. Yaglou. A. P. Kratz and C.-E. A. Winslow (Year Book, American Journal Public Health, 36-37). bs The Thermo-Integrator--A New Instrument for the Observation of Thermal Interchanges, by C.-E. A. Winslow and Leonard Greenburg (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 149). 88 I = B =R Testing and RatingCodes for Low Pressure Heating Boilers, 1947 {Institute ofBoiler and Radiator Manufacturers), 57 Commercial Standard for Warm Air Furnaces Equipped with Vaporising Pot-Type Oil Burners, C.S. 104-26 {National Bureau of Standards). bb Rapid Determination of Small Amounts of Carbon Monoxide, by Martin Shepherd {2nd. Eng, Chem. Anal. Ed. 19, 77: 1947). 88 Determination of Small Amounts of Carbon Monoxide in Air by Various Reference Methods, by Martin Shepherd {National Bureau of Standards Journal of Research 38, 351-8; 1947 R. P. 1777). ' 80 A Carbon Monoxide Recorder, by S. H. Erats, D. A. Reynolds, H. W. Frevert and J. J. Bloomfield ( U. S. Bureau of Mines, Technical Paper No. 355, 1926). - si Commercial Standard for Mechanical Draft Oil Burners Designed for Domestic Installations, C.S. 75-42 (Notional Bureau of Standards). 83 Industrial Dust, by Philip Drinker and Theodore Hatch (McGraw-Hill Book Company, New York). ' 88 Testing and Rating of Air Cleaning Devices Used for General Ventilation Work, by S. R. Lewis (A.S.H.V.E. Transactions, Vol. 39, 1933, p. 277). 84 A.8.H.VJ3. Code for Testing and Rating Air Cleaning Devices Used in General Ventilation Work, adopted January, 1934 (A.S.H.V.E. Transactions, Vol. 39,1933, p. 225). .. 88 A Test Method for Air Filters, by Richard S. Dill (A.S.H.V.E. Transactions, Vol. 44, 1938, p. 379). 88 Analytical Chemistry of Industrial Poisons, Hazards and Solvents, by Morris B. Jacobis (Interscience Publishers, Inc., New York, 1941). . 87 The Determination and Control of Industrial Dust, by J. J. Bloomfield and J. M. Dalla Valle (XJ. S. Public Health Bulletin No. 217,1935). " Sampling and Analysis of Atmospheric Contaminants, by F. A. Patty {Industrial Hygiene and Toxi cology, Vol. I, Interscience Publishers, Inc., New York, 1948). 1* . 88 Electrical Engineer's Handbook, by Harold Pender and Knox Mcllvaine (John Wiley and Sons, New York). 78 Elements of Acoustical Engineering, by Harry F. Olson, (D. Van Nostrand Co., New York). 74 American Tentative Standards for Sound Level Meters for Measurement of Noise and Other Sounds, Z 24.3-1944 {American Standards Association). ' CHAPTER 53 CODES AND STANDARDS __ ____ ________ vwfuwwiiMi iii xauic i rcprcstjnii accepted pr&ctic6| A methods, or standards prepared and accepted by the organizations in dicated. They are valuable guides for the practicing engineer in determin ing test methods, ratings, performance requirements, and limits applying to equipment used in heating, ventilating, and air conditioning. Copies can usually be obtained from the organization listed in the reference column. Table 1. Codes and Standards Prepared and Accepted by Various Societies and Associations Subject Title Acoustics American Standard (Terminology) minology. (1951) t. Air Conditioning Code of Minirmirn Requirements for Comfort Air Conditioning (1938); Air Conditioning Code and Manual.for tbe Design and (120,000 Btu/ Hr or less) Conditioning System, (1953)! Air Conditioning Code and Manual for the Design and (Above 120,000 Installation of Mechanical Warm Air Btu/hr) Heating Systems (1950). Air Conditioning Standards for the Installation of Air Conditioning, Warm Air Heating, Air Cooling and Ventilating Systems Air Conditioning ASRB Standard Methodn of Rnf.in ^ . (Equipment) and Testing Air Conditioning Equipment (1942). Air Conditioners ASHE Standard Method* of Raflnf and Testing Air Conditioners (1949)~ (Supersedes ASRE Circular 13-42) Airplane' Air Conditioning 'Rnnipmntl A;*-. plane--General Requirements for (1948). Airplane Heaters, Airplane, Internal Combus tion Heat Exchanger Type (1949). Airplane Heaters, Airplane, Steam Type Attic Ventilation Residence Ventilation Guide (1950). Boilers I"B=R Testing and Rating Code for Low Pressure Heating Boilers (1950). Boilers Net Load Recommendations for Heat ing Boilers. Publ. semi-annually. Boilera Net Square Feet Radiation Loads in 70 Deg Fahr. Recommended for Low Pressure Heating Boilera (1948). Boilers Boilers Boilers . Standard and Short For a Heat Bal ance Codes for Testing Low Pressure Steam Heating Solid Fuel Boilera (Codes 1 and 2)(1929). ASHVE Performance Test Code for Steam Heating Solid Fuel Boilers (Code No. 3) (1929). J ASHVE Standard Code for Testing 1 Steam Heating Boilers Burning Ou Fuel (1932). Sponsor AS of A ASHVE ASRB NWAH & ACA NWAH <fcACA NPPA ASHVE NEMA RMA ACMA ASRB . SAB SAB SAB PFMA IBR HP <t ACCNA HP & ACCNA ASHVE ASHVE ASHVE Rreebencb ASA Z24.1 ASHAE NWAH <t ACA Manual No. 7 ; 4th Edition ' NWAH <fc ACA Manna] No. 9 4th Edition . NFPA or NBFU Pamphlet No. 90 1952 ASRB Circular No. 13-42 ASRB Standard 16-53 SAB - ' ARP 85B ? SAB ARP 143B SAB ARP 87 PFMA IBR HP <t ACCNA HP & ACCNA ASHAE ASHAE. ' ASHAE 1167 1168 CHAPTER 53 Table 1. Codes and Standards-- (Continued) Subject . Title Boilers Boilers Boilers ASHVE Standard Code for Testing Stoker-Fired Steam-Heating Boilers (1938). ASME Boiler Construction Code for Low Pressure Heating Boilers (1952 with 1954 Addenda). ASME Boiler and Pressure Vessel Code.(1952, 8 Vol.). Boilers (Gas) Boilers (Minia ture) - Boilers (Power> American Standard Approval Rc* ' quirements for Central Heating Gas Appliances Vol. 1, Steam and Hot Water Boilers (1951 with Addenda, 1954). ASME MiniatureBoiler Code (1952). ASME Power Boiler Code (1952 with 1954 Addenda). . Boilere (Power) Boilers (Steel) Suggested Rules for Care of Power Boilen. (1954). Steel Boiler Institute Rating Code for Steel Boilers (1954). Boilers (Steel) Simplified Practice Recommendation for Steel Firebox Boilers and Steel Heating Boilers (Commercial and Residential Types) (1950). Building Code Standards . Building Requirements Buildings Building Code Standards of the NBFU for the Installation of Heat Producing Appliances, Heating, ing. Ventilating, Air Conditioning, Blower and Exhaust Systems. American Standard Building Re quirements (1946). Baste Building Code (Also published in Abridged form as Abridged Building Code) 1950. Burners (Anthracite) Commercial Standard for Domestic Burners for Pennsylvania Anthra cite (Underfeed Type) (1940). Burners (Gas) Standard Requirements for Installation of Domestic Gas Con version Burners (1948). Burners (Gas) American Standard Requirements for Installation of Gas Burning Equip ment in Large Boilers (1950). Burners (Gas) Burners (Oil) American Standard Listing Require ments for Domestic Gas Conversion Burners (1948). Commercial Standard for MechanicalDraft Oil Burners Designed for Do mestic Installations (1942). Chimneys (Flue American Standard Sixes of Clay Flue Linings) Linings (1947). Cleaners (Air) Coal (For Stokers) Coils Code for Testing Air Cleaning Devices Used in General Ventilation: Section L Unit or Panel Type Air Filtering Devices (1953). Tentative Standard Procedure for Testing and Evaluating Bitumin ous Stoker Coals (1952). Proposed Commercial Standard for Rating and Testing Air Cooling Coils Using Non-Volatile Refriger ants (1945). ____ __________ Sponsor ASHVE ASMS ASME . A.G.A. ' ASME ASME ASME SBI BS SBI . NBFU NBA USPHS BOCA BS AIL A.G.A. A.O.A A.G.A. BS OBI AlA PC AFl SMA BCR BCMI BS 1956 Guide Reverence ASHAJb - ASMS ASME ASA Z21.13.1-1951 ASME . ASME ASME SBJ 6th Edition BS R157-50 ' NBFU -ft? ASA A53.1-1946 BOF BS CS48-40 ASA Z21.8-1948 ASA Z21.33-1950 ASA Ztl.l7-1948 BS CS75-42 ASA A62.4-1947 AFl rV SMA BCR BS TS 4044* J------------------------------------ Codes and Standards 1169 Table 1. Codes and Standards---(Continued) Subject Coils . Color Scheme (Piping) Color Scheme (Piping) Compressors Condensers Condensers Condensing Units Conductance Conductivity Title Standard Methods of Testing and Rating Forced-Circulation Air Cooling and Air-Heating Coils (1955). Scheme for Identification of Piping Systems (1945). Scheme for Identification of Piping Systems (1928). ASRE Standard Methods of Rating and Testing Refrigerant Com pressors. ASRE Standard Methods of Rating and Testing Evaporative Conden sers. ASRE Standard Methods of Rating and Testing Water-Cooled Refrig erant Condensers. ASRE Standard Methods of Rating and Testing Mechanical Condensing Units (1940). Method of Test for Thermal Conduct ance and Transmittance of Built-Up Sections by Means of Guarded Hot Box (1949). Standard Method of Test for Thermal Conductivity of Materials by Means of the Guarded Hot Plate (1945). Control Equip Underwriters' Laboratories, Inc., ' meat (Indus Standard for Industrial Control . trial) . Equipment (July 1938). Controls Underwriters' Laboratories, Inc., Standard for Temperature Indicat ing and Regulating Equipment (June 1953). Controls Temperature NEMA Standards for AutomaticTem perature Controls (1953). Controls Temperature Temperature Control Equipment, Automatic, Airplane Cabin Convector . ASHVE Standard Code for Testing and Rating Concealed Gravity Type Radiation(Hot Water Section) (1933). Convector ASHVE Standard Code for Testing ing and Rating Concealed Gravity Type Radiation (Steam Code) (1931). Convector Commercial Standard for Testing and Rating Convectors (1947). Coolers (Air) Coolers Cooling Towers Ducts and Fittings Exchangers (Heat) ASRE Standard Methods of Rating and Testing Forced Circulation and Natural Convection Air Coolers for Refrigeration (1945). ASRE Standard Methods of Rating and Testing Water and Brine Coolers. Accepted Test Procedure for Water - Cooling Towers, Mechanical Draft, Industrial Type (1955). Simplified Practice Recommendation for Pipes, Ducts and Fittings for Warm Air Heating and Air Condi tioning (1945). ' Standards of Tubular Exchanger Man ufacturers Association (1941). Sfonbob ARI HCCMA Reference - HCCMA Bulletin No. 202 - HP & ACCNA ASME ASRE A8HVE ACRMA ASRE ASHVE ACRMA ASRE ASHVE ACRMA ASRE ASHVE ACRMA ASTM HP & ACCNA Engrg. Stds., Sec. 2, Part V ASA A13-1928 ASRE Standard 23-R ASRE Standard 20 ASRE Standard 22 ASRE Standard 14-41 ASTM C 236-49 T ASHVE ASRE ASTM NRC UL UL ASTM C-177-45 UL Subject 508 UL Subject 873 NEMA SAE ASHVE ASHVE BS CMA IBR ASRE ASHVE ACRMA REMA ASRE ASHVE ACRMA CTI Mfrs. BS NEMA DCl-1953 SAE ARP 89A ASHVE Transactions, Vol. 39, 1933, p. 237 ASHVE Transactions, Vol. 37, 1931. p. 367 BS CS 140-47 ASRE Standard 25-44 ASRE Standard 24 " CTI Bulletin ATP-105 . BS R207-49 TEMA TEMA 1170 CHAPTER 53 1956 Guide Table 1. Codes and Standards--(Continued) Subject Title Exhaust Systems American Standard for Grinding, Pol ishing, and Buffing Equipment Sanitation (1941). Exhaust Systems Tentative Code of Recommended Practices for Testing and Measur ing Air Flow in Exhaust Systems (1937). Exhaust Systems Tentative Recommended Good Prac tice Code and Handbook on the Fundamentals of'Design, Construc tion, Operation and Maintenance of Exhaust Systems. Exhaust ' . - Systems Exhaust Systems (Open Tanka) Standards for Blower and Exhaust Systems (1949). American Standard Safety Code for Ventilation and Operation of OpenSurface Tanks (1951). Fans Definitions and Terms in Use by the Blower Industry (1950) (Was NAFM Bulletin No. 105). . Fans Standard Test Code for Testing Cen trifugal and Axial Fans (1950) (Was NAFM Bulletin No. 103). Fans Standard Code for Testing Centrifu gal, Axial, and Propeller Fans. (Hav ing Wheels Less Than 12-in. Diam). 1953. Fans Standards, Definitions, Terms and Test Codes for Centrifugal, Axial and Propeller Fans. Fans Standards for Fans (1947). Sponsob AFA AFA AFA , NFPA Aina A.S.H.V.E. NAFM NAFM NAFM ASHVE NAFM NAFM ASHVE** NEMA Fans . Test Code for Fans (1946). ASMS Fans Testing and Rating Ventilating Fans (Axial and Propeller Type). CSD Fire Prevention National Fixe Codes (1954). NFPA Furnaces (Duct) Vol. I--Flammable Liquids and Gases, Vol. II--Combustible Solids, Dusts, Chemicals, and Explosives, Vol. Ill--Building Construction and Equipment, Vol. IV--Extinguish ing Equipment, Vol. V--Electrical, Vol. VI--Transportation. American Standard Approval Re quirements for Gas-Fired Duct Fur naces (with 1954 Addenda). A.Q.A. Furnaces (Gas) American Standard Approval Re quirements for Central Beating Gas Appliances Vol. II, Gravity and Forced Air Central Furnaces (1951 - with 1952 and 1954 Addenda). - A.G.A. Furnaoes (Forced Air, Solid-Fuel) Commercial Standard for Solid-Fuel Burning Forced Air Furnaces (1944). N.W.A.EL& A.C.A. AIL Furnaces (Heavy Code for Testing and Rating Heavy Duty) Duty Furnaces and Direct-Fired Unit Heaters (1955). ASHAE . Furnaces (OilFired) Commercial Standard for Warm Air Furnaces Equipped with Vaporis ing Type Oil Burners (1949). Mfn. BS Furnaces (OilFired) Recommended Commercial Standard for Warm Air Furnaces Equipped with Pressure Atomising or Rotary Type Oil Burners. Also endorsed by PFMA. Refers to Test Code for Centrifugal and Axial Fans. BS NWAB A ACA Reference ASA Z43-1941 AFA Preprint 36-27 AFA NFPAotNBPU ; No. 91 ASA Z9.1-1951 . : NAFM .Bulletin No. 110 NAFM Bulletin No. 110 NAFM Bulletin No. 116 NAFM Bulletin 110 2nd Edition, 1952 NEMA' Publ. 47-128 ASMS PTC 11-1946 CSD NFPA ASA Z21.34-1942 ASA Z21.13.2 1951 BS CS109-44 ASHAE BS CS104-49 BS TS-5107 Codes and Standards 1171 Table 1. Codes and Standards--(Continued) Subject Title Sponsob Furnaces (Oil) Furnaces (Oil) Commercial Standard for Oil Burn ing Floor Furnaces Equipped with Vaporising Type Burners (1951). BS OPA - A Tentative Code for Testing OilFired Furnaces. NWAH A ACA Garage Ventilation Recommended Good Practice Re quirements for the Construction and Protection of Garages (1932, Reprint 1952) NFPA NBFU Garages Code of Minimum Requirements for Heating and Ventilating Garages (1935). ASHVE Gas Equipment American Standard Requirements for i (Large Boilers) Installation of Gas Equipment in large Boilers. . 4-U-A. Gases (Toxic) and Dust American Standard Allowable Con-' centration of Harmful Gases: Carbon Monoxide Hydrogen Sulfide Carbon Di-sulfide Benzene ; ASA Manganese ' Chromic~Acid-and Chromates Mercury Xylene Lead and Certain Inorganic Lead Compounds Toluene Oxides of Nitrogen Methanol Styrene-Monomer Formaldehyde Methyl Chloride Trichloroethylene Heat Transfer (Walls) Thermal Conductance and Transmit tance of Built-up Sections by of Guarded Hot Box (1949). ASTM Heaters (Re cessed Gas Fired) American Standard Approval Re quirements for CentreTHeating Gas Appliances, Vol. IV Gravity and Fan Type Vented Recessed Heaters (1953 with 1954 Addenda). A.Q.A. Heaters (Room Gas Fired) American Standard Approval Re quirements for Gas-Fired Room Heaters (formerly Space Heaters) (1954). A.G.A. ' Homes (Pre fabricated) Commercial Standard for Prefabri cated Homes. PEMI BS Mineral Wool Commercial Standard for Mineral Wool Insulation for Heated Indus trial Equipment (1949). BS IMWl Mineral Wool Commercial Standard for Mineral Wool Insulation for Low Temper ature Installations (1948)* BS JMWI Mineral Wool Recommended Commercial Standard for Industrial Mineral Wool Prod ucts--All Types--Testing and Re porting (1946). 1MWI Bs Motors Nema Motor and Generator Stand ards (June 1945). NEMA Motors Test Code for Single-Phase Motors (1941). AIBB Panel System (Warm Air) Code and Manual for the Design and Installation of Warm AirCeiling Panel Systerna. NWAH A ACA Reference BS . C8113-51; ; NWAH A ACA NFPA or NBFU . Pamphlet No. 88. ASHAE ASA 221.33-1950 ASA Z37.1-1941 237.2-1941 Z37J-1941 Z37.4-1941 - Z37.6-1948 Z37.7-1943 Z37.8-1943 . . Z37.10-1948 Z37.11-1943 Z37.12-1943 Z37.13-1944 237.14-1944 Z37.15-1944 Z37.16-1944 Z37.18-1949 237.19-1949: ASTM C-238-49 T .. ` ASA Z21.13.4 . ASA )' Z22.11-1954 BS ; CS125-47 BS C8117-49 BS CS105-48 BS CS131-46 NEMA 45-102 AIBB ' Report 502 - NWAH A ACA No. 7-A 1172 CHAPTER S3 1956 Guide Table 1. Codes; and Standards--(Continued) Subject Title Sponsor Reverence Perimeter (Warm Air Small Pipe) Perimeter (Warm Air) Pipe & Tubing (Copper & . Brass) Piping -. Piping (Gas) Pumps Radiation (Base board) '; ` Radiation. ; (Finned-Type) Small Pipe Warm Air Perimeter Heat ing. Warm Air Perimeter Heating (1P53, 3rd Edition). Simplified Practice Recommendation for Copper Water Tubes and Brass Pipe. American Standard Code for Pressure. Piping (1955)' ' ; American Standard for Installation of Gas Piping, and Gas Appliances in'Buildings (1954). j Hydraulic Institute Test Code for Centrifugal Pumps. Hydraulic In stitute Test Code for Rotary Pumps (1943). I=B=R Testing and Rating Code for Baseboard Type of Radiation (1950). I=B=R Testing and Rating Code for Finned-Type Radiation (First' Edition 1951, with Addenda 1954). NWAU & ACA NWAH & ACA Mfr. BS ASMS . A.G.A. HI 1BR IBR ; NWAH A ACA Manual No. 10 (Tentative) ' NWAH A ACA Manual No. 4 BS R217-49 ASA B31.1-1955 ASA . ; Z21.30-1954 HI Section F IBR ; IBR Radiators Code for Testing Radiators (1927). Radiators Simplified Practice Recommendation for Cast Iron Radiators(-1943). Refrigeration . (Equipment) Underwriters' Laboratories, Inc., Standard for Air Conditioning and Commercial Refrigerating Equip ment (Feb. 1946). Refrigeration . American Standard Safety Code for '(Mechanical) Mechanical Refrigeration (1950). Refrigeration ,, Underwriters' Laboratories, Inc., - . (Unit Systems) Standard for Unit Refrigerating Systems (Feb. 1946). Refrigerators. (Gas-Fired) American Standard Approval Re ' quirements for Refrigerators Using Gas Fuel (1942, Reaffirmed 4950). ; ' Refrigerators (Household) American Standard Test Procedures for Household Electric Refriger ators (Mechanically Operated) (1944). Sound American Standard for Noise Meas (Measurement) urement. ' Sound American Standard for Sound Level (Measuremen t) Meters for Measurement of Noise and Other Sounds. Sound American Standard Method for the (Measurement) Pressure Calibration of Laboratory Standard Pressure Microphones . -Sound Sound Measurement Test Code for (Measurement) Centrifugal and Axial Fans (1950) (Was NAFM Bulletin No.-104). Sound Sound Measurement Test Code for (Measurement) Unit Heaters (1955). Space Heaters * Commercial Standard for Flue'Con- nected Oil-Burning Space Heaters Equipped with Vaporizing Pot- Type Burners (1943). ; Also designated ASRE Circular No. 15. ASHVE IBR : . BS . ' UL ASHAE BS R174-47 : UL Subject 207A ASRB ASA B9.1-1950 UL ' . : ; : UL . . ; Subject 207C A.G.A ' ASA | Z21.19-1941 ASRE ; USDA : ASA B38.2-1944 . AS of A AS of A ' ASA . . Z24.2-1941 ASA ' : Z24.3-1944 AS of A - ' ASA . Z24.4-1949 .. NAFM NAFM Bulletin No. HO 1950) IVHA ICRAM . IVHA Bulletin No. 13 BS CS101-43 " . Codes and Standards 1173 Table 1. Codes and Standards (Concluded) Subject Title . Sponsor Reference Stokers Code for Determination of Rated Ca parities- of -Anthracite Underfeed Stokers (1944). Stokers Code for Determination of Rated Ca pacities of Bituminous Underfeed . Stokers (1944).. '' Stokers Recommended Minimum. Firebox Dimensions and Base .'Heights (1944). Stokers* ' Recommended Standards Governing Minimum Setting Heights (1944). Tubing (Seam less ~ - Copper and Copper Al loy) , Simplified Practice Recommendation for Copper and. Copper-Alloy Round Seamless Tube (1948).4 Tubing - (Seam Standard Specifications for Seamless less Copper Copper Water Tube (1951). Water Tube) . Unfired Pressure. Unfired Pressure Vessel Code (1950). Vessels . SMA SMA SMA ' SMA . -A8TM ASMB - * . SMA SMA SMA SMA BS R235-48 ,, ASA *. H23.1-1951 ASMS \ - Unit Heater* Unit Heaters American ..Standard Approval Re- ..-quirements"f6r'*Gas' Unit Heaters (1951-with 1953 Addenda). . Standard Code for Testing and Rating' Steam Unit Heaters (1950). . A.G.A. ASHVE IVHA - : Unit Heaters Standard Code for Testing Hot Water Unit Heaters (1942). ivha Unit Ventilators - A.S.H.VJB.-Standard Code for.Testing and Rating Steam Unit Ventilators (1934). ... ` .ASHVE Vacuum Pumps , A.S.H.V.E. Standard Code for Test ing and Rating Return Line Low Vacuum Heating Pumps (1934); : : ASHVE Warm Air (Gravity) Gravity Code and Manual for the Derign and Installation of 'Gravity-: Warm Air Heating Systems (1947). NWAH <fc ACA Water Heaters Water Heaters American Standard Household Auto matic Electric Storage-type -Water Heaters. American Standard Approval Re quirements for Gas Water Heaters' (with 1954 Addenda). ' NEMA ": A.G.A. Water Heaters NEMA Standards for Electric Water ' Heaters (1945).. . . . NEMA Water Heaters : Testing and Rating Hand-Fired Hot Water Supply Boilers (1948). FHA Wiring Interior Wiring Design for Commer . cial Buildings. - AIEB Wiring . National Electrical Code, (1953). NFPA ASA Z21.J6-1951 IVHA W Bulletin 10 - IVHA ' Bulletin 11 ASHAE ASHAE.;;/,, . NWAH & ACA . Manual No. 5 ' * 5th Edition ' ASA '"*- C72.1-1949 . . ASA * * Z21.10-19S3 NEMA w 45-104 . . , BS CS145-47 . aiee NFPA or NFBU . Pamphlet No. 70. ABBREVIATIONS AND ADDRESSES The Codes and Standards listed in preceding pages of this table can be obtained from the organizations listed in the Reference Column. ACMA ' ACRMA AFA AF1 A.G.A. Air. Conditioning Manufacturers Association,* superseded 1940 by ACRMA. Air Conditioning and Refrigerating Machinery Association, Southern Bldg., Wash* ington, D. C.'- superseded 1953 by ARI. American Foundrymen's Association. 616 8. Michigan Ave.,-Chicago, Hi. v V - ' Air Filter Institute, 215 Central Ave., Louisville, Ky. American Gas Association, 420 Lexington Ave., New York 17, N. Y. 1174 CHAPTER 53 .1956 Guide 'TSS AGABM AlA A1EE AJHA . ABBREVIATIONS AND ADDRESSES (Concluded) Association of Gas Appliance and Equipment Manufacturers, superseded 1945 by GAMA. American Institute of Architects, 1741 New York Aye., Washington, D. C. American Institute of Electrical Engineers, 33 Wesi 39th St., New York 18, N. Y. American Industrial Hygiene Association, 4400 Fifth Ave., Pittsburgh 13, Pa. f3 M& r'S AIL ARI Anthracite Industries Laboratory, 237 Old River Rd., Wilkes Barre, Pa. Air-Conditioning and Refrigeration Institute, 1346 Connecticut Ave., N. W. ASA ` AS of A ASHAE Washington, D. C. .. .. . American Standards Association, 70 East 45th St., New York 17, N. Y. Acoustical Society of America, 205 West Monroe St., Chicago, 111. American Society of Heating.and Air-Conditioning Engineers, 62 Worth St., New ASHVE ASMB ' ABBB astm BCMI .: BCE* York 13, N. Y. .. . ,: . American Society of Heating and Ventilating Engineers, name changed to American Society of Heating and Air-Conditioning Engineers, Dec. 8, 1954; ' - : American Society of Mechanical Engineers, 29'West 39ih St., New York 18, N. Y. American 8ociety of Refrigerating Engineers, 234 Fifth Ave., New York, N. Y. American Society for Testing Materials, 1916 Race St., Philadelphia, Pa. Blast Coil Manufacturers Institute, superseded by Heating and Cooling Coil Manu facturers Association, HCCMA. "` Bituminous Coal Research, Inc, 2609 First National Bank Bldg., Pittsburgh 22, Pa. 74 4gj- lr. BOCA BS *. Building Officials Conference of America, 110 East 42nd St., New York 17j" N. Y. ' National Bureau of Standards, Washington, D. C. . "> CSD CAfA CTI FHA GAMA HCCMA BI ' Commodity Standards Division, U. S. Dept, of Commerce, Washington, D. C. Convector Manufacturers Association, 2159 Guardian Bldg., Detroit, Mich. Cooling Tower Institute, 444 Emerson St., Palo Alto, Calif. . Federal Housing Administration, Washington, D. C. . -. Gas Appliance Manufacturers' Association, 60 East 42nd St., New York 17, N. Y. Heating and Cooling Coil Manufacturers Association, 2159'Guardian Bldg., Detroit, Mich. . Hydraulic Institute, 122 East 42nd St., New York 17, N. Y. .> iff* A ACCATA 1BR ICHAM - IMFI JMWI /t/HA NAFM NBFXJ ATBMA ; - - ' Heating, Piping and Air Conditioning Contractors National Association, Suite 1843. ' 30 Rockefeller Plata, New York 20, N. Y. . Institute of Boiler and Radiator Manufacturers, 608 5th Ave., New York, N. Y. & Institute of Cooking and Heating Appliance Manufacturers, Shoreham Hotel.' Washington, D. C. . . - Industrial Mineral Fiber Institute, 441 Lexington Ave-, New York 17, N. Y. \vV Industrial Mineral Wool Institute, superseded 1953 by IMFI. . Industrial Unit Heater Association, 2159 Guardian Bldg., Detroit, Mich. ' National Association of Fan Manufacturers, 2159 Guardiazi'Bidg., Detroit, Mfrh, National Board of Fire Underwriters, 85 John St., New York 8, N. Y. .. National Electrical Manufacturers Association, 155 East 44th St., New York 17, V NFPA . ATHA ' JVBC MAH * ACA OB/ * OH/A ' OPA PC PFMA PHMl REM A BA/A SAB SB/ ` SMA TEMA UL USDA USPHS National Fire Protection Association, 60 Batterymarch St., Boston 10, Mass. National Housing Agency, Washington, D. C. -- National Research Council, 2101 Constitution Ave., Washington, D. C. National Warm Air Heating and Air Conditioning Association, 640 Engineers Bldg., Cleveland, Ohio. .- On Burner Institute, superseded 1942 by OHIA * Oil Heat Institute of America, Room 1618 (Lower Level) 500 Fifth Ave.. New York 36, N. Y. : . Office of Price Administration, Washington, D. C. . Producers Council,1001-15th St., N.W., Washington, D. C. Propeller Fan Manufacturers Association, 2159 Guardian Bldg., Detroit, Mich.. Prefabricated Home Manufacturers Institute, 908 20th St., N.W., Washington 6, D. C* Refrigeration Equipment Manufacturers Association, superseded 1953 by ARI. Refrigerating Machinery Association. See ACRMA. Society of Automotive Engineers, 29 West 39th St., New York, N. Y. ' Steel Boiler Institute, 1308 Land Title Bldg., Philadelphia 10, Pa. ' Stoker Manufacturers Association, 307 N. Michigan Ave., Chicago 1, IU. Tubular Exchanger Manufacturers Association, 53 Park Place, New York, N. Y. Underwriters' Laboratories, 207 East Ohio St., Chicago, 111. * United States Department of Agriculture, Washington, D. C. . United States Public Health Service, Washington, D. C. ik Heating Ventilating Air Conditioning Guide 1175 SPECIFIC HEAT Table 1. Specific Heat of Solids* Alloys Materials - - Monel Metal.'..........'............................... Coal .................................................. Temperature F 32 32 57-208 68-2370 80-212 68-208 104-1637 Glass . Gold................ -........................................... 64-212 77-1832 50-122 50-122 64 32 -40 32 32-600 68-212 59-212 32 32 Rocks Tin................................................................ 58-212 63-210 54-212 59-212 32-212 32 240-320 77-1832 77 68 32 Specific Heat 0.0899 0.0883 0.0862 0.127 0.212 0.195 0.195 0.314 0.278 0.201 0.270 0:0928 0.258 0.161 - 0.117 0.0312 0.259 0.487 0.434 0.1043 0.127 0.1189 0.1152 0.0297 0.1032 0.2159 0.2 0.0319 . .0.199 . 0.192 0.216 0.21 0.22 0.0536 0.1175 0.220 0.263 0.0548 0.327 . 0.0913 Authority s s s s s s -H I H H H s I 's .S S H S S. 8 M H H .S S H H S S s 8V S S 8 H S I S s .s Table 2. Specific Heat of Liquids Liquid FTemperature Specific Heat Sea Water . Sp Gr 1.0043.............. ............................. Water............................................................ 32 59-68 59-122 360 68 70-136 64 64 59 0.548 0.601 0.576 0.041 0.03325 0.511 . 0.980 0.903 1.000 Authority S S S H S 8 S. S s Table 3. Specific Heat of Gases and Vapors Substance Temperature F Specific Heat at Constant Pressure Ratio of Specific Heat Cp/Cv Specific Heat at Constant Volume (Computed) Authority Air..................................... Ammonia..................... Carbon Dioxide........... Carbon Monoxide........ Hydrogen........................ Nitrogen.......................... Oxygen............................ Water VaDor.................. Water Vapor.................. 32-392 80-392 52-417 79-388 68-1900 70-212 32-392 55-404 212 356 0.2375 0.5356 0.2169 0.2426 0.3145 3.41 0.2438 0.2175 0.421 0.51 " 1.405 1.277 1.3003 1.395 1.419 1.41 1.3977 1.305 0.169 0.419 0.1668 0.1736 2.402 0.1729 0.155 0.322 S S s S s H s s s s .s * See also The Specific Heat of Thermal Insulating Materials, by Cordon B. Wilkes and Carl O. Wood (A.S.H.V.E. Transactions, Vol. 48, 1942, p. 493). # # Notes: When one temperature is given the true specific heat is given, otherwise the value is the mean specific heat between the given limits. Authorities: S--Smithsonian Physical Tables, 1933; I--International Critical Tables: H--Heating, Ventilation and Air Conditioning, by L. A. Harding and A. C. Willard; M--Engineers' Handbook, by Lionel S. Marks- . DiamETER IN Inches Table 4. Circumferences and Areas of Circles --------------- :--------------------^^--------------------------------------------- -- Area Circumference Area Circumference Sq In. Sq Ft Inches Feet Inches Sq In. Sq Ft Inches Feet H 0.049 H 0.196 H 0.442 1 0.785 m 1.227 w 1.767 m 2.405 2 3.142 2M 3.976 2H 4.909 2H 5.939 3 7.069 3*4 8.296 3H 9.621 3H 11.04 4 12.57 4H 14.19 4H 15.90 4H 17.72 5 19.64 5*4 21.65 5H 23.76 5H 25.97 6 28.27 6H 30.68 6H 33.18 6H 35.79 7 38.49 7H 41.28 7*4 44.18 7H 47.17 8 50.27 8*4 53.46 m 56.75 8H 60.13 9 63.62 9X 67.20 9)4 70.88 9*4 74.66 10 78.54 10*4 86.59 11 . 95.03 11*4 103.9 12 113.1 12*4 122.7 13 132.7 . 13*4 143.1 14 153.9 14*4 165.1 15 176.7 15*4 188.7 16 201.1 im 213.8 17 226.9 17*4 240.5 18 254.5 18*4 268.8 19 283.5 19! 298.6 20 314.2 20*4 330.1 21 346.4 21*4 361.1 22 380.1 22*4 397.6 23 415.5 23)4 433.7 24 452.4 24)4 471.4 25 490.9 25)4 510.7 26 530.9 26)4 551.6 27 572.6 27*4 593.9 0.0003 0.0014 0.0031 0.0054 0.0085 0.0123 0.0167 0.0218 0.0276 0.0341 0.0412 0.0491 0.0576 0.0668 0.0767 0.0873 0.0986 0.1104 0.1231 0.1364 0.1504 0.1650 0.1840 0.1964 0.2131 0.2304 0.2486 0.2673 0.2867 0.3068 0.3276 0.3491 0.3713 0.3942 0.4175 0.4418 0.4668 0.4923 0.5185 0.5454 0.6010 0.6600 0.7215 0.7854 0.8520 0.9218 0.9937 1.069 1.146 1.227 1.310 1.396 1.485 1.576 1.670 1.767 1.867 1.969 2.074 2.182. 2.293 2.405 2.508 2.640 2.761 2.885 3.012 3.142 3.274 3.409 3.547 3.687 3.832 3.976 4.125 0.785 1.571 2.356 3.142 3.927 4.712 5.498 6.283 7.069 7.854 8.639 9.425 10.21 . 10.99 11.78 12.57 13.35 14.14 14.92 15.71 16.49 17.28 18.06 18.85 19.64 20.42 21.21 21.99 22.78 23.56 24.35 25.13 25.92 26.70 27.49 28.27 29.06 29.85 30.63 31.42 32.99 34.56 36.13 37.70 39.27 40.84 42.41 43.98 45.55 47.12 48.69 50.27 51.84 53.41 54.98 56.55 58.12 59.69 61.26 62.83 64.40 65.97 67.54 69.12 70.69 72.26 73.83 75.40 76.97 78.54 80.11 81.68 83.25 84.82 86.39 0.0652 28 0.1309 28*4 0.1964 29 0.2618 29*4 0.3273 30 0.3927 31 0.4582 32 0.5236 33 0.5891 34 0.6546 35 0.7200 36 0.7854 37 0.8510 . 38 0.9160 39 0.9818 40 1.047 - .41 1.113 42 1.178 43 1.243 44 1.309 45 1.374 ' 46 1.440 47 1.505 48 1.571 49 1.637 50. 1.702 51 1.768 52 1.833 53 1.899 54 1.964 55 2.029 56 2.094 57 2.160 58 2.225 59 2.291 60 2.356 61 2.422 62 2.488 63 2.553 64 2.618 65 2.750 66 2.880 67 3.011 68 3.142 69 3.273 70 3.403 71 3.535 72 3.665 73 3.796 74 3.927 75 4.058 76 4.189 77 4.321 78 4.451 79 4.582 80 4.712 81 4.845 82 4.974 -83 5.105 84 5.236 85 .5.367 86 5.498 87 5.629 88 5.760 89 5.891 90 6.021 91 6.153 92 6.283 93 6.415 94 6.545 95 6.676 96 6.807 97 6.938 98 7.069 99 7.199 100 615.8 4.276 637.9 4.430 660.52 4.587 683.5 4.747 706.8 4.909 754.8 5.241 804.3 5.585 855.3 5.940 907.9 6.305 962.1 . 6.681 1018.0 ' 7.069 1075.0 7.467 1134.0 . 7.876 1195.0 8.296 1256.0 8.727 1320.0 9.168 1385.0 9.621 1452.0 10.08 1521.0 10.56 1590.0 11.04 1662.0 11.54 1735.0 ' 12.05 1810.0 12.51 1886.0 13.09 1963.0 13.64 2043.0 14.19 2124.0 14.75 2206.0 15.32 2290.0 15.90 2376.0 16.50 2463.0 17.10 2552.0 17.72 2642.0 18.35 2734.0 18.99 2827.0 19.63 2922.0 20.29 3019.0 20.97 3117.0 21.65 3217.0 22.34 3318.0 23.04 3421.0 23.76 3526.0 24.48 3632.0 25.22 3739.0 25.97 3848.0 26.73 3959.0 27.49 4072.0 28.27 4185.0 29.07 4301.0 29.87 4418.0 30.68 4536.0 31.50' 4657.0 32.34 4778.0 33.18 4902.0 34.04 5027.0 34.91 5153.0 35.78 5281.0 36.67 5411.0 37.57 5542.0 38.48 5675.0 39.41 5809.0 40.34 5945.0 41.28 6082.0 42.24 6221.0 43.20 6362.0 44.18 6504.0 45.17 6648.0 46.16 6793.0 47.17 6940.0 48.19 7088.0 49.22 7238.0 50.27 7390.0 51.32 7543.0 52.38 7698.0 53.46 7854.0 54.54 ` 87.97 7.330 89.54 7.462 91.11 7.592 92.63 7.725 94.25 7.854 ` 97.39 8.116 100.5 8.378 103.7 8.639 106.8 8.901 109.9 9.163 113.1 9.425 116.2 9.686 119.4 9:948 122.5 10.21. 125.6 10.47 128.8 10.73 131.9 . .10.99 135.1 . 11.26 138.2 11.52 141.4 11.78 144.5 12.04 147.7 12.30 150.8 - . 12.57 153.9 : 12.83 157.1 13.09 160.2 13.35 163.4 13.61 166.5 13.88 169.6 14.14 172.8 - 14.40 175.9 - 14.66 179.1 14.92 182.2 15.18 185.4 15.45 188.5 15.71 191.6 15.97 : 194.8 16.23 197.9 16.49 201.1 16.76 204.2 17.02 207.3 17.28 210.5 17.54 213.6 17.80 216.8 18.06 219.9 18.33 . 223.1 18.59 226.2 18.85 229.3 19.11 232.5 19.37 235.6 19.63 238.8 19.90 241.9 20.16 - 245.0 . 20.42 248.2 20.68 251.3 : 20.94 254.5 21.21 257.6 21.47 260.8 21.73 263.9 21.99 267.0 22.25 270.2 22.61 273.3 22.78 276.5 23.04 279.6 23.30 282.7 23.56 285.9 23.82 289.0 24.09 292.2 24.35 295.3 24.61- 298.4 24.87 301.6 25.13 304.7 25.39 307.9 25.66 311.0 25.92 314.2 26.18 | $ S3 M m it M |8 IP w ' -J5 $ T-SJ & H k :Fm M 2H1 M -ffi#g? M S m -1 : iik M 1 ;f! Y-y i CATALOG DATA SECTION INDEX TO ADVERTISERS PAGE 1179 INDEX TO MODERN EQUIPMENT PAGE 1187 1 CATALOG DATA SECTION INDEX TO ADVERTISERS HEATING VENTILATING AIR CONDITIONING GUIDE, 1956 A-J MFG. CO., 3601 E. 18 St., Kansas City 27, Mo.............................................. 1426-1427 ACME INDUSTRIES, INC., Jackson, Mich..................... ........................................ 1358 ADDISON PRODUCTS CO., Addison, Mich............................................................ 1243 AERCO CORP., Paris Ave., P.O. Box 248, Northvale, N. J........................... 1595 AEROFIN CORP., 101 Greenway Ave., Syracuse 1, N. Y..................... 1359-1360-1361 AEROQUIP CORP., Jackson, Mich........................................................ 1.............. 1312 AEROVENT FAN CO., INC., Ash & Blade Sts., Piqua, Ohio..........!.................. 1374 AIR & REFRIGERATION CORP., 439 Madison Ave., New York 22, N. Y. ... 1219 AIR CONDITIONING, HEATING and VENTILATING (publication), 93 Worth St., New York 13, N. Y........ ....................................................................... 1689 AIR CONTROL PRODUCTS, INC., Coopersville, Mich...............1428-1429-1430-1431 AIR DEVICES, INC., 185 Madison Ave., New York 16, N. Y.......................1316, 1432 AIR-FACTORS, INC., 1624 S. Raymond Ave., Monrovia, Calif...:................... 1433 AIR FAN ENGINEERING CO., 7401 Telegraph Rd,, Los Angeles 22, Calif....... 1343 AIR FILTER CORP., 108G N. Water St., Milwaukee 2, Wis................................... 1317 AIR-MAZE CORP., 25000 Miles Rd., Cleveland 28, Ohio........................... ... 1318 AIRTEMP DIV. OF CHRYSLER CORP., Dayton 1, Ohio.................................1248-1249 AIRTHERM MFG. CO., 728 S. Spring Ave., St. Louis 10, Mo............................... 1522 ALADDIN. HEATING CORP., 1111 West Ave. 137, San Leandro, Calif............ 1375 ALCO VALVE CO., 851 Kingsland Ave., St. Louis 5, Mo...................................... 1472 ALDRICH CO., 121 E. Williams St., Wyoming, 111................................................ 1541 ALLEN COOLER AND VENTILATOR, INC., 704 Woodward, Rochester, Mich. 1414 AMERICAN AIR FILTER CO., INC., 673 Central Ave., Louisville 8, Ky........... 1319-1320-1321 AMERICAN ARTISAN (publication), 6 N. Michigan Ave., Chicago 2, 111........ 1694 AMERICAN BLOWER CORP., P. O. Box 58, Roosevelt Park Annex, Detroit 32, Mich................................................................................................................... 1220-1221 AMERICAN BRASS CO., THE, Waterbury 20, Conn....................................... 1310-1311 AMERICAN DISTRICT STEAM DIV., ADSCO INDUSTRIES, INC., North Tonawanda, N. Y......................... ;.......................................... ..........................1505, 1594 AMERICAN FLANGE & MFG. CO., INC., 30 Rockefeller Plaza, New York 20, N. Y......................... 1678 AMERICAN FOUNDRY & FURNACE CO., P. O. Box 904, Bloomington, 111. 1266-1267 AMERICAN G1LSONITE CO., Salt Lake City, Utah ........................................... 1646 AMERICAN MOISTENING CO., Providence 1, R. 1............................................. 1222 AMERICAN RADIATOR & STANDARD SANITARY CORP., (Plumbing & Heating Div.), New York 18, N. Y..........................................................1523-1524-1525 AMERICAN SOCIETY OF REFRIGERATING ENGINEERS, 40 West 40th St., New York 18, N. Y........................................ .................................................... 1690 AMERICAN-STANDARD,Air Conditioning Div., Elyria, Ohio........................1244-1245 AMERICAN 3 WAY-LUXFER PRISM CO., 431 S. Dearborn St., Chicago 5, 111.................................................................. ................................................................ 1660 C. L. AMMERMAN CO., 110 N. Second St., Minneapolis 1, Minn.................... 1415 V. D. ANDERSON CO., THE, DIV. OF INTERNATIONAL BASIC ECONOMY CORP., 1935 West 96th St., Cleveland, Ohio.............................................. 1612-1613 ANEMOSTAT CORP. OF AMERICA, 10 East 39th St., New York 16, N. Y... 1434-1435 APRIL SHOWERS CO., INC., 4126 Eighth St., N.W., Washington 11, D. C. .. 1644 1179 1180 1956 Guide ARMSTRONG CORK CO., Lancaster, Pa................................................................. 1665 ARMSTRONG FURNACE CO., Columbus, Ohio............. ,............................. 1246-1247 ARMSTRONG MACHINE WORKS, 851 Maple St., Three Rivers, Mich.. .1614-1615 AUER REGISTER CO., THE, 6600 Clement Ave., Cleveland 5, Ohio................. 1436 AURORA PUMP DIV. THE NEW YORK AIR BRAKE CO., 40 Loucks St., Aurora (Chicago Suburb), 111.................................................................. .............. 1603 B BABCOCK & WILCOX CO., THE, 16l!East 42nd St., New York 17, N. Y.... 1542 BADGER MFG. CO., 230 Bent St., Cambridge 41, Mass...................................... 1506 BAHNSON CO., THE, Winston-Salem, N. C........................................................... 1223 BALTIMORE AIRCOIL CO., INC., 2615 Mathews St., Baltimore 18, Md....... 1346 BARBER-COLMAN CO., 150 Loomis, Rockford, 111............................ ............ 1437, 1473 BARNEBEY-CHENEY CO., Cassady & 8th Aves., Columbus 19, Ohio.... 1322-1323 BARNES & JONES, INC., 34 Crafts St., Newtonville, Mass....'..................... .. 1616 BAYLEY BLOWER CO., 1821 S. Sixty-Sixth St,, Milwaukee 14, Wis............... 1376 BELL & GOSSETT CO., Morton Grove, HI..................... ....................1598-1599 BINKS MFG. CO., 3130-36 Carroll Ave., Chicago 12, 111.................................1344-1345 BISHOP & BABCOCK MFG. CO., THE, MASSACHUSETTS BLOWER DIV., 4901 Hamilton Ave., Cleveland 14, Ohio................................................... ......... 1377 G. C. BREIDERT CO., THE, P.O. Box 1190, San Fernando, Calif.................... 1416 BRONSON FAN MFG. CORP., 4560 Worth St., Los Angeles 63, Calif............... 1378 BROOKSIDE PRODUCTS CO., INC., McCordsville, Ind.................................... 1379 BRUNDAGE CO., THE, 530 N. Park St., Kalamazoo, Mich..........................1380-1381 BRUNNER MFG. CO., Dept. M-56, Utica, N. Y..................................................... 1368 BRYAN STEAM CORP., Chili Pike, Peru, Ind........................................................ 1543 BUENSOD-STACEY, INC., 60 East 4Znd St., New York 17, N. Y................. ... 1224 BUFFALO FORGE CO., 450 Broadway, Buffalo, N. Y........................................... 1382 BUFFALO PUMPS, DIV. OF BUFFALO FORGE CO., 450 Broadway, Buffalo, . N. Y. .................................................................................-...................................... 1604 ALAN E. BURDEN CO., INC., 1940-50 Pontius Ave., Los Angeles 25, Calif........ 1383 BURGESS-MANNING CO., 5970 Northwest Highway, Chicago 31, 111............. 1438 BURNHAM CORP., Irvington-on-Hudson, N. Y............................................. .1526-1527 C CAMBRIDGE FILTER CORP., 736 East Erie Blvd., Syracuse 3, N. Y.... ... 1324 E. K. CAMPBELL CO., 1809 Manchester, Kansas City 26, Mo........................ 1270 CAMPBELL HEATING CO., 3121 Dean, Des Moines 17, Iowa..'................. 1268-1269 CAM-STAT, INC., DIV. of the PAUL HENRY CO., 11831 W. Olympic Blvd., Los Angeles 64, Calif..................................................................... .................. 1474 CAREY ELECTRONIC ENGINEERING CO., Metal Wool Dlv., 1875 Clifton Ave., Springfield, Ohio............................................................................................ 1325 PHILIP CAREY MFG. CO., THE, Lockland, Cincinnati 15, Ohio............... 1656-1657 CARRIER CORP., Syracuse 1, N. Y..................................................................... 1226-1227 A. W. CASH CO., P. O. Box 551, Decatur, HI... '................................................... 1617 CELOTEX CORP., THE, 120 S. LaSalle St., Chicago 3, 111................................. 1666 CENTURY FAN & VENTILATOR CO., INC., 45 Cedar St., Stamford, Conn. 1384 CHAMPION BLOWER & FORGE CO., Div. 9, Lancaster, Pa...... ..................... 1385 CHICAGO BLOWER CORP., 9865 Pacific Ave., Franklin Park, 111................... 1386 CHICAGOiPUMP CO., 622 W. Dlversey Parkway, Chicago 14, 111.............. 1606-1607 CHICAGO STEEL FURNACE CO., 9326 S. Anthony Ave., Chicago 17, 111........... 1271 CHRYSLER AIRTEMP, DIV. of CHRYSLER CORP., Dayton 1, Ohio..........1248-1249 CLARAGE FAN CO., Kalamazoo, Mich..............................................................1225, 1387 CLEAVER-BROOKS CO., 498 E. Keefe Ave., Milwaukee'12, Wis.............. 1544, 1580 COAL-HEAT (publication), 20 W. Jackson Blvd., Chicago 4, 111........................ 1691 COLUMBIA BOILER CO., Pottstown, Pa............................................................1546-1547 COMBUSTION CONTROL DIV., ELECTRONICS CORP. of AMERICA, 718 Beacon St., Boston 15, Mass..-.............................................................................. 1475 COMBUSTION ENGINEERING, INC., 200 Madison Ave., New York 16, N. Y: 1548-1549 COMBUSTION ENGINEERING, INC., Hom.e Equipment Div., 911 W. Main St., Chattanooga, Tenn............................................................................................ 1250 CONNOR ENGINEERING CORP., Shelter Rock Lane, Danbury, Conn............ 1326-1327, 1441-1442 CONTINENTAL AIR FILTERS, INC., P. O. Box 1647, Louisville 1, Ky........... 1328 COPELAND REFRIGERATION CORP., Sidney, Ohio........................................ 1369 0` /s | I & * t; Index to Advertisers 1181 CRANE CO., 836 S. Michigan Ave., Chicago 5, 111............................................ 1528-1529 CURTIS MANUFACTURING CO., Refrigeration Div., 1959 Klenlen Ave., St. Louis 20, Mo................................................................................................................. 1370 CYCLOTHERM DIVISION, NATIONAL-U. S. RADIATOR CORP., Oswego, N.Y,...............................................................................:.......................... ................. 1545 DE BOTHEZAT FANS DIV., AMERICAN MACHINE & METALS, INC., East . Moline, 111.............................................................................................................. 1388-1389 CHARLES DEMUTH & SONS, INC., 245 Elm Place, Mineola, N. Y.................. 1439 DESOMATIC PRODUCTS, INC., 1109 W. Broad St., Falls Church, Va........... 1228 DETROIT STOKER CO., 5-125 General Motors Bldg., Detroit 2, Mich........... 1568 DEVICES, INC., DIVISION MIRACLE ADHESIVES CORP., 214 East 53 St., New York 22, N. Y..................................................................................................... 1654 DEWEY-SHEPARD BOILER CO., THE, Sales Office, 1311 N. Capitol Ave., Indianapolis, Ind..................................................... 1550 DOLE VALVE CO., THE, 1933 Carroll Ave., Chicago 12, 111.................................. 1640 DOLLINGER CORP., 6 Centre Pk., Rochester 3, N. Y............................... 1330-1331 DOMESTIC ENGINEERING PUBLICATIONS, 1801 Prairie Ave., Chicago 16, 111.................................................................................................................................... 1692 DOMESTIC PUMP & MFG. CORP., Shippensburg, Pa........ .............................. 1605 DOW CHEMICAL CO.,.THE, Plastics Sales, Midland, Mich.................:......... 1667 DRAVO CORP., Machinery Div., Dravo Bldg., Fifth & Liberty Aves., Pitts- . burgh 22, Pa............................................................................................................1272-1273 DRAYER-HANSON, DIV. of NATIONAL-U. S. RADIATOR CORP., 3301 Medford St., Los Angeles 63, Calif........................................................ 1229 C. A. DUNHAM CO., 400 West Madison St., Chicago 6, 111........... 1618-1619-1620-1621 DURANT INSULATED PIPE CO., Deme ter St. off Bay Road, Palo Alto, Calif.. 1647 DURO-DYNE CORP., 800 Third Ave., New Hyde Park, L. I., N. Y............... 1466-1467 DUTTON BOILERS, DIVISION HAPMAN-DUTTON CO., 639 Gibson St., Kalamazoo, Mich...................................... '............................................................... 1551 E EDDINGTON METAL SPECIALTY CO,, Eddington, Pa..................................... ELECTRIC AUTO-LITE CO., THE, Instrument & Gauge Div., Dept. HV, Toledo 1, Ohio......................................................................................................... ELECTRO-AIR CLEANER CO., 1285 Reedsdale St., Pittsburgh 33, Pa.. . . ELECTROMODE CORP., 45 Crouch St., Rochester 3, N. Y........ ....................... ELGEN MFG. CORP., 41-34 39th St., Long Island City 4, N. Y........................ ENTERPRISE ENGINE & MACHINERY CO., A SUBSIDIARY of GENERAL METALS CORP., 18th and Florida Sts., San Francisco 10, Calif............. 1591 1476 1329 1305 1468 1581 FAIRBANKS CO., THE, 393 Lafayette St., New York 3, N. Y.......................... 1641 FARR COMPANY, P. O. Box 45187, Airport Sta., Los Angeles 45, Calif. . .1332-1333 FARRAR & TREFTS DIV., ADSCO INDUSTRIES, INC., 20 Milburn St., Buffalo 12, N. Y....................................................................................................... 1554 FEDDERS-QUIGAN CORP., Hancock & Lalor Sts., Trenton 7, N. J................... 1286 FIELD CONTROL DIVISION of H. D. CONKEY & CO., Press Bldg., Men- dota. 111.......................................... 1477 T. R. FINN & CO., INC., Industrial Div., 200 Central Ave., Hawthorne, N. J. 1686 FITZGIBBONS BOILER CO., INC., 101 Park Ave., New York 17, N. Y....... 1552-1553 FLEXONICS CORPORATION, Expansion Joint Division, Maywood, 111........... 1507 FLUOR PRODUCTS CO., A DIV. of THE FLUOR CORP., LTD., 1200 E. Washington Blvd., Whittier, Calif....................................................................... 1347 FRICK CO., Waynesboro, Pa....................................................................... 1371 FULTON-SYLPHON DIVISION, ROBERTSHAW-FULTON CONTROLS CO., Knoxville 1, Tenn........................................................................................ 1478-1479 G & O MANUFACTURING CO., THE, 138 Winchester Ave., New Haven 8, Conn............................................................................................................................... GALLAHER CO., THE, 4108 Dodge St,, Omaha 3, Nebr.................................... GARDEN CITY FAN CO., 332 S. Michigan Ave., Chicago 4, 111. 1362 1417 1390 1182 1956 Guide GENERAL AUTOMATIC PRODUCTS CORP., 2300 Sinclair Lane, Baltimore 13, Md............................................................................................................. .......... 1313 GENERAL BLOWER CO., 8602 Ferris Ave., Morton Grove, 111.......................... 1391 GENERAL CONTROLS, 801 Allen Ave., Glendale 1, Calif............................ 1480-1481 GENERAL ELECTRIC, Home Heating and Cooling Dept., 5 Lawrence St., Bloomfield, N. J....................................................................................................... .. 1230 GENERAL ELECTRIC, Commercial and Industrial Air Conditioning Dept., 5 Lawrence St., Bloomfield, N. I.. ..................;................................................ 1231 GENERAL FITTINGS CO., Box 151K, East Greenwich, R. 1................................... 1596 GENERAL REGISTER CORP., 14 Factory St., Cedar Grove, N. J............. 1442-1443 GENIE-AIR, INC., 4273 S. Broadway, Los Angeles 37, Calif......................... 1418-1419 E. D. GOODFELLOW CO.,'INC., 496 E. Bodley Ave., Memphis, Tenn............... 1348 B. F. GOODRICH, Sponge Products Div., 274 Derby Place, Shelton, Conn...... 1683 GOODYEAR TIRE & RUBBER CO., INC., THE, Akron 16, Ohio................ 1334 GORDON-PIATT, INC., P. O. Box 914, Winfield, Kans....................................... 1576 GOVERNAIR CORP., 513 N. Blackwelder, Oklahoma City 4, Okla.. ............. 1232 H HALSTEAD & MITCHELL, Bessemer Bldg., Pittsburgh 22, Pa..................1350-1351 HAMMOND BRASS WORKS, Summer Blvd., Hammond, Ind.................... 1642 ARTHUR HARRIS & CO., 210-218 N. Aberdeen St., Chicago 7, 111.............. 1512 HART & COOLEY MFG. CO., Holland, Mich.................:................................ 1444-1445 HARTZELL PROPELLER FAN CO., DIV. of CASTLE HILLS CORP., Piqua, OWo................................................................................................................... 1392 HASTINGS AIR CONDITIONING CO., INC., Hastings, Nebr..................... 1233 HAVENS STRUCTURAL STEEL CO., 1713 Crystal Ave., Kansas City, Mo... 1349 HAYES FURNACE MFG. & SUPPLY CO., 2929 S. Fairfax Ave., Los Angeles 16, Calif............................... 1252-1253 HEATING & AIR CONDITIONING CONTRACTOR, (publication, formerly SHEET METAL WORKER) 92 Martling Ave., Tarrytown, N. Y............... 1693 HEATING & PLUMBING EQUIPMENT NEWS (publication), 93 Worth St., New York 13, N. Y............................................................ 1689 HEATING, PIPING and AIR CONDITIONING (publication), 6 N. Michigan Ave., Chicago 2, 111...................................................................................... '............ 1594 HELLER LABORATORIES, INC., 124 Fort Lee Road, Leonia, N. J.............. 1352 HENDRICK MFG. CO., 48 Dundaff St., Carbondale, Pa............................... 1446-1447 HENRY VALVE CO., Melrose Park, 111........................... ......................................... 1482 HIRSCHMAN-POHLE CO., INC., 200 Lent Ave., Le Roy, N. Y. ..................... 1420 HOFFMAN SPECIALTY MFG. CORP., 1001 York St., Indianapolis 7, Ind....... 1622-1623-1624-1625 HUBBELL CORP., P. O. Box 700, Hawley Road, Mundelein, 111....................... 1483 HYDRALINE PRODUCTS, DIV. BORG-WARNER CORP., 18538 Mack Ave., Detroit 36, Mich......................................................................................................... 1251 HYDROTHERM, INC., Northvale, N. J............................................................... . 1555 I" ILG ELECTRIC VENTILATING CO., 2880 N. Crawford Ave., Chicago 41, 111... . 1287, 1393 ILLINOIS ENGINEERING CO., DIV. of AMERICAN AIR FILTER CO., INC., 2059 S. Racine Ave., Chicago 8, 111...................................................... .......... 1626-1627 ILLINOIS TESTING LABORATORIES, INC., Room 516, 420 N. LaSalle St., Chicago 10, 111....................................................................................................... '.. i486 INDEPENDENT REGISTER CO., THE, 3747 East 93rd St., Cleveland 5, Ohio. 1448 INDUSTRIAL ENGINEERING & EQUIPMENT CO., 711 S. Teresa Ave., St. Louis 3, Mo................................................................. ;............................................. 1306 INFRA INSULATION, INC., 525 Broadway, New York, N. Y................... .. 1679 INSULITE DIVISION, MINNESOTA and ONTARIO PAPER CO., Investors Bldg., Minneapolis 2, Minn............................................................................. 1668-1669 INTERNATIONAL BOILER WORKS CO., THE, 500 Birch St., East Strouds burg, Pa......................... ........................................................................................ 1556 INTERNATIONAL EXPOSITION CO., 480 Lexington Ave., New York 17, N. Y. 1636 Index to Advertisers 1183 JACKSON & CHURCH, Furnace Div., Saginaw, Mich.................................... 1276 JENKINS BROS., 100 Park Ave., New York 17, N. Y......................................... . 1643 JOHNS-MANV1LLE, 22 East 40th St., New York 16, N. Y..-....................... .1670-1671 S. T. JOHNSON CO., 940 Arlington Ave., Oakland 8, Calif........................1582-1583 JOHNSON HEATER CORP., 1 Winnisimmet St., Chelsea, Mass............... 1274-1275 JOHNSON SERVICE CO., Milwaukee, Wis....................................................... 1484-1485 JOHNSTON BROS., INC., Ferrysburg, Mich...........................................: ............ I55? JOURNAL of PLUMBING, HEATING & AIR CONDITIONING, THE, (publi cation) 92 Martling Ave., Tarrytown, N. Y....................................................... 1692 JOY MFG. CO., General Offices, Henry W, Oliver Bldg., Pittsburgh 22, Pa. 1394-1395 K KAISER ALUMINUM & CHEMICAL SALES, INC., Palmolive Bldg., Chicago jj in..........................................................................................................................1684-1685 E. b'. KAISER COl,' P.'6'. Box 276, 2114 W. Lake Ave., Glenview, 111......... . 1648-1649 KENNARD CORP., 1819 S. Hanley Rd., St. Louis 17, Mo..................... .......... 1234 KEWANEE BOILER DIV. of AMERICAN-STANDARD, Kewanee, 111........... 1558-1559-1560-1561 KEWAUNEE MFG. CO., 5119 S. Center St., Adrian, Mich............... ............... 1411 KILLEBREW ENGINEERING CORP., 8640 Pardee Lane, St. Louis 23, Mo. . 1597 KIMBERLY-CLARK CORP., Neenah, Wis.................................................. .1672-1673 KNOWLES MUSHROOM VENTILATOR CO., Upper Montclair, N. J............ . 1449 KORFUND CO., INC., THE, 48-01R 32nd PL, Long Island City 1, N. Y....... .. 1687 KRAISSL CO., INC., 297 Williams Ave., Hackensack, N. J................................ 1610 KRITZER RADIANT COILS, INC., 2909A Lawrence Ave., Chicago 25, 111....... 1514 L L.O.F GLASS FIBERS CO., 1810 Madison Ave., Toledo 2, Ohio....................... 1655 LADISH CO., Cudahy, Wis................................................................................ ........... 1508 lAMNECK DIVISION, CLAYTON & LAMBERT MFG. CO., 1026 Lamneck St., Middletown, Ohio...................... ...................................................................... 1256 LAU BLOWER CO., THE, 2007 Home Ave., Dept. J, Dayton 7, Ohio.... 1396-1397 LEE CORP., Foot of Madison St., Wilmington, Del........................... ........ 1277 LESLIE CO., 266 Grant Ave., Lyndhurst, N. J........................................................ 1487 LILIE-HOFFMANN COOLING TOWERS, INC., 1450 S. Vandeventer Ave., St. Louis 10, Mo. ................................................................................................... I388 LIMA REGISTER CO., Lima, Ohio........................................................... ........1450-1451 LOCKPORT MILLS INC., Dept. C, Lockport, N. Y................................. . LOUVRA MANUFACTURING & SALES CO.. 1010 Jeanette Ave., Union, N. J.. 1452 M MAID-O'-MIST, INC., 3217 N. Pulaski Rd., Chicago 41, 111................... 1630-1631-1632 MAMMOTH FURNACE CO., THE, 509 Vandalia St., St. Paul 4, Minn........... 1278 CHARLES E. MANNING CO., 90 Clairton Blvd., Pittsburgh 36, Pa.................. 1335 MARLEY CO., THE, 222 W. Gregory, Kansas City 14, Mo.............................. 1354 MARLO COIL CO., 6135 Manchester Ave., St. Louis 10, Mo. ....................... 1355 JAS. P. MARSH CORP., Dept. 5, Skokie, 111................ ....................................1628-1629 MAXITROL CO., 12200 Beech Rd., Detroit 39, Mich............................................. 1488 McDONNELL & MILLER, INC., 3500 N. Spaulding Ave., Chicago 18, 111.. .. 1570-1571-1572-1573 McQUAY, INC., 1602 Broadway, N.E., Minneapolis 13, Minn...................... 1288-1289 MERCOID CORP., THE, 4201 Belmont Ave., Chicago 41, 111............................. 1489 METALBESTOS DIV., WILLIAM WALLACE CO., Belmont, Calif..............1592-1593 MILWAUKEE GAS SPECIALTY CO., 730 N. Jackson St, Milwaukee 2, Wis. 1492 MINNEAPOLIS-HONEYWELL REGULATOR CO., 2644 Fourth Ave., So., Minneapolis 8, Minn.............................................................. :......... ....... ......... 1490-1491 MIRACLE ADHESIVES CORP., 214 East 53 St., New York 22, N. Y.............. 1654 MODINE MFG. CO., 1515 Dekoven Ave., Racine, Wis................................... 1290-1291 MOELLER INSTRUMENT CO., 132nd St. and 89th Ave., Richmond Hill 18, H. Y. .................................................... ...................................... 1493 MONARCH MFG. WORKS, INC., 2509 E. Ontario St., Philadelphia 34, Pa... 1357 MORRISON PRODUCTS, INC., East 168th St. and Waterloo Rd., Cleveland 10, Ohio.................................................................................................... ........... 1398 1184 1956 Guide 5 MTJCKLE MFG. CO., 666 Belford Road, Owatonna, Minn.................................... 1421 MUELLER CLIMATROL, DIV. of WORTHINGTON CORP., MUwaukee 15, Wis............................................................................... ;.......................... ...............1254-1255 MUELLERMIST IRRIGATION CO., 2612-22 So. Ninth Ave., Maywood, 111. . 1645 D. J. MURRAY MFG. CO., Wausau, Wis.............................................................. 1292 'N NASH ENGINEERING CO., THE, 234 Wilson Rd., South Norwalk, Conn.. 1608-1609 NATIONAL CLAY PIPE MANUFACTURERS, INC., 1820 N St. N.W., Wash ington 6, D. C................................................ ........... .. 1516-1517-1518-1519-1520-1521 NATIONAL HEATER CO., 2180 Cleora Ave., St. Paul 4, Minn................... 1280-1281 NATIONAL-U. S. RADIATOR CORP., Johnstown, Pa.................1530-1531-1532-1533 HERMAN NELSON, AMERICAN AIR FILTER CO., INC., Louisville, Ky.. 1296-1297 JOHN J. NESBITT, INC., Philadelphia 36, Pa........................................ 1293-1294-1295 NEW YORK BLOWER CO., THE, 3145 S. Shields Ave., Chicago 16, 111...... 1399 NIAGARA BLOWER CO., 405 Lexington Ave., New York 17, N. Y..................... 1235 NORMAN PRODUCTS CO., 1150 Chesapeake Ave., Columbus 12, Ohio.......... 1257 O ARTHUR A. OLSON & CO., Broad and Court Sts., Canfield, Ohio ORR & SEMBOWER, INC., Morgantown Rd., Reading, Pa.............. OWENS-CORNING FIBERGLAS CORP., Toledo 1, Ohio ........ . OWENS-ILLINOIS, General Offices, Toledo 1, Ohio......................... .... 1279 .... 1562 1336, 1658 ... 1661 P PACIFIC LUMBER CO., THE, 100 Bush St., San Francisco 4, Calif.............. 1675 PACIFIC STEEL BOILER DIV., NATIONAL-U. S. RADIATOR CORP., Johnstown, Pa..............................................................................:...................... 1534-1535 PACKARD WATER CONDITIONER DIVISION, INC., PACKARD MFG. CO. ' P. O. Box 719, Jacksonville 1, Fla..................................... ......................... .. 1575 PARKS-CRAMER CO., Fitchburg, Mass..........................................................1236-1237 PATTERSON-KELLEY CO., INC., THE, 101 Burson St., East Stroudsburg, Pa.......................................................................................... 1363 PEERLESS ELECTRIC CO., THE, Fan and Blower Div., Warren, Ohio...... 1400 PENN CONTROLS, INC., Goshen, Ind................. :......... ............ :........................ 1494 PENN VENTILATOR CO., Goodman above Allegheny Ave., Philadelphia 40, Pa........................................................................................................ .............;........... 1422 PENNSYLVANIA FURNACE & IRON CO., 316 N. Pine St., Warren, Pa....... 1258 PENNSYLVANIA SEPARATOR CO., Box 348-H, Brookville, Pa....................... 1574 PHILLIPS COOLING TOWER CO., INC., 220 Dupont St., Brooklyn 22, N. Y.. 1356 PITTSBURGH CORNING CORP., One Gateway Center, Pittsburgh 22, Pa... ' .1662-1663 PITTSBURGH LECTRODRYER CORP., Foot of 32nd St., P. O. Box 1766, Pittsburgh 30, Pa.............................................................................. 1238 PITTSBURGH PLATE GLASS CO., Fiber Glass Div., 1 Gateway Center, Pittsburgh 22, Pa................................................................................................ 1337, 1664 H. W. PORTER & CO., INC., 817-G Frelinghuysen Ave., Newark 5, N. J..... 1650 POTTER & BRUMFIELD MFG. CO., INC., Princeton, Ind.................... 1495 POWERS REGULATOR CO., THE, General Office and Factory, 3400 Oakton St., Skokie, 111..............................................................................................1496-1497-1498 PREFERRED UTILITIES MFG. CORP., 1860A Broadway, New York 23, N. Y. 1566 PROPELLAIR DIVISION, ROBBINS & MYERS, INC., 1947 Clark Blvd., . Springfield, Ohio................................................ 1401 FRANK PROX CO., INC., 1201 S. First St., Terre Haute, Ind........... ...... 1536 PUR AIR DIV., BARNEBEY-CHENEY CO., Cassady & 8th Aves., Columbus 3, Ohio............................. ................................................................................... 1322-1323 PYLE-NATIONAL CO., THE, Multi-Vent Div., 1363-78 N. Kostner Ave., Chicago 51, 111................................................................ 1454-1455 il R RAY OIL BURNER CO., 1301 San Jose Ave., San Francisco 12, Calif,... .... 1584-1585 RAYFIELD-STAFFCO BURNER CO., 2066 S. Canalport Ave., Chicago 8, 111.. .1586 RAYPAK CO., INC., 2416 Chico Ave., El Monte, Calif.............................. . 1563 READY-POWER CO., THE, 11231 Freud Ave., Detroit 14, Mich....................... 1372 .:>i Index to Advertisers 1185 REED UNIT-FANS. INC., 1001 St. Charles Ave., New Orleans, La................... 1402 REFLECTAL CORP., A SUB. OF BORG-WARNER CORP., 310 S. Michigan Ave., Chicago 4, 111............... .............................. .............................. ......... ............ 1682 REFRIGERATION APPLIANCES, INC., 923 West Lake St., Chicago 7, 111... 1259 REFRIGERATION ENGINEERING, INC., 7250 E. Slauson Ave., Los Angeles 22, Calif................................................................................ ....................................... 1373 REGISTER & GRILLE MFG. CO., INC., 70 Berry St., Brooklyn 11, N. Y........ 1453 RESEARCH PRODUCTS CORP., Madison 10, Wis............................................... 1338 REVCOR, Dept. R, 249 Edward St., Carpentersville, 111....................................... 1403 REVERE COPPER AND BRASS INCORPORATED, 230 Park Ave., New York 17, N. Y.......................................... ................... :................................:.............. 1313 REZNOR MFG. CO., 66 Union St., Mercer, Pa..:............................. 1282-1283 RHEEM MFG. CO., 7600 S. Kedzie Ave., Chicago 29, 111...............................1260-1261 RIC-WIL INCORPORATED, 24 Brown St., Barberton, Ohio........................... . 1651 RITTLING CORP., THE, 103 Kentucky St., Buffalo 4, N. Y...................... ,... 1364 ROBERTS-GORDON APPLIANCE CO.; Dept. HVG, Buffalo 6, N. Y....:.... 1577 ROBVON BACKING RING CO., THE, 675 Garden St., Elizabeth 2, N. J........ 1509 ROME-TURNEY RADIATOR CO., THE, Erie Blvd., East, Rome, N. Y....... 1365 S SARCO CO., INC., Empire State Bldg., New York 1, N. Y........................... 1634-1635 SARCOTHERM CONTROLS, INC., Empire State Bldg., New York 1, N. Y... 1633 SCULLY SIGNAL CO., 174 Green St., Melrose 76, Mass..................................... 1499 SERVEL AIR CONDITIONING DIV., SERVEL, INC., Evansville 20, Ind.. .1262-1263 SHAW-PERKINS MFG. CO., 201 E. Carson St., Pittsburgh 19, Pa............ .. 1515 E. H. SHELDON EQUIPMENT CO., Muskegon, Mich............................. 1412-1413 SHELDONS ENGINEERING LIMITED, Galt, Ontario, Canada....................... 1404 SIEMON MFG. CO., Grandview, Mo. (Suburb of Kansas City, Mo.)............... 1587 SILVERCOTE PRODUCTS, INC., 161 E. Erie St., Chicago 11, 111...............1680-1681 SIMPLEX MFG. CO., 198-206 N. Main St., Fond du Lac, Wis............. ............ 1500 SKIDMORE CORP., St. Joseph* Mich................................................................... 1611 SLANT-FIN RADIATOR CORP., 87-67-130th St., Richmond Hill 18, N. Y. .. 1366 H. B. SMITH CO., INC., THE, Westfield, Mass....................... ............................ 1537 SNIPS MAGAZINE (publication), 5707 W. Lake St., Chicago 44, 111................ 1695 SOMERS CORP., 6063 Wabash Ave., Detroit 8, Mich.. :........-......... ................. 1339 SONNER-BURNER CO., THE, 412-420 East 6th Ave., Winfield, Kansas....... 1578 SONOCO PRODUCTS CO., Construction Products Div., Hartsville, S. C. ... 1659 SPENCE ENGINEERING CO., INC., 28 Grant St., Walden, N. Y.................... 1501 SPENCER HEATER, LYCOMING DIVISION--AVCO MFG. CORP., Wil liamsport, Pa..........................................................................................................1538-1539 STANDARD STAMPING & PERFORATING CO., 3111 West 49th Place, Chicago 32, 111................................... 1456 STERLING, INC., 3738 N. Holton St., Milwaukee 12, Wis........................ .. 1502 STEWART MFG. CO., INC., Cedar Grove, Essex County, N. J......................... 1457 STILLWATER CLAY PRODUCTS CO., THE, Conduit Div., 3334 Prospect Ave., Cleveland 15, Ohio......................................................................................... 1652 STRONG, CARLISLE & HAMMOND CO., 1392 W. Third St., Cleveland 13, Ohio............................................................................................................................. 1637 SWARTWOUT CO., THE, 18511 Euclid Ave., Cleveland 12, Ohio..................... 1423 T TACO HEATERS, INC., 1160 Cranston St., Cranston 9, R. 1............................. 1602 TAYLOR FORGE & PIPE WORKS, P. O. Box 485, Chicago 90, 111....................... 1510 TAYLOR INSTRUMENT COMPANIES, Rochester 1, N. Y................................ 1503 TECTUM DIVISION, PEOPLES RESEARCH & MFG. CO., 105 S. Sixth St., Newark, Ohio..................................................................................................... 1676 THERMOBLOC DIV., PRAT-DANIEL CORP., Meadow St., South Norwalk, Conn....................... 1284 H. A. THRUSH & CO., Peru, Ind.................................................................. .1600-1601 TITUS MFG. CORP., 113 East 8th St., Waterloo, Iowa................................. 1458-1459 TITUSVILLE IRON WORKS CO., THE, DIV. OF STRUTHERS WELLS CORP., Titusville, Pa..........................................................................................1564-1565 TJERNLUND MFG. CO., 2140 Kasota Ave., St. Paul 14, Minn.......................... 1285 TORRINGTON MFG. CO., THE, 50 Franklin St., Torrington, Conn........... 1406-1407 TRADE-WIND MOTORFANS, INC., 7755 Paramount Blvd., Rivera, Calif.... 1405 1186 1956 Guide TRANE CO., THE, 2021 Cameron Ave., LaCrosse, Wis................ 1298-1299-1300-1301 TRION, INC., 1000 Island Ave., McKees Rocks, Pa. .................. .......................... 1340 TUBE TURNS, A DIV. of NATIONAL CYLINDER GAS CO., Louisville 1, Ky.. 1S11 TUTTLE & BAILEY, INC., New Britain, Conn.......... ............ ..................,.l .1460-1461 U UNION ASBESTOS & RUBBER CO., 332 S. Michigan Ave., Chicago 4, 111.... 1265 UNITED STATES REGISTER CO., Battle Creek, Mich....:.........................1462-1463 UNITED STATES STEEL, Pittsburgh, Pa.................................................................... 1425 UNIVERSAL DIFFUSER CORP., 1360 Garrison Ave., New York 59, N. Y........ 1464 UTILITY FAN CORP., A DIV. of UTILITY APPLIANCE CORP., 911 East 59 St., Los Angeles 1, Calif............................................ .................................................. 1264 V VAPOR HEATING CORP., 80 E. Jackson Blvd., Chicago 4, 111. ................... VIBRATION MOUNTINGS, INC., 98-01 50th Ave., Corona 68, N. Y................. VIKING AIR PRODUCTS, DIV. of NATIONAL-U. S. RADIATOR CORP., 5601 Walworth Ave., Cleveland 2, Ohio.................................................................. VORTOX CO., Claremont, Calif.......................................................................... ........ VULCAN RADIATOR CO., THE, 26 Francis Ave., Hartford 6, Conn............... 1567 1688 1408 1341 1367 W WALTON LABORATORIES, Irvington 11, N. J......................................... ................ 1239 WATERLOO REGISTER CO., INC., P. O. Box 72, Waterloo, Iowa.................. 1465 WARREN WEBSTER & CO., 1731 Federal St, Camden 5, N. J................... 1638-1639 WEBSTER ENGINEERING CO., THE, DIV. of SURFACE COMBUSTION CORP., 115 S. Frisco St., P. O. Box 2168-, Tulsa, Okla....................................... 1579 WEIL-McLAIN CO., General Sales Office, Michigan City, Ind............................. 1540 WESIX ELECTRIC HEATER CO., 390 First St., San Francisco 5, Calif............ 1307 WESTERN BLOWER CO., 1800 Airport Way, Seattle 4, Wash........ .......... .. 1409 WESTERN ENGINEERING & MFG. CO., 4112 Glencoe Ave., Venice, Calif.. 1424 WESTINGHOUSE ELECTRIC CORP., Air Conditioning Div., Staunton, Virginia................................................................................................................................ 1240 WESTINGHOUSE ELECTRIC CORP., STURTEVANT DIV., Hyde Park, Boston 36, Mass.................................................................................................. .. .1342, 1410 WHITE-RODGERS ELECTRIC CO., 1209 Cass Ave., St. Louis 6, Mo.............. 1504 EDWIN L. WIEGAND CO., 7672 Thomas Blvd., Pittsburgh 8, Pa............... 1308-1309 WILL-BURT CO., THE, Orrville, Ohio.......................................................................... 1569 L. J. WING MFG. CO., 59 Vreeland Mills Road, Linden, N. J..................... 1302-1303 WIREMOLD CO., THE, Hartford 10,Conn.................................................................... 1469 WOLVERINE TUBE, 1463 Central Ave., Detroit 9, Mich..................................1314-1315 WOOD CONVERSION CO., Dept. 220-6, First National Bank Bldg., St. Paul 1, Minn................................................................ ......................... .......................................... 1677 WORTHINGTON CORP., Air Conditioning & Refrigeration Div., Harrison, N. J........................................................................................................................................ 1241 Y YORK CORP., York, Pa....................................................................................................... 1242 YORK-SHIPLEY, INC., York 16, Pa............................................................................... 1590 YOUNG RADIATOR CO., Dept. 546, Racine, Wis..................................................... 1304 YOUNG REGULATOR CO., 5209 Euclid Ave., Cleveland 3, Ohio................ 1470-1471 Z Z-CRETE DIVISION, ZONOLITE CO., 135 S. LaSalle St., Chicago 3, 111........ 1653 JOHN ZINK CO., 4401 S. Peoria, Tulsa, Okla......................................................1588-1589 INDEX TO MODERN EQUIPMENT Of Advertisers Appearing In Heating Ventilating Air Conditioning Guide, 1956 ACCUMULATORS AIR COMPRESSORS (See Com- AIR CONDITIONING SCREEN Domestic Pump & Mfg. Corp., 1605 pressors, Air) ' (See Screening) Hoffman Specialty Mfg. Corp., 1622-1625 AIR CONDITIONING UNITS McQuay, Inc., 1288-1289 AIR CONDITIONING COILS Acme Industries, Inc., 1358 Worthington Corp., 1241 Acme Industries, Inc., 1358 ' Aerofin Corp., 1359-1361 Addison Products Co., 1243 - Air & Refrigeration Corp.,.1219 ACOUSTICAL CONTROL Airtemp Div., Chrysler Corp., 1248 Airtemp Div., Chrysler Corp., 1248 Burgess-Manning Co., 1438 1249 . 1249 Konund Co., Inc., The, 1687 American Blower Corp., 1220-1221 American Blower Corp., 1220-1221 Tectum Div., Peoples Research & Bell & Gossett Co., 1598-1599 American Moistening Co., 1222 Mfg. Co., 1676 Carrier Corp., 1226-1227 American Radiator & Standard Drayer-Hanson, Inc., Div. of Na- Sanitary Corp., (Plumbing & ADHESIVES tional-U. S. Radiator Corp.,1229 Heating Div.,) 1523-1525 Armstrong Cork Co., 1665 Goodyear Tire & Rubber Co., Inc., Governair Corp., 1232 Hastings Air Conditioning Co., Inc., American-Standard, Air Condition ing Div., 1244-1245 The, 1334 -------- 1233 . Armstrong Furnace Co., 1246-1247 Miracle Adhesives Corp., 1654 Kennard Corp., 1234 Bell & Gossett Co., 1598-1599 Mario Coil Co., 1355 Bishop <fc Babcock Mfg. Co., The, ADSORBERS, Odor McQuay, Inc., 1288-1289 (Massachusetts Blower Div.), 1377 Barnebey-Cheney Co., 1322-1323 Modine Mfg. Co., 1290-1291 Brunner Mfg. Cov 1368 ' Connor Engineering Corp., 1326-1327 John J. Nesbitt, Inc., 1293-1295 Buensod-Staoey, Inc:, 1224 Charles E. Manning Co., 1335 Niagara Blower Co., 1235 Buffalo Forge Co., 1382 Patterson-Kelley Co., Inc., The, Burnham Corp., 1526-1527 - ADSORPTION SYSTEMS 1363 . Carrier Corp.,-1226-1227 Barnebey-Cheney Co., 1322-1323 Refrigeration. Appliances, Inc., 1259 Clarage Fan Co., 1225, 1387 Connor Engineering Corp., 1326-1327 Refrigeration Engineering, Inc., 1373 Curtis Mfg. Co., Refrigeration Div., Desomatic Products, Inc.,. 1228 . Rome-Tumey Radiator Co., The, 1370 Charles E. Manning Co., 1335 1365 Drayer-Hanson, .Inc., Div. of Na- Pittsburgh Lectrodryer Corp., 1238 Pur Air Div., Barnebey-Cheney Co., 1322-1323 Trane Co., The. 1298-1301 Westinghouse Electric Corp., Conditioning Div., 1240 Air tional-U. S. Radiator Corp., 1229 Electromode Corp., 1305 Farr Co., 1332-1333 Worthington Corp., 1241 Fedders-Quigan Corp., 1286 AFTER COOLERS York Corp., 1242 Frick Co., 1371 American District Steam Div., Young Radiator Co., 1304 General Automatic Products Co.,- Adsco Industries, Inc., 1505, 1594 1513 Niagara Blower Co., 1235 General Electric Co., 1231 Parks-Cramer Co., 1236-1237 . AIR CLEANING EQUIPMENT (See also Fillers. Air) Air & Refrigeration Corp., 1219 Air Devices, Inc., 1316,1432 Air Filter Corp., 1317 Air-Maze Corp., The, 1318 American Air Filter Co., Inc., 1319 1321 American Moistening Co., 1222 V. D. Anderson Co., The, 1612-1613 Bahnson Co., The, 1223 Barnebey-Cheney Co., 1322-1323 Buffalo Forge Co., 1382 Cambridge Filter Corp., 1324 Carey Electronic Engineering Co., Continental Air Filters, Inc., 1328 Dollinger Corp., 1330-1331 AIR CONDITIONING COM PRESSION EQUIPMENT Airtemp Div., Chrysler Corp., 1248 1249 American Blower Corp., 1220-1221 Brunner Mfg. Co., 1368 Carrier Corp., 1226-1227 Curtis Mfg. Co., Refrigeration Div., 1370 Frick Co., 1371 General Electric Co., 1231 Hydraline Products, Div. Borg- Warner Corp., 1251 Servel, Inc., 1262-1263 ' Trane Co., The, 1298-1301 Westinghouse Electric Corp., Air Conditioning Div., 1240 Worthington Corp., 1241 ' York Corp., 1242 `- Governair Corp., 1232 Hastings Air Conditioning Co., Inc., 1233 Hydraline Products, Div. Borg- Warner Corp., 1251 * S. T. Johnson Co., 1582-1583 Kennard Corp., 1234 Mario Coil Co., 1355 McQuay. Inc., 1288-1289 Modine Mfg. Co., 1290-1291 Mueller CUmatrol, Div. of Worth ington Corp., 1254-1255 National-U. S.-Radiator Corp., 1530 1533 Herman Nelson, American Air Filter Co., Inc., 1296-1297 John J. Nesbitt, Inc., 1293-1295 Niagara Blower Co., 1235 Norman Products Co., 1257 Parks-Cramer Co., 1236-1237 Electro-Air Cleaner Co., 1329 Patterson-Kelley Co., Inc., The, Farr Co., 1332-1333 Goodyear Tire <fc Rubber Co.; 1334 Charles E. Manning Co.. 1335 Owens-Coming Fiberglas Corp., 1336, 1658 AIR CONDITIONING CON TROLS (See Controllers and Con- Irol Equipment, Electric, Humidity and Temperature Controls) 1363 Pennsylvania Furnace <fc Iron Co., 1258 Ready-Power Co., The, 1372 Refrigeration Appliances, Inc., 1259 Pittsburgh Plate Glass Co., Fiber Refrigeration Engineering, Inc., 1373 Glass Div., 1337, 1664 Research Products Corp., 1338 E. H. Sheldon Equipment Co., AIR CONDITIONING DUCTS (See Ducts, Air Conditioning, Un Rheem Mfg. Co., 1260-1261 Rittling Corp., The, 1364 Roberts-Gordon Appliance Corp., 1412-1413 der Floor) 1577 Somers Corp., 1339 Servel, Inc., 1262-1263 Trion, Inc., 1340 Sheldons Engineering Ltd., 1404 Vortox Co., 1341 AIR CONDITIONING REGIS Trane Co., The, 1293-1301 Westinghouse Electric Corp., Stur- TERS AND GRILLS (See Grilles, Union Asbestos & Rubber Co., 1265 tevant Div., 1342 Registers) ' - Vulcan Radiator Co., The, 1367 1187 Please mention THE GUIDE 1956 when writing to Advertisers 1956 Guide Western Blower Co., 1409 Hart A Cooley Mfg., Co., 1444-1445 Connor Engineering Corp., 1326 Worthington Corp., 1241 Hendrick Mfg. Co., 1446-1447 1327, 1440-1441 York Corp., 1242 . Independent Register Co., The, 1448 Charles E. Manning Co., 1335 York-Shipley, Inc., 1590 - Knowles Mushroom Ventilator Co., Young Radiator Co., 1304 1449 AIR TRAPS (See Traps, Air) Lima Register Co., 1450-1451 AIR COOLING EQUIPMENT. Louvra Mfg. A Sales Co., 1452 AIR TUBING, Flexible Metal (See (See Coding Equipment, Air) Pyle-National Co., The, Multi-Vent Tubing, Flexible Metallic) Div., 1454-1455 AIR COOLING, HUMIDIFYING Register A Grille Mfg. Co., Inc., 1453 AND DEHUM1DIFYING AP Standard Stamping A Perforating PARATUS .. Co., 1456 Addison Products Co., 1243 Titus Mfg. Corp., 1458-1459 Aerofin Corp., 1359-1361 , Tuttle A Bailey, Inc., 1460-1461 Air A Refrigeration Corp., 1219 United States Register Co., 1462 Airtemp Div., Chrysler Corp., 1248 1463 1249 Universal Diffuser Corp., 1464 American Blower Corp., 1220-1221 ' Vulcan Radiator Co., The, 1367 American Moistening Co1222 Waterloo Register Co., 1465 American-Standard, Air Condition AIR TURNING VANES (See Vanes, Air Turning) AIR VELOCITY METERS (See Meters) AIR WASHERS Air & Refrigeration Corp., 1219 Airfan Engineering Cc., 1343 . American Blower Corp., 1220-1221 Bahnson Co.. The, 1223 ing Div., 1244-1245 . AIR DUCTS (See Duds) Armstrong Machine Works, 1614-1615 Bayley Blower Co., 1376 Bishop A Babcock Mfg. Co., The, Bahnson Co., The, 1223 AIR ELIMINATORS (Massachusetts Blower Div.), 1377 Bayley Blower Co., 1378 V. D. Anderson Co., The, 1612-1613 Buensod-Stacey, Inc., 1224 .Buensod-Stacey, Inc., 1224 Armstrong Machine Works, 1614-- Buffalo Forge Co., 1382 Buffalo Forge Co., 1382 1615 Carrier Corp., 1226-1227 Carrier Corp., 1226-1227 Dole Valve Co., The, 1640 Clarage Fan Co., 1225, 1387 Clarage Fan Co., 1225, 1387 C. A. Dunham Co., 1618-1621 Continental Air Filters, Inc., 1328 Curtis Mfg. Co., Refrigeration Div., Hoffman Specialty Mfg. Corp., 1622 Dollinger Corp., 1330-1331 1370 1625 . Mario Coil Co., 1355 Desomalic Products, Inc., 1228 Illinois Engineering Co., 1630-1632 D. J. Murray Mfg. Co., 1292 Drayer-Hanson, Inc., Div. of Na- Maid-O'-Mist, Inc., 1626-1627 tional-U. S. Radiator Corp;, 1229 Jas. P. Marsh Corp., 1628-1629 Niagara Blower Co., 1235 Parks-Cramer Co.{ 1236-1237 Farr Co., 1332-1333 Sarco Co., Inc., 1634-1635 Sheldons Engineering Ltd., 1404 Frick Co.. 1371 Taco Heaters, Inc., 1602 Trane Co., The, 1298-1301 General Electric Co., 1231 ' H. A. Thrush A Co., 1600-1601 Western Blower Co.; 1409 . Governsir Corp.. 1232 . Westinghouse Electric Corp., Stur- Hydraline Products, Div. Borg- AIR FILTER GAGE tevant Div., 1342 Warner Corp., 1251 . Air Devices, Inc., 1316, 1432 York Corp., 1242 Kennard Corp., 1234 Cambridge Filter Corp., 1324 Mario Coil Co., 1355 Owens-Corning Fiberglas Corp!, ALARMS, Water Level McQuay, Inc., 1288-1289 1336, 1658 McDonnell A Miller, Inc., 1570-1573 Modine Mfg. Co., 1290-1291 Research Products Corp., 1338 John J. Nesbitt, Inc., 1293-1295 ALUMINUM DUCTS (See Duets, Niagara Blower Co., 1235 AIR FILTERS (See Filters, Air; Aluminum) Parks-Cramer Co.. 1236-1237 - . Air Cleaning Equipment) Pittsburgh Lectrodryer Corp., 1238 ALUMINUM FOIL, Insulation . Refrigeration Appliances, Inc., 1259 AIR MEASURING INDICAT Infra Insulation, Inc., 1679 Refrigeration Engineering Inc., 1373 ING AND RECORDING IN Reflectal Corp., 1682 Serve!, Inc.. 1262-1263 STRUMENTS Silvercote Products, Inc., 1680-1681 Trade-Wind Motorf&ns, Inc., 1405 . Anemostat Corp. of America, 1434 Trane Co., The, 1296:1301 t 1435 ALUMINUM FOIL VAPOR BAR Westinghouse Electric Corp.,' Air Illinois Testing Laboratories, Inc., Conditioning Div., 1240 1486 RIER (See Aluminum Foil) Worthington Corp., 1241 York Corp., 1242 ' Minneapolis-Honeywell Regulator Co., 1490-1491 Parks-Cramer Co., 1236-1237 ALUMINUM SHEETS (See Sheets, Aluminum) ' AIR DIFFUSER UNITS, Hifeh Taylor Instrument Co's., 1503 Pressure Tnon, Inc., 1340 AMMONIA COILS (See Coils, Am Anemostat Corp. of America, 1434 monia) ' 1435 AIR. MIXING UNITS (See Dual Auer Register Co., 1436 Duet Systems) ' . ANCHORS, for Insulation Connor Engineering Corp., 1326 1327, 1440-1441 ' Lima Register Co., 1450-1451. Standard Stamping A Perforating Co., 1456 . Tuttle A Bailey, Inc., 1460-1461 AIR MOISTENING APPARA TUS (See Humidifiers) . AIR PURIFYING APPARATUS Air A Refrigeration Corp., 1219 Air Filter Corp., 1317 Devices, Inc., 1654 Miracle Adhesives Corp., 1654 H. W. Porter A Co., Inc., 1650 ANEMOMETERS Illinois Testing Laboratories, Inc., AIR DIFFUSERS AND VENTI LATORS. CEILING, FLOOR AND WALL A-J Mfg. Co., 1426-1427 Air Control Products, Inc., 1428-1431 Air Devices, Inc., 1316, 1432 Air-Factors, Inc., 1433 . Airfan Engineering Co., 1343 Anemostat Corp. of America, 1434 1435 V. D.Anderson Co., The, 1612-1613 Barnebey-Cheney Co., 1322-1323 Connor Engineering Corp., 1326-1327, 1440-1441 Dollinger Corp., 1330-1331 Electro-Air Cleaner Co., 1329 Charles E. Manning Co., .1335 Somers Corp., 1339 Trion, Inc., 1340 Universal Diffuser Corp., 1464 1486 ANGLES AND ELBOWS Lamneck Div., Clayton A Lambert Mfg. Co., 1258 ASBESTOS PRODUCTS (See In sulation) Philip Carey Mfg. Co., The, 1656-- 1657 Auer Register Co., The, 1436 Barber-Colman Co., 1437, 1473 Connor Engineering Corp., 1326 AIR RECEIVERS (See Receivers, Air) Infra Insulation, Inc., 1679 ' Johns-Manville, 1670-1671 H. W. Porter A Co., Inc., 1650 1327, 1446-1441 AIR RECOVERY. Method of Reflectal Corp., 1682 Charles Demuth A Sons, Inc., 1439 Barnebey-Cheney Co., 1322-1323 Reid Hayden Inc., 1650 Numerals following Manufacturers' Names refer to pages In the Catalog Data Section -5: Index to Modern Equipment 1189 ATMOSPHERIC COOLING BENDS, Pipe, Ferrous and Non- Century Fan A Ventilator Co., 1384 TOWERS (See Cooling Towers, Ferrous Champion Blower A Forge Co., 1385 Atmospheric) . Arthur Harris A Co., 1512 Chicago Blower Corp., 1386 Parks-Cramer Co., 1236-1237 Clarage Fan Co., 1225, 1387 ATOMIZING SPRAY NOZZLES C. A. Dunham Co., 1618-1621 (See Spray Nozzles) BENDS (See Pipe, Returns) Garden City Fan Co., 1390 General Blower Co., 1391 ATTIC FAN COOLERS (See Fans, BLOCKS, Asbestos Hartzell Propeller Fan Co., Div. of Attic; Ventilators, Attic) Philip Carey Mfg. Co., The, 1656 Castle Hills Corp., 1392 1657 AUTOMATIC FUEL BURNING Johns-Manville, 1670-1671 Hastings Air Conditioning Co., Inc., 1233 EQUIPMENT (See Burners, Au Hg Electric Ventilating Co., 1287 tomatic; Gas Burners; Oil Burners; BLOCKS, Glass 1393 Stokers) Owens-Illinois, 1661 Joy Mfg. Co., 1394-1395 Pittsburgh Corning Corp., 1662 AUTOMATIC SHUTTERS (See Lau Blower Co., The, 1396-1397 McQuay, Inc., 1286-1289 Shutters, Automatic) BLOWER HOUSINGS Morrison Products, Inc., 1398 Airfan Engineering Co., 1343 Mueller Climatrol, Div. of Worth AXIAL FLOW FANS (See Fans, Bishop A Babcock Mfg. Co., .The ington Corp., 1254-1255 Axial Flow) (Massachusetts Blower Div.), Herman Nelson, American Air Filter 1377 ' . BACKING RINGS (See Rings, Brundage Co., The, 1380-1381 Co., Inc., 1296-1297 John J. Nesbitt, Inc., 1293-1295 Backing) Champion Blower A Forge Co., 1385 New York Blower Co., The, 1399 BASEBOARD HEATING A-J Mfg. Co., 1426-1427 Air Control Products, Inc., 1428-1431 Air-Factors, Inc., 1433 American Radiator A Standard Sanitary Corp., (Plumbing & Heating Div.), 1523-1525 Auer Register Co., 1436 - ___ Burnham Corp., 1526-1527 Campbell Heating Co., 1268-1269 Columbia BoilerCo., 1546-1547 Crane Co., 1526-1529 Dole Vale Co., The, 1640 C. A. Dunham Co., 1618-1621 Electromode Corp., 1305 Feddcrs-Quigan Corp., 1286 General Automatic Products Corp., 1513 Hart & Cooley Mfg. Co., 1444-1445 Hoffman Specialty Mfg. Corp., 1622-1625 Kritzer Radiant Coils, Inc., 1514 Lima Register Co., 1450-1451 National Clay Pipe Mfgis., The, 1516-1521 National-U. S. Radiator Corp., 1530 1533 Herman Nelson, American Air Filter Co., Inc., 1296-1297 John J. Nesbitt, Inc., 1293-1295 Raypak Co., Inc., 1563 Rittling Corp., The, 1364 Rome-Turncy Radiator Co., The, 1365 Sarco-Sarcotherm, 1633-1635 Shaw-Perkins Mfg. Co., 1515 Slant-Fin Radiator Corp., 1366 Standard Stamping A Perforating Co., 1456 Trane Co., The, 1298-1301 Tuttle A Bailey, Inc., 1460-1461 Union Asbestos A Rubber Co., 1265 Vulcan Radiator Co., The, 1367 Warren Webster A Co., 1638-1639 Weil-McLain Co., 1540 Wesix Electric Heater Co., 1307 Edwin L. Wiegand Co., 1306-1309 Clarage Fan Co., 1225, 1387 Lau Blower Co., The, 1396-1397 Morrison Products, Inc., 1398 Rcvcor, 1403 Utility Fan Corp., 1264 BLOWER MOTORS (See Motors, Electric) BLOWERS, Centrifugal (See Fane) BLOWERS, Fan (See Fans, Supply and Exhaust) ' BLOWERS, Forced Draft Aerovent Fan Co., Inc., 1374 Aladdin Heating Corp., 1375 American Blower Corp.,' 1220-1221 Bayley Blower Co., 1376 ' Bishop A Babcock Mfg. Co., The, (Massachusetts Blower Div.), 1377 Buffalo Forge Co., 1382. Century Fan A Ventilator Co., 1384 Champion Blower A Forge Co., 1385 Chicago Blower Corp., 1386 Clarage Fan Co., 1225, 1387 . Garden City Fan Co., 1390 General Blower Co., 1391 ' ' Hg Electric Ventilating Co., 1287, 1393 Joy Mfg. C o., 1394-1395 . Lau Blower Co., The, 1396-1397 Herman Nelson, American Air Filter Co., Inc., 1296-1297 New York Blpwer Co., The, 1399 Sheldons Engineering Ltd., 1404 Tiernlund Mfg. Co., 1285 ' Westinghouse Electric Corp., Stur- tevant Div., 1410 L. J. Wing Mfg. Co., 1302-1303 BLOWERS, Heating and Venti lating Aerovent Fad Co., Inc., 1374 Airfan Engineering Co., 1343 Aladdin Heating Corp., 1375 American Blower Corp., 1220-1221 Niagara Blower Co., 1235 Peerless Electric Co., The, 1400 Refrigeration Engineering, Inc., 1373 Revcor, 1403 . Sheldons Engineering Ltd., 1401 Torrington Mfg. Co., The, 1406-1407 Trane Co., The, 1298-1301 Utility Fan Corp., 1264 Viking Air Conditioning Div., of - The National-U. S. Radiator Corp., 1408 Western Blower Co.. 1409 Westinghouse Electric Corp., Stur- tevant Div., 1410 L. J. Wing Mfg. Co., 1302-1303 BLOWERS, Pressure Aerovent Fan Co., Inc., 1374 Air Fan Engineering Co., 1343 American Blower Corp., 1220-1221 Bayley Blower Co., 1376 Brookside Products Co., Inc., 1379 Buffalo Forge Co., 1382 Century Fan A Ventilator Co., 1384 Champion Blower A Forge Co., 1385 Chicago Blower Corp., 1386 Clarage Fan Co., 1225, 1387 ' Dcsomatic Products, Inc., 1228 . General Blower Co., 1391 Hartzell Propeller Fan Co., Div. of Castle Hills Corp., 1392 Hg Electric Ventilating Co., 1287, 1393 Lau Blower Co., The, 1396-1397 Peerless Electric Co., The, 1400 Sheldons Engineering Ltd., 1404 . .Westinghouse Electric Corp., Stur- tevant Div., 1410 L. J. Wing Mfg. Co., 1302-1303 BLOWERS. Turbine C. L. Ammerman Co., 1415 General Blower Co., 1391 Western Blower Co., 1409 L. J. Wing Mfg. Co., 1302-1303 - BLOWERS.-Warm Air Furnace Aladdin Heating Corp., 1375 BASES, Fan and Motor Vibra American Foundry A Furnace Co. American Blower Corp., 1220-1221 tion 1266-1267 American Standard, Air Condi T. R. Finn A Co., Inc., 1688 Korfund Co., Inc., The, 1687 ' American-Standard, Air Condition tioning Div., 1244-1245 ing Div., 1244-1245 Brookside Products Co., Inc., 1379 Vibration Mountings, Inc., 1688 Bayley Blower Co., 1376 . Brundage Co., The, 1380-1381 BELLOWS . Bishop A Babcock Mfg. Co., The, 1377 Flexonics Corp., 1507 ' ' Bishop A Bibcock Mfg. Co., The (Massachusetts Blower Div.); 1377 Brookside Products Co., Inc., 1379 Brundage Co., The, 1380-1381 Chicago Blower Corp., 1386 Clarage Fan Co., 1225, 1387 General Blower Co., 1391 Lau Blower Co.. The, 1396-1397 Morrison Products, Inc., 1398 Fulton Sylphon Div., The, Robert- Buffalo Forge Co., 1382 Mueller Climatrol, Div. of Worth shaw-Fulton Controls Co., 1478 Campbell Heating Co., 1266-1269 1479 E. K. Campbell Co., 1270 ington Corp.. 1254-1255 Peerless Electric Co.. The, 1400 . Please mention l THE GUIDE 1956 when writing to. Advertisers 1190 1956 Guide Utility Fan Corp., 1254 ' ' H. B. Smith, Co., Inc., The, 1537 American Radiator- A Standard Viking Air Conditioning Div. of Spencer Heater, Lycoming Div., Sanitary Corp., (Plumbing. A The National-U. S. Radiator Aveo Mfg. Corp^, 1538-1539 - Heating Div.), 1523-1525 Corp., 1408 WeU-McLain Co., 1540 Babcock A Wilcox Co., The, 1542 L. J. Wing Mfg. Co., 1302-1303 Bryan Steam Corp., 1543 , ' BOILERS, Down Draft Burnham Corp., 1526-1527 ' ' BOILER-BURNER -. Air Devices, Inc., 1316, 1432 - Aldrich Co., 1541 Cleaver-Brooks Co., 1544, 1580 Cleaver-Brooks. Co., 1544, 1580 Johnston Bros.. Inc., 1557 Combustion Engineering, Inc.,' 1548 Kewanee Boiler Div. of American- 1549 - American Radiator A- Standard Standard, 1558-1561 ' Crane Co., 1528-1529 . Sanitary Corp., (Plumbing A Titusville Iron Works Co., The (Div. Cyclotherm Div. of National-U. S. Heating Div.)* 1525-1525 of Struthers-Wells Corp.), 1564 Radiator Corp., 1545 Babcock A Wilcox Co., The, 1542 1565 Dewey-Shepard Boiler Co., 1550 Bryan Steam Corp., 1543 ` Dutton Boilers, Div. Hapman- Burnham Corp., 1526-1527 Cleaver-Brooks Go.* 1544, 1580 . ' ColumbiaBoiler Co., 1546^-1547- ' Dewey-Shepard Boiler Co., 1550 Eddington Metal Specialty Co., 1591 Dutton Co., 1551 . .. . BOILERS, Fire Tube Farrar A'Trefts Div., Adsco In Cleaver-Brooks Co., 1544, 1580 ' -. dustries, Inc., 1554' Columbia Boiler Co., 1546-1547 - Fitzgibbons Boiler Co., Inc., 1552-- Combustion Engineering, Inc., 1553 . * Farrer ' A Trefts Div., Adsco In 1548-1549 dustries, Inc., 1554 Dewey-Shephard Boiler Co., 1550 Fitzgibbons'* Boiler Co., Inc., 1552 Orr A Sembower, Inc., 1562 General Automatic Products Co., 1513 . .. General Electric Co., 1230 1553 . Preferred Utilities Mfg. Corp., 1566 Hydraline Products, Div. Borg- General Automatic Products Corp., Titusville Iron Works Co., 1564-1565 Warner Corp., 1251 1513 Hydrotherm. Inc., 1555 Gordon-Piatt, Inc., 1576 ' Hydrotherm, Inc., 1555 - Johnston Brothers, Inc., 1557 Kewanee Boiler Div. of American- Standard, 1558-1561 Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 National-U.' S. Radiator Corp., 1530-1533 Norman Products Co., 1257 . Orr A Sembower, Inc., 1562 Pacific Steel Boiler Div., National- U. S. Radiator Corp., 1534-1535 Pennsylvania Furnace A Iron Co., 1258 Ray Oil Burner Co., 1584-1585 Raypak Co., Inc., 1563 ' H. B. Smith Co., Inc:, The, 1537 Sonner Burner Co., The, 1578 Titusville Iron Works Co., The, (Div. of Struthers-Wells Corp.), 1564-1565 Weil-McLain Co., 1540 BOILER COMPOUNDS {See Com pounds, Boiler) BOILER COVERING {See Cover ing, Pipe and Surfaces) BOILERS. Gas Fired Aldrich Co., 1541 American Radiator A Standard Sanitary Corp., (Plumbing A Heating Div.), 1523-1525 . ' Babcock A Wilcox Co., The, 1542 Bryan Steam Corp., 1543 . . - Burnham Corp., 1526-1527 . Cleaver-Brooks Co., 1544, 1580 Columbia Boiler Co., 1546-1547 Combustion Engineering, Inc., 1548 1549 Crane Co., 1528--1529 . Cyclotherm Div. of National-U. S.' Radiator Corp., 1545 . Dewey-Shepara Boiler Co., 1550 Dutton Boilers, Div. Hapman- Dutton Co., 1551 Farrar A Trefts Div., Adsco In dustries, Inc., 1554 Fitzgibbons Boiler Co., Inc., 1552 1553 General Automatic Products Co., 1513 . . Hydraline Products, Div. Borg-' Warner Corp., 1251 Hydrotherm. Inc., 1555 . International Boiler Works Co., 1556 Johnston Bros., Inc., 1557 International Boiler Works Co., The, 1556 : S. T. Johnson Cc., 1582-1583 . Johnston Bros., Inc., 1557 . Kewanee Boiler Div. of American- Standard, 1558-1561 Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 National-U. S. Radiator Corp., 1530 1533 Orr A Sembower, Inc., 1562 Pacific Steel Boiler Div., National- U. S. Radiator Corp., 1534-1535 Pennsylvania Furnace A Iron Co., 1258 .. Preferred Utilities Mfg. Corp., 1566 Frank Pro* Co., Inc., 1536 . Raypak Co., Inc., 1563. Roberts-Gordon Appliance Corp., 1577 . H. B. Smith Co., Inc., The, 1537 Spencer Heater, Lycoming Div., Avco Mfg. Corp., 1538^1539 . Titusville Iron Works Co., The, (Div. of Struthers-Wells Corp.), 1564-1565 Vapor Heating Corp., 1567 Weil-McLain Co.,1540 York-Shipley, Inc., 1590 BOILER FEED PUMPS Pumps, Boiler Feed) {See Kewanee Boiler Div. of AmericanStandard. 1558-1561 BOILERS. Water High Temperature, ' Mueller Climatrol,- Div. of Worth International Boiler Works Co., 1556 BOILER FEED WATER TREAT MENT Packard Water Conditioner Div., Packard Mfg. Co., 1575 BOILER FEEDERS (See Feeders, Boiler Water) BOILER GRATES (See Grates or Boilers) BOILERS, Cast-Iron . American Radiator A Standard Sanitary Corp., (Plumbing A Heating Div.), 1523-1525 Burnham Corp., 1526-1527 Crane Co., 1528-1529 ' Hydrotherm, Inc., 1555 Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 National-U. S. Radiator Corp., 1530-1533 ington Corp., 1254-1255 National-U. S. Radiator Corp., 1536-. BOILERS, Magazine Feed 1533 .Packard Water Conditioner Div. Orr A Sembower, Inc., 1562 Packard Mfg. Co., 1575 Pacific Steel Boiler Div., NationalU. S. Radiator Corp., 1534-1535 Pennsylvania Furnace A Iron Co., 1258 Preferred Utilities Mfg. Corp., 1566 Raypak Co., Inc., 1563 . Roberts-Gordon Appliance Corp., 1577 H. B. Smith Co., Inc., The, 1537 Spencer Heater, Lycoming Div, Avco Mfg. Corp., 1538-1539 Titusville Iron Works Co., The, (Div. of Struthers-Wells Corp.), 1564-1565 Vapor Heating Corp., 1567 Weil-McLainCo., 1540 Worthington Corp., 1241 BOILERS, Oil Burning Air Devices, Inc., 1316, 1432 Aldrich Co., 1541 ' American Radiator A Standard Sanitary. Corp., (Plumbing A Heating Div.), 1523-1525 Babcock A Wilcox Co., The, 1542 Bryan Steam Corp., 1543 Burnham Corp., 1526-1527 ' Cleaver-Brooks Co.,.1544, 1580 Columbia Boiler Co., 1546-1547 Combustion Engineering, Inc., 1548 1549 Crane Co., 1528-1529 . Cyclotherm Div. of National-U. S. Radiator Corp., 1545 Dewey-Shepard Boiler Co., 1550 Pennsylvania Furnace A Iron Co., Dutton Boilers, Division Hapman- 1258 BOILERS, Heating Dutton Co., 1551 Frank Pro* Co., 1536 Airtemp Div., Chrysler Corp., 1248 Eddington Metal Specialty Co., 1591 Roberts-Gordon Appliance Corp., 1249 Farrar A Trefts Div., Adsco In 1577 Aldrich Co., 1541 dustries, Inc., 1554 Numerals following Manufacturers* Names refer to pages In the Catalog Data Section Index to Modern Equipment 1191 Fitzgibbons Boiler Co.. Inc., 1552 1553 Hydraline Products, Div.- BorgWarner Corp., 1251 International Boiler Works Co., The, 1550 S. T. Johnson Co;, 1582-1583 Johnston Bros., Inc., 1557 Kewanee Boiler Div. of American- Standard, 1558-1561 Preferred Utilities Mfg. Corp., 1566 Titusville Iron Works Co., The, (Div. of Struthers-Wells Corp.), 1564-1565 Vapor Heating Corp., 1567 York-Shipley, Inc., 1590 BOILERS, Water Tube American Radiator A Standard Sanitary Corp., (Plumbing A nay UU burner Uo., 1584-1585 Rayfield-Staffco Burner Co., 1586 Roberts-Gordon Appliance Corp.. 1577 Siemon Mfg. Co., 1587 Sonner Burner Co., The, 1578 Webster.Engineering Co., The, 1579 York-Shipley, Inc., 1590 John Zink Co., 1588-1589 National-U. S. Radiator Corp., The. Heating Div.), 1523-1525 1530-1533 Babcock A Wilcox Co., The, 1542 BURNERS, Gas (See Gas Burners) Orr A Sembower, Inc., 1562 Bryan Steam Corp., 1543 Pacific Steel Boiler Div., National- Burnham Corp.,1526-1527 . BURNERS, Oil (See Oil Burner*) U. S. Radiator Corp., 1534-1535 Combustion Engineering, Inc., CALKING, Building Preferred Utilities Mfg. Corp., 1566 1548-1549 Philip Carey Mfg. Co., The, 1656 Frank Prox Co., Inc., 1536 International Boiler Works Co., The, 1657 H. B. Smith Co., Inc., The, 1537 1556 . Spencer Heater, Lycoming Div., Avco Mfg.. Corn, 1538-1539 Titusville Iron Works Co., The, (Div. of Struthers-Wells Corp.), 1564-1565 -. Vapor Heating Corp., 1567 . Raypak Co., Inc., 1563 H. B. Smith Co., Inc., The, 1537 . Titusville Iron Works- Co.,' The (Div. of Struthers-Wells Corp:), 1564-1565 CAPS, Vent Flue G. C. Breidert Co., The, 1416 Metalbestos Div., William Wallace Co., 1592-1593 Penn Ventilator Co., 1422 Weil-McLain Co., 1540 BRACKETS, Radiator CARBON, Activated York-Shipley, Inc., 1590 American Radiator A Standard Charles E. Manning Co., 1335 BOILERS, Steel Sanitary Corp., (Plumbing A Pur Air Div., Bamebey-Cheney Heating Div.), 1523-1525 Co., 1322-1323 Aldrich Co., 1541 National-U. S. Radiator Corp., Bryan Steam Corp., 1543 1530-1533 CASTINGS, Bronze and Nickel Burnham Corp., 1526-1527 -- Metal Cleaver-Brooks Co., 1544, 1580 BREECHINGS Arthur Harris A Co., 1512 Columbia Boiler Co., 1546-1547 Pennsylvania Furnace A Iron Co., Combustion Engineering, Inc., 1548-- 1258 CEILING. Diffusers 1549 Air-Factors, Inc., 1433 Cyclothenn Div., of National-U. S. Radiator Corp., 1545 Dewey-Shepara Boiler Co., 1550 Dutton Boilers, Div. Hapman- Dutton Co., 1551 Farrar A Trefts Div., Adsco In dustries, Inc., 1554 . BURNER PROTECTION, Gas. Airfan Engineering Co., 1343 and Oil Burgess-Manning Co., 1438 . Combustion Control Div., Elec Pyle-National Co., The, Multi tronics Corp. of America, 1475 Vent Div., 1454-1455 Merooid Corp., The, 1489 Penn Controls, Inc., 1494 CEILING, Panels Burgess-Manning Co., 1438 Fitzgibbons Boiler Co., Inc., 1552 1553 General Automatic Products Co., 1513 . International Boiler Works Co., The, 1556 S. T. Johnson Co., 1582-1583 - Johnston Bros., Inc., 1557 Kewanee Boiler Div. of American- Standard, 1558-1561 National-U. S. Radiator Corp., 1530 1533 . Orr A Sembower, Inc., 1562 Pacific Steel Boiler Div., National- U. S. Radiator Corp., 1534-1535 Rheem Mfg. Co., 1260-1261 Spencer Heater, Lycoming Div.-, Avco Mfg. Corp., 1538-1539 Titusville Iron Works Co., The, (Div. of Struthers-Wells Corp.), 1564-1565 BURNERS, Automatic Aldrich Co., 1541 Cleaver-Brooks Co., 1544, 1580 Columbia Boiler Co., 1546-1547 Dewey-Shepard Boiler Co., 1550 Eddington Metal Specialty Co., 1591 Enterprise Engine A Machinery Co., Burner Div., Sub. of General - Metals Corp., 1581 Gordon-Piatt, Inc., 1576 S. T. Johnson Co., 1582-1583 Norman Products Co., 1257 Ray Oil Burner Co., 1584-1585 Rayfield-Staffco Burner Co., 1586 Roberts-Gordon Appliance Corp., 1577 Sonner Burner Co., The, 1578 Webster Engineering Co., The, 1579 York-Shipley, Inc., 1590 John Zink Co., 1588-1589 Lima Register Co.,1450-1451 Standard Stamping A Perforating Co., 1456 .Tectum Div., Peoples Research A Mfg. Co.^1676 CELLULAR GLASS INSULA* TION. (See Insulation, Cellular Glass) CEMENT, Asbestos Philip Carey Mfg. Co., The, 1656 1657 . ' CEMENT, Insulating Armstrong Cork Co., 1665 Philip Carey Mfg. Co., The, 1656 1657 Johns-Manville, 1670-1671 Z-Crete Div., Zonolite Co., 1653 York-Shipley, Inc., 1590 BOILERS, Unit Steam Gener ator '. Airfan Engineering Co., 1343 - Cleaver-Brooks Co., 1544, 1580 Columbia Boiler Co., 1546-1547 - Combustion Engineering, Inc., 1548- BURNERS, Combination for Natural and LP Gases Gordon-Piatt, Inc., 1576 Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 Siemon Mfg. Co., 1587 Sonner Burner Co., The, 1578 John Zink Co.. 1588-1589 CEMENT, Mineral Wool Philip Carey Mfg. Co., The, 1656 1657 .. CEMENT, Refractory (See Re fractories) CHILL RINGS (See Rings, ChiR) Cyclotherm Div. of National-U. S. Radiator Corp., 1545 Dutton Boilers, Division HapmanDutton Co., 1551 Farrar A Trefts Div., Adsco In dustries Inc., 1554 International Boiler Works Co., The, 1556 Johnston Bros., Inc., 1557 Kewanee Boiler Div. of American- Standard, 1558-1561 Orr A Sembower, Inc., 1562 BURNERS, Combination Gas and Oil Babcock A Wilcox Co., The, 1542 Cleaver-Brooks Co., 1544, 1580 Enterprise Engine A Machinery Co., Burner Div., Sub. of General Metals Corp., 1581 Gordon-Piatt, Inc., 1576 S. T. Johnson Co., 1582-1583 Norman Products Co., 1257 Orr A Sembower, Inc., 1562 . . CHILLERS. Water Packaged Drayer-Hanson Div. of National- U. S. Radiator Corp., 1229 CHIMNEY TOPS G. C. Breidert Co., The, 1416 Penn Ventilator Co., 1422 . CHIMNEYS. Liner Pipe . Metalbestos Div., William Wallace Co., 1592-1593 - . Please mention THE GUIDE 1956 when writing to Advertisers 1192 1956 Guide CIRCULATORS, Hot Water Heating Bell A Gossett Co., 1598-1599 - Chicago Pump Co., 1606-1607 ' Crane Co., 1528-1529 - Domestic Pump A Mfg. Corp., 1605 C. A. Dunham Co., 1618-1621 Hoffman Specialty Mfg. Corp., 1622 1625 Kmi'ssl Co., Inc., The, 1610 Jas. P. Marsh Corp., 1628-1629 Minneapolis-Honeywell Regulator Co., 1490-1491 H A. Thrush A Co., 1600-1601 Trane Co., The, 1298-1301 CLEANERS, Air (See Air Cleaning D. J. Murray Mfg. Co., -1292 John J. Nesbitt, Inc., 1293-1295 New York Blower Co., The, 1399 Niagara Blower Co.t 1235 Rome-Turney Radiator Co., The, 1365 Trane Co., The, 1298-1301 Westinghouse Electric Corp., Stur- tevant Div., 1410 Young Radiator Co., 1304 COILS. Brass Arthur Harris A Co., 1512 Mario Coil Co., 1355 McQuay, Inc., 1288-1289 Trane Co., The, 1298-1301 . Patterson-Kelley Co., Inc., The;. 1363 Trane Co., The, 1298-1301 . COILS, Tank General Fittings Co., 1596 - Patterson-Kelley Co., Inc., The, 1363 - Western Blower Co'., 1409 COLLECTORS, Fly Ash American Air Filter Co., Inc., 1319-- 1321 American Blower Corp., 1220-1221 V. D. Anderson Co., The, 1612-1613 Detroit Stoker Co., 156o . Prat-Daniel Corp., 1284 Equipment) . COILS, Cooling COMPENSATORS, Expansion CLEANERS. Flue (See Flue Clean- Aerofin Corp., 1359-1361 ' Airtemp Div., Chrysler Corp., 1248 Flexonics Corp., 1507 era) ' COAL BURNERS (See Burners, Automatic) -' COATINGS Armstrong Cork Co., 1665 , Miracle Adhesives Corp., 1654 1249 American Blower Corp., 1220-1221 Burgess-Manning Co., 1438 ` Drayer-Hanson, Inc., Div. of Na- tional-U. S. Radiator Corp., 1229 Fluor Corp., Ltd., The, 1347 Frick Co., 1371 G A O Mfg. Co., The, 1362 COMPOUNDS, Bolter Heller Laboratories, Inc., 1352 Packard Water Conditioner Div., Packard Mfg. Co., 1575 . ` COMPRESSOR MOTORS (See Motors, Electric) Governair Corp., 1232 COMPRESSOR TUBING, Flex COATINGS, Protective Halstead A Mitchell, 1350-1351 ible (See Tubing, Flexible Metallic) Philip Carey Mfg. Co., The, 1656 Arthur Harris A Co., 1512 1657 Hastings Air Conditioning Co., Inc., COMPRESSORS. Air ltfirftftlft Adhesives Corp., 1654 1233 ' American Blower Corp., 1220-1221 Kennard Corp., 1234 Binks Mfg. Co., 1344-1345 COILS, Aluminum. Aerofin Corp., 1359-1361 ' Drayer-Hanson, Inc., Div. of Na- tional-U. S. Radiator Corp., 1229 John J. Nesbitt, Inc., 1293-1295 Niagara Blower Co., 1235 Patterson-Kelley Co., Inc.', The, 1363 . v Rome-Turney Radiator Co., The, Mario Coil Co.. 1355 Brunner Mfg. Co., 1368 . McQuay, Inc., 1288-1289 Curtis Mfg. Co., Refrigeration Div., Modine Mfg. Co., 1290-1291 1370 . D. J. Murray Mfg. Co., 1292 Johnson Servioe-Co., 1484-1485 John J. Nesbitt, Inc., 1293-12!995 Joy Mfg. Co., 1394-1395 New York Blower Co., The, *139* 9 Minneapolis-Honeywell Regulator Niagara Blower Co., 1235 Co., 1490-1491 Patterson-Kelley Co., Inc., The, Nash Engineering Co., 1608-1609 1363 Worthington Corp*. 1241 Refrigeration Appliances, Inc., 1259 1365 Trane Co., The, 1298-1301 Westinghouse Electric Corp., Stur- tevant Div., 1410 ' Worthington Corp., 1241 Refrigeration Engineering, - Inc., COMPRESSORS, Refrigeration 1373 Airtemp Div., Chrysler.Corp., 1248 Rome-Turney Radiator Co., The, 1249 . 1365 Brunner Mfg. Corp., 1368 Trane Co., The, 1298-1301 Carrier Corp., 1226-1227 Westinghouse Electric Corp., Stur- Copeland Refrigeration Corp., 1369 COILS, Ammonia tevant Div., 1410 Curtis Mfg. Co., Refrigeration Div., Acme Industries, Inc., 1358 Worthington Corp., 1241 1370 Aerofin Corp., 1359-1361 . York Corp., 1242 Frick Co., 1371 Drayer-Hanson, Inc., Div. of Na- Young Radiator Co., 1304 Trane Co., The, 1298-1301 tional-U. S. Radiator Corp., 1229 Worthington Corp., 1241 . Mario Coil Co., 1355 COILS. Pipe, Copper York Corp., 1242 . McQuay, Inc., 1288-1289 Arthur Harris A Co., 1512 ` Modine Mfg. Co., 1290-1291 Kritzer Radiant Coils, Inc., 1514 CONCRETE INSERTS (See In Niagara Blower Co., 1235 Patterson-Kelley. Co., Inc., The, Niagara Blower Co., 1235 Refrigeration Engineering, Inc., 1373 serts, Concrete) 1363 . '. Refrigeration Appliances, Inc., 1259 York Corp., 1242 CONCRETE SLAB HEATING (See Slab, Heating Concrete) Refrigeration Engineering, Inc., 1373 Trane Co., The, 1298-1301 Worthington Corp., 1241 York Corp., 1242 COILS, Blast COILS, Pipe, Iron Acme Industries, Inc., 1358 . Bayley Blower Co., 1370 .. . Kritzer Radiant Coils, Inc., 1514 " Niagara Blower Co., 1235 .. Refrigeration Engineering, Inc., 1373 CONDENSERS and EVAPORA TORS Acme Industries, Inc., 1358 Addison Products Co., 1243 . American Blower Corp., 1220-1221 American District Steam . Div., Aerofin Corp., 1359-1361 American Blower Corp., 1220-1221 Bayley Blower Co., 1376 G & O Mfg. Co., The, 1362 Governair Corp.,1232 Halstead A Mitchell, 1350-1351 Hastings Air Conditioning Co., Inc., 1233 Industrial Engineering A Equip COILS, Pipe and Tube, NonFerrous Killebrew Engineering Corp., 1597 McQuay, Inc., 1288-1289 Niagara Blower Co., 1235 ' Patterson-Kelley Co., Inc., The, 1363 Refrigeration Engineering, Inc., 1373 Rome-Turney Radiator Co.; The, AdsCo Industries, Inc., 1505, 1594 Baltimore Aircoil Co.. Inc., 1346 Bell A Gossett Co., 1598-1599 Buffalo Forge Co., 1382 Carrier Corp., 1226-1227 Curtis Mfg. Co., Refrigeration Div., 1370 Drayer-Hanson, Inc., Div. of Na- tional-U. S. Radiator Corp., 1229 ment Co., 1306 1365 ' Fedders-Quigan Corp., 1286 Kennard Corp., 1234 Frick Co., 1371 Mario Coil Co., 1355 COILS, Stainless Steel G A O Mfg. Co., The, 1362 McQuay, Inc., 1288-1289 Arthur Harris A Co., 1512 Governair Corp., 1232 Modine Mfg. Co., 1290-1291 Niagara Blower Co., 1235 Halstead A Mitchell, 1350-1351 Numerals following Manufacturers* Names refer to pages In the Catalog Data Section Index to Modern Equipment 1193 Kennard Corp., 1234 Killebrew Engineering Corp., 1597 McDonnell A Miller, Inc., 1570-1573 Electromode Corp., 1305 Mereoid Corp., The, 1483 Industrial Engineering A Equip Mario Coil Co., 1355 McQuay, Inc., 1288-1289 Niagara Blower Co., 1235 ' - Patterson-Kelley Co., Inc., The, 1363 Refrigeration Appliances Inc., 1259 Refrigeration Engineering, Inc., 1373 Rittling Corp., The, 1364 Rome-Turney Radiator Co., The, 1365 Trane Co., The, 1298-1301 Worthington Corp., 1241 York Corp., 1242 Warren Webster A Co., 1638-1639 CONTROL EQUIPMENT, Air Conditioning, Electric, Com bustion Barber-Colman Co., 1437, 1473 . Combustion Control Div., Elec tronics Corp. of America, 1475 General Controls, 1480-1481 Maxitrol Co., 1488 Mereoid Corp., The, 1489 Milwaukee Gas Specialty Co., 1492 Minneapolis-Honeywell Regulator ment Co., 1306 -. Kritzer Radiant Coils, Ino., 1514 : Modine Mfg. Co., 1290-1291 National-U. S. Radiator Corp., 1530-1533 . John J. Nesbitt, Inc., 1263-1295 . Rittling Corp., The, 1364 Rome-Turney Radiator Co., The, 1365 Shaw-Perkins Mfg. Co., 1515 - . Trane Co., The, 1298-1301 Warren Webster A Co.,1638-1639 Wesix Electric Heater Co., 1307 - Co., 1490-1491 Edwin L. Wiegand Co., 1308-1309 CONDUIT, Non-Ferrous Metal Penn Controls, Inc., 1494 - Young Radiator Co., 1304. American Brass Co., The,1310-1311 Simplex Mfg. Co., 1500 - CONDUIT, Refrigeration (See Hose, Flexible Metal, and Liquid Gas, Vapor) CONDUITS, Underground Fit tings . Durant Insulated Pipe Co., 1647 Durant International Corp.; 1647 E. B. Kaiser Co., 1648-1649 National Clay Pipe Mfgrs., The; 1516-1521 H. W. Porter & Co., Inc., 1650__ Reid Hayden Inc., 1650 ' Ric-wiL Inc., 1651 Stillwater Clay Products Co., The, 1652 ' CONDUITS, Underground Pipe Durant Insulated Pipe, 1647- Durant International Corp., 1647 E. B. Kaiser Co., 1648-1649 National Clay Pipe Mfgrs., The, 1516-1521 H. W. Porter A Co., Inc., 1650 Reid Hayden Inc., 1650 . Ric-wiL, Inc., 1651 Stillwater Clay Products Co., The, 1652 Z-Crete Div., Zonolite Co., 1653 CONNECTORS, FLEXIBLE Webster Engineering Co., The, 1579 White-Rodgers Electric Co., 1504 CONVECTORS AND CONVEC TOR ENCLOSURES CONTROL EQUIPMENT, Time April Showers, Inc., 1644 Barber-Colman Co., 1437, 1473 . Minneapolis-Honeywell Regulator Co., 1490-1491 Penn Controls, Inc., 1494 Acme Industries, Inc., 1358 Airtherm Mfg. Co., 1522 - r American Radiator A Standard Sanitary Corp., (Plumbing A Heating Div.), 1523-1525 Crane Co., 1528-1529 C. A. Dunham Co., 1618-1621 CONTROLLERS AND CON TROL EQUIPMENT, ELEC TRIC. (See Humidity and Tem perature Control) ' Alco Valve Co., 1472 ' American Moistening Co., 1222 Barber-Colman Co., 1437, 1473 Heller Laboratories, Inc., 1352 . Minneapolis-Honeywell Regulator Co., 1490-1491 Penh Controls, Inc., 1494 Fedders-Quigan Corp., 1286 . GAO Mfg. Co., The, 1362 Kritzer Radiant Coils, Inc., 1514 ' Louvra Mfg. A Sales Co., 1452 Modine Mfg. Co., 1290^1291 - ' . National-U. S. Radiator Corp., 1530-1533 . Herman Nelson, American Air Filter Co., Inc., 1296-1297 Pacific Steel Boiler Div., National- U. S. Radiator Corp., 1534-1535 Rittling Corp., The, 1364 CONTROLLERS, Pump A. W. Cash Co., 1617 C. A. Dunham Co., 1618-1621 Hoffman-Specialty Mfg. Corp., 1622 1625 ' Hubbell Corp., 1483 - Illinois Engineering Co., 1226-1227 Leslie Co., 1487 Jas. P. Marsh Corp., 1628-1629 McDonnell A MUler, Inc., 1570-1573 Shaw-Perkins Mfg. Co., 1515 Slant-Fin Radiator Corp., 1366 . Somers Corp., 1339 . Standard Stamping A Perforating Co., 1456 - Trane Co., The, 1298-1301 Tuttle A Bailey, Inc., 1480-1461 Union Asbestos A Rubber Co., 1265 Vulcan Radiator Co., The, 1367 Warren Webster A Co., 1638-1639 Wiremold Co., The, 1469 Mereoid Corp., The, 1489 . CONTROL, ACOUSTICAL Acoustical Control) . (See Penn Controls, Inc., 1494 Powers Regulator Co., The, 1496-? 1493 COOLERS EVAPORATIVE (See Evaporative Coolers) CONTROL, Air Volume Damper Sarcotherm Controls, Inc., 1633 AJ. Mfg. Co., 1426-1427 Simplex Mfg. Co., 1500 COOLING EQUIPMENT. Air Addison Products Co., 1243 Air A Refrigeration Corp., 1219 Air Control Products, Inc., 1428-1431 Air Devices, Inc., 1316,1432 Air-Factore, Inc., 1433 > Sterling, Inc., 1502 Taylor Instrument Cos., 1503 Wesix Electric Heater Co., 1307 White-Rodgera Electric Co., 1504 Aerofin Corp., 1359-1361 ' Airtemp Div., Chrysler Corp., 1248 1249 . American Blower Corp., 1220-1221 Anemostat Corp. of America, 1434 1435 Barber-Colman Co., 1437, 1473 Duro-Dyne Corp., 1466-1467 CONTROLS, Combustion, Auto- matlc Air for Stokers WiU-Burt Co., The, 1569 . American Moistening Co., 1222' American-Standard, Air Condition ing Div., 1244-1245 April Showers, Inc., 1644 Eigen Mfg. Corp., 1468 General Register Corp., 1442-1443 Hart A Cooley Mfg. Co., 1444-1445 Armstrong Furnace Co., 1246-1247 CONTROLS, Liquid Level (See Bell A Gossett Co., 1598-1599 ' Liquid Level Controls) Brunner Mfg. Co., 1368 Johnson Service Co., 1484-1485 Lima Register Co., 1450-1451 Buensod-Staoey, Inc., 1224 CONTROLS, Motor (See Motor Buffalo Forge Co., 1382 Louvra Mfg. A Sales Co., 1452 Controls) Carrier Corp., 1226-1227 Minneapolis-Honeywell Regulator Co., 1490-1491 Powers Regulator Co., The, 1496 1498 ` Register A Grille Mfg. Co., 1453 Standard Stamping A Perforating Co., 1456 CONTROLS, Water Level Heller Laboratories. Inc., 1352 Leslie Co., 1487 Maid-O'-Mist, Inc., 1630-1632 McDonnell A Miller, Inc., 1570-1573 Mereoid Corp., The, 1489 Clarage Fan Co., 1225,1387 Copeland Refrigeration Corp., 1369 Curtis Mfg. Co., 1370 . DeBothezat Fans Div.; American Machine A Metals, Inc., 1388-1389 Drayer-Hanson, Inc., Div. of Na tional-U. S. Radiator Corp., 1229 Titus Mfg. Co.,' 1458-1459 Farr Co., 1332-1333 Waterloo Register Co., 1465 CONVECTION HEATERS General Automatic Products Co., Young Regulator Co., 1470-1471 Airtherm Mfg. Co., 1522 1513 American Radiator A Standard General Electric Co., 1230 . CONTROL, Boiler Water Level Sanitary Corp., (Plumbing A Halstead A Mitchell. 1350-1351 Leslie Co., 1487 Heating Div.), 1523-1525 Hydraline Products, Div. Borg- Maid-O'-Mist, Inc., 1630-1632 C. A. Dunham Co., 1618-1621 Wamer Corp., 1251 ' Please mention THE GUIDE 1956 when writing to Advertisers 1194 1956 Guide Joy Mfg. Co., 1394-1395 Kennard Corp., 1234 Mario Coil Co.. 1355 . McQuay.Inc., 1288-1289 McQuay, Inc., 1288-1289 CORROSION, Treatment of Modine Mfg. Co., 1290-1291 American Gilsonite Co., 1646 Niagara Blower Co., 1235 _ Durant Insulated Pipe Co., 1647_ Packard Water Conditioner Div.,' Durant International Corp., 1647 Mueller Climatrol, Div. of Worthing Packard Mfg. Co., 1575 ton Corp., 1254-1255 . Patterson-Kelley Co., Inc., The, D. J. Murray Mfg. Co., 1292 1363 Niagara Blower Co., 1235 Pennsylvania Furnace A Iron Co., Parts-Cramer Co., 1236-1237 1258 Pennsylvania Furnace & Iron Co. Phillips Cooling Tower Co., Inc., 1258 1356 Ready-Power Co., The, 1372 - Ready-Power Co., The, 1372 Refrigeration Appliances, Inc., 1259 Refrigeration Appliances, Inc., 1259 Refrigeration Engineering, Inc., Refrigeration Engineering, Inc., Heller Laboratories, Inc., 1352 E. B. Kaiser Co., 1648-1649 Owens-Coming Fiberglas Corp., 1658 . Packard Water Conditioner Div., Packard Mfg. Co., 1575 Ric-wiL, Inc., 1651 COUPLINGS Aeroquip Corp., 1312 ' 1373 Rheem Mfg. Co., 1260-1261 Rittling Corp., 1364 Servelilnc., 1262-1263 Trane Co., The, 1298^1301 . 1373 Rome-Turney Radiator Co., 1365 Servel, Inc., 1262-1263 Taco Heaters, Inc., 1602 . Trane Co., The, 1298-1301 Westinghouse Electric Corp., Air Worthington Carp., 1241 Conditioning Div.. 1240 York Corp.. 1242 Westinghouse Electric Corp., Stur- Young Radiator Co., 1304 tevant Div., 1410 Worthington Corp., 1241 York Corp., 1242 COOLING TOWER FANS Aerovent Fan Co., Inc., 1374 COVERING. Pipe and Surface American Gilsonite Co., 1646 ; Philip Carey Mfg. Co., The, 1656 1657 Durant Insulated Pipe Co., 1647 Durant International Corp., 1647 ' Infra Insulation, Inc., 1679 . . Johns-Manville, 1670-1671 E. B. Kaiser Co., 1648-1649 Kimberly Clark Corp., 1672-1673 Lockport Mills, Inc., 1674 Binks Mfg. Co., 1344-1345 COOLING EQUIPMENT, Oil Clarage Fan Co., 1225, 1387 ' - Acme Industries, Inc., 1358 . - ~ Fluor Corp., Ltd., The, 1347 Aerofin Corp., 1359-1361 ' _ Hartzell Propeller Fan Co., Div. of American District Steam Div., Castle Hills Corp., 1392 Adsoo Industries, Inc., 1505,-1594. Joy Mfg. Co., 1394-1395 Bell A Grossett Co.. 1598-1599 Lau Blower Co., The, 1396-1397 Binks Mfg. Co., 1344-1345 Lilie-Hoffmann Cooling Towers, Brunner Mfg. Co., 1368 - Inc., 1353 Marley Co., The, 1354 Marley Co., The, 1354 Niagara Blower Co., 1235 Morrison Products, Inc., 1398 Miracle Adhesives, Inc., 1654 Owens-Coming Fiberglas Corp., 1658 . ^ Owens-Illinois, 1661 Pittsburgh Corning Corp., 1662 . H. W. Porter A Co., Inc., 1650 Reflects! Corp., 1682 Reid Hayden, Inc., 1650 Ric-wiL, Inc., 1651 Z-Crete Div., Zonolite Co., 1653 Patterson-Kelley Co., Inc., The, Utility Fan Corp., 1264 CUT-OFFS, Low Water 1363 . L. J. Wing Mfg. Co., 1302-1303 Refrigeration Engineering, Inc., Barber-Colman Co., 1437, 1473 General Controls, 1480-1481 - 1373 Sterling, Inc., 1502 Taco Heaters, Inc., 1602 Trane Co., The, 1298-1301 Worthington Corp., 1241 Young Radiator Co., 1304 COOLING EQUIPMENT, Water (See also Water Cooling) * Acme Industries, Inc., 1358 - Addison Products Co., 1243 Aerofin Corp., 1359-1361 . V Airtemp Div., Chrysler Corp., 1248-1249 American District Steam Div., ' Adsco Industries, Inc., 1505, 1594 American Radiator A Standard Sanitary Corp., (Plumbing A Heating Div.), 1523-1525 . BeU A Gossett Co., 1598-1599 Binks Mfg. Coa 1344-1345 Brunner Mfg. Co., 1368 . Carrier Corp., 1226-1227 Copeland Refrigeration Corp., 1369 Curtis Mfg. Co., Refrigeration Div., 1370 Drayer-Hanson, Inc., Div. of Na- tional-U. S. Radiator Corp., 1229 C. A. Dunham Co., 1618-1621 Fluor Corp., Ltd., The, 1347 Frick Co., 1371 General Electric Co., 1230 " " E. D. Goodfellow Co., Inc., 1348 Govemair Corp., 1232 Halstead A Mitchell, 1350-1351 Hastings Air Conditioning Co., Inc., 1233 Havens Structural Steel Co., 1349 COOLING TOWERS, Atmos pheric, Mechanical Draft, Forced Draft, Induced Draft (See also Coding Equipment, Water) Acme Industries, Inc., 1358 Air A Refrigeration Corp., 1219 Airtemp Div., Chrysler Corp., Maid-O'-Mist, Inc., 1630-1632 McDonnell A Miller, Inc., 1570-1573 Merooid Corp., The, 1489 Minneapolis-Honeywell Regulator Co., 1490-1491 National-U. S. Radiator Corp.; 1530-1533 Warren Webster A Co., 1638-1639 1248-1249 American Blower Corp., 1220-1221 Baltimore Aircoil Co., Inc., 1346 DAMPER QUADRANTS Quadrants, Damper) (See Binks Mfg. Co., 1344-1345 Buensod-Stacey, Inc., 1224 Carrier Corp., 1226-1227 Curtis Mfg. Co., Refrigeration Div., 1370 . Drayer-Hanson, Inc., Div. of National-U. S. Radiator Corp., 1229 Fluor Corp., Ltd., The, 1347 E. D. Goodfellow Co., Inc., 1348 Governair Corp., 1232 Halstead A Mitchell, 1350-1351 Havens Structural Steel Co., 1349 Kennard Corp., 1234 Lilie-Hoffmann Cooling Towers, Inc., 1353 Marley Co., The, 1354 Mario Coil Co., 1355 DAMPER REGULATOR SETS: Barber-Colxnan Co., 1437, 1473 Duro-Dyne Corp., 1466-1467 Eigen Mfg. Corp., 1468 Field Control Div. of H. D. Conkey A Co., 1477 Hart A Cooley Mfg. Co., 1444-1445 Mercoid Corp., The, 1489 ` ' . Minneapolis-Honeywell Regulator Co., 1490-1491 National-U. S. Rradiator Corp., 1530-1533 Penn Controls, Inc., 1494 # Standard Stamping A Perforating Co., 1456 Tuttle A Bailey, Inc., 1460-1461 Young Regulator Co., 1470-1471 . McQuay, Inc., 1288-1289 D. J. Murray Mfg. Co., 1292 Phillips Cooling Tower Co., Inc., 1356 Refrigeration Appliances, Inc., 1259 Refrigeration Engineering, Inc., 1373 DAMPER REGULATORS. Boiler (See Regulators) . Penn Controls, Inc., 1494 Preferred Utilities Mfg. Corp., 1566 Simplex Mfg. Co., 1500 Spence Engineering Co., Inc., 1501 Servel, Inc., 1262-1263 DAMPER REGULATORS. Fur Heller Laboratories, Inc., 1352 nace Kennard Corp.? 1231 . CORK PRODUCTS (See Insula A. W. Cash Co., 1617 Killebrew Engineering Corp., 1597 tion) Duro-Dyne Corp., 1466-1467 Lilie-Hoffmann Cooling Towers, Armstrong Cork Co., 1665 Field Control Div. of H. D. Conkey Inc., 1353 Marley Co., The, 1354 Korfund Co., Inc., The, 1687 Vibration Mountings, Inc., 1688 A Co.. 1477 Hart A Cooley Mfg. Co., 1444-1445 Numerals following Manufacturers' Names refer to pages In the Catalog Data Section Index to Modern Equipment 1195 Mercoid Corp., The, 1489 ' DEHUMIDIFIERS Trane Co.. The, 1298-1301 . . Minneapolis-Honeywell Regulator Addison Products Co., 1243 Edwin L. Wiegand Co., 1308-1309 Co., 1490-1491 Air & Refrigeration Corp.,-1219 Penn Controls,; Inc., 1494 . Airtemp Div., Chrysler Corp., DUAL DUCT SYSTEMS Simplex Mfg. Co., 1500 1248-1249 Buensod-Stacey, Inc., 1224 . United States Register Co., 1462 American Blower Corp., 1220-1221 . 1463 Young Regulator Co., 1470-1471 Bahnson Co., The, 1223 Bayley Blower Co., 1376 - DUCT AND FITTINGS : : ' Lamneck Div., Clayton A Lambert Buensod-Stacey, Inc., 1224 Mfg. Co., 1256 ... DAMPERS, Air Volume Control Buffalo Forge Co., 1382 Air Control Products, Inc., 1428 Carrier Corp., 1226-1227 ' DUCT CONNECTORS, Pre 1431 . Clarage Fan Co., 1225, 1387 ' fabricated Air Devices. Inc., 1316, 1432 - . Desomatic Products, Inc., 1228 Duro-Dyne Corp., 1466-1467 Air-Factors, Inc., 1433 Mario Coil Co., 1355 Eigen Mfg. Corp., 1468 American Foundry A Furnace Co., New York Blower Co., The, 1399 1266-1267 . Niagara Blower Co., 1235 ' ' DUCT FABRIC Anemostat Corp. of America, 1434 Parks-Cramer Co., 1236-1237 Duro-Dyne Corp., 1466-1467 - . 1435 Pittsburgh Lectrodiyer Corp., 1238 Auer Register Co., 1436 Refrigeration Engineering, Inc., DUCT FURNACES (See Heaters, Barber-Colinan Co., 1437, 1473 ' 1373 Duct) . . Duro-Dyne Corp., 1460-1467 Trane Co., The, 1298-1301 General Register Corp., 1442-1443 Walton Laboratories, Inc,, 1239 DUCT INSULATION (See In Hart A Cooley Mfg. Co., 1444-1445 Westinghouse Electric Corp., .Stur- sulation, Ducts, Ventilating, Air Johnson Service Co., 1484-1485 tevant Div., 1410 Conditioning) Lima Register Co., 1450-1451 York Corp., 1242 . Minneapolis-Honeywell Regulator DUCTS, AIR CONDITIONING. Co., 1490-1491 DESTROYERS. Soot (See Scot HEATING AND VENTILAT Parks-Cramer Co., 1236-1237 Destroyers) ING, Under Concrete Floor Powers Regulator Co., The, 1490 Slabs '. 1498 DETECTORS, Smoke (See Smoke National Clay Pipe Mfgrs., The; Register A Grille Mfg. Co.-,-1453_ Detectors and Indicators, for Flues 1516-1521 * Rittling Corp., The, 1364 and Ducts) ' Sonoco Products Co., 1659 Titus Mfg. Corp., 1458-1459 Tuttle A Bailey, Inc., 1460-1461 Stillwater Clay Products Co., The, DIFFUSERS, Air (See Air Dif 1652 United States Register Co., 1462 fusers, and Ventilators, Ceiling, 1463 Floor and Wall) DUCTS. FLEXIBLE Vulcan Radiator Co., The, 1367 Wiremold Co., The, 1469 Waterloo Register Co., Inc., 1465 Young Regulator Co., 1470-1471 DIFFUSERS, Celling (See Ceding, Diffusers) . DUCTS, Prefabricated Duro-Dyne Co., 1466-1467 . . DAMPERS, Back Draft (See Dampers, Air Volume Control) DISCS, Removable Composition Fairbanks Co., The, 1641 - Jenkins Bros., 1643 Johns-Manville, 1670-1671 Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 DAMPERS, Mechanical Barber-Colman Co., 1437; 1473 Buensod-Stacey, Inc., 1224 Carrier Corp., 1228-1227 Duro-Dyne Corp., 1466-1467 DISTRICT HEATING (See Cor rosion, Treatment of--Expansion Joints--Insulation, Underground-- Meters, Pipe) - National Clay Pipe Mfgrs., The, 1516-1521 Sonoco Products Co., 1659 United States Register Co., 1462 1463 Eigen Mfg. Corp., 1468 Minneapolis-Honeywell Regulator Co., 1490-1491 Powers Regulator Co., The, 1496 1498 Young Regulator Co., 1470-1471 DISTRICT HEATING, Hightemperature Fluid Systems American Gilsonite Co., 1646 Durant Insulated Pipe Co., 1647 Durant International Corp., 1647 E. B. Kaiser Co., 1648-1649 DUCTS, Ventilating National Clay Pipe Mfgrs., The, 1516-1521 Sonoco Products Co., 1659 DUST COLLECTING EQUIP DAMPERS. Multi-Blade, Hard ware Duro-Dyne Corp., 1466-1467 Eigen Mfg. Corp., 1468 Z-Crete Div., Zonolite Co., 1653 DRAFT APPARATUS (See Blow ers, Forced Draft) ' MENT Air Filter Corp.j 1317 . American Air Filter Co., Inc., 1319 1321 . American Blower Corp., 1220-1221 DEFLECTION GRILLE (See Grilles. Registers and Ornamental Metal Work, also Louvers, Registers) A-J Mfg. Co., 1420-1427 Air Control Products, Inc., 1428 1431 Air-Factors, Inc., 1433 Auer Register Co., The, 1436 DRAFT CONTROL, Barometric Field Control Div. of H. D. Conkey A Co., 1477 General Controls, 1480-1481 National-U. S. Radiator Corp 1530-1533 Simplex Mfg., Co., 1500 Webster Engineering Co., 1579 V. D. Anderson Co., The, 1612-1613 Buffalo Forge Co., 1382 Clarage Fan Co., 1225, 1387 Fan- Co., 1332-1333 General Blower Co., 1391 Thermobloc Div., Prat-Daniel Corp., 1284 Trion, Inc., 1340 Barber-Colman Co., 1437, 1473 General Register Corp., 1442-1443 Hart A Cooley Mfg. Co., 1444-1445 Hendrick Mfg. Co., 1446-1447 Lima Register Co., 1450-1451 DRIERS, Refrigerant Henry Valve Co., 1482 DRYING EQUIPMENT Aerovent Fan Co., Inc., 1374 DUST COLLECTORS. Cloth Type American Air Filter Co., Inc., 1319-1321 Louvra Mfg. A Sales Co., 1452 Air Devices, Inc., 1316, 1432 Register A Grille Mfg. Co., 1453 Buffalo Forge Co., 1382 Standard Stamping A Perforating Campbell Heating Co., 1268-1269 Co., 1456 Dravo Corp., 1272-1273 EJECTORS, Sewage Buffalo Pumps, Inc., 1604 Chicago Pump Co., 1606-1607 Titus Mfg. Corp., 1458-1459 Tuttle A Bailey, Inc., 1460-1461 United States Register Co., 1462 1463 Waterloo Register Co., 1465 Young Regulator Co., 1470-1471 Lau Blower Co., The, 1396-1397 Lee Corp., 1277 Modine Mfg. Co., 1290-1291 National Heater Co., 1280-1281 Niagara Blower Co., 1235 Arthur A. Olson A Co.. 1279 ELECTRICAL RELAYS (See Relays, Electrical and Pneumatic) ELECTROSTATIC AIR CLEAN ERS Air-Maze Corp., 1318 Please mention THE GUIDE 1956 when writing to Advertisers 1196 1956 Guide American Air-Filter Co., Inc., 1319 Joy Mfg. Co., 1394-1395 1321 . . Kewaunee Mfg. Co., 1411 American-Standard, Air Condi Lau Blower Co., The, 1396-1397 tioning Div., 1244-1245 Muckle Mfg. Co., 1421 Dollinger Corp., 1330-1331 John J. Nesbitt, Inc., 1293-1295 Electro-Air Cleaner Co., 1329 New York Blower Co., The, 1399 Trion, Inc., 1340 . Peerless Electric Co., The, 1400 Westinghouse Electric Corp., Stur- Penn Ventilator Co., 1422 tevant Div., 1342 Propellair Div., Robbins & Myers, Inc., 1401 ELECTROSTATIC FILTERS, Reed Unit-Fans, Inc., 1402 Gas Sheldons Engineering Ltd., 1404 Electro-Air Cleaner Co., 1329 Swartwout Co., The, 1423 Trion,.Inc., 1340 Trade Wind Motorfans, Inc., 1405 Trane Co., The, 1298-1301 ELIMINATORS, Air (See Air Westinghouse Electric Corp-. Stur- Eliminators) '. tevant Div., 1342, 1410 L. J. Wing Mfg. Co., 1302-1303 EVAPORATIVE CONDENSERS (See Condensers and Evaporators) EXHAUSTERS, Laboratory EVAPORATIVE COOLERS Fume C. L. Ammerman Co., 1415 Airfan Engineering Co., 1343 - Gallaher Co., The, 1417 Baltimore Aircoil Co., Inc., 1346 Genie-Air, Inc., 1418-1419 Trade-Wind Motorfans, Inc., 1405 1 Muckle Mfg. Co., 1421 E. H. Sheldon Equipment Co., EVAPORATIVE ROOF COOL 1412-1413 ING SYSTEMS April Sbbwere Co., Inc., 1644 Muellermist Irrigation Co., 1645 EXPANSION JOINTS American District Steam Div., Adsco Industries, Inc., 1505, 1594 EVAPORATORS 4 Badger Mfg. Co., 1506 American District Steam Div., Philip Carey Mfg. Co., The, 1656 Acisco Industries, Inc., 1505, 1594 1657 Bell A Gossett Co., 1598-1599 Celotex Corp., The, 1666 Buffalo Forge Co., 1382 DeBothezat Fans Div., American Drayer-Hanson Div. of National- Machine A Metals, Inc., 13S8-1389 U. S. Radiator Corp., 1229 . T. R. Finn A Co., Inc., 1686 Mario Coil Co., 1355 Flexonics Corp., 1507 McQuay, Inc., 1283-1289 Refrigeration Appliances, Inc., 1259 Fulton-Sylphon Div., The Roberfcshaw-Fulton Controls Co., 1478 Refrigeration . Engineering, Inc., 1479 ' 1373 Hoffman Specialty Mfg. Corp., Rome-Tumey Radiator Co., The; 1622-1625 1365 Illinois Engineering Co., 1626-1627 Trane Co., The, 1298-1301 Owens-Corning Fiberglas Corp., Young Radiator Co., 1304 1336, 1658 EXHAUST HEADS (See Heads, Vibration Mountings, Inc., 1688 Warren Webster A Co., 1638-1639 Exhaust) Philip Carey Mfg. Co., The, 1656 1657 Champion Blower A Forge Co., 1385 General Blower Co., 1391 Genie-Air, Inc., 1418-1419 Ilg Electric Ventilating Co., 1287, 1393 Lau Blower Co., The, 1396-1397 Muckle Mfg. Co., 1421 Peerless Electric Co., The, 1400 Reed Unit-Fans, Inc., 1402 Somers Corp., 1339 Trade-Wind Motorfans, Inc.{ 1405 Viking Air Conditioning Div. of The National-U. S. Radiator Corp., 1408 . John Zink Co., 1588-1589 FANS, Axial Flow Aerovent Fan Co., Inc., 1374 Allen Cooler A Ventilator Inc., 1414 American Blower Corp., 1220-1221 C. L. Ammerman Co., 1415 Bronson Fan Mfg. Corp., 1378 Brookside Products Co., Inc., 1379 Buffalo Forge Co., 1382 Century Fan A Ventilator Co., Inc., 1384 Chicago Blower Corp., 1386 DeBothezat Fans Div., American Machine A Metals, Inc., 1388-1389 Gallaher Co., The, 1417 Hartzell Propeller Fan Co., Div. of Castle Hills Corp., 1392 Ilg Electric Ventilating Co., 1287, 1393 Joy Mfg. Co., 1394-1395 Lau Blower Ck>., The, 1396-1397 New York Blower Co., The, 1399 Peerless Electric Co., The, 1400 Penn Ventilator Co., 1422 . Propellair Div., Robbins A Myers, Inc., 1401 Reed Unit-Fans, Inc., 1402 Sheldons Engineering Ltd., 1404 Torrington Mfg. Co., 1406-1407 Trade-Wind Motorfans, Inc., 1405 Westinghouse Electric Corp., Stur- tevant Div., 1410 L. J. Wing Mfg. Co., 1302-1303 EXHAUST TUBING, Flexible (See Tubing, Flexible, Metallic) EXHAUSTERS Aerovent Fan Co., Inc., 1374 Air Devices, Inc., 1316,1432 Airfan Engineering Co., 1343 Aladdin Heating Corp., 1375 '' Allen Cooler A Ventilator, Inc. 1414 American Air Filter Co., Inc., 1310 1321 American Blower Corp., 1220-1221 C. L. Ammerman Co., 1415 ' Bayler Blower Co., 1376 G. C. Breidert Co., 1416 Brookside Products Co., Inc., 1379 Brundage Co., The, 1380-1381 Buffalo Forge Co., 1382 Century Fan A Ventilator Co., 1384 Champion Blower A Forge Co., 1385 Chicago Blower Corp., 1386 Clarage Fan Co., 1225, 1387 DeBothezat Fans Div., American Machine A Metals, Inc., 1388-1389 Gallaher Co., The, 1417 Garden City Fan Co., 1390 General Blower Co., 1391 Genie-Air, Inc., 1418-1419 4 Hartzell Propeller Fan Co., Div. of Castle Hills Corp., 1392 Hirschmann-Pohle Co., Inc., 1420 Ilg Electric Ventilating Co., 1287, 1393 EXPANSION LOOPS Durant Insulated Pipe Co., 1647 Durant International Corp., 1647 E. B. Kaiser Co., 1648-1649 Ric-wiL, Inc., 1651 Z-Crete Div., Zonolite Co., 1653 EXPOSITIONS International Exposition Co., 1636 FABRIC, Duct (See Duet Fabricj FAN BLADE HUBS .. Alan E. Burden Co.,* Inc., 1383 FAN BLADES Bronson Fan Mfg. Corp., 1378 Brookside Products Co., Inc., 1379 Alan E. Burden Co., Inc., 1383 Century Fan A Ventilator Co., 1384 Torrington Mfg. Co., The, 1408-1407 FAN MOTORS (See Motors, Elec tric) FAN STACKS Dutton Boilers, Division Hapman- Dutton Co., 1551 FANS, Attic Allen.Cooler A Ventilator Inc., 1414 American Blower Corp., 1220-1221 Buffalo Forge Co., 1382 FANS, Centrifugal Aerovent Fan Co., Inc., 1374 Air Fan Engineering Co., 1343 Aladdin Heating Corp., 1375 American Blower Corp., 1220-1221 Bayley Blower Co., 1376 Bishop A Babcock Mfg. Co., The, (Massachusetts Blower Div.),1377 Brookside Products Co., Inc., 1379 Brundage Co., The, 1380-1381 Buffalo Forge Co., 1382 E. K. Campbell Co., 1270 Campbell Heating Co., 1268-1269 Carrier Corp., 1226-1227 Century Fan A Ventilator Co., Inc., 1384 Champion Blower A Forge Co., 1385 Chicago Blower Corp., 1386 Clarage Fan Co.; 1225, 1387 # DeBothezat Fans Div., American Machine A Metals, Inc., 1388-1389 Gallaher Co., The, 1417 Garden City Fan Co., 1390 General Blower Co., 1391 ' Hartzell Propeller Fan Co., Div. of Castle Hills Corp., 1392 Hirschman-Pohle Co., Inc., 1420 Ilg Electric Ventilating Co., 1287, 1393 Morrison Products, Inc., 1398 Muckle Mfg. Co., 1421 Mueller Chmatrol, Div. of Worth ington Corp., 1254-1255 Numerals following Manufacturers* Names refer to pages in the Catalog Data Section Index to Modem Equipment 1197 Herman Nelson, American Air Hartzell Propeller Fan Co., Div. of Hartzell Propter Fan Co Div r.f Filter Lo., Inc., 1296-1297 3 Castle Hills Corp., 1392 Castle Hilln Corn 1392 * * * New York Blower Co., The, 1399 Ilg Electric Ventilating Co., 1287, Hirschman-Pohle Co Inc 1420 Niagara Blower Co., 1235 1393 n Electric Ventilatincr rv'' 1997 Peerless Electric Co., The, 1400 Joy Mfg. Co., 1394-1395 1393 "*** '* * Penn Ventilator Co., 1422. Lau Blower Co., The. 1396-1397 Joy Mfg. Co., 1394-1395 . Revcor, 1403 Propellair Div., Robbins & Myers, Lau Blower Co., 1396-1397 Sheldons Engineering .Ltd., 1404 Inc., 1401 Muckle Mfg Co 1491 Torrington Mfg. Co., The, 1406-1407 Reed Unit-Fans, Inc., 1402 Herman Nelson, American Air Trade-Wind Motorfans, Inc., 1405 Trane Co., The, 1298-1301 Utility Fan Corp., 1264 Western Blower Co., 1409 Westinghouse Electric Corp., Stur- tevant Div., 1410 Torrington Mfg. Co., The, 1406-1407 L. J. Wing Mfg. Co., 1302-1303 FANS Propeller Aerovent Fan Co., Inc., 1374 Allen Cooler A Ventilator Inc., 1414 Filter Co Inc 1296-1297 New Yor*k`*B~low'*er C~o., --The, 1399 Niagara Blower Co., 1235 Peerless Electric Co., The, 1400 Penn Ven__ti_la__to__r_C__o_._, _1_4_2_2 Propellair Div., Robbins A Myers, FANS, Electric American Blower Corp.; 1220-1221 Inc., 1401 . C. L. Ammerman Co., 1415 Reed Unit-Fans, Inc., 1402 Allen Cooler A Ventilator Inc., 1414 Bishop A Babcock Mfg. Co., The, Trane Co., The, 1298-1301 Philip Carey Mfg. Co., The, 1656- (Massachusetts Blower Div.), Utility Fan Corp., 1264 1657 1377 Viking Air Conditioning Div. of Century Fan A Ventilator Co., 1384 Bronson Fan Mfg. Corp., 1378 The National-U. S. Radiator Champion Blower A Forge Co., 1385 Brookside Products Co., Inc., 1379 Corp., 1408 . General Blower Co., 1391 Buffalo Forge Co.. 1382 Westinghouse Electric Corp., Stur- Hirechman-Pohle Co., Inc., 1420 Alan E. Burden Co., Inc., 1383 . tevant Div.. 1410 Ilg Electric Ventilating Co., 1287, Century Fan A Ventilator Co., 1384 k. J* Wing Mfg. Co., 1302-1303 1393 Chicago Blower Corp., 1386 Joy Mfg. Co., 1394-1395 Lau Blower Cvvo-.,, Tghuec,. 1iO39v6iF-1it3f9p7i PPrmonpaellllfatiirr TDlivv., PRoaKbbKiIntiso AAt MMyitesrms, Inc., 1401 Clarage Fan Co., 1225, 1387 DeBothezat lFaanms iDiiivv..,, AAHmICeriIiCcaanu Machine AAt MMaettsallas, TInfca., 1193I8K8L-11?3E89n Gallaher Co., The, 1417 FANS, Attic, etc.)\ Ventilating Axial Flow. (See Fans Centrifugal* Trade-Wind Motorfans, Inc., 1405 General Blower Co., 1391 FEED WATER HEATERS (See Utility Fan Corp., 1264 Hartzell Propeller Fan Co., Div. of Heaters, Feed Water) Viking Air Conditioning Div.. of Castle Hills Corp., 1392 The National-U. S. Radiator Hirschman-Pohle Co., Inc., 1420 FEED WATER REGULATORS , Corp., 1408 Ilg Electric Ventilating Co., 1287, (See Regulators, Feed Water) . 1Western Engineering A Mfg. Co., 1393 . 1424 Lau Blower Co., The, 1396-1397 Westinghouse Electric Corp., Stur- Muckle Mfg. Co., 1491 tevant Div.. 1410 Herman Nelson, American Air L. J. Wing Mfg. Co., 1302-1303 . xtFilte,yr Co., Inc., 1296-1297 New York Blower Co., The, 1399 FEEDERS. Boiler Water Cyclotherm Div. of National-U. S. Radiator Corp., 1545 . Heller Laboratories, Inc., 1352 Maid-O'-Mist, Inc., 1630-1632 FANS Furnace Peerless Electric Co., The, 1400 McDonnell-* Miller, Inc., 1570-1573 Aladdin Heating Corp., 1375 Penn Ventilator Co., 1422 Packard Water Conditioner Div., American Blower Corp., 1220-1221 Pl?peU*?ft,Dlv-' A Myers, Packard Mfg. Co., 1575 Bishop & Babcock Mfg. Co., The, t nj'tT , (Massachusetts Blower Div.), 1377 5eed Un,1f;ans Inc 1402 Brundage Co., The, 1380-1381 Rev<x)r, 1403 Penn Controls, Inc., 1494 Warren Webster * Co., 1638-1639 . Champion Blower & Forge Co.. 1385 Thel FELT, Insulating (See Insulation Clarage Fan Co., 1225, 1387 Trade-Wind Motorfans, 1 nc., 1405 Felt) Joy Mfg. Co., 1394-1395 Trane Co., The, 1298-1301 Morrison Products, Inc., 1398 V&E* Air Conditioning, Div, f FELT> Sound Deadening Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 Utility Fan Corp., 1264 L. J. Wing Mfg. Co., 1302-1303 FANS Induced Draft American Blower Corp., 1220-1221 C. L. Ammerman Co., 1415 Bayley Blower Co., 1376 The National-U. S. Radiator Corp., Western Blower Co., 1409 . Western Engineering A Mfg. Co., 1424 L. J. Wing Mfg. Co., 1302-1303 FANS, Supply and . Exhaust Aerovent Fan Co.. Inc., 1374 Armstrong Cork Co., 1665 Philip Carey Mfg. do.. The, 1656 1657 . L*0*F Glass Fibers, Inc., 1655 Kimberly-Clark Corp., 1672-1673 Lockport Mills, Inc., 1674 Owens-Corning Fiberglas Corp.. 1658 Wood Conversion Co., 1677 Buffalo Forge Co., 1id3e8a2 Air Fa Engineering Co., 1343 Century Fan A Ventilator Co., 1384 Heating Corp., 1375 FIBER INSULATION (See In Champion Blower A Forge Co., 1385 Allen Cooler A Ventilator Inc., 1414 sulation) Chicago Blower Corp., 1388 American Blower Corp., 1220-1221 Clarage Fan Co., 1225, 1387 * k` Ammerman Co 1415 . FILTERS, Air (See Atr Cleaning DeBothezat Fans Div., American Equipment) Machine A Metals, Inc., 1388-1389 Bp*a Mfg. Co., 1344-1345 Air A .-R--e--f-r--ige.r--at.i.on Corp., 1219 Gallaher Co., The, 1417 . Bishop A Babcock Mfg. Co., The Air Devices, Inc., 1316, 1432 Garden City Fan Co . 1390 General Blotter Co., 1391 (Massachusetts Blower Div.), 1377 Air Filter Corp., 1317 Brundage Co., The, 1380-1381 Air-Maze Corp., 1318 Muckle Mfg. Co.. 1421 Bufial Forge Co., 1382 American Air Filter Co., Inc., Pacific Steel Boiler Div., National- Carey ***** P The, 1656- 1319-1321 U. S. Radiator Corp., 1534-1535 ^ , tp . ,, ., _ American Moistening Co., 1222 Sheldons Engineering Ltd, 1404 century * a:n A Ventilator Co., American-Standard, Air Condi- Westingbouse Electric Corp., Stur- TM,, tioning Div., 1244-1245 tevant Div., 1410 Champion Blower A Forge Co., 1385 V. D. Anderson Co., The, 1612-1613 L. J. Wing Mfg. Co., 1302-1303 Chicago Blower Corp., 1386 Oarage Fan Co., 1225, 1387 Cambridge Filter Corp., 1324 Carey Electronic Engineering Co., r.V!e ... DeBothezat Fans Div., American 1325 ' nt Aerovent Fan Co., Inc., 1374 Machine A Metals, Inc., 1388-1389 Continental Air Filters, Inc., 1328 Gallaher Co., The, 1417 Dollinger Corp., 1330-1331 im?p10D Blower A Forge Co., Garden City Fan Co.,1390 Electro-Air Cleaner Co., 1329 General Blower Co., 1391 General Blower Co., 1391 Genie-Air, Inc., 1418-1419 Farr Co., 1332-1333 Goodyear Tire A Rubber Co., 1334 Please mention THE GUIDE 1956 when writing to Advertisers 1198 1956 Guide Muckle Mfg. Co., 1491 . - Owens-Coming Fiberglas Corp., 1336 . Pittsburgh Plate Glass Co., Fiber FITTINGS. Air Conditioning and Warm Air Furnace (See Furnace Pipe and Fittings) _ Mueller Climatrol, Div. of Worthing Taylor Forge A Pipe Works, Inc., 1510 : Tube Turns, A Div. of National Cylinder Gas Co., 1511 : Glass Div., 1337, 1664 . Research Products Corp., 1338 Somers Corp., 1339 ' Trion, Inc., 1340 Vortox Co., 1341 ... ton Corp., 1254-1255 United States Register Co., 1462 FITTINGS. Pipe, Socket-Weld . 1463 ing IAftish Co., 1508 FITTINGS, Hot Water Heating Systems - . - FITTINGS. Pipe, Solder . FILTERS, Air, Continuous, Bell A Gossett Co., 1598-1599 Automatic. . ' C. A. Dunham Co., 1618-1621 American Brass Co., The, 1310-1311 General Fittings Co., 1596 Air-Maze Corp., 1318 ` American Air Filter Co., Inc., 1319 1321 V. D. Anderson Co., The, 1612-1613 Bahnson Co., The, 1223.. Continental Air Filters, Inc., 1328 Dollinger Corp., 1330-1331 Electro-Air Cleaner Co., 1329 Farr Co., 1332-1333 Charles E. Manning Co., 1335 ' Flexonics Corp., 1507 - General Fittings Co/, 1596 . FITTINGS, Pipe, Steel . Hammond Brass Works, 1642 ' ^ - Henry Valve Co., 1482 ` Hoffman Specialty Mfg.. Corp., Ladish Co., 1508 1622-1625 . Robvon Backing Ring Co., The,- Maid-O'-Mist, Inc., 1630-1632 . . 1509 ' . Jas. P. Marsh Corp., 1628-1629 Taylor Forge. A Pipe Works, Inc., National-U. S. Radiator Corp., 1510 ' 1530-1533 . Tube Turns, A Div. of National Packard Water Conditioner Div., Cylinder. Gas Co., 1511. Trion, Inc., 1340 . '. Packard Mfg. Co., 1575 Sareo Co., Inc., 1634-1635 - FITTINGS. Welding FILTERS, Electrostatic Precipi tators ` Air-Maze Corp., 1318 American Air Filter Co., Inc., 1319 A. m13e2r1ican-Standard, A.ir C,,onditi.on ing Div., 1244-1245 Sarcotherm Controls, Inc., 1633 Taco Heaters, Inc., 1602 H. A. Thrush & Co., 1600-1601 Trane Co., The, 1298-1301 Warren Webster & Co., 1638-1639 FITTINGS, Jacketed. Steam and Ladish Co.. 1508 . Robvon Backing Ring Co., The, 1509 Taylor Forge A Pipe Works, Inc., 1510. -. Tube Turns, A Div. of National Cylinder Gas Co., 1511 Dollinger Corp., 1339-1331 : Electro-Air Cleaner Co., 1329 Trion, Inc., 1340 Westinghouse Electric Corp., Stur- tevant Div., 1342 Oil E. B. Kaiser Co., 1648-1649 Parks-Cramer Co., 1236-1237 - FITTINGS, Pipe. Add Resisting FLANGES, Galvanized or NonFerrous Ladish Co., 1508 Simplex Mfg. Co., 1500 FILTERS, Gas Air-Maze Corp., 1318 Ladish Co., 1508 . FLANGES, Lead, Roof National Clay Pipe Mfgrs.j The, Simplex Mfg. Co., 1500 1516-1521 . American Air Filter Co., Inc., 1319-1321 `,, V. D. Anderson Co., The, 1612-1613 Barnebey-Cheney Co., 1322-1323 Cambridge Filter Co., 1324 Connor Engineering Corp., 1326 1327, 1440-1441 Dollinger Corp, 1330-1331 Electro-Air Cleaner Co., 1329 Pur Air Div., Bamebev-Cheney Co., 1322-1323 Trion, Inc., .1340 Stillwater Clay Products Co., The, 1652 Taylor' Forge A Pipe Works, Inc., 1510. FITTINGS. Pipe, Alloy and Stainless, Non-Ferrous Ladish Co., 15G8 . Robvon Backing Ring Co., The, 1509 Taylor Forge A Pipe Works, 1510 Tune Turns, A Div. of National Cylinder Gas Co., 1511 FLANGES, Pipe. Alloy, Stain less, Non-Ferrous Ladish Co., 1508 : - Taylor Forge & Pipe Works, Inc., 1510 . . Tube Turns, A Div. of National Cylinder Gas Co.,.1511 FLANGES, Pipe Blind Ladish Co., 1508 - Taylor Forge A Pipe Works, Inc., 1510 . Tube Turns, A Div.- of National FILTERS, Grease Air Devices, Inc., 1316, 1432 _ Air Filter Corp., 1317 . Air-Maze Corp^ 1318 American Air Filter Co., Inc., 1319 1321 Continental Air Filters, Inc., 1328 Dollinger Corp., 1330-1331 FITTINGS. Pipe, Flanged York Corp., 1242 FITTINGS, Pipe for Under ground Conduit Durant Insulated Pipe Co., 1647 Durant International Corp., 1647 Cylinder Gas Co., 1511 FLANGES. Pipe, Reducing Ladish Co., 1508 Taylor Forge A Pipe Works, Inc., 1510 . Tube Turns, A Div. of National Cylinder Gas Co., 1511 Farr Co., 1332-1333 Research Products Corp., 1338 Trion, Inc., 1340 FILTERS, Liquid Air-Maze Corp., The, 1318 Dollinger Corp., 1330-1331 Eddington Metal Specialty Co., 1591 Kraissl Co., Inc., The, 1610 E. B. Kaiser Co., 1648-1649 National Clay Pipe Mfgrs., The, 1516-1521 H. W. Porter A Co., Inc., 1650 Reid Hayden, Inc., 1650 Ric-wiL, Inc., 1651 Robvon Backing Ring Co., The, 1509 Stillwater Clay Products Co., The, 1652 FLANGES, Pipe, Steel Ladish Co., 1508 Taylor Forge A Pipe Works, Inc., 1510 Tube Turns, A Div. of National Cylinder Gas Co., 1511 FLANGES, Welding Ladish Co., 1508 FILTERS. Odors FITTINGS, Pipe. Galvanized Barnebey-Cheney Co., 1322-1323 E. B. Kaiser Co., 1648-1649 Connor Engineering Corp., 1326-- Ladish Co., 1508 1327, 1440-1441 Taylor Forge A Pipe Works, Inc., 1510 . Tube Turns, A Div. of'National Cylinder Gas Co., 1511 Charles E. Manning Co., 1335 ` FITTINGS, Pipe. Screwed - Pur Air Div., Barneoey-Cheney Ladish Co., 1508 Co., 1322-1323 Research Products Corp., 1338 FITTINGS. Pipe, Seamless Weld FLOATS, Ferrous and Ferrous (Seamless) Arthur Harris A Co., 1512 Non- FIREBRICK, Insulating Babcock A Wilcox Co., The, 1542 Johns-Manville, 1670-1671 ing * Ladish Co., 1508 FLOATS. Welded-Stainless, Mo Robvon Backing Ring Co., The, nel. Plated Steel 1509 1 Arthur Harris A Co., 1512 Numerals following Manufacturers* Names refer to pages In the Catalog Data Section Index to Modern Equipment 119& United States Steel, 1425 . nneem Mlg. Co., 1260-1261 John Zink Co., 1588-1589 . uenerai Automatic rroducte Corp.; FLUES Metalbestofi Div., William Wallace Co., 1592-1593 FURNACES, Oil Burnings, Floor Airtherm Mfg. Coi; 1522 .. Hayes Furnace Mfg. A Supply Co., 1252-1253 Jackson A Church Co., 1276 FOOD SAVERS Barnebey-Cheney Co., 1322-1323 Connor Engineering Corp., 1326 1327, 1440-1441 Pur Air Div., Barnebey-Cheney. Co., 1332-1333 FORCED-AIR DUCTS and FIT TINGS (See Ducts; Fittings) American Foundry A Furnace Co.. 1266-1267 S. T. Johnson Co., 1582-1583 Johnson Heater Corp., 1274rl275 Chicago Steel Furnace Co., 1271 Dravo Corp., 1272-1273 Mueller Climatrol, Div. of Worthing ton Corp., 1254-1255 General 1513 Automatic Products Co.,- National-U. 1530-1533 S. Radiator . Coro.. Jackson A Church Co., 1276 Johnson Heater Corp., 1274-1275 Lee Corp., 1277 . Norman Products Co., 1257 Pennsylvania Furnace A Iron Co.. 1258 Mammoth Furnace Co., The, 1278 Ray Oil Burner Co., 1584-1585 National Heater Co., 1280-1281 FORCED DRAFT COOLING Arthur A. Olson A Co., 1279 TOWERS (See Cooling Towers, Vapor Heating Corp., 1567 Rheem Mfg. Co., 1260-1261 , Roberts-Gordon Appliance Coro.. 1577 Induced Draft, Mechanical Draft) Acme Industries, Inc., 1358 Air A Refrigeration Coro.,1219Airtemp Div., Chrysler Corp., 1248 FURNACES, Suspended Airtemp Div., Chrysler 1248-1249 ' Coro.. Servel, Inc., 1262-1263 York-Shipley, Inc., 1590 John Zink Co., 1588-1589 1249 . Baltimore Aircoil Co., Inc., 1347 Carrier Corp., 1226-1227 ' American-Standard,' Air Condition ing Div., 1244-1245 Armstrong Furnace Co., 1246-1247 GAGES, Altitude . Jas. P. Marsh Corp., 1628-1629 .*' Fluor Corp., Ltd., .The, 1347 Chicago Steel Furnace Co., 1271 ' GAGES, Compound E. D. Goodfellow Co., Inc., 1348 Dravo Corp., 1272-1273 . C. A. Dunham Co., 1618-1621 Kennard Corp., 1234 General Automatic .Products Co.. Jas. P. Marsh Corp., 1628-1629 Lilie-Hoffmann Cooling' Towers. 1513 . Inc., 1353 -- Hayes Furnace Mfg. A Supply Co., GAGES, Liquid Level Marley Co., The, 1354 "1252-1253 * * Scully Signal Co., 1499. Mario Coil Co., 1355 Jackson A Church Co., 1276 ' McQuay, Inc., 1288-1289 Johnson Heater Coro., 1274-1275 GAGES, Pressure Phillips Cooling Tower Co., Inc., Mammoth Furnace Co., The, 1278 C. A. Dunham Co., 1618-1621 ' 1356 ' ; Mueller Climatrol, Div. of Worthing. General Controls, 1489-1481 Refrigeration Engineering, Inc.. ton Corp., 1254-1255 Jas. P. Marsh Corp., 1628-1629 1373 Servel, Inc., 1262-1263 National Heater Co., 1280-1281 Norman Products Co., 1257 Reznor Mfg. Co., 1282-1283 Mercoid Corp., The, 1489 ' Taylor Instrument Cos.,-1503 FUEL BURNING EQUIPMENT, Rbeem Mfg. Co , .1260-1261 GAGES, Steam .- Automatic (See Burners, Auto Vapor Heating Corp., 1567 matic; Gas Burners; Oil Burner*; Wesix Electric Heater Co., 1307 C. A. Dunham Co., 1618-1621 Hoffman Specialty Mfg. Corp., 1622 Stokers) York-Shipley, Inc., 1590 , >) 1625 . Jas. P. Mareh Corp., 1628-1629 FUEL OIL, Heating. Pumping FURNACES, Wall and Straining Units . Rheem Mfg. Co., 1260-1261 GAGES, Tank . " S. T. Johnson Co., 1582-1583 Wesix Electric Heater Co., 1307 Scully Signal Co., 1499 . ' Edwin LI Wiegand Co., 1308-1309 John Zink Co., 458871589 GAGES, Vacuum " FUME DISPOSAL DUCTS, Vitrified Clay National Clay Pipe MfgrB.,. The, 1516-1521 ./ : ' FURNACES, Warm Air, Duty Air Devices, Inc., 1316,1432 Airtherm Mfg. Co., 1522 Aladdin Heating Corp., 1375 Heavy C. A. Dunham Co., 1619-1621 Electric Auto-Lite Co., The Instru ment A Gauge Div., 1476 . Hoffman Specialty Mfg. Corp., . 1622--1625 FUME DISPOSAL UNITS (Hoods) Laboratory ' Kewaunee Mfg. Co., 1411 , E. H. Sheldon Equipment Co.. 1412-1413 ' American Foundry A Furnace Co., 1266-1267 - Armstrong Furnace Co., 1246-1247 E. K. Campbell Co., 1270 ' Campbell Heating Co., 1268-1269 Carrier Corp., 1226-1227 Jas. P. Marsh Corp., 1628-1629 Moeller Instrument Co., 1493 Taylor Instrument Cos., 1503 GAGES, Vapor C. A. Dunham Co., 1818-1621. . FURNACE PIPE AND FIT TINGS Lamneck Div., Clayton A Lambert Mfg. Co., 1256 Mueller Climatrol, Div. of Worthing ton Corp., 1254-1255 United States Register Co., 1462 1463 Chicago Steel Furnace Co., 1271 Dravo Corp., 1272-1273 Hayes Furnace Mfg. A Supply Co., 1252-1253 . Jackson A Church Co., 1276 - Johnson Heater Corp., 1274-1275 Lee Corp., 1277 Mammoth Furnace Co., The, 1278 Mueller Climatrol, Div. of Worth GAS BURNERS Airtemp Div., Chrysler Coro., 1248-1249* .. American Radiator A Standard Sanitary Corp., (Plumbing A Heating Div.), 1523-1525 American-Standard, Air Condition ing Div., 1244-1245 FURNACES, Duct (See Heaters, Duct) FURNACES, Electric Electromode Corp., 1305 Wesix Electric Heater Co., 1307 FURNACES. Gas-Fired. Floor Chicago Steel Furnace Co., 1271 Dravo Corp., 1272-1273 Jackson A Church Co., 1270 Johnson Heater Corp., 1274-1275 Mammoth Furnace Co., The, 1278 ington Corp., 1254-1255 National Heater Co., 1280-1281 Arthur A. Olson A Co., 1279 Ray Oil Burner Co., 1584-1585 Rheem Mfg. Co., 1260-1261 FURNACES, Warm Air. Resi dence Airtemp Div., Chrysler Corp., 1248 1249 _ .. _ Aiaddm Heating Corp., 1375 American-Standard, Air Condition- ing Div., .1.2..4..4..-.1..2..4..5 Armstrong Furnace Co., 1246-1247 A.UrUmWsHtrVo1nMg Fi uUriniUaVcCe CWo., 1246-12*14,7 Babcock A Wilcox Co., The, 1542 Cleaver-Brooks Co., 1544. 1580 Columbia Boiler Co., 1546-1547 Crane Co., 1528-1529 Dewey-Shepard Boiler Co., 1550 Gordon-Piatt, Inc., 1576 . Hastings Air Conditioning Co., Inc.. 1233 Mueller Climatrol, Div. of Worthington Corp., 1254-1255 National-U. 5. Radiator Coro 1539-1533 Norman Products Co., 1257 Please mention THE GUIDE 1956 when writing to Advertisers 1200 1956 Guide Orr A Sembower, Inc.', 1562 Pennsylvania Furnace & Iron Co., '1258 __ Preferred Utilities Mfg. Corp., 1566 Ray Oil Burner Co., 1584-1585 Rayfield-Staffco Burner Co., Inc., 1586 . Roberte-Gordon Appliance Corp., 1577 Siemon Mfg. Co^ 1587 Bonner Burner Co., 1578 Webster Engineering Co., The, 1579 John Zink Co., 1588-1589 GAS FILTERS (See Filters, Gas) GAS SAFETY PILOTS (See Pilots) GAS VENT PIPE or GAS VENTS (See Pipe, Gas Vent) GASKETS. Cork . ., Armstrong Cork Co., (Industrial Div.), 1665 GLASS BLOCK ROOFLIGHTS (See Skylights Insulated). GLASS BLOCKS HANGERS/Radlator American Radiator A Standard Sanitary Corp., (Plumbing & Heating Div.), 1523-1525 T. R. Finn & Co., Inc., 1686 National-U. S. Radiator Corp.; 1530-1533 HEADS. Exhaust V. D. Anderson Co., The, 1612-1613 Muckle Mfg. Co., 1421 HEAT EXCHANGERS Acme Industries, Inc., 1358 Aerco Corp., 1595 Aerofin Corp., 1359-1361 _ American District Steam Div., Adsco Industries, Inc., 1505, 1594 Bell & Gossett Co.. 1598-1599 Binks Mfg. Co., 1344-1345 Fluor Corp., Ltd., The, 1347 General Fittings Co., 1596 Hayes Furnace Mfg. & Supply Co., 1252-1253 Illinois Engineering Co., 1626-1627 International Boiler Works Co., The, 1556 - E. B. Kaiser Co., 1648-1649 Killebrew Engineering Corp., 1597 Marley Co., The, 1354 Combustion Engineering, Inc., 1648 1549 Drevo Corp., 1272-1273 Electromode Corp., 1305 ( Industrial Engineering A Equip ment Co., 1308 Lee Corp., 1277 Mammoth Furnace Co., The, 1278 McQuay, Inc., 1288-1289 Mario Coil Co., 1355 . Modine Mfg. Co., 1290-1291 Mueller Chmatrol, Div. of Worth ington Corp., 1264-1255 National Heater Co., 1280-1281 National-U. S. Radiator Corp., 1530-1533 . . Herman Nelson, American Air Fil ter Co., Inc., 1290-1297 John J. Nesbitt, Inc., 1293-1295. Arthur A. Olson A Co., 1279 Reznor Mfg. Co., 1282-1283 . Thermobloc Div., Prst-Damel Corp., 1284 . Trane Co., The, 1298-1301 Vapor Heating Corp., 1567 Westinghouse Electric Corp., Stur- tevant Div., 1410 .' Edwin L. Wiegand Co., 1308-1309 L. J. Wing Mfg. Co., 1302-1303 John Zink Co., 1588-1589 Owens-Illinois, 1661 ' Pittsburgh Corning Corp., 1662 Mario Coil Co., 1355 McQuay, Inc., 1288-1289 Modine Mfg. Co., 1290-1291 HEATERS, Automatic Hot Wa ter, Domestic GLASS, Cellular Pittsburgh Corning Corp., 1662 National Heater Co., 1280-1281 Airtemp Div., Chrysler Corp., National-U. S. Radiator Corp., 1248-1249 . . jJ 1530-1533 American Radiator A Standard GOVERNORS, Pump John J. Nesbitt, Inc., 1293-1295 Sanitary Corp., (Plumbing A Leslie Co., 1487 Niagara Blower Co., 1235 Heating Div.), 1523-1524 McDonnell & Miller, Ino.j 1570-1573 Patterson-Kelley Co., Inc., The, Bryan Steam Corp., 1543 Spence Engineering Co.,-Inc., 1501 Combustion Engineering, Inc., Warren Webster A Co., 1638-1639 Taco Heaters, Inc., 1602 (Chattanooga Div.), 1250 H. A. Thrush & Co., 1600-1601 Crane Co., 1528-1529 GREASE FILTERS Grease) (See Filters, Trane Co., The, 1289-1301 Western Blower Co., 1409 Westinghouse Electric Corp., Stur- Dewey-Shepard Boiler Co.,'1550 Hydrotherm, Inc., 1555 8. T. Johnson Co., 1582-1583 GRIDS. Panel American Brass Co., The, 1310-1311 tevant Div., 1410 Worthington Corp., 1241 York Corp., 1242 . 1530-1533 Ray Oil Burner Co., 1584-1585 GRILLES, REGISTERS AND ORNAMENTAL METAL York-Shipley, Inc., 1590 Young Radiator Co., 1304 . Rheem Mfg. Co., 1260-1261 . WesLx Electric Heater Co., 1307 WORK (See also Louvers, Regis ters) A-J Mfg. Co., 1428-1427 Air Control Products Inc., 1428-1431 Air-Factors, Inc., 1433 Auer Register Co., The, 1435 Barber-Colman Co., 1437; 1473 Dole Valve Co., The, 1640 General Register Corp., 1442-1443 Hart A Cooley Mfg. Co., 1444-1445 Hendrick Mfg. Co., 1446-1447 Independent Register Co., The, 1448 Lima Register Co., 1450-1451 Louvre Mfg. & Sales Co., 1452 HEAT PUMPS Acme Industries, Inc., 1358 HEAT RECLAIMERS American District Steam Div., Adsco industries, Inc., 1505, 1594 E. B. Kaiser Co., 1648-1649 HEAT SURFACE Aerofin Corp., 1359-1361 G & O Mfg. Co., The, 1362 McQuay, Inc., 1288-1289 Modine Mfg. Co., 1290-1291 HEATERS, Blast Aerofin Corp., 1359-1361 Airtherm Mfg. Co., 1522 Bayley Blower Co., 1376 Carrier Corp., 1226-1227 . Drayer-Hanson, Inc., Div. of Na tional-U. S. Radiator Corp., 1229 Electromode Corp., 1305 G A O Mfg. Co., The, 1362 Hastings Air Conditioning Co., Inc., 1233 . Industrial Engineering A Equip ment Co., 1306 Pyle-National Co., The Multivent Div., 1454-1455 Register A Grille Mfg. Co., Inc., 1453 Standard Stamping & Perforating Co., 1456 Stewart Mfg. Co., Inc., 1457 Titus Mfg. Corp., 1458-1459 Tuttle & Bailey, Inc., 1460-1461 John J. Nesbitt, Inc., 1293-1295 New York Blower Co., 1399, Niagara Blower Co., 1235 Rittling Corp., The, 1364 Rome-Turney Radiator Co., The, 1365 . Warren Webster A Co., 1638-1639 Young Radiator Co., 1304 Mario Coil Co., 1355 - McQuay, Inc., 1288-1289 Modine Mfg. Co., 1290-1291 D. J. Murray Mfg. Co., 1292 . _ Herman Nelson, American Air Filter Co., Inc., 1296-1297. John J. Nesbitt, Inc., 1293-1295 Niagara Blower Co.t 1235 Rome-Turney Radiator Co., The, United States Register Co., 1462 1463 Vulcan Radiator Co., The, 1367 Waterloo Register Co., Inc., 1465 Young Regulator Co., 1470-1471 HEATERS, Air Aerofin Corp., 1359-1361 Air Devices, Inc., 1316, 1432 Airtherm Mfg. Co., 1522 American Foundry & Furnace Co., 1266-1267 1365 Trane Co., The, 1298-1301 . Westinghouse Electric Corp., Stur- tevant Div., 1410 Edwin L. Wiegand Co., 1308-1309 Young Radiator Co., 1304 HANGERS. Pipe T. R. Finn A Co., Inc., 1686 Korfund Co., Inc., The, 1687 Buffalo Forge Co- 1382 E. K. Campbell Co., 1270 Campbell Heating Co., 1268-1269 HEATERS. Cabinet American Blower Corp., 1220-1221" Vibration Mountings, Inc., 1688 Chicago Steel Furnace Co.,*1271 Carrier Corp., 1228-1227 Numerals following Manufacturers' Names refer to pages in the Catalog Data Section Index to Modern Equipment 1201 C. A. Dunham Co., 1618-1621 Eleclruuiodc Corp., 1305 . Modine Mfg. Co., 1290-1291 \ Herman Nelson, American Air Kilter Co., Inc.,-1296-1297 - John J. Nesbitt. Inc., 1293-1295 : Trane Co., The, 1298-1301 Wesix Electric Heater Co., 1307- Young Radiator Co., 1304 American Foundry & Furnace Co., 1200-1267 . . E. K. Campbell Co., 1270 Campbell Heating Co., 1268-1269 Cyclotherm Div. of National-U. S. Radiator Corp., 1545 ' . Dravo Corp., 1272-1273 ` Hayes Furnace Mfg. A Supply Co~ 1252-1253 American Foundry A Furnace Co., 1266-1267 . .Campbell Heating Co., 1268-1289 Chicago Steel Furnace Co., 1271 Johnson Heater Corp.. 1484-1485 National Heater Co., 1280-1281 Arthur A. Olson A Co., 1279 . Thermobloc Div., Prat-Daniel Corp., 1284 Johnson Heater Corp., 1274-1275 HEATERS, Convection (See Base Lee Corp., 1277 board Heating, Convection Heaters) Mammoth Furnace Co., The, 1278 Tjernlund Mfg. Co., 1285 Vapor Heating Corp., 1567 York-Shipley, Inc., 1590 . HEATERS, Duct Mueller Climatrol, Div. of Worth John Zink Co., 1588-1589 ington Corp., 1254-1255 . . Campbell Heating Co., 1268-1269 Carrier Corp., 1226-1227 \ Chicago Steel Furnace Co., 1271 Dravo Corp., 1272-1273 . Electromode Corp., 1305 - Hastings Air Conditioning Co., Inc., 1233 . Hayes Furnace Mfg. A Supply Co., 1252-1253 Industrial Engineering A Equip ment Co., 1306 . Mammoth Furnace Co., The, 1278 Modine Mfg. Co., 1290-1291 National Heater Co., 1280-1281 Reznor Mfg. Co., 1282-1283 Edwin L. Wiegand Co., 1308-1309 John Zink Co., 1588-1589 . HEATERS, Electric Electromode Corp., 1305 Industrial Engineering A Equip ment Co.. 1306 Trade-Wind Motorfana, Inc., 1405 Wesix Electric Heater Co., 1307 Edwin L. Wiegand Co., 1308-1309 HEATERS, Feed Water American District Steam Div., Adsco Industries, Inc., 1505, 1594 Bell A Gossett Co., 1598-1599 Packard Water Conditioner Div., Packard Mfg. Co., 1575 Pattereon-Kelley Co., Inc., The, 1363 Warren Webster A Co., 1638-1639 Worthington Corp., 1241 HEATERS, Fuel Oil American District' Steam Div., Adsco Industries, Inc., 1505; 1594 Bell A Gossett Co., 1598-1599 Campbell Heating Co., 1268-1269 Cyclotherm, Div. of National- U. S. Radiator Corp., 1545 Dravo Corp., 1272-1273 General Fittings Co., 1596 Industrial Engineering A Equip ment Co., 1306 * ' Johnson Heater Corp., 1274-1275 . E. B. Kaiser Co., 1648-1649 . Killebrew Engineering Corp., 1597 Mammoth Furnace Co., The, 1278 National Heater Co., 1280-1281 Arthur A. Olson & Co., 1279 Reznor Mfg. Co., 1282-1283 -Rheem Mfg. Co., 1260-1261 Vapor Heating Corp., 1667 Westinghouse Electric Corp., 8tur- tevant Div., 1410 . John Zink Co., 1588-1589 HEATERS, Hot Water Service Aerco Corp., 1595 Air Devices, Inc., 1316,1432 Airtemp Div., Chrysler Corp., 1248-1249 . Aldrich Co., 1541, American District Steam Div., " Adsco Industries, Inc., 1505, 1594 Bell A Gossett Co., 1598-1599 Bryan Steam Corp., 1543 Burnham Corp., 1526-1527 Columbia Boiler Co., 1546-1547 Crane Co., 1528-1529 - Cyclotherm Div. of National-U. 8. Radiator Corp. 1545 Dewey-Shepard Boiler Co., 1550 - Dutton Boilers, Div. Hapman- Dutton Co., 1551 ' Fitzgibbons Boiler Co.. Ine., 1552 1553 General Fittings Co., 1596 Hydrotherm, Ino., 1555 S. T. Johnson Co., 1582-1583 Johnston Bros., Ine., 1557 .. Kewanee Boi'er Div. of American- Standard, 1558-1561 Kfllehrew Engineering Corp., 1597 Mueller Climatrol, Div. (j Worth ington Corp., 1254-1255 National-U. S. Radiator Corp., 1530-1533 Patterson-Kelley Co., Ine., The. 1363 . Raypak Co., Inc., 1563 Rheem Mfg. Co., 1260-1281 H. B. Smith Co., Ino., The, 1537 Taco Heaters, Inc., 1602 Titusville Iron Works Co., The, (Div. of Struthers-Wells Corp.), 1564-1565 Vapor Heating Corp., 1567 Weil-McLain Co., 1540 HEATERS. Storage American District Steam Div., Adsco Industries. Inc., 1505, 1594 Fitzgibbons Boiler Co.. Inc., 1552 1553 E. B. Kaiser Co., 1648-1649 Kewanee Boiler Div. of American- Standard, 1558-1561 Killebrew Engineering Corp., 1597 National-U. S. Radiator Corp.. 1530-1533 . Patterson-Kelley Co., Inc., The. 1363 Taco Heaters, Inc., 1602 Edwin.L. Wiegand Co., 1308-1309 HEATERS. Tank Aerco Corp., 1595 American District Steam Div., Adsco Industries, Inc., 1505, 1594 Bell A Gossett Co., 1598-1599 Drayer-Hanson, Inc., Div. of Na tional-U. S. Radiator Corp., General Fittings Co., 1596 . Industrial Engineering A Equip ment Co., 1306 E. B. Kaiser Co., 1648-1649, Killebrew Engineering Corp., 1597 Patterson-Kelley Co., Inc., The. 1363 . Wesix Electric Heater Co., 1307. Edwin L. Wiegand Co., 1308-1309 HEATERS, Unit Airtherm Mfg. Co., 1522 American Blower Corp., 1220-1221 American Foundry.* Furnace Co.. 1266-1267 Bishop A Babcock Mfg. Co., The, (Massachusetts Blower Div.), 1377 Buffalo Forge Co., 1382 Burnham Corp., 1526-1527 Campbell Heating Co., 1268-1269 Carrier Corp., 1226-1227 Chicago Steel Furnace Co., 1271 Clarage Fan Co., 1225, 1387 Crane Co., 1528-1529 Dravo Corp., 1272-1273 C. A. Dunham Co., 1618-1621 Feddeis-Quigan Corp., 1286 National Heater Co., 1280-1281 Arthur A. Olson A Co., 1279 Patterson-Kelley Co., Inc., The, 1363 Preferred Utilities Mfg. Corp., 1566 Taco Heaters, Inc., 1602 : - H. A. Thrush A Co., 1600-1601 Titusville Iron Works Co., The, (Div. of Struthers-Wells Corp.), 1564-1565 Tjernlund Mfg. Co., 1285 Vapor Heating Corp., 1567 Edwin L. Wiegand Co., 1308-1309 HEATERS, Gas HEATERS, Indirect Aerco Corp., 1595 Aerofin Corp., 1359-1361 . American District Steam Div., Adsco Industries, Inc., 1505, 1594 Bell A Gossett Co., 1598-1599 . Campbell Heating Co., 1268-1269 ' Genual Fittings Co/( 1596 Killebrew Engineering Corp., 1597 Patterson-Kelley Co., Inc.. The, 1363 Taco Heaters, Inc., 1602 HI A. Thrush A Co., 1600-1601 York-Shipley, Inc., 1590 Governair Corp., 1232 Hartzell Propeller Fan Co., Div. of Qastle Bills Coip., 1392 Hastings Air Conditioning Co., Inc., 1233 Hayes Furnace Mfg. * Supply Co., 1252-1253 Ilg Electric Ventilating Co., 1287, 1393 Jackson * Church Co., 1276 Johnson Heater Corp., 1274-1275 Kennard Corp., 1234 Lee Corp., 1277 Mammoth Furnace Co., The, 1278 Mario Coil Co. 1355 Airtemp Div., Chrysler Corp., 1248 McQuay, Inc., 1288-1289 1249 HEATERS, Space, Direct-Fired Modine Mfg. Co., 1290-1291 Airtherm Mfg. Co., 1522 Airtherm Mfg. Co., 1522 Muckle Mfg. Co., 1421 Please mention THE GUIDE 1956 when writing to Advertisers 1202 1956 Guide Mueller Climatrol, Div. of Worth? HEATERS. Unit, Oil Fired E. K. Campbell Co., 1270 ington Corp., 1254-1255 . Airtherm Mfg. Co., 1522 Campbell Heating Co., 1268-1269 D. J. Murray Mfg. Co., 1292 American Foundry A Furnace Co., Chicago Steel Furnace Co., 1271 National Heater Co., 1280-1281 ' 1266-1267 Columbia Boiler Co., 1546-1547 National-U. S. Radiator Corp.. Campbell Heating Co., 1268-1269 . Crane Co., 1528-1529 1530-1533 # # Chicago Steel Furnace Co., 1271 Dravo Corp., 1272-1273 .. Herman Nelson, American Air Dravo Corp., 1272-1273 ' C. A. Dunham Co., 1618-1621 . Filter Co., Inc.i 1296-1297 Johnson.Heater Corp., 1274-1275 General Electric Co., 1230 John J. Nesbitt, Inc., 1293-1295 Lee Corp., 1277 . Hayes Furnace Mfg. A Supply Co: New York Blower Co., 1399 Mammoth Furnace Co., The, 1278 1252-1253 Niagara Blower Co., 1235 Mueller Climatrol Div. of Worth Hoffman Specialty Mfg. Corp., 1622 Arthur A. Olson A Co., 1279 . ington Corp., 1254-1255 . . 1625 . Reznor Mfg. Co., 1282-1283 National.Heater Co., 1280-1281 Hydraline Products Div., Borg- Rheem Mfg. Co., 1260-1261 Arthur A. Olson A Co., 1279 . Waroer Corp., 1251 '* Rittling Corp., The, 1364 Thermobloc. Div., Prat-Daniel Hydrothenn, Inc., 1555 Roberts-Gordon Appliance Corp., Corp., 1284 : Illinois Engineering Co., 1626-1627 1577 ` Tjernfund Mfg. Co., 1285 ~ Jackson A Church Co., 1276 Sheldons Engineering Ltd., 1404 ' - Johnson Heater Corp., 1274-1275 Thermobloc Div., Prat-Daniel HEATING DUCTS. Under Con S. T. Johnson Co., 1582-1583 Corp., 1284 crete Floor Slabs (See Duett, Kewanee Boiler Div. of American- Tjernfund Mfg. Co-, 1285 Under Concrete Floor Slabs) Standard, 1558-1561 Trane Co., The, 1298-1301 Lee Corp., 1277 - ~ Union Asbestos A Rubber Co., 1265 HEATING SYSTEMS, Air, Heavy Mammoth Furnace Co., The, 1278 Vapor Heating Corp., 1567 Duty Mueller Climatrol, Div. of Worth Warren Webster A Co., 1638-1639 Airtherm Mfg. Co., 1522 . ington Corp., 1254 Western BlowerCo., 1409 American Foundry A Furnace Co., National Heater Co., 1280-1281 .. Westinghouse Electric Corp., Stur- , 1266-1267 National U. S. Radiator Corp., tevant Div., 1410 Armstrong Furnace Co., 1246-1247 Edwin L. Wiegand Co., 1308-1309' E. K. Campbell Co., 1270 L. J. Wing Mfg. Co., 1302-1303 .Campbell Heating Co., 1268-1269 1530-1533 Arthur A. Olson A Co., 1279 Pennsylvania Furnace A Iron Co., Young Radiator Co., 1304 John Zink Co., 1588-1589 Chicago Steel Furnace Co., 1271 Dravo Corp., 1272-1273 1258 - . . ` Ray Oil Burner Co., 1584-1585 HEATERS, Unit, Electric Lee Corp., 1277 Reznor Mfg. Co., 1282-1283 Mueller Climatrol, Div. of Worth Rheem Mfg. Co., 1260-1261 Electromode Corp., 1305 . Ilg Electric Ventilating Co., 1287, 1393 Wesix Electric Heater Co., 1307 ington Corp., 1254-1255 Sarco Co., Inc., 1634-1635 National Clay Pipe Mfgrs., The Sarcotherm Controls, Inc., 1633 1516-1521: . Titusville Iron Works Co., The, National Heater Co., 1280-1281 . (Div. of Struthers-WeUs Corp.), Edwin L. Wiegand Co., 1308-1309 L; J: Wing Mfg. Co., 1302-1303 Niagara Blower Co., 1235 ' Arthur A. Olson A Co., 1279 1564-1565 Tiane Co., The, 1298-1301 HEATERS. Unit, Gas Fired Airtherm Mfg. Co., 1522 American Blower Corp., 1220-1221 Ray Oil Burner Co., 1584-1585 Tjernlund Mfg. Co., 1285 Trane Co., The, 1298-1301 . Vapor Heating Corp:, 1567 .Weil-McLainCo., 1540 . York-Shipley, Inc., 1590 . American Foundry A Furnace Co., 1266-1267 :: Burnham Corp., 1526-1527 ' Campbell Heating Co., 1268-1269 Carrier Corp., 1226-1227 . . Dravo Corp., 1272-1273 Fedders-Quigan Corp., 1286 Hastings Air Conditioning Co., Inc., 1233 Hayes Furnace Mfg. A Supply Co., 1352-1353 Ug Electric Ventilating Co., 1287, 1393 ; Johnson Heater Corp., 1274-1275 . Lee Corp., 1277 Mammoth Furnace Co., The, 1278 Modine Mfg. Co., 1290-1291 Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 National Heater Co., 1280-1281 National-U. S. Radiator Corp., 1530-1533 Herman Nelson, American Air Filter Co.. Inc., 1296-1297 John J. Nesbitt, Inc., 1293-1295 Norman Products Co., 1257 Arthur A. Olson & Co., 1279 HEATING SYSTEMS, Air Resi dence Airtemp Div., Chrysler Corp., 1248-1249 American-Standard, Air Condition ing Div., 1244-1245 Armstrong Furnace Co., 1246-1247 Burnham Corp., 1526-1527 :Jackson A Church Co., 1276 ' Johnson Heater Corp., 1274-1275 Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 National Clay Pipe Mfgrs., The, 1516-1521 Pennsylvania Furnace A Iron Co., 1258 - Roberts-Gordon Appliance Corp:. 1577 Servel, Inc., 1262-1263 - Trane Co., The, 1298-1301 National-U. - S. Radiator Corp., 1530-1533 Edwin L. Wiegand Co., 1308-1309 York-Shipley, Inc:, 1590 John Zink Co., 1588-1589 HEATING SYSTEMS, Coal Fired American Foundry A Furnace Co., 1266-1267 # American Radiator A Standard Sanitary Corp., (Plumbing A Heating Div.), 1520-1525 American-Standard, Air Condition ing Div., 1244-1245 E. K. Campbell Co., 1270 Campbell Heating Co., 1268-1269 Columbia Boiler Co., 1546-1547 Crane Co., 1528-1529 Fitzgibbons Boiler Co:, Inc., 1552 1553 . . . Kewanee Boiler Div. of American- Standard, 1558-1561 Lee Corp., 1277 Mueller Climatrol Div. of Worth ington Corp., 1254-1255 National Heater Co., 1280-1281 National-U. S. Radiator Corp., 1530-1533 . Arthur A. Olson A Co., 1279 HEATING SYSTEMS, Electric Reznor Mfg. Co., 1282-1283 ' HEATING SYSTEMS, Automa Electromode Corp., 1305 Rheem Mlg. Co., 1260-1261 tic Industrial Engineering A Equip- Sonner-Burner Co., The, 1578 . Airtemp Div., Chrysler Corp., / roent Co., 1306 Thermobloc Div., Prat-Daniel 1248-1249 . Wesix Electric Heater Co., 1307 Corp., 1284 Tjernfund Mfg. Co., 1285 Airtherm Mfg. Co., 1522 American Foundry A Furnace Edwin L. Wiegand Co., 1308-1309 Trane Co., The, 1298-1301 Vapor Heating Corp., 1567 Warren Webster A Co., 1638-1639 Co., 1266-1267 American Radiator A Standard HEATING SYSTEMS, Furnace Sanitary Corp., (Plumbing A Airtemp Div., Chrysler Corp.; 1248- Westinghouse Electric Corp., Stur- Heating Div.), 1523-1525 1249 tevant Div., 1410 American-Standard, Air Condition Airtherm Mfg. Co., 1522 . L. J. Wing Mfg. Co., 1302-1303 ing Div., 1244-1245 American Foundry & Furnace Co'., John Zink Co., 1588-1589 Burnham Corp., 1526-1527 1266-1267 ... Numerals following Manufacturers' Names refer to pages in the Catalog Data Section Index to Modem Equipment 1203i American-Standard, Air Condition Parks-Cramer Co., 1236-1237 Lee Corp., 1277 -. ing Div., 1244-1245 Titusville Iron Works Co., The, Mammoth Furnace Co., The.1278 Armstrong Furnace Co., 1246-1247 (Div. of Struthers-Wells Corp.), Mueller Climatrol; Div. of Worth E; K. Campbell Co., 1270 ' 1564-1565 ington Corp., 1254-1255 . Campbell Heating Co., 1268-1269 National Clay Pipe Mfgrs., The,' Chicago Steel Furnace Co., 1271' -Crane Co., 1528-1529 Dravo Corp-, 1272-1273 General Electric'Co., 1230. ' Jackson A Church Co., 1276 . S. T. Johnson Co., 1582-1583 Johnson Heater Corp., 1274-1275 Lee Corp., 1277 , Mammoth Furnace Co.,The, 1278 Mueller Climatrol Div. of Worth ington Corp., 1254-1255 National Clay Pipe Mfgrs., The, 1516-1521 . . National Heater Co., 1280-1281 Norman Products Co., 1257 Arthur A. Olson & Co., 1279 Ray Oil Burner Co., 1584-1585 Rheem Mfg. Co., 1260-1261 Tjemlund Mfg. Co., 1285 . York-Shipley, InC., 1590 HEATING SYSTEMS, Hot Water Air Devices^ Inc., 1316, 1432 Airtemp Div., Chrysler Corp., 1248-1249 American Radiator A Standard Sanitary Corp., (Plumbing A Heating Div.), 1523-1525 Bell A Gossett Co., 1598-1599 Bryan Steam Corp., 1543 . Burnham Corp., 1526-1527 Columbia Boiler Co., 1546-1547 Crane Co., 1528-1529 C. A. Dunham Co., 1618-1621 Durant Insulated Pipe Co., 1647 Durant International Corp., 1647 Fitzgibbons Boiler Co., Inc., 1552 1553 General Automatic Products Corp., 1513 . General Electric Co., 1230 Hoffman Specialty Mfg. Corp. 1516-1521 .- National Heater Co., 1286-1281 National-U-S. Radiator Corp., 1530- - 1533 Arthur A. Olson A Co., 1279 Ray OU Burner Co., 1584-1585 Rheem Mfg. Co., 1260-1261 , . Tjernlund Mfg. Co., 1285 York-Shipley, Inc., 1590 . HEATING SYSTEMS, Steam American Radiator A Standard Sanitary Corp., (Plumbing . A Heating Div.), 1523-1525 Barnes A Jones, Inc., 1616 . . Bryan Steam Corp., 1543 Burnham Corp., 1526-1527 . ' Columbia Boiler Co., 1546-1547 Crane Co., 1528-1529 .. Dole Valve Co., The, 1640 C. A. Dunham Co., 1618-1621 HEATING SYSTEMS. Gas Fired Airtemp Div., Chrysler Corp., 1248 1249 Airtherm Mfg. Co., 1522 . American Foundry A Furnace Co., 1266-1267 American Radiator A Standard Sanitary Corp., (Plumbing A Heating Div.), 1523-1525 American-Standard, Air Condition ing Div., 1244-1245 ' Bryan Steam Corn., 1543 - E. K. Campbell Co., 1270 Campbell Heating Co., 1268-1269 Chicago Steel Furnace Co.', 1271 Columbia Boiler Co., 1546-1547 Crane Co., 1528-1529 . Dewey-Shepard Boiler Co., 1550 Dravo Corp., 1272-1273 Fitzgibbons Boiler Co., Inc., 1552 1553 General Automatic Products Corp., 1513 Hayes Furnace Mfg. A Supply Co., 1252-1253 Hydrotherm, Inc., 1555 Jackson A Church Co., 1276 Johnson Heater Corp., .1274-1275 Kewanee Boiler Div. of American- Standard, 1558-1561 1622-1625 Hydraline Products, Div. Borg- Warner Corp., 1251 ' Hydrotherm, Inc., 1555 8. T. Johnson Co., 1582-1583 "E. B. Kaiser Co., 1648-1649 Kewanee BoilOr Div. of American- Standard, 1558-1561 Jas. P. Marsh Corp., 1628-1629 Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 . National-U. S. Radiator Corp., 1530-1533 Pennsylvania Furnace A Iron Co., 1258 Raypak Co., Inc., 1563 Refrigeration Engineering, Inc., 1373 Ric-wiL, Inc., 1651 Sarco-Sarcotherm, 1633-1635 H. JB. Smith Co., Inc., The, 1537 Taco Heaters, Inc., 1602 ' Trane Co., The, 1298-1301 H. A. Thrush & Co., 1600-1601 Vapor Heating Corp., 1567 Vulcan Radiator Co., The, 1367 Warren Webster A Co., 1638-1639 York-Shipley, Inc., 1590 HEATING SYSTEMS, Oil Fired Durant Insulated Pipe Co., 1647 Durant International Corp., 1647.. . Fitzgibbons Boiler Co., Inc., 1552 1553 Hoffman Specialty Mfg. Corp., 1622-1625 Illinois Engineering Co., 1626-1627 S. T. Johnson Co., 1582-1583 E. B. Kaiser Co., 1648-1649 ' Kewanee Boiler Div. of American- Standard, 1558-1561 Jas. P. Marsh Corp., 1628-1629 Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 ' National-U. S: Radiator Corp.,. 1530-1533 Pennsylvania Furnace A Iron Co., 1258 Ric-wiL, Inc., 1651 Sarco-Saxcotherm, 1633-1635 H. B. Smith Co., Inc., The, 1537 Titusville Iron Works Co., The, t(tDflii-vie. aoef Struthers-Wells Corp.), Trane Co., The, 1298-1301 . Vapor Heating Corp., 1567 Vulcan Radiator Co., The, 1367 Warren Webster & Co., 1638-1639 L. J. Wing Mfg. Co., 1302-1303 York-Shipley, Inc., 1590 Lee Corp., 1277 Mammoth Furnace Co., The, 1278 Mueller Climatrol, Div. of Worth ington Corp., 1254-1255 National Clay Pipe Mfgrs., The, 1516-1521 National Heater Co., 1280-1281 National-U. S. Radiator Corp., 1530-1533 Airtemp Div., Chrysler Corp., 1248-1249 Airtherm Mfg. Co., 1522 American Foundry A Furnace Co., 1266-1207 American Radiator A Standard Sanitary Corps., (Plumbing A Heating Div.), 1523-1525 American-Standard, Air Condition HEATING SYSTEMS. Under Concrete Floor Slabs National Clay Pipe Mfgrs., The, 1516-1521 ' HEATING SYSTEMS. Vacuum American Radiator & Standard Sanitary Corp., (Plumbing A Heating Div.), 1523-1525 Norman Products Co., 1257 Arthur A. Olson A Co., 1279 Reznor Mfg. Co., 1282-1283 Rheem Mfg. Co., 1260-1261 Roberts-Gordon Appliance Corp., 1577 Titusville Iron Works Co., The, (Div. of Struthers-WeUs Corp.), 1564-1565 Tjernlund Mfg. Co., 1285 L. J. Wing Mfg. Co., 1302-1303 York-Shipley, Inc., 1590 John Zink Co., 1588-1589 ing Div., 1244-1245 Bryan Steam Corp., 1543 Burnham Corp., 1526-1527 E. K. Campbell Co., 1270 Campbell Heating Co., 1268-1269 Columbia Boiler Co., 1546-1547 Crane Co., 1528-1529 Dewey-Shepard Boiler Co., 1550 Dravo Corp., 1272-1273 Fitzgibbons Boiler Co., Inc., 1552 1553 General Automatic Products Corp., 1513 Barnes A Jones, Inc., 1616 Columbia Boiler Co., 1546-1547 C. A. Dunham Co., 1618-1621 General Electric Co., .1230 Hoffman Specialty Mfg. Corp., 1622-1625 Illinois Engineering Co., 1626-1627 Kewanee Boiler Div. of American- Standard, :558-1561' Jas. P. Marsh Corp., 1628-1629 National-U. S. Radiator Corp., 1530-1533 . Sarco-Sarcotherm, 1633-1635 Jackson A Church Co., 1276 . Warren Webster & Co., 1638-1639 HEATING SYSTEMS, Hlgh- S. T. Johnson Co., 1582-1583 temperature Fluid Johnson Heater Corp., 1274-1275 HEATING SYSTEMS. Vapor International Boiler Works Co., Kewanee Boiler Div. of American- Airtemp Div., Chrysler Corp., 1248 The, 1556 Standard, 1558-1561 1249 Please mentioi1 THE GUIDE 1956 when writing :o Advertisers 1204 1956 Guide American Radiator A Standard Powers Regulator Co., The' 1496 IGNITION, Oil Burner (See Sanitary Corp., (Plumbing A 1498 Transformers) Heating Div.), 1523-1525 Barnes A Jones, Inc., 1616 O. A. Dunham Co., 1618-1621 Trane Co., The, 1298-1301 . Westinghouse Electric Corp., Stur- tevant Div., 1342 Hoffman Specialty Mfg. Corp., 1622-1625 HUMIDIFIERS, Convector Illinois Engineering Co., 1625^1627 Maid-O'-Mist, Inc., 1630-1632 Kewanee Boiler Div., American* Standard, 1558-1561 HUMIDIFIERS. Industrial Jaa. P. Marsh Corp., 1628-1629 American Moistening Co., 1222 Nation&l-U. S. Radiator Corp.,' Armstrong Machine Works, 1614 1530-1533 1615 Sarco Co., Inc., 1634-1635 Bahnson Co., The, 1223 Sarcotherm Controls, Inc., 1633 Binks Mfg. Co., 1344-1345 Titusville Iron Works Co., The Maid-O'-Mist, Inc., 1630-1632 (Div. of StrutheiB-Wells Corp.), Parks-Cramer Co., 1236-1237 1564-1565 Walton Laboratories, Ino., 1239 Trane Co., The, 1298-1301 INDUCED DRAFT COOLING TOWERS (See Cooling Towers, Forced Draft, Mechanical Draft) Acme Industries, Inc., 1358 Baltimore Airooil Co., Inc., 1346 Binks Mfg. Co., 1344-1345 Fluor Corp., Ltd., The, 1347 E. D. Goodfellow, Inc., 1348 Governair Corp., 1232 Kennard Corp., 1234 Lflie-Hoffmann Cooling Towers, Inc., 1353 Marley Co., The, 1354 Mario Coil Co., 1355 Phillips Cooling Tower Co., Inc., 1356 Vapor Heating Corp., 1567 Warren Webster A Co., 1638-1639 York-Shipley, Inc., 1590 HOSE, Flexible Aeroquip Corp., 1312 _ Wiremofa Co., The, 1469 HUMIDIFIERS. Spray American Moistening Co., 1222 Bahnson Co., The, 1223 Binks Mfg. Co., 1344-1345 Maid-O'-Mist, Inc., 1630-1632 Walton Laboratories, Inc., 1239 HUMIDIFIERS, Unit HOSE, Flexible. Metal American Moistening Co., 1222 American Brass Co., The, 1310-1311 Armstrong Machine Works, 1614-- T. R. Finn A Co., Inc., 1686 . Flexonics Corp., 1507 1615 Bahnson Co., The, 1223 Henry Valve Co., 1482 Buffalo Forge Co., 1382 Farr Co., 1332-1333 HOT WATER HEATING SYS Mario Coil Co., 1355 TEMS (See Heating Systems, Hot D. J. Murray Mfg. Co., 1292 Water) Niagara Blower Co., 1235 Parks-Cramer Co., 1236-1237 HUMIDIFIERS Somers Corp., 1339 INSTRUMENTS, Indicating, Controlling and Recording Barber-Colman Co., 1437,1473 Combustion Control Div., Elec tronics Corp. of America, 1475 Desomatic Products, Inc., 1228 Electric- Auto-Lite Co., The, In strument A Gauge Div^, 1476 General Controls, 1486-1481 Illinois Testing Laboratories, Inc:, 1486 . Johnson Service Co., 1484-1485 Jas. P. Marsh Corp., 1628-1629 Minneapolis-Honeywell Regulator Co., 1490-1491 Moeller instrument Co., 1493 ' Powers Regulator Co., The, 149(K 1498 Taylor Instrument Cos., 1503 Air & Refrigeration Corp., 1219 Trane Co., The, 1298-1301 American Blower Corp., 1220-1221 Walton Laboratories, Inc., 1239 INSULATION, Acoustical (See American Moistening Co., 1222 ^ Insulation, Sound Deadening) . American-Standard, Air Condition HUMIDITY AND TEMPERA ing Div., 1244-1245 TURE CONTROL INSULATION, Aluminum Armstrong Machine Works, 1614--. American Moistening Co., 1222 Infra InsuIation.Inc., 1679 - 1615 . . Armstrong Machine Works, 1614-- Reflectal Corp., 1682 Bahnsod Co., The, 1223 . * 1615 Silvercote Products, Inc., 1680-1681 Binks Mfg. Co., 1344-1345 Bahnson Co., The, 1223 . Buensod-Stacey, Inc., 1224 Barber-Colman Co., 1437, 1473 - INSULATION. Anchors and Ad Buffalo Forge Co., 1382 Buensod-Stacey, Inc., 1224 hesives (See Anchors, Adhesive) Clarage Fan Co., 1225, 1387 . Desomatic Products, Inc.,. 1228 Farr Co., 1332-1333 . C. A. Dunham Co., 1618-1621 INSULATION, Asbestos. (See Maid-O'-Mist, Inc., 1630-1632 Johnson Service Co., 1484-1485 Covering, Pipe) ' Jas. P. Marsh Corp., 1628-1629 Mercoid Corp., The, 1489 McDonnell & Miller, Inc., 1570-1573 Minneapolis-Honeywell Regulator INSULATION. Building Mueller Climatrol, )iv. of Worth Co., 1490-1491 American Flange A Mfg. Co., Inc., ington Corp., 1254-1255 , Parks-Cramer Co., 1236-1237 1678 Niagara Blower Co., 1235 Penn Controls, Inc., 1494 Armstrong Cork Co.. 1665 Parts-Cramer Co., 1236-1237 Powers Regulator Co., The, 1496 Philip Carey Mfg. Co., The, 1656-- . Research Products Corp., 1338 1498 1657 Somers Corp., 1339 Taylor Instrument Cos., 1503 Celotex Corp., The, 1666 Trane Co., The, 1298-1301 White-Rodgers Electric Co., 1504 Dow Chemical Co., The, 1667 Viking Air Products, Div. National- L.O.F Glass Fibers Co., 1655 . U. S. Radiator Corp., 1408 HUMIDITY RECORDERS and Infra Insulation, Inc.,' 1679 Walton Laboratories, Inc., 1239 HUMIDIFIERS, Central Plant Air A Refrigeration Corp., 1219 American Moistening Co., 1222 Armstrong Machine Works; 1614-- 1615 Bahnson Co., The, 1223 Bayley Blower Co., 1376 Buensod-Stacey, Inc., 1224 Buffalo Forge Co., 1382 Carrier Corp., 1226-1227 Clarage Fan Co., 1225, 1387 Farr Co., 1332-1333 Johnson Service Co., 1484-1485 Mario Coil Co., 1355 Jas. P. Marsh Corp., 1628-1629 McDonnell & Miller, Inc., 1576-1573 Niagara Blower Co., 1235 Parks-Cramer Co., 1236-1237 INDICATORS American Moistening Co., 1222 Barber-Colman Co., 1437, 1473 Johnson Service Co., 1484-1485 . Minneapolis-Honeywell Regulator Co., 1490-1491 Moeller Instrument Co., 1493 Parks-Cramer Co., 1236-1237 Powers Regulator Co., The, 1496-- 1498 Taylor Instrument Cos., 1503 WaJton Laboratories, Inc., 1239 HYGROMETERS (See Humidity Recorders and Indicators) American Moistening Co., 1222 Moeller Instrument Co., 1493 ' Parks-Cramer Co., 1236-1237 Taylor Instrument Cos., 1503 Walton Laboratories, Inc., 1239 Insulite, 1668-1669 Johns-Manville, 1670-1671 Kimberly-Clark Corp., 1672-1673 Lockport Mills, Inc.. 1674 Owens-Coming Fiberglas Corp., 1336, 1658 Pacific Lumber Co., The, 1675 Pittsburgh Coming Corp., 1662 Pittsburgh Plate Glass Co., Fiber Glass Div., 1337, 1664 H. W. Porter A Co., Inc., 1650 Reflectal Corp., 1682 Reid Hayden, Inc., 1650 Silvercote Products, Inc., 1680-1681 Tectum Div., Peoples Research A Mfg. Co., 1676 Wood Conversion Co., 1677 INSULATION, Calcium Silicate Johns-Manville, 1670-1671 Numerals following Manufacturers' Names refer to pages In the Catalog Data Section Index to Modem Equipment 1205 Owens-Coming Kaylo, 1658 Fibendas Coro.. Infra Insulation, Inc., 1679 . Silvercote Products, Inc., 1680-1681 INSULATION, Steam Pipe Underground INSULATION, Cellular Glass Pittsburgh Coming Corp., 1663 INSULATION, Cork Armstrong Cork Co., 1665 H. W. Porter A Co., Inc., 1650 Reid Hayden, Inc., 1650 INSULATION. Mineral American Gilsonite Co., 1646 Owens-Coming Fiberglas Coro. Kaylo, 1658 Tectum Div., Peoples Research A Mfg. Co., 1676 American Gilsonite Co., 1646 Durant Insulated Pipe Co., 1647 Durant International Corp., 1647 Johns-Manville, 1670-1671 E. B. Kaiser Co., 1648-1649 Owens-Coming Fiberglas Corp.. Kaylo, 1658 INSULATION. Cotton Lockport Mills, Inc., 1674 Pittsburgh Coming Corp., 1663 INSULATION, Mineral Wool H. W. Porter A Co., Inc., 1650 (See Insulation, Building) Reid Hayden, Inc., 1650 INSULATION, Ducts, Ventilat ing, Air Conditioning Armstrong Cork Co., 1665 Celotex Corp.. The, 1666 Ric-wiL, Inc., 1651 INSULATION, Pipes and Sur Stillwater Clay Products Co., The, faces (See Covering, Pipe and 1652 Surface) Z-Crete Div., Zonolite Co., 1653 Dow Chemical Co., The, 1667 INSULATION. Plastic B. F. Goodrich, Sponge Products Dow Chemical Co., The, 1667 Div., 1683 INSULATION, Water April Showers Co., Inc., 1644 Infra Insulation, Inc., 1679 INSULATION, Reflective Johns-Manville, 1670-1671 American Flange A Mia.' Co.. Ino.. Kimberly-Clark Corp., 1672-1673 1678 * L.OJ Glass Fibers Co., 1655 Celotex Corp., The, 1666 Lockport Mills, Inc., 1674 L.O.F Glass Fibers Co., 1655 Owens-Coming - Fiberglas Corp. Infra Insulation, Inc., 1679 Kaylo, 1658 Kimberly-Clark Corp., 1672-1673 Pittsburgh Coming Corp., 1663 Lockport Mills, Inc.; 1674 Pittsburgh Plate Glass Co., Fiber Pittsburgh Plate Glass Co., Fiber Glass Div., 1337, 1664 ------ - ..Glass Div., 1337, 1664 Reflectal Corp., 1682 Reflectal Corp., 1682 Wood Conversion Co., 1677 Silvercote Products, Inc., 1680-1681 ISOLATION VIBRATION, Shock & Noise (Sec Acoustical Control, Vibration Absorbers; Sound Isolators) JOINTS, EXPANSION (See Ex pansion joints) LABORATORY RESEARCH AND TESTING (See Testing Laboratory) . INSULATION, Felt Philip Carey Mfg. Co., 1656-1657 Johns-Manville, 1670-1671 L.O.F Glass Fibers Co., 1655 INSULATION, Refractory Philip Carey Mfg. Co., The, 1656 1657 ' ' Johns-Manville, 1670-1671 LABORATORY VENTILATION (See Exhausters, Laboratory Fume; Fume Disposal Units (Hoods) Laboratory) Lockport Mills, Inc., 1674 Owens-Coming Fiberglas 1658 Wood Conversion Co., 1677 Corp.. INSULATION, Sheets, Stainless LIQUID LEVEL CONTROLS Steel Alco Valve Co., 1472 . American Flange A Mfg. Co., Inc.. Barber-Colman Co., 1437, 1473 1678 Fulton Sylphon Div., The, Robert- INSULATION, Fiber Celotex Corp., The, 1666 Insulite, 1668-1669 ' Johns-Manville. 1670-1671 Kimberly-Clark Corp., 1672-1673 L.O.F Glass Fibers Co., 1655 Lockport Mills, Inc., 1674 Owens-Corning Fiberglas Corp.. 1658 . Pacific Lumber Co., The, 1675 Pittsburgh Plate Glass Co., Fiber Glass Div., 1337, 1664 Wood Conversion Co., 1677 INSULATION, Sound Deaden ing (See also Felt, Sound Deaden ing) Philip Carey Mfg. Co., The, 1656 1657 Celotex Corp., The, 1666 T. R. Finn A Co., Inc., 1686 Insulite. 1668-1669 Johns-Manville, 1670-1671 Kimberly-Clark Corp., 1672-1673 Korfund Co., Inc., The, 1687 L.O.F Glass Fibers Co., 1655 Lockport MiUs, Inc., 1674 shaw-Fulton Controls Co., 1478-- 1479 General Controls. 1480-1481 Heller Laboratories, Inc., 1352 Johnson Service Co., 1484-1485 Leslie Co., 1487 Jas. P. Marsh Corp., 1628-1629 McDonnell A Miller, Inc., 1570-1573 Penn Controls, Inc., 1494 Powers Regulator Co., The, 1496 1498 Spence Engineering Co., Inc., 1501 Taylor Instrument Cos., 1503 INSULATION, Fibrous Glass Armstrong Cork Co., 1665 L.O.F Glass Fibere Co., 1655 Owens-Coming Fiberglas Corp.. 1336, 1658 INSULATION, Low Tempera ture American Flange A Mfg. Co.. Inc . 1678 . Dow Chemical Corp., The, 1667 Infra Insulation, Ino., 1679 Johns-Manville, 1670-1671 Lockport Mills, Inc.. 1674 Owens-Coming Fiberglas Corp.. 1658 Pacific Lumber Co., The, 1675 Pittsburgh Corning Corp., 1663 Reflectal Corp., 1682 Owens-Coming Fiberglas Corp.. 1336, 1658 Pacific Lumber Co., The, 1675 Pittsburgh Plate Glass Co., Fiber Glass Div., 1337, 1664 Tectum Div., Peoples Research A Mfg. Co., 1676 Vibration Mountings, Inc., 1688 Wood Conversion Co., 1677 INSULATION. Steel American Flange A Mfg. Co., Inc., 1678 INSULATION, Structural American Flange A Mfg. Co., Inc.. 1678 Celotex Corp., The, 1666 Insulite, 1668-1669 Johns-Manville, 1670-1671 LIQUID LEVEL GAGES (See Gages, Liquid Level) LOUVERS (Also see Grilles, Regis ters) A-J Mfg. Cp., 1426-1427 Air-Factors, Inc., 1433 American Foundry A Furnace Co., 1266-1267 Auer Register Co., The, 1436 Barber-Colman Co., 1437, 1473 Hart A Cooley Mfg. Co., 1444-1445 Hendrick Mfg. Co., 1446--1447 Independent Register Co., The, 1448 Lima Register Co., 1450-1451 Pyle-National Co., The, (Multi Vent Div.), 1454-1455 Register & Grille Mfg. Co., Inc., 1453 INSULATION. Magnesia Philip Carey Mfg. Co., The, 1656 1657 Johns-Manville, 1670-1671 Kimberly-Clark Coro., 1672-1673 Pittsburgh Coming Corp., 1662 Pittsburgh Plate Glass Co., Fiber Glass Div., 1337, 1664 - Wood Conversion Co., 1677 Standard Stamping A Perforating Co., 1456 Stewart Mfg. Co., Inc., 1457 Swartwout Co., The, 1423 Titus Mfg. Corp., 1458-1459 United States Register Co., 1462 INSULATION, Metal INSULATION. Tubing 1463 American Flange A Mfg. Co., Inc.. 1678 B. F. Goodrich, Sponge Products .Waterloo Register Co., Inc., 1465 Div., 1683 L. J. Wing Mfg. Co., 1302-1303 Please mention THE GUIDE 1956 when writing to Advertisers 1206 1956 Guide MACHINED RINGS (See Rirva. MOTORS. Electric OIL BURNERS. Pressure Atom- Machined) Peerless Electric Co., 1400 izing Propellair Div., Robbins & Myers, Airtemp Div., Chrysler Corp., 1248- MECHANICAL DRAFT APPA Inc., 1401 RATUS See Blowers, Forced . Draft, Exhausters Laboratory Fume; MOUNTINGS, Spring Laboratory Ventilation) Kcxfund Co., Inc., The, 1687 American Blower Corp., 1220-1221 Vibration Mountings, Inc., 1688 1249 Aldrich Co., 1541 American Radiator & Standard Sanitary Corp., (Plumbing & Heating Div.), 1523-1525 Babcock & Wilcox Co., The, 1542 Clarage Fan Co:, 1225, 1387 Burnham Corp., 1526-1527 DeBothezat Fans Div., American NOISE ELIMINATORS (See Tub- Cleaver Brooks 6o,, 1544, 1580 'Mach--ine &- Metals, Inc., 1388-1389 in,, Flexible; Sound Deadeners; Columbia Boiler Co., 1546-1547 General Blower Co., 1391 Vibration Absorbers) Crane Co., 1528-1529 Kewaunee Mfg. Co., 1411 ` ` Dewey-Shepard Boiler Co., 1550 E. H. Sheldon Equipment Co. NON-FERROUS METAL CON- Eddington Metal Specialty Co., 1591 1412-1413 . Westinghouse Electric Corp., Stur- DUIT (See Conduit, Non-ferrous Enterprise Engine & Machinery Metal) Co., Burner Div., Sub. of General tevant Div., 1410 Metals Corp.,1581 - ' MECHANICAL DRAFT COOL- N?S'inf' BHne Smravinfi' F'{|bb0nS C'' lDC'' I552~ ING TOWERS (See Coolino Sdi^fqU Bumer?^Wafer Genial Automatic Products Corp., Towers, Forced Draft, .Induced Draft) . . ' Cooling (See Spray Nozzles) S. T. Johnson Co., 1582-1583 _ Acme Industries, Inc., 1358 Baltimore Aircoil Co., Inc., 1346 Binks Mfg. Co., 1344-1345 NOZZLES, Oil Burner Monarch Mfg. Works, Inc., 1357 Mueller Climatrol Div. of Worthing ton Corp., 1254-1255 Orr & Sembower, Inc., 1562 Fluor Corp., Ltd., The, 1347 Ray Oil Burner Co., 1584-1585 E. D. Goodfellow Co., Inc., 1348 Havens Structural.Steel Co., 1349 Kennard Corp., 1234 OIL BURNER MOTORS Motors, Electric) (See Rayfield-Staffeo Burner Co., 1586 Sonner Burner Co., The, 1578 National-U. S. Radiator Corp., LUie-Hoffmann Cooling Towers, 1530-1533 Inc., 1353 Marley Co., The, 1354 OIL BURNER TUBING. Flex ible (See Tubing, Flexible, Me John Zink Co., 1588-1589 Mario Coil Co., 1355 tallic) McQuay,' Inc.. 1288-1289 Phillips Coohng Tower Co., Inc., OIL BURNERS 1356 Aldrich Co., 1541 American Radiator & Standard METAL INSULATION (See In Sanitary Corp., (Plumbing & sulation, Metal) Heating Div., 1523-1525 Bryan Steam Corp., 1543 METAL SKYLIGHTS (See Sky- Cleaver-Brooks Co., 1544, 1580 lights. Metal and Ventilating) Columbia Boiler Co., 1546-1547 OIL BURNERS. Rotary . Enterprise Engine & Machinery Co., Burner Div., Sub. of General Metals Corp., 1581 S. T. Johnson Co., 1582-1583 Johnston Bro6., Inc., 1557 Preferred Utilities Mfg. Corp. 1566 Ray Oil Burner Co., 1584-1585 Rayfield-Staffeo Burner Co., 1586 Dewey-Shepard Boiler Co., 1550 . ntx-tpro Kir Eddington Metal Specialty Co., 1591 OIL BURNERS, Steam Atomiz AnemcstutCurp. of America, 1434- Tllinnia Testing Laboratories, Inc., 1486 E?"n S1 JgSH ^ -. _ . Babcock & Wilcox Co.. The, 1542 Metals Corp., 1581 Webster Engineering Co., The, 1579 Preferred Utility Mfg. Corp., 1566 Jobn Zink Co., 1588-1589 Ray Oil Burner Co., 1584-1585 .- METERS. Flow Minneapolis-Honeywell Regulator Co., 1490-1491 Taylor Instrument Cos., 1503 qjl BURNERS. Automatic Ald-rich C~o., --1541Airtemp Div., Chrysler Corp., 1248 OIL BURNERS, Variable Capac ity ' . Enterprise Engine & Machinery Co., Burner Div., Sub. of General 1249 , Metals Corp., 1_5_8_1 MIXERS, Hot-Cold Water, American Radiator & Standard Rayfield-Staffeo Burner Co., 1586 Steam-Water % , Sanitary Corp., (Plumbing & York-Shipley, Inc., 1590 American Radiator & Standard Heating Div.), 1523-1525 _ . . Sanitary . Corp., (Plumbing & American-Standard, Air Condition Heating Div.), 1523-1525 mg Div., 1244-1245 Fulton Sylphon Div., The, Robert- Armstrong Furnace Co., 1246-1247 shaw-Fulton Controls Co., 1478- Cleaver-Brooks Co., 1544, 1580 ' 1479 Columbia Boiler Co., 1546-1547 General Fittiogs Co., 1596 Dewey-Shepard Boiler Co., 1550 Powers Regulator Co., The, 1496- Eddington Metal Specialty Co., 1591 1498 Ennteterprprinssee Enn.nggininee &s Mmaacchuinmeeryry OIL BURNING EQUIPMENT Airtemp Div., Chrysler Corp., 1248-1249 Aldrich Co., 1541 American Radiator & Standard Sanitary Corp., (Plumbing & Hnweawtiung DV,iv.). 1523-.4525 Taco Heaters, Inc., 1602 Co ~Burner *D"*i'v., Sub. of General Eddington Metal Specialty Co., 1591 Metals Corp., 1581 Enterprise Engine A Machinery MIXERS, Steam and Water Fitsgibbons Boiler Co., Inc., 1552- Co., Burner Div., Sub. of General oiSa. A^ -- Cmp.. &&& Wort, Rw*tr Co.. The. 1496- MOTORS, Damper Barber-Colman Co., 1437, 1473 Merooid Corp., The, 1489 Mueller Climatrol Div. of Worth ington Corp., 1254-1255 Orr A Sembower, Inc., 1562 Ray Oil Burner Co., 1584-1585 ington Corp., 1254-1255 National-U. S. Radiator Corp., 1530-1533 , Pacific Steel Boiler Div., National ly S. Radiator Corp., 1534-1535 Preferred Utilities Mfg. Corp., 1566 Ray Oil Burner Co., 1584-1585 Serve!, Inc., 1262-1263 Numerals following Manufacturers' Names refer to pages in the Catalog Data Section Index to Modern Equipment 1207 OIL BURNING SYSTEMS, In dustrial Enterprise Engine A Machinery Co., Burner Div., Sub. of General Metals Corp., 1581 PIPE BENDING Acme Industries, Inc., 1358 Parks-Cramer Co., 1236-1237 PIPE, Brass PLASTER BASE, Insulatire Celotex Corp., The, 1666 Insulite, 1668-1669 Wood Conversion Co., 1677 ' S. T. Johnson Co., 1582-1583 Preferred Utilities Mfg. Corp., 1566 Ray Oil Burner Co., 1584-1585 Rayfield-Staffeo Burner Co., Inc., 1586 American Brass Co., The, 1310-1311 Revere Copper and Brass Incor porated, 1313 PIPE CONDUITS (See Conduits, PLASTER BASE, Sound Dead ening . Celotex Corp., The, 1666 Insulite, 1668-1669 ' Wood Conversion Co., 1677 Underground Pipe) OIL TANK GAGES (See Gages, Tank) PIPE, Copper PLATES. Stainless Steel United States Steel, 1425 . American Brass Co.,- The, 1310-1311 ORIFICES. Radiator C. A. Dunham Co., 1618-1621 Illinois Engineering Co., 1626-1627 Revere Copper and Brass Incor PLATES, steel porated, 1313 United States Steel, 1425 ! . Johnson Service Co., 1484-1485 PIPE, Corrosion-Proof PNEUMATIC RELAYS (See Re Minneapolis-Honeywell Regulator Johns-Manville, 1670-1671 lays, Electrical and Pneumatic) Co., 1490-1491 National Clay Pipe Mfgrs., The, Warren Webster A Co., 1638-1639 1516-1521 PRECIPITATING EQUIPMENT Stillwater Clay Products Co., The Dollinger Corp., 1330-1331 ORNAMENTAL GRILLS (See 1652 Tnon, Inc., 1340 . Deflection Grilles, Grilles, Registers Westinghouse Electric Corp., Stur- and Ornamental Metal Work, Lou PIPE COVERING (See Covering tevant Div., 1342 ' vers, Registers) Pipe) PADS, Rubber Korfund Co., Inc., The, 1687 Vibration Mountings, Inc., 1688 PIPE, Fabricated Dutton Boilers; Div. Dutton Co., 1551 Hapman- PREFABRICATED DUCT CON NECTORS (See Duet Connectors, Prefabricated) .Farrar A Trefts Div., Adsco Indus PREHEATERS, Fuel Oil PANEL GRIDS (See Grids, Panel) . tries, Inc., 1554 American District Steam Div., Fluor Corp., Ltd., The, 1347 Adsco Industries, Inc., 1505, 1594 PANEL BOARD (For Mounting Stoker Controls) \Will-Burt Co.. The, 1569 PIPE FITTINGS Pipe) (See Fittings, Bell A Gossett Co., 1598-1599 E. B. Kaiser Co., 1648-1649 Kewanee Boiler Div., American- Standard. 1558-1561 PANEL HEATING American Radiator A Standard Sanitary Corp., (Plumbing & Heating Div.), 1523-1525 Crane Co., 1528-1529 Kritzer Radiant Coils, Inc., 1514 . PIPE, FURNACE (See Furnace Pipe and Fittings) PIPE, Gas Vent . Johns-Manville, 1670-1671 Metalbestoe Div., William Wallace Killebrew Engineering Corp., 1597 ' Preferred Utilities Mfg. Corp, 1566 Taco Heaters, Inc., 1602 . H. A. Thrush A Co., 1600-1601 Edwin L. Weigand Co., 1308-1309 Western Blower Co., 1409 Sarcotherm Controls, Inc., 1633 Shaw-Perkins Mfg. Co., 1515 Edwin L. Wiegand Co., 1308-1309 Co., 1592-1593 PIPE HANGERS Pipe) (See Hangers, ' PRESSURE REDUCING VALVES (See Regulators, Pres sure) ` : PANELS, Air Distributing Pyle-National Co., The, (Multi Vent Div.), 1454-1455 PIPE HEATING Edwin L. Wiegand Co., 1308-1309 Lfcriws, 1UV., lOlU, llOi Niagara Blower Co., 1235 PANELS, Celling (See' Ceiling, Panels) PERFORATED METALS A-J Mfg. Co., 1426-1427 Auer Register Co., 1436 Hart A Cooley Mfg. Co., 1444-1445 Hendrick Mfg. Co., 1446-1447 Pyle-National Co., The, (Multi Vent Div.), 1454-1455 Standard Stamping A Perforating Co., 1456 United States Register Co., 1462 1463 PIPE, Spiral Welded . Taylor Forge A Pipe Works, 1510 Trane Co., The, 1298-1301 L. J. Wing Mfg. Co., 1302-1303 PIPE. Steel Taylor Forge A Pipe Works, PROCESS HEATING UNITS, 1510 ` Fluid Heating and Cooling ; American District Steam Div., Adsco Industries, Inc., 1505, 1594 PIPE SUPPORTS. For Under Killebrew Engineering Corp., 1597 ground Conduits Arthur A. Olson A Co., 1279 American District Steam Div., Trane Co., The, 1298-1301 Adsco Industries, Inc., 1505, 1594 Edwin L. Wiegand Co., 1308-1309 Durant Insulated Pipe Co., 1647 Durant International Corp.. 1647 PROPELLER FANS (See Fans. E. B. Kaiser Co., 1648^1649 Propeller) H. W. Porter A Co., Inc., 1650 Reid Hayden, Inc., 1650 PSYCHROMETERS (See Air PILLOW BLOCKS Lau Blower Co., The, 1396-1397 Ric-wiL Co., The, 1651 Measuring, Indicating and Re Stillwater Clay Products Co., The 1652 cording Instruments) American Moistening Co., 1222 . PILOTS. Safety Z-Crete Div., Zonolite Co., 1653 Bahnson Cov The, 1223 ' Illinois Testing Laboratories, Inc.. General Controls, 1480-1481 Milwaukee Gas Specialty Co., 1492 Penn Controls, Inc., 1494 White-Rodgers Electric Co., 1504 PIPE ALIGNMENT GUIDES American District Steam Div., PIPE VITRIFIED CLAY, Heat ing Ducts National Clay Pipe Mfgrs., The. 1516-1521 Stillwater Clay Products Co.. The, 1652 1486 Johnson Service Co., 1484-1485 Moeller Instillment Co., 1493 Parks-Cramer Co., 1236-R37 Powers Regulator Co., 1496-1498 Taylor Instrument Cos., 1503 ' Adsco Industries, Inc., 1505, 1594 PIPE ANCHORS American District Steam Div., Adsco Industries, Inc., 1505, 1594 PITOT TUBES (See Air Measuring and Recording Instruments) ' PLASTER BASE, Fire Retarding Celotex Corp., The, 1666 PUBLICATIONS Air Conditioning, Heating and Ventilating, 1689 American Artisan, 1694 : American Society of Refrigerating Engineers, 1690 - Please mention THE GUIDE 1956 when writing to Advertisers Coal-Heat, 1691 Domestic Engineering, 1C92 Heating & Plumbing Equipment News, 1689 ,. Heating A Air Conditioning Con tractor, 1693 ,. Heating, Piping and Air Condition ing, 1694 ', Journal of Plumbing-Heating A Air Conditioning, The, 1693 Snips Magazine, 1695 PUMP CONTROLLERS (See Contrailers, Pump) Buffalo Pumps, 1604 Chicago Pump Co., 1608-1607 Crane Co., 1528-1529 Domestic Pump A Mfg. Corp., 1605 C. A. Dunham Co., 1618-1621 Hoffman Specialty Mfg. Corp., 1622-1625 Illinois Engineering Co., 1626-1627 Nash Engineering Co., The, 1608 1609 Sarco-Sarcotherm, 1633-1635 Skidmore Corp., 1611 Sterling, Inc.. 1502 Trane Co., The, 1298-1301 Crane Co., 1528-1529 Electrcmode Corp., 1305 Hoffman Specialty Mfg. Corp., 1622 1625 Hydrotherm, Inc., 1555 Kritzer Radiant Coils. Inc., 1514 National-U. S. Radiator Corp., 1530-1533 Raypak Co., Inc., 1563 Sarcotherm Controls, Inc., 1633 Shaw-Perkins Mfg. Co., 1515 Weil-McLain Co., 1540 Wesix Electric Heater Co., 1307 Edwin L. Wiegand Co., 1308-1309 PUMP MOTORS (See Electric) PUMPS, Ammonia Worthington Corp., 1241 . York Corp., 1242 Motors, PUMPS, Fuel Oil Kmiftsl Co., Inc., The, 1610 . Preferred Utilities Mfg. Corp., 1666 Ray Oil Burner Co., 1584-1585 Rayfield-Staffco Burner Co., Inc., 1586 RADIATION, Aluminum Kritzer Radiant Coils, Inc., 1514 Shaw-Perkins Mfg. Co., 1515 Slant-Fin Radiator Corp., 1366 Trane Co., The, 1298-1301 Young Radiator Co., 1304 PUMPS, Boiler Feed Aurora Pump Div., The New York Air Brake Co., 1603 Buffalo Pumps, Inc., 1604 . Chicago Pump Co., 1606-1607 Crane Co., 1528-1529 Domestic Pump A Mfg. Corp., 1605 PUMPS, Sump Aurora Pump Div., The New York Air Brake Co., 1603 Buffalo Pumps, 1604 Chicago Pump Co., 1606-1607 Skidmore Corp., 1611' C. A. Dunham Co., 1618-1621 Dutton Boilers, JDiv. Hapman- Dutton Co., 1551 Hoffman Specialty Mfg. Corp., 1622-1625 Nash Engineering Co., The, 1608 PUMPS, Turbine Aurora Pump Div., The New York Air Brake Co., 1603 Chicago Pump Co., 1606-1607 Skidmore Corp., 1611 1609 Skidmore Corp., 1611 PUMPS, Vacuum Spence Engineering Co., Inc., 1501' Chicago Pump Co., 1606-1607 Sterling, Inc., 1502 Domestic Pump & Mfg. Corp., 1605 Worthington Corp., 1241 . C. A. Dunham Co., 1618-1621 Joy Mfg. Co., 1394-1395 PUMPS, Brine Kraissl Co., Inc., 1610 Aurora Pump Div., The New York Nash Engineering Co., The, 1608 Air Brake Co., 1603 ` 1609 Buffalo Pumps, Inc., 1604 Sarco-Sarcotherm, 1633-1635 RADIATION, Baseboard, Fer rous American Radiator A Standard Sanitary Corp., (Plumbing A Heating Div.), 1523-1525 Burnham Corp., 1526-1527 Crane Co... 1528-1529 C. A. Dunham Co., 1618-1621 Fedders-Quigan Corp., 1286 Kritzer Radiant Coils, Inc., 1514 Kittling Corp., The 1364 Sarcotherm Controls, Inc., 1633 Shaw-Perkins Mfg. Co., 1515 Slant-Fin Radiator Corp., 1366 H. B. Smith Co., Inc., The, 1537 Trane Co., The. 1298-1301 National-U. S. Radiator Corp., 1530-1533 Union Asbestos A Rubber Co., 1265 Vulcan Radiator Co., The, 1367 Weil-McLain Co., 1540 Wesix Electric Heater Co.,. 1307 ' Chicago Pump Co., 1606-1607 Skidmore Corp., 1611 Domestic Pump A Mfg. Corp., 1605 Sterling, Inc., 1502 Worthington Corp., 1241 Worthington Corp., 1241 RADIATION, Baseboard ' Non- ferrous ,. American Radiator A Standard PUMPS. Centrifugal Aurora Pump Div., The New York Air Brake Co., 1603 Bell A Gossett Co., 1598-1599 PUMPS, Water Supply Aurora Pump Div., The New York Air Brake Co., 1603 Sanitary Corp. (Plumbing Heating Div.), 1523-1525 Columbia Boiler Co., 1546-1547 C. A. Dunham Co., 1618-1621 A Buffalo Pumps, 1604 Chicago Pump Co., 1606-1607 Domestic`Pump A Mfg. Corp., 1605 PURGERS, Refrigeration Armstrong Machine Works, C. A. Dunham Co., 1618-1621 1615 KVaisal Co., Inc., The, 1610 York Corp., 1242 1614-- Fedders-Quigan Corp., 1286 GAO Mfg. Co., The, 1362 General Automatic Products Corp., 1513 Hoffman Specialty Mfg. Corp., 1622-- Skidmore Corp., 1611 1625 . Taco Heaters, Inc., 1602 PURIFIERS AND SCRUBBERS, Kritzer Radiant Coils, Inc., 1514 Trane Co., The, 1298-1301 Air Gas and Steam National-U. S. Radiator Corp., Worthington Corp., 1241 V. D. Anderson Co., The, 1612-1613 1530-1533 ,. Herman Nelson, American Air PUMPS, Circulating (See Cir culators) Aurora Pump Div., The New York Air Brake Co.,1603 Bell A Gossett Cb., 1598-1599 Buffalo Pumps, 1604 Chicago Pump Co., 1606-1607 Domestic Pump A Mfg Corp., 1605 C. A. Dunham Co., 1618-1621 Ifraissl Co., Inc., 1610 . Minneapolis-Honeywell.. .Regulator Co., 1490-1491 . Toco Heaters, Inc., 1602 PYROMETERS, Portable and Stationary _ Illinois Testing Laboratories, 1486 Minneapolis-Honeywell Regulator Co., 1490-1491 QUADRANTS, Damper Duro-Dyne Corp., 1466-1467 RADIANT COOLING Burgess-Maiming Co., 1438 Filter Co., Inc., 1296-1297 ' John J. Nesbitt, Inc., 1293-1295 Rittling Corp., The, 1364 ' Sarcotherm Controls, Inc., 1633 Shaw-Perkins Mfg. Co., 1515 Slant-Fin Radiator Corp., 1366 H. B. Smith Co., Inc., The, 1537 Trane Co., The, 1298-1301 Tuttle & Bailey, Inc., 1460-1461 Union Asbestos A Rubber Co., 1265 Vulcan Radiator Co., The, 1367 Warren Webster A Co., 1638-1639 York-Shipley, Inc., 1590 H. A. Thrush A Co., 1600-1601 RADIANT HEATING Trane Co., The, 1298-1301 American Radiator A Standard RADIATION, Cast-Iron Worthington Corp., 1241 Sanitary Corp., (Plumbing & American Radiator A Standard Heating Div.), 1523-1525 Sanitary Corp., (Plumbing A PUMPS, Condensation Burgess-Manning Co., 1438 Aurora Pump Div., The New York Burnham Corp., 1526-1527 Air Brake Co., 1603 Campbell Heating Co., 1268-1269 Heating Div.), 1523-1525 Burnham Corp., 1526-1527 Crane Co., 1528-1529 Numerals following Manufacturers' Names refer to pages in the Catalog Data Section fi Index to Modem Equipment 1209 D. J. Murray Mfg. Co., 1292 Natiou&l-U. S. Radiator Corp., 1530-1533 Weil-McLain Co., 1540 Fedders-Quigan Corp., 1286 Modine Mfg. Co., 1290-1291. National-U. S. Radiator Corp., 1530-1533 REFRIGERATING MENT, Absorption Carrier Corp., 1226-1227 EQUIP. RADIATION, Copper Airtherm Mfg. Co., 1522 C. A. Dunham Co., 1618-1621 Fedders-Quigan Corp., 1286 1 GAO Mfg. Co., The, 1362 General Automatic Products Corp., 1513 Herman Nelson, American Air Filter Co., Inc., 1296-1297 Rittling Corp., The, 1364 Shaw-Perkins Mfg. Co., 1515 Slant-Fin Radiator Corp., 1366 Union Asbestos A Rubber Co., 1265 Weil-McLain Co., 1540 Young Radiator Co., 1304 REFRIGERATING EQUIP. MENT, Centrifugal Bell A Gossett Co., 1598-1599 Carrier Corp.. 1226-1227 Trane Co., The, 1298-1301 Worthington Corp., 1241 York Corp., 1242 Hoffman Spcialty Mfg. Corp., 1622 1625 . Modine Mfg. Co., 1290-1291 Rittling Corp., The, 1364 RADIATORS, Concealed Airtherm Mfg. Co., 1522 ,. American Radiator A Standard REFRIGERATING MENT, Steam Jet Worthington Corp., 1241 EQUIP -' Shaw-Perkins Mfg. Co., 1515 Slant-Fin Radiator Corp., 1366 Sanitary Corp. (Plumbing & Heating Div.), 1523-1525 Trane Co., The, 1298-1301 Burnham Corp., 1526-1527 Union Asbestos A Rubber Co., 1265 Crane Co., 1528-1529 York-Shipley, Inc., 1590 C. A. Dunham Co., 1618-1621 Young Radiator Co., 1304 Fedders-Quigan Corp., 1286 Kritzer Radiant Coils, Inc., 1514 RADIATION, Plain, Extended Modine Mfg. Co., 1290-1291 . Surface . . . National-U.S. Radiator Corp.. American Radiator A Standard 1530-1533 Sanitary Corp., (Plumbing A Herman Nelson, American Air Heating Div.), 1523-1525 Filter Co., Inc., 1296-1297 Burgess-Manning Co., 1438 Rittling Corp., The, 1364 C. A. Dunham Co., 1618-1621. Shaw-Perkins Mfg. Co., 1515 Fedders-Quigan Corp., 1286 G A O Mfg. Co., The, 1362 Slant-Fin Radiator Corp., 1366 Union Asbestos & Rubber Co., 1265 General Automatic Products Corp., Warren Webster A Co., 1638-1639 1513 . Weil-McLain Co., 1540 .. Modine Mfg. Co., 1290-1291 Young Radiator Co., 1304 REFRIGERATING MACHIN ERY Addison Products Co., 1243 Airtemp Div., Chrysler Corp., 1248 1249 : American Blower Corp., 1220-1221 Brunner Mfg. Co., 1368 ' Carrier Corp., 1228-1227 . Curtis Mfg. Co., Refrigeration Div., 1370 Copeland Refrigeration Corp., 1369 Frick Co., 1371 Niagara Blower Co., 1235 Ready-Power Co., The, 1372 , . Refrigeration Engineering, Inc.* 1373 . Servel, Inc., 1262-1263 Trane Co., The, 1298-1301 Worthington Corp., 1241 . , \ National-U. S. Radiator Corp., 1530-1533 . Herman Nelson, American Air Filter Co., Inc., 1296-1297 John J. Nesbitt, Inc., 1293-1295 ' Rittling Corp., The, 1364 Sarcotherm Controls, Inc., 1633 Shaw-Perkins Mfg. Co., 1515 . Slant-Fin Radiator Corp., 1366 H. B. Smith Co., Inc., The, 1537 Trane Co., The, 1298-1301 Union Asbestos A Rubber Co., 1265 Warren Webster A Co., 1638-1639 Young Radiator Co., 1304 RANGES, Cooking. Hotel, Hos York Corp., 1242 pital, etc. - Air Devices, Inc., 1316, 1432 REFRIGERATION CONTROLS Ray Oil Burner Co., 1584-1585 Alco Valve Co., Inc., 1472 General Controls, 1480-1481 - . RECEIVERS, Air Hubbell Corp., The, 1483 Curtis Mfg. Co., Refrigeration Div., Mercoid Corp., The, 1489 1370 Penn Controls, Inc., 1494 Farrar A Trefts Div., Adsco In White-Rodgers Electric Co., 1504 dustries, Inc., 1554 International Boiler Works The, 1556 Joy Mfg. Co., 1394-1395 Co., REFRIGERATION TUBE, Cop ' per (See Tubes and Tubing, Cop per) -- Worthington Corp., 1241 . RADIATION, Underfloor National Clay Pipe Mfgrs., The, 1516-1521 RADIATOR BRACKETS (See Brackets, Radiator) RECEIVERS, Condensation REGISTERS (See Grilles, Registers Domestic Pump A Mfg. Corp., 1605 Hoffman Specialty Mfg. Corp., 1622-1625 Illinois Engineering Co., 1626-1627 Worthington Corp., 1241 and Ornamental' Metal Work) A-J Mfg. Co., 1426-1427 Air Control Products, Inc., 1428 1431 Air-Factors, Inc., 1433 Auer Register Co., The, 1436 radiator enclosures AND SHIELDS . American Radiator A Standard Sanitary Corp., (Plumbing A Heating Div.), 1523-1525 RECEIVERS, Refrigerants Acme Industries, Inc., 1358 Worthington Corp., 1241 York Corp., 1242 B&rber-Colman Co., 1437, . 1473 Dole Valve Co., The, 1640 General Register Corp.,-1442-1443 Hart A Cooley Mfg. Co., 1444-1445 Hendrick Mfg. Co., 1446-1447 National-U. S. Radiator Corp., 1530-1533 Sarcotherm Controls, Inc., 1633 Slant-Fin Radiator Corp., 1366 Somers Corp., 1339 RADIATOR HANGERS (See Hangers, Radiator) RECORDERS, Humidity, Tem perature . American Moistening Co., 1222 Electric Auto-Lite Co., The Instru ment A Gauge Div., 1476 Johnson Service Co., 1484-1485 Moeller Instrument Co., 1493 Powers Regulator Co., The, 1496 Independent Register Co.,' The. 1448 Lima Register Co., 1450-1451 Louvra Mfg. A Sales Co., 1452 National-U.S. Radiator Corp., 1530-1533 Pyle-National Co:, The, (Multi Vent Div.), 1454-1455 Radiator tors heat reflec 1498 ' Taylor Instrument Cos., 1503 Register A Grille Mfg. Co., Inc., 1453 Stewart Mfg. Co., Inc., 1457 Infra Insulation, Inc., 1679 Peflectal Corp., 1682 Sflvercote Products, Inc., 1680-1681 RADIATORS, Cabinet Airtherm Mfg. Co., 1522 American Radiator A Standard Sanitary Corp. (Plumbing A Heating Div.), 1523-1525 Crane Co., 1528-1529 C. A. Dunham Co., 1618-1621 REFRACTORIES, Cement. Ma terials Armstrong Cork Co. (Building Ma terials Div.), 1665 Babcock A Wilcox Co., The, 1542 Philip Carey Mfg. Co., The, 1656 1657 . Johns-Manville, 1670-1671 REFRIGERANT DRIERS (See Driers, Refrigerant) Titus Mfg. Corp., 1458-1459 Tuttle A Bailey, Inc., 1460-1461 United States Register Co., 1462 1463 Waterloo Register Co., Inc., 1465 Young Regulator Co., 1470-1471 REGULATORS. Air Volume A-J Mfg. Co., 1426-1427 Barber-Colman Co., 1437, 1473 Duro-Dyne Corp., 1466-1467 Please mention THE GUIDE 1956 when writing to Advertisers 1210 1956 Guide Hart & Cooley Mfg. Co., 1444-1445 _S_ w_artwo_ut Co-, The^ 1423 Strong, Carlisle & Hammond Co., Powers Regulator Co., 1496-1498 EL~A Thrush & Co., 1600-1601 1637 Young Regulator Co., 1470-1471 Waifen Webster & Co., 1638-1639 Dl -- SEPARATORS, Blow Down REGULATORS,: Remote Con- Pennsylvania Separator Co., 1574 REGULATORS. Back Pressure Alco Valve Co., 1472 Aler^V&lve Co 1472 - SEPARATORS, Dust Hubbell Corp., 1483 . FuUon Sylpbon Div., The, Robert- Ameri<*nAir Filter Co.. 1319-1321 shaw-Fulton Controls Co., 1470- V. D. Anderson Co., The, 1612-1613 REGULATORS, Damper 1479 - Dollinger Corp., 1330-1331 A-J Mfg. Co., 1426-1427 .Hubbell Corp., 1483 Farr Co., 1332-1333 Barber-Colman Co., 1437, 1473 Duro-Dyne Corp., 1466-1467 COnkey SSS^elf9 Regulator fo"^de^uC^The, 1612-1613 HaVtcg. Mfg. Co.,= Pc^-C>"luc., H94 ^ Minneapolis,Honeywell Regulator PowerB Co,, 1496-1498 Po^ere Rotator Co., The, 1496- Young Regulator Co., 1470-1471 1498 REGULATORS. Temperature Spence Engineering Co., Inc., 1501 (See Temperature Control) Trane Co., The, 1298-1301 -. Young Regulator Co., 1470-1471 - REGULATORS, Time Controls SEPARATORS, Oil Acme Industries, Inc., 1358 Air-Maze Corp., 1318 . DolUnger Corp., 1336-1331 Rbnpis Engineering Co 1626-1627 TCraiasI Co., Inc., The, 1610 York Corp., 1242 REGULATORS, Draft . Si^S'pSiSe^ll'^Regulator SEPARATORS, Refrigmaut Oil Field Control Div., of H. D.' Conkey Co. 1490-1491 ' Acme Industries, Inc., lioo & Co., 1477 Simplex Mfg. Co., 1500 . Powers Regulator Co., The, 1498 1496- SEPARATORS, Steam American District Steam Div., REGULATORS, Pressure Alco Valve Co., 1472 Evaporator RELAYS Electrical and Pneu '. matic Potter A Brumfield, 1495 ' Hubbell Corp., The, 1483 Adsco Industries, Inc., 1505, 1594 V. D. Anderson Co., The, 1612-1613 Illinois Engineering Co., 1626-1627 _ Pennsylvania Separator Co., 1574 REGULATORS, ' Feed Water Heller Laboratories, Inc., 1352 RELIEF Relief) VALVES (See Voice, Strong, Carlisle A Hammond, Co., - 1637 . McDonnell 1573 A Miller, Inc., 1570 RESTRICTOR TUBING Tubing, Restrictor) (See SHEET METAL TOOLS (See Tools, Sheet Metal) REGULATORS, Furnace Field Control.Div. of H. D. Conkey A Co., 1477 Mercoid Corp., The, 1489 Minneapolis-Honeywell Regulator Co., 1490-1491 Penn Controls, Inc., 1494 White-Rodgers Electric Co., 1504 RINGS. Backing Robvon Backing Ring. Co., The, 1509 RINGS, Chill _ Robvon Backing Ring Co., The, 1509 SEPARATORS. Vapor V. D. Anderson Co., The, 1612-1613 SHEETS, Aluminum Revere Copper and Brass Incor porated, 1313 SHEETS, Asbestos. Flat, and RINGS, Machined Corrugated . . REGULATORS, Gas Robvon Backing Ring Co., The PhiUp Carey Mg., Co., The, 1656 General Controls, 1480-1481 Maxitrol Co., 1488 1509 1557 . - Johns-Manville, 1670-1671 Minneapolis-Honeywell Regulator K'SSk, Co.. The, Co., 1490-1491 BUM... Penn Controls, Inc., 1494 Webster Engineering Co., The, 1579 REGULATORS, Humidity (See Humidity Control) REGULATORS, Pressure Alco Valve Co., 1472 Bell A Gossett Co., 1598-1599 A. W. Cash Co., 1617 C. A. Dunham Co., 1618-1621 Tube Turns, A Div. of National Cylinder Gas Co., 1511 ROOF COOLERS . April Showers Co., Inc., 1644 Muellermist Irrigation Co., 1645 RUST PREVENTATIVE Corrosion, Treatment of) ..... _........... . _ (See Revere Copper and Brass, Incor- porated, 1313 ... Standard Stamping A Perforating Co., 1456 SHEETS, Copper Bearing Steel United States Steel, 1425' SHEETS. Galvanized Steel United States Steel, 1425 Fulton Sylphon Div., The Robert- SAFETY CONTROLS (See Burner High-Strength Steel shaw-Fulton Controls Co., 1478" 1479 General Controls, 1480-1481 Hoffman Speciality Mfg. Corp., 1622-1625 Protection, OGans* aanndd. Oil)! SAFETY VALVES (See Safety) Valves, U-ni-ted- States S-teel, 1425 SHEETS, Porcelain Enameling United States Steel, 1425 Hubbell Corp., The, 1483 fSEIAJuminum & Chemical 'SHEETS. Sp<gtal Fbdsh Illinois Engineering Co., 1620-1627 Johnson Service Co., 1484-1485 Sales, Ine., 1684-1685 United States Steel, 1425 Leslie Co., 1487 _ Reflectal Corp., 1682 SHEETS. Stainless Steel Jas. P. Marsh Corp., 1628-1629 Maxitrol Corp., 1488 SCREENS. Perforated Metal American Flange & Mfg. Co., Inc., McDonnell A Miller, Inc., 1570-1573 Hendrick Mfg. Co.. 1446-1447 g & Perforating Mercoid Corp., The, 1489 Monarch Mfg. Works, Inc., 1357 Penn Controls, Inc., 1494 Powers Regulator Co., The, 1496 1498 Spence Engineering Co., Inc., 1501 Strong, Carlisle A Hammond Co., 1637 SEPARATORS, Air V. D. Anderson Co., The, 1612-1613 Barnebey-Cbeney Co., 1322-1323 Dollinger Corp., 1330-1331 C A Dunham Co., 1618-1621 Pur Air Div., Bamebey-Cheney Co., 1322-1323 Co., 1456 United States Steel, 1425 ' __ ^___ ' SHEETS, Steel ' American Flange A Mfg. Co., Inc., ,1678 , c. . 1J9_ United States Steel, 1425 Numerals following Manufacturers' Names refer to pages In the Catalog Data Section Index to Modem Equipment 1211 SHUTTERS, Automatic American Foundry A Furnace Co., 1266-1267 r Ilg Electric Ventilating Co., 1287, 1393 . Herman Nelson, American Air Filter Co., Inc., 1296-1297 Peerless Electric Co., The, 1400 Reed Unit-Fans, Inc., 1402 L. J. Wing Mfg. Co., 1302-1303 Buensod-Stacey, Inc., 1224 Buffalo Forge Co., 1382 ' Fluor Corp., Ltd., The, 1347 Marley Co., The, 1354 Monarch Mfg. Works, Inc., 1357 D. J. Murray Mfg. Co., 1292 STEAM AND WATER MIXERS (See Mixers, Steam and Water) STRAINERS. Gas - V. D. Anderson Co., The, 1612-1613 Hubbell Corp., 1483 Maid-O'-Mist, Inc., 1630-1632 STRAINERS. Oil V. D. Anderson Co., The, 1612-1613 Armstrong Machine Works, 1614-- 1615 . Bell & Gossett Co., 1590-1599 SIGNAL. Liquid Level Scully Signal Co., 1499 SIGNAL, Tank Filling Scully Signal Co., 1499 STEAM GENERATORS. Unit Babcock <fc Wilcox Co., The, 1542 Combustion . Engineering. Inc.. 1548-1549 Cyclotherm Div. of National-U.S. Radiator Corp., 1545 Hubbell Corp., The, 1483 Kraissl Co.. Inc., The, 1610 Monarch Mfg. Works, Inc., 1357 Sarco Co., Inc., 1634-1635 Spence Engineering Co., Inc., 1501 Sterling, Inc., 1502 SKYLIGHTS, Insulated American 3 Way-Luxfer Prism Co., 1660 Owens-Illinois, 1661 ' Pittsburgh Coming Corp., 1663 SKYLIGHTS, Metal and Ven tilating . American 3 Wav-Luxfer Prism Co.. 1660 * SLAB, Heating Concrete National Clay Pipe Mfgrs.,. ..The, 1516-1521 SMOKE DETECTORS AND IN DICATORS (For Flues . and Ducts) . Combustion Control Div., Elec tronics Corp. of America, 1475 Tnon, Inc., 1340 Dutton Boilers, Div. HapmanDutton Co., 1551 Farrar & Trefts Div., Adsco In dustries, Inc., 1554 Fitzgibbons Boiler Co., Inc., 1552 1553 Johnston Brothers, Inc., 1557 Orr A Sembower, Inc., 1562 Preferred Utilities Mfg. Corp., 1566 Titusville Iron Works Co., 1564-1&65 Vapor Heating Corp., 1567 Worthington Corp., 1241 York-Shipley, Inc., 1590 STEAM HEATING SYSTEMS (See Heating Systems, ' Steam) STEEL INSULATION (See In sulation, Steel) STOKER MOTORS (See Motors, Electric) STRAINERS, Refrigerant Alco Valve Co., 1472 Henry Valve Co., 1482 Hubbell Corp., The, 1483 Maid-O'-Mist, Inc., 1630-1632 Penn Controls, Inc., 1494 Sarco Co., Inc., 1634-1635 STRAINERS, Steam Alco Valve Co., 1472* American District Steam Div., Adsco Industries, Inc., 1505, 1594 V. D. Anderson Co., The, 1612-1613 Armstrong Machine Works, 1614-- 1615 A. W. Cash Co., 1617 Crane Co., 1528-1529 C. A. Dunham Co., 1618-1621 Illinois Engineering Co., 1626-1627 Kraissl Co., Inc., The, 1610 Leslie Co., 1487 Sarco Co., Inc., 1634-1635 SMOKE VENTILATORS Ventilators, Smoke) SOOT DESTROYER John Zink Co., 1588-1589 (See Spence Engineering Co., Inc., 1501 STOKERS. Mechanical, Anthra Sterling, Inc., 1502 cite Strong, Carlisle & Hammond Co., Airtemp Div., Chrysler Corp., 1248 1637 1249 Trane Co., The, 1298-1301 SOUND DEADENING (See Vibra tion Absorbers) SOUND ISOLATORS Korfund Co., Inc., The, 1687 Vibration Mountings,'Inc., 1688 SPOT WELDERS (See Welders, Spot) SPRAY DRYER'(See Spray Equip ment) SPRAY EQUIPMENT Bayley Blower Co., 1376 Bmks Mfg. Co., 1344-1345 Monarch Mfg. Works, Inc., 1357 D. J. Murray Mfg. Co., 1292 Combustion Engineering. 1548-1549 Detroit Stoker Co., 1568 Ihc STOKERS, Mechanical, Bitu minous - Airtemp Div., Chrysler Corp., 1248 1249 - ' Combustion Engineering, Inc., 1548 1549 Crane Co., 1528-1529 Detroit Stoker Co., 1568 Will-Burt Co., The, 1569 STOKERS, Refuse Burning Combustion Engineering, Inc., 1548- Detroit Stoker Co., 1568 STRAINERS, Water Aloo Valve Co., 1472 American District Steam Div., Adsco Industries, Inc:, 1505, 1594 V. D. Anderson Co., The, 1612-1613 Armstrong Machine Works, 1614-- 1615 . A. W. Cash Co., 1617 Hubbell Corp., The, 1483 Illinois Engineering Co., 1626-1627 Kraissl Co., Inc., The, 1610 Leslie Co., 1487 Maid-O'-Mist, Inc., 1630-1632 Monarch Mfg. Works, Inc., 1357 Penn Controls, Inc., 1494 Sarco Co., Inc., 1634-1635 Spence Engineering Co., Inc., 1501 Sterling, Inc., 1502 Trane Co., The, 1298-1301 STRAINERS, Air Maid-O'-Mist, Inc., 1630-1632 SWITCHES, Electric and Time American Moistening Co., l: April Showers Co., 1644 April Showers Co., Inc., 1644 Bahnson Co., The, 1223 ginks Mfg. Co., 1344-1345 . Fluor Corp., Ltd., The, 1347 ^I353offman Cooling Towers, In STRAINERS. Dirt American District Steam Div., Adsco Industries, Inc., 1505. 1594 . V. D. Anderson Co., The, 1612-1613 SWITCHES. Float Alco Valve Co., 1472 McDonnell & Miller, Inc., 1570-1573 Mercoid Corp., The, 1489 Marley Co., The, 1354 Monarch Mfg. Works, Inc., 1357 k>.J. Murray Mfg. Co., 1292 Cooling Tower Co., In 1356 SPRAY NOZZLES American Moistening Co., 1222 April Showers Co., Inc., 1644 oannsoii Co., The, 1223 Bmks Mfg. Co., 1344-1345 Armstrong' Machine Works, 1614-- 1615 C. A. Dunham Co., 1618-1621 Eddington Metal Specialty Co. 1591 Hoffman Speciality Mfg. Corp., 1622-1625 Illinois Engineering Co., 1626-1627 Kraissl Co., Inc., The, 1610 Sarco Co., Inc., 1634-1635 Sterling, Inc., 1502 . Warren Webster & Co., 1638-1639 SWITCHES, Flow Control McDonnell & Miller, Inc., 1570-1573 SWITCHES, Mercury Mercoid Corp., The, 1489 Minneapolis-Honeywell Regulator Co., 1490-1491 SWITCHES, Pneumatic Powers Regulator Co.. The, 1495 1498 Please mention THE GUIDE 1956 when writing to Advertisers 1212 1956 Guide SWITCHES, Stack Safety Minneapolis-Honeyweil Regulator Co., 1490-1491 Penn Controls, Inc., 1494 White-Rodgers Electric Co., 1504 Sarco Co., Inc., 1634-1635 . Taylor Instrument Cos., 1503 - ' THERMOMETERS, Indicating Electric Auto-Lite Co., The, Instru ment & Gauge Div., 1476 Crane Co., 1528-1529 C. A. Dunham Co., 1618-1621 Hoffman Speciality Mfg. Corp., 1622-1625 Jas. P. Marsh Corp., 1628-1629 Sarco Co., Inc., 1634-1635 SWITCHES, Time April Showers, Inc., 1644 General Controls, 1480-1481 Fulton Sylphon Div., The, Robert- Strong, Carlisle & Hammond Co., shaw-Fulton Controls Co., 1478 1637 1479 .. Trane Co., The, 1298-1301 Illinois Testing Laboratories, rnc., TANK COILS (See Coils, Tank) 1486 TRAPS, Float Johnson Service Co., 1484-1485 V. D. Anderson Co., The, 1612-1613 TANK COVERING (See Covering Jas. P. Marsh Corp-* 1628-1629 Armstrong Machine Works, 1614-- Pip*) ' Minneapolis-Honeywell Regulator 1615 Co., 1490*1491 Barnes & Jones, Inc., 1616 ' TANK HEATERS (See Heaters, Moeller Instrument Co., 1493 Crane Co., 1528-1529 Tank) TANKS, Blow-off American District Steam Powers Regulator Co., The, 1496 1498 . Sarco Co., Inc., 1634-1635 Div., Taylor Instrument Cos., 1503 C. A. Dunham Co., 1618-1621 Hoffman Speciality Mfg. Corp., 1622-1625 . Illinois Engineering Co., 1626-1627 Adsco Industries, Inc., 1505, 1594 Jas. P. Marsh Corp., 1628-1629 International Boiler Works Co., THERMOMETERS, Recording Sarco Co., Inc., 1634-1635 The, 1556 Electric Auto-Lite Co., The Instru Strong, Carlisle & Hammond Co., ment & Gauge Div., 1476 1637 TANKS, Pressure Johnson Service Co., 1484-1485 Trane Co., The, 1298-1301 Farrar & Trefte, Div., Adsco In Minneapolis-Honeyweil Regulator dustries, Inc., 1554 , Co., 1490-1491 TRAPS, Float and Thermostatic International Boiler Works Co., Moeller Instrument Co., 1493 V. D. Anderson Co., The, 1612-1613 The, 1556 . , Powers Regulator Co., The, 1496 Barnes 4 Jones, Inc.,1616 Killebrew Engineering Corp., 1597 1498 C. A. Dunham Co., 1618-1621 Trane Co., The, 1298-1301 Hoffman Speciality Mfg. Corp., TANKS, Storage THERMOSTATS Barber-Colman Co., 1437. 1473 1528-1529 . . __ Illinois Engineering Co., 1626-1627 Rheem Mfg. Co., 1260-1261 Cam-Stat, Inc., Div. of the Paul Jas. P. Marsh Corp., 1628-1629 Western Blower Co., 1409 Henry Co., 1474 . Sarco Co., Inc., 1634-1635 TEMPERATURE CONTROL Barber-Colman Co., 1437, 1473 Cam-Stat, Inc., Div. of the Paxil Henry Co., 1474 Combustion Control Div., Electron Combustion Control Div., Electron ics Corp. of America, 1475 Crane Co., 1528-1529 , Fulton Sylphon Div., The, Robert- shaw-Fulton Controls Co., 1478 1479 Sterling, Inc., 1502 . Strong, Carlisle & Hammond Co., 1637 ` Trane Co., The, 1298-1301 Warren Webster & Co., 1638-1639 ics Corp. of America, 1475 General Controls. 1480-1481 TRAPS, Radiator Crane Co., 1528-1529 __ C. A.Dunham Co., 1618-1621 Fulton-Sylphon Div., The Robert- shaw-Fulton Controls Co., 1478 Hoffman Speciality Mfg. Corp., 1622-1625 ,, Johnson Service Co., 1484-1485 Mercoid Corp., The, 1489 Barnes 4'Jones, Inc., 1616 Crane Co., 1528-1529 C. A. Dunham Co., 1618-1621 Hoffman Speciality Mfg. Corp., ' 1479 . - General Controls^ 1480-1481 Hoffman Speciality Mfg. Corp., 1622-1625 . Illinois Engineering Co., 1626-1627 Illinois Testing Laboratories, Inc., I486 __ Minneapolis-Honeyweil Regulator Co., 1490-1491 Penn Controls, Inc., 1494 ` Powers Regulator Co., The 1496 1498 Sarco Co., Inc., 1634-1635 Sarcothenn Controls, Inc., 1633 1622-1625 Illinois Engineering Co., 1626-1627 Jas. P. Marsh Corp., 1628-1629 Sarco Co.. Ino., 1633-1634 Sterling, Inc.. 1502 TraneCo., The. 1298-1301 Johnson Service Co., 1484-1485 H. A. Thrush & Co.,' 1600-1601 TRAPS, Return Leslie Co., 1487 Jas. P. Marsh Corp., 1628-1629 . Mercoid Corp., 1489 Minneapolis-Honeywell Regulator Co., 1490-1491 Wesix Electric Heater Co., 1307 White-Rodgers Electrio Co., 1504 Edwin L. Wiegand Co., 1308-1309 TIME SWITCHES OSes Switches, Crane Co., 1528-1529 C. A. Dunham Co., 1618-1621 Hoffman Speciality Mfg., Corp., 1622-1625 Illinois Engineering Co., 1626-1627 Penn Controls, Inc., 1494 Time) Powers Regulator Co., The, 1496- 1498 TIMERS, Electric, Interval Jas. P. Marsh Corp., 1628-1629 Trane Co., The, 1298-1301 Sarco-Sarcotherm, 1633-1635 Barber-Colman Co., 1437, 1473 TRAPS, Scale _ / Spence Engineering Co., Inc., 1501 Sterling, Inc., 1502 TOOLS, Sheet Metal Taylor instrument Cos., 1503 . Duro-Dyne Corp., 1466;-1467 Henry Valve Co.j 1482 Illinois Engineering Co., 1626-1627 Warren Webster & Co., 1638-1639 Wesix Electric Heater Co., 1307 . Young Regulator Co., 1470-1471 TOWERS, Cooling. Towers) (See Cooling TRAPS, Scale, Refrigerant Henry Valve Co., 1482 i TEMPERING VALVES Voltes, Tempering) (See TRANSFORMERS a General Controls, 1480-1481 TRAPS, Steam ___ y. d. Anderson Co., The, 1612-1613 Armstrong Machine Works, 1614 THERMOMETERS, Distance TRAPS Air V. D. Anderson Co., The, 1612-1613 Electric Auto*Lite Co., The Instru Armstrong Machine Works, 1614-- ment & Gauge Div., 1476 1615 ,, Illinois Testing Laboratories, Inc., -Sarco Co., Inc., 1634-1635 1486 Strong, Carlisle & Hammond Co., Jas. P. Marsh Corp., 1628-1629 1637 Minneapolis-Honeyweil Regulator Co., 1490-1491 Moeller Instrument Co., 1493 Powers Regulator Co., The, 1496 TRAPS, Bucket ___ V. D. Anderson Co., The, 1612-1613 Armstrong Machine Works, 1614-- 1498 1615 1615 Barnes <fc Jones, Inc., 1616 Crane Co., 1528-1529 C. A. Dunham Co., 1618-1621 Hoffman Speciality Mfg. Corp-. Illinois Engineering Co., 1626-1627 Jas. P- Marsh Corp., 1628-1629 Powers Regulator Co., The, 1496 1498 Sarco Co., Inc., 1634-1635 Sterling, Inc., 1502 ` Numerals following Manufacturers' Names refer to pages In the Catalog Data Section Index to Modem Equipment 1213 Strong, Carlisle & Hammond Co., TUBING, Steel Hoffman Specialty Mfg. Corp. 1622-- 1637 . Revere Copper and Brass Incorpo 1C25 ' Trane Co, The, 1298-1301 \ rated, 1313 Illinois Engineering Co., 1626-1627 Warren Webster & Co., 1638-1639 Wolverine Tube, 1314-1315 . Johnson Service Co., 1484-1485 Maid-O'-Mist Inc., 1630-1632 TRAPS, Thermostatic TUBING, Unicellular Rubber Sarco-Sarcotherm, 1633-1635 Barnes & Jones, Inc., 1616 - B. F.' Goodrich, Sponge Products H. A. Thrush 4 Co., 1600-1601 Crane Co., 1528-1529 Div., 1683 . C. A. Dunham Co., 1618-1621 Hoffman Speciality Mfg. Corp., TURBINES VALVES. Blowoff Fairbanks Co., The, 1641 1622-1625 Pyle-National Co., The, 1454-1455 Jenkins Bros, 1643 Illinois Engineering Co., 1626-1627 Jas. P. Marsh Corp., 1628-1629 PoweiB Regulator Co., The, 1496 1498 . Sarco Co., Inc., 1634-1635 . L. J. Wing Mfg. Co., 1302-1303 Worthington Corp., 1241 UNDERGROUND PIPE CON DUITS (See Conduits, Under VALVES. By-Pass Henry Valve Co., 1482 Jenkins Bros., 1643 Johnson Service Co., 1484-1485 Sterling, Inc., 1502 Trane Co., The, 1298-1301 ' Warren Webster 4 Co., 1638-1639 ground Pipe) UNIT HEATERS Unit) (See VALVES, Check Heaters, Fairbanks Co., The, 1641 , Hammond Brass mirks, 1642 Henry Valve Co., 1482 TRAPS, Vacuum .. V. D. Anderson Co., The, 1612-1613 Armstrong Machine Works, 1814-- UNIT STEAM GENERATORS (See Steam Generators, Unit) Hubbell Corp., The, 1483 Jenkins Bros., 1643 ' 1615 umit vcxmi .w.ADc> to v VALVES, Corrosion Resisting Barnes 4 Jones, Inc., 1616. . UNrr VENTILATORS (See Yen- Crane Co., 1628-1529 Hoffman Specialty Mfg. Corp., 1622 (.Wore, Unit) Jenkins Bros., 1643 1625 . . Illinois Engineering Co., 1626-1627 Jas. P. Marsh Corp., 1628-1629 UNITS, Air Conditioning (See Air Conditioning Units) Sarco Co., Inc., 1634-1635 --- Strong, Carlisle 4 Hammond Co., 'VACUUM HEATING SYSTEMS 1637 ' (See Heating Systems, Vacuum) VALVES. Diaphragm A. W. Cash Co., 1617 Crane Co., 1528-1529 General Controls, 1480-1481 Henry Valve Co.. 1482 Hubbell Corp., The 1483 TUBES, Boiler Babcock 4 Wilcox Tube Co., The, 1542 . . VALVES, Air V. D. Anderson Co., The, 1612-1613 Crane Co., 1528-1529 - Desomatic Products, Inc., 1228 Johnson Service Co., 1484-1485 Powers Regulator Co., The 1496 1498 Taylor Instrument Cos., 1503 TUBES and TUBING. Copper American Brass Co., The, 1310-1311 Revere Copper and Brass Incorpo rated. 1313 . Wolverine Tube, 131.4--1315 C. A. Dunham Co., 1618-1621 Fairbanks Co., The, 1641 Hammond Brass Works, 1642 Hoffman Specialty Mfg. Corp., 1622 1625 Jenkins Bros., 1643 Jas. P. Marsh Corp., 1628-1629 White-Rodgers Electric Co., 1504 VALVES, Expansion Alco Valve Co., 1472 . Crane Co., 1528-1529 . Henry Valve Co., 1482 . TUBES, Pitot (See Air Measuring VALVES. Float and Recording Instruments) VALVES, Angle, Globe and Cross Alco Valve Co., 1472 Crane Co., 1528-1529 Fulton Sylphon Div., The', Robert- TUBING, Aluminum Fairbanks Co., The, 1641 shaw-Fulton Controls Co., 1478 American Brass Co., The, 1310-1311 Frick Co., 1371 1479 Revere Copper and Brass, Incorpo Hammond Brass Works, 1642 Hubbell Corp., The, 1483 rated, 1313 - Heniy Valve Co., 1482 Illinois Engineering Co., 1626-1627 Wolverine Tube, 1314-1315 Jenkins Broe., 1643 Maid-O'-Mist, Inc., 1630-1632 McDonnell & Miller, Inc., 1570-1573 TUBING, Fabricated VALVES, Automatic Revere Copper and. Brass Incorpo rated. 1313 Wolverine Tube, 1314-1315 TUBING, Finned G 4 O Mfg. Co., The, 1362 General Automatic Products Corp., 1513 . Kritzer Radiant Coils, Inc., 1514 Rittling Corp., The, 1364 Rome-Turney Radiator Co., The, 1365 Wolverine Tube, 1314-1315 TUBING, Flexible Wiremold Co., The, 1469 Barber-Colman Co., 1437, 1473 A. W. Cash Co., 1617 Combustion Control Div., Elec tronics Corp. of America, 1475 Dole Valve Co., 1640 Fulton Sylphon Div., The, Roberta shaw-Fufton Controls Co., 1478 1479 Hubbell Corp., The, 1483 Johnson Service Co., 1484-1485 Leslie Co., 1487 Jas. P. Marsh Corp., 1628-1629 McDonnell & Miller, Inc., 1570-1673 Minneapolis-Honeyweil Regulator Co., 1490-1491 Penn Controls, Inc., 1494 Powers Regulator Co., The, 1496-- 1498 ' VALVES, Flow Control Bell <fc Gossett Co., 1598*1599 Crane Co., 1528-1529 Dole Valve Co., 1640 C. A. Dunham Co., 1618-1621 Fulton Sylphon Div., The, Robert- shaw-Fulton Controls Co., 1478 1479 General Controls, 1480-1481 Illinois Engineering Co., 1626-1627 Jas. P. Marsh Corp., 1628-1629 McDonnell & Miller, Inc., 1570 1573 Powers Regulator Co., The, 1496 1498 H. A. Thrush & Co., 1608-1601 Warren Webster & Co., 1638-1639 TUBING, Flexible. Metallic Aeroquip Corp., 1312 . American Brass Co., The, 1318-1311 r lexomcs Corp., 1507 TUBING, Insulation (See Insula- turn, Tubing) ' TUBING. RESTRICTOR Sarcothenn Controls, Inc., 1633 White-Rodgers Electrio Co., 1504 VALVES, Back Pressure Alco Valve Co., 1472 A. W. Cash Co., 1617 * Hubbell Corp., The, 1483 Illinois Engineering Cot, 1626-1627 VALVES, Gas Combustion Control Div., Elec tronics Corp. of America, 1475 Fairbanks Co., The, 1641 . Hammond Brass Works, 1642 JeDkins Bros., 1643 Penn Controls, Inc., 1494 White-Rodgers Electric Co., 1504 American Brass Co., The, 1316-1311 VALVES. Balancing Wolverine Tube, 1314-1315 Hammond Brass Works, 1642 VALVES, Gate Crane Co., 1528-1629 Please mention THE GUIDE 1956 when writing to Advertisers 1214 1956 Guide Fairbanks Co., The, 1641 ' . Crane Co., 1528-1529 VALVES. Safety _. Hammond Brass Works, 1642 ' - Dole Valve Co., The, 1640 Combustion Control Div., Elec Jenkins Bros:, 1643 C. A. Dunham Co., 1618-1621 tronics Corp. of America, 1475 Fairbanks Co., The, 1641 Frick Co., 1371 VALVES, Humidifier . Fulton Sylphon Div., The, Robert- General Controls, 1480-1481 M&id-O'-Mist, Inc., 1630-1632 Shaw-Fulton Controls Co., 1478 Henry Valve Co., 1482 McDonnell A Miller, Ino., 1570-1573 1479 Jas. P. Marsh Corp., 1628-1629 Hammond Brass Works, 1642 McDonnell A Miller, Inc., 1570-1573 VALVES. Hydraulic A. W. Cash Co., 1617 Jenkins Bros., 1643 Hoffman Specialty Mfg. Corp., 1622 1625 Illinois Engineering Co., 1626-1627 Jenkins Bros., 1643 VALVES. Solenoid Alco Valve Co., 1472 Combustion Control Div., . Elec Valves, Magnetic Alco Valve Co., 1472 General Controls, 1480-1481 Hubbell Corp.. The, 1483 McDonnell a Miller, Inc., 1570-1573 Milwaukee Gas-Specialty Co., 1492 Penn Controls, Inc., 1494 ' M&id-O'-Mist, Inc., 1630-1632 Jas. P. Marsh Corp., 1628-1629 Minneapolis-Honeywell Regulator Co., 1490-1491 Nation&l-U. S. Radiator Corp., 1530 1533 Powers Regulator Co., The, 1496 1498 tronics Corp. of America, 1475 General Controls, 1480-1481 Jas. P. Marsh Corp., 1628-1629 McDonnell A Miller, Inc., 1570-1573 Milwaukee Gas Specialty Co., 1492 Penn Controls, Inc., 1494 Spence Engineering Co., Inc., 1501 White-Rodgers Electric Co., 1504 Sarco Co., Inc., 1634-1635 VALVES, Mixing, Thermostatic Sterling, Inc.. 1502 VALVES, Stop and Check (See Dole Valve Go., 1640 TraneCo., The, 1298-1301 .. Valves, Non-Return) Fulton Sylphon Div., The, Robert- Warren Webster A Co., 1638-1639 ehaw-Fulton Controls Co., 1478-- VALVES, Tempering 1479 VALVES. Radiator, Convector Dole Valve Co., The, 1640 Powers Regulator Co., The, 1496 Powers Regulator Co., The, 1496 Fulton Sylphon Div., The, Robert- 1498 1498 shaw-Fulton Controls Co., 1478-- Sarco Co., Inc., 1634-1635 1479 . VALVES, Radiator, Humidifying General Fittings Co., 1596 VALVES, Motor Operated : Maid-O'-Mist, Inc., 1630-1632 Powers Regulator Co., The, 1496 fiarber-Colman Co., 1437,1473 1498 Bell A Gossett Co., 1598-1599 VALVES, Radiator Orifice Taco Heaters, Inc., 1602 Desomatic Products, Inc., 1228 Barnes A Jones, Inc., 1616 General Controls, 1480-1481 - C. A. Dunham Co., 1618-1621 VALVES, Thermostatic . Hoffman Specialty Mfg. Corp., 1622 Hammond Brass Works, 1642 Alco Valve Co., 1472 1625 Illinois Engineering Co., 1626-1627 Barber-Colman Co., 1437, 1473 Illinois Engineering Co., 1626-1627 Sarco Co., Inc., 1634-1635 Crane Co., 1528-1529 Jenkins Bros, 1643 Warren Webster A Co., 1638-1639 Fulton Sylphon Div., The, Robert- Johnson Service Co.. 1484-1485 shaw-Fulton Controls Co., 1478- Milwaukee Gas Specialty Co., 1492 VALVES, Radiator, Pneumatic 1479 Powers Regulator Co., The, 1496 Diaphragm General Controls, 1480-1481 1498 Johnson Service Co., 1484-1485 Hoffman Specialty Mfg. Corp., 1622 Sarco Co., Inc., 1634-1635 Minneapolis-Honeywell Regulator 1625 . Warren Webster A Co., 1638-1639 Co., 1490-1491 Illinois Engineering Co., 1626-1627 Powers Regulator Co., The, 1496 Jas. P. Marsh Corp., 1628-1629 VALVES, Non-Return 1498 Powers Regulator Co., The, 1496- Fairbanks Co., The, 1641 Hammond Brass Works, 1642 Illinois Engineering Co., 1626-1627 VALVES, Reducing Bell A Gossett Co., 1598-1599 1498 Spence Engineering Co., Inc., 1501 Sterling, Inc., 1502 . Jenkins Bros., 1643 A. W. Cash Co., 1617 Crane Co., 1528-1529 VALVES. Water Flow Regulat VALVES. Packless C. A. Dunham Co.. 1618-1619 Fulton Sylphon Div., The, Robert- ghaw-Fulton Controls Co., 1478 1479 . Henry Valve Co., 1482 Hoffman Specialty Mfg. Corp., 1622 1625 Illinois Engineering Co.* 1626-1627 Johnson Service Co., 1484-1485 Jas. P. Marsh Corp., 1628-1629 Minneapolis-Honeywell Regulator Co., 1490-1491 Penn Controls, Inc., 1494 Powers Regulator Co., The, 1496 1498 Sarco Co., Inc., 1634-1635 Sterling, Inc., 1502 C. A. Dunham Co., 1618-1621 Fulton Sylphon Div., The, Robert- shaw-Fulton Controls Co., 1478 1479 Hoffman Specialty Mfg. Corp., 1622 1625 Illinois Engineering Co., 162&-1627 Leslie Co., 1487 Strong, Carlisle A Hammond Co., 1637 H. A. Thrush A Co., 1600-1601 VALVES, Refrigerant Line Aeroquip Corp., 1312 Alco Valve Co., 1472 Hammond Brass Works, 1642 Henry Valve Co., 1482 Worthington Corp., 1241 York Corp., 1242 ing . Bell A Gossett Co., 1598-1599 Dole Valve Co., The, 1640 C. A. Dunham Co.. 1618-1621 Fulton Sylphon Div., The, Robert- shaw-Fulton Controls Co., 1478-- 1479 Hoffman Specialty Mfg. Corp., 1622 1625 Leslie Co., 1487 ,, McDonnell A Miller, Inc., 1570-1573 Powers Regulator Co., The, 1496 1498 ... Spence Engineering Co.,*1501 Taco Heaters, Inc., 1602 H. A. Thrush A Co., 1600-1601 VALVES. Water Level. Float Control VALVES, Pressure Reducing (See Regulators, Pressure) VALVES, Relief _ V. D. Anderson Co., The, 1612-1613 Fulton Sylphon Div., The, Robertsh&w-Fulton Controls Co., 1478-- VALVES.' Radiant Heating Hammond Brass Works, 1642 Bell A Gossett Co., 1598-1599 )A. r W. A rCansnhh*CTon.,f!1n6.1.71618--1621 Maid-O'-Mist, Inc., 1030-1632 McDonnell A Miller, Inc., 1570-1573 Sarcotherm Controls, Inc., 1633 H. A. Thrush A Co., 1600-1601 Henry Valve Co., 1482 Jas. P. Marsh Corp., 1628-1629 VALVES. Water Regulating McDonnell A Miller, Inc., 1570-1573 Alco Valve Co., 1472 VALVES, Radiator American Radiator A Standard Sanitary Corp. (Plumbing A Hating Div.), 1523-1525 Barnes A Jones, Inc., 1616 Monarch Mfg. Works, Inc., 1357 Taco Heaters, Inc., 1602 H. A. Thrush A Co., 1600-1601 Trane Co., The, 1298-1301 York Corp., 1242 Dole Valve Co., 1640 C. A. Dunham Co., 1618-1621 Fulton Sylphon Div., The, Robert- shaw-Fulton Controls Co., 1478 1479 Numerals following Manufacturers' Names refer to pages In the Catalog Data Section Index to Modern Equipment 1215 Hammond Brass Works, 1642 Jenkins Bros., 1643 Leslie Co., 1487 Jas. P. Marsh Corp., 1628-1629 McDonnell A Miller, Inc., 1570-1573 Packard Water Conditioner Div., Packard Mfg. Co., 1575 Penn Controls, Inc., 1494 Powers Regulator Co., The, 1496 1498 Spence Engineering Co., 1501 VANES, Air Turning Duro-Dyne Corp., 1466-1467 Eigen Mfg. Corp., 1468 Louvra Mfg. A Sales Co., 1452 . Miracle Adhesives Corp., 1654 VAPOR BARRIERS . Philip Carey Mfg. Co., 1656-1657 L -O F Glass Fibers Co., 1655 Infra Insulation, Inc., 1679 . Refiect&l Corp., 1682 Silvercote Products, Inc., 1680-1681 VAPOR HEATING SYSTEMS (See Heating Systems, Vapor) Ilg Electric Ventilating Co., 1287, 1393 , , Independent Register Co., The, 1448 Knowles Mushroom Ventilator Co., 1449 Lima Register Co., 1450-1451 Louvra Mfg. A Sales Co., 1452 . Penn Ventilator Co., 1422. . Propellair Div., Robbins A Myers, Inc., 1401 Reed Unit-Fans, Inc., 1402 Register A Grille Mfg. Co., Inc., 1453 Titus Mfg. Corp., 1458-1459 Trane Co., The, 1298-1301 United States Register Co., 1462-- 1463 Universal Diffuser Corp., 1464 Waterloo Register Co., Inc., 1465 VENTILATORS, Laboratory Gallaher Co., The, 1417 Kewaunee Mfg. Co., 1411 Muckle Mfg., Co., 1421 E. H. Sheldon Equipment Co., 1412 1413 VENTILATORS, Roof VENTILATORS. Unit Aerovent Fan Co., Inc., 1374 Air A Refrigeration Corp., 1219 Allen Cooler A Ventilator, Inc., 1414 American Blower Corp., 1220-1221 C. L. Ammerman Co., 1415 ' Brookside Products Co., Inc., 1379 DeBothezat Fans Div., American Machine A Metals, Inc., 1388-1389 General Blower Co., 1391 Genie Air, Inc., 1418-1419 Dg Electric Ventilating Co., 1287, 1393 Muckle Mfg. Co-i 1421 . Herman Nelson, American Air . Filter Co.. Inc., 1296-1297 . John J. Nesbitt, Inc., 1298-1295 Propellair Div., Robbins A Meyers, Inc., 1401 Rittling Corp., The, 1364 Swartwout Co., The, 1423 Trade-Wind Motorfans, Inc., 1405 Trane Co., The, 1298-1301 Westinghouse Electric Corp., Stur- tevant Div., 1410 L. J. Wing Mfg. Co., 1302-1303 VENT FLUE CAPS Vent Flue) (See Caps, Aerovent Fan Co., Inc., 1374 Air Control Products, Inc., 1428-1431 Air Devices, Inc., 1316, 1432 VENTILATORS. Wall Allen Cooler A Ventilator, Inc., 1414 VENT PIPE, Gas or Vents,"Gas (See Pipe, Gas Vent, Duets, Fume Disposal) Aladdin Heating Corp., 1375 Allen Cooler A Ventilator, Inc., 1414 American Blower Corp., 1220-1221 American Foundry A Furnace Co., VENTILATORS, Window Ilg Electric Ventilating Co., 1287 1393 VENTILATING DUCTS (See Ducts, Ventilating) VENTILATING SKYLIGHTS (See Skylights, Metal and VentHat ing) 1266-1267 American 3 Way-Luxfer Prism Co. 1600 C. L. Ammerman Co., 1415 Bishop A Babcock Mfg. Co., The, 1377 G. C. Breidert Co., 1416 . Lau Blower Co., The, 1396-1397 Muckle Mfg. Co., 1421 Reed Unit-Fans, Inc., 1402 L. J. Wing Mfg. Co., 1302-1303 VERMICULITE (See Insulation) VENTILATORS, Attic (See Fans, Electric, Propeller, Supply and Exhaust) Air Control Products, Inc., 1428-1431 Allen Coder A Ventilator, Inc., 1414 American Blower Corp., 1220-1221 G. C. Breidert Co., 1416 Bronson Fan Mfg. Corp., 1378 Brookside Products Co., Inc., 1379 Century Fan A Ventilator Co., 1384 Champion Blower A Forge Co., 1385 DcBothezat Fans Div., American Machine A Metals, Inc., 1388-1389 General Blower Co., 1391 Genie-Air, Inc., 1418-1419 Ilg Electric Ventilating Co., 1287, 1393 Lau Blower Co., The, 1396-1397 Reed Unit-Fans, Inc., 1402 Torrington Mfg. Co., The, 1406-1407 Trade-Wind Motorfans, Inc., 1405 Western Engrg. A Mfg. Co., 1424 L. J. Wing Mfg. Co., 1302-1303 VENTILATORS. Celling Genie-Air, Inc., 1418-1419 Brookside Products Co., Inc., 1379 Buffalo Forge Co., 1382 Century Fan A Ventilator Co., 1384 DeBothezat Fans Div., American Machine A Metals, Inc., 1388-1389 Gallaher Co., The, 1417 General Blower Co., 1391 Genie-Air, Inc.. 1419-1419 H&rtzell Propeller Fan Co., Div. of Castle Hills Corp., 1392 - Hirschman-Pohle Co., Inc., 1420 Ilg Electric Ventilating Co., 1287, 1393 Muckle Mfg. Co., 1421 New York Blower Co., 1399 Peerless Electric Co., The, 1400 Penn Ventilator Co., 1422 Propellair Div., Robbins A Myere, Inc., 1401 Sheldons Engineering Ltd., 1404 Swartwout Co., The, 1423 Trade-Wind Motorfans, Inc., 1405 Trane Co., The, 1298-1301 Western Engrg. A Mfg. Co., 1424 Westinghouse Electric Corp., Sturtevant Div., 1410 L. J. Wing Mfg. Co., 1302-1303 VIBRATION ABSORBERS (See Sound Deadening) American Brass Co., The, 1310-1311 Celotex Corp-, The, 1666 T. R. Finn A Co., Inc., 1686 Flexonics Corp., 1507 Korfund Co., Inc., The, 1687 Lockport Mills, Inc., 1674 Vibration Mountings, Inc., 1688 VIBRATION ISOLATORS Eigen Mfg. Corp., 1468 T. R. Finn A Co., 1686 Korfund Co., Inc., The, 1687 Vibration Mountings, Inc., 1688 VITRIFIED CLAY PIPE (See Pipe, Vitrified Clog, Heating Ducts) WALLBOARD ANCHORS AND ADHESIVES Devices, Inc., 1654 Miracle Adhesives Corp., 1654 Trade-Wind Motorfans, Inc., 1405 VENTILATORS. Floor and Wall A-J Mfg. Co., 1426-1427 Aerovent Fan Co., Inc., 1374 Air Control Products, Inc., 1428-1431 C. L. Ammerman Co., 1415 Auer Register Co., The, 1436 VENTILATORS, Ship Air Devices, Inc., 1316, 1432 C. L. Ammerman Co., 1415 G. C. Breidert Co., 1416 Gallaher Co., The, 1417 HartzeU Propeller Fan Co., Div. of Castle Hills Corp., 1392 WALLBOARD. Insulating Celotex Corp-, The, 1666 Insulite, 1668-1669 Johns-Manville, 1670-1671 Wood Conversion Co., 1677 Barber-Colman Co., 1437, 1473 DcBothezat Fans Div., American Machine A Metals, Inc., 1388-1389 Charles Demutb A Sons, Inc., 1439 General Blower Co., 1391 General Register Corp., 1442-1443 Penn Ventilator Cov 1422 Westinghouse Electric Corp., Sturte- vaat Div., 1410 L. J. Wing Mfg. Co., 1302-1303 VENTILATORS. Smoke WARM AIR FURNACES (See Furnaces, Warm Air) WARM AIR HEATING SYSTEM (See Heating Systems, Furnace) Hart A Cooley Mfg. Co., 1444-1445 American 3 Way-Luxfer Prism Co., Hendnck Mfg. Co.. 1446-1447 1660 WASHERS, Air (See Air Washers) Please mention THE GUIDE 1956 when writing to Advertisers 1216 1956 Guide WATER CONDITIONING EQUIPMENT Packard Water Conditioner Div., Packard Mfg. Co., 1575 WATER COOLING (See Cooling Equipment, Water, Cooling Tower*) Acme Industries* Inc., 1358 ' Aerofin Corp., 1359-1361 Airtemp Div., Chrysler Corp., 1248 1249 Baltimore Airooil Co., Ino., 1346 Binks Mfg. Co., 1344-1345 Brunner Mfg. Co., 1368 Carrier Corp., 1226-1227 Curtis Mfg. Co., Refrigeration Div., 1370 1 Fluor Corp., Ltd., The, 1347 E. D. Goodfellow, Ino., 1348 Governair Corp., 1232 ' Halstead & Mitchell, 1350-1351 Havens Structural Steel Co., 1349 Heller Laboratories, Inc.. 1352 Hydraline Products, Div. Borg- Warner Corp.,'1251 Kennard Corp., 1234 Liiie-Hoffman Cooling Towers, Inc., 1353 Marley Co., The, 1354 Mario Coil Co., 1355 McQuay, Inc., 1288-1289 Modine Mfg.. Co., 1290-1291 John J. Nesbitt, tnc., 1293-1295 ' Niagara Blower Co., 1235 . Packard Water Conditioner Div., Packard Mfg. Co., 1575 Patterson-Kelley Co., Inc., The, 1363 Phillips Cooling Tower Co., Inc., 1356 Servel, Inc., 1262-1263 Trane Co., The, 129^1301 . Westinghouse Electric Corp., Air Conditioning Div., 1240 Worthington Corp., 1241 York Corp., 1242 Young Radiator Co., 1304 WATER COOLING, Spray Sys tems - . Air & Refrigeration Corp., 1219 April Showers, Co., Inc., 1644 Binks Mfg. Cov 1344-1345 Copeland Refrigeration Corp.,-1369 Muellermist Irrigation'Co., 1645 -Niagara Blower Co., 1235 Pittsburgh Lectrodryer Corp.,1238 Refrigeration Engineering, Ino., 1373 Trane Co., The, 1298-1301 Westinghouse Electric Corp., Air Conditioning Div., 1240 York Corp., 1242 . WATER COOLING TOWERS (See Cooling Towers, Water) WATER FEEDERS (See Feeders, Boiler Water) , WATER HEATERS (See Heaters, Hot Water Service) WATER LEVEL CONTROLS (See Controls, Water Level) . WATER MIXERS. Thermostatic (See Valves, Tempering) ' Beil & Gossett Co., 1596-1599 Dole Valve Co., The, 1640 Fulton Sylphon Div., The, Robert- shaw-Fulton Controls Co., 1478-- 1479 Powers Regulator. Co., The, 1496 1498 - .. Taco Heaters, Inc., 1602 WATER TREATMENT Heller Laboratories, Inc., 1352 Packard Water Conditioner Div., Packard Mfg. Co., 1575 ' Worthington Corp., 1227 WELDERS. Spot Duro Dyne Corp., 1466-1467 WELDING FITTINGS (See Fit tings, Wdding) WELDING RINGS (See Rings, Wdding) WELDING ROD American Brass Co., The, 1310-1311 Revere Copper and Brass Incorpo rated, 1313 ' WHEELS, Blower ' Aerovent Fan Co., Inc., .1374 1 Airfan Engineering Co., 1343 Bishop & Babcock Mfg.* Co., The, (Massachusetts Blower Div.), 1377 Brookside Products Co.. Inc., 1379 Brundage Co., The/1380-1381 . Champion Blower & Forge Co., 1385 Clarage Fan Co., 1225, 1387 ' Garden City Fan Co., 1390 General Blower Co., 1391 Lau Blower Co., The, 1396-1397 Morrison Products, Inc., 1398 Peerless Electric Co., The, 1400 Revcor, 1403 Torrington Mfg. Co., The, 1406-1407 Viking Air Products, Div. Na tional-!!. S. Radiator Corp., 1408 WHEELS. Spray (See Spray Equip ment) WINDOWS, Fire Observation Detroit Stoker Co., 1568 . MANUFACTURERS' CATALOG DATA (PAGES 1219-1696) Numerals following Manufacturers* Names refer to pages In the Catalog Data Section / On pages 1219-1696 will be found the Catalog Data of 335 manu facturers whose products are described and illustrated. For the convenience of the user of THE GUIDE 1956 there are eleven main divisions: ,, Air Conditioning.............................................................................................................. 1219-1309 Air Conditioning and Heating Piping............................................... .1310-1315 Air System Equipment............................................................................................... 1316-1471 Controls and Instruments................................ ................................................. .. .1472-1504 ` Expansion Joints..............................................................................................................1505-1507 Fittings and Flanges.. ................................................................. 1508-1511. Floats................................................. ........................................................................................ 1512 Heating Systems....................................................................................'........................1513-1643 Insulation......................................................................................................................... ; 1644-1685 Vibration.................................................................................................................................. 1686-1688 Publications....................................................................................................... 1689-1695 On pages 1187-1216, under each of the index headings--Air Clean ing Equipment, Fans, Humidifiers, Ventilators, etc., will be found a list of manufacturers of any desired products, fully cross-indexed, and the page numbers in the Catalog Data Section where the prod ucts are described. By reference to these indices, the manufacturers' names and the page numbers, any item of equipment or materials, and the pro ducer's address, may be located quickly. Air Conditioning Central Systems Air & Refrigeration Corporation 439 Madison Avenue, New York 22, N. Y. 271 Milton Avenue, S. E., Atlanta, Ga. Representatives in all major cities Air Conditioning, Humidifying, Dehumidifying, Cooling, Scrubbing, Air Washing and Purification Apparatus Air & Refrigeration Corporation specializes in the design and manufacture of indus trial and comfort-conditioning apparatus where maintenance of suitable humidity and temperature within closely controllable limits is essential. This specialization is based on technical knowledge and ingenuity born of extensive experience in the solution of the more difficult problems of air conditioning. A complete line of air conditioning equipment is available to contractors and owners for all phases of humidifying, dehumidifying, cooling and washing. * Capillary Air Washers provide a superior type humidifying, dehumidifying, air washing, cleaning and cooling unit for central station apparatus. For most purposes the Capillary Washer requires the volume of water at the pressure used . by conventional spray equipment. They are available with factory insulated casings and tank for central station applica tions. For complete data, see Capillary Bulletin. Capillary Unit Conditioners are factory insulated and as sembled, ready for use. They include fan, motor, drive, heating coils, Capillary Cells with suitable sprays, spray pump and mixing dampers. Units are designed for floor mounting or for ceiling suspension, a.nd can be arranged for the reception of Factory insulated Class I cooling coils, if required. Complete description and engineering Capillary Air Watker data will be found in Capillary Unit Bulletin. Spray Type Air Washers for washing, humidifying and dehumidifying air are all basically the same. A & R Spray Washers include special features of design developed to insure more efficient and dependable operation, lower maintenance costs, and, in many cases, lower installation costs. Such features relate especially to eliminators, collecting tanks, flooded baffles, nozzle arrangement, etc. Spray Washers can be supplied with factory insulated casings and tank for central station applications. For details, see Air Washer Bulletin. Sprayed Coil Dehumldlfiers for year-round treatment of air are complete with cooling coils, sprays, circulating pump and glass mat eliminators. Sprayed coil de humidifiers are factory insulated ana complete, ready for assembly in the field. Special features in design insure continuous washing and cleaning of finned surfaces and easy accessibility to all parts. For engineering information and detailed descrip tion, see Sprayed Coil Bulletin. A & R Insulated Panels consist of insulation between metal sheet on one side and hard fiber board on the other, the three laminated and cemented together. This unique panel design includes the structural frame to form units which require only bolting together to make enclosures of any required shape for plenum chambers and many other purposes. Panels are available in widths from 3 in. to 48 in., and in lengths to 12 ft. Their use insures tremendous economies in field labor. For details, see Panel Bulletin. Write for catalog and engineering data. Registered Trade Mark Factory Insulated 1219 Factory Insulated Plenum Chamber Air Conditioning system American Blower Corporation Detroit 32, Michigan CANADIAN SIROCCO COMPANY, LTD. 310 Ellis Street, Windsor, Ontario Branch Offices in Principal Cities Division of PiMEsacAN - Standard AIR CONDITIONING -- HUMIDIFYING -- DEHUMIDIFYING -- COOLING -- VENTILATING -- HEATING -- VAPOR-ABSORPTION -- DRYING -- AIR WASHING AND PURIFICATION -- EXHAUSTING EQUIPMENT AND MECHANICAL DRAFT APPARATUS American Blower Corporation Air Conditioning s^tems TYPES OF AMERICAN BLOWER CORPORATION AIR HANDLING AND CONDITIONING EQUIPMENT All types of air handling and air conditioning equipment for industrial applica tions, process work, drying, cooling; also equipment for stores, offices, shops, public buildings, power plants, etc., and attic and kitchen ventilation for homes. Capillary Air Washers--above, for high efficiency in cleaning, humidification, cooling and dehumidification of air. Air is forced at low resistance through long, irregular passages of small size formed by a large amount of thoroughly wetted glass surface. Write for Bulletin IfiSS. "ABC" Utility Sets--complete packaged units, directly connected or V-belt short coupled drive for duct applications. Equipped with Aileron Control consist ing of scroll sheet adjusted by connecting rod. Fan outlet is modified to give effi cient operation over a wide range of air volumes and pressures. Sizes for a wide variety of ventilating problems. Quiet, compact. Complete technical informa tion in Bulletin 2814. Heating & Cooling Coils--above, Ameri can Blower heating and cooling coils offer a number of improvements in design and construction. Available in a complete range of sizes and types, including: Bulletin B-1218 Type S steam coils Type - D double tube, coils Type U return blend coils Type B booster coils Bulletin 1521 Type W water coils Type C cleanable water coils Type X direct expan sion coils Bulletin B-1318 Type H heavy duty coils Double Inlet "ABC" Multiblade Fan-- above, is a heavy duty ventilating fan. The wheel has narrow, forward pitched blades. Low tip speeds assure quiet op eration. Request Bulletin A-801. Bul letin A-80S describes backwardly in clined, nonoverloading HS Fan. 1220 Unit Heaters--for many general purpose heating jobs. Wall or ceiling mounted. Streamline construction, rugged heating elements. Steam or hot water. Re quest Bulletin 7517. Heating and Ventilating Units--with air filters and Aileron control. Ideal wher ever attractive, quiet and economical heating and ventilation units are re quired. Wall, floor or ceiling mounting. Offer great flexibility of design and arrangement to meet specific needs. Bulletin 7227. Gas Fired Unit Heater--self contained --for clean, automatic, instantaneous heating. Adjustable louvers assure effi cient heat distribution throughout the work area. A. G. A approved. Write for Bulletin 8517. Centrifugal Type Unit Heaters--for use with or without duct systems, for large hard to heat areas. Ideal for floor mount ing. Request Bulletin 7727. American Blower Air Conditioning Units. --Three basic types are available in twelve sizes, with capacities from 600 to 48,000 cfm. Type A (shown) is designed for all normal unitary-type commercial and industrial applications: Summer cooling and dehumidifying, using chilled water, direct-expanded refrigerant, or brines; winter heating, using steam or hot water. Type S is same basic unit as Type A, plus spray system, water recir culating pump and eliminators; com bines the washing, air cleaning, humidi fying, and evaporative cooling of an air washer with the cooling and heating of the basic unit conditioner. Type AB Multi-Zone Unit is furnished in a single arrangement for either horizontal or vertical air flow. Plenum and diffusion device between fans and coils provides even air distribution over coils. Request Bulletin 8427. 1221 . ,, . Centra! Systems Air Conditioning Humidification __________ and Cooling American Moistening Company Atlanta, Ga. Providence 1, R. I. Boston, Mass. Camden, N. J. Charlotte, N. C. Humidification Systems since 1888 AMCO MODEL 35 * HUMIDIFIER Ideally suited for areas of light heat concentration, especially where cost of other types of humidification might be prohibitive. Propeller-type fan draws room air into rear of unit and forces it forward around periphery of atomizer disc--thus carrying atomized water into room where it quickly evaporates into surrounding atmosphere. Housed in stainless steel. Requires only simple water and electrical connections. May be adjusted to evaporate from zero to 22 pounds of water per hour while cir culating 1200 cu ft of air per minute. Simple and reliable, it requires a mini mum of maintenance. . AMCO ATOMIZER NO. 6 > The automatically self-cleaning Amco No. 6 micro-spray atomizer delivers a smoke-like spray to a great distance for balanced distribution of humidity. Its fine performance and ease of main tenance make this atomizer popular for new installations and replacements. These units require compressed air for operation and obtain their water supply from a constant level, float controlled tank. AMCO CYCLESTAT HUMIDITY + CONTROL & 4E ft 45 JS Iff M ns 1 ,rk. f XI& `Ss* The Amco Cyclestat is easily adjusted and provides exceptionally fine control . of relative humidity within limits hereto fore believed impractical. This improve ment comes from a unique "change an ticipating mechanism" which employs jeweled bearings and a principle of operation that converts microscopic changes in its humidity sensing mem branes into instantaneous control sig nals. When properly adjusted and located all variations from the selected relative humidity are immediately coun teracted. ft i M f; Jv 1222 5>Sl Air Conditioning central sjstems THE 0H* COMPANY WINSTON-SALEM, N. C. Air Conditioning Humidification * Cleaning 1. AIR WASHER--Bahnson Type Y and Type DC Air Washers cleanse, cool, and provide humidity control. Available in standard sizes from 6,000 to 250,000 cfm, they can be provided with spray systems best suited for the specific application. Write for Catalog 1A 2. TYPE E HUMIDIFIER--A self-con tained unit with high evaporative ca pacity for installation in all types of industrial and commercial spaces requir ing automatically controlled humidifica tion. Evaporates up to S gallons per hour with 360 degree radial distribution of moisture. Requires only water supply and electrical connection. Write for Catalog 16A 3. CENTRIFUGAL HUMIDIFIER--A self-contained unit for industrial use. Evaporation up to 12 gph plus directional air flow with fractional horsepower motor. Installed singly or in groups with individual or group automatic control. Requires only water supply, drain, and electrical connection. Write for Cata log 2A 4. TYPE BA-2 HUMIDIFIER--A highcapacity unit for overhead suspension in commercial and industrial applications. Adjustable grilles give complete direc tional control of moist air delivered. Automatically regulated, the unit pro vides air flow, humidification and filter ing. Requires only water supply, drain, and electrical connection; capacity up to 18 gph. Write for Catalog 17A 5. TYPE ESC-2 ATOMIZER--A self cleaning pneumatic atomizer of superior design for direct humidification or sup plementary evaporation. Uses air and water under pressure to provide high evaporation and fine spray quality, with minimum air requirements. Modulating control regulates evaporation in direct proportion to the room requirements. Write for Catalog 8A Other equipment manufactured by Ajahnson includes: portable humidifiers, steam humidifiers, air washer suction strainers, spray nozzles, automatic con trols, grilles and complete industrial air conditioning systems. Write for descrip tive literature on your requirements. * 1223 Air Conditioning systems Richmond, Va. BUENSOD-STACEY ^ IWMeMTIO eo East 42 St. New York 17, N. Y. Charlotte, N. C. Air Conditioning, Humidifying, Cooling, Ventilation Systems DUAL DUCT AIR CONDITION ING SYSTEMS. In multi story build ings with many separated occupied spaces, Dual Duct air conditioning al lows' each occupant to select the tem perature at which he is most comfortable. For example, it allows one space to be cooled while an adjacent one is being heated. Air does all heating and cooling and insures proper ventilation. Buensod-Stacey has devoted many years in the development of design techniques and apparatus improvement. In this long study it became apparent that the basic requirement of such a system is constant air flow to all areas. To accomplish this, air mixing units, each with self-contained volume regula tors requiring no outside source of power, were developed for use in Dual Duct systems. Dual Duct Air Mixing and Distributing Units Under Windotce ' TYPE V3 DUAL DUCT AIR MIXING AND DISTRIBUTING UNITS are made in three parts for in stallation under windows or against walls. They supply air vertically through high velocity outlets. Mixing unit V3 contains pneumatically operated air mixing valve and self-contained volume controller. To this is attached a distributing header, VD, which can be varied in length to suit window width or building module. Part VFC provides a flush, finished front for the entire area under the distributing header and can also be varied in height and length to accomodate the space. Type VS Air Mixing Unit complete with Distributing Header and Front Caver TYPE H DUAL DUCT AIRMIX ING UNITS have a wider range of sizes than Type V3 and are designed for over head or under-floor installation. Each one includes an automatic, pneumati cally operated, air mixing valve, and selfcontained volume controller. The units are arranged to supply air to conditioned spaces through conventional grilles, registers, or diffusers. BUENSOD-STACEY HIGH PRESSURE DEHUMIDIFIERS for use in high pressure Dual Duct sys tems have been developed. A series of specially braced, factory insulated, sprayed coil dehumidifiers for use with pressure up to 10 in. wg are described in Bulletin DD-1. 1224 Type H Air Mixing Unit i, y .1 a Air Conditioning Central Systems Clarage CLARAGE FAN COMPANY Kalamazoo, Mich. Air Handling and Conditioning Equipment Application Engineering Offices in All Principal Cities For nearly a half century Clarage has been a leading manufacturer of equipment and units for ventilating, exhausting, cooling, air cleaning, humidifying and com plete conditioning. Clarage equipment is designed to meet all types of industrial, commercial and public building requirements. For other equipment in the complete Clarage line see "Air System Equipment--Fans and Blowers." Clarage Multitherms - cool and dehumidify in summer, heat and humidify in winter. For comfort applications and process conditioning. Vertical and hori zontal types, 10 sizes, capacities 600 to 20,500 efm. " Clarage Air Washers are built in both capillary and spray types. Sizes range from 2000 to 193,000 cfm. Used for air cleaning, humidifying and dehumidifying purposes. Special constructions can be furnished. Clarage Unlcoil Units are ideal as an integral part of a central station system for heating or cooling, or both; or for complete air conditioning in comfort applications. Wide size range. - We welcome your inquiry on any air handling or conditioning problem. Con tact our nearest branch office, or write us at Kalamazoo, Michigan. 1225 Air Conditioning Central Carrier Corporation Syracuse 1, N. Y. MARINE DIVISION: 385 Madison Ave. New York 17, N. Y. Carrier INTERNATIONAL DIVISION 385 Madison Are, New York 17, N. Y. Offices and Dealers in principal cities--refer to your telephone directory. 'Carrier) AIR CONDITIONING Weathermakers--completely self-con tained air conditioners for commercial and industrial applications. Six sizes from 2 to 15 hp cooling capacity. Year-Round Weathermakers--for heat ing and cooling in residential and com mercial applications. Compact, efficient gas heating combined with summer cool ing. Six combination sizes. Room Weathermakers--fan-coil units for use with remote sources of refriger ation and heat. Each unit operates inde pendently permitting individual room temperature control. Units are available in 3^, 1 and 1J^ ton capacities with or without cabinets. Zoning Weathermakers--blow-through fan-coil units for air conditioning sys tems using remote sources of heat and refrigeration. Six sizes for comfort and industrial applications, 6 to 80 tons. System Weathermakers--fan-coil uni tary air conditioners for applications to central cooling and heating systems for comfort and industrial use. Seven sizes r from 5 to 125 tops, 2,000 to 23,000 cfm. Central Station Air Conditioners--for application with fan and duct systems for large spaces such as stores, theatres, auditoriums and industrial plants. Weathermaster Systems--for air condi tioning of multi story, multi-room build ings such as hotels, hospitals, office and apartment buildings. System consists of room units with individual tempera ture control, and central station air conditioning. Conditioned air distrib uted by high velocity conduits to indi vidual Weathermaster units shown. Blast Freezers and Cold Diffusers--for food freezing and storage, meat packing operations, and other industries requir ing low temperatures. Units available in suspension or floor models, for use within space to be refrigerated or remQtely located and connected by ducts. . Write for descriptive literature. 1226 Carrier Corporation Air Conditioning Central Systems Centrifugal Refrigerating Machines--for large comfort and industrial air condi tioning applications and for process cool ing. High efficiency at peak or partial loads. Operate with any standard motor or turbine drive. Available in capacities from 100 to 4000 tons in a single unit. Absorption Refrigerating Machines--for producing chilled water at 40 F or higher in fully automatic operation from 0 to 100 per cent capacity. Uses low pressure steam for operation. Available in eleven sizes with capacities from 100 to 700 tons. Water Cooling Machines--Compact, packaged water cooling systems for air conditioning and for industrial process cooling. Direct or belt drive, capacities range from 5 to 200 hp. Commercial Refrigerating Machines-- for storage refrigerators, display cases, walk-in coolers and similar duty. Com plete with compressor, drive, air or water cooled condenser and controls. All sizes. Reciprocating Compressors--for refrig eration needs of air conditioning and process cooling. Adaptable to all drives and available for "Freon" and ammonia refrigerants. Sizes from 3 to 200 hp. Evaporative Condensers--for use with refrigerating compressors in place of water cooled condensers. Simplify water supply and disposal problems. For in door or outdoor use. Capacities 10 to 110 tons, for "Freon" or ammonia. REFRIGERATION Carriep INDUSTRIAL HEATING trial space heating using steam or ho water. Complete range of sizes in thre types: 46U Horizontal Discharge (13,40 to 200,000 Btu per hr), 46S Four-wa; Directed-flo (55,000 to 600,000 Btu pe hr) and 46AE Cabinet Heaters (26,20 to 115,000 Btu per hr). Gas-Fired Unit Heaters--for clean, eco nomical heat in offices, .stores, factorie and similar spaces where gas is available A.G.A. approved for manufactured mixed, natural, LP and LP-air gases Capacities: 50,000 to 230,000 Btu pe hour. Heat Diffusers--for ventilating as wel as heating large commercial and indus trial spaces. Floor, wall or ceiling mounted with coils for steam or hot wa ter. Capacities 47,000 to 2,990,000 Btu per hour at 2 lb steam. 1227 Air Conditioning "umidmcato units Desomatic Products, Inc. 1109 West Broad Street Falls Church, Virginia DEHUNHDIF1ERS Designers Engineers Manufacturers U. S.Representatives in Principal' Cities and Canada DESOMATIC MODEL 350. This Deso matic unit protects materials in storage from corrosion, mold and mildew, danger by maintaining low relative humidities in the space, over a temperature range from 0 F to 120 F. DESOMATIC De humidifiers use a solid sorbent, silica gel, and no replacement of adsorbent is necessary. Customer may specify other, desiccants. Desomatic equipment for dehumidifica tion of air is your answer to efficient moisture control in storage areas, homes, industries and laboratories. Five standard models to meet your needs. Also'custom designed equipment and machines for Class 1, Group D, hazardous locations. All standard models may be modified to meet Military # Specifications. Standard Desomatic Industrial Dehumidifiers Air Flow cfm External Pressure Voltage Load Kw. Capacity 70-35% lb/hr Weight, Lbs. Length, Inches Width, Inches Height, Inches SOR-8 DOR-38 DOR-100 DOR-350 DOR-800 25 100 175 500 %' W.G. 110 V, 1 W W.G. 110 V, 1 W.G. 220 V, 3 1" W.G. 440 V, 3 Ph. Ph. Ph. Ph. 1500 2" W.G. 220 V, 3 Ph. 1 1.4 3 9 25 Yi 1 48 - 375 2.5 425 7.5 1150 22 4000 15 54 54 70 108 13 20 20 25 61.5 18 42.5 42.5 60 92.5 Write for full details on Desomatic Dehumidifiers, for low as well as high pressure applications. Pressure Blowers, 4-Port Mr Valves, Air Flow Indicators and Humid ity Controllers. 1228 Air Conditioning Central and Unit Systems draper hanson SINCE 1910 (Division of National-U. S. Radiator Corporation) Factory and General Sales Office 3301 Medford St. Los Angeles 63, California Representatives in Principal Cities Manufacturers of Air Conditioning and Refrigeration Equipment REFRIGERATION AND AIR CONDITIONING LEFT COLUMN READING DOWN: Multizone-type FZ--Air conditioners, blow-through type, supply many zones individually by damper control. Hori zontal, vertical types. Perma-Fan Series PF--Complete line of blow-through type evaporative con densers, on principle developed by D-H in 1937. 5 to 110-ton capacities. HH and HHV types--for horizontal or vertical air conditioning; central-type systems. Water Chiller--Space-saving, self-con tained water cooled or air-cooled units. Spotaire Series LRC---Compact basic or cabinet types for air conditioning in dividual rooms of multi-room buildings. Overhead installation; takes little head room. RIGHT COLUMN READING DOWN: Spotaire Series HRC--Room unit air conditioning equipment for chilled wa ter, hot water or DX. Concealed basic unit or cabinet models. Spotaire Series VRC--Handsome, floormounted models for chilled or hot water, or "Freon." d-h Hot Shot Electric Defrost--ceilingtype units using D-H's electric auto matic defrost patents. d-h Spasaver-Product cooling applica tion for over 34F temperatures. Many sizes. d-h Flocold--Product or produce coolers for under or over 34F; water or ammonia defrost. Extended Surface Coils--Staggered tubes for steam, water, DX, "Freon" or ammonia; removable header or plug-type coils. 1229 Air Conditioning Systems GENERAL ELECTRIC HOME HEATING AND POOLING DEPARTMENT 5 Lawrence St., Bloomfield, New Jersey REGIONAL SALES OFFICE: New York 22, N. Y.--570 Lexington Ave. Cleveland 15, O.--1010 Euclid Bldg., Room 1101 Chicago 54, III.--Merchandise Mart, Room 1144 Atlanta 3, Ga.--410 Redkock Bldg., Room 400 New Orleanb 12^ La.--511 International Trade Mart Los Angeles 17, Calie.--1052 West 6 Street, Room 614 See your classified telephone directory for localgsourcesunder: G-E Furnaces G-E Air Conditioning Equipment & Supplies 1. G-E OIL-FIRED BOILER . Compact, integrated steel boiler units designed exclusively for low-pressure oil burning. Ideal in multiple installation for both central heating and zone heating. High heat transfer' rate with low water content and low metal mass. Exclusive G-E features give fuel savings up to 50 per cent: "Turnback Flame"; oil atomization for complete combustion; famous G-E "heat-trap" design. Built-in tank or tankless-type hot water coil. Five models: 100, 140, 200, 300 and 450,000 Btuh output. Listed by Underwriters' Laboratories, Inc. Constructed in accordance with ASME Code. Also GAS-FIRED BOILERS --06,144, 192, 240, 288,336, and 432,000 Btuh input--Cast Iron Heat Exchanger. For natural, manufactured or mixed gas. 2. G-E OIL AND GAS-FIRED WARM AIR FURNACES Oil-Fired. Fuel savings up to 50 per cent reported by users. Features: G-E Atomized Oil burning, "Turnback Flame," "Spira-Flow" heat transfer surface. 60 to 155,000 Btuh bonnet output. Listed by Underwriters' Laboratories. Gas-Fired. G-E's long-life, cast-iron "Pinpoint" heat transfer sections give superior heating action. Compact,- quiet. Listed by Underwriters' Laboratories, approved by A.G.A. Bum manu factured, mixed, natural, natural-SUR or LP gases. 60 to 210,000 Btuh input. Models. G-E Oil and Gas-Fired Furnaces are' available in Upflow, Downflow and Horizontal models. Each is "Pre-Paired" to permit addition of G-E Home Cooling at any time. " 3 G-E'S COOLING UNITS AND YEAR-ROUND AIR CONDITIONERS ,' Self-contained central system heats, cools, filters, dehumidi- fies, ventilates and circulates conditioned dir. Cooling capac ity: 2 to 5 tons. Heating capacity: with gas firing, 60 to 210,000 Btuh input; with oil firing, 60 to 155,000 Btuh, bonnet output. Over 4,784 heating-cooling combinations--permitting accurate sizing of units to fit any home size and design--all climatic conditions. Upflow, Downflow, Horizontal models. Cooling with water-cooled or air-cooled condensers. 4 G-E AIR-WALL* SYSTEM FOR HEATING AND COOLING ,,, ,.x. , Air-Wall--The Air-Wall register spreads a wall of conditioned air over insides of windows and outer walls, protectingagainst extremes of winter and summer weather. With G-E Year- Round Air Conditioning, or G-E Furnaces or G-E Home Cool ing, same registers deliver both heat and cooling. Engineers and architects especially acclaim the coordinated design of the Air-Wall SYSTEM--heating and cooling units, ducts and registers designed to function as a single unit. Reg. Trademark of General Electric Company. ' 1230 fr *'te $ s ijV n 'la M f:' ,fy Air Conditioning Central Systems GENERAL ELECTRIC PACKAGED Am CONDITIONING Commercial and Industrial Air Conditioning Department 5 Lawrence St., Bloomfield, N. J. REGIONAL SALES OFFICES New York 22, N. Y.--570 Lexington Ave. Cleveland 15, Ohio--1010 Euclid Building, Rm. 1101 Chicago 54, III.--Merchandise Mart, Rm. 1144 Atlanta 3, Ga.--410 Red Rock Building New Orleans 12, La.--511 International Trade Mart Los Angeles 17, Calif.--1052 W. 6th St. See your Classified Telephone Directory for local sources under: GENERAL ELECTRIC AIR CONDITIONING CEILING-MOUNTED UNITS The latest additions to the complete G-E Line of Packaged Air Conditioners require no floor space. Instead, these compact, self-contained units are fas tened to the ceiling or mounted on shelves. And there are no remote parts to complicate operation or increase danger of refrigerant leakage. Available in water-cooled and air-cooled models-- latter designed to eliminate problem of water restriction. For offices, factories, shops, supermarkets, etc. Water-cooled model in 3, 5, and 71^ ton capacities; Air-cooled model in 3 and 5 ton capaci ties. FLOOR-MOUNTED UNITS These popular G-E Packaged Air-Conditioners are famous for quiet, reliable performance--as they filter, cool, dehumidify and circulate air. They can be installed step-by-step to fit limited budgets--without extensive alterations. Modern, func tional styling blends in with any decor. Units can be located in-space or out-of-space. For stores, offices, hotels, restaurants, Plants, etc. Capacities: 3, 5, 7'A, 10 and 15 tons. TH ceiling-mounted and floor-mounted units have entire cooling system--motor, compressor, condenser--sealed-by-flame to keep dirt and moisture out, vital refrig erant m. Both have completely adjustable air distribution. Both can be supplied with Oils for winter heating. And both carry G-E's 5-year warranty covering entire refrigeration system. . 1231 Central and Self Contained Air . Air Conditioning Conditioners, Blower Units, Coils, Evaporative Condensers Governair Corporation 513 North Blackwclder, Oklahoma City 4, Oklahoma GOVERNAIR Self-Contained Air Conditioners SELF - CONTAINED AIR CONDI TIONERS--completely packaged air conditioners with evaporative con denser. Ready for connection to duct system--3 to 60 ton--single or two sepa rate refrigeration systems--non ferrous condenser available. TYPE SC CONDITIONERS--for stores, offices, hospitals, homes--3, 5, 7^J, 10, 15 ton sizes--heating optional--plenum or duct air distribution for city water or cooling tower use-- with quiet hermetic compressor. FAN AND COIL CABINETS--cooling, heating, humidifying, dehumidifying, ventilating, 1 to 100 ton, 500 to 30,000 cfm, vertical or horizontal types. Gover-. nair multi-zone fan and coil units are available in sizes ranging from 5 to 60 ton capacities, suitable for individual zoning. EVAPORATIVE CONDENSERS--3 to 100 ton--all prime or fin surface--corro sion resistant steel or non-ferrous con struction--internal jacket liner. BLAST COILS--direct expansion, water steam--hydraulically expanded tubes for close fin spacing--mechanically ex panded tubes for wide fin spacing--. copper or aluminum fins--complete . range of sizes. Also: Multi-Zone Fan and Coil Units, Cooling Towers, Packaged Water Chillers and Low Temperature Coolers. 1232 Air Conditioning SXHeft^'Sd cooler. Hastings Air Conditioning Co., Inc. Hastings, Nebr. Manufacturers ot - Cooling, Heating and Ventilating Equipment. Water, DX and Steam Coils. Gas and Steam Unit Heatezs. Gas Power Conversion Burners. A complete line of air conditioners for chilled or well water, cold city water, and direct expansion. Full range of sizes, 1 to 40 tons. All coils are constructed entirely of copper. Fins are both solder-bonded and mechanically-bonded to the tubes for permanent high efficiency. Flowmeters (to visually indicate water flow) are standard on all water units. DOUBLE-KOOL "2-stage" COOLING UNITS--3 to 56 tons. 2 Tons cooling per compressor hp. Air is first pre-cooled using water up to 70 F, then further cooled and de-humidified by Freon coil. Packaged and remote models. Up to 100 per cent FRESH AIR may be used for cooling, re gardless of outside conditions. Saves approximately 50 per cent of water and power cost. HOME AIR CONDITIONERS--2 to 5 tons Easily attached to any furnace. Water Coil Models--for water up to 60 F. Dovble-Kool Models (Combination Water-DX)--for water up to 70 F. GAS UNIT HEATERS--50,000 to 220,000 Btu capacity Equipped with CENTRIFUGAL or PROPELLER type fans. DUCT HEATERS available for use with remote blowers. A G-A- approved for all gases. Aluminized steel heat exchangers for fast heat transfer and extra long life. Stainless steel ribbon burners for quiet, efficient combustion. Dual directional, adjustable louvers permit complete control of air delivery. HEATWELL POWER GAS CONVERSION BURNERS-- Inshol--To replace oil burners. Up to 370,000 Btu. Roundhead--For any round furnace or boiler. Up to 250,000 Btu. Adjusto "V"--Commercial, Multiple-dwelling, and Industrial. Up to 4,000,000 Btu. No combustion chamber required. Adjustable flame placement. Write for Catalogs, Literature, or Information ` .1233 Air Cnn/iifinrtinn Central Systems. Blower Units. Coils, JilT VsOTlUlllUTuTig Evaporative Condensers, Cooling Towers 1819 So. Hanley Rd., St. Louis 17, Mo. Manufacturers of AIR CONDITIONING EQUIPMENT Finned Coils (Heating & Cooling)--Air Conditioning Blower Units--Multi-Zone Units--Heating and Ventilating Units--Sprayed Coil Dehumidifiers--Cooling Towers--Evaporative Condensers--Liquid Chillers AIR CONDITIONING BLOWER UNITS MULTI-ZONE UNITS 13 Sizes. 300 to 21,600 cfm. Horizontal or Sizes up to 36 sq ft. Cooling Coil Face Vertical. Catalog No. AC. Area. Catalog No. MZ. HEATING AND VENTILATING UNITS Air Volumes 300 to 28,800 cfm, and up to 36 sq ft Coil Face Area. Catalog No. HV. SPRAYED COIL DEHUMIDIFIERS 56 Sizes. Coil Face Areas up to 81 sq ft. Catalog No. SC. COOLING TOWERS AND EVAPORA TIVE CONDENSERS Sizes from 3 to 15 tons. Centrifugal type fan for quiet Indoor operation-propeller fan water turbine driven for Outdoor operation. EC and CT models for 15 to 75 tons (not shown). Catalogs No. KT andQT. FINNED COILS Direct Expansion, Water, Steam Dis tributing Tube, Standard Steam Coils. Sizes up to 48 in. wide x 132 in. long. Catalogs No. CC and HC. LIQUID CHILLERS Direct Expansion, Freon Shell and Tube Liquid Chillers. Internally finned tubing (Pat. Applied For), brass baffles, positive oil return, closed refrigerant circuits without freon gaskets. Catalog No. LC. 1234 P 4 A'-f Air Conditioning sy"?ms Niagara Blower Company Executive Offices: 405 Lexington Ave. New York 17, N.Y. - Sales representatives in Principal Cities oi U. S. and Canada Over 85 Years' Experience in Industrial Air Conditioning NIAGARA AIR CONDITIONING SYSTEMS For human comfort and for all industrial applications requiring controlled conditions of temperature, relative humidity, air purity and air movement. NIAGARA AIR CONDITIONER, TYPE A, AND CONTROLLED HUMIDITY METHOD USING HYGROL LIQUID ABSORBENT High precision apparatus using saturation to obtain control of R. H. to 1 per cent for laboratory work and control of hygroscopic materials. Ask for Bulletins ligand IBB NIAGARA AIRiCONDITIONER, TYPE C A year around air conditioning unit providing heating and humidifying or dehumidifying. Ask for Bulletin 80. NIAGARA^FAN COOLER AND DISK FAN COOLER For comfort cooling,.process cooling, low temperature storage for dairies, fruits, meats, food products, fur storage vaults, etc. Bulletin TB. / NIAGARA SPRAY COOLER For all cooling applications requiring high humidity or high capacity in small space. Ask for Bulletin 110. NIAGARA "NO FROST" SYSTEM Using Niagara "No Frost" Liquid in spray coolers prevents frosting of cooling coils, automatically keeps spray solution at proper concentration, gives freedom from brine troubles, corrosion. Constant, efficient operation. Temperature to -- 100F. Ask for Bulletin 105 (Food) or Bulletin 95 (Industrial). NIAGARA AEROPASS CONDENSER Saves power and water cost utilizing atmospheric air to remove heat of condensation. Patented Duo-Pass prevents scaling, saves power. "OILOUT" positively removes oil and dirt from refrigerant lines, assuring always full capacity. Balanced Wet Bulb Control assures operation of refrigeration plant at minimum head pressure regardless of weather or load conditions. Capacities up to 400 tons refrigeration. Ask for Bulletins 108, 111 and IBS. NIAGARA "DUAL" COOLERS Simultaneously cools a room and furnishes chilled water as a refrigerant. Saves equipment cost, operating expense. Patented. Ask for Bulletin 70. NIAGARA AERO HEAT EXCHANGER For cooling industrial liquids, water, oils, solutions, chemicals, compressed air and gases, with Niagara "Balanced Wet-Bulb" temperature control to improve efficiency and obtain precise results. Capacities up to 30,000,000 Btu. Patented (U. S. Nos. 2,296, 946 and R. I. 22,553). Ask for Bulletins 1B0 and 1B4. NIAGARA INDUSTRIAL LIQUID COOLER Furnishes refrigerated water or aqueous solution in any quantity up to 220 gpm. Positive control of temperature regardless of load variation. Delivers "sweet" water at 33F without danger of freezing damage. Ask for Bulletin 104. NIAGARA FAN HEATERS AND HIGH PRESSURE STEAM FAN HEATERS For heating and ventilating large areas. Units of the highest quality in engineering, material and workmanship. Ask for Bulletins 78 and 109. . NIAGARA MOTOR BLOWERS One, two and three-fan units. High and low static pressure models. Ask for^Bulletin 1235 Air Conditioning Central Systems Parks - Cramer Company Fitchburg, Mass. Charlotte, N. C. Atlanta, Ga. CERTIFIED CLIMATE Industrial air conditioning systems, including humidifying or dehumidifying, cooling by evaporation or refrigeration, ven tilating,Altering, air washing; with automatic control of hu midity, temperature and air change. Engineered, manufac tured, installed and serviced by Parks-Cramer. Air Conditioning , Parks - Cramer Company Fitchburg, Mass. Charlotte, N. C. Atlanta, Ga. Industrial Humidifying and Air Conditioning Since 1904 AUTOMATIC AIRCHANGER ' An improved system of forced air change and distribution used with direct humidi fication. Insures fixed uniform humidity and maximum evaporative cooling. Amount of air change and operation of humidifiers controlled by humidity and temperature Psychrostat. Designed for either complete new installations or for supplementing existing direct humidify ing equipment, especially Gradumatics. Includes heating, refrigeration, filtering, where needed. GRADUMATIC HUMIDIFYING SYSTEM ' Vastly improved direct humidifying system for use alone, with Airchangefs, or as booster for Central Station system. Air and water under pressure, water pressure always less than air. Safe. Economical. Humidifier is self-cleaning. CENTRAL STATION AIR CONDITIONING A complete system for conditioning the factory atmosphere, with positive circulation and controlled ventilation. One or more air washer units. High humidifying and evaporative cool ing capacity. Heating, filtering, and refrigerated cooling where needed. Ducts with adjustable outlets distribute conditioned air uniformly. Slight air pressure also improves uniformity. Centralized maintenance. Used with or without booster hu midification. Under gradual acting automatic control. Exclu sive multi-speed control of fan improves economy. Central Station Air Washer Units. Nozzles and Self-Cleaning Tank Screens for Central Station Air Washers. LABORATORY AIR CONDITIONING An essential of a good testing laboratory is adequate and'de- pendable air conditioning. Accuracy in testing is maintained only when samples and testing equipment are free from fluctu ations in both temperature and humidity. A vertical or hori zontal unit is located within or adjacent to the laboratory. Includes equipment for heating, humidifying,'dehumidifying, refrigeration, circulation, and adjustable recorder-controller. Heat by steam or electricity. * 1236 Has few component parts, easy to take apart and reassemble. Proper operation as sured without testing. No adjustment required. When humidification is needed, heads operate continuously, evaporative output being varied gradually and auto matically by Certified Climate Psychrostat to suit requirements for constant humid ity at all times. CERTIFIED CLIMATE PSYCHROSTAT For gradual control of humidity and temperature. Improved model more sensitive than ever before. Rugged and reliable. Use of the wet and dry bulb principle permits Psychrostat to perform the many and varied tasks in the field of humidity and temperature control which contribute to the success of Certi fied Climate systems. THE PETTIFOGGER (not illustrated) A compact centrifugal humidifier, with fan, for offices, storerooms, experimental rooms, hospitals, or other isolated departments. Self-contained in lacquered copper casing. Easily connected to water and electrical supplies. Automat ic control. Adjust able capacity. ' 1237 .. .. Central Systems Air Conditioning Dehumidification Units Pittsburgh Lectrodryer Corporation Foot of 32nd Street Pittsburgh, 30, Pa. This machine -protects equipment in storage by maintaining a relative humidity of 85 per cent , or lower. Small automatic air conditioning type LEC TRODRYER used for providing lowered rel ative humidities. FOR INDEPENDENT CONTROL OF DEHUMIDIFICATION IN COM FORT AND INDUSTRIAL AIR CONDITIONING The results of years of experience in the independent control of industrial dehumidification are now available for comfort air conditioning in the form of sturdy, dependable, thoroughly tested machines for controlled adsorption de humidification. LECTRODRYER equipment using Ac tivated Alumina, a solid adsorbent, is widely used in maintaining lower than normal relative humidities in the chem ical, pharmaceutical and other indus tries. In comfort air conditioning these ma chines handle the latent heat load with only the sensible heat load left for refrig eration or water cooling. With this type system, only the air needed for the sensi ble heat load is cooled and no reheat is required. Machines are available for steam, gas or electric operation, whichever the pur chaser specifies. Standard machines are available in several sizes ranging from 350 cfm upward. LECTRODRYERS are shipped com plete as self-contained automatic units in that they require no regular manual attention except for starting. They are built for continuous operation with reac tivation being carried on simultaneously with the drying operation. Write for full details. 1238 Air Conditioning g Walton Laboratories, Inc. Irvington 11, New Jersey MANUFACTURERS OF HUMIDIFIERS and AQUA-SORBER DEHUMIDIFIERS WALTON PATENTED CENTRIFUGAL ATOMIZER principle has been embodied in all of the Walton humidifiers for over 25 years. Positive humidification is available continuously without the need for pressure devices, nozzles and other auxiliary equipment. PORTABLE ROOM HUMIDIFIERS are available in table and automatically controlled console models, attractive design; uses no heating coils, nozzles or filters. - INDUSTRIAL HUMIDIFIERS self con tained, easy to install. Water and electrical connections are the only re quirements. No costly ducts, com pressors or drain piping are used. Sizes and types to accommodate small, and large installations requiring humidifica tion up to 100 per cent. DUCT OR WARM AIR SYSTEMS can utilize Walton Model WF which can supply positive humidification without plates, drip pans, or jets, unaffected by mineral content in water. Available to engineers, architects, and industrial designers is the complete new Walton Catalog file including-- "Industrial Humidification" "Humidification for Textiles" "Humidification for Knitting" "Humidification for Graphic Arts" "Humidification for Hospitals" "Humidification for Home and Office" "HumidificationforWarm AirSystems" "Dehumidification for all Applica tions" - 1239 Air Conditioning ggfJgT*- Westinghouse Electric Corporation Air Conditioning Division Staunton Self-contained Air Conditioners--2 to 25 tons; Heat Pumps; Field-assembled Air Conditioning Equipment Offices in all principal cities AIR CONDITIONING UNITS Type HP Heat Pumps are Sameless, water-less, all-electric units which will heat the home in the winter and cool it in the summer, automatically. Recom mended for areas where extremes of tem perature are not of long duration. Avail able in nominal 3 and 5 hp ratings. Type RG/RO Year-Round Air. Condi tioners heat in summer and cool in winter. Features ingenuous slip-in cool ing package, economical gas or oil burner operation, year-round thermostat con trol. (A.G.A. approved.) Available in 2 or 3-ton cooling capacities. Type RU Unitaire Conditioners for resi dential and commercial cooling requiring duct work. Installed with new or existing forced-air heating system, or independ ently with own duct work. Features compact design, sturdy welded-frame construction. In 3 and 5-ton capacities. Type ACU Air-Cooled Condensing Units for residential cooling applications with new or existing forced air furnaces. May be installed indoor or outdoor with cool ing coil in furnace discharge duct or plenum. Full nominal capacity at high ambient. Features durable bonderized cabinet, waterproof electrical panel, versatile vertical discharge arrangement. In 2, 3 and 5-ton capacities. Type SU and MU Unitaire Conditioners are designed for commercial and indus trial use. They cool, dehumidify, filter and circulate air. Accessory heating coil available. Dual refrigeration cycles on MU Unitaire provide 50 and 100 per cent capacity operation. Available in 3, 5, 710 and 15-ton capacities. Type LU Central Plant Unitaire Condi tioners for installation with supply and return air ducts. In capacities of 20 to 28 ton. REFRIGERATION COMPRESSORS 1 Type CLS Refrigeration Compressors are hermetically sealed, direct connected units with refrigerant cooled motors made in 12 sizes from 2 to 125 ton. WATER COOLED CONDENSERS They are constructed with integrally finned copper tubing, steel. sheets and silver soldered tube sheets. Manufac tured in accordance with the recom mendations of the ASME Boiler Con struction Code, Section VIII. Available in 16 sizes within 2 to 125 ton range. Central Plant Unitaire pc ACU Air-Cooled, Condensing Unit. Virginia SU Unitaire Units 1240 Air Conditioning Central Systems Worthington Corporation Air Conditioning and Refrigeration Division Albany Atlanta Baltimobe Birmingham Boston Buffalo Chablotpe Chicago Cincinnati Cleveland Dallas Denveb Detboit El Paso General Offices: HARRISON, NEW JERSEY Fobt Wobth Galveston Gbeenville, S. C. Houston Kansas Citt Knoxville Los Angeles Louisville Milwaukee New Haven New Oblbans New Yobk Omaha Philadelphia Phoenix Pittsbubgh Pobtland, Obe. Pbovidencb St. Louis St. Paul Salt Lake City San Fhancisco Seattle Spbingfield, Mass. Stbacuse Tulsa Washington, D. C. Wilmington, Del. Representatives in all Principal Cities A.0-25 Packaged Air Conditioners Centrifugal Refrigeration Water Cooling Systems Provide cooling (and heating, if desired), dehumidification, ventilation, and air cleaning for commercial and industrial applications. 3, 5, 7)4, 10, 15, 20, and 25 ton capacities. 150 to 1,200 tons, 56 unit sizes. Freon centrifugal compressor, water cooler and water-cooled condenser in compact unit assembly. Electric motor or steam turbine drive. Reciprocating Compressors Freon Packaged Liquid Chillers V and W type, to 150 tons with Freon-12 and to 170 tons with Freon-22. Full force feed lubrication above 10 hp. Ca- acity reduction and unloaded starting y gas unloaders. Mounted on steel base, with water cooled condenser or for use with separate evaporative condenser. Evaporative Condensers Series LCP Freon-22 Packaged Liquid Chillers for process cooling, refrigera tion, or air conditioning. 14 sizes, 7)4 to 150 hp; 4 to 303 tons. Incorporate a com plete refrigeration cycle with all neces sary components. Factory assembled, 7)4 to 80 hp; field connected, 100 to 150 hp. Series ECZ, 10 to 150 tons. Sectionalized construction, all parts easily ac cessible. Bare copper coils for Freon-12. 1241 Air Conditioning s"teme York Corporation York, Pennsylvania Factory Branches and Distributor Engineering and Sales Offices throughout the World. Air Conditioning and Refrigeration for maintaining proper atmospheric conditions for industrial processes or comfort requirements. Installations of unit and central systems in a wide range of capacities and types for every design need. Turbomatic Compressor--a completely assembled "packaged" compressor with a capacity range from 115 ton to 350 ton. Factory assembly speeds installation of complete system jobs. Single stage aluminum alloy impeller, reduced shaft diameter, simplified shaft seal, permit higher rpm, less friction than in multi-stage equipment, assure longer service life. Model L-95, York's largest Turbomatic, weighs only 1600 lb. Other turbos available over wide range of capacities--up to 2500 ton refrigeration for Freon water cooling duty--suitable for steam turbine or motor drive. Self-contained dynamically balanced, non-vibrating V/W type reciprocating compressors available in capacities up to 350 ton refrigeration in a single unit, with water cooled or economizer type condensers. Effi cient automatic capacity reduction available for economical operation at reduced load. . Yorkalre Complete Systems--Three basic types available for big building applications. Designed for maximum flexibility in each case. York Cl System utilizes York Turbo or V/W Compressor as cooling source, with one air intake, usually at top of building. Air brought in by fan, filtered, dehumidified..Sound trap elim inates fan noise. Units in individual rooms also provide heat in winter by hooking into existing hot water system. York CF System cools in summer, heats in winter, uses Turbo or V/W compressor for cooling, building's hot water system for heating. Air intake located in unit in each room. Economical for buildings where space is at a premium. No large fan room required; units individually operated. York CSA System--Individual room units cool in summer, heat in winter, require no fan room for cooling equipment, hooks easily into existing hot water system. Units can be added one room at a time; no extensive alterations required. . ' 1242 Air Conditioning Air and Water * Cooled Units ADDISON PRODUCTS COMPANY Addison, Michigan Specialists in Air Conditioning Systems Contract Manufacturers Addison Units are built to Customer Specifications WATER COOLED AIR COOLED Addison air conditioning systems are available in vertical or horizontal types for water cooled operation. The vertical system is available in 2 hp, 3 hp and 5 hp sizes. 2 hp and 3 hp size3 mounted within a 24 in. x 20 in. x 40 in. frame. 5 hp unit available with single compressor or two compressor, two stage cooling operation. Both 5 hp models mounted within a 38 in. x 24 in. x 40 in. frame. Vertical units are designed to install easily in companion cabinet for hi-boy type furnace installations or, if desired, in hi-boy type cabinet for space cooling. The horizontal type is available in 2 hp or 3 hp sizes. The entire assembly is mounted within a in. x in. x 42^ in. frame. Louvered or solid drain pans are optional. The horizontal system is ideal for a companion cabinet installed with lo-boy furnace installation. It may also be used in limited spaces such as crawl space or attic type of installations. The horizontal attic air conditioning sys tem is available in Economy 2 hp size. This system was designed primarily for small home operation where economy is especially important. Dampered air flow in evaporator plenum provides zone cooling. Air cooled systems are also available in 2, 3 and 5 hp sizes. Condensing as sembly is designed for outdoor operation with vertical or horizontal evaporators designed to fit in plenum of existing air ducts of heating system. These units are ideal for areas where water supply , is critical. All systems are designed and engineered to customer specifications and require.ments, subject to Addison high quality standards. All sheet metal parts have a corrosion resistant finish. All service connections are of standard size in con struction and easily accessible. Equip ment is Underwriters* Laboratories ap proved. 1243 Air Conditioning !rC"S?"ter A^wiRicAN-c^tattdatfd AIR CONDITIONING DIVISION ELYRIA, OHIO Executive Offices: 40 West 40th St., New York 18, N. Y. A Division of American Radiator & Standard Sanitary Corporation Distributors are listed under "Air Conditioning Equipment & Supplies" or "Furnaces" in the yellow pages of your telephone directory. AMERICAN-STANDARD SUMMER AIR CONDITIONERS RESIDENTIAL UNITS--WATER COOLED. All are compactly designed and have 100 per cent hermetically sealed refrigerant circuits covered by American-Standard Air Conditioning Divi sion 5 Year Protection Plan. Models HCA-2H and HCA-3H, 2 hp and 3 hp horizontal units, less blower, utilize the blower of new or existing furnace, as do Models HCA-2, -3, -5, offer ing choice of 2,3 or 5 hp cooling. Models HCA-2F, -3F, -5F, equipped with blower, can be used either with forced air fur nace, or independently with their own ducts, for 2, 3 or 5 hp cooling. HCA-l RC-tV RESIDENTIAL UNITS--AIR COOLED. New, outdoor air- P cooled condensing units AC-2A (2 hp) and AC-3A (3 hp) have 100 per cent hermetically sealed refrigerant circuits covered by 5 Year Protection Plan. Easily connected to evaporator unit installed in discharge air duct of new or existing forced air RC-tHA furnace. Evaporator units RG-2HA and RC-3HA (2 hp and 3 hp respectively) are for horizontal air flow; RC-2V and RC-3V (2 hp and 3 hp respectively) are for vertical air flow. COMMERCIAL UNITS. These are self-contained, water-cooled package units for 2, 3 or 5 hp cooling of shops, offices, res taurants and other business establishments. All have 100 per cent hermetically sealed refrigerant circuits covered by 5 Year Protection Plan and are finished in Cooltan--a neutral shade that blends with any color scheme. HCA-IF CCA-S AMERICAN-STANDARD YEAR 'ROUND AIR CONDITIONERS GAS-FIRED HEATING WITH 2 hp OR 3 hp COOLING. A complete winter-summer unit under a single jacket. Choice of 7 size combinations ranging up to 150,000 Btuh input winter heating with 3 hp cooling for summer' air conditioning. The 100 per cent hermetically sealed refrigerant circuit is covered by 5 Year Protection Plan; slides in or out as a complete unit for easier installation or servicing. The air conditioner is available less cooling circuit for owners who need immediate winter air conditioning but prefer to add summer air condi tioning at a later date. C-OB-W OIL FIRED HEATING WITH 2 hp OR 3 hp COOLING. This unit, complete under single jacket, has the same easy slide-out refrigerant circuit as the gas-fired model listed above; may be Obtained less cooling circuit. Choice of 2 hp or 3 hp cooling and either 85,000 or 112,000 Btuh winter heating output at bonnet. Features include heavy gauge steel heating element specifically designed for oil firing to insure efficient, economical combustion of fuel. 1244 k r American-Standard Air Conditioner Div. Air Conditioning Summer and Winter Air Conditioners AMERICAN-STANDARD GAS-FIRED FURNACES GAS BASEMENT. Model GLA low-boy completely assembled and wired, blower-equipped, in 8 sizes, from 75,000 to 300,000 Btuh input, all Installation Tested* at the factory. Model SG gravity furnace, equipped with automatic controls, in 4 sizes, from 85,000 to 150,000 Btuh input. GAS UTILITY. Compact, narrow-width Model GUA (smallest size is only 13 inches wide), completely assembled, wired and Installation Tested* at the factory. Seven sizes, from 50,000 to 200,000 Btuh input. A.O.A. approved models for 1-inch or zero clearance installations. Models with belt-driven or directdrive blowers available. GAS COUNTERFLOW. New, more compact Model GCA for perimeter heating installations in modern, slab type homes. Permits 1-inch clearance at sides, zero clearance at rear; can be installed on combustible flooring if optional sub-base is used. Three sizes--75,000, 100,000 and 125,000 Btuh input-- completely assembled, wired and Installation Tested* at the factory. , GAS HORIZONTAL. Unit can be suspended from ceiling, in crawl space or placed on attic joists. Five sizes, from 60,000 to 140,000 Btuh input, all completely assembled, wired and Installation Tested* at the factory. Models available with vertical or horizontal flue outlet. SHC Installation Testing of completely assembled unit at factory includes actual gas firing and operation of blower and controls. AMERICAN-STANDARD OIL-FIRED FURNACES OIL BASEMENT. Models 1307-OB and 1310-OB for small and Pmedium size homes are approved for installation on com bustible flooring. Convertible to gas with American-Standard GP package. Six sizes, from 67,000 to 167,000 Btu capacity IS07-OB 1310-OB OIL UTILITY. Model 1200-OB units are designed for small homes and individual apartments. Standard and zero clearance models available. Three sizes--79,000, 96,000 and 102,000 Btu output at bonnet. Convertible to gas. ItOO-OB 1400-OB OIL COUNTERFLOW. Model 1400-OB units for basementless and slab construction houses, are approved for zero clearance installations; convertible to gas.'Three sizes--79,000, 96,000 and 102,000 Btu output at bonnet. OIL HORIZONTAL. Model HS units can be placed on attic joists, suspended from ceiling or installed in crawl space; are applicable either to perimeter or conventional heating sys tems. Three sizes--93,900 and 102,000 Btu output at bonnet. AMERICAN-STANDARD ELECTROSTATIC AIR CLEANER MAGNE-FILTER. Model EF is a dry type electronic air filter, easily installed in the return air duct of warm air furnace or summer air conditioner. Traps even smallest particles; remove pollen, bacteria, dust and smoke from the air. Made in 7 sizes; to meet the requirements of any installation. No water con nection required. ' 1245 Armstrong Furnace Company Columbus, Ohio p' WARM AIR HEATING EQUIPMENT Domestic Winter Air Conditioning Furnaces Basement Models--Gas, oil, or coal; 17 basic sizes; ideal for all types of new homes; widely used to replace obsolete furnaces. Gas-fired: 7 sizes, 85,000 to 250.000 Btu/hr input. Oil-fired: 6 sizes, 80.000 to 200,000 Btu/hr output. Coalfired : 4 sizes, 20 to 27 inch. Counterflow Models---Warm air deliv ered at bottom to ducts in slab floor or crawl space. Fits into closet or utility room corner. Gas-fired: 3 sizes, 65,000 to 105.000 Btu/hr input. Oil-fired: 2 sizes, 80.000 and 110,000 Btu/hr output. & JCf m Hi-Boy Models--Designed for modern basementless homes and homes with basements. Approved for operation in close quarters. Quiet, compact, attrac tive. Gas-fired: 6 sizes, 65,000 to 125,000 Btu/hr input. Oil-fired: 2 sizes, 80,000 to 110,000 Btu/hr output. Horizontal Models--Lies flat in crawl space or attic, or suspended from ceiling anywhere. Occupies no floor space. Gas- fired: 4 sizes, 70,000 to 135,000 Btu/hr input. Oil-fired: 4 sizes, 80,000 to 165,000 Btu/hr output. B|fB| DOMESTIC GRAVITY FURNACES H-HI All furnaces listed above are forced air furnaces. For homes suited to gravity heating, Armstrong has models for basement installations, to burn oil, coal or gas. 10 sizes. HEAVY DUTY INDUSTRIAL FURNACES Seven sizes, either gas or oil-fired. Standard models, 350,000 and 450,000 Btu/hr gas or oil-fired. Stainless steel heat exchanger. Two blowers. Induced draft. Units may be installed vertically (as illustrated) for air delivery upward or suspended for air delivery downward or horizontal. Factory assembled, wired and fire-tested. Suspended units, oil-fired only. 225,000, 275,000, and 350,000 Btu/hr. Stainless steel combustion chamber, aluminized steel secondary tubes. Factory .assem bled, wired, and fire-tested. 1246 i ft* 'tv. I & X< i! 4 '-S'." Air Conditioning Air-Cooling, Blower Automatic Heating Armstrong Furnace Company ARMSTRONG FURNACE COMPANY Columbus, Ohio Up-Flow Coil Down-Flow Coil COOLING EQUIPMENT Air Cooled Air-cooled summer air conditioners designed for convenient installation. Evaporator unit, including only those elements which'must be located close to the cooling coil is installed in side. Other parts are incorporated in the condensing unit, which is usually installed outside. Evaporator unit is con nected to the condensing unit by two copper lines--a liquid refrigerant line and a suction line. Motor-compressor unit guaranteed in writing 5 years. Up-flow, down-flow, horizontalflow, and independent unit cooling coils, 2, 3, 5-ton capacities. Water Cooled Residential Models Horiztmial Flow Coil Vertical or horizontal companion units to harmonize with Armstrong winter air conditioners. Entire refrigeration unit hermetically sealed. Five year written guaranty. Water-cooled. Vertical units: 2, 3, 5-ton capacities. Horizontal units; 2 and 3 ton capacity. Duel Cooler Write for the Armstrong consolidated catalog, a useful refer ence book on heating and cooling. Includes detailed specifi cations, dimensions, illustrations and descriptions of all Armstrong furnaces and air conditioners. Please address De partment G-5 at the plant nearest you. 1247 Air Conditioning ftjuJtLwvp * DIVISION CHRYSLER CORP Dayton 1, Ohio AIR CONDITIONING HEATING FOR HOMES, BUSINESS, INDUSTRY WATER-COOLED "PACKAGED" AIR CONDITIONING . . . 2, 3, 5, 7J4, 10, 15 hp Complete--assembled and tested at the factory. Cools, dehumidifies, filters and circulates air. Free air discharge or duct distribution. Heating coil for year 'round sendee optional. Compact--entire unit is enclosed in "Bonderized" steel cabinet of modern, FUNCTIONAL design. Oc cupies very little floor space. Easily Installed--Needs only electric, water and drain connections. Flexible--can be in stalled singly or in multiple to meet virtually every require ment. 5-year warranty on entire refrigeration cycle. WATERLESS COMMERCIAL AIR CONDITIONING ... 2, 3, 5,7J.<> hp. Uses no water, needs no plumbing, all-electric op eration. Flexibility of installation. Low cost of operation. 5- year warranty on entire refrigeration cycle. "SPACESAVER"--GAS OR OIL-FIRED FURNACES . . . 67,000 to 240,000 Btu output. Hi-Boy and Lo-Boy models heat, humidify, filter and circulate the air. "Bonderized" and insu lated cabinets. Burners start, stop and operate quietly, have many features for high-efficiency heating. Gas models approved by A.G.A.; oil models approved by Underwriters' Laboratories. "HORIZONTAL"--GAS OR OIL-FIRED FURNACES . . . gas--48,000 to 120,000 Btu output, oil--84,000 to 168,000 Btu output. May be installed in attic, under floor, or hung from ceiling. Gas models have dual flue outlets and draft diverter mounts on either side. Completely automatic controls fully enclosed. | 'M COUNTERFLOW--GAS OR OIL-FIRED FURNACES . . . i ft 65,000 to 100,000 Btu output. May be installed in closet. Fully automatic. Quiet rubber-mounted blower. Front flue outlet. 1Factory-assembled, easy to install. . RADIAL COMPRESSOR UNITS ... 10 to 125 hp. These heavy-duty units, for use with Freon, are especially designed for air conditioning or refrigeration. Radial compressors are direct connected and have force-feed lubrication. Automatic capacity-reduction. Light weight, economical to operate.' 1248 :F "S AS- Air Conditioning AjUXLwup / DIVISION CHRYSLER CORP) Dayton 1, Ohio AIR CONDITIONING HEATING FOR HOMES, BUSINESS, INDUSTRY "PACKAGED" LIQUID COOLERS ... 3 to 250 hp for use with Freon refrigerants. A completely assembled unit that is piped, pressure tested, dehydrated and supplied with a refrig erant holding charge. Starters and control panels optional. CENTRAL DUCT "PACKAGED" AIR CONDITIONING . . . 20, 25, 30, 40, 60, 75, and 100 hp. Self-Contained Central Type "Packaged" Air Conditioners. Utilizes the Airtemp Radial Compressor with its exclusive features. Units available with evaporative condenser or for use with cooling tower. 5-year compressor warranty on-20,-25,_30 hp sizes. INDIVIDUAL--ROOM AIR CONDITIONING UNIT ... For year 'round cooling and heating when used with central cold and hot water systems. Ideal for hotels, motels, offices. Three types--floor, wall and ceiling. Built-in controls make each unit independently operated. Two centrifugal fans provide circula tion. CONVENTIONAL--ROOM AIR CONDITIONING . . . new window models available in 14, %, 1, 1}4 hp. Flush mounts up to 3}4 in. from sash line or can be installed half in and half out. Full directional control of discharge air. Cools, filters, de humidifies, exhausts, and ventilates. Thermostatic control of temperature. CASEMENT--ROOM AIR CONDITIONING . . . Window models in ]4 and % hp. Easy inside installation without cutting or removing glass--nothing projects outside or interferes with opening, closing or locking of window. IMPERIAL--ROOM AIR CONDITIONING . . . In-The-Wall Installation for individual Room Air Conditioning--in 14, % and 1 hp. Ideal for homes, offices, motels and hotels. Filters, dehumidifies, cools, and gently circulates the air. Only 18J in. deep, fits flush on outside of building with piinimum projection on inside. Thermostatic control of temperature. IMPERIAL-- WINDOW MOUNT--in H, % and 1 hp. Fits all windows 28 in. and larger. 1249 i* - Automatic Equipment AtT K^OTVultlOTUTtQ 9 Heating and Cooling Combustion Engineering, Inc. Home Equipment Division 911 West Main Street, Chattanooga, Tennessee Heatmaster Home Heating and Cooling The simple way to heat and cool a home Heatmaster Home Heating and Cooling System is pre-englneered and factory assembled This "wet" system is assembled at the factory, ready to install on the job. The C-E units are approved by A.G.A., built and inspected in accordance with ASME code and backed by the C-E warranty. Designed to meet FHA Minimum Prop erty Requirements for financing. C-E HOME HEATING UNIT Model 110GHB-88 LM Height--36' Width--24' Depth--24*4* Flue Dia.--64 Inlet--1' I.P.S. Outlet--1' I.P.S. Gas Supply--*4' I.P.S. Drain--*4' I.P.S. Weight of Complete unit--Approx. 250 lbs (includ ing controls and circulator) FURNISHED AS STANDARD WITH: Circula tor Gas Regulator. Gas Automatic Pilot and Safety Valve. Gas Flue Diverter (Draft Hood), Control Relay, Complete wiring and piping for simple hook-up, Three Way Control Valve Fan Control Switch, Drain Valve, Gas Control Valve (Solenoid) Temperature, Pressure and Altitude Gauge. Take just 4 sq ft of floor space The C-E Heatmaster Home Heating and Cooling System uses only standard pip ing and wiring practices. Compact room conditioners are recessed between stand ard studding. C-E HOME COOLING UNIT HP Water rate Water resistance K.W. input Condenser water rate Waste water (series) Cooling tower (series) Condenser Water Resistance (series) (Parallel) Unit Weight MODEL JB200 MODEL JE300 2 24,000 Btu/hr net refrig. effect 8 gpm 5.5' of water 2.4 3 36,000 Btu/hr net refrig. effect 12fgpm 10* of water 3.4 3 gpm 6 gpm 4*4 gPm 9 gpm 7.8' -- . Approx. 280 Ids (less . cabinet) 13.5' 5.5' Approx. 308 Ids .fless 1 cabinet) BOTH MODELS HAVE CAPACITY AT A.G.A. CONDITIONS - . SEA LEVEL TO 2,000' 2,000 to 5,000' INPUT Btu OUT PUT Btu input' OUT PUT Btu Btu Nat'!, Mfd.and Mixed Gases 110,000 88,000 Liq. Pet. Gases 105,000 84,000 88,000 84,000 70,400 67,200 Electrical Supply Unit Service 110 v,, a-c., 60 Cy., 1 Phase Thermostat Serv. 24 v., a-c. Compressor: Motor: Evaporator: Tecumseh 230 v.. 1 phase or 220 v; 3 phase Sealed in vaporproof insulated cabinet. Water inlet and out let 1' FIPS. . Condenser: Water cooled. __ Overall Frame !U' wide x 17*4' deep x 26'. Size: high , . Water into chiller: 66F Water out of ' chiller: 50F .Water entering condenser: 75F Water leaving condenser: 95F ________________ SPECIFICATIONS AND DIMENSIONS--ROOM CONDITIONERS Heating Btu/hr, 200F Water Temp. Cooling Btu/hr, 42F Water Temp. Water Flow gpm Box Height Box Width Box Depth Cover Height Cover Width Filter Size Recessed Model 10-R 10,000 4,000 1.5 18*4' 14' 6' . 20*4' 16*4' 9*4'x 14' 2*4' Recessed Model 22-R 22,000 9.000 3.0 18*4' 29*4' 6' 20*4' 31*4' 9*4' x 29*4' 2*4' Free Standing Model 10-RFS 10,000 4,000 1.5 18*4' 14' 6' 20*4* 16*4' 9*4' x 14' 6*4' Free Standing Model 22-RFS 9.000 3.0 18*4' . 29*4' 6' 20*4' 31*4' ,, 9*4' x 29*4' 6*4' Fittings are adaptable for w or W I D. Copper Water Tubing-Type "L." ------ Specifications are Subject to Change Without Notice . 1250 Air Conditioning summer and winter Air Conditioners Hydraline Products Division Borg-Wamer Corporation General Sales Office: 18538 Mack Avenue Detroit 36, Michigan IM---t-l-M--IIIKO ,i District Engineers in Principal Cities of the United States YEAR 'ROUND REICKaEOES-MaSAKED ROOM AIR CONDITIONERS Hydraline combines in one central forced-water heating and cooling system the desirable features of two separate systems--gentle forced-water heating or cooling to the room, filtered air circula tion in the room. The basic Hydraline units measure only 17% in. x 14 in. x 4% in. and may be fully recessed between standard studs or under floor between joists. Basic unit in wail (before plaster). Up to 186 cfm 9M-Btu, heating--lM-Btut cooling. A manual blower speed control with each unit provides individual room con trol. Automatic Control Kits also provide thermostatic control of indi vidual room temperatures. Balanced heating or cooling is no problem even in the most rambling type of structure because Hydraline units are controlled independently of the central system. Model HAC-185 Completed in-wall installation with grille attached. As.many thermostatically controlled zones can be specified as are needed without the need of a separate circulator for each zone. With modulating controls, Hydraline units can be economically combined with Radiant Panel Heating, such as snow melting, where such combinations are specified. Hydraline Chiller Package (May be added later) Mechanical specifications, system de signs and technical data available upon request. 1251 Hydraline Boiler Package (Gas or Oil Fired) Air Conditioning oSSST"" Hayes Furnace Mfg. & Supply Co. 2929 South Fairfax Ave., Los Angeles 16, Calif. (Telephone Texas 0-3734) Contact Nearest Representative Associated Refrigeration Engrs., Montgomery, Ala. M. Blazer & Son, Passaic, N. J. Blue Flame Supply Co., Atlanta, Ga. . Eugene Bolstad, Edmonton, Alberta, Canada E. B. Bomar, Phoenix, Arizona Boyd Engineering Co., Albuquerque, New Mex., and El Paso, Texas Dealers Supply Co., Atlanta, Ga. Reube 0. Emery, Nashville, Tenn Jewell & Co., Hot Springs, Ark. Leudecke Engineering Co., Austin, Texas Homer Maxey & Co., Lubbock, Texas McCombs Supply Co., Denver, Colo. Noland & Co., Newport News, Va. O'Connor-0klahoma Co., Oklahoma City, Tulsa, Okla., and Wichita, Kansas ^. Smith Steam Specialty Co., Kansas City, Mo. Tay-Holbrook, Inc., San Francisco, Calif. F. R. Young, Houston, Texas : DUCT FURNACES Constructed of Type 321 Stabilized Stainless Steel. Non-cor rosive property of heat exchanger permits installation down stream of cooling coils or washer. Heat exchanger will not corrode when subjected to continuous ventilation during the summer season. Designed for continuous blower operation for offices, theaters, schools, churches, factories. Air throughput in either direction. Draft Hood and Vent Manifold reversible, adjustable for both horizontal and vertical connection, 14 sizes, 80,000 to 600,000 Btu per hr input in 40,000 Btu incre ments. A.G.A. certified for all gases. MODEL SED-E Non-corrosives type 321 stainless steel heat exchanger. Per mits installation downstream of cooling equipment, for con tinuous blower operation. Air throughput in either direction. 80,000 to 600,000 Btu input. MODEL SED-S Same as SED-E except controls are at the side, instead of at the end where accessibility requires. SED-S is available in sizes from 80,000 to 600,000 Btu input in increments of 40,000 Btu. Both SED-E and SED-S can be used for industrial applica tions for drying. FORCED AIR FURNACE MODEL SEC Heat exchanger constructed of identical die formed sections, of type 321 stabilized stainless steel. Sections are seam and arc welded. One piece cast iron burners with drilled ports. Oversize double inlet blower. Long hour motor. Equipped with glass filters. Can furnish permanent filters at extra cost. Finished in baked silver grey. 6 sizes 70,OOQ to 245,000 Btu per hr input in 35,000 Btu increments. For natural, manufactured and L.P. gases. Can be used for 0 clearance ALL HAYES FURNACES ARE A.G.A. APPROVED 1252 ' Hayes Furnace Mfg. & Supply Co. Air Conditioning . &`rKS!8m"t DUCT FURNACE MODEL SED-VF Tested and approved as a DUCT FUR NACE!--Constructed of type 321 sta bilized stainless steel. Re-circulated or fresh air is introduced through bottom, sides or back of furnace. Equipped with air bypass. Handles large cfm per Btu input. Vent in front of furnace. Made in 6 sizes from 70,000 to 245,000 Btu per hr input in increments of 35,000 Btu. For natural, manufactured and L.P. gases. FORCED AIR SUSPENDED FURNACE, MODEL SES Equipped to install in a suspended duct system. Inlet and outlet designed for sheet metal duct connection. UNIT HEATER MODEL SEU Used where room air is to be recircu lated. Diffuser outlet with adjustable vertical and horizontal vanes. Both types of Suspended units are designed for factories, commercial and other large Btu requirements -- equipped with brackets for suspension, save floor space. Double inlet forward curve blower. Continuous duty variable pitch drives; cast iron, raised port, precision ma chined burners. Made in sizes 80,000 to 600,000 Btu per hr input in 40,000 Btu increments. For natural, manufactured and L.P. Gas. Centrifugal backwardly curved blower type . . . the blower wheel cannot be overloaded regardless of length or curves in the duct or variation in design. It is belt driven to provide flexibility. The ventilator is mounted on a built up curb on the roof. Special features in clude low profile with streaimlined de sign and a corrosion resistant housing. The motor and fan bearings are grease packed ball bearings and are out of the air stream. A manually operated safety cutoff switch is provided. dimensions UNIT SIZE 1000 1200 1300 1600 1800 2000 2200 2400 -2700 3000 3300 3600 4000 4400 4900 5400 AB 2444 15V* 28 , i/w 29 2434 35V* 26V* 39>4 2134 43 .30 4634 49V* 55V4 666034 30 V* 3234 3434 8634 40 4234 eon85 45H 49 9834 54 57 V* C nv* 13 13V& 2106V* 20 22V* 25 28 31 33V* 4UV* 40 44 V* 50 55 D 2119V* 21 24 V* 28 28 30 V* 33 36 39 41 48V* 52 56 62 67 E 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 APPROX. SHIP. WT. 130 137 275 300 325 350 630 700 795 1120 1500 1900 1253 Air Conditioning Automatic Equipment Heating--Cooling heating Mue||er Climofrol Division of Worthington Corporation Milwaukee 15, Wisconsin coold,g Type 101 (Gas)--201 (Oil) Gas or oil, steel, gravity furnace, convertible. Modular design. Available in three sizes: 135-, 160-, 180,000 Btu. (Type 120-220 also available iTnyp9e0,010005 B(tGuaisn)p2u0t2s.)(Oil) Gas or oil, steel, winter air conditioners. Convertible. Available in eight sizes with input ratings of 150,000 to 675,000 per hour. Type 116 (Gas) 216 (Oil) Gas or oil, lowboy winter air conditioners. Four sizes-- 90,000 to 150,000 Btu input. Convertible. Types 119 (Gas) 219 (Oil) also available. Mueller Climatrol Air Conditioning hS'SSTM' Type 160 Gas, direct fired, steel, suspended unit heater. Horizontal air tube design; propeller type fan. Available in nine sizes, with A.G.A. ratings of 25,000 to 225,000 Btu input. Type 10 Gas-fired, cast iron boiler for residential heating, and hot water supply. A.G.A. approved for all types of gas. Sizes range from a 3-section, 54,000 Btu input to a 15-section, 378,000 Btu input. Controls enclosed. (Also with controls exposed. Type 11). Type 21 Gas-fired, cast-iron boiler for larger installations. Sectional construction, (sizes increase in increments of 70,000 Btu). A.G.A. rated in sizes from 6-section, 350,000 to a twin 31-section, 4,200,000 Btu unit. Type 117 (Gas) 217 (Oil) Versatile unit that meets the requirements of either a low boy or highboy. Available in four sizes--80,000, 100,000 and 125,000 and 150,000 Btu input. Shipped assembled, pre-wired. Enclosed burner. . Type 118 (Gas) 218 (Oil) Counterflow winter air conditioners. For perimeter heat ing, slab or crawl-space homes. One size only--100,000 Btu input. Types 115 (Gas) aTnypde211524(O(Gila)sa)v2a2i4la(bOleil)in901650,0H0i0ghBbtuoyinwpinutte. r air conditioners. Four sizes; 80-, 100-, 125-j 150,000 Btu input. Compact. Shipped assembled and pre-wired. Type 906 com panion cooling unit available. Type 900- 912- 914 Summer air conditioning coil units; for operation with remote air- or water-cooled condensing units. Type 900- installs vertically with any forced air unit. Available in 2, 3, 5 and 7^ ton sizes. Type 912- installs horizontally. Avail able in 2 and 3 ton sizes. Type 914- Counter-flow. Available in 2-3 ton Bizes. Type 903 Self-contained cooling unit for installation with any warm air system, new or existing. Refrigeration cycle is factory-assembled, charged. 2, 3 and 5 hp sizes. Water cooled. Condensing Units Remote Type 908, air-cooled, (illustrated). Water-cooled Type 902 also available. Both in 2, 3, 5 and 7}<j hp sizes. Type 907 remote condenser, for con verting water cooled units. Available in 2,3, and 5 hp sizes. Type 128 (Gas) 228 (Oil) 928 Versatile combination heating and cooling unit. Casing has integral compartment for cooling cycle. One size only, 100,000 Btu. Type 165 Gas-fired horizontal winter air conditioners. Available in two sizes with A.G.A. rating of 100,000 and 120,000 Btu. Shipped assembled and pre-wired. Large sTiyzepece2n53trifuOgial-lfirbelodwheor.rizontal winter air conditioner, or blower heater. Up-draft design. All welded steel heat exchanger. Convertible to gas firing. Available in five sizes, 110,000 to 350,000 Btu input. 1254 . . Type 904 Self-contained cooling unit for stores, restaurants; or used with duct sys tems in homes with steam or hot water heat. Built-in blowers and filters. 2, 3, 5, 7J, 10 and 15 hp sizes. Type 920 For heating and cooling in hotels and commercial buildings. Cooling is self-contained--air cooled. Heating through central system with steam or hot water coil. Operates with 370 cfm. Cooling is 1 hp. Type 911 Self-contained, air-cooled summer air conditioner. May be installed singly or as multiple units in conjunction with existing duct system, or with its own duct system. Available in 1 hp size. 1255 Air Conditioning Lamneck Division Clayton & Lambert Mfg. Co. 1026 Lamneck Street, Middletown, Ohio Phone 2-6304. Distributors in Principal Cities -a- Fittings and duct work illustrated are selected to indicate range of design and construction of the Lamneck line distribution pipe and fittings for heating and cooling. This line is designed with full-throated elbows and angles for full efficiency to simplify later air cooling demands. Line includes complete range of perimeter heating fittings. New catalog 5629 available. No. 700-P standard L-shaped corner seam duct. Manufactured in 8 in. depth, 16 in. and 32 in. length, in widths from 4 in to 26 in. Also available as No. 700-T, standard U-shaped center-seam duct. Duct sections furnished complete with No. 7S7-T Snap-lock connector. No. 7n No. 794 combination top and side takeoff (adjustable collar). Available in 4 in., 5 in., 6 in., 7 in. and 8 in. sizes. No. 763 45 degree angle boot available in register sizes 2)4 in. x 12 in. and 2)4 in. x 14 in. for 6 in. systems and 2)4 in. x 10 in. for 4 in. systems. No. 7CS No. 764 center end register boot available for register sizes from 2)4 in. x 12 in. to 6 in. x 10 in. No. 700 6 ft Snap-lock pipe ________ ^ 5 ft Snap-lock through 8 in. No. 700 wall stack. Complete with No. 737 connector attached to each half. Available in 3)4 in. depth, 10 in. to 14 in. width, and 15 in. to 60 in. length. pipe available 1256 . Air Conditioning Automatic Equipment Gas Fired Units Norman Products Company 1150 Chesapeake Avenue, Columbus 12, Ohio Manufacturers of a complete line of oas heating and air conditioning Fequipment. or information contact factort representative at Columbus headquarters bat.tcb office. Norman Southerner--Horizontal forced air gas furnace for compact home instal lation. Factory assembled and tested. Right or left-hand unit. Newly designed heat exchanger provides more efficient heat transfer. Five sizes: 70-85-100-120 140 thousand Btu input. Norman Duct Furnace--for Commercial and Industrial Heating--in combination with air conditioning. Installed in ducts of warm air and air conditioning system where air is circulated by remote blower. 70-85-100-120-140 thousand Btu input. Norman `360'--Gas fired overhead forced convection heater. "Circular" heat dis tribution eliminates hot blasts and cold comers. Streamlined design. UL listed. 100,000 But input. Norman Gas Conversion Burners--Com mercial-Industrial in 4 sizes with ratings from 300,000 to 2,000,000 Btu. Converts apartment, commercial and industrial heating plants. Residential burners, ratings 50,000 to 300,000 Btu. Norman Blower-Filter Unit... a com pact blower, motor, and filter package for handling air requirements of nesting and cooling systems up to 5 tons capac ity. Entire unit is housed in a heavy gauge, steel cabinet. Doors on either side Norman Direct Gas-Fired Unit Venti lator for schoolrooms, offices, stores. Low-cost, self-contained central heating and ventilation system. No piping, or expensive outside ventilating system needed. Easy td install . . . saves space. 85,000 Btu input. Norman Winter-Summer Air Condi tioner--Horizontal year round air condi tioner combining Norman Duct Furnace with independent cooling and blower assembly in one package. Damper com partment operated by single thermo static control. Cooling only in Separate Package for Existing Furnace. Cooling available in 2 or 3 ton unit, heating in capacity of 70-85-100-120-140 Btu input. DESCRIPTIVE LITERATURE on all Items listed above Is available from manufacturer. Write for detailed specifications. 1257 Mr Conditioning ^"dticmiuipm"t Pennsylvania Furnace & Iron Company 316 North Pine St., Warren, Pennsylvania Representatives are in principal gas using centers. Pennsylvania Gas Furnaces, Floor Furnaces, Conversion Burners, Pennco Gas Fired Boilers for steam, vapor and water, for residences, schools, hospitals, hotels, stores, and any other type of building that requires a heating plant. A full and complete line of sizes. SERIES 6 PENNCO BOILER The Series 6 Pennco boiler is a large capacity type boiler. It is a cast iron sectional type with all sections having hollow pro jections which add to the heating surface. The sections are assembled on a specially designed steel base. The design of this base greatly reduces assembling time and reduces installa tion costs. The Series 6 boiler sections are hydro-statically tested to 150 psi. All boilers are constructed in accordance with the A SME code. They are also approved by the A.G.A. Testing Labora tory. Twenty-seven different sizes are available from 400,000 Btu per hr input to 4,400,000 Btu per hr input. All Series 6 Pennco boilers are furnished with completely automatic controls. SERIES 2 fis 3 PENNCO BOILERS Series 2 & 3 Pennco boilers are' the cast iron sectional type with all sections hav ing hollow proj ections to add to the heat ing surface and efficiency. Both the Se ries 2 & 3 are made in either Standard or Deluxe type. The Series 2 is made for water only in four sizes from 175 sq ft EDR to 350 sq ft EDR. The Series 3 is made for steam, vapor 'br water and is made in eight sizes from 96,000 Btu per hr input to 400,000 Btu __ per hr input. SERIES IDA PENNSYLVANIA FURNACES The Series 10A Pennsylvania Forced Air Furnace is constructed with an all steel combustion chamber and corrugated steel radiator. All joints and seams are continuous welded assuring gas tightness. A two-tone blue baked enamel casing contrib utes to the beauty of the Series 10A Pennsylvania furnace. This Series furnace is made in seven sizes, ranging from 75,000 Btu per hr input to 225,000 Btu per hr input. . SERIES 10-V VERTICAL TYPE PENNSYLVANIA FURNACE The Series 10-V vertical type furnace is constructed with the same type combustion chamber and radiator as the Series 10 horizontal. This unit is compact and made in three sizes; 60,000, 90,000 and 120,000 Btu per hr input. SERIES 11 AND SERIES 11 ULTRA The Series 11 and Series 11 Ultra are newly designed forced air furnaces. The Series 11 Ultra is constructed of 12 gauge steel to comply with SUR and for burn ing fuel oil and gas. Both series are available in three sizes--75,000, 100,000 s and 125,000 Btu per hr input. SERIES 55 PENNSYLVANIA GRAVITY FURNACES This new line of Pennsylvania Gravity Furnaces is made in six sizes--75,000 to 250,OtiO Btu per hr input. A two-tone blue enamel finish casing and special designed lining which forms a dead air space contribute to.the high efficiency of this unit. PENNSYLVANIA CONVERSION GAS BURNERS The Pennsylvania Conversion Gas Burner is made in three sizes and ranges in size from 75,000 Btu per hr input to 350,000 Btu per hr input. 1258 f Air Conditioning Automatic Heating and Cooling l&v/x Refrigeration Appliances, Inc. Mi) West Lake Street, Chicago 7, Illinois / MAKERS OF AIR CONDITIONING AND REFRIGERATION EQUIPMENT SINCE 1931 A--New Krack Komfort Masters Quiet remote type air conditioners. Models adaptable to practically all re mote comfort cooling and heating uses. Designed for ceiling or floor mounting, use with or without ducts. Can be sup plied without cabinets for furred-in in stallation. Volume control dampers and 3-speed control on fan motors give wide range of air velocity modulation. Wide choice of coil arrangements for direct expansion, water, steam, or combina tions. Sizes: 2, 3, and 5 ton. Removable filters. B--New Krack Furnace Bonnet Koils Convert new or existing forced air fur nace duct systems to summer cooling service with minimum installation prob lems. Compact V-bank arrangement of air-conditioning coils. Three models have 24,000, 36,000, and 60,000 Btu per hour nominal capacities. C--New Krack Transom Komfort Conditioners Quiet remote type cooler and heater for multi-room offices and commercial, in stitutional, and private housing. Direct expansion, chilled water, hot water. Op tional 3-speed fan control. Two models handle 410 and 480 cfm. D--Krack Air Kooled Kondensers Eliminate all water problems. Easy, in expensive installation and maintenance. Five models, 1 to, 7.5 ton certified nomi nal capacities based on 110 F condensing temperature and 90 F ambient. E--Krack Koils Air-E-Fex series air conditioning coils . . . % in., in., % in. tube surfaces, for . all sizes of installations, old or new. Patented construction features give in creased strength, reduce static re sistance. Evaporative Condensers & Cooling Towers Floor types for indoor and outdoor ap plications. Nine sizes 5 to 50 ton. 1259 Write for neto detailed bulletin*! Rheem Manufacturing Company Chicago, 29, Illinois Sparrows Point 19, Md. REGIONAL OFFICES ,, 4381 Fibestone Bi.vd., Sooth Gate, Calif. 7600 S. Kedzie Ate., Chicago 29, III. 3693 E. Maboinal Wat, Seattle, Wash. 1025 Locewood Dbive. Houston 20, Tex. Export Sales Office: 477 Madison Ave., New Yohx 22, N. Y. Every Rheem Furnace is "Fire-Tested** with pilot and burners igpited, Automatic oontrols, safety checks, operational and construction details must pass rigid tests. WARM-AIR HEATING EQUIPMENT ' GAS-FIRED Fully automatic, factory-assembled, forced-air furnaces of all-steel, electrically welded construction. "Flame-shaped" combustion chambers (in all but horizontal models) and multiple channel heat exchanger prevent expansion-contraction noise, and provide high heat transfer in limited space. All models feature built-in draft diverters, except for 3302 gravity model and 1603 B floor furnace, and enclosed con trols. A.G.A .-approved for natural, mixed, manufactured and LP gases. Imperial Highboy--Model 3202--for first-floor utility room or small basement installation. Top rear flue outlet. Side or bot tom filter frames. Knockout plates on casing sides for optional cold-air return. Eight sizes--from 85,000 through 300,000 Btu/ hr input--assure a tailored-heat-loss installation for small to largest residences, commercial buildings, churches and stores. 2-tone grey and green baked enamel finish. Imperial Lowboy--Model 3402-- for basement installation. Top rear flue outlet with built-in draft diverter. Four sizes from 85,000 through 150,000 Btu/hr input. Completely insulated jacket, finished in attractive grey and green baked enamel for safe, exposed recreation room placement. Standard Highboy--Model 3203S--"File cabinet" styled for compact utility room, hall, closet or small basement installa tion. Top front flue outlet. Six sizes from 60,000 through , 150,000 Btu/hr input finished in pearl-grey baked enamel. All models approved for zero clearance. Standard Lowboy--Model 3402S--designed for even limited overhead clearance basement installation. Top rear flue outlet with built-in draft diverter. Four sizes from 85,000 through 150,000 Btu/hr input. Poly-chromatic, baked-on grey enamel finish. Oversized glass fibre filters assure high dust removal efficiency. Horizontal Furnace--Model 2400-Jor "perimeter" heating or conventional duct systems. Suitable for attic, attached garage or basementless home crawl space_installation. May be suspended from roof rafters or ceiling joists, or rigid support brackets can be placed on bottom of unit for base setting. Five sizes from 60,000 through 140,000 Btu/hr input. Counterflow Furnace--Model 3205-- for "perimeter" heating applications. 80,000 and 100,000 Btu/hr input sizes, both A.G.A-approved for zero clearance installation. Readily accessible blowerfilter assembly in top of unit. Ample space in bottom for dehumidifier place ment. Gravity Furnace--Model 3302--de signed for low cost installation in base ments of smaller, compact houses. Four sizes from 77,000 through 150,000 Btu/hr input. Piping and controls fully enclosed in insulated, grey baked enamel-finished jacket. Optional side gas connection. 1260 Ift ft ft -V- Rheem Mfg. Co. Air Conditioning Atttomatle Heating RHEEM OIL-FIRED HEATING EQUIPMENT Highboy--Model 2448, Lowboy--Model 2446, and Counterflow--Model 2444, are pres sure atomizing oil-fired. 90,000 and 112,000 Btu/hr bonnet output sizes in all three models. Additional 140,000 Btu/hr bonnet output size available in Lowboy. "Air foil" design in convoluted heat exchanger assures rapid heat transfer, and expansion and contraction without, noise. Factory-assemblea burner and support for easy, accurate positioning during installation. All models readily convert to gas-fired furnaces. RHEEM SPACE HEATING EQUIPMENT Four types of space heaters for small homes, "hard-to-heat" rooms and small commercial applications. All are A.G.A.approved for natural, manufactured, mixed or EP gases. Flat floor and dual wall (series 1603B) registers in 25,000,35,000 and 50,000 Btu/ hr input sizes. Only 25% in. overall depth. 2-way adjustable head on dual wall model for easy installation in walls of varying thickness. Console heaters (model 1703) in similar input sizes with minimum space requirements. Tailored design in golden tone finish. Available with automatic or manual controls. Recessed wall heaters (model 1801) in 28.000 Btu/hr input single wall unit and 50.000 Btu/hr input dual wall units. Both models60 in. high, 17 in. wide, in neutral ivory casing. Thermostat or manual controls. RHEEM AIR CONDITIONING EQUIPMENT Year 'Rounder--Model 3103--offers forced warm-air heating and summer air conditioning controlled by a single thermostat. Summer-winter changeover damper' leaves control circuits energized during transfer. Burner operates quietly, efficiently on all gases. Models available with water or air cooled refrig eration condensers. Water cooled refrigeration circuits her metically sealed for life. Remote air cooled condenser field installation work involves only two refrigeration lines. Wide selection of furnace and cooling capacities. Add-on Conditioner--Model 3150--provides year `round air conditioning when installed beside any Rheem warm.air heat ing furnace. For economical summer air conditioning, unit may be combined with existing warm air, or wet heat systems, or used in houses without heating systems. 2 and 3 ton water or air cooled models. Thermostat available, including "off-on" switch. Completely automatic controls. Water cooled refrigera tion circuits hermetically sealed for life. Only work required for field-installed air cooled units involves two refrigeration lines. 1261 ] i; ;j ' 1] :ii -I! t) i .5 .V i. .1 ! Automatic Equipment Air Conditioning Heating and Cooling Air Conditioning Division Servel, Inc. Evansville 20, Indiana . SERVEL All-Year GAS AIR CONDITIONERS 5.4-TON MODEL AND COOLING TOWER Complete year-round air conditioning. Delivers 5.4 tons of refrigeration, and 96,000 or 144,000 Btuh of heating output depending on model. Fully automatic. Induced draft type tower with capacity to match model DE unit. Servel Air Conditioning Division Air Conditioning Automatic Equipment Heating and Cooling SERVEL ABSORPTION REFRIGERATION CYCLE Model DYCS 33-TON MODEL AND COOLING TOWER Deluxe unit for medium-size homes. Sup plies 3.3 tons of refrigeration, and 96,000 Btuh of heating output. Fully automatic. Induced draft type tower with capacity to match model DC unit. COOLING WATER removes beat from absorber aarf condenser SERVEL 25-TON WATER CHIL LER (Steam Operated) Completely "packaged." Requires only simple plumbing connections plus 115volt line to operate controls. Steam con trols built in. Provides chilled water at minimum temperature of 40 F for wide range of applications--from industrial processing to comfort air conditioning. Chilled water circuit operates under nor mal pump pressure--is hot a part of absorption vacuum system. 1262 -W 'M solution of lithium bromide and water HEAT EXCHANGER warm solution from generator Is cooled by solution from absorber nf t K*ese ?rv,e* ^lr Conditioners an absorption refrigeration unit takes the place `Si"?1 electric compressor refrigeration system. It is a compact factory-sealed tho that .is actuated by.heat. Gas-operated, self-contained steam generators supply `'tie neat in JUit and DC models. . The 25-ton Water Chiller does not incorporate its own steam generator. In all models, water is the refrigerant and lithium bromide the absorbent. mHtir.e'Ie<" Fa<it?.r? Warranty is provided for all models--one year on the complete mcLiQ *iouri Wkonal yeare on the absorption refrigeration unit. In DE and DC eis, tne steam generator and heating coil are also covered for five years. 1263 j Automatic Heating. Evaporative Alt Conditioning Air Cooling and Blowers Utility Fan Corporation A Division of Utility Appliance Corp. 911 East 59th Street, Los Angeles 1, Calif. Cable Address: UTILIFAN, Los Angeles Manufacturers of heavy and standard duty blowers for heating, air conditioning and ventilating installations. Producers of blowers and blower parts for original equipment manufacturers. Built, tested and rated in accordance with ASHVE and NAFM codes. Sizes 6 inches to 60 inches. Write for catalog data. Heavy duty blower. Type "B" backward curved DWDI. HEAVY DOTY BLOWERS, Double Inlet Double Width and Single Inlet Single Width, Forward and Backward Curved Wheels. Wheel diameters range in size from 12 inches to 60 inches. These blowers are of Class I construction, in any of ten drive arrangements and eight discharge positions. NEW ENCLOSED DRIVE BLOWERS, sizes 10 inches to 36 inches, with fully enclosed drive compartment. Ideal for roof installation. The ED blowers are of the forward curved slow speed type, built for ease of installation and a mini mum of maintenance. Enclosed Drive Blower UTILITY'S FAMOUS "FOUR WAY" BLOWERS, designed by Utility, avail able in single width single inlet as well as double width double inlet. A simple change in bearing position makes it pos sible to obtain discharges in any of four directions. An economy unit for medium duty use, rigidly constructed and fac tory guaranteed. . SHent Direct Drive Blower NEW SILENT DIRECT DRIVE BLOWER. By using vibration-absorbing Neoprene in the basic hub design, the blower wheel is isolated from the motor shaft. This unique development pro duces a very quiet blower. The direct drive blower is available in three wheel sizes providing a varied range of capaci ties, depending on motor horsepower selected. 1264 m v - ... . Packaged Air Conditioners, Air Conditioning * Unit Heaters, Convectors, Radiators Union Asbestos & Rubber Company 332 S. Michigan Ave., Chicago 4, Illinois HEATING AND COOLING PRODUCTS The UNARCO ROYAL-AIRE (CU series) provides full comfort cooling range. Refrigerant flow through vertical coil is thermostatically controlled, utiliz ing UNARCO "pump-down" control system. Oversize vari-flow blower and oversize condenser, plus large "fin area" cooling coil, insure full-rated capacity. The UNARCO CEILING SUS PENDED UNIT (CS series) is a com pletely self-contained unit available in 2-, 3-, 5- and 7}<j-ton capacities. The UNARCO COMPLETE AIR CONDITIONING PACKAGE for stores and industrial plants (series AEC) is available in capacities from 5 to 60 tons. It is of single cabinet construction, with packaged condensing unit, blower coil section and evaporative condenser. UNARCO HORIZONTAL AND DOWNBLOW UNIT HEATERS (down- blow shown) include die-formed cabinets of not less than 20 gauge steel. Casings are phosphatized and finished in ham mer enamel, baked on for permanence. UNARCO WALL RADIATION. UNARCO CONVECTOR RADIA Covers are of 14, 16 and 18 gauge steel in TORS. Cabinets are phosphatized, fin sloping top, flat top and expanded metal ished in prime gray paint, and con styles. Available in 2 ft to 10 ft lengths structed of furniture quality steel. Also in 6 in. increments. Elements range from available in other models. Elements con 2 ft to 12 ft in 6 in. increments. Acces sist of cast brass headers, aluminum fins, sories available. copper tubes and 20 gauge side plates. 1265 Air Conditioning Automatic Heating Air Control American Foundry and Furnace Co./ General Offices: Bloomington, Illinois, P. O. Box 904 Sales Offices Atlanta 6, Ga. Boston, Mass. Buffalo 2, N. Y. Chicago, 111. (Glenview) Cincinnati 2,0. Cleveland 7,0. Boynton Cole Foulds Associates Arnold R. Kamman Co. D. P. Gladish Co. Walter A. Juergens # Am. Warming A Ventilating 1)28 Moines M, Ia. C. H. McGuiness Co. Elmira, N. Y. Am. Warming & Ventilating Co. Indianapolis 18,Ind. Elliott-Williams Co. KansasCitt11,Mo. John H. Kitchen & Co. Los Angeles 7, Harry F. Haldeman, Inc. Calif. Milwaukee 2, Am. Foundry <fc Furnace Nashville 6, Tenn. New Obleanb 15, La. . New York 68, N, Y. James H. Winters Co. R. K. Rothrock The Demuth Co. Philadelphia 2, Pa. Richmond 25, Va. Rochesteb 7, N. Y. St. Louis 17, Mo. Salt Lake City 1, Utah . San Antonio 6, Tex. San Lbandbo, Calif. Seattle 9, Wash. Syracuse 3, N. Y. Toledo 4, 0. Toronto, Canada Am. Heating A Ventilating Co. Richmond Air Equipment Co., Inc. Wm. H. Stoll Co. M. F. Carlock Williams, Gritton A Wilde Langhammer-Rummel Co. Aladdin Heating Corp. McPherson Furnace A Equip ment Co. F. W. Chadwick Co., Ino. Am. Wanning A Ventilating Co. MfaliftAl Stuart Co., Ltd. HEAVY DUTY FORCED WARM AIR HEATERS Heavy Cast Iron Construction--Inte grally Cast Fins. SUpped Knocked Down--Assemble In side Building. Tight Bolted Joints. Long Fire Travel--Ample Heating Sur face. Design Relieves Internal Stresses When Expanding. Horizontal Flues With Access Doors Facilitate Cleaning. CENTRAL TYPE "June-Aire" conditioning for schools, public and commercial buildings. Beats and ventilates with same system. Out side air and recirculated air used in any desired proportion. Air filters--Germ killing means. Atomist humidifier-- Humidistat control. Individual room temperature control with constant venti lation. Time clock program control of plant. Oil, Gas, Coal (hand or stoker fired) and convertible models. Capacity for buildings of any size. Warm floors (air tubes in slab) combined with window sill air supply, optional application method. Summer cooling by adding com pressor and coil. UNIT HEATER TYPE "Superfin" (Cast Iron*) and "Dyne-Aire" (Stainless Steel) for fac tories, industrial buildings, warehouses, etc. Complete heating plant in one pack age. Use for heating and ventilating or tempering outside air supply. Main blower, burner, and induced draft fan driven by separate motors. 'Cast iron units with built-in refractories recom mended for heavy oil. RESIDENTIAL UNITS: "June-Aire" cast iron--oil and gas fired. Complete information available at near est sales office or factory. 1266 American Foundry and Furnace Co, Air Conditioning AMS5iH"tin* "AFFCO" VENTILATING SPECIALTIES _____ vj,vw<u*wvu wvmyiisc A A'lUl JU1U6 UI rrCSH Air Julw...v> vru^tuc TT all justable Louvers, Dampers (Single and Multiple Blade--Parallel and Opposed Blade), Automatic Fire Dampers, Fan Outlet Louvers, Fan Pent Houses, Low Profile Roof Ventilators, Et Cetera. Used In Public, Commercial, Factory, and Industrial Buildings Including Power Plants. Inquiries Invited On Standard Or Special Con structions In Any Size, Any Metal, Any Quantity. S-454-F COMBINATION STORMPROOF LOUVER AND DAMPER Frame: 20 gauge galvanized steel. Sta tionary Stormproof Louvers: 26 gauge galvanized riveted to frame--apron ex tends over sill. Insect Screen: 16 mesh, rust-proofed, in removable "U" type frame, back of sta tionary louvers. Louver Control Damper: 16 gauge gal vanized steel multiple blades in 2 x i x J galvanized steel channel .frame. Manual or motor operation means available. Wall Thickness: 8 in. minimum. F-12 LOUVER DAMPER Frame: 2 x x i steel channel, 2 x i bar iron optional, heavier frames for large sizeB. Blades: 16 gauge steel. Bearings: Oilite, ball, or brass trunnions. Position Installed: Vertical or horizon tal. Maximum Blade Length: 48 in. Longer dampers are made in sections with all blades arranged to operate in unison. Motor Mounting Brackets: Internal or external--at extra charge. Motors and Connecting Linkage: By others, or from us at extra charge. Finish: Prime coat--galvanized steel optional. "LO-VENT" ROOF VENTILATOR Designed to hug roof and be inconspicu ous. For buildings with pressurizing ventilating systems--propeller fans may be added. Body: galvanized steel--cover binged. Back Pressure Dampers: aluminum blade. Bird Screen: over exhaust openings on four sides. Louver Control Damper: optional for in side curb. Vent Grille: By others if desired--may be placed under curb. Sizes: 8 to 42 in. square standard-- special sizes optional. 1267 .. j- .... . Industrial Heating; Air Conditioning Direct-Fired Heaters Campbell Heating Co. 3121 Dean, Des Moines 17, Iowa WINTER-CHASER AIR CONDITIONING SYSTEMS EASTERN REPRESENTATIVE: Neil Adams, 22 Jefferson St, Lambertville, N. J- Tel. No. 2-0655 HORIZONTAL UNIT HEATER Oil & Gas HI-BOY UNIT HEATER Oil & Got HEAVY DUTY HEATERS For Large Churches, Schools, (Dp to 3,000,000 Btu) Commercial & Industrial Buildings LO-BOY Oil * Gat Fired 75 F Heating Guarantee If the heating plant design is approved by our Engineering Department or de signed by a Registered Engineer and the heater and blower are furnished by us and are in accordance with our ratings, we will guarantee the heating of all rooms to which warm air is delivered to 75 F in the coldest and windiest weather. 10 Year Durability Guarantee All Campbell Heaters installed as de scribed above are guaranteed for 10 years against repairs from any cause, parts to be furnished free f.o.b. the factory.; Motor, humidifier, automatic burner and controls and other parts not manu factured by us carry their manufactur ers' guarantee of one year against de fects. Engineering Service Our Engineering Department will be glad to help the consulting engineer or architect solve any heating, ventilating or air conditioning problems or help with layouts and specifications for any large building. Our Engineering Department consists of trained graduate engineers backed by 60 years of practical experi ence. 1268 8000 UNIT HEATER For all Fucle Campbell Heating Co, Air Conditioning Di?e"S3hedHeSter. SPECIFICATIONS and DIMENSIONS HEATER Unit No. Btu Output Capacity BTU/ Hr. f Heating Surface Sq Ft per Sq Ft Heat ing Sur face N orm al cfm 135 D ischg, Temp. BLOWER* MAX. FUEL RATES DIMENSIONS Assumed External Static In. Water Motor Oil hp gpb 1000 Btu Gas cfh LP Gas gph Coal Lbs Per H in. Hr. L in. Win. Hi Boy & Horizontal Unit Heater--Oil & Gas for Churches, Schools, Commerical & Industrial Buildings HU200 HU250 200,000 250,000 83 2410 2600 83 3000 3300 H V* 1.8 250 2.5 ?4 2.2 312 3.1 66 66 HU300 . HU350 HU400 HU500 300,000 119 2520 4000 350,000 119 2930 4600 400,000 180 2220 5300 500,000 180 2780 6600 h h H H 2.7 375 3.8 1 3.1 437 4.4 l 3.6 500 5.0 m 4.5 625 6.3 72 72 84 84 HU600 i 600,000 244 2460 8000 HU700 700,000 244 2870 9200 h M 2 5.4 750 7.5 2 6.3 875 8.8 99 99 HU850 850,000 333 2540 11000 HU1000 1,000,000 333 3000- L-13000 H -H 3 .3 7.6 1060 10.6 9.0 1250 12.5 108 108 48 48 54 54 60 60 78 78 106 106 23 23 29 29 84 34 40 40 48 48 Lo Boy Oil & Gas Fired for Large Residences, Small Churches, Schools, etc. H200 H250 H300 200,000 100 2000 2600 250,000 125 2000 3300 300,000 136 2200 4000 Vt H yi h 1.8 250 2.5 M 2.2 312 3.1 M 2.7 375 3.8 52 41 57 85 41 61 87 50 H350 H4Q0 H50Q 350,000 152 2300 4600 400,000 167 2400 5300 500,000 200 2500 6600 H H a 1 3.1 437 4.4 3.6 500 5.0 W 4.5 625 6.3 61 87 50 61 87 50 74 91 60 H600 H700 600,000 240 2500 8000 700,000 280 2500 9200 a H 2 5.4 750 7.5 2 6.3 875 8.8 76 97 72 104 60 80 8000 Series Oil, Gas, Stoker or Hand Fired For Large Schools, Churches, etc. 8075 8100 8125 840,000 280 3000 11,000 960,000 320 3000 12,500 1,080,000 360 3000 14,100 H H H 3 7.5 1050 10.5 100 3 8.6 1200 12.0 114 3 . 9.7 1350 13.5 129 93 134 95 153 97 171 76 76 76 8150 8175 8200 1,320,000 440 3000 17.300 1,440,000 480 3000 18.900 1,800,000 600 3000 23,600 H H 5 11.8 1650 16.5 157 98 195 5 12.9 1800 18,0 171 99 202 5 16.1 2250 22.5 214 120 216 76 76 94 8250 8300 8350 2,250.000 750 2,700,000 900 3,150,000 1050 3000 29,500 3000 35,400 3000 41,300 H H H 7H 20.1 7W 24.1 10 26.1 2810 3380 3940 28.0 33.8 39.4 268 320 375 120 243 132 251 150 251 94 104 114 8000 Series Unit Heater--Oil, Gas, Stoker or Hand Fired--For Large Industrial Buildings U8125 1,080,000 360 3000 14,100 Consult 2-1 '9.7 1350 13.5 129 97 105 76 our U8150 1,320,000 440 3000 17,300 Engineers 2-1H 11.8 1650 16.5 157 98 118 76 U8175 1,440,000 480 3000 18,900 if 2-m 12.9 1800 18.0 171 99 130 76 U8200 1,800,000 600 3000 23,600 duct 2-2 16.1 2250 22.5 214 120 137 94 system U8250 2,250,000 750 3000 29.500 is to 2-3 20.1 2800 28.0 268 120 157 94 U8300 2,700,000 900 3000 35,400 be 2-3 24.1 3380 33.8 320 132 157 104 U8350 3,150,000 1050 3000 41,300 used. 2-5 26.1 3940 39.4 375 150 157 144 Type A unite include Special Oil or Gaa Heater, Casing, Blower, Motor, Drive, Filters, Humidifier, and Blower Control but less Burner, Controls and Built-in Combustion Chamber. Type B units include same as Type A plus Oil or Gas Burner and built-in Combustion Chamber and Stand ard Controls. t Based on 80% thermal efficiency for oil and gas and 70% for coal. Add 10% to 35% over calculated heat loss for pick-up load and 10% to 15% for duct radiation losses. The higher figure is preferable for best operat ing economy and life of the equipment. | For other air volumes and static pressures consult our Engineering Department. An induced draft blower can be furnished if a stack or chimney is not available. The gas passages of the heaters are adequate so an induced draft blower is not ordinarily needed. For Complete Specifications, See Sweet's Catalog Service 1269 Air Conditioning . SSSSgJSSSTM E. K. Campbell Company Manchester at 18th Street, Kansas City 26, Missouri Since 1910 Manufacturers of Heavy Duty Furnaces Unit capacities up to 8,000,000 Btu per hour District Offices: New York City, St. Louis, Mo., Denver, Colo., Kansas City, Mo. Representatives: Minneapolis, Minn., Salt Lake City, Utah, Memphis, Tbnn. "THERMIDAIRE" DESIGN 20 TYPE H-D FURNACE Standard equipment for engineered application--available for installation in any position in capacities from 400,000 to 3,000,000 Btu per hour output--re quires separate blower equipment-- highly compact heavy duty furnace of high operating-efficiency up to 84 per cent--available in any fuel except coal --normally shipped assembled. Avail able for special air volumes if required. "Tkermidaire" Design 10 "THERMIDAIRE" DESIGN 30 TYPE H-D FURNACE Standard equipment, industrial type direct fired heater-- available from 400,000 to 2,000,000 Btu per hour output-- available in vertical, horizontal and inverted models--provides maximum compactness--available for single or multiple unit installations--equipped with burner, induced draft fan, and controls mounted and wired at the factory. ` `Tkermidaire'' Design 30 "THERMIDAIRE" DESIGN 10 TYPE H-D FURNACE Custom equipment for engineered appli cations--units from 400,000 to 8,000,000 Btu per hour output--any required ductoutlet arrangement--equipment com ponent arrangements extremely flexible --balanced job design, blower and fur nace sized separately--available in any fuel, oil fired model illustrated--large air volumes at low temp, rises up to 84 per cent operating efficiencies--nor mally shipped K-D. "Tkermidaire" Design. 10 "THERMIDAIRE" TYPE H-D FURNACES are all heavy-duty high-quality equip ment--extra heavy, welded steel construction--induced draft fan on all models-- baked enamel exterior finish--low internal resistance of flue gases--low static pres sure-drop across equipment--permanently smoke and gas tight--true counterflow heat transfer--operating efficiencies up to 84 per cent. Outstanding for schools, churches, auditoriums, factories, hangars, warehouses, etc. For further information ................................................................... E. K. CAMPBELL COMPANY Kansas City 26, Missouri 1270 Air Conditioning Heam?ired Chicago Steel Furnace Co. 9326 S. Anthony Ave., Chicago 17, 111. Manufacturers of Heating & Cooling Products DIRECT-FIRED SPACE HEATERS OIL-GAS OR COMBINATION FIRING ____ ____ __ pivviuc uuiiorm neat at low cost, eliminating the need for boiler rooms, costly chimneys or extensive duct work. All CSF equipment is constructed for durability, utilizing heavy gauge steel heat exchangers, high temperature refractories, and heavy duty fans. All models supplied with approved firing equipment. All heat exchangers are war ranted for ten years. There is a CSF model designed to meet any application, requiring either light oil,*heavy oil, or gas. Serte* "A" Floor Model PERFORMANCE DATA MODEL "A" Model No. A-560 A-700 A-S40 . A-980 A-1260 A-1610 A-1960 A-2240 A-2520 BTU Output 448.000 560,000 672,000 784,000 1,008.000 1,288.000 1,568.000 1,792,000 2,016,000 Firing Rate'-- gph Air De livery CFM @ W SP 4.0 5.0 6.0 7.0 9.0 11.5 14.0 16.0 18.0 5,850 7,300 8,750 10,250 13,100 16,700 20,500 23,500 26,500 HP Motor iyi 2 2 5 5 7H 7# 10 Stack 18* PERFORMANCE DATA MODEL "5" Com mercial BTUHR Output CFM at W SP Stack GPH S-210 S-280 , S-350 Industrial 168,000 2,200 224,00C 2,900 280,000 3,600 8 1.5 9 2.00 9 2.50 --" ' S-490 392,000 4,900 S-560 448,000 5,600 S-700 560,000 6,600 S-1050 840,000 9,600 S-1260 1 [,008,000 15,400 S-1610 1 1,288,000 18,000 S-1960 | 1,568,000 22,000 10 10 12 12 14 14 16 4.00 5.00 9.00 11.50 14.00 Weight 870 2,160 1,450 2,100 2,650 2,850 4,200 5,300 5,600 6,100 PERFORMANCE DATA MODEL "H" & "C" Model No. C-2101 H-210/ C-2801 H-280; C-3501 H-350; C-420\ H-420; C-4901 H-490/ BTU Output Firing |Air De Rate-- livery GPH CFM @ W SP HP Motor 168,000 1.5 2,200 a 224,000 2.0 2,900 a 280,000 330,000 2.5 3.0 3,650 4,400 H 1 392,000 3.5 5,100 Stack 8* 9' 9' 10' 10' 1271 Air Conditioning DiJ^iteedeHea?ers Dravo Corp, Air Conditioning Industrial|Heating; Direct-Fired Heaters Dravo Corporation Machinery Division ' Dravo Building, Fifth & Liberty Avenues, Pittsburgh 22,;Penna. Atlanta, Baltimore, Boston, Chicago, Cincinnati, Cleveland, Detroit, Houston, Indianapolis, New York,^Philadelphia, Pittsburgh, San Francisco, St. Louis Sales Representatives in Principal Cities DRAVO Gnmteif6r SPACE HEATERS DRAVO .Pawflo SPACE HEATERS 200,000 to 250,000 Btu/hr output POWER AND FUEL--Heater operates on 220 volt 60 cycle current. 220 or low voltage operation can be supplied if de sired. Unit can be equipped with a selfcontained gun-type oil or gas burner de pending upon the fuel available. FAST TRANSFER OF HEAT--Stain !i 400,000 to 2,000,000 Btu/hr output less steel combustion chamber allows faster heat transfer from fuel to air and ECONOMICAL--Low initial cost-- guarantees longer heater life and sus 30-70 percent less than standard wet- tained efficiency. Equipped with UL u type equipment to install. 80-85 per approved gun-type oil burner or A.G.A. cent efficient at bonnet . . . burns gas approved bas burner. t\ or oil, readily convertible from one to the other. FLOATING COMBUSTION CHAM BER--Supporting straps hold stainless EASY INSTALLATION--Just hook up fuel, electric and exhaust connections --no ductwork required. 7 % f steel chamber in place for inverted or horizontal mounting. One end floats freely relieving stresses and strains due to normal expansion of chamber. HEAT ANYDIRECTION--Warms areas STAINLESS STEEL COMBUSTION up to 3600 sq ft. Directional nozzle can CHAMBER--Rugged mill-type con be rotated 360 deg heating any desired u struction . . . top quality engineering. location, high velocity discharge assures S|j Exhaust whirl-cooled through two sets of economizer tubes. good distribution up to 90 ft from the unit without the use of ductwork. SAFETY-TESTED--Approved by A.G.A. and listed by underwriter's Laboratories, Inc. Dravo Safety Con trol Circuit is accepted by Factory Mutual Engineering Division and Factory Insurance Association. *i*~ .>Vv- This new Dravo heater is ideal for garages, service stations, construction offices, recreation centers, agriculture buildings, warehouses, stores, offices and showrooms. The heater fan can be used for summer ventilation. Heaters can be adapted to air conditioning systems. PARAFLO 10-YEAR GUARANTEE--All stand ard model Counterflo heaters carry a fully bonded 10-year guarantee on all parts in direct contact with flame or flue gases. -&? Dravo Counterflo Space Heaters in addition to comfort heating are easily adapted to heat curing and process dry- ing, tempering of replacement air and summertime ventilation. Dravo Counterfio Space! Heaters can also be tied m with air conditioning systems, COUNTERFLO Htr. No. Output Btu/hr CFM at 70F 20 ' 200,000 25 250,000 2200 2700 Temp. Rise 84 84 Efficiency Fan Mtr. hp 80% 80% Yt H Approx. Nozzles Shpg. Wt. 2 785 2 795 Dimensions L 4'2" 4'2* W 2'5' 2'5* H 7'10* 7'10# DRAVO SUSPENDED TYPE UNIT HEATERS 68,000 to 180,000 Btu/hr output COMPLETE RANGE OF SIZES-- Heaters are available in a wide range of capacities in various model sizes with outputs from 68,000 to 180,000 Btu/hr. Htr. No. Output Btu/hr CFM Temp. Effi at 70F Rise ciency Fan Approx. Mtr, Nozzles Shpg. hp Wt. Dimensic ns L w H* Ii>i 40 400,000 4500 50 500^000 5500 75 750,000 8500 100 1,000,000 11,000 125 1,250,000 14,000 150 1,500,000 17,000 175 1,750,000 19,000 200 2,000,000 22j000 82 84 82 Si 83 82 85 84 80% 80% 80% 80% 80% 80% 80% 80% m 2 3 5 7H 10 10 15 3 3 4 4 4 4 4 4 1400 1500 2500 2600 3400 3600 4200 4400 5'3" 27" 8'3" 5'3" 27" 77' 37" lO'O" 77" 37" 10'0" 9'2" 4'3" 1I'2" 9'2" 4'3" 11 9'9" 4'9" 12'10 9'9" 4'9" 12'10 1272 FLEXIBILITY OF GAS FUELS-- Heaters can operate on natural, manu factured, mixed, butane, sewer, or pro pane gas and liquified petroleum. LOW COST HEATING--These heat ers are ideal for economically heating small unit areas in commercial or indus trial buildings such as garages, stores, machine shops, warehouses, amusement centers and other similar type buildings. 1273 Air Conditioning Industrial Heating Direct Fired Heaters Johnson Heater Corp. 1 Winnisimmet St. Chelsea, Mass. DESIGNERS MANUFACTURERS 15 Models, single heater capacities to 5,000,000 Btu fired by light or heavy oil, gas or combination gas and oil burner. Multiple criss-cross air tube heating surfaces over the combustion chamber. DIRECT FIRED "AIR ROTATION" HEATING UNITS (PATENTS PENDING) FOR INDUSTRIAL AND COMMERCIAL APPLICATIONS LOW INITIAL INSTALLATION--FUEL AND MAINTENANCE COST Simplified heating for large open buildings such as Warehouses--Machine Shops-- Garages--Airplane Hangars--Fabricating plants, etc. Our exclusive method of "air rotation" heating (Patents Pending) uniformly blankets with warm air all areas of an open building. All duct work, piping spot ting, and throwing of the heated air is eliminated. One Johnson Heater can success fully heat in excess of 1,500,000 cubic feet of building space. TUBULAR DESIGN FULLY AUTOMATIC HIGH EFFICIENCY CONSERVATIVELY RATED PRACTICALLY SELF CLEANING ALL STANDARD PARTS DIMENSIONAL BTU MODEL OUTPUT AT AVER'G CFM PLENUM MAX. BTU INPUT APPROX. SHIP PING WEIGHT A B SMOKE- C GH I PIPE DIA JA-3 JA-4 JA-5 JA-6 JA-7 JA-8 JA-10 JA-12 JA-15 JA-20 JA-25 JA-30 JA-35 JA-40 JA-50 330,000 425,000 550,000 650,000 750,000 850,000 1,000.000 1,250,000 1,500,000 2,000,000 2,500,000 3,000,000 3,500,000 4,000,000 5,000,000 4600 , 6000 7800 9200 10.500 12,000 14,000 17,500 21,000 28,000 36,000 42.000 49,000 55,000 68,000 420,000 560,000 700,000 815,000 950,000 1,080,000 1,260,000 1.590.000 1,900,000 2,500,000 3,150,000 3,750,000 4,375,000 5,000,000 6,250,000 1850 2300 3100 3500 4000 4500 5200 6100 7100 10,750 12,500 14,000 16,500 21,000 24,500 3'6' 3'8' 4'2' 4'8# 470* 5'O' 5'8' 6'(T 6'6' 7'6' 87' 9'6' 9'10* 107' li'0' 4'3' 5'4' 5'8' 5'8' 67' e'lo' 7'6' 87* 8'8' 9'9' 071' mo' 137' 13'6' 1470' 6'3' VP 7'S' sir 8'4' 8'8* 9'6' 10'3' in' BV 13'5' 14'4' 157' 16'4'. 17'8' 2'5' 270' 3'3' 3'3' 37' 37' 371' 4'5' 4'9' 57' 5'5' 5'5' s'kt 6'8' Q'80 2'3' 27' 3'0* 3'O' 3'<r 3'3' 3'3' 37* 47' 4ir 4'6' 4'6' sir 5'5' 5'5' 3ir 3'5' rvr 370* 47' 4'6' 4'6' SIT 5'5' 5'\o* 67' 67' e's* 7'6' 7'6' 9' 10* 12' 12' 12' 14' 14' 16' 16' 18' 2(T 22' 24' 24' 26' The Johnson Heater Corp. reserves the right to change any dimensions contained herein without notice. Models JA-3 thru JA-15 can be supplied with blower enclosures with or without filters. All models of Johnson Heaters are designed for use with a conventional duct system where required. 1274 Air Conditioning Industrial Heating Direct Fired Heaters Johnson Heater Corp. 1 Winnisimmet St. Chelsea, Mass. DESIGNERS MANUFACTURERS 9 Models, single heater capacities to 500,000 Btu. Fired by light fuel oil or gas. Stock sizes. Practically self cleaning multiple air tube heating surfaces. SUSPENDED T MULTI-TUBE DIRECT FIRED HEATERS Low cost heating for Service Stations--Garages--Warehouses--Machine Shops Residences and other types of commercial'and domestic installations. Larger single heater models up to 1,000,000 Btu. . Heaters fired by oil, gas or combination burners. COMPLETELY ASSEMBLED NO FLOOR SPACE REQUIRED FULLY AUTOMATIC ALL STANDARD PARTS CONSERVATIVELY RATED DIMENSIONAL DATA BTU MODEL OUTPUT AT AVER'G CFM PLENUM JAS-1 JAS-iis JAS-1.5 JAfa.ZH. JAS-3 JAS-ju> JAb-4 JAS-5 133,000 152,000 170.000 220,000 280,000 335,000 390,000 450,000 500,000 1800 2000 2400 3000 3600 4300 5000 6000 6500 MAX. BTU INPUT 175,000 190,000 210,000 280,000 350,000 420,000 490,000 560,000 630,000 APPROX SHIP PING WEIGHT 800 ' 850 925 1025 1050 1450 1550 2000 2025 SMOKE PIPE DIA 8 8 9 9 9 10 10 12 12 A 28 28 31 36 36 46 46 48 48 B c E FGH P 85 26 23 48 12 25 20x20 85 26 23 48 12 25 20x20 88 28 25 48 15 25 23x23 96 32 29 48 23 25 26x26 96 32 29 48 23 25 26x26 109 36 33 60 19 30 30x30 109 36 33 60 19 30 30x30 115 43 40 60 25 30 38x38 115 43 40 60 25 30 38x38 The Johnson Hester Corp. reserves the right to change any dimensions herein without notice. SMALLER JOHNSON FLOOR MODEL HEATERS Five models of horizontal extended casing units: 110,000-138,000-165,000-210,000 275,000 Btu. Five models of vertical Hi-Boy units: 110,000-138,000-165,000-210,000-275,000 Btu. 1275 Air Conditioning Industrial Heating; Direct* Fired Heaters, Unit Heaters Suspension Units Jackson & Church Furnace Division Saginaw, Michigan "Work well done since '81" The school building heating system shown incorporates all the advantages of per imeter heating . . . plus seven complete air changes per hour, constant blower operation, and individual room temperature control. A J-C furnace provides both heat and ventilation. A blending of desired proportions of fresh outside air and room air is heated to proper temperature and delivered through floor ducts in tunnels used for wiring and piping. Air may be introduced through floor registers, elevated registers or book-shelf-register combinations. High inside wall returns are used. SUSPENSION FURNACES--the line of horizontal units. Available in wide range, 80,000 to 1,000,000 Btu output. Oil and gas fired . . . with UL and A.G.A. approval. POWERAIRE FURNACES--for most commercial and large residential jobs. Air conditioning units can be added to system. Outputs from 152,000 to 320,000 Btu. Oil and gas fired. POWERATED FURNACES--for indus trial heating and industrial ventilating where outside air is introduced. Outputs from 380,000 to 3,800,000 Btu. Oil, gas and coal fired. J-C Direct-fired units now available with outputs from 400,000 to 2,000,000 Btu/hr. 1276 Air Conditioning ............... -...........------------- ------ Heat*. ...... ...................... Lee Corporation Foot of Madison Street, P. O. Box 1801 Wilmington, Delaware Baltimobe, Md. New Yobx, N. Y. . Chicago, III. Representatives in all Principal Cities Manufacturers and Designers of Complete Line of Industrial and Commercial Warm ' . Air Heaters MODEL HD--750,000 to 2,000,000 Btu MODEL TSE--2,000,000 to 8,000,000 Btu MODEL VTH--2,000,000 to 6,000,000 Btu MODEL BST--2,000,000 to 10,000,000 Btu LEE HEAVY DUTY HEATERS LEE HEATERS have been in continuous operation since 1918. Lee Heater instal lations have been made in most of the States of the United States, in Canada, Alaska, Yukon Territory, Northwest Territory, Labrador, Iceland, Norway, Mexico ahd South America. Firing Equipment manufactured spe cially for us by leading Companies with International service organization. There is a Service man near you if and when you require assistance. In addi tion Lee maintains a competent field serving staff. Replacement and Spare Parts Service is maintained. Most items are carried in stock. Types of Fuel Light Oil ( S 3 or Lighter) Medium Oil ( H 5 or Lighter) Heavy Oil ( g 6 or Lighter) Gas (Natural, Manufactured Oven.) Combination Light Oil & Gas Combination Heavy Oil & Gas Propane VERSATILE Mount in any Position Coke Floor Mounted Horizontally Mounted (& Suspended) Vertically Mounted (& Suspended) Use with Ducts lor Central Heating System Use without Ducts as Self Contained Heating System Output Capacity (Btu per hr) Total Heating Surface in Sq Ft Cu Ft of Air per Min. (Approx.)* Air Fan Motor h.p. Induced Draft Fan Motor h.p. External Static Pressure (Std.) Maximum External Static Pressure Avail able for Duct Work** Temperature Rise-Degrees F. Fuel Consumption*** Gas (cu ft per hr) Oil (gal per hr) Shipping Weight-lbs Refractory Comb. Chamber Stainless Steel Comb. Chamber Heater Length Heater Width Heater Height Number of Outlets Number of Blowing Fans HD-750 750,000 175 8,500 5 H H' r 82 940 6.5 5000 3100 6'-4H# 4'0* 9'11* 3 2 HD-1000 HD-1250 HD-1500 HD-1750 HD-2000 1,000,000 1,250,000 1,500.000 1,7*1,000 2,000,000 192 11,000 218 14,000 17,000 20,000 363 22,000 5 H W 1' 7H H H' \* m H w i' H M' H' 15 K W H' 80 83 82 81" 84 1250 8.6 1560 10.8 1880 13.0 2190 15.0 2500 17.2 5300 3400 v-w 4'0* 9'11# 4 2 5800 3800 8'3' 4'0# 9'ir 4 3 7000 4700 ll'-3%' 4 2 8600 6300 8'-4H' 4'4* U'll* 4 2 9400 7000 9'-4H* 4'4* ll'll' 4 2 * Based on Standard Air at 70 F Free Delivery ** Requires large Air Fan Motor *** Fuel consumption based on 1000 Btu per cu. ft of Gas, 145,000 Btu per gal of Oil and on 80 per cent efficiency for the heater. 1277 Air Conditioning D^eo^eduStl Mammoth Furnace Company 509 Vandalia Street St. Paul, Minnesota Commercial-CLtfte, ;s jr- s ig Strong--built for rugged service and safe shipment. Quiet Fan Operation--a rigid tubular fan shaft supported by two self aligning bearings eliminates shaft and bearing problems. Retractable Burner Tray--allows com plete service to burner. Permits removal from unit with no disassembly and mini mum handling. Central Control Cabinet--provides con trols, fusing and wiring in an accessible dust-tight enclosure. Direct Driven Induced Draft--troublefree, vortex cooled motor shaft connec tion to blower wheel. No belts and addi tional bearings to service. Variety Of Controls And Power Supplies --units may be "off-on" thermostat con trolled, hi-low fire or modulated control. Wiring and controls can be provided for all power supplies. Integrated Burner Applications--burners by reputable manufacturers are tailored to produce the most effective flame con figuration for the heater design. Combustion Safety And Draft Controls-- MH-Electronic flame: control system, pre-ignition draft purge timing and draft sensing give a high degree of operation safety. Series "F" Floor mount with discharge heads for industrial plants, foundries, etc. . Series "H" Horizontally suspended unit for use where floor space is unavailable. Series "FD" For duct distribution. For churches, schools, auditoriums, etc. : Series "U" Suspended inverted unit for make-up air applications in plants, foundries, etc. SPECIFICATIONS A p p ro x ** Fan rpra L e n g th f W idth P le n u m O pening Approx. S h ip p in g W eight Model Btu Output Sq ft t OhH XcoS Htg. Sur face 8*8 E.D.T.* o Blower Motor DIDW hp Max Firing Rate Oil Gas gph cfh ato `5 s Mech. Ex haust Dis charge 300 300,000 135.3 4,000 I4'-twin H 575 3.0 375 60* 80' 32' 18x60 8'dia. 1,590 400 400,000 135.3 5,500 14'-twin 1 640 4.0 500 60' 80* 32' 18x60 8' dia. 1,690 550 550,000 183.6 7,000 14'-triple 1 tt 750 5.0 688 80' 80' 32' 18x80 8'dia. 1,950 700 700,000 183.6 8,700 14'-triple 2 820 7.0 875 80' 80* 32' 18x80 8' dia. 2,150 800 800,000 276.8 10,000 16'-triple 3 710 7.5 1,0041 80' 83' 48' 22x80 10* dia. 2,775 1000 1,000,000 276.8 13,000 16'-triple 5 790 9.5 1,25(J 80* 83' 48' 22x80 10' dia. 2,850 1250 1,250,000 431.0 16,000 l8'-triple 5 755 11.5 1,563 100' 96' 54' 26xlOC 10' dia. 3,850 1500 1,500,000 431.0 19,000 18'-triple m 830 14.0 1,875 100' 96' 54' 26xlOC lO'dia. 4,010 1750 1,750,000 574.1 23,000 21'-triple 7V4 680 16.5 2,183 120* 96' 60' 30xl2C 12' dia. 4,750 2000 2,000.000 574.1 26,000 21'-triple 10 740 18.5 2,500 120' 96' 60' 30x120 12* dia. 4,910 Equivalent Direct Transfer. Head Projection Not Included. Adjustable. t Burner Projections Not Included. tt Discharge .. 1278 sfl* fs t ' '*y*: fi |#= ;fv 8 15 V; 0-1 T Air Conditioning * Direct-Fired Heaters Arthur A. Olson & Company Canfield, Ohio Manufacturers of Direct Fired Heaters Hj A completely automatic direct-fired unit heater. Olson heaters operate on gas, oil, dual gas-oil or coal. These units may be hung, suspended horizontally or inverted. All heaters can be adapted to filtering, humidifying and air conditioning. Use of standard accessories and easy access to bearings and other vital parts simplify main tenance. Also special adaptions for make-up air, drying, high-temperature and process work. Austinetic Stabilized Stain less Steel Combustion Cham ber with floating design and a multiple battery of 10 gauge boiler tube economizer sec tion. Heavy Duty Fans and Shaft. Inlet Screens or Frame for Filter Box. Adjustable, Deflecting Out lets. Separate Induced Draft Fan. Bearings Outside Heater at End of Shaft. Engineering Data--Gas, Oil, or Dual Gas-Oil Heaters Heater Btu/Hr Model Output Number Capacity Cfm Blowing Fans A General Dimensions li C D No. Motor of Hp Blow Blow ing ing Stack Dia. E Fans Fans S-300 S-400 8-ouu S-600 J5-750 S-1000 S-izou S-1750 300,000 400,000 500,000 600,000 750,000 1,000,000 1,250,000 1,500.000 1,750,000 2,000,000 3,500 4,500 5,500 7,000 8,500 11,000 14,000 17,000 20,000 22,000 3'-0' 3'-0' 3'-O' 3'-0' 3/-8' 3'-8' 4'-4' 4'--1' 4'-J0' 4'-10' 3-3' 3'-3' 4'-7M' 4'-7)r 5'-ll' 5'-11' 7-G' 7'-G' 8'-6' S'-G' 7'-6' 7'-6' S'-O' 8'-0' 8'-4' 8'-4' 9-10' 9-10' l0'-9^ i0'-9' r-3' r-3' r-3' r-3' r-3' r-3' r-5' l'-5" r-5' r-5' 2-3' 2'-3' 2-3' 2/-3' 2-7' 2'-7' 2/-7' 2'-7' 2'-7' 2'-9' 1 2 2 2 2 2 2 2 7Ji 15 10' 12' Write for complete data on stoker fired units and large central systems. No. of Nossle Out- 5 1279 Air Conditioning National Heater Company "28 2180 Cleora Avenue St. Paul 4, Minnesota NATIONAL CHAMPION HEATERS 200,000 to 2,000,000 Btu Direct fired for oil, gas, or combination units Engineered for industry--space heating, tempering make np air, and drying iv. ft V.'.\ GUARANTEED 80 PER CENT OPER ATING EFFICIENCY -- in factories, foundries, warehouses, garages, hangars, terminals and many other installations. .* & --i-1 f.l SAVE ON OPERATION -- National Champion Heaters circulate warm air at working levels, keep roof heat loss at a minimum. Low initial cost--no boiler house or power piping required. Low operating cost--standby losses elimi nated, no licensed attendant needed! ''h vf: SAVE ON FUEL--National Champion Heaters burn fuel only when zone ther mostats call for heat. Burner shuts off when temperature is attained. No fuel wasted to overcome transmission losses. No wasteful recycling to maintain steam pressure or water temperature. . :4 MODEL H Available in ceiling sus pended, inverted and portftMe units SAVE ON MAINTENANCE--National Champion Heaters feature simplified burner and controls and easily acces sible clean-out plates--no problem to maintenance personnel. Spare parts are readily available. TESTED CONSTRUCTION -- Features SAVE ON INSTALLATION--National high chrome nickel stainless steel combus Champion Heaters save 30 per cent to tion chamber, in efficient teardrop design. 70 per cent over systems requiring ex Structure welded into rugged, one-piece pensive ductwork, piping, condensate steel unit with baked enamel exterior lines, traps, pumps, etc. Units, are finish. Engineered for dependable, en shipped completely wired, assembled during service. Underwriter's laboratories and name-tested at the factory to guaran listed. tee peak performance. 1280 vr _____________________________ Air Conditioning . National Heater Company 2180 Cleora Avenue St. Paul 4, Minnesota Efficient heat exchange, high velocity discharge develop truly economical space heating. . 1. When thermostat calls for heat, in duced draft blower starts first to purge combustion chamber and establish draft before burner is fired. 2. Main blowers--separate from induced draft blowers--start only when proper bonnet temperature is attained. 3. Cool air is drawn through louvered panels at floor level. 4. Air passes over National's stainless steel teardrop combustion chamber and then around multiple banks of econo mizer tubes. 5. After this full uniform heating, air discharges at high velocity from adjust able heads atop the heater. Cutaway view of the National Champion Model H shews air flow from floor intake to adjustable discharge heads. 6. Separate blower integral with burner, and separate induced draft blower, are independently adjustable for maximum combustion efficiency. RESULT: No "cold blasts" on start-up; proper, uniform heating of air; high velocity discharge keeps warmed air at working levels; minimum temperature differential between floor and roof. Underwriters' L oratories Listed ^Heater -- TD-25 TD-30 TD-40 TD-50 TD-70 TD-80 td-ioo TD-125 TD-150 TD-175 ____ TD-200 WRITE FOR DESCRIPTIVE BROCHURE! Btu^ Output 200,000 250.000 300.000 400.000 500.000 750.000 800.000 1,000,000 1.250.000 1.500.000 1.750.000 2.000.000 CFM at H in. S.P. HP Blower Motor 2.400 3,200 4,000 5.400 6,600 8,800 10,200 12,500 15,300 19,400 22,000 26,000 54 54 1 m 2 3 5 5 7H 7H 10 1281 Overall Dimensions Width 28 28 32 32 32 32 48 48 54 54 60 60 Length 52 52 60 60 80 80 SO 80 100 100 120 120 Height 66 66 81 81 81 81 81 81 98 98 98 98 Shipping Weight 950 1020 1400 1500 ' . '.750 1900 2400 2600 3200 3450 4150 4300 Industrial Heating Air Conditioning guctPuniaces J Unit Heaters Reznor Manufacturing Company 66 Union Street, Mercer, Pa. Gas Unit Heaters--nine sizes: 25,000 to 250,000 Btu; Console-Type Room Heaters-- 25, 50,65 and 75,000 Btu; Duct Furnaces--50,000 to several million Btu; Gas Horizon tal Furnaces--75,000, 100,000 and 125,000 Btu. Reznor Series DS Sectional Duct Furnaces 150,000 to Several Million Btu Sectional assembly simplifies installa tion. Capacities totaling 2,000,000 Btu and above can be installed in custom engineered heating systems from sec tions weighing no more than 315 pounds. Unlimited number of sizes in steps of 50,000 Btu from 150,000 to several million Btu. All assembled from four basic sections--150, 200, 250 and 300,000 Btu. Units are compact, highly efficient, lightweight heat exchangers, each with a full complement of combustion controls. For assembly with components for airmoving, cooling, cleaning and humidifi cation selected to meet the exact re quirements of each job. May also be used as booster units to supplement other warm air heating equipment. Designed for installation as an integral part of the ductwork, all sections are equipped for either suspended or base mounting. Because air flow through the heater may be in either direction, sec tions can always be turned to provide easy access to controls and burners. To provide for seasonal operation of less than the total capacity, each section is complete with controls and built-in draft diverter. The unit shown above is a 450,000 Btu duct furnace (one 150,000 and one 300,000 Btu section mounted side-by-side). Be cause sections can be mounted in a single bank or in a double bank, overall dimen sions depend on the manner of installa tion. All sections are 37 in. high and 24 in. deep. Width varies according to capacity. Gas and electrical controls are nor mally installed on the front of the heater, but can be relocated to the side if pre ferred. Controls include main and pilot shut-off valves, electric valve, pressure regulator, safety pilot and adjustable limit control. All controls supplied by leading manufacturers. All electrical components Underwriters' Laboratory ap proved. Aluminized steel is the standard heat exchanger material; stainless steel heat exchangers are also available. Built-in draft diverter is reversible so that flue connection may face in either direction. Flue collar on snap-out plate for easy adaption to vertical or hori zontal discharge. Section DS-150 DS-200 DS-300 Btu Input 150,000 200,000 250,000 300.000 Specifications--DS Duct Furnace Sections Btu Output 120,000 160,000 200,000 240,000 EDR 519 692 864 1038 Thrup ut-cfm Miniroumt M&ximumtt 1200 1600 2000 2400 1S00 2400 3000 3600 High 37' 37' 37' 37' Deep* 24' 24' 24' 24' Wide*' 21H* 27 3554* 40Ji' Weight 190 lbs 315 lbs 1 %rr total depth of multiple banks, add depths oflections, then add 11' <fsections will be metalled back-to-back, or aid enough space to allow for removal of burners if units are to be metalled front-to-fronl orfronl-to-back. For total width of mulliplesections, add widths ofsections. For total undth of duct on multiple sections suo- tract t\i" from total overall width, ' .. . Industrial Heating Air Condltonina Duet Furnaces Unit Heaters Reznor Manufacturing Company 66 Union Street, Mercer, Pa. Check your local phone directory for your neares.t Reznor distributor or district office Methods of Installation--DS Series Duct Furnaces This schematic diagram shows how Reznor Series DS. Duct Furnaces may he combined in the duct system with' other com ponents. All components .shown (except the blower or other air-impelling equipment) are optional, to be used only as re quired by the specific job to be done. It is recom mended that cooling and humidifying equipment be installed downstream Multiple-section single bank installation with common atr supply and distribution ducts. ,, Multiple-section, double-bank installation with com mon air supply and distribution ducts. Reznor Gas Unit Heaters Completely automatic heating for all commercial and in dustrial buildings ... as the basic system or to supplement other types of equipment. Eight sizes--25,000 to 200,000 Btu with choice of propeller fan or centrifugal blower plus 250,000 Btu twin-fan model. Aluminized steel heat exchangers. Cast iron universal burners. Built-in draft diverter. For complete details, dimensions and specifications write for Bulletin B-55-UH. Reznor Series D Duct Furnaces For residential and small commercial applications requiring a heat exchanger for use in a custom engineered system- Four sizes: 50, 75, 100 and 125,000 Btu. For installation with any combination of equipment for air moving, cooling, cleaning and humidification. Burner access and controls completely enclosed on same side of handsomely-styled cabinet. All models 22 in. wide by 23 in. high; depth varies with capacity. Complete with combustion controls and built-in draft diverter. For suspended or base mounting. Bulletin B-55-D. Direct Fired Air Conditioning Unit Heaters Division of PRAT-DANIEL CORPORATION Meadow Street South Norwalk, Conn. % :L. t"ivr *3 THERMOBLOC DIRECT-FIRED INDUSTRIAL HEATERS The Thermobloc heater is a direct-fired, self-contained heating unit- designed to provide high efficiencies for all commercial and industrial heating applications. The Thermobloc Heater is a product of a firm with over 30 years of experience in the industrial heating field. It represents up-to-date proven design and engineering principles to assure a minimum of installation and operating costs and dependable comfort conditions. Thermobloc Heaters are sold in 28 countries. They are available in a complete range of sizes from 100,000 Btu/hr to 2,250,000 Btu/hr output to cover any industrial or commercial application. , All heaters are factory assembled, tested, and shipped com plete--requiring only connection of fuel, power and vent for immediate operation in the field. Range of sizes available offers a versatile unit or a combination of units for any indus trial or commercial job regardless of size. They may be located directly in the area to be heated jor may be full ducted and placed where desirable. Units are available for all commercial fuels: oil--number two or four; gas; combination gas arid oil; combination gas and LP gas. PORTABLE THERMOBLOC HEATERS. Designed for temoprary or emergency beating in industrial construction, agri culture or personnel applications. The Industrial Model P 420 is oil-fired, has a capacity of 4,500 cfm and may be used in open areas or ducted, as required. Maximum output is 420,000 Btu/hr vented and 560,000 Btu/hr unvented. Unit may be easily moved to location. The personnel heater Model P 190 provides radiant heat with an output 175,000 Btu/hr. It is oil-fired and completely self-contained including fuel tank, and may be easily moved by one man. PANELBLOC GAS-FIRED INFRA RADIANT INDUSTRIAL HEATERS. The overhead Panelbloc (formerly the Overhead Panelray) offers an entirely new design for industrial heating. Proven for the past seven years in over 15,000 installations, the Panelbloc has demonstrated its advantages as a heater for personnel or equipment. The Overhead Panelbloc is available in two sizes, 62,500 and 125,000 Btu/hr input and it is available for all commercial gas fuels. All models are A.G.A. approved. Operating on the radiant heat principal, the Overhead Panel bloc requires no fans, blowers or electrical energy for operation. The absence of moving parts make maintenance negligible. The sun-like radiant heat output from the Overhead Panel bloc is not affected by drafts from open doors or windows, as suring a deposit of heat on the objects and floor in the area being heated. The Overhead Panelbloc, makes it possible to properly heat spots or areas within large unheated building?, 1284 ' ' f . ; Air Conditioning KSSUSIES Tjernlund Manufacturing Co. 2140 Kasota Avenue . St. Paul 14, Minnesota TJERNLUND "Quick Heat" Manufacturers of DOMESTIC, INDUSTRIAL, and COM MERCIAL WARM AIR HEATING EQUIPMENT, OIL and GAS BURNERS, BLOWERS and DRAFT INDUCERS 7 MODELS 134,000-896,000 BTU OUTPUT -Style "A" Suspended or Lo-Boy Style *'E" Counierflow BLOWER EQUIPMENT Properly sized DWDI blower wheels with correctly designed scrolls. Blowers made by Tjernlund for correct applica tion to each piece of equipment. Extra capacities available for higher air de livery and external static pressure. Style "D" Suspended Units HEAT EXCHANGER Features well known Tjernlund Counter flow flue system coupled with direct fir ing into high heat resistant stainless steel combustion area. No internal baffles or restrictions. FIRING EQUIPMENT Oil fired units utilize Tjernlund high pressure integral draft inducing oil unit for g2 or #3 oil. Single motor operation of inducer and oil burner. Two stage fuel units--standard equipment. GAS FIRED UNITS Feature Tjernlund jet fire power type gas units. Models 150, 200, 280 incorp orate integral draft inducing equipment identical to that shown on oil units with electric ignition, prepurge timing elec tronic safety control. DUCT HEATERS All Tjernlund units available less blower equipment for use in conjunction with air conditioning units or as replacement heaters where existing blower equipment can be utilized. Engineering Data Model 35 50 70 100 150 200 Btu Cfm H* Output S.p. 134,000 184,000 224,000 336,000 500,000 670,000 896,000 1600 2300 2800 4200 6300 8400 10000 Input Oil Gph 1:20 1:65 2:00 3:00 4:50 6:00 8:00 Nat Gas tfh 160 230 280 400 600 800 1000 Blower Phase h.p. H H h H 1 IH 2 Volt H20 Hto' Rpm 680 560 600 520 500 450 480 No. Wheels 1 1 1 1 2 2 2 Wheel Size 12 x 12 14 x 12 14 x 14 16 x 16 16 x 14 18 x 16 18 x 18 For cfm and a.p. other than stated request additional information from factory. Filters Quan. 2 4 4 4 6 8 8 Size 20 x 25 1285 Air Conditioning 9 aUnnditCHoeoaletersrs Fedders-Quigan Corporation Heating Division Lalor & Hancock Sts., Trenton 7, N. J. FE DD EES Manufacturers of Convector-Radiators, Wall Radiation, Baseboard Radiation, Unit Air Conditioners, Unit Heaters, Railroad Car Convectors, Unit Coolers, Refrigera tion Coils, Air-Cooled Fin and Tube Condensers, Clip-on Thermometers, Room Air Conditioners, Automotive Radiators, Car Heater Cores, Dehumidifiers. Fedders Series 17 Hori zontal Unit Heaters made tn capacities from 93- im EDR. FEDDERS CONVECTOR-RADIATORS Feddere Series 16 Downblow Unit Heaters for high or low ceilings and spot locations. Capacities from 155-3050 EDR. Cabinets are attractively designed for free standing, semi-recessed and flush installations. Heating elements have copper tubes and aluminum fins. Types F, FE and FB available with Fedders slide-in front panels. Code-approved in accordance with Commercial Standard CS140-47. Write for catalog. FEDDERS WALL RADIATION Feddere Series 18 GasFired Unit Heaters in eight eisee--183-667 EDR. ; FEDDERS UNIT HEATERS Made in horizontal and downblow types. Well graduated range of capacities to fit requirements. Quick response to manual and thermostatic controls as sures comfort and fuel economy. Com plete data given in catalogs. For industrial, commercial and insti tutional uses. Available with aluminumfinned copper tube elements or steelfinned steel tubes. Flat or sloping top covers. Also expanded metal covers. Write for.catalog. FEDAIR AIR CONDITIONERS , FEDDERS BASEBOARD RADIATION Provides uniform around-the-room comfort. Delivers radiant and convected heat at floor level. No interference with furniture arrangement, draperies or wallto-wall carpeting. Packaged units fac tory assembled in 4, 6 and 8 ft lengths. Aluminum-finned, copper tube heating elements. Also steel-finned steel tube. Full length, built-in deflectors serve as adjustable dampers for individual con trol. I=B-R Approved. Write for catalog. For multiple room installations using circulating hot and cold water supplied from a remote source. Individual room control, quiet operation, no duct work. 3 sizes. Free standing, semi-recessed, concealed and overhead models. Write for catalog. 1286 Air Conditioning Dni< Heaters ILG Electric Ventilating Co. 2880 North Crawford Ave., Chicago 41, 111. Offices tn^more than 40 Principal Cities ILG UNIT HEATERS--STEAM, HOT WATER, ELECTRIC OR GAS Tested and rated by IUHA and ASHVE codes. "One-name-plate" guarantee. HORIZONTAL TYPE UNIT HEATERS--New design. Four side pipe connections for simplified piping. Copper tubes hydraulically expanded for permanent mechanical union with aluminum fins, brazed to one-piece cast iron headers. Suitable for hot . water and steam to 150 lbs pressure . . . tubes hydrostatically tested to 500 lbs. Motor totally enclosed, continuous duty type with oil lubricated bearings. 16 capacity VERTICAL TYPE UNIT HEATERS-- New design. Ball bearing motors shielded from radiant heat. Heating surface features similar to Horizontal Type above. Type V for standard outlet tem peratures, Type VL forlow outlet tem peratures. 12 capacity sizes. ILGDUALGAS UNIT HEATERS--Use natural, manufactured, mixed, Butane- air mixtures, Propane, or Butane gas. Safety pilot, automatic control valve, electric limit switch. Motor has thermai overload protection. TEXTILE TYPE UNIT HEATERS-- More tubes, no fins--for applications where lint, etc. normally adheres to fin surfaces. Other features same as Horizontal Type above. HEAVY DUTY ELECTRIC UNIT HEATERS -- Non-glow heating coil. Ideal for heating isolated buildings and for completely automatic heating, peri odic, temporary, and auxiliary heating. Capacities 1 Yi to 15 kw ... all sizes available for 110, 230, 440 and 550 volts. 1287 Unit Heaters Air Conditioning and Coolers -Heating*Air Conditioning-Refrigeration 1602 Broadway, N. E., Minneapolis 13, Minn. Sales Offices in Pbinctpal Cities w Tube Evaporator M' Condenser McQUAY RIPPLE-FIN COILS McQuay now makes the famous Ripple Fin coils in three tube diameters, % in., in. and % in., in a wide variety of styles and sizes; for steam, hot water, cold water, direct expansion and re frigerant condensing. "Custom Engineered" coils are readily obtained as McQuay's manufacturing methods provide a wide variety of fin spacings, fin heights, finned lengths, rows deep, and circuiting; thereby both space and capacity requirements can be met. Ripple-Fin coils have all tubes me chanically pressure bonded into the wide smooth fin collars providing a permanent bond and high heat transfer efficiency. McQuay coils are pneumati cally tested under water at 300 psig. Ripple-Fin coils have a staggered tube pattern which combined with the ripple fin produces a turbulent air flow and reduces air "by-pass." In addition to the ripples across the air flow the fins of McQuay coils have rippled edges to give strength and a pleasing appearance. McQuay Evaporators and Condensers are dried to minus 40F. dew point to as sure moisture free coils. McQuay Ripple Fin coils have been approved by Underwriters' Laboratories for use as evaporators or condensers with either Freon 12 or Freon 22. m. 3f :L>. :r-'$ Direct Expansion Coil 1288 McQuay, Inc. Air Conditioning HORIZONTAL UNIT HEATERS Two basic types available--Standard and High cfm. 13 Standard models ran^- mg in size from 21,600 to 360,000 Btu; fl High cfm models 20,300 to 248,000 Btu. Write for Catalog 322. DOWN FLOW UNIT HEATERS Two basic types available--Standard and High cfm. 11 Standard models rang ing in size from 39,300 to 500,000 Btu; 11 Down Flow Unit Heater High cfm models 25,400 to 289,000 Btu. Write for Catalog 762. Horizontal Unit Heater "RH" AIR CONDITIONER (For Small Commercial Jobs) Deluxe units with attractive appearance. Four basic sizes: 1000, 1500, 2000, and 3000 cfm. Nominal capacities range from 2 to 10 tons. Freon and water cool ing coils--steam and water heating coils --condenser reheat coils. Write for Bul letin 88. Heating and Ventilating Unit HEATING AND VENTILATING UNIT Horizontal; "vertical, wall and inverted types. Covers the entire range from 1280 cfm and 26,000 Btu to 32,000 cfm and 2,227,000 Btu. Filters, face and by pass dampers, mixing boxes, humidifiers, discharge plenums, and nozzles are available. Write for Catalog 344. SEASONMASTER (Central Station Air Conditioner) Horizontal and Vertical types. Cools, dehumidifies, filters, and circulates air in summer; heats, humidifies, filters, and circulates air in winter. Freon and water cooling coils--steam and water heating coils. Cooling capacities from 1 to 100 tons, cfm from 640 to 21,000 in both sus pended and floor type. Write for Catalog 506. SEASONMAKERS (For Multi-Room Buildings) Room air conditioner, four types: floor, Seasonmaker (Ceiling Type) hideaway, basic, and ceiling. Cooling and heating medium supplied from cen tral plant. Cools, dehumidifies, and filters in summer; heats and filters in winter. Three basic sizes: 200, 400, and 600 cfm (up to 25 per cent of cfm may be fresh air). The Seasonmaker's coin pactness, attractiveness, quiet opera tion, and ease of installation make it ideal for hotels, apartment buildings, hospitals, motels, etc. Write for Bulletin 704. Seasonmaker (Floor Type) ICY-FLO ACCUMULATORS The practical "Storage-Battery" for re frigeration "effect is now available for handling heavy loads of short duration. Ideal for churches, lodges, mortuaries, noon cafeterias, and many industrial applications. Write for Bulletin 109. 1289- Air Conditioner (Year-Round) Seoeonmaster A" Conditioner Cfear-Round) Accumulator ;; ` Air Conditioning UannditCHoeoaletersrs Modine Manufacturing Company Heating and Air Conditioning Division General Offices: 1515 Dekoven Ave., Racine, Wis. Factories at Racine, Wls., LaPorte, Ind., Paducah, Ky., and Whittier, Calif. Sales Representatives in all Principal Cities NEW MODINE AIRditioner* The modern room unit for cooling and heating hotels, apartments, motels, of fices, hospitals, schools and homes. Ideal for new construction and modernization. Provides cooling with chilled water and heating with hot water--from a central source. Filters and dehumidifies while introducing and circulating fresh air. Four-speed motor control for maximum adaptability to conditions. Four types available: The Console (illustrated) for exposed and partially recessed installation ... the Concealed ... the Ceiling ... and the Overhead Models, with or without casings. Each is available in three sizes rated at 1)^ and 2 tons of refrigeration (220, 440 and 640 cfm respectively). All Modine AIRditioners are designed and engineered for fast, easy installation and quick access to all connections and parts. Casings are Parker-Bonderized and finished in a semi-gloss Marine Green primer. MODINE UNIT HEATERS FOR WATER AND STEAM A fully coordinated line of Modine Unit Heaters offers greatly expanded oppor tunities for correct unit heater application. Individually or in combination, they meet the exacting engineering demands' of any space heating application. For steam, Modine builds *6 sizes of vertical (includes IS low outlet temperature models), 19 sizes of horizontal (includes 9 low outlet temperature models), and lOnzes of power throw units. For hot water, Modine builds 13 sizes of vertical and 16 sizes of horizontal units Rugged Condenser--Tubes and headers are cylindrical and brazed at the joints fhr greater pressure-resisting strength. Individual expansion bends of horizontal models absorb differential stresses. One-Piece Construction--Tubes, head er, inlet and outlet connections are brazed into a rugged, pressure-resisting unit. Safety Fan Guard--On all Horizontal models, a built-in fan guard offers con stant protection from exposed fan. Bonderite-Treated Casings--All unit heater casings are Bonderite-treated to prevent rust and bond paint to steel. Efficient Motors--Nationally known makes of continuous-duty, totally en closed fan type. Rubber mounted to prevent vibration noise. Easy Installation--Direct-from-pipe line suspension-for low cost, fast installation .of all Horizontal types. Accurately rated in strict accordance with the Standard Test Code for Unit Heaters- frtfiemrtr 1290 Modine Manufacturing Company Air Conditioning SacJSST' Gas-fired unit heeler MODINE GAS-FIRED UNIT HEATERS Half the weight . . . half the size ... of the average of 7 other leading gas units of comparable capacity. Modine Gas-Fired Units are made with both stainless steel burners and a choice of stainless or aluminized steel heat exchangers. Lighter weight means easier, less expensive instal lation plus faster heat delivery . . . within five seconds after thermostat calls for it. Individually fired tubes provide higher heat transfer. Elongated ports--four times free area of con ventional drilled ports--minimize clogging and simplify clean ing. Seven sizes--from 25,000 to 220,000 Btu. A.G.A. and CGA approved for natural, mixed, manufactured LP and LP air gases. MODINE CONVECTOR RADIATION Modine Convectors combine exceptional beauty with outstanding performance. Available in Deluxe and Standard en closure styles, they are" also obtainable in heavy-duty Institutional models. Floor, wall, sloping wall, concealed, fully recessed and partially recessed styles offer a wide selection to meet any requirement. MODINE HEATING COILS The extensive line of Modine Heating Coils is en gineered to meet the diversified requirements of modern air-handling systems. In addition to more than 1200 cataloged heating coils for use with steam and hot water, Modine produces many cus tom built coils for installation in air handling equipment produced by other firms. Types include standard and non freeze heating and booster coils, and hot water heating coils. Standard Healing CoU MODINE CABINET UNITS The Modine Cabinet Unit line provides eco nomical heating, cooling and ventilating where the expense of air conditioners or unit ventilators is not warranted. A single Cabinet Unit can provide quick, . positive, quiet distribution of heated or cooled air--with or without ducts. Addi tion of inexpensive accessories permits introduction, filtering, heating and dis tribution of fresh outside air for ventilat ing. Five different models provide (1) heat ing with steam or hot water and (2) cooling with chilled water in addition to heating. Various combinations, with or without optional equipment, permit free standing, recessed and concealed instal lations--floor, wall or ceiling mounting. 1291 ' Air Conditioning Unit Heaters and Coolers D. J. Murray Manufacturing Co. ^ T.M.RU, U. t. PAT. OFF, Wausau, Wisconsin Offices in Principal Cities MANUFACTURERS OF GRID UNIT HEATERS AND GRID BLAST COILS Designed andtested to operate with steam or hot water systems--for steam pres sures from 2 lbs to 250 lbs. GRID Unit Heaters are "Put up to stay up" without repairs or other maintenance . . . service records from all types of industry prove One piece construction "fin" heating sections of high test cast iron--no sol dered, brazed, welded or expanded con nections. Patented. Cl (CAST IRON) SERIES GRID UNIT HEATER DATA Model No. CI-1000 CI-1200 CI-1500 CI-1520 CI-2000 CI-2025 Cl-2504 CI-2500 CI-2530 01*3000 01-3000 A 11% 14% 17% 17% 22% 22% 27% 27% 27% 32% 32% Dimensions BC D 10% 13% 15% 15% 20% 6 20% s 25% 25% 25% 31 31 12% 12% 11% 11% 11% 11% 13 13 13 13 13 10% t 13M 16 21 21% 25% 25% 25% 31 31 31 E 17% 21% 23% 28% 28% 35% 35% 35% 40% 40% 40% Motor Hp RPM Ho 1550 Hi 1700 H 1700 54 1700 H 1100 54 1100 54 1100 54 1150 54 1150 54 850 154 1150 Vol. Fan Cfm Capacities 5 PSI Steam Pipe Size 60*F Air Btu/ Hr Final Temp. F Sup ply Re turn 572 29,080 798 45,450 1500 76,500 1700 101,500 2600 143.000 2875 173,640 4350 224.000 3300 206.000 4650 275,800 6300 332.000 8000 1380.000 112 107 114 no 115 107 117 114 108 103 1% 1% 154 1% 154 1% 154 2 154 2 154 2 154 2 154 2 154 2% m 2% 154 Sup port Rod Dia. Approx. Ship. Weight Lbs 54 210 54 280 54 390 54 490 n54 520 660 54 700 54 900 54 1020 54 1070 NO ELECTROLYSIS TO CAUSE CORROSION Low maintenance expense. More air changes per hour. Positive "directed" heat. No leaks--no breakdowns. Lower outlet- temperature. Larger air volume. No soldered, brazed or expanded joints. Open design that keeps units clean. Send for complete Catalog information Send for information on Blast coils and radiation. 1292 . Air Conditioning Unit Heaters and Coolers JOHN J. NESBITT, INC. Philadelphia 36, Pa. Manufacturers of NESBITT SCHOOLHOUSE HEATING AND VENTILATING EQUIPMENT AND AUXILIARY STORAGE CABINETS SERIES-WIND-O-LINE SYSTEM A new hot water heating and ventilat ing system (Syncretizers and Wind o-line piped in series circuits)' that reduces mechanical system costs by eliminating pipe trenches, coverings and individual runouts. Variable water temperature provides better control, ideal cold sur face protection. Pub. 104. THE NESBITT PACKAGE Modern classroom ensemble of storage cabinets and the Nesbitt Syncretizer heating and ventilating unit. Provides quick, economic heat without overheat ing; draft-free ventilation and cooling when needed; room-by-room balance. A fully automatic, quiet-operating unit adaptable to four cycles of control. Sturdy, attractive 28 in. and 32 in. high ensembles with laminated plastic hard top, choice of 6 baked enamel finishes. Capacities from 750 to 1560 cfm anemom eter rating. Publication 101. WIND-O-LINE RADIATION For integration with the Syncretizer under large glass areas with cold expo sures. Consists of fin and tube radiation in a grilled wall-hung casing or recessed in components of the Nesbitt Package. Controlled in cycle with the Syncretizer to meet the heat demands of low tem perature surfaces. Capacities 450, 550 and 700 Btu/lineal ft. Pub. SSI, Sec tion W. SERIES T THERMOVENTS New higher capacity heating and ven tilating units for large auditoriums, gyms, shop rooms, cafeterias and similar gathering places. Available "for both low-pressure and high-pressure, rela tively high - resistance applications. Unique acoustically treated discharge plenum assures quiet operation. Avail able in capacities from 1250 to 15,000 cfm. Publication 270. SILL-LINE RADIATION WITH STORAGE CABINETS For modern school and office installations which require practical storage space combined with a need for heating, this low-cost combination of high-capacity Sill-line perimeter heat ing with Nesbitt open and closed storage shelving is ideal. Cabinets are made in 28 in. and 32 in. heights, 2 ft, 3 ft and 4 ft lengths to form continuous ensembles. Piping Compartment and Fill-in Section conceal control valves, piping, etc. Avail able in choice of 6 attractive baked enamel finishes with lam inated plastic hardtop for extreme durability. Steam heating capacities from 1435 to 2520 Btu per hr per lineal ft, true con densation. Publicaton 261, Section S. 1293 Air Conditioning SS'cST JOHN J. NESBITT, INC. Philadelphia 36, Pa. NESBITT SILL-LINE RADIATION High-capacity perimeter heating in an attractive 16-gauge wall-hung enclosure for use in schools, hospitals, offices, showrooms, etc. Made in five casing styles with one-piece back panel for true, rigid alignment; seven lengths from 2 ft to 8 ft; choice of finishes. Full range of accessories and sleeves eliminate on-thejob cutting. Eight heating elements with CODE approved ratings from 2.9 to 12.1 sq ft EDR. Publication 102. NESBITT HEATING AND COOLING SERIES W. Water surface for air-cool ing, dehumidifying or heating. Copper tubes, aluminum or copper fins. Wide range of sizes in three types: Type WD (continuous tube with exclusive freezeproof drainability feature, and sur face pitched in the casing). Pub. 246. Type WB (continuous tube sections for booster-heating or air-cooling relatively small air volumes but without drainabil ity feature) and Type WC (standard Series W cores pitched in the casing; cast iron headers removable cover plates to permit cleaning, single or double serpen tine circuits.) Pub. 255. SERIES H. General blast coil surface for heating, ventilating, air-condition ing and drying in both high and lowpressure systems. Copper tubes, alum inum or copper fins. Seven types, full range of sizes. Pub. 248. SERIES T. With Trombone-shaped steam-distributing tubes that eliminate stratification and all danger of freezing under modulated valve control. Gives uniform temperatures over the entire capacity range. Ideal for heating and ventilating and for preheating outdoor air. Copper tubes and headers, aluminum or copper fins. Type TO with steam and condensate connections at opposite ends, Type TS with connections at same end. Fin leifgths from 12 in. to 120 in. Publica tion 805. NESBITT GAS-FIRED UNIT HEATERS Modern, attractive direct-fired unit heaters in seven basic models ranging in capacity from 25,000 to 200,000 Btu heat input. Made of die-formed furniture steel finished in heatresistant, baked-on enamel. Low-speed motor equipped with thermal overload protection. Quiet-operating fans; dieformed adjustable louvers. Equipped with automatic con trols and safety pilot. Units are A.G.A. approved and listed by Underwriter's Laboratories. Publication 280. NESBITT BASEBOARD RADIATION A new approach in baseboard design. Combines an enclosure of unusual beauty with a heating capacity ample to achieve true perimeter heating (4.1 sq ft EDR per lineal ft). CODE approved steam and hot water ratings. Copper tube, aluminum fin element. Furniture steel cabinet in 4, 5, 6, 8 ft lengths. Pub. 272. Nesbitt Baseboard Radiation 1294 Air Conditioning * Sd'clSS* JOHN J. NESBITT, INC. Philadelphia 36, Pa. NESBITT UNIT HEATERS are designed to circulate large volumes, of air at comparatively low temperatures, assuring quick heating. _ Ratings of Nesbitt Unit Heaters are based on tests made in accordance with standard test code of Industrial Unit Healer Association and ASHVE. Standard Propeller-Fan Type Featuring universal heating elements of continuous tube design, each size unit gives a comparable range of capacities with either steam or hot water. Made for high temperature drops, low water rates for installation economy. Small physical size for comparable Btu output saves space. Sturdy steel casings with baked-on gray-green hammertone finish for lifetime beauty. Flush-to-ceiling mounting permitted by male pipe connections extending through casing rear. Sealed-for-life motors in most models. Balanced aluminum fans with large blade areas assure gradual, quiet, efficient- air delivery. Eight basic sizes, 24 models, capacities from 15,000 to 335,000 Btu per hour. Sound rated within lowest classifications of new Bulletin IS, I.U.H.A. Sound Test Code. Pub. 401. GIANT BLOWER-FAN UNIT HEATERS Large capacity units for: heating and/or ventilating, free delivery or static pressure, steam or water systems. Twelve basic sizes, each with one of three standard steam coils, three distributing-tube coils, or with a single, two, three, or fourrow hot water coil. Air deliveries from 2000 to 28,000 cfm. Basic steam ratings, 83,000 to 1,735,000 Btu/hr. Hot water capacities from 50,000 to 2,460,000 Btu/hr, 1800 to 3400 fpm. Control may be STANDARD--periodic fan operation; THERMADJUST--continuous fan operation with thermo stat-controlled dampers; or VALVE-CONTROLLED--with thermostat controlling steam supply. Horizontal-suspended, wall, inverted or floor-mounted with wide choice of cowls, fans, dampers, filters and other accessories. Pub. 404- Giant Blower-Fan Type Utile Giant iwn-Blaw Type LITTLE GIANT UNIT HEATERS Adaptable to a wide variety of applications and field condi tions. Eight basic sizes, each with a choice of two (some units three) heating elements. The three smaller sizes are of the blow-through type, having lower outlet velocities generally intended for the lower mounting heights of commercial in stallations. These sizes in down-blow type only. The five larger models are of the draw-through type; produce the high discharge velocities necessary to blow long distances. These five available for either horizontal or vertical down-blow. Durable lightweight Heating Elements. Extended fin-andtube type, copper condensing tubes and plate-type aluminum fins. Steam capacities from 28,500 to 510,000 Btu. Pub. 402. SERIES "C" UNIT HEATERS Tile new Series "C" permits complete flexibility of design and operation. Units are available for floor mounting, hori zontal, wall or inverted applications and can be installed fully recessed-, semi-re cessed or free standing. The discharge or intake can be face, top or bottom-- direct or with ducts. Available in five basic sizes--46 basic capacities ranging from 25,000 to 148,000 Btu per hour. For steam or hot water. Pub. 403. Series "C" Cabinet Heater 1295 Air Conditioning 2S?aSST m HERR1RP. RELSQR American Air Filter Company, Inc. Office -- Louisville, Ky. Factories -- Louisville, Ky., and Moline, 111. Branch Offices and Product Application Engineers in Principal Cities Horizontal Shaft Heater HORIZONTAL SHAFT PROPELLER-FAN TYPE UNIT HEATERS. For ceiling or wall mounting. Use with steam or hot water. Copper heating element, with patented stay tube prolongs unit life. Many models and sizes. Bulletin 700. VERTICAL SHAFT PROPELLER-FAN TYPE UNIT HEATERS. Designed for high ceiling installations. Long life copper heating element for use with either steam or hot water. Units avail able in range of capacities with high or low velocity discharge. Bulletin 700. Gas Fired Heater 4GAS FIRED UNIT HEATER. Operates on all types of gas. Compact in design-- easy to install--^readily moved. Avail able in 7 sizes with heat output ranging from 20,000 to 160,000 Btu's per hour. Bulletin 716. CENTRIFUGAL FAN UNIT HEATERS. Use has supplied > solution to many heating and ventilating problems. Wide variety of models, sizes and speeds assure right unit for every commercial and industrial building need. Bulletin 750. CONSOLE HEATER. Compact, quiet, economical and at tractively styled. Ideal for offices, showrooms, corridors, stores, etc. May be placed on floor, wall or suspended from ceiling. 18 models and sizes. Bulletin 727. _ Console Heater Unit Ventilator DRAFT/STOP UNIT VENTILATORS. A Unit Ventilation System that traps cold drafts before they reach classroom occupants--automatically heats, ventilates and cools. System is quiet and economical--requires little maintenance. Bulle tin 600. Herman Nelson Unit Heaters and Unit Ventilators are tested and rated in accord ance with the Standard Test Codes adopted by the Industrial Unit Healer Asso ciation and ASHVE. 1296 An Conditioning ?^"`ftowen HERmnn nEison American Air Filter Company, Inc. Louisville, Ky. Moline, HI. PROPELLER FANS. A complete line of belt or direct drive ventilating fans. Twenty-nine sizes with wheel diameters from 10 to 54-in. Unit capacities ranging from 655 to 36,150 cfm. Bulletin 800. Propeller Fan <UNIT BLOWERS. Direct or belt drive with forwardly curved or backwardly inclined wheels. Wheel diameters from 4J-in. to 30-in. and capacities from 160 to 18,303 cfm. Bulletin 825. HEATING AND VENTILATING UNIT. Features sectionalized construction, low outlet velocities, slow fan speeds, wide selection of heating coils. Available . with humidifier. Ideal for institutional or commercial use. Bulletin 775. CENTRIFUGAL FANS. Designed for systems requiring a Class I or II cen trifugal fan. Slow speed or non-over loading type. Wheel diameters from 12)4 to 73-in., single or double width. Direct or belt drive. Any rotation or Centrifugalfans discharge. Bulletin 850. RADIATION PRODUCTS . BASEBOARD RADIATION. Recess and flush types for steam or hot water feature aluminum fin on copper tube and are designed to prevent "wall streaking." Bulle tin 792. CONVECTOR RADIATORS. Range of sizes for steam or hot water. Heating elements made of non-ferrous materials. Cabinets designed for free standing or semi-recessed installation. Also sloping top models. Bulletin 791. FINNED RADIATION AND COVERS. Adaptable to any system as a primary or supplementary heating source. Range of sizes with choice of expanded metal, flat top or slant top covers. Bulletin 790. Herman Nelson Propeller and Centrifugal Fans are tested and rated in accordance with the Standard Test Code adopted 1j2o9in7tly' by the National Association of Fan Manufacturers and ASHVE. - Air Conditioning Unit Heaters and Coolers The TRRflE Company * La Crosse, Wis. In Canada: Thane Company of Canada, Ltd., Tobonto, Ontario--Offices in 17 Canadian Cities REFRIGERATION AIR HEATING VENTILATING CONDITIONING HEAT TRANSFER COMPLETE LINE HEATING AND CONDITIONING 88 Trane Sales Offices in U. S. Albany, N. Y. Allentown, Pa. Amarillo, Texas Appleton, Wis. Atlanta, Ga. Aurora, III. Baltimore, Md. Billings, Mont. Birmingham, Ala. Boston, Mass. Buffalo, N. Y. Canton, Ohio Charleston, W. Va. Charlotte, N. C. Chattanooga, Tenn. Chicago, III. Clarksburg, W. Va. Cleveland, Ohio Columbia, S. C. Columbus, Ohio Dallas, Texas Davenport, Iowa Dayton, Ohio Denver, Colo. Des Moines, Iowa Detroit, Mich. Duluth, Minn. Fargo, N. D. Flint, Mich. Gainesville, Fla. Grand Rapids, Mich. Greensboro, N. C. Greenville, S. C. Harrisburg, Pa. Houston, Texas Indianapolis, Ind. Jackson, Miss. Johnson City, Tenn. Kansas City, Mo. Knoxville, Tenn. La Crosse, Wis. Lansing, Mich. Little Rock, Ark. Los Angeles, Calif. Louisville, Ky. Madison, Wis. Memphis, Tenn. Miami, Fla. Milwaukee, Wis. Nashville, Tenn. Newark, N. J. New Orleans, La. New York, N. Y.. . N. Tabbttown, N. Y. Oklahoma City, Okla. Omaha, Nbbr. - Pensacola, Fla. Peoria, 111. Philadelphia, Pa. Phoenix, Abie. Pittsburgh, Pa. Portland, Me. Portland, Ore. Providence, R. I. Raleigh, N. C. Richmond, Va. Roanoke, Va. Rochester, N. Y. St. Louis, Mo. ' St. Paul, Minn. Saginaw, Mich. Salt Lake City, Utah San Antonio, Texas San Francisco, Calif. Seattle, Wash. South Bend, Ind. Spokane, Wash. Syracuse, N. Y. . Tampa, Fla. Toledo, Ohio Trumbull, Conn. Tulsa, Okla. Washington, D. C. West Hartford, Conn. Wichita, Kans. Wilkes-Barre, Pa. Wilmington, Del. Worcester, Mass. TRHI1E REFRIGERATION 1. CENTRAVACS A self-contained hermetic centrifugal refrigeration unit in 19 sizes. Capacities 45 to over 800 tons. 2. RECIPROCATING COMPRESSORS Two cylinder sizes in 4, 6, and 8 cylinder units. Single or duplex direct drive ar rangements with capacities from 10 to 150 tons. 3. COLD GENERATORS Complete refrigeration machine meets all normal requirements of chilled water systems. Models from 10 to 150 tons. 4. CONDENSING UNITS Trane Reciprocating Compressor com plete with water cooled condensers. Capacities 10 to 150 tons. . 5. EVAPORATIVE CONDENSERS Condenses Freon-12_and Freon-22 re frigerants. Uses minimum amount of water. Sizes 3 to 100 tons. The Trane Company TRM1E Air Conditioning Unit Heaters and Coolers AIR CONDITIONING 6-7-8. SELF-CONTAINED AIR CON DITIONERS Packaged air conditioning units for offices, shops or home air conditioning. Available in 6 sizes--9 models ranging from 3 to 20 tons. Smaller 3, 5, and 7}ton sizes have de luxe cabinet design to be installed in the conditioned' space and blend with any surrounding. Larger 10, 15, and 20-ton sizes constitute the commercial line and are usually installed in a remote location, outside the con ditioned area. De luxe units available with water cooled condenser. Com mercial units may be had with either water cooled condenser or built in evaporative condenser. 9-10. ROOM AIR CONDITIONERS UniTrane air conditioners heat, ven tilate, filter and circulate air in the winter. In summer, they cool, ventilate, filter, control moisture content and cir culate air. Two vertical and two hori zontal models. Each available for 200, 300, 400 and 600 cfm delivery. 11-12-13. CLIMATE CHANGERS Any or all phases of air conditioning available in one unit; Two models, hori zontal and vertical, each in 12 different sizes. Capacities range from 600 cfm to 29,000 cfm for any application, comfort or process. Multi-Zone Climate Changers provide a number of zones with different air con ditions at the same time. ; EDUCATIONAL MATERIAL ' "Trane Air Conditioning Manual" ($6.50), an unbiased 380-page textbook for the engineering profession. New re vised edition now available. Many tables and charts Included for making computa tions. In general, text covers heat gains, psychrometry, calculations for the condi tioned air supply, refrigeration for air "conditioning, water for air conditioning, and ducts and fans. . "Trane Refrigeration Manual," a ref- hrence for servicing and installing all types of refrigeration systems. Also available from The Trane Company, La Crosse, Wis. Price $1.50. 1299 The Trane Company Air Conditioning and*coolers8 SELES HEATING AND VENTILATING 14-15. CONVECTORS For all steam and hot water systems. Type C--immediately available in many standard sizes. Other units for specific application problems. 16. BASEBOARD CONVECTORS Non-ferrous fin-and tube heating ele ment. Attractive steel cabinets, 834 in. or 12 in. height. Damper or valve con trols, optional. 17. WALL LINE CONVECTORS High capacity radiation designed to run continuously below window expanses. Cabinet depths 4 in. and 6 in., heights--' 14 in., 16 in., and 26 in. 18-19-20. WALL-FIN Ferrous or non-ferrous finned radiation. Lengths 2 ft to 12 ft in 6 in. increments. Cabinets and expanded metal grilles available. . 21. PROJECTION UNIT HEATERS Model "P" taps the reservoir of ceiling heat, solves multitude of heating prob lems. Louver Cone diffuser, optional. 22. HORIZONTAL UNIT HEATERS Combines Trane broad blade propeller fan and extended surface coil. In 24 sizes, 22,000 to 352,000 Btu. Louver Fin diffuser, optional. 23. STEAM SPECIALTIES Complete line including thermostatic traps, valves, float traps, bucket traps, strainers, vents and temperature control valves. 24. TORRIDORS Blower type unit heaters combining Trane Centrifugal Fans and extended surface coils fob heating and ventilating large spaces and for process applica tions. . 1300 m The Trane Company Air Conditioning Sa*coolers8 25. ROOF VENTILATORS Complete line of supply and exhaust ventilators and ventilating heaters. 355 to 25,000 cfm. 26. FORCE-FLO HEATERS De luxe cabinet-type unit heater with centrifugal fan. Capacities: 17,700 to 105,000 Btu. 27. UNIT VENTILATORS Kinetic Barrier System with lateral ex tensions the length of the outside wall provides constant protection against window downdrafts. Conventional dis charge type units with all air being de livered from the unit itself, also avail able. 28. SHELVING Available for Kinetic Barrier and con ventional units in open or closed type. Have plain tops, or may be linoleum covered. Three sizes. 29-30-31. FANS Centrifugal fans in non-overloading backwardly inclined or slow speed for ward curved types. All standard ar rangements in sizes from 12 in. to 108 in. Capacities 668 to 491,000 cfm. Utility fans, both belt-driven and direct connected, in non-overloading backwardly inclined or slow speed for ward curved types. All standard ar rangements in sizes 434 in. to 30 in. Capacities 110 to 15,450 cfm. Propeller fans with direct or belt drive. Sizes 10 in. through 72 in. Capac ities 475 to 58,560 cfm. 32-33-34. EXTENDED SURFACE COILS Heating coils include a complete range of same and opposite end connection steam distributing tube coils, standard coils, heavy duty, high pressure steam coils, and equipment coils. Cooling coils are manufactured for direct expansion or water cooling in thousands of sizes and types. All extended surface coils have exclusive Delta-Flo Fin for greater heat transfer efficiency. 1301 Air Conditioning unit Heaters Office and Factor; LINDEN, N. J. L. J. Wing Mfg. Co. 59 Vreeland Mills Road, Linden, N. J. Canadian Factory: MONTREAL Branch Offices in European Representative for Heaters: Principal Cities Wanscm, Haren-Nord, Brussels, Belgium WING REVOLVING UNIT HEATERS Air Conditioning Draft Inducers Fans, Blowers Office and Factory linden, n. j. L. J. Wing Mfg. Co. 5Q yreeland Mills Roadj Linden, N. J. Canadian Factory MONTREAL Branch Offices in European Representative for Heaters: Principal Cities Wanson, Haren-Nard, Brussels, Belgium WING FANS An outstanding and unique feature of WING Revolving Unit Heaters is the revolving air distributor, which slowly turns, delivering air obliquely downward, in ever changing direction, to the working floor. Warm air spreads across the floor and around obstacles creating a pleasant atmosphere. In warm weather with heat off, WING Revolving Units furnish refresh ing zephyrs of cooling air. Write for Bulletin HR-6A. , WING FRESH AIR SUPPLY HEATERS The Elbow Type WINGFOIL Duct Fan replaces an elbow in a run of duct. The WINGFOIL Straight Line Duct Fan is inserted in a straight run of duct. In both of these.types the motor, outside the casing remains cool and clean. The WINGFOIL Vaneaxial Fan has a sealed motor within the casing. All deliver large volumes of air for size of fan, quietly, without vibration. Capacities to 95,000 cfm. Write for Bulle tin F-10A. -WING DRAFT INDUCERS & m Ventilating and fume exhaust systems require free admission of air into the building to balance the air exhausted. WING Fresh Air Supply Heaters provide an adequate supply of properly warmed, evenly distributed fresh air without chilling drafts. They cannot freeze, regardless of outdoor temperature, as the steam is on at full pres sure all the time. Write for Bulletin HS-4- OTHER WING HEATERS (Left to Right) WING Stationary Discharge Unit Heater. WING Door Heater. WING Utility (Horizontal Discharge) Unit Heater. WING Electric (Horizontal Discharge) Unit Heater. WING Gas-Fired Unit Heater (Horizontal). WING Gas-Fired (Vertical Discharge) Unit Heater. 1302 . WING Draft Inducers for heating boil ers assure positive draft regardless of weather conditions and eliminate the need for high chimneys. New design has interchangeable inlets, automatic belt tension, sealed bearings. Fan assembly, may be withdrawn from housing for in-' spection or servicing. Available in a wide range of capacities. WING Packaged 'plants up to 120,000 lbs of steam per hour. Power Plant Draft Inducers for power Send for Bulletin 1-56. WING BLOWERS WING Motor Driven Forced Draft Blowers for statics up to 10 in.; volumes up to 50,000 cfm. Manual or automatic capacity regulation. Vertical or horizontal mounting. Voltrol vanes permit regulation to 10 per cent of maximum. Bulletin FD-4- WING Turbine Driven Blowers are easily installed on burner fronts or boiler settings, providing precise draft control manu ally or automatically. Oil-free exhaust steam permits utiliza tion in processes or heating. Bulletin FD-4. WING STEAM TURBINES for driving pumps, fans, compressors, etc. are sturdy, dependable sources of auxiliary power. Capacities to 150 bhp. Temp, to 750F. Speeds to 4000 rpm. Bulletin T-54. 1303 Air-Conditioning Unit Heaters and Coolers Radiator Company Dept. 546, Racine, Wis. Sales & Engineering Representatives in all Principal Cities Heating, Cooling, Air Conditioning Products for Home and Industry, Heat Transfer Products for Automotive, Agricultural, Industrial, Gas and Diesel Engine Applications CONVECTORS & UNIT HEATERS ^Convectors are available from stock in six standard cabinet styles; also Insti tutional and bathroom models; for steam or hot water systems. "Vertiflow" Unit Heaters are built in nine sizes; capacities from 52,600 to^ , 552,000 Btu per hr; adjustable louvers, nozzles, diffusers, Anemostats. ^Type "SH" Unit Heaters are built in 14 ^sizes; capacities from 19,000 to 325,000 Btu per hr; for steam and hot water systems. Cabinet Type Unit Heaters are avail able in number of arrangements, wall^. hung, horizontally suspended, etc.; from" 26,200 to 115,000 Btu per hr. "Perimaheat" Baseboard Convector for hot water service; available in 6 and 8 ft ^lengths; capacity with 190 deg average water 822 Btu per lineal foot; available with either adjustable damper or splitter. Gas-Fired Unit Heaters are available in seven sizes ranging in capacities from 50,000 to 230,000 Btu/hr output. Havf* welded corrosion-resistant aluminized^ steel combustion chamber and heat ex changer; other important design fea tures. HEATING & COOLING COILS ^Young manufactures a complete line of heating and cooling coils for central heating or cooling systems. ' AIR CONDITIONING UNITS Young "YAC" Air Conditioning Units, provide year around service for cooling,^ heating, filtering, circulating, humidi fying and dehumidifying in any com bination. Units are available in nine sizes; capacities from 400 to 22,000 cfm; vertical (right) or horizontal types; ^ Young "Roomaire" Cabinet Air Condi tioner cools, heats, filters, circulates and ' dehumidifies--for use with chilled water systems. Available in 3 sizes and 4 models. 1304 Air Conditioning Unit Heaters Electric 45 Crouch St., Rochester 3, N. Y. Complete line of Electric Heating Systems For HOME, INDUSTRY, FARM Division of Commercial Controls Corporation The advantages of electric heat are well known. However, there is a great dif ference in the safety of electric heaters. Electromode has a completely sealed-in, cast-aluminum heating element which provides absolute protection against fire, shock, burn or explosion. This element acts as a superior heat diffuser, resulting in greater heating efficiency and economy. For Big Rooms -- For HOME and OFFICE -- Bathroom Small Room (im * Fig. 1. Fig. I- Fi0- Fig. i. Electromode Wall-type Heaters are made in models and capacities suitable for all size rooms, ranging from 1320 to 4000 watts, with built-in thermostat or manual con trol. Heat is fan-circulated_at floor level. All have automatic thermal safety switch. The big room heaters have silver grey hammertone finish; small room or bathroom heaters are available in gleaming chrome or white enamel. See figs. 1 and 4 ELECTROMODE RADIANT HEATING PANEL combines radiant and convection heating. Modern design with silver grey hammertone finish. With or without built-in thermostat. Capacity 1100 watts. See fig. 2. ELECTROMODE BASEBOARD HEAT ERS provide low level perimeter heat. Blank sections, endpieces, corners, for making up system to room dimensions. 600, 900, 1200 watts; 120 or 240 volts. See fig. S. ELECTROMODE RADIANT CABLE HEAT. Coils of cable hid den in ceiling radiate clean, healthful heat downward. Each room temperature controlled by separate thermostat. Cables are a measured length of specially constructed and insulated electric wires; waterproof; non-corrosive. Used in plaster or drywall ceilings, or concrete floors. Magic Seal coating pre vents streaks on ceiling. See fig. 5. Fig. s. . For INDUSTRY UNIT HEATERS available in Suspension-type and Combina tion Portable and Suspension models. Capacities from 1500 to 45,000 watts. Ideal for auxiliary warmth in hard-to-heat areas and for complete heating in outlying buildings. Adjustable louvers for directing fan-circulated heat into working zone. Thermostat control available on all models. See fig. 6 and 7. EXPLOSION-PROOF HEATERS for areas charged with inflammable vapors. Listed by Underwriters' Laboratories for Class 1-Group D Hazardous Industries. Convection type. Three models range from 2000 to 6000 watts. See Fig. 8. ELECTROMODE BLAST COILS consist of a bank of Electromode cast-aluminum Fig. 8 heating elements mounted in a 16 gauge formed steel frame having a 14 in. wide flange with in. holes on approx. 6 in. centers for mounting to air ducts. Com plete wiring diagrams for special applications furnished on request. See Fig. 9. All Electromode Heating Systems are approved by Underwriters' Laboratories and are fully guaranteed. ,_ Engineering help gladly given. For more information, see your supplier or write Dept. HVG-16, Electromode Corporation. . ' 1305 Air Conditioning gw|nH,I"er`' Industrial Engineering and Equipment Co. 711 South Theresa Ave., St. Louis 3, MoELECTRIC BLAST COIL HEATERS FOR PACKAGE AND DUCT AIR CONDITIONERS AND SUPPLEMENTARY HEAT 3,487 INSTALLATIONS--150 to 15,000,000 Watts More than 100 Installations at Rockefeller Center Leading commercial, industrial and governmental properties are heated by these units. They offer the following advantages: 1. COMPLETE UNIT, ready for instal- lation, eliminating design and layout work 2. SIZED TO FIT 3. THERMAL CUT-OUTS, furnished with each unit 4. WIDE SIZE RANGE INDEECO UNITS FOR PACKAGE AIR CONDITIONERS, are furnished in 280 3izes to fit 11 manufacturers' package units--write for Bulletin E97P. INDEECO UNITS FOR DUCT-INSTALLATION are furnished in 422 sizes--write for Bulletin E97U. . SPECIAL UNITS in both categories furnished at no extra cost. INDEECO Blast Coil Heaters are made to suit your specifications. You are not compelled to change your plans to meet our specifications. . WRITE for CATALOGS 1306 " parl of TM<`latop totalinll t.esofloo Air Conditioning Unit Heaters, Electric AUT0M1TIC HEAT Wesix Electric Heater Co. 390 First Street - . . San Francisco 5, California Chicago Dallas Denver Detroit Huntsville Los Angeles : New Yobk Portland - Seattle Complete line of Electrical Air and Liquid Heating Equipment for Residential, Commercial A Industrial Applications BASEBOARD PERIMETER PANELS available in standard lengths for simple, inexpensive installation without special tools or metal cutting. Heating lengths: 32 in. and 48 in., 157 watts (536 Btu) per lineal foot.. Control Section (thermostat and switch) 6 in. long. Approved by UL. AUTOMATIC ELECTRIC BRACKET TYPE HEATER for commercial, institutional or industrial applications, these units are available in a large range of sizes and types including explosion-proof models for use in Class I, Group C and D locations. Approved by UL. AUTOMATIC ELECTRIC WALL FUR NACE sizes range from one to eight kilo watts for use in domestic and commercial installations. Available in radiant-con vection-(model illustrated), convector or blower type (5000 watt maximum). Approved by UL. DUCT HEATERS utilizing either Wesix "dust free" or conventional transverse fin elements, these units may be ordered from a wide variety of self contained, standard units, or built to order. Units available complete with sensitive inte gral overtemperature control. LOAD REGULATORS control electric heating capacity automatically by switching voltage supply from 240 volts to 120 volts by means of outdoor thermo static control. Controls heating loads up to 24 kw. Approved by UL. INDUSTRIAL UNIT HEATERS-- BLOWER TYPE for horizontal or verti cal mounting either as suspended unit heaters or duct system use in standard sizes to 60 kw. Larger sizes or models for special applications on order. Ap proved by UL. QUIET AUTOMATIC SWITCH, a motor operated contactor for resistance loads to 24 kw, 1<j> or 40 kw 3^, 240 volts and 33 kw 1< or 55 kw 34>, 480 volts. Actuated by SPDT switch or thermostat. Available with sequence action for control from single switch of two or more contactors. Approved by UL. COMMERCIAL UNIT HEATERS--AXIAL; FLOW sizes from 3 to 40 kw for ceiling or pedestal mount. Feature Wesix longi tudinal fin, "(lust free" inclosed heating elements. Approved by UL. 6 .. HEAVY DUTY WALL THERMOSTAT AND SWITCH for control of electric heating apparatus directly up to 30 amp, this unit includes a lockout switch double-pole in the "off" position. Thermostat action is bi-metallic,sensitive to 24>F. Fits standard wall box mounted horizontally. Approved by UL. " 1307 Air Conditioning Radiant Circulating and Unit Heaters Edwin L. Wiegand Company 7672 Thomas Boulevard Pittsburgh 8, Pa. Representatives in all Principal Cities PRODUCTS: Over 15,000 types, sizes and ratings of Chromalox electric heaters for Industry and Home. All heating elements are metal or alloy sheathed in metal for strength and corrosion resistance, fully Insulated for safety. _____________ Air Conditioning gffS5%SgnK Edwin L. Wiegand Company 7672 Thoma-s Boulevard Pittsburgh 8, Pa. Representatives in all Principal Cities CHROMALOX PANEL RADIANT . WALL Heavy gauge, all-metal construction in cluding breakproof, moistureproof, shockproof, radiant heating plate. Quickly supplies gentle radiant heat con trolled by optional on-off switch or built-in thermostat. For flush or recessed mounting in homes, motels, playrooms, doctors' offices, cottages, first aid rooms. Easy installation. Available in 1000 watts for 120 or 240 volts a-c, and 1500 watts for 240 volts a-c. CHROMALOX BASEBOARD RADIA TORS Clean, balanced radiant and convected heat supplied by rugged baseboard measuring only 8JjJ in. high and 2%6 in. deep. Lengths in standards of 1 ft with 100 watts, 2 ft with 300 watts, 5 ft with 800 watts, 8 ft with 1250 watts. Ex tremely easy to install. Heating element is all-metal fully enclosed, flat strip type which is breakproof, moisture-proof and shockproof. Designed for maintenancefree heating in homes, offices and public buildings. CHROMALOX HI-FLOW PORTABLE Fully-enclosed metal sheathed elements quickly heat the high volume of air forced through the unit by the smooth running fan and motor. Heavy-gauge case in metallic blue finish. Controlled by manual on-off switch with protective device and reset button. UL listed cord 5) ft long with polarized plug. For bed rooms, dens, kitchens, drugstores, etc. In wattages from 2000 to 4000 for 115-120 to 230-240 volts a-c. CHROMALOX FORCED-AIR WALL HEATERS Smooth molded contours of heavy-gauge steel form the front grill of this forcedair recessed wall heater. Recessed sec tion contains a quiet, fully-enclosed motor and smooth-running dustproof fan. Metal sheathed fintube element and fan are controlled by manual on-off switch. Variable temperature control knob for setting automatic built-in ther mostat. Available in wattages from. 1500 to 4000 for 240 a-c supply for gamerooms, living rooms, motels, reception rooms, cottages, etc. 1308 CHROMALOX AIR DUCT HEATERS For use in square or rectangular forced air ducts. Construction of heater allows free-flow of existing forced air circula tion. Finned radiator design presents maximum surface contact.for fast heat ing and minimum air friction. For room heating and process work requiring heated air blasts. Ratings from 6 kw to 100 kw. CHROMALOX FAR-INFRARED UNITS Far-Infrared Radiant Heat for mass heating, drying, baking, dehydrating and similar uses. Compact pre-engineered panels, heaters and lamps can be made into banks, tunnels, and ovens. All-metal construction gives protection against breakage, splash of liquids plus high safety against shock hazards. CHROMALOX FINSTR1P HEATERS Finstrip heaters are used in air ducts having forced circulation, in ovens, dryers and for process work requiring heated air blasts. Temperatures to 750 F can be maintained accurately with'ther- mostatic controls. r-i CHROMALOX HIGH VOLUME HEAT ERS For heating of larger areas or as central heating system for distribution of heat through ducts to desired locations. Rat ings from 15 to 40 kw. CHROMALOX CIRCULATION HEAT ERS Circulation Heaters heat fluids in con vection or forced heating systems; for washrooms, laundries, dishwashers, cen tral heating systems, superheating and drying steam, preheating fuel oils and heat transfer fluids, heating nitrogen and other gases. Temperatures to 750 F. CHROMALOX PORTABLE UNIT HEATERS High volume comfort heater for indus trial offices, shipping depots, stock rooms and isolated small buildings. Sturdy construction of motor fan gives long, dependable service and a reliable supply of heated air. Available with manual or automatic controls in 1,5 to . 4,0jkw capacities. 1309 Air Conditioning and Heating Piping copper and Brass The American Brass Company- Waterbury 20, Conn. District Offices in Principal Cities IN CANADA: Anaconda American Brass Limited, New Toronto, Ontario PRODUCTS--Anaconda Phosphorized Copper Tubes and Fittings; Anaconda "85" Red Brass Pipe; Everdur Metal for storage beaters, storage ' tanks, ducts and air-conditioning equipment They meet the requirements for these types of tubes in Federal Specification WW-T-799a and ASTM Specification B88. Type K, the heavier, is recom mended for heating lines and general piping. Anaconda Copper Tubes, in standard sizes are furnished soft in 60- and 100-ft coils; also hard and soft in 20-ft straight lengths. ANACONDA COPPER TUBES AND FITTINGS CUSTOM-MADE CAPILLARY TUBES For Heating, Plumbing and Air Conditioning Anaconda Custom-Made Capillary Tubes, for restriction purposes, are made Anaconda Types K and L Phosphorized Copper Tubes, assembled with solder joint Fittings, offer an unusual com bination of advantages for hot water and low pressure steam heating systems, in cluding radiant panels. These advan tages may be summarized briefly as fol lows: to specific mutually-agreed-upon airflow limits. These limits alone are the base for production. Initial shipments contain Master Ref erence Sample Tubes with labels giving maximum and minimum flow capacities agreed upon. Duplicate Master Samples are kept in the mill files. Every subse quent shipment of tubes will be made to Low Friction Loss--Because the inside the limits of the Master Samples. surfaces of copper tubes are inherently smoother than those of pipe and tubes made of ferrous materials and also be REFRIGERATION TUBING cause they do not become roughened by the formation of rust, these tubes offer a lower resistance to flow. In addition, the long-radius turns of elbows and the smooth inside surface of wrought copper fittings further reduce friction losses. These factors naturally increase the efficiency of the system, particularly Anaconda Dehydrated Copper Refrig erationTubes are manufactured in accord ance with the ASTM Specification for this product in all standard sizes up to and including % in. O.D., in 50-foot coils. The tubes are sealed immediately after annealing and dehydrating. when it includes a forced-pressure VIBRATION ELIMINATORS circulator. Ease of Installation--In many places the flexibility of copper tubes simplifies connections that ordinarily would be awkward and expensive to make with rigid pipe and threaded fittings. Solder joint fittings are compact. They can be installed in restricted space where the use of a wrench would be impossible. American Vibration Eliminators--Com pressor vibration and noise are muffled in a line equipped with an American Vibration Eliminator. The corrugated bronze tubing is seamless. Copper ferrules and tube ends are braze welded. Each unit is pressure-tested under water, is spot lessly clean and dry, with ends firmly sealed. 1310 Air Conditioning and Heating Piping * copper and Brass The American Brass Company ANACONDA "85" RED BRASS PIPE Anaconda "85" Red Brass Pipe, in standard pipe sizes, is considered the highest quality corrosion-resistant pipe commercially obtainable at a moderate price and is recommended for steam re turn lines. Anaconda "85" Red Brass Pipe con tains 85 per cent copper'and conforms to Government specifications for Grade "A" water pipe. The mark "Anaconda 85" is stamped in the metal at one-foot intervals throughout each length. EVERDUR* Everdur Metal is the original coppersilicon alloy group. It is manufactured by The American Brass Company in five standard compositions and in practically all commercial forms. These high-strength engineering alloys are resistant to a wide range of corroding agents. Because of a versatile combina tion of useful properties, Everdur has become standard as a material for equip ment in many fields of engineering and industry. In addition to their non-rusting prop erties and high strength, Everdur alloys possess many qualities not usually found in metals of this character. They are unusually resistant to general atmos pheric conditions and other normally corrosivq factors. Everdur alloys have excellent machining and working charac teristics and can be fabricated into a variety of forms and shapes. Everdur alloys are available for oxyacetylene, carbon-arc and inert-gas arc welding. Everdur Tanks--Everdur copper-sili con alloy is an ideal material for durable, non-rusting water tanks of every descrip tion--from domestic range boilers to large storage heaters for hotels, laun dries, hospitals, textile plants, schools or breweries. Everdur is made in all commercial shapes, including annealed tank plates which have physical properties as given in ASTM Specification B96. Minimum specification requirements for hot-rolled-and-annealed tank plates are: Tensile Strength, 50,000 psi.; Yield Strength (at 0.5 per cent elongation under load) 18,000 psi.; Elongation, 40 per cent in 2 inches. Welds made with annealed Everdur tank plates meet the requirements for construction in the A.S.M.E Boiler and Pressure yessel Code. For additional data and names of fabri cators address our nearest District Sales Office. EVERDUR FOR AIR-CONDITIONING EQUIPMENT Because of its strength and welding properties, Everdur may be. substituted for steel and fabricated by substantially the same methods, with much the same equipment as steei. Everdur metal has been used with marked success for fans, blowers, ducts, humidifiers, cast and wrought parts of other equipment items subject to corro sive influences. EVERDUR LITERATURE Descriptive literature containing much pertinent tabular data will be sent on request. * "Everdur" is a trademark of The American Brass Company registered at the U. S. Patent Office. RESTRICTOR TUBE FORMED TUBE PARTS HARD COPPER TUBE CUT TO LENGTH COPPER TUBE IN COILS AND STRAIGHT LENGTHS * FITTINGS FOR TYPES K AND L TUBES VIBRATION ELIMINATORS FLEXIBLE REFRIGERATION TUBING CONDUIT DIE PRESSED FORGINGS * COPPER, BRASS, BRONZE IN SHEETS, WIRE, RODS, TUBES AND SPECIAL SHAPES ` 1311 . Air Conditioning and Heating Piping uiugfS~;,,,, Aeroquip Corporation, Jackson, Michigan ^\enoquip This new coupling for "Freon 12" and "Freon 22" applications is finding wide use for all refrigeration and air-condi tioning applications. Convenient connec tion and disconnection without loss of refrigerant or inclusion of air and mois ture. Simplifies production and charging and testing of equipment and permits shipping of factory charged units for easy field installation. Rapid assembly in equipment by means of sweat-type adapters and mounting flanges. Sizes through 114 in. O.D. tube size. AEROQUIP 1540 HOSE FOR "FREON 12" APPLICATIONS Dash Size 4 6 8. 10 12 16 20 24 32 40 48 O.D. Tube Size H H a n H I IPS 2 2H 3 Min. Operating Min. Burst Pressure Bend Pressure psi Radius 2000 350 3 2000 350 4 20C0 350 m 2000 350 5H 1400 350 1400 350 m 1400 350 0 1400 350 11 1200 350 13J4 700 175 24 700 175 33 Aeroquip 1540 hose and reusable fittings are designed for refrigerating and air conditioning systems using "Freon 12." Aeroquip flexible hose lines can. be in stalled easily, even in confined areas, withstand compressor vibration and re duce noise. Ease of assembly makes Aeroquip hose and fittings ideal for en gineering mockups and production mod els. Available in sizes from Y in. to 3 in. Operating pressures up to 350 psi; temperature range --40 F to +170 F. 1312 Pipe and Tube Ait Conditioning and Heating Piping COPPER AND BRASS INCORPORATED Executive office: 230 Park Avenue, New York 17, N. Y. HILLS--Baltimore, Md.; Brooklyn, N. Y.; Chicago, Clinton, and Joliet, III.; Detroit, Mich.; Loa andAngeles Riverside, Calif.; New Bedford, Mass.; Newport, Are.; Rome, N. Y. . DISTRICT SALES OFFICES--Atlanta, Ga.;. Boston, Mass.; Buffalo, N. Y.; Cincinnati, Ohio; Cleveland Ohio; Dallas, Tex.; Dayton, Ohio; Grand Rapids, Mich.; Hartford, Conn.; Houston, Tex.; Indianapolis, Ind.; Miami, Fla.; Milwaukee, Wib.; Minneapolis, Minn.; New York, N. Y.; Philadelphia, Pa.; Pittsburgh, Pa.; Providence, R. I.; Rochester, N. Y.; St. Louis, Mo.; San Fran cisco, Calif.; Seattle, Wash. ' TUBE AND PIPE FOR GENERAL CONSTRUCTION Revere produces a wide range of Pipe and Tube for various industrial uses including condensers, aftercoolers and similar heat exchangers. The services of Revere Technical Ad visors are available without obligation to assist Engineers, Designers and Con tractors in the selection of suitable Revere products for various' appli cations. REVERE COPPER WATER TUBE For: Hot and cold water service lines Underground systems for water, oil or gas _ Drainage line and soil pipe Fuel oil and compressed air lines Heating systems--hot water and steam Radiant Panel Heating (technical book let, "Design Procedure and Installation Practices for Radiant Panel Heating" available upon request). LENGTHS, TEMPERS AND OPERATING PRESSURES Type K K L L M Temper Hard Soft Hard Soft Hard Pressure Standard Lengths Pounds Straight Coils up to400 12 and 20 ft " " 250 " " " 250 " " " 150 " " " 250 " ___ 60 ft -- 60 ft -- STANDARD DIMENSIONS AND WEIGHTS Size .in In. H 4* W H 1 m n* 2 2>* 3 344 4 5 6 O.D. in In . , WaU T h ic k ness In . Wall T h ic k ness In . Wt Lb per F t WaU T h ic k i ness In . Wt Lb 1 per F t TypeK Type L Type M .375 .500 .625 .750 .875 1.125 1.375 1.625 2.125 2.625 3.125 3.625 4.125 5.125 6.125 .035 .049 .049 .049 .065 .065 .065 .072 .083 .095 .109 .120 .134 .160 .192 2* & .145 .269 .344 .418 .641 .839 1.04 1.36 2.06 2.93 4.00 5.12 6.51 9.67 13.9 .030 .035 .040 .042 .045 .050 .055 .060 .070 .080 .090 .100 .110 .125 .140 .126 .198 .285 .362 .455 ' .655 .884 1.14 1.75 2.48 3.33 4.29 5.38 7.61 10.2 .025 .028 .032 .035 .042 .049 .058 .065 .072 .083 .095 .109 .122 .145 .204 .328 .465 .682 .940 1.46 2.03 2.68 3.58 4.66 6.66 8.92 Revere Copper Water Tube does not rust. It is smooth inside and out, easy to install and bends and flares readily. There is no thread cutting; it takes solder or compression type fittings. Specifications: Federal: WW-T-799 ASTM: B88 REVERE DRYSEAL COPPER TUBE For: , Air conditioning and refrigeration sys tems General service work Revere Dryseal Copper Tube is de hydrated and sealed at the factory be fore packaging. It is soft and flexible and when flared for compression fittings, it does not split on the ends. Its ability to take smooth hand bends virtually elimi nates the need for fittings. 50 ft. coils in sizes from M io. to % in. O.D., with wall thicknesses from .030 in. to .035 in., are packed in individual cartons. REVERE RED BRASS & COPPER PIPE For use when threaded pipe is required. Both are manufactured in standard pipe sizes--hence can be used with standard threaded or silver brazed fittings. Because of their extraordinary resistance to corrosion, they function with unimpaired efficiency even after many years of normal service. Specifications: Revere Red Brass Pipe meets the fol lowing specifications: Federal Standard: WW-P-35I, Grade "A" Navy Department: 44P12, Grade "A" ASTM: B43 (Red Brass) Revere Copper Pipe meets the following specifications: Federal Standard: WW-P-377 Navy Department: 44P2 ASTM: . B42 Air Conditioning and Heating, Piping Tube and Fittings Wolverine Tube 1463 Central Avenue Detroit 9, Michigan Manufacturers of Quality-Controlled Tubing and Extruded Aluminum Shapes Plants in Detroit, Michigan and Decatur, Alabama Sales Offices in all Principal Cities. . Wolverine Trufin is available in Canada through the Unifin Tube Co. London, Ontario. WOLVERINE COPPER WATER TUBE ... a roll of tube that rolls Wolverine's round cartons for rolls of copper water tube represent a new pack aging concept. The carton now becomes even more functional than its primary job of protecting the contents. For ex ample, it can be rolled like a hoop to storage or job site. There's an arm hole in the middle for convenient carrying. ' And also important to users, it can be used as a reel with the carton protecting the tube .right up to its last inch. The package is extra sturdy, designed with a heavy corrugated core for extra protection. It's easy to open, easy to identify, and color coded. WOLVERINE COPPER WATER TUBE Wolverine copper water tube is available in all three types: Type K--in straight lengths and coils-- is recommended for general plumbing involving severe service conditions and for heating, gas, steam and oil lines and for underground service. It is available in nominal sizes from 34 in. through 6 in. Type L--in straight lengths and coils-- recommended for general plumbing in volving less severe service conditions and for interior applications for heating, gas, steam and oil lines. Available in nominal sizes from 34 in. through 6 in. Type M--in straight lengths only--suitable for use with soldered fittings only; for interior applications, for heating and for waste, vent, soil and other non-pressure applications. Available in nominal sizes from % in. through 6 in. Wolverine also manufactures S.P.S. and extra heavy pipe in copper and red brass. Pipe is available in standard lengths of 12 and 20 feet. Sizes range from 34 in. through 3^ in. t? 9 WOLVERINE COPPER REFRIGERATION TUBE Wolverine copper refrigeration tube is well-known in the industry. It, too, is packaged in round cartons. It has mirrorbright inside diameter 'finish, is dehy drated, is consistent in quality and soft in temper.' CONVENIENT NEW SEAL: Wolverine has a new refrigeration tube seal that keeps tubing clean and dry. Because the O.D. of the seal is no larger than that of the tube proper, it makes it easier to insert through partitions. 1314 Air Conditioning and Heating, Piping Tube and Fittings Wolverine Tube 1463 Central Avenue Detroit 9, Michigan Manufacturers of Quality-Controlled Tubing and Extruded Aluminum Shapes Rants in Detroit, Michigan and Decatur, Alabama Sales Offices in Principle Cities Wolverine Trufin is available in Canada through the Unifin Tube Co., London, Ontario. WOLVERINE CAPILATOR* Wolverine Capilator* is designed for pre cision control in the metering of gases, liquids or air. Capilator is plug drawn-- has a smooth, mirror-bright bore held to exceptionally close limits. It can be made of copper or aluminum and is available in sizes from .026 in. to .090 in. inside diameters. Capilator is washed, deburred, flow-tested and its ends are paper wrapped. WOLVERINE TRUFIN* Wolverine Trufin is an extended surface tube with fins extruded from the tube wall. It increases heat transfer surfacetransfers more Btu's per foot of tube. Fins resist vibration, temperature changes and fluctuating pressures. Trufin is available in a wide range of sizes, alloys and fin spacings in copper, copper base alloys, aluminum, electric-welded steel and bi-metal. FABRICATED TUBULAR PARTS Wolverine's fabrication facilities include the Wolverine Spun End Processf. Onepiece tubular shaped parts with closed or partially closed ends can be produced in one fast operation. Other fabrication techniques include finning, coiling, bend ing, expanding, flaring, brazing and soldering and piercing, to name but a few. ALUMINUM TUBE AND SHAPES Wolverine produces strong, lightweight aluminum tube--plain or Aimed--drawn or extruded--in the following alloys: 1100 (2S); 3003 (3S); and 6063 (63S). Wolverine aluminum extruded shapes, in the same alloys, are rigidly quality con trolled, can help you save machining and assembly time and reduce material re quirements. FIELD ENGINEERING SERVICE For the convenience of our customers. Wolverine maintains a Field Engineering service. Highly-trained tubing technicians are ready at all times to help you solve such problems as design, corrosion and fabrication. U. S. Pat. Off. t A.patented process Re. 22465. - ' 1315 Air System Equipment daSers Air Devices Inc. Air Diffusers Exhausters Air Filters. Filter Holding Frames Industrial Furnaces 185 Madison Are. Hew York 16, N. Y. eGlIRlP pappiicTS cri 1 Agents in All Principal Cities AGITAIR AIR FILTERS LOWER RESISTANCE The sustained low resistance of the Agitair FM means sustained peak volume of air for longer periods of time. . mo loss in air volume. . mo danger of un loading. . .clean filtered air at all times. HIGHER DUST HOLDING CAPACITY Employing a new formula for air filtra tion the new Agitair FM holds more dirt, from two to six times as much as ordinary 2 in. permanent, cleanable filters. No early clogging of air passages. . .less frequent servicing. . .lower mainte nance cost. TWO TYPES OF HOLDING FRAMES HOW IT WORKS High turbulence of many finely divided air streams is the keynote of Type FM air filters. The media divides the air into countless fine streams and throws those streams into violent cyclonic turbulence against countless viscous-coated "wip ing surfaces" which virtually scrub the air clean by catching and holding the dirt. HIGH VELOCITY The Agitiar FM Filter is designed to perform at highest efficiency at an ap proach velocity of 432 fpm--or 1200 cfm through a 20 x 20 in. filter panel. 1/3 LESS SPACE REQUIRED Individual type: Designed and con structed for easy handling in single unit installations, and to facilitate "on the, job" assembly, into a multiple unit bank. Pre-Fabricated Type. Made of heavy gauge steel and delivered completely knocked down. They can be quickly and easily bolted together to form a sturdy panel bank. GREASE FILTERS Strong Expanded Metal Media recom mended for use in kitchens where grease-ladened air is a fire hazard and a main tenance problem. Prevent grease from entering exhaust ducts, eliminate fre quent duct cleaning, protect fans, greatly reduce fire hazard, and help maintain good ventilation. AGITAIR WIND-ACTUATED EXHAUSTERS The ability of the FM to filter, with greater efficiency, 50 per cent more air at the high velocity of 432 fpm reduces the number of filter panels required. Now TWO FM's will do the work of THREE ordinary filters % less space required . . . fewer units to be installed . . . fewer units to be serviced . . . overall installa tion and maintenance costs reduced to a minimum. Provide proper ventilation regardless of HIGH EFFICIENCY ' wind direction, and with positive elimi nation of down-draft. Functions at At the recommended velocities, the Agitair FM has a high dust arresting efficiency, which increases as the dust fieak efficiency at average low wind ve- ocities. Will not restrict the exhaust of air or gases when there is no movement load is applied. of out-door air across the head. 1316 Air System Equipment Airmen Air Filter Corporation 108G North Water St. Canadian Representative Milwaukee 2, Wis. DOUGLAS ENGINEERING CO.. Ltd. Montbbal AIR FILTERS (formerly Aircor) Permanent-Cleanable GREASE FILTERS AIRSAN AIR FILTERS Industrial Domestic Commercial AIRSAN VIRO-CRIMP FILTER Pat: No. t,eS3,m The specially designed high velocity Alrsan Viro-Crimp filter core is viscous type and constructed of horizontal layers of galvanized wire mesh so arranged as . to assure jt large filter-area with no ap preciable pressure drop. Its outstanding Viro-Crimp is designed to operate at face velocities of 300-500 fpm at minimum resistance. Viro-Crimp edges are hemmed, an important safety feature that provides a smooth surface, extra rigidity and filtering area. Alrsan Viro-Crimp filters are easily cleanable. Drain slots are provided, hasten drying and aid in cleaning. Air- san Viro-Crimp Air Filters are of all metal construction throughout, the formed galvanized steel frames haying full bronze welded corners and joints. Bulletin W801. ' ENGINEERING DATA ' Initial Resistance Rated Efficiency Type Fi * (1 in. thick) .060 in. w.g. at 288 fpm 98.5% Type F* (2 in. thick) .065 in. w.g. at 288 fpm 98i5% Type Di (2 in. thick) .09 in. w.g. at 288 fpm 98.5% Type D* (1 in. thick) .10 in. w.g. at 288 fpm 98.5% Type W (2 in. thick) .07 in. w.g. at 300 fpm 95.1% Type W (2 in. thick) .012 in. w.g. at 500 fpm 97.9% AIRSAN FILTER RETAINER Meticulous design includes such features as positive snap locks, oil resistant rub ber seals to assure no by-pass of air. Particularly flexible to any type of in stallation of flat or "V" banks. Easily built up to any height or width by pro gressive addition of Alrsan Filter Re tainers. Available in 2 or 4 in. sizes. Bulletin ISOS. Airsan's expanded metal face plate acts as a lint arrestor to provide easier clean ing and servicing. It distributes air evenly over entire filtering area provid ing high filtering efficiency and dust holding capacity with low resistance. Media is viscous type, permanent, clean able, and is constructed of multiple layers of galvanized wire mesh to give maximum air resistance. All Airsan Filters have full bronze welded corners, galvanized steel frames and drain slots for quicker, easier cleaning. Alrsan Air Filters are available in stand ard 1 in. and 2 in. thickness--Bulletin LS01. Also HEAVY DUTY filters for industrial and special applications in 2 in. to 4 in. thickness--Bulletin H01. AIRSAN GREASE FILTER Permanent cleanable type Alrsan Grease Filters specially designed for range cano pies, galleys, kitchens. Removes grease at source, reduces fire hazard in exhaust ducts and prolongs life of fans, motors and other mechanical equipment. Assemblies for mounting on ceiling or wall, single or multiple units--includes holding frames, support ing angles and end seals. Bulletin L508. Initial Resistance: .07 in. w.g. at 216 fpm Efficiency Rating: 98.5% Stand. Thickness: 2 in. Write AIR FILTER Coi i. for Complete Bulletins Air System Equipment ^dFcKers CORPORATION 25000 Miles Rd. Cleveland 28, Ohio THE FILTER ENGINEERS Representatives in all principal cities Since 1925, Air-Maze engineered air filtration has been successfully applied to every phase of the heating and ventilating industry. A complete line of filters are available for fresh air and re circulated air intakes, kitchen range canopies, railroad, marine and aircraft applications. Send for catalog sheets on specific products. General catalog also available on request. micron diameter, has rated efficiency over 90 per cent, as tested by the Na tional Bureau of Standards Discoloration Method. Collects smoke, fumes, pollens, and soot. AUTOMAZE AUTOMATIC AIR FILTER AIR FILTER PANELS Available in metal washable, viscous im pingement types, and dry disposable types. Dry `filters also available with washable strainer-type filter element. ELECTROMAZE ELECTRONIC AIR FILTER Where continuous operation without servicing is required, the Automaze "pulse action" automatic self-cleaning filter should be used. It combines a double filter panel curtain with a positive effective panel cleaning action to provide the best in viscous impingement air filtration with a minimum of mainte nance. New self contained drive mecha nism and unitized control system simplifies installation. Standard Auto maze filter media is satisfactory for most installations, but other media types are available for special applications. ACCESSORIES Super-cleans air. Has semi or completely automatic vertical spray washing sys tem. Removes particles as small as 0.1 Cleaning tanks, holding frames, com plete assemblies for range canopies, viscous adhesive coatings, spray guns, etc. are available for complete installa tion and service Requirements. . 1318- Air System Equipment ^ American Air Filter Company, Inc. 673 Central Avenue, Louisville 8, Ky. American Air Filter of Canada, Ltd., Montreal, P. Q. AAF THE COMPANY: The American Air Filter Company, Inc., is recognized in ternationally as an authority on air filtration and dust control. In 30 years, its leadership and scientific "know how" have been responsible for installations of AAF equipment in every industrial ized part of the world. Because its con tinuous research, high engineering stand ards and exclusive specialization have been consistently maintained, AAF equipment is used by leading companies in nearly every industry and is specified by leading architects and engineers for use in commercial and industrial air conditioning. The American Air Filter Company, Inc., manufactures a complete line of air filtering and dust control equipment. A few representative types are shown here. AAF's years of experience and the scope of its knowledge dealing with the elimination of air borne particles in every form insures maximum efficiency in ' application, design, manufacture and installation ... with a minimum of field engineering. Write AAF on all problems of air filtration and dust con trol, or itB Herman Nelson Division (see pages 1296-1297) on heating or, ventilat ing problems. AAF AIR CLEANING PRODUCTS Electro-Matic Self-Cleaning Electronic Precipitator--The Electro-Matic Precip itator is an automatic electronic pre cipitator combining advanced principles of electronic air cleaning with an ex clusive self-cleaning principle. It elimi nates the necessity of shutting down the filter for manual cleaning, minimizes the need for personal attention and permits continuous high-efficiency oper ation. It also allows the Electro-Matic filter to be built in standardized selfcontained sections, easy to install and with all exposed parts of the filter casing electrically grounded for the protection of operating personnel. Send for Bul letin No. B50. ROLL-O-MATIC Renewable Media Filter--An automatic air filter featuring a low cost, renewable media filtering cur tain of bonded glass fibers supplied in convenient roll . form. The media, mounted at top of filter, moves down the face of the ROLL-O-MATIC and is re rolled on a driven spool at bottom. Intro duction of clean material to maintain desired operating resistance is controlled by an automatic time switch. ROLL-OMATIC's maintenance-free operation provides continuous, high efficiency cleaning at less than half the operating cost of a disposable type filter of equal capacity. Send for Bulletin 848. 1319 American Air Filter Co., Inc. Air System Equipment Electro-Cell Electronic Filter Electro-Cell Electronic Filter--A plate AMER-glas Replaceable Unit Filters. type electronic precipitator offering sim A new viscous impingement type for plified design, improved performance and maintenance advantages. Built in verti cal sections 2-ft and 3-ft wide. Hinged ionizers extend the full height of the sections for easy access. Collector as semblies may be removed for individual cleaning--washed in place manually--or, with the addition of Type "H" Washer, eliminating atmospheric dust from forced air heating systems. The highly efficient filtering media consists of continuous, curled and interlaced, extremely fine glass filaments, bonded with thermo plastic to form a thick resilient pad. The pad is sprayed with a special Visco cleaned automatically by traveling sine and placed in a fiberboard casing water sprays. Write for Bulletin No. 252. between perforated metal grilles. The Electro-PL: An exclusive dry-type elec tronic air filter with charged Airmat collector element which combines air filtration and electronic precipitation in AMER-glas is nonflammable, sanitary and odorless and the Viscosine remains, in a fluid-jell state for the life of the filter. Available in 15 sizes. Write for a single unit. Gives intermediate effici- ' Bulletin No. 211-A. ency at lower cost, when the need for super-clean air is not indicated. How ever, it has twice the efficiency of un charged dry-type filters. Available in Straight Bank or "V"- arrangement to meet virtually any space or capacity requirement. Send for Engineering Bul letin No. 257. Airmat Type PL-24--Airmat filters use standard Airmat medium, renewable af ter collecting dust load. Used both for comfort and industrial air conditioning. Available with unit frames to be set up to meet any capacity requirement or space condition. Send for Bulletin No. 230. Multi-Duty Automatic Filter provides outstanding features of performance and design and will accommodate either armored screen panels or die stamped louvre panels available in three types. Type HV-2 Filter: A high capacity, lowresistance unit designed for velocities up to 500 fpm. Exclusive pyramid pocket media design eliminates through-air pas Offers advantage of uniformly constant sages and gives uniformly high efficiency air supply, fixed operating resistance over wide range of air velocities. HV-2 and automatic operation. Ideal for ven ` has large dust capacity, long life, and tilation and air conditioning service. decided advantages where space is Available in any size or capacity. Send limited. Available in three designs. Write for Bulletin No. 241-A. for Engineering Bulletin No. 203. AMER-glas Disposable Filter 1320 Airmat Type PL-S4 American Air Filter Co., Inc. Air System Equipment AanirdFCillteearnsers AAF ROTO-CLONE DYNAMIC DUST PRECIPITATORS THE ROTO-CLONE is an exclusive, pat ented development of AAF combining the functions of exhausting, separating and storing dust in one simple, com pact, self-contained unit. Most types of dust collectors or separators are so large that they are usually installed out doors, which requires long pipe runs, increased power consumption, and higher installation costs. The ROTO-CLONE, however, eliminates expensive ductwork and reduces both installation and operat ing costs to a minimum. Available in a wide variety of types and sizes for either individual unit or central system in stallations and with wet or dry type collectors, the ROTO-CLONE has a proven record of economy and efficiency covering thousands of production fine and individual applications. Write for profusely illustrated 35-page application and Engineering Bulletin No. 274-A. Type D ROTO-CLONE--A dynamic precipitator designed for dry collection of granular industrial process dust. Combines functions of exhauster, dust separator and storage facilities in one compact unit. High collection efficiency remains con stant over entire pressure volume range. Adapted for individual unit or central system use. Capacities--from 100 to 15,000 cfm. Write for Bulletin No. 274- _Type W ROTO-CLONE offers high dust separation efficiency where extreme fines and heavy dust loads are involved. Com bines dynamic precipitation with inte gral water sprays. Delivers a constant air volume and collects dust as a sludge. Compact design makes for easy, low-cost installation. Capacities from 1,000 to 50,000 cfm. Write for Bulletin No. 274. Type N ROTO-CLONE is a hydro-static collector, with induced water scrubber. Requires minimum space--easy to in stall. No moving parts, spray nozzles or pumps. Completely self-contained with dust discharged as a sludge. Capacities --from 1,000 to 50,000 cfm. Write for Bulletin No. 277. Type N ROTO-CLONE AMERjet AMERjet--A reverse jet type fabric arrester offering high collection efficiency, constant pressure drop (constant air volume), compact design and continuous operation. Other features are (1) tension control to compensate for variation in fabric dimensions, (2) rugged mechanism for dislodging col lected material with high pressure air jets and (3) venturi shaped inlet for dust-laden air which extends life of cloth. Available in range of capacities. Bulletin No. 279. AMERclone--A dry centrifugal dust collector designed to handle large exhaust volumes containing dust in high concen trations. Unit requires small space due to compact design and high cleaning capacity of the AMERclone tubes. Abrasion resistant construction featured throughout. Collection effi ciency remains practically constant over wide range of exhaust volumes. Available in wide range of capacities. Write for Bulletin No. 29t. 1321 . Air Filters Air System Equipment nd cieaneTM Air Recover; Air Recovery Air Purification Activated Carbon Barnebey-Cheney Company Cassady at Eighth Columbus 19, Ohio In Canada: BARNEBEY-CHENEY LTD, St Johns. Quebec Odor Removal Solvent Recovery Reactivation Service PUR AIR RECOVERY By purifying and recirculating air which is already heated or cooled, as much as 40 per cent can be saved on operation costs of heating or air conditioning equipment. A Pur Air RECOVERY system can reduce the volume of outside air necessary for ventilation by 90 per cent. "First cost" of new systems can also be reduced 20 to 45 per cent by incorporating activated carbon for Air Recovery. ODOR REMOVAL Pur Air adsorbers eliminate odors from fresh air intakes, from exhausts, or from enclosed spaces. Pur Air Activated Carbon adsorbs or physically removes odors, staleness or stuffy air, revitalizing it for re-use at low cost. AIR PURIFICATION Air Purification is sometimes necessary without possibility of recovery, when in dustrial wastes, processing or combustion odors, vaporous impurities, atmospheric contaminants or other nuisance situations must be handled. Pur Air Activated Car bon does a thorough job of air purifying. SOLVENT RECOVERY Our Solvent Recovery Division designs, engineers, fabricates and erects complete systems for industries requiring recovery of volatile solvents which are normally lost in "thin air." Such systems readily amortize installation costs in savings of solvent. ACTIVATED CARBON and REACTIVATION SERVICE . We manufacture high-grade Activated Carbon for all heating and ventilating, as well as industrial uses. We also reactivate any carbon of suitable type or hardness to peak adsorptive capacity. PUR AIR ACTIVATED, COCONUT-SHELL CARBON ADSORBERS Barnebey-Cheney Company manufactures both the Activated Carbon and the equip ment to use it. This combined, integrated function permits the Pur Air Division to offer the greater protection of better quality carbon and adsorbers designed to utilize this basic ingredient to the fullest extent. Pur Air adsorbers are com pact, easy to handle, and designed spe cifically for the special jobs they're meant to do. DACOR DACOR stands for Disposable Activated Carbon Odor Remover. It utilizes highgrade activated carbon in a lightweight framework of porous fiber tubes. DA COR clips easily to either permanent or throw-away dust filters in forced air furnaces or air conditioning units. It is also available with built-in dust filter. DACOR is designed to adsorb all odors after several recirculations, will last from three months to one year--de- ending on conditions--and can easily Ce replaced. DACOR "soaks up" odors, allows pure, fresh air to recirculate. Stocked in standard dust filter sizes; other sizes are manufactured to order. 1322 Barnebey-Cheney Co. Panel Adtaiicr Filter Fold, Model M avail able with builtin dust filter on request A..ir S_ystem Equi.pment * AirCFclfeltaenrsers Air Recovery PUR AIR PANEL ADSORBER The Pur Air activated, coconut-shell charcoal Panel Adsorber permits instal lation of the most carbon in the smallest possible space. For precision results, in stall one Panel Adsorber per 100 cfm. Air resistance only 0.30 (w.g.). Available in assembly frame components or selfcontained units. PUR AIR FILTER FOLD "FF" Another Pur Air "package filter" that does a big job for its size. In a small space--24 in. x 24 in. x 8% in.--it recovers (deodorizes) 1000 cfm of "used" air. Can be used in multiples in duct work. Re moves stuffiness, body odors, smoke irri tants, etc., in homes, public buildings, restaurants or any type of enclosed spaces. Model M handles 1000 cfm, con tains 45 lb carbon. Model D, 500 cfm, with 22J lb. carbon. Stat. 125 in. mg. M-15 CANISTER For replacement on existing systems, or new installations where canister-type equipment is indicated. BREEZE UNIT Modern design portable unit for home or office. Uses Dacors to adsorb common household odors, reduce amount of outside air needed for ventilation. Three sizes available. AIR FRESH'NER Purifies air, removes odors from small laboratories, offices, hospital rooms, darkrooms, toilets, etc. Capacity is 65 cfm. Serves up to 1500 cubic feet. PORTABLE UNIT Suitable for larger areas--offices, recreation rooms, hospital rooms, libraries, vaults, etc. 500 and 1000 cfm models available. FIXED MOUNT UNIT A complete line of self-contained units available for ware houses, cold storage areas, industrial space, etc. Made in 12 sizes, from 220 cfm to 2640 cfm. Is particularly adapted to apple storage use, to prolong life of stored fruit. STANDARD EQUIPMENT Efficient air recovery and odor removal requires selection of proper Pur Air adsorbers for each application and problem involved. Standard units available to purify air and remove odors in practically any occupied space. CUSTOM DESIGN Custom design and fabricating service available for special requirements of abnormal odor problems, industrial solvent recovery, etc. Inquiries invited on any phase of air recovery, odor removal and air purification. Key personnel have security clearance for handling classified'military documents. 1323 Air Freek'ner Unit Fixed Mount Unit Air System Equipment paters Cambridge Filter Corporation 736 East Erie Boulevard--Syracuse 3, N. Y. Manufacturers of High-Efficiency Air Filters Offices in all Principal Cities CAMBRIDGE ABSOLUTE FILTERS A Series B Series This type of filter has been used for many years by the Atomic Energy Commission for the removal of radioactive particles and by many leading companies in the in dustrial field which have critical air cleaning problems. Removes essentially all smoke, dust, bacteria and mold spores. Every filter is individually tested with 0.3 micron smoke particles and has a guaranteed efficiency of 99.95 per cent. Initial Ap 1.0 in. w.g. at rated air flow. Long life-6,000 hours and longer when prefiltered-- provides economical owning and operating costs. Over 200 sq ft of filtering area ip a 1,000 cfm unit (24 in. x 24 in. x \V& in.). Filters are easily installed--No supporting frames. Provide positive, trouble-free cleaning. No costly shut downs. No product contamination. Filters in standard size units from 25 cfm to 1,250 cfm available for immediate shipment. Special size units upon request. A-Series--For Standard Ap plications. Asbestos bearing cellulose filter media, rubber base sealer. D-Series-- For High Humidity and Fire Resistant Applications. All glass filter media, rubber base sealer. Similar to A-Series in appearance. B-Series--For Fireproof Applica tions. All glass media, refractory sealer. Will withstand temperatures up to 1,000F. CAMBRIDGE AEROSOLVE FILTERS Cambridge Aerosdve A Model of a Bank of Filters A new, widely accepted, high efficiency, low pressure drop system of air filters designed for multi-filter banks in industrial and comfort ventilation and air condi tioning supply systems. Also used in filtration of exhaust gases. Filters consist of a permanant cadmium plated steel frame and interchangeable cartridges. Filter media used in the cartridges composed of special glass mats, available in efficiencies from 35 per cent to over 90 per cent, based on the Discoloration Test Method developed by the National Bureau of Standards. All tests employ normal atmospheric dust. This is the same test as used in rating Electrostatic Precipitators. Initial pressure drops range from 0.16 in. to 0.35 in. w.g. The greater-area and thickness of these specially designed mats provide long life, which together with a low initial cost guarantee economical owning and operating costs. Installation is easily made. Multi-filter banks quickly erected. Cartridges slide easily into frames and are held tightly in place by quick-acting fasteners. Operation is reliable and trouble-free. Protective screens and prefilters available if desired. 1,000 cfm unit 24 in. x 24 in. x 12 in. 1324 Air System Equipment patera CAREY Electron ic Engineering ComP<3,nH METAL WOOL itlUM'O'ltif# FILTERS 1875 CLIFTON AVENUE DIVISION itlUM'O ALtir0M w ww ^copper wool SPRINGFIELD, OHIO CONSTRUCTION The A-LUM-O-AIRE Filter is a perma nent-type, all-metal air filter designed for top economy and efficiency in all wann-air heating, air-conditioning and ventilating applications. In 90 per cent. of all installations, the A-LUM-O Aluminum Wool media catches and holds dirt--without the aid of oils and ad hesives. Rustproof and fireproof, the media can be quickly cleaned with water. Frames, with comers welded for extra support, are aluminized steel which combines the strength of steel with the protection of an aluminum surface. Mat retainers are heavy-gauge ex panded steel, plated after cutting to size. Media is securely locked in position to prevent slipping or moving. EFFICIENCY The Metal Wool Division of Carey Electronic Engineering Co. has devoted many years to the research and development of the uses and methods of pro ducing A-LUM-O Aluminum and Copper Wool. Hundreds of tests, under simulated operating conditions, have proved its unusually high efficiency as a filter media. Millions of tiny barbs provide an extremely rough surface which catches and holds even the most minute particles. Consisting of continuous strands with no short fibers, the wool is processed from special alloys produced to rigid specifications developed by Carey for this particular purpose. AVAILABILITY Furnished in all standard 1 and 2 in. sizes, A-LUM-O-AIRE Filters are also available in special sizes to order. Copper wool media with copper-plated mat retainers available for acid and corrosive conditions. Units can be loaded with proper media for specific operating requirements. Thousands in use in all phases of industry have proven the advantages of greater efficiency and economy in all types of installations. ENGINEERING Carey maintains one of the most modern engineering laboratories in the industry to aid you in solving your air filtration problems. The facilities for research, design and testing--plus the experience and assistance of competent personnel-- are entirely at your disposal. You are invited to submit specifications for complete recommendations. Above t a photomicrograph of aluminum wool show ing the countless rows of burrs and ridges which screen out dirt, dust and lint. In a standard 80 x SO * 8 filter there is an area of more than 69 sq ft of wool media-- tritA literally millions of barbs in each inch of filter surface. 1325 Air Filters Air System Equipment CONNOR ENGINEERING CORP. Danbury, Conn. /connor) Representatives in All Principal Cities ^tiorex* Air Recovery car recovery Air Purification In Canada: Douglas Engineering Co., Ltd., Montreal, P. Q. WHERE TO APPLY AIR RECOVERY Air Recovery is simply the conversion of foul or stale air to fresh air. It has been used to advantage wherever air is conditioned to enhance comfort, raise production efficiency, extend food preservation or protect product quality. Depending on the source of contamination, Dorex Air Recovery Equipment has been installed to remove odors and other gaseous impurities from intake air, from recirculated air or from exhaust air. When applied to recirculated air, Dorex Adsorbers reduce the amount of uncon ditioned outdoor air needed for ventila tion and effect savings in installation and operation costs. For example: Given an air conditioning requirement of an area of 20,000 cfm, of which it is assumed 14.000 cfm would be recirculated and 6.000 would be outdoor ventilation before installation of Air Recovery Equip ment, it may be possible to cut the amount of unconditioned outdoor air intake to 2,000 cfm by converting 4,000 cfm of used, already conditioned re circulated air to fresh air. Figured for average temperate zones, this 33% per . cent load reduction would lower the Fig. f- Dorex Canister installation and operating cost substan tially because each 1,000 cfm of heated or cooled air that is converted saves: (1) 100,000 Btu of installed heating ca pacity, (2) 2.6 tons of installed refriger ation, (3) 1,800 kw hours of current per cooling season, (4) 1,500 gallons of fuel oil or 9 tons of coal per heating season, and (5) incidental water consumption and maintenance. In existing systems, the application of Dorex Air Recovery Equipment will enable the system to serve a larger space or satisfy a greater conditioning load without increasing cooling or heating equipment and with-, out consuming more fuel or power. Fig. S. Typical Canister Arrange, ment--tide view Activated Carbon Traps Gases and Odors Activated carbon removes gases and odors by adsorption--a natural phe nomenon which takes place when air borne gases or vapors come in contact with it. An instantaneous condensation occurs and the condensed impurities are held tenaciously until the carbon is forced to give them up in reactivation. For air conditioning purposes, .however. 1326 Connor Engineering Corp. . Air Filters Atr System Eguipmeni cleaners Air Recover; the carbon must be especially processed, activated, and impregnated to meet the following specifications: (1) High ac tivity (adsorptive capacity) for a wide range of gases and vapors; (2) High retentivity over an entire range of normal operating conditions; (3) No retentivity for water vapor; (4) Extreme hardness to avoid dusting in handling and in service ; (5) High apparent density (in the granu lar form) of not less than 0.45j (6) Adapt ability to repeated reactivation without appreciable loss in activity or reten tivity. In actual use, Dorex activated carbon has removed and retained 95 per cent of all gaseous impurities from the air passed through it and maintained that efficiency from six months to two years, depending on the air contami nation. Equipment to Suit Individual Requirements Dorex Air Recovery Equipment is avail able in a range of types and sizes to suit individual requirements. Each type is designed to hold the correct amount of activated carbon in a manner to provide a maximum area for decontamination, a minimum of air resistance and uniform air flow through the carbon. The average resistance to air flow ranges only from 0.15 to 0.2 in. wg. TYPE H--Adaptable to Most Central Systems for Recovering the Freshness of Intake Air and Recirculated Air and for Eliminating Exhaust Nuisances Type H Equipment--for complete de contamination of all air passed through it--consists of removable, perforated, carbon-filled canisters which are mounted in multiple on one or more supporting manifold plates. Fig 1 shows a canister and its function; Fig 2 shows a typical arrangement of canisters as installed. The flexibility of this ar rangement makes Type H Equipment readily adaptable to a wide variety of space limitations. Write for Bulletin 10S-B. Fig. 4- Dorex G Panel TYPE C--Equipment for Recovering the Freshness of Recirculated Air. Dorex Type C Air Recovery Cells were developed to meet a need for a large capacity, easily handled and installed air purification unit. Each cell measures only 24 in. x 24 in. x 8% in. deep and completely purifies 1,000 cfm. They require no more engi neering than that required for ordinary dust filters and can be mounted right along with them in either flat or "V" arrangement. (Fig. 3) Write for Bulletin 117-C. TYPE G--for "Package" Conditioners, Unit Heaters, Refrigerated Spaces, Airplane, Bus, Railway Car, and Marine Installations and Other Systems Where Space is at a Premium. Write for Bulletin 106-C. These compact panels consist of sturdy metal frames, each housing a battery of exposed perforated metal tubes which contain the activated carbon. Standard units of one, two or three tube rows in depth are available in a range of stock sizes for arrangement in air ductB. (Fig 4) 1327 IQIITIIIEIITni 1647P. O. BOX Ait System Equipment ^ cleaners DIR FILTERS. Inc. IOUISVIUE l.KY. CONTINENTAL AUTOMATIC, SELF-CLEANING Air Fil ters, viscous impingement type; 91.3 per cent efficient, 0.28 W.G. resistance at 500 fpm (ASHVE method test). Features: Patented E-Z-Wash media, "Ferris Wheel" action of con tinuous rotating filter curtain, and positive automatic flush cleaning of curtain in each rotation cycle. Ferris Wheel action passes filter sections from front to rear curtain without reversing them to the direction of air-flow . . . thus eliminating problem of trapped dirt being blown into clean air stream. ... Cam action tilts and lowers each filter section while in oil reservoir so as to forcefully flush filter oil through the media counter to air-flow. . E-Z-WASH PATENTED MEDIA is a honeycomb of opposed V-eorrugated metal strips which provides exceptional efficiency with extremely low resistance and effective self-cleaning . . . because air passages are. relatively large and smooth-walled. Write for Bulletin No. SOl-D. CONTINENTAL E-Z-WASH UNIT FIL TERS, available in all standard di- ' mensions, 2 in. or 4 in. thick, use same advantageous patented media as dis cussed above. CajS be washed easily by brisk cold water hosing, and quickly re oiled with E-Z-Oil spray bomb. Write for Bulletin No. 401-A. DYCON CA-24, dry-type air filters have an excellent dust holding capacity because the efficient media is a blanket of specially prepared synthetic fibers. Low maintenance cost: quickly and easily restored to like-new efficiency by coldwater rinsing. No oil involved. Write for Bulletin No. B01-A. DYCON, Type DY, one-inch dry-type filter for domestic and commercial use, is available in a wide range of standard sizes, and custom sizes as well--for air-conditioners, warm air fur naces, and air-handling units. Write for Bulletin No. 5S0. GREASE FILTER, Type GW, uses same type media as E-ZWash filters, thus affords extremely low resistance. Since fatty acids of kitchen exhausts would be highly corrosive upon steel, Continental grease filters are made entirely of corro sion-resistant 3S aluminum. A sturdy permanent filter, type GW is easily washed in a commercial dishwasher. Write for Bulletin No. 700. 1328 Air System Equipment aAnirdFCillteearnsers Electro-air Cleaner Company 1285 Reedsdale St., Pittsburgh 33, Pa. Representatives in Principal Cities Electro-air Electronic Air Cleaners have been developed for ease of installation, maintenance-free operation, and high efficiency (90 per'cent by the National Bureau of Standards Dust-Spot Test). New features such as selenium rectifiers and a self adjusting, ballasted, single circuit are incorporated in the design of all Electro-air equipment. All parts, including selenium rectifiers are unconditionally guaranteed for two years. "Built-up Line" equipment is manufac tured in every capacity to handle all sizes of buildings. All units have alumi num frame-work and top and side panels. Washing systems can be of either the "fixed horizontal-manifold" type, or with a "traveling vertical manifold and adhesive applicator" operated by semi automatic or completely automatic con trols. "Built-up Line" units are also furnished with "enclosures" complete with drain pans and ft of ducts before and after the Electro-air. "Built-up-Line'' Eleclro-uir "Custom Line" units are furnished as complete "packages" and are designed for use in those cases where space is limited and access doors in ducts are not practical. These units are furnished in capacities from 1,350 to 12,000 cfm and are complete with required number of collecting cells, drain pans, washing sys tems, and power packs. "Custom Line" Electro-airs are furnished in either hori zontal or vertical ("up or down" air flow), and may be floor mounted or suspended. "Cuetom Line" ElectnMxir "Compact Line" Electro-airs are mod erately priced and are designed for easy installation in homes and smaller com mercial and industrial buildings which, have forced air ventilation. They are available in nine models, both horizontal and vertical (down) flow.,1 in capacities from 800 to 4,800 cfm. Horizontal flow % models may be either floor mounted or.". suspended. -"Compact Line" units in clude most of the features of larger "made-to-order" Electro-air models. 1329 "Compact Line" Electro-air Air System Equipment AanirdFCiltleearsners A Dodger Corporation 6 Centre Park Rochester 3, N. Y. Di-- Filters for Bnildlng Ventilation, Air Conditioning, Engine Intake, Pipelines and Many Other Special Applications. Representatives In Principal Cities STAYNEW MODEL A-3 AUTOMATIC FILTER An endless curtain type oil-bath filter for handling large volumes of heavily dust-laden air at low cost. The effi ciency of Staynew Model A-3 is out standing among mechanical self-clean ing filters. Operation and Features: Double filter curtains (1) carried on heavy roller chains driven by sprockets keyed to the shafts of the curtain rollers (2). These rollers float on ball bearings for quiet, frictionless operation. Curtains consist of removable panels (3) made of a single layer of bronze screen cloth to which are attached layers of woven copper mesh. The first of the curtains is the denser, having about twice the impingement surface of the second or rear curtain. This first curtain acts as the filter and travels through the oil reservoir. The second curtain does not enter the reservoir, but acts only as a safeguard against oil en trainment This design permits a direc- MoiA A_, Automatic FiU,, (nu,,,w fmlura tion 01 certain travel SUCH that Cleaned are referred to in accompanying description) . panels (4) are always on the filtered air side. Therefore no dust can be carried across the back or return side of the front curtain to be blown off and carried on by the flow of air. Patented, exclusive Staynew Compressed Air Curtain Cleaners (5) are available for special conditions. ' Specifications . Model A-3 Filters are sectional and may be bolted together to obtain any required capacity. Sections come in two widths, 4 ft 3 in. and 2 ft 9 in. Curtain drive and control mechanism (6) arranged either as an integral part of filter unit or for remote mounting, includes a % hp motor (7) driving through a reduction gear and a momen tary contact time switch (8) for testing and checking curtain travel and compressed air control. All are mounted on a common base plate (9) on clean air side of filter. Shear pin (10) is provided for protection of moving parts from accidental damage. Drive motor operates for a few seconds at 15 minute intervals, and compressed air curtain cleaners can be arranged to operate simultaneously. " 1330 Dollmger Corporation Air System Equipment Model WKE Panel and Frame STAYNEW PANEL TYPE FILTERS Model WKE: Diy-type finned panel filter for use in ventila tion and air conditioning -systems. Extremely large filtering area in relation to overall size. Adaptable to wide variety of filtering media--in fact, almost any medium obtainable in sheet form that can be crimped. Steel mesh on both sides of medium prevents sagging and makes the WKE fire-resistant (models available to meet Class I Fire Underwriters approval), and cleanable without possible damage from vacuum cleaning tool or cleaning nozzle. It may also be washed or dry cleaned when and if necessary. There are no cross bars, spacer bars, or other obstructions to interfere with the cleaning operation. Unaf fected by temperature changes. Filter cells are held in rigid box-type supporting frames of heavy gauge metal by spring-loaded cam-type locking latches. Two lifting handles are provided on each cell. Filtering me dium supplied already cnmped and cut to size. It may be in expensively replaced in 2 to 5 minutes right at the filter bank-- no special tools required. Frames are drilled so that they can be riveted together to form a flat bank, or by the addition of angle uprights into a "V" or staggered arrangement. Viscous Model DPV Panel and Frame Viscous Panel (Model DPV) : A permanent type panel for air conditioning systems used in heavy duty industrial service. Filtering media consist of a series of layers of crimped galvan ized screen cloth and woven mesh. These media when coated with PD-10 Pingene Filter Oil form an unusually efficient filter. Model DPV filters are cleaned easily with five steam or by washing in a suitable solvent. Spring-loaded locking latches and lifting handles are provided as in Model WKE. Both Model WKE ana DPV cells are furnished in 2 in. and 4 in. depths in various standard sizes. Electro-Staynew Electronic Filter: Ionizer and Collector Cell built into one compact unit. Highly efficient--removes 90 per cent of all air-borne dirt, including smoke, dust, pollen, oil mist. Available in single units of 1200 and 1800 cfm; any capac ity in multiple units. STAYNEW LIQUID FILTER ; ISOOcfm Elcctro-Staynew Precipitator Model ELS: Widely used for the filtration of cooling water to prevent clogging of spray nozzles. Exclusive) low-cost SLIP-ON INSERT easy to remove, clean, replace. Radial Fin Construction provides all possible filtering area in smallest possible space. Standard models available to handle up to 1000 gpm. ~ Mold els (oeefumcJ View) Representatives In Principal Cities Complete Information from Factory on request FILTERS FOR INTERNAL COMBUSTION ENGINES COMPRESSORS, PIPE LINES; ALSO DtfST COLLECTORS 1331 Air System Equipment raters Farr Company Manufacturing Engineers P.O. Box 45187, Airport Station Chicago Hew Orleans LOS Angeles 45, Calif. . Manufactured under license by Farr Co. Mfg. Ltd., Montreal, Canada New FAR-AIR1 FILTER AND HOLDING FRAME A high velocity, low resistance, viscous impingement unit for industrial and commercial applications. Available in a wide range of types and sizes for dirt, lint, grease, entrained water, ink, paint, etc. Herringbone-crimp media design assures higher performance, larger dirt holding capacity, lower pressure loss, easier cleanability and reduced main tenance costs. Standard interlocking holding frames are 16 gauge steel. Various protective coatings available. FAR-AIR CAPACITIES 1 Recommended net face velocity is guide in estimating FAR-AIR Filter 519 fpm although velocities up to 700 requirements. 4 in. filter thickness has fpm may be used. The following chart is a twice the pressure loss of the 2 in. NET FACE VEL. F.P.M. 346 390 433 476 519 563 606 650 PRESCAP. NOMINAL FILTER SIZE C.F.M. LOSS Per CLEAN Standard Stocked Filters Other Common Sizes Sq. In. In. HsO 1*&2* #44 16* x 20*| 16* x 25*i20" x 20"| 20* x 25* 10* x 20*| 16* x 16*|20* x 30*|25* x 30* FILTER CAPACITY CUBIC FEET PER MINUTE 2.40 0.06* : 625 795 - 800 1020 360 485 1235 1575 2.70 0.07*7 700 895 900 1145 405 550 1390 1775 3.00 0.09*3 780 995 1000 1275 450 610 1545 1970 3.30 0.10*. ' 860 1095 1100 1400 495 670 1700 2170 3.60 0.12* 935 1195 1200 1530 540 730 1855 2365 3.90 0.14* 1015 1290 1300 1655 585 790 2010 2560 4.20 0.16* 1090 1390 1400 1780 630 855 2165 2760 4.50 0.19* 1170 . 1490 1500 1910 680 915 2320 2960 4.80 0.21* 1250 1590 1600 2035 725 975 2475 3155 MEDIA DESIGNATION AND APPLICATION Type 44:14 mesh zinc-electroplated steel screen. For ventilation, paint, lint, ink, oil. Type 44F: Coated with vinyl or other special paint. For fume-resistant appli cations. Type 44G: Standard filter, unoiled. For grease arrestance. * Type 44MZ: Screen painted with zinc chromate before and after assembly. Frame hot dip galvanized. Marine venti lation application. Type C4C4H: All copper media and filter frame. Corrosive atmosphere and water elimination applications. . Type A4A4: All aluminum media and filter frame. Stainless steel and.monel filters for special applications can be Trade Mark Reg. supplied on special order. 1332 Farr Co. Air System Equipment Air Fitters HOW TO SPECIFY STANDARD TYPE 44 FILTERS & FRAMES Filter shall be permanent, impinge ment, washable, all metal, panel type.. Media shall be zinc electroplated, 14 mesh steel screen, arranged in alternate layers of flat and herringbone-crimped screens, so that at no point is air flow restricted to flow through the screen, 4 layers of each per inch, Jjj-in. rod rein forced, and enclosed in a frame of 16 gauge steel with flush mitered corners. Resistance to air flow of a clean filter shall not exceed 0.12 in. w. g. at 3.6 cfm per square inch of net face area. Holding frames shall be factory built on 16 gauge steel "T" section, with felt -air seal, interlocking edges, and filter locking device. Filters, shall be Far-Air Type. 44 and frames shall be Far-Air Standard Inter locking as manufactured by Farr Com pany, Los Angeles 45, California. ROTONAMIC SELF WASHING FILTERS ROTONAMIC The Rotonamic is a compact, multiple tube, cyclonic type air cleaner with continuous dirt removal by air bleed. Efficiency averages 98 percent on 5 to 10 micron dust of 2.5 specific gravity. Efficiency is even higher on larger parti cles or on denser material. Rating of 20 x 20 x in. panel is 1000 to 2000 cfm depending on available pressure. Ap parent straight through air flow requires no difficult change in duct direction. Bleed off piping is simple. Deflecting vanes form a high velocity vortex in each tube. Internal reversal of the direc tion of flow doubles the cyclonic action, producing the high efficiency. These completely automatic units wash and re-oil themselves on any frequency cycle desired. Each is made up from 4 in. thick corrosion-resistant filters in combination to meet any cfm require ment. Washing water and contami nated oil is immediately flushed away, eliminating messy sludge and oil sumps. There is no oil entrainment. Each unit has a safety deluge valve that auto matically prevents fire from passing the unit. Installation is simple ana inexpensive. . ENDLESS GREASE ELIMINATORS FAR-AIR Endless Grease Eliminators halt the deposit of highly combustible grease and lint in the air ducts, reduce maintenance, protect blower and fan, provide better ventilation and sanita tion. Available in one-sided and two sided models in sizes to meet any cfm requirement. Full catalog and technical informa tion on any FAR-AIR product is avail able on request. ' 1333 ' Air System Equipment Air cleaners The Goodyear Tire & Rubber Company/ Inc. .. Akron 16, Ohio PLIOTRON* AIR CLEANER WHAT IT IS PLIOTRON is a self-charging, electro static, washable, permanent-type air cleaner. Revolutionary feature is its new filter medium of shredded polyethylene. Sound engineering and construction in sure long life and minimum maintenance. HOW IT WORKS Shredded polyethylene carries inherent positive and negative charges in close proximity to each other. These charges are greatly increased with the passage of air. Since particles of dirt are simi larly charged, the meshed plastic does an effective job of attracting and capturing them. SPECIAL SHREDDING INCREASES . EFFICIENCY A special method of shredding produces a feathered edge with thousands of cilia like serrations. These increase the area exposed and create a'heavy turbulence that brings the dirt particles into inti mate association with the statically charged polyethylene. AVAILABILITY INFORMATION PLIOTRON is supplied through dis tributors located in every major market ing center across the country. It is presently available in four standard sizes, all 1 in. in thickness. It is so de-' signed as to stay in the general resistance range of ordinary, 2 in. thick, impinge ment filter, yet do a superior job of air cleaning. Spacer clips which are also available, or another PLIOTRON, are recommended in instances where a filter greater than 1 in. in thickness is required. SELF-CHARGING ELECTROSTATIC WASHABLE PERMANENT TYPE Filter Size Nominal 16 x 20 x 1 16 x 25 x 1 20 x 20 x 1 Net Face Velocity fpm Static Pres sure Drop Inches H,0 Actual 151 x 19 % x .938 Sq Ft (Net Area) 2.22 151^6 x 24 K x -938 2.78 19K x 19 H x .938 2.78 20 x 25 x 1 19K x 24 Kb x .938 3.47 Filter Capacity cfm . 200 0.08 300 0.15 375 0.22 450 0.30 500 0.36 600 0.48 445 665 830 1000 1110 1330 555 835 1040 1250 1390 1670 555 835 1040 1250 1390 1670 695 1040 1300 1560 1735 2080 PLIOTRON--T.M. The Goodyear Tire & Rubber Company, Akron, Ohio. NOTE: Additional standard sizes availablefrom stock are: JO x 10 x l, 10 % SO x 1 and 16 x SO x 1. Special sizesin 1 in. thickness available from factory. Contact your Distributor or write Goodyear, Pliolron Sales, Dept. 7iS, for prices and delivery. 1334 Air System Equipment Air Recmerr Charles E. Manning Co. 90 Clairton Blvd. Pittsburgh 36, Peuna. AIR PURIFICATION AIR RECOVERY SYSTEMS REFILLABLE ACTIVATED CARBON AIR RECOVERY CANISTER PERFORMANCE CHART C-4 CFM Pressure Loss* (Inches W. G.) 5 0.02 10 0.045 15 0375 20 0.11 25 0.15 30 03 35 035 40 032 * Resistance is overall TYPE "C"--CANISTER, a perforate metal cylinder filled with granular car ' bon (for 15 to 35 cfm each with recom mended maximum of 25 cfm). Made up of one perforate metal cylinder within another, with the side walls of the two forming an open area which is filled with granular activated carbon. The top is completely sealed with a cap that en closes both the inner and outer shell. Air flows through the cylindrical side wall and carbon bed, into the hollow center of the inner cylinder--then down through the opening punched manifold plate upon which it rests. The Canisters may be set on the mani fold plate in any arrangement that best suits the requirements and available space. Canisters and/or manifold plate can be furnished in stainless steel, brass or aluminum for special installations. NTT-AIR TYPE "A" AIR RECOVERY UNIT The Type "A" panel Air Recovery unit handles from 700 to a maximum of 1000 cfm. For use in removing odor and gaseous impurities where those concen trations are light to medium. The shape of the carbon bed offers a great exposed area to the air flow for maximum effi ciency. The carbon bed is formed by two parallel sheets of perforated metal, fashioned in a series of S-curves, com prising the surface through which the air flows. . Both types of equipment can be used in single or multiple units for required capacities. Complete technical date available in new bulletin 15-CX, 15-DX_ by writing the manufacturer. PERFORMANCE TABLE CFM 500 600 700 800 900 1000 1100 1200 1300 Static Pressure Lass* (Inches W.G.) V-Arrangement Flat 0.105 0.08 0.15 0.105 0.177 0.13 0.23 0.17 0.275 0.19 0.33 0.23 0377 036 03 0345 * Resistance is overall. 1335 Air System Equipment AanirdFCillteearnsers Owens-Coming Corporation Toledo 1, Ohio THE ALL-PURPOSE, REPLACEMENT-TYPE AIR FILTER Air flows freely through a Fiberglas Dust-Stop* Air Filter, yet virtually all dirt is trapped inside. Correctly sized fibers mean peak efficiency . . . minimum resistance. "Depth-load ing" extends filter life. . THE FILTER Dust-Stop Air Filters are impinge ment-type filters constructed of glass fibers which are non-absorptive, fire proof and will not shrink or , swell. Fibers are coated with a non-evaporating odorless adhesive which effectively traps dust, lint and pollen. Dust-Stops are replacement-type filters and should not be laundered. Uses--Dust-Stop Filters may be used at approach velocities up to 450 fpm with out impairment of their high efficiency characteristics blit with higher resist ances. Maximum permissible resist ance of filters is m. water gage. Resistances Resistance--inches, water gage 300 fpm 450 fpm 1 in. filter .080 .170 2 in. filter .135 .300 In cases where velocities approach 450 fpm, care should be taken to see that fan capacity is adequate to overcome increased resistances. Cfm Capacities--Rated capacities of standard 20 in. x 20 in. Dust-Stop Filters are 800 cfm at 300 fpm velocity and 1250 cfm at maximum permissible velocity of 450 fpm. DUST-STOP FILTER FRAMES Dust-Stop Filter Frames are designed for the convenience of the engineer in constructing filter banks. Metal frame is of universal style, suited to use in flat or "V" banks. Designed-in, self-lock ing device permits fast, economical assembly. Made to take 2 in. or 4 in. depth of standard 20 in. x 20 in. or 20 in. x 25 in. filters. Black painted or galva nized finish. Front, back and side angle uprights for V-bank assembly are also offered in 20 in. increments up to 160 in. length. ' DUST-STOP RESISTANCE INDICATOR The Dust-Stop Resistance Indicator acts as a guide to economical bank main tenance. With adjustable filter-change marker set at resistance level specified by engineer as point where filters should be changed, this indicator provides a guide to "when-to-change filters." InBures operation at rated capacity and efficiency. FIBERGLAS and DUST-STOP are trade-marks (Reg.U.S.Pat. OS.) of Owens-Coming Fiberglas Corpora tion for a variety of products made of or with fibers of glass. . 1336 Air System Equipment Air paters Pittsburgh Plate Glass Company FIBER GLASS DIVISION One Gateway Center Pittsburgh 22, Pennsylvania GLASS GjjjpjEB- Where clean air is a necessity for either residential, commercial or industrial appli cations specify GLASFLOSS filters. Products of the Pittsburgh Plate Glass Com pany, these filters are composed of extremely long and exceptionally fine glass fibers. Because of this fineness, they furnish a greater dust-collecting area and provide unusually complete filtering action. GLASFLOSS filters are available in three forms, to suit all filtering requirements: ^GLASFLOSS STANDARD AIR FILTER --Provides millions of fine, glass fibers scientifically bonded and treated with a special fire-resistant, dust-catching ad hesive, to trap and hold more dirt. This extends the life of the filter and makes it ideal for normal home heating and air conditioning equipment. GLASFLOSS I-S FILTER--To the long, fine glass fibers used in the STANDARD Air Filter a special strainer mat has been added. This means that the I-S filter is actually two filters in one. For industry, where clean air is essential, or in the meticulous home equipped with forced air heating, Glasfloss I-S provides new quality air filtering. A GLASFLOSS ROLL-PAK--For bulk users of air filters who are faced with the roblem of continuous replacement. The grlasfloss Roll-Pak provides substantial savings ... as high as 30 per cent. It offers quick replacement of filter media, and is available in rolls of 40 in. wide and 10 in. long and in in., 1 in. and 2 in. thicknesses, packed five rolls per carton, to suit every size commercial air filter. ACTUAL DIMENSIONS Height Thickness 1" Filter | 2" Filter TOLERANCES glasfloss STANDARD AIR FILTERS Special sizes available Nominal Sizes 2200"" x x 25" 20" 16" x 25" 16" x 20" 111005""" x x x 20" 20" 10" 2120"" x x 30*i" 22 M" x x 1" 1" 16" x 22*4" x 1" 7" 10" x x 23H' 12" x x H" \V Volume of Air Cleaned Plus 0.00* Minus H" 1000 CFM 800 CFM 800 CFM 640 CFM 600 CFM 400 CFM 200 CFM 735 CFM 890 CFM 715 CFM 330 CFM 240 CFM ll'Hi* 19M* 15`Mb' IS'Mb' , 14`Mb' 9`Ms' 9`Mb' 11`Ma* 19`Mb' 15`Mb' 6`Mb' 9`Mb' 24*4#" 19H" 24**4#' 19*4* 19**4#' 19**4*" 9**4#" 30M" 22*4*" 22*4" 23*4*" 11**4" Plus or Minus *4#' `Hz' `Mb' `Mb' `Mb' `Mb' `Mb' Mb' `Mb' `Mb' `Mb' Mb' Mb' J`Mb* 1`Mb' I`Mb' 1`Mb* I`Mb' 1`Mb' 1111'''`Mooobnnn*lllyyy Vf only H* only GLASFLOSS I-S AIR FILTERS 2200"" x x 26" 20" 16* x 25" 16" x 20" 15" x 20" ` 1000 CFM 800 CFM 800 CFM 640 CFM 600 CFM 19`Mb' 19H* 15`Mb' 15'Mb* 14`Me* 24*4*" 19H" 24`Mb' 19*4" 19`Ms* `Mb' Mb' `Mb' `Mb' `Mb' l`Me' 1`Mb* l'Me* l`M* 1`Mb* 1337 Air System Equipment Air Filters Research Products Corporation Madison 10, Wisconsin AIR FILTERS FOR HEATING AND VENTILATING Grease Filters for Kitchen Exhaust Systems--Paint Arrestor Pads RP AIR FILTERS Controlled turbulence design is pro vided in every RP filter. Scientifically staggered baffles cause thousands of sharp reversals of air flow in the filter. Media gradation, insures RP depth loading, an important longevity feature. Air borne particles are centrifuged REPLACEMENT "Snap-In"`Grid Air Filter Installation Showing Self. Seal Edge. . Fiber Self-Seal Air Filter The highly efficient, Boft, resilient, non-fracturing RP replacement media is held in a sturdy, refillable wire grid. Media pad is oversize and no channel is required or used on edge which provides the self-sealing feature. Used in domestic and commercial units and in central sys tem filter banks. Available in \ in., 1 in. and 2 in. thicknesses in standard and special sizes. Snap-In Grid Air Filter Designed for central system use of the inexpensive Fiber Self Seal Pad. Paint Arrestors Specially designed, inexpensive and efficient pad removes overspray from paint spray booth exhaust air. Snap-in grid retains pad in frame. against the baffles and are held by adhe sive in the air filter and by the viscous qualities of the particles, themselves, in the grease filter and paint arrestor appli cations. Constructed of slit and expanded ma terial, RP filters are uniform in con struction and performance. WASHABLE E Z Kleen-Air Filter The RP Alumaloy, E Z Kleen Air Filter is an economical selection for many ap plications. Like all RP washable air filters, this filter is extremely easy to clean. Industrial Air Filter RP Alumaloy Industrial air filters are multi-velocity filters, which have ex tremely low initial resistance and slow build-up resistance. Holding frames for filter banks, combination lift and lock handles, lift handles and water soluble filter coat adhesive are available. Grease Filter Efficiency in excess of 99 per cent on grease vapors, gleaming appearance, ease of cleaning ana light weight have made RP Alumaloy Grease Filters a volume performance leader in its field. A free comprehensive data booklet on kitchen exhaust systems is available. RP Alumaloy Air Filter and Inset Showing Handle Lock ADHESIVE Two types of adhesives are available. RP Filter Coat for removal of dust and other impurities--RP D-0 Kote which has the additional quality of odor removal. Both are for application to RP Alumaloy washable filters. APRILAtRE Automatic-Electric HUMIDIFIER Positive control by humidistat and high capacity are features of Aprilaire Humidifiers. Three models available: Plenum Model (illustrated) for installa tion in forced air furnaces; Universal Model, for installation in building with steam or hot water heat; Portable Model requiring no installation for any type home or office. 1338 . at m Air System Equipment m/ciSm Somers Corporation 6063 Wabash Ave., Detroit 8, Mich. Established 1925 REPRESENTATIVES IN PRINCIPAL CITIES SOMERS Heavy Duty Industrial Filter Patented Somers Hair Glass Filters provide everything required in an efficient air-cleaning system. FEATURES High rating for dust, soot and bacteria separation. Require no adhesive, coating or im pregnation. Indestructible in normal service. Minimum low-pressure drop. Odorless and non-absorptive. Fireproof. No periodic replacement. Washable. Permanent--Do not rot nor disinte grate. All welded zinc-plated 20 gauge steel frame. 100 hour salt spray test. Metal protection strip on apex. Glass cloth between hot-dipped hard ware cloth. Glass ribbon seal so air cannot short circuit. Refills. Somers Hair Glass Filters consist of a 20 gauge zinc plated frame holding galvanized wire cloth packed with hair-spun glass strands. The glass strands are flexible, do not break up and cannot be drawn into air stream. Hair Glass being chemically inert, has no facility of absorption; it cannot rust and lasts indefinitely in service. Water either hot or cold may be used to clean it, without impairing its efficiency. . t Available in all standard and special sizes. Quotations and further engineering data will be sent on request. Master holding frames available. ' .1339 Air System Equipment Air men TRION, INC. 1000 Island Avenue, McKees Rocks, Pa. In Metropolitan Pittsburgh Designers and manufacturers of equipment for cleaning and purifying air and other gases. TRION ELECTRONIC AIR CLEANERS '''C Highest efficiency air purification equipment. Electronically removes more than 90 per cent (National Bureau of Standards Dust-Spot Test using normal atmospheric air) of dust, dirt, smoke, pollen, germs and virus from air. All airborne particles are electronically charged (positive) as they enter the Trion. They are then attracted to and collected upon plates having an opposite electrical charge (negative). An in tegral washing system flushes the dirt to a sewer. Field Assembled: Built to specifications for required cfm and assembled on job. Custom-Built: Built to specifications up to 9330 cfm and shipped as a complete unit. Standard Packaged: Residential and small commercial units. Seven sizes up to 4,800 cfm. Shipped from stock. Special: Designed for specific requirements such as by-product recovery, gas purification, nuisance elimination. TRION OIL MIST PRECIPITATOR Electronically recovers coolant oil mist from high speed cutting and maching opera tions. Unit includes blower. TRION MECHANICAL AIR FILTER Inexpensive, viscous impingement air filtering equipment featuring high velocity, progressive loading, low pressure drop, high dirt holding capacity and non-clogging. Manufactured from wire screen or aluminum strip media with exclusive "air scoop" design. Fixed Panel: Permanent and cleanable panels for filtering larger particles of dirt, pollen and grease. Automatic self cleaning accessories available. Traveling Curtain: Advanced design automatic filters with con tinuous self cleaning features for large volumes of air where filtering of coarse particles is sufficient. 1340 Air System Equipment Air raters Vortox Company Claremont California Panel Air Filters for all Industrial Applications Vortox Panel Air Filters are of the cleanable, impingement, viscous-coated type with exceptionally low air flow resistance. They are made for use in air conditioning) ventilation, range canopies, engine intakes, and general air filtration. EFFICIENCY. Vortox Panel Air Filters are efficient at both high and low air flowB. Consequently to reduce costs of the original installation or to save space, fewer Vortox Filters may be used at higher air velocities. To assure a longer service life, more Vortox Filters may be used at lower velocities. In either case Vortox Panel Air Filters provide better cleaning at lower cost. Fitter with Frame OPERATION. Numerous changes in direction of dust laden air cause the dust particles to impinge on the adhe sive viscous-coated surfaces of the filter Vortox Type VR Panel Air Filter illus trated above is the type used on engine intakes and in car bodies of diesel loco motives. It is constructed to withstand the severe usage of locomotive service. It has the exceptional characteristics as in all types of Vortox Panel Air Filters. FILTER ELEMENT. Fabricated of elastic units of fine steel wire positively interlocked to provide a permanent filter, the element offers many advan tages: (1) In a 2 in. x 20 in. panel there are from 9300 to over 15,000 feet of fine steel wire, depending upon the type. (2) Even distribution of filaments ex poses innumerable viscous-coated sur faces to the air stream, thus obtaining the most effective cleaning for space occupied. (3) Proper spacing of fila ments prevents clogging and assures maximum dust removal efficiency. (4) Structural strength and permanent re silience combine to withstand "packing" effect of vibration and pulsation. element. Coarser particles collect near the entrance, while finer particles pene trate to a greater depth. As the entrance becomes saturated the cleaning action takes place deeper in the filter and the restriction is increased slightly. In creased restriction in certain sections of the filter diverts the air to cleaner sec tions, thus distributing the dust load for a higher over all efficiency and a greater total dust-holding capacity. EASY TO CLEAN. All dust and lint are easily and completely flushed from the filter by water or steam sprays. Nominal Size of Pane) Inches* 16 X 20 X 2 16 X 25 X 2 20 X 20 X 2 20 X 25 X 2 Actual Outside Dimensions Inches 15% X 19% X 1% 15H>X 24% X 1% 19% X 19% X 1% 19% X 24% X 1% Capacity Range In CFM** 640 to 950 800 to 1200 800 to 1200 1000 to 1550 Outside Dimensions Of Holding Frames Inches 16% X 20% X 2 16% X 25% X 2 20% X 20% X 2 20% X 25% X 2 * These filters are also made in 4-in. thickness. ... .... ,, . . . ... . , Some filter manufacturers specify very high velocities which are applied to certain internal dimensions of the filter. The range of capacities stated above are computed on the basis of average to high velocities ap plied to the total niter area Mfffog the actual outside d*TMwnginT<H of Vortox Panel Air r titers. 1341 Air System Equipment Air cleaners Westinghouse.--Electric Corporation Slurlevanl Division Heating, Ventilating, Dust Control and Fume Removal Equipment, Electronic Air Cleaners, Mechanical Draft Equipment Hyde Park - Offices in Principal Cities BoStOII 36, ^ESS> ELECTRONIC AIR CLEANING PRECIPITRON high efficiency elec tronic cleaners save money by removing harmful dust and dirt from ventilating air. ...In commercial buildings PRECIPI TRON catches dirt and grime before it settles on walls, merchandise, light fix tures and equipment. In industrial plants PRECIPITRON protects valuable equipment, and improves working con ditions. . . Oil Mist Control Unit Oil Mist Control Units . Designed to collect oil coolant mists generated by high-speed cutting, grind ing operations. Have built-in fan for individual machine ventilation. Avail able in 600 and 1200 cfm capacities. Encased Precipitron Horizontal Airflow Horizontal and Vertical Air Flow Manual wash type for installation in ducts. Sizes range from 1200 to 100,000 cfm for operation at 90 per cent efficiency by Blackness Test. Units easily main tained by manual washing. Uses 115 volts single phase power--only 40 watts per 1000 cfm. . Push-Button washing type; washes and applies adhesive with a built-in motorized moving nozzle washing mech anism operated by remote control. Allows operator to service the unit quickly and economically from outside the duct. Sizes from 5000 to 72,000 cfm. Commercial Precipitron With 44Push-Button" Wash Automatic Washing type for large, heavy duty applications. Washes and applies adhesive automatically without interrupting the air flow. Mobile washer boxes isolate small section of unit for complete servicing. Capacities from 24,000 cfm up. . Vertical Unit for up or down, air flow --manual washing. Suited to small and medium size installations where space is at a premium. Capacities 1200 to 9600 cfm. 1342 Commercial Vertical Airflow Unit Air System Equipment llow^rnffuSS Air Fan Engineering Company 7401 Telegraph Rd., Los Angeles 22, Calif., U. S. A. (Telephone RAymond 3-3354) AIRFAN AIR WASHER EVAPORATOR . COOLER The Airfan Air Washer Evaporator Cooler has high cooling efficiency and is next in line to mechanical refrigera tion, yet low in cost. Units available from 2,000 cfm to 100,000 cfm. Xtjr.'M UTILITY SETS For general ventilation complete with weather-proof covers. Self contained package units for easy installation. 300 cfm to 20;000 cfm. Wheel diameters 10 inch to 36 inch. ROUND DIFFUSER Precise control of air delivery and radius of diffusion with Airfan round ceiling diffusers. Nine sizes, 8 inch to 36 inch. Outlets from 200 cfm to 15,500 cfm. AIRFAN H-D BLOWER Airfan builds a complete line of forward and backward heavy duty blowers, rotat able discharge housing and extended streamlined air inlets for quiet operation and low horsepower. Capacities range from 600 cfm to 100,000 cfm. SQUARE DIFFUSER Also 2-way, 3-way and 4-way square and rectangular ceiling outlets. From 400 cfm to 20,000 cfm capacity. Technical Data Catalogs on all Airfan Products are available upon request to building contractors, engineers and dealers. 1343 Air System Equipment 5!!55i Binks Manufacturing Company 3130-36 Carroll Ave., Chicago 12, 111. Representatives In all principal cities Water cooling systems and nozzles__ a size and type for every purpose Binks atmospheric spray cooling towers Small sizes, in a variety of standard units with capacities ranging from 10 to 125 gpm--larger units handle from 600 to 1200 gpm. Special designs furnished in sizes of exceptionally large capacity. Standard tower capacity and tempera ture performance are based on nozzle pressure of 7 lbs per sq in. Ask for Bulletin SIS Atmospheric cooling towers. Type i I Binks blower type induced draft cooling towers The squirrel cage blower provides ex tremely quiet operation. Available in single or multiple types, capacity range from 9 to 800 gpm' of cooling water. Ask for Bulletin 177. Blower type towers, Type "BB" Binks steel cased induced draft cooling towers Towers of this type are of the spray filled or deck filled type--made in 20 standard sizes of sq ft rated area. Larger models are engineered to specification. Air propulsion assemblies for either type can be arranged for V-belt or reduction gear drive, as required. Ask for Bulletin SSS Induced draft towers, Types "S-K-S", *'S-K-W" }fi -m Binks Induced draft masonry cooling towers Engineered for large scale air condition ing systems in towers that harmonize with the architectural features of the building. Spray or deck filled. Ask for Bulletin SSS 1344 Vr Binks Manufacturing Co. Air System Equipment TowSf Binks non-clogging Rotojet spray nozzles . Non-clogging Rotojet nozzles are the heart of every Binks water cooling system. They account largely for the efficiency and satisfactory operation of Binks water cooling installations. In addition to cooling tower applications, Binks Rotojet nozzles have found a wide number of uses in brine-spray and quick-freeze refrigerat ing systems, air washing equipment, metal cleaning and treating machines, chemical plants, etc. Rotojets produce a uniformly fine fluid breakup in a hollow cone pat tern. Standard small and medium Rotojet nozzles are machined from brass bar stock, but can be made on special order from monel, stainless steel, or other machin able metals. Large, heavy-duty Rotojet nozzles for use in large cooling towers and spray pond installations, are cast from high quality brass with precision machined threads and orifices. These nozzles may be cast in other metals for special purposes. Binks small and medium capacity Rotojet nozzles To fit ) to % in. pipe connections. Regularly supplied in brass, with male or female threads, as specified. Discharge orifices are available over a considerable range for each size. Roto jet nozzles of this type are designed on the side inlet whirl chamber principle, which produces a fine fluid breakup and a uniform spray pattern. Binks heavy-duty Rotojet nozzles To fit 1 to 2V2 in. pipe connections. Female threads only. Discharge orifices available in various sizes, from Ye in. to U%6 in- The totally unobstructed involute type of whirl chamber produces a uniformly fine water breakup at low pres sures (5 to 7 lbs). Binks Spra-Rite nozzles . Produce a solid mass cone spray pattern. Small sizes for 34 to Yi in. connections are widely used for air washing, cooling, brine refrigeration, rapid evaporation processes, filtering sys tems, chemicals, etc. Binks large capacity Spra-Rite nozzles To fit 1 to 3 in. connections meet a variety of heavy-duty uses in blast furnace gas washers, vibrating and revolving screen coal and gravel washers and water cooling. Binks pneumatic atomizing nozzles Series 50 nozzles are designed for use wherever conditions of controlled humidity must be maintained, as in the storage of perishable products, paper storage and printing plants, textile mills, greenhouses, etc. Nozzles of all brass construction deliver round or flat spray and are designed for use with auto matic siphon or pressure feed installations. Free technical bulletin and engineering service Binks 40 page Bulletin No. 5600 contains a wealth of useful in formation for anyone specifying spray nozzles for air condi tioning, refrigeration, humidifying, heating and ventilating, or similar heat transfer processes. Nozzles shown above and all other nozzles in Binks line are illustrated and described. Data given include nozzle dimensions, capacities and spray angles. Cutaway drawings explain nozzle operation in many cases. "Blue print" drawings show installation details for heating and cooling uses where this information is required. Write for a free copy without obligation. Binks engineering service in planning and installing cooling systems is available without obligation or cost to architects, heating and ventilating engineers and builders. . . 1345 Air System Equipment Baltimore Aircoil Company, Inc. 2615 Mathews Street Baltimore 18, Maryland Manufacturers of Evaporative Condensers and Cooling Towers B. A. C. Evaporative Condensers and Cooling Towers are rigidly built for long, trouble-free service. Casings are of galvanized steel construction throughout. Gal vanized steel Cooling Tower surface is designed for long and efficient operation. The above basic construction is further protected against corrosion by the use of B. A. C. Zinc-Chromatized Aluminum Paint and Special B. A. C. Mastic. These finishes have proven through years of research and field testing to be outstanding in corrosion resisting and long wearing properties. Model "MC" Model "MC" Evaporative Condenser: (Pat. Pending) Centrifugal fan type . . . indoor or outdoor installation . . . Freon or Ammonia . . . Capacities: up to 350 TR. Model "MT" Cooling Tower: (Pat. Pending) Centrifugal fan type ... in-, door or outdoor installation . . . Capaci ties : up to 400 TR. Model "U" Evaporative Condenser: Centrifugal fan type. . .indoor or out door installation. . .Freon or Ammonia.. Capacities: up to 100 TR. Model "Mr- Model "UT-1" Cooling Tower: Centrifu gal fan type. . .indoor or outdoor in stallation. Capacities: up to 100 TR. Model "UL" Evaporative Condenser: Centrifugal fan type. . .indoor or out door installation. . .Freon or Ammonia. Capacities: 105 to 300 TR. Model''VT" Model '' UL" Model "LT-1" Cooling Tower: Centrifu gal fan type . . . indoor or outdoor in stallation. Capacities: 115 to 240 TR. 1346 Model "LT-l" Air System Equipment cooiin* Towers FLUOR PRODUCTS COMPANY A Division of The Fluor Corporation, Ltd. 12000 East Washington Boulevard, Whittier, California Manufacturers of Counterflo Mechanical Draft Cooling Towers--Aerator Natural Draft Cooling Towers SALES OFFICES and REPRESENTATIVES in: Birmingham, Boston, Buffalo, Chicago, Denver, Detroit, Houston, Los Angeles, Minneapolis, New York, Philadelphia, Pittsburgh, San Fran cisco, Tulsa. ASSOCIATES: Fluor Corporation of Canada, Ltd., Toronto, Calgary, Head-Wrightson Processes, Ltd., London, England Thirty-four years of intensive develop ment work in research, design, fabrica tion and erection of cooling towers enable Fluor to offer both natural draft and mechanical draft cooling towers with guaranteed performance, quality con struction, and long-life service. COUNTERFLO MECHANICAL DRAFT . COOLING TOWERS DESIGN: Counter-flow principle of de sign which enables the greatest possible utilization of available driving force for cooling. Available in a variety of distri bution systems, tower heights, and ar rangements. Exterior appearance de signed to complement modern plants and buildings. PERFORMANCE: Efficient counter-flow principle provides economy cooling for all services. Costsstudies made on individual design conditions dictate the type of tower to be offered from the many available designs. MAINTENANCE: Decking withstands repeated washing and cleaning and the abuse of removing and replacing. Enclosed distribution system eliminates algae growth. Stainless steel fan blades support a man's weight at their tips. Heavy-duty, precision gear units are designed specifically for the conditions peculiar to cooling tower operation. MANUFACTURE: Completely prefabricated. Tower structure based on 4 in. x 4 in. members with fan and gear supported on structural beams. Two-inch redwood in fan deck and stack. Internal gusset plate and bolt-type structural joints take both tension and compression loads. Over 250 tower sizes and combinations are furnished from only 258 prefabricated parts-to enable fast delivery and erection. FLUOR COOLING TOWERS FOR AIR-CONDITIONINGREFRIGERATION SERVICE The new FLUOR SERIES L.H. is a small, compact cooling tower designed ex pressly for the air-conditioning and re frigeration industries. The height of the top deck above basin is less than eleven feet on all models. This low height is ac complished by the use of extended sur face packing, and the advantages of counter-flow cooling are maintained. Construction is normally of Select Heart and Clear All Heart redwood with sheathing of double-walled redwood or inner redwood with asbestos cement board outer. Ten different models are available ranging from 150 to 1500 ons of refrigeration. This "package unit" meets the same high standards of performance, quality of construction, pre fabrication and long-life serviceljthat are embodied in the larger Fluor Counterflo Towers. Write for Details. 1347 Air System Equipment Cooling Towers E. D. Goodfellow Co., Inc. Memphis, Tennessee COOLING TOWERS GOOD-FELLOW RS Series: This series is suitable for residential application. Their compact size and extremely quiet operation make them suitable for this type of application. They are shipped completely assembled with lifetime lub ricated, totally enclosed motor. Bulletin Pf'56-1. GOOD-FELLOW PF Series: These mod els are manufactured in tonnage from 8 to 100 TR. All sizes of this series are de signed to withstand a wind pressure of 30 lb per sq ft. Large diameter, slow speed fans produce efficiency and quiet opera tion. Bulletin PF56-1. Select Redwood fill is used in both the RS and P series. Salt and acid resistant mastic coating spray applied to the in terior assures complete corrosion re sistance. Normally shipped completely assembled, they can be separated for ease of installation and rigging. The PF series conform to Military Spe cification MIL-T-16278B for Type 2, Style 2, induced draft cooling towers. GOOD-FELLOW CF Series: These mod els are produced in capacities from 2 to 100 TR. They are available with our standard corrosion resistant finishes or hot-dipped galvanized (after fabrica tion). Standard units have double air inlet and vertical discharge. Front or rear horizontal discharge and/or front or rear air inlet are available on order. This series is available with pump and motor mounted for uni-drive operation or with fan motor only, or with separate arrange ment for close-coupled pump mounting. These models are leakproof. Models 15 tons and larger are constructed in three sections to facilitate erection and in stallation. They are normally shipped completely assembled. The CF series conform to Military Specification MIL-T-16278B for Type 2, Style 1, or Style 2, induced draft cooling towers. We believe the CF series is one of the most versatile types of cooling tower available. Bulletin CF66-1. 1348 CF Series Air System Equipment Havens Structural Steel Company 1713 Crystal Avenue Kansas City, Missouri (Havens HAVENS TESTING TOWER . . . This 80-ft testing laboratory is shown accurately measuring air quantity, water quantity and temperatures of a 50-ton Havens Cooling Tower for exacting tower performance. All Havens Towers are given this same rigid test, and a certified guarantee covers all phases of performances. HAVENS 2 TO 10 TON WRAPAROUND . . . A small, economical tower that is ideal for light industrial and home use. Complete, lightweight and constructed for rugged service, it is furnished with combination motor cover and belt guard as are all Havens Towers. Lined inside and out with new HAVENS-COAT, it is guaranteed to withstand the corrosive effects of weather, salt air, water and chemicals. HAVENS S TO 60 TON KNOCK-DOWN . . . Shipped assembled, this tower may be disassembled in a matter of minutes for installation in inacessible places. De signed for medium size installations, it is constructed of heavy gauge steel sheets and select all heart California redwood and is, of course, lined inside and out with HAVENS-COAT. HAVENS 60 TO 200 TON ... A heavy duty tower in a completely new design that does a tremendous job for large in stallations. A unique bearing design cuts maintenance time and costs. The rugged construction of this tower plus HA VENS-COAT means years of lasting service. ALL HAVENS COOLING TOWERS are available with erection yokes at no extra charge for rapid one-piece installation." WRITE FOR FREE BOOKLET GIVING COMPLETE DETAILS ON ALL HAVENS TOWERS 1349 Air System Equipment Tow'S! Halstead & Mitchell Bessemer Bldg., Pittsburgh 22, Pa. Plant: Zellenople, Pa. One of the world's largest manufacturers of Counter-Flow, Water.Cooled Condensors HALSTEAD & MITCHELL COOLING TOWERS The Halstead & Mitchell cooling tower This economy of operation is one con saves and re-uses over 95 per cent of the . sideration. Waste of water is a second-. cooling water used in an'air-conditioning With water tables falling throughout andjirefrigeration system. It does this the country, many municipalities now byjsaving.the thousands of gallons of prohibit wasting air conditioning cooling water which would normally be wasted to water, and Halstead & Mitchell cooling the sewer each month by the conven towers meet all local specifications in tional condensing system. areas where their use is mandatory. H & M COMMERCIAL-INDUSTRIAL COOLING TOWERS Halstead & Mitchell's WT and CT cooling towers are designed in a range of sizes from 5 to 60 tons specifically for industrial and commercial applications. Halstead & Mitchell makes cabinets of both 10-gauge and 14-gauge steel as a part of its regularly scheduled production, and all of these units are pro tected by the 20-Year Guarantee on the wetted deck surface against rotting or fungus attack. The Protected Steel concept also adds many vital years of life. , H & M RESIDENTIAL COOLING TOWER The Halstead & Mitchell Type RE residential cooling tower is for home use. This H & M tower incorporates major features found in larger cooling towers. H & M residential cooling towers are protected by the 20-Year Guarantee on the wetted deck surface against rotting or fungus attack. Deep pitch, 4-bladed fans insure quiet, efficient operation. The steel is specially protected, and fans are made of stainless steel. Capacities are 2 through 7J4 tons. H & M TAKE-APART COOLING TOWER This cooling tower can be taken apart for installation in diffi cult places, and can be moved easily to roof tops without the expense of riggers, or down narrow stair wells for basement installations. The K-Series of Halstead & Mitchell take-apart cooling towers is specifically designed for this feature. All of the important long life advantages have been built into the Take-Aparts. Capacities are 5 through 60 tons. H & M CENTRIFUGAL COOLING TOWER Halstead & Mitchell's centrifugal fan cooling tower for home, hospital and other quiet applications can be relied on to meet the most stringent municipal decibel codes. These Type KB towers feature the 20-Year Guarantee on the wetted deck sur face against rotting or fungus attack, as well as the Protected Steel concept which adds many years of life. They may be in stalled both indoors and out and are also of the Take-Apart design. Centrifugal fans are for duct-work installation. Caphcilies are 5 through SB tons. 1350 Halstead & Mitchell Air System Equipment tot!5! H & M COOLING TOWER CONSTRUCTION DETAILS 20-YEAR GUARANTEE! ON THE WETTED DECK SURFACE against rotting or against damage due to fungus attack WETTED DECK SURFACE Halstead & -Mitchell's use of Koppers Pressure-Creosoted wood makes pos sible a 20-Year Guarantee on the wetted deck surface against rotting or damage due to fungus attack. MOTOR Special weather and splash-proof, suit able for operating exposed under all weather conditions. Weather shield for motor pulley and belt on all except residential cooling towers permits opera tion even tinder icing conditions. HOUSING Halstead & Mitchell offers electrically welded sheet-steel cabinets of both 10-gauge and 14-gauge steel. The Pro tected Steel concept controls rusting with hydraulically applied coatings of Vinsynite, Vinyl Zinc Und chlorinated rubber. Cutaway View, H & M Commercial Cooling Tower DRIVE Drive shaft is stainless steel. Fan bear ings are . . . ball bearing . . . perma nently grease sealed and lubricated . . . and protected against water drift. Belt tension is adjustable. RE tower motors are totally enclosed and thoroughly pro tected against moisture, fans being direct driven. FANS WATER DISTRIBUTION Efficient gravity-type distributing pan eliminates extra pumping head required Deep-pitch, stainless steel, 4-blade fans. Type KB units use centrifugal fans for ultra-quiet operation. on spray type towers, and cuts down windage losses due to atomizing of water. The sump level is continuously and automatically controlled by float. (Note: Pumping bead due to tower is represented by height of tower.) COMPLETE ASSEMBLY For installation in cramped quarters, towers with sectional housings are avail able. All towers easily accessible for cleaning through inlet in back. 1351 Water Air System Equipment Treatment Heller Laboratories, Inc. 124 Fort Lee Road, Leonia, N. J. SPECIALISTS IN WATER TREATMENT ` Equipment, Chemicals and Service for Control of Scale, Corrosion, Algae and Slime Agents in Principal Cities Heller Laboratories furnishes water. treating equipment, analysis service and chemicals for treatment of any cooling water application, large or smtjl. Heller Laboratories' chemicals are tailored to suit individual requirements determined after operating surveys and water anal yses are made. Heller Laboratories furnishes treatment control equipment as listed below. H YDROTROL for accurate concentration control and chemical Seeding. HYDROTROL maintains a desired fixed range of mineral concentration and feeds chemicals in proportion to requirements. HYDROTROL assures good treatment results and saves chemicals and water which are normally wasted when the usual fixed bleed-off method is used to reduce excessive mineral concentration. Excessive mineral concentration is caused by adding natural minerals, con tained in the fresh makeup water, but losing only pure water vapor from the system on evaporation. When mineral concentrations build up too high scale may form. When concentrations are too low corrosion may take place and treat ment chemicals are wasted with the bleed-off. Fixed bleed-off obtained by the usual float valve and overflow arrangement cannot maintain a fixed range of mineral concentration because the evaporation load in a cooling system is not fixed. HYDROTROL does maintain a fixed range of mineral concentration and con trols bleed-off and chemical feed in pro portion to evaporation by means of dif ferential level regulation. HYDROTROL works as follows: When a predetermined, fixed, adjustable amount of water is evaporated a fixed adjustable amount of water is bled off, then a fixed adjustable amount of chemical is added while the fresh water is added back to the full operating level. HYDROTROL is entirely automatic and can maintain accurately a concen tration as high as 50 cycles when wind age loss is negligible. HYDROTROL units are available from stock in three sizes: For systems up to 25 ton, 50 ton and 100 ton. Larger sizes are available on order. HYDROTRON is a patented process and equipment used to apply an electro physical treatment to control mineral scale formation. It is used for cooling systems working under difficult operat ing conditions where chemicals or soften ing are not practical or too costly for control of scale formation. Water is treated electro-physically in the HYDROTRON unit by subjecting the water to a closely controlled and proper range of voltage while the water is brought into intimate contact with a special electrode. This treatment brings about a change in nucleation and crystal habit so that after treatment, when sat uration is reached, hardness minerals are precipitated as a fine soft sludge instead of a cement-like coating on heat ex-, change surfaces. The sludge formed is removed by normal blowdown or flushing. Hydrotronfor Scale Control The HYDROTRON Process is appli cable for treatment of water for use in cooling systems, boilers, condensers, hot water generators and many other types of heat exchange equipment where scale forms due to concentration of hardness . minerals. HYDROTRON equipment requires very little attention or maintenance, gives life time service and saves the cost of chemicals used for scale control. HYDROTRONS are available from stock in sizes to treat up to 10,000 gph, larger sizes are available on order. 1352 Air System Equipment Cooling Towers Lilie-Hoffmann Cooling Towers, Inc. Exclusive Builders of Cooling Towers Since 189S 1450 So. Vandcventer Ave., St Louis 10, Mo. Two Modern Plants--St. Louis, Mo., and Plainview, Texas INDUCED DRAFT TOWERS New type filling reduces static pressure. Filling consists of slats, assembled in grids. Slat arrangement insures maximum wetted surface, minimum pressure drop of air flowing through tower packing, and uniform distribution of water and air over the entire effective area within the tower. Gravity distribution system requires only one riser pipe. Teco timber connectors develop 100 per cent working stress of members. Normally constructed of selected California redwood. All fans furnished by LilieHoffmann are P.F.M.A. tested and certified. ATMOSPHERIC SPRAY TYPE Generally offered in capacities up to 3000 gpm. Distribution by galvanized pipe header with smaller lateral arms, equipped with non-clogging spray noz zles. Water atomized as finely as possi ble. Sides and ends of towers equipped with narrow louvres, which fit into mast slots--no nails required. Recommended where cost is prime factor; and close approach to wet bulb is unnecessary. HORIZONTAL DRAFT (Package Type) Designed specifically for 4 to 100 ton refrigeration installations. Structure and basin of California Redwood. Sides of corrugated and flat cement .asbestos sheets with stainless steel trim; no paint ing required. Distribution of splash gray *fy type, non-sag, non-warp removable filling. 1353 Air System Equipment cooling Towers The Marley Company 222 W. Gregory, Kansas City 14, Missouri Representatives in All Principal Cities (Consult Classified Phone Director?) Water Cooling Towers of All Types and Capacities. MARLEY DOUBLE-FLOW AQUATOWER . . . Series 8 and 12 of this "low silhouette", low pumping head cooling tower fill every intermediate capacity cooling requirement for air conditioning and refrigeration. They combine the efficiency of Marley Double-Flow design with the simplicity of Marley Aquatowers. Mechanical equipment has been field proved in thousands of Marley industrial installations. Available with either wood or steel structure for easy job erection, for either single or multi-cell installations. Write for Bulletin DFA-56. 5v, & MARLEY AQUATOWER . . . Available in a complete range of 11 sizes, rated for servicing from 3 to 60-tons of air condi tioning or refrigeration. Thousands of steel packaged units have proved themselves in years of maintenance-free opera tion. They are stocked by dealers throughout the country--are shipped completely assembled and require no field construc tion. Large units may be readily disassembled for easy hand ling. Write for Bulletin AQ-56. MARLEY FORCED-DRAFT WOOD AQUATOWER . . . This new series of cooling towers, specifically designed to combat corrosive atmosphere and water, is produced in 10 models for services of 3 to 50 tons. It utilizes the forced-draft, cross-flow and vertical discharge principles. Because air discharge is vertical, these towers are applicable to many restricted loca tions. Tower structure is all redwood with heavy asbestos ce ment board or wood casing; fan and mechanical equipment are located out of hot, humid air stream. Small models are factory assembled; larger models are shipped disassembled. Write for Bulletin WAQ-56. .un MARLEY SPRATOWERS . . . These heart quality redwood cooling towers are available in two series, one designed primar ily for air conditioning and refrigeration applications up to 50 tons and a series of larger towers which are built in standard ized units for larger capacities and are also available with at mospheric sections for cooling of jacket water, oils and gases. Write for Bulletin ST-56. 1 MARLEY COUNTER-FLOW SERIES, STEEL AND WOOD... ji This series of Marley counterflow cooling towers is designed jj especially for heavy duty air conditioning and refrigeration service wherever appearance is important. The all-steel ea model (with the exception of corrugated asbestos cement board Jp casing) is designed to meet fire codes in all metropolitan areas. Both the steel and wood models blend well with modern architecture. May be installed with any combination of lou\,i vered walls open providing unusual flexibility and maximum t utilization of usable space. Write for Bulletins CS-56and CW-56. MARLEY CROSS-FLOW .. . For large capacity industrial cooling, Marley offers 3 towers that utilize the patented Marley Cross-Flow principle--The Double-Flow, Twin-Flow and Single-Flow. Write for Bulletin CF-56. 1354 Air System Equipment Cooling Towers, Unit Coolers Mario Coil Co. 6135 Manchester Ave., St. Louis 10, Mo. Manufacturers MARLO = HEAflV line. 199s | RAMSFER Equipment Industrial Coolers--Unit Coolers--Evaporative Condensers--Low Temperature Units-- Air Conditioning Units--Heating and Cooling Coils--Cooling Towers--Diesel Engine and Oil Evaporative Coolers. COOLING TOWERS--industrial and commercial--20-100 tons--induced draft, wetted deck surface, water spray--out door-indoor. "THR.IFTI-TOWER."-- smaller adaptation for residential, light commercial use--2-16 tons. Write for Bulletins 406, 6154 CEILING TYPE AIR CONDITIONING UNITS--cooling, heating, dehumidifying, humidifying. 14 sizes--1 to 175 tons --480 to 37,'200 cfm. Ceiling suspended, floor types. Write for Bulletin S055. INDUSTRIAL COOLERS--15 unit sizes --1,000 to 26,400 cfm--blow-through and pull-through type. Write for Bulletin 412, Section 40, pp. 1-6. REMOTE RO9M AHt CONDITIONING UNITS--permit individual climate selec tion. No ductwork, only simple piping needed. Floor and ceiling type units. Write for Bulletin SS56. BLAST COILS--air conditioning, indus trial refrigeration, heating. Any mate rial--all refrigerants--every application. Pressure-expanded staggered tubes, con tinuous plate-type fins. Write for Bulle tins 396-A, 495. MULTI-ZONE UNIT--complete winter and summer functions--individual zone control--1,300 to 37,000 cfm. Write for Bulletin 3155. Multi-Zone Unii Ceiling Type Air Conditioners^ Air System Equipment xSwm -$ w 220 Dupont St., Brooklyn 22, N. Y. Phillips Standard Induced Draft Conterflow cooling towers are designed in Steel and Corrugated Transite, Redwood and Corrugated.Transite, or all Redwood in sizes from 150 tons upward. Transite Siding is attached to tower frame by use of Stainless Steel fastenings to prevent staining or deterioration. All steel in Standard Towers is hot dipped galvanized after fabrication. All California Redwood is of Select Heart grade. The slip-fit fill construction and box type drift elimina tors are extremely efficient and produce maximum cooling with minimum water loss. Fans are of Stainless Steel or Cast Aluminum with low tip speed to reduce sound level to a minimum. Right angle worm gear drives having tapered roller bearings and forced feed lubrication are used to assure long trouble-free life. Weatherproof motors of standard makes are supplied on all models. Bulletins PC-211 or 212. Phillips Standard Induced Draft Counlerftow Phillips Special Steel and Transite, or Redwood and Transite, Induced Draft or Forced Draft Counterflow Cooling Towers are engineered and designed to suit building conditions. The exteriors may be of Flat Transite with ornamental trim, or of Corrugated Transite with no trim. Either the Flat or Corrugated Transite presents a clean exterior which will remain watertight and will not dis color. Fill, drift eliminators, fans, gears and motors used in the Special Cooling Towers are the same as those described for Standard Cooling Towers. Phillips Special Steel 4 Transite Phillips Special Steel and Transite Phillips Spracoolers or Natural Draft Cooling Towers are designed in Steel and Transite, or California Redwood. This type of tower is available in sizes up to 150 tons. It is particularly adaptable where space is not limited and air circu lation is not restricted. Bulletin PC-209. Phillips Spray Ponds and Spray Pond Fences are available in all sizes and ar rangements. Bulletin PC-213. Phillips Spracooler or Natural Draft Cooler 1356 iv. 77,.' Air System Equipment spray Nozzles Monarch Manufacturing Works, Inc. 2509 E. Ontario St., Philadelphia 34, Pa. SPRAY NOZZLES FOR WATER AND OIL NON-CLOG AIR WASHER NOZZLES produce an exceptionally efficient, evenly distributed hollow cone spray. Single large tangential inlet to swirling chamber minimizes any possibility of clogging. Also available in % in. to 1 in. pipe sizes inclusive, and of Brass, Stainless and Monel. Capacities: Gallons per Hour Sizes Pipe Orifice Lead 60 69 61 61 61 53 53 53 49 49 M* w *' Me' US' w W mat H' H' Me' Ms' He' 10 4.4 5.8 9.1 11.8 Lbs Operating Pressure 20 30 40 60 4.0 6.2 8.2 11.1 16.6 2.9 5.0 7.5 9.8 13.2 20*4 3.3 5.5 8.3 10.9 15.0 23.4 4.0 7.0 10.3 14.1 19.5 29.0 -19,5.. 24.3 31.5 52.2 78.0 82.0 27.6 "'34.6 46.1 75.0 112 121 33.3 42.8 57.0 92.5 138 152 39.1 50.0 64.1 109 163 180 49.0 64.0 81.9 138 205 225 100 5.1 8.7 13.0 17.3 24.6 36.5 60.0 78.5 105 189 257 300 Pip. eat Fig. 629 AIR CONDITIONING AND OIL BURNER NOZZLES Fig. F-SO Nozzle No. 1.35 1.65 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 7.00 Water Capacity in Gallons per Hour 25 1.03 1.36 1.56 1.86 2.20 2.22 2.55 2.90 Lb Operating Pressure 40 60 80 .57 .69 .83 .75 .89 .99 .94 1.H 1.28 1.13 1.45 1.64 1.39 1.62 1.85 1.77 2.11 2.46 . 2.00 2.42 2.77 2.32 2.77 3.21 2.88 2.96 3.35 3.01 3.57 3.75 4.01 4.60 4.09 4.31 4.78 5.17 100 .92 1.12 1.40 1.86 1.95 2.80 3.16 3.68 4.59 4.78 5.23 6.00 Produce finest breakup possible with direct pressure only. Capacities above are on water. "Nozzle No." is capacity on 34 second Saybolt viscosity oil at 1001b pressure. Larger sizes up to 60.00 gph and smaller sizes down to 0.60 gph. Furnished of all Brass for Water--Stainless Steel tip and disc for Oil. Standard with % in. or in. female pipe Brass adapter and Monel gauze strainer. SPRAY POND NOZZLES For recooling condenser water, etc. Operate on pressures from 5 lb upward. Made of Cast Red Brass and in-pipe sizes 1 in., 114 hi-, 2 in., and 2J in. Capaci ties from 4.1 to 88 gpm at 7 lb pressure. ' Write for Detailed Catalogs 1357 / AcrnE inousTRiES, inc. JACKSON, MICHIGAN, U.S. A. . Manufacturers of Quality Air Conditioning and Refrigeration Equipment since 1919 37 years experience stands behind these ACME products Since 1919 Acme has been building units to serve the air conditioning and re frigeration field. They have experi mented with thousands of models and installations. Today, Acme has a com plete line of commercial refrigeration and air conditioning equipment. Specify Acme on your installations. FLOW-THERM LIQUID CHILLER Complete, compact, packaged units of advanced design for air conditioning, heat pump and liquid cooling applica tions. Proven Acme components pre piped, tested and ready for operation. With compressor or without. Capacities --20 through 300 ton. ACME DRY-EX WATER CHILLERS For cooling water, brines, and other fluids by direct expansion of the re frigerant. Capacities from 5 to 300 ton. FREON and AMMONIA CONDENSERS EVAPORATIVE CONDENSERS and COOLING TOWERS Solid, sturdy, dependable. All fabri cated steel parts are hot-dip galvanized 'after fabrication assuring long life. Prime surface coils or specially designed Acme Pak for Freon or Ammonia in stallation. Capacities from 2 to 150 ton. The standard of the industry. Enough production combinations to assure you of the most efficient operation available. Capacities from to 700 ton. THE FLOW-COLD LINE A factory assembled and tested packaged liquid chiller designed for industrial process temperature control and air conditioning. Used as a heat pump for both heating and cooling. Capacities-- 3 through 20 ton. HEAT EXCHANGERS, LIQUID RECEIVERS, OIL SEPARATORS Freon suction and liquid line heat ex changers with capacities from 3 to 200 tohs; more than 70 standard sizes of liquid receivers for Freon, Ammonia, or other refrigerants; and a complete line of Freon or Ammonia Oil Sepa rators for Yi to 100 ton systems. Write for catalogs and more Information on any ACME product. 1358 Air System Equipment HSuerafat cTeransfer Aero pin Corporation 101 Greentvay Avenue Syracuse 1, N. Y. AEROflN Standardized Light-weight Heat Exchange Surface There is a factory-trained Aerofin application and service engineer located near you to give you prompt service. Write, wire or phone the factory. Aerofin is the modem Standardized Light-Weight Encased Fan SyBtem Heat ing and Cooling Surface originated by Fan Engineers to meet the present and future requirements of - this highly specialized field. All Standard Aebofin Units are furnished as completely en cased Units, ready for pipe and duct connections. The patent casings are built of pressed steel and are exception ally strong and rigid, protecting the Unit from all the strains of pipe connections and expansion or contraction in service. The casings are flanged on both faces, top and bottom, and template punched for bolting together adjacent Units, or for duct connection. units or for installing in ducts. May be installed either horizontally or ver tically. Used on any two-pipe steam system for preheating or reheating. Modulating control on preheaters. Available in 13 lengths and 3 widths, from net face area of 2.76 sq ft to 26.28 sq ft. Ftp. Fig. i Aerofin Non-freeze heater (Fig. 1) is non-freeze, non-stratifying spiral fin coil built into casing for air conditioning Flexltube Aerofin (Fig. 2) is distin guished from all other developments by its off-set tubes, so arranged as to absorb all expansion and contraction strains. Headers--Steel. . . Tubing--% in. O.D. copper, admiralty or aluminum. Joints--Where admiralty or copper tubes are used together with bronze or steel headers tubes are brazed to headers. Where both aluminum tubes and headers are used tubing is welded to headers. Casings--Copper, aluminum or gal vanized iron. Design--Constructed with headers on opposite ends making possible installa tion of units with tubes horizontal or vertical. Aerofin Corporation Air System Equipment Aerofin Corporation Air System Equipment Heat'Transfei Surface Pig. S Universal Aerofin (Fig. 3) is distin guished by its "S" bend construction of tubing, units designed with steel headers on opposite ends, the ends of the "S" bends being connected thereto by com pression nuts, the bends taking care of the expansion and contraction of the tubing. Recommended where close control is desired. Headers--Pressed steel. Tubing--1 in. O.D. copper or admi ralty. Casings--Copper, aluminum or galvan ized iron. Fig. 6 Booster Aerofin (Fig. 5)--straight tube type, single pass construction for pres sures from 1 to 200 lb gauge. Headers--steel. Tubings--% in. O.D, copper. Casings--copper, aluminum or gal vanized iron. Recommended where small coils are needed or to raise the air temperatures in branch ducts. Pig. 4 Aerofin Heavy-DutyIndustrial Heating Coil (Fig. 4) for use where extra-rugged coil is needed for close control. Steam pressures from 25 to 450 lb gauge; tem peratures to 550 F. Headers--Pressed steel. Tubing--1 in. O.D. heavy copper. Casings--12-gauge galvanized iron. Fig. 6 Narrow Width Aerofin: (Fig. 6) recom-mended for water cooling or for flooded Freon systems. Made in straight tubes only with headers on opposite ends, joint between headers and tubing being brazed. Construction similar to Flexitube Aerofin. Fig. 7 Aerofin Continuous Tube Water Coils (Fig. 7) are designed for air cooling by circulating cold water through the Aerofin and air over extended fin surface. Made for either horizontal or vertical air flow. Fig. 9 Aerofin Direct Expansion Units: (Fig. 9) Centrifugal Header Type--For cooling air, using Freon expanded directly into the coil. Tubes and fins are copper, completely Aerofin Sizes tinned with permanent metallic bond between fin and tubes. Headers are made of steel and casings of heavy gal- ; ,, Flexltube: 13 standard lengths, three widths, one and two rows deep. vanized iron or copper. Narrow: same as Flexitube. Tested to 250 lb air with coil sub merged in water. Universal: 17 standard lengths, two widths, one and two rows deep. ' Continuous Tube : 13 standard lengths, three widths, 2-3-4-5 and 6 rows deep. Cleanable Tube: 17 standard lengths, one width, 2 and 4 rows deep. . Direct Expansion: Centrifugal Header --11 standard lengths, three widths, 2-3-4-5-6 rows deep. Steel Supporting Legs: 18 in. and 24 in. high. Punched same bolt hole centers as standard' casings. Quickly, attached. No other foundation required. Fig. 8 Aerofin Cleanable Tube Units (Fig. 8) for cooling only made with headers re movable to permit cleaning tubes. Sale: Aerofin is sold only by manu facturers of nationally advertised Fan System Apparatus. List upon request. Recommended for use where sediment or scale forming, chemicals are present in the cooling water. Headers--Fabricated steel. Write Syracuse for Heating Bulletin H-45; Direct Expansion Bulletin DE-48-1 on refrigeration type units; Continuous Tube Bulletin C.T. 39-2 for Water Cool Tubing--Copper or admiralty. ' ing coils; or pamphlet on Cleanable Type Casings--Copper or galvanized iron. Aerofin for cooling. 1361 Air System Equipment Heat Transfer Surface The G & O Manufacturing Company ' 138 Winchester Avenue New Haven 8, Connecticut INDIVIDUAL AND STRIP FIN TUBING We manufacture a complete line of high efficiency heat transfer surfaces m a wide range of standard sizes with individual square, round and oblong fins. The use of individual fins permits using fins in groups at intervals along the straight length of any tube for the manufacture of U-bends, continuous return bend, and spirally wound coils. Where space permits, the use of square or oblong fina provides proportionately greater surface than a round fin of a diameter equal to one side of the square or oblong fin. , .. G&O Individual Fin Tubing is available for heating coils of every description, including unit heaters and blast coils, intercoolers,- aftercoolers, baseboard radia tion, and convector elements. INDIVIDUAL FIN TUBING STRIP FIN TUBING Continuous strip aluminum fin tubing is particularly suited for cooling and air conditioning coils. The "lightweight all aluminum construction is of advantage in installation where weight is an im portant factor. Various fin spacing is available and sections can be stacked to provide any practical number of rows in direction of air flow within the limits of maximum height and width area dimen sions. . G&O continuous strip fin coils are produced in two standard sizes: % in. O.D. tubing with % in. wide continuous strip fins, or % in. OX). tubing with in. wide continuous strip fins. O.D. of Tube 9S* W O' iV ti" W IV w V US' US' STANDARD SIZES Fin Size JS'sq. Fin Spac Surface per ing per Inch Linear Foot 6 0.80 sq. ft. JS* r'd. 6 0.60 sq. ft 1H' X 2H* 6 3.65 sq! ft oblong US' r'd. 6 0.87 sq. ft US' r'd. 6 1.55 gq. ft. sq. 0 2.40 sq. ft. sq. 6 4.15 sq. ft. 2H*sq. 5 3.50sq. ft. 2Ji? sq. 6 4.00 sq. ft. 2J6* sq. 6 3.82 sq. ft. 2^4' r'd. 4 2.33 sq. ft RADIATING ELEMENTS FOR ALL HEAT TRANSFER PURPOSES ARE AVAILABLE IN A WI RANGE OF SIZES 8 I I Air System Equipment The Patterson-Kelley Company, Inc. 101 Burson Street New York 17 101 Park Avenue Philadelphia 3 700 Walnut Street East Stroudsburg, Pa. Boston 16 96A Huntington Avenue Chicago 4 Railway Exchange Building Representatives in Principal Cities He Balance Loader: Standard capacities range from % to 50 tons. Shell sizes available from 4y2 in. by 12% in. to 14 in. by 90 in.-Three types available, depending on application--trombone design, shell and coil, and shell and tube. H* Storage Cooler: Available in all commercial metals. Sizes range from 24 in. by 48 in. to 60 in. by 192 in. Designed for service where requirements are not constant or where a large volume of fluid must be held in storage for peak load periods. He Slug Eliminator: A combination trap and heat exchanger that changes slugs of liquid refrigerant into gas before they reach the compressor. Standard capaci ties range from % to 60 tons. |* Freon Condensers: Capacities 5% to 410 tons. Shell sizes from 8 in. by 48 in. to 24 in. by 168 in. Two or 4 pass design, built in accordance with ASME code. The integral finned copper tubing is electronically expanded to assure water tight joints. Continuous Strip Fin, All Aluminum Cooling Coil . Standard No. 10 Send for Catalog and Price List 1362 P*** Dry Expansion Freon Cooler: *Catalogue& from 2 tons to 232 tons. Shell sizes j0n? in- ^ 40 in. to 26 in. by 220 in. Standard units are available in 1 and 2 P u{* design arrangements, 3 and 4 circuit arrangements are available on request. an oe constructed of carbon steel, galvanized steel, stainless steel, cupro-nickel silicon bronze or other alloys. ' 1363 Air System Equipment fusing The Rittling Corp, 103 Kentucky St. Buffalo 4, N. Y. Representatives in Principal Cities Warehouses--Buffalo, Albany. Philadelphia, Chicago Factories--Hamburg and Brooklyn, N. Y. Manufacturers of residential and non-residential Baseboard and Finned Tube Radiation, Convector-Radiators. Finned Tube Surface, Unit Ventilators and Air Conditioners, Unit Heaters, Back Draft Dampers, Air Cooled Condensers, etc. Rittling Baseboard Radiation. Complete line of Snap-On and PRE-FAB units for fast installation. Heating element^-choice of two tube aluminum finned copper tube or single tube copper tube with steel fins. Write for catalog. Rittling Heavy Duty Radiation. Complete line of heavy duty all-steel or steel finned copper tube units for commercial and industrial use. Flat and sloping top enclosures for wall and baseboard installations. Write for complete catalogs. Rittling Unit Heaters. Horizontal and vertical types. Capacities from 100 to 2000 EDR. Write for catalog. RITTLING CABINET CONVECTORS RITTLING BACK DRAFT DAMPERS Rittling Cabinet Convectors (left). Six standard cabinet styles. Aluminum finned copper tube elements with copper headers for use with steam or forced hot water. Write for catalog giving capacities and dimensions on all sizes. Rittling Back Draft Dampers (right). For high or low velocity. Positive seal. Extremely sensitive, quiet, non-metallic blades. Write for catalog. RITTLING UNIT AIR CONDITIONERS Unit Ventilators for heating and cooling schoolrooms, hotels, hospitals, office buildings, apartment houses and resi dences. Simplified design and controls give impressive savings on first cost and maintenance. Write for catalog. 1364 Air System Equipment Fin Tubing and Coils The Rome-Turney Radiator Company Erie Boulevard, East Rome, N. Y. ROME \ TURKEY RADIATOR COMPANY Manufacturers of "Ro-Fin" Extended Surface (continuous helical fin) Tubing for Heat Transfer Nearly 100 Sizes of Helical Fin Tubing in Production Straight lengths up to 30 feet long . . . coils . . . U-bends . . . tube-within-tube coils--sizes suitable for use with stand ard solder or flare-type fittings. "RoFin" Tubes are adaptable for a wide variety of heat transfer equipment, meet the requirements of the most rigid speci fications! Outside tube diameters from % inch to 1% inches, fin widths from } inch to % inch. Number of fins per inch ranges from 3 to 14. "Ro-Fin" tubing is made up in long, continuous lengths to meet customers' specifications. Stainless and other kinds of tubes furnished on special order. AIR HEATING AND AIR COOLING CASED COILS Two foot to ten foot lengths; 3 pace widths, approximately 12 inch, 18 inch, and 27 inch--custom sizes made to your specifi cations when required. ROME CONVECTOR RADIATOR * For heating residential, commercial, or public buildings. Free standing and wali-hung cabinet styles in ten lengths and four depths for steam and forced hot water installations. Non-ferrous fins on copper tube with brass and iron headers. . WRITE FOR INFORMATION ON YOUR INDIVIDUAL HEAT TRANSFER PROBLEMS 1365 Air System Eqquipment IStato? SLANT-FIN RADIATOR CORPORATION 87-67 130th Street Richmond Hill 18, N. Y. SQUARE-FIN SERIES SLANT-FIN SERIES ORDINARY fIN SIZE SLANT FIN SENT AT 45 Increased Surface FEATURES OF DESIGN AND CONSTRUCTION . 1. FIN TO PIPE BOND. Pipe is forced through undersize holes in fins under hydraulic presure. Pipe is not expanded. Fins do not cut into pipe surface. The result is a strong union of pipe and fin. 2. THERMAL BONDING. Standard pipe is rolled to uniform round diameter. Wide flanges of fins press solidly against entire surface of pipe. 3. SPACING AND STRENGTH OF FINS. Because of the uniformly wide flanges and their interlocking features, the fins fit tightly one into another. 4. EFFICIENT AIR CIRCULATION. Because of the increased surface, fewer of the distinctive "V" shaped slant fins than the traditional square fins can furnish the same radiation per linear foot of pipe. Therefore, fins can be wider apart and a greater volume of air flows more freely. 5. NO SNAPPING--NO BUCKLING OF FINS. Because of the patented notched flange, the slant-fin can expand and con tract without disturbing the bond to the pipe, even under high steam pressures. The result is a radiator that is troublefree. SPECIFICATIONS 1)4 in. IPS and 2 in. IPS steel pipe with steel fins 1)4 in. nominal hard copper water tube with copper or aluminum fins. Square-Fin Spacings: 24, 32, 40 and 48 fins (4)4 in.) per foot. Slant-Fin Sizes: 4% in. x 3)<> in. bent at 45 degrees to 3) in. x 3)4 in. and 5% in. x 4J4 in. bent at 45 degrees to 4)4 in. x 4)4 in Stock lengths in every integral foot from 2 to 12 feet. On specification, lengths up to 12 feet fabricated to nearest inch. Slope-Top Enclosure - Snap-On Enclosure Plat-Top Enclosure Expanded Metal Cover RESIDENTIAL BASEBOARD HEAT ING for Steam or Hot Water with a choice of 3 heating elements and 2 en closure styles. CATALOG No. 505 for details on" Slant- Fin" and "Square-Fin" radiators and enclosures for commercial and industrial applications. BULLETIN No. R-602 for residential baseboard heating. * 1366 Air System Equipment Fin-Type Radiator The Vulcan Radiator Company 26 Francis Avenue Representatives in Principal Cities Hartford 6, Conn. Vulcan Radiation (Linovector) is used in schools, industrial plants, hospitals, office buildings, churches, railroad cars and ships. Available in steel or copper . . . easy to install . . . light in weight . . . requires few fittings and supports . . . tube ends threaded or chamfered for welding. Heat distribution is uniform. Steel ra diation comes in two sizes ... 2 in. IPS, rated--5)4 sq ft per lineal ft at 1 lb steam and 65 deg air . . . for~lJ4 in. IPS see illustration--this size also available in copper. Illustrated catalog available. Standard Linovector Covers Grille Type F Type S Cover l*B *R Ratings for Vulcan Linovector available in , aiicviiauiuiuiy lmDeaaing onset tins or plates on seamless steel pressure tube or copper water tube. The patented offset fin construeofth|1t^beCOraPlete ngldlty t0 the eDt,re assemb|y extends the heating surface Because of its comparatively light weight and compactness, Vulcan Radiation re sponds qmckly to thermostatic control. Full heat output is obtained almost immedi ately after steam is supplied. Since most of the heat is given off bv convection the result is EVEN, UNIFORM HEAT from floor to ceiling 7 CODVecMon- the Vulcan Baseboard Radiation . . . fin-ontube construction with TRIMLINE cov ers combines radiant and convection heating. High safe working pressure . . . either hot water or two-pipe steam systems. Light in weight . . . easy to install . . . requires few fittings or sup ports. Comes in two sizes ... 1 in. IPS . . . steel fins 224 in. wide by 3% in. high and 1 in. IPS, 2 in. x 4)4 in. . . . for 1 in. IPS, see illustration. Also available in copper. Illustrated catalog available. I tn. IPS TRIMLINE covers in continuous lengths t rf1 ^ A- BuOt of .0S4-gage galoanite steel lsf>=ii ratings for Vulcan Radi- Vector available in Catalog No. 54. 1367 ______________________ Air System Equipment mISSSt"* Brunner Manufacturing Company , Dept. M-56, Utica, New York, U. S. A. The Brunner Co., Gainesville, Ga. In Canada: Brunner Corp. (Canada) Ltd., Toronto, Ont Refrigeration Air Conditioning Air Compressors Industrial Gas Compressors PRODUCTS: Refrigeration.compressors and condensing units for commercial. and industrial use--motor-compressor units for use with evaporative condensers, 2-stage and sub-zero units, truck units, self-contained and remote air conditioning. Also complete line of single and two-stage air compressors for pneumatic control and industrial applications. Industrial Gas Compressors for transferring Liquefied Petroleum Gas, Anhydrous Ammonia and booster for natural gas in manufacturing plants. Refrigeration Compressors Complete line of 2, 4 and 8 cylinder re frigeration compressors, adaptable to any need. Designed for slow-speed opera tion, less wear, longer life. F-12 and F-22. Air and Air-and-Water Cooled Condensing Units Y hp to 3 hp, for "Freon-12" refrigerant, finned tube condenser. Also Y hp to 3 hp combination air and water-cooled units, with cleanable condensers, to han dle fluctuating refrigeration loads. iVK: 8 Air System Equipment Refrigerating ' Machinery Copeland Refrigeration Corporation Sidney, Ohio COPELAND compressors, motor-compressors and condensing units for all. applications COPELAMETIC The Accessible Hermetic Direct-drive Copelametic units are com pletely accessible, making on-the-spot servicing a plus value. There are no belts or seals. No manual oiling is required. Ninety per cent of service costs removed by these features. Copelametic: motorcompressors have rugged, cast-iron bod ies; bronze rods, bushings and bearings; Swedish steel valve reeds. Copelametic offers unusual ec6nomies*ijuiet opera tion, long life and dependability. There are units for all applications ... on thermostatic or automatic expansion valves, high- or low-side floats and capil lary tubes. Remote, water-cooled from Y hp through 7Y hp. Air-cooled from Y hp through 3 hp. Self-contained models through 2 hp. Water-Cooled Condensing Units Y hp to 100 hp, for every commercial and industrial use. "Freon-12" or "Freon22" refrigerants, with cleanable con densers. Air Compressors Complete line--single stage from Y hp to 2 hp, two stage from \Y hp to 50 hp. Air compressors 5 hp and over available with water-cooled after-cooler. f3 Industrial Refrigeration Sizes up to 100 hp, complete line of watercooled condensing units and compressor units for use with evaporative condens ers, for industrial refrigeration and air conditioning use. Capacity controls available. Air Conditioning Units 2, 3, 5, 7Y> 10, 15 and 20 hp sizes, com pletely self-contained, in various styles for commercial and residential use. Easily installed. Semi-Hermetic Condensing Units . Brunner-Metics--Commercial and Low Temperature applications. Air-Cooled models, in Y, Y, Y, H, 1, 1Y, 2 and 3 hp Water-Cooled models, in Y> Y, 1> 1Y, 2 and 3 hp. 1368 Model ZRSOOH capacities at low power input. "Freon12" and "Freon-22" models. 1H Ap Copelaweld CONDENSING UNITS WITH SUC TION-COOLED MOTORCOMPRESSORS COPELAWELD MOTORCOMPRESSORS Suction-cooling affords greater flexibility of installation, since no water is required. Engineered to Copeland's high stand; These larger sizes make possible even ards, the welded motor-compressors give ; wider applications. 2 hp and 3 hp have a maximum economy in package air condi centrifugally-forced oiling system. tioners, water coolers, refrigerators and Larger sizes incorporate a gear pump. other equipment. Cool-running, two- Both systems allow motor-compressor to cylinder Copelawelds are free fr6m vibra operate in either direction. From cast tion and chatter. High quality, one-piece body to solid bronze rod, bearings and body casting .for positive alignment of bushings, and Swedish steel valve reeds motor and bearings. Solid bronze rods it is quality built. Units have oversize and main bearings assure long wear. condensers for maximum efficiency in Compact size conserves space. Efficient high ambient temperatures. Designed oil pump has no mpving parts, will op especially for air-conditioning and other erate in either direction. Heavy-duty, high-suction pressure applications. Sizes high-power-factor motor delivers high 2, 3 and 5 hp. Air System Equipment Curtis Manufacturing Company Refrigeration Division 1959 Kienlen Ave. St. Louis 20, Missouri, U. S. A. New. Yohk Office Chicago Office 30 Veset St. 9 S. Cuntos St. Kbtahlisiied 1S54 * Products: Full line of Packaged Air Conditioners from 3 through 20 ton? Condensing Units from through 100 hp with Cooling Towers, Air Handling Units to match. Packaged Water Chillers 7)4 through 100 hp. Waterless Air Cooled Packaged Con densing Units, 2 through 7)4 hp, Residential and Commercial. . 15 hp Cleanable Shell and Tube Con densing Unit. Other sizes from 7)4 to 100 hp. .. . . COMMERCIAL REFRIGERATION Air cooled condensing units from 14 to 3 hp, inclusive, combination air and water copied units from )4 to 3 hp, inclusive, and water cooled unite from )$ to 40 hp, in clusive. All models charged with Freon 12 refrigerant. Mechanical advantages include Timken Bearings, Positive Pressure lubrication. Special models are available for ice cream, frozen food cabinets and for the dairy industry. it M. ft Packaged Water Chiller 7H through 100 ton. For process or solution cooling and various other types of liquid chilling ap plications. Air System Equipment Atlanta Boston Buffalo Charlotte Chicago Cincinnati Dallas Kansas City Los Angeles Frick Company Waynesboro, Penna. Memphis Philadelphia New Orleans Pittsburgh New Yore St. Louis Okla. City Seattle Palatka Washington Distributors id Principal Cities Air Conditioning, Refrigerating, Ice Making and Food Freezing Equipment AIR CONDITIONING Complete Frick Systems, including several that are patented; also refrigera tion for use with equipment supplied by others. Thousands of installations attest the value of Frick air conditioning. See Bulletin 504 on typical installations, 505 on -engineering details, 522 on unit Frick VECLIPSE" conditioners, and 148 on air conditioned . Compressors.t, S, 4, 6 cold storages. or 9 cylinders. Bulletin 100. FREON REFRIGERATION UnU9 \ir,?2^i^oneT9> Frick low pressure unite, "ECLIPSE" multi-cylinder com pressors, and larger enclosed Freon machines provide a com plete and efficient line. Unit air conditioners; central systems; plain and finned coils; coolers, condensers, controls; also valves and fittings to suit. Patented Flexo-Seals, pressure lubrication, capacity controls, and built-in dependability make Frick machines your logical choice. Combined Unite with "ECLIPSE" Com pressors. Bulletin 100 AMMONIA REFRIGERATION Combined units and vertical enclosed compressors, with 2 or 4 cylinders, in sizes from 2U to 1000 tons. Also "ECLIPSE" compressors for ammonia and high pressure service, with 3, 6 or 9 cylinders. Ammonia equipment is used with material savings in certain air conditioning work. Waterless Air Cooled Packaged Con densing Unit (right) for residential and commercial application 2 through 7)4 hp. Packaged Air Conditioners (Left) in many combinations of pastel colors 3 through 20 ton. 1370 If? Enclosed Ammonia Compressors, S in. by S in. to J7?4 in. by It in. Bul letins lit, 516 '& 651. i'M 41 ] si 1 1 i.i Low Pressure Refrigerating Units, Cpen Drive or Accessible - Hermetic Types. Bulletin 97. Eight 9-Cyl. "ECLIPSE" Compressors Air Condition the Two 11Slory Buildings of The American National Insurance Co. at Galveston 1371 Air System Equipment gSffifo, The Ready-Power Co. 11231 Freud Aye., Detroit 14, Mich. Atlanta Boston Chicago REflDVPOUlER AIR CONDITIONING AND REFRIGERATION EQUIPMENT SAVES AS IT SERVES District Offices or Representatives Cincinnati Dallas Detboit Philadelphia Pittsbdbgh Los Angeles New Obleans New York Seattle St. Louis Ready-Power Engine Driven Com pressor Units are designed and built to meet the need of (1) Low operating cost air conditioning and refrigeration em ploying NATURAL GAS fuel and (2) Air Conditioning and refrigeration where electric power is not available or high in cost. It is particularly adaptable to ortable equipment for cooling airplanes, efore take-off, for pre-cooling perish able food shipments by rail or truck, and for installations in refrigerated rail cars and trucks. CAPACITY MODULATION The Ready-Power inherent system of capacity modulation permits operation of the compressor to meet the needs of varying conditions. This assures much better control of temperature and humidity conditions than is possible with the usual "on and off" system generally used with electrically driven equipment. On units of 15 to 70 ton. the capacity modulation is controlled both by varying the engine speed and by unloading the cylinders of the compressor. Since engine speed can be varied from maxi mum to less than half of maximum this more than doubles the usual advantages obtained from unloading. On the smaller units, the capacity modulation is controlled entirely by gjj. engine speed variation. .' ' All capacity modulation is auto- 'h'/ matically controlled. .-Tw UP TO 70 TON RANGE ; Unit capacities range up to 70 tons for ; air conditioning and multiple unit instal- . lations of more than 150 ton are in sue- . cessful operation. Compressor units are adaptable for use with evaporative condenser, heat px- . changer or radiator cooling of the engine. -.7 Water cooled manifolds are standard on some models and available on all models. 1 Engine starting is by either storage battery or a-c Motor. . .y All units are supplied for operation on Natural Gas, Gasoline, Propane on Butane fuels. 7^ Units of 15 ton and larger are also ... available for operation on Diesel fuel. 1372 Air System Equipment ?^geraTTM8erBMachiner7- VINE--INC,s 7250 East Slauson Avenue, Los Angeles 22, California. Manufacturers of Air Conditioning and Commercial Refrigeration Equipment I* RECOIL ID* TRAOCMARK REG. RECOLD AIR CONDITIONING EQUIPMENT Sizes from 3.3 to 40 sq ft cooling coil area Vertical or horizontal units (illustrated) Bulletin No. AC-S08G Multi-Zone units . Bulletin No. AC-S04G Air Conditioning Coils Bulletin No. AC-S01G Midget Evaporative Condensers (Specifications Sheet) Hy-Flo Cooling Towers (3 and 5 ton) Bulletin No. CT-811G Recold also manufactures a complete line of refrigeration blower coils includ ing Water Defrost and Vapor Defrost systems. "DRI-FAN" EVAPORATIVE CONDENSERS AND "DRI-FAN" COOLING TOWERS Capacities from 3 to 150 tons Diagram shows "Dri-Fan" principle. Wavy arrows denote warm inlet air. Dotted arrows show discharge of moist air. Air is forced through instead of drawn through. Fans operate in dry, in coming air stream. This prolongs life of fan and eliminates many service prob lems. Units are galvanized inside and out. Ingenious panel fastening insures an air tight, water tight housing and yet provides easy access by removing only a few screws. "Dri-Fan," Evaporative Condenser-- Bulletin No. EC-410G "Dri-Fan" Cooling Towers--Bulletin No. CT-801G Patented access doors (left) form a water tight seal without use of gaskets. Door,s slide freely, can be opened and closed repeatedly without danger of leaking. Patented bleed control (right) elim inates small tubes and valves. Funnel catches an accurately determined amount of jvater. Assures positive, non clogging action with scale control and minimum water loss. Write for bulletins and name of nearest distributor Refrigeration Engineering, Inc. 7250 East Slauson Avenue Los Angeles 22, California 1373 Aerovent Fan Company, Inc. Ash and Blade Sts. Piqua, Ohio Standard Assemblies for Every Air-Moving Requirement BELT-DRIVEN AND DIRECT-DRIVEN DUCT Easily installed in present ducts for haz ardous and non-hazardous atmospheres. In sizes 12 to 84 in. with 2,4,6 or 7 blades for capacities to 120,000 cfm. DIRECT CONNECTED Heavy-duty units for all industrial ap plications. Steel ring and panel types. In sizes 9 to 84 in. with 2,4, 6 or 7 blades for capacities to 120,000 cfm. "BI-FLO" DUCT New divided-duct design for duct or stack installation. Available with new 7-blade Semi-Pressure propeller. Sizes 16 to 48 in. for capacities to 40,000 cfm. MANCOOLERS Four models for any industrial cooling, drying, exhausting or ventilating re quirement. Sizes 16 to 48 in. for capaci ties to 40,000 cfm. MATERIALS HANDLING Reversible rotation and adjustable air discharge for conveying production and waste materials, dust collecting or ex haust. Wheel diameters 19, 26, 33, 40, 51 in. VANEAXIAL Maximum efficiency against resistances to 6J4 in. S.P. High-velocity, straight line air discharge. Sizes 12 to 48 in. for capacities to 77,000 cfm. ROOF VENTILATORS Three types for all industry exhaust and air supply requirements. All-weather construction for use in all climates. Sizes 12 to 72 in. Capacities to 80,000 cfm. CERTIFIED RATINGS All Aerovent Fane are tested and rated tn accordance with the Stand ard Test Code for Centrifugal and Axial Pane and conform with V. S. Department of Commerce Com mercial Standard CS178-51. "Specialists in efficiency-engineered air-moving equipment" Fan Wheels Large Diameter Propellers Penthouses - Shutters Accessories ' . 1374 Air System Equipment Fans and Blowers Aladdin Heating Corporation 1111 West Ave. 137, San Leandro, Calif. Manufacturers of Centrifugal Blowers, Heating and Ventilating Equipment BB FAN--Backwardly inclined blade fan with non-overloading horsepower charac teristic. Manufactured in 22 sizes, single and double width, all arrangements, 2 classes of construction. Request Bulletin S05-A, 60S-B. FC FAN--Forward curved fan, slow speed for quiet operation. Manufactured in 22 sizes, single and double width, all arrangements, 2 classes of construction. Request Bulletin 605-A, 605-C. ____ RB FAN--Radial blade fan well suited for handling grease or other sticky materials. Manufactured in 13 sizes, single width only, all arrangements, 2 classes of construc tion. Request Bulletin 450-B. EX FAN--Radial blade fan used chiefly for conveying materials, fume exhaust, etc. Manufactured in 15 sizes, single width only, all arrangements, 5 classes of construc tion, 3 wheel types. Request Bulletin 461. UTILITY SETS--Self contained units for a wide variety of ventilating applications. Manufactured in 14 sizes with forward curved rotors, 12 sizes with backwardly in clined blade rotors, single width only. Request Bulletins 610-A, 611-A. FC JUNIOR FANS--Self contained direct connected fans with forward curved rotors. Manufactured in 5 sizes with 13 motor speeds, single width only. Request Bulletin 428 HV UNITS--Heating and ventilating unit of universal design. Can be furnished with air filters, face and by-pass dampers or mixing box. Manufactured in 7 sizes with unlimited flexibility as to arrangement. Request Bulletin 510. ROOF VENTILATOR--Backwardly inclined blade centrifugal type. Manufactured in 13 belt driven and 12 direct driven sizes with steel, aluminum, copper or stainless steel housings. Request Bulletin 410-A. TYPE AR ROOF VENTILATORS--Backward inclined blade centrifugal type. All units fabricated from spun aluminum. Available in both direct connected and belt driven models. Request Bulletin 411. r ' 1375 Air System Equipment Blower* Bayley Blower Company 1821 S. Sixty-Sixth Street Branches in Principal cities Milwaukee 14, Wis. Engineers and Manufacturers of Fans, Washers, Heaters and Other Air-Handling Equipment CENTRIFUGAL FANS Bayley offers a complete selection of types, sizes and arrangements of centrifugal fans for ventilating, conditioning, industrial, and mechanical draft service, with slow-speed, power-limiting, or medium speed wheels. Made in single or double widths, with capacities up to 300,000 cfm or more. Smaller sizes have reversible housings for convenience and economy. t P .ft-., ;!?V VENTILATING FANS AND PACKAGED SETS Type "F" Fans are equipped with wheels having forward-curved floats, effecting a slow-speed characteristic. The floats of the wheels supplied with Type "AP" Fans are backwardly inclined, producing a non-overloading characteristic. Choice of fans is determined by the design condi tions of the individual installation. ' Compact, unitary Ventilating Sets are manufactured with drive complete, ready to use, direct-connected and belted styles with capacities to 15,000 cfm.fThese handy units serve a wide variety of applications in ventilation and exhausf; for kitchens, lavatories, gymnasiums, restaurants, garages, halls, hospitals, laboratories, indus trial.plants, and many other locations. May be used for supply, exhaust or both. They can be equipped with weather-protection hood for outdoor or penthotise installation. Carefully engineered and sturdily built to give long-lasting, efficient service. W. Industrial Fan INDUSTRIAL FANS Bayley Industrial Fans are available : in a wide range of sizes and constructions from which to select .'Jjf the unit best fitted for any application in exhausting, convey- %|K ing, cleaning, drying, blast, draft, or similar duties. Type -guj "EX" is proportioned primarily for medium pressures and capacities usually encountered in materials handling or ex-' haust. Type "H" is similar, but proportioned for relatively higher pressures and smaller volumes. Designs are adaptable to ; - suit virtually any requirement of temperature, corrosion-re- , >~sistance or other severe operating conditions. Turbo Washer AIR WASHERS Because Turbo wash ers atomize by mechanical means, they cannot clog, hence are admirably suited to handling air contaminated with par ticulate matter. Standard pressurenozzle washers also available for use where dust content is light. lasting iron pipe coils of Chinook Heaters will not clog, therefore maintain full capacity longer. Pipe-within-a-pipe ar* rangement has single heater for supply and return, cannot short-circuit, and absorbs expansion and contraction with out damaging stresses. - , Air System Equipment. a"11 Blower* The Bishop & Babcock Mfg. Co. Massachusetts Blower Division . 4901 Hamilton Ave. Cleveland 14, Ohio CB.C.) SQUIRREL CAGE AND POWER FIXED FANS Squirrel Cage (forward curve) and Power Fixed (Backward curve) Fans available in a complete range of sizes--single or double width. For all types of commer cial and industrial air conditioning and exhaust systems. Bulletin 101 (P-F.) Bulletin 105 (S.C.) MASSACHUSETTS UNIT HEATERS AND AIR CONDITIONING UNITS Both floor and ceiling mounting arrangements available. These units are built in sections to facilitate efficient handling and erection. Offered in a wide range of popular sizes with various heating and cooling coil combinations. Bulletin 11S .(Unit heaters) No. ISO (A.C. Units) POWER ROOF VENTILATORS Propeller fan type features a steel ven turi-type inlet orifice, belt or direct drive. Power fixed type has backward curve wheel, belt or direct drive. Both offered in a wide range of competitive . sizes. Bulletin No. 118 (Power fixed) No. 1S4 (Propeller fan). BELT OR DIRECT DRIVE UTILITY TYPE VENTILATING SETS Belt drive wheel diameters 7 in. to 30 in., direct drive 6 in. to 13J^ in. Both avail able in popular competitive sizes. Bulletin No. 109. PROPELLER FANS New venturi-type propeller fans. Belt drive 24 in. to 48 in. wheel diameters. Direct drive 12 in. to 30 in. wheel diam eters. A complete line of accessory items are available. Bulletin No. 117. UNIVERSAL BLOWERS (at left). A stock blower assembly made in single or double width, sizes 7 in. to 27 in. wheel diameter and features universal dis charge arrangement. Bulletin No. 110. DESIGN 2 A.C. BLOWERS (at right). Available in single, double or special width. All housing and wheel parts are die formed and are offered as complete assemblies or-parts only. Bulletin No. 115. 177 Air System Equipment sBaSdeflwerS' Bronson Fan Manufacturing Corp. 4560 Worth Street, Los Angeles 63, Calif. Representatives in Principal Cities Manufacturers of Propeller Type Fan Blades for Air Conditionlng, Heating and Ventilating Equipment. . Tested and rated according to NAFM and NEMA codes. m HI-STATIC SERIES--Quiet operation against static resistances. Gives high air vofumes at reduced fan depth. Diam eters 11 in. through 16 in. Neoprene hubs available. HI-STATIC SLINGER RING--Con densate eliminating fan blade for use in air conditioning units where space is a factor. Exceptionally low noise level. Hi-Static Senes Hi-Static Slinger Ring STATIC PRESSURE SERIES--For effi cient air deliveries against static pres sures. Diameters 8 in. through 20 in. Pitches 6 deg to 40 deg. Also in THREE BLADE SERIES. Static Pressure Series STATIC PRESSURE SLINGER RING-- Designed to eliminate condensate in air conditioning applications. Ring can be positioned anywhere on fan blade. Neo prene hubs available. S. P. Stinger Ring FERE AIR THREE BLADE SERIES-- _ Bright finish aluminum blades, steel \ spider. High efficiency in free air. Diam/ eters 8 in. through 30 in. Pitches 6 deg ' to 40 deg. Free Air Three Blade FREE AIR FOUR BLADE SERIES-- Wide overlapping blades assure quiet operation. Sturdy construction. Diam eters 8 in. through 30 in. Pitches 6 deg to 40 deg. Iree Ai* I > /?.*/< HURRICANE SERIES--Semi-pressure type for efficient use against low static resistances. Diameters 12, 14 and 16 in. Neoprene bushed hubs available. K-D SERIES ATTIC FAN BLADES-- Heavy duty construction. Shipped knocked down. Diameters 24, 30, 36, 42 and 48 in. 35 deg pitch only. Hurricane Series One-Piece Series ONE-PIECE SERIES--Available with hub or pierced for unit-bearing motors. Diameters 6 in. through 12 in. Many special designs. SPACESAVER SERIES--Off-set design enables the blades to rotate around motor for space reduction. Diameters: 18 in., 20 in. Three blade only. Pitches 15deg to 35 deg. 1378 K-D Seric SpaceSaver Series X $ a i I ic fs Ik. VTv' Air System Equipment ITMered Brookside Products Company, Inc. McCordsville, Indiana Manufacturers of-- FANS -- BLOWERS -- VENTILATING EQUIPMENT POWER-FLO 100-SERIES BLOWERS: Sturdily built with conical shaped inlet ring welded to blades. Built especially for higher pressure ventilating and exhaust systems. Backwardly inclined for non-overloading and low noise characteristics. Both statically and dynamically balanced. 14 in. to 60 in. dia. too-SerUs POWER-FLO 200-SERIES BLOWERS: Ruggedly and efficiently built as well as lighterjn weight for lower pressure ap plications. Backwardly inclined blades for low noise and non-overloading char acteristics, also, statically and dynamically balanced. Fabri cated of aluminum or steel. Riveted construction throughout. u in. to 60 in. dia. POWER-FLO 50-SERIES BLOWERS: Are general purpose blowers for various air moving applications including air con ditioning, heating, oil burners, etc. Available in both single and double inlet types, both rotations. All widths in sizes from 3 in. to 10 in. Stinger Type M-PEL-AIR FAN BLADES: Slinger type for air conditiomfrg or offset spider and conventional propellor type fans for ventilating and other applications. All engineered exactly to your specifications free of charge. Slinger rings are all one piece die drawn. 50-Serie* Off Set Type M-PEL-AIR "A" SERIES FANS: Are of one piece construc tion of aluminum or steel. Available with hub or unit bearing motor piercing. Designed especially for air conditioning and refrigeration industries. 1379 A-Seriei Air System Equipment biow<*!> `Bmtdaqe THE COMPANY C- 530 N. Park Street Kalamazoo, Mich. Air Conditioning and Furnace Blower Specialists The Brundage Company Air System Equipment Blowers SERIES "X" BLOWER ASSEMBLIES. A high-performance unit for all heating and air conditioning applications ... in top and bottom, vertical and horizontal discharges. A full range of standard sizes from 8 in. to 16 in. built to high quality standards. Special discharge models are produced on special order. M P m DIRECT DRIVE BLOWERS. Save space. Cut costs. And maintain full cfm output with top-quality Brundage Direct Drive blowers. Ideal for modern, cojnpact heat ing and air conditioning equipment. The Brundage Volume Control Damper insures proper air flow at lowest cost . . . requires no electrical components. With full or three-quarter width wheels. Produced in all discharges. BLOWER-FILTER PACKAGE UNITS. 7 sizes, from 400 to 3,500 cfm output. Cabinets are heavy-gauge, cold-rolled steel finished in durable baked enamel. Standard replaceable air filters are easily reached. SERIES "S" BLOWER-EXHAUSTERS. 200 to 2,200 cfm output, very compact. Can be fastened directly to wall and easily made weatherproof. Angle of dis charge adjustable to any degree. Pre cision made of heavy-gauge steel. -rfv UX SERIES UNIVERSAL BLOWERS. Here are all standard and angular discharges your heating or air conditioning equipment may require--in one package. Available with full or three-quarter width wheels, Brundage Universal Blowers are ideally suited to streamlined production facilities where lower inventories are desired. ,j'~% "; WRITE FOR DETAILED SPECIFICATIONS AND PERFORMANCE DATA. 1380 SERIES "T" TWIN BLOWERS. For distribution of large volumes of air over large areas. Consists of two blower wheels on self-aligning, polished shaft. Heavy scroll housings and rugged metal frame for industrial applications. WRITE FOR DETAILED SPECIFICATIONS AND PERFORMANCE DATA. 1381 Air System Equipment Fans and Blowers Buffalo Forge Company 450 Broadway, Buffalo, N. Y. Unit heaters. Ventilating Fans (centrifugal axial flow and propeller). Air Washers, Drying Equipment, Mechanical Draft Fans, Air Preheaters, Blowers, Exhausters, Air Cleaning Equipment, Spray Nozzles. Write for Bulletins mentioned below, or call the "Buffalo" Engineering Representative in your nearest principal city. "Buf falo", publisher of "PAN ENGINEERING", is ready to work with you on any air problem,you may have. TYPE "BL" VENTILATING FANS. These non-overloading centrifugal fans are widely used in large ventilating and air conditioning systems where quiet operation and high efficiency are desirable. Performance is completely stable, from free air delivery to shutoff. Smooth bell-shaped inlet and duct collars with "Buffalo" directional inlet vanes, minimize entry turbu lence. The rotor has a curved shroud matching the inlet bell, as well as double backward curved blades for smooth, quiet air flow through the streamlined, full-curvature housing. Capaci ties from 1000 to 500,000 cfm. Wide choice of arrangements. Write for BULLETIN F-101. INDUSTRIAL EXHAUSTERS: All-welded steel plate construc tion in these heavy-duty fans means smooth rivet-free interior surfaces for minimum friction. Available with interchangeable "AW" Air Wheels for airborne dusts, gases, fumes, or with "MW" Material Wheels for grit, sawdust, grain, stringy ma terials. Available with heat slingers to handle gases up to 1000 F. in induced draft and other high temperature applications. Write for BULLETIN 3578. AXIAL FLOW VENTILATING FANS. For light-duty (up to 3 in. s.p.) ventilation, exhausting, system boosting, draft and circulation applications, these lightweight fans fit into straight duct runs, taking up no more room than a section of round duct. Extremely quiet, efficient and non-overloading. Avail able in tubeaxial (without directional vanes) or vane-axial (with directional vanes) models, with direct connected motorin-housing or with Vee-belt drive and motor out of air steam. Models for high or low temperatures, non-sparking and/or corrosion resistant construction. Write for BULLETIN S5SS-EF. AIR CLEANING EQUIPMENT. "Buffalo" builds all types of units from Air Washers like the one shown for cleaning, humid ity control, heating and cooling to highly specialized units for abating effluent nuisances in the chemical and process indus tries. More than a half-century of experience in this field is at your service, as well as our complete manufacturing facilities. Write for Bulletins on the industry-proved "Buffalo" equip ment to solve any air cleaning or processing problem you may have. PC CABINETS (1). Heavy-duty units coils and heavy-gauge paneling and tank. for major air conditioning. Compact, BULLETIN 3703. sectionalized construction permits easy installation and servicing. Vertical floor or flat suspended models for any or all air conditioning functions. Equipped with "Buffalo" Fans and Pumps, Aerofin UNIT HEATERS (2). "Buffalo" breezoFin Heaters operate on as little as 2 lbs steam, have high-radiation one-piece copper-finned tubes and efficient "Buf falo" Breezo Fan for quick, economical heat where needed. Write for BULLETIN S1S7-E. Also, a wide selection of heating and ventilating units, with or without filtered intake and by-pass dampers, suspended and floor models for large areas. Air System Equipment Fans and Blowers Alan E. Burden Co., Inc. Manufacturer of Propeller Type Fan Blades 1940-50 Pontius Ave., Los Angeles 25, Calif. For Air Conditioning Refrigerating and Heating Applications All Burden Fan blades are individually inspected after leaving the production line for bore size with "go and no-go" gauges, to a tolerance of plus or minus one Hoooth of an inch. Each fan blade is individually gauged on a special machine for contour and alignment, then statically and dynamically balanced with Mechanical, Audio Vibration Equipment. A modern, completely equipped laboratory makes possible exhaustive performance tests. Expert engineering counsel is available for requirements involving unusual applications. A laboratory at the factory is equipped for both routine and special testing when necessary. BURDEN 3 BLADE FANS. Furnished clockwise and counter-clockwise. Diam eter range, 10 in. to 24 in. with variations of pitch of from 6 deg to 42 deg in incre ments of 1 deg. Hubs front or back. Standard spiders cadmium plated. Blades aluminum, commercial bright. BURDEN 4 BLADE FANS: Furnished clockwise and counter-clockwise. Diam eter range, 10 in. to 30 in. with varia tions of pitch of from 6 deg to 42 deg in increments of 1 deg. Hubs front or back. Spiders cadmium plated. Blades alumi num, commercial bright. BURDCO REVERSIBLE, INTER CHANGEABLE HUBS: Designed for BURFLEX HUBS: Are similar to the special Burden blades produced with 'Burdeo reversible, interchangeable type uniform size openings. Hubs produced * With the added feature of a specially de in six bore sizes can be quickly adapted signed noise insulating grommet, con to front or back and keyed firmly into structed to fit over the hub in applica place with a positive locking device. tions where lessened vibration and damp They are adaptable to 3 or 4-blade ening of sound are desired. Insulated hub fans, clockwise or counter-clockwise in absorbs motor noise. Information sent all variations of pitches. on request. 1383 Air System Equipment Fans and Blowers Century Fan & Ventilator Co., Inc. 45-55 Cedar St., Stamford, Conn. Plants in Stamford, Burrville, Torrington, Conn. PROPELLER FAN EQUIPMENT . PADDLE WHEEL TYPE s BLOWERS MULTIVANE & BACKWARDLY CURVED VENTILATING BLOWERS . INDUCED DRAFT FANS . GRAVITY VENTILATORS s- CYCLONE ROOF FAN ...Compact, symmetrical and low in height for modern buildings. Its high efficiency, large volume capacity, slow operating speed and quiet performance make it ideal for schools and hospital buildings. Shipped complete with motor, driver, fan, framework and housing. Housing of galvanized steel, aluminum, copper, lead- coated copper and stainless steel to withstand atmospheric conditions. Conforms to code ratings of PFMA, NAFM and ASHVE. ' Capacity Table Fan Size 16 19 22 25 28 31 34 37 43 50 56 62 Fan Rpm 1140 960 . 1070 900 850 750 790 600 620 540 510 590 390 500 440 500 410 400 345 350 300 300 265 280 240 Motor Hp H n K H H H 1 H H % \\ 1 H m i Hi 1 2 m 3 2 3 2 3 2 Fan Tip Speed 4460 3760 5040 4230 4675 4120 4960 3760 4390 3820 3595 4840 3065 4330 3815 4710 3995 4390 3785 4390 3770 4240 3745 4400 3750 Cfm F.A. Cfm W 1565 1320 2610 2380 3680 3385 4680 4055 5670 5000 4745 7160 5000 8600 7640 10920 9130 13920 12240 17900 15440 23060 20660 27030 23900 1460 1205 2500 2200 3520 3280 4460 3660 5335 4615 4325 6800 4415 8360 7335 10640 8770 13460 11600 17120 14470 22280 19830 . 25800 22560 Cfm ys 1310 1050 2340 2100 3355 3120 4220 3260 5015 4160 3800 6620 3820 8160 7065 10320 8400 13000 11020 15890 13100 21550 19060 24700 21490 Cfm W 1120 855 2220 1895 3190 2790 3910 2740 4705 3785 3315 5930 3030 7990 6800 9550 7680 12470 10250 14900 11830 20150 17730 23100 20050 Cfm 1020 730 2030 1620 2945 2510 3705 2270 4145 2965 2430 5510 7500 6185 8830 6870 11630 8960 13530 10300 18800 16140 21800 18200 Cfm W 755 1770 1310 2580 1880 3290 1630 3520 2050 4920 6680 5060. 8080 5920 9720 7080 12070 8500 16950 14100 19000 14900 CENTURY AUTOMATIC DRAFT INDUCER ` Installed in boiler breeching. Maintains draft of pre-selected intensity. Elim inates high stacks. Completely auto matic and quiet operation. Approved by "Underwriters Laboratory". -V'V. CENTURY MID DRAFT FAN For low and high pressure heating plants using oil, stoker or gas-fired boilers. Creates perfect uniform draft regardless of weather. Installed in breeching in any position. Rated in conformity with test codes of PFMA, NAFM, and ASHVE. Size 14 14 18 18 18 Mid Draft Fan Hp Max. Fan Rpm M 1725 1725 1200 1450 1650 Send For Complete Catalog Cfm 960 1080 1600 1850 2160 . Sp inch H nHH 1384 Oil Gal Der hr 12 14 20 23 27 * - ** Air System Equipment Fans and Blowers CHAMPION BLOWER & FORGE CO. Lancaster, Pa. Address Correspondence to Div. 9 Manufacturers of Blowers, Ventilating Fans and Exhaust Fans for handling air, material and fumes Representatives in Principal Cities ... 1 CHAMPION TYPE "D" VENT.SETS For. general ventilation of all types equipped with backward curved non overloading wheels up to 30 in. diameter, furnished complete With electric motor; adjustable drive and weather proof; covers if required. .. Champion Cast Iron Housed Fans of Champion Forward and Backward various types for fume hood exhaust Curve Ventilating Fans and Exhaust and for handling corrosive gases. Can Blowers manufactured in sizes up to be equipped with either plain steel or 60 in. dia. Fans also furnished in all non ferrous blast wheels, interior of standard arrangements with Ball, Bab housing and wheel can be covered with bitted or Water Cooled Bearings, as re special corrosive resisting coating. quired. 1385 Air System Equipment . Fans and Blowers $ CORPORATION 9865 Pacific Ave., Franklin Park, 111. GLadstone 5*478o-Write for Bulletins Ala., Birmingham Ariz., Phoenix Are., Little Rock Calif., Los Angeles Calif., San Francisco Colo., Denver Conn., New Haven Fla., Jacksonville Fla., Miami Fla., Ponte Verda Beach Ga., Atlanta ' III., Chicago III., Rockford Ind., Fort Wayne Ind., Indianapolis Ind., Sooth Bend____________ Iowa, Bettendorf Iowa, Des Moines Kans., Wichita Ky., Louisville La., Shreveport La., New Orleans Md., Baltimore Mass., Boston Mass., Springfield Mich., Detroit Mich., Muskegon Minn., Minneapolis Miss., Jackson Mo., Kansas City Mo., St. Louis Nebr., Omaha________ N. M., Albuquerque N. Y., Albany . N. Y., Brooklyn N. Y., Buffalo N. Y., Rochester N. Y., Syracuse N. C., Charlotte Ohio, Cincinnati Ohio, Cleveland Ohio, Columbus Ohio, Dayton Ohio, Toledo Okla., Oklahoma City Oki.a., Tulsa Ore., Portland Pa., Harrisburg_________ Pa., Philadelphia Pa., Pittsburgh Tenn., Knoxville Tenn., Memphis Tenn., Nashville Texas, Amarillo Texas, Dallas Texas, Houston Texas, Lubbock Texas, San Antonio Utah, Salt Lake Cin Va., Richmond D. C., Washington Wash., Seattle .Wash., Spokane Wib,, Milwaukee NEW AIRFOIL CENTRIFUGAL FANS REDUCE NOISE LEVELS 65 PER CENT Quieter Operation, Greater Efficiency for industrial, commercial and all other heating, ventilating and air condition ing applications. . Efficiencies in excess of 90 per cent. Steep pressure characteristic curves. Noise level ratings lower than other type wheels. . Certified ratings. All drive arrange ments; directions of rotation and dis charge. 600 to 1,000,000 cfm to 32 in. sp. Class I to V construction. Wheels 12 to 143 in. diameter. Bulletin A-102. -f- V. ; =T 'r' V' l % s' Axial Airfoil Fans for removing fumes, vapors in dangerous locations. 1100 to 105,000 cfm. Bulletin AA-101. Axial Mushroom Roof Exhausters for industrial, commercial ventilation. 870 to 47,800 cfm. Bulletin CAM-102. Gyra-Flo Roof Exhausters--Extremely quiet for schools and hospitals. 830 to 29,750 cfm. 61 to 88 db. Bulletin GPE10S. ' . Centrifugal Fans for heating, ventilating, air conditioning, all drive styles. 600 to 750,000 cfm. Bulletin C-102. Propeller Fans for commercial, indus trial, business, home ventilation. 1200 to 24,100 cfm. Bulletin CEF-10S. Steel Plate Fans for removing dust, ma terials or high temperature air, gases. 200 to 50,000 cfm. Bulletin SPE-10S. Turbo-Pressure Blowers for oil or gas burners in industrial furnaces, ovens. 80 to 5500 cfm. Bulletin CTB-102. MD Fans for commercial ventilation. Direct or belt drives. 300 to 17,000 cfm. Bulletin MD-102. Air System Equipment Fans and Clarage '"-CLARAGE FAN COMPANY Kalamazoo, Mich. Air Handling and Conditioning Equipment Application Engineering Offices in All Principal Cities For nearly a half century Clarage has been a leading manufacturer of equip ment and units for ventilating, exhaust ing, cooling, air cleaning, humidifying and complete conditioning. Clarage equipment is designed to meet all types of industrial, commercial and public building requirements. For other equip ment in the complete Clarage line see "Air Conditioning-r-Central Systems." . Clarage Fans for ventilating and air conditioning are offered in many differ ent standard types and arrangements. Capacities range from 200 to 725,000 cfm. Clarage Unit Heaters are available for either floor or suspended installation. 23 sizes range from 24,000 to 1,160,000 Btu. They can be operated on either steam or hot water. Clarage Industrial Fans (shown above) range up to 130,000 cfm, 18 in. sp, and 60 in. inlet diameter. Can be constructed for special applications. Clarage Ready Units (left) are furnished complete ready-to-run. V-belt or direct connected. Capacities to 12,000 cfm. . We welcome your inquiry on any air handling or conditioning problem. Con tact our nearest branch office, or write us at Kalamazoo, Michigan. 1387 Air System Equipment Fans and Blowers DeBothezat Fans Division American Machine and Metals, Inc. Main Office and Factory--East Moline, Illinois Sales Engineering Offices in all Principal Cities Consult Your Telephone Directory Unber "Fans" or "Ventilating Equipment" FOR CONTROLLED VENTILATION Centrigugal Roof Ventilator is ideal for schools and hospitals where whisperquiet operation is a must. It runs at low speeds and moves large volumes of air efficiently against static pressures. Ca pacities up to 32,980 cfm. Centrifugal Roof VerUHator Vertical Discharge Roof Ventilator ex hausts oil or grease-laden'air straight up at high velocity. It keeps harmful resi due off the roof and thus prolongs roof life. Capacities up to 48,925 cfm. Vertical Discharge Roof Ventilator Power-Flow Roof Ventilator is most pop ular of all for general usage. It is a rug gedly built unit in an aerodynamically correct, weatherproof housing. Capaci ties up to 43,070 cfm. All three DeBothezat roof ventilators are low in silhouette and distinctively profiled . . . blend well with modern architecture. Write for separate catalogs, mentioning units by full name. Certified Capacity Ratings. All perform ance ratings are the output of the com pletely assembled unit . . . obtained from wind tunnel tests as per Standard Test Code for Power Roof Ventilators . . . and conform to U. S. Department of Commerce Standard 178-51. Power-Flow Roof Ventilator 1388 DeBothezat Fans Division Ah System Equipment Fans and Blowers FOR FUME REMOVAL BIFURCATOR FAN Bifurcator Fan exhausts hot, corrosive or flammable fumes. Motor is mounted in a through-ventilated chamber and de structive fumes are by-passed (bifur cated) around it. Bifurcators install directly in the duct, in any position from horizontal through vertical. Fan wheels 12 in. through 48 in. in diameter, with capacities up to 54,200 cfm. Write for Catalog. Bifurcator Fan INDUCED DRAFT BIFURCATOR Induced Draft Bifurcator provides con trolled draft for boilers and furnaces, eliminating the need for tall costly stacks. For high-pressure boilers de livering up to 60,000 pounds of steam per hour and for low-pressure boilers up to 190,000 EDR. Write for Bulletin. Induced Draft Bifurcator Hy-V` Air Jet "HI-V" AIR JET FOR SPOT COOLING AND GENERAL VENTILATION "Hy-V" Air Jets blow a directed stream of cooling air as far as 60 feet without ducts. Write for Bulletin. Additional bulletins are also offered on Axial-Flow Vent Sets and Panel Vent Sets. 1389 Air System Equipment Fan* "d Blowers Garden. City Fan Company 332 South Michigan Avenue Chicago 4, Illinois Representatives in principal industrial cities. Manufacturers of Design "B" Multiblade--Non-Overloading--Hi-Static Cycloidal Standard Steel Plate and Small Exhaust Fans. Wheels designed in forward curved, backward curved and radial bladed types, adaptable to commercial and industrial applications. Suitable for cooling, evaporating, drying, air-conditioning, ma terial conveying and disposal, processing foodstuffs and animal or mineral products and by-products, induced draft, paint spray and fume removal, packaged steam generators, and requirements for fan and blower systems. Standard Steel Plate fans also produced for high temperature operation 300 F to 1600 F, N.O.L. fans to 600 F, and Design "B" Multiblade fans for temperatures to 800 F. Non-Overloading Fan illustrates an an gular up discharge position. Fan in terior coated with resistant paint. Back ward curved fan blades. Large Design "B" Multiblade Fan for temperatures to 800 F, showing insulated cup and air-cooled fan shaft. Forward curved fan blades. Hi-Static Cycloidal Fans--used for sys tems handling and conveying many ma terials. Specially designed fan blade re duces power requirement and operates at slow-speed. Small Exhaust Fans--steel plate housing shown. Available with cast iron housing and direct-connected motor. Wheels, in. thru 16 in. O.D. High Temperature Fans to 1600 F. In sulated or uninsulated housings. Air cooled shaft with ball bearings. Engineering data, information, and cata logs, available upon request. Non-Overloading Fan Design "B" Multiblade Fan High Temperature Fan Small Exhaust Fan 1390 Hi-Static Cycloidal Fan Air System Equipment Fans and Blowers Plant Offices General Blower Company 8602 Ferris Ave., Morton Grove, I1L Sales Offices in Principal Cities :l A General Centrifugal Fans for complete range of volumes for heating, ventilat ing and air conditioning. Type SS (seal seam) housing construction. , B For Industrial applications requiring', heavier construction, General offers the type W (Welded) housing construction. C General Backward Blade and Forward Curved fan wheels and inlet cones are assembled of spun parts for smooth quiet air movement. Ask for Bulletins BB10S or FC-IOS for particulars. ------ ---- D General Propeller Fans supplied with either cast aluminum or steel blades from 10 in. to 72 in., with direct or belt driven arrangement. Bulletin PF101 E Inlet vane controls of General design are offered for manual or automatic operation. F Material handling Exhausters convey air borne particles caused by grinders,. polishing or cutting. General Steel Plate Exhausters are suitable for high tem perature air recirculation. Bulletin MX-104 G General Util-A-Vent sets of FC or BB wheel construction recommended for low cost air handling requirements for ventilating and industrial needs. Direct motor connected units for up to 12 in. fan wheels. Belted units up to 36 in. Bulletin UVS-103 H For removal of fumes and foul air where no duct system is required, General offers the Automatic Propeller type Roof Ventilator having vertical discharge. Bulletin PF-101 D General Power* Roof Ventilator, of low silhouette design having type BB cen trifugal fan wheel meets architectural design requirements. Aerodynamic de sign provides quiet efficient operation. Bulletin RV-101 ALL GENERAL FANS TESTED ACCORDING TO NAFM STANDARD TEST CODE. 1391 Air System Equipment Pans and Blowers Hartzell Propeller Fan Go. DIV. OF CASTLE HILLS CORP. Piqua, Ohio Engineering Offices In Principal Cities PROPELLER TYPE FANS Standard fans (shown) in single-propeller, two-propeller and multi-blade models, diameters from 12 in. to 60 in. Also Lo- Noise Fans, 24 in. to 60 in., and a special high pressure fan which operates efficiently against pressures as high as 3^in. water gauge. All can be supplied in direct-drive, belt-drive, pulley- drive or extension shaft construction--ring or panel mounted. Cast aluminum-alloy propellers. . .. VANEAX1AL BLOWERS For use in duct systems, against very heavy pressures. Directdrive' in six sizes, 18 in. to 42 in. Belt-drive in 10 sizes, 12 in to 54 in. Air deliveries to 88,000 cfm. Special high-temperature models move air at elevated temperatures; and air containing mild acids and alkalies, without danger of premature failure of belts and bearings. All-welded construction. Dynamicallybalanced cast aluminum alloy impellers. I 1 k i ;.s> DUCT FANS Standard duct fans are prefabricated duct sections which can easily and quickly be bolted into place in any duct system. Direct or belt-drive, 12 in. to 60 in. Bi-Pass Duct Fan has motor in tunnel out of air stream; for high temperature applications (up to 550 F with special heavy duty construction) and for moving corrosive fumes. REVERSIBLE FANS Move air in either direction with the same high efficiency .'Can be reversed manually or automatically. For many cooling and drying processes and for ventilating jobs where intake may be desired under some conditions and exhaust under other condi tions. Available in 28 in, 36 in. and 44 in. fans diameters, in duct section or double-ring construction. ROOF VENTILATORS The Vertijet (shown) or the Automatic Airjet attain unusual efficiency and economy through extreme simplicity of design. Lids open automatically when the fan is on, close weather tight when it goes off. Other ventilators include a Rotary Ventilator and a new Reversible Roof Ventilator which also meets all the requirements for a blackout unit. OTHER HARTZELL VENTILATING EQUIPMENT; Centrifugal blowers, man and materials cooling fans, intake air units, unit heaters, aluminum and plastic adjust able-pitch fans for cooling tower and heat exchanger applications and mine ventila tion. 1392 Air System Equipment Propeller and Centrifugal Fans ILG Electric Ventilating Co. 2880 North Crawford Ave., Chicago 41, 111. Offices in more than 40 Principal Cities ILG PROPELLER FANS, CENTRIFUGAL FANS, ROOF VENTILATORS Tested and rated by NAFM, PFMA and ASHVE code. Capacities guaranteed. Type "X" Ex plosion Proof Fans carry VL certification of suitability for all Class 1, Group D hazardous appli cations. Type "TA" Tubeaxial Duct Fans for pres sures up to 0.8 in. Easily installed duct section for vertical or hori zontal use. ILG DIRECT-CONNECTEDSELF-COOLED MOTOR PROPELLER FANS--Exclu sive self-cooling feature: motor covered for protection against corrosive and con taminating exhaust air, .but cooled by a vent, the entrance of which is outside the exhaust area. Motor never "gums up" from contact with foul air . . . saves on power costs . ^ . practically no maintenance required. Direct drive assures permanent align ment. Exceptionally quiet operation. Wide range of sizes. Volume Blower Type "B" left--Small volume, low pressure, quiet running. Cast iron base. Universal discharge positions, 7 capacities. Volume Blower Type "P" left--For exhausting dust, fumes, vapors. Four discharge positions, 7 capacities. ILG DIRECT-CONNECTED CENTRIFUGAL FANS, NEW AIRFOIL TYPE BC above, far left--Motor load is constant for wide range of volume and static pressure changes. Direct drive design with motor partially recessed, 10 sizes. Belt-drives in 12 sizes. TYPE LSQ--Direct-connected propeller fan type featuring low silhouette, low maintenance and high capacity, 5 sizes up to .6 in. static pressure. TYPE RVS--Centrifugal fan type, ideal for low volume requirements. 9 sizes up to .5 in. static pressure. 17 in. high above curb. Optional without dampier, Type RAS, 13 in. high above curb. ILG PRV POWER ROOF VENTILATORS--Centrifugal fan type, shown above left, tor exhaust from vertical flues or duot systems. Direct drive, self-cooled motor. in on-overloading, backward curved wheel. 10 sizes. Up to 1} in. Static Pressure. 1393 Air System Equipment Fans and Blowers JOY MANUFACTURINGCO. General Offices: Henry W. Oliver Building, Pittsburgh 22, Pa. MANUFACTURERS OF VANEAXIAL FANS UNITED STATES AND TERRITORIES Ala., Birmingham _, 601--10th St., N. (Crandall Eng.) Calif., Los Angeles 3. .5426 E. Washington Blvd. Calif., San Francisco 3.............. 1155 Harrison St. Colo., Denver 2 ,, 1626 Wazee St. (Schloss & Shubart) D. C., Washington 5.. .1000 Vermont Ave., N.W. Ida., Kellogg............................North 1 Division St. 111., Centralia.............................Fifth and Chestnut 111., Chicago 6................560 W. Washington Blvd. Mass., Boston 15.......................... 88 Brookline Ave. Mich., Detroit 27........................ 14225 Schaefer Rd. . Minn., Duluth............................1021 E. Superior St. Mont., Butte...............................24 W. Granite St. Mo., St. Louis 10...........................1203 Macklind Ave. N. Y., New York 6.................................140 Cedar St. Ohio, Cleveland 13. .2410 Terminal Tower Bldg. Ore., Portland 9.......... 1631 N.W. Thurman St. Pa., Forty Fort.......................................155 Welles St. Pa., Pittsburgh 13.............................4107 Sennott St. Pa., Philadelphia 2...............................1420 Walnut St. Tenn, Knoxville.............................108 W. Main St. Tex., Dallas...................................... 7425 Hines Blvd. Tex., El Paso...................................1022 Wyoming St. Utah, Salt Lake City 15. .1359 S. Second West St. Wash., Seattle 4.......................... 3410 First Ave. So. Wash., Spokane.................................S. 121 Monroe St. W. Va., Huntington.........................742 Eighth Ave. IN CANADA Alberta, Calgary......... .................Ill 3rd. Ave. E Nova Scotia, Sidney........................87 Charlotte St. Ontario, Galt................................... 175 Beverly St. Ontario, Kirkland Lake........... 24 Duncan Ave. Ontario, Sudbury...................................61 Eyre St. Ontario, Toronto......................... 208 King St., W. Quebec, Montreal.............................. 1275 Hodge St. IN MEXICO Mexico, Mexico City................ Insurgentes Sur 132 EXPORT OFFICES N. Y., New York 1.............. Empire State Bldg. Algeria, Aloiebb Compagnie Joy, S.A.4, Rue Charles Vallin Australia. Rosebery........ 56-58 Rothschild Ave. Belgium, Anderlecbt-Bbubsels 1 "1 Blvd. de la Revision Brazil, Rio de Janeiro ,. Caixa Postal, 54, Copacabana Chile, Santiago.................................................Casilla 86-D England, London W1.......................... 7 Carlos Place France, Paris. ...............................30 Rue de Chabrol Fr. Morocco, Casablanca . Cie. (Marocaine) Joy, S. A. Rue de Verdi Northern Rhodesia, N'Dola ^ v_ . JoySullivan (Africa) (Pty.) Ltd. Peru, t.tma....................................................... Casilla 3111 South Africa, Johannesburg .. 1 Steele St., Steeledale AND MORE THAN 500 DISTRIBUTORS THROUGHOUT THE WORLD SERIES 1000 AXIVANE* INDUSTRIAL AND COMMERCIAL FANS Joy Series 1000 adjustable blade AXIVANE* Industrial fans are available in 136 sizes ranging in volume capacity up to 200,000 cfm with pressures up to 11 in. W. G. Housing diameters range from 18 in. to 84 in. For complete speci fications, construction details, and selec- tor charts giving pressure-volume range for each fan, write for bulletin number J-611. . Joy AXIVANE* Series 1000 fans are efficient, quiet, compact, flexible, and easy to install. ,, ADJUSTABLE BLADES Joy AXIVANE* Industrial Fans have the extra performance flexibility of ad justable blades. Adjustable blades are standard equipment on all Series 1000 fans. The factory blade setting can be quickly changed to provide either a wide pressure range for any particular volume or a change in a volume simply by loosen- -yt m f? Blades are adjustable on the job bg loosening one lock nut Cutout drawing showing location of motor and compact construction 1394 Joy Manufacturing Co. Aij System Equipment Fans and Blowers Rear view, showing vanes and motor Front view, showing simplicity of construction ing a lock nut with a wrench, setting the blades uniformly with the indicator, and retightenjng the lock nut. A permanent stop prevents setting blades in a position likely to overload the motor. Minimum blade settings are limited by the fan housing. Adjustable blades permit on-the-job correction for unpredictable duct resist ance or for poorly installed duct work. MORE EFFICIENT Stationary straightener vanes, located immediately behind the rotor, partially recover the rotative energy imparted to the air by the rotor, and re-establish axial flow to the air leaving the vanes. This eliminates excess turbulence at the point where the air enters the duct sys tem and increases efficiency by decreas ing pressure loss. The Joy AXIVANE* fan utilizes an aerodynamically efficient blade and sta tionary vane design. . % QUIETER OPERATION For equal weight and space the Joy AXIVANE* fan is quieter than a centrif ugal type fan of equal volume and pres sure. The streamlined airflow from an AXIVANE* fan makes sound insulation a simple and inexpensive operation when required for the ventilation and air con ditioning of quiet spaces such as hospi tals, auditoriums, radio stations, etc., where insulation against system noise must be used. MORE COMPACT Joy AXIVANE* fans are built around the motor, the fan housing becoming an actual part of the duct system. This produces a more compact design than is possible with a centrifugal fan. An AXI VANE* fan, installed on an in-line con nection with ventilation ducts, parallel to and close by an overhead structure, may require 70 per cent less space than a conventional belt-driven centrifugal fan. The compactness of a Joy AXI VANE* fan assures a maximum of net operating or rentable area. Fan rooms are virtually eliminated. EASIER TO INSTALL The Joy AXIVANE* Series 1000 fan de velops a greater volume and pressure per pound of fan and motor because of its compact, in-line construction. This light weight permits a simplicity of in stallation that minimizes installation costs and total weight by eliminating heavy foundations, complex duct offsets and elbows, drives and guards. AXI VANE* fans can be installed quickly and easily, even by relatively inexperienced or un-skilled labor. MATCHED ACCESSORIES Inlet bells, screens, and fan supports are accessories designed to fit all AXI VANE* fan housings. In ordering, it is only necessary to state the model number with or without the accessories as desired. If required with accessories, these will be furnished to fit the fan model ordered without special number. No matter how carefully a duct system is planned, an incorrectly selected inlet bell will reduce fan efficiency by increas ing intake turbulence. This excess tur bulence will also increase the noise level of the fan. When a fan takes its air directly from the weather, a plenum, a fan room, or from a duct system larger in circumference than the fan housing, a bell should be used. Beg. U. S. Pat. Off. Air System Equipment Fans & Blowers 1 Blower Wheels The Lau Blower Company 2004 Home Avenue, Dept. J, Dayton 7, Ohio In Canada The Lau Blower Company of Canada, Ltd., Kitchener, Ont., Canada Manufacturers of Exhaust and Portable Fans, and Air Conditioning Blowers LAU all new `ELECTRO-WHEEL BLOWER: Two unobstructed air inlets on wheel sides plus compact motor design gives more air delivery with less power load. Stationary shaft with rubber mountings reduces vibration to a mini mum. Rugged tripod mountings give greatest shipping strength without im peding air now. Air deliveries from 500 to 1500 cfm, static pressure from .5 to 1.25 in. (water gauge), 34 hp motor. Available in 115 and 230 volt ac. Housing supports optional. Pre-punched holes in housing unit make any discharge angle possible. LAU Econo-Pak Blowers cover most applications for residential air-moving equipment; effect savings up to 10 per cent by eliminating special blowers for each application; reduce blower inven tories by simplified order procedures, quick handling of model changes, lower handling costs, up to 26} per cent re duction in warehouse space. Three Basic Sizes each in 2 widths, with all features of Standard Series A Blowers. Package Includes blower wheel, housing with cut-off, housing supports, motor mount (not attached), all hardware. Exclusive Lau-Pak Bearings without oil cups', require no lubrication. Adjustable Dis charge, any one of 5 positions. Write for LA U Blower Catalog 707. Mention all Blower items of interest. LAU Standard Blower Assemblies (Series A), heavy-gauge steel housing assemblies, entire unit die-formed. Capacity range 350-22,000 cfm. Motor Mounting adjustable for any motor location. Housing Base heavy 16-gauge steel, rigid. Discharge Outlet improved design, construction. Belt special com position for blower operation. Shafting 2-stage centerless ground, burnished. Bearing Bracket 3-point suspension; same bracket used for all discharge angles. Lausteel Pulleys employed; V.S. motor pulley allows speed variations up to 30 per cent. Center Suspended Wheel. Embossing of Scroll Sides reinforces, venturi inlet and discharge. Bearings highfest grade self-aligning porous, bronze sleeve type. Plastic. Thrust Washer absorbs shocks. LAU Spun Wheels, Center Suspended Riveted Wheels, S.I. and D.I. Weld Wheels, a complete wheel line. Spun Wheels center disc construction; baked enamel, Ruspruf, or hot-dip galvanized Trade-Mark t one Air System Equipment The Lau Blower Company 2004 Home Avenue, Dept. J, Dayton 7, Ohio In Canada The Lau Blower Company of Canada, Ltd., Kitchener, Ont., Canada Manufacturers of Exhaust and Portable Fans, Air Conditioning Blowers Lau Series A Bearing Lau-Pak Gold Seal Bearing LAU Series A and Lau-Pak Gold Seal Bearings are noted for their high per formance and longer life. Series A is a self-aligning, self-oiling bronze bearing held in housing under uniform spring pressure; bore sizes %, %, 1 and 1%6 in. Lau-Pak Gold Seal Bearings require no additional lubrication; ample supply of plastic petroleum is sealed in housing; bore Bizes %, 1, and 1%6 in. LAU Self-Aligning Pillow Blocks are low-cost, light-weight, oil-tight steel housings with porous bronze bearings. Hold much more oil than cast iron types. Durex bushing feeds oil to shaft by capillary action. Spring keeps spheri cal surface of bearing and ring in close contact. Long bolt slots permit inter changing with other makes of pillow blocks. Bore sizes available are %, 1^ie, 1, and ljHe in. finish; standard steel or Power Lock hubs. Center Suspended Wheels, blades double-riveted to end rings, arc welded to center disc, diameters 18 in.-30 in.; standard steel or Power Lock hubs. S.I. and D.I. Weld Wheels, individual blades of correct length, width, pitch; . baked enamel, Ruspruf, or plated; diam eters 4)<> in.-9 in.; widths 2)4 in.-9 in. Lausteel Variable and Constant Speed Pulleys are in balance and true-running. Lausteel Variable Speed Pulleys avail able in three standard bores: 34, %, and in. Diameter 3)4 in. OD. Allow speed variations up to 30 per cent for many drive combinations. Lausteel Constant Speed Pulleys available in diameters of 6 in. to 10 in., inclusive. Suitable for both "A" and "O" section belts. Lau also offers cast iron pulleys in diameters of 11 in. to 14 in. LAU Niteair* Exhaust Fans for residen tial, commercial, and industrial use. Niteair* Rancher, for homes with lowpitched roofs, pulls air up through ceil ing opening; four sizes: 24-30-36-42 in. Niteair* Panel Unit in standard and heavy-duty models, with four.blades properly pitched for greatest air* move ment; five sizes: 24-30-36-42-48 in. All Lau Fans carry PFMA Certified Ratings and VL Approval; also regular manu facturer's warranty. * T. M. Reg. U. S. Pal. Off. Variable Speed Pulley Constant Speed Pulley LA U Blower Catalog 707 contains full information on Pillow Blocks and Pulleys. Niteair* Panel Unit LA U Fan Catalog gives you complete details. Write for it. 1397 Air System Equipment Fans and Blowers Blower Wheels Morrison Products, Inc. A 33 Year Firm East 168 Street and Waterloo Road, Cleveland 10, Ohio Air System Equipment Fans and Ventilating Equipment THE NEW YORK BLOWER COMPANY SALES OFFICES 3145 SOUTH SHIELDS AVENUE CHICAGO 16 FACTORY, IAPORTE, INDIANA Representatives in Principal Cities FANS BLOWERS UNIT HEATERS MAKE-UP AIR UNITS HEAVY DUTY HEAT SURFACE Belt Drive Blower MORRISON COMPLETE BLOWER ASSEMBLIES AND PARTS Made exclusively for original equipment manufacturers of heating, ventilating and air conditioning products. MORRISON BLOWER WHEELS Are double width-double inlet in stand ard diameters from 10 in. to 20 in. and 6 in. to 20 in. wide. ONE-PIECE BLADE CONSTRUCTION Three-piece balanced assembly--onepiece blade and two pressed end rings of deep drawn steel. Never any loose M blades. Spot welded for lasting strength and quiet operation. MORRISON PARTS for manufacturers who want to build 4g| their own blower assemblies and thus ||| save approximately 50 per cent of their Blower Dollar investment. Ahv -it COMPLETE ENGINEERING SERVICE ||g Shop drawings, certified performance data, cost analysis. & ' ' .-pVr Morrison Catalog No. 603 Belt Driven Blowers, and Catalog No. 604 Direct Drive Blowers mailed upon request. Exploded View-Belt Drive Part* 1398 Propeller Fan Unit Heater M15--15,000 e/m un**' that delivers, warmed, filtered, outside air to industrial spaces to replace exhausted air and balance minus pressure. Corrects drafty conditions and uncontrolled in filtration. Made in 4 sizes from 5,000 cfm to 20,000 cfm. De scribed in Bulletin BBS. . IPL Centrifugal Fans--Capacities up to 101,000 cfm. Slow speed wheels offered from 7^ to 73 in. Capacities up to 123,000 cfm. Quiet operating (IPL) medium speed wheels with non overloading horsepower characteristics for heating, ventilating and air conditioning or industrial applications. Wheel di ameters from 18 in; to 73 in., with any speed or discharge required. Class I, II, III or IV construction. Write for Bulletins 543 and 644- . Steelfin Hot Blast Heating Surface--Extra heavy duty, finand-oyal tube, all-steel, welded construction. A hot dip metallic coating over all, including headers, affords perfect bonding and conductivity. Suitable for continuous heating service on steam pressures up to 150 lb. Bulletin 49S. Stedfin nyb Propeller Fans-^-Deliver large volumes of air at low re sistance and low current consumption. All wheels are machine balanced for smooth, vibrationless operation. Made in two types and eight basic sizes. Wheel diameters from 12 in. to 48 in. Direct or belted drive. Capacities from 400 cfm to 23,500 cfm. Ask for Bulletin 541- nyb Unit Heaters--Heavy duty, welded steel, fin-and-tube heating element. Suitable for continuous heating service on steam pressures up to 150 lb or more. 10 sizes with capacities from 30 Mbh to 490 Mbh. Bulletin BBS. Type GI Industrial and Heat Fans--For dust and gas removal, conveying of materials and handling hot gases. Housings, drives, and discharge arrangements to meet any requirement. Wheel diameters from 10 in. to 66 in. Capacities from 450 cfm to 60,500 cfm. Details and engineering data in Bulletin SSt. General Purpose Fan General Purpose Fans--Portable, self-contained units for Class I industrial and ventilating applications. Recom mended for ease of installation, low maintenance and space saving features. Made in three types and eight basic sizes. Capacities 400 cfm to 18,000 cfm. Bulletin 84s. 1399 J Air System Equipment Fans and Blowers Air System Equipment * Fans and Blowers II PROPELLAIR Divi The fy&ie4^86ect%ic Company ' ! ROBBINS & MYERS, INC. 1947 Clark Boulevard SPRINGFIELD, OHIO W. Market Street Warren, Ohio HEAVY-DUTY INDUSTRIAL VENTILATING Representatives in Principal Cities EQUIPMENT Industrial and Commercial Ventilating Equipment Offices in Principal Cities i t] UTILITY BLOWERS--Belt or. direct i drive with clockwise or counterclockwise rotation; % through 7J hp; motors in all ? current characteristics; convertible dis charge; arc-welded housing; sleeve or i BACKWARD CURVE BLOWERS--In ball-bearing construction; weatherproof sizes from 121^ in. to 49 in.; self-limiting drive covers optional. hp characteristics; NAFM standards; dynamically balanced wheel; heavy cast- iron hub; nothing in air stream; quiet entry, passage and exifcj job-matched motor; convertible discharge; belt drive or direct drive. I !'- i RADIAL BLADE BLOWERS--to 2 hp; slow and high-speed units; self-cleaning wheel; ball or sleeve bearing motors; dis charge as specified; base and housing of ARRANGEMENT 3-12 in. through 48 in. wheel; clockwise or counterclockwise rotation; convertible discharge; single or double width; motors and_ drives avail able; vibration bases optional; ball or sleeve bearings furnished. For Duett, Walls,S'Wtndows, Hoods, Roof Venti lators Propellalr Direct- Connected Fans For use wherever motors may operate within the air stream, from free air to medium and relatively high resistance. A compact, durable design with fan having two to six blades. Sizes: 12 in. to 60 in. Capacities :J ,020 to 85,000 cfm. Type "CD." ~ For Heat, Acids, Alka lies--Fumes, Gases, Dust Belt-Driven Propellalr Tube-Axial Type A complete fan unit in short duct section ready for installation in lines from 20 in. to 60 in. diameter. Type "CS" may be used for severe acid or alkaline condi tions, explosive fumes and gases. Type "CSV," for excessive temperatures, cir culates outside air through belt and fan shaft tubes to keep drive and bearings cool. Capacities: 5,075 to 78,000 cfm. For Heat, Moisture, Fumes, Dust, and Gases Propellalr Extended-Shaft Fans This design locates motor outside air stream when fan is installed in duct at right angle turn, elbow, "Y," or offset. Simple installation usually can be sup ported by duct without auxiliary brac ing. Drive shaft is enclosed and sealed within steel tube. Sizes: 12 in. to 60 in. Capacities: 1,020 to 78,800 cfm. Type "CE." Power Roof Ventilator Propellalr Sky-Blast Dependable and economical power roof ventilators. Butterfly dampers open wide the instant fan is started, close automatically as fan coasts to a stop, offer virtually zero resistance as heat, fumes, moisture, dust shoot high into air. Rain is prevented from entering by fan when operating. Drainage shed pre vents leakage when dampers are closed. Sizes: 16 in. to 60 in. Capacities: 2,800 to 78,000 cfm. POWER ROOF VENTILATORS--Direct or belt drive; 12 in. to 48 in.;600 to 25,000 cfm; complete with disconnect switch; totally enclosed motor; automatic shut ters; inside insulation; 16 gauge steel housing; baked enamel finish. INDUSTRIAL EXHAUST FANS--Verti cal or horizontal mounting; totally en closed motors; adjustable motor base; continuous duty; ball-bearing construc tion; cfm rating from 470 to 29,350; mount with 4 or 6 lag screws. 1400 Propellalr Vaneaxlal Fans Airfoil Principle Entrance Ring A compact, highly efficient pressure fan using standard steel drum sections incorporating standard NEMA frame motors in direct drive models. Also available in belt-driven ratings with motor outside the air stream. Cast alu minum airfoil propeller and guide vanes for naximum efficiency and durability. Available in 20, 24, 30, 36, 48, and 60 in. diameters in belt and direct driven models. Capacities from 3410 to 85,000 cfm. Airfoil-Section Blades Propellair fans have airfoil-section blades with variations of pitch, curva ture, and thickness to compensate for different lineal speeds of points at vari ous radii. Air movement is uniform over whole fan area. The Propellair curved entrance ring eliminates eddy currents; helps efficient Propellair blades deliver highest pressure and volume. 1401 Air System Equipment `Fans and Blowers (Rje.exL Unit-Fans, Inc. 1001 Saint Charles Ave., New Orleans, La. Manufacturers of Industrial, Direct-Drive Axial Flow Fans, Belt-Drive Exhaust Fans, Window Fans, Attic Fans and Portable Air Circulators REED INDUSTRIAL AXIAL-FLOW FANS The Reed APD Industrial Fan line consists of heavy-duty axial-flow direct-con nected fans capable of operating against static pressures up to 3 in. water gage, with air delivery ratings from 1,000 to 100,000 cfm. Cast aluminum air foil blades of unique design make it possible to vary the number of blades and their angle of attack, thus providing the necessary flexibility to custom-build to specific requirements. The basic line consists of four groups of sizes, namely 9 in. through 18 in., 21 in. through 27 in., 30 in. through 36 in., and 42 in. through 60 in. These groups are fur ther subdivided in 3 in. steps. Totally enclosed ball-bearing motors, either single or three phase are standard, but special motors are furnished on request. Fan frames are of heavy hot-rolled steel, electro-welded throughout. PP.TT.n PACKAGED ATTIC FANS Seven stock sizes ranging from 24 in. to 48 in. blade dia. Corresponding free air cfm ratings of from 5,000 to 18,600. Sim ply and quickly installed with hanging brackets on rafters. Completely auto matic shutters. REED PORTABLE AIR CIRCULATORS Supplied in 5 stock sizes; 22 in., 26 in., 30 in., 36 in., and 42 in. blade dia. Wire guards front and back, four hard-rubber casters at bottom of fan case. Completely vibrationless, two-speed and reversible. Ideal for commercial and industrial spot cooling. 1402 Air System Equipment 249 Edward Street Revcor Carpentersville, Illinois Phone: HAZEL 6-4819 ENGINEERS AND MANUFACTURERS OF SINGLE AND DOUBLE BLOWER WHEELS AND HOUSINGS Two single inlet blower wheels welded together back to back and having a common hub make up the REVCOR DOUBLE INLET BLOWER WHEEL. Any two REVCOR single inlet wheels of the same diameter and of the same or varying widths can be assembled to make the double inlet blower wheel. Heavy gauge. backplate and inlet ring assure rigid support for blades and hub. Individual blades of correct number, curvature, depth, and blade angle to deliver the greatest amount of air both efficiently and quietly. FULL WIDTH blades with a blade tip diameter substantially the same as the outside diameter of the wheel enable REVCOR BLOWER WHEELS to de liver the MAXIMUM AIR AND PRES SURE FOR THE SPACE DIMEN SIONS REQUIRED. Blade tips projecting through slots in the backplate and ring are bent toward the blade curvature to securely lock the backplate and ring between the bent tip and the shoulder at each end of the blade. Tips may be spot welded for greater strength when required for spe cial severe applications. Cast hubs are attached to the backplate with 4 or 6 rivets. Hubs can be mounted either inside, or outside of the wheel. SIZES: 1W in. to \2% in. Diameter; wheel widths from % in. Special Sizes of Single and Double Inlet Blower Wheels can be made to your specifica tions. Hubs machined from bar stock are at tached to the serrated center hole in the backplate by curling the hub material on to the backplate. The hub material is then pressed into the serrations in the backplate to key the hub to the wheel to prevent loosening. Hubs can be mounted either inside or outside of the wheel. MATERIALS: Steel. Also available in Aluminum, Brass and Stainless Steel. AVAILABLE: Sheet Metal Housings for all Revcor Wheels FREE REVCOR CATALOG Containing technical details, diagrams, specifications, and sizes of Revcor Blower Wheels. Write direct to: REVCOR, 249 Edward Street, Dept. R, Carpentersville, Dlinois 1403 Air System Equipment Fans and Blowers iseffltms- tHCtttimnte uutriD GALT. CANADA fiAT.res OFFICES: Montreal, Ottawa, Tobonto, Hamilton, London AGENTS: Halifax, St. John, N.B., Winnipeg, Calgabt, Edmonton, Vancouver Fan Manufacturers For More Than GO Tears Member Canadian Fan Manufacturers* Association. Silavenl Fans Keith Fans AIR HANDLING APPARATUS for every industrial, commercial, mining and processing need For more than 60 years this Company has been well and favorably known in Canada as manufacturers of high-qual ity air-handling equipment. SHELDON products are accepted as "EQUAL" to any other similar apparatus produced on the American Continent. Inquiries invited for specifications and full information on SHELDON Fans, Blowers, Exhausters, Heating, Ventilat ing and Air-Conditioning Apparatus, and allied equipment required on your Cana dian projects. Roof Ventilators A ir-Conditioners Utility Sets Air Conditioning Units Keith and Silavent Fans * Utility Sets Forced Draft Fans Induced Draft Fans Airscrew Fans Axial Flow Fans Medium Blowers and Exhausters Mill Exhausters Dust Separators and Collectors * Dust Filters Centrifugal Blowers * Unit Heaters Drying Equip ment Chemical Plant Fans Mine Ventilating Fans Axial Flow Fans Pressure Blowers Complete engineering data and catalogs available upon request 1404 ;-/ ' V -T -r"is Air System Equipment Fans and Biowerf Trade-Wind Motorfans, Inc. E'SrsSSS 7755 Paramount Bivd. Rivera, Calif. Cities. Carried in Stock By Many Electrical Jobbers CABINET VENTILATOR At left, Model 8601 for kitchen cabinets, shown with op tional Stationary Hood. SUPER CLIPPER MODEL 3S01. 550 cfm kitchen ventilator installs in cabinet directly over stove. The dual inlets, one directly over the stove, the other at ceiling level are equipped with cleansable metal filters. The unit has twin blowers, isolated and radio shielded 140 watt motor, 4-speed switch control and builtin back draft damper. Three optional hood styles are available. Finished in choice of copper or stainless steel, the Stationary Hood comes in standard sizes from 30 in. to 48 in. The Expansion Hood adjusts from 30 in. to 54 in. The stainless steel Fold-Under Hood comes in 39 in. or 42 in. sizes. CEILING VENTILATORS Trade-Wind ceiling ventilators are de signed for small rooms such as kitchen, laundry, den, ticket booths, offices and photographic darkrooms. They come in complete "unit package" assembly, re quiring only the application of a dis charge duct for installation. Units are Underwriters' approved and listed and carry a (pro-rata) five year guarantee. AXIAL FLOW MODEL AF-7M. Compact 300 cfm axial flow ventilator for ceiling or wall in 100 cu ft room. It can be in stalled between joists in ceiling or be tween studs in the side wall. No elbows are required for vertical discharge. 50 watt motor. Available with aluminum of ivory grille. .CLIPPER MODEL 2501. Shown above. 425 cfm for 2000 cu ft room. Dual cen trifugal blowers. 130 watt motor. Inter changeable horizontal or vertical dis charge, complete with grille and 4-speed switch. CLIPPER MODEL 1501. 300 cfm for 1000 cu ft room. Dual centrifugal blow ers. 105 watt motor. Interchangeable horizontal or vertical discharge, com plete with grille. CLIPPER MODEL 1201. 100 cfm for bathrooms only.- 50 watt motor. Hori zontal discharge, complete with grille. Optional time delay switch available. VENTILATOR/LIGHT MODEL 1701. 100 cfm for bathrooms. 50 watt motor, horizontal discharge. Features modern Alba-lite glass grille, with two light sockets. Unit is prewired to external switch box. May be connected to single or double switch. Optional time delay switch available. 1405 Air System Equipment ' Palis and Blowers Pan Blades THE / TORRINGTON MANUFACTURING COMPANY TORRI INI <3 TO N. CONNECTICUT VAN NUYS. CALIFORNIA OAKVILLE. ONTARIO 1i "Slinger Rings" for Assembled Fans "Slinger Rings" for Assembled Fans-- A rolled ring, L-shaped in cross-section, with riveted construction. Designed to adapt all popular sizes of assembled Airiatocrat fan blades for application in eliminating condensate from room air conditioners. Design allows considerable. flexibility as to diameter, location of ring on periphery of blade, etc., without expensive tooling. "P" series AIRISTOCRAT fan blades-- This fan blade has outstanding pressure characteristics and is widely used in room air conditioning units--many times with slinger rings. It is available in heavy gauge construction in all diameters and in light gauge construc tion on certain diameters for special applications. New "LU" Series One-Piece AIRISTO CRAT Fan Blades--An extremely quiet and very efficient one-piece fan designed especially for refrigeration and air con ditioning applications. This quality product is hand-set to assure accurate forming and alignment. Made of alumi num, pierced for all unit-bearing motors. Sizes: 7%, 8%, and 10 in. diameters. i m Rem "LU" Series One-piece Airislxral Fan Blades Torrington Airotor Blower Wheels are light, sturdy and inexpensive--incor porate new principles of design and con struction, which insure rigidity and concentricity. Single Width--Single In let wheel is of simple four-piece construc tion. No rivets or welds are used; concentric rib serving as backing for. blade strip is formed at same time as hub socket, insuring trueness of wheel. ' Rigid radial ribs prevent deflection by is?'thrust. Three thicknesses of metal in , rims make for maximum strength.. Excellent for many heating and venti lating uses. Manufactured in both aluminum and steel in 1% in., 2, 3, 3%, 1406 I The Torrington Mfg. Co. Air System Equipment Fans and Blowers Blower Wheels m, m, 4%, 5a, sm, m, &Ae, 7%,,, 72%2. and 11 in. diameters. Clockwise or counterclockwise rotation. Same sizes available in DA type double width, double inlet wheels. Torrington Airotor Blower WheelDouble Inlet--Spider End Plates. Has blades punched and formed in a single strip, rigidly held by flanged single piece end rings. Hubs are rigidly mounted by peening. Wheels of 2H in., 3, 2%, 72%2, and 11 in. diameter are available at present. Additional sizes how being developed. Airotor Blower Wheel--Single Width--Single Inlet Patents tSI,Q6S; t,t7S,695 Des. lt6,04S "E" Series AIRISTOCRAT Fan Blades--Outstandingly high efficiency is the chief characteristic of this fan blade. It delivers more air for any. given horse power. Size for size it looks bigger, more powerful. . Convincing proof of the superior per formance of this fan may be found in the NEMA and NAFM tables prepared as a guide to selection. The catalog con taining these tables and specifications will be mailed upon request. Specifications: Three-blade models in 10 in., 12, 14, 16, 18 and 20 in. diameters; four-blade models 8 in., 10,12,14,16, 18, 20, 22 and 24 in. diameters. Five pitches in most sizes. Aluminum blades, steel spider and hub. Airotor Blower Wheel Double Inlet--Spider End Plates Neoprene Hubs for Shaded Pole motors --designed to minimize the transmission and amplification of motor noises by the fan blade. These hubs are currently available in H, He, %, He, H in. diam eters for Torrington propeller fans up to and including 12 in. diameters. AIRISTOCRAT "M" Series--Master Ventilating (Attic Fan) Blades--Three outstanding features of this new design are: (1) Extremely high efficiency, which gives maximum cfm per horsepower; (2) knockdown construction which dras tically lowers shipping costs; (3) quiet operation--a point of major interest to the consumer. This all steel four-blade fan is manu factured for domestic application ex clusively, in 24, 30, 36, 42 and 48 in. diameters, in 40 deg pitch only. 1407 4-Blade Airislocral Fan "E" Series 4'Blade Airistocral Attic Fan *'M" Series Air System Equipment Blowers Viking. Air Products Division of National-U. S. Radiator Corporation 5601 Walworth Ave., Cleveland 2, Ohio Heating, Cooling and Ventilating Blowers for Furnace and Air Conditioner Manufacturers Air System Equipment Fans and Blowers Western Blower Company Main Office and Plant: 1800 Airport Way, Seattle 4, Washington Sales Offices in the Principal Cities West of Rock; Mountains In addition to standard (Top Horizontal, Bottom Horizontal, Upblast and Downblast) positions, motor can be mounted and outlet located in any specified posi tion. Both Belt Drive and Direct Drive Blow ers are available without foot mounted. Lock-on feet provided which you can mount in any position on your own pro duction lines. ' Multiblade Fans MUX Exhausters Utility Sets Turbine Multiblade Fans--forward curved blade, Type TR, or backward curved blade, Type "S," fans for heating, ventilating, mechanical draft, etc. Bulletins No. SO and SI. Mill Exhausters--single or double for material conveying exhaust systems, direct connected or V-belt driven.^Bulletin No. S2-S. Pulley Driven Utility Sets--V-belt driven, slow speed, quiet operating, for general utilityduct ventilating systems. Bulletin No. St. New Direct Drive Blowers Equipped with A or A hp motors. New 6-point motor mount test-proven to resist shipping abuse. Mount by feet in standard positions or by outlet in any other position. Brackets available if you choose to buy and mount motors at your plant. Universal Duct Blowers Designed to be mounted in duct work in any position required to boost air move ment for heating, cooling and ventilat ing. New 16 page "Viking Blower Assembly Work Book"--For use in specifying sample model blower assembly you need for test ing with your air conditioner, cooling tower, and evaporative cooler. Contents: 1. Air Selector Table for determining cfm 2. Blower Capacity Table 3. Speed Ranges of Variable Pitch Pul leys _ 4. Dimensions of Blowers in all positions 5. Motor Location Grid for 9 in., 11 in., 13 in. blowers . . . with acetate tem plate guide 6. Belt size tabic for all motor positions 7. Effect of side and rear wall clearance on performance 8. Effect of blower outlet and furnace drum clearance on efficiency 1408 RB Volume And Pressure Fans--radial blade type either direct connected or V-belt driven for ventilating and conveying applications. Bulletin No. S9. . Western Unit Heaters--vertical or horizontal, for general heating and drying appli cations. Bulletin No. SS. Centrifugal Exhaust Fans Series 59--for general exhaust systems. Complete packaged units. Bulletin No. 59. Atr Washers r Mi vuvv, ijytlUWUG Propeller Fans Air Washers--for cleaning, cooling, humidifying and dehumidifying. Bulletin No. SO. Volume Heaters--with one or more centrifugal fans for heating, ventilating and air conditioning. Available in vertical or horizontal cabinet units. Bulletin No. 54. Spirovane Propeller Fans--furnished either direct connected or V-belt driven for commercial or industrial ventilation. Bulletin No. 50. Olympic Heat Exchangers--Converters, Side Arm Heaters, Immersion Heaters, Oil Heaters, and Condensate Coolers. . Bulletins as listed above furnished upon request 1409 Air System Equipment Blowers Westinghouse Electric Corporation Slurievanl Division Heating, Ventilating, Dust Control and Fume Removal Equip ment, Electronic Air Cleaners, Mechanical Draft Equipment Hyde Park offices in Principal cities Boston 36, Mass. AIR HANDLING PRODUCTS Centrifugal Fans--General purpose and Heavy Duty centrifugal fans are highly effective in both commercial and indus trial service. Capacities up to 480,000 cfm and pressures up to 32 in. w.g. Axial Flow Fans--Axiflo fans are designed to operate against resistance, are avail able for either vertical or horizontal air flow. Widely used in industrial heating, ventilating and fume removal. Ventilating Sets--Series 900: direct con nected units for maximum efficiency at popular motor speeds. Manufactured in six sizes up to 3200 cfm. Series 1000: com pact V-Belt driven units for large capac ity and quiet operation. Twelve sizes up to 14,400 cfm. Air Handling Units--For year-round air conditioning, also available for heating and ventilating or ventilating only. They feature sectional construction, various types of coils, and accessories to give combinations to suit the application and space. Capacities to 23,000 cfm. Stlentoane Centrifugal Fan Design 10 Direct-Connected Ventilating Set HEAT TRANSFER PRODUCTS Heat Transfer Surfaces--Sturtevant cooling and heating coils are available for Freon, chilled or not water and steam. Steam coils are of standard, heavy duty steam, and steam-distributing types. Air Blenders--For both winter and sum mer conditioning of individual rooms, air blenders mix conditioned air from a central system with recirculated air. Surface Dehumidifiers--For central plant air conditioning, these sprayed coil units are available with chilled water or direct expansion coils. Capacities to 115 tons of refrigeration and 45,000 cfm. Air Handling Unit Type AH Air Blender UNIT HEATERS Industrial Heaters--For heating of man ufacturing areas, warehouses, garages and general. industrial and commercial buildings. Also for continuous duty heat ing in industrial processes and steel, paper and rubber manufacturing. Capac ities to 2,500,000 Btuh and 25,000 cfm. Propeller Fan Heaters--Available for steam, hot water and gas-fired applica tions in., horizontal and downblast Surface Dehumidtfier models. Capacities range from 20,000 to 400,000 Btuh, Downblast Speedheater 1410 Axiflo Fan Design t A V-Belt Ventilating Set Direct Expansion Type EA Evaporator Coil Industrial Heater Horixontal Speedheatcr Air System Equipment !S<!teei Kewaunee Manufacturing Company 5119 South Center Street, Adrian, Michigan Representatives in principal cities. Products: AIRFLOW control fume hoods--CONVENTIONAL fume hoods--SPE CIAL purpose hoods--C.B.R. SYSTEM laboratories and components--LABORA TORY EQUIPMENT--wood-metal construction--HOSPITAL casework--EDUCA TIONAL equipment--LABORATORY SINKS and SERVICE FIXTURES. Catalog No. 3601 (Stainless steel interior) (7i in. long, 38 in. wide, 84H in. high) Safe operation for personnel protection and comfort is paramount with Airflow fume hoods. Aerodynamically efficient, modern design enables Airflow hoods to operate at lower face velocities. Gently1 curved, streamlined entrance shapes at the hood face decrease turbulence--in crease efficiency. Airflow hoods operate at 50 lineal feet per minute minimum face velocity, thereby effecting reductions in cost of operation for heating and cooling sys tems. Automatic bypass results in con stant-volume exhaust regardless of sash position. Hoods are available in various sizes in addition to those listed below.Interior lining materials include stain less steel, Kemstone and Transite. Ex terior of hoods is carbon steel with acid resistant painted finish. Recommended Min. Face Velocities and Total cfm Length of Hood 4 ft 5 ft 6 ft 8 ft Overall Dimensions 49* x 38' x 84H' 61'x 38'x 84 H* 72' x 38' x 84tf' 96' x 38' x 84H' Min. Face Total cfm Velocity @ sp 50 fpm . 50 fpm 50 fpm 50 fpm 375' 500 \ 625 875 Automatic bypass-constant volume hoods especially adaptable for air conditioned laboratories. The bypass is completely open in the down position of the sash. Air enters through the bypass and purges the interior of the hood. Use of the bypass limits the maximum air velocity such that disturbing air currents cannot be induced within the hood. This bypass is positive and completely automatic--there are no moving parts, controls or linkages to require service and maintenance. Operation of the bypass is controlled solely by positioning of the sash. Booklets on "Airflow Fume Hoods" and "Airflow Control Fume Hoods Characteristics and Applications" are available without charge or obligation upon written request. The Kewaunee Manufacturing Company's two modern plants in Adrian, Michigan, are equipped to design, engineer, and manufacture nuclear laboratory equipment, and scientific laboratory furniture. One of our field engineers will gladly visit you, upon request, to discuss the requirements of the job you have in mind and to offer any service possible without cost or obligation. 1411 Air Air System Equipment Hoods E. H. Sheldon Equipment Company Muskegon, Michigan SHELDON INDUCTION FUME HOODS Manufacturers of Laboratory Equipment for Schools, Industry, and Hospitals. SHELDON'S induction hoods are designed for use in air-conditioned laboratories or in any situation where it is necessary to conserve room air. By injecting regulated volumes of "out door" air into the working areas of the hood to supplement the primary airflow from the laboratory, the following con trolled conditions may be achieved: 1. Sufficient volume of air passes through the working areas of the hood at the face velocity required to insure com plete evacuation of fumes from the system. The exhaust system of the Sheldon induction-type hood handles the same volume of air that the exhaust system of the conventional hood handles at a face velocity of 70-80 linear feet per minute. 2. At the same time, air movement from the room into the hood has a low enough velocity to minimize turbulence within the hood and assure quiet operation, and to prevent objectionable drafts in the work area, and excessive drain on the heating, cooling, and air-conditioning systems of the room. The difference be tween the exhaust volume and the vol ume of intake from the room is provided by adjusting the supplementary-air supply. 3. Sufficient volume of air flows into the hood from the room to carry generated fumes into the fast-moving, high-volume evacuation air currents, and also to in sure optimum laboratory air changes. If air movement from adjacent parts of the building to the laboratory is desired, a condition of negative pressure in the laboratory may be induced by lowering the supply-fan capacity or increasing the exhaust-fan capacity. Also, even if the front sash is closed, the hood will purge of fumes because a definite part of the exhaust capacity is still being supplied mechanically and passes through the hood. Except for minimum filter requirements, provided for in the hood design, supple mentary air seldom needs to be treated, since it does not enter the room. The following table gives the velocity, velocity pressure and total entrance loss for both exhaust and supply for various lengths of hoods with duct sizes as shown in diagrams below. These values are for volumes as shown. These values are based on exhaust fan capacity capable of producing a face velocity of 75 lfm with only the exhaust fan operating and with a supply fan capable of introducing % the exhaust capacity and producing a face velocity of 25 lfm with both fans operating. 1412 | 1 Air System Equipment Exhaust Hoods E. H. Sheldon Equipment Company Muskegon, Michigan SHELDON INDUCTION FUME HOODS Manufacturers of Laboratory Equipment for Schools, Industry, and Hospitals. EXHAUST @ 75 L.F.M. face Vel. SUPPLY @ % of exhaust Hood Length 3" 4' 5' 6' 8V' cfm 487 690 900 1087 1275 1500 Vel 21080000 2000 21090000 2000 VP 0,20 0.25 0.25 0.23 0.25 0.25 * Entrance Loss 0.30 0.37 0.37 0.42 0.44 0.44 cfm 324 460 600 724 . 1805000 Vel 1900 1800 1650 1400 1600 1800 VP 00..2230 0.17 0.13 00..2160 1 Total negative static developed by the hood. The conversion factor to obtain entrance loss from velocity pressure is 1.5 for 3 ft, 4 ft and 5 ft hoods, and 1.75 for 6 ft, 7.ft and 8 ft hoods. ** Total positive static developed by the hood. The conversion factor for all hoods for the supply air static is 1.5. These statics should be added to the duct resist ances when computing fan sizes. Entrance Loess 0.34 0.30 00..2260 0.24 0.30 a- HOOD 5' Hood operating under the above conditions. The duct stubs are located on the top of the hoods as shown. The supply air can enter from below when building condi tions require such arrangement. The values given in the table, for various lengths of hood are for average condi tions. Consultation is solicited without obliga tion on other or unusual conditions. Since the hoods use a definite volume of "conditioned" air, their requirements should be considered very early in the work of designing and specifying heating and/or conditioning plants. Sheldon engineers welcome new problems arising out of recent production and development programs. A laboratory at Muskegon is maintained for this purpose. A list of satisfied users of a wide variety of industrial installations is available upon request. Contact the Muskegon office for the field engineer nearest you. 1413 Air System Equipment Roof ventilators Allen Cooler & Ventilator Inc. Rochester, Michigan Representatives in Principal Cities See Sweet's Catalog for Farther Details Write to Factory for Catalog Air System Equipment Air Vents and Roof Ventilators im l,. Ammerman e;o. 110 North Second St., Minneapolis 1, Minn. EXHAUSTERS Write for specU engineers bulletin Exhausters Powered or Gravity Ujiderfloor and Overhead Systems See Sweet's file for further details BACKWARD CURVE DIRECT CONNECTED POWER ROOF EXHAUSTER LOW SILHOUETTE ROOF FAN Allen "I-Line" Roof Fan is designed to meet the architect's demand for an at tractive low silhouette and the engineer's demand for high efficiency. This is ac complished by use of a circular spun steel hood,, and venturi, with baffle so arranged in relation to the propeller as to -.provide" maximum efficiency with minimum over-all height. Its appearance an,d. quiet performance recommend it for new or old construction, such as schools and offices as well as industrial plants,. It is easy to install (no extra base required)'and it.is easy to lubricate and clean. Available with Direct Drive (450 to.-34,000-fefm). or with-Bell Drive (4,000 to 2O;150icfin.) * VERTICAL DISCHARGE FAN Allen Type "VD" Roof Fan is designed for use where extremely high discharge velocity prevents the tendency of fumes to short circuit back through building openings. Fabricated of prime zinccoated iron sheet, welded construction throughout. Automatic wing dampers open with air blast, close weathertight when not operating. Available with Direct Drive, with motor readily acces sible, or Remote Drive, with motor in outside housing and enclosed V-belt drive. "BCD" Non-Overloading Roof or Wall Exhauster. Designed for optimum per formance at lowest possible velocities, reduces noise level to an absolute mini mum. Motor directly connected to dy namically balanced wheel eliminates costly maintenance. BELTED ROOF EXHAUSTER "PB" or "PFAS" Lo-Boy Wall or Roof Units. Efficient and quiet operation for low static pressures up to % inch.Rubber grommets are installed around all.points where metal contacts metal. Powered fresh air supply units on "PB" exhauster with reversed pressure blade to bring fresh air in under power. DISAPPEARING EXHAUST SYSTEMS { . - STAXAUSTER FAN Allen Staxauster is a simple, compact, sturdy unit that can be used to convert all types of roof ventilators into power ful exhaust or air supply units. It is available in many sizes with either Direct Drive or Remote Drive for handling corrosives and/or high temperature air. TURBINE VENTILATOR Allen Type "C" Turbine Ventilator is ' wind driven and economically removes heated air, fumes and dust. It is made of heavy-gage coated iron or of special non-ferrous metals, and is easy to install and maintain. Many thousands of Type "C" Turbines are in use in industry. 1414 -rim ?CB" Lo-Boy Non-Overloading Cen trifugal Wheel. Capacity table offers a selection of 16 wheel sizes--204 constant speed combinations with tip-speeds as low as 2000 fpm. Unit is exceptionally low in height. Standard construction consists of welded structural steel frame, heavy 16 gauge mild steel. Storm band and motor cover is 18 gauge. Under the Floor and Overhead exhaust systems for all makes and models of cars and trucks. Will accommodate flexible metal hose up to six inches in diameter. Write for Bulletin No. 6S0H. Patents No. 2571513-26666378. Others Pending 1415 Air System Equipment Air vents THE G. C. BREIDERT CO. P.O. Box 1190, Sain Fernando, Calif. Representatives in Principal Cities of the United States & /&vj- v' -4/ IS i MANUFACTURERS OF VENTILATORS FOR EVERY NEED! p ^ There is a Breidert Air-X-Hauster for every ventilation problem. Breidert guarantees J|| POSITIVE VENTILATION UNDER ANY WIND CONDITION, barring interna] |g negative pressures! FOR ROOF VENTILATING: If |f THE NEW BREIDERT POWAIR-XHAUSTER-- The latest addition to the Breidert line of Air-X-Hausters is this low silhouette power unit. Its unusually large capacity against high static resistance is made possible by horizontal discharge. The top-mounted motor is kept cool and trou ble free by ingenious use of outside air. Continues to operate by gravity action when power is off! FOR CHIMNEYS Breidert Air-X-Hauster Chimney Tops overcome sluggishness caused by down drafts . . . have produced excellent re sults on Industrial, Commercial and Residential applications. THE ORIGINAL BREIDERT AIR-X- ^ HAUSTER-- A gravity flow ventilator, stationary with no moving parts. Widely used on all types of factories, commercial buildings and residences. Breidert Air-X-Hausters pioneered with published certified capac- 7^ ity ratings based on tests* made with wind blowing in all directions as shown, Only such tests can guarantee the capacities -3 - a ventilator will deliver under actual op- crating conditions. .4.^ FOR GAS APPLIANCES The Breidert L. S. Vent Flue Cap assures - f positive ventilation with complete, safety. Pilot lights cannot be blown out, barring internal negative pressures! In every case where Breidert Air-X-Hausters were properly installed they have . never failed to function as advertised. lift' Write for Free Engineering Data Book containing detailed specifications and in stallation data and certified capacity ratings. .r-s-i Pittsburgh Testing Laboratories 1416 Air System Equipment * ventilators The Gallaher Company 4108 Dodge Street, Omaha 3, Nebraska Representatives in Principal Cities of USA and in Canadajby Canada Fans Ltd., Montreal Manufacturers of AIR-VAN and AIR-MAX Power Roof Exhausters Series I, 2, 3, 4, AIR-VAN Direct Drive Capacities 150-11,700 cfm. Static Pres sure to 4 in. Low installed silhouette design with motor out of airstream for protection against fumes. Exclusive Gallaher scroll effect design. Shipped as complete package ready for installa tion. Series 1, 2, and 3 have forwardly curved wheels with blades at varying angles. Series 4 has backwardly curved non-over-loading wheels. Choice of wheels allows buyer to tailor-make unit and select exact capacity desired. Rat ings are certified by an independent laboratory. Series 5 AIR-VAN Belt Drive Capacities 1,000 to 65,000 cfm. Static Pressures to 4 in. The one belt driven power roof exhauster with guaranteed high static pressures and air volumes. Motor out of airstream. Patented scroll effect design. Shipped as complete pack age including base. Does not require extra height for unobstructed discharge. Extremely heavy construction. Certified ratings by an independent laboratory. Weatherproof under extreme conditions. AIR-MAX Downblast Model C Capacities 1,000 to 44,000 cfm. Static Pressures to in., and more on special order. Designed to handle relatively dry air at minimum horsepower. Low sil houette. Economical direct connection to duct system without field assembly. Fully blackout. Certified Ratings. Can be furnished for summer or winter supply as well as exhaust. Propellers incorporate latest features in air foil design--four or six blades. Can be replaced without buying new wheel. AIR-MAX Upblast Model CU Capacities 1,000 to 44,000 cfm. Static Pressures to Jj) in. and more on special order. Designed for upward discharge. Special clam shell type dampers give weatherproof protection when units are not in operation. Units have low sil houette characteristics of all Gallaher units. Sturdy construction throughout. Damper stops prevent locking in the open position. Units can be supplied in Aluminum, Copper, Monel, Stainless Steel, and in any resistant finish. For complete catalog information including certified rating tables, and all pertinent selection and installation data, write The Gallaher Company or contact its representatives. 1417 9 Air System Equipment Roof Ventilators nr 1 illr > in | SuSjtet ta 7/taqic tJWW \ ufmrnm 4273 So. Broadway Los Angeles 37, Calif. Multi-Functional Powered Roof Ventilators con on boo* eta MODEL ER (Exhauster and Patent No. 170038! Recirculator) Other patents pending MODEL ES (.Exhauster and MODEL PRE (Power Supplier) Roof Exhauster) MODEL RS (Recircu- DELUXE MODEL ERS lator and Supplier) (Exhauster, Recirculator and Supplier) Unit selection table dependent upon roof height (To be used with all models except Power Roof Exhausters) Max. Roof Height--To 12' 14' 16' 18' 20' 22' Over 22' Genie-Air Unit Size-- 15 17 19 21 25 31 38 GENIE-AIR Performance Data For All Models a Unit size 1 Volt- e d JS sx *615-10 1000 1140 15-14 1400 1140 1 1 115 115 w17-18 1800 114C V* 1 115-230 17-22 2200 1140 1 115-230 Drive DD DD DD DD Weight PRE ER 70 80 70 80 75 85 75 85 119-27 2700 1140 u 115-230 19-30 3000 1140 1 115-230 DD DD 85 95 85 95 M21-33 3300 1140 1 115-230 H21-37 3750 1140 1 115-230 DD DD 100 110 100 110 M25-41 4100 1140 1 115-230 K25-47 4700 1140 1 115-230 DD DD 150 160 150 160 *$31-55 5500 850 V* 1 115/230 31-65 6500 750 1 115/230 31-80 8000 750 a 1 115/230 BD BD BD 260 300 260 3C0 265 305 l38-10 10850 900 *$ 3 220/440 BD-DD 310 360 38-13 13000 545 3 220/440 BD 315 365 38-14 14400 1140 1 3 220/440 DD 315 365 IH38-16 16800 1140 3 220/440 DD 320 370 GENIE-AIRS exhaust, recirculate, sup ply or mix recirculated and supply air-- any 1,2,3 or all 4 functions with the same unit. MODEL ER exhausts in summer and re circulates in winter. During the recircu lating cycle the butterfly dampers, which seal the opening between the roof jack M3 collar ana sleeve section, remain in closed position and the heated air trapped at the roof line is recovered through the opening between the venturi 'll fe and jet and returned to the occupied area; thus improving the efficiency of the heating system and reducing operating costs as well as initial costs. The cycle of operation may be changed at any time through a three-position switch or ther # mostat. In new design the amount of heat normally required can be greatly reduced when used in conjunction with these units. This model, with slight modifications, can also provide for sup ply of fresh air. ft fI iMODEL ES either exhausts or provides for supply of fresh air merely by revers ing fan rotation through a three-posi m tion switch. MODEL PRE is a typical power roof ventilator. This unit is equipped with butterfly dampers, which prevent heat fif? jiffloss in winter. Domes are optional. MODEL RS recirculates or supplies; also, any proportion of recirculated and supply air may be obtained by varying the opening between the venturi and jet thru a manually, pneumatically, or elec trically-operated mechanism. Filters are optional. DELUXE MODEL ERS provides all four functions listed above. Filters are op tional. Raise the sleeve or fan section for recirculated or exhaust air and close it for supply. The sleeve or fan section is raised or lowered by: (1) gear ratio motor and rack assembly, controlled either by a three-position switbh or ther mostat or (2) manual mechanism. This model available in sizes 31 and 38 only. NOTE: Cfm delivery of all models has . been calculated on the basis of the static pressure through the unit. As the per centage of cfm delivery is reduced when fan blade rotation is reversed, specify on which cycle of operation the greater cfm is required. Units having larger capaci ties or special combinations of fan blades, motor sizes and speeds are avail able on special order. 1418 Genie-Air Air System Equipment Roof Ventilators Dimensional Data Dimensional Chart For All Genie-Air Models Size 15 17 19 21 25 31 38 CD 16 18 20 22 26 32*$ zm DD 34 38 38 42 45 54 59 WBS 19 21 23 25 31 35 44 SSD 15 17 19 21 25 31 38 FSD "U Diana." 15 22*$ 17 25 19 26 21 28 25 33 31 39 38 48 Dimensions in Inches Models ER, RS, ERS Models ES and PRE See charts below for A, B, A SL dimensions. Type 1 and Type 2 roof jacks, as illustrated below, are furnished with all Genie-Airs. Any model may be installed in either type of roof jack; however type 2 is preferred because of its simplicity of installation. In either case, CD dimension plus 2 in. must be held vertically clear downward through the full length of equipment be low the underside of roof. Unit sizes 31 and 38 require support in addition to the roof jack: Support is to be furnished by others. See suggested method for framing or support. The Following Dimensions Are to Be Used With Type 1 Roof Jack: Genie Air Size 15 17 19 21 25 31 38 Models ER, RS, and ERS A *SL *B 27 27 37 29 27 38 29 27 38*$ 35 27 39*$ 39 27 43*$ 42 27 51*$ 44 28 52*$ Models PRE Models ES A *B A *B 27 16 27 17 29 16 29 17 29 16 29 17 35 16 35 17 39 17 39 1742 18 42 17 44 19 44 18 . * Dimensions (in inches) Based on 12 in. Roof Jack Height But May Be Varied. wwwwuu*uw iur,inw>3 . TYPE 1 ROOF JACK--"RO" (roof jack opening-- inside dimensions) for unit sizes 15,17,19, 21 A 25 is 28 in.x 28 in.; size31 is 35in. x 36in.; size 38 is 42 in x 42 in. TYPE 2 ROOF JACK--B2 (inside dimensions of roof jack base) for unit sizes 15,17,19 A 21 is 31 in.x31 in., CH (collar height above base) is 6 in., F2 (finish surface dimensions of curb) must be 30*$ x 30*$ in.; B2 for unit sizes 25, 31 A 28 is 43 in.-x_43_ in., CH is 8 in., F2 must be 42J<$ in. x 42*<$ in. All curbs must be 6 in. minimum cn high side of roof. The Following Dimensions Are to Be Used With Type 2 Roof Jack: ' GenieAir Size 15 17 19. 21 25 31 38 Models ER, RS, and ERS Model PRE A SL *B A B 21 27 43 21 22 23 27 44 23 22 23 27 44*$ 23 22 29 27 45*$ 29 22 33 27 49*$ 33 23 36 27 57*$ 36 24 38 28 58*$ 38 25 Model ES A B 21 23 23. 23 23 23 29 23 33 24 36t 25 38 26 Dimensions (in inches) Based on 6 in. Curb Height (High Side of Roof) But May Be Varied. OUrrWAUll (J OUlZO CC Oo Typical Installation With Steel Frame Support Typical Installation With Wood or Steel Frame . Support NOTE: On flat or slightly pitched roofs 14-gauge steel collar may be connected above roof decking with necessary support framing on underside of roof. NOTE: Conformance of installations with local agencies and governing codes is the responsibility of others. SUGGESTED ELECTRICAL SWITCH WIRING USING 3-POLE DOUBLE-THROW SWITCH See our complete catalog in A-E-C Catalog File or write to above address. 1419 Air System Equipment R^vStiStaa S; Hirschman-Pohle Co., Inc. Since 1908 200 Lent Ave. . . . LeRoy, N. Y. Sales Representatives in Principal Cities Manufacturers of all types of Power and Gravity Roof Ventilators * 3% || .fe- Minimum Overall Height (So Desirable for Modern One-Story School Buildings) Bool opening "A" Cowl height 'C" 10* 12* 15' 18* 20' 24' 30' 36' 5H* 6' 7' 8' m* 11' 12* 14' The Hirschman Type "CAF" Electric ventilator shown has been designed in response to a demand for the absolute minimum in overall height above the roof line, and as standard construction uses our INSULATED DOUBLE SHELL STEEL CURB of any of the several types for any kind of roof deck. Fan and motor assembly avail able for a wide range of capacities at the lower static pressures. The companion Type "CA" gravity or pressure relief ventilator (not shown) uses the same general construction minus the fan and motor. Either type subject to numerous modifications to meet the needs of any building project. Con* removable ` for servie* f & 'Spring & Rubber Vibration Absorbers Our Type "LA" STATICK Power ventilator designed for efficient exhaust at either low or high static pressure, using non-overloading backward curved blade centrifugal fan, available in many sizes for almost any required capacity within reason. Note the damper housing above the top of the curb providing ready access to whatever type of damper is used. The Type "LB" STATICK Power ventilator (not shown)- uses a similar construction minus the damper housing. . See Sweet's Architectural, Engineering, or Industrial Construction Files. Complete data on any or all types gladly furnished on request. mo * r. Air System Equipment .Power Ventilators Air Intakes Muckle Manufacturing Co. 666 Belford Road Owatonna, Minn Sales Engineering Representatives in Principal Cities MUCKLE VENTS--are ideal for moisture laden applications or corrosive condi tions. Motor is located out of the air stream, and housing is hot dipped gal vanized after fabrication for maximum protection. Capacities 254 to 10280 cfm. Units very efficient at low static pres sures. Constructed from heavy gauge steel, electrically welded. MUCKLE LO-SIL--designed for low sil houette appearance. Largest unit only 25J-2 in. high. Capacities from 225 to 17,600 cfm. Automatic back draft damp ers built in on all models. Vibration separators are provided to eliminate vibration and hum. Totally enclosed, ball bearing motors are directly con nected to propeller. MUCKLE, BC VENT--Centrifugal back ward curved wheel is ideal for operation where static pressures are encountered. Non-overloading, dynamically balanced wheel, directly connected to totally en closed motor. No maintenance of belts, pulleys, or bearings. Motor is out of air stream for protection. Capacities from 280 to 7650 cfm. Heavy gauge construc tion. MUCKLE BELTED VENT--offers over 100 different capacities for any specific requirement. High exhaust capacity uti lizes low fan tip speed to make unit very quiet in operation. Low in height, com pact and symmetrical design, blends well with modern architecture. Heavy duty, ball bearing motors and non-overloading backwardly curved wheels used on all units. manufacturers of power roof ventilators FOR OVER 15 YEARS SEE SWEETS ARCHITECTURAL OR INDUSTRIAL FILE, OR COMPLETE DATA 1421 Air System Equipment "Senators ENN VENTILATOR COMPANY W Goodman above Allegheny Avje. Philadelphia 40, Penna. Representatives and Distributors in Principal Cities. Roof Ventilators and Accessory Products for PUBLIC, COMMERCIAL AND INDUSTRIAL BUILDINGS DOMEX--V-belt and direct driven cen trifugal fans in a weather-tight spun aluminum housing. Backwardly curved statically and dynamically balanced fan wheels with non-overloading characteris tic. Over 40 capacity selections. PENN DYNAFAN--Quiet, steady ex haust against system resistances. Cen trifugal fans in sixteen sizes belt-driven at speeds to fill many capacity require ments. . AIRETTE--Efficient fans housed in easily installed modern, and inconspicu ous roof mounted housings. Certified capacities from 9,000 cfm to 40,000 cfm. HI-EX--Straight thru--high velocityvertical discharge air exhausters-- streamlined housings. Certified capaci ties from 2,400 cfm to 60,000 cfm. TURBINE--Ball bearing turbine venti lators are true rotary, air-driven suction turbines that work automatically and continuously without maintenance or operating expense. Ball bearing action enables the slightest motion of air to move the rotor. PULLMAN--Efficient gravity roof venti lator with large protected outlet area. Large, exterior suction band converts passing wind currents into a powerful suction force accelerating the movement of air up through the ventilator. RIDGE--Provides complete ventilation for continuous openings of various lengths. Furnished in many throat sizes and in 10 ft standard lengths. Fabricated to be inconspicuously low and to blend with building. RECTANGULAR PUL-AIR--Modifica tion of standard round unit,.intended for use where odd size ducts, masonry flues or. shafts extend through the roof or openings of irregular areas must be capped with a weatherproof gravity ventilator. They can be furnished in any desired size. Domex Penn Dynafan : For More Than tS Years, The Builders Roof-top Line Manufacturers of PROPELLER FAN, CENTRIFUGAL, STATIONARY, and ROTARY RIDGE VENTILATORS See Sweets Architectural or Engineering File or unite direct for catalogue. Member of Power Fan Manufacturers' Association ` 1422 Air System Equipment Air Vents and Roof Ventilators The Swartwout Company 18511 Euclid Avenue, Representatives in Principal Cities Cleveland 12, Ohio GRAVITY ROOF VENTILATOR GRAVITY ROOF VENTILATOR Swartwout-Dexter Heat Valve Continuous opening natural draft venti lator particularly effective for ridge of peaked roof, saw-tooth construction or skylights; adaptable to flat or slant roofs. Made in throat opening sizes 4, 6, 9, 12, 15.18,24,30,36 and 42 in. Ten foot units. Adjustable damper. Weatherproof. . DUCT EXHAUST VENTILATOR Swartwout Alrmover Compact multiple opening type featur ing very short air travel, built in units 10 ft x 7 ft, 6 in. x 32 in. high; 30 sq ft of opening per unit. Used as single units, or single or multiple width runs. Unusual large scale ventilation results possible by roof coverage such as illustrated. Can be adapted to any type of roof. Insert shows "open roof" effect. FIRE VENTILATION The Airlift is a centrifugal fan unit for duct exhaust against static pressure. Operates at very low noise levels. Fan has backwardly curved blades completely non-overloading; bottom of wheel flared to/prm throat overlapping inlet increases efficiency, avoids turbulence. 14 sizes, 138 capacity variations. Swartwout Fire Valve Roof unit for release of heat, smoke, gases in event of fire. Two large dampers drop, released by fusible link; provide 46 sq ft free area opening. Only 21 in. high above curb. Weatherproof when closed. OTHER SWARTWOUT ROOF VENTILATOR TYPES RJ,,A?Y' URJXCTOR, VALVBNT, gravity LOW-LINE, grac- yravtty powered and powered ily and powered WHIRLOUT, powered LOUVERS See Sweets Architectural, and Industrial Construction Files. 1423 Air System Equipment * Ventilators Western Engineering & Mfg. Co. ESTABLISHED 4112 Glencoe Ave. 1921 Venice, Calif. Representatives in Principal Cities HIGH EFFICIENCY ROOF VENTILATORS Western Rotary Ventilator High exhaust capacity for relatively small bulk in weight. Remains in con tinuous motion between gusts, and is . stormproof. It cannot backdraft because the throat velocity rises at an increasing rate with the wind speed. Wind tunnel tested. Rigid center support, and vibra tion absorptive rubber mountings, quiet performance. Enclosed, long-life lubrica tion, and durable hammertone sea-green finish. Sizes: 6 in. to 48 in. inclusive. Western Continuous Ridge Ventilator For high volume, low velocity exhaust capitalizing on air movement generated by temperature difference plus induced draft, this ventilator provides a continu ous opening of any length desired in 17 throat sizes. The structure is storm and rain proof and is available with or with out adjustable dampers and screens. In herent characteristics qualify this venti lator for use in factories, foundries,mills and similar buildings. ' Forbes Syphonaire A highly-engineered stationary type roof ventilator employing a circular wind band that prevents the entrance of out side air. High capacity, rain and storm proof, rugged construction, and low silhouette, obviating the need for guy wires. Wind tunnel tested by aeronauti cal laboratory. Sizes range from 6 in. to 48 in. inclusive. Westemalre Curb-mounted Fan For low cost air movement under low static conditions, this unit is designed to meet practically every application in volving a roof-mounted exhaust fan. High speed, high velocity for industrial use or slow speed, quiet operation for commercial use. Available in 39 models. 8 in. to 48 in. Can be used in conjunction with any type gravity ventilator. SEE OUR COMPLETE CATALOG IN SWEET'S ARCHITECTURAL FILE, INDUS TRIAL CONSTRUCTION FILE AND ARCHITECTS AND ENGINEERS CATALOG FILE or write to above address for additional catalog and list of Representatives. j Forbes Econovent Gravity Western Airaui, Gravity 1424 Booster Fan, Powered Ish Air System Equipment mui Sheets UNITED STATES STEEL AMERICAN STEEL & WIRE DIVISION, CLEVELAND COLUHBIA.GENEVA STEEL DIVISION, SAN FRANCISCO NATIONAL TUBE DIVISION, PITTSBURGH TENNESSEE COAL & IRON DIVISION, FAIRFIELD. ALA. UNITED STATES STEEL CORPORATION, PITTSBURGH UNITED STATES STEEL SUPPLY DIVISION, Warehouse Distributors, Coast-to-Coast UNTIED STATES STEEL EXPORT COMPANY, NEW YORK U.S.S. GALVANIZED STEEL for high quality results and ease of fabrication U.S.S. Galvanized Steel Sheets are espe cially processed for the jobs they have to handle. They arejmiform in flatness and surface. They can be bent, cut, stamped, rolled and formed--all with unusual ease of handling. In the pro duction of U.S.S. Galvanized Steel . Sheets careful attention is paid to the adherence of the zinc coating. This is done in order that forming operations may not fracture or flake the coating and thereby expose the base metal to atmospheric corrosion and rust. Because of all these outstanding quali ties, U.S.S. Galvanized Steel Sheets per mit true bends, tight joints and neat seams, even in . forming difficult angles ' and shapes when working in close and confining places. U.S.S. Galvanized Steel Sheets are produced in a wide variety of sizes and forms. Our engineers are specialists in their use and will gladly assist you in their application. Other U.S.S. Steels famous for service U.S.S. STAINLESS STEEL is ideal for use in chemical plants, laboratories, and other places where highly corrosive at mospheres would spell early destruction for less durable materials. Its high re . sistance to corrosive attack, great strength, ease of cleaning and high re sistance to extremes of temperature are definite money-saving advantages. U.S.S. COPPER STEEL--coated or uncoated, insures increased resistance to corrosion, and increases life under all conditions of atmospheric exposure. U.S.S. GALVANIZED PAINTBOND STEEL--for ductwork requiring imme diate painting without preliminary treatment or weathering. Paint will not flake. Bonderized surface prevents dete riorating action between paint and gal vanized coating. A similar sheet, U.S.S. DULKOTE, is available in the South and the West. 1425 Air System Equipment A?DmSs"^ Grines A-J Manufacturing Co. 3601 E 18th St. Kansas City 27, Missouri REGISTERS GRILLES DIFFUSERS Model 400 VH Grille A-J No. 44 Series Dampers are the same dampers furnished with No. 440 Series registers, but are also available as separate units for easy installation in the A-J No. 400 Series Air Conditioning Grilles and No. 440 Series Air Con ditioning Registers are available as either single or double deflection units to fit most standard duct sizes from 8 in. x 4 in. through 60 in. x 24 in. Choice of vertical or horizontal bars only, or combination of both with either vertical or horizontal in front. Both the spring tension mounted bank of extruded aluminum face bars and the bank of back bars are individually adjustable. No. 440 Series registers combine any size No. 400 Series grille with a corre sponding size opposed blade damper which can be locked in any desired position. Model 44 Damper duct behind a grille. They provide positive metered air flow by means of their opposed blades which are con trolled by a patented Phillips screw gear drive. Air is distributed evenly over the entire area of the grille. Damper locks at any degree from fully opened to fully closed, as in the photoS above. Maximum depth of the unit in full open position is in. Sizes range from 8 in. x 4 in. through 40 in. x 12 in. A-J No. 45 Series Return Air Grilles are the matching counterpart for the No. 400 Series grilles and the No. 440 Series registers. Designed for return air intake, they are available with hori zontal face bars--straight deflection, Model 440 II Register Model tf-D GriUe vertical face bars--straight deflection, and horizontal face bars--35 deg down ward deflection. Face bars are of % in. wide extruded aluminum set on % in centers. Bar deflection is fixed at the factory. Available in all standard duct sizes from 8 in. x 4 in. through 60 in. x 24 in. For positive volume control, can be used with No. 44 Series dampers. 1426 A-J Manufacturing Co. Ah System Equipment Registers and Grilles A-J Architectural Grilles are available in square meshes of and % inches, and in various slotted designs. Made to your order in any size from steel, aluminum, bronze, monel or stainless. A-J Double and Single Diffusers are furnished with one-half of the vertical curved louvers facing to the right, onehalf to the left. In cases where deflection is required in one direction only, louvers will be assembled to direct all of the air to one side only. A-J No. 70 Series No-Vision Door or Partition Grilles are ruggedly con structed, yet are light in weight and have a free area of approximately 70 per cent. Completely sight proof. Excellent for door or partition installations. Illustra tion at right shows grille and cut-away view of auxiliary frame. A-J No. 77 Series Thin Core Grilles are only } in. thick, yet are completely sight proof. Free area is approximately 80 per cent. They were developed to answer the increasing demand for ventilating grilles for panels or par titions, and can be installed in any panel ranging from yA in. to % in. thick. Illustration at left shows grille and cut away view of auxiliary frame. ^J No. 55 Diffusing Perimeter Registers are designed specifically for installations with perimeter heating systems. Heavy gauge curved vanes are set at the factory to deliver a fan-shaped pattern of air to cover window areas and cold outer walls. Excellent for installation in stair risers, under kitchen cabinets, in picture window sills, or as side wall outlets with high velocity systems. FOR COMPLETE SPECIFICATIONS* AND PRICES ON ALL A-J PRODUCTS, WRITE FOR ILLUSTRATED CATALOG NO. 55 . 1427 Air System Equipment GriUes Air Control Products, Inc. Coopersville, Michigan Air Conditioning Registers. Grilles, Celling Diffusers and Leigh Building Products. No. 20 Series Air Conditioning Registers and Grilles Superbly styled. Two tone finish. Posi tive control of air stream assured by ad justable vertical front fins plus adjust able horizontal back fins. Both banks of fins are easily adjusted from the face of the register, making it simple to set for heating or cooling. ' The front fins are factory set for a multiflow horizontal air pattern, an unique Air Control feature. Back fins are set for 22J^ deg deflection but may be easily adjusted for any desired up or down flow. Special fin adjusting tool furnished. The air flow pattern is not changed by the damper position. Its design provides for perfect volume control, plus ideal air distribution. The volume control damper is formed for rigidity and strength and opens easily to a full 90 deg. An ad justable spring loaded operator makes this register ideal for upside down in stallation on systems where duct comes down from the attic, or on shallow depth stackheads. Adjusto-stop makes it easy to balance system at the register face. Does not interfere with closing of the damper. . No. 20 Series Sidewall and Baseboard. Registers are available in the following duct sizes: 8 in. x 6 in., 10 in. x 6 in., 12 in. x 6 in., 14 in. x6 in. Sidewall and Base board Grilles are' available in the above sizes plus the following: 24 in. x 6 in., 30 in. x 6 in. MULTI-TROL REGISTERS AND GRILLES Air Control's Multi-Trol Register line was developed to solve the problem of installation in standard wall construc tion. Here is a commercial type, adjust able bar register with an opposed action valve that is so shallow it can be used with standard fittings and duct work, even in in. risers. The shallow depth air control valve is achieved by moving the pivot point as WRITE FOR AIR CONTROL CATALOG No. 56-AC--COMPLETE ENGINEERING DATA, SIZES 1428 Air Control Products, Inc. Air System Equipment * GriUes MULTI-TROL REGISTERS AND GRILLES (Cont.) close to the face as possible and closing the louvers practically flat. Louvers are butterfly type and in closed position, air pressure seals the valve and prevents whistling and air leakage. At any degree of opening, air is distributed evenly over the face of the register. Micro operator gives positive control in any position and opens and closes the largest valve smoothly and easily. On residential installation,"'the attractive operator key may be left in place if de sired. Face bars are built with an airfoil con tour, reducing resistance to a minimum and making units extremely quiet at high velocities. Bars pivot on a round bearing surface. Pivots are rolled over where they extend through the marginwill not pull out. Easily adjusted with deflection key furnished. Bars are full depth, spaced on 0.666 in. centers, the ideal spacing to give positive air deflec tion and maximum free area. Beige prime coat finish. A wide range of sizes to 36 in. x 36 in. NO. 188 BASEBOARD DIFFUSER WITH BUILT-IN ROTARY DAMPER. With built-in rotary damper the No. 188 installation time in half. After difluser assures peak efficiency in air patterns for is located over the duct, the base strip is heating or cooling. Insures uniform veloc withdrawn to duct width, snipped off, ity at the face, regardless of degree of and the cut-off inserted into other end opening. In 4-ft lengths (29.36 sq in. free of base. No. 186 Return Air Grille in area) and 2-ft (14.68 sq in. free area) for matching design offers 58.72 sq in. free single or continuous installation. Sculp area. Both diffusers and return air grilles tured plastic operator. may be installed before or after plaster New Adjusto-Bottom Base Strip cuts ing, on sub-floor or finish floor. WRITE FOR AIR CONTROL CATALOG NO. 56-AC--COMPLETE ENGINEERING DATA. SIZES - 1429 Air Control Products, Inc. Air System Equipment a?ijSm" GrfflCB NO. 333 RETURN AIR GRILLE. An swers the problem of centralized re turns--easily installed in ceilings, walls, doors. Made of heavy gauge steel, onepiece construction, with angle frame for added stiffness. A single return in one of the larger sizes has enough capacity NO. 42 PERIMETER FLOOR DIF FUSER. One-piece face has no corner seams to mar the beauty of its curved, for an entire heating or cooling system. In 15 sizes from 10 in. x 10 in. to 30 in. x 18 in. flowing contours. New, extra wide flanges insure complete coverage of rough cut or irregular floor opening. Smoothly curved vanes and wafer-thin valves re duce resistance, increase free area, and provide more efficient air distribution. Outside walls are blanketed with a layer of warm air--prevents cold drafts from flowing into the room. Adjusto-Stop screw stops the valve at any desired opening, balances system at diffuser face--eliminates the need for additional duct dampers. Vanes can be set for any desired deflection without shearing off at ends. Outstanding for use with conventional heating systems, perimeter heating and small-pipe perim eter heating. Standard Oak and Metalescent finishes. No. 15 SIDEWALL PERIMETER DIF FUSER. Scientifically engineered to give a draftless blanket of air over the outside wall from a sidewall location. Two sizes-- 12 in. x 6 in., and 10 in. x 6 in. Provide complete, rapid diffusion of air when used with conventional duct or loop or radial slab installations. Top sectionds flared away from diffuser face--prevents air from scrubbing wall. Balancing is easily accomplished at face. Flat-spring OPENING SIZES--14 in. x 6 in., 12 in. x 6 in., 14 in. x 4 in., 12 in. x 4 in., 10 in. x 4 in., 14 in. x 2J6 in., and 12 in. x 2J in. Latter two are ideal for narrow, hard-to- linkage holds valve rattle-free in any position. Sponge rubber gasket seals against wall. Beige prime coat or Metalescent finish. fit spaces under kitchen cabinets, in sill of large picture window, under stair risers, etc. No. 16 OUT-OF-THE-WALL-DIFFUSER. Same advantages as the No. 188 or No. 42 series. Ideal for baseboard diffuser, particularly in remodeling. NO. 265 OUT-OF-THE-WALL PERIM Duct connected through floor; back fits ETER BASEBOARD REGISTER. Solves flush with wall. Made in 10 in. x 6 in. and installation problem where duct does not 12 in. x 6 in. opening sizes. or cannot enter wall. Adjusto-Stop per mits the system to be balanced at diffuser face. Horizontal fins can be adjusted to throw air stream at any angle in relation to wall. Matching No. 262 Baseboard Grilles have same construction, without damper. "E" FRAME FOR NO. 15 DIFFUSER. Makes conversion of No. 15 Diffusers to baseboard use extremely easy. New style frame blends smoothly with diffuser con tours. Made of heavy-gauge steel, fin ished in beige prime coat or Metalescent. Sculptured plastic operator. WRITE FOR AIR CONTROL CATALOG--No. 56AC--COMPLETE ENGINEERING DATA, SIZES 1430 ,4ir Control Products, Inc. Air System Equipment Registers and Grilles Air Difitisers CEILING DIFFUSERS FLUSH TYPE for installation where pro jection from ceiling is not desired. Air Flow Rings discharge air in concentric jets for rapid diffusion. Curved contours of ring directs air slightly downward with minimum resistance. STEP-DOWN TYPE, with approxi mately 30 per cent more free area than Flush. Delivers air downward more di rectly. Both types suitable for cooling, since air is delivered at ceiling level for gradual settling. Both in 6 sizes, 8 in. to 22 in., finished in Beige prime coat. DOUBLE VALVE DAMPER gives exact control of air volume, plus even air dis tribution. Chain operated, permit balancing system at face. For 8-in. to 16-in. Diffusers. Single valve types avail able for 18-in. and 22-in. Diffusers. INSTALLATION RINGS simplify firm seating of Ceiling Diffusers. Easily screwed or riveted to duct end or block ing. Not used with dampers. In sizes to fit all Air Control Ceiling Diffusers. ADJUSTABLE CEILING DIFFUSER--adjusts to any pattern from straight down ward deflection to flat pattern. 6 sizes from 8 in. to 22 in. NO. 40 FLOOR REGISTERS feature famous Rigid-Lock type construction. Each fret is locked to each crossing fret and to margin. Dial-operator valves run the short way of face. Medium mesh (J^6 in.) between faces. Same construc tion in No. 41 Floor Return Air Faces. NO. 110 SERIES REGISTERS with vertical adjustable fins. Provide hori zontal control of air stream. Single-shut ter damper with sculptured plastic operator, equipped with Adjusto-Stop for balancing. y,,. no NO. 50 SERIES BASEBOARD REGISso TERS. A gravity-type register with re movable face for streak-proof installa tion. Balanced damper with sculptured plastic operator, stays at any open posi tion. No. SO Sidewall Gravity Register is styled to match; with damper. WRITE FOR AIR CONTROL CATALOG NO. 56-AC--COMPLETE ENGINEERING DATA, SIZES 1431 Air System Equipment fafoSL Air Devices Inc. Air Diffusers Exhausters Air Filters Filter Holding Frames Industrial Furnaces ; 185 Madison Ave. New York 16, N. Y. 3ciTmQ . Agents in All Principal Cities AGITAIR DIFFUSERS AGITAIE square and rectangular air diffusers are available with removable core and three distinct types of mounting frames, attractive in appearance, and practical for all job conditions. The removable core is a tailor-made dif fuser with patented built-in diffusing vanes. The vanes and louvers are as sembled in a wide variety of patterns and sizes to suit conditions of each applica tion. Air is discharged in one-two-three or four directions with each side deliver ing a quantity of air proportional to the area being served. These AGITAIR Dif fusers perform efficiently, quietly, draftlessly with rapid temperature equaliza tion. Square or Rectangular in Shape STRIPLINE Diffusers incorporate patented built-in diffusing vanes which produce extremely high turbulence and aspiration. Rapid temperature equaliza tion is achieved with maximum allow able temperature differentials between room and supply air. STRIPLINE in sures an unvaried distribution of noise less, draftless conditioned air over a predetermined area. Hot or cold spots are eliminated in the zone of occupancy. Available in two styles and supplied as a continuous decorative unit or in sec tions. CIRCULAR DIFFUSERS Type "OA" adjustable units employ a radically, new means for controlling air direction at 4 different angles of dis charge simultaneously without disturbing the position of the spinpings. Not only New method of installing AGITAIR Type "RC" Air Diffusers saves time and labor costs. Only two steps are required to finish installation: 1) attach mounting frame to duct collar. 2) Insert diffuser core and lock in position. For installation in acoustical ceilings AGITAIR square and rectangular dif fusers are made in sizes to conform to standard tile dimensions. The AGITAIR Diffuser Data Book, avail able to architects and engineers, will help you design and install air distribution systems. Consult our engineers. is it possible to produce any angle of discharge from above horizontal to verti cal, but each of four 90 deg segments are independently adjustable. Thus, it is possible to blow horizontal from one segment; vertical from a second; 45 deg downward from a third and 20 deg from a fourth if desired. AGITAIR Type "OA" Diffusers are truly adjustable, with or without ceiling. Type "O" are non-adjustable. They are identical to the Type "OA" except for omission of deflectors. Air is discharged horizontally or above--with or without a ceiling. 1432 Air System Equipment mirusm i 1624 So. Raymond Ave. All* nicfrihtiti/in ms X!N/' Monrovia, California SERIES LCF SIDEWALL DIFFUSERS: SERIES AVP-QO Adjustable Air Proportioning Vanes: MODEL LCF-RC (Removable Core) Factory set outlets distributing air in laminar counterflow layers mix supply with room air reaching design conditions in minimum time and space. LCF outlets can be equipped with secondary flexible horizontal vanes which may be reset on job, giving maximum, vertical control with varying length of blow. SERIES B60 CEILING DIFFUSERS: Moximum ftlry into duct 2b" whon full opft Balances air distribution for given supply outlet. Quick opening feature extracts air with a 2J4 in. maximum en trance into main duct, reducing velocity evenly over outlet face. Full shutoff. Manufactured separately or attached to sidewall ceiling outlet or diffuser. Key or rod operated. SERIES OBD-KO Air Volume Control: MODEL 4B60-RC (Removable Core) ODOODOd t? tdO O O 1 Patented construction provides pro portionately balanced. air distribution with controlled total air motion through laminar counterflow core. Square or rectangular air. diffusing outlets. Full range sizes and capacities allows maxi mum mixing of primary and secondary air with distribution of supply air in di rect ratio to floor area. Opposed acting blades; center pivoted. Operate from full open to full closed position. Used directly attached to grille, diffuser or installed as separate unit. Key operated. Friction linkage maintains blades in position wrhen set. SERIES ACD DIFFUSER: For ceiling installation. Patented laminar counterflow core and flexible vanes permit on-the-job adjustments for controlling blow length and ceiling discharge angle. 1433 Air System Equipment Anemostat Corporation of America lO^East 39th Street ANEMOSTAT<D Representatives in New York 16, N. Y. DRAFTlESS&fiwfc^AIR DIFFUSERS Principal Cities PRINCIPLE OF ASPIRATION The Anemostat Air Diffuser splits the supply air into multiple, separate air streams and at the same time creates low pressure areas in certain parts of diverging passageways. This causes room air to be siphoned into the device where it is thoroughly mixed with sup ply air. The mixture is discharged in a series of expanding turbulent air layers and, therefore, readily entrains a large amount of additional room air. As a result, temperature and humidity are equalized throughout the room and a continuous air motion in the occu pancy zone within low acceptable veloc ity limits is established. Stagnant air pockets are also avoided. The quantity of room air drawn into Anemostat Air Diffusers depends on the specific design, size and type of the various units and is equal to as much as 35 per cent of the supply air. This effective aspiration distinguishes Ane mostat Air Diffusers from all other air outlets. SMALLER DUCTS Aspiration permits the use of greater temperature differentials and higher supply air velocities than customary, which results in savings in the initial cost of fans and ducts and in the operat ing cost of the system. Duct layouts may be simplified because Anemostat Air Diffusers distribute air evenly in spite of unusual room plans, columns or other obstructions. THE COMPLETE LINE Anemostat Corporation of America has developed air distribution devices and related equipment for every purpose. Circular, semi-circular, square and straightline Anemostat Air Diffusers of various types and sizes for ceiling and wall distribution are available for com fort conditioning and industrial heat ing, ventilating and air conditioning in stallations. These are available for both conventional and high-pressure, high velocity systems. ' 1434 Ahemoslat Corporation of America Air System Equipment QUALITY Anemostat Air Diffusers are scientifi cally designed according to modern fluid flow theory and manufactured according to modern production standards. TYPICAL ANEMOSTAT ALL-AIR HIGH VELOCITY INSTALLATIONS ANEMOSTAT PATENTS The Anemostat Corporation of America holds over fifty patents covering the use and design of diffusers in the field of air distribution. The superior functioning of the Anemostat is protected by these patents which are the result of inventive spirit, diligent research and constructive engineering. RESEARCH AND ENGINEERING Anemostat Corporation of America maintains a large, well equipped labo ratory manned by experienced scientific and technical personnel for testing pur poses and the development of new prod ucts. Engineers from all over the world have visited the Anemostat laboratory to witness demonstrations of Anemostat products and their applications to any conceivable problem pertaining to air diffusion. Anemostat has spent over a million dollars in research and engineer ing and will continue to make substan tial contributions to the progress of the science of air distribution. EXPERIENCE . Over a million and a quarter Anemostat Air Diffusers are now doing an excellent job in thousands of comfort conditioning and industrial heating, ventilating and air conditioning installations. In addi tion to applications in commercial build ings, industrial plants, hotels, stores, hospitals, theatres, restaurants and homes, Anemostat Air Diffusers are used in military and commercial aircraft, rail road cars, buses and ships. SPECIAL INSTRUMENTATION Anemostat engineers have developed various instruments for the accurate and convenient testing of the perform ance of air outlets. The Anemotherm Air Met^J a self-contained, compact, portable instrument, facilitates the bal ancing and checking of air distribution systems by engineers and contractors. It is now commercially available and is being used with great success by engi neers and contractors throughout the country. 1435 Air System Equipment SJorfUes The Auer Register Co. 6600 Clement Avenue, Cleveland 5, Ohio Manufacturers of Registers and Grilles for Gravity and Air Conditioning Systems; Metal Grilles for Radiator Enclosure, Ventilation, Concealment AIR CONDITIONING REGISTERS AND GRILLES Auer has a complete line for warm air or air conditioning, a wide choice of styles for every purpose. For gravity systems, the Heat-Rite is a quality model, adjustable for up-or-down flow. DuraBilt floor registers and intakes provide extra strength with interlocked cross-bar construction. "Streamliner" registers. and grilles for high velocity outlets are made in 8 styles, with single bank of adjustable bars, vertical or horizontal, also with double bank, front vertical and rear horizontal (or the reverse), also all these types with the addition of multi-louvre valves. Auer Register Book showing entire line sent on request. Auer perforated grilles are made in many designs and sizes, in steel (or stainless), aluminum, brass or bronze. Finished or plated as desired. Grille Catalog. "G" gives full scale details, tables of openings and free areas. I 1 c Air System Equipment Register^ and Grilles Barber-Colman Company uniiio Air Distribution Products Rockford, Illinois Engineered Air Distribution Products and Complete Engineering Data to Meet Any Air Distribution Requirement Streamliner Register No. 1005V-HML. streamliner No. 1205VH. Double deflec- Adjustable bars, multi-louvre valve. tion grilje> adjustable bars. Airo-Flex No. 4432 Register--Multilouvres adjustable up, straight or down Grille bars adjustable for right or left flow. Grille to match. Airo-Flex No. 7032 Register--Grille bars set to direct air downward at 22) deg, but adjustable for other angles. Single louvre. Grille to match. 1436 No. 100 Perfusaire GRILLES AND REGISTERS Uni-Flo Grilles and Registers provide rapid diffusion, a high rate of aspiration with resultant high air entrainment ratio, low pressure drop, low noise level, simple adjustment of the air pattern, and a pleasing appearance. A variety of frame styles is available to meet sidewall, panel, or exposed duct installation re quirements. A removable core feature makes it unnecessary to break the paint or plaster seal for cleaning or decorating purposes. CEILING DIFFUSERS Uni-Flo Square and Rectangular Ceiling Diffusers blend with acoustic ceiling tiles, providing air pattern modification without altering outward appearance of diffuser. Venturi-Flo Diffusers, for in stallation on ceilings or exposed ducts, provide simple adjustment of air patterns from vertical to horizontal. They are available in a complete range of sizes. Line-O-Flo Ceiling Diffusers have dis tinctive linear design and can be in stalled individually or in a continuous strip. HIGH VELOCITY Uni-Flo High Velocity Air Valves reduce high velocity air to conventional veloci ties. Installed directly behind grilles or at junction of high velocity trunk duct with conventional velocity branch duct. Uni-Flo High Velocity Control Units, for use at individual diffusers, reduce air velocities, providing maximum attenua tion of noise in minimum space. Uni-Flo High Velocity Double Duct Units mix hot and cold high velocity air and reduce it to conventional velocities. ACCESSORIES Uni-Flo accessories simplify system balancing; assure uniform air distribu tion across diffusers and duct sections, reducing noise, turbulence, and pressure losses; and effect savings in ductwork installation and system operation. UniFlo Airturns give sweeping radius per formance to square duct corners. Uni-Flo Volocitrol is a balancing device designed to provide even distribution across the grille. The Deflectrol is an air turning device designed for installation at diffuser or branch duct runouts. 1437 Air System Equipment Outlets and Grilles BURGESS-MANNING COMPANY j4%c&UeetwuU 'Proc(uct& 5970 Northwest Highway, Chicago 31 3-Way Functional Ceilings A Finished Ceiling that Supplies 1. Radiant Panel Heating 2. Radiant Panel Cooling 3. Acoustic Control The radiant panel principle of this modern ceiling provides heating and cooling independently of air movement. Heat is conducted from the coils through the aluminum ceiling panels, which are secured directly to the coils. Heat energy is then radiated to or from the entire ceiling to or from every surface and ob ject in the room. Every square inch of the Burgess-Manning Functional Ceiling works--every square inch is heated or cooled as the case may be. Nature's way of controlling human comfort. TYPICAL SPECIFICATION Install Burgess-Manning Ceiling com plete with suspension system, heating cooling coils, acoustic-thermal blanket, perforated aluminum Snap-On Panels standard finish and matching metal edge molding. Each coil is to be pro vided with threaded nipple ready to accept supply and return piping. Open ings to be provided for recessed light troffers, diffusers and sprinkler heads. Supply and return piping, including balancing cocks and air vents to be sup plied and installed by others. For design procedure and performance curves send for Catalog A-U9-G. Standard iV tn. Uniform air temperatures are main tained, convection drafts and heat shadows are minimized. Concentrated heat sources and overheated air are eliminated. Burgess-Manning Ceiling can satisfy a wide range of heat requirements includ ing panel demands of 125 Btu/sq ft/hr. THE BURGESS-MANNING CEILING CREATES A NEW STANDARD FOR COMFORTABLE WORKING AND LIVING CONDITIONS. * Carries the entire Heating Load * Carries approximately one-half of the entire cooling load. (Air requirements usually limited to latent heat removal and ventilation--reduced air handling equipment and smaller ducts save build ing cubage.) * Standard controls--instantaneous re sponse to water temperature changes. Controlled heating and cooling with out LAG or OVER-RUN. * Modular system for design flexibility as to layout, lighting, and any system for air distribution. Unrestricted use of floor area. 1438 Air System Equipment GnuST* Charles Demuth & Sons, Inc. Mineola, N. Y. Demuth Draftless Air Distributors Representatives in Principal Cities Type (&') Type (P Type (!/} The DEMUTH DRAFTLESS AIR DIS TRIBUTOR consists of a series of curved yanes, mounted on a deflecting cone, to insure 360 deg distribution without the aid of secondary equalizing devices. A second hollow deflecting cone is arranged at a tangent to the primary cone, forming an injection nozzle. The curved vanes discharge the supply air in turbulent streams, mixing room air with conditioned air, thereby providing constant air motion, uniform tempera ture and draftless distribution through out the room. Secondary air currents, which are created by the turbulence of the dis charge air, are drawn into the diffuser by the bottom or secondary cone, mixed with the supply air, resulting in positive aspiration. Type (SQ) square and rectangular Air Diffusers are made to any size with re movable core assembly. Air distribution is from one, two, three or four sides of the diffuser. Made to any air pattern. Accessories Combined lighting is available with the circular type. Volume and Splitter Dampers are available for all types. 1439 Registers Air System Equipment and Grilles Air Diffusers CONNOR ENGINEERING CORP. Danbury, Conn. o* draft Representatives in All Principal Cities adjustable air difiuaere In Canada: Do^^tas Engineering Co., Ltd., Montreal, P. Q. CONTROLLED AIR DIFFUSION Kno-Draft Adjustable Air Diffusers are designed to give accurate control of air distribution, plus installation and opera tion economies. With air direction and air volume adjustments on each diffuser, "custom-made" air patterns can be created after .installation which will in sure draftless diffusion and equalized temperatures for comfort conditioning or specific patterns for industrial proc esses. Type KDA for supply air. Type SRD for combination .. . . ,. . supply and return air. Aluminum, sizes 4teSS in. Sizes e t0 H in. TOppIl) nak neck dia. Capacities SO to <* Capacities SO to t.SOO _ cfm per unit, return neck 15,000 cfm per unit. area 75% of supply. Installation, balancing and inspection are fast because of features like the Type HD quick-opening set-lock assembly, the self-contained inner unit and the sleevetype damper. Kno-Draft Diffusers are geometrically proportional, size for size, insuring like re sistance at like neck velocity for any size--a considerable advantage when selecting various size diffusers for a common system. Anti-Smudge Cone Where exceptionally sooty or dusty air conditions are expected or where roughtextured ceilings are employed, the use of this accessory cone is recommended.It furnishes the additional control needed to provide the precise air sepa ration which inhibits smudging. Square Diffusers Diffuser with anti-smudge Diffuser and Cone separated Kno-Draft Square and Panel-type Air Diffusers with built-in volume control Cone assembled and precision circular air patterns are engineered to give the utmost in air dis tribution efficiency. Designed for installation in modern acoustical ceilings their simple geometri cal lines complement the inherent beauty of the ceiling pattern, creating a uniform effect that is pleasing to the eye. Utmost flexibility of installation is an outstanding feature of the Panel-type diffuser. By use of special patented flex ible tubing the diffuser need not be lined up with duct and may even be installed in adjacent bays. Entire offices, partit ions and floor areas may be relocated without moving ductwork. Integrally stamped Panel Type diffusers shown in stalled in Acousti-Lins ceil ing. Sizes available, 4 in. to 6 in. neck dia. with capac ities from 75 to 175 cfm. Type KP for installation in acoustical ceilings. 4 in. to 14 in. neck dia. sizes. Capacities from 50 to 1950 cfm. Kno-Draft Diffusers are covered by U.S. Patents Nos. 9,565,867; 9,569,119; 9,459,989 and others pending; Cana dian Patents Nos. 499,906; 44S,9S5. 1440 Connor Engineering Corp. Registers Air System Equipment G"Ues Air Diffusers HIGH PRESSURE AIR DIFFUSION In 1949 Connor Engineering Corp. was among the first to supply units for large high pressure diffuser installations. Since that time, the company has been con tinuously active in the development and use of high pressure systems. High pressure techniques are now applicable to almost every type of proposed or existing structure. High pressure air transmission systems using Kno-Draft high pressure air diffusers are installed and operating satisfactorily in office buildings, hotels, hospitals and schools. The air outlets are of utmost importance to the successful operation of a high pressure system. Located directly above the occupied areas, they must perform in a completely satisfactory manner if the system is to be a success and its potentialities fully realized. Various high pressure dif fusers are required to satisfy all job re quirements. Different outlets are necessary for different systems; also, different installations require different methods of air distribution. The illustra tions show two of the many types of Kno-Draft high pressure diffusers. . The HPC-J was the first high pressure HPC-J High Prssure Dif user for exposed duct in Cutaway view of BPR-KA showing internal construc diffuser made by -Connor Engineering ttatlriim. tion. Corp. The one shown is the result of improvements that have been made over the years. This diffuser was specifically designed for use on exposed ducts in existing department stores and office buildings with particular emphasis on achieving a neat, unobtrusive appearance. The HPR-KA is one of the most silent high pressure diffusers made. The cutaway illustration shows internal construction including the damper mechanism and sound trap. The damper is a perforated cylindrical type patented by Connor Engineering Corp. It is used in all Kno-Draft high pressure diffusers. The inlet tube and per forated cylinder are fabricated from one piece of corrosion resistant, stainless steel An adjustable felt-edge piston seals the cylinder. Changes of position increase or de crease the number of perforations exposed and thus vary the air delivery of the unit. This cylindrical perforated damper has many advantages: it is quiet, simple in construction, self-cleaning, and permits both a complete and positive shut-off together with a wide open position where unavoidable construction dirt can pass through the damper mechanism. The sinuous sound trap is another patented development. It absorbs both low and high frequency noises and the carefully de signed contours prevent turbulence and noise generation. Kno-Draft high pressure units are also available in dual-duct models which feature the same unique construction. Provision is made for operation of the dampering mechanism by pneumatic motors. Free Handbooks on Air Diffusers Complete information on Kno-Draft high pressure diffusers is contained in the newly published Bulletin K-SS. This manual also answers many of the questions about high pressure air trans mission and contains complete detailed information for designing these systems Bulletin K-20A contains complete information on the standard line of Kno-Draft low pressure diffusers. The Kno-Draft High Pres sure Bulletin KSS gives complete technical data on high pressure systems and diffusers. Kno-Draft Adjustable Air Diffusers and their operating characteristics are fully described in Bul letin K-09-A. unique characteristics of these single-jet, high velocity diffusers makes them ideally . applicable to low pressure installations. Either of these bulletins may be obtained by writing on your company letterhead to: Connor Engineering Corp., Dept. Y29, Danbury, Connecticut. See pages 1596 and 1597 for data on Dorex Air Recovery and Air Purification Equipment. 1441 Air System Equipment SmGriura General Register Corporation 14 Factory St., Cedar Grove, N. J. General Register manufactures a complete, quality line of adjustable and fixed supply and return registers and grilles for cooling systems. Double-deflection register illustrated consists of double-deflection grille with Silentite opposed-blade damper. Front fins may be either horizontal or vertical. Single-deflection type also available. gjgiv Ea*lWWSTO-I*ffi IWM44H SWt i-H'l-i .14 S3 HT*I rarea;a5ii-an=is:ijr5*-ii.iFifBff fa - im :SP Double-deflection adjustable grilles offer quiet, efficient diffusion. Face fins are hollow, streamlined, sturdy, staked on close-fitting pins to prevent move ment after setting. Heavy frames have solid corners and pleasing radius edges. All registers and grilles available with fins on either .ii in. or % in. centers; supply units furnished with rubber gasket. Fixed return registers and grilles are of same quality construction as supply outlets, with fins set straight or at 40 deg angle. Registers are furnished with keyoperated Silentite damper. G-R's standard Baked prime coat paint is a handsome finish suitable for permanent installation unchanged, or may be readily repainted later. Simple, inexpensive dampers of the multi-shutter type are available for all General products. Supply registers, with very shallow depth, contain the entire blade struc ture within the damper housing, whether damper is in open or closed position. Curled edges of rolled blades interlock when closed, providing positive shut-off. General Register Carp. Silentite Volume Damper, outstanding feature of the General line, is supplied with all commercial registers; also furnished as a separate unit. Diagram shows hollow blade construction, made by an automatic precision fabrication process. The streamlined contour elimi nates turbulence, allows greatest free air passage. Hollow formation provides for positive gripping of bearings, assuring firm, free action without rattling. Re inforcing rib and double-thick edges produce great durability, also rigidity in longer blades. The General line includes a long list of air handling and control devices for ventilating and cooling systems. The Ductrol consists of a series of individually adjustable deflecting blades staked on close-fitting pins, to divert air from a supply duct into a collar. Air System Equipment Registers and Grilles Mounting frames are provided where it is desirable to remove registers or grilles periodically. Also available is a full line of ven tilating grilles for doors and partitions, fusible links for Silentite dampers, angle-iron frames, pulley and chain operators, adjusting keys, and a variety of plated, polished, and lacquer finishes. Plain lattice stamped grilles can be furnished as exhaust registers with keyoperated dampers. Other grilles include Pencil-Proof for schools, and Sanitary, readily suitable for cleaning. Various metals can be supplied, as well as a variety of finishes. 1442 Air System Equipment Registers and Grilles Hart & Cooley Manufacturing Co., Holland, Mich. Air Conditioning Registers, Grilles & Diffusers--Warm Air Registers--Damper Regulators--Furnace Regulators--Pulleys--Chain No. 74 DESIGN--Economy Type Air No. 76 DESIGN--Ideal Register for Conditioning Register. Flexible-fin face Shallow or Horizontal Ducts. Multi permits any up or down deflection of air flow. Positive valve with volume control for accurately balancing system. Gasket revents streaking. Side-wall and Baseoard Registers in sizes 8x4 through 14x8. .Grilles 8x4 through 30x8. No. ^DESIGN--Multi-deflection. Flexible-fih face provides for any deflection shutter valve (depth 1XK6 in- from wall) and flexible-fin face provide for all de flections desired. Any up or down defleetion can be maintained with adjusting screw. Sealed to prevent streaking. Sidewall and Baseboard type Registers in sizes 6x4 through 30x8. No. 88 DESIGN--Shallow Ducts, Large Installations. Similar to No. 76 except of airflow sidewise. Turning-Blade Valve, an H & C exclusive, turns airflow up, straight or down with 30 per cent less resistance. Instantly adjustable. Gasket revents streaking. Side-wall and Baseoard Registers in sizes 6x4 through 14x8. Grilles 6x4 through 30x8. TRIPL-AIRE Sidewall Registers. Excellent for commercial type installs- that face bars are adjustable in 2)4 in. sections (one moves all in section). Ex ceptionally good for large installations. Removable handje available to avoid tampering. Sidewall Registers or Grilles 6x4 through 30x24. FIXT-AIRE Return Air Grilles and Registers. Similar in construction and tions. Provide any deflection or combina tion of deflections desired. Opposed louvers afford absolute volume control. 26 standard sizes up to 36x12 . . . each available in 10 combinations of hori zontal and vertical front and secondary face bars and louvers. All key adjusted from front. Maximum size: 36x36. perfect complement to TRIPL-AIRE line. Same louver, but face bars (single bank) are fixed in either horizontal or vertical position. Grilles may be had with horizontal face bars set at 22 degree angle for up or down deflection. Maxi mum one-piece size: 36x30. 1444 Hart & Cooley Manufacturing Co. Air System Equipment anTormes No. 401 DIFFUSAIRE--For Perimeter Heating or Cooling. Installed above the baseboard on outside walls, provides an excellent means of blanketing outside wall and window areas with a curtain of warm or cool air. This diffuser disperses air in full 180 degrees spread upward in addition to directing a small portion downward over floor. Adjustable stop on handle permits balancing system at the face. Sizes: 10x6, 12x6, 14x6. No. 405 DIFFUSAIRE--For Perimeter Installations. Particularly good for use in established homes. Out-of-wall Base board type. No stackhead required. Provides same air pattern as our No. 401 Sidewall DIFFUSAIRE. No. 411 DIFFUSAIRE--For Perimeter Heating or Cooling. Floor-type. Counter acts downdrafts from windows and cold walls. Opposed louver valves and set screw adjustment permits accurate vol ume control for easy balancing of system. Design of louver blades provides even spread of air in fan shaped pattern with minimum resistance. Sizes: 2)4x10, 12, 14; 4x10,12, 14; 6x10,12,14. No. 44 Series DIFFUSAIRE--For Perim eter Systems. Continuous Baseboard type for installations of 8 ft or more. Furnished in 2 ft or 4 ft units, KD. No disassembly or lining up of screw holes necessary. Precision parts snap together without need of tools. Easy to install, easy to clean. Damper available with balancing adjustment. No. 452 DIFFUSAIRE--2 Foot Perimeter Unit. Same construction as No. 44 with additional top perforations for greater volume. Equal to 8 ft continuous type. No cutting of bottom section required. Balancing damper available. Its high throw makes it ideal for cooling as well as heating. CEILING DIFFUSAIRE--Low resistance eliminates necessity of changing blower in "residential package heating." Does excellent job on any residential or small commercial heating or cooling installa tion. 5 popular sizes. Gasket prevents streaking. Damper available. 1445 Registers Grilles Hendrick Manufacturing Company 48 Dundaff Street, Carbondale, Pa. Sales offices in principal cities--consult telephone directories Hendrick Bolators; Hendrick Perforated Metal Grilles; Hendrick Miteo Open Steel Flooring, Armorgrids, Shur-Site Treads HENDRICK BULATOR the dual-unit combination of a deflecting vane grille and an ornamental grille Now you can secure in a single installa tion all the advantages of an adjustable vane' grille--to direct air flow--and an ornamental grille--to harmonize with the decorative scheme--by specifying the new dual-unit Hendrick BULATOR*. It is a practicable combination that meets both the engineer's specifications for air throw and spread, and the decorative require ments of the architect. In this dual-unit, the deflecting vanes are not noticeable, although they are mounted just behind the ornamental grille. The vanes are adjustable so that the air flow can be deflected to right or left, up or down, or in a combination of both directions. For the imposed ornamental grille sec tion of the dual-unit Bulator, Hendrick offers a wide selection of attractive de signs, with the essential open area. Tested at Case Institute To determine the efficiency of the dual unit, tests were made at the Case Insti tute of Technology, Cleveland, under the direction of Professor G. L. Tuve, as a result of which, "it was found that at a given air volume, the presence or absence of the `Mosaic' (design) grille made very little difference on either the air stream pattern or the throw." A copy of the detailed report on these tests will be mailed on request. How to specify or order Hendrick Bulators In specifying or requesting quotations on the Hendrick dual-unit Bulator, the fol lowing information is required: 1. The name or description of the de sired ornamental grille, as given in Photograph taken with deflecting vanes less than an inch . behind grille, shows that vanes are not noticeable. the Hendrick Grilles catalog. 2. The metal, gauge and finish of the ornamental grille, that is required. 3. The dimensions of the air duct opening. 4. The type of deflection desired in the deflecting vane section; whether right and left, up and down, or a combination of both. Vertical deflecting vanes. showing how the vanes may be set to produce any desired air stream pattern. * Beauty + Ventilator 1446 Hendrick Manufacturing Company Air System Equipment GrSle*r' HENDRICK PERFORATED METAL GRILLES Hendrick decorative grilles are fur nished in over a hundred patterns, and in a wide variety of overall dimensions, bar sizes, and number and size of per forations. Many exclusive Hendrick designs, originally produced to meet an ar chitect's specifications for some particu lar project, are now available as stand ard numbers, and facilities for making special designs to specifications make the Hendrick service even more com plete. The wide range of patterns permits the choice of a grille that will harmonize with any style of architectural design or period construction. Arglin--55 per cent Open Area Grilles are fabricated in heavy-gauge aluminum, bronze, copper, Monel, steel, stainless steel, and other commercially rolled metals. With ample open areas and accurate sizes, Hendrick grilles are characterized by clean-cut perforations, fine finish, and freedom from burrs and other imperfections. They are easy to install, and always lie flat because of a special flattening opera tion in their manufacture. I'i^'l I'^'l (Wl IWiil Hisa IMI I'Sgjj lifrSilli&Sn iX4iih>Siiiiuiiiii*iiiiir>'.ii La Crosse--55 per cent Open Area AIR CONDITIONING GRILLES AND REGISTERS Hendrick air conditioning grilles and registers for directed air flow are made in various meshes, the standard having % in. opening between face bars. All types are furnished with either horizontal or vertical directional bars. The standard mesh can either be fur nished with grille bars permanently set at the factory for straight or directional air flow, or furnished so that the grille bars may be individually adjusted on the job to direct air flow to any desired degree. M-No. --57 per cent Open Area Front View Rear View M-No. 9.--$7 per eent Open Area 1447 Air System Equipment Grfiifs"8 The Independent Register Co. Established 1898 3747 East 93rd Street, Cleveland 5, Ohio AIR CONDITIONING REGISTERS AND GRILLES No. SS1A-HMV Tandem With these grilles, compound deflections of air flows can be obtained with ac curacy and certainty. The directional adjustment can be made at the time of installing or after the grille is in position. Each vertical bar on the front may be individually adjusted for air flow right" or left. The HMV valves on the back may be adjusted by the levers in front so as to direct the air flow up or down, or they may be fully closed. If width exceeds 24 in. the valves are made tandem as illustrated, above. Adjustable Vertical Front Bars. Adjust able Horizontal Rear Bars. Key Control opposed blades for volume control attached. No. SlID-WG Bars Fixed Down These grilles are designed for com mercial installations. Style No. 311D-WG illustrated has grille bars set permanently at approximately 35 deg. down. Othef models available have grille bars set for straight flow. No. 7 Rear View Opposed blades for volume control. No. 60A . For floor installations. Bars are set to diffuse the air up and out to both sides. Famous ` `Fabrikated * ' construction, excelling in rigidity, open area and fine appearance. Size shown 2x 14. Other sizes are made and comply with code requirements of NWAH and ACA. 1448 Air System Equipment Air Diffusers Knowles Mushroom Ventilator Co. Established 1906 All Patents Protected Main Office and Factory Upper Montclair, New Jersey 7ki92cfc)i NU-NOTCH Specifications Furnish and install where indicated on drawings or as hereinafter specified (5 in.) (6 in.) (7 in.) (8 in.) (10 in.) (Dome Top) (Flat Top) Nu-Notch Cast Iron Mushroom Air Diffusers with recessed notches for the permanent adjustment of mushroom caps at any desired open ing, together with center locking screw feature. Cast iron mushroom, successfully serving in over 5,000 buildings in U. S. and abroad. Provides correct draft-free distribution of air to each individual in any size auditorium, orchestra or bal cony. Close regulatioiTof-air--10 differ ent adjustments for all possible condi tions. Easily regulated by part turn of cap, and locked in position by tightening head screw with special key--new feature to prevent tampering. Supplied with dome or flat tops, 5 diameter sizes. Easy, permanent anchorage to wood, concrete or monolithic floors. PROPER auditorium ventilation is now recognized to be a combination of temperature, air motion and distribu tion, humidity, dust, bacteria, odors, and carbon dioxide. Air motion and distribution is second only to tempera ture in importance. The Synthetic Air Chart adopted by the ASHVE takes into account all of these factors and makes it possible to arrive at an average which will show the percentage of ven tilation obtained in any given installa tion. For nearly a half century KNOWLES has devoted itself to one specialized field --the manufacture of air diffusers for auditoriums. Write for free Guide to Distribution of Air in Auditoriums. KNOWLES NU-NOTCH MUSHROOM AIR DIFFUSER For Auditoriums MODERN practice shows that 8 cu ft of fresh air per minute per person is ample to keep the air in an auditorium free of odors; and to maintain body heat and to balance the outdoor heat of a warm summer's day, about 20 cu ft per minute per person must be introduced. The accurate amount becomes an engi neering problem too extended for this outline. Of the 20 cu ft per minute per person introduced, 12 cu ft may be recirculated, economizing heat in winter and cooling in summer. If too much air is recircu lated, odors will result; and when smok ing is to be allowed, much more new air must be introduced. Adaptability of the KNOWLES Mushroom Air Diffuser. In an auditorium seat ing 2000, requiring 40,000 cfm, it is desired to use 6 in. dia. NU-NOTCH Mushrooms with air velocity of 600 fpm. By referring to the table below, it will be seen that a 6 in. mushroom will exhaust 120 cfm. Dividing 40,000 cfm by 120 indicates 333 units are required. Size 5 6 7 8 *10y Dimensions in Inches Net Wgt. A B c D E F Lbs. 6 78HM 9H 11M K 1H nt l11yHHg 22mH 12H o3 &27W1 56 7 8 i1u0 6 VA 8H ion unyns 4 m 6H 9 n14yVa4 Area Sq Ft .1364 .1964 .2673 .3491 .5454 200 27.3 39.3 53.5 69.8 1iu0y9.v0 250 34.2 4696..18 87.3 m13u6.v3 Cfm at Velocity of 300 41.0 59.0 80.2 105.0 16w3.v6 350 47.7 68.7 19232..50 -1-9-1--.0 400 450 500 550 600 54.6 78.6 107.0 6881..22 120.6 68.0 98.0 134.0 74.8 107.8 147.4 81.6 117.6 160.8 140.0 157.0 174.5 192.5 209.4 -2-1-8-.-0 --2-4--5-.-2---2--7-2--.5----3-0--0-.-0---3-2--7-.-0 * The 1<P dia. Nu-Notch is the most economically priced Mushroom to use also affording the greatest ex haust area and least duct connections. 1449 Air System Equipment a^wSs<SUc' Register Company, Lima, Ohio Complete line of floor, baseboard, wall and ceiling diffusers, registers and grilles for heating and cooling. Bold exclusively through heating wholesalers and manufacturers. Proper Diffusion of Air There is a Lima diffuser designed to as sure efficient air distribution over a wide area from any location in the room-- floor, baseboard, sidewall or ceiling. Lima's standard sizes of heating diffusers have extra sturdy construction and are equally efficient for cooling as well as heating. Unretouched photo shows front view diffusion pattern of Lima Series 70 Extended Baseboard Diffuser. Series 70, Perimeter Extended Base board Diffuser with Automatic Push button Damper Factory set louvers assure uniform diffu sion over a wide area. Correct vertical angle eliminates wall scrubbing and al lows aspiration of room air down between wall and air stream. Equally efficient for cooling. Full length spring operated automatic pushbutton damper. Finger tip balancing adjustment. Available in 4-ft and 2-ft sizes. Can be installed in any multiples using joining connector. Permanent medium beige finish. ,fe\ I I I ft Series 75 without damper This unit is identical in sturdy construction and permanent medium beige finish as the Series 70 but without the automatic pushbutton damper feature, for economy installations where a damper is not required. Available in 4 ft and 2 ft sizes. Series 77 Matching Return For use as a return air grille in perimeter extended baseboard installations. This attractive matching unit has the same modern styling, sturdy construction and permanent medium beige finish as Lima Series 70 and 75 diffusers. Aspiration of Room Air All Lima diffusers are engineered to in duce imperceptible aspiration of room air for satisfactory indoor comfort without drafts, in heating and cooling. Photo shows Lima Series 70 side view diffusion pattern with arrows indicating how air within the room is drawn into air stream, setting up induced recirculation of room air. This air pattern holds constant even at low cfm delivery and the velocity remains'"uniform without whistling, re gardless of damper setting. 1450 Lima Register Company Series 65 Round Step-Down Ceiling Diffuser Air System Equipment Registers, Grilles And Diffusers Series 60 Square Step-Down Celling Diffuser Step-down rings have curved contour without straight edge for proper air diffu sion and greater free area. Air stream is deflected outward and slightly downward in all directions without ceiling smudges or drafts. Angle permits aspirating effect with continuous recirculation of room air. Equally efficient for cooling. Springloaded butterfly damper, with exclusiye balancing control feature. Available in seven sizes. Square design harmonizes with modern tile or block ceilings. Tiere of step-down vanes assure maximum free area with a minimum of resistance and provide effec tive air diffusion in heating and cooling. Also recommended for return air outlets, especially in perimeter systems, elim inating large, unsightly grilles. Springloaded butterfly damper. Exclusive bal ancing control feature. Six sizes available. Permanent light beige finish. Series 45 Wall Diffuser Offers perimeter heating and cooling ad vantages from side wall. Adaptable for replacing wall or baseboard registers when cooling is being added. Diffuses air upward and outward so air stream does not strike room occupants. Vertical angle induces aspirating effect of room air. Series 40 Floor Diffuser Spreads a full fan-shaped blanket of air upward and outward to both sides at reasonably high velocity. Pulls air from within the room toward outer wall, set ting up induced recirculation of air. This constant aspiration of room air is com fortable and complete without being noticed. Equally efficient for cooling. Five popular sizes are available in a choice of permanent finishes. See Sweet's Architectural File B. '-Li. For complete catalog contact your local heating contractor or trite direct to The Lima Register Company, Lima, Ohio. 1451 Air System Equipment gSikT3' Louvra Manufacturing and Sales Company Union, New Jersey Products of Satisfaction RESIDENTIAL INDUSTRIAL SCHOOL INSTITUTIONAL REGISTERS & GRILLES Louvra Manufacturing and Sales Company manufactures one of the most complete line3 offered. Carefully designed and built to highest specifications. Solid vanes. Re sistant to inward corrosion and rust. Maximum free area in all designs. Manufactured of prime steel, aluminum and brass, electro-plated finishes of all types. 1. The Flow Trol, volume controller of air, easily adjusted, complete range in setting. Adjustable tension. Vision Proof Door louvers available in three types. Core type A, core and flange type B, core flange and reverse frame type C. Maximum free area. (Not shown.) 2. 111-Series. Maximum range four way deflection supply grille. Adjustable face bars. 3. 115-Series. Maximum range single deflection register with protector vanes and adjustable face bars. 4. 116-Series. Maximum range. Four way deflection plus complete volume control and shut off. Adjustable face bars. 5. 111-S-Series. Four way deflection with adjustable range. Back vanes have screw adjustment m and out of air stream without removing face. Available on all series. Face bars adjustable on all types. 6. The 25-75 Lattice Register and Grille in 10 to 14 gauge steel. 7. 103-Series. Conversion-Aire air wall heating or cooling. 8. 110-Series. Maximum range, single deflection grille. Adjustable face.bars. Positive tamper proof volume control available on all series registers. (Not shown.) Patent Pending. 9. Vane-O-Line. One of the original strip grilles with adjustable vanes. Air System Equipment GmiS."8 Register & Grille Mfg. Co. 70 Berry Street, Incorporated Brooklyn 11, N.Y. Sales Offices in principal cities in U. S. REGISTERS AND GRILLES HEATING VENTILATING AIR CONDITIONING WE SPECIALIZE IN THE CONTRACT CONSTRUCTION FIELD Complete Line of Registers and Grilles, Plaster Frames, Angle Frames for HEATING . VENTILATING AIR CONDITIONING BLADE TYPE BAR TYPE Air Conditioning type Registers and Grilles for the maximum in directional and volume control--Noiseless Opera tion--Strength and Beauty. Registers equipped with tamperproof opposed blade action, key operated shutters. Solid 14 gauge adjustable bars make this style rugged and long lasting. Interlock ing construction makes them tamper proof, adjustable only with the special tool provided. Designed for the job where performance and quality are of primary consideration. Architects and Engineers have specified both of these type registers and grilles for America's finest Schools, Hospitals, and Public Buildings. Each of the above types is a complete line in itself and is available in all the standard styles. 81 STYLES OF PERFORATED GRILLS Available in Bronze, Aluminum, Stainless Steel and Steel. Trade Names Include Directrol, Quantrol, Alrcon Shutter, Arrowtrol Shutter, 13W Frames. Catalog on Request 1453 Air System Equipment outlets and Grilles The Pyle-National Company Multi-Vent Division 1363-78 N. Kostner Ave. Chicago 51, Illinois Sales Engineers and Agents in Principal Cities of U. S. and Canada < S A. Air Duct--recommended air velocity 1000 fpm. B. Four inch dia. clean cut hole in bot tom or sides of duct to receive duct collar. C. Four swinging anchor clips support panel on tee-runners of metal pan ceiling suspension. D. Any standard perforated 12 in. x 24 in. acoustical metal pan (with pad re moved), supplied by ceiling contractor, functions as a distribution plate in metal pan ceilings.* E. MVC Duct Collar. Snaps into 4 in. dia. hole. No tools required. F. MVH--Flexible and compressible, neoprene impregnated, fire-retardant, fiber-glass tubing permits variation in alignment between duct opening and panel. G. MVM--Modular Panel with adjust able perforated volume control valve. Seats in standard metal ceiling pan, plaster or tile perforated distribution plate. (See below.) H. Perforated distribution plate MVP, MVT or standard acoustical inetal pan to suit ceiling construction. S m-&.V ifi M i '-A*.!? M D. ADVANTAGES OF MULTI-VENT TYPE AIR DIFFUSER 1. Conditioned air is delivered straight 4. Eliminates dirt smudge on ceiling, down into the room at a comfortable low velocity. 2. Complete concealment when used with standard perforated metal pan ceil ings. 3. Complete freedom of partition move ment with no mechanical adjustment or usually found adjacent to conventional diffusers having horizontal high velocity distribution. 5. Exceptional performance with no drafts even when used on applications requiring 60 air changes per hour. relocation required because air gently drops straight down. Sect-l-C-Page-37 of the Multi-Vent Engineering Manual for Sound Level Data. 1454 Air System Equipment ouUets and Grille THE PYLE-NATIONAL COMPANY Multi-Vent Division MVM MODULAR PANEL ; SELECTION DATA Static pressure required in inches water gauge for duct applications at vari ous valve settings. Pres sures listed include distri bution plate, panel, valve and 12 in. length of 4 in. dia. tubing.* VALVE OPENED TO: CFMf BTU/ LIMIT HR 60 971 45 971 36 971 M* H* H' H' .138 .076 .048 .099 .055 .035 .087 .048 .031 .077 .043 .027 For plenum applications'consult factory t Refer to sound level chart when perforated acoustical ceiling pans are used for distribution TYPE-MVAR UNITARY MULTI-VENT PANEL 1. The Control Plate and Frame are in stalled in the bottom of the air supply duct of plenum or in a collar extending down through the ceiling. cleaning equipment, perforations will ' not clog. 2. The Pressure Displacement Air Valve is located in the center of the control plate. Its function is to control the volume of air admitted to the unit and to reduce both velocity and pressure of the incoming air. 3. The Perforated Plate spreads the de livery of the incoming air over a large area and further reduces the velocity which, in a typical installation, is only 30 to 50 ft per minute at 6 in. below the perforated plate. Even tvith relatively inefficient air Type MVAR Multi-Vent Panel for duct or plenum application* TYPE MVAR PANEL SELECTION DATA PANEL CATALOG No. MVAR-122-1 MVAR-123-2 MVAR-124-2 MVAR-125-3 MVAR-126-3 W dth ft PANEL DIMENSIONS .c g < 12 2 3 14 15 16 3 4 5 6 COOLING OR COMBINATION HEATING <fc COOLING LIMITS PER PANEL CUBIC FEET PER MINUTE BTU/HR SENSIBLE HEAT 5 T/D 74 111 148 185 222 10* T/D 70 105 140 175 210 15* T/D 60 90 120 150 180 20* T/D 46 69 92 115 138 25* T/D 36 54 72 90 108 5* T/D 405 600 799 999 1199 10* T/D 756 1134 1512 1890 2268 15* T/D 972 1458 1944 2430 2916 20* T/D 994 1490 1987 2484 2981 25* T/D 972 1458 1944 2430 2916 MVAR-224-1 2 8 280 240 176 144 104 1512 2592 2851 3110 2808 MVAR-245-1 2 5 10 300 300 220 180 130 1620 3240 3564 3888 3510 MVAR-246-1 2 6 12 300 300 264 216 156 1620 3240 4277 4666 4212 MVAR-364-1 3 4 12 300 264 216 156 120 1620 2851 3499 3370 3240 MVAR-365-1 3 5 15 300 300 270 195 150 1620 3240 4374 4212 4050 M VAR-365-2 3 5 15 450 330 270 195 150 2430 3564 4374 4212 4050 MVAR-366-1 3 6 18 300 300 300 234 180 1620 3240 4860 5054 4860 MVAR-366-2 3 6 18 540 396 324 234 180 2916 4277 5249 5054 4860 1455 Air System Equipment 252* Standard Stamping & Perforating Co. 3111 W. 49th Place, Chicago 32, Illinois Air Conditioning Registers and Grilles--Cold Air Faces Perforated Metals for all Purposes No. 551 Perimeter Wall Register Gives four way air diffusion. Equipped with Fractionator Volume Control and Damper Tension Screws. Also available with a base extension as Model No. 451 perimeter base board-register,, No. 331 Sidewall Register Horizontal multiple valve louvres at tached to vertical "bend-ezy" faces, adjustable for four way deflection. B-24 Perimeter Baseboard Diffuser Maintains heating and cooling comfort at a high level. New Adjustamatic finger tip control regulates built-in damper. No damper installation required. Pro vides uniform temperature along outer walls, keeping floors warm and avoiding condensation on windows. Replaces lost heat immediately, where it's lost, with out creating blasts, hot spots, or cold corners. 2 ft sections, 4}4 in. high. Open area 28 inches. Heavy gauge steel construction, baked-on metallic finish. No. 100-LO Multiple Louvre, Lever operated register. Also available as:'100-KL, a Key Oper ated register; 100-RK, a register with a Removable Key; 100-PO, a Pulley Oper ated register (especially suited for inac cessible installations). Register faces are attached to louvre boxes with screws so that the boxes are detachable. Single System Ceiling Air Diffusers For Air Conditioning And Warm Air Heating Supply full dimension distribution of warm air in the winter and cool air in the summer. FLUSH or EXTENDED models available with dampers and in stallation rings. Both models are finished in Standard's baked-on metallic finish Packed one to a box and 10 to a carton Complete specifications will be furnished upon request 1456 Air System Equipment Registers Grilles Stewart Manufacturing Co., Inc. Cedar Grove, Essex County, New Jersey A complete line of Registers, Grilles and Scoops for all types of Industrial and Residential air conditioning applications. DDV A double deflection grille afford ing four way diffusion--individually ad justable streamlined fins % in. C.-C. heavy gauge metal and sturdy construc tion. - rfii B - ira-.a II Bf H 'll1 ii_.b 'it; Cl *_ /lhih|i i|i /a .im- iii r"' a as .SB .as s ii ee i B II ill 8- si - ii a n IK is tKs saa'lniIiIBltInIi5s i i ii b sc I 1 111 s B ipna ~is 08 a BJ SIB (i B S !B I BI [1111 IS 05 a. si sia itr'c'ia i ei it is as BB -SlSiVSi S 18 91I 'll I B 1 illl ' U e'g: wrr si9 tv it a_ti i- i mi fl s DVL A directional-type register em ploying 1 in. wide, parallel-acting valves. Face fins are individually adjustable right and left. The 1 in. wide, parallel-acting valve mechanism is available with any/all STEWART face patterns. DDVO A double deflection grille with opposed action valves. The valve con sists of a series of hollow, internally rein forced air-foil sections. Through a unique actuating mechanism each air-foil sec tion turns in a 90 deg arc toward a simi larly turning section. SCOOPTROL A device designed to de flect and control the air from a supply duct into a collar, and installed at the junction of the duct and collar. Scooptrol is a double-blade functional product, easily adjusted, positioned and then fastened by sheet metal screws; it cannot move or fall. DG An exhaust grille with non-adjustable fins. Fins are normally factory set at 45 deg down angle to restrict vision. Also available with fins set at 0 deg vertical or horizontal. PLASTER FRAME Permits the removal of grille when desired without damage to surrounding painted areas. FINISH DIRECTIONAL TYPE OUTLETS ARE PROTECTED BY A PRIME COAT FINISH AND A FINISHING COAT OF SILVAIR ENAMEL, BAKED ON. SILVAIR FINISH IS A MODERN, ATTRACTIVE COATING CONTAINING ALUMINUM PIGMENT, AND IS SILVER-BLUE IN TONE. NO ADDITIONAL PAINTING IS REQUIRED. Send for Illustrated Catalog No. 55 ' 1457 Air System Equipment g^uST* AIR C0HVITI0HIH6 OUTIETS \y Titus Mfg. Corp. WATERLOO, IOWA Titus Mfg. Corp. are designers and manufacturers of Airfoil Grilles featuring the Airfoil Louver--patterned after the air foil section of an airplane. The following distinctive features identify Titus Airfoil Louvers. (1) Smooth as glass stream lined surface (2) Solid construction (3) Noiseless performance (4) Minimum turbulence. 270 Airfoil Grille Gives 4-way directional control. Louvers set on % in. centers. In dividually adjustable to create any air pattern desired. 276 4-Way Multi-Shutter Register Con sists of the S 270 4-way directional grille combined with a multi-shutter damper. Damper blades inter-locked when closed to provide complete shutoff. 274 Multi-Shutter Register Airfoil Lou vers are featured in front. Individually adjustable. Rear multi-shutter damper blades. 277 4-Way Registers with opposed blade dampers. Two front sets Airfoil louvers individually adjustable, % in. spacing. Opposed blade damper key operated in rear. 275--Double deflection register with op posed blade damper, key operated.' 230 Return Air Grille--blades on % in. centers. Parallel to long dimension. Deep fins. Standard in. beveled border. Any size grille can be furnished. R-240 (not illustrated) combines # 230 Return air grille with multisnutter damper blades. R-241 (not illustrated) combines #230 with opposed blado damper. 1458 Titus Mfg. Corp. Air System Equipment Grujts" AG-25 Volume Controllers provide posi tive control of air volume. Blades indi vidually adjustable. Sponge rubber gasket holds unit firmly in duct. Door Grilles--No vision door and parti tion grilles. Made with flange frame or channel frame. All steel--V shaped louvers. T-700 standard thickness. T-800 thin core. AG-35--Opposed acting volume con troller. Provides complete control of air volume to the outlet with minimum disturbances of air pattern. Louvers move simultaneously in opposite direc tions and can be set at any degree from full open to full closed. 200 Series--New hi-efficiency sidewall or ceiling diffuser. Adjustable curved de sign louvers. 1, 2, 3, or 4 way deflection. AG-45--Air volume extractor and con troller. Will`control air volume and also produce balanced air distribution. Re places extra volume controller. Fifty percent savings on cost and installation. CONVECTOR GRILLES--Louvers closely spaced. Heavy-duty support bars on 6 in. centers. Over 70 per cent free area. Can be installed in any spe cial surface, such as marble or tile. Perimeter Baseboard Diffusers--Made in 17 in., 30 in. or 60 in. lengths complete with built-in damper. Easily installed. Outstanding performance. FRAME 115 FOR ALL AIRFOIL GRILLES AND REGISTERS (not illus trated) Allows quick easy removal for cleaning or adjusting. Can be installed either before or after plastering has been completed. WRITE FOR NEW ILLUSTRATED CATALOG. 1459 Air System Equipment f Engineered Produets for Residential, Com mercial and Institu tional Air Condition ing, Heating, Venti lating NEW BRITAIN, CONNECTICUT HIGH PRESSURE AIR DISTRIBUTION UNITS TYPE MPW TYPE MP Medium Pressure Periphery Wall Mixing Plenum Unit for individual room control on heating or cooling cycle, or zone control. Handles static pressure in system up to 3.5 in. w.g. Medium Pressure Sub-Central Station Unit for' distribution of air to one or more diffusers by means of rigid or flexible ductwork.. Handles static pres sure in system up-to 3.5 in. w.g. TYPE MPD Medium Pressure Ceiling Diffuser TYPE HPD Double Duct Mixing Plenum Unit for High Pressure Ceiling Diffuser Unit for individual unit or zone control. Single individual unit or zone control. Handles duct units also available. Handles static static pressure in system up to 6.0 in. pressure in system up to 3.5 in. w.g. w.g. 1460 Tuttle & Bailey Air System Equipment Registers Grilles Aerofuse ceiling diffusers A wide selection of diffuser types and sizes, styled and engineered to meet the most rigid requirements of appearance and performance at the point of air delivery. TRI-FLEX SUPPLY AIR GRILLES AND REGISTERS 8x4 10 x 4 10x6 12 x 4 12 x 5 12 x 6 Available as single and double deflection grilles; single and double deflection registers with opposed blade dampers. Blades are regulated by means of a key operator and may be set in any position from fully open to fully closed. Face bare are individually adjustable. Stocked in 26 standard sizes. 26 STANDARD SIZES 14 x 4 14 x 5 14 x 6 16 x 5 16 x 6 20 x 5 20 x 6 20 x 8 24 x 5 24 x 6 24 x 8 24 x 10 24 x 12 30 x 6 30 x 8 30 x 10 30 x 12 36 x 8 36 x 10 36 x 12 . AEROVANE RETURN AIR GRILLES AND REGISTERS Aerovane grilles are available with horizontal or vertical bare. Aerovane registers are furnished with the same opposed blade damper units as supplied; with Tri-Flex registers. Stocked in 20 standard sizes. 1461 20 STANDARD SIZES 10 x 6 10 x 8 12 x 6 12 x 8 12 x 12 18 x 6 18 x 12 18 x 18 24 x 12 24 x 18 24x24 30 x 12 30 x 18 30x24 36 x 18 36 x 24 36 x 30 48 x 24 48 x 30 48 x 36 Air System Equipment gSSST15 United States Register Company General Offices: Battle Creek, Mich., U.S.A. Branches: Minneapolis, Minn., Kansas City, Mo., Albany, N. Y. Air Conditioning Registers, Vents and Grilles No. 153--Single-Valve Air Conditioning Register-Bars in. deep--Spaced 4 openings to the inch affords Non-Vision. Can be supplied in Directional Flow in either Horizontal or Vertical Bar Styles. Can be furnished with all styles of Setting Frames. S M 4*1 Ho. 249--Multiple-Valve Air Condition ing Register. Gives complete Air Con trol. Vertical Front Bars--Key-pin ad justed to provide 45 deg Right and Left or Two-way Side Flow. Lever operated Horizontal Back Valves Give from Full Closed to any degree of Upflow and to 45 deg Downflow. FULL FACE COV ERAGE. Can be supplied with any style of Setting Frame. Fits all Stack Heads of Standard Size Dimensions. irtfirfG?:: ;r 1>nl>fit . -| 11 mi u in i > iiiuimi nu in ini iinn.ip iy|T|--jil, fril'ii H'wnn rtit.iki u i <i i > V iiiiiinniiiiimJtinmiiL. riiniiitmrrmiiiHnrMnimnjH'iii'mhiihJm.Lvi P""'A No. 256--Multiple-Valve Flex-bar Air Conditioning Register. Vertical Front Bars set 22 deg Right and Left. Side Flow Deflection attained by setting of Grille Bars with bending wrench to accommodate room condition. Back- valves give same Up and Down control of air flow as No. 249 above. FULL FACE COVERAGE. Can be supplied with any style of Setting Frame. Fits all Stack Heads of Standard Size Dimen sions. 1 '4^ .iff "St m m- -1& -c 'S-IK if i& 4- All of above Styles can be supplied with either Lever or Individually adjusted Multiple Valves or Louvers, i.e. 177VVI --Vertical Valves Individually adjusted. 145WL -- Lever operated Vertical Valves. Specially adapted to Combina tion Heating and Cooling Systems. Grilles and Vents in Matching designs are available. For Complete Information Write for Catalog No. 55-6. No. 153-WL Horizontal Bar Non-Vision Design Vertical lever operated rear valves. No. 145-VVL--Specially adapted to Combination Heating and Cooling Systems. Horizontal Bar Adjustment to 60 deg Up and Down Flow. Multiple Valve A. C. Registers available with Key Operation. 1462 ixV' ; United States Register Co. Air System Equipment Registers Grilles No. 500 U S. Round Celling Diffuser Step-Down Style No. 1000 U.S. Super Base Diffuser is equipped with Balancing Set-Lock and Adjustable Slide-Plate bottom opening. Furnished in 2 ft and 4 ft sections with which any continuous lengths may be assembled. No. 1000_U.S. Super Base Diffuser A No. 500 U. S. Round Ceiling Diffuser. Made in 6 in., 8 in., 10 in., 12 in. and 14 in. sizes. Furnished with or without No. 900 frames. However, frames are rec ommended. No. 500 diffusers will be furnished with Dampers when required. No. 410 U. S. Perimeter Floor Register. No. 105 U.S. Diffuser Sidewall Register furnishes a complete 180 deg Sunburst Diffusion at an even fpm at every degree of air diffusion. No. 105 Diffuser Sidewall No. 191 U. S. Multi-Flex Register Streamlined Double-Edged Grille bars. Front bank of bars--Horizontal Adjust able. Second bank of bars--Vertical Adjustable. Opposed Rear Valves-- Key operated. .* No. 191 U. S. Multi-Flex Register No. 190 U.S. Multi-Flex Register A No. 190 U. S. Multi-Flex Register Stream lined, Double-edged Grille bars. Front bank of bars--Vertical, Adjustable. Second bank of bars--Horizontal, Adjustable. Opposed Rear Valves-- Key operated. No. 192 U. S. Multi-Flex Register--same as No. 190--but with Vertical Front Bars. No. 193 U. S. Multi-Flex Grille--same as No. 190--but less Rear Valves. No. 194 U. S. Multi-Flex Grille--sameas No. 191--but less Rear Valves. No. 195 U. S. Multi-Flex Grille--same as No. 193--but Vertical Bars only. No. 196 U. S. Multi-Flex Grille--sameas No. 194--but Horizontal Bars only. See our Catalog No. 55-6 for the additional Non-Flex Register and Grille Line. ' 1463 Universal Diffuser Corp. 1360 Garrison Ave., New York 59, N. Y. Manufacturers of FLEXIFLO Adjustable Diffusers Flexifio-Type R and V Flexifio-Series MP Flexiflo-Adjwtdble Series IfA R VARIABLE EFFECTIVE AREA The FLEXIFLO diffuser is unique in that it has an infinitely variable effective area. All blades move simultaneously when the control knob is moved up or down. This provides a simple, effective means of controlling the volume of air. The pattern of diffusion for cooling pur poses remains constant on the Type "R" FLEXIFLO. For cooling and heat ing purposes the Type "V" FLEXIFLO provides a variable pattern of diffusion from horizontal to downflow. Type R--For Cooling Provides a diffusion pattern and radius of diffusion that are not altered by change in air volume. Air leaving the Type R diffuser always travels parallel to the ceiling, assuring satisfactory per formance under all operating conditions. Type V---For Cooling, Ventilating and Heating Has a special blade configuration that gives a variable air distribution cone from horizontal to downward flow. Air can be delivered at practically any angle. Type S--For Side Wall or Ceiling Instal lations Model SC is for ceiling installations in cooling work. Model SW is for wall installations. Every Type S diffuser has one set of equalizing deflectors. Series MP--Multi-Pattern Diffusers FLEXIFLO Series MP diffusers are made to order in all rectangular shapes for one, two, three and four way blows to accommodate rooms of irregular shape. The diffusion pattern is parallel to the ceiling in all cases. Standard finish is metallic gray baked enamel. Other cqlors are available at no extra cost. Series H^R The FLEXIFLO HAR Series of adjust able square diffusers is built for either i ceiling or acoustical tile installation. The blades move simultaneously when the control knob is moved up and down. Air volume can thus be controlled with great precision and can be varied be tween near zero and full output at con stant horizontal pattern. 1464 I Air System Equipment co,SShf1DaSg Waterloo Register Co. Inc. "Since 1902" P.O. Box 72 Waterloo, Iowa Complete Line of Air Diffusion Equipment for All Air Conditioning and Heating In stallations. Offers: Performance. Appearance. Selection. Prompt Delivery. Features Silent Flow "Tear Drop" Louvre Design which provides unobtrusive diffusion with SUFFICIENT SURFACE to turn high velocity air WITHOUT TURBULENCE. 2V SUPPLY GRILLE Two sets of extruded aluminum louvres, each individually adjustable for four way deflection at degree desired. De signed for long or short throw. 3H RETURN AIR GRILLE Fixed fins at 45 degree or 0 degree deflec tion, in heavy gauge frame, strengthened with adequately spaced support bars. IVMH SUPPLY REGISTER One set of adjustable louvres for easy control of air, right or left, with multi shutter damper, horizontal blades. Ideally suited for home installations be cause of narrow stack depth. DV DOOR VENTILATORS V-Shaped fixed fins, permanently spot welded in channel frame for rigidity. Offers more than 57 per cent free area, yet completely sight proof. Available flange both sides, one side, or no flange. 2VO SUPPLY REGISTER DUCTROL Air Volume Extractor Two sets of adjustable louvres, vertical and horizontal, with opposed blade damper, vertical blades, for even volume control. Fins spaced on % inch centers. Provides positive air control. Volume controller and extractor adjusts from full open to full closed, to provide even distribution to entire grille surface. Completely assembled at the factory-- ready to install on job. Waterloo 6-page "Size Selection Table" available in folder form to use in making SIZE SELECTIONS of outlets on comn ercial jobs. Air System Equipment. Duro-Dyne Corporation 800 Third Avenue, New Hyde Park, N. Y. Manufacturers of Accessories for the Sheet Metal, Heating, Air-Conditioning and Ventilating Fields -NEVA DURO-BLADE KIT Multi-blade Louver Damper Hardware The Neva Bind Duro-Blade Kit--multi blade louver damper hardware permits smoothly operating, absolutely non-bind ing dampers to be assembled with little care and no alignment afterward. The Kit's unique 4-way adjustability auto matically compensates for slight errors in blade dimensions or formation, minor misplacements of bearing holes or other inaccuracies which cause stress or bend ing of the connecting rod--the main cause of binding. The Neva Bind feature allows the rod to remain absolutely straight regardless of inaccuracies in damper construction. Besides operating smoothly and never binding, dampers made with the Neva Bind Duro-Blade Kit can be fully closed without the'bracket hitting the duct. The damper can be fully opened without interference of the con necting rod. JIFFY DAMPERS Complete, Prefabricated Dampers for Round Pipe Jiffy Dampers are complete, prefabri cated dampers ready for immediate in stallation in ductwork. A comparable damper fabricated in the shop costs con siderably more. The P-K Jiffy Regulator (now manufactured by Duro-Dyne) is Ere-attached to a galvanized damper lade. The steel threaded bearing will never break. There are no loose parts to rattle. JD Series--Consists of damper plate with a Yu in. square end bearing, washer, handle and wing nut. JDS Series--Same as JD Series plus atented P-K Spring-Loc Bearing. For igh air velocities or when necessary to keep damper in perfect position. JD and JDS Series Jiffy Dampers are regularly available in 4 in., 5 in., 6 in., 7 in., 8 in. and 9 in. pipe sizes. Other sizes, and rectangular dampers on quo tation. JD Series--No Spring-Loc DAMPER REGULATORS AND CONTROLS (formerly Manufactured by Parker-Kalon) UNXLD Damper Quadrant Heavy Duty Quadrant Jiffy Regulator 1466 Dial Damper Regulator Duro-Dyne Corporation Air System Equipment Regulators and Controls; Tools FLEXIBLE DUCT CONNECTOR PRODUCTS Rolls of Preassembled Metal-to-Fabric-to-Metal LAID OUT AND PUNCHED SIDE RAILS FOR MAKING AIR TURNING VANES___ Air turning vanes made with DuroVane-Rail side rails save 50 per cent to 70 per cent in installed costs. Vanes are. merely sheared from scrap. No tab cut ting on vanes is necessary. Insert vanes in notches provided in Duro-Vane-Rail. Duro-Metal-Fab and Econ-O-Fab are preassembled metal-to-fabric-to-metal for making flexible duct connectors (for eliminating vibration travel). They eliminate the annoying time-consuming job of attaching metal to fabric in the shop. The exclusive Double-Loc Seam cannot pull apart and prevents the metal from cutting the fabric when the finished connector vibrates. Duro-Metal-Fab for industrial or heavier gauge ductwork consists of 124-gauge galvanized iron at tached to U.L.-Approved Canvas, As bestos or Neoprened Fiberglas. Econ-OFab, tor residential and lighter' gauge ductwork, is identical to Duro-MetalFab, except lighter. Both Duro-MetalFab and Econ-O-Fab are packed 50 ft or 100 ft to the handy Dispens-O-Flat carton. DUCT FABRIC is available for special cases where fabrics without metal are de sired. Packed in 100 ft rolls, available 6 in. or 10 in. wide canvas and 6 in. wide asbestos or neoprene. TOOLS FOR SHEET METAL FABRICATION Greyhound Portable Spot Welder Place chisel (supplied with each bundle of Duro-Vane-Rail) on protruding por tion of vane in slot. One blow securely locks vane to rail. Duro-Vane-Rail al lows maximum free area; eliminates noise and "whistle." Completed air turn ing vane assembly meets most engineer ing specifications. X. X. Metal Punch O. X. Metal Punch Shur-Grip File and Solder Iron Handles UNXLD DAMPER QUADRANT SET-- H in. size used for dampers up to 20 in.; Al in. size for dampers up to 30 in. Pro vides positive control. Sturdily con structed, easily installed and adjusted. HEAVY . DUTY QUADRANTS--Regu late larger size dampers up to 60 in. The ball bearing quadrants are fine manually operated, heavy duty units. The plain bearing quadrant for larger regulators up to 52 in. has the same rugged con struction except for the ball bearing feature. Sizes % in. to 1 in. JIFFY REGULATOR SET--Installs more quickly since it does not have to be attached to the duct. DIAL DAMPER REGULATOR SET-- J4 in. size for dampers up to 10 in.; % in. size for dampers up to 20 in. Special construction prevents air leakage and damper rattle. Made of heavy gauge steel, cadmium plated. 1467 Air System Equipment Eigen Manufacturing Corporation 41-34 39th St., Long Island City 4, N. Y. ELGEN SILENT DUCT--Pre-assembled metal and material for flexible duct con nectors. ELGEN ALL-TITE VANE RUNNERS--for making turning vanes for square elbows. ELGEN DAMPERSET--for damper control in blower and exhaust systems. ELGEN SILENT DUCT Factory-assembled metal and material. Delivered in dispenser carton . . . pulls out flat, ready to use. Union made. Available in 24 or 26-gauge galvanized steel . .. Fastened to fire, water and mildewresistant UL approved canvas (Govt. Spec. MIL-D-10860) or to. JohnsManville asbestos (wire-filled, if desired) or to U.S. Rubber Co. Neoprene-coated fiber glass. Delivered in 100-ft (approx.) coils; 50-ft coils with asbestos available. ELGEN ALL-TITE COILED VANE RUNNER Button .Type for single and double blades Quick, inexpensive method of making turning vanes. 24-gauge galvanized steel. Eliminates notching, punching,-etc. No special tools needed. Is screwed into elbow . . . absolutely rigid and rattleproof. Delivered in the 100 ft coils (approx.) Unrolls absolutely flat. Union made. ELGEN DAMPERSET for multi-blade dampers--parallel or opposed Licensed by Minneapolis-Honeywell. Quick and easy to assemble. Precision-machined--cadmium plated. Bronze self-oiling bearings. Packed in single boxes or bulk 100's. All Eigen products engineer-approved; available at leading jobbers in U. S., Canada, Hawaiian Islands. Descriptive literature on request. 1468 Air System Equipment Flexible Duct and Connectors The WI[il@lilliiyD) Company Hartford 10, Connecticut Manufacturers of Wiremold Air Duct for Commercial Air Conditioning Systems. Wiremold Air Duct has REMARKABLE FLEXIBILITY ... proved on every type of Commercial Air Conditioning System! Designed for connecting air-distribution units to branch ducts, strong, durable, and extremely : flexible Wiremold Air Duct conducts air at temperatures of 0 to 250F at high or low velocities. Wiremold Flexible Air Duct Type 57-1A connecting four diffusers to sound box and sound box to main duct tn modular ceiling construction. Takes all bends without kinking. Flexi bility of duct allows for expansion and contraction of system and prevents transmission of mechanical vibration. Wiremold Engineering Data Sheets give details of Wiremold Air Duct installa tions. Send for your copies. Type S7-1A, 6-in. and 7-in. IJ). flexible connectors high velocity system. City County Building, Detroit. Unique construction--vinyl coated fiber- glas fabric mechanically locked into the steel spiral--gives Wiremold Air Duct extraordinary longevity and strength. No glue or other adhesive to dry out and crack. Saves time, effort, and money in in stallation--easily bends 90 deg to 180 deg. Can be easily run around structural members. Solves misalignment problems. Finished modular ceiling installation--Wiremold Air Duct permits relocating of diffusers. There are WIREMOLD AIR DUCT SALES ENGINEERS to give you onthe-job service throughout the United States and Canada, 1469 Air System Equipment Air Row Regulators Young Regulator Company 5209 Euclid Avenue, Cleveland 3, Ohio YOUNG SURFACE - CONCEALED - SPLITTER - SQUEEZE - REMOTE CONTROL DAMPER REGULATORS No. SIS No. 700-CP A complete line of manually controlled damper regulators for every type of heating, ventilating and air conditioning installation in office buildings, factories, hospitals, ships, schools, churches and residences. Young Regulators are used by many leading companies in nearly every industry and are specified by lead ing architects and engineers. Model No. 1, FOR SURFACE MOUNT ING. The original Young Damper Regu lator, of which thousands have given satisfactory service for years, has been modernized and streamlined. It is used to regulate a damper, controlling the air flow through a duct. It is readily set and locked into position by a key. Model No. 315, ADJUSTABLE COVER CONCEALED REGULATOR. For use in acoustical ceilings. Similar to No. 301 Concealed Type, except the cover plate is adjustable for height to meet the var ious thicknesses of acoustical or plas tered ceilings by screwing down the cover plate. The adjustment or locking the regulator is by a socket wrench. Model No. 700, CP REMOTE CONTROL. For manual operation of dampers and registers to give individual room tem perature by remote control. With No. 704 Corner Pulleys, Remote Control operates Young Dampers at a distance of 250 ft or more. Two registers or dampers can be operated by a single unit. Model No. 9C0, AIR-SPLIT REGULA TORS. For operating a splitter or squeeze damper. Operating head may be placed in any accessible location. Opera tion is by a crank. Model No. 914, CONCEALED AIRSPLIT REGULATOR, with beveled gears. It is used when regulator is operat ing a vertical damper from suspended ceiling. No. 301 Operator is used. Model No. 912, CONCEALED AIRSPLIT REGULATOR. It is used when regulator is operating a horizontal damper from suspended ceiling. No. 301 Operator is used. No. 900 1470 Young Regulator Co. Air System Equipment celim* OPPOSED BLADE DAMPERS-- REGISTERS--GRILLES--CEILING DIFFUSERS Model No. 830, OPPOSED BLADE DAMPER distributes the air evenly over the entire face of the grille. It is easy to install in the duct behind the grille. It is operated by a Young Remote Control placed in any convenient location. Tub ing to Remote Control is attached to duct by Young Compression Fitting. Furnished as part of No. 840 Series Air Conditioning Register, No. 855 Ceiling Diffuser, or separately. Model No. 831. Same as No. 830, but without the Remote Control attachment. It can be locked in any position. A Phil- lips head screw driver is the tool required to operate it. No. 840 SERIES REGISTERS is a com bination of the various No. 800 Grilles and a vertically Opposed Blade Damper. All specifications as to register construc tion are identical to the No. 800 Series details. These registers give individual room control when operated by Model No. 700 Remote Control. No. 800 SERIES AIR CONDITIONING GRILLES. Grille bars are made of ex truded aluminum secured in a frame and dividing mullions. They must be ad justed with a hand tool, lessening the possibility of tampering. Gasket is furnished with all supply grilles. No. 800-VH has double banks of blades, one vertical, the other horizontal, both banks adjustable. SERIES No. 845 RETURN AIR GRILLES for intake has been designed to match the No. 800 Series for supply. No. 855, CEILING DIFFUSER is de signed to distribute the air without drafts. The unit has two banks of bars; each bank is 4-way adjustable to 45 deg angle to direct the air flow. The Opposed Blade Damper that is attached to the Diffuser is controlled by Young No. 700. Remote Control. No. S30 No. 840-H No. 800-VH No. 84S-D No. SIS FOR COMPLETE DETAILS SEE OUR CATALOG IN SWEET'S FILE ARCHITECTURAL ^ 1471 Controls and Instruments Alco Valve Company ENGINEERED REFRIGERANT CONTROLS 851 Kingsland Avenue, St. Louis 5, Mo. New York Office: 55 West 42nd Street Chicago Office: 4554 North Broadway _ THE COMPLETE LINE OF REFRIGERANT CONTROLS ALCO THERMO EXPANSION VALVES: for automatic control of liquid refrigerant on all types of refrigeration and air conditioning systems. Capacities--from frac tional tonnage to 220 tons "Freon-12," 350 tons "Freon-22;" selective charges. Low . temperature valves for --40F to -- 100F. It FI VI fl Type 401 uith prosure limiting feature Type TK . "J valves in 1" . Type TCL Angle type or straight- through connections Type TS-- Multi-Outlet ALCO SOLENOID VALVES: for all types of service. For Liquid: "Freon-12" up to 75 tons; 110 tons "Freon-22." For Suction: "Freon-12" up to 10 tons; 15 tons "Freon-22." For brine, water, steam, hot gas discharge, air and oil. Type St Type MS Type RS . ALCO AMMONIA CONTROLS: Solenoid Liquid Valves--up to 172 tons. Solenoid . Suction Valves--up to 28 tons. Thermo Expansion Valves--from fractional tonnage to 125 tons. Automatic Expansion Valves--from fractional tonnage to 60 tons. % f1 Type M91P Type UG ALCO SUCTION LINE^CONTROLS: TypeTX. Type E with Strainer 1* t Type EPR EVAPORATOR PRESSURE REQULA TORS--for all re- frigerants, with con nection sizes up to 6 in. Types 771-772 SUCTION PRESSURE REGULATORS--HOLDBACK VALVES--prevent motor - overload. Freon-12, Freon-22. . Type 760 "EVAPOTROV --Pressure Regulator-- H ton, "Freon-lt"--ton,Methyl Chloride, ALCO ALSO MAKES: Constant Pressure (Automatic) Expansion. Valves--Liquid and Suction Line Strainers--High Pressure Float Valves--Electric Float Switches-- Reversing Valves. . 1472 Controls and Instruments Barber-Colman Company Automatic Temperature Controls Rockford, Illinois THERMOSTATS OUTDOOR RESET CONTROLS Single and two-stage room and remote bulb thermostats for on-off control; room and remote bulb thermostats for proportioning control. MOTOR-OPERATED VALVES Both fixed and adjustable ratio outdoor reset hot water controls applicable to any size building. ELECTRONIC CONTROLS A complete line of factory-assembled motor-operated valves for two-position and proportioning control. On-off or fully proportioning. Extremely sensitive and flexible control of air or liquid temperature. Large, legible, easily understood dials. Mounted in metal "Control Center." ECONOSTAT ZONE CONTROL CONTROL MOTORS--PROGRAM SWITCHES Spring return, unidirectional, reversible, multi-position, and proportioning types. Adjustable speed optional. Program switches for multiple step control of compressors, pumps, etc. Outdoor-indoor zone control for multi occupancy buildings. Night depression with automatic morning warm-up. Op tional week end cutout. 1473 Controls and Irisi.uments Cam-Stat, Incorporated Division of The Paul Henry Company 11831 W. Olympic Blvd. Los Angeles 64, California District Offices in AH Principal Cities AUTOMATIC TEMPERATURE CONTROLS These compact warm air furnace controls are available, as shown below, for integral mounting on the furnace, and also in conduit housings to meet U.L. requirements for plenum or duct mounting. Any one of the controls below is available in combination with any one of the other controls, complete in a conduit housing. Extreme sensitiv ity is obtained through the use of a low mass bimetal actuator. This insures uni formly accurate control results even with high rates of temperature change. FAN CONTROL FIXED LIMIT CONTROL Hotel No. FH-llA Specification: Range--80 to 120 F. Differ ential--25 F. (Fixed). Rating--hp at 120 or 240 volts A.C. Other differentials available on request. Model Ltl-TA Specifications: Fixed cut-out and dif ferential to manufacturer's requirements. Rating--90 volt-amps at 30 volts A.C. . ADJUSTABLE LIMIT CONTROL FAN CONTROL Model LSI-8A Specifications: Range--170 to 200 F, or to manufacturer's requirements. Dif ferential--Fixed anywhere between 15 and 50 F. Rating--90 volt-amps at 30 volts A.C. RESET LIMIT CONTROL 1 1 3 $ v.->: f Model No. FI4-11A Specification: Range--80 to 120 F. Differ ential--20 to 35 F. (Adjustable). Rating --% hp at 120 or 240 volts A.C. Model No. LSS-9A Specifications: Fixed cut-out to manu facturer's requirements. Equipped with push button to reset after cut-out. Rat ing--90 volt-amps at 30 volts A.C. 1474 Controls and Instruments Combustion Control Division ELECTRONICS CORPORATION OF AMERICA 718 Beacon Street, Boston IS, Mass. FIREYE PANEL CONTROL SYS TEMS FOR AUTOMATIC OIL, GAS BURNERS. Fireye flame failure protection plus com plete automatic programming in a single integrated unit, assembled and tested by factory experts. Includes System FP-2 primary controls, short circuit protec tion, motor starters, fuel selector switches, signal lights, any needed op tional equipment such as sequence draft controls, draft and temperature indi cators. FIREYE SAFETY INTERLOCK SYS TEMS FOR SEMIAUTOMATICALLY AND MANUALLY-LIGHTED BURN ERS. Complete safeguard systems for up to four burners per boiler--oil, gas, or com bination oil-gas. Assures safe light-off and firing. Includes System FP-4 primary control in pre-wired cabinet assembly: plus all external valves, switches, and alarms. FIREYE ELECTRONIC SAFEGUARDS AND PRIMARY CONTROLS. System FP-2. Flame failure protection and programming for automatic in dustrial oil, gas, and combination oil-gas burners. System FJ-2. , Flame failure protection and programming for automatic com mercial light oil, gas, and combination light oil-gas burners. System FP-4. Flame failure protection for semiautomatically and manually- lighted oil, gas, and combination oil-gas burners. FIREYE FLAME FAILURE INDICA TION AND ALARM SYSTEMS. System FP-3. Electronically senses presence or absence of oil, gas or pul verized coal flames, and actuates a visible or audible signal. Type F18T-3. A sensitive photoelectric switch in a rugged industrial housing. Used with industrial oil burners to shut off fuel on loss of flame. fireye photoelectric smoke DENSITY INDICATOR. System FE^3. Provides low cost, easy-toinstall smoke density indication with assured accurate readings. Helps keep smoke within legal limits. Saves fuel dollars. Chart recorders also available. . 1475 ------- "4 Panel Control System for Automatic Burners Fuel Valve Safety Interloci for Semi- Auiomatically and ManuallyLighted Burners Light Source Controls and Instruments The Electric Auto-Lite Company / INSTRUMENT AND GAUGE DIVISION Jk Department HV aSa [WTWCv\\\ TOLEDO 1, OHIO ^5 NEW YORK * CHICAGO SARNIA, ONTARIO TEMPERATURE INDICATING AND RECORDING THERMOMETERS MODEL 1000 RECORDING - THERMOMETER Temperature cycles are permanently charted by this latest addition to the Auto-Lite line of temperature recorders. Has evenly calibrated, 6-in. chart; at tractive die-cast case. Various standard chart ranges from minus 40F to plus 550F. The style shown is wall mounting type, with capillary tubing for remote, eye- level reading. Also available with port able case with capillary and portable self-contained. Obtainable with cycle indicator for refrigeration. Choice of 24-hour or 7-day mechanical chart rota tion: . MODEL F-l INDICATING THERMOMETER -* Designed to facilitate systematic tem perature observation for air condition ing, refrigeration or heating applica tions. Large, easily read dial, evenly calibrated and fully compensated for temperature changes at the indicating head. Adjustable to 3 positions. Choice of temperature ranges from minus 40 F to plus 750 F. Available with elec tric alarm contact at small added cost. MODEL "G" INDICATING - THERMOMETER These thermometers have the same effi cient one-to-one ratio, solid liquid-filled movement as Model "F" with evenly calibrated scales. Capillary tubing for remote reading or rigid stem. Send for Catalog describing styles and types of Auto-Lite Thermometers. 1476 Controls and Instruments Field Control Division of H. D. Conkey & Company, Mendota, HL Manufacturers of FIELD DRAFT CONTROLS FIELD BAROMETRIC DRAFT CONTROLS FIELD "MG" DOUBLE ACTING: For commercial gas fired heating plants. Double acting gate opens inward to regu late up-drafts, and outward to relieve down drafts. Highly sensitive. Optional safety switch closes main gas valve in case of prolonged down draft, thus pro viding full protection. Available in 10 in. 12 in., 16 in., 20 in., 24 in., 28 in. and 32 in. sizes. Illustration shows up-draft view. FIELD TYPE M: For automatic heating equipment, designed to assure finer per formance, greater fuel economy, through highly accurate control of drafts. Avail able in sizes from 6 in. through 24 in. for pipe diameters of 6 in. through 25 in. Features "Rocking Chair" gate action, off-center gate mounting, sidewings, ex tended housing. Widely used in the heat ing industry. FIELD TYPE RC: Calibrated draft con trol in sizes 7 in. and 9 in. for 6 in. through 10 in. flues: Features extreme capacity, and reversible wing flap on gate for more precise adaption to either vertical, horizontal or sloping flues. Fric tion-free gate mounting, single strap at taching, easily leveled on a sloping flue. FIELD TYPE M Heavy duty commercial model for oil and coal fired equipment, in sizes 28 in. and 32 in. Features stainless steel knife edge bearing, and very heavy construction to eliminate vibration (14 gauge steel throughout, weights up to 140 lbs net). Includes all the outstanding patented type "M" features for accuracy and dependability. 1477 ! { ; I i j Controls and Instruments Fulton Sylphon Division ROBERTSHAW-FULTON CONTROLS CO. Knoxville 1, Tenn. Sales Representatives in Principal Cities Manufacturers of Sylphon Automatic Temperature Controlling Instruments and Packless Expansion Joints Series 800 ROOM THERMOSTATS Heavy duty, super sensitive wall thermo stats for accurate, direct control of elec tric heating units, air conditioning units, etc. Sensitive thermostat responds to both radiant heat and air temperature changes to J- differential under ac tual load conditions. Other features include: positive snap-action switch; mounts on standard outlet box with only two screws and without removing cover; electrically rated for both non-inductive load ratings and motor ratings; instru ment type construction; accurately cali brated dial; calibrated thermometer eliminates guesswork as to room temper atures; shock-proof plastic cover; com pact, attractive design; UL approved, and guaranteed for 18 months against defective workmanship or materials. HOT WATER SUPPLY No. 999 Temperature Regulator controls temper ature of liquids. Particularly suited for storage water heaters and for all indus trial processes requiring accurate tem perature control. Stainless steel frame for minimum heat conduction. Large size Sylphon Bellows provides added power. Self-operating. Valve sizes from in. to 4 in. Temperature ranges start at 40 F, up to 420F. Bulletin HVG-E. SPACE HEATING CONTROL No. 88S Automatic Radiator Valve-- For exposed radiation. Small, neat, at tractively finished, adjustable to room temperature desired. Simply replace ordinary radiator valves with these Syl phon Automatic Valves--no wiring, pip ing or auxiliary equipment is required. These valves answer the demand for an inexpensive means of providing accurate, dependable space temperature control in rooms, sections or throughout large buildings, new or old. Similar type valves for concealed radiation--get Bul letin HVG-E. 801 Series: Temperature Range: 64 80F. Operating Differential M 20 amps (non-inductive load) at 125-250 volts ac, % hp at 115 volts ac, lj<f> hp at 230 volts ac. 802 Series: Temperature Range: 5585F. Operating Differential: 1 20 amps (non-inductive load) at 125-250 volts ac, M hp at 115 volts ac, 1^ hp at 230 volts ac. Type 801-A3: Combination thermostat for heating-cooling use. Temperature Range: 64-80F. Operating Differential: J4 Requires only a simple connection with a manually operated summer-winter switch to provide change from heating to cooling. Sylphon No. 890 Radiator Control Valve For either exposed or concealed radia tion. Similar in appearance and action to other Sylphon Automatic Valves, but operated by an electric wall thermostat. The closing of the thermostat circuit energizes a tow voltage electric heater coil surrounding a bulb containing a vola tile liquid. This liquid expansion causes pressure on a bellows in the valve head operating the valve. This provides radi ator valve "control from a remote loca tion, permits regulation of several radia tors from a single thermostat, enables a time switch to be installed, if desired, offers effective zone control of large areas at a fraction of the cost of conven tional motor-operated valve systems. Bulletin HVG-E. 1478 Fulton Syphon Division Controls and Instruments REFRIGERATION CONTROLS No. 945-Z Regulator ranged to control any air conditioning system and to provide exactly the condi tions desired. Write for Bulletin SACS60. The No. 928-H Regulator Adaptable wherever brine is used as the refrigerant. Latest development is a "freeze-proof" valve (illustrated) on the popular Sylphon No. 945-Z Regulator. Bulletin HVG-D. PACKLESS EXPANSION JOINTS No. 110-M Sylphon Expansion Joint The Sylphon Packless Expansion Joint eliminates expensive construction, non revenue producing space. No leaks or repairs, no repacking. Use- No. 110-M for steam lines; No. 111-M for water lines. Sizes M in. to 3 in., inclusive. Bulletin HVG-65. NO. 96066 SYLPHON EXPANSION JOINT Simple, compact yet highly sensitive. Suitable for modulating control of air temperatures in ducts. Bulb is construc ted of numerous coils of copper tubing giving sensitivity to the slightest tem perature variation. Packless valve eliminates service problem and makes this regulator ideal for installation in in accessible locations. Suitable for steam pressures up to 15 lbs; other types availa ble for pressures up to 75 lbs. The Sylphon No. 889-C Regulator Used on hot water lines, a simple, com pact means for absorbing expansion of "baseboard" radiation, finned convec tors, horizontal supply lines, etc. A twoply Sylphon bellows absorbs expansion, Srevents noise, pipe strains, leakage. ompletefactoryassembledunit. Easily installed or removed. Sizes in. to 2 in., inclusive. Bulletin HVG-E. HEATING AND AIR CONDITIONING CONTROL Almost any type of heating, ventilat ing or air conditioning system can be advantageously controlled wholly or in part by Sylphon Regulators. Basic ad vantages of Sylphon Controls are: Modulating--Maintain ideal condi tions--not continually correcting too hot, too cold, too humid or too dry conditions. Compensating--Many Sylphon Regu lators offer compensating control, auto matically raising their low limit setting at a predetermined rate as outside tem peratures fall. Sensitive--Close operating tempera ture differentials. Quick response. Simple--in design. Rugged Construction--Give years of satisfactory service. . Adaptable--Any one of many combina tions of Sylphon Instruments can be ar A modulating, dual-function regulator for control of duct heating and ventilat ing systems--two independent valves in a single body. Adjustable Thermostat "A" governing Valve "D" functions to maintain room temperature from temperature of re circulated air. Adjustable Thermostat "B" acts as a low-limit ducstat control ling Valve "E" to maintain minimum discharge air temperature. Bulb "C" compensates Bulb "B" to maintain even discharge air temperature irrespective of demand. Compensated Thermostat "B" can also be furnished to raise its setting at a predetermined rate with falling fresh air temperatures if desired. Suitable for steam pressures up to 15 lbs- The Sylphon No. 889-C7 Regulator The No. 889-C7 regulator has a wall type adjustable thermostat that is placed in the room or space to be controlled. This thermostat "A" operates upper half of the regulating valve. Otherwise, same as No. 889-C regulator described above. 1479 Controls and Instruments 0 GENERAL CONTROLS MANUFACTURERS OF AUTOMATIC CONTROLS FOR HOME, INDUSTRY AND THE MILITARY GENERAL CONTROLS piCKI COHICOtl 40 FACTORY BRANCH OFFICES SERVING THE UNITED STATES AND CANADA h FIVE PUNTS. IRON MOUNTAIN, MICHIGAN GlNDAIf;<AUFORNIA SURSANK, CALIFORNIA SKOXIt, IWNOIS GUtWH, CANADA (A) Type T-tO (B) Type K-10 (>) Type BSSQ (A) THERMOSTATS Compact, snap action, Line or Voltage Thermostats. Functional beauty for ac curate, remote control of desired temper ature. Extends only % in. from wall. Streamlined stainless cover, sensitive to slightest temperature change, ivory plastic base,. (B) K-10 MAGNETIC LEVER VALVES Provides six times more power than ordinary solenoid valves. Controls air, gas, water, light, heavy oils, steam. Positive opening, complete shutoff, packless, hum-free. Available for any voltage, a.c. or d.c., in sizes up to 1J4 in. I.P.S., port sizes up to % in. <D) SLOW OPENING GAS VALVES New combustion control afforded: by these diaphragm-controlled gas .valves. Governor model regulates fuel supply to burner in direct ratio to steam pressure, eliminating hunting aspect. Available 1 in. to 6 in. I.P.S. (E) MAGNETIC GAS VALVES Versatile, two-wire, straight magnetic current-failure valve. Packless. Insures tight shutoff indefinitely. Humless. Size range jhj in. to 6 in. I.P.S. Operating pressures up to 10 lb. Voltages and. fre quencies a.c. or d.c. Quiet,' positive, trouble-free. Available in explosionproof housing. (C) BX-69 GAS ACTUATED PACKAGE (F) Type V-UO SETS (F) MANUAL RESET VALVES No outside current required. Operates on all types of gases. Safe, quiet, de pendable. For all gas-heating appli ances. Set consists of a PG-9 700 milli volt pilot generator, a B-60 gas control valve, a T-70 snap action thermostat, thermostatic cable and vent tubing. Everything needed in convenient pack Equipped with manually-reset electromagnetically-held valve operator. Cur rent flowing to operator permits manual opening by turning valve wheel at side. Current failure releases operator allow ing valve to close. Trip-free mechanism won't open under unsafe conditions. Closed, valve must be reopened man age for remote gas control. ually. ' 1480 General Controls Controls and Instruments (G) HYDROMOTOR VALVES Simplify valve control installations. Two-wire, current failure, electric-hy draulic operation. Ample motor-driven power, slow opening and closing move ment. G-l Series, designed for low pres sure steam,' hot and chilled water circu lating systems. G-2 and G-3 Series for high pressure applications. (H) REFRIGERANT CONTROLS Magnetic Stop ValvesPiloted, two-wire current failure, high pressure, packless. Handle large capacities with minimum pressure drop and loss. Tight shutoff. Operates on air, steam, water, and re frigerants. (I)*"hf-g" MAGNETIC VALVES Designed for positive operation on air craft, trucks, tractors, tanks, graders, ships, and other moving equipment. Handle all fluids, vapors and gases on anything that rolls, floats or flies at pres sures up to 3000 lbs or more. Packless, two-wire, current-failure type, available normally open, normally closed for inter mittent or continuous duty. (K) A-100 THERMOPILOT RELAY Gas safety control--thermocouple in pilot flame closes control circuit auto matically through relay to hold gas valve open. Gas valve shuts off when pilot is extinguished, prevents gas escape. Thermocouple adapts to pilot burners. Pilot generator models for long couple lengths or operating multiple controls. (L) THERMAL EXPANSION VALVES Type V-200 with new selective capacity cartridge provides instant sizing adjust ment. Only one valve required for full capacity range in each body size at all back pressure or suction temperature ranges. For Freon, Methyl Chloride or Sulphur Dioxide. (M) THERMOPILOT VALVE AND GAS COCK SAFETY VALVE Manually reset, electromagnetically holds valve open with current generated by thermocouple, subject to heat of pilot flame. Automatically shuts off gas if pilot goes out. Type MR-5 combines manual gas cock with thermopilot safety valve. Available in jhj in. to 1}^ in. I.P.S. (AT) SA dt SY Strainers (N) STRAINERS (TO Type A-I00 (J) Type T2S-10O Relay (J) RELAYS AND TRANSFORMERS Type RS-100 handles single phase motor loads up to 1 hp or heating loads up to 1.1 kw. Combines double break relay and integral transformer. Normally open; large double-break contacts. Twowire control circuit; maximum holding current 0.4 amps. Furnished with in. conduit connections and low voltage outlet, a.c. only. * Trade mark--"hi-g" indicates positive ability to or motion or acceleration. Protects automatic regulators or valves from pipe scale, other foreign matter. Assures proper seating, closing of valve. Prevents leakage. Convenient cleaning or blowoff without breaking line. Monel screen. OTHER GENERAL CONTROLS ITEMS IMMERSION THERMOSTATS COMBINATION FAN AND LIMIT CONTROLS . STEAM PRESSURE, VAPOR AND VACUUM CONTROLS # TEMPERATURE CONTROLS * LOW WATER CUTOFFS iction in any position, regardless of vibration, change 1481 Controls and Instruments Henry Valve Company MELROSE PARK. ILLINOIS (A Chicago Suburb) HENRY PRODUCTS FOR REFRIGERATION, AIR CONDITIONING, AND IN DUSTRIAL APPLICATIONS: CONTROL DEVICES, VALVES, STRAINERS DRIERS. FITTINGS, AND ACCESSORIES. STRAIGHT-THRU TYPE--Large capa city--Brass Construction. 34" thru 1". ANGLE TYPE--for ammonia, 2". thru DRIERS Filled with PA400 silica gel. Balanced-Action Diaphragm Packless Valves STANDARD TYPE--Valves cannot stick shut regardless of pressure above or be low Valve seat. Forged brass body and bonnet, ports-in-line and non-direc- tional. Back seat and ball check permit diaphragm inspection and replacement under pressure. Sizes: J4" thru %" Flare; 34" thru O.D.S.; 34" thru 34" F.P.T. Line, angle and branch types. BLUE BANTAM TYPE--Two-way line shut off valves, flare or solder connec tions. Contain same field proven features as STANDARD line except that dia phragms cannot be inspected or replaced while valves are under pressure. Stock sizes 34" thru 54" flare and solder. TYPE 705--Brass shell, forged brass end caps with integral fittings--silver brazed joints. Dehydrant capacity 10 to 32 cu in. Sizes, )4" thru 34" flare. TYPES 77, 78 and 79 cartridge driers with side outlet, safety disc, cartridge retaining spring and distortion-proof access flange. Dehydrant capacity 12 to 500 cu in. Sizes 14" thru 2)4" O-D. solder. Can be converted to strainer by use of strainer screen cartridges. STRAINERS WING CAP PACKED VALVES--Bronze with solder connections, sizes 34" thru 434" O.D. Semi-steel with F.P.T. connec tions in valve body, sizes )4" thru 2)4". Semi-steel flanged type, with separate brass O.D.S. adapters, sizes 1 % thru 5)4"; with separate steel butt weld adapters, sizes 1)4" thru 5"; with one piece F.P.T. flanges, or with one piece slip-on weld flanges, sizes 1)4" thru 6". TYPES 891 and 892. Brass shell, forged brass end caps. Screen area 11 and 25.5 sq in. respectively. Sizes )4" thru %" flare and 54" and 34" O.D. solder. RELIEF VALVES Straight-Through Type and Ferrous Type Most sizes meet ASME Standards--Na tional Board Certification. TYPE 895--Brass plated steel "Y" strainer, welded construction, forged brass end caps. Distortion-proof access flange. Screen area 12 to 150 sq in. Sizes 54" thru 4M" O.D.S.; and 2)4" thru 4" butt weld. Stocked by Wholesalere. Ask for Catalogs 1482 Controls and Instruments Hubbell Corporation . Mundelein, Illinois C. & S. EQUIPMENT CO, INC. 2103 San Pedro St, Los Angeles 11, Calif. ' MASON EMANUELS CO. 91 Dearborn St, Seattle 4, Wash. Designers and Manufacturers of Automatic Control Valves for All Refrigerants Type SAS, SPS Type SA-6, SPS Type SA-7, SF-7 Back Pressure Regulating Valves are of the conventional type used to maintain a constant evaporator pressure. Combination Back Pressure Regulator and Stop Valves. This regulator is of the conventional type used to maintain a constant evaporator pressure and the addition of a small solenoid pilot valve built into the head, makes it a suction stop valve. Type DSA-9, DSP-9 1. The Type "T" suction stop valve is used where automatic suction line con trol is required. It is operated by high pressure gas and its construction makes a tight closing valve and its dependabil ity surpasses the conventional magnetic stop valve. 2. The DSA-9-DSF-9 is a dual regulator which will control evaporators with two load conditions requiring different refrigerant temperatures. The dia phragms in the dual head may be set for any two evaporator pressures and will automatically change from one to the other by the opening or closing of the solenoid pilot valve. 3. The SAC-6 and SFC-6 valves are of the compensating type and are used where a constant temperature is desired in the medium being cooled. These valves will increase or decrease the evaporator pres sure to compensate for the increase or decrease of the cooling load. Operated with air, electricity, or thermal type. Solenoid Valves from % in. to 2 in. inclusive for liquids add gases with com position seat discs readily renewable, coils for any electrical characteristics, built-in lifting stem standard, with either screwed, welding flanges or copper tube connections. HUBBELL-ize your plant v Strainers in all sizes for liquids and gas with very large screen areas and ar ranged to bolt directly to valve or with screwed, welding flange or copper tube connections for installation wherever strainer is necessary, h "Service Free" controls. Johnson Service Company AUTOMATIC TEMPERATURE AND AIR CONDITIONING CONTROL General office md Factory 507 E. Michigan St. Milwaukee 1, Wis. Direct Branch Offices in Principal Cities Johnson Temperature Regulating Company op Canada, Ltd., 120BebmondseyRd.,Toronto 16,Ont. MANUFACTURERS, ENGINEERS and CONTRACTORS. A complete line of automatic temperature and humidity controls for heating, cooling, ventilat ing, air conditioning, industrial process ing, military installations and special temperature and humidity control appli cations. SPACE CONTROL--Automatic room temperature and humidity control for convectors, radiators, radiant heating, unit ventilators, unit heaters, and heat ing and cooling air delivery equipment. INDUSTRIAL PROCESSING--Auto matic temperature and humidity con trol for every requirement in manu facturing and industrial processing. Thermostats, valves, dampers for tanks, dryers, vats, kettles, curing rooms, coolers, kilns, and other special equip ment in textile, rubber, paper, petro leum, meat, dairy, baking, sugar, brew ing, distilling, tanning, candy, foods, pharmaceutical, and other industries. SERVICE ORGANIZATION--Johnson sales engineers, and trained installation experts at all branches in United States and Canada.. No agents, jobbers, or part-time representative! All Johnson salaried personnel for exclusive service of Johnson Service Company customers. JOHNSON LITERATURE: Available at your nearest JOHNSON branch office or write to address above. . JOHNSON THERMOSTATS Room Thermostats--single and dual temperature (Day-Night, Heating and Cooling). Proportional or two-position action. Maintain temperatures within one degree above or below set ting. Wide selection of adjusting features, guards, and mount ing. Furnished with or without thermometers. Insertion and Immersion Thermostats--Liquid-filled tempera ture measuring elements. Stem type for direct measurement. Remote bulb types for applications requiring location of thermostat at a distance from the point of temperature meas urement. Various bulb styles available. Standard, capillary length is 8 ft. Lengths of 15, 25, 35 and 50 ft available on spe cial order. Submaster Thermostats--The 6et point of these Johnson con trollers is changed from a remote location by the action of another (master) controller. Available with liquid-filled stem and remote bulb measuring elements. Johnson "Duo-Stats," weather compensated primary con trollers, control heating system temperatures in accordance with the outdoor temperature. Duo-Stats are available for any heating system, all types of buildings, and furnished in pneu matic, electric or electronic models. Series T-400 Room Thermostat TSOI Liquid-filled Immersion Thermo stat PRESSURE CONTROLLERS Pressure Regulators with ranges of 30 inches of water to 300 psi. Static pressure regula tors measure variations in pressure from .009 inches to 3 inches of water. Used also as differential regulators measuring difference in pressure between two chambers. Pressure switches and governors also available. T-901 Liquid-filled Re mote Bulb Submaster Thermostat JOHNSON HUMIDITY CONTROL Humidistats--Room and insertion types with humidity meas uring elements of wood or animal membrane, the most sensitive of which controls within 1 per cent at relative humidities as high as 95 per cent, at temperatures of 200 F. Submaster models also available which are adjustable from a remote point by another controller (master) or may be manually readjusted from a remote point by means of a Johnson Gradual Switch. Humidifiers--Steam grid (perforated pipe supplied with low pressure steam) or pan type with copper evaporating pan, brass or copper heating coils and float control. 1484 ?r;. (.ns fi \ U -'-j i'r Johnson Service Company Controls and Instruments SPECIAL CONTROLLERS Aspirating Cabinets--Several models with many combinations of controlling and auxiliary devices required to provide control of temperature and humidity. Cabinets equipped with blowers for positive air circulation and air gages for checking function of controllers at all times. Pneumatic Step Controllers--for capacity control of recipro cating refrigeration equipment or any application where se quence of pressure switches is used. Record-O-Stat--Combination capillary temperature con troller and recorder. Available in single pen, two-pen, and sub master models. Indicating controllers and recorder-controllers also available. Liquid Level Regulators--(Float Type) control within ex tremely close limits. Mounted through wall of containing vessel by stem with 1 inch pipe thread. Floats of copper, stainless steel or special alloys. Thermometers--Insertion and immersion types for air and liquids. Stem and remote bulb temperature measuring models with vapor tension or liquid filled elements. Variety of styles, mountings and finishes. 18 Point Model Pneu matic Step Controller ' - JOHNSON VALVES Johnson Diaphragm Valves--Simple, rugged. Diaphragms of special molded rubber, resistant to age and oxidation, operate valve stems against spring pressure. Available also with "Syl phon" seamless metal bellows. In standard sizes and patterns including compact valves for convectors and unit conditioners. Normally open or normally closed. Three-way mixing and by pass valves, for water, brine and other liquids. Johnson "Streamline" Diaphragm Valves--With modulating discs and special internal construction. Smooth proportional control. Where maximum power is required for repositioning at slightest demand of controlling instruments, the larger molded rubber diaphragm valves are fitted with pilot posi tioners. V-10S 3-wag Mixing Valve- Rvbber Diaphragm V-U3 "Sylphon" Convector Valve JOHNSON DAMPERS AND SWITCHES Standard Johnson Dampers--Galvanized 16-gauge steel blades in flat steel frames with adequate bracing to form rigid assem bly. Black lacquer or special corrosion-resisting finishes. Angle iron frames optional. Special Dampers--Galvanized iron frames and monel metal, aluminum, copper or rust-resisting steel blades on special order. Frames of same material as blades, if desired. Brass pins in steel bearings or ball bearings. Johnson Damper Operators--Similar in operating principle to valves. Specially molded rubber diaphragm or seamless metal bellows operates damper through suitable linkage. Johnson "piston" damper operators afford long travel at full power. With or without pilot mechanism, as described for "Valves." Johnson Pneumatic Switches--For direct operation of dampers and to switch controllers in and out of service from remote locations. Standard switchboard panels are Masonite. Ebony, asbestos, steel, polished oak and genuine or imitation marble panels on special order. Special switchboards including all types of control equipment available on special order. D-ttS Proportioning Louver Damper^. D-851 Piston Damper Operator 1485 Controls and Instruments Illinois Testing Laboratories, Inc. Room 51G, 420 N. La Salle St., Chicago 10, 111. Precision Instruments for Every Industry The direct-reading ALNOR VELOMETER sfc M TYPB4-F Standard minimum set for heating and air conditioning air velocity measurement*. The Alnor Velometer is an instantane ous, direct-reading air velocity meter designed for convenient, rapid deter mination of air velocities in air condi tioning, heating and ventilating, and exhaust systems. It gives instantaneous direct readings in feet per minute, with out timing, calculations, or reference to tables or charts. Accurate information on performance of equipment, duct sys tems, etc., can be obtained with a few moments inspection with the VELOM ETER; It can be effectively used to locate drafts and leaks around windows and doors, or in duct systems. Alnor Velometer, Jr. A miniature, di rect reading Velometer--4 in. high, 3 in. wide, 1-i in. deep. Weight, 8 oz. Accu rate, strong. Available in single and double scale ranges: 0-200 to 0-2500 fpm. Bulletin 725. The Alnor Velometer is built in several standard ranges from 20 fpm to 6000 fpm, and up to 3 in. static or total pressure. Special ranges available as low as 10 fpm and up to 25,000 fpm velocity and 20 in. pressure. Alnor Thermo-Anemometer. For accu rate measurement of low air velocity. Compact, direct-reading, battery oper ated, self-contained, portable. Scale 6 in. Meter ranges: 0-600 fpm and double range 0-300/100-2000 fpm. Accurate readings as low as 5 fpm. Temporary Bulletin 913-A. 1486 m %. 1| ' Jts'k ?jr V* :.J* ' &rv* it r-o: i?L* ? & Controls and Instruments Leslie Co. 266 Grant Avenue Lyndhurst, New Jersey REGULATORS and CONTROLLERS for the Regulation and Control of Pressure, Temperature, Flow and Liquid Level. LESLIE COAST-TO-COAST SERVICE In all principal industrial centers LESLIE factory-trained engineers are available to help with any control prob lem involving steam, liquid, air or gas. Look for LESLIE REGULATORS under "Valves" or "Regulators" in your classi fied telephone directory. INTERCHANGEABILITY -- Internal parts of LESLIE Regulators are dimen -----signally interchangeable. Maximum in terchangeability in all sizes and classes. Temperature Regulator Clast T LESLIE EXCLUSIVE FEATURES--at no extra cost! Stellited Seat Rings Hardened Stainless Steel Main Valves, 500 Brinell Corrosion Resistant Springs Hardened Stainless Steel Cylinder Lin ers, 500 Brinell. Supplied as standard equipment. Reducing Valve Class L-S Pump Pressure Regulator Class PR LESLIE PRESSURE REDUCING VALVES, PUMP PRESSURE REGU LATORS and TEMPERATURE REG ULATORS Self-contained, spring loaded, internal pilot piston or diaphragm operated with stellited seat rings, hardened stainless steel trim, bronze, iron, or steel construc tion. All LESLIE Regulators feature: Accuracy of regulation comparable to . instrument control Single-seated construction for positive dead-end shutoff Valve acts fast for sudden load changes Maximum resistance to corrosion and wear Maximum spring range--from mini mum to maximum controlled pres Floatless Lead Control for Boilers, Tanks, Evaporators, Heaters, Standpipes, etc. sure range without change of spring or diaphragm Diaphragm Control Valve Class D-t SEND FOR BULLETIN 552 DESCRIBING THE LINE 1487 Controls and Instruments Maxitroi Company 12200 Beech Road Detroit 39, Michigan LOW PRESSURE GAS REGULATORS Pacific Coast Distributor; PACIFIC SCIENTIFIC CO. San Francisco, Los Angeles, Seattle, Portland Maxitroi gas regulators feature the patented "Straight-Thru- Flow" design principle. This construction sharply reduces pressure loss commonly encountered in conventional type gas pressure regulators. The new feature permits greater flexibility in design of manifolds for domestic; equipment, and frequently allows a reduction in pipe size of gas mani folds. Capacity charts at greater differential .pressures for industrial use at inlet pressures up to S psi available on re quest. - CAPACITY RATING (A. G. A. Listed) Model No. RV10. RV40 RV41 RV41 RV42 RV50 RV60 RV61 RV51 RV60 RV60 RV80 RV80 RV90 RV90 RV110 RV110 Pipe Size Cu Ft/ Hr at 0.3 Pressure Drop 0.6 Sp. Gr. Gas Wi 15 )6 150 H 118 H 130 Vt 176 H 270 H 270 H 450 11 460 676 \M 705 1W 1.250 Gi 1,260 2 2.030 2W 2.030 m 4,200 3 4.000 Btu/Hr Gases 800 Btu/ Cu Ft or More (Natural Gas) 11.000 111.000 87,300 06,000 130,000 200,000 200,000 333.000 340,400 500,200 521,700 925,000 932,400 1,502,000 1,502,000 3.108,000 3,626.000 Btu/Hr Gases Less Than 800 Btu/ Cu Ft (Mid. Gas) Model No. 7.450 75,000 59,000 65,000 88,000 135,000 135,000 225,000 230,000 338,000 352,500 625,000 630,000 1,015.000 1,015.000 2,100,000 2.450,000 RV10 RV40 RV41 RV41 RV42 RV50 RV5Q RV51 RV51 RV60 RV60 RV80 RV80 RV90 RV90 RV110 RV110 1488 DIMENSIONS A IH m 2>Ho 2H 3 3 3% 3H 4H 4H 6 6 7)6 7)6 9 9 B 1*M 2H 2'M* 2>M. 3H 3'H i'Ht 494. 4*4. 5h 7 7 9)6 9)6 1294 1294 c 294 494 3*94* 494. 594 594 6Me 694. 7)6 7a 8Me 8Me 9'94 S'M, liH 14H D 94 1H m 1H 194 2He 2Ms 2M<J 2Ms 294 294 2H 2H 3H ZU ' Ship ping Weight Each 3 os H* M* H* H* 1* 10 154* 1H* 2)60 2)60 50 50 8H0 90 200 200 Controls and Instruments The Mercoid Corporation Main Office and Factory, 4201 Belmont Avenue. Chicago 41, Illinois New York Office, 205 East 42nd St. . . Philadelphia Office, 3137 N. Broad St. AUTOMATIC CONTROLS FOR HEATING, AIR CONDITIONING, REFRIGERATION AND VARIOUS INDUSTRIAL APPLICATIONS 100% MERCURY SWITCH EQUIPPED CONTROLS STEAM PRESSURE CONTROLS Type DA-31 Circuit opens on pressure rise. For application where pressures change slowly. Equipped with outside double adjustments for setting cut-in or cut-out points. Elec. Cap--A-C orD-C10 Amp. 115V;5 Amp.230V.M in. I.P.S. connection. Ranges 0-14 lbs, 0-30 in. vac., 10 in. vac.--12 lbs, 0-20 lbs, 0-35 lbs, 0-60 lbs, 0-100 lbs, higher ranges available. Type DA-21 Circuit opens on pressure rise. For applications where pressures fluctuate rapidly. Similar,to Type DA-31. Electrical Capacity same as DA-31 above. Ranges available to 2,500 lbs. HOT WATER TEMPERATURE CONTROLS Type 437 Circuit opens on temperature rise. Bimetal-operated (back angle immersion well type) used as a high limit for hot water boilers. Equipped with outside double adjustment for setting cut-in or cut-out operating points. Electrical Capacity--A-C or D-C 10 Amp. 115V; 5 Amp. 230V. Connection % in. I.P.S. Ranges 80-240 F and 40-200 F. Type DA-36 (straight stem) Circuit opens on temperature rise. For immersion applications where bulb is directly installed into boiler water. Equipped with outside double adjustments. Electrical Capacity same as 437 above. Connection % in. I.P.S. Immersion bulb 3 in. long. Ranges 100-200 F and 135-235 F. WARM AIR TEMPERATURE CONTROLS Type M-41 Limit Control. Equipped with outside adjustments for setting cut-in and cut-out operating points. Range 70-310 F. Type M-43 Fan or Blower Control has outside adjustments to gether with summer switch used for ventilating purposes dur ing summer. Range 50-300 F. Electrical Capacity all types A-C or D-C 115V. 10 Amp; 230V, 5 Amp. ROOM THERMOSTATS Type H, opens circuit on temperature rise (low voltage). Regulates heating equipment from True Room Temperature without the aid of artificial stimulation. The Mercoia switch is unaffected by dust, dirt or lint. The cover has a jewel hard alumilite finish that will last a lifetime. Electrical Capacity 5fo Amp, at 24V. or less. Ranges 55-85 F and 65-95 F. Type R same as above except circuit closes on temperature rise. OIL BURNER PRIMARY CONTROLS Type JMI (intermittent ignition) stack mounted safety igni tion control provides complete protection against flame or ignition failure--low line or power failure protection. Type JM (constant ignition) same as above except that no ignition switch is employed. Electrical Capacity A-C 10 Amp. 115V; 5 Amp, 230V. Write for Catalog No. 800ASHV. 1489 Controls and Instruments MINNEAPOLIS-HONEY WELL REGULATOR CO. 2644 Fourth Ave. S- Minneapolis 8, Minn. Cable Address: Mlnnreg, Minneapolis HONEYWELL CONTROLS for Heating, Ventilating, and Air Conditioning BROWN INSTRUMENTS for Indicating, Recording, and Controlling APPLIANCE CONTROLS for Gas, Water, and Space Heaters MICRO SWITCHES for all applications VALVES for Industrial applications Factories: Minneapolis, Minn., Boston, Mass., Denver, Colo., Newton Highlands, Mass., Phila delphia, Pa., Wabash, Ind., Freeport, Iii., Chicago, III., Gardena, Calif., Toronto, Canada, . . Newhoose, Scotland, Amsterdam, Netherlands BRANCH OFFICES ARE LOCATED IN THE FOLLOWING CITIES; Akron, Ohio Albany, N. Y. Albuquerque, N. M. Amarillo, Tex. Anchorage, Alaska Atlanta, Ga. Bakersfield, Calif. Baltimore, Md. Billings, Mont. Binghamton, N. Y. Birmingham, Ala. Bismarck, N. D. Boise, Ida. Boston, Mass. Buffalo, N. Y. Cedar Rapids, Iowa Charleston, W. Va. Charlotte, N. C. Chattanooga, Tenn. * Chicago, III. Cincinnati, Ohio Hammond, Ind. Harrisburg, Pa. Cleveland, Ohio Hartford, Conn. Columbia, S. C. Houston,-Tex. Columbus, Ohio Indianapolis, Ind. Corpus Christi, Tex. Jackbon, Miss. Jacksonville, Fla. Dallas, Tex. Kansas City, Mo. Davenport, Iowa Knoxville, Tenn. Dayton, Ohio Denveb, Colo. Lansing, Mich. Little Rock, Ark. Des Moines, Iowa Los Angeles, Detroit, Mich. Duluth, Minn. Calif. Louisville, Ky. Eau Claire, Wis. El Paso, Tex. Eugene, Ore. Evansville, Ind. Fort Wayne., Ind. Lubbock, Tex. Madison, Wis. Memphis, Tenn. Menasha, Wis. Miami, Fla. Fort Worth, Tex. Milwaukee, Wis. Fresno, Calif. . Minneapolis, Grand Rapids, Minn. Mich. Mobile, Ala. Gbeen8bobo, N. C. Moorhead, Minn. Greenville, S. C.- Nashville, Tenn. New Haven,Conn. San Antonio, Tex. New Orleans, La. San Diego, Caup. New York, N. Y. San Francisco, Norfolk, Va. Calif. Odessa, Tex. Scranton, Pa. Oklahoma City, Seattle, Wash. Okla. Shreveport, La. Omaha, Nebb. Sioux Falls, S. D. Peoria, III. South Bend, Ind. Philadelphia., Pa. Spokane, Wash. Phoenix, Ariz. ~Pittsburgh, "Pa. Portland, Me. Springfield, Mass.' Sybacube, N. Y. Portland, Ore. _Tacoma_, Wash. Providence, R. I. Tampa, Fla. Richland, Wash. Toledo, Ohio Richmond, Va. Tulsa, Okla.* Roanoke, Va. Union, N. J. Rochester, N. Y. Washington, D. C. Wichita, Kans. Calif. Wilmington, _SS_ta_.g__Li_no_a_u_w_is,_,_M_M_i_co_h. . ,, Worcester, Mass. Salt Lake City, Youngstown. Utah Ohio ' In C__a_n__a__da:. Calgary, Edmonton, Halifax, Hamilton, London, Montreal, Ottawa, Quebec City, St. John, Saskatoon, Sudbury*. Toronto, Vancouver, Windsor, Winnipeg In Puerto Rico: Santubce San Juan In Cuba: Havana In Mexico: Monterey Mexico City ; ' Branch Offices and Distributors in More than 40 Foreign Countries A COMPLETE LINE OF MATCHED CONTROLS TO FACILITATE THE EARLY DESIGN OF EVERY CONTROL SYSTEM Minneapolis-Honeywell manufactures a complete line of automatic controls for heating, ventilating and air conditioning. They are used singly or in combination in any type of control system. Therefore, at the time the building is designed you can specify Honeywell for all controls. You can be sure all the controls you need will be available from one manufacturer. FOR ALL TYPES OF BUILDINGS Honeywell control systems may be adapted to your own.in dividual plans to give custom-tailored performance in such various structures, as apartments, hospitals, hotels, schools, motels and commercial, industrial and residential buildings. And, there are Honeywell controls for all three principal types of control systems--electric, electronic and pneumatic. Motorized Valve Assembly FOR ELECTRIC CONTROL SYSTEMS Honeywell offers a complete line of such precision-tested equipment as thermostats, humidity controls, temperature controls, pressure controls, valves, relays, motors and ac cessories, all of which may be interlocked and co-ordinated to obtain a high degree of operating economy and efficiency in every heating, ventilating or air conditioning system. 1490 Minneapolis-Honeywell Regulator Co. Controls and Instruments FOR ELECTRONIC CONTROL SYSTEMS The flexibility of electronic controls makes them adaptable to control applications from the simplest to the most complex. From small buildings where completely automatic control of heating, ventilating and air conditioning requires only one thermostat, to large buildings where the entire control system can be supervised at one control-supervision center. All elec tronic thermostats, from the round room model to the 27 foot duct model, are co-ordinated at a convenient central panel where complex sequences caii be set up; adjusted, and inspected in minimum time. Pneumatic Round Thermostat FOR PNEUMATIC CONTROL SYSTEMS Honeywell offers a complete line of pneumatic controls for ap plications from simple domestic temperature regulation to precision control of industrial processes. New Pneumatic Round thermostats provide faster response and more accurate control plus a "decorator" cover which can be painted to match surroundings. Honeywell pneumatic operators have a positive positioning feature which provides full power for even a relatively small adjustment. FOR COMBINATION SYSTEMS Honeywell combination systems make it possible for you to take advantage of the most salient features of electric, elec tronic and pneumatic controls. These systems also allow you maximum flexibility, low-cost installation and permanent dependable control results. INSTRUMENTATION , Pneumatic Radiator Valve Honeywell indicating and recording instruments provide quality control of air conditioning systems. Used to measure temperature, humidity, pressure, or flow, they offer many advantages. These remote reading instruments also facilitate central panel supervision of control systems. - ` - Recording Thermometer AT YOUR SERVICE There is a Honeywell sales and service office near you. This office maintains a staff of experienced control engineers who are highly qualified to give you advice on a broad range of applications and to install and service all types of control equipment. Honeywell engineers are equally well prepared to assist you in the writing of specifications and to furnish control layouts and cost estimates without charge. WRITE FOR FREE HONEYWELL LITERATURE . Listed below are but a few of the many pieces of literature Honeywell has prepared to help you select controls and control systems for your own specific requirements. In addition, instruction sheets on design systems and reference manuals for both electric and pneumatic controls are available to you. You may obtain literature and answers to your problems by contacting your nearest Honeywell office or writing to the Merchandising Division, Minneapolis-Honeywell Regulator Co., Minneapolis Oj Juinncsotfl, Handbook of Individual Apartment Temperature Control Heating and Air Conditioning Controls for the Modern Hospital Honeywell Control Systems for the Modern School Controlling the Thermal Environment 1. Honeywell Dampers and Shutters' Instruments Applied to Commercial Air Handling Systems ;i Automatic Controls for the Marine' In dustry t Electronic Control of Heating and Air Conditioning Honeywell Pneumatic Round 1491 Controls and Instruments Milwaukee Gas Specialty Company 730 North Jackson St., Milwaukee 2, Wisconsin SERIES EA SOLENOID VALVE Internal parts in contact with gas are aluminum or stainless steel to prevent corrosion; aluminum bodies. Straight through models in Yi in. and % in. pipe sizes with or without pilot tap pings and pressure tapping. Voltage types: 20v, 60 c, a-c; 115 v,60c, a-c; 230 v, 60 c, a-c; and 440 v, 60 c, a-c. Low voltage transformers in three-terminal and two-terminal types, DAI and DA2, respectively. ACTROL VALVE . Automatic main gas control valve. Maximum force exerted at beginning of stroke. Valve has built-in, current limiting trans former for 24-volt control circuits. Straight through body tapped with % in., 1 in., or l}i in. F.P.T. inlet and outlet. Valve can be mounted in a 360 deg circle around horizontal centerline of body. Other models with manual set, safety switch, or Baso valve. . BASOtD VALVES Type AK Baeoid Valve Basoid valves Series AE, AH, and AK are 1 in., % in., and Yi in. sizes, respectively. They combine solenoid valve for automatic main gas control and Baso automatic safety pilot . in one aluminum body. One or two pilot tappings optional. Current types: 20 v, 60 c, a-c; 115 v, 60 c, a-c; 230 v, 60 c, a-c; and 440 v, 60 c, a-c. Low voltage transformers in three-terminal and two terminal types, DAI and DA2, respectively. Switches No. 860 and 861 are wired in series with other controls. Opens circuit to main valve in case of pilot failure. Circuit closes automatically when pilot is relighted. MODEL No. 860 is a twowire switch and No. 861 is a three-wire switch. Electrical Ratine: 8 Amp at US v, a-c. I Amp at SS0 v, a-c. H kp 1(5/250 v, a.c. 860 Sttrilch ' ANNULAIR PILOT BURNERS are available in a variety of tips and dual orifice inlet fittings for all kinds of fuel gas and pilot line connections. They are made in four types, "B" for low consumption appliances, "C" for medium consumption, and "D" and "F" for larger capacity appliances. Thermocouple leads of the 88D and 58D types are available in standard lengths from.12 in. to 72 in. and in special, lengths to 240 in. Write for complete catalog SV-300-3. 1492 Controls and Instruments Moeller Instrument Company 132nd St. and 89th Ave., Richmond Hill 18, New York Representatives in Principal Cities INSTRUMENTS FOR HEATING AND VENTILATING MOELLER INDUSTRIAL THERMOM ETERS made in all forms, in scale ranges from minus 120 to plus 1125 F or its equivalent in centigrade. Available in 5 in., 7 in., 9 in. and 12 in. scale sizes. RECORDING THERMOMETERS, Mer cury Actuated, made in the round or rectangular cases. Charts 10 in. or 12 in., 1 hr, 12 hr, 24 hr or 7 day. Ranges from minus 40 to plus 1000 F or its equivalent in centigrade. TERS, Mercury Actuated, made in 41 in., 6 in. and 8J in. sizes with flexible extension tubing. Scale ranges from minus 40 to plus 1000 F or its equivalent in centigrade. MOELLER BI-METAL THERMOM ETERS are actuated by a powerful, specially processed bi-metal helix. Made in 3 in. and 5 in. diameter cases. Scale ranges from minus 150 to 1000 F. or its equivalent in Centigrade. THERMOMETKRTESTWELLsjTHER^ MOCOUPLE PROTECTING TUBES and WELLS, made up in all sizes and alloys. RECORDING PSYCHROMETERS, Mer cury Actuated. Round and Rectangu lar Case, 12 hr, 24 hr or 7 day charts, self contained or remote reading, with or without motor driven fan. ENGRAVED STEM andi PORCELAIN and PAPER SCALE THERMOMETERS made in ranges from minus 150 to plus 1125 F or its equivalent in centigrade. COMBINED with THERMOMETER. Made in all scales. Standard and com mercial grades. Send for catalogs and literature on INDUSTRIAL LABORATORY and RECORDING THERMOMETERS THER MOSTATS HYGROMETERS HYDROMETERS PSYCHROMETERS and MA RINE SPECIALTIES 1493 m Controls and Instruments Penn Controls, Inc. Main Office--Goshen, Indiana; In Canada--Penn Controls, Limited , Offices and Representatives Albuquerque; Atlanta; Berkeley; Chicago; Cleveland; Columbus; Dallas; Datton; Denver; Lob Angeles; Minneapolis; Milwaukee; Moline; Newton, Mass.; New York (North Bergen, N. J.); Philadelphia; Ptitbbubgh; Rochester; Salt Lake City; St. Louib; Seattle; Export--13 E. 40th St., New York 16, N. Y. . ! Wholesalers o> All Principal Cities Automatic Controls for Heating, Refrigeration, Air Conditioning, Engines, Pumps, Air Compressors and Gas Appliances Controls and Instruments &QiMer Princeton, Indiana Relays: All types--All sizes--For all applications Albany, N. Y. Atlanta, Ga. Boston, Mass. Buffalo, N. Y. Camden, N. J. Engineering Offices in Canaan, Conn. Cedar Rapids, Ia. Chicago, III. Cleveland, Ohio Dallas, Tex. Dayton, Ohio Denver, Colo. Detroit, Mich. Indianapolis, Ind. Kansas City, Mo. Memphis 4, Tenn. Milwaukee. Wis. Minneapolis, Minn. Montreal, P.Q., Can. New Orleans, La. New York, N. Y. Los Angeles, Calif. Philadelphia, Pa. San Francisco, Calif. St. Louis, Mo. Seattle, Wash. Syracuse, N. Y. Tampa, Fla Toronto, Ont., Can. Tuira, Okla. North Vancouver, Can. Washington, D. C. Wilmington, N. C. 500 Franchised Electronic Parts Distributors throughout the United States and Canada HEATING CONTROLS COOLING CONTROLS A wide selection of controls is available for automatic heating service on steam, vapor, hot water, or warm air systems . . . gas, oil or coaf-fired. Typical con trols in Penn's complete line are: Low and Line Voltage Room Thermostats-- Stoker Timers -- Oil Burner Stack Switches--Magnetic and Motorized Gas Valves--Hot Water and Warm Air Tem perature Controls (including a complete line of Liquid Expansion Fan and Limit Controls)--Vapor and Steam Pressure Controls -- Relays and Relay-Trans formers--Humidistats--Day-Nite TernClocks--Pilot Burners and Pilot Gen erators -- Thermopilot Relays -- Low Pressure Gas Regulators -- Damper Motor Controls--and Solenoid Valves. A complete line of automatic commercial refrigeration controls ... in a wide choice of pressure and temperature models to fit every need. Series 270 single pole, standard duty or two pole, heavy duty controls feature direct reading, calibrated scales. Other controls in the refrigeration line include: Cooling Room Thermostats -- Humidistats -- Relays -- Solenoid Valves--Line Starters and Motor Contactors in Size 0, 1, and 11-- Water Regulating Valves in sizes up to 2J in. N.P.T.--and Oil Protection Con trols for pressure lubricated refrigeration - compressors. WRITE FOR FREE CATALOGS WHICH GIVE DESCRIPTIONS AND SPECIFICATIONS 1494 *4 -0 . > >5, -g-; ji) ^ : v ~ y SERIES MS RELAYS MS series motor starting relays are volt age controlled to insure cut of starting windings when the motor reaches run ning speed, regardless of the load on the motor. This design permits an exception ally wide differential between pull-in and dropout voltages. Relays can be either factory or field adjusted to meet exact requirements. MS2A for use with % hp motor 115 or 230 volt 60 cycle, MS4A motors up to 3 hp either 115, 230 or 440 volt, 60 cycles. All relays are mounted on molded phenolic bases. Contact arrange ment MS2A, SPST-NC, MS4A, SPST-NC double break. SERIES PR RELAYS SERIES PR are heavy duty, fast acting relays designed for high current or high voltage switching requirements. The full floating movable contact carrier assures ample wipe and contact pressure. Standard contacts are g in. diameter, fine silver, rated 15 amperes, 115 volt, 60 cycle non-inductive or 20 amperes double break contacts. By the use of equivalent size cadmium oxide contacts higher rat ings are possible. A wide variety of standard and auxiliary contact armB are available for multiple current handling requirements. Terminals for printed circuits, plug or screw type, are available. The PR series are Underwriter Labora tory approved. 1495 Controls and Instruments THE POWERS REGULATOR CO. Over 60 Years of Automatic Temperature and Humidity Control. Factory and General Offices: Skokie, 111. Offices in Over 60 Cities, TJ.S.A., Canada and Mexico, see your phone book. New York 17. N. Y. 231 E. 46th St. Los Angeles 26. CaL 3200 W. Temple St. Chicago 13. HI. Toronto Downsrlew, OnL 3319 N. Ashland Ave. 15 Torbarrie Road Mexico, D. F. ' . Apnrtedo 63 Bis. ABC Some of the many controls employed in a Powers pneumatic control system for heating, ventilating, air conditioning and industrial processes are shown here. Controls for water heaters, fuel oil pre heaters and heat exchangers appear on third page. . Powers Thermostats have true gradual action with no constant bleed of com pressed air. They give many years of dependable control with practically no maintenance. Various types for specific implications are available. Some are shown at left. A)Type D Single temperature range room thermostat has durable stamped brass cover and plastic insulating base. Because of its small size b% H x 2% W x 2Jfj in. deep, it fits into narrow vertical spaces. B)Type D Two-temperature range Day-Night thermostat. C)Type 190 Room Hygrostat for humidity con trol, duct typo also available. D)Type D Summer-Winter remote bulb thermo stat for air conditioning units. E) Limitern thermostat for unit ventilators and ducts. F) Type K remote bulb thermo stat . G) Type K remote bulb Submaster thermostat. H) Accritem Temperature Regulator has adjustable sensitivity and calibrated dial adjustment with ranges 50-250F and 150-350F. J) Static Pres sure Regulator for air ducts. Powers Series 100 Recording and Indi cating Controllers also control switches, gages, etc., are available in a variety of models; some are shown on control panels on next page. Powers Packless Control Valves (K and L) are made in various types and sizes for convectors, unit ventilators, unit air conditioners or coils in ducts. With their durable construction, ample power and Duo-Seal packless feature they eliminate normal packing gland friction and give better control. They eliminate steam or water leakage, loss of vacuum and packing maintenance. The Powers Regulator Co. Controls and Instruments UNIT VENTILATOR CONTROL Pow ers latest advancement the LIMITEM Thermostat (E on previous page) is a precision instrument engineered to pro vide accurate low limit control of unit ventilator discharge temperatures ... a critical requirement for classroom com fort. It has sturdy construction, accu rate response, Powers famous NON WASTE double air-valve with adjustable sensitivity and graduated temperature dial for changing the control point. It is fully described in Bulletin S08. Modern Control Panel employing vari ous types of Powers pneumatic control ling, indicating and recording instru ments which regulate four complete year round air conditioning systems. Powers MASTROL Systems for control ling forced hot water heating, radiant panel heating, etc:, are available in various combinations of Master and Sub Master controls. Control panel below shows MASTROL system using Powers Series 100 Recording Master Controller readjusting Sub-Master Indicating Con trollers. Left: Powers Wet and Dry Bulb Recording Con troller with motor driven fan. Powers FLOWRITE diaphragm valves. See other models next page. POWERSTROKE Pislon Operators for Dampers, etc. Available in S in., 4 in. and 6 in. size. Powers modern line of diaphragm control valves, and damper operators meet all heating and air conditioning require ments. Simplicity and good design features in Powers FLOWRITE Valves give close control and they last longer. They are available with single seat, double seat, 3 way mixing and V-Port characterized valve which gives straight line control. Accurate control results from smooth rolling diaphragm and minimum of valve stem friction. Diaphragm has formed bead which provides increased sealing action with increasing control pressure. It has no bolt holes. Diaphram lasts longer without replacement. Piston plate assembly has a free float ing thrust plate which absorbs side thrust. Closely guided piston plate maintains valve stem in accurate align ment. Series S44 Bulletins give more facts about these valves. 1497 The Powers Regulator Co. Controls and Instruments POWERS Temperature Control for Water Heaters, Heat Exchangers, Fuel Oil Preheat ers, and many other uses. ' No. 11 Regulator below, is self-operating, especially adapted for hot water storage heaters. Available with 60F, ranges, various types of valve bodies and trim, also 3 way valves for water mixing. Accritem Regulator at right, is com pressed air or water operated, used to control Powers Three-way Flowrite valves. Is especially adapted for con trol of instantaneous water heaters, sub merged and indirect heaters, 2-Temp, domestic water heating systems--appli cations requiring accurate control and having frequent load changes and for large size valves. Had adjustable sensi tivity, calibrated dial temp, adjustment, ranges 50-250F and 15(1-350F. Sensi tive bulb 12 in. long, )4 in. IPS connec tion. TEMPERATURE ADJUSTMENT Thermostatic Water Mixing Valves-- complete line for individual shower baths, gang showers, hydrotherapy, hot water line control, and processes. Con tact nearest Powers office for bulletins. Controls and Instruments Scully Signal Company Main Offices and Factory: 174 Green Street, Melrose 76, Mass. Representatives in Principal Cities Branch: ScnUy Signal Ltd, 286 King Si, W., Toronto, Ontario SCULLY PRODUCTS include VENTALARM Whistling Tank Fill Signal, VENTALARM GAUGE, combination audible fill signal and tank gauge, and the separate SCULLY GAUGE. VENTALARM Signal--An audible whis tling tank fill signal installed directly on the fuel oil tank as an integral part of the vent pipe. Displaced air forced from the tank by inrusbing oil motivates a sensi tive but sturdy whistle within the body of VENTALARM Signal. The sound travels up and out the vent pipe where it is audible to the man filling. He simply fills until the whistle stops which is when the oil reaches the bottom of the whistle stem (at a predetermined safe level with in the tank allowing for expansion zone). Permits householder to come and go regardless of oil delivery time. Elimi nates need for delivery man to enter home. Stops damaging spills and while the whistle sounds there is positive proof that all parts of the tank fill system are in good working order. SCULLY TANK GAUGE--Easily read even 10 feet away. Gauge face adjust able for convenient reading. Pure white button indicator within oil and odorproof plastic housing in a gasketed seat. Jam-proof lever arm. Oil resistant cork float. Button-Lift allows installation with or without oil in tank. Model GA for 2 in. tank opening. Model GB for 1)4 in. tank opening. Model GC for 1)4 in. tank opening. Specify tank depth--24 in., 26 in., 27 in., 28 in., 37 in. 42 in., 44 in., 47 in. Underwriters' approved. Scully Tank Gauge Combination Ventalarm Gauge These models thread into tank vent flange opening. The lower end of vent pipe threads into top of VENTALARM Signal. Model LA (Listed as Standard by Under writers Laboratory) Bottom Top UP male 1H' female node! L (same as LA except for sue) Bottom Top 2* male female male 1H' female Part No. 201 Part No. 521 240 Special models for special situations in cluding Model LC for Old Tanks--fur nished complete with quick-fit compres sion lock device eliminating need for threading or special fittings. Combination VENTALARM-GAUGB-- Both an audible fill signal and gauge in one unit. No reducing bushing needed. Only one item to install instead of three. Sizes VG-A, 2 in. X 1)4 in.; VG-B, 1)4 in. X 1)4 in- For 275 gal cellar tanks with depth of 24 in., 26 in., 27 in., 28 in., 37 in., 42 in., 44 in., 47 in. " Scully products are manufactured under U.S. and Foreign Patents or Pat ents Pending. Prices subject to change. Over 4,000,000 Scully VENTALARM Signals in use--UL approved. SEE YOUR SUPPLY HOUSE 1499 Controls and Instruments Simplex Manufacturing Company ; 198-206 North Main Street Fond du Lac, Wis. SIM-TROL Barometric Draft Controls--SIMPLEX Roof Vent Flashings Breechings and stacks must provide sufficient draft under adverse atmos pheric conditions. During normal and high barometric periods, cold months and windy days they generate excessive intensities with resulting inefficiency and fuel waste. ADVANTAGES SIM-TROLS automatically maintain a minimum draft required for good com bustion, fuel economy, increased heat transfer by reduction of gas velocity through the boiler, and minimize cold air infiltration and inrush causing sud den shrinkage of boiler parts. They eliminate local hot spots, floating and pulsating flame and sucking out of pilots. They improve feed water regulation, super-heater results, boiler life and boiler room ventilation. Type **-4" SIM-TROLS aid materially in smoke abatement and boiler cleanliness by re duction of unbumed combustibles and air dilution of stack gases. Lowered stack temperatures prolong liner life and reduce fire hazards. CONSTRUCTION . Properly sized SIM-TROLS adjust easily to any desired draft intensity. The races adjust laterally, the race assembly vertically, and the arm angle may be varied in relation to the plane of the gate. - Gates of Type A and Type C'SIM-TROLS rotate on cold rolled arbors and dust proof ball bearings. Curved tubular counterbalances contain metal balls which con stantly change position to compensate for varying rotation angles of the gate, main taining over-fire draft within 0.01 in. water, plus or mjpus. SIM-TROLS are protected by hard, heat resisting boiler room enamels. All coun terbalance members are outside, free from encrustment and corrosion by products of combustion. DESIGN FACTORS Sizing is important. The input opening should equal the stack area, plus 10 per cent for each 35 ft of stack height over 65 ft thereof. Preference should be given to control width, rather than height for ease of adjustment and smooth operation. Horizontal clearance from installation point approximates gate height plus 30 in. Over-all height approximates gate height plus 37 in. Over-all width approximates gate width plus 8 in. Designs for limited space may be made if plans are submitted. Types A, G and F are individually designed to plant specifications presented, in cluding breeching and stack dimensions, clearances, fuel, method of firing and num ber of boilers. Detailed sketches are submitted for approval without obligation. GAS MODEL SIM-TROLS Types A, F and H are available to provide full back pressure relief and draft con trol. If specified, Types A and F are designed for use with coal, gas or oil by minor adjustment by the operator. 1500 Controls and Instruments Spence Engineering Company, Inc. 28 Grant Street, Walden, N. Y. The SPENCE Type ED-W27 TwoStage Pressure Reducing Station iB de signed to serve a heating system depend ably, at low cost and with utmost safety. The primary is a pilot operated, Type ED Pressure Regulator. SECO Metal trim affords guaranteed resistance to wiredrawing. The secondary is a direct operated, Type W27 Valve, simply con structed, yet engineered for long trouble- free, heating duty. Note that the Diaphragm of the SPENCE Safety Pilot is connected to the low side. Should the secondary valve fail, this Pilot will assume control of the primary; thereby effecting a one-stage reduction from primary to final delivery pressure. ^ A Spence Type E2T100 Temperature Regulator reduces the steam pressure in addition to accurately modulating the flow as required to control the temperature. No separate reducing valve is necessary. a By adding a SPENCE Solenoid Pilot any SPENCE Regula tor may be cut on and off electrically. 4- The Spence design provides a self-op erated, pilot controlled regulator en tirely packless in construction and guaranteed to shut tight. SECO Metal seats and discs will not be cut by the wire-drawing action of steam. Spence thermal elements are not injured by overheating Pilot Type T100 is weight-loaded for heaters requiring not more than 10 psi pressure. Pilot Type T150 is spring-set for pressures up to 50 psi. Either may be used on a storage or instantaneous heater in combination with a main valve selected to suit the initial steam condi tions. 1501 Controls and Instruments Sterling, Inc. 3738 North Holton Street, Milwaukee 12, Wisconsin Heating and Temperature Control Products Distributed through leading Heating and Plumbing Wholesalers Sales RepreseatatWes in Principal Cities ' ?$- Controls and Instruments laulor Irudmmcni (jvmpxmUA / Rochester 1, N. Y., U. S. A. * Mfg. Subsidiaries: Taylor Instrument Companies of Canada Limited, Toronto, Canada , Taylor Instrument Companies of Australia Pty. Ltd., Melbourne, Australia Short & Mason Ltd., London, England NEW YORK CHICAGO BOSTON PHILADELPHIA BUFFALO LOS ANGELES PITTSBURGH CLEVELAND ST. LOUIS SAN FRANCISCO HOUSTON CINCINNATI TULSA BALTIMORE ATLANTA MINNEAPOLIS WILMINGTON SCHENECTADY SCOTIA Taylor Instruments for Indicating, Recording and Controlling Temperature. Pressure, Humidity, Flow and Liquid Level CONDENSATION and VACUUM PUMPS 4100 and 4200 Series (illustrated): neat, convenient unit with either steel or cast iron tank. Dual voltage capacitor type motor and carbon type rotary seal--for all jobs up to 15,000 sq It EDR, 20 psi. 3500 Series: heavy duty units with pedes tal mounted steel tank for a wide range of jobs--2000 to 65,000 sq ft, up to 150 psi. 3700 Series: with heavy cast iron tank for installation underground or in wet locations. 2000 to 20,000 sq ft, .20 or 30 psi. Vacuum Pumps: Type V, 2500 and 5000 sq ft, 20 psi. Type S, 10,000 to 40,000 sq ft, 20 to 40 psi. . i. Xti. -s Series 150-E TEMPERATURE CON TROL VALVES Self-powered, modulating control valves --applicable to any process involving heating and cooling by means of water, oil, steam or other fluids. Sturdy bellows --sealed valve with stainless steel trim and monel bellows. Armored capillary tube. Extremely compact--MOUNTS and OPERATES in ANY POSITION. M Sizes: )4 in., % in., 1 in. Max. pressure: w 125 psi. Direct or reverse acting. Series 117-A: Dependable action for H larger capacities. Sensitive thermostat bellows operates a pilot valve--steam supply pressure is used for smooth posi tive operation. Sizes: 1 J4 in., 1)4 in., 2 in.' Max. pressure: 125 psi. Direct acting only. p -Pv^: `It FLOAT and THERMOSTATIC TRAPS Used wherever it is desired to prevent flow.of steam, but to permit passage of .air and water . . . on unit heaters, large radiators and convectors, water heaters, steam main drips and other types of equipment where steam is used. Com pact, rugged, easy to service. Bellows thermostat vents air, float valve has plenty of capacity for large amounts of condensate. Sizes:54 in., 1 in., 1)4 in., 1)4 in., 2 in. Max. pressures: 15, 100 psi. Also Strainers, Radiator Valves, Boiler Return Traps. SERIES 120-A THERMOTROLS Self-contained individual radiator tem perature controls for steam or hot water. Simple to install! Eliminate overheating, save fuel.Maintain even temperature for comfort and health. Sizes: )4 in., 54 in., 1 in. Body styles: Angle, Straightway, Corner. THERMOSTATIC TRAPS: Keep radi ators clear of condensate without wast ing steam. Dependable bellows thermo stat, sturdy bronze bodies and covers, replaceable seats. Sizes: )4 in., 54 in., 1 in. Max. pressures: 15, 65,100, 125 psi. Body styles: Angle, Straightway, Corner, Ver tical. 1502 m *vl-^ -'VSMSe-* H f, *V4h fC -m. - At . vYP M (A) Taylor Industrial Thermometers-- with BINOC* Tubing Includes many styles and scale ranges with bulbs for every application. These thermometers use the well known Taylor BINOC Tub ing--a designed and optically correct glass tubing which assures ease of read ing generally lacking in industrial ther mometers. BINOC tubing more than doubles the angle of vision within which readings can be made. Because of the atented triple-lens construction, its road mercury column can be read easily and accurately with both eyes. Bore reflection is absent. (B) Taylor Biram's Anemometer For measuring air velocities with fan revolu tions indicated on dial. Various models for a wide range of air speeds and regis tration limits. (C) Mason's Form Hygrometer. Pro vides temperature and humidity meas urements. Magnifying thermometer tubes are mercury-filled, approximate range 30 to 120 F. Thermometer scales and siphon reservoir are mounted on a mahogany finished wood panel, 854 *n x 4)4 in. (D) FULSCOPE* Recording Controller An air-operated controller that gives practically any character of process con- *Trade Mark * trol regardless of time lag in apparatus. Available for controlling temperature, pressure, humidity, rate of flow, liquid level. Where extreme load changes or badly balanced operating conditions exist, precision control can be main tained by the automatic reset feature. For applications where a record is not essential, Taylor supplies an Indicating FULSCOPE Controller. (E) Sling Psychrometer Two accurate etched-stem thermometers mounted on die-cast frame, with the bulb of one covered with a wick to be moistened. Whirling bulbs subject this hygrometer to complete air contact to produce ex treme accuracy of temperature and hu midity measurement. (F) Recording Hygrometer Records both wet and dry bulb temperatures on the same chart in different colored inks, making comparison very easy. Type shown has motor-driven fan for conditioned rooms or passages where circulation is poor. Furnished without fan for installations where circulation across bulb is good. Taylor also offers a complete line of the famous Taylor Recording and Dial Ther mometers; Ratio, Pneumatic Set, Self Acting and Type "P" Controllers; Indi cating Hygrometers and many types of Humidiguldes. 1503 Controls and Instruments White-Rod gers Electric Company HT^ New Yobx, N. Y. (Long Island City) Bojtalo, N. Y. 1209 Cass Ave., St. Louis 6, Mo. In Canada, White-Rodgers Limited, Toronto ,; . . Chicago, III. '.`Detboit, Mich. ' Distributors in Principal Cities Cleveland, Ohio Philadelphia, Pa. (Havebtown) HYDRAULIC-ACTION CONTROLS The complete line of White-Rodgers controls includes: Warm Air Controls Relays Low Voltage Thermostats Gas Valves Line.,Voltage Thermostats Oil Burner Controls Hot Water and Steam Con- Refrigeration and Air-Condi-' tools'j. tioning Controls Hydraulic-Action temperature controls `operate 5n the principle of expansion and contraction of a solid liquid charge against a diaphragm. This system, developed and perfected by White-Rodgers provides accuracy com parable to that of a fine thermometer . . . and other outstanding features guaran teeing excellent performance. ADVANTAGES OF HYDRAULICACTION Hydraulic-Action controls provide maxi muni: sensitivity^-positiv'e dial settings :--full range accuracy--consistent differ ential--eliminates temperature drift-- simplified installation--extra_ sturdy switch mechanism--and other qualities that assure long satisfactory operation. Low voltage room thermostat. Ivory and chrome finish. PRIMARY CONTROLS In addition to Hydraulic-Action Con trols, White-Rodgers manufactures Oil Burner primary controls, Gas Valves (both diaphragm and solenoid types) and automatic safety pilots for gas installa tions. Line voltage thermo stat for unit heaters or air conditioning installations. Fan <fe Limit con* trols in single cate. Note the flexible ele ments. Also in single units. "Cushioned Power" Solenoid Cos Valves. Quiet, soft seat, spring loaded. For ALL gases. 7 iy r_ s' A 'T. is. -`A; Dual Hot Water Controls. Limit and Circulator, High and Lout Limit combina tions. Also made in single control*. Remote bulb heavyduty thermostat, also available with selfcontained bulbs. Oil Burner primary control [stack svritch). Intermittent or Con- .. slant Ignition types. - "i i- Contact your nearest White-Rodgers office for complete information. Catalog and engineering data furnished quickly. 1504 K- >. .."i . y. ENGINEERED PRODUCTS Expansion Joints Hot Water and Steam Specialties American District Steam Division Adsco Industries.Inc. 20 Milburn St. Buffalo 12. N. Y. Y.--Planib, Buffalo, n: Richmond, Calif. PACKLESS EXPANSION JOINTS Adsco's Corruflex packless expansion joints absorb pipe expansion and are adaptable tp any piping condition. They are made in two basic types. The self-equalizing joint is used for various types of motion and is suitable for pres sures to 300 psi and higher. The non equalizing type is generally used to ab sorb vibration and a small amount of expansion under vacuum or pressures to 30 psi. .. Depending on the type of metal used in the expansion element, these joints are suitable for temperatures from sub zero to 1600 F. With variations in design, these joints will absorb axial, lateral, or angular motion, or any combinations of these motions. Some types handling these conditions are the universal, hinge, swing, gimbal, tie-rod, balanced, and anti-compression joints. They are made in nominal pipe sizes ranging from 3 in. to 54 in., with single or multiple corrugations. Most types can be supplied with covers to permit joints to be fully insulated and to prevent foreign matter from being lodged be tween the corrugations. When used for axial movement, joints can be equipped with internal guide sleeves to provide a guiding feature and .rigidity. For other purposes they can be equipped with telescoping inner sleeves to reduce turbulence in the fluid being handled. SLIP-TYPE JOINTS Slip-type expansion joints, designed for axial motion, offer long traverse, low initial cost, and produce minimum stresses and strains on pipe anchors. With proper maintenance, they will last as long as the pipeline. The piston-ring joint, illustrated above, with external-internal guiding, can be unpacked arid repacked under full line pressure because of its piston ring feature. The polished, chromeplated slip is in contact with packing only. Hence, it cannot be scored by metal-to-irietal contact. Packing can be quickly lubricated to prolong its life. The slip in the externally-internally guided joint is fully supported at both ends throughout its entire length of travel. The gland is not used as a guiding feature. The internally-guided joint (not illus trated), being more compact, is espe cially recommended for use where space is limited. Adsco slip joints are furnished in both single and double units, with flanged ends or welding ends. Sizes range from 1J4 in. to 48 in. and traverse per slip is 4 in., 8 in., and 12 in. Semi-steel joints can be used for working pressures to 250 lbs and temperatures to 450 F. Steel joints can be used for working pressures to 400 lbs and temperatures to 800 F. PIPE ALIGNMENT GUIDES Adsco pipe alignment guides insure straight movement of pipe line for effi cient operation of expansion joints, per mit line to be completely insulated. In all nominal pipe sizes for various thick nesses of insulation; 12 in. of pipe move ment permitted . 1505 Expansion Joints Badger Manufacturing Company 230 Bent St., Cambridge 41, Mass. 60 East 42nd St., New York 17, N. Y. Representative* in principal cities Also in Canada and Mexico "BADGER PACKLESS CORRUGATED EXPANSION JOINTS" To compensate for thermal expansion and contraction in pipe lines carrying hot gases dr fluids; also used to absorb vibrations. Hinged, Tandem, and Balanced Ex pansion Joints are available for complex piping problems where forces are critical. Badger Non-Equalizing Expansion Joint, Multiple Corrugation. Single corrugation type available. Wide range of sixes. Badger Self-Equalizing Expansion Joint, Directed Flexing Type. Wide range of sixes and traverses avail able. INSTALLATION, OPERATING, MAINTENANCE FEATURES Packless--Each Badger Packless Expan sion Joint is formed from a single tube hence, no packing is needed etc. Engineered Relationship--Between di ameter of joint, depth of corrugation and allowable traverse. crements up to 7% in. for single joints; up to 15% in. for double joints. Connections--Flanged or welding ends available. Materials--Standard joints fabricated from stainless steel or copper. Heat Treatment--Successive heat treat ing operations during manufacture re moves forming stresses and increases life. Wide Pressure Range--Standard joints for pressures up to 300 psig. Wide Temperature Range--Standard joints for temperatures up to 900 F. Wide Traverse Range--In standard in Compact, Easy to Install--Outside diam eters of all Badger Expansion Joints are approximately the same as standard pipe flanges; joints are as easily installed in the line as any fitting. Special Designs--Our Engineering De partment will be pleased to consult with you regarding applications involving large sizes, special alloys, or abnormal operating conditions. Expansion Joints Flexonics Corporation EXPANSION JOiNT DIVISION 1329 S. Third Ave. Maywood, Illinois District Omczs Atlanta Boston Buffalo Cincinnati Cleveland Detboit Ft. Worth Kansas City Los Angeles Memphis Milwaukee New Yohk Philadelphia San Fbancisco In Canada: Flexonics Cobpobation op Canada, Ltd., Brampton, Ontario FLEXON EXPANSION COMPENSATORS FOR STEAM AND HOT WATER HEATING SYSTEMS Model L for pressures to 40 psig The Flexon Model L Expansion Com pensator consists of a two ply phosphor bronze bellows with copper tube end connections enclosed in a floating pro tective shroud of brass. It is especially designed for control of expansion in finned type convectors, baseboard, radi ator or heating supply and return lines. Sizes from % in. through 1% in. Suit able for temperatures from --60 F to 250 F and for pressures up to 40 psig. A single unit will handle motion up to % in. (% in. compression, % in. extension). Available with all commonly used fit tings. Model H for pressures to 150 psig The Flexon Model H Expansion Com pensator is used primarily on vertical risers for high pressure steam and hot water lines. However it may also be used on horizontal runs. The Model H con sists' of a corrosion resistant Flexon bellows enclosed in an all-welded steel housing. The unit is provided with a positive anti-torque device to prevent possible bellows damage during installa tion. Sizes from % in. through 3 in. Suitable for temperatures from --60 F to 750 F. A single unit will handle motion up to 1% in. (1% in. compression, % in. exten sion). Mild steel male NPT pipe nipples on both ends are standard. Ground joint unions or weld ends are optional. Sizes and Dimensions Pipe Size (in.) i m 2 Overall Length, Max. O.D., in. in. Sweat Ends Female Thread ed Ends Sweat Ends Female Thread ed Ends 5% 7%s i% m 8% i% m m 9% 2% m 10% 3He Sizes and Dimensions Pipe Size (in.) % 1 1% 1% 2 2% 3 O/A Length (in.) 9% 9% 13% 13% 12% 13%6 14i%6 Max. O.D. (in.) 2% 2% 3% 3% 4% 5 5% Work ing Press (psi) 150 150 100 100 100 100 100 Unit Wt. (lb.) 2.6 2.8 7.7 8.0 10.3 13.7 17.4 FLEXION EXPANSION JOINTS FOR POWER AND PROCESS PIPING For medium and high pressure piping, Flexonics offers a complete line of corru gated expansion joints in free-flexing and controlled flexing types. Free-flexing units are available in standard sizes from 3 in. to 48 in., I.D. for pressures to 30 psi, temperatures to 850 F. Designed for ex pansion travel up to 3% in. per unit. Controlled-flexing units are available in standard sizes from 3 in. to 48 in., I.D. for pressures to 300 psi, temperatures to 850 F. Designed for expansion travel up to 7% in. per unit. Both free-flexing and controlled flexing types are available with flanged or welding ends. 1507 Fittings and Flanges IScJme?*4 LADISH CO. Wisconsin TO MARK PROGRESS Complete service in Controlled Quality pipe fittings regardless of size, type, wall thickness, pressure rating or material speci fications. ; DISTRICT OFFICES: Atlanta, Buffalo, Chicago, Cleveland, Havana. Houston, Loa Angeles, Mexico City, New York. Odessa, Philadelphia, Pittsburgh, St Louis, St Paul, San Francisco, Seattle, Tulsa. BRANCH PLANTS: Los Angeles. California--Brantford. Ontario, Canada--Kenosha, Wisconsin Standardizing on Ladish_ assures unre stricted selection in meeting your entire fittings requirements . . - for the Ladish. fittings line is complete in types, sizes, pressure ratings ana materials, including carbon, alloy and stainless steels, alumi num, brass and other non-ferrous alloys. All Ladish fittings are produced under rigid metallurgical and manufacturing controls. BUTT WELDING FITTINGS 3^ in. through 42 in. Schedule 5 through Double Extra Strong and special heavy wall thickness up to 4 inches. All fittings carry permanent heat code identifica tion. ' ASA AND MSS FLANGES ASA Flanges } in. through 24 in. 150 lb through 2500 lb ratings, MSS 150 lb Flanges Y in. through 12 in. Large O.D. Flanges in sizes up to 20 ft diameter. Forged under exacting metallurgical controls, accurately machined to full dimensions. SCREWED AND SOCKET WELDING FITTINGS Forged Steel Fittings Y in- through 4 in. 2000 lbs through 6000 lbs. Wide reinforc ing bands provide ample wrench grip surface and extra strength at stress points. Sharp, clean threads of Ladish Screwed Fittings assure tight, leak- Eroof joints. Socket Welding Fittings ave deep, true welding sockets to as sure proper alignment and slip fit. 150 LB STANDARD SCREWED FITTINGS are also available in a complete range of sizes. PRODUCED IN ANYFORGEABLE MATERIAL Carbon Steels Stainless Steels Alloy Steels Inconel Monel Titanium Nickel Steels Carbon-Molybdenum Steels Chromium-Nickel Steels Chromium-Molybdenum Steels Aluminum Forging Brass Nickel-Copper AlloysAluminum-Manganese Alloys 1508 LADISH 304 PAGE CATALOG NO. 55 SENT ON REQUEST Fittings and Flanges s^Ju^flings The Robvon Backing Ring Co. 675 Garden Street Elizabeth 2, New Jersey ; Robvon Backing Rings for Welding Pipe, Valve and Fitting Joints ROB VON Type "CCC" ROBVON BACKING RING TYPE "CCC." This RING is designed for application where variation inside diam eters is relatively great. Extra-long chamfered NUBS maintain the estab lished root opening under the most adverse fit-up. The easy "STRIKE OFF" feature of the "CCC NUBS" per mits each to be removed with a light tap of a hammer. Normal welding currents ' may be used when the NUBS have been removed. , ROBVON Type"CC" ROBVON TYPE "CC" is inserted into beveled end of pipe with the split end of the ring placed at the bottom of the pipe and the spacer NUBS flush against the land of the pipe. The beveled end of adjoining pipe is slipped onto the backing ring until the edge of pipe bevel is firmly abutted-against the spacer NUB. Diameter of NUB automat ically sets the root opening for the electrode. The welder has the choice of "STRIKING OFF" the NUBS or leaving them intact. If the NUBS are not chipped off, a higher welding current will insure full penetra tion and fusion of the spacer NUB. ROBVON Type "C` ROBVON TYPE "C." The fit-up proce dure is the same as outlined above. The non-removable NUB is readily and completely fused during welding by using a slightly higher than normal welding current. MACHINED rings are manufactured to specification in either the solid or split type design. All ROBVON Rings are available in carbon steel, wrought iron, alloys, stainless steel, aluminum, etc. Machined Ring Nom. Pipe Size M* 1* w w 2* W 3* w 4* 5* 6* 8' 10" 12* 14* 16* 18* 20* 24* 30* 36* 40* I.D. of Pipe Std. Inches .824 1.049 1.380 1.610 2.067 2.469 3.068 3.548 4.026 5.047 6.065 7.981 10.020 12.000 13.250 15.250 17.250 19.250 23.250 29.250 35.250 39.250 X Hvy. Inches .742 .957 1.278 1.500 1.939 2.323 2.900 3.364 3.826 4.813 5.761 7.625 9.750 11.750 13.000 15.000 . 17.000 19.000 23.000 29.000 35.000 .39.000 SPECIFICATIONS No. of Root Open ing Spacers Type C Type CC & CCC Dia. of Spcr. 33w 3 3 h' 3 3 Vi' 3 3 - H' 3 3 He' 3 3 Me' 3 3 Mb' 3 3 Mb' 4 3 Me* 5 4w 5 4 Ma' 6 4 Me* 9 4 Mb' 9 5 Mb' 9 5 Mb' 12 5 Me' 12 6 Me' 12 6 Mb' 15 6 Mb' 18 6 Mb' 21 6 Mb' 21 6 Mb' 1509 Ring ' Thickness Ma* Hi' Hi' Ma' Hi' Hi' Ma' Hi' w H' H' Vi' H' V4' Vi' Vi' Vi' Vi' Vi' Vi' Vi' Vi' - Ring Width H' H' nm H' H' H' H' H' H' 1* 1' 1' 1' 1* 1' 1' 1' 1' 1' 1' 1' 1' Width of Land H' H' H' H' W W H* H' w H' M' M' W W w W *W H* M' H' M' 54' m Fittings and Flanges S^cialties'nf" ii Taylor Forge & Pipe Works General Offices & Works: Chicago 90, 111. (P. 0. Box 485) Plants: Carnegie Pa.; Fontana Calif.; Gary, Ind,; Houston, Tex.; Hamilton Ont., Can. TAYLOR FORGE WeldELLS District Offices New York: 60 Church Street Chicago District Sales: 208 S. LaSalle St. Philadelphia: Suburban Station Bldg. Houston: 707 N. Drennan St. Pittsburgh- P. O. Box 122, Carnegie, Pa. Los Angelee: General Petroleum Bldg. San Francisco: Adam-Grant Bldg. Atlanta: 705 Mortgage Guarantee Bldg. Toronto, Ont., The Dominion Bank Bldg. Tulsa: Constantine Bldg. * Short Radius Return Bend I FullBranch Tee . s 90 Long Radius WeldELL _____ __ 46 WeldELL Long'Radius Return Bend Whatever your piping requirements the Taylor Forge line-- WeldELLS and Forged Steel Flanges--will meet them. The WeldELL line offers a wider range of type sizes and weights in a complete range of materials. Popular ranges are listed below; more complete ranges in the big Taylor Forge catalog. . . Write for the name of your nearby Taylor Forge distributor, who carries stocks of WeldELLS and Flanges. Type of Fitting WeldELLS Welding Fittings--Range of Sizes Descrip tion 90 Long Standard Weight Y-wr Extra Strong 4'-30* Sched ule 160 i'-24' Double Extra Strong I'-s* WeldELLS 90 Short l'-24' l'-24' l'-8' l'-S' WeldELLS 45* Long Y-stf F-30* JM2* r-s* Return Return Tees Tees Reducers Stub Ends Saddles Sleeves 180* Long r-30* Y-zo* Radius 180* Short l'-24' l'-24' Radius Full |'-24' |'-24' Branch Reducing rxrxr l'xi'xr outlet 16*X16#X6# 24'X24'X10' Concentric J'Xi' l'X!' A Ec 30?X24' 30*X24' centric l'-24' l'-24' Lap Joints l'-24' l'-24' 2* 24* -- Welding 2'-24' -- $*-12* r-8' l'-l2* -- -- -- -- -- -- l'-8* l'-8' rxr 8*X31' lr-6* l'-8' -- -- Forged Steel Flanges--Range of Sizes 150 300 400 600 900 1500 2500 lb. lb. lb. lb. lb. lb. lb. Socket Type 24* Y-24' *'-24' Y-2Y i'-24' i'-24' r-24' r-24' r-24' r-24' *'-24r-12' r-ir r-12' *'-24' r-24' 4'-24' r-24' r-24' r-24' r-12' r-24' 4'-24' r-24' 4'--24' r-24' r-12' r-12' Y-2Y r-24' r-24' r-24' r-24' i'-24' r-12' Y-24' r-24' -- ------ Reducing (Threaded and r-24* r-24' r-24' i'-24' r-24' r-24' |'-24' Orifice \ -- l'-24' r-ir r-ir l'-ir r-ir` -- 1510 > M ' y&\ M f! .vy. Fittings and Flanges Pipe Welding Specialties Tube Turns A Division of National Cylinder Gas Company General Offices and Factory: Louisville 1, Ky. TRACE MARK DISTRICT OFFICES: TRACE MARK NEW YORK, 150 Broadway--Rector 2-8230 PHILADELPHIA, Sub'. Sta. Bldg.--Rittenhouse 6-0722 , PITTSBURGH, 3001 Grant Bldg--Atlantic 1-8848 CLEVELAND, 52 Manning Dr., Berea, Ohio-- Berea 4-1554 . CHICAGO, 600 S. Michigan Ave.--Harrison 7-8526 DETROIT, 6432 Cass Ave.--Trinity 3-7938 ATLANTA. 22 Marietta St.--Walnut 7310 MIDLAND, Tex.. 209 Ridglea Dr.--2-5743 DALLAS, 155 Leaa Drive--Fairdale 0860 TULSA, 305 Wright Bldg.--Cherry 2-9193 . KANSAS City--Westport 8111 DENVER, Rm 370, Silver State Bldg--Main 3261 LOS ANGELES, 2417 E. 24th St.--Ludlow 7-8287 SAN FRANCISCO, 2611 Russ Bldg.--Garfield 1-2594 HOUSTON, 7120 Katy Road--Underwood 2-6631 SEATTLE, 101 Jones_Bldg.--Seneca 8118 In Canada: Tube Turns of Canada Limited, Chatham, Toronto, Edmonton DISTRIBUTORS IN PRINCIPAL CITIES In addition to carbon steel welding fittings listed here, the complete TUBE-TURN line embraces many alloys--types 304,347 and 316 stainless, carbon moly and chrome moly steels, copper, aluminum, brass. Monel, Inconel, nickel and wrought iron. Dimensions and engineering data are included in TUBE TURNS catalog sent on request. TUBE-TURN SEAMLESS WELDING FITTINGS RANGE OF TYPES AND Siriw 45 Long Radius Elbow Concentric Reducer Eccentric Reducer Carboe Steel Type ot Fitting Stand- Extra Sched- Double Light gaga etrong waB ulce I. P. S. O D. O. D. ELBOWS RETURNS TEES nCDUCERS CAPS STUB ENDS LATERALS CROSSES . RINGS SADDLES1 SLEEVES* M Lone Radio* 90 with Tangent 90 Reducing 90 Short Radio* U Long Radio* 100 Long Radio* 100 Ex Long Rad100 Short Radio* Straight Outlet Reducing Outlet Concentric Eccentric Lap Joint Straight Outlet Reducing Outlet Straight Outlet Reducing Outlet Cium Type Ridge Type 11-0 19-42 i*1021--xxCc012- 111229xx-0t0- 111-42 19-42 11-42 *-30 t-JH *1--211 M2 19-3# 11119--2402 0*0xx1*1 11x14 30x10 *x* Mill 42x24 42x24 *x *x* 42x21 42x24 H-42 *-42 11-24 11-24 1-24 1-24 uh n* 24x10 24x10 IM-24 114-24 l*x* 114x11 24x10 24x10 *-24 H-K *-11-224 2-30 2-30 1-12 *-0 11--1122 *2--88 *-12 *-o *12xx0* *x0 *0xx0* *x* 0x319 *121xx-10*2 Kx* 01-x03* 114-0 0-24 0-24 0-24 0-24 0-24 4-24 4-24 4-24 1 Sine* SADDLES aod SLEEVES are used far external ninteraeaaeni only, they do not conform to Iras Pipe Site Thicknee*. Straight Tee 90* Long Radius Elbow 180* Long . radius Return Straight Lateral TUBE-TURN FORGED STEEL FLANGES RANGE OF TYPES AND SIZES Saddle Welding Ring Lapped Flange Typo ef Flange Carbon Sled ISO lb <00 lb* COO lb W0 lb* 10001b 20001b WELDING NECK 11-42 *-42 11-42 11-43 *-24 11-24 SLIP-ON 19-42 V9-42 W-43 19-42 19-24 19-24 LAP JOINT *-34 19-24 >9-24 19-24 19-24 1924 THREADED 11-24 19-24 19-24 19-24 19-24 19- B BLIND H-42 11-42 12 42 *-42 11-24 *-24 SOCKET TYPE REDUCING ORIFICE Threaded or Slip-On Threaded W-24 *-34 H-4 *-24 1-24 *-21 4-B *-311 *-12-142 *2-2-142 *-t2 1-13 Slip-On Welding Neck M2 t-42 1-42 9-42 4-0 4-42 1-12 0-12 M2 11-13 19-11 H-K 19-13 11-13 *-12 oo dxra thru 3* loch (except Orifice Flange*) ' as tot WO lb Banc on rite* thru 2* inch (except Orifice Fiancee) as (or U00 lb fiaa^e. 'TUBE-TURN" and Reg. U. S. PaL Off. Straight Cross Welding Neck Flange Socket Flange Floats Arthur Harris & Co. 2J0-218 N. Aberdeen Street Engineers--Metal Float Manufacturers Chicago 7, HI. Floats Fabricated of Aluminum, Brass, Copper, Admiralty, Everdur, Monel, Nickel, Inconel, Stainless Steel, Type 304, Type 316, etc., Steel and other Workable Metals Floats can be plated with copper, nickel, chrome, zinc, tinned, or lead coated. Special connections can be furnished where required. B-262 ball floats are pro - vided with standard female pipe spuds--unless special connections are ordered. Stainless steel, steel, nickel and monel floats, are suitable for high pressure and high temperature; Where corrosion is a factor, our catalog should be consulted so that floats of suitable material can be furnished. Open tank floats can be loaded with sand, lead or steel to bring them to a desired weight. Aluminum floats are vulnerable to corrosion by many solutions, but also give satisfactory results when properly used. Metal Floats Flat Cylindrical Cylindrical Cylindrical Seamless copper ball floats carried in stock in diameters of 3 in., 4 in., 5 in., 6 in., 7 in., 8 in., 10 in., and 12 in. for open tank. ... 25 lb, 50 lb, 100 lb, and 150 lb working pressure. Copper floats of special sizes and for special pressures made to order. Stainless steel ball floats 2J/ in. to 12 in. diameter for high pressure and corrosion carried in stock. Special stainless steel floats made tc order.--Copper Ball floats of 12 in. and to 18 in. diameter, and stainless steel floats over 12 in. to 14 in. diameter made to order. Consult our Engineering Department when you have float problems. Catalog on request. Copper plated---brazed joint--steel ball and special floats for high and low pressure. Ask for Special Bulletin on these steel base floats. 1512 Heating Systems SS2?5&?vSff. (jeneral Automatic Products Corporation I MRAL 2300 Sinclair Lane Baltimore 13, Md. Manufacturers of a Complete Line of Gas and Oil Heating Equipment and Summer Air Conditioning FLOORLEVEL BASEBOARD RADIATION "FLOORLEVEL" Hot Water DUAL DE-AIRATOR TANK TWO TYPES FOR EASY INSTALLATION A complete unit with feed and relief valve, for positive elimination of air in hot water heating systems; also acts as an expansion tank. Three sizes to 1500 sq ft. ,, SERIES "L" GAS FIRED BOILER BURNER UNITS Available for natural, manufactured, mixed or LP gas. All units only 30" high, completely assembled. Controls avail able to meet all local code requirements; SPECIFICATIONS: .- . A.G.A. Ratings. ' V vi Model Btu Input Btu Output Sq Ft Output L-4 to L-10 72,000 to 57,600 to.-, 384 to 960 " 180,000 144,000 Specifications I=B>R Capacitv (per lin. ft) Ratings Water Temp. STANDARD HI-CAP 200" 190" 180" 610 Btu 550 Btu 490 Btu 750 Btu 680 Btu 600 Btu OIL FIRED BOILER BURNER UNITS "WA" "T Each package consists of enough ma terial to do the average installation for the amount of square footage required. The packages are sized to fit any installa tion. Carton No. 1 contains the fin type heating element, assembled with front panel, back panel, etc., in 10-ft lengths, Carton No. 2 contains the front paneling, top moulding and fittings, and Carton No. 3 contains the panel and moulding. Elements are interchangeable, without adjustment to enclosure or other parts. "WA" is pre-wired and pre-assembled, complete with Burner, 3 controls and circulator. Available in 2 sizes: Model No. WA-85 WA-100 Boiler Ratings Capacity EDR Hot Water Sq Ft 500 650 Series "T" Steel water-tube BoilerBurner unit, constructed to ASME Code, Available in following sizes and ratings: Model No. Boiler Ratings EDR Hot Water Sq Ft Steam Sq Ft T-16 to T-30 580 to 1980 326 to 1100 . waieT flow rate oj o,uvu lb/hr. i above hot looter ratings were based on an active ten o/9/t9in with total length of 10 ft. Also manufacturers of a complete line of summer and winter air conditioning equipment. 1513 Heating Systems Baseboard Radiation, Fin Coils - KRITZER RADIANT COILS, INC. "IF IT'S KRITZER, ITS RIGHT SIR" 2909A LAWRENCE AVENUE . CHICAGO 25, ILLINOIS "K" LINE Radiant Baseboard for RESIDENTIAL, COMMERCIAL, _1_ %' *1*'1 INDUSTRIAL and INSTITU TIONAL HEATING Quick and easy to install with such >----~~\J KRITZER features (at no extra cost) as; Coil Support Bracket, Coil Shoe, Manual 9*r Damper, and Optional Knob Control. Capacities shown below are representa T- -0-r tive of the wide selection available with KRITZER Radiant Baseboard. Capacities per linear foot. Air'at 65F k ii i1j Element Symbol 275-40A 21-40A 21-40 SBC-40 / psi STEAM 200F T Cover Sq Ft per Btu per Symbol Lin. Ft Lin. Ft Water (1 gpm) $ ..1 -**i f K-l KU-1 KU-1 KS-1 3.50 4.40 3.90 -- 840 1055 935 --. 645 820 . 720 780 Get BULLETIN S00 for complete information STB Radiant Baseboard for SCHOOLS, HOSPITALS, OFFICE BUILDINGS, INSTITUTIONS, and FACTORIES Sturdy. Lifetime of efficient service. Has such KRITZER. features (at no extra cost) as Adjustable Coil Support Bracket, Coil Shoe, and Patented Damper and Control. Capacities shown below are but a few of the wide selection , available with KRITZER Radiant Baseboard. Capacities per linear fool. Air at 6SF Element Symbol 31-40 4125-40 42-40 4125-40A 1 psi STEAM Cover Sq Ft per Btu per Symbol Lin. Ft Lin. Ft STB 3-1 STB4-1 STB4-1 STB4-1 5.1 6.7 6.3 7.9 1225 1610 1510 1895 200F -- 3*-- Water (2 gpm) L" minimum height 970 from Hoot. 1220 1090 Write for complete 1445 information -f KRITZER Radiant Panel Heating SEE YOUR JOBBER FOR KRITZER PRODUCTS Simple, efficient, and economical method of Radiant Panel Heating. KRITZER coils are positioned between joists slightly back of plaster line. They touch no part of the building, are not imbedded in any building material. Heating Contractor can install complete job without special cooperation from other contractors. Air between joists is heated which in turn heats floor and/or ceiling surfaces. For complete informa tion on installation and advantages, send for Bulletin 155. 1514 Heating Systems ] Shaw-Perkins Manufacturing Company manufacturers of convector radiators delivering - 201 East Carson St. AIR-e-ATED RADIANT HEAT Pittsburgh 19, Pa. Shaw Panel Radiators Shaw Panel Radiators WIDTH; 3 in. thin. 6 HEIGHTS; 11 in., 14 in., 17 in., 20 in., 23 in., 26 in. 51 LENGTHS; 11 in. to 111 in. incl. in 2 in. incre ments. TAPPING: /*> in. % in., or 1 in.--same end or opposite end. RATING: 3.9 to 480.7 sq ft EDR. GRILLE: front or top air outlet. INSTALLATION: wall hung, free standing, open or closed recess. APPLICATION : hot water, steam to 150 psi or mixed systems. End panels, air chambers, wall brackets available for any application. All Shaw Radiators convert the heat furnished by the steam or hot-water into an exact engineered ratio of warm circulating air and mild radiant heat rays which creates an "ideal heat environment" in each room. It is known as AIR-e-ATED RADIANT HEAT. Shaw Baseboard Radiators Shaw Panel Baseboard Radiators WIDTH: 3 in. thin. HEIGHT: 8 in. LENGTHS: 2 ft 5 in. to 72 ft 7 in. with opposite end tapping; 2 ft 3 in. to 36 ft 7 in. with same end tapping. TAPPING: Supply and return on same end or oppo site end. RATING: 6.0 sq ft EDR per lineal foot. GRILLE: Front air outlet. INSTALLATIONS: Wall hung and cor ner radiators; end panels available. AIR CHAMBERS: Factory installed for hot water systems. APPLICATION: Hot water or steam systems, up to 15 psi. Shaw Panel Baseboard Radiators are factory assembled one-piece-bonded units, each unit individually packaged complete with fittings to assure simpli fied, quick installation. PERKINS AIRadiators Perkins AIRadialore WIDTH: 5 in. thin. 3 HEIGHTS: 14K in., 23K in^, 45 in. LENGTHS: 15 in. to 125 in. inclusive in 2J in. increments. PIPING: 1 in. tapping, can be bushed to in. or % in; as specified. RATINGS: 14 to 474 sq ft EDR. TAPPINGS: supply and return on opposite ends--radiator reversible. AIR CHAM BERS: factory installed for hot water systems. INSTALLA TION: wall hung, free standing, ceiling mounted. APPLICA TION : hot water, low or high pressure steam systems to 150 psi. . . . Factory assembled, sturdy, heavy duty, industrial heating unit ready to connect to new or existing piping. Used on low or high pressure steam or forced circulation hot water systems. Con structed of 1 in. copper tubing and full-height steel plates. Represented in principal cities. Send for catalog. 1515 Heating Systems Baseboard and Under Floor Ducts National Glay Pipe Manufacturers, Inc. 1820 "N" St., N. W., Washington 6, D. C. 311 High Long Bldg., 5 E. Long&t., Columbus 15, Ohio 703 Ninth St Hill Bldg., Los Angeles 15, Calif. 100 N. LaSalle Sr., Rm. 2100, Chicago 12, 111. 200 Connally Bldg., Atlanta, Ga. CLAY PIPE HEATING. VENTILATING, AND AIR CONDITIONING DUCTS Information contained here includes the by eliminating high heat-loss at ceilings basic data needed by engineers, -archi tects, builders, and heating contractors to evaluate and install low-cost Vitrified or attics. Successful research conducted by the National Warm Air Heating and Air Conditioning Association has been Clay Heating Ducts in basementless slab- ! followed with great interest by the build floor homes and other structures. This new development has become so popular that many requests for authoritative in ing and heating industries. According to the Association, "Warm Air Perimeter Heating is a highly successful method of formation have followed the publication heating a basementless building. ... It of articles about the new system in the tra'de press. There are three major reasons for its. popularity: produces the ultimate of occupancy comfort. It is economical to install; can be designed to use a minimum amount of ECONOMY--The complete Clay Pipe installation is economical and efficient. It combines the advantages of radiant scarce materials; and requires no unusual skill in its design and installation that the heating contractor cannot supply." heat and controlled warm-air circulation at greatly reduced costs. SERVICE--Clay Pipe actually outlasts the foundation slab. It is chemically inert and cannot be eaten away by lime in the concrete. It does not rust, corrode, or disintegrate from moisture and fur nace gases. It will not crush or deform as concrete is poured over it. INSTALLATION--Clay Pipe's handy lengths and easy-to-make joints permit fast installation and lower labor costs. A wide variety of fittings is available to solve construction problems with no on. the-job delay, and Clay Pipe cannot "float" as the concrete is poured. PERIMETER LOOP SYSTEM--The data and instructions contained here apply to the Perimeter Loop System, smce it is more highly recommended by heating authorities. Its pattern elimin ates the "waterfall" of cold air. at the outer walls and effectively combats "radiant cold" at the outside edges of the slab. It combines the advantages of forced warm-air heating with heat by radiation'..through the concrete slab. Heat is concentrated where people are sitting--not at the ceiling. In test in stallations, the new heating method has cut operating costs from 20 to 30 per cent THIS PERIMETER LOOP DESIGN is used in structures built upon a concrete slab directly on the ground. Its air dis tribution system includes a warm air duct that extends completely around the perimeter of the building in a con tinuous loop. The ducts are buried in the slab 2 to 18 inches from its outside edge, and the tops of the bells will be inches below the slab surface. Heat is delivered into the rooms by warm air discharged from registers placed in the floor beneath the windows, and by radiant heat from the warm floor sur faces over the embedded ducts. The loop is supplied by feeders extending from a plenum chamber in the slab. Healing Systems Baseboard and Under Floor Ducts National Clay Pipe Manufacturers, Inc. Washington 6, D. C. Typical Installation of Clay Pipe Heating Ducts g DuCtS .` -ri; Advantages It is well known that the greatest heat loss in a well constructed and insulated building--commercial or residential-- will be found at the outside walls and glass areas. This loss will usually average 65 per cent of the total structural heat loss. Concrete slab floors will account for approximately 18 per cent of the total heat loss. The rest of the heat will be lost through the ceiling or attic. Perime ter heating introduces the heat along the outside walls and along the glass area. The heat rises and the resulting blanket ing effect reduces the radiant heat loss from all outer walls and windows. Fur thermore, this blanketing effect also eliminates air drafts which are caused by the cooling influence of the walls. The heating ducts, embedded in the concrete slab floors, help to maintain the floor surface temperature at desired com fortable levels. It can be seen that perim eter heating accomplishes three im portant basic functions: first, it replaces the heat that is lost; second, it replaces the heat at the same point where it is lost; and third, it replaces the heat as fast as it is lost. (b) Temperature gradients from; floor to sitting level--30 inches above, the floor--can be maintained at lessHhan 2 deg. ,. (c) Temperature gradients from flcidr to ceiling level can be maintained at less than 8 deg. - (d) Temperature variations from outside wall areas to the center of rooms' can be maintained at less than 2 deg. ? i (e) Temperature variations between rooms can be maintained at less than 3 deg. Versatility Clay pipe heating ducts can also be adapted for ventilation purposes. This is another advantage of the under-slab duct design--the required amount of ventilation air can be circulated through the same distribution ducts used for heating. Furnaces Although a down-flow type of furnace is generally associated with the perime ter warm air heating system wnen in stalled in basementless structures, all types of winter air conditioning units can be used. Successful installations have been made using up-flow types of equip Test Results Tests conducted by the National Warm Air Heating and Air Conditioning As ment as well as horizontal units. When up-flow furnaces or horizontal suspended units are used, down-comer ducts are sociation at its University of Illinois Re used to connect the warm air plenum search Center and in actual installations of the furnace unit with the distribution throughout the country indicate that plenum in the floor. Also, two or more temperatures in residential structures can be maintained well within the limits established for comfort conditioning. Perimeter heating systems can be de signed so that the following temperature coefficients may be maintained: (a) Floor surface temperatures can be maintained at 70F plus 2 deg in all usable areas. furnaces can be installed--each unit having separate control for its own dis tribution system so that various sections of the structure can have individual temperature control. However, one unit sized for the entire heat loss can be also installed, using two or more bonnet outlets with automatically controlled dampers in each. Heat,i.ng Sr,yst.e__m__ s_ Baseboard and Under Floor Ducts National Clay Pipe Manufacturers, Inc. Washington 6, D. C. m r|| VITRIFIED CLAY PIPE FOR UNDERFLOOR HEATING DUCTS Conforming to ASTM Specifications C-13 'iri M Size, in. (D)' Laying Length (L) Nominal, ft Limit of Minus Varia tion,* in. per ft of length Maxi mum Differ ence in Length of Two Op posite Sides, in. Outside Diameter of Barrel, in. Min. Max. Inside Diameter of Socket at Yi in. Above Base, in. CDs) Depth of Socket, in. (Le) Min. Max. Nom inal Min. Thickness of Barrel, in. (T) Nom inal Min. Thickness of Socket at in. * from Outer End, in. (Ts) Nom inal Min. 4 2, 2%, 3 x 6 2, 2%, 3 X 8 2, 2%, 3 X 10 2, 2X. 3 X He m 5% 6% i% X Xb Xb X X 7Xb Wb Wb m 2% 2 % Xb X Xb Xb m m iox ii 2% 2% % 'Xb Xb % Xb ux 12 12% 13% 2% 2% X 1Xb X Hb d -u There is no limit for plus variation. 1518 ' , -_____________ Heating Systems fiSA*, National Clay Pipe Manufacturers, Inc. Washington 6, D, C. Storage There are no storage problems, becausevitrified clay pipe heating ducts can be exposed to weather in any season. Performance in Use Clay pipe ducts have such advantages as permanence, resistance to shock loads, and resistance to corrosion from lime in the concrete. They create no odor as warm air flows through them during furnace operation. The smooth inner surface eliminates turbulence and mini mizes register noise. The clean smooth surface of the Vitrified Clay Duct is free from dust. - Design Data Detailed design recommendations have been prepared by the National Warm Air Heating and Air Conditioning Association and are contained in the new revised edition of Manual 4 ($1.50) and Manual 9 ($.76), which are available from the association's offices, 145 Public Square, Cleveland 14, Ohio. Manual No. 4 de scribes warm' air perimeter heating systems as applied to structures without basements. Manual No. 9 contains de tailed information on design and instal lation of warm air winter air conditioning systems and all necessary engineering data, tables, and recommendations for se lection of the proper heating equipment. Case Histories For data on actual case histories of Clay Pipe heating, ventilating, and air condi tioning duct installations in homes, schools, churches, hospitals, factories, gasoline stations, garages, stores, and theaters, write the National Clay Pipe Manufacturers, Inc., 1820 "N" St., N.W., Washington 6, D. C. . Large diameter clay pipe heating duct and plenum con nection used tn commercial structure. This type of duct, when tnstoiled tn garages and maintenance or repair shops, can be used Jot heating, ventilating, air condi tioning, and removal ofexhaust gases. When the registers are located under the windows, the warm air toil! blanket the plots area and eliminate frosted and icet windows, sills, and walls. Clay Pipe Heating Ducts ready for th e concrete pouring. Wire mesh may be installed at the contractor's discretion to reinforce the floor slab. 1519 ____________________________ Heating Systems gMSTpU, National Clay Pipe Manufacturers, Inc. Washington 6, D. C. Construction Data The building site must be well-drained. If the natural ground-slope is not suffi cient for good drainage, a simple net work of Perforated Clay Pipe should be installed underground. The site should then be levelled and graded: All ground beneath the building should be cleared of organic material. A four to six inch layer of coarse fill is then laid--washed gravel, crushed rock, or stone that has been passed over a coarse screen. Cinders or fine sand should never be used for the SAM El { 3$ BARBU SUPPORTS BUI w* AND SPIGCOT ClAt Pipe ON fill \ CAULKING 1-------- N SMAU EXCAVATION IN Fill FOR Bill ^ RICH CEMENT Figure t After the slab has hardened, the form can be removed and an opening cut into the pipe with a heavy hammer or bar. . Some contractors prefer to retain the wooden register forms in the slab for register mounting frames. ture barrier before the slab is gotlred. This membrane should be the equivalent of a good grade of roll roofing at least 55 lb per 108 sq ft. Strips should be over lapped at least four inches aiid tarred. The barrier must completely cover the area within the foundation walls and extend up the walls to the top of the slab. See Figure 1. Edge insulation must be placed com pletely around the concrete slab. Twoinch thick insulation is recommended, but one-inch is acceptable. It is not necessary to anchor the Clay Pipe ducts to stakes, or to surround them completely with concrete (as with lighter materials). The Clay Pipe is laid directly upon the membrane, and gravel or sand is used to level it. Small depressions should be made in the sand or gravel so the pipe bells "hang free." This facilitates proper pipe alignment and prevents buckling at the joints. See Figure 2. ' Figure 5 The Clay Pipe bell at the plenum should be butted firmly against the wooden forms of the plenum pit and the concrete poured around it. See Figure 4. The pit floor is poured after the wooden form is removed. The moisture mem brane must extend- under the pit floor. Recommended distance from the slab floor to the top of the pipe bell is five inches. ' ClAY PIPE BUTTED AGAINST FORM Registers must be located before the slab is poured. Wooden forms like those shown in Figure 3 are secured to the pipe by a wire wrapped around the duct. 1520 Heating Systems u^Mow Ducts National Clay Pipe Manufacturers, Inc. Washington 6, D. C. \WBELL BELOW SLAB SURFACE . ! 'V* - * CLAY PIPE *-IJ Figure 5 BELL 5" BELOW SLAB SURFACE .* A FURNACE PLENUM Clay Pipe in the Perimeter Loop should be installed so that the top of the bell closest to the perimeter, will be 1% inches below the slab surface. Feeder ducts should slope downward toward the plenum, so that the top of the bell next to the plenum will be five inches below the floor slab surface. See Figure 5. All Clay Pipe joints must be waterproof. Care must be taken when the slab is poured not to puncture the moisture barrier or dislodge the ducts. Wheel barrows should not be moved over the ducts without suitable planking. A strip of mesh should be placed over the top of the ducts to give added strength to the slab. Mesh may be extended over the entire slab at the contractor's discretion. OTHER STANDARD FITTI N GS-ELBOWS -REDUCERS-DOUBIE TEES AND WYES 1521 Heating Systems Direct Fired and Steam Unit Heaters and Convectors Airtherm Manufacturing Company 728 S. Spring Ave. St. Louis 10, Mo. Representatives in Principal Cities . For Heating Satisfaction--Think first of AIRTHERM formance. Copper coil for all hot water and two pipe steam systems. Produced in full range of types and sizes. Write for Catalog 70S. ' AIRTHERM Cabinet Unit Heater Combines 22 industry approved, per formance proved features that guarantee maximum efficiency. Vertical Horizontal AIRTHERM Steam Unit Heaters, Horizontal and Vertical Discharge Horizontal models are produced in ca pacities from 18,000 to 270,000 Btu. Ver tical models 32,000 to 350,000 Btu per hour. Write for Catalog 1209 A. AIRTHERM Gas or Oil Fired Space Heaters A complete heating, and heating and ventilating unit. Equipped with motors, burner and all safety and operating con trols. Easy to install and operate. Heavy duty stainless steel combustion chamber. Capacities from 400,000 to 2,000,000 Btu per hour. Write for Catalog 804. AIRTHERM Gas Fired Unit Heaters Efficient answer to heating needs where there is no steam supply. Compact, sus pended, propeller fan units available from 25,000 Btu to 200,000 Btu. Write for Catalog 500. AIRTHERM Centrifugal Fan Unit Heaters For all types of heating, and heating and ventilating installations, in industrial and commercial buildings, auditoriums, AIRTHERM Convectois gymnasiums, schools. Available with dampers, filters and non-freeze coils. Airtherm Convectors are designed for Capacities up to 1,440,000 Btu per hour. easy installation and outstanding per- Write for Catalog 408. 1522 Boilers Heating Systems Radiators Convectors American - <$tadai*d Plumbing c& Heating Division American Radiator & Standard Sanitary Corporation, New York 18, N. Y. 1. EMPIRE BOILER For all types of gas. Made in a com plete range of sizes for smaller homes and buildings with or without basements. Approved by American Gas Association. UB=R Ratings: Steam--165 to 275 sq ft, Water--160 to 1,055 sq ft net installed radiation. 2. G-4 BOILER For all types of gas. For larger homes and small commercial establishments. Approved by American Gas Association. I-B^R Ratings: Steam--395 to 1390 sq ft. Water-- 725 to 2400 sq ft installed radiation. 3. G-6 BOILER For all types of gas. Designed for medium to very large buildings. Approved by American Gas Association. I-BrR Ratings: Steam--1520 to 13450 sq ft, Water--2615 to 21520 sq ft installed radiation. 4. ARCOLINER PACKAGED OIL-FIRED HEATING UNIT. Compact unit for small to medium sized homes. Wet base con struction ideal for homes with or without basemeilts. I-B-R Ratings: Steam--260 to 520 sq ft, Water--485 to 940 sq ft in stalled radiation. " 5. OAKMONT BOILER Exclusively for oil firing. Also avail able as complete oil heating unit with Arcoflame Burner. 1-BrR Ratings: Steam--390 to 810 sq ft, Water--715 to 1440 sq ft installed radiation. 6.'EXBROOK BOILER For oil or stoker. Sized for larger homes and buildings. Available with Arcoflame Burner as oil heating unit. 7=B=fl Ratings: Steam--775 to 1830 sq ft, Water-- 1380 to 3100 sq ft installed radiation. 7-. SEVERN BOILER For all fuels. Efficient boiler with ad vanced features for convenience and economy. Available with Arcoflame Burner as oil heating unit. Ratings: Steam--400 to 780 sq ft. Water--730 to 1390 sq ft installed radiation. 8. REDFLASH BOILER For all fuels. Economical heat for any size or type of building. Attractive jacket, fully insulated. Ratings: Steam--770 to 9900 sq ft. Water--1230 to 15,840 sq ft installed radiation. 9. WATER TUBE BOILERS For oil or stoker. For medium to large buildings. Ratings: Steam--930 to 4600 sq ft, Water 1640 to 7360 sq ft installed radiation. 1523 American Radiator & Standard Sanitary Corp. Plumbing & Heating Division Gas and Heating Systems wat^Hratm, ' Accessories Ss4*- 1. RADIANTRIM PANELS Replace ordinary baseboards. Cast iron panels provide all the advantages of both convected and radiant heat. For forced hot water or two pipe steam. Sheet metal accessories also available for complete installa tion. 2. HEATRIM PANELS Non-ferrous panels provide con vected heat with forced circulation hot water systems only. Adaptable to mainless or series loop installations. Available in 4, 6 and 8-ft lengths. Two models: Model 75-A Standard, Model 75-B High Capacity. 3. ARCO RADIATORS--Highly efficient, slim tube radiators. Available in four widths--3,4, 5 and 6 tubes--and four heights --19,22, 25 and 32 in. 4. CONVECTORS With cast iron (Arco) or non-ferrous (Mul- tifin) heating elements. Styles and sizes for every need. Special, designs for hospitals, institutions, etc. Multifin Type K (shown) available in 63 packaged stock sizes. 5. SUNRAD RADIATORS Recessed or free-standing. Need no enclosure. Two sizes: 5 in. deep x 20'in. high and 7}4 in. x 23 in. Inlet grilles if desired. . 6. AMERICAN STANDARD WATER HEATER--Approved by A.G.A. Heats water automatically, stores it for instant use. White enameled jacket, gray trim. .Thrifty and depend able. Three sizes--20, 30 and 40 gal. 7. NEW STANFLAME CONVERSION BURNER Gas fired. Vertical, upshot-type burner for boiler, furnace, or winter air conditioner. Fits round or square combustion chamber. Runner pilot igniter. Burns all gases. A.G.A. inputs of 60,000 to 325,000 Btu per hour. 8. ARCOFLAME OIL BURNER--Listed by Underwriters' Lab oratories, Inc. Complies with Commercial Standard CS-75. Special flange types for oil heating units. Pedestal types for conversion. Capacities from 0.70 to 7 gal per hour. 9.-TEMTRIM--Finned tube radiation for schools, hospitals, factories, offices, churches, theaters and similar buildings. For forced hot water and two-pipe steam installations. Available in two sizes: 114 >n- tube with314 in. x 3)4 in. fins or 4)4 in. x 4)4 in. fins, and 2 in. tube with 4)4 in. x 4J4 in. fins; 3)4 in. size fins are spaced 24 and 34 fins per lineal foot; 4)4 in. fins are spaced 28 and 36 fins per foot. Three attractive covers in three tier heights--expanded metal grille, flat top cover, and sloping top enclosure. Heating element fabricated in lengths of 2 to 12 ft in 1-ft increments. Covers and enclosures are available in lengths of 1- to 6-ft in 1-ft increments. I-B-Ii approved. DETROIT HEATING CONTROLS AND ACCESSORIES--A complete line of heating controls and accessories for all types of systems. 1524 American Radiator & Standard Sanitary Corp. Plumbing & Healing Division Heating Systems Air Conditioning and Water Chilling: Package Units 1. VERTICAL REMOTAIRE ROOM CONDITIONER--A remote type unit providing year-round air conditioning for central-plant, multi-room installa tions such as office buildings, apart ments, hotels, schools, hospitals, motels and residences. Features individual room control. Available in 200, 300, 400, and 600 cfm sizes for free standing, partially recessed and fully recessed applications. Uses hot water for heating, chilled water for cooling, both supplied by remotely located water chiller and boiler and us ing the same piping system. Units are listed by Underwriters' Laboratories, Inc. 2. HORIZONTAL REMOTAIRE ROOM CONDITIONER--Similar in operation to Vertical Remotaires. Installed over head either exposed or concealed in a closet, drop ceiling or furred space. Available in four sizes--200, 300,400 and 600 cfm--and three models to meet every architectural requirement. 3. PACKAGED WATER CHILLERMODEL ACS--Central chilled water source for medium and large air condi tioning systems. Complete, packaged units; sizes 7.5, 10,15, 20, 25, 30, 40, 50, 60 and 75 hp. Assembly consists of refrig erant compressor, compressor motor, evaporator, condenser, heat exchangers, controls, piping and framework. Units tested and given a holding charge of refrigerant prior to shipment. 4. PACKAGED WATER CHILLERWATER COOLED--MODEL PAS--Cen tral chilled water source for residential and small commercial air conditioning systems. Hermetically sealed. Available in 2 and 3 hp sizes. Assembly consists of steel framework enclosing a motor-com pressor assembly, condenser and evap orator with connecting tubing, complete with operating charge of Freon-22 and all auxiliary components. 5. PACKAGED WATER CHILLERAIR COOLED--MODEL PAS-AC Com pletely factory-assembled 2 and 3 hp water chillers with air-cooled condenser. For residential and small commercial systems in areas where water is scarce. Has a permanently lubricated and her metically sealed motor-compressor unit containing a 5-year warranty. 4S&&- Heating Systems Boilers, Radiators, Valves, Tanks BOILERS ond RADIATORS Irvington-on-Hudson, N. Y. There's a Burnham for Every Purpose--Write for Descriptive Catalogs :f Burnham BASE-RAY Radiant Baseboard -- Two Sizes, No. 7 and No. 9 (Cast Iron) I*B=R Rating per lineal foot for No. 7 is 2.35 and for No. 9 it is 3.45 per sq ft. Tappings % in. top and bottom. Sections come in 12, 18, and 24 in. lengths. New matching sheet metal baseboard extensions and accessories available. New HOLIDAY Cast-Iron Gas Boiler A.G.A. approved for manufactured, natural, mixed or LP Gases and I=B=R approved and rated for water from 300 to 1100 sq ft; for steam 160 to 610 sq ft sup plied with or without domestic hot water. PACEMAKER Boiler for oil firing. I-B=R Ratings 270 to 710 sq ft for Steam and 490 to 1270 for Water. A cast-iron vertical flue boiler. Can be equipped with tankless or storage type domestic hot water coils. . PACE-PAK Boilers--I=B=R Net 565 sq ft and 810 sq ft for Water. Design same as PACEMAKER. Delivered in one crate ready' for installation with all controls and wiring factory installed for assured performance. . .-. :b -F * f 4 ^i Heating Systems Bo&ers, Sections tAMAMT fifAIJMS ,, ______ . - .#_____ BOILERS and RADIATORS ^ Irvington-on-Hudson, N. Y. - There's a Burnham for Every Purpose--Write for Descriptive Catalogs PACE-KING BOILER A new Burnham Series, exclusively oil fired, for apartment houses, schools, hospitals, commercial installations, etc. Its vertical flue design is engineered similar to -PACEMAKER and PACEPAK . . . low internal draft loss . . . lower stack temperatures . . . lower chimney design ... no baffles used. Provided with tankless hot water heaters with capaci ties from 6 to 10 gpm. Available in 14 models with I=B=R ratings from 1100 to 4500 for Steam and 1925 to 7200 for Water. Built for safety and dependability ac cording to the ASME Construction Code and the I-B-R Rating and Testing Code. PACE-KING SECTIONS are designed with hundreds of efficient fins for fast heat exchange and fuel economy. Can easily be passed through existing door ways. Sections are reversible ... this fea ture also allows wider choice of location since outlet connections and clean out panels can be placed on either side. Boiler can be fired from front or rear. Long wa ter legs provide plenty of room for com bustion. . YELLO-JACKET Boiler (shown with ex tended Jacket). All fuel, convertible. l-B-R Ratings 305 to 935 sq ft for Steam and 490 to 1600 sq ft for Water. BURNHAM RADIANT RADIATORS-- Two heights 20 and 23 in. Ratings 2.25 sq ft per section and 3.40 sq ft per section respectively. BURNHAM SLENDERIZED RADIATORS--Three to six tubes in four heights 19 in. to 32 in. Ratings are from 1.6 sq 11 per section to 3.7 sq ft per section. 1526 ; No. l, 2, 3 and 36 in. Series and 50 in. Twin Series--Famous Burnham 3-times- back-and-forth fire travel; for all fuels. 230 to 14,600 sq ft for Steam; 370 to 23,360 s9 ft for Water. Welded Steel Boiler--Compact type-- Capacities from 2500 to 35,000 sq ft for Steam and 4800 to 50,000 sq ft for Water. Furnished for coal, oil or stoker firing. SBI Rated. 1527 Heating Systems Boilers, Radiators, Furnaces, Heating Accessories Crane Co. BOILERS, BASEBOARD, RADIATORS, FURNACES, AIR CONDI TIONERS, VALVES, FITTINGS, PIPE, WATER AND STEAM SPECIALTIES, CONTROLS AND PLUMBING MATERIALS General Offices: 836 South Michigan Avenue, Chicago 5, Illinois Nationwide Service Through Branches, Wholesalers, Plumbing and Heating Contractors CRANE--A SINGLE SOURCE FOR EVERYTHING IN HOME HEATING Crane Sunnyday 16 Boiler Crane Sunnyday 16 "Senior" Boiler- Burner Unit CRANE SUNNYDAY 15--All-new packaged cast iron boiler saves up to 15 percent on fuel. Nine firetube flues give greater heating surface in 20 per cent less space. Water, oil-fired, net I-B=R rating from 67,000 to 156,000 Btu. ' CRANE SUNNYDAY 16 "SENIOR"--A packaged cast iron boiler for steam or hot water designed for maximum efficiency with oil. Patented Sustained Heat Principle assures fuel economy. Water, net J-B=R rating from 126,000 to 239,000 Btu. CRANE SUNNYDAY 20 "ALL PURPOSE"--Cast iron, completely packaged, all fuel boiler for home or small commercial systems. Design improvements increase boiler efficiency. Water, oil fired, net I=B=R rating from 101,000 to 245,000 Btu. CRANE-LINE STEEL BOILER--A complete line of new, assembled and wired, low-cost boilers. Accessory equipment ana rectangular steel jacket available. Oil or gas. Four sizes. Oil fired, net SB I rating 66,000 to 168,000 Btu per hour. with Oil Burner Crane $1 Boiler Fired Botler Fired Boiler CRANE 30--Ideal medium-size cast iron boiler for larger homes, small commercial buildings. Easy-to-handle sections speed assembly. Water, oil fired, net l^B-R rating 201,000 to 736,000 Btu. .* .. CRANE 41--New all-fuel boiler for institutions and other large buildings. Precision ground cast iron sections easy to assemble. Water, oil fired, net I=B-R rating 622,000 to 1,440,000 Btu. ' . CRANE 2WG--A completely assembled cast iron gas boiler only 33 inches high. Patented "staggered heat travel" fins set up unusual scrubbing action. Water, A.G.A. input 70,000 to 210,000 Btu per hr. ` CRANE 60--Big new 6-inch gas boiler. Patented "staggered heat" travel surfaces capture all liberated heat. Steam, hot water, or large volume indirect water heating. Net A.G.A. ratings from 625,000 to 5,000,000 Btu input. VALVES--FITTINGS--The complete Crane line of valves and fittings offers all neces sary piping items for any heating system. 1528 Crane Co. Heating Systems* &g^SLPor"c"- Compac Radiators Type F (fabricated) Type RC (cast iron) Type tt {cast iron) CRANE RADIANT BASEBOARD introduces an even distribution of radiant warmth at floor level, leaving entire floor area free from obstruction. If baseboard area is limited, Type R panels may be installed vertically or at ceiling level. Type RC pro vides radiant and convected heat. Type R provides radiant heat only. CRANE COMPAC RADIATORS--Slender lines give pleasing modern appearance, require minimum space without sacrificing heat output. For free-standing or recessed installation, steam or hot water. Sizes up to 111 sq ft output I-B^R rated. WATER SPECIALTIES--available to suit every installation--including water heaters, circulators and flow control valves. CRANE OIL BURNERS are newly en gineered to provide automatic heating comfort at low fuel cost with a minimum of maintenance. GAS BURNERS feature "Spreader Flame" principle of construction and operation that eliminates-Josses due to incomplete combustion or excess air. Crane Counterflow Furnace Horizontal gas-fired furnace CRANE-LINE COUNTERFLOW FURNACE requires as little as 2} Sq ft of floor space with 1 in. clearance on sides, rear, top. Gas fired: five sizes, 65,000 to 140 000 Btu input. Oil fired: three sizes, 84,000 to 123,000 Btu at Bonnet. ' CRANE-LINE HORIZONTAL FURNACE can be suspended in crawl space, from basement ceiling, or installed in an attic. Gas fired: two sizes, 65,000 to 85 000 Btu input. Oil fired: four sizes, 84,000 to 224,000 Btu at Bonnet. ' CRANE-LINE BASEMENT OIL-FIRED FURNACE is a winter air-conditioning unit that heats, filters and provides forced circulation of heated air to all rooms. Gas hred: nine sizes, 70,000 to 250,000 Btu input. Oil fired :`seven sizes 84 000 to 224,000 Btu at Bonnet. w_*_. CRANE HI-BOY AND COUNTERFLOW YEAR 'ROUND AIR CONDITIONER Available in both water cooled and air cooled models. Two, three, and five-ton cooling capacities, with gas or oil-fired furnace. ADD-ON AIR CONDITIONER UNIT-- Converts any warm air heating system to year 'round use. Available in watercooled models (2, 3 or 5-ton capacity) or air-cooled models (2 or 3-ton capacity). Charged with refrigerant and sealed at the factory, so you need no refrigeration Crane HI-BOY Year serviceman when you make your installa- cnm'AXT Crane-Line Add-on Air Conditioner Unit 1529 Heating Systems 55So2SSSS -National U. S. Radiator C O R P O R AT I O N HEATING AND AIR CONDITIONING DIVISION General Offices: Johnstown, Pa. Cast Iron and Steel Boilers Baseboard Convectors Radiators Fintube Unit Heaters Furnaces Oil and Gas Burners Air Conditioning Accessories Nationwide distribution through Branches. Wholesalers, Plumbing and Heating Contractors NATIONAL-U. S. ALL-FUELS BOILERS (CAST IRON) Designed especially to meet the special requirements of automatic firing . . . rugged cast iron construction. Provided with many features to insure high operat ing efficiency and maximum fuel econ omy. Convertible to any fuel or method of firing. Wide range of both storage and tankless water heaters available. "27" Series . . . for medium to large size residential installations available in six sizes'. Net Steam Ratings from 350 to 880 sq ft, and Net Water Ratings from "7" Series "47" Series 560 to 1560 sq ft. "37" Series . . . for large residential and small commercial installations . . . available in nine sizes: Net Steam Rat ings from 700 to 2300 sq ft, and Net Water Ratings from 1120 to 3835 sq ft." "47" Series . . . for commercial, indus trial and institutional installations . . . available in eight sizes: Net Steam Rat ings from 2500 to 6000 sq ft, and Net Water Ratings from 4000 to 9600 sq ft. NATIONAL-U. S. OIL HEATING BOILERS AND UNITS (CAST IRON) Developed specifically for oil firing . . . the Oil Heating Units comprise a cast iron boiler, dependable oil burner, pre cast combustion chamber and high qual ity controls. Oil Heating Boilers are de signed for top performance with any oil burner. A wide range of both storage and tankless water heaters is available with "57" Series "10" Series all Units and Boilers. "10" Series ... an economical wet base Boiler and Unit for installation in small and medium size residences . . . available in five sizes: Net Steam Rat ings from 230 to 500 sq ft, and Net Water Ratings from 430 to 910 sq ft. "12W" Series . .,. priced low and styled right for installation in the small to medium size home . . . wet base de sign . . . available in four sizes: Net Water Ratings from 430 to 855 sq ft. "12" Series ... a popular wet base Boiler and Unit for the small to medium "ltW" Series (with Flush size home. Available in four sizes: Net "if" Series (with Enclosing Jacket) Steam Ratings from 230 to 470 sq ft, and Jacket) Net Water Ratings from 430 to 855 sq ft. 1530 National-U. S. Radiator Corporation Heating Systems oif&Gas 11SO" Series "20" Series ... a larger wet base Oil Heating Boiler for residential installa tions . . . available in four sizes: Net Steam Ratings from 340 to 780 sq ft, and Net Water Ratings from 625 to 1370 sq ft. "25" Series ... a high capacity Oil Heating Boiler . . . wet base construc tion for residential, commercial and in dustrial installations . . . available in five sizes: Net Steam Ratings from 545 to 1985 sq ft, and Net Water Ratings from 985 to 3355 sq ft. "37" Series . . . for large residential and small commercial installations . . . available in nine sizes: Net Steam Rat ings from 700 to 2300 sq ft, and Net Water Ratings from 1255 to 3835 sq ft. "46" Series . . . Boiler and Unit of special design for medium to large size residential installations . . . available in four sizes: Net Steam Ratings from 310 to 700 sq ft, and Net Water Ratings from 570 to 1255 sq ft. "46" Series NATIONAL-U. S. GAS BOILERS National-U. S. Gas Boilers are mod ernly styled, compact and designed ex clusively for gas firing. Cast iron sections for long life, effective gas travel, de pendable controls and many other fea ture-advantages contribute to efficient and economical operation . . . .A.G.A approved for all gases. "11B" Series ... a factory-assembled packaged boiler, economically priced . .. for small to medium size homes . . . available in seven sizes: Net Water Rat ings from 185 to 725 sq ft. "llB" Series "16B" Series . . . dependable, efficient gas heating for residential and small commercial installations . . . can be equipped with water heater . . . avail able in twelve sizes: Net Steam Ratings from 295 to 2090 sq ft, and Net Water Ratings from 545 to 3510 sq ft. "22," "33" and "44" Series . . . taper ing zig-zag flue passages extract maxi mum heat-save fuel ... to meet heating requirements of small residences up to commercial and industrial structures . .. available in twenty-one sizes: Net Steam Ratings from 110 to 1920 sq ft, and Net Water Ratings from 205 to 3245 sq ft. "66" Series . . . National-U. S. gas heating comfort for larger apartments, stores, hotels, hospitals, schools and other large installations . . . available in eighteen sizes: Net Steam Ratings from "it", "ss" and "44" Series 1770 to 12950 sq ft, and Net Water Rat ings from 3005 to 20720 sq ft. 1531 "25" Series "37" Series "16B" Series "66" Series National-U. S. Radiator Corporation Heating Systems hSiS,Erectors 17 and $4 in. Series 41 in. Series NATIONAL-U. S. STEEL BOILERS National-U. S. Steel Boilers meet all the requirements of the SBI Testing and Rating Code and the ASME Boiler Construction Code. All are inspected and approved at the factory by a representa tive of a boiler insurance company. 17 and 24 in. Series . . . available as a Boiler or as a complete Oil Heating Unit--suited for small and medium size residential installations . . . available in four sizes: Net Steam Ratings from 320 to 700 sq ft, and Net Water Ratings from 580 to 1260 sq ft. 26, 29 and 39 in. Series . . . can be furnished as a Boiler or as a complete Oil Heating Unit for installation in medium residential to small commercial buildings . . . available in nine sizes: Net Steam Ratings from 700 to 3000 sq ft, and Net Water Ratings from 1260 to 5400 sq ft. 41 in. Series ... a modern automatic heating boiler... for firing with oil burner, gas burner or stoker in commer cial, institutional and commercial in stallations. . . available in four sizes: N et Steam Ratings from 3500 to 5000 sq ft, and Net Water Ratings from 6300 to 9000 sq ft. Commercial Series . . . adaptable to either automatic or hand firing for the very largest installations . . . available in sixteen sizes: Net Steam Ratings from 2500 to 35000 sq ft, and Net Water Rat ings from 4000 to 56000 sq ft. . 26, 29 and 69 in. Series Commercial Seriesl NATIONAL-U. S. PACKETS Compact, all-in-one, factory-assem bled automatic oil or gas fired home heat ing Units for small installations. An in tegral tankless or storage heater provides domestic hot water. Furnished with either flush or enclosing jacket. Net Wa ter Ratings: for gas--460 to 520 sq ft, for oil--495 to 580 sq ft. The Packet, combined with National- U. S. Baseboard, provides a modern, low-cost, easy-to-install forced hot water heating system for homes, motels, diners Model U Packet (with Flush j +ZZ? Jacket) and stores. NATIONAL-U. S. CONVECTORS Aero Convector Art Convector . . . ^ non-ferrous con vector for flush and send or full-recessed installations. Aluminum fins bonded to copper'tubing comprise the heating ele ment. Enclosures are made in a variety of types for residential or commercial in stallations. . Aero Convector . . . heating element is made of cast iron with fins cast integral with tubes. Adaptable to any type of hot water or steam heating system. Numer ous types of enclosures can be furnished for residential or commercial installa tions. Model K Packet (with Enclosing Jacket) Art Convector 1532 1 & >. '> ->c -V 'M j r;> .'4i *4 1 Baseboard, Radiators, Con* National-U.S. Radiator Corporation Heating Systems* TiTI-^ces NATIONAL-U. S. BASEBOARD HEAT DISTRIBUTING UNITS ~~ Three types of baseboard can be furnished: Art (non-ferrous). Radiant (cast iron), and steel ... all combine the best features of radiant and convected heating--radiant heat at floor level and convected heat to banish drafts. For new Art Baseboard or old buildings--residential or commeron-ftT,ou`) cial. Ideal for remodeling old homes, and for basementless homes. NATIONAL-U. S. RADIATORS Sunray Radiators . . . modern cast iron radiation for recessed or free-stand ing installations . . . available in 19, 20, 21 and 22^ in. heights . . . piping can be completely concealed by grilles. Thin Tube Radiators. Compact, slen der tube cast iron construction. Blend inconspicuously with most decorative schemes. Efficient and quick heating. National-U. S. Unit Heaters for hot water and steam, also for gas firing-- . both types in a wide range of sizes. National-U. S. Fintube Radiation . . . ideal where heating requirements are heavy and space limited. Available in two types: steel tubing with steel fins and copper tubing with aluminum fins. Slop ing top, flat top and expanded metal grille covers can be furnished. National-U. S. Oil Burners and Gas Burners are available in a number of sizes for conversion of either boilers or warm air furnaces to automatic firing. Radiant Baseboard (Cast Iron) jiSI Thin Tube Radiator Conversion Oil Burner Conversion Gas Burner CAPITOLAIRE AIR CONDITIONING AND WARM AIR FURNACES 1. Hi-Boy Series available for all fuels. Output: from 65,000 to 100,000 Btu/hr. 2. Lo-Boy Series available for all fuels. Output: from 68,000 to 160,000 Btu/hr. 3. Horizontal Series available for gas and oil firing. Output: from 48,000 to 180,000 Btu/hr. 4. Hi-Cap Series available for all fuels. Output: from 330,000 to 1,000,000 Btu/hr. 5. Suspended Air Conditioner, Model HRZ recessed with deluxe cabinet. Can be furnished with cabinet for duct mount ing. Range from 300 cfm to 1750 cfm. Floor Model, Fan Coil Unit, freestanding and concealed, Model VER, 1. and l^ton. Packaged Chillers, water and air cooled condensers, 2 and 3 ton units (not shown). 6. Self-contained Hi-Boy, model COM . . . range from 2 to 15 ton. 7. Residential Packaged Air Condi tioner, air cooled (remote) and water cooled condenser. Range from 2 to 6 ton. Self-contained Hi-Boy, model US-AEC with built-in evaporative condenser . . . range from 3 to 60 ton. (Not shown). 5. 1533 Heating Systems 1ST' DIVISION National-U. S. Radiator Corporation Johnstown, Pennsylvania Sales Offices In Principal Cities Pacific Standard Firebox Boiler* Pacific Scotch Marine Boiler* Pacific Front Smoke Outlet Boiler* Pacific Split-Firebox Boiler* SBI TABLE 1 BOILERS A Complete Line of Low-Pressure Steel Heating Boilers For Commercial Application All Pacific Commercial Boilers are built using the ASME Boiler Code Stand-, ards as minimnms, and rated in ac cordance with Steel Boiler Institute code. PACIFIC STANDARD FIREBOX BOILERS Pacific Standard Firebox Boilers for mechanical firing, stoker, oil or gas are built in capacities of 2680 to 56830 sq ft for steam and in corresponding capacities for water. Design is of two types: Low Water Line and High Firebox. Pacific Direct Draft and Smokeless Boilers for coal firing are built in capac ities of 2200 to 35000 sq ft for steam and in corresponding capacities for water. PACIFIC SCOTCH MARINE _ BOILERS Pacific Scotch Marine Boilers for oil or gas firing. Capacities of 5470 to 42500 6q ft SBI rating steam and in cor responding capacities for water. Fully Wet Back. PACIFIC FRONT SMOKE OUTLET BOILERS Pacific Front Smoke Outlet Boilers for hand, stoker, oil or gas firing are built in capacities of 4000 to 42500 sq ft for steam and in corresponding capacities for water. PACIFIC SPLIT-FIREBOX BOILERS Low Water Line and High Firebox of Pacific Boilers are built in three sections --shell, firebox and base--and require minimum building opening. Where neces sary, Pacific fireboxes can be split (as illustrated) to allow the boiler to be taken into the building in four sections, through any ordinary door or window. No cutting, no welding is required in assembling any Pacific Boiler. Descriptive bulletins on Pacific Commercial Boilers will be mailed on request 1534 Heating Systems *r/accu: DIVISION National-U. S. Radiator Corporation Johnstown, Pennsylvania Sales Offices in Principal Cities SBI TABLE 2 BOILERS A Complete Line of Residential Steel Boilers for Coal, Stoker, Oil or Gas Firing All Pacific Residential Boilers are built using the ASME Code Standards as minimums, and are rated in accordance with Steel Boiler Institute code. MENCR U S off. PACIFIC "ELATE FLUE" BOILERS Pacific "Plate Flue" Boilers are designed for oil or gas firing and are__built in 4 sizes. Capacities range from 9600 to 216.000 Btu/Hr steam and from 108,000 to 243,000 Btu/Hr water. They are avail able with either flush or extended jackets. Pacific "Plate Flue1* Boilcre PACIFIC "O" SERIES BOILERS Pacific "O" Series Boilers for residential application are designed for steam or water and for either automatic oil or gas firing. They are built in 7 sizes with capacities from 264,000 to 720,000 Btu/ hr steam and from 297,000 to 810,000 Btu/hr water. Available with flush jacket. (4 Pacific "On Series Boilers PACIFIC SERIES 700 BOILERS Pacific Series 700 Boilers are designed for steam or water and for either stoker or hand firing. Capacities range from 194.000 to 595,000 Btu/hr steam and from 219,000 to 670,000 Btu/hr water for hand fired models. Stoker fired models have capacities from 264,000 to 720.000 Btu/hr steam and from 297,000 to 810,000 Btu/hr water. All series 700 Boilers available with flush jacket. PACIFIC SERIES 33 BOILERS Pacific Series 33 Boilers are designed for oil, gas- and stoker firing. Capacities range from 840,000 to 1,200,000 Btu/hr steam and from 945,000 to 1,350,000 Btu/ hr water. Available with flush jacket. Descriptive bulletins on Pacific Residential Boilers will be mailed on request 1535 Pacific Series SS Boilere -1 i Heating Systems Boilers Cast Iron Frank Prox Company, Inc. Office and plant . 1201 So. First St. Terre Haute, Ind. PROX BOILERS For Large Installations in Schools, Theatres, Apartments, Churches, Hospitals, Hotels, Etc. Write for complete catalog. The 40 Series DUPLEX ECONOMIC BOILERS FOR STOKER, OIL, OR GAS Swinging connections! No vibration! No pulsation! Plenty of room for stoker, oil burner, or gas conversion burner! No iron to iron joints! Expansion and contraction troubles eliminated! The 40 Sm'ea--50-inch Water Line. The fire travel is in three successive layers--full length of the boiler three times. Rotating action of hot gases in evenly shaped flues greatly increases effective heat absorbing capacity of the large heating surfaces. Independent connections to each indi vidual section. Each section is a separate boiler with outside, accessible con nections. No shut-downs. Guarantees service since any section can be plugged off and firing continued. STEAM BOILER Boiler No. 040--S 6 040--S 7 040--S 8 040--S 9 040--S 10 040--S 11 040--6 12 040--S 13 040--S 14 040--S 15 040--S 16 Rating Feet (Net) 2700 3200 3700 4200 4700 5200 5700 6200 6700 7200 7700 WATER BOILER Boiler No. 040--W 6 040--W 7 040--W 8 040--W 9 040--W 10 040--W 11 040--W 12 040--W 13 040--W 14 040--\V 15 040--W 16 Rating Feet (Net) 4100 5100 5900 6700 7600 8300 9400 10200 11000 11800 12700 1536 Hydrostatically Tested ASMB Standard Maximum Allowable Working Pressure Furnace Vol Oil Delivery Coal Delivery ume cu ft Rate Rate Above base Gals Per Hr Lbs Per Hr 15.8 20.0 24.3 28.6 32.9 36.1 39.4 44.3 7.4 8.8 10.2 11.6 13.0 16.8 17.2 103 114 113 219 48.6 51.0 55.3 18.6 20.0 21.4 Heating Systems Boners, cast-iron The H. B. Smith Company, Inc. Westfield, Mass. Broach Offices and Soles Representatives in Principal Cities A complete line of modern cast Iron sectional boilers for residential, commercial and Industrial heating and for domestic hot water supply. SMITH "CENTURY" GAS BOILER, A.G.A. approved, for steam or hot water heating. Input ratings from 138,000 to 745,500 Btu. Combines latest features of gas boiler design. Available with five sizes of built-in tank domestic hot water heaters, capacities to 168 gal, and eight sizes of tankless heaters, capacities to 8 gpm. Entire burner assembly mounted on wrought iron frame with casters for easy removal. 4 ' TOO" and "2000" OIL BOILER. BURNER steam or water units for homes and small commercial installa tions. Furnished with line of tankless heaters with capacities up to 8 gal of hot water per minute. Net radiation to 1275 sq ft, steam; 2210 sq ft, water. SMITH-MILLS BOILERS, Series 15-20-25; capacities 200 to 2275 sq ft steam radiation. This complete line of modem push nipple boilers is available in models for gas, oil, stoker or hand firing. Have provisions for built-in domestic hot water heaters and controls. MILLS WATER TUBE BOILERS, Series 24-34-44; capaci ties 900 to 13,380 sq ft steam radiation. Independent header type construction. Tens of thousands are installed in schools, hospitals, apartment houses, stores and other commercial and public buildings. Models for hand and all types of automatic firing. SMITH HY-TEST BOILERS for hot water supply are furnished in several models, and many sizes for tank capaci ties to 20,000 gal. Constructed of the finest quality grey iron castings, these Hy-Test units are carefully tested at ex tremely high pressures before shipment. 42 and 60 SMITH BOILERS, may be used in batteries for Cheating loads up to and over 100,000 sq ft steam radiation. Many of these large units installed in industrial plants furnish steam for processing requirements as well as for heating and domestic hot water. STERLING FIN-TYPE RADIATORS for low-cost heat in public and commercial buildings, and baseboard convectors for homes, are distributed nationally by The H. B. SMITH COMPANY, Westfield, Mass. Complete catalog information describing Smith boilers Is filed In current Issues of Sweet's "Architectural" and Domestic Engineering Catalog Directory. 1537 Heating Systems Boflere, cast-iron Spencer Heater Heating Systems Boners, steel SPENCER H EATE R LYCOMING DIVISION PEN NS'*'-''I** Sales Representatives Allentown, Pa. Cincinnati, Ohio Harrisburg, Pa. Minneapolis, Minn. Portland, Ore. Atlanta, Ga. Cleveland, Ohio Houston, Texas Nashville, Tenn. Richmond, Va. - Baltiuobe, Md. Columbus, Ohio Indianapolis, Ind. New Haven, Conn. Rockford, III. Binghamton, N. Y. Dallas, Texas Kansas Citt, Mo. New York, N. Y. San Antonio, Texas Birmingham, Ala. .Detroit, Mich. Knoxville, Tenn. Philadelphia, Pa. Seattle, Wash. Boston, Mass. Grand Rapids, Mich. Memphis, Tenn. Pittsburgh, Pa. Spokane, Wash. Chicago, III. C. D. C.Greensboro, N. Milwaukee, Wis. Pocatello, Idaho Washington, STEEL AND CAST IRON HEATING BOILERS FOR EVERY BUILDING . . . FOR EVERY FUEL "l.W``,4," "C," and "R Series fully approved by Steel Boiler Institute X i sa A M : 4J f All products manufactured in strict accordance with the ASME code and carry the code seal. Every Spencer meets rated specifications, is easy to install, and assures economical operation. 3,500 TO 42,500 SQUARE FEET, STEAM Steel Commercial Heating Boilers.--Exelusive peaked firebox design aids in making the "A" Boiler quick steaming and efficient. Space for either storage tank or instantaneous type service water coils. Larger sizes can be cut in half to . move through narrow openings. "A" Series 1,300 to 5,000 NET SBI STEAM Steel Commercial and Residential Heat ing Boilers--For oil burner, stoker, or hand firing. With heavy-duty doors and frame precision-ground for airtight fit. Adaptable to front, rear, or side in stallation of oil burner or stoker. Avail able with domestic hot water coils and attractive insulated jacket. 1538 'C* Series i 'ip iiM "LW" SERIES--3,500 to 42,500 SQUARE FEET, STEAM. New Divided LowWaterline Commercial Boiler Flattened out to beat low headroom and excavation problems. Divided for easier entrance through narrow basement openings, yet 2 watertight sec tions require no welding. Easier to install because of specially designed smokebox.' Low stack designs possible because boilers designed to be installed with induced draft fans. Both Instantaneous or tank type service waterheating coils. Quickly convertible from mechanical to hand-firing. "R" SERIES--320 to 1,100 SQUARE FEET, STEAM, NET LOAD Steel Residential Heating Boilers---Excellent for small homes requiring economical heat and instantaneous hot water. Available with attractive beauty jacket. SUBURBAN 87,000 BTU NET SBI WATER RATING Oil Fired Boiler Burner Kitchen appliance beauty fits in any where. Quickly installed in minimum floor space, no special base required. Extra-high combustion chamber assures quiet, trouble-free operation. Easily cleaned and serviced. Suburban RANCHER 1G SERIES: 40,000 TO 128,000 BTU 2G SERIES: 80,000 TO 232,000 BTU Gas-Fired Boiler Burner Extremely compact and efficient. A. G. A. -approved for manufactured, mixed or natural gases. Ease of installa tion, cleaning and service saves time and money. Gleaming white kitchen appli ance beauty. 1539 Rancher Heating Systems . n UlEll-llkUUN COmPANY General Sales Office: Michigan City, Indiana Distributors in all principal cities WEIL-McLAIN CAST IRON OIL-FIRED BOILERS HR Series Heavy Duty boilers for hori zontal rotary burners Special steel front plate and section sim plify rotary burner installation. Large fire box volume develops better combus tion conditions--high base eliminates high brick foundation. These boilers are also available as-all-fuel units. Load range: steam 2,700-12,270 sq ft; water 4,450-19,630 sq ft. BOILER FOR OIL AND OIL HEATING UNITS Designed specifically for efficient oil burning. Long flue travel extracts maxi mum heat. 1-B-R. rated, ASME con structed. Available in residential sizes as complete package units for forced hot water systems. Load range: Steam 285-3,400 sq ft; water 525-5,505 sq ft. WEIL-McLAIN CAST IRON GAS-FIRED BOILERS A complete line of jacketed gas-fired boilers for residential, commercial and industrial applications. Cast iron construction for long life. Special design features assure efficient fuel com bustion--longer fire travel through finned flues permits maxi mum heat absorption. A.G.A. approved for natural, mixed, manufactured or liquefied petroleum gases--ASME construc ted. . Load range: steam 260-12,950 sq ft; water 300-20,720 sq ft. Type J Gas Boiler Weil-McLain .Snug Cast Iron Baseboards and Radiation Snug Baseboard Panel Snug Cast Iron Baseboard Panels provide a balanced combina tion of radiant convected heat which assures uniform tempera ture from floor to ceiling. Available in two heights--734 in. x 23 in. and 9% in. x 2J4 in. Complete line of metal finishing accessories. Solray Cabinet Radiators have attractive, easily cleaned cabinet top. Large wa terways store heat for release when burner shuts off. Raydiant Recessed Radiators are designed exclusively for recessing virtually flush in the wall--completely unobtrusive. Junior Radiators offer modern slender-tube design--can be installed in open recess if desired. 1540 Heating Systems Boiler Burner Aldrich Company 121 E. Williams St., Wyoming, Illinois Boiler-Burner Units, Domestic and Commercial Oil Burners Aldrich Boiler-Burners are available in sizes for hot water heating, steam heat ing and hot water supply. Heavy duty double spiral hot water coils factory installed and tested in SC and WC models. Matched Aldrich Oil Burner with each unit, or choice of gas fired models. Welded steel fire box lined with re fractory of high deterioration resistance. Extra thick wool insulation minimizes heat loss. Easy access to fire box. ALDRICH GULF STREAM BOILERBURNER PACKAGE--Five sizes of com pact, economical units designed for the small home, fully erected, wired, equipped. From 495 to 1260 sq ft of water radiation. Quick heating load pick-up means fuel saving. Efficient and econom ical in operation. Tankless hot water coil optional. SEMES "B" BOILER BURNER SPECIFICATIONS tiise of Boiler Bantam 118 160 225 315 514 808 Rating Sq Ft Hot Water 660 750 1,000 1,500 2,100 3,300 5,000 Rating Sq Ft Hot Water Standing Radiation... 440 500 650 1,000 1,400 2,200 3,333 Rating Sq Ft Steam 425 500 630 935 1,275 2,025 3,000 Rating Sq Ft Steam Standing Radiation ... 285 333 420 620 850 1,350 2,000 Rating Btu Per Hr (Max) 100,000 118,000 160,000 225,000 315,000 514,000 808,000 Water Heater Delivery GPH @ 100 Rise.... Storage Capacity Gal 93 125 190 2S0 H25 610 850 Ions................................ 20 28 38.5 72 99 120 170 Firing Rate--GPH Maxi mum.............................. Firing Rate--GPH Mini 1,00 1.25 1.65 2.75 3.65 5.7 9.00 mum............................... Firing Rate--GPH Bet Model Burner Furnished Sq Ft of Heating Surface Dia. Main Shell (Inside) Height of Main Shell... Dia. of Fire Box (Inside) Height of Fire Box....... Number of Tubes......... Length of Tubes. . Output Hot Water WC- .65 .75 CXI 17 mi' mv 12* 21* 16 1556' .75 1.00 SAX1 21 19* 46)$' 14)4' 24' 16 15H' 1.25 1.35 SAX2 27 21' 50)$' 16' 24' 20 19)4' 1.75 2.00 SAX3 44 24H' 58 W 19* 26' 30 23H' 2.4 2.5 SAX3 67 28' 66)$' 22)$' 26' 42 30H' 3.7 4.5 DX 93 32' 66)$' 27' 26' 60 29H* 6.00 7.5 DX 136 38' 70)$' 32)$' 26' 94 31*i* Coil @ lCK)0 Rise SC-GPM 3 1.75 2.00 2.66 5.25 6.50 7.25 3 2.00 2.75 3.67 6.75 8.00 10.00 GULF STREAM PACKAGE SPECIFICATIONS Boiler No. Net Rating SB I Water Sq Ft ........... Net Rating SBI Btu Per Hour....... Oil Firing Rate GPH.......................... Output Tankless Coil GPM (FHA).. Water Heater Delivery GPH--100 rise____ Storage Capacity of Boiler--Gallons. Heating Surface Sq Ft. . . Number of Tubes. C-10 495 74,000 1.00 3 104 19 16 20 C-12 580 87,000 1.10 3 121 23 19 20 C-14 720 108.000 1.35 3 C-20 995 149,000 2.00 4 C-25 1,260 189.000 2.50 4 151 207 265 29 31 39 . 24 32 41 20 32 32 1541 Gulf Stream Packages Heating Systems Boilers steel The Babcock & Wilcox Co. 161 East 42nd Street, New York 17, N. Y. Offices in All Principal Cities - Water-tube Boilers for Stationary Power Plants, and Marine Services. . .Super heaters .. . Economizers . . . Air Heaters . . . Pulverized-Coal Equipment. . . Chain .Grate Stokers. . .Oil, Gas, and Multifuel Burners. . .Seamless and Welded Tubing and Pipe. . .Refractories. . .Process Equipment. Heating Systems Boilers, Gas and Oil Bryan Steam Corporation Chili Pike, Peru, Indiana Hot Water and Steam Boilers designed exclusively for oil or gas firing. Products include domestic hot water or vapor steam boilers, commercial low pressure heat ing boilers for hot water or steam, and high pressure boilers up to 50 hp nest of tubes directly over the flame where heat is most intense. These tubes break up the path of heat travel, re ducing "surface film" to a minimum. Of the many advantages of Bryan Boilers, none is more important than the use of Copper Tubes for the heating surface. All gas fired heating boilers A.G.A. approved. B&W INTEGRAL-FURNACE BOILER, TYPE FM Shop-Assembled Steam Generator B&W Type FM Boiler combines the supervision. A large part of the total benefits of package steam with cost FM capacity now in service or on order saving big-boiler advantages. This consists of multiple-unit installations. compact self-contained unit has been widely applied to heating services in hospitals, schools, colleges, and other buildings. It has also gained wide ac ceptance throughout a broad range of industries--supplying steam for combi nation services. The Type FM Boiler is fast steaming and features automatic operation with special safety provisions. It quickly responds to load changes and operates at high efficiency over the load range. This versatile unit burns gas and/or oil, separately or in combination, with quick The Type FM Boiler is particularly and easy changeover accomplished at suitable for small- and medium-sized the control panel. plants where excessive fuel consumption and costly maintenance are often serious problems. And, even for some larger steam requirements, multiple-unit Type FM installations have proved more flexible in operation and more economical The Type FM Boiler is available in standard sizes for steam requirements to 40,000 lb per hr and for operating pres sures to 235 psi. Many have been in stalled for higher pressures and with a moderate degree of superheat. Details are than one or more large boilers requiring given in Bulletin G-76--copies sent on costly field erection and close operating request. . 1542 Bryan Copper Tube Boilers are engi neered expressly for oil or gas firing, where the flame is either on at full inten sity or entirely off. Such combustion characteristics call for a boiler that is able to capture heat units with utmost rapidity--and able to withstand sudden expansion and contraction. Average stack temperature of the Bryan is 412 degrees. Doniestic Boilers Commercial Heating Boilers Sigh Pressure Boilers DOMESTIC BOILERS The Bryan Domestic Boiler is avail able in 7 sizes for hot water radiation. 70,000 Btu's to 560,000 Btu *s. For steam radiation 5 sizes are avail able, 390 to 1560 sq ft of radiation. All models come complete with built-in combustion chamber and flange mounted oil burners. In gas fired models the burner is built in. COMMERCIAL HEATING BOILERS Any of the domestic Bryans may be used for small offices or buildings; but they are supplemented with three additional larger capacity boilers. These boilers are rated 2600 to 5000 sq ft of steam radia tion or 4150 to 8000 sq ft of hot water radiation. They are used also for supply ing hot water or low pressure steam in industrial applications. BRYAN COPPER TUBES The Bryan starts with copper tubes. Copper has a coefficient of heat transfer approximately 6 times that of iron or steel. Heat applied to a Bryan tube is therefore transferred to the water inside 6 times as fast. The design of the Bryan tube is such that water circulates rapidly through all parts of the boiler. There is a veritable HIGH PRESSURE BOILERS Bryan High Pressure Boilers are made 5-10-20-35- and 50 hp ratings. Every one carries the ASME stamp. They are made for high efficiency on long, hard pulls but are exceptionally useful in operations requiring fast, safe steam on short notice. Hospitals, dry cleaning plants, laundries, milk plants, tire repair shops and many others find them ideal for their operations. 1543 Heating Systems Boilers, steel Gleaver-Brooks Company 498 E. Keefe Ave., Milwaukee 12, Wisconsin Cleaver-Brooks BOILERS--Steam or Hot Water, for Heating and Processing 15 to 600 hp, 15 to 250 psi. Oil, Gas, and Combination Oil & Gas Fired Models COMPLETE SELF-CONTAINED STANDARD SIZES HP Approx. Rated Capacity--lbs Steam -t'er 15 20 30 40 515 690 1050 1380 50 60 1725 2070 Hour 212 F. 125 150 200 250 300 350 Approx. Rated Capacity--lbs Steam Per 4300 5200 6900 8600 110500 12000 Hour 212 F. 70 2415 400 13800 80 2760 500 17000 CLEAVER-BROOKS BOILERS OPERATE AT A GUARANTEED MINIMUM 80 PER CENT EFFICIENCY 100 3450 600 20700 Cleaver-Brooks boilers are guaranteed to operate at fuel-to-steam efficiency of not less than 80 per cent, at ratings from 30 to 100 per cent and at the designated working Dressure Economical operation is assured by establishing an efficient flame, and utilizing forced draft to send the hot gases through four successive passes, thus ab sorbing maximum usable heat before combustion gases leave the boiler. Boilers are fully automatic in operation ... meet ASMS code requirements. Factory finished and tested under load conditions. 80 PER CENT EFFICIENCY RATINGS are estab lished at the factory and can be maintained with relative ease after installation. Available with "tO-Secani" Oil and Gas Fuel Interchange Feature Write for complete Spec ifications, dimensions data, firing rates, etc. Catalog AD-187 sent on request. CLEAVER-BROOKS HELPS YOU SELECT THE EXACT STEAM BOILER YOU WANT TO MEET YOUR SPECIFIC NEEDS JOB RATED--Each Cleaver-Brooks steam boiler is job rated to meet the steam requirements of your plant. A competent sales engineer helps analyze your load de mands and takes into account these conditions: Pop valve settings Per cent of total feed water returned as condensate Tem perature of condensate Pressure of make-up water Type of fuel available Electric current characteristics Space and machinery arrangement. Suggested boiler room, layouts Plant altitude above sea level Maximum steam require ments in pounds per hour or boiler horsepower Whether your steam load is con stant or fluctuating, and the degree of fluctuation The. heating load requirements Standby requirements Steam pressure required at point of use Future growth or expansion of plant facilities Look for the "CLEAVER-BROOKS" listing in the Boiler Section of your classified Telephone Directory for name of nearest distributor. 1544 Heating Systems Boilers Steel Cyclotherm Division National-U. S. Radiator Corporation Sales and Executive Offices Oswego, New York Factory Distributors throughout the United States CYCLOTHERM STEAM AND HOT WATER GENERATORS ... operate on Cyclonic Combustion prin ciple. Completely automatic with full safety controls. Oil, gas or interchange able gas and oil firing. Only four con nections required. The Cyclonic Combustion operating principle causes the fuel to be burned while spiraling at high velocity around the inside wall of the combustion chamber, forming virtually a tube of flame. This provides uniform and highly efficient heat transfer over the entire furnace wall without hot spots. Com plete utilization of heat transfer areas provides quick heat as well as greater than 80 per cent efficiency with the re duced maintenance of a two-pass design. 18 to 80 hp models are equipped with "on-off" control; 100 to 500 hp models have modulated control. 80 hp units with modulating controls furnished at customers request. Automatic combus tion safeguard, low water and other safety controls are included. Size, from IS to 500 hp Pressure Range Available in standard low pressure units or high pressures up to 200 psi. Hot water generators are also available in all sizes. Standard Burner Arrangements ' Fuel Cyclotherm Model No. Light Oil, 1 to 3 C-600 thru C-17,500 Gas, mfd., mixed and natural C-600 thru C-17,500 Comb. It. oil and gas C-600 thru C-17,500 Heavy Oil, 5, 6 and Bunker C C-2800 thru C-17,500 Comb. hy. oil and gas C-2800 thru C-17,500 Model No. STANDARD RATINGS AND"DIMENSIONS Max. hp Output Btu Rating Per Hour 18 803,000 30 1,005,000 40 1,340,000 50 1,675,000 60 2,010.000 80 2,680.000 100 3.350.000 125 4.187.500 150 5,025.000 200 6,700.000 250 8.375,000 3UU 10,050,000 350 11.725,000 400 13.400,000 500 16,760,000 Steam Units Steam Per Hr (Lbs) 620 1,035 1,380 1,725 2,070 2,760 3,450 4,315 5,175 6,800 8,625 10,350 12,075 13,800 17,250 Equiva lent Di rect Radi ation (Sq Ft) 2,513 4,188 - 5,583 6,980 8,375 11,167 13,959 17,448 20,938 27,917 34,836 41,975 48,854 55,833 69,792 1545 Hot Water Units Gallons per Hr (100 Rise) Equiv. Direct Radiation 744 1,240 1,654 2,068 2,481 3,308 4,135 5,169 6,203 8,270 10,338 12,405 14,473 16,540 20,675 4,020 6,700 8,933 11,167 13,400 17,867 22,333 27,917 33,500 44,687 55,833 67,000 78,167 89,333 111,667 Overall Dimensions (Inches) length Height Width 7035 80 H 87)4 84 124 35 152 16234 1733* 197 35 224 35 251 }5 252 252 252 29334 45H 55 5734 57H 6434 66)4 73 H 8435 9135 9834 98H 102)5 102Vi 10235 10235 36 45 48 48 51 56 65 70 78 85 85 90 90 90 90 Heating Systems Emwdoa1 COLUMBIA Boiler Company of Pottstown Pottstown, Pa. Makers of steel power and heating boilers COLUMBIA'S H.R.T.* OIL OR GAS FIRED BOILER ASME CODE CONSTRUCTED-- Available for pressures of IS to 150 psl. A complete, automatic power plant wherever steam is used for pro cessing Horizontal Design for longer life: The complete submersion of tubes pro tects them from water line corrosion. Dry Steam Assured: Large steam Space and greater liberation area vir tually eliminate waste producing water carryover. Columbia h.r.t. boilers are fully auto matic, compact, complete steam gener ators. Available in sizes ranging from two to sixty horsepower. Designed for firing with gas, light or heavy oils. A special Columbia unit makes possible the inter-changeable use of gas or oil. Overfiring Permitted: Conservative rat ings plus large combustion volume per mit overfiring. This frequently elimi nates the need for additional boiler capacity, allows for plant expansion. High Steam Output: Columbia's h.r.t. boilers have an unusually large heating surface to produce more steam at higher efficiencies. More heat is converted into steam since it is proportioned to make maximum use of hot gases of combustion for the production of steam. Over-All Efficiency: Factory installed, specially designed combustion chamber provides rapid heating refractory sur faces for peak combustion efficiency. In sulation, 7 inches thick in the combus tion chamber proper, and 4 inches thick in the gas passage, keeps heat loss at a minimum. Special refractory brick heats up to great intensity to complete the combustion of previously unignited fuel particles. This complete combustion not only increases efficiency but makes for clean combustion. Soot accumulation on heating . surfaces is minimized. Boiler tubes require less cleaning. Safety Assured: Two pass updraft design lowers direct loss and reduces possibility of furnace pressure, pulsation or exces sive combustion noises. Accessibility and easy Maintenance: Simplified construction provides easy front and back access to the single bank of tubes. Entire unit can be gotten to for inspection of boiler and chamber by removing the covers. SPECIFICATIONS AND DATA COLUMBIA HRT BOILERS FOR GAS. LIGHT OIL OR DUAL FUEL Horizontal Return Tabular Type Boiler Size Jp Rating...................... jength O.A..................... Yidth O.A....................... deight O.A..................... Yater Heating Surface. Dil Firing Rate.............. jas Input...................... Approximate Output... ...........sq ft . gal. per hr .But per hr .Btu per hr 6 5$ 29 44 30 2.00 250,000 200,000 6 8 69 33 50 56 3.00 400,ooc 300.000 8 10 69 33 50 72 3.5 490,000 350,000 10 15 84 39 64 92 5.00 700,000 500,000 15 20 84 39 64 120 7.00 900,OOC 700,000 25 30 100 45 68 H 200 10.00 1.400,000 1,000,000 35 ___50_ 40 100 60 102 45 52 6SH 290 12.00 ' 18 1.700,000 2,600, 1,200,000 1,800,( Horizontal return tubular type boiler 1546 Heating Systems Boilers. Steel Gas and Oil COLUMBIA Boiler Company of Pottstown Pottstown, Pa. . Makers of steel power and heating boilers STEEL, TUBELESS OIL-FIRED, WATER TUBE GAS-FIRED AND COAL-FIRED HEATING UNITS Available with highly efficient, custom engineered gas or oil burners. Columbia steel boilers, gas or oil fired, have self con tained large copper instantaneous tank less coils, supplying a continuous flow of year 'round domestic hot water. Maximum operating efficiencies assured by the balanced design of the boiler and burner; by the arrangement of the baffles which force the hot gases to travel four of five times the full length of the boiler. One piece electric welded construction: Columbia offers a heating unit with full electric welded construction of heavy copper bearing steel, to assure lower heating cost and longer operating life. Quiet operation: Ample combustion space, the insulation and heavy steel jacket completely eliminate objectional noise. Dual Firing: Columbia gas heating units may be easily converted for efficient oil firing. * MODEL NO. Ratings--Oil Fired Input--Gals per Hr. .*.. Output--Btu per Hr... Installed Radiation Sq Ft Forced Water -- Sq Ft Gravity Water... Btu per hr Forced Water Btu per hr Gravity Water........... ................ Btu per hr Steam......... L-I6 1.00 105,000 580 * 510 320 86,000 77,000 77,000 L-18 1.20 120,000 720 640 400 108,000 96,000 96,000 L-20 1.35 150.000 990 880 550 148.000 132.000 132,000 L-22 1.75 210,000 1260 1120 700 189.000 168.000 168,000 L-24 2.25 270.000 1620 1440 900 243.000 216.000 216,000 L-30 3.00 330.000 1980 1760 1100 298.000 264.000 264,000 L-32 4.00 450.000 2700 2400 1500 405.000 360.000 360,000 * Constructed Water Tube Only Gas Fired Unite AH.A. and SUR Approved for outputs from 72,000 to 172,000 Btu's per hour Goal Hand Fired Conversion Units available in sizes L-18, L-22 and L-30 COLUMBIA BASEBOARD RADIATION Suspended Element--no noise! Tension Fastening--no rattling! Low Angle Heat--no drafts! Pre-Punched Holes--fast installa tion! 1547 Heating Systems Stokers Combustion Engineering, Inc. AU Types of Fire Tube and Water Tube Boilers Mechanical Stokers Complete Steam Generating Units Pulverized Fuel Systems 200 Madison Avenue, New York 16, N. Y. Offices in all principal cities of the world More than 20.700 C-E Stokers purchased to date C-E SKELLY STOKER--A compact, self-contained unit with integral forceddraft fan, designed to burn either bi tuminous coal or anthracite. Alternate fixed and moving grate bars assure lateral distribution of fuel. Automatic control is standard equipment. Approxi mate capacity range--20 to 300 rated boiler horsepower. C-E SPREADER STOKER--A simple, rugged overfeed stoker designed to burn a wide variety of coals. Revolving spreader blades feed fue} into the furnace in criss-crossing streams which assure uniform distribution. Fines are burned in suspension and the coarser coal on a grate which may be of either continuous discharge or dumping type. Rate of coal feed and air supply may be regulated over a wide range and are adaptable to automatic control. Applicable to'boilers from about 100 boiler hp up. C-B Spreader Stoker--Continuous Discharge Type C-E TRAVELING GRATE STOKERS-- Available in either bar or chain grate designs. These stokers are used for anthracite, coke breeze or free-burning bituminous coals. Available in either forced draft or natural draft designs. Application range from ISO boiler hp to units producing 275,000 lb steam per hr. OTHER TYPES--The C-E line includes the Type E Underfeed Stoker available for use with boilers from ISO to 600 boiler hp. A single retort underfeed stoker, it is one of the best known and most widely used in the world. It burns a variety of bituminous coals and it is particularly adapted to coals having caking and coking characteristics. 1548 Combustion Engineering, Inc, Heating Systems Boilers and Stokers C-E PACKAGE BOILER, TYPE VP I For medium size and smaller plants . . . completely shop assembled . . . pres sures to 500 psl... capacities from 4,000 to 40,000 lb per hr. . . oil or gas firing. The VP is a completely packaged two drum vertical bent tube boiler with inte gral water-cooled furnace. Automatic controls provide protection from flame failure, high steam pressure and low water level; also adjust the air supply to the needs of fluctuating loads. Pressure fired, the unit requires no induced draft fan. Being self contained, it needs no special foundation and may be placed on a concrete slab or on a level floor. Only connections required are water, fuel, steam, electric and flue vent. C-E Package Boiler, Type VP C-E LA MONT CONTROtLED-CIRCULATION HOT WATER BOILER For commercial or industrial heating or processing . . . capacities to 200 million Btu per hr . . . pressures to 300 psi . . . temperatures to 425 F . . . for coal, oil or gas firing. Using high pressure, high temperature water-in a closed system, this unit is ideally suited for those applications where high temperature water is pre ferred over steam. The C-E La Mont HT Boiler offers many advantages over other water systems--complete control, low pressure loss, single pass design with low draft loss, efficient heating surfaces and pressurized operation. It needs no induced draft fan or separate boiler pump. C-E LaMont Controlled Circulation Hot H'aicr Hoiler C-E VERTICAL-UNIT BOILER, TYPE VU-10 For medium-sized and smaller plants . . pressure to 475 psi . . . capacity to 60,000 lb per hr, or more . . . suitable for any type of fuel. A standard unit, the VU-10 is especially designed for industrial load conditions and plants having a limited number of operating personnel. It is of symmetrical design, and steam is released evenly across the full width of the unit. Gas flow is uniform, heat absorption is efficient and draft loss is low; it is essentially a "quick steamer." The boiler is bottom supported with no outside supporting steel. Type VU-10 boilers are adaptable to stoker firing or mav be fired with oil or gas. " 1549 C-E Vertical Unit Boiler, Type VU-10 i Heating Systems IST8, The Dewey-Shepard Boiler Co. Sales Office: 1311 N. Capitol Avenue, Indianapolis, Ind. STEEL FIRE TUBE BOILERS & HEATERS GAS & OIL FIRED VERTICAL FIRE TUBE UNITS capaciUes 95,000 to 1,000,000 Btu ASME CODE CONSTRUCTED NATIONAL BOARD REGISTRATION AVAILABLE All Dewey-Shepard boilers and water heaters (oil and gas fired) are built on the pat ented "Tube within a Tube" principle. All units are jacketed with fiber-glass insula tion ready for instant hook-up. , Oil Burners Underwriters Approved. Gas Burners A.G.A. Listed. Boilers Automatically Welded. Built-in Coils Optional. NET RATING Model Water, Sq Ft Steam, Sq Ft B c D E F G H I J K h -M 560 756 840 1120 1400 1540 1960 2120 2750 3000 4480 5960 . 350 470 520 700 . 875 965 1230 * 1330 1720 1895 2800 3730 Boiler ratings do not include allowance for Built-in Coils. If piping and pick-up loss exceeds 20 percent of installed radiation, allow for such added loss. OIL and GAS BOILERS and WATER HEATERS Dewey-Shepard's patented "Tube within a Tube" principle gives you 80 per cent or more heat absorption, resulting in pre-heating the incoming cold water before it comes in contact with the metal surfaces to which radiant heat is being applied. There is one square foot of heating surface for every gallon of water, transferring every possible unit of heat to the water, resulting in EFFICIENT, ECONOMICAL OPERATION . . . plus many other advantages for your customers, such as: LESS FUEL USED LOWER INSTALLATION COST#NO LIME--NO SCALE# 20 PER CENT LESS HEAT LOSS THROUGH THE STACK#NO EXPANSION, CONTRACTION OR CONDENSATION# CLEANEST HEAT POSSIBLE# SUFFI CIENT HOT WATER AT ALL TIMES DEWEY-SHEPARD'S NEW OIL and GAS FIRED "COUNTER FLOW" BOILER Designed for use with Baseboard Radiation, Copper Convectors, and Radiant Panel with forced circulation and small pipe sizes. SPECIFICATIONS COUNTER-FLOW Output Net Btu Model A Oil 90,000 Model A Gas 80,000 Model B Oil 135,000 Size 19 in. x 19 in. x 31 in20 in. x 20 in. x 34 in. 19 in. x 19 in. x 38 in. 1550 Weight 400 lb 275 lb 4501b Heating Systems Boilers Steel Dutton Boilers Division Hapman-Dutton Co. 639 Gibson Street, Kalamazoo, Michigan Four types, many sizes . . . From 5 hp up___Firing with gas, light or heavy oil, stoker coal or by hand ., . For processing, power, high and low pressure steam and hot water heating -- For Industrial Plants, Dairies, Laundry and DryrCleaning Plants, Chemical and Food Processing, Hotels, Schools, Institutions, etc. Off-Center Firing With EeonoTherm "Packaged" Models--Gas or Oil or Ctfinbination Gas-Oil. EeonoTherm Models are automatic, selfcontained, "packaged" units with full safety controls. Of 3-pass fire-tube de sign, they feature a modified Scotch Internal . Furnace located off-center. This firing creates rotary water circula tion, resulting in more uniform water temperature, fast steaming, steady water line at all times, and high quality dry steam. Higher water column above furnace adds extra safety, efficiency. Rotary cpmbustion, large steam stor age space, and five or more square feet of heating surface per rated "hp combine to deliver guaranteed 80 per cent .ef ficiency with dryness rating of 99 plus 0/0 dry steam under proper operating conditions. Induced draft or forced draft fan available for positive, fast firing. Only a vent pipe is needed--no chimney or stack. Boiler shell is welded in one piece, X-ray inspected; complies with all ASME requirements. Every unit gets full running test. Certified ASME Data Report furnished. Multiple Convertible Firing With The EconoMist "Packaged" Models. EconoMist Models are automatic, "packaged" boilers featuring multiple convertible firing. They can be equipped for firing by hand, stoker, light oil, heavy oil, or gas, singly or in combina tions. Can also be fired with by-products such as wood chips, sugar cane, corn husks, waste gas, etc. EconoMist Models give you the de pendability and simplicity of operation of H.R.T. design, plus greater combus tion space, less heat loss. Installation, operation and maintenance costs are low. Welded boiler shell is X-ray in spected; complies with all ASME re quirements. Sizes from 15 to 105 hp are available as "packaged" units ready to connect or as basic units less refractory lining and accessories. Can be equipped withinduced draft fan to eliminate need for stack or chimney. Conversion from one type of fuel to another is simple and inexpensive. Each unit is fully tested and certified ASME Data Report fur nished when shipped as a packaged unit. ECONOTHERM--RATI 5S AND CAPACITIES Equivalent Hp Sq ft Water Heat. Surf. Lbs Steam per Hr Equivalent Hp Sq ft Water Heat. Surf. Lbs Steam per Hr m20 700 125 650 4485 25 125 773 150 814 5617 30 151 1035 180 905 6210 40 201 1728 200 1000 6900 50 70 300 356 2070 2450 80 400 2760 100 510 3754 250 300 350 400 1252 _1500 1750 2000 8639 10,350 12,000 113,800 WRITE DIRECT OR CONTACT YOUR DUTTON REPRESENTATIVE FOR COMPLETE DE TAILED SPECIFICATIONS AND DATA DESCKIBING THESE AND OTHER DUTTON BOILER1' 1551 Heating Systems Btdiers. steel Re*. O. 8. Pat. Off. Fitzgibbons Boiler Company, Inc. 101 Park Avenue, New York 17, N. Y. Sales Branches in Principal Cities Member Manufactured at Oswego, N. Y. Steel Boilers since 1886 Reg. U. S. Pat. Off. t i r PRODUCTS--STEEL HEATING BOILERS AND BOILER UNITS for all fuels and all heating systems. Capacities to meet requirements of any building. Built and rated according to ASME and SBI Codes and "Hartford" inspected. Fitzgibbons Boiler Company, Inc. Heating Systems. Boilers, steel "D" TYPE FIREBOX BOILER For mechanical firing with oil, gas or stoker in ratings from 3650 to 60,700 sq ft steam, 876 to 14,570 Mbh EDR. 15 lbs Steam--30 lbs Water. For hand fired coal in ratings from 3000 to 35,000 sq ft steam, 4800 to 56,000 sq ft water, 720 to 8400 Mbh EDR. The steel boiler for heating apartments, office buildings, theatres, schools, hos pitals and other large commercial build ings. Provides year 'round service hot water, without the need of a separate storage tank, with the Fitzgibbons TANKSAVER, a copper coil submerged in the boiler water. 770 SERIES UNITS A completely pre-assembled and wired .OIL FIRED unit for forced hot water heating systems in small homes. Com bines the Fitzgibbons boiler, oil burner and TANKSAVER with all the neces sary controls and specialties into a co ordinated unit that provides abundant heat and tankless hot water at low cost. 580 (87,000 Btu) and 720 (108,000 Btu) sq ft water--SBI Net Rating. GAS FIRED: Available pre-assembled and wired, or as unassembled units. A.G.A. approved units, 96,000 and 124,000 Btu output. The aristocrat of steel boilers for resi dences. Quick heating, low fuel con sumption. Abundant hot water, winter and summer, without the need of a stor? age tank with the Fitzgibbons TANK SAVER. In sizes from 400 to 900 sq ft steam, 720 to 1620 sq ft water--SBI Net Rating. R-Z-U JUNIOR BOILER The popular choice for a wide range of intermediate installations ranging from large residences to medium sized schools and commercial buildings. Large com bustion area and two passes through 3 in. tubes account for efficient firing with oil, gas or coal. No rear or left side clearance necessary as all servicing can be done from the front. In eleven sizes from 264 to 1200 Mbh--SBI net. FITZ GIBBONS TANKSAVER available for service hot water. 1552 "SCOTCH TYPE" BOILER A Full Wet Back--Low 'Pressure Heating Boiler for oil and gas firing in sizes from 5470 to 60,700 sq ft steam, 1313 to 14,570 Mbh EDR. 15 lbs Steam--30 lbs Water. This compact, efficient Fitzgibbons Boiler has the design advantage of com plete water jacketing of all heating sur faces, including the rear furnace wall, thus eliminating usual rear dry-wall re fractory lining and corresponding up keep and repair expense. PACKAGED BOILER UNIT Fully assembled and wired integrated unit for low pressure commercial appli cations. Fire tested and shipped as a unit ready for firing on the job. Boiler has full wet back construction that eliminates re curring expense for maintaining rear refractory. SBI ratings based on 8.2 sq ft heating surface per boiler hp with guaranteed gross outputs based on 5.0 sq ft of heating surface. Induced draft for quieter, cleaner operation. Thirteen sizes from 39 to 464 hp. 1553 Heating Systems Boilers, steel Farrar &Trefts Division Sales Offices: Birmingham, Ala. Little Rock, Ark. Los Angeles, Calif. Denver, Colo. Washington, D. C. Clearwater, Fla. Miami, Fla. Atlanta, Ga. Boise, Idaho Chicago, 111. "Louisville, Ky. New Orleans, La. Springfield, Mass. Detroit, Mich. Grand Rapids, Mich. St. Paul, Minn. Kansab City, Mo. Adsco Industri es. Inc. Dallas, Tex. El Paso, Tex. 20 MILBURN ST. BUFFALO 12, N. Y . Houston, Tex. San Antonio, Tex. FARRAR & THEFTS SALES OFFICES St. Louis, Mo. 'Billings, Mont. Omaha, Neb. Nutlet, N. J. Albuquerque, N. M. Geneva, N. Y> New York, N. Y. Rensselaer, N. Y. Rochester, N. Y. Syracuse, N. Y. Cleveland, Ohio ,, Dayton, Ohio Toledo, Ohio , Oklahoma City, Okla. Portland, Orb. Mechantcsburg, Penn. Philadelphia, Penn. Pittsburgh, Penn. Scranton, Penn. Chattanooga, Tbnn. Salt Lake City, Utah Richmond. VaSeattle, Wash. Spokane, Wash. Milwaukee, Wib. Export Division: St. Catharines, Ontario, Canada Honolulu, Hawaii Mexico City, Mexico Buenos Aires, Argentina, Charlotte, N. C. Columbus, Ohio Cincinnati, Ohio Knoxville, Tenn. Memphis, Tenn. Nashville, Tenn. South America Montevideo, Uruguay South America SCOTCH WET BACK HEATING BOILERS Series 3000, for packaged heating units. These boilers can be used with any manu facturer's burner equipment. Two-pass design gives good distribution of beat transfer with low stack temperatures and permits easy access to tubes. Large water and steam space assures smooth opera tion, steady pressure, and constant heat. Among the features are: Wet front furnace--Front end of furnace, with water all around, is flush with front of boiler. Burner can be connected to fire directly at water heating surface without heat loss. Complete wet back--Entire combustion chamber is surrounded by water, for efficient and quick conversion of water to steam. There is no heat waste in rear; boiler room is.cooler. Sizes from 4200 to 70,000 sq ft of steam radiation. SCOTCH WET BACK HEATING BOILERS Series 2600 Where economy of installation and op eration are paramount and the space is small, F & T Series 2600 Boilers are ideal. No expensive foundations, pits, or ex ternal brick work are needed. Piping to boiler is easily installed, especially where headroom is at a minimum. Steam space extends the entire length of the boiler, since the surface above the rear combustion chamber is covered with water. This provides large steam space and disengaging area. Series 2600 boilers are self-contained and can be moved easily and installed on two saddles. All parts are readily acces sible for inspection and cleaning. Boilers can be furnished with special front.fur nace extension to suit burner require ments. . Sizes from 3160 to 42,500 sq ft of steam radiation. BISON COMPACT HEATING BOILERS iison Compact Heating Boilers are designed to have a large urnace volume, ample water and steam storage, proper steam iberating surface and a balanced circulation. The result is a emarkably steady waterline. Original cost of Bison Compact Heating Boilers is low and ,hey are easily installed. They come complete, ready for pipng. Minimum brick work is required. These boilers are de signed for mechanical firing with oil, gas or stoker, but can oe made for hand firing with anthracite or bituminous coal. Sizes from 2680 to 42,500 sq ft of steam radiation. 1554 Heating Systems % aniere. Gas HYDROIhERM c* Northvale, New Jersey HYDROTHERM The "Packaged" Automatic Gas Heating Plant. For resi dential, commercial and industrial hot water systems. HYDROTHERM is designed to de liver maximum hot-water heat with minimum fuel consumption. Fully A.G.A. approved for use on manu factured, natural and LP Gas . . . from 45,000 to 500,000 Btu; Outstanding for: Model R150 without jacket 600 sq ft installed radiation. Baseboard, convector and - radiant panel heating systems Individual apartment heat Natural companion for cen tral cooling system i Booster service for 180 de gree sterilizing water Volume hot water heating Model R1S0 with jacket 4SS H>s, Iff in. x St in. x t7 in. vviuiAuvuvii; au cose trim nyarotnerm's unique absorption unit has deep ribbed horizontal sections, which are connected in zig-zag. This design affords maximum heat transfer surface for minimum water volume, resulting in greater efficiency and faster pick up. Hydrotherms are factory tested at 250 lb hydrostatic pressure and are ASME approved for 100 lb working pressure. Unit is fully wired and assembled for speedy installation. All controls including automatic gas control valve, Baso safety pilot,' pressure regulator, aquastat and tridieator are enclosed in De Luxe jacket of Hammeroid finish. CAPACITY RANGE OF HYDROTHERMS SPACE HEATING A.G.A RATINGS VOLUME WATER HEATING GALLONS PER HOUR FOR Model No. M-45 M-72 M-85 Natural, Mixed and . L.P. Gas Manufactured Gas (Propane and Butnnpl input output install- input output installBtu/ Btu/ jed* ra- Btu/ Btu/ led* ra- 45.000 36,000 72.000 57,600 85.000 68,000 ; 288 j 72,000 571600 340 | 85,000 68,000 las 288 340 Natural, Mixed and Manufactured Gas L.P. Gas (Propane and Butane) * #' 60 80 100 120 140 60 80 100 120* 140* 72 54 115 86 136 102 43 69 81 36' 30 67 50 40 33 28 57 49 115 85 69 57 49 68 58 136 102 81 68 58 R-100 100,000 80,000 R-120 120,000 98,000 R-150 180,000 120,000 R-170 170,000 136,000 4d0 100,000' 80,000 480 110,000 88.000 600 il45,000;il6,000 680 j -- | -- L-200 ^200,000 160.000 800 200,000'l60,000 L-250 (250,000 200.000 1,000 225.000,180,000 400 440 580 160 192 240 272 120 144 180 204 96 115 144 163 80 68 160 120 96 80 96 82 176 132 105 88 120 136 103 116 232 174 139 116 68 75 99 ---- ^----- 800 900 320 400 240 300 192 240 160 200 137 173 320 360 240 !192 270 .216 160 180 137 154 EE D R-300 300.000 240.000 1,200 290,000 232,000 R440 340,000 272,000 1,360 1.160 480 544 360 408 288 326 240 272 206 232 464 348 278 232 198 ibft L-400 '400.000 320.0001 1.600 L-500 500,000!400,000l 2^000 400.000 320.000 450.000 360.000 1,600 1 640 1.800 1 800 480 600 384 480 320 400 274 346 640 720 480 540 384 432 320 360 274 308 0 Indicates net load at 17(FF water and includes pick-up and piping 1555 Heating Systems Boilers, steel THE INTERNATIONAL BOILER WORKS CO. 500 Birch St., East Stroudsburg, Pa. - Sales Offices in Principal Cities WATER TUBE BOILER DESIGN ASSURES. . . QUICK STEAMING ... due to rapid and directed water circulation. MORE HEAT ABSORPTION ... due to extra long three pass gas travel, across the entire bank of water tubes. EASY CLEANING . . . free access to heating surfaces makes cleaning easy. INTERNATIONAL WATER TUBE BOILERS. . . ' Standard sizes: Heating Boilers 400 70,000 sq ft steam, Power Boilers 10 600 bhp. . Steel Boiler Institute ratings. Heating Boilers 15 lbs steam-30 lbs water. All Boilers ASME standard For Oil, Gas, Stoker or hand fired Coal. INTERNATIONAL "COMPAK" PACK AGE BOILERS ... Completely assembled factory firetested water tube package boilers. For low pressure and high pressure re quirements. Oil, gas, or combination oil-gas fired. INTERNATIONAL-LA MONT* FORCED RECIRCULATION BOILERS Specifically designed for . . . High Temperature Water distribution systems. Hi-Temperature process systems em ploying Dowtherm, Aroclor, Socony Vacuum Heat Transfer Oil and other Thermal Liquids. . Write for complete catalog. * Licensed under LaMont patents. 1556 Large Heating Boiler-Type C Induced Draft Units for Heat or Power International "COMPAK" Package Boiler Intemational-LaMont High Temperature Water Generator Heating Systems Boilers, steel Johnston Brothers, Inc, ESTABLISHED 1864 Member Ferrysburg, Michigan ttg. u. $. Pet. off.;? "PACKAGED" STEAM BOILER UNIT FULLY AUTOMATIC HEAVY OIL AND/OR GAS WATER-BACK TYPE, FORCED DRAFT, THREE-PASS, TROUBLE-FREE, EFFICIENT. Catalog-Rating guaranteed and at least 25 per cent overloads readily ob tained. HIGH PRESSURE TYPE from 60 to 800 hp and pressures of 125, 150 and 200 lb psi (250 lb available as a special) LOW PRESSURE TYPE for heating; 15 lb pressure, and EDR rating from 2190 sq ft to 42,500 sq ft steam. ASME Code construction. Under writers' Laboratory and Factory Mutual Approved. Specification Forms in detail to exactly cover the requirements of any particular job will be furnished upon request and without any obligation whatever. Ask for Bulletin 509 A Standard Scotch Boiler Water-back Type, Natural Draft. Firebox Heating Boiler, Compact Type. Oil, Gas, Stoker or Hand Firing. ThreePass, 15 lb pressure, ASME Code. Capacities 2190 to 42,500 sq ft, SBI rat ing. Ask for Bulletin 1500. Also built for High Pressure (125 psi.) Ask for Bulletin 70S. POWER, PROCESS, HEATING 25 to 300 hp and pressures 15 lb to 200 lb psi. For mechanical firing with Coal, Gas or Oil. Overloads up to 200 per cent of rating readily developed. Oil or Gas firing equipment and controls can be in stalled for completely automatic opera tion and in emergency or fuel scarcity, can be readily converted to Coal firing. Ask for Bulletin 4000 and 9000 and 920Q, 1557 Kewanee Boiler Div. of American Standard oz f 021 (A o z m* J-i o 5 CO H Uc>j> Cac3O, > TJ *cco3 a '*>?. 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OS O. > SH 1561 11 |S I1 lg5ssS I 1 5ooo^3 1 mdiet CO I 1 ono'e^'^3 s' dieliei e SE 1 lSSe^7--7co s: 1 1 dJ.A cco- ocdcoco^s wb saa,S 23 PS Q <Ct-O0 OoeXcOoMwWioi pi -0w, i4* S O utC-oO- Ot*fOQCM~O -QJi CNO CM^1Oi MOir1l M--c1ol Vi OooCeOcOflwHir >cpoo 11734 ~ J. iA 5co OoSxiOSmm 3RU o|vO<Oh|P21hCg) clooicst2o*u2b 0 co cOoc0OQ--0OCtcofOlcokfp*-0iTclMoll0uMb Pi sCO kc<o5OtC'OwCWoOc(MoBc1oS-c|X0w1o^o-| ggSSCS.-- 2 3R7 : 3R8 OtCefl cNrroOCrf-l OiC-Oi^C0rifl'O0-ii'ChlOintO CO CO OOCCffll INMO Oto'cNmairCo-tflp--S*if'l'cHlolNmor W3 0CO3 o0m0n-rw-tomSi C1floCO1H1Mws1 CO 0otMolCOOo-to1-OOCtflo--SiR>llOcl^.<-> CO oCOs c--oCc--fol cMoOl (St.-C-rfl ^c1o >10C-*wr-t oO-t< a|-_iWo5 ot- 2 g 2Cfl 5CflSCcrflTCfl't?o*-cf* "c.c.c..c Ssssliil Boiler Number.................................... 3R2 l2 :=? : : 5a1 30k.-03L5Ogm^f4e."^mdj^>'--SJt3f 2n-sSSSS CAD ' ' KJJ`C0Q'0C'0Q^^ Heating Systems Boilers and Burners Orr & Sembower, Inc. Established 1885 . Morgantown Road, Reading, Pa. ^PbtOZklKftTfEA-L PACKAGED AUTOMATIC BOILERS Powennaster boilers are modern, com pact, self-contained, automatic units with an outstanding record for highly dependable and efficient performance in public buildings, hospitals, schools, apartments, industrial plants and other installations. Two models are available in standard sizes of 15 hp to 500 Bp for steam generation to 250 psi, and for hot water to 30 psi. As delivered, Powermas- ters are completely factory-assembled on a structural steel base for simple in stallation. Both models are designed and built to ASME Boiler Code require ments, approved by Underwriters' Lab oratories, Inc., and fully guaranteed by Orr & Sembower, Inc. All units are thor oughly factory-tested under fire. Advantages--Cost-saving installation . . . space-saving compactness . . . fuel saving efficiency at all loads .. fast steaming . . . instant response to load swings . . . clean, dry steam . . . hospi tal-clean operation . . J maintenance saving accessibility . . . fully automatic operating and safety controls . . . onesource responsibility for complete unit . . . nation-wide factory trained service. Model 3 Powennaster (40-500 hp) pro vides . . . Complete fuel flexibility: Light or heavy oil, any gas or combina tion oil and gas . . . Choice of: Air atomizing oil burner--pre-mix gas burner--combination oil and gas burner --all designed and built by O & S . . . full-range modulation . . . selection of automatic operating and safety controls . . . instant change from fuel to fuel. Model 4 Powennaster (15-100 hp) pro vides . . . Choice of fuels: Light distil late--^natural gas--manufactured gas-- combination oil and gas . . . Choice of: Mechanical pressure atomizing oil burner --pre-mix gas burner--combination oil and gas burner--all designed and built by O & S . . . dependable on-off and low-fire start burners . . . selection of automatic operating and safety controls . . . quick change from fuel to fuel. OUTPUT OVERALL DIMENSIONS BOILER Hp 2150 30 : 40 50 60 70 80 100 125 210500 250 300 350 400 500 Lbs Steam/ Hr at 212F EDR (Water) Sq Ft EDR (Steam) Sq Ft Length 517 600 1,035 1,380 1,725 2,070 2,415 2,760 3,450 4,312 5,175 6,900 8,625 10,350 12,075 13,800 17,250 3,336 4.448 6,672 181,,812906 13,344 15,568 17,792 22,240 27,800 33,360 44,480 55,600 66,720 77,840 18181,,926000 2,085 2,780 4,170 5,560 6,950 8,340 9,730 11,120 13,900 17,375 20,850 27,800 34,750 41,700 48.650 55,600 69,500 V 0* 111r8100'''' n' 9' 3' 8' 6* 1111'' 6' s' ir 3' 13' 1' 14' 7' 16' 7' 15' 7* 17' 5' 17' 9* 18' 11' 19', 7' Width Oil 3' 7' 8' 4' 71"' 4' 9' 4' r 5' jr 5' 66'' 2V' 7' 6' 7' V 88'' 1171111''''' 9' O' 9' 9' 1' Gas 4' 0' 4' 0' 4' 6' 5' 3' 566''' 3' 3' 3' 6' 10' 7' 3' 7' 3' 8' 9' 8' 9' 88'' 11' 10* 9' 10* 190'' lO' O' Height 5' 4' 5' 4' O6'' 2* 9' 6' 9' 7' 4' V 4' 8' 1' 8' 8' 8'- 8' 9' 5* 9' 6' 9' 11' 1119010''''1111811'''' WEIGHT Lb 2,700 .3,000 - 3.750 6.350 6.750 7,900 8,500 10,700 12,500 14,000 2127,,135000 25,560 33,700 36,000 37,000 45,000 Fuel Coztsump. (100% of rating) #2 Oil 96 Oil Gas Gal/ Gal/ Cu Ft/ Hr Hr Hr 64..72 9.4 12.5 15.6 18.7 21.9 25.0 31.2 39.1 46.9 62.5 78.1 93.8 109.4 125.0 156.3 --- --- --- 10.8 13.5 16-1 18.8 21.5 26-9 336 40.4 53.8 67.3 80.? 94.2 107.7 134.6 628 837 1,255 1,673 2,091 2,510 2,928 3,346 4,183 5,229 6,274 8,366 10,457 12,548 14,639 16,731 20,914 1562 Heating Systems Boners. Gas Raypak Company, Inc. 2416 Chico Avenue, El Monte, Calif. nui wftllSK rsUiLiSKS 1 vras urea All models approved by A-G.A. Complies with ASME Code for low-pressure hot water boilers. copper water lube Models~T Standard Boiler SPECIFICATIONS Model 75 Model 110 Model 160 Model 225 Btn input 75,000 110,000 160,000 225,000 Btu output 60,000 88,000 128,000 180,000 EDR 400 sq ft 586 sq ft 853 sq ft 1200 sq ft 60 rise 120 gph 176 gph 257 gph 360 gph 72 gph 106 gph 154 gph 216 gph 125 lbs 160 lbs 195 lbs 225 lbs ;ui inuueis usueu aiso avauaDie as packaged "piug-in" boilers including expansion tank, transformer DPST relay, air vent, mometer, pressure gauge, relief valve and high head circulator; jacketed. Special packaging for swimming pool direct heating for central heating, automatic fill, therall piped, wired and independent electrical system, thermometer and low-water cut with off. self-contained COMPACTNESS FEATURED All three Raypak models are similar in exterior appearance to those illustrated with controls concealed and protected and are available in every Btu size. Ray pak is quiet-engineered, a packaged boiler of single-shell construction with heavy 18-gauge baked enamel jacket. Model 75 is designed primarily for central heating. All models are adapt able to radiant heating, swim pools, (included sensitive pressure detector for low-water cut-off), air conditioning, volume supply and baseboard radiation. EXTRA ADVANTAGES Quiet efficient modulating gas valve operates at any temperature, sizes the boiler for the job. Heavy wall mono lithic cast insulated refractory keeps outside cool to touch. Integral copper fin tube heat exchanger in grid form, extra heavy headers, concealed and main gas valve are features of all models. Raypaks are condensate pro tected with clean air foil transfer sur faces. Minimum pressure drop is assured, plus equal tube flow. RADIANT HEATING, BASEBOARD RADIATION and AIR CONDITION ING COIL UNITS Model-T and -TP, designed primarily for residential and small commercial heat ing, combine on-off firing with gas modu lation . . . turns off and on at lowest flame for quietness and to minimize ex cessive firing. Model-75 preferred in group construction installations for lightness (125 pounds) and easy one-man installation. Occupies only 1). sq ft of floor space or can install elevated. Con trols concealed--no installation clutter. All models have 100 per cent copper wa terways, preventing electrolysis, rust, ferric corrosion or water discoloration. 1563 Heating Systems Boilers, steel THE TITUSVILLE IRON WORKS CO. TITUSVILLE, PENNSYLVANIA DIVISION OF STRUTHERS WELLS CORPORATION Designers and Manufacturers of A.S.M.E. CODE . BOILERS.. .since 1860 PACKAGE BOILERS Type Designation WTP Type Designation Ticosteam The Titusville Type WTP Water Tube The Ticosteam Generator is a packaged Steam Generator is completely shop- steam power plant, completely equipped assembled, ready for operation as soon at the factory, tested and certified. Es as service connections are made. The sentially the unit is a three-pass, con Type WTP features forced draft, pres stant furnace pressure, forced draft, fire surized furnace operation, and requires tube, horizontal boiler, with burners of no high stack or induced draft fan. It is special design using any desired type of adapted for firing with heavy oil, light gas, fuel oil, or combination of the two. oil, natural gas, coke oven gas or manu Built in sizes from 20 hp to 350 hp, this factured gas, and combinations of these unit provides outstanding economy in fuels. Capacities are from 7,500 to 40,000 operation, with thermal efficiencies of not lbs of steam perKour. less than 80 per cent. TYPE CM SPLIT FIREBOX BOILER Designed for replacement installations where entrance conditions are not suffi cient to accommodate standard boilers, the Titusville Type CM Split Firebox Boiler offers maximum utility and con venience. Separating into four basic sec tions (see cut), the Split Firebox CM Boiler can be taken easily through nar row doors and passageways impossible to negotiate by standard models, with out damage or alterations to building* Wide range of sizes and capacities. 1564 Heating Systems Boilers, steel THE TITUSVILLE IRON WORKS CO. Titusville, Pennsylvania LOW PRESSURE HEATING BOILERS Titusville Compact Steel Heating Boilers built in 22 sizes ranging from 129 square feet to 3571 square feet heating surface, and maximum steam working pressure 15 psig. ---------- Titusville Scotch Marine Heating Boilers built in 22 sizes from 129 square feet to 3571 square feet heating surface, and maximum steam working pressure 15 psig. HIGH PRESSURE FIRETUBE BOILERS Titusville All-Welded Portable High Pressure Firebox Boilers built in 12 sizes ranging from 250 square feet to 2500 square feet heating surface, steam pres- sure 100 psig, 125 psig and 150 psig. ,,. litusville Scotch Marine Power Boilers built in 13 sizes ranging from 97 square feet to 3000 square feet heating surface, Pressures 125 psig and 150 psig. WATER TUBE BOILERS Type Designation Ticotkerm Titusville Ticotherm Steam Generators built in 13 standard sizes ranging from 1000 square feet to 5000 square feet heat ing surface. Pressures 160 psig, 200 psig, 350 psig and higher. . Typs Designation TDL Titusville Three Drum Low Head Water Tube Boilers built in numerous sizes ranging from 729 square feet to 6109 square feet heating surface. Pressures 150 psig, 200 psig, 250 psig and higher, Descriptive technical literature is^available on request. 1565 ______________________________________ Heating Systems gg"tor Pgit Preferred Utilities Manufacturing Corp.; 1860A Broadway, New York 23, N. Y. - Sales Offices in Principal Cities Unit Steam Generators Oil, Gas and Combination Burners Draft-A-Justors Fuel Oil Heaters Heating Accessories PREFERRED UNIT STEAM GENERATOR The fully automatic "package" boiler of outstanding reputation for producing steam or hot water at a low overall operating cost. Burns oil, gas or both fuels in combination with equally high efficiency. , Factory fire-tested before shipment, every Preferred Unit is certified to oper ate at a guaranteed thermal efficiency of 80 per cent or more. Its fast steaming means faster response to fluctuating boiler loads. The unit, fully piped and wired, is mounted on a heavy H-beam base so that no excavation or special foundation, frequently a major item of installation cost, is necessary. It occupies about half the space needed by ordinary boilers of equivalent output. No ugly, costly stack is needed. Capacity--20 to 600 bhp, 15 to 250 psig (see table). Preferred's 25 Year Features 1-- 5 sq ft of Heating Surface per boiler horsepower for reliable, economical, con tinuous steam production. 2-- Four-Pass Gas Travel for uniform heat distribution, quick steaming; clean heat transfer surfaces minimize tube cleaning; lower stack temperature. 3-- Down Draft Design for guaranteed high operating efficiency and low off- period losses. 4-- Induced Draft for smoother starting, higher combustion efficiency, less refrac tory maintenance. 5-- Intermediate Furnace Position pro tects tube areas and safeguards shell from unequal heating. 6-- Expansile Precipitator, installed in flue gas offtake, prevents rapid build-up of non-combustible deposits. 7-- Staggered Tubes insure thorough heat wiping of the entire tube circum ference at all times; makes possible faster heat pick-up rate. 8-- Anti-Stress Deck keeps the sections of the rear tube sheet; above and below water line, in close balance, preventing unequal stress action within the area. BHP Rating 20 30 40 50 60 70 80 100 125 150 19 Standard Sizes Max. Rated Capacity Lbs Steam per hr at 212 F. i> 690 '1035 1380 1725 2070 2435 2760 3450 4313 5175 BHP Rating 200 250 300 350 400 450 500 550 600 Max. Rated Capacity Lbs Steam per hr at 212F. 6900 8625 10350 12075 13800 15525 17250 18975 20700 9--Dual Purging Action removes gas vapors from the entire vessel before and after firing. 10--Horizontal Rotary Burner for oil, gas or combination--starts, ignites, follows the load, shuts off, cleans and purges itself automatically. For detailed information write for Bulletin 2000. Other Preferred Products Horizontal Rotary Burners for oil (7*^ to 175 gph); for gas and oil (15 to 90 gphoil) and (2050 to 12,300 cfh of 1050 Btu gas). "Thermopak" completely integrated oil or gas combustion system for existing boilers of 20 to 525 bhp. Pump and Heater Sets for preheating oil, 110 to 1200 gph. Draft-A-Justors, barometric type for controlling stack draft. Fuel Oil Heaters, Combustion controls, Oil Valves, Gauges, Boiler Accessories. 1566 Heating Systems Steam Generators Vapor Heating Corporation 80 East Jackson Blvd., Chicago 4, Illinois . NEW YORK ST. PAUL WASHINGTON PHILADELPHIA ATLANTA SAN FRANCISCO HOUSTON RICHMOND LOS ANGELES ST. LOUI8 VAPOR MODULATIC STEAM GENERATORS ' Industrial Type A compact steam generator--a safe, de pendable, push-button "boiler plant" you merely set and forget! It's the answer to your plant expan sion--to steam for any use. Moving a desk makes room, or any corner will do. Needs no enclosure, special foundation, expensive stack. Operation is clean, quiet, automatic. Two-minute steam from cold-starts ends early reporting and standby. Saves time, saves fuel . Modulatic tracks fluctuating steam de mand, up or down, with speed and ac curacy. Fuel consumption is exactly pro portional to volume of steam used. Shipped complete, passes through plant- type doorways. W'1 Sizes, 10 to 160 hp. Pressures to 1000 psi. Multiple installations can have a single automatic control that cuts whole units "in" or "out" according to steam demand. Oil, gas, or flip-switch com bination burner. Vapor Modulatic Steam Generators are built to conform to both the ASME Power Boiler Code and ASME Healing Boiler Code. Drum-Type tor heating, low pressures. Full Modulatic advantages of compact ness, quick steaming, and high efficiency incorporated into a heating boiler with controls materially simplified. Reduced cost, reliable performance, minimum maintenance. Especially designed for operating pressures below 15 psi. Industrial Type Drum Type VAPOR WAIKIKI HEATER Gives a flood of hot air at the touch-of-a- button for every conceivable use. Sets on floor, shelf; hangs from ceiling; burns kerosene, fuel oil, gas. Plugs into 110volt, a-c outlets. Versatile, simple to service Ttoo HI,000 and 100,000 Btu per hoar. Permits simple connection to exhaust vent or stack, or including combustion products in forced air circulation. Burner and blower are outside-mounted--no moving parts inside the unit. Shipped fully assembled and wired. Out put: 2400 cfm. Compactly quality-built for efficient performance with extra large heat transfer area. 1567 Heating Systems stokers Detroit Stoker [oirporv -General Motors Building - Detroit, Michigan Detroit LoStoker (Underfeed type) Compact firing unit--single retort-- mechanically driven--plunger feed--side cleaning stoker. Sizes and capacity for all heating boilers, from 50 to 150 horse power 'rated capacity. Now available with Detroit Adjustable Feed--provides automatic control of coal and air. Effi cient and dependable operation assured. Detroit RotoStoker (Spreader type) Built with stationary, hand or power dumping grates or continuous cleaning grates. Wide range of sizes. Burns all bituminous coals without special prepa ration, but with high thermal efficiency. Responsive to fluctuating loads. Heating Systems stokers COMMERCIAL . INDUSTRIAL RESIDENTIAL AIR-CONTROLLED BITUMINOUS STOKERS Detroit LoStoker--a great coal saver. Easily installed. Thousands tn operation. Write Jot catalog. Detroit UniStoker (Underfeed'type) Plunger feed, side cleaning, compact unit type. For boilers of 125 to 250 hp rated capacity. Detroit Adjustable Feed keeps air supply in ratio to coal feed. May be motor or steam turbine driven automatically controlled. Readily in stalled with existing boilers to provide automatic heat at low cost. Detroit RotoStoker (CC) is a new type with continuous ash discharge at the front. For steaming capacities ap . proximately 5,000 to 75,000 lbs. Smoke-free operation at light loads. ' Detroit RotoGrate (Large spreader type) For medium and large heating and power boilers up to 400,000 lbs steam per hour. Forward moving grates continuously and automatically discharge ash at the front. Combustion loss in ash usually less than two per cent. Detroit UniStoker with Adjustable Feed provides a wide range of coal feed control. Detroit RotoGrate Stoker burns all grades of coal. Permits higher burning rates. Responds quickly to changes in load. Bums wood and other refuse separately or in conjunction with coal. ' 1568 Patented automatic air control insures delivery of correct quantities of air to meet constantly changing fire-bed con ditions, eliminates need for banked fir ing methods and prevents back-smoking. If overload occurs, shear pin and auto- : matic switch protect stoker against dam age. Strong, cast iron hopper base with heavy gage rust-resisting steel hopper. Will-Burt hopper type stokers are avail able in 20 to 750 lbs per hr capacities. BIN FEED MODELS Like the hopper models, Will-Burt binfeed stokers offer all the advantages of automatic air control and the patented protective shear pin and switch. Pat ented flange and set screw locking device prevent coal screw from disengaging from drive shaft. Precision machined power unit. Capacities from 20 to 750 lbs per hr. PANEL BOARDS Prewired, pretested control panel boards provide an interconnected control sys tem for-stokers to be operated by either a common operating and/or individual holdfire control, depending on the setting of the safety switch, off-on switch and timeswitch cycle". Mounting wall brack ets are provided. Not illustrated, but available are control cabinets with controls mounted and wired on a sub panel and completely enclosed in a heavy steel cabinet. Write for your free copy of the Will-Burt Engineers and Architects Manual. 1569 Heating Systems BoOer Feeders McDonnell & Miller, Inc. Safety Devices for Steam and Hot Water Heating Boilers and Hot Water Tanks 3500 N. Spaulding Ave,, Chicago 18, Illinois ----- --------------------------------------- :-------------------:--------------- The McDonnell line consists of the following safety devices: (1) For Low Pressure Steam Boilers . . . Boiler water feeders, low water fuel cut-offs and combined feeders and cut-offs; (2) For Higher Pressure Steam Boilers . . . Pump controls, low water fuel cut-offs and low water alarms for pressures to 150 lbs, and receiver make-up water feeders; (3) For Hot Water Space Heat ing Boilers . . . ASME pressure relief valves, boiler water feeders, low water fuel cut-offs and combined feeders and cut-offs; (4) For Domestic Hot Water Tanks and Heaters . . . ASME pressure relief valves, temperature relief valves and combination T & P relief valves. McDonnell also manufactures liquid level controls for humidifying pans and many other applications- (1) LOW PRESSURE STEAM BOILERS Service Recommendations Boiler Size ... ... . Pressure McDonnell Product to Use For Automatically For Hand Fired Jobs . Fired Jobs Boiler Water Feeders and Feeder Cut-Off Combinations Up to 5000 sq ft Above 5000 sq ft Any size 25 lbs 35 lbs 75 lbs No. 47-2 No. 51-2 No. 53-2 No. 47 No. 51 No. 53 Low Water Fuel Cut-Offs (Jot Automatically Fired Jobs) Any size Any size 20 lbs 50 lbs No. 67 No. 63 McDONNELL Boiler Water Feeders and Feeder Cut-off Combinations McDonnell No. 47-S ' McDonnell No. Sl-S McDonnell No. 63-S McDonnell No. 47-2 Feeds water when necessary to maintain safe water level in boiler. If water level for any reason falls into emergency zone, cut-off switch cuts burner circuit until emergency has passed. Has "Quick-Hook-Up" for in stallation in gage glass tappings; "cool" feed valve; extra-deep sediment chamber; stainless steel valve and seat; ASME approved blow-off valve. Also available for hand fired jobs without No. 2 Switch, as No. 47 Feeder. McDonnell No. 51-2 is same as No. 47-2, except it has greater feeding capacity for larger boilers, and is installed with 1 in. equalizing pipes instead of "QuickHook-Up." Also available for hand fired boilers without No. 2 Switch, as No. 51 Feeder. For boilers operating at higher pres sures, from 35 to 75 lbs, use McDonnell No. 53-2 (or No. 53, without switch). McDonnell & Miller, Inc. Heating Systems * |5 33S McDonnell Low Water Cut-offs For automatically fired steam boilers of any size Maximum steam pressure, 2Q lbs. No. 67 has McDonnell "Quick-Hook-Up" for installation in gage glass tappings; deep sediment chamber with large open ing blow-off valve; packless non-binding construction; adjust able terminal box; snap-action twin switches. One switch can sound low water alarm, or control McDonnell No. 101 Electric Water Feeder; second switch cuts burner current if water level jy,,. drops into emergency zone. ' No. 61 has same mechanism as No. 67 but has larger body for installation with 1 in. equalizing pipes. 69 Series "Built-ins" meet same operating conditions, fit 2J^ in. tappings provided by many boiler manufacturers. Order by boiler make, model. McDonnell No. 101 Electric Boiler Water Feeder For boilers up to 5000 sq ft capacity. For use with No. 67 Low Water Cut-off, No. 61 or "Built-ins" which are standard equipment on many modern heating boilers. Its use converts cut-off into feeder cut-off combina tion. (2) HIGHER PRESSURE STEAM BOILERS McDonnell Pump Control, Low Water Fuel Cut-Off and Alarm Switch Maximum boiler pressure, 150 lbs. The McDonnell No. 150 has two switches; one controls electric feed pump or electric valve in line to steam pump; second stops burner on greater float drop and completes alarm circuit. Under writers' Laboratories approved. No. 150 has automatic reset; for manual reset order no. 150-M. Maximum boiler pressure, 250 lbs. The No. 192 is a totally new kind of con trol. Introduces a new principle of repul sion magnetic switching. Has junction box totally sealed from float chamber; remarkable heat dissipation meets new Underwriters' Laboratories standards for use of 75 deg C. wire. Water column body has all tappings for steam trim. For man'ual reset order No. 192-M. No. 1S7 No. 157 is the same as No. 150 but has integral water column which simplifies installation and has all tappings for steam trim. No. 157 has automatic reset; for manual reset order No. 157-M (Tri cocks and gage glass not included.) No. 92 is same as No. 192 but without water column body; is installed with 1} in. equalizing tappings. For manual reset order 92-M. 1571 McDonnell & Miller, Inc. Heating Systems McDONNELL No. 27 Make-up Water Feeder for Receivers Teams up with McDonnell No. 150 or No. 157--assures an ade quate minimum supply of water in receiver at all times. Fea tures large feeding capacity, well-guided valve action, all brass construction of valve assembly. Models also available without float bowl for mounting right inside of receiver. Max imum receiver pressure, 35 lbs; maximum supply pressure, 100 lbs. (3) HOT WATER SPACE HEATING BOILERS Service Recommendations Boiler Water Feeders and Feeder Cut-off Combinations BoQer Size (Btu/hr Output) Differential Pressure 10 lbs* Differential Pressure 20 lbs* Differential Pressure 30 Hm* Mnyimiim Boiler Pressure 1,000,000 2,000,000 2,800,000 2,100,000 1.400.000 3,000,000 4.300.000 2.800.000 1,800,000 3.750.000 5.600.000 3.300.000 30 lbs 35 lbs 35 lbs 75 lbs Differential Pressure equals water supply pressure less boiler pressure. McDonnell Product to Use For Automati cally Fired Jobe For Hand Fired Jobs No. 247-2 No. 51-2 No. 51-S-2 No. 53-2 No. 247 No. 51 No. 51-S No. 53 Low Water Fuel Cut-off (only) (/or Automatically Fired Jobs) McDonnell No. 63. For boilers of any size. Maximum Boiler Pressure, 50 lbs. ASME Safety Pressure Relief Valves Boiler Size (Btu/hr Output) Opening Pressure McDonnell Product to Use. 303,000 743,400 1,025,100 1,488,000 1,928,400 30 lbs 30 lbs 30 lbs 30 lbs 30 lbs No. 230 % In. No. 230 1 In. No. 230 1M InNo. 230-MI No. 230-M2 McDONNELL Boiler Water Feeders and Feeder . Cut-off Combinations Experience has shown that hot water heating boilers, just like steam boilers, can run into low water trouble--as a result of leakage in the system, prolonged discharge from pressure relief valves, or simple negligence. Best answer is a McDonnell feeder cut-off combination for automatically fired boilers, and a boiler water feeder for hand fired jobs. No. 247-2 is a modifi cation of the dependable 47-2, but without "Quick-Hook-Up." No. 51-2 and No. 53-2 are larger capacity and higher pressure feeder cut-off combinations. (No. 47-2, 51-2 and 53-2 are de scribed under "Low Pressure Steam Boilers.") McDONNELL No. 63 Low Water Fuel Cut-off Suitable for boiler pressures to 50 lbs, the No. 63 is ideal for cut-off service on hot water boilers. Has time-tested No. 2 low water cut-off switch, center pivoted bellows construction. Underwriter's Laboratories approved. Can also be used on steam boilers. 1572 No. tp-t McDonnell & Mill r. Inc. Heating Systems % * Boiler Water Lever Controls Afanifold Type tSO Series McDONNELL 230 Series ASME Pressure Relief Valves for Hot Water Space Heating Boilers The 230 Series was developed to provide dependable protection against over pressure at a moderate price. Each valve in the series conforms to-ASME Boiler Code in every respect, and has been certified, and Btu-rated by the National Board of Boiler and Pressure Vessel Inspectors. All operating parts are of noncorrosive materials. Valve seat is brass, valve disc of sili cone. Testing lever is independent of valve action, cannot in terfere even if tied down. All connections are internal tappings. Five sizes are available, three individual valves and two manifold valves. These manifold valves offer two units, set to open at progressively higher pressures, on a common mani fold; they have the advantage of keeping discharge from larger boilers in step with the actual need, avoiding water waste when only a small discharge to take care of thermal expansion is required. (4) DOMESTIC HOT WATER TANKS AND HEATERS Service Recommendations Opening Pressure 75 lbs 100 lbs 125 lbs 150 lbs ASME Safety Pressure Relief Valves Capacity Btu/hr McDonnell Product to Use 502,000 640,000 783,000 925,000 No. 230-75 No. 230-100 No. 230-125 No. 230-150 McDONNELL 230 Series Pressure Relief Valves . ' For Hot Water Tanks and Heaters Used to guard against dangerous over-pressure, the McDonnell 230 Series valves conform to the ASME Boiler Code and have been tested and Btu-rated by the National Board of Boiler & Pressure Vessel Inspectors. Available with four standard open ing pressures. Construction features non-corrosive materials for all operating parts, independent action test lever, internal tappings for connections. For larger hot water tanks, two and three valve assemblies are available, up to 125 lbs maximum pressure. McDONNELL No. 201 Temperature Relief Valve Safeguards hot water tanks and heaters against excessive temperature. A.G.A. listed for heat input to 1,200,000 Btu/hr. Vernatherm element provides positive operation, drip tight reseating. Extra connection for fixture flow simplifies pipe hook-up, improves operation. In regular or dip tube models. McDonnell No. 202 Combination P-T Relief Valve Combines working mechanisms of 230 Series and No. 201; safeguards hot water tanks against both pressure and temper ature. Bears the ASME symbol. Pressure side is steam-rated by the National Board of Boiler & Pressure Vessel Inspectors-- 650,000 Btu/hr at standard 125 lbs opening pressure. Temper ature side is listed by A.G.A. for heat input to 750,000 Btu/hr. Opening pressures of 75 and 100 lbs also available. 1573 Heating Systems Boiler Blow-down Separators Pennsylvania Separator Co. Box 348H, Brookville, Pa. Mfgrs. of Boiler Blow-down SEPARATORS Pennyslvania's Separators utilize the velocity of the boiler blow-down in jected tangentially into the tapered cylinder to separate heavier water-sus pensions from flash which is forced to center vent. Thus excess pressure and temperature are removed by venting, leaving remaining water and suspen sions acceptable to most drains. Water suspensions are directed by Spiral Baffle to drain. When requested, units will bear ASME Code Stamps at extra cost. The unit meets national and most state and local requirements. Stainless Steel "Striking Plate" reinforces Separator at blow down entry to greatly extend life of unit. State boiler operating pressure and blow down valve size when making inquiry. Consult the table for size. Prices and additional information on request. SEPARATOR INLET SIZE TO EQUAL BOILER BLOW-DOWN VALVE SIZE AVAILABLE SIZES Inlet r 1M" 2" 2H" Drain 2" VA" 3" 4" 4" Vent 3" 4" . 6" 6" DIMENSIONS TOP--12* BOTTOM--14' HEIGHT--(200 (34') SUGGESTED HOOK-UPS FIG. A A popular and simple installa tion with the Separator installed below the blow-down valve. It pro vides ready drainage and blow downs at all pressures or from a dead boiler. FIG. B Elevated Separator installation when boiler room floor space is not available. May be installed indoors or outdoors for Separator is selfdraining--no freezing. 1574 FI G.C Where Receivers are required, they may be open tanks, or vented closed tanks 4'-$' vent. Manual or siphon drainage may be pro vided. Boilers, Heating Systems Packard Water Conditioner Division, Inc. Packard Manufacturing Company Post Office Box 719 Jacksonville 1, Florida SPECIFICATIONS* The Packard Water Conditioner elim inates and prevents corrosion and scale formation in boilers and water systems. It is an important commercial applica tion of nuclear physics principles to the effective treatment of boiler feed waters --without the use of chemicals. The Packard Water Conditioner prevents scale and corrosion by imparting added energy to the atoms of the water solu tion. The unit is easily installed. It has no moving parts and requires no expensive maintenance or servicing either in the form of labor or added chemicals. Use of the Packard Water Conditioner reduces operating costs and increases plant efficiency, minimizes shutdowns for maintenance and repair. Laboratory and field tests substantiate the theoretical and practical value of the device. Complete boiler protection is assured by installing Packard Water Condition ers to treat both the raw water and con densate return lines. Flow rates should be carefully determined and provision made for variations in pumping capacity caused by changes in back pressure. All feed water will be conditioned when a single Packard Water Conditioner is in stalled between the feed pump and the boiler. Capacity of the Conditioner should be great enough to handle the maximum output of the pump. The Packard Water Conditioner is manufactured in sizes handling from 6.5 , to 1760 gpm for connection with cor responding standard iron pipe ranging from % in. to 12 in., as shown in chart below. Conditioners are guaranteed for a period of ten years. - Capacity GPM 6* 13 20 40 52 80 106 . 185 265 440 660 990 1760 Industrial Price S199.50 299.50 449.50 595.00 875.00 1295.00 1725.00 2895.00 3395.00 4185.00 5150.00 5895.00 7625.00 - Type Screwed * " 1 One Screwed One Flanged Flanged * * Engineering Data Diameter Connec tion (IPS) r it' 4' ir 54' y 54' 54' T 84' 9*' 19* 20' .24' 30* 36' 4' 5' f' 10* 12* Length 26' 28' SO' 40' 41' 42' 43' 49* 02' 63' 101' no* 125' Carton 6 6 4 4 1 1 1 1 1 1 1 1 1 Shipping Weight Each 9 lbs 18 lbs 23 lbs 65 lbs 80 lbs 83 lbs 185 lbs 300 lbs 730 lbs 750 lbs 1110 lbs 1780 lbs 2390 lbs Note; All sizes 200 PSI WP on all screwed. All others ISO PSI WP. For all sizes up to 40 inches write fac tory. For heavy duty units to withstand pressure up to 1,000 lbs, add 25 per cent to cost. 1575 Heating Systems Burners, Gu Gordon-Piatt Inc. P. O. Box 914 Winfield, Kansas Combustion Engineering GPH Inshot Burner GPV Upshot Conversion Burner Glow Top Burner GORDON & PIATT are combustion en gineers, specializing in the design and manufacture of a complete line of Do mestic, Commercial and Industrial Burners. Engineering Service available for customer convenience. GPH-INSHOT GAS CONVERSION BURNER, designed to replace Gun-Type Oil Burners without alteration of com bustion chamber. Four inch tube; 75,000 to 150,000 Btu hr input; A.6.A. Listed. See Cat. GPH-1 GPV-UPSHOT GAS CONVERSION BURNER, for Domestic Heating Plants. Annular Slot Head. No Burner parts in flame, adjustable length, 75,000 to 350,000 Btu hr A.G.A. Listed. See Cat. GPV-1. GLOW TOP BURNER to convert large Commercial Heating Plants and Power Boilers. Standard firebrick completely covers cast ports. Shape and capacity flexible. 45 sizes listed in Cat. GT 55-1. Other sizes on application. TYPE H INSHOT ATMOSPHERIC BURNER, for Marine Boilers and other applications where horizontal flame is indicated. 30 sizes listed in Cal. H-l, others on application. TURBO-FIRE POWER TYPE GAS BURNER. Refractory nozzles and dis tinctive air distribution giving desired flame characteristics. Factory assembled with prewired control panel. Sizes listed to 18,000,000 Btu hr in Cat. FG-1. Also available dual fuel, gas-oil and gas-gas combination units. Write for de tails. Type H Inehot Burner 1576 Heating Systems Burners, Gas Roberts-Gordon Appliance Corp. CONVERSION GAS BURNERS DEPARTMENT HVG GAS HEATING EQUIPMENT Buffalo 6, N. Y. NEW! MULTURI (Multiple Venturi) GAS BURNER * f ';. Especially designed for HARD-TO-FIRE . SCOTCH MARINE BOILERS STEEL FIRE BOX BOILERS AT HIGH FIRING RATES AT HIGH EFFICIENCY ` A Premix Type Gas Burner, ideal for commercial and industrial size boilers and warm air furnaces. Gives maximum performance from hard-to-fire Scotch Marine and steel fire box boilers. Flame characteristics make the burner ap propriate for units with extensive re fractory surface. Suitable for any gas at 4 in. gas pressure or more. Permits high firing rates at high efficiency. Simple to install, adjust, and operate. Completely Factory Wired and Assembled ... Ready for Immediate Installation! MULTURI BURNERS are available in standard modular units of 6 to 54 mixers. Capacities from 1,200,000 to 10,800,000 Btu/hr. Special units of higher capacities can be furnished. Write or phone us for detailed information. NEW! COMBINATION GAS-OIL BURNERS 362,000 to 4,300,000 Btu/hr. 2%0 to 30 Gallons of Oil . Completely Automatic Switch-over from 1 Fuel to Another. Write or phone for details. ROBERTS-GORDON APPLIANCE CORP., DEPARTMENT HVG * BUFFALO 6, N. Y. 1577 Heating Systems Burners, gm The Sonner Burner Company Designers and Manufacturers of Gas Conversion Burners and Unit Heaters Offices and Factories: Winfield, Kansas Type L~6t Heal Machine Type LV SOMMER Burner Type D SOMMER Burner Sonner Gas Conversion Burners are a product of a quarter century of speciali zation in design and manufacture. A wide range of designs provides a Sonner Burner for domestic, commercial or industrial use. Consult Sonner Engi neering for advice. TYPE L-S2 HEAT MACHINE is designed specifically for the conversion of resi dential heating plants to gas. Com pletely automatic burner is A .G.A. listed. Available in two sizes with capacities ranging from 75,000 to 400,000 Btu/hr. See Cat. 52-L-2. .. TYPE LV SONNER BURNER for large heating and power boilers, handles a wide range of fuels. Standard assemblies from 320,000 to 7,200,000 Btu/hr are described in Cat. 52-LV-l. Step fired as semblies are described in Cat. 50-LVS-l. TYPE D SONNER BURNER offers com plete flexibility for all types and sizes of boilers and plants. Type "D" Burner Units can be readily manifolded into exactly the correct size and shape of burner for any kind of firebox. See Cat. 49-D-l. TYPE X-54 SONNER BURNER spe cifically designed for replacing gun type oil burners in domestic furnaces or oil boilers. A.G.A. listed with inputs rang ing from 75,000 to 175,000 Btu/hr. See Cat. 54-X-l. GAS OIL UNIT FOR COMMERCIAL AND INDUSTRIAL BOILERS, two fuel burning units each designed for one fuel --natural gas, light fuel oils. Standard assemblies 280,000 to 2,800,000 Btu/hr input. See Cat. 52-CU-l. Type X-6i Burner 1578 Sonner Gas Oil Unit Heating Systems Burners, Gas The Webster Engineering Company 115 South Frisco St., P.O. Box 2168 Tulsa, Oklahoma Division of SURFACE COMBUSTION CORPORATION, TOLEDO, OHIO WEBSTER KINETIC* Low Pressure Atmospheric Gas Burner with full venturi mixers and Meehanite alloy flame retention nozzles. Compact and easy to install, the assemblies are available in any desired size and shape. WEBSTER CYCLONETIC* The Webster Cyclonetic* Dual Fuel Burner is designed to operate on either gas or light oil with only the flick of a switch necessary to change from one fuel to another. Employing 100 per cent forced draft, the Cyclonetic* provides fully automatic operation on both fuels with complete programming and safety built in. Capacities from 675,000 to 4,000,000 Btu/hr. WEBSTER ROTONETIC* Dual Fuel Burner utilizing low pressure gas and any grade of commercial fuel oil under forced draft. Completely as sembled, wired and tested at the factory; the units are available to 400 horse power. WEBSTER DYNETIC* Forced Draft Gas Burner. A completely packaged unit available from 800,000 to 14,000,000 Btu/hr with low pressure gas. WEBSTER ALSO MANUFACTURES: Series F600 and Series 650 Vertical Gas Burn ers for Heating and Power Boilers. Series 340 Gas Burners for Vertical Boilers. Series VI and Webster Rectilinear High Pressure Inspirators for Boilers, Kilns, Stills, Dryers,"Etc. Series 200 and Series R Combination Gas and Oil Burners for Power Boilers. SALES and SERVICE IN ALL PRINCIPAL CITIES * Trade Mark 1579 !I Heating Systems Gumdon Cleaver-Brooks Company 498 E. Keefe Ave., Milwaukee 12, Wisconsin Cleaver-Brooks oil, gas and combination oil and gas burners for commercial. Industrial and institutional applications. Use tbe most available and most eco nomical fuel in your area. Burn oil, gas or combination oil or gas with equal efficiency. Cleaver-Brooks conversion burners can be installed as easily as domestic burners to fire any acceptable boiler. Recom mended for buildings containing over 1500 sq ft of radiation--or if 45 tons of coal .or more than 6000 gallons of oil are burned per year. SPECIFICATIONS, RATINGS AND CAPACITY___________ ___ Models AL3-C A M 3 -C H ,AM3-CF AL4-C A M 4 -C H AM4-CF A M 6-C H A M 6-C F A M 7-C H AM7-CF Oil - oQO >-323S GO ss Max. oil (gph) 5 11 17.5 25 40 60 Min. oil (gph) 1 1 3 5 6 8 Max. boiler rating Net standing Steam radiation 1750 3800 6100 8750 14000 21000 GAS .Net standing Water ^ radiation 2800 6000 9800 14000 22400 33600 Fuel oil No. 1, 2, 4 or 5 with maximum point of 10 F and maximum viscosity of 300 SSU at 100 F. Uses natural, mixed pr manufactured gas. 9 models available. COMBINATION LIGHT OIL OR GAS Combination burners have same Btu output, burning gas or oil as regular HEV-E-OIL burners. OIL Gas Combination Oil/Gas G2-H G3-H G4-H G2 G3 G4 G5 G6 G7 GL2- GL3- GL4- GL5 UL6 GL7 H HH GL2 GL3 GL4 Combination % 5 Oil/Gas AMG AMG AM AM 3-H 4-H G G .V 6HH AM AM AM AM G3 G4 G5 G6 Specifications for Gas Max. Btu (in lOOO's) Gas burned 7200 1500 2500 3600 5700 8600 Max. recom 1750 mended connected load (EDR Steam) 3800 6100 8750 14000 21000 Specifications for Light Oil (Capacity in gph) Max. Oil cap. (gph) 5 11 17H 25 40 60 Min. Oil ` 4M 10 5 8 13 12 cap. (gph) Specifications for No. 5 Oil (Capacity in gph) Max. Oil cap. (gph) 11 17M 25 40 60 Min. Oil cap. (gph) 1 3 568 mounted relay. AMCH Burners use Honeywell R890C electronic relay--delayed start with thermostat, post purge 15 models available. Burners equipped with automatic electric ignition. Motor starter delayed until oil at nozzle is hg&ted, No expensive pilots needed. and high-low air solenoid valve. AMCF Burners use combustion controls Fireye FJ-2 electronic relay with immediate shut-down on flame failure, and non-return of ignition to pjeet Factory Mutual requirements.. . mo Heating Systems Burners, on Enterprise Engine & Machinery Co. A SUBSIDIARY OF GENERAL METALS CORPORATION 18th & Florida Streets, San Francisco 10, California Distributors in Principal Cities ENTERPRISE HORIZONTAL ROTARY BURNERS--OIL, COMBINATION OIL--GAS BURNER CAPACITIES-UM.OOO BTU OIL 1,000 BTU GAS aN 3 os z Oa03S Ph H G-3O ojj OS oOBOaS j* o OcoPwS O aft, Oah o03 OS g* a ts aPPhS<-Bg3 2Q OS 3 "GO gCL 9 AA A C w w 1475 600 1,050 2,250 251303 31,,280000 6,950 1251,,,811822000 1,247759005 EF G JH LK M H ?14 20 28 3550 34,,020000 5,250 7,500 67 93 111666 192,,391300 2136,;10275fr 14,900 20,700 2356,,890000 2,310 3,270 45,,070205 332 5 17000 210350 1105,,500000 3200,,020500 234335330 666 346262,,,325959000 92,575 51,800 17040,,000000 148,100 8,040 11,490 15,525 22,975 to burn either fuel oil or gas. Gas may be natural, manufactured, or L. P. gas. All maximum capacities are necessarily approximate. Burners installed with adequate draft provisions and correct furnace volume, properly designed, will de velop capacities indicated, at sea level. APPLICATION STANDARD EQUIPMENT All full-automatic burners are furnished with; V-Belt drive, with known advan tages of standard electric motors. Gas-electric ignition--dual ignition on Enterprise Horizontal Rotary Burners sizes G to M. ' are specifically designed for Commercial Interconnected linkage to provide pro and Industrial use. Commercial heating portionate mixing of oil and air or gas includes heating plants in all types of and air at all firing rates. buildings larger than private homes, Optional open type or angular vane air including apartment houses, hotels, hospi nozzles for flame control. tals, schools, greenhouses, public build Copper tubing--provides free flow of. oil ings, offices, manufacturing plants. Indus with minimum connections. trial applications include furnaces, kilns, Operating and combustion safety con driers, etc. trols--oil burners, temperature or elec MULTIPLE TYPES Manual--To be started, regulated and stopped by operator. tronic type--Combination Oil-Gas burn ers, electronic controls exclusively. SPECIAL FEATURES Semi-Automatic--Started and stopped The Enterprise P. D. Metering Pump by operator, but automatically regulated provides exact delivery of oil to the by temperature or pressure control. burner by positive displacement, rather Full-Automatic--Burner automatically than through a metering valve. This defi starts, stops, and is regulated to provide nitely insures correct oil supply and air desired temperatures or steam pressure. proportioning regardless of the viscosity Fixed fire start available on smaller of the oil, resulting in high efficiency. sizes. Low fire start for high-low or full Burner hinges are provided with leak modulating control on all Bizes. proof "O" rings rather than conven All burners available with either Stand tional packing glands. ard gear pump or P. D. Metering Pump or Non-pump (for use with separate pump set). Any grade of fuel oil is burned efficiently --No. 6 (Bunker C) fuel is burned by burners equipped with oil heating sys tem. COMBINATION OIL-GAS BURNERS FULLY APPROVED All Enterprise Burners have been tested, approved, and listed as standard by Underwriters' Laboratories, Inc. and by other recognized boards and bureaus of safety, measures, and controls. ENGINEERS will be provided with complete engineering information, either All of the above types of burners are by manufacturers or qualified distribu incorporated in combination type burner tors, upon request. 1581 Heating Systems Burners, on S. T. Johnson Co. Builders of fine Oil Burners... since 1903 Residential Commercial Industrial Iohmoti Od 'IVUWlA, 940 Arlington Ave. Oakland 8, California Church Road, Bridgeport, Pennsylvania BANKHEAT BURNER Pressure - atomizing, fully - automatic. Built with top quality safety and operat ing controls. A time-tested burner nota ble for its economy, dependability and efficiency. Highly adaptable. Ideal for "conversions." Bankheat Burners power the complete Johnson units shown below. SIZE bh-oBH-OA BH-1A BH-2 BH-2A BH-3 BH-3A CAP. GPH J MAX BOILER RATING Min. Max. Steam Water Hp .8 1.0 2.0 3.0 4.0 5.0 7.5 2.25 3.0 5.5 7.5 10.0 15.0 18.0 900 1300 2300 3100 4150 6200 7500 1450 2100 3650 4950 6650 9900 12000 6H 9 16 . 22 30 45 54 BANKHEAT OIL-and-GAS BURNER in areas where low-cost gas is available on a part time basis Bankheat Dual-Fuel Oil-and-Gas Burners offer the utmost possible economy and efficiency. They are equipped with fine electronic auto matic controls. SIZE 0 0A 1A 2 2A 3. 3A MAX FIRING RATE MAX BOILER OUTPUT oa Gas CFH Steam Water gph 1000 Btn Sq Ft Sq Ft HP 2H 3 5H IVt 10 15 18 315 420 770 1050 1400 2100 2520 ' 900 1300 2300 3100 4150 6200 7500 1450 2100 3650 4950 6650 6900 12000. 6tf 9 16 22 30 45 54 Haallnx Home Heaters 66000 and 160000 Bln Heating Systems Burners, on S. T. Johnson Co. Builders of fine Oil Burners... since 1903 Residential Commercial Industrial J ohmon B&d ivum& 940 Arlington Ave. Oakland 8, California Church Road Bridgeport, Pennsylvania MODEL 53 fully AUTOMATIC METERING PUMP BURNER This revolutionary new heavy-duty Johnson Burner will automatically main tain a fixed Air-Fuel Ratio regardless of variations in oil temperature and vis cosity. This fact explains why the Model 53 Burner is so remarkably successful at starting up and operating automatically even when the oil in tank and lines is cold and difficult to pump. The Model 53 Burner is built with a positive-displacement Metering Pump, a 3-Way Magnetic Oil Valve and a high efficiency Suction Pump. Because it keeps fuel and maintenance costs down to a minimum, the Model 53 is excep tionally economical to own and operate. And already it has achieved an enviable reputation for dependability and faith ful performance. Model 53 Burners are available in 8 sizes as listed below, with either Direct Drive or Belt Drive. Dual-Fuel Oil-andGas models are also available as shown at at the bottom of this page. Model 68 Metering Pump Oil Burner SIZE AND BHP 25 50 76 100 150 200 300 400 MOTOR HP M H H M 1H 2 3 4 GPH OIL m 15 22U 30 45 60 90 120 SO FT STEAM RADIATION 3500 7000 10500 14000 21000 28000 42000 56000 Model 58 Metering Pump Oil Burner with Belt Drive MODEL S3 METERING PUMP DUAL-FUEL fully AUTOMATIC OIL-and-GAS BURNER Offers a choice of fuels in addition to the other advantages of the new Model 53 . . . thus making it possible in many areas to effect worth while fuel econ omies. Model 58 Metering Pump Dual-Fuel Od-and-Gae Burner 1583 Heating Systems oSgu Ray Oil Burner Co. . Since 1872 1301 San Jose Avenue San Francisco 12, Cal. Atlantic Seaboard Division G29 Grove Street Jersey City 2, N. J. There is a RAY Burner for every Heating Purpose. RAY FORCED DRAFT PACKAGED BURNER A factory assembled unit readily applied to any type of boiler designed for forced draft operation. Fully automatic operation on oil, gas or combination gas-oil. The combination gas-oil unit includes a rotary oil burner, integrated ring type gas burner, secondary air control with a forced draft fan, windbox, refractory support ring, completely wired control panel and pre-piping completely factory as sembled for quick and easy installation to the boiler. FD-ARC Size ft 8 fully Oil components may be selected to burn any grade of oil automatic, combination with the secondary air control providing increased efficiency gae-oa. Forced Draft even with the difficult-to-burn catalytic residual #6 fuel oils. Packaged Burner. From 83 to 540 equivalent boiler horsepower. RAY COMBINATION OIL-GAS BURNERS ARC-l-U Model 50 for heavy oil and how Pree- eure Gae Type PC for Oil and Low Pressure Gas Type AH-HN Combina tion Oil and High Pres sure Gas ARC-MODEL' 50. Consists of a rotary type oil burner of Ray conventional design coupled with a gas housing for low pressure gas, from 2 in. WC to 10 in. NO. The gas burner parts provide for the introduction of gas in a manner which fully utilizes the energy in the high pressure air supplied by the rotary burner fan. Gas and pri mary air are intimately combined, in two stages, before mixing with the secondary air which is introduced through a vaned annular opening concentric with the nozzle. Change-over requires less than one minute. Available to burn any grade of oil in 9 sizes with capacities to 31,500,000 Btu/hr. TYPE HN for gas pressures above 1 lb/sq in. may be used alone or in combination with a Ray Oil Burner. Built in ten sizes; in capacities to 48,000,000 Btu/hr. TYPE 5C. Combination gas-oil burner of the pressure atomizing type. Available in three sizes with capacities from 560,000 to 2,500,000 Btu/hr. RAY DOMESTIC AND MARINE BURNERS Fully Automatic, Type JP, US or lighter oil Steam Turbine Drive, Type TG, all grades oil. Tested and approved for V. S. Navy Service. Ray Warm Air Oil Furnace RAY PRESSURE ATOMIZING OIL BURNERS Fully automatic for No. 2 oil. or lighter. AC or DC; capacities 1 to 18 gallons per hour. WARM AIR FURNACES Built in five sizes, with input capacities of 105,000; 140,000; 230,000 ; 350,000 ; 450,000 Btu. . RAY OIL WATER HEATERS Five sizes. Capacities: 35,45, 60,75 and 100 gal. Maxi mum recovery rates: 100 to 240 gph. 1584 Heating Systems Burners Oil and Gas Ray Oil Burner Co. Since 1872 1301 San Jose Avenue San Francisco 12, Cal. Distributors in --. All Principal Cities of the World Atlantic Seaboard Division 629 Grove Street Jersey City 2, N. J. Consult your local Telephone Directory Products: A complete line of Horizontal Rotary and Pressure Atomizing Oil Burners; Combination Oil-or-Gas Burners; Industrial Gas Burners; Forced Draft, packaged Burners; Oil Burning Water Heaters; Warm Air Furnaces. Type AR-144 Size 10 for No. 6 oil. Available in 10 sizes from 2 to 210 gph. Fully automatic. Fully Automatic Type AR-184, for No. 5 oil. 1 to 1000 Boiler hp Type AO. Manual. Semi-au tomatic control. Type ARJP, Fully Autornatic for heavy oH where gas for ignition not available. RAY HORIZONTAL ROTARY OIL BURNERS Type BR-144> Belt Drive, Fully Automatic, Avail able in 8 sizes. Capacities from 2 to 110 gph. Built in fully automatic, semi-automatic and manual types; in sizes from 1 to 1000 Boiler hp; to burn all grades of fuel oil. Standard models include both direct and belt drives--the latter being recommended for use where other than 50 or 60 Cycles AC, or only DC is available. Types for straight elec tric or straight gas ignition; pump or gravity feeds. Direct drive types include a steam turbine driven model. All fully automatic types for heavy oil incorporate the Ray Dual Pump and Reservoir, with the Ray VISCOSITY Valve, a patented, exclusive feature which automatically meters the correct amount of fuel at all times, regardless of changes in viscosity of the oil due to temperature variations. All larger sizes employ dual ignition system, consisting of dual high-volt age transformers, dual electric ignitors and dual gas valves. Fully automatic sizes 9 and 10 include as standard equipment electronic pilot and flame failure control. HOURLY CAPACITY RATINGS of RAY OIL BURNERS . Motor ` H. P Burner Size >8 0-P H 1-P H 2-P H Oil Capacity U. S. Gallons Min. 1 3 8 Max. 3 4 8 18 Equivalent Boiler HP Min. 3 3 6 25 Max. 9 12 25 55 Equivalent Lbs. Steam Generated* . Min. Max. 110 325 110 430 325 860 860 1950 Heat Capacity Input Thou. Btu Oil or 1000 Btu Gas Min. Max. 140 420 140 560 420 1120 1120 2500 Equivalent Sq. Ft Steam Radiation Min. 440 440 1300 3500 1300 1750 3500 7900 0H 2 1H4 2a 5 3H 8 5 11 15 25 7 13 17 27 16 230 580 300 35 460 1270 600 50 580 1740 750 83 930 2900 1200 750 1650 2250 3750 938 1880 2340 3750 2340 5160 7030 11720 51 6 1H 72 83 10 12 15 25 35 50 70 110 33 40 50 83 116 1160 4050' 1500 165 1400 5800 1800 230 1740 8100 2250 365 2900 12700 3750 5250 7500 10500 16500 4690 5620 7030 11700 16400 23500 32800 51500 96 35 10 7M 50 12 m 75 150 210 320 116 500 4050 17400 5250 165 700 5800 24400 7500 250 1000 8700 37000 11250 22500 31500 48000 16400 23400 35100 70500 98300 149800 NOTE: These ratings are predicated upon specific conditions of draft and furnace volume. It may be per missible, under desirable conditions, to operate at higher rates, or advisable under restricted conditions, to operate at reduced rates. Heating capacities are based upon 150,000 Btu per gal of oil for rotary burners and 14Q0:,t0e0-a-0-m--B- c-tauppaecritgyab-l-ao-s-f-e-od>i-lo-if-nwo--ir-s`tppeireaesmsssauFurreeaaantdt*oommA---iiz-z2-1ii-nn-2-gg-F--bo.uurners and upon an overall boiler efficiency of 75 per cent 1585 Heating Systems oflners' Rayfield-Staffco Burner Co. 2066 S. Canalport Ave. Chicago 8, 111. DOMESTIC, COMMERCIAL AND INDUSTRIAL OIL BURNERS FOR ALL GRADES OF FUEL OILS, FOR SMALLEST TO LARGEST BUILDINGS. DOMESTIC AND SMALL COMMERCIAL AND INDUSTRIAL GAS BURNERS For No. 4 or No. 5 Heavy Oils For No. 5 or No. 6 Heaviest Oils RAYFIELD-STAFFCO BURNERS for No. 4 or No. 5 HEAVY OILS Model JR.--1.00 to 5.00 gph. Model D4--3.00 to 12.00 gph. Model D5--10.00 to 22.00 gph. Maximum 8,800 EDR These fully automatic burners are de signed to provide efficient heating with the cheaper grades of oil. Both models are all-electric operating, self-lubricat ing and have self-cleaning nozzles for long, trouble-free service. By utilizing the low-priced fuels, these units keep heating costs to a minimum. Ideal for smaller commercial and industrial ap plication. RAYFIELD-STAFFCO ROTARY BURNERS FOR No. 5 and No. 6 HEAVIEST FUEL OILS * 9 sizes ranging from 10 to 165 gph firing rates Maximum 66,000 EDR . These sturdy burners, known and used all over the world, give excellent results and are built for long life with minimum seryice. Available with many types of controls including mechanical, electrical and electronic types. All equipped with Regulating valves to maintain constant oil flow regardless of oil viscosity or temperature. Adjustable air vanes to produce any flame shape or size desired. SHELL COMBUSTION HEAD OIL BURNERS for No. 2 or No. 3 CATALYTIC OILS GUN TYPE GAS BURNERS 1586 Heating Systems Burners, Gas and Oil Siemon Manufacturing Company Grandview, Mo. (Suburb of Kansas City, Mo.) Representatives in most Principal Cities "POWER-FLAME" Gas Burners The "POWER FLAME" forced draft burners offer EXTREME FLEXIBILITY. "FG" series Gun Type units are ideal where limited space is a factor such as Scotch Marine type boilers, narrow fire box heaters and the like. fg Series--Gun Type . Series "BFG" units--Block Type--de signed for use where high capacities are required and minimum base heights for installation are available. Both types employ standard items of control equipment, are shipped as a package, factory wired and tested before shipment-. Ash for Cat. Nos. FG-105S and BFG-655 for complete specifications. bfg Series-- Spread-block type _______ - HOURLY CAPACITIES AND SPECIFICATIONS Burner Model Gas Input MBTU/Hr Min. Max. Gross Boiler Output 100% Rating Sq ft Sq Ft Steam Water Max BHP Gas Conn. Motor Hp Type Control FG175B FG330B FG500B FG500B-E 85 175 150 330 300 500 300 500 460 900 1420 1420 750 1400 2300 2300 3.9 7.3 11.1 11.1 W 1# V Ho Thermo-Relay Ho Thermo-Relay Ho Thermo-Relay Ho Electronic BFG-750E BFG-1000E BFG-1600E BFG-2200E BFG-3000E BFG-4500E BFG-6000E BFG-9000E 450 650 900 1500 2000 3000 4500 6000 750 1000 1600 2200 3000 4500 6000 9000 2250 3000 4800 6600 9000 13500 18000 27000 3600 4800 7500 10400 14500 21000 29000 43500 16 22 35 49 69 100 133 200 -j# 1M* \w V 2H# 3* 3' 4# H H U H H M H l Electronic A.G.A. Listed 1000 Blu Gas @ 3" W. C. Pressure--Availablefor Mixed or L. P. Gases * Bated on 70% Boiler Efficiency "COMBI-MATIC" Forced Draft GAS-OIL Burners Listed as standard by Underwriters' Lab oratories. The "FGO ' ' Series units employ a "tube within a tube" principle to fire both fuels (gas and light oils) efficiently. Installation costs are reduced to a minimum since all units are packaged and factory wired and "FIRE TESTED BEFORE SHIPMENT." All units are pressure atomizing type, SIMPLE TO INSTALL, SERVICE AND MAIN TAIN. Ask for Cat. No. FGO-9164 for complete specifications. HOURLY CAPACITIES AND SPECIFICATIONS Burner Model FGO-700A-E FGO-1000A-E FGO-1400A-E FGO-2200A-E FGO-3000A-E FGO-3500A-E Gas Input MBTU/Hr Min. Max. Gross Boiler Oil* 1.2,3 Output Gals, 100% Rating Max BHP per hour Sq Ft Sq Ft Steam Water Gas Conn. Motor Hp 400 700 1000 1400 2200 2800 700 1000 1400 2200 3000 3500 3- 5 5- 7 7-10 10-16 16-22 20-25 2100 3000 4200 6600 9000 10500 3875 4800 6750 10500 14400 16750 18 22 30 48 66 77 1H' IW W V 2H' 3' W H H H h H 1000 Btu Gas @ 3* W. C. Pressure--Available for Mixed or L. P. Gases . Based on 70% Boiler Efficiency Type Control Electronic Electronic Electronic Electronic Electronic 1587 Heating Systems Burners. gs nd on John Zink Company 4401 S. Peoria -- Tulsa, Okla. Shreveport New Orleans Corpus Christi Houston San Antonio Lubbock Fort Worth Los Angeles See other page for additional offices Heating Systems Burners. Gas ana oa John Zink Company 4401 S. Peoria -- Tulsa, Okla. JOHN ZINK" co. Boston New York Detroit Chicago Omaha Dallas Little Rock See other page for additional offices SERIES STY GAS BURNER Ideal for heating boiler installations. From one head to fifty heads. Quiet, efficient and economical operation. Write for literature. SERIES VR VERTICAL GAS BURNER * This burner is of the "upshot" or vertical radiant type with multiple burner heads so designed as to entrain a certain amount of primary air from the total air entering through the louvre. The "VR" burners are especially designed to operate in boilers having low draft and small combustion space. Write for literature. FLOOR FURNACES A size for every home heating requirement. Small grille--fool proof--simple to operate--A.G.A approved--sturdy construction. . Sizes--35,000; 50,000 and 65,000 Btu input. Write for literature. NEW SUSPENDED UNIT HEATER (Series U H S Fan Type) A.G.A. approved for Natural, Mixed, Manufactured or LP Gas. For clean, safe trou ble-free heating of industrial and commercial establishments. A complete packaged unit that is fully automatic. Conserves valuable floor space. Designed for an at tractive addition to any store or shop. Write for literature. SERIES YC COMBINATION GAS AND OIL BURNER The John Zink Series YC Combination Gas and Oil Burner is recommended for boilers and process furnaces where maximum heat release at low excess a^*_^ , high heat density is required. Features of the Series YC are Rugged/Weather-rr Construction; Easy to Remove Fuel Guns; Lightweight Fuel Guns; Burn Any O mercial Fuel Oil; Bum Any Gas at Reasonable Pressure; Draft--Natural, horceu or Induced; Center Firing of Both Fuels; Will Operate with Either Fuel as well as in Combination; Can Be Equipped With Any Standard Type Controls. . Also: SMOKELESS FIELD FLARE BURNERS 1588 CENTRAL GAS HEATERS (Horizontal-Vertical) A truly universal, efficient, simple and compact central heating unit. Fully auto matic, it is a complete packaged unit ready for installation. May be installed in the basement, attic, service closet or utility room. It is designed as a winter air conditioner with a summer switch to provide air circulation during warm weather. Two models available. Write for literature. Also: EVAPORATIVE COOLERS, CONVERSION BURNERS, ATTIC FANS ' 1589 Heating Systems Somers, oa York-Shipley, Inc. Main Office and Plants--York 16, Pennsylvania OIL AND/OR GAS-FIRED EQUIPMENT FOR INDUSTRY York-Power provides a complete line of economical automatic heating and processing equipment, gas or oil-fired, for every industrial and commercial need. York-Power Steam-Pak (illustrated) and Steam-Pakette Generators are designed for either low-pressure heating loads or high-pressure processing loads, from 15 to 500 hp using Nos. 3, 5, or 6 fuel oil, or gas. York-Power Horizontal Rotary Burners come in a wide range of sizes, from 45 to 400 boiler hp; oil or combination oil or gas fired. Burners take Nos. 3, 5, or 6 oil. York-Power Econol Burner, our latest oil-gas combination burner with improved low-cost operating features. Burns Nos. 1, 2, 3, 4 and 5 fuel oil. Available in two sizes: 36 and 75 max _ boiler rating hp at boiler outlet. York-Power Scotch Marine (Illustrated) or Firebox Boiler Burners for efficient, low-cost heating. Oil and/or gas fired. York-Power F/C (Factory Coordinated) Industrial Fuel Burn ing Systems now provide factory-packaged, industrial fuel burning systems, with all basic components pre-wired and mounted in position. Photo shows details of wiring,of main control panel. For further information write York-Shipley, Inc., or call the York-Shipley Distributor nearest you. 1590 Heating Systems % Eddington Metal Specialty Company Eddington, Pennsylvania Filters, Nozzles, Valves, Stabilizers & Air Cones, Strainers, Adaptors, Inspection Mirrors, Servicemens' Nozzle Kits, Combustion Heads HIGH PRESSURE COMBUSTION HEAD (HP-53) Developed especially to provide Air-Oil Mixture of Catalytic Fuel Oils at high - CO, ratings. Excellent results in field tests with both steel and cast iron furnaces. Ready adaptation to conven tional burners in field and by Oil Burner Manufacturers. Also available is a low pressure combustion head (LP-53) which converts high pressure oil burners to low pressure without change in housing design. ----- FUEL OIL FILTER For heating oils in pressure and gravity type oil burners, space heaters, water heaters, stoves and ranges. Light weight, sturdy aluminum construction. Stag gered surface of cartridge provides maximum filtering area. Easily replaced by loosening a single bolt and without interrupting pipe connections. Com pletely interchangeable with other makes. DIMENSIONAL SPECIFICATIONS OF FILTERS MODEL NO. HEIGHT S-252 6Hb S-254 5% DIAM ETER 4Hs 3Ke WEIGHT 1 lb 10 oz. 1 lb 5 oz. INLET % OUTLET SURFACE AREA 98 sq in. 72 sq in. UNDER WRITERS APPROVED -25 gph 25 gph OIL BURNER NOZZLE Stainless steel throughout with particularly high quality steel and finish of Tip, Disc, and Locknut for maximum wear and heat resistance. Supplied standard with Hollow (H), Semi Hollow (SH), and Solid (S) spray patterns. Custom made if so required for specific Combustion Heads, Boiler Burner Units, or Burners. Factory tested for spray angle, atomization, and actual rated capacity. 1591 Heating Systems Gas vent SI METALBESTOS Be Sure of Safe Gas Venting Use METALBESTOS-- the insulated vent Right for you ... because Metalbestos is easily and quickly installed. Precision made couplers slip together without forcing . . . are tightly and permanently sealed without using mastic or cement. Ad justable lengths, adjustable elbows and other versatile fittings speed assembly and eliminate wasteful cutting and fitting. Your costs are lower, profits higher, because with Metalbestos you can make more installations per man per day. . Right for your customers . . . because Metalbestos assures safe, trouble-free venting for the lifetime of the house itself. Double-wall design provides an inner "hot stack" to create a strong venting draft and prevent condensation ... and an air insulated outer pipe to protect adjacent wall surfaces from dangerous overheating Joints that stay permanently tight and sturdy damage-resistant construction are further reasons why you can install Metalbestos and then forget it. Send for free copy of VENT INSTALLATION HANDBOOK Based on the latest gas venting research, this pocket-size booklet contains com plete, up-to-date information on venting practices plus many helpful installation tips. Write today for your copy. No obligation. 1592 Heating Systems Gas vent METALBESTOS DIVISION iiMiir A11A Cl_C_0-MJ_A.st r__ a ruansi-miu_ specify METALBESTOS for all Type B venting needs RV Metalbestos Round Vent --for standard applications. WV Metalbestos Oval Vent --for in-the-wall venting " Approved by Underwriters' Laboratories for use with approved gas appliances. DOUBLE-WALL DESIGN . . . an inner "hot stack" for strong draft, minimum condensation ... a cooler outer pipe for maximum protection of surrounding wall areas. QUICK COUPLERS . . . and adjustable fittings for fast, low-cost installation. DURABLE CONSTRUCTION ... all metal, will never crack or break . . . makes a sturdy, tightly sealed venting system that will last the lifetime of the house itself. 1. Draft Hood Connector 2. RV Round Pipe 3. RV 90 Adjustable Round Elbow 4. RV Round to WV Oval Tee 5. WV Oval Pipe Typical Metalbestos gas vent installation for two-story structure. Refer to adjacent list for identification of carious sittings. SAFE, CORRECT VENTING FOR RECESSED WALL HEATERS Metalbestos Type B-W Gas Vent is listed by Underwriters' Laboratories, Inc. for use with recessed wall heaters. Installation in 2 x 4 stud walls is simple with no furring out or extra insulation required. The narrow double-wall gas vent measuring only 234 in. x 734 in overall in cross section, when centered in standard stud walls provides a full 34 in. clearance from adjacent material. Furnished in 4 in. size in 3, 4 and 5-ft lengths. 6. WV Oval to RV Round Adapter 7. RV Round Increaser 8. RV Round Tee 9. Type B-W Wall Heater Vent 10. RV 45 Adjustable Round Elbow 11. RV Round Adjustable Length 12. RV Adjustable Roof Flashing 13. RV Storm Collar 14. RV Belmont Top NOTE: RV Round pipe and fittings are furnished in sizes of 3 in. to 8 in. diameter. WV Oval Metalbes tos and Type B-W Wall Heater Vent are available in standard 4 in. size only. 1593 Heating Systems o"water American District Steam Division Adsco Industries.Inc. 20 Milburn St. Buffalo 12, N. Y. . Plants, Buffalo, N. Y.--Richmond, Calif. EXPANSION JOINTS--HEATERS HEAT EXCHANGERS--STRAINERS SEPARATORS INSTANTANEOUS HEATERS Adsco instantaneous heaters are made in a large variety of types, including the simple U-bend instantaneous shown above, which is used to heat water for showers, dishwashers, laundries, and other purposes. These heaters are also used as Convertors for furnishing hot water to space heating systems. Many straight-tube, float-head units are used as closed feed-water heaters,' boiler blow-down heaters, and for vari ous uses in the process industries. STORAGE HEATERS Adsco storage heaters are built in ac cordance with the ASME code for work ing pressures desired. Tanks are made of flange-quality steel, nickel-clad, or stainless-clad steel, or copper silicon alloy. Where alloy tanks are used, tube sheets are of non-corrosive metal, so that service water does not come in contact with any ferrous parts. Steel tanks can be lined with Adsco Phenolic 6-2 or Adscote bitumastic to prevent corrosion. All units\are equipped with cold-water spreaders \ Manholes are heavily rein forced. Copper U-bend heating element is easily removed for cleaning. TANK SUCTION HEATERS Adsco tank suction heaters reduce vis cosity of heavy oil or other fluids so they can be pumped economically. Instead of employing pipe coils on the bottom of the tank to raise the temperature of all the liquid, only the liquid to be pumped is heated. Steam waste is eliminated. These heaters are furnished with nozzle for welding into storage tanks or with flange for bolting to existing flanged nozzle. OIL PRE-HEATERS Adsco oil pre-heaters help obtain the highest performance from fuel oil by heating it properly for complete com bustion in the burner. In many cases, the work done by oil pre-heaters permits the use of heavier grade, less costly fuel oil. These heaters frequently are used with Adsco tank suction heaters, the two units making an efficient team. STRAINERS Adsco strainers remove dirt, scale and other foreign matter from steam, gas, air, water and oil lines. Their installation ahead of every regulator, pump, valve or trap protects this delicate equipment, reduces maintenance and prevents ex pensive shut-downs. Type Y strainers with flanged ends, left, have large screen surfaces and are easily cleaned. Sizes in. to 14 in., pressures to 600 psig. . Type S strainers, right, are usually in stalled on suction side of pump. Five cover designs are available: lever and toggle, toggle and bolt, clamp, through bolt, and stud-bolt. Adsco separators (not shown here) re move moisture, oil and small solid mat ter from steam, air and gas lines. Avail able in vertical up-flow and down-flow as well as horizontal types. Sizes to 10 in. and pressures to 300 psig. 1594 Heating Systems sSZe'*' Aerco Corporation Paris Avenue, P.O. Box 248 Northvale, N. J. AERCO's Controlled "HTR" (Heat Transfer Rate) Heat Exchanger is a Compact Storage Water Heater featuring an Internal Compensator which: Anticipates changes in required steam flow before the actual heat transfer takes place. Meiers the steam flow accurately in direct proportion with load. Prevents surges in steam flow, elimi noting need for large storage. Maintains ACCURATE control of out let water temperature. Prevents OVERRIDE of outlet tem perature on sudden interruptiort of water flow. For UNIFORMLY VARYING LOADS (i.e. Hospital General Water Supply), the ability of the above heater to prevent steam flow surges ELIMINATES the need for large STORAGE. For NON-UNIFORMLY VARYING LOADS or periodic high peak flows and low average demands (i.e. Small Commercial Laundry), the AERCO COMPACT STOR AGE WATER HEATER with an Accumulator and Recirculating Pump (as shown in Figure 2) gives a low cost combination which also permits: Minimum storage volume for peak de mands. Minimum steam input for required load. Accurate controlled outlet water tem perature under all load conditions. CONSTRUCTION Shell fabricated to ASME Code Standards, of Flange Quality Steel with plastic or copper lining. Shell ends Cast-iron or Bronze. Internal parts of Copper or Brass. Tested for 125 psig operating pressure. Capacities, 300 to 25,000 gph. OPERATION Cold water enters top, flows 3own through the Compensator, then up across steam coils to discharge at top. Steam feeds into coils through Steam Riser and leaves through Condensate Return. Compensator anticipates and controls heat transfer rate by sensing changes in flow or incoming temperature before water passes over the heating coils. It accom plishes this by causing variations of temperature to occur at the Regulator bulb which are definitely related to changes in flow and incoming temperature as well as the final temperature. Send for booklet: "THE NEW APPROACH To the Design of Hot Water Supply Systems" and Bulletin <22 for capacity data and sizes. 1595 Heating Systems Hot Water Heating Heat Transfer General Fittings Company Box 15 IK, East Greenwich, R.L, U.S.A. HOT WATER HEATING AND HEAT TRANSFER GENERAL Instantaneous Water Heaters For continuous supply of hot water, for industrial service or processes, apart ments, hotels, etc. No storage tank. Two types: steam or boiler water through shell instantly heats water drawn through copper coils as needed. Capac ities to 300 gpm. GENERAL Fuel Oil Heaters Baffle-type heaters for use with live steam, exhaust steam or boiler water through tubing; fuel oil through heater shell. U-type heaters for water-through shell, oil-through tubing. Capacities to 2,000 gph. 'X GENERAL Converters Compact, efficient heaters for supplying forced hot water heating systems. Two types available: for use with constant steamjmupply, or for mounting below boi^r water level. Capacities to 9,000,000 per hr. GENERAL Indirect Horizontal heaters for use with largesize storage tanks. For use with steam source or below water-line installation on heating boilers. GENERAL Coil-Heated Tanks Black Iron or Galvanized. Boiler water or steam through coils. Heater easily removable for cleaning. WRITE FOR CATALOG 61 OF FLUID-HEATING SPECIALTIES 1596 Heating Systems Water Heaters Radiation, Oil KI HEBREW Engineering ~ '-wagon*--- " Corporation 8640 Pardee Lane, Saint Louis 23, Mo. ASME FABRICATION FRE-FLO INSTANTANEOUS WATER HEATER Easily cleaned, straight tube, .with re movable cover plate and floating head. Designed for heavy loads and fouling fluids. Standard sizes from 50 gph up. HEATER Steel (rust resistant lining optional) or alloys. Copper tubes on square pitch or flat bundles to set low in tank for use as condensate cooler or used where heavy fouling requires complete access for cleaning. FRE-FLO RADIATION CONVERTER Complete range of sizes. Used with steam or boiler water. Cast iron head, steel shell, copper U tubes and bronze tube supports or baffles. _ FRE-FLO LOAD LEVELER A simple, rugged, packaged water heater designed specifically for handling extreme surge loads, yet levels Hie steam load on your boiler. Will deliver one or two temperatures of your se lection, individually controlled. The Fre-Flo Load Leveler is completely assembled, ready to connect to utilities. Sizes from 450 gph and up. WRITE US REGARDING YOUR HEAT EXCHANGE PROBLEMS FRE-FLO CATALOG AVAILABLE 1597 Heating Systems Hot water Bell and Gossett Company Morton Grove, Illinois HYDRO-FLO HOT WATER SYSTEMS AND SPECIALTIES B & G Booster Pumps The B & G Booster is the basic unit of a B & G Hydro-Flo Forced Hot Water Heating System. It is built as a hori zontally driven unit for sound engineer ing reasons which have demonstrated their practical value in thousands of installations. This construction makes possible many desirable, exclusive fea tures. For example, the patented water tight Seal eliminates need for a stuffing box. This Seal positively prevents entry of water into bearings. Shaft is of highly polished, hardened machine steel. The close-fitted Impeller makes every revolu tion count by holding water slippage to a minimum. B & G Flo-Control Valves This valve, installed in the main, shuts off circulation to radiators when heat is not needed, permitting summer opera tion of a B & G Indirect Water Heater. It also helps maintain a uniform room temperature during the heating season. B & G Monoflo Fittings B & G Monoflo Fittings permit the use of a single pipe main instead of the conventional flow and return lines. They are installed at the junction of the radiator risers to the single main and assure the diversion of the proper amount of heated water into each radiator. Savings in space, labor and materials are obviously effected. Avail able in cast-iron and copper. , B & G Motorized Valves Thermostatically operated valves usgd toTcontrol boiler water flow through indi^ridnal circuits of zoned heating svstems. B & G Boosters have a genuine oilcirculating lubrication system--one of the greatest reasons for quiet, depend able, economical operation. Oil is drawn up from the oil well by wool fibre wicking and dropped on the horizontal bearing surfaces. Medium grade motor oil is used and only a few drops at infrequent intervals are required. SEE THE B & G HANDBOOK FOR COMPLETE DESIGNING DATA B & G Universal Pumps Designed for forced hot water heating systems in apartment and office build ings, factories, schools, etc. The Uni versal is not an ordinary centrifugal pump, but is specially designed to assure quiet operation, so essential in heating system applications. 1598 Bell and Gossett Company Heating Systems HOT WATER SYSTEMS AND SPECIALTIES B & G Relief Valves Designed and built to ASME require ments, Tested by National Board--la belled, with ASME symbol. For relieving excess boiler pressures in hot water heating systems, and in the lines of service water systems. B & G Relief Valves have the design features which assure dependable service. B & G Type "WU" Heat Exchangers B & G Reducing Valves All working parts bras3, with built-in strainer. Easily adjusted to meet vary ing building heights. Also high pressure reducing valves for.protection of plumb ing fixtures. B & G Comfort Control System A shell and tube heat exchanger with hot boiler water pumped through the shell by a B & G Booster, making pos sible big capacity in a small unit. Pumping boiler water through the heater also affords excellent temperature control and permits use of much smaller pipe and fittings. B & G Type "SO" Heat Exchangers For heating water with steam. Ideal for industrial plants or wherever large volumes of hot water are required con tinuously for service water supply or process work. No storage tank required --the large heat transfer surface in these units heats water instantly as needed. Available in a wide range of capacities. B & G Centrifugal Pumps Outdoor type, wind-compensating tem perature control. The Regulator pro jects through the building wall, with the indoor end warmed by water in the radiation circuit. A small amount of this heat is conducted to the outside end, where it is dissipated at a rate dependent upon temperature and wind velocity. This heat dissipation governs the Control Valve, which permits hot boiler water to enter the system in required amounts. Design and construction based on years of experience in the industrial field. Rugged, compact units--built to withstand strain of continuous opera tion. Semi-open or enclosed impellers-- motors flexible coupled or integral with pump. Series 1522 illustrated. <-- B & G Refrigeration Components A very complete line of direct expansion evaporators, condensers, liquid re ceivers, combination liquid receivers and subcoolers for refrigeration and air conditioning. Special alloys may be incorporated in the units for those critical heat transfer applications. 1599 fI' Heating Systems Hot water H. A. Thrush & Company Peru, Indiana Representatives in Principal Cities FORCED CIRCULATING THRUSH FLOW CONTROL SYSTEM OF HOT WATER HEATING AND HEATING SPECIALTIES Thrush Flow Control System of Hot Water Heat assures continuous radiant heat whether used with radiant panels, convectors, radiant baseboards or radia tors. Circulation is forced and opera tion is entirely automatic. It automati cally compensates for outdoor weather changes. Hot water for kitchen, laun dry and bath, both summer and winter is provided by the heating plant boiler. Piping plans and engineering assistance are available to the trade. THRUSH WATER CIRCULATORS Forced circulating pumps for Hot Water Heating and Domestic Water Systems. Insure uniform heating. Quiet and efficient, long lived and vibration-free. Sealed-in lubrication. Made-in 7 sizes, % in., 1 in., 1)4 in., 1A in., 2 in., 2)4 in., and 3 in. Hi-Head Horizontal Thrush Water Circulators, designed for use with radiant baseboards, convectors, radiant panels, etc.2 which require higher heads, are also available in 1 in., 1)4 m., and Vertical with Air Tube 1A in- sizes. ' THRUSH FLOW CONTROL VALVES Special check valves for use on automatically fired boilers, automatically control circulation when installed with a Thrush Circulator. Close tight when circulator is not running prevent gravity circulation when heat is ^ot needed in the radiators. Available with Air Tube which vents air from boiler^into pressure tank, greatly improving heating efficiency by eliminating air froja the system. 1 in. through )A in. valves also available with solder type outlet uy&ns^Also made in angle type with or without air tube and in horizontal type for zoning. Made in six sizes, 1 m.; 194 m., 1A in., 2 in., 2)4 in. and 3 in. THRUSH PRESSURE TANKS NOW HAVE VACUUM BREAKER Genuine Thrush Pressure Tanks are air tight... tested under Tank preSgUre... and equipped with the convenient Thrush Vacuum WM Vacuum Brcaker Breaker at no extra cost; Easy to drain if waterlogged. Bronze or Iron H in. H in. and t in. THRUSH AUTOMATIC FILLING VALVES AND LOW PRESSURE RELIEF VALVES Whenever system pressure drops below 12 lbs, city water pressure will auto matically open the Thrush Automatic Filling Valve and admit water until the system is filled. Thrush Relief Valves protect heating boilers from excess pressures. Large metal diaphragm assures positive closing and opening. 1600 H. A. Thrush & Company Heating Systems Hot water ASME APPROVED NO. 46 THRUSH SAFETY RELIEF VALVE FOR HOT WATER HEATING SYSTEMS Rated output of 283,500 Btu based on steam capacity discharge. Primarily a water relief valve designed to serve double duty of relieving water, as well as steam should critically high tempera tures occur. Testing lever. 30 lbs pres sure. A in. inlet, 1 in. outlet. Patent No. 8,180,680 THRUSH WATER HEATERS Highly efficient heat exchangers or con . verters. Fifteen sizes, for Hot Water or Steam. Pressure up to 150 lb Water, 50 lb steam. Straight tubes readily cleanable. Provide Domestic Hot Water at low cost. Also used industrially for heating or cooling liquids. if:' 1 96 in. or 96 in. No. 75 THRUSH HIGH PRESSURE WATER RELIEF VALVES To protect hot water heaters, range boilers and automatic water heaters from excess pressure. Factory setting 85 lb. Adjustable at factory to 150 lb maximum. ' NO. 76 HIGH PRESSURE AND TEMPERATURE RELIEF VALVES The valve illustrated above at right has an added -safety feature. It not only guards against excessive pressures, but also relieves if excessive temperatures develop. A fusible element melts at 210 F. Both types are designed for use in the hot water outlet line. THRUSH MANIFOLDS AND BALANCING VALVES Thrush Manifolds save time, space and labor installing Radiant Heating. Avail able in 1 in. and 1A in. sizes, each with two, three or four ) in. or A in. threaded branch outlets. Also available in 1)4 in. and 1)4 in. sizes with three or five A in. solder branch connections. Ends have solder connections. Manifold with Balancing Valves as shown - above is used in return lines only. Used in'supply lines without valves. Balancing Valves permit individual filling of each coil, eliminate air quickly and save time. Two types, three sizes, % in., )4 in. or jl in. Flared fittings for % in. and )4 in. tubing. ADJUSTABLE THRUSH SUPPLY TEES FOR ONE PIPE SYSTEMS C. I. Patent No. 8,404,9! --Bronze Patent No. 8598148 Provide exact balancing of forced circu lating one-pipe hot water heating sys tems. Easily adjusted. When branch flow is cut down main flow is increased, not retarded. Available in bronze with solder connections for use with copper pipe and in threaded cast iron for steel pipe. Non-adjustable tees also available. NO. 5 HOT WATER AIR VALVE An inexpensive, dependable, automatic air vent for Hot Water coils, convectors, radiators, unit heaters, and high points of mains. Tapping )$ in., I.P.T. Air Valve lg in Box ) THRUSH TANK DRAIN Combines Drain Valve and Vacuum Breaker in one handy, inexpensive fitting. Removing plug admits air to permit quick draining of waterlogged tank. WRITE FOR NEW CONDENSED CATALOG TJTUih Chain 1601 ,-l yr n '.-8 ! Heating Systems * Hot water Taco Heaters, Incorporated 1160 Cranston Street, Cranston 9, R. I. TACO HEATERS OF CANADA, LTD., 4 Gilead Place, Toronto TACO CIRCULATORS Easy to service in the field. Available in a full line--% in. to 3 in. Motors are es pecially selected for quiet performance and low cost operation. TACO VENTURI FITTINGS Only one required per radiator on return ... use ordinary tee for supply. Power ful suction action draws water through radiator for positive circulation. May be used for above or below main radiation. TACO UNIVERSAL FLOW CHECK An accurately weighted automatic valve. Opens when circulator is running. Closes when thermostat stops circulator to pre vent hot boiler water entering system. For angle or horizontal application. TACO-MATIC VALVE Designed primarily to protect the per formance of a tankless hot water heater on a forced circulation hot water heating system. Also performs function of a re verse acting control, eliminating added cost. TACO PANELTROL Adjustable to deliver water to radiant heating panels for any temperature be tween 110 F and 150 F even though boiler water is kept at higher temperature for summer-winter hot water. TACO AIR-SCOOP Scoops air from ho water system by a series of baffles. Ai' is then vented to either atmosphere .Sansion tank, When system is , filled . .. vent radiators and high points once ... no return to job. TACO AUTOMATIC AIR VALVES TACO TEMPERING VALVE Taco-Vent is leak-proofed. A porous bronze plug limits the flow of water through valve. The Steam Vent elimi nates pinging, clicking or hissing. TACO RELIEF AND REDUCING VALVES Guards against excessively hot domestic hot water. Mixes cold water with hot water from Tqco Tankldss or storage heater to provide tempered water at fixtures. TACO WATER HEATERS, CONVERTORS AND CHILLERS Automatically maintains sufficient water and pressure in system. The new Taco ASME Relief Valve {% in.) handles 80 per cent of all hot water heating jobs, and is set to relieve at 29 lbs. Re Taco Convertors and Water Heaters pro vide hot water and radiation for commer cial and institutional heating purposes. Chillers are designed for chilling water in the air conditioning and refrigeration ducing Valve is factory set at 12 lbs. fields. Send for Catalog 1-99 for complete information and engineering data. 1602 ' Heating Systems AURORA* PUMP division ^ allKOlk THE HEW YORK AIR BRAKE COMPANY 40 LOUCKS STREET AURORA ILLINOIS Manufacturers of Turbine-Type, Vertical and Horizontal Centrifugal and Special Design Pumps Distributors tn Principal Cities - Barring Unusual Conditions We MAINTAIN A COMPLETE STOCK Apco Single Stage" Turbine-Type Pumps. Also available in Two Stage. FOR IMMEDIATE SHIPMENT Packaged Duplex Apco-Matic Condentation Return Unit designed for smaller jobs. LARGER UNITS up to 150 ppm capacity, horizontal and ver tical also available. APCO PUMPS are IDEALLY SUITED to MANY HEATING and AIR CONDI TIONING DUTIES--CAPACITIES UP TO 150 GPM--HEADS TO 600 FT. FEATURES--APCO pumps "are distin (28 ft at sea level) QUIET OPERA guished for their ability to deliver small TION HIGH PRESSURE PER STAGE capacities against high heads; their abil ity td deliver with but slight change in capacity or efficiency against drastic head variations. They possess these ad vanced features -- SIMPLE -- WEARFREE -- COMPACT HIGH EFFI DOUBLE SUCTION DESIGN PRE CISION SHAFTS BALL BEARINGS (support on both sides of impeller) RIGHT OR LEFT HAND OPERATION (Changeable in Field without special CIENCY WILL NOT VAPOR BIND parts) . REPLACEABLE COVER HYDRAULICALLY BALANCED . AC PLATES AVAILABLE IN VARIOUS CESSIBILITY HIGH SUCTION LIFT CORROSION RESISTANT ALLOYS. LOW HEAD ' SMALL CAPACITY--SIDE SUCTION PUMPS MEDIUM ' HEAD At Left TYPE--SAC--Close Coupled, Caps 5 to 85 ppm. Heads to 15 ft. Sizes Available 34', l\i9, S9 At Right TYPE--JMC--Close Coupled Caps, 5 to 150 ppm. Heads to 100 ft. Sizes Available l9, l\i9, lVf, V The' SAC and JMC Close-Coupled Pumps are available in a PACKAGED Arrange ment for IMMEDIATE DELIVERY. APPLICATIONS Well suited as integral part of manufac turer's product such as air conditioning units, cooling towers, evaporator coolers, hot water circulators etc., also for gen eral service. CONSTRUCTION SPECIFICATIONS Made in bronze fitted, all iron or all bronze construction. CASINGS, vertically split--end suction. High grade material as specified. Cas ing wearing ring is standard on Type JMC. MECHANICAL SEAL is standard on all sizes and is located in packing cover-- easily replaceable. IMPELLER is balanced, enclosed type of high grade bronze material. SHAFTS--Stainless steel on Types JMC, SAC and JA. Can be furnished on Type SA at additional cost. MOTOR Built to NEMA specifications and equipped with STAINLESS STEEL shaft. BALL BEARINGS--Permanently sealed against dust and moisture--No lubrica tion required. AURORA CENTRIFUGAL PUMPS are available in many types and sizes-- all noted for their streamline co-ordina tion between impellers and shells. Write for CONDENSED CATALOG "V" 1603 Heating Systems Pomps Buffalo Pumps Division of Buffalo Forge Co. 450 Broadway, Buffalo, N. Y. A complete line of Centrifugal Pumps, Single and Double Suction, Single and Multi stage, for all types of heating and air conditioning installations. Write for Engineer ing Bulletins mentioned below, or consult the Buffalo Engineering Representative in any principal City. DOUBLE SUCTION SINGLE STAGE PUMPS Extensively used for handling chilled water and other air conditioning and clear water applications including air washers, these pumps are available in capacities from 10 to 14,000 U.S. gallons per minute, against heads up to 350 ft. Highly efficient operation is provided by their simply formed water passages and their hydraulically balanced impellers (water enters each side of impeller, with equal pressure and volume). All parts are ample for durability under hard service. Top half of the casing is readily remov able for servicing without disturbing piping. Write for BULLETIN 965-Q. CLOSE-COUPLED SINGLE SUCTION PUMPS These pumps offer the advantages of compactness, high performance and sim ple installation without need for shaft alignment. (A 4 in. pump, delivering 600 gpm at 60-ft head, requires less than 2 cu ft of space). Available in 1 in. to 6 in. discharge sizes. Design permits vertical or horizontal installation, with dis- . charge adjustable to desired angle. These pumps are suited to handling hot water with.low submergence. Write for BULLETIN 975-D. SINGLE SUCTION MULTISTAGE PUMPS Used for boilhr-feed and other clear water service, these heavy-duty pumps are especially suited to delivering at high pressures^mr temperatures. Avail able in two and four stage models for capacities from 20 to 900 gpm at heads up to 1500 ft. Shaft is extra-heavy and oversize bearings support the shaft on each end. Top-half of pump casing is removable for servicing without dis turbing piping. Write for BULLETIN 980-D. AUTOMATIC SUMP PUMPS These are shipped as preassembled units ready to put into the sump pit, wire and start pumping. No priming is necessary, since there is no suction lift. Thrust load is carried. by ball bearings, and the shaft is fully enclosed to prevent fouling with waste or stringy matter from the sump. All parts are readily accessible. Write for BULLETIN 96S-H. Heating Systems Pomps DOMESTIC PUMP & MANUFACTURING CORP. SHIPPENSBURG FINN. SYLVANIA INDUSTRIAL PUMPS COMMERCIAL PUMPS Products: Return Line Vacuum Heating Pumps; Condensate Return Pumps; Vertical, Horizontal and Flange Mounted Centrifugal Circulating Pumps. THREE COMPLETE LINES OF VACUUM HEATING PUMPS Type VLR Single and Duplex Units for Standard and Special capacities up to 20.000 8q ft EDR. Bulletin SUO. Type VLS Single and VLD Duplex for Stand ard and Special capacities from 25,000 to 150.000 sq ft EDR. Bulletin S1S0. Type VCA with individually sized and sep arately controlled jvacuum and conden sate pumps. Air capacities up to 95 cfm at 20 in. Hg and condensate capacities up to 300 gpm at 75 psi. Bulletin S150. Vacuum Pump Type VLRl The heart of all Domestic-Ames Vacuum Pumps is the multi-orifice vac uum producer. Average air evacuating rate is twice its rating, reducing operat ing time and power cost. Removes up to 300 per cent of rated air capacity at start of heating cycle to shorten warm-up period. It is simple, efficient and capable of producing a near perfect vacuum. It will retain its original effectiveness year after year. Vacuum Pump Type VCA4 CONDENSATION AND BOILER FEED PUMPS Single and Duplex Units for systems up to 150,000 sq ft EDR and 60 psi. Each motor of the Type CC Unit is controlled by its own float switch. Bulletin S900. The BOILER FEED type CM Unit provides automatic water make-up to replace water lost from the system and to maintain the most efficient boiler steaming level. Bulletin S200. UNDERGROUND CONDENSATE PUMPS are available for use where re turns are either too low for a standard pump or below floor level. Bulletin SSjjQ All types vacuum-tight accumulators (condensate receivers) available. Condensation Pump Type CCt All Domestic-Ames Vacuum Heating and Condensation Pumps have life-time cast iron receivers with low inlets. Vertical pump mountings put motors above dirt and water and contribute to unit's compact design. Pumps are close coupled for precision alignment and smooth, quiet operation. GENERAL PURPOSE CENTRIFUGAL PUMPS New Domestic "Centriflo" for hot and cold liquids. Quiet, efficient and compact. Head to 200 ft capacities to 400 gpm. Bronze fitted, all iron or bronze. Mechanical seal or packing. Motors 1750 or 3500 rpm, 1 or 3 phase, open, totally closed or explosion proof. Flange mounted, vertical or horizontal close coupled. Bulletin S690 1605 Heating Systems Pumi>s Chicago Pump Company 622 W. Diversey Parkway EAstgate 7-1020 Chicago 14 PRODUCTS--Return Line Vacuum Heating and Boiler Feed Pumps, Condensation, House, Booster, Fire Pumps, Circulating, Brine, Sewage, Bilge, Sludge, Pneu- - matic and Tankless Water Supply Systems and Automatic Alternator for Duplex Sets of Pumps. . . .. Fig. D-9900--Duplex "Condo-Vacs" with Duplex Double Automatic Control "CONDO-VAC" Return Line Vacuum and Boiler Feed Pump for Heating Systems No vacuum on stuffing boxes, ample clearance in rotating member. It costs less to operate a "Condo-Vac." "Condo- ac" reduces corrosion in piping and boiler to minimum--because pump does not take in air from atmosphere and en tirely eliminates all air coming back from system. "Condo-Vac" is quiet, has a low inlet, entirely automatic, fool-proof, easy to maintain. Ask for Bulletin 270. For every heating system get the pump that is specifically designed for the par ticular job. For below floor returns, for low vacuum systems, for small capacity high pressure requirements, for any standard heating system, or any unusual condition, there is a CHICAGO Heating Pump that will do the job better. "SURE-RETURN" CONDENSATION" PUMPS for Low and Medium Pressure, and Sys tems up to 75,000 Sq Ft Radiation "Sure-Return " Condensation Pumps and Receivers are built for systems up- to 75,000 sq ft of direct radiation and for low and medium pressures. Built in either single or duplex units. Duplex units are alternated in their operation by the Automatic Alternator. Complete data in Bulletin 250. Fig. D-SS00 VERTICAL CONDENSATION PUMPS for Low and Medium Pressure for Sys tems from 500 to 100,000 Sq Ft Radiation The vertical condensation pump is designed to receive re turns from lowest radiation. The receiver is placed under ground--an ordinary hole sufficing if necessary--and requires very little floor space. Unit is shipped complete, easy to install, assembled so as to prevent steam leaks. Special bearings will stand up under hot water for several years. A special float mechanism is guaranteed not to leak or stick in stuffing box. Complete data and description in Bulletins 245, 25S and 25S. 1606 Heating Systems Pomps Chicago Pump Company 622 W. Diversey Parkway EAstgate 7-1020 Chicago 14 PRODUCTS--Return Line Vacuum Heating and Boiler Feed Pumps, Condensation, House, Booster, Fire Pumps, Circulating, Brine, Sewage, Bilge, Sludge, Pneu matic and Tankless Water Supply Systems and Automatic Alternator for Duplex Sets of Pumps. TYPE D, DOUBLE SUCTION, HORI ZONTALLY SPLIT CASE PUMP For house pump, fire and booster service. A ruggedly built, heavy duty pump for long trouble-free service. The rotating assembly nqay be inspected without dis connecting the piping. Capacities up to 1900 gpm--heads to 530 ft. Described in Bulletin 101. Type D, Double Suction, Horizontally . Split Coze Pump For circulating service, heating, bilge, or sewage pumping, CHICAGO equipment is among the best available. Each pump is specifically designed to do the particu lar job and do it right. Over 40 years ex perience with pumps for every applica tion is built into every unit. For "worry proof" pumping at all times--specify CHICAGO Industrial Pumps. TYPE C-C, CLOSE COUPLED ' BOOSTER PUMP Designed to handle the toughest pump ing jobs efficiently and in the least pos sible space. May be mounted in any po sition as long as the motor is not lower than the pump. Provided with leak proof mechanical seal. Capacities up to 500 gpm--heads to 215 ft. Described in Bulletin 108. TYPE F-C, PEDESTAL MOUNTED, SIDE SUCTION PUMP Built to the same exacting engineering standards as the Type C-C Pump and with the same capacity and head. The flexible coupling drive permits easy field servicing and the use of customer's choice of motor manufacture. Described in Bulletin 107. Type F-C, Pedestal Mounted, Side Suction Pump Heating Systems Pumi>s The Nash Engineering Company 234 Wilson Road South Norwalk, Conn., U. S. A. Sales and Service Offices in all Principal Cities Heating Systems Pumps The Nash Engineering Company 234 Wilson Road South Norwalk, Conn., U. S. A. Sales and Service Offices in all Principal Cities NASH HOSPITAL PUMPS For vacuum and pressure systems in hospitals to provide vacuum or pressure to operating rooms, laboratories and wards. Nash pumps possess particular charac teristics adapting them to this exacting service. Silent service is assured, because the pumps and equipment are installed in a mechanical equipment room. Automatic con trol assures constant maintenance of the correct vacuum or pressure. No pulsation is present in either vacuum or pressure produced by Nash Pumps. Air delivered by- Nash Compressors is entirely free from dust, heat or oil. Even dust entering the pump inlet is effectively removed. No oil or dust filters are required. No expert attendance is required. Bulletin on request. * RETURN LINE VACUUM HEATING PUMP TYPE CSM The new CSM Heating Pump achieves a high level of performance and efficiency. Complete flexibility is secured in this design, since each pumping element is driven by its own motor, actuated by its own control. This makes possible a wide range of air and wrater capacities that can be selected to meet the exact requirements of each particular job. . These pumps are now available in a full range of air and water capacity combina tions, for operation up to 20 inches Hg vacuum, and for pressures from 10 lbs to 70 lbs. Bulletin on request. CONDENSATION PUMP TYPE CS . Following the advanced design of our CSM Heating Pumps, the CS Condensation Pump has features representing long life, dependable operation and low main tenance and installation cost. .. Pump is single suction centrifugal in bronze fitted construction with renewable bronze sealing rings. Balanced impeller is designed for high efficiency handling hot condensate. Pump and motor form a compact unit. Simple mechanical seal replaces conventional stuffing box, eliminating maintenance. Strainer area nearly three that in previous pumps. Easily removed for cleaning. Inlet connection is only 12, 14 or 15 inches, depending upon size of unit, permitting easy and low' cost installation. Bulletin on request. 1608 RETURN LINE VACUUM HEATING PUMP UNIT TYPE Removes air and condensation from return lines of vacuum heating systems. Separation of liquid and gas is made under vacuum. Independent air and water units, combined in single casing and rotating on single shaft, handle returns with high efficiency. Air unit delivers to atmosphere without back pressure. Water unit delivers directly to boiler. Bronze fitted throughout. No internal wearing parts. No internal lubrication. Supplied direct connected to electric motor, or for belt drive, for continuous operation or with automatic control. Standard capacities up to 40,000 sq ft equivalent direct radiation. Larger units special. Bulletin on request, . 1609 IP Heeding Systems Pomps :e> KRAISSL 297 Williams Ave. Hackensack, N.J. Salpg representatives in principal cities. . Pumps and separators for fuel oil burner and heating service; circulators for water service; filters and strainers for oil, water, liquids, air and steam applications. Glass 50 Light Oil Pumps Direct drive for No. 1 to No. 4 oils in clusive. High suction lift; pressures up to 100 psi. Ask for bulletin A-1SS0. Particularly adapted to dirty oil condi tions where extraneous matter would cause seizure in more closely fitted mech anisms. Capacity 1 to 10 gpm. Class 60 M Pumps provide capacities from 2 to 212 gpm; special bearings available for solvent service. Glass 60 Heavy Oil Pumps Reduction drive for heavy oils including No. 6 and blended No. 5--for direct burner operation or booster pump appli cation. Internal gear type, machined to close tolerances for max. vacuum characteristics. Ball bearing, V-belt reduction drive-connected to pump by loose coupling--eliminate side deflection from pump shaft. Suction and discharge in. to 2 in.; capacities 75 to 2100 gpn; pressures to 100 psi. Write for bulletin . A-119S Class 72 Separators Strainers or filters for both suction and discharge service on every burner instal lation. Single and duplex units for both standard and high pressure service. De sign features ease of cleaning and inter changeability of separator baskets. Available with Underwriters Labels from in. to 4 in.; larger sizes up to 6 in. Ask for bulletin A-14S0 iu & K ,V UL listed single strainers for installation as integral part of pump type burners. Any practical degree of separation; sizes H in. to 4 in. inclusive. Ask for bulletin A-1S14 Glass 34 Water Circulators Enclosed-impeller type centrifugal pump for both vertical and horizontal mount ings--particularly suitable for high head applications. Ball bearing construction, replaceable wear plate, simplified dis mounting and remounting without com plete disassembly. Capacities up to 140 gpm. Ask for bulletin A-1581 1610 Heating Systems Pomps Skidmore Corporation St. Joseph, Michigan Quality Heating Pumps for over a quarter of a century Write for Bulletin No. 19~A on Type UV Pump '' Bulletin No. 21-B on Type CP Pump SKIDMORE TYPE UV PUMP The Skidmore Type UV Condensation Pump, single or duplex unit, is designed for use where returns are too low to permit the operation of horizontal type pumps. Type UV Pump operates very satisfactorily where condensate is to be returned to the boiler or other points, from all types of steam heating systems or process equipment. Type UV Pump consists of vertical pump and motor unit with float and float switch mechanism mounted on cover plate which is bolted to sump type receiver. Capacities 2000 to 40,000 sq ft EDR and discharge pres sures from 10 to 75 lbs. SKIDMORE TYPE CVS PUMP The Skidmore Type CVS Condensate Pump is built for maximum efficiency, requires a minimum of space. Designed in both single and duplex units. Shown , above is the duplex pump with two float 1 switches. This model also furnished with automatic alternator on all sizes. Inte gral pump casing and motor stand of cast iron construction, bolted to top of receiver. Pump bronze fitted throughout, with enclosed centrifugal impeller of spe cial design for hot water. Capacities 500 to 10,000 sq ft EDR, pressures from 10 to 40 lbs. Write for Bulletin No. 14-A on Type HS Pump Bulletin No. 17 on Type TM Pump SKIDMORE TYPE HS PUMP SKIDMORE TYPE TM PUMP The model HS Condensation pump is economically designed to offer maximum efficiency with lower operating cost. The Type HS will operate at high tem perature encountered in condensation pump service. The pump can be dis assembled without disturbing piping connections. Furnished in either single or duplex type. Pump casing is con structed of heavy close grain cast iron, vertically split, bronze fitted throughout. Capacities 1,000 to 65,000 sq ft EDR, pressures 10 to 75 lbs. Type TM pump consists of motor, steel receiver, automatic make-up valve mounted on receiver, water level gage glass mounted on receiver, self-cleaning strainer between pump and receiver, assembled and mounted on steel base. Cast iron base furnished if required. Electric boiler water level controller furnished for mounting on boiler. The Type TM Condensate and makeup water pump is of turbine type designed for boilers up to 250 hp and pressures up to 150 lbs. . Write for Complete Engineering Data Bulletins on Skidmore Condensate and Vacuum Pumps will be sent on request 1611 Heating Systems specialties The V. D. Anderson Company Div. of International Basic Economy Corp., . 1935 West 96th Street, Cleveland, Ohio Quality Steam Specialties Since 1886 Representatives in all principal cities SUPER-SILVERTOP STEAM TRAPS Inverted bucket steam traps of an . improved, thoroughly tested design. For use on steam-using equipment where it is desired to remove condensate and air automatically in order to produce maximum heating efficiency. FEATURES Simplified Piping---Hooks up as an elbow or straight-in-line--only one nipple needed since the U-tube is inside the trap. Saves 3 elbows, 3 nipples and 60 minutes of time, compared to conven tional inverted bucket steam traps. Precision Parts Alignment--The bucket does not swing free. It is controlled in true engineering fashion, guided on a hexagonal tube. This makes a knife- edge contact, eliminating almost all friction! The unusual guide arrangement keeps all parts in proper alignment and prevents the bucket from Tutting the sidewalls of the case. Positive closing of the valve is insured. Self-Cleaning--The reversing of the condensate flow on entering the trap Standard Heat-Kwik produces a scrubbing action. This stirs up any sediment and dirt which is car ried away in the discharging condensate. No Restricting Passages--Even in the smallest sizes there are no narrow cored passages to become clogged with scale. Cannot Alr-Blnd--As the air is auto matically discharged ahead of the condensate in each cycle of operation. Vacuum or Pressure--These traps do not leak steam. No danger of vacuum being destroyed--trap is recommended THREE TYPES OF STEAM TRAPS Standard Inverted Bucket--Use where normal heat-up periods are satisfactory. Thermal Air Eliminator--This trap should always be used where instant heat is necessary. Heat-Kwik Traps--Designed for ex tremely fast air elimination at pressures up to 150 psi. Recommended for all pro duction units such as steam jacketed kettles, autoclaves, dryers, sterilizers, etc. SIZES. LIST PRICES. AND CAPACITIES (Standard Steam Traps) . Size Connections-- (See Note) Max. Ga. Pressure... 110 w only 100 $10.00 118 W or 44' 150 $9.00 119 %' or Hm 200 $10.00 120 Yt* or n* 200 $12.00 121 w or 44' 200 $16.00 122 %' or 1' 250 $25.00 23 ?4# or 1' 250 $32.00 24 VA' 250 $45.00 25 1 Vs* or 2' 250 $70.00 $11.60 with thermal air eliminator $10.60 $11.60 $13.60 t $17.60 $28.20 i $35.20 . $49.80 | $76.40 Differential CAPACITY IN POUNDS OF WATER PER HOUR 1 5 10 20 50 100 125 150 200 250 137 .305 435 300 455 440 161 360 505 700 650 455 500 450 225 510 705 980 900 675 740 580 655 390 970 1190 1650 1400 1200 1310 1000 1100 790 1790 2480 3450 2490 2380 2060 2220 1920 1220 2720 3850 3980 4180 3740 4090 4400 3700 3600 1500 3200 4600 6000 4500 4200 3400 3700 4150 4500 2400 5274 7500 11100 7500 10000 8000 8600 8900 9600 21000 29650 40300 26000 25300 19100 20500 16800 13750 `iuo aizesshown in heavy type are standard and traps will be shipped tapped standard unless other* pedfied Pipe sizes shown in light type furnished at no additional cost but only from Cleveland stock. ' 1fi19. ` The V. D. Anderson Co. Heating Systems Specialties HEAT-KWIK SUPER SILVERTOP TRAPS Size No. Trap 119BL 119BH Size Conn.... 44' 44' Max. Gage... Press........... SO ISO List Price.... $16.00 22.00 DIFF. PRESS. 120BL 120BH 121BL 121BH 122BL 122BH 23BL 23BH w 44' Hw w 1' 1' 1' 1' 50 ISO SO 150 50 150 50 150 18.00 24.00 22.00 28.00 31.00 37.00 38.00 44.00 CAPACITY IN POUNDS OF WATER PER HOUR 1 5 15 8U ldt> 487 1584 1890. 487 880 1136 1584 1890 2108 4SI6O 2731 3109 3143 3447 3484 652 1158 1596 2069 2458 2858 2566 3231 652 1158 1596 2069 2458 2858 2566 3231 3569 3668 4017 3904 1C52 1868 2416 3359 3988 4658 4026 4321 1052 1868 2416 3359 3988 4658 4026 4321 4419 4848 4767 5124 1482 2598 3346 4729 5158 5188 6256 6011 1482 2598 3346 4729 5158 5188 6256 6011 6549 6208 6797 7304 11762 2988 3826 5479 6458 7208 5956 6331 1762 2988 3826 5479 6458 7208 5956 6331 5999 6668 6107 6604 24BL 24BH 1H' 1M' 50 150 54.00 60.00 2662 4588 5900 8379 11058 12308 7656 9331 2662 4588 5900 8379 11058 12308 7656 9331 10849 12468 10707 11504 Capacities based on continuous flow. When ordering be sure to specify mnximum steam pressure. . Anderson Air Release Valves ieoucr- Anderson mr release valves are automatic air vents used for venting air from hot water service and heating systems. Eliminates the annoying venting of air through faucets when water is first turned on. The air release valve consists of an extremely durable valve and seat, a fool-proof lever and ball float which opens or eloses the valve, depending upon the presence of water or air. Write for Bulletin No. 454. Anderson Air Release Valve No 171 Anderson Hi-eF Purifiers are used on steam lines and in boilers to produce clean, dry steam. Type L shown here should always be used ahead of steam engines and turbines to protect this valuable equipment against slugs, line scale, moisture, salts and dirt. Internal type Hi-eF Purifiers should be installed in boilers to assure the delivery of clean, dry steam devoid of carryover, entrain ment and condensate. Also for use in cleaning and drying air and other gases. Write for Bulletin No. 700. Hi-eF Purifiers Anderson Hi-eF Purifier Type L ; Anderson Strainers Anderson Self-Cleaning Strainers remove scale, grit, and sedi- , ment from the line ahead of steam traps, reducing valves, air i tools, pumps, temperature regulators, etc. Stainless steel strainer screens (brass available on 2)4 in. and 3 in.) are stand ard equipment and have an extremely large free area. Standard 3 screen for steam and other gases has iu. openings--for I liquids in. openings. Other sizes of openings furnished when specified, prices on application. Pipe Size........................................... Overall Length................................ Blowdown Connection Pipe Size Shipping Weight (lbs.)................ List Price.......................................... (Stainless Steel Screen) List Price.......................................... (Brass Screen)________________ SPECIFICATIONS AND PRICES w 3W' H' 1 $2.00 w 344' w 1 $2.50 w 34^ w m $2.75 3' ** 244 $3.25 1' 4)6' 3M $4.00 1H' 5W' 1' 5H $5.00 6* V 2W 3' 744' 844' 1O' 1W' 144' aw 1644 2644 40 $7.25 $11.GO $28.00 $36.00 $22.00 $27!00 1613 Heating Systems specialties ARMSTRONG MACHINE WORKS 851 Maple Street, Three Rivers, Mich. Guaranteed: Satisfaction or Your Money Back Traps Available From Local Stocks of 39 Factory Representa tives and 13S Jobbers or Through the Supplier of Your Choice or Direct from the Factory--Representatives Listed in Major Industrial and Classified Phone Directories ARMSTRONG INVERTED BUCKET STEAM TRAPS FOR LOW PRESSURE HEATING--for draining mains, risers, coils, convectors, radiators and unit heaters at pressure differentials from 1 lb up--vacuum, grav ity or closed return systems. For EDR ratings and selection data, ask for Catalog J. FOR UNIT HEATERS. Bulletin No. BS1S gives complete trap selection and instal lation data and lists Btu ratings for all sizes of 30 makes of heaters--free on re quest. . FOR STEAM HEATED EQUIPMENT-- for draining all types of institutional and industrial units including hot water heaters and kitchen, hospital and laundry equipment. Ask for selection data. FEATURES. High Quality Mechanisms in Armstrong traps for low and medium pressures are identical in design, work manship and materials to those used in traps for 900 psig. 900F--see illustration. Open float (inverted bucket) cannot collapse. Nothing to stick, bind or clqg. Only two moving parts, heavily rein forced for wear. Corrosion-resistant materials. Non air-binding. Quick-act ing. High capacity for size. No cooling legs required. Side Inlet Traps Pipe Connections............................. List Price (Regular)....................... List Price (Blast Trap)................. Height................................................... Diameter........................................... Weight................................................... Maximum Pressure, lbs................. 5 10 15 20 Dlete information see 2 30 8 50 70 .100 5125 150 200 250 Bottom Inlet Traps Pipe Connections............... No. 800 94* or 94* $10.00 $12.00 5Ms* 5' 5 lbs. 150 450 560 640 690 500 580 660 640 680 570 __ -- -- Maximum Pressure, lbs.. -- -- -- -- -- -- No. 811 94' or 94* $14.00 $16.00 W 5' 6 lbs. 250 830 950 1060 880 1000 840 950 860 950 810 860 760 No. 211 H* $13.00 $15.00 694' 494* 6 lbs. 250 No. 812 No. 813 No. 814 94* or 94* $23.00 $26.00 8* Ms' w 15 lbs. 250 1600 1900 2100 1800 2050 1900 2200 1800 2000 1500 1600 1300 ' No. 212 941**or $31.00 $34.00 1194* 794* 27 lbs. 250 2900 ..3500 3900 3500 4000 4100 3800 3600 3900 3500 3200 3500 No. 213 1* or 194* $46.00 $49.50 1394' 9* 45 lbs. 250 4800 5800 6500 6000 6800 6300 6000 6200 6700 5700 5300 5700 No. 214 Choice of side inlet or bottom inletbody styles fori owest cost instal ation 7600 9000 10000 8500 6800 9000 9200 10400 10900 9500 9200 7000 No. 215 14500 17300 19200 18500. 18000 18300 20000 18500 17500 19000 No. 216 W or 94* 94' or 94* $21.00 $24.00 8* w 12 lbs. 250 $29.00 $32.00 1094* 694' 21 lbs. 250 1* 1*. 194', 194' $41.00 $55.00 $44.50 $60.00 1294* 14Me* 7W' 894* 35 lbs. 47 lbs. 250 250 194* or 2* $78.00 1i i09fs* 78 lbs. 250 1614 Armstrong Machine Works Heating Systems Specialties OPEN FLOAT AND THERMOSTATIC --for fast heat-up when steam is turned on to pipe coils, small on-and-off unit heaters. When trap is cold, large thermic vent discharges 500 to 1500 cu ft free air/hr. Thermic closes at 210 F and regu lar bucket vent handles normal air load. Specify "blast trap"--see table. No. 800-814 INTEGRAL STRAINER TRAPS. No. 880, 881, 882 and 883 have strainers in trap body, otherwise identical to 800, 811, 812 and 813 listed in table. No. 880 lists at $11.50,881 at $16.00,882 at $25.50, 883 at $34.00. Each costs less to buy and install than standard trap plus separate strainer. Blast Trap No. 880-888 RIGHT ANGLE TRAP NO. 801. Capac ity and price same as No. 800 listed in table. For replacing old radiator traps or 'wherever angle connections are simplest. Integral Strainer No. 801 BOTTOM INLET TRAPS--No. 211 through 214 have same mechanisms and capacities as No. 811 through 814 side inlet traps. No. 215 and 216 are larger. See table. AIR RELIEF TRAPS (ball float) for venting air from high points in hot water systems and similar applications. Stain less steel mechanisms. No. 21 is 6J, in. diameter, lists at $16.00. No. 21-G fits in wall having 2x4 studs, lists at $18.00. Ask for Bulletins B06B and 450. No. 81 Y-TYPE STRAINERS--250 psig semi steel bodies, stainless perforated or wire mesh screens. Blowout-proof stainlessclad asbestos gasket locked in place by bushing. Square bushing threads assure easy removal. List prices: Y in., % in., K m.--$2.75; % in--$3.25; 1 in.--$4.00; iyi in--$5.00; 1Y in.--$6.50; 2 in.-- $10.00. Details in Bulletin 60S. STEAM HUMIDIFIERS for Stores, Offices, Hospitals, Fac tories, Churches, Laboratories, etc. Automatic, closely con trolled humidification is provided by introduction of steam directly into the room. Installation is comparable to that of steam, unit heaters. A room humidistat controls the solenoid steam admission valve and fan. The smallest unit, for up to 40,000 cu ft, lists at $170.00. Large models available for instal lation in central air ducts. Air-operated models available for explosive atmospheres. Capacities range from 31 to 630 Ibs/hr steam. Bulletin No. 500 gives complete information'. 1615 No. 111-186 No. 81 Heating Systems Slean> Barnes cjones iNeenveMno^^ New York Office: 101 Park Avenue 34 Crafts Street tt Newtonyille 60, Mass. Barnes & Jones Vapor and Vacuum Systems of Steam Heating; Modulation Valves; Adjustable-Orifice Radiator Valves; Packless Quick-Opening Radiator Valves; Ther mostatic Radiator Traps; Thermostatic Trap Replacement Units; Condensators (Boiler Return Traps); Float and Thermostatic Traps; Strainers; Gages; Systems of Zone Control for Steam Heating. Complete Catalog on Request Vapor and Vacuum Series K--The Series K Valve is of the modulating type equipped with dial and pointer to indicate whether the valve is open or shut or in an intermediate position. Lever or wheel handle. Series F--The Series F Valve has no dial or pointer and is therefore furnished only with wheel handle or lock shield. Of same quality as Series K, but lower priced. Both Series K and Series F Valves are quick opening, have non-rising stems, renewable disc seats, of packless design. Made angle pattern in 34, 34, 1, and 134 in. sizes; straightway (globe) pat tern in % and 1 in. sizes. For use in vapor or vacuum systems. Type H--The Type H Valve is of the adjustable orifice type so arranged that the dial indicates at all times the size of the radiator for which the valve is adjusted. May be adjusted with steam on the system. Noiseless in operation. Lever or wheel handle, unauthorized tampering virtually impossible. Made for pressure differentials of 1, 2, 3, 4 and 5 pounds, 34 in. valve up to 100 sq ft. 1 in. valve over 100 sq ft. Thermostatic Radiator Traps--The B & J precision made ther mostatic trap contains the unique, patented cage unit which is a complete operating unit in itself. The cage assembly contains the double thermostatic element calibrated in the factory, and locked in correct adjustment with the trap seat, which is also an integral part of the cage unit. Suitable for pressures up to 15 lb 34 to 1 in. Medium and high pressure traps suitable for pres sures between 15 lb and 100 lb can be furbished. Float and Thermostatic Traps--Barnes & Jones F&T traps respond instantly to sudden loads and pass condensate, regard less of temperature, through water sealed float operated valve. Thermostatic element gives rapid, air venting. Made in Low and Medium pressure ratings. All working parts are readily accessible. No special wrenches needed. No disconnecting of pipe lines. 34 to 2 in. Cage Units--Most maintenance engineers believe in a regular check-up of their heating systems. Barnes and Jpnes make this check-up easy by providing a means for testing all steam traps, and for replacing the actuating units of any make trap. The B & J cage unit replaces all working parts. The double diaphragm unit is correctly and permanently adjusted before leaving the factory. Made for all sizes, pressures and makes of vapor and vacuum traps up to 65 lbs. It's a complete one-piece replacement containing thermostatic element, valve piece and seat locked in unalterable adjustment. No field calibration is necessary. Ask for Bulletins C-34 and B-44- PUMPS--CONDENSATE & VACUUM HEATING. Condensate Pumps up to 65.000 sq ft EDR. Vacuum Pumps up to 100.000 sq ft EDR. 10 psi to 150 Psi Dis charge Pressure. Steel or Cast Iron Re ceivers. Single & Duplex Units. 1750 rpm & 3500 rpm Units. Ask for pump catalog. 1616 Heating Systems A. W. CASH COMPANY P. 0. Box 551 Decatur, Illinois Specialties Valves msh STMIDRRD AUTOMATIC PRESSURE, HYDRAULIC, TEMPERATURE, PROCESS AND COMBUSTION CONTROLS The A. W. CASH COMPANY under trade mark CASH STAND ARD manufactures a complete line of automatic valves, regula tors, controllers, governors, hydraulic valves, refrigeration back pressure valves and complete process and combustion control systems. Typical examples. PRESSURE REDUCING AND REGULATING VALVES Streamlined Reducing Valve, Type 1000. Three principles as sure high capacity and close pressure control: streamlined inner valve eliminates turbulence; straight-line flow through valve housing; aspirating effect controls valve opening, amplifies slight pressure changes into large valve operating forces. High and low pressure models in eight sizes, 34 in. to 2 in. x 2)4 in. (expanded outlet if desired). Self Contained Pressure Reducing Valve, Type 1260. For steam, air, oils, water, gases, other fluids. Spherical self-clean ing inner valve rotates freely, seats in different positions at each closure. Built-in strainer protects seat. Screwed ends, in., 34 iu. and 1 in. Single Seat, Diaphragm Type Reducing Valve, Type D. For steam, hot or cold water, air, oils, many chemicals and gases. Free circulation around moving parts assures even expansion and contraction, prevents seizing. A simple, inexpensive valve. Screwed ends, J4 in. to 2 in. PILOT OPERATED VALVE Pilot Operated Pressure Reducing Valve. Type 30-AP. For steam, air, most fluids. Pilot normally operated by independent fluid. Manner of connecting control lines to pilot and installing . reversible inner valve makes it a pressure reducing and regulat ing valve or a relief or back pressure valve; determines whether main valve opens or closes with failure of operating fluid de livered to pilot. Screwed ends, 34 in. to 3 in.; flanged ends, 1 in. to 12 in. AUTOMATIC COMBUSTION CONTROL SYSTEMS Cash Standard Systems are for use on all kinds of boilers (forced or natural draft), stokers and burners, and for coal, powdered coal, gas, oil, other fuels. All elements of efficient combustion controlled automatically; combustion rate regu lated to keep pace with changes in steam demand. Furnace Draft Controller, Type 90. Operates remotely in stalled hydraulic cylinder, normally regulating damper on forced draft jobs; either alone or as part of a system. Extremely sensitive; fully automatic; no packing or gasometer. Air-Flow Controller, Type 95. Works with Type 100 to main tain proper flow of air to combustion chamber with respect to rate of combustion, automatically compensating for variables: fuel bed resistance, fan speed variation, number of boilers or fans in service. Super Sensitive Automatic Controller, Type 100. Double acting, with four-way valves. Operates balanced valves, chro nometer valves, butterfly valves all sizes; controls fans and other motor driven apparatus. For vacuum and pressures to 600 lb gauge. Reduces and regulates pressure, relieves pressure, controls back pressure, maintains constant differential pres sure or liquid level, controls rate of flow. For steam, water, air, salt brine, various gases, chemicals. Six sizes of power cylinder employed in many different models for wide variety of uses. 1617 Heating Systems Specialties Radiation C. A. Dunham Company 400 W. Madison St., Chicago Toronto London HEATING & COOLING EQUIPMENT Radiation Unit Heaters Pumps Specialties Heating Systems Akron, Ohio Albuquerque, N. M. Allentown, Pa. Atlanta, Ga. Baltimore, Md. Birmingham, Ala. Boston, Mass. * Buffalo, N. Y. Champaign, 111. Chicago, III. Cincinnati, Ohio Clabkbbubg, W. Va. Cleveland, Ohio Dallas, Tex. Davenport, Iowa Dayton, Ohio Denver, Colo. * Sales Engineers h All Principal Cities Des Moines, Iowa Detroit, Mich. Duluth, Minn. - El Paso, Tex. Grand Rapids, Mich. Greenville, S. C. Houston, Tex. Huntington, W. Va. Indianapolis, Ind. Jacksonville, Fla. Kansas City, Mo. Knoxville, Tenn. Little Rock, Ark. Long Island City, LoNs.AYn.geles, Calif. Louisville, Ky. Memphis, Tenn. Miami, Fla. Michigan City. Ind! Milwaukee, Wis. Minneapolis, Minn. Missoula, Mont. Nashville, Tenn. Newtown, Conn. Oklahoma City, Okla. Omaha, Nebb. Philadelphia, Pa. Phoenix, Abiz. Pittsburgh, Pa. Portland, Obe. Providence, R. 1. Richmond, Va. Rochester, N. Y. St. Louis, Mo. Salt Lake City, Utah San Antonio, Tex. San Francisco, Calif. Schenectady, N. Y. Seattle, Wash. Spokane, Wash. Syracuse, N. Y. Tampa, Fla. Toledo, Ohio Trenton, N. J. Tulsa, Okla. Washington, D. C. Wichita, Kan. Wilkes Bahbe. Pa. Mexico, D.F., Mex. . CONVECTORS--Attractive, easy-toinstall. Use with hot water or steam. Eight models, capacities with steam 1 lb entering air 65F: 9 to 139 EDR. Dimen sions: 4,6, 8 and 10 in. wide; 18 to 112 in. long; 12 in. window convector, 20, 24, 26, 32, and 38 in. high. Picture window, . extra long, plaster front and institu tional types also' available. BASEBOARD--Snap-on front baseboard for forced hot water, steam or vapor heating. Fits flush with floor. 10 in. high. Shipped in 10-ft lengths for easy, on-the- job cutting. Steel or copper elements shipped in 1- to 6-ft lengths. Semirecessed and flush-back enclosures. 12 in. baseboard also available for commercial applications. FIN-VECTOR--Can be installed at any level above 4 in. from floor. Three style covers: sloping top, flat top, ex panded metal. Adjustable hook-and-link hanger or new ball bearing bracket sup ports elements. One, two, or three tiers high. Two tube sizes, 1)4 and 2 in. steel or copper tube. Self-spacing fins. THERMO VECTOR RADIATION For along-the-wall heating of educa tional, commercial or institutional build ings with steam or hot water. Flush-type model, one, two or three tiers high. Two tube sizes: 1)4 in. and 2 in. Lever-op erated damper. 1618 THERMO VECTOR Radiation C. A. Dunham Company VARI-TEMP Heating~Cdoling Unit Horizontal Unit Heater Vertical Unit Heater Heating Systems HEATING-COOLING UNITS--Forindividual room heating with steam or forced hot water; cooling with chilled water; ventilating; heating and ventilating; or cooling and ventilating. ' Three dif ferent sizes can be floor, wall, ceiling or inverted mounted. Can be recessed or completely concealed. Capacities at 2 lb steam, 60 F ent. air: 21,000 to 84,000 Btu. UNIT HEATERS--Type M, Model H and HM, not shown. Cabinet type. Seven styles, 3' sizes. Blower fans directly mounted on double end shaft motor. Capacities at 2 lb steam, 60 F ent. air: 18.000 to 108,000 Btu. UNIT HEATERS--Type V. Horizontal discharge. 11 sizes, 2 models. Capacities at 2 lb steam, 60 F ent. air: 15,600 to 360.000 Btu per hour. UNIT HEATERS--Type C. .Vertical-dis charge. Four types of diffusers available. Ten sizes, 2 models. Capacities at 2. Jb, steam, 60;F ent. air: 42,000 to 576,000 Btu. UNIT HEATERS--Blower, Type R. New, redesigned line. 5 types of mount ings for floor, wall, ceiling, inverted or platform. Mixing dampers, by-pass dampers, filter sections available. Ca pacities at 2 lb steam, 60 F ent. air: 86.000 to 1,500,000 Btu per hour. VACUUM PUMPS--Pull and maintain, at low amperage, up to 26 in. vacuum without dependence on close clearances. Only ONE principal moving part. Single motor easily handles BOTH air and con densate removal. Low 9)4-in. return line connections. Capacities: 2,500 to 65.000 EDR. Single or duplex units. CONDENSATION PUMPS--Pumps fea ture mechanical seal that eliminates stuffing box worries. Capacities: 2,000 to 50.000 EDR. Single and duplex units. Model Ct Vacuum Pump 1619 Type CH V Condensation Pump C. A. Dunham Co. Heating Systems v3ves*nd RADIATOR TRAPS-For all types of low pressure steam beating systems. Body and cover of cast bronze, disc of Monel metal. Available in 6 patterns. Capacities from 200 to 700 EDR. Types OB and OBS Backed Traps THERMOSTATIC TRAPS-Trap has cast brass body and cover; replaceable stainless steel valve and seat; disc of Monel metal. For 5 to 100 lb working pressures. Capacities from 126 to 4,500 lb of condensate per hour. FLOAT AND THERMOSTATIC TRAPS --Use as drip trap for steam mains, unit heaters, heat exchangers. Float, copper; Boat valve and seat, Monel metal. Up to 15 psi gauge working pressure. Sizes: Hi 1, 1J4, 1H and 2 in. with capacities from 100 to 5,750 lb of condensate per hour. INVERTED BUCKET TRAP--Body and cover of high tensile iron castings. Valve and seat (renewable and inter changeable) are specially hardened, cor rosion-resistant steel. Operating pres sures 20 to 150 lb gauge. Sizes H, H, 1 and 1H in. Capacities from 220 to 5,600 lb of condensate per hour. SPRING PACKED VALVES--For lowpressure systems up to 15 lb. Heavy coil spring keeps packing tight around valve stem. Body and bonnet, cast brass. Sizes: % to 2 in. in 4 body patterns. PACKLESS VALVES--Packless con struction (no packing spring or stuffing box) provides tight permanent seal. Sizes: to in- in 4 body patterns. No. V>0 Radiator Valve No. BOO Radiator Valve HOT WATER VALVES--For hot water heating systems with pressure to 60 lb. Cast brass body. Packing nut, one-piece asbestos ring provides tight stem seal: Sizes: % to 2 in. PACKED STEM VALVES--For lowpressure steam systems and hot water systems up to 60 lb. Cast brass body and bonnet. Sizes: ^ to2in. Electronic Control Pand DUNHAM HEATING SYSTEMS VARI-VAC DIFFERENTIAL VARI-VAC HEATING saves up to 40 per cent on fuel -because VARI-VAC automatically provides the exact amount of heat needed by using a contin uous flow of sub-atmospheric steam at temperatures that vary with the weather. METRO single-riser method of piping, costs less to install and maintain. Provides continuous path for flow of steam from top to bottom of building. Continuous pipe runs down through overlying rooms and is offset into each room into convectors or baseboard radiation. 1620 C. A. Dunham Heating Systems DUNHAM CIRCULATORS Standard and high head capacity models for all water heating or cooling systems. Single spring motor coupling. Special brand name motor with built-in overload protection. Extra-large oil reservoir. Field replaceable seals. FLOW CONTROL VALVES Completely automatic. No adjustment for winter-summer op eration. Easy to clean without breaking pipe- connections or removing valve mechanism. Angle pattern: 1 to 2J4 in. incl. Horizontal pattern: 1 to 3 in. incl. . AIR SEPARATORS _ Automatically remove air from forced hot water heating sys tem. One-piece construction. Positively prevents re-entry of air into system. 30 psi working pressure. Sizes: % to 2} in. incl. FLOW DIVERTOR FITTINGS Assure proper water flow through all radiation. Only one fitting normally needed (on return) for each unit of radiation. Size (thread to thread): 1 in. x 14 in- to 2 in. x 1 in. inch; (sweat to sweat):-K-in. x in. to 1 in. x H in. incl. RELIEF AND REDUCING VALVES Pressure Relief Valves have extra-large diaphragm area, non stick design. Factory set at 30 lb. Pressure Reducing Valves have built-in strainer. Factory set 12 lb. Adjustable. Combina tion Relief and Reducing Valves available. CIRCULATOR VALVES : Extra-large flow area reduces water resistance and circulator load. T-type handle operates in only 54 turn. Straightway and angle patterns; thread or sweat; full range of sizes; 60 psi working pressure. BALANCING ELBOWS AND FITTINGS Extra-large flow area. Unique sloping seat provides V-shaped opening for accurate balancing from full open to any degree of closure. Thread or sweat. Complete line includes vent tees, union elbows, connectors. AUTOMATIC AIR VENTS Expansion Type Vents need no adjustment. Manual venting for rapid air removal when system is first filled. 50 lb. working pressure. Float Type Vent has built-in siphon to prevent water logging. 35 lb. working pressure. VARI-FLOW CONTROLS Fully automatic indoor-outdoor temperature controls for all types of hot water heating systems. No seasonal adjustment needed. Immersion bulb and capillary "wrap-around" types. DISTRIBUTOR HEADS For radiant panel and "spaghetti" type hot water heating. Same lji in. copper head usable for supply or return, both ^ and % in. tube connections. Each length has 14 pairs of con nections. . C. A. Dunham Company manufactures a complete line of quality heating equip ment. For catalogs and literature write: Dept. HVAC-56 C. A. Dunham Company, 400 W. Madison Street, Chicago 6, 111., or see your local Dunham Sales Engineer. 1621 Heating Systems I'SwiSk Hoffman Specialty Mfg. Corp. , General Office and Factory Sales Representatives in Principal Cities Indianapolis, Ind. ENGINEERED VENT VALVES for STEAM and HOT WATER SYSTEMS UNIT HEATER STEAM VENT No. 74 For steam unit heaters with working pressure up to 35 lbs. Vents air at any time with rising, dropping or steady pressure. Effectively eliminates air from the unit heater to keep it "Piping Hot" at all times. Capacity 300 C.I.M. at 1 lb press., and 800 C.I.M. at 10 lbs and over. Max. oper. press: 35 psi. MAIN VENTS FOR WATER SYSTEMS No. 79 Valve tapped at top for 34 waste pipe conn. Gives j continuous venting under all conditions. Size conn: 24 in. male, 34 in. female. Max. oper. press: 75 psi. No. 791 Can be easily taken apart for cleaning. Tapped at ____ No. V, t3o5ppfso.i.r 34 in. drain conn. Size conn: 34 in. Max. oper. press: No 79ani No. 791 CONVECTOR VENTS--Steam No. 1-B Adjustable port. Non-vacuum. Size conn: 34 in. Max. oper. press: 10 psi. . No. 71-A Single port, non-vacuum. Size conn: 34 in. Max. oper. press: 15 psi. No. 71-B Single port, non-vacuum. Size conn: 34 in. Max. oper. press: 15 psi. No. 71-C Single port, non-vacuum. Size conn: 94 in. male, 34 in. female. Max. oper. press: 15 psi. No. 41 & 43 No. 41 single port, non-vacuum. Size conn: 34 in. Max. oper. press: 10 psi. No. 43 same as No. 41 except size conn: 34 in. __ No. 45 Single port, non-vacuum. Size conn: 94 in. male, 34 in. female. Max. oper. press: 10 psi. No. 71-A, B and C MAIN VENTS^-Steam No. 4 Small non-vacuum steam mains. Size conn: 94 in. male, 34 in. female. Max. oper. press: 25 psi. No. 4-A For one-pipe or two-pipe non-vacuum systems. Size conn: 34 in. male, 34 in. female. Max. oper. press: 10 psi. No. 16-A Small one-pipe vacuum systems. Non-adjustable port. Size conn: 94 in. male, 34 in. female. Max. oper. press: 10 psi. No. 75 Medium size non-vacuum systems. Single port. Float. Size conn: 34 in. male, 34 in. female. Max. oper. press: 10 psi. No. 75-A Similar to No. 75 except for larger systems. Size conn: 94 in. male, 34 in. female. Max. oper. press: 10 psi. No. 76 For one-pipe medium size vacuum systems. Single No. 75, 75A port. Size conn: 34 in. male, 34 in. female. Max. oper. press: 10 psi. No. 76-A Similar to No. 76, except larger venting capacity. Size conn: 34 in. male, 34 in. female. Max. oper. press: 10 psi. RADIATOR VENTS No. 1-A Adjustable vent ports, non-vacuum. Size conn: 34 in. Max. oper. press: 10 psi. ; No. 2-A Adjustable port vacuum valve. Size conn: 34 in Max. oper. press: 10 psi. No. 70-A Single port, non-vacuum. Meets Federal spec W W--V-151 for Type 1 valves. Size conn: 34 in. Max. oper. No. 1A, 8A press: 15 psi. No. 1000 Large single port, non-vacuum. Size conn: 34 in. Max. oper. press: 10 psi. No. 40 Single port, non-vacuum. Size conn: 34 in. Max. oper. press: 10 psi. No. 500 Vents all systems automatically. Size conn: 34 in. Max. water press: 50 lbs Max. steam press: 15 psi. 1622 Hoffman Specialty Mfg. Corp. tieatmg Systems % gSTTM L^1_HE'DIUM AND SIGH PRESSURE THERMOSTATIC TRAPS Low Pressure Thermostatic Trap Medium Pressure %Traps 5 15-- --25. 50 8 100 . 125 v*r 225 325 180 225 350 500 235 300 450 625 400 490 650 850 8H 8H 9H 9H X' 25 50 100 235 400 550 300 490 650 450 650 875 625 850 1125 F & T TRAPS, DIRT STRAINERS AND SUPPLY VALVES 125 590 720 950 1250 p <fe T Trap Dirt-Strainer Supply Valte 50 Series Float and Therm. Traps are available in pressure ranges to 125 lbs. Used for venting and draining risers, steam mains, unit heaters, blast coils, etc. 50 Series Traps are made for easy servicing with all working parts mounted on cover. Remove four bolts to expose all parts. Pipe sizes are from 94 in. to 2 in. cap. from 70 to 12,000 lbs. condensate per hour. Radiator Supply Valves are made in sizes from 34 to 2 in. in Angle, R.H., L.H., and Straightway patterns. Brass bodies, union nut and tailpiece. Nos. 180 and 185 have non-rising handles. Both are packless. No. 186 is especially suited to vacuum systems. \ Hoffman Dirt Strainers are self-cleaning Y type. Brass strainer cylinders and cast iron body. Sizes 34 to 2 in. for 125 lb pressure. Should be used in line ahead of all float and thermostatic traps. Also available with monel metal strainers. CONDENSATION AND VACUUM PUMPS Hoffman pumps are available in varying capacities, a-cand d-c current, single, two, or three phase, and in pressures up to 60 lbs. Vacuum Pumps Single and Duplex Units Capacities from 9,500 to 100,000 sq ft BDR Condensation Pump Single and Duplex Units Capacities from 1,000 to 150,000 sqfiEDR 1623 Hoffman Specialty Mfg. Corp. Heating Systems IwwSs Series 600 HOFFMAN INVERTED BUCKET TRAPS Working Pressures to 250 lbs Simple mechanism assures high operat ing efficiency. Features include-- straight-through pipe connection; simple seat adjustment; all working parts con nected to bonnet and easily removed with it; stainless steel seat and pin. Series 700 HOFFMAN PRESS. REDUCING VALVES Series 700 Max. Press. 200 psi., Low Press. 1 to 25 psi. Series 710 Max. Press. 250 psi.. Low Press, 5 to 80 psi. . Series 715 Max. Press. 250 psi., Low Press. 2V^ to 125 psi. Series720-S &720-W Max. Press. 250 psi., Low Press. 2 to 125 psi. Series 750 Max. Press. 250 psi., Low Press. 2)4 to 25 psi. Choice of types specifically engineered for your needs--continuous service, or, for tight sealing against low pressure side when there is no demand--and with typi cal Hoffman features of design. Series 710 HOFFMAN TEMPERATURE REGULATORS Series 1100--for steam pressure to 150 lb per sq in. Standard temperature range--80 F to 250 F. Other ranges available on special order. Self-motivated. Hydraulically formed bellows of selected material. Rugged construction. For water heaters, convectors, fuel oil preheaters and other similar applications. HOFFMAN "ZONET" ZONE CONTROL \ Series 1200--Zonet systems or packages for Steam and Hot Water consist of heat anticipating Room Thermostat, motor operated Globe Type Valve, Transformer, Fuse Block and fuse, and in the case of steam zoning, a Vacuum Breaker. The motor'operated, two position, single seated, packed globe type Valve (illustrated) is available in sizes from 14 in. to 6 in. Maximum service pressure: steam 100 lbs per sq in., water 150 lbs per sq in. WALL AND BASEBOARD RADIATION Series "S" Series "F" Series "S" Wall Radiation made of 18 gauge steel in 1, 2 and 3 tier heights for either 3)4 in. or 4)4 in. steel or aluminum fin element. Series "F" Wall Radiation made of 20 gauge steel in 1, 2 and 3 tier heights for 3)4 in. or 4)4 in. steel or aluminum fin element. . Series "A" Baseboard. Copper and aluminum heating elements. Furnished in 1 in. nominal size only with 48--2 in. x 4 in. aluminum fins per ft. Series "B" Baseboard. Pre-assembled unit, ready to install. 10 ft lengths only. Can be cut on job to suit. 1624 Hoffman Specialty Mfg. Corp. Heating Systems Steam and Hot Water HOFFMAN "PANELMATIC" HOT WATER SYSTEM CONTROLS Designed for all Types of Radiant Heating The Hoffman method vastly improves the ordinary forced hot water system by the application of Continuous Circulation. This method permits a smoothly modulated regulation of the heat supply. The Control Valve closes and the circulating stream by-passes the boiler as long as the heat requirements are satisfied. When the circulating water begins to lose heat, the Control Valve is slowly opened by the Controller, permitting hot boiler water to enter the system. Thus, the delicate precision of the Hoffman Controller smoothly varies the temperature of the contin uously circulating water so that the heat supply is always equalized with the heat loss and room temperature remains constant throughout all changes in the weather. There is no type of building to which Hoffman Hot Water Controlled Heat cannot be applied. The system permits zoning of apartments, institutions, large residences and factories, thereby assuring a distribution of heat in di rect relation to either personal temperature preference or to the functional activities of the building. Boiler Connections For One or Two Pips Systems HEATING COMFORT IS ACHIEVED BY THESE SIX HOFFMAN SPECIALTIES Circulator Orifice The Panelmatic Controller The brain of the Hoffman system. It automatically maintains a constant com fort condition regardless of the outdoor temperature. Its accurate balancing mechanism electrically opens or closes the Hoffman Hot Water Control Valve as required. Contro..l.l.e.r Outdoor Temperature Anticipating Bulb This Bulb transmits changes in the outdoor temperature to the balancing mechanism of the Panelmatic Controller. A ccurately relays temperHatoutrWe cahtaenrgTeesmopf ethraetusureppBlyulmb ain water to the balanc_ing mechanism of the Hoffman Comfort Controller. A calibrated orifice used to CbairlcaunlcaetinthgePcipirecuOitrsifictherough the boiler and through the Hoffman circulating pipe. Opens only sufficiently to HsuoptpWlyattheer Ccoornrteroctl Vamalvoeunt of water to ma. inta.in the proper water temperature being circulated through the system. Thermometer. Should be installed about 6 in. from submerged Water Temp. Bulb. A centrifugal pump of preHsocfrfimbeadncHapoat cWityataenrdCloirwcuilnatpoor wer consumption. Usually installed in the return main and continuously circulates the water through the sys tem. Can be installed in horizontal or vertical position. 1625 . Heating Systems steam fTTFEPTH ENGINEERING Illinois Engineering Company 20 5 9 SOUTH RACINE AVENUE * CHICAGO 8, ILLINOIS DIVISION OF AMERICAN AIR FILTER COMPANY, INC. STEAM HEATING SYSTEMS CONTROLS STEAM AND POWER SPECIALTIES ILLINOIS HEATING SYSTEMS, with or without control, are offered in five types and cover the complete range of vacuum and vapor heating requirements. ILLINOIS SELECTOTHERM CONTROL SYSTEM--A high vacuum steam heating system with single dial control that provides comfort, economy and convenience. For buildings of any size where boilers are mechanically fired and used for low pressure steam heating only. CONTINUOUS FLOW CONTROL SYS TEMS--Type A--For zoned installa tions or where steam is used for other than heating and domestic hot water service, or where steam is supplied by Central Station Service. Furnished for pneumatic or manual operation. CYCLING FLOW CONTROL SYS TEMS--Type R--For automatic or manual control of steam flow and pres sures in vacuum systems and one-pipe or two-pipe gravity installations. VACUUM SYSTEMS--A two-pipe steam circulating system in which a standard vacuum pump is used. For any type of building, industrial plants, or for groups of buildings heated from a central plant. VAPOR SYSTEMS--A two-pipe system circulating steam at low positive pres sures without pump or mechanical vacuum producer. Recommended for Residence, Small Apartment, and simi lar service. . Float and Thermostatic.Traps Series G For Low Pressure Service Compact, simple, accessible, durable, dirt-proof. Positive valve action. Wire drawing impossible. Low discharge temperatures. Efficient air venting. Trap not damaged by freezing. Recommended Applications For draining Low Pressure Heating Systems, Ventilating Units, Unit Heaters, Pre-Heaters, Re-Heaters, and other Fan System Heat Surface, Process i SPECIALTIES ' Heaters, Hot Water Generators, Drips of Mains and Risers. Series G operating ranges from 25 inches vacuum to 15 lbs pressure. Illinois Radiator Supply Valves Quick Opening, Spring Loaded, Packless. For any two-pipe steam, vapor or vac uum heating system. " Extremely smooth and easy to operate with a cool, break-proof plastic handle for finger tip control. Illinois Thermostatic Trap Series G . For Vacuum and Vapor Heating Sys tems-- For Working Pressures Up to 15 Pounds Positive acting and responsive to the slightest temperature cnanges, it dis charges condensate quickly and freely without loss of live steam. Heating Systems % stesm mu.i.m E N G I NEERING Illinois Engineering Company 2059 SOUTH RACINE AVENUE. .. CHICAGO 8, ILLINOIS . j-.. DIVISION OF AMERICAN AIR FILTER COMPANY, INC. STEAM HEATING SYSTEMS * CONTROLS STEAM AND POWER SPECIALTIES STEAM TRAPS--A special feature is the impact operated valve with snap ac tion. The valve is either open or shut. It cannot remain in an intermediate posi tion. Wire drawing, scoring or cutting of valve and valve seat are positively eliminated. The valve cannot chatter on the seat under any operating condition. Sizes from in. to 2 in. Pressures from 5 psi to 250 psi and heavy duty to 600 psi. ILLINOIS MOTORIZED VALVES (on and off)--Type R5--For automatic con trol of steam temperatures and pressures to prevent overheating and conserve steam. May be operated by any auto matic contact device or by manual switches. ILLINOIS THERMOSTATIC TRAPS FOR HIGH PRESSURES--Series HG-- Maximum working pressure 150 pounds. Used where neat appearance and com pactness are desirable, as for trapping sterilizers or water stills in hospitals; steam jacketed kettles, coffee urns, warming tables and for process work. These traps are also furnished for medium pressures. ILLINOIS CONDENSATION PUMPS-- The complete line includes both hori zontal and vertical, Single and Duplex Units. Illinois Type "ECR" Pump. Capacities, 2,000 to 65,000 sq ft ear. Discharge pressures to 50 psi. Bronze fitted throughout. Dependable mechani cal seal eliminates leakage around shaft. Heavy duty float control with seamless copper float. Float switch ad justable for various levels. No sub-base required. Cast iron receiver. ILLINOIS ASU HEAT EXCHANGERS-- For heating water with steam. Complete range of sizes and capacities. Other Illinois Products Air Vent Traps Boiler Return Traps Strainers Control Valves: Non-Return, Back Pres sure, Stop and Check Exhaust Heads Suction Strainers Separators--Oil and Steam Pressure Regulating Valves 1627 Series 35 Steam Trap Type R Valve Series HO Trap AS U Heat Exchanger Heating Systems * Jas. P. Marsh Corporation Dept. 5, Skokie, Illinois Branches in Principal Cities Marsh products include: Pressure, Vacuum and Compound Gauges; Dial Thermometers; Steam Traps; Vents; Packless Radiator Valves and other heating specialties; Tri-trol Regulators; Electrimatic Refrigeration Water Regulators and Solenoid Valves. Radiator Traps--These highly efficient radiator traps are equipped with a phos phor bronze diaphragm charged with a support. Condensation is discharged through a float-operated valve located at the lowest point inside the trap body. Air vent is located in a by-pass in the cap or cover of the trap. Air passes through a passageway and out through the trap outlet. Construction permits removal of mechanism without disturbing the piping. Thermostatic Diaphragm Radiator Trap volatile fluid making them equally effi cient for use on pressures below atmos pheric up to IS lbs pressure. Also other traps available up to 125 lbs pressure. Packless Radiator Valves--The metalto-metal seal of Marsh Radiator valves makes them truly packless. They contain no packing of any kind to wear, crack and deteriorate. Proved by many years of service. Easy to operate. Close on less than one turn. Individually tested. Adaptable for hot water as well as steam heating systems. Float and Thermostatic Trap Marsh Inverted Bucket Traps are ideal for all types of hospital and kitchen equipment or similar service where a Jas. P. Marsh Corporation Heating SystemssjgWes Marsh Pressure Gauges--The Marsh standard, low pressure gauge will con tribute to the economy and improve the operation of any type of steam boiler. It is finely built throughout and is available with the Marsh "Recali brator'' for quickly and easily resetting the hand to zero when the gauge is knocked out of adjustment. - Marsh Electrimatic Refrigeration Valves --The Marsh Electrimatic line of re frigeration valves includes condenser water regulators for ammonia, Freon or methyl chloride service; temperature actuated valves, packless solenoid valves, and other related products. Marsh Gauges include vacuum and com pound types in a wide range of designs covering all services and pressures. Over 90 years of gauge manufacturing has reached its highest achievement in the Marsh "Mastergauge" for use where high pressures and temperatures are present and where maximum stamina and accuracy are essential. Marsh Dial Thermometers--The same basic refinements found in Marsh Gauges are found in Marsh Dial Thermometers. Bourdon tube types are available in self- The Electrimatic Type HT Temperature Actuated Regulating Valve is illus trated. It is used to control the flow of hot water or low pressure steam in heat ing or other industrial processes. The valve opens with rise in temperature and closes with fall in temperature. Main application is in heating, but may also be used as a by-pass control in cooling and process service. Regulator is quick opening and tight closing on either high or low pressures. Five standard tempera ture ranges cover most conditions. Car tridge construction of working parts eliminates need for removal of valve from line for cleaning or servicing. Marsh Electrimatic Solenoid Valves are made in both direct-acting and pilotoperated types in iKc, M in. and K in. or Packless Radiator Valve Marsh Float and Thermostatic Traps-- One of the many types of Marsh Heavy Duty Float and Thermostatic Traps is illustrated. These traps are designed for removal of air and condensate from steam mains, branches, or risers, unit heaters, steam coils, etc. The size and weight of the trap permits installation in the piping without any other neans of Inverted Bucket Trap considerable volume of condensate is handled. Traps are self-venting and have large water capacity thus assuring un usually high efficiency in removing con densate, air and gases. 1628 contained and distant reading instru ments, vapor-tension or gas filled. All ranges up to 400 F are covered. "Recali brator" is standard in all bourdon tube types. Ask for catalog information. ifice sizes respectively. They are of pack less, tight seating construction with impregnated coils to withstand frost and moisture. 1629 Heating Systems Kt Maid-O'-Mist, Inc. 3217 No. Pulaski Road . Chicago 41, 111. Manufacturers of Heating and Air Conditioning Specialties ? , Products: Automatic air valves for hot water heating and cooling systems; automatic " humidifiers for steam or hot water; automatic humidifiers for warm air furnaces; steam boiler water line controls; water line float control valves; liquid gas and air strainers. AUTO-VENT Air Eliminators . Maid-O'-Mist Auto-Vents permit auto matic venting of the air which causes = circulation trouble in heating and cool-/ ing systems. More and more, contractors who value satisfied customers are in stalling these trouble stoppers. No. 7 Auto-Vent. For mains, pipe lines, unit heaters, chillers, convectors, coils, etc. Designed for vertical mounting only. Size 4% in. x 2 yt in. with in. I.P. __ female connection. Made of brass and !fo 7 Auto-Vent eclu'PPeiI w'*'h a self-closing, float oper ated valve. All working parts, including Venting trapped mains and circulating lines valve and copper float, mounted on a removable bonnet for quick servicing or re placement. Valve is equipped with a Monel metal spring and a Neoprene valve seat' which is unaffected by high temperatures, oil, anti freeze, etc. For pressure not ex ceeding 75 lbs. . No. 77 Auto-Vent. Identical to No. 7 Auto-Vent, except for an additional J4 in-> I P. side opening to permit its use on overhead pipe lines, coils, etc., where head room is factor. Ideally suited for Diesel engine and cooling manifold use, where vibration demands secure mounting. No air chamber required. Auxiliary Equipment: No. 7X--bonnet assembly for No. 7 and 77; No. 777--self- closing valve core; No. 7A--connector for safe waste. No. t7 Auto-Vent For Horizontal Mounting Only-with in. I.P. female side connection --Size S in. x in. No. 27 and 37 Auto-Vents No. 37 Auto-Vent For Horizontal Mounting Only with H *. l-Pvertical male bottom connection--Size 3 in. x in. . For convectors and free standing radiation. Construction and internal working parts are same as in No. 7 Auto-Vent. Made of non-ferrous metals and designed for pres sure not over 50 lbs. No air chamber required. Auxiliary Equipment: No. 27X--bon net assembly for Nos. 27 and 37; No. 7A--connector for safe waste. No. 666 valve core. Write for price sheet and descriptive literature. 1630 Maid-O'-Mist, Inc. Heating Systems Hwtias and - Chilled Water Cooling No. 67 Auto-Vent JVo,S7 Auto-Vent For convectors and baseboard radiators. Designed for vertical mounting only. Size in. x in. with a I.P. male connection. Designed for limited space, small, self-closing, float operated valve may be installed in trouble spots pre viously neglected or improperly vented. Valve is equipped with a Monel metal spring and Neoprene valve seat, which is unaffected by high temperature, oil, etc. No air chamber required. For pressures up to 30 lbs. Where a Safe Waste is needed, specify No. 7A connec tor fitting. Pot venting convector radiators No 72 Auto-Vent For convectors, baseboard and free standing radiation. Designed for both vertical and horizontal mounting. Size Wi in. x in. with % in. I.P. male con nection. No. 72 Auto-Vent is a fast vent ing self flushing valve of the expansion type. All expansion and contraction of the single, non-porous, composition disk is confined to four port vents. Internal siphon tube prevents water logging when installed in either vertical or horizontal position. Immediate drainage means fast disk drying, quick venting cycle which is continuous and no air chamber is needed. for convector raiiatore No. 7* A Manual venting features plus tight shut off are all controlled by valve cap adjust ment. Valve cap is tamper-proof and can be removed and replaced without damage or special tools for cleaning or flushing, if needed. For baseboard radiation No. 14, No. 15 and No. 16 Balancing Valve Adapter Units for Hot Water Heating and Cooling Systems Maid-O'-Mist Valve Adapter Units make any copper, bronze, or cast brass or iron tee a balancing valve. These units, quickly soldered or sweat fitted into cop- rro.nlt JVo. l<o Pe.r> bras,s*, and . bronze te,es. or, th,read,ed NIoi.ni.seuasntibtfroaersHteeins .toand No. 14 for copper and bronze 'J1'0 aasI iron tees, regulate hot water completeanglebalancing tecs. Nominal pipe eires flow through radiators, convectors, base- calces. fa-.W ., Kin., tin. board panels, radiant coils, return mains, nS{ln"tine"/woT' and branches. Can be inserted in side outlet or run of tee of same pipe-size to complete either a straightway or angle balancing valve. Full, free flow of water through the tee is possible. Since there is no inside reduction of pipe diameter, there is no water restriction except for the balancing required. This permits the use of ad ditional balancing in a heating or cooling system without preliminary planning. Pre cision made of non-ferrous metals. Simple balancing requires only a screw driver. 1631 Maid-O'-Mist, Inc. Heating Systems Hot Water Heating and Chilled Water Cooling CONVECTOR HUMIDIFIER Maid-O'-Mist Convector Humidifier has no flat bottom to block the flow of warm air. Their individual % in. copper water troughs are spaced 1 in. apart to allow un restricted air flow between the evapo rator pads. Maid-O'-Mist Convector Humidifiers are designed for use with radiators and cabinet convectors in hot water heating systems and for all types of warm air furnaces. 8 Trough Convector Humidifier, also available in 1 and i trough sizes NO. 50 SERIES FLOAT CONTROL VALVES The No. 50 Series Float Control Valves are precision designed to fill requirements for humidifying units, pan fillers, air conditioning equipment, evaporative coolers, air washers and other applications where dependable water level control is essential in limited space to meet various operating conditions. (No. 51 float control valve) (No. 68 float control valve) *No. 51 Float Control Valve. Only 5% in. long overall, including copper float which is 2% in. diameter by 1>4 in-deep. Valve body is made of hex-brass rod with removable, raised, hard nylon valve seat. Valve stem is brass with an incased heat and oil resistant, special Neoprene washer. Valve seat is protected with a 100 mesh Monel Metal screen. Valve body is fitted with two in. I.P. locknuts for horizontal mounting securely in %6 in. hole--or valve may be screwed directly into tapped opening. Supply is equipped with union coupling for J4 in. O.D. copper tubing. Working pressures up to 85 lbs, with capacity of gal per minute at 50 lbs pressure. *No. 52 High Duty Float Control Valve. Same general construction as No. 51 but de signed for use where a larger volume of water is required. Capacity 1 gal per minute at 50 lbs pressure, with working pressures to 125 lbs. Overall length 8 in. with over sized float l]4 in. diameter by 4% in. long. *No. 53 High Duty Float Control Valve. Same general construction as No. 52 except valve is vertically mounted with special bracket as integral part for mounting on reservoir or pan, well above water line. Only ()!, in. long. Non-back-siphoning when installed according to instructions. *No. 59 Float Control Valve. Same general construction as No. 51 valye, except valve is vertically mounted with special bracket as integral part for mounting on reservoir or pan, well above water line. Non-back-siphoning when installed according to in structions. Only 5 in. long. . *NOTE: Nos. 51, 52, 53 and 59 can be furnished with a % in. I.P. male connection at additional cost, when specified on order. Series 6900--Water Line Float Control Diaphragm Valves. The No.#6900 Series float control valves are heavy duty large capacity water level controls. Rugged, strong and precision made, the cast brass body is fitted with a removable chromium valve seat. Controlled water level is accomplished through the action of the oversized copper float, linkage and special Neoprene diaphragm. Valve can be furnished to discharge water in an upward or downward position as specified. Inlet.and outlet tapping % in. I.P. Capacities from gal to 6 gal per min. The No. 6927 Brass Mount ing Plate (3 in. diameter) with gasket and screws is used where special mounting ot the No. 6900 Series Valves is necessary. Write for prices and descriptive literature. 1632 Heating Systems Hot water Sarcotherm Controls Inc. Empire State Bldg., New York 1, N. Y. Representatives in Principal Cities, Factory at Bethlehem, Pa. Type STA-1 for Hot Water and Radiant Heating Systems Type W for Steam Heating Systems Automatic Control Panel Fully automatic weather modulated control systems for all types of heating, and all necessary accessories. Hot Water and Radiant Heating Sarcotherm provides a carefully engi neered control system for radiant or panel heating which is fully modulating, and allows continuous circulation. The customary lag of conventional room thermostats is eliminated with the comfprt control ''Thermoray" sensitive to both convection and radiation. For forced hot water heating system for garden apartments, housing develop ments, hospitals, and institutional build ings, Sarcotherm provides a completely zoned control system, including auto matic night set-back and automatic morning pick-up. Steam Heating Systems . The Type "W" Sarcostat Control sys tem automatically proportions the amount of heat supplied to the actual need for any given weather condition. The control is fully modulating, and complete program control panels are provided to meet any control cycle re quired. ' Control Panels Adjustments can be made through a manual control panel or through a completely automatic program panel that provides round-the-clock control of heating systems. For special applica tions control panels with indicating gages can be provided. All panels are electrically operated and can be re motely positioned in any desired loca tion. Engineering Service Consulting Engineers and Contractors are invited to consult with our Engineer ing Staff on any proposed control system. There is no obligation. 1633 Heating Systems Sleam Sarco Company, Inc. Empire State Bldg., New York 1, N. Y. Branches In Principal Cities Anuurs Company: Sabcothebm Contbozb, Inc. PRODUCTS in addition to those listed below: ..Room thermostats, lift traps, balancing fittings, dial thermometers, motor valves, cooling controls. Also Sarcotherm weather-compensated control systems for hot water and radiant heating. (See page 1633) SARCO RADIATOR TRAPS Type H for VACUUM, vapor or gravity steam systems: Self adjusting bronze bellows for highest vacuum to 25 psi. Dis charges condensate, air and air-steam mixture. Body and cap of brass. Self-aligning head and removable seat of hard bronze or stainless steel. Angle, straightway, offset, vertical. to 1 in. Radiator Trap. Typo H Cat' N 150' SARCO RADIATOR VALVES Type 40--Packless--for VACUUM and all other steam systems. Valve stem sealed by packless bronze bellows, balanced pres suDreettyapiles.: ABrnagslse boordgylo, breev, ersitbolelfdiisicns., bakelite handle. Avail able with modulating devices. Lever, wheel or extension handles; lockshield tops. Cat. NISO & N22h Type SM--Spring-packless or gland packed for all steam and hot water systems. Angle, globe, offset, H to 2 in. Same details as for above type 40. Cat. NISO & N221. Type SM SARCO N-100 TRAPS STrimapil,atrhienNs-t1y0le0 tTohearbmovoestaStiacrcToraRpadisiastuoirtable for operation at pressures up to 125 psi. Shield protects bronze bellows from condensate thrust, prevents over-expansion if removed while hot. Stainless steel renewable valve head and seat. Angle,. N-ioo Medium straightway and vertical. Sizes % in. to 1 in. Bulletin 190. Pressure Trap . SARCO FLOAT-THERMOSTATIC STEAM TRAPS Discharge condensate at steam temperature, continuously and without shock. Automatically vent air and gases by built-in thermostatic by-pass. Immediately responsive to varying loads and pressures. Sizes % in. to 2> in. for pressures to 200 psi- Catalog No. N-450. Flooi-Tkermostalic Trap SARCO INVERTED BUCKET TRAPS Sarco Camlift valve mechanism provides rapid and free dis charge of the condensate. Special design to prevent prime loss on light loads. Sizes Yi in. to 2 in., for pressures to 900 psi. Catalog N-S60. Z%ip-B 1634 Inverted Bucket Trap Sarco Company, Inc. Heating Systems steam SARCO THERMODYNAMIC STEAM TRAPS These new type traps virtually eliminate maintenance. Stain less steel throughout . . . immune to both internal and external corrosion. Safe in fire-hazard locations. Not affected by cor rosive condensate, superheat, water-hammer. Only moving part is solid stainless steel disc. No valve-closing mechanism to wear or stick. No critical clearances to choke. No gaskets to leak. Same trap for pressures 10-600 psi. Sizes Y in., % in., 1 in. Bulletin No. N-257. SARCO PIPE LINE STRAINERS (Also Scraper Strainers) Furnished in brass, semi-steel or cast steel for all commercial pressures. They are also furnished with hand or motor operated rotary scrapers, which clean the screen without flow interrup tion. Catalogs No. N-1S00 and N-1225. SARCO SELF-CONTAINED TEMPERATURE REGULATORS Sarco Temperature Regulators are simple, self-operated valves --the self-contained units that use the uniform force of liquid expansion. No stuffing boxes to leak, no auxiliary "power" required. All moving parts are inside the regulator. For steam, gas, oil, water or brine for temperatures to 300 F. Bulletin N-600. SARCO WATER BLENDERS AND TEMPERING VALVES For mixing hot and cold water to deliver automatically water at any desired temperatures. Type MB for showers, wash basins, etc. Type DB, a tempering valve for use with sub merged heating coils or tankless heaters. Bulletin N-800. SARCO AIR ELIMINATORS For convector and radiant hot water heating systems. Also for chilled water lines in air conditioning systems. Semi-steel or cast brass body. Copper floats, stainless steel valve parts. % in. and 1 in. Bulletin N-190. OAA.vvyrxn r in ii -xu wnuuuvmw IU1L/Art A complete' line with approved ratings as established by Insti tute of Boiler and Radiator Manufacturers. Guaranteed for 1-year against defects in -materials and workmanship. Heating ele ments guaranteed for maximum working pressures. Bulletins No. N-1650 and No. N-162S: /- ' SARCO CONDENSATE AND VACUUM PUMPS Complete line of condensate and vacuum pumps for all capacity ranges. New Sarco Type S Condensate Pump shown com bines all these advantages and others: 1. Low inlet height--TYi in. above floor; 2. Enclosed bronze impellers with re placeable bronze wearing rings; 3. Quick, easy disassembly for inspection and maintenance, without disturbing any Types Duplex piping; 4. Single unit converted to du- Condensate Pump plex by simply removing a flange and adding a pump and motor assembly with mechanical alternator. Bulletin on request. " 1635 Thermodynamic Trap Type TR-tt. Standard for hot water storage tanks, fan units. flgSn Type 6 Air li^Bl Eliminator International Heating & Air-Conditioning Exposition Permanent Address--480 Lexington Ave., New York 17, N. Y. EXPOSITIONS HELD Philadelphia, 1955; Chicago, 1953; Philadelphia, 1951; Chicago, 1949; New York, 1948; Cleveland, 1947-1940; New York, 1938; Chicago, 1936; New York, 1934; Cleveland, 1932; Philadelphia, 1930. ' FUTURE SCHEDULE No exposition scheduled for 1956. In 1957, the Exposition will return to Chicago at International Amphitheatre, February 25 to March 1. UNDER AUSPICES OF A.S.H.A.E. These Expositions have been and will be held co-incident with the annual meetings of American Society of Heating and Air-Conditioning Engineers, Inc., and under their auspices. Management is by International Exposition Company with permanent headquarters at 480 Lexington Ave., New York 17, N. Y. EXHIBITORS Comprise leading firms in each phase of thq industry; number has varied from 150 to more than 400 exhibitors. EXHIBITS These range from and comprise all the types of, articles discussed or advertised in this copy of The ASHAE Guide. 1. The Combustion Group: Furnaces, burners (coal, oil and gas), grates, stokers, boilers, radiators (vari ous types), refractories and auxiliaries. 2. The Oil Buhner Group: 3. The Hydraulic Group: Water feeders, water heaters, pumps, traps, valves, piping, fittings, expansion joints, pipe hangers, etc. 4. The Steam Heating Group: Vapor heating, steam specialties. 5. The Hot Water Heating Group: 6. The Air Group: Warm Air furnaces and stoves, registers and grilles, cooling towers, air filters, motors,- fans, blowers, conditioning equipment, ventilators (room and indus trial types), unit heaters, etc. 7. The Air Conditioning Group: Equipment which circulates and filters the air, in summer dehumidifies and cools; in winter heats and humidifies, and does all these in proper season for com plete, all yepr-round air conditioning. 8. The Control Group: Instruments of precision for indicating, controlling or recording temperature, pressure, volume, time, flow, draft or any other function to be measured. 9. The Refrigerating Group: Compressors, condensers, cooling appa ratus, contingent apparatus and refrig erants. 10. The Central Heating Group: Apparatus and materials especially de signed or adapted to the uses of central heating and central heating station sup plies. 11. The Insulating Group: Structural insulators (refractory and cellulose materials), asbestos, magnesia clays and combinations thereof, pipe and conduit covering, etc., weather-strip ping, etc. 12. The Miscellaneous Group: Electric Heaters, boiler and pipe repair alloys, liquids and compounds, tools of all kinds, and equipment not specifically included in the above groups, but related thereto. 13. The Machinery Equipment Group. and General 14. Books and Publications. VISITOR ATTENDANCE Attendance is by invitation and regis tration only, thereby presenting a selected audience. Included are con tractors, dealers, jobbers, supply houses, home owners, industrial users, pro fessional and service organizations, public utilities, real estate management concerns, etc. A detailed analysis of registered attendance is available on request. ' Industrial Expositions in America lead the expositions of the world in style, business effectiveness, industrial influence and educational value. This Exposition stands among the leaders m Industrial Expositions in America. It is an educational institution which brings together the research develop ments ana improvements in equipment and materials for use.in heating, venti lating and air conditioning all types of buildings. Heating Systems Steam Specialities Strong, Carlisle & Hammond Company 1392 West 3rd St., Cleveland 13; .Ohio "STRONG" The Complete Steam Specialties Line 1. Standard In-Line Traps (Semi-Steel). Inverted bucket type. Hi-Cap design. Parts on cover for easy removal without breaking pipe connections. All stain less parts. Trap Pipe Size Continu- Capacity Weight List No. (inches) ous at psi lbs/hr "lbs Price 070 a. H 125 490 3*4 $7.00 170 a. H 125 955 7 9.00 271 n. i 125 1230 m 13.50 2. "Y" Type Strainers (Semi-Steel). Features perforated Monel screen and new V-shaped gripping lugs. 250 psi 450 deg steam. 400 psi cold, non-shock. Pipe Size (inches) Weight List lbs Price H, H Vk H 1 }M 2 2H 3 Sizes *4-in., *4-in. fur nished with 60 x 50 mesh Monel cloth screens. Sizes H-in. to 3-in. standard with .027 perforated Monel. 1 2*4 3*4 5*4 8*4 11*4 17 22 32 $1.90 2.25 2.70 3.25 4.10 5.25 7.75 18.00 21.00 3. In-Line Blast Traps (Semi-Steel). Inverted bucket (open-float) and ther mostatic type. Hi-Cap design. Inte gral bi-metal thermal operated vent. For rapid heating on unit heaters, cookers, etc. Anum-Metl seat, stainless bucket and working parts. Trap Pipe Size Continu* Capacity Weight No. (inches) ous at psi Ibs/hr lbs 070-T h. H 170-T H. H 271-T a. i 30 30 30 660 1290 1760 3*4 8 9 List Price $8.50 12.00 17.50 4. Bottom Inlet Traps (Semi-Steel). Rugged, heavy duty inverted bucket type. "Lever-lift" action and dual fulcrum give high discharge capacity, dependable operation on light loads. All stainless working parts. Anum-Metl valve and seat. Lowest maintenance. Pipe Trap Size (in No. ches) 43 44 54 45 IH 46 1H Continuous Capacity at 125 psi--lbs/hr 3,700 7,180 15,000 35,280 Weight List lbs Price 13*4 $22.00 26 31.00 45 48.00 84 80.00 5. F & T Traps (Gray Iron). For rapid air and condensate removal in low pres sure steam systems. Ball-float mecha nism controls condensate flow; expandmg thermal element controls removal of air. Stainless steel valve and seat, copped hided float. For pressures to 15 psi. Trap No. 11-T 12-T 13-T 14-T 15-T Pipe Continuous Size Capacity Weight (inches) at psi lbs/hr lbs *4 15 230 7 1 15 575 7 m 15 1,380 12*4 m 15 2,760 19*4 2 15 5,750 38*4 List Price $17.45 21.40 26.80 55.85 80.65 6. Type O & K Pressure Regulators (Semi-Steel). For steam, air and gas. Direct operated. Rugged construction. Fitted with special laminated, phosphor- bronze diaphragms and stainless valve and seat. Pipe Size No. (inches) Type O Type K (illus trated) *4, *4, Initial pressure to *4 225 psi, 400 F, re duced ranges 0-200. n Initial pressure to 225 psi, 400 F, re H duced ranges from 0 1 to 85 psi. Type K has an inte m gral strainer. Weight last lbs Price 8 $15.00 15 19.00 15 20.00* 18 27.00 40 38.00 40 42.00 7. Type C Pressure Regulators (Semi Steel). For installations requiring ac curate and dependable regulation. Stainless trim, single-seated, pistonoperated, pilot controlled spring-loaded. Pipe Size No. (inches) Weight List lbs Price Type C . *4' From initial pressure 17 $36.00 . *4 to 2(0 psi, 450 F. For 17 39.00 1 reduced pressure from 17 -43.00 1*4 0 to 200 psi 40 46.00 1*4 40 48.50 2 Available in cast steel 48 60.00 2*4 series, 30, 40 or 60 74 79.00 3 flanges; pressure 600 98 65.00 4 psi; temperature 750 150 160.00 deg ' Complete Catalog Available on Request. 1637 fn. ry it E-i' i Heating Systems conStioriSt'Equipment Warren Webster & Company The Vacuum System of Steam Heating: : Since 1888 Main Office and Factory: 1731 Federal St., Camden 5, New Jersey WEBSTER HEATING AND AIR CONDITIONING EQUIPMENT Webster Radiation: : Thermostatic Traps Webster Walvector for Steam and Hot Water Convectors for Steam and Hot Water Tru-Perimeter Webster Baseboard Heating, for Forced Hot Water Webster Unit Heaters for Gas, Steam or Hot Water; Series 45 Unit Heater Controls. Webster Hydro-Heat Hot Water Heating Specialties: Continuous Flow Controls Hydro-Heat Water Accumulators Float-and-Thermostatic Traps Dirt Strainers Double Service Valves Boiler Return Traps and Vent Traps Boiler Protectors Lift Fittings Expansion Joints Vacuum Breakers Hylo Vacuum Controllers Webster Process Steam Traps: Thermostatic Traps Tru-Perimeter Expansion Joints Float-and-Thermostatic Traps Pressure Regulating Valves Pressure Reducing Valves Flow Control Valves Purge Headers Balance Valves Webster Steam Heating Controls: Webster Moderator Systems Main Steam Control Valves Motorized Shut-Off Valves Webster Blendor Controls Metering Orifices Webster Steam Heating Equipment: Radiator Valves Pressure Difference Controllers Time Switches Air Conditioning Webster Heating-Cooling Conditioner Warren Webster Cool Air System WEBSTER TRU-PERIMETER HEATING Webster Tru-Perimeter Heating uses Webster Baseboard, Webster Walvector, or a combination of both, to replace the heat at the perimeter where heat loss occurs. Heating elements.are mounted close to the floor along outside walls, spreading the heat the entire length of the exposed walls. Webster Tru-Perimeter Heating warms the air within a room, warms the floors, and warms the inside surface of outside walls where a normal coolness occurs during the winter months. Gently mov ing warmed air is drawn to floor level and across the floor into the inlet opening of the radiation. Radiant heat rays strike the floor along the full length of the ex posed walls. Floors are warm and com fortable even with slab floor con struction. 1638 Warren Webster & Company Heating Systems Heatmg and Air Conditioning Equipment Watt-to-waU application of Webster Walvector. Webster Walvector Webster Walvector for steam or forced hot water heating is an elongated con vector designed for mounting along the wall, close to the floor line and under windows. For new buildings or modern ization. Combines an attractive steel enclosure, newly styled and improved, and a highly efficient heating element of copper tubing and aluminum fins in 3 in. and 4 in. fin sizes. Custom Webster Walvector employs 3 in. or 4 in. fin size heating elements, single or double row. Front or top outlet enclosures for wall mounting or with integral sill. For details on standard Walvector, send for Bulletin B-1551; for Custom Walvector, get Bulletin B-1558. Cut-away view showing iaign simplicity of Webster Tru-Penmeter Forced Hot Water Baseboard Heating. . Webster Moderator System The new Type IB Electronic Webster Moderator System provides continuous but automatically graduated or throttled steam flow to orificed radiators--without use of mercury. An outdoor thermostat automatically varies the rate of steam delivery to radiators with changes in outdoor temperature. A Variator, manu ally operated, modifies the action of the outdoor thermostat for such require ments as quick heating-up, changes in occupancy. For details, ask for Bulletin B-900-4B. Isometric mew of Tru-Perimeter Forced Hoff Water Webster Baseboard Beating with new Hydro-Heat features, installed in typical modem ranch house. Note simplicity. Kitchen can be heated by Webster Walvector or Webster Convector (not shown). Hydro-Heat Water Accumulator replaces expansion tank, eliminates con tact between air and system water. Webster Baseboard Heating Webster Baseboard Heating is a forced hot water system in which a convector heating element is concealed within a specially built metal baseboard. It is run in a continuous loop around the ex posed walls of the house, with a sepa rate loop for each floor or zone. Heating element is copper tubing with aluminum fins. Send for Bulletin B-1602. Heating Systems vahes. Air The Dole Valve Company Plumbing and Heating Division 1933 CtHTOll AvCIlllC, ChiCAgO 12, 111. Control with WATER MIXERS THE ALL STAR LINE AUTOMATIC REGISTERS Dole 20 Sr. Vent AIR AND VACUUM VALVES ___________j. -y This high-quality hot water air valve is designed to provide. an automatic air eliminator, a manual shutoff and a man ual air vent. A Dole design developed on the hygroscopic principle by The Dole Valve Company. A selector dial permits various settings and provides for faster venting. One of a complete line of Dole Hot Water Air Valves. Dole No. 100 Water Mixer Here is a new water mixing valve utilizing the famous Dole element which gives extra power. It is noncorrosive and trouble-free. The No. 100 is made of a brass forg ing and yet despite its high quality is low in cost, making it a top value. Nonad- justable. 140 deg setting. Designed for installation at the water heater or storage tank. Dole Air Valves , The complete Dole line includes air valves for every type of heating system. Below are six typical valves from the line. DOLE NO-. 1 A VARI-VENT--adjustable valve that provides an infinite number of venting speeds. radiation where faster venting is essen- tial. DOLE NO. 3--designed to assure utmost heating performance on hand-fired steam heating systems. Complete venting is assured at any pressure up to 10 lbs. DOLE NO. 4 QUICK VENT VALVE--for quick venting steam mains and returns DOLE NO. 1 D--a very fast venting, up to 25 lbs pressure. fixed-orifice, nonadj ustable air valve. DOLE 2 B VARI-VENT VACUUM Factory-set to vent two or three times VALVE--for use on hand-fired gravity as fast as regular type air valves. one-pipe steam heating systems. Has the DOLE NO. 1 B VARI-VENT--provides Dole patented bellows that locks air out better control of heat on convector type once it has been expelled. . Dole Water Mixers Dole Water Mixers provide safer tem- , pered domestic hot water on all tankless y} heaters and storage tank installations.p v Available in three sizes: 14. in., Vi in. and ft jl in.; adjustable range--125 to 175 deg F. 1 Dole Automatic Register .. jj Provides individual room temperature jcontrol. Operates thermostatically from room air temperature. Completely selfcontained. Dial permits setting for the heat desired. Made in sizes to fit practi cally any stack-head opening. 1640 Heating Systems vahes The Fairbanks Company 393 Lafayette Street New York 3, N. Y. Boston; Pittsburgh; Binghamton. N. Y.; Rome. Georgia Dependable Service GUARANTEED From This Complete Line Of Bronze And Iron Body Valves Available From Your Local Distributor Fig. U-01 150 lb SWP Fig. U-OtS! its lb SWP Fig. 0405 115 lb SWP OJKi Fig.'070S 1S5 Ib'SWP BRONZE GLOBE AND ANGLE VALVES Pressures--125 through 300 lbs S.W.P. ' Ends--Screwed, Flanged, Solder, Brazed and Hose. Discs--Bronze: Renewable Composition; Nickel Alloy Semi-Plug Disc and Seat; Stainless Steel Semi- and Full Plug Disc and Seat. Needle Valves Radiator Valves LP--Gas and Oxygen Valves BRONZE GATE VALVES Pressures--125 through 300 lbs S.W.P. Ends--Screwed, Flanged, Solder, Brazed and Hose. Stem Action-Rising with Solid or Split Wedges, Non Rising with Solid Wedges. Bonnets--Screwed, Union, Bolted and O. S. & Y. Radiator Valves LP--Gas Valves BRONZE CHECK VALVES Horizontal, Angle and Vertical Types--Swing and Lift Pressures--125 through 300 lbs S.W.P. . Ends--Screwed, Flanged, Solder and Brazed. Discs--Bronze, Renewable Composition, Rubber Faced. LP--Gas Valves IRON BODY GLOBE & ANGLE VALVES Bronze Mounted Pressures--125 through 250 lbs S.W.P. Ends--Screwed and Flanged Discs--Bronze, Renewable Composition, Semi-Plug Disc and Seat Bonnets--O. S. & Y. and Union Automatic Stop and Check Valves Nickel Alloy IRON BODY GATE VALVES Bronze Mounted and All Iron Pressures--125 through 250 lbs S.W.P. Ends--Screwed, Flanged and Hub Stem Action--Rising, Non-Rising and Quick Opening Bonnets--Screwed, U-Bolt, Bolted & O. S. & Y. Underwriters' and AWWA Approved Valves IRON BODY SWING CHECK VALVES Horizontal--Bronze Mounted Pressures--125 through 250 lbs S.W.P. Ends--Screwed, Flanged and Hub Discs--Bronze, Bronze Faced and Rubber or Leather Faced Underwriters' Approved Valves. 1641 Healing Systems Fim?ga"d H B Wammond rass orks HAMMOND, INDIANA Complete line of packed type radiator valves, circulator valves, balancing elbows, convector valves and gate valves for iron pipe and copper tubing, for use In steam, gravity and forced hot water heating systems; including baseboard, convectors, floor, ceiling, and wall radiant panel heating. Circulator valves, balancing elbows, and fittings for forced hot water systems. Service recommendations: These circu lator valves provide a "nearly tight" shut off when closed and full flow when open. A quarter turn of the handle gives a smooth, easy, full opening. Valves can be furnished in any com bination of copper to iron, copper to copper, iron to copper, etc. Construction of balancing elbows same as circulator valves. The external adjustment allows for adjusting and re-adjusting while system is in operation and eliminates necessity of draining. Caps can be furnished to prevent tampering. These valves are engineered and de signed to fit into small enclosures of the concealed or convector type radiators. Tapered ball seat gives positive flow control. A'o chance for rust flakes to collect. Hammond Radiator Valves and Elbows for Steam and Gravity Hot Water Heating No. 101--Steam Corner. Same as No. 100. Specify whether right or left hand wanted. Valve illustrated is left hand. No. 102--Gate Union. For hot water installations and steam or vapor heat ing systems. Especially suitable for use with unit`heaters; ideal for general shut-off valve service at other points throughout heating systems including boilers and hot water heaters. Specify when ordering for hot water system, as such valves are furnished with a small hole drilled through the disc to provide for slow circulation when valve is closed. No. 105--Convector Single Union Gate. Same as No. 102, but single union does not permit removal of radiator while system is in operation. No. 108--Convector Female Union Steam Angle. Same as No. 100, but should only be used for convector radiators equipped with inside leg tappings. The female union eliminates the necessity for exact roughing in measurements to tapping. Variation of the nipple inside leg will allow for adjustment. Shipped with bonnet loose to facilitate installation. No. 300--Union Elbow--For gravity hot water heating installations. No. 101--Double union gate for convec tor radiators only, See Hammond Catalog 1 r complete line of valves. Stocked by all leading wholesalers, also 29 factory wai touse stocks located in 29 cities throughout the United States. 1642 Heating Systems Vawes Jenkins Bros. 100 Park Avenue, New York 17, N. Y. Brjdgepobt, Conn.; Boston, Philamxpbia^Chicago, San Francisco, Atlanta LOOK FOR THE JENKINS DIAMOND : "V ' . &nrt . Leading Supply Houses Everywhere Stock Jenkins Valves JENKINS VALVES for LASTING ECONOMY Corrosion Resistant iron PATTERNS AND PRESSURES FOR ANY SERVICE IN JENKINS COMPLETE LINE Consult Jenkins Catalog for complete details on more than 500 different valves that cover practically all industrial plumbing and heating, and engineering requirements. Below is a brief list. All-Iron Valves,--globe, angle, gate; Angle Valves,--bronze, steel, and iron body with bronze mounting or trimming. Blow-Off or Y Valves,--bronze and iron. Electrically Operated Valves, Gates, Globes, Angles, Fire Line Valves; Floor Stands; Foot Valves for gasoline service. Gate Valves,--bronze, iron, steel; with solid wedge or double disc parallel seats; with removable bonnet and renewable bushing. Globe Valves,--bronze, iron and steel; one piece and union bonnets; renewable and integral seats; rubber composition or metal discs and plugs. Horizontal Check Valves,--bronze, iron and steel; Hose Valves; Indicator Posts; Lock Shield Valves. Needle Valves; Non-Return Valves; Quick-Opening; Self-Closing Valves. Radiator Valves; Rapid Action Valves; Regrinding Valves; bronze and iron body with bronze trimming; renewable plug seats and bevel seats of a special nickel alloy in globe, angle, check and swing check patterns. Stop and Check Valves,--non-return; Swing Check Valves,--bronze, iron and steel. . Stainless Steel Valves,--globe, angle, gate and check. Underwriters' Pattern Valves,--check and gate; Whistle Valves; Waterworks Valves. 1643 Insulation Roof Cooling April Showers Company, Inc. 4126 Eighth Street, N.W. Washington 11, D. C. COO l_ I N <3 (Trade Mark Reg. U. S. Pat. Off.) AUTOMATIC EVAPORATIVE ROOF COOLING Distributers and Dealers la Principal Cities Automatic ROOF COOLING Spray Method The logical FIRST step in any large or medium sized Air Conditioning program Over 19,500,000 Square Feet of Roofs Cooled by APRIL SHOWERS. Excellent results recorded whether in conjunction with a true air conditioning system or alone as an "under-roof" Cooling System. _ (Partial hist of Users) E. I. duPont de " Nemours & Co., Inc. (Stores: 19,549 sq ft Shipping Dept: 43,902 sq ft. Shops: 17,772 sq ft) Martinsville, Virginia. * Calhoun Garment Co., (44,660 sq ft) Calhoun City, Mississippi. * American Viscose Corp., (139,120 sq ft) Marcus Hook, Penna. * Stahl-Urban Company, (64,000 sq ft) Brookhaven, Miss. . * Hamilton Standard, Div. United Air craft (538,500 sq ft) Windsor Locks, Coud.. * Livingston Shirt Corp. (24,544 sq ft) Livingston, Tenn. * Lockport Felt Company, (180,859 sq Consider these important Facts when planning your next Air Conditioning or Cooling installation * Reduces loads of True air conditioning systems as much as 25 percent Lowers temperatures of upper floors 8 deg to 15 deg * Used on all types and shapes of roofs on Industrial, Commercial and Residential buildings * Increases em ployee efficiency * Thermostatically con trolled; no pool, no run off * Installation Is simple, Inexpensive, fool-proof Op eration and maintenance costs are negli gible The APRIL SHOWERS System is fully automatic. The Sun operates it. Re quires very little water and City water, under normal city pressure, is usually adequate. No runoff. Installation and Maintenance Costs are low. Only finest materials are used. Precision workman-' ft) Starkville, Miss. ship. * Write-Right, Mfg. Co., (44,352 sq ft) Chamblee, Ga. And suck others as: Lilly Tulip Co., General Electric Co., Westinghouse Electric Co., Eastman Kodak Co., Bulova Watch Co. and many others. Besides cooling "under-roof" areas, APRIL SHOWERS adds longer life to roofs (preventing the sun from speedily evaporating the protective roof-coating oils), gives added protection in case of fire and acts as a lightning arrestor. In addition, the Federal Government has used millions of square feet of APRIL April Showers is protected by U. S. Pat. SHOWERS installations. Among them is the 500,000 sq ft roof of the U. S. WRITE for complete Information or Naval Ordnance Building in Indi Free Estimates. No obligations. anapolis, Ind. i e. > t * Insulation Muellermist Irrigation Company, Inc. 2612-22 South Ninth Ave., Maywood, Illinois. - FANJET EVAPORATIVE ROOF COOLING SYSTEM Adapted to Practically Any Kind of Roof Surface Tests of a sprayed roof* show that it is more effective in excluding solar heat than a dry roof; more effective than a pool of water one inch deep; and more efficient than a pool six inches deep. For this reason engineers and plant managers are turning more and more to the sprayed roof as a relatively inexpensive means for improving working conditions in the absence of air conditioning, or of sub stantially reducing the load where there is air conditioning. FANJET is a low priced roof cooling system with unusual features. No spray heads are required. By an exclusive proc ess (Patents pending), copper pipe of special size and temper is pierced in such a way as to produce a fan shaped spray of peculiar character in that there are both fine and large drops. The fine drops wet the near areas while the large drops reach the outer areas with intersecting streams. Laterals are placed eighteen feet apart, with the pipe pierced on both sides except around the outside perime ters. The effect is a more evenly wetted surface than is possible by other methods. The sprays are regulated by adjustable automatic controls, so that the quantity of water applied approximately balances evaporation, with little if any waste. To absorb all solar energy on a hot day may call for up to 36 gal of water per 1000 sq ft per hr. This would mean an excessive demand rate on a large roof, so the roof is divided into sections to fit the available water supply, each being wetted in consecutive order. For design purposes allow 200 sq ft to one gallon of water. Evaporation from a properly wetted surface will go on with full effi ciency for five or more minutes during the "off" period. The daily water re quirements would be around 200 gal per 1000 sq ft. Water pressure at roof level should be enough to allow 20 psi at the valve for each section. Full information and estimates on re quest, without obligation. Inquiry from Dealers invited. See ASHVE Transactions , Vol. 46, 1940, Research Paper 1157, p. 231 1645 Insulation CUnodnedrugitroaunndd American Gilsonite Company ' Salt Lake City, Utah An affiliate of Barber Oil Corp. & Standard Oil Co. of California ULATE TRIPLE-ZONE INSULATION Gllsulate is a unique solidified hydro carbon of high resin content which in granular form is poured directly around 7. Requires no mixing or special han dling 8. Can't be punctured, obviating need . to remove rocks from backfill hot underground pipes for insulation and corrosion-protection. - 9. Only normal pipe spacing required; steam and condensate lines can run side by side GENERAL DATA , 1. Low cost per installed linear foot ^ 10. Pipe expands and contracts within V Gilsulate structure 11. Makes repairs to the pipe quick, easy 2. Easy-to-use: pour . . . tamp . . : and economical normal pipe heat does the rest, -"GRADES AND TEMPERATURE 3. Fuses itself in hours into 3 zones of GRANGES ; Ifype A............................... 220F to 300F permanent protection for the pipe ; .Type B............................... 300F to 385F against all commonly-encountered"/ -Type C............................... 385F to 520F buried-line conditions such as acids,' TRENCH SIZE alkalies, roots, water, and corrosion 4 Jn to w in wider than pipe diameteri 4. Tested and proved in actual use in 6 in. minimum backfill over the Gilsulate hundreds of new construction and replacement installations 5. Can be used under all multiple-pipe and cramped space conditions (see bed. EFFICIENCY Heat loss 8-12 per cent of bare pipe Inert to ordinary acids and alkalies found in soil, excellent dielectric illus. below) For further data or information, write: American Gilsonite Co., 134 W. Broadway, 6. Needs no housing or mechanical Salt Lake City 1, Utah, or 1145 E. Jersey sheaths to protect it St:, Elizabeth 4, N. J. 1646 .Insulation Durant Insulated Pipe Company Palo Alto, California Durant International Corporation Williamstown, New Jersey REPRESENTATIVES IN PRINCIPAL CITIES AND CANADA DURANT Pre-Sealed INSULATED PIPE Cutaway shows DURANT construction--Insulation and support sections are ap plied next to pipe--heavy gage galvanized steel casing is slipped over load bearing .and spacer sections leaving a minimum 1 in. space.which is filled with a special high melting point, non-porous asphalt. The result is a solid, compact unit, per manently waterproofed. DURANT INSULATED PIPE is pre-fabricated into complete, insulated and water proofed systems for use in underground or exposed locations. DIP is used for the tcyopnevesyyasntecme so. f steam, hot water, refrigerants and process fluids, and for tracer DIP is fabricated in all standard sizes--Pipe and Insulation supplied as specified-- and is equally adaptable to single or multiple pipe units. SPECIAL FEATURES The DURANT patented insulated anchor eliminates contact between pipe and anchor plate--provides electrical and thermostatic insulation against heat loss and electrolytic action. Assembly and installation of DIP units consists of joining pipe--applying insulation around pipe joint--securing connector to conduit ends--filling 1 in. space between insulation and connector with DIP special asphalt. Units may be assembled before placing in trench as shown here. No slabs, drains or supports are necessary. The DURANT engineering staff and representatives are at yowr service--unite or call for information esti mates, or new Durant catalog No. 85. 1647 Insulation Conduit & Underground E. B. Kaiser Co. SINCE 1890 P. 0. Box 276, 2114 West Lake Avenue, Glenview, Illinois PIPING SYSTEMS REPRESENTATIVES IN PRINCIPAL CITIES resistance to chemical and corrosive OUTER CASING AIR SPACE attack under all subsoil conditions. The inner pipe is concentrically aligned within the casing by heavy sup ports fastened to the inner pipe on 10 ft centers (Fig. 1). This method permits free movement of the inner assembly longitudinally yet controls any tendency for it to deflect or sag during expansion - -and-contraction. Movement is also con trolled by the EBKO anchor, an integral part of the system requiring no costly external reinforcing. Any portion of the inner assembly can EBKO underground or overhead pre fabricated insulated piping systems are designed for efficient and economical distribution of steam, condensate re turn, refrigerants, hot and chilled water in single or multiple units (Fig. 1). Made in standard lengths--18 ft for cast iron casings; 20 ft for steel--with all fittings and accessories to complete the system. The spirally-welded, lock- seam steel casing, ranging from 8 to 14gauge provides substantial support for the inner assembly and resists crushing loads, as does the cast iron; therefore, expensive reinforcements are unneces sary under railways and roadways. These heavy-duty casings may be assembled on the ground and lowered into the trench or hoisted into position overhead, where they can be suspended on 24 ft centers by means of clevis hangers. EBKO casings are designed for 150 psi operating pressures. These casings are protected from weather by an anti corrosive paint. The anti-corrosive compound used on the underground systems has also proved its effective be removed after installation without major disturbance to the system. This design permits the rotation of the inner assembly, eliminating many position welds. Another important feature is the continuous, uniform, annular air space throughout the system, designed to afford maximum insulating efficiency. The insulation retains its normal effi ciency and form even after being thor oughly saturated and then dried. This process may be accomplished after the system is installed. The sectional fittings permit accurate casing alignment and allow visual inspection of all inner pipe joints during tests. Standard devices for expansion relief are adaptable to an EBKO system. The steel-loop type is prefabricated and tested at the EBKO plant and permits ample unrestricted expansion without crushing the insula tion. Installation costs are reduced con siderably by the relatively low cost of field erection, which can be mainly per formed at ground level. All EBKO systems are completely guaranteed. 1648 Insulation Conduit & Underground E. B. Kaiser Co. SINCE 1890 P. O. Box 276, 2114 West Lake Avenue, Glenview, Illinois representatives m principal cities BAIUWP MKK CARS A, D, EBKO outside and inside viscous liq uid systems (Fir. S) AO EBKO Piping Systems for handling vis cous materials merit close investigation by those faced with this problem. Here is the system (Fig. 2-3) that handles any degree of vicidity requiring either high or low temperatures to liquefy. EBKO provides a continuous Heating or Cooling chamber--through valves, fittings, expansion devices, and level controls. Constant. temperatures are maintained thermostatically. The initial investment is rapidly re covered through increased productive capacities. Many industries have found EBKO indispensable to their operations because of EBKO's high efficiencies and low maintenance costs. It is used to convey everything from petroleum by products to process foods--from chem- PUMP HOUSC flt0 STORAGE TANKS rhr^ir+r ESK0 TASK HEATER r9-^ BOILER HOUSE MANUFACTURING HOUSE EBKO heavy oil system (Fiy. S) icals to paints and varnishes--waxes-- fats. Anything that liquefies under temperature is conveniently and eco nomically moved in an EBKO Piping System. EBKO systems can be used over any distance, anywhere--indoors, outdoors--underground, overhead--they can be totally submerged without peril to their efficiency or long life. All EBKO systems are guaranteed. EBKO Heat Exchangers with the counter-flow feature are designed for high efficiencies.-They-are-designed for' various liquids and gases, pressure and capacities. All EBKO Heat Exchangers are in accordance with ASME codes. Single and Multiple Stack Type Heat Exchangers (Fig. 5) This type of Heat Exchanger assures maximum extraction. Each pass can be provided with rod-outs, eliminating disassembly in the event of stoppage. Combination Tank and Suction Heater (Fig. 4) These horizontal or vertical heaters are designed for large and small storage for Various capacities. They heat the liquid in the tank and pre heat the liquid as it is withdrawn. EBKO also designs in the line type heaters--single and multiple tube, tank storage heaters, pre-heaters, econo mizers, reclaiming heat exchangers, and heat exchangers for continuous blow down. ' gafyeld ftoraqe^eaVV 8ection tanh beaterfor 600,000 1649 Insulation fFfarni'O-Uile, H. W. Porter & Co., Inc. 0- ^ 817-G Frelinghuysen Ave., Newark 5, New Jersey Permanent Protection and REID HAYDEN,1 INC. IPnispuelaLtiinoens.fo r Underground B_altimore, Md. Rich. mond.,.V.a.- Charlotte, N.C,,. Advantages offered by Therm-O-T~il'e Anchors & Guides. Therm-O-Tile Anchors and Guides are available to fit CX--onHdiguhitearree:fficiency PERMANENTLY entirely within the tile enclosure and securely anchored to the concrete base. because insulation and conduit are 2'--aPlowsaiytisveDsReYal.ing throughout. Internal Drainage. The Therm-O-Tile concrete base contains an emergency drainage drainag-e assures dry, efficient insula channel--see photograph--which carries 3--tAtihorac-cnRhnh.eeRddN_ccf_oo-:T_nn--_Hss,tt_1rrA_uu_Fc,tFio_oI_nnDAoAtRfhfVTaaMnItTyi.sScAiosfvtnsrdkoPennifg?tosoerar-tioncthothenadtiunmist aufylraoetminotnearnPtyhEesRouMrcAeN, EthNusTLkYeepdirnyg. STRREnNiwGTjmH AhFIDAV.I.1 fa by Ptto burgh Testing Laboratory. 4--"Spread-Footing" foundation. The Drainage is entireiy internal and amply designed to keep the pipe space always dry. Open to thorough inspection at any "sidewalk" makes installation easier. time at manholes. 5--Surrounded by sealed air. 6--All loads are taken directly by an un 7--yTiheeldicnogrrbeacstes. lop' e is PERMANENT hence no condensation pockets. 8--PERMANENCE assures maximum "Spread-Footing" Base. The foundation base of Therm-O-Tile is a thick concrete slab poured directly in the trench bottom. This positively prevents settling economy. Lowest ultimate cost. THERM-O-TILE PATENTED STEAM CONDUIT SYSTEMS r Therm O-Tile o^ eemblyview with tedional pipe cover ing. For a view with fil ler type finsulation see the^ 18$4 GUIDE. Note the chan nel drain which assures the "permanent protection** men tioned here. Expansion Loops. Expansion Loops may be constructed from over-sized Therm O-Tile designed to allow proper expan sion movement of the piping within the loop. ' IBppp SSH Therm^>-Tile Expansion Loop and sagging. The original surveyor's slope is PERMANENTLY held hence condensate pockets cannot form. When installed over filled or boggy ground PERMANENCY is insured by steel re inforcement or supporting piles. Wide Size Range. Top and base sectionf of the envelope are made in numerous sizes. Result: any desired section if usually made available. For complete data ask for Therm-O-Tile Bulletin. Resonable In First Cost Despite the many excellent features obtained in Therm-O-Tile, it is nevertheless com petitive in total first cost. Engineers -- Contractors -- Manufac turers. Write, phone, or wire the nearest Porter-Hayden office for estimates, re commendations, and complete specifica tions for the conduit and insulation on any underground pipe line project. Insulation UCnodnedrugitroaunndd Ric-wiL Incorporated Prefabricated Insulated Piping Systems UNDERGROUND or OVERHEAD Barberton, Ohio Representatives in Principal Cities Ric-wiL Systems for central beating and process piping are engineered and insulated to specific project requirements for efficient distribution of steam, hot or refrigerated liquids and gases. Hel-Cor Insulated Pipe Units... Single or Multiple Pipes . Prefabricated in 21 ft lengths with any specified combination of pipes and insulation. 16 gage helically-corrugated, hot-dip gal vanized metal housing, protected with asphalt coating. Hel-Cor Uniline--For Oil or Process Liquids Similar to standard units except pipes are nested inside a laminated asbestos insulation liner--insulated from the exte rior but" not from each other. Designed for oil and process liquids. Ric-wiL Cast Iron Insulated Pipe Units Factory prefabricated 18 ft 6 in. lengths. Pipe and insulation housed in heavy-duty cast iron conduit. Insulation any type or thickness to meet job requirements. Hel-Cor Underground Systems Standard 21 ft prefabricated sections for efficient field installation. Single or multiple pipe Hel-Cor Units or Hel-Cor Uniline Insulated Pipe Units can be used underground or overhead. Hel-Cor Overhead Systems Prefabricated 21 ft pipe units for straight runs. Elbows, tees, anchor units and expansion loops finished at factory and delivered to job site with joint materials for simple assembly. Cast Iron Underground Systems For underground insulated piping sys tems where permanency and thoroughly tight joints are required. Prefabricated for easy field assembly, complete with accessories--expansion loops or joints, etc. " For full descriptive literature and technical information on Ric-wiL prod ucts and services, call or write the RicwiL office nearest you, or Ric-wiL In corporated in Barberton, Ohio. 1651 Insulation CUnodnedrugirtoaunndd The Stillwater Clay Products Company Plants . Uhrichsville, Dennison, and Junction City, Ohio Conduit Division Factory Agents in Principal Cities General Offices 3334 Prospect Avenue Cleveland 15, Ohio Stillwater funnel and Round Conduit Systems TUNNEL SYSTEM The most versatile of the Stillwater Conduit Systems. With Tunnel Arch in ten different sizes, and in conjunction with one of the three different sizes of Side Blocks, any combination of service piping can be accommodated. ROUND SYSTEM The Stillwater Conduit System supplied complete with Combination Underdrain and Support Structure. The complete system can be quickly installed without ' a concrete pad. With twelve Round sizes, each with proper size of Underdrain Sup port, the proper design size is available to fit any job. Stillwater Conduit is an engineered, proven system. Its major component is Vitrified Clay--the ageless material Stillwater Conduit Systems will pro tect and accommodate all combinations and conditions of underground piping, "using either filler or sectional insulation. Piping, Insulation, and Conduit are ac cessible for testing and inspection at each step of construction. which has withstood the test of under ground use for centuries. Stillwater Con duit Systems are not affected by ex tremes of temperature or moisture, or the attack of corrosive soils. Vitrified Clay, being dielectric, protects the en closed metal service piping from elec trolytic disintegration. We offer, without obligation, our En gineering Services for your proposed new project or replacement job. Complete warehouse stock assures prompt ship ment of any size order with Stillwater Support Assemblies, Alignment Guides, Anchors and other accessories. Write for the Stillwater Conduit Manual--your guide to the best in Un derground Conduit Installation. STILLWATIE C,,. metal piping Investment. 1652 Insulation Z-Crete Division Zonolite Company 135 S. LaSalle St. Chicago 3, 111. UNDERGROUND PIPE INSULATION Z-CRETE* is a Lightweight Insulating Concrete which is poured directly and monolithically around heated under ground piping. Z-CRETE insulation serves as a mono lithic, jointless insulating filler around pipes. A curing and waterproofing mem brane completes the installation. GENERAL DATA The Z-CRETE system of underground insulation is a field fabrication adaptable to any size, number or arrangement of pipes. Six inches of insulation is ordinarily used on the outside of all pipes. A minimum of four inches is economical spacing be tween piping. Z-CRETE installations have no joints to leak heat or collect water--they are as permanent as the earth itself. Anchors, guides and expansion devices (except loops) are the same as used in any other system. The curing membrane provides external water protection and imparts a tensile strength to the conduit. -- TCRCTf ft - KCMBRANB ;i i tfCRCT* ---SBULRORCOKBT i-i*- BASE Single Pipe Conduit k KOUMHt ,0..o. I fe*m --SUBLPOPOCKRT Ttco Pipe Conduit -'Ycarr* - MtMBIUMt Multiple Pipe Conduit TYPICAL Z-CRETE CONDUITS Commonly used designs of Z-CRETE are shown above. The single pipe and double pipe conduit consist of a structural concrete pad, pre-cast Z-CRETE support blocks on which the pipes rest, a pour of Z-CRETE insulating concrete and a curing and waterproofing membrane. The multiple pipe conduit at the right has a second pre cast support for the upper group of pipes. REINSULATION OF EXISTING CONDUITS The ruinous effect of water on steel pipe and insulation is well known. Z-CRETE insulation restricts moisture, keeps the conduit dry. Inorganic Z-CRETE con crete naturally resists deterioration. Many existing hollow or Box Type Con duits may be reinsulated by pumping them full of Z-CRETE. The mass of water resistant Z-CRETE restricts the movement of moisture, so special drain, age provisions are not ordinarily re quired. Z-CRETE is sold and installed by licensed applicators of Zonolite Com pany under U. S. Patent No. 2355966-- Canadian Patent No. 439356. There is an applicator near you. For further data or information, write Dept. HV-6. * 3^-Crete is a registered trade mark of Zonolite Company. 1653 Insulation Anchors Miracle Adhesives Corporation Devices, Inc. Division Manufacturer of Miracle Surface Anchors 214 East 53 St., New York 22, N. Y. Representatives in all Principal Cities and in Canada Miracle Surface Anchor jnethod cuts costs No wiring--No metal corner beads Ideal for cumbersome installations. . Miracle Surface Anchors consist of per forated metal plates 2 in. x 2 in. or 2% in. x 2% in., to the center of each is welded a nail, bolt, spindle, prong or threaded stud. These Anchors are zinc and dichro mate finish to resist corrosion. (Figs. 2, 3, and 5) bonded to rigid surfaces with Miracle Adhesive which is manufactured in many formulations to meet various job requirements. Fig. 6: Ceiling construction unth Miracle Pronged Anchors. MIRACLE TC CLIPS Miracle TC Clips provide an economical, fast and permanent method of fastening light pneumatic air control lines, tele phone cables, and wiring, etc., without drilling to any masonry or metal surface. Each clip will support 1 lb. For twin lines use Miracle PA-1 Pronged Anchors. For fixing lines to steel work, use Miracle Hanger Supports. Fig. 1: Attaching Corkboard toith Miracle Spindle Anchors to Ducts Fig. t: Miracle Spindle Anchor and Washer Fig. 3: Curved Platefor Convex Surfaces . Miracle Spindle Anchors--When at tached to ducts, walls, ceilings, ship hulls, deck heads, etc., will firmly sup port various types of insulation, such as cork, batt and fiber glass, by impaling the insulation (and wire mesh, if any) on the spindle (Fig. 1). Self clinching wash ers to fit over the spindles are available, (Fig, 2). Spindle Anchors are also made on a curved plate for attaching to convex surfaces (Fig. 3). Miracle Pronged Anchors--For bonding thermal cellular glass and other types of block insulation to ducts, walls and ceil ings. Pronged Anchors are set between rows of block insulation and prongs bent in reverse direction over blocks. For wire mesh with plaster finish, 1 prong of each Anchor is bent over block insulation, the other prong penetrating mesh, then bent over before applying plaster finish (Figs. 4 and 6). Fig. 7: Miracle PA-1 Pronged Anchors. Fig. S: Miracle TC Clips. Fig. 9: Miracle Hanger Supports Designed for supporting smallcables, tubing, air lines, etc. MIRACLE "Z" CLIPS Miracle "Z" Clips consist of 2 in. x 2 in. or 2 in. x 4 in. perforated 20 gauge steel. Provides an effective and economical means of attaching wallboard, insulation board, etc. to walls when an air space is required. The hinged construction take up irregularities in surface to which they are bonded. (Figs. 10, 11 and 12). Fig. 10: Cat No.--Z-St,iin.x9in. Fig. 11: Cat. No.-- Z-Si, S in. x t in. Fig. It: Vertical wall section illus trating Miracle "Z" Clips in position. Adhesives: For Anchor installations use Miracle Anchor Adhesive for tempera tures minus 40F to plus 200F or Mira cle RT 1000 for minus 40F to plus 450F or when asphalt primers or compounds Fig. Wall construction with Miracle Pronged Anchors. Fig. S: Miracle Pronged Anchor. are involved. 1654 Insulation Dnc L O F GLASS FIBERS COMPANY Dept. 81-56,1810 Madison Ave., Toledo 1, Ohio Sales Offices and Distributors in Principal Cities Microlite and Super-Fine are low-density, resilient glass fiber insulating materials, which have high thermal efficiency and sound-absorption characteristics. The high insulating efficiency found in both these materials results from the countless dead air cells formed by millions of fine glass fibers, which effectively reduce heat loss or gain. Application: The light weight, flexibility and resilience of Microlite and SuperFine make them easy to handle in large sections, easy to place properly, and easy to fasten securely by standard methods. Either material can be cut with knife or shears, and can be bent around curved surfaces and easily fitted in irregular areas. In addition, these springy, airy insulating materials are compressed and packaged in convenient rolls which save storage space in factory warehouses and in busy cutting-fabricating rooms. Microlite and Super*Fvne can be fitted quickly around the duct and supporting hangers. Light-gauge wire tits complete thejob. Men Hie to work tpith L-O-F Glass Fibers' insulation because it is so softandflexible --so pleasant to handle. Properties: Composed of minute glass fibers of consistent uniformity, bonded together in blanket form, Microlite and Super-Fine insulating materials resist fire, corrosion, vibration, settling and effects of humidity. Glass fibers are in organic; they provide no sustenance for fungi or bacteria, and no food for ro dents or insects. Inch for inch, Micro lite and Super-Fine are two of the most effective of all insulating materials. Densities: % lb, % lb, 1 lb, 1 lb, and 2 lb per cu ft. Widths: 18,24,36,48 and 72 in. Microliteand L-O-P Super-Fine are efficient thermal and acoustical insulating liningsfor air supply ducts. Linings areeasily applied by fastening the insulaticn to fiat metal sheets with adhesive, and forming the duct in a brake. Coated Microlite or Super-Fine Duct Liner: Either is available for all veloci ties up to the highest normally required. If desired, uncoated liner may be used for velocities under 3000 ft per minute. Noise Reduction Coefficient: J^-in. liner has a noise absorption efficiency of 0.64; 1 in. of 0.80. Type No. 6 mounting used. Thicknesses:)><>,%, 1,1)4>,2,3,4and 5 in. Lengths: Comes in rolls from 50 to 200 ft, depending on density and thickness. Facings: Microlite and Super Fine are available with facings already applied in standard widths of 18 in., 24 in., 36 in. and 48 in. 1 in. flange available on one side or both edges for easier joint seal ing. Types of facings include; Plain Va por Barrier Paper; Reinforced Reflective Vapor Barrier Paper; Aluminum Foil (0.0025 in.,0.001 in.,and 0.0007 in. thick); Vinyl Film (0.004 in. aluminum pig mented); Reinforced Duplex Paper Vapor Barrier. Also available are Vinyl and Neoprene Coatings. 1655 Insulation Boarda The Philip Carey Mfg. Company PRODUCTS Lockland, Cincinnati 15, Ohio District Offices In AU Principal Cities . FIREFOIL BOARD Firefoil Board consists of successive plies of corrugated asbestos paper sheets bonded with a special fire-resistant ad hesive, treated with a chemical and hardened to make it a strong, fire-re sisting and water resisting panel. There are approximately 8 layers of corruga tion per inch of thickness. This results in a sheet having structurally strong, fire and moisture resisting and insulating qualities. MARINE PANEL Marine Panel consists of corrugated as bestos sheets laminated together forming a material similar to Firefoil Board to which, on each surface a ply of 3-6 in. asbestos-cement board is bonded. It therefore has similar characteristics of Firefoil -with the exception that it has added strength and durability resulting from the asbestos-cement facings. Standard sheet size i8 in. x 98 in. Cut sizes, available from the standard size sheets, can be cut of factory to customer's requirements. Standard sheet size 48 in.x$6in. Cut sizes, available from the standard size sheets, can be cut at factory to customer's requirements. - ' Materials are available in thickness of )4 in. to and including 3 in. in )4 in. multiples. The use of Firefoil Board with metal corners produces an insulated and acous tical duct construction. Other uses are for bulkheads in ships, partitions, coil housings, ovens, etc. Firefoil Board can be easily nailed, screwed or bolted into place. It can be cut and installed with ordinary tools. Sheets are self-supporting when installed in metal channels or fastened to struc tural iron with bolts. Firefoil can be used at temperatures up to 950 to 1000 F. The "K" factor at 100 F. mean tem perature is .725. The "U" factor at 100 F. mean tem perature as follows: Materials are available in overall thickness of 34 >n- to and including 3 in. in 34 in. multiples. Marine Panel is recommended for partitions, coil housings, ovens, plenum chambers, interior elevator enclosures, fire resisting chambers, etc. Its asbestos-cement facings give the material a rigid surface and an attractive gray-white appearance. Marine Panel can be sawed and drilled as required in the field. Panels are self supporting when installed in metal chan nels, or sheets can be secured to struc tural iron with bolts. Asbestos-cement or steel battens are used over butt joints, and corner angles of steel or galvanized iron are used at corners. Materials must be drilled prior to nailing or bolting in place. All holes should be slightly over sized. The "U" factors at 100 F. mean .tem perature are: Thickness Thermal transmittance B.T.U./hr/sq ft/F. Thielrncss Thermal transmittance DTP /),,/cn HIV. w....................... W....................... 1*........................... m'....................... m......................... 2".......................... w..................... 3*......................... ....................... 65 .................... 55 .................46 .................... 40 .................34 .......................31 ......................28 ...................... 23 .................. 20 W w I* 1M' \W 2". 2Vf 3'.. .79 .62 .51 .43 .37 .33 .30 .24 .21 Firefoil Board is terior use only and ecommended for ininder dry conditions, Marine Panel is recommended for interior use only and under dry conditions. 1656 * Insulation % pjjeDuct` The Philip Carey Mfg. Company Lockland, Cincinnati 15, Ohio District Offices In AU Principal Cities Cs2 PRODUCTS CAREYCEL FOR AIR DUCTS Uses: A fireproof, low cost, high effi ciency asbestos board foi msulating ducts and all types of air conditioning equipment. Use 1 inch thickness up to . 25 F difference in temperature and 80 per cent relative humidity. Recommen dations for more severe conditions on request. Description: Composed of 12 to 14 laminations of indented (not corrugated) asbestos felt per inch of thickness. Weight: approximately 1)4 lb per board foot. Sheet Size: 36 in. x 36 in., or cut to order. Blocks: 6 in. x 36 in. Thick ness: 34 in. up. CAREY IMPERVO FOR COLD PIPES Uses: A high efficiency insulation for cold or ice water pipes--keeps the water cold and prevents sweating. Double 34 inch thickness recommended for ice water pipes. Description: Laminated insulating felt with waterproof liner and jacket. 36 in. long in 34 in., 34 in., double 34 in. and double 34 in. thick sections, finished with cotton duck jackets and ' bands. . FOR HEATING SYSTEMS Uses: Pipe coverings and blocks for pipes, boilers, ovens and other appara tus where the temperature doesn't exceed 300 F. Use 1 inch thickness for temperatures up to 300 F. Description: Pipe covering sections 36 in. long by 1 in., 1)4 aid 2 in. thick, finished with cotton duct jacket and bands. Blocks: 6 in. x 36 in. Sheets:36 in. x 36 in., or cut to order. Thickness: 34 in. up. CAREY PROTECTO TO PREVENT FREEZING Uses: Designed especially to reduce the danger of freezing of exposed water pipes. Description: Consists of two inner layers of hair felt, a waterproof felt liner and an outer layer of insulatingfelt (wool felt). For severe conditions--exposure down to 0 F--use two-inch thickness. 36 in. long sections with cotton duck jacket and bands. Standard thickness --approximately 1)4 in. Insulation Duct Owens-Coming Fiberglas Corporation General Offices--Toledo 1, Ohio. Pacific Cast DM** ^ B" S*"" aara- A COMPLETE LINE OF INDUSTRIAL INSULATIONS Fiberglas Duct Insulations Fiberglas Duct Insulations come in both rigid and flexible forms in six basic typ All deliver top insulating performance against heat and cold plus the additio advantage of sound control. .. Fiberglas Vapor-Seal Duct Insulation is ideal for use on air conditioning due i warm and humid areas. Built-in vapo barrier of asphalt and kraft paper. u range of thicknesses for speciBc tempera tures. , Fiberglas Flexible Duct Liner is used as a sound absorber and thermal ipsu a- tion inside ducts. Available in two thicknesses with high NRG. Fiberglas Flexible Duct Insulation can be used to provide thermal insulation on exterior of ducts of any shape. Faced Flexible Duct Insulation, with facings of foils, duplex papers and rein forced laminate for vapor barrier 01 appearance purposes. . Fiberglas Coated Duct Insulation is a versatile product used for both inside and outside duct insulation. Fiberglas PF Duct Insulation for cover ing rectangular ducts at minimum cost for efficient performance. Fiberglas* Pipe and Block Insulation , Fiberglas PF (pre-formed) Pipe piping. M standard sizes for both low temperatu a Dual-Temperature Pipe Insulation for use uu d ?; or ^s dual-temperature piping. p TnslIiating Boards for Fiberglas Block Insulation and K small and large heated or cooled equipme - cooled piping, Aerowrap* Pipe Insulation for heated pipi g. ye steam traced lines, valves and ht"ngbot .,,ipes up to 1000F, Blanket-Type Pipe Insulation for hot P v v welded pipe aod jarge pipe sizes Low Pressure Pipe Insulation lor t water and low pres sure steam lines and for cold watef P^^ose insulation for Fiberglas PF Insulation, a general-purpose heated or cooled equipment. ^on^ral-Durpose insulation Fiberglas TW-F Insulating ^ool. general ^ used for high-temperature equipment . g vens and other Metal Mesh Blankets for breechm^ tan^^ ^ high-temperature equipment for temp KayIo Pipe and Block Insulation . of conductivity, or "k," of Kaylo Heat The low cemc . er with ;ts iong iife at temperatures up to I1n2s00uFlamtioank,esto>gUdea, Mj o^hgiggh temper^atur^e infisUueldatioonn.^Av.aibl- able in all calcium silicate by Owens-Illinois Glass Co- ^ffl^*TM**TM* Fib6rglaS Crp- i t'nflc look in the yellow pages for your local Fiberglas DistriFor detailed information on Fiberglas Insulation Fibrgias Corporation, Toledo 1. Ohio. butor-Contractor or write Dept 44, Owens- .r x a ronWRAP are trade-marks of Owens-Coming Fiberglas Oor- FIBERGLAS (Reg. U.S. Pat. Off.) and AEKU * poraUoi. 165g Sonoco Insulation Products Company Construction Products Division s. C. '--------------- _bp, Ontabio Sonqcq de Mexico, Mexico, D.F. ov^uaiklmjcT FIBRE DUCT for slab-floor, warm air perimeter heating systems Made especially for gas and oil fired warm air, slab-floor perimeter heating systems where the duct is to be encased . in dense aggregate concrete. Widely .__ used and approved by engineers, archi tects and contractors. Saves time, labor and money without lowering the quality of construction. Designed to comply with FHA mini mum property requirements. It is light weight and easy to handle. Available in lengths up to 50 ft long which can be sawed to exact lengths on the job. Fits all standard metal elbows, T's, registers, etc. Aluminum foil lined and wrapped with asphalt duplex kraft. Also available is SONOAIRDUCT-XP fibre duct for crawl, basement and attic space, gas or oil fired warm air systems. Lined with aluminum foil and outer wrapped with 16-lb asbestos. Same sizes as regular SONOAIRDUCT. # For warm atr perimeter loop system*. /\ _ For warm atr perimeter radial syelems. pllllllllll fiiiiiiiiiiiil . For warm air perimeter lateral systems. SONOAIRDUCT SIZES AND WEIGHTS Inside Diameter bli2* I?. [4* 5' 1" 8' 10* n* 14' 16' 18* 24' 34' 1659 Wall Approx. Wt. Thickness Per M Feet 0.125' 0.J25' 0.150' 0.150' 0.175' 0.200' 0.200' 0.225' 0.225' 0.225' 0.225' 0.250* 0.300' 0.300' 0.375' 0.375' 0.375' 0.375' 0.375' 0.400* 0.400* 0.400* 0.400* 267 lbs 392 lbs 616 lbs 766 ibs 1,058 lbs 1,399 lbs 1,592 lbs 2,003 Ibs 2,220 lbs 2,438 lbs 2,654 lbs 3,212 lbs 4,660 lbs 5,232 lbs 7,223 lbs 7,931 lbs 8,641 lbs 9,349 lbs 10,058 lbs 11,472 lbs 12,227 lbs 12,982 lbs 14,075 lbs Approx. No. Ft in 40-ft Carload 60,000 ft 39,000 ft 22,400 ft 14,700 ft 10,300 ft 8,000 ft 6,500 ft 5,000 ft 4,400 ft L512 ft. 432 ft 324 ft 288 ft 288 ft Glass Blocks Insulation Skyl ights American 3 Way-Luxfer Prism Co. 431 So. Dearborn St., Chicago 5,11L Over SO years' experience in all types of rooflighting and ventilation AMERICANJ3jWAY TOP-LIGHTS AND TOP-BRITES Bring Free Daylight into Interiors ... the Scientific Way to Transform Daylight into Pleasant, Uniform, Room Light American 3 Way TOP-LIGHTS consist of uniquely designed glass blocks of prism structure which are assembled into special insulated grids to make up standard panel units of various sizes. These panel units are installed on the roof according to carefully developed specifications whereby one end of the panel is oriented northward within a rotation of 30 deg. Daylight is automatically transformed as it passes through the specially de signed glass prisms. The TOP-LIGHT serves as a sort of traffic director for the various types of daylight that fall on it. The extremely bright rays of sunlight are rejected* . . . softer, more comfortable light is given unrestricted passage . . . and all light is diffused and directed downward in a wide flood of comfortable roomlight. The diffusion and rejection eliminates traveling "bright spots" such as may appear under ordinary daylighting mediums when the sun travels from east to west. The hollow semi-vacuum glass blocks substantially reduce solar heat transfer during the hot summer months assuring cooler and more comfortable conditions below than can be expected with ordi naryskylighting methods. The blocks also greatly reduce any tendency for con densation on the room side. The glass blocks are set in aluminum , grids surrounded by an insulation fill properly treated, covered and sealed with Tee-Ess compound for protection and weatherproofing. The factory-as sembled and sealed panel is designed to carry customary roof loads, yet is com paratively light in weight. Cross section of joint between blocks viewed from north-south Cross section of joint between blocks viewed from . east-west Cross section of grid perimeter showing the flashing ends ends MADE IN STANDARD SIZES Whenever possible standard sizes should be ordered because they cost less and can be delivered quicker. Special sizes can be made to order at higher costs up to 22 square feet or up to 6 ft 2 in. in any one direction. Special size orders should specify direction of north and structural members. glass unit size modular unit size approx, weight live load maximum span (aluminum grid) maximum area (prefabricated) minimum slope for drainage 1056'x 12* x 12* 16 lbs per sq ft 40 lbs persq ft 6 ft 22 sq ft \i* per ft On the Job Directions Each TOP-LIGHT has a large label on its upper surface which clearly shows: IT'S THE MODERN TREND to flood (1) direction of north, (2) direction of interiors with the cheerful environment structural members, (3) code number. It of natural, uniform daylight. . . auto also has directions for the general con tractor and step by step instructions for matically controlled by American 3 Way thleb rluououfiungg contractor. TOP-LIGHTS and TOP-BRITES. For areas such as stairwells, corridors, etc., where maximum light transmission is most important, TOP* BRITE glass blocks can be specified instead o! TOP-LIGHT blocks. 1660 Insulation Glass Blocks Owens-Illinois GENERAL OFFICES TOLEDO 1, OHIO GLASS BLOCK AND TOPLITE PANELS TWO (l) PRODUCTS GLASS BLOCK PANELS. Owens-Illinois Glass Block are hollow, hermetically sealed glass units containing a % vacuum. They are laid in mortar to form light-transmitting panels in vertical walls. Owens-Illinois Glass Block pro vide quality-controlled daylighting by glass areas which reduce heat loss, sur face condensation and infiltration in cold weather and heat gain -in warm weather. air and vapor leakage are minimized. Natural ventilation requirements can be met by installing windows in glass block panels. SOLAR HEAT GAIN. Complete instan taneous solar heat gain data for OwensIllinois Glass Block designs for all exposures are given on Pages 305 through 307 of this GUIDE. The O-I design num bers which compare with the ASHAE type numbers are as follows:-- TOPLITE PANELS. Owens-Hlinois Toplite Panels are made of hollow, partially evacuated and hermetically sealed glass units, prefabricated at the factory into panels of insulated aluminum-grid con struction. Used horizontally in roofs, Toplite Panels offer controlled daylight ing with reduced heat loss, surface con densation and solar heat gain. THERMAL INSULATION. The coeffi cients of heat transmission `U' for panels of O-I Glass Block and Toplite are as follows: Size of Block TP (Btu/sq Ft/Hr/F Temp. Difference) 554' Sq 754* Sq 754* Sq with Glass Fiber Insert 1154'Sq 1154* Sq withGlass Fiber Insert Toplite Panels .60 .56 .48 .52 .44 .58 II III IVA V 36/, 316, 330, 331, 370 340 340 with Fiberglas Insert 365 363 A new O-I Block design, No. 80-F, is now available which has a much lower maximum solar heat gain than any of those shown in THE GUIDE. This re duction is due to the fact that this block reflects a high percentage of the solar energy which is incident on the exterior at the time of year when it reaches a maximum. Calculations of the solar heat gain through this block are now avail able. Confirming tests are being run. Solar heat gain through Toplite Panels is much less than that through single glass or plastic skylights, due to the fact that Toplite Panels reflect a high per centage of the solar energy when the sun is at high altitude angles as in the spring and summer months. SURFACE CONDENSATION. Because of the low over-all, air-to-air heat trans fer, the exterior air temperatures which will produce condensation on panels of O-I Glass Block and Toplites are much lower than that for ordinary single glass. This permits higher humidities to be maintained where needed for winter air conditioning for comfort or for industrial processes. INFILTRATION. Panels of glass block which are laid in mortar provide a barrier against infiltration. Dusts, drafts, and DESIGN AND SIZES. Owens-Illinois Glass Block are made in a variety of face designs and in three standard sizes (5% in. sq, 7% in. sq, and 11% in. sq--all three are 3% in. thick). Mortar joints of % in. thickness are recommended. Prefabricated Toplite Panels are avail able in four standard sizes (3 ft x 3 ft, 4 ft x 4 ft, 3 ft x 6 ft and 4 ft x 5 ft--all four are 3% in. thick). Complete tech nical data, description and details will be gladly sent. Write: Kimble Glass Company, subsidiary of Owens-Illinois, Department HV, P. O. Box 1035, Toledo 1, Ohio. 1661 Insulation Glass Blocks PITTSBURGH CORNING CORPORATION Dept. AW6, One Gateway Center, Pittsburgh 22, Pennsylvania THERMAL INSULATION PC Glass Blocks allow economical use of large glass daylighting areas, reduce heat loss in cold weather and heat gain in warm weather because each PC Block contains a sealed-in dead-air space that is an effective retardant to. heat trans fer. See Section C, Table 20, Page 200 of this Guide. SURFACE CONDENSATION Because of their high insulating value, condensation will not start forming on the room side of PC Glass Block panels until outside air has reached a tempera ture much lower than that necessary to produce condensation on single-glazed windows. The accompanying chart shows at what temperatures condensa tion will form. Note that LX, Suntrol and Skytrol blocks--in which a fibrous glass screen creates a double cavity-- provide maximum insulation value. are properly air-conditioned, but does not eliminate the need for adequate ventilation or shading in non-air-con ditioned rooms. PC Suntrol blocks, with green diffusing screen, cut heat gain an additional 25 per cent. For data on solar heat gain through PC Glass Blocks, see Tables 19 through 23 in Chapter 13. Types listed are the following PC patterns : Type I--Argue, Argue Parotid Flutee, Decora, Vue _ Type II--Bristol Type III--Bristol LX Type IVA--Essex Type V--Prism A, Priam B ' PC GLASS BLOCKS AID AIR-CONDITIONING The chief aims of air-conditioning-- temperature control, humidity control and cleansing of air--are aided by the use of PC Glass Blocks. Heat loss is less in winter--heat gain is less in sum mer. Solar heat transmission and radia tion are significantly reduced. Dirt, drafts and moisture cannot filter in, for each panel is a tightly sealed unit. PATTERNS SIZES INSTALLATION Outdoor temperature required to produce condensation on the room side surface of PC Glass Block panels. SOLAR HEAT GAIN . The use of glass blocks for light-trans mitting areas results in a marked reduc tion in solar heat gain as compared with ordinary windows. This factor is of considerable advantage in buildings that PC Glass Blocks are made in three ses:6in.,8 in., and 12in. square. All are in. thick. They are available in rcorative and functional patterns--the tter designed for control of transmitted lylight and solar radiation. Usually ey are laid up in panels with K in. ortar joints. Any mason can install 3 Glass Blocks; no special tools are quired. Insulated skylights that elimiite many of the problems of ordinary vlights can be constructed using pg :ytrol blocks. For complete details, -ite the above address. In Canada: o< esesr St. W Toronto. Ontario. 1662 Insulation Glass PITTSBURGH CORNING CORPORATION PITTSBURGH Department S-6, One Gateway Center, Pittsburgh 22, Pa. FOAMGLAS COflWIWg the cellular, stay-dry insulation What FOAMGLAS is FOAMGLAS is an entirely unique thermal insulation. Its light-weight, strong, rigid structure provides the combination of the two essentials for efficient, long-lasting insulating per formance. . .FOAMGLAS is completely inorganic and has a closed cellular structure. It is made of glass, expanded about fifteen times into minute, non connecting, hermetically sealed cells. This sealed cellular structure makes FOAMGLAS water-proof and vaporproof, preventing moisture absorption which impairs greatly the effectiveness of many insulations. Being inorganic, FOAMGLAS is fireproof, rot-proof and vermin-proof. These inherent characteristics have enabled FOAMGLAS users to benefit from its long-lasting, constantly-high insulating performance. That is why FOAMGLAS is very rapidly gaining recognition as the ideal insulation for roofs, ceilings, walls, and floors of all kinds of buildings, as well as hot and cold piping, tanka and other equipment. For Building Roofs, Ceilings, Walls and Floors. At Winston-Salem., FOA MGLAS' high strength permitted insulating parking deck-roof of Sears Roe buck s otr conditioned store. In your building, mois ture-proofFOAMGLAS insulation con help maintain air conot/toning system efficiency. How FOAMGLAS can benefit you: _______ Properties ________ Benefits_______ Absorption 0 Moisture reduces insula tion effectiveness and life. FOAMGLAS stays dry, maintain ing constant insulat ing value. Acid Re Impervious to No deterioration of in - sistance common sulation; prevents acids and corrosion of piping add fumes and equipment. Combusti Incombustible Protects from fire bility hazards. Compres 100 Ibs/sq in. Offers unusually high sive strength for varied Strength structural and load bearing applications. Hygro- No increase in FOAMGLAS is its own scopicity weight in 24fi vapor barrier. davs in air at 90% relative humidity . Density 9 lbs/cu ft Lightweight, easy to Thermal fave.) ' handle and install. Conduc tivity^) At 50* F 0.38 Btu/hr/sq Excellent insulating fVF/in. value that remains constant. For Ducts. Light-weight blocks of FOAMGLAS were easily applied to these metal air conditioning ducts at the Moses H. Cone Memorial Hospital, Greensboro, North Carolina. For Piping. FOAMGLAS pipe insulation (available for up to S6 in. pipe size) ipgs applied on this welded pipe carrying cold water for the system air conditioning Pittsburgh's new Gateway Center skyscrapers. For full technical information, please write for our new catalogs indicating which of the above uses of FOAMGLAS you are most interested in. Address Dept. S-6, Pittsburgh Coming Corporation, One Gateway Center, Pittsburgh 28, Pa. ' 1663 Insulation Gloss Pittsburgh Plate Glass Company ^ FIBER GLASS DIVISION One Gateway Center Pittsburgh 22, Pennsylvania FIBER GLASS [GjpP^ Pittsburgh Superfine insulation is composed of extremely fine glass fibers, ranging upward m diameter from only 3/100,000 of an inch. It/s an exceptionally light weight, efficient thermal and acoustical insulating material. When specifications call for controlled heat or cold--or you need sound absorbed or vibration deadened --here are some of the advantages Pittsburgh Superfine Fiber Glass insulation provide: High Thermal Efficiency--Thermal con ductivity, k, at a mean temperature of 75 F is 0.22 to 0.27 Btu/sq ft/hr/deg F/in. thickness, depending on density. Ef Type Den sity (lbs per cu ft) Thick ness (in ches) Approx sq ft per lb Tsr` Lengths (feet) Approx ODof Rolls (in ches) fective for both high and low tempera tures ranging up to 500 F. Fine Acoustical Properties Noise re duction coefficient of a 1 in, thickness is as high as 0.80 with the sound absorption curve showing high efficiencies in the ranges of the most irritating noise. Light Weight, Easy to Handle--Added load in any application is virtually negligible. Density as low as 0.6 pound per cubic foot. Readily cut with knife, shears, or die. Can easily be sewed and quilted, glued, tacked or taped into position. _ Flexible, Resilient, Tough, and Soft Can be used on round or irregularly shaped objects and spaces as easily as in conventional layers. Fits closely into corners and `tight spots quickly and easily, without damage to its structure Saves Vital Space--In use: Higher insulating efficiency means less thickness of Superfine required, as compared to ordinary insulation. In shipment: Pack aged compressed to reduce shipping and storage space. . S-314 S-315 S-316 S-317 S-318 S-319 S-105 0.6 0.75 1.0 1.5 2.0 3.0 0.6 W 'H 1 m 2 3 H y> n i in 2 3 H n M 1 1H 2 3 K M H 1 1H H n H 1 114 H n n i 14 40 26.7 20 13.3 10 6.7 64 32 21.3 16 10.7 8 5.3 48 24 16 12 8 6 4 32 16 10.7 8 5.3 24 12 8 6 4 16 8 5.3 4 40 100 100 100 100 10Q 100 100 100 100 100 100 100 50 100 100 100 100 100 100 100 100 100 100 100 100 10Q 100 100 100 50 100 100 100 50 50 18 22 26 30 32 38 10 16 20 23 26 28 27 10 14 17 20 24 34 . 39 13 18 22 25 31 13 23 27 32 29 16 23 28 26 14 STANDARD SPECIFICATIONS--Pitts (Airburgh Superfine is available in standard craft) roll widths of 18 in., 24 in., 36 in., 48 in., 54 in. and 72 in. It can be supplied in any desired slit down to 2 in. Rolls are wound on 2 in. tubes and wrapped in heavy kraft paper. Superfine is also available in special lengths on request. It can be fumisheavinyl coated, or with various paper, cloth or foil facings. . 1664 Insulation Armstrong COR K S CM P Lancaster, Pennsylvania Uisthict Offices in Majob Cities Low Temperature Insulations Corkboard--Moisture resistant, strong, durable, lightweight, easy to handle. Sizes: 36 in. long; 12 in., 18 in., 24 in., 36in. wide; 1 in., 1% in.,2in.,3in.,4in., 6 in. thick. K factor: 0.27. LT* Cork Coverings--low-cost, easy-toapply insulations for lines operating at temperatures down to --30 F. Made of precision cut segments of corkboard, cemented to 3-ply vaporproof paper. Thickness: in., in., 2 in., 2% in. Armaflex*--flexible plastic insulation for fast installation on copper tubing and other hard-to-insulate lines. For tem peratures from 32 to200F.K factor: 0.28. Inside diameters: % in., % in.,1^ in. 1% in. Armaglas* PF Insulation--all-purpose, easy-to-apply insulation for tanks, ves sels and equipment. Size: 24 in. x 48 in. Densities from 3.5 to 9 lbs per cu ft. Armaglas AB Board--a rigid glass fiber board for cold room walls, ceilings and partitions. Coated with asphalt. Size: 12 in. x 36in. 6 lb and 9 lb densities. fibers in 3 ft. molded half-sections. Fits pipe sizes up to 8 in. and copper tubing up to 3 in. Armaglas PF Insulation--an all-purpose material for use on tanks and vessels operating up to 400 F. Comes in panels and boards; in 7 densities from 2.5 to 10.5 lbs per cu ft. Armaglas Insulating Wool--comes in rolls, batts and shredded; for many in dustrial applications where tempera tures go up to 1000F. Thicknesses:M in. up to 3% in. Armaglas Metal Mesh Blankets--for large, hard-to-insulate equipment. Made of glass fibers faced on one or both sides with wire mesh or metal lath. For tem peratures to 1000 F. Sizes: 2 ft x 8 ft, 2 ft x 4 ft. Thicknesses from 1 in. to 6 in. Armaglas Block Insulation--for boilers, breechings, tanks and other process equipment operating up to 400 F. 6 in. and 12 in. wide, 36 in. wide. % in., 1 in., 1}^ in., 2 in. thick. Duct Insulations Heat Insulations Armaglas PF Duct Insulation--low-cost Armatemp*--strong, mineral wool insu insulation for exterior duct surfaces. lation for tanks, ducts and other heated Size: 24 in. x 48 in. Thicknesses: in. surfaces. In block form for temperatures and 1 in. For temperatures up to 400 F. up to 1900 F; in blankets for temperatures Armaglas Coated Duct Insulation--has a up to 1200 F. neoprene finish to provide good painting Armabestos*--asbestos fibers formed surface and prevent air erosion. Up to into pipe covering and block. Pipe cover 250 F. ing, A-7 for temperatures up to 750 F; Armaglas Vapor-Seal Duct Insulation-- A-12 for temperatures up to 1200 F: both thermal insulation and sound ab Block for use up to 1200 F. sorber with built-in vapor barrier. For Armaglas Pipe Coverings--a glass fiber cool air ducts where condensation is a insulation for temperatures up to 400 F. ' problem. 24 in. x 48 in. size; % in., 1 in., Plain or with aluminum foil vapor jacket. in., 2 in. thicknesses. Up to 250 F. In 3 ft long sections for pipes up to 33 in. Armaglas Flexible Duct Insulation--All in size. Copper tubing sizes from % in. purpose insulating blanket and sound to 6 in. . conditioning for fast application on hot Armaglas WA Pipe Covering--flexible, or cold ducts of any size or shape. Up to light-weight blankets for wrapping 250 F. r around lines operating up to 600 F. Fur Armaglas Flexible Duct Liner--Neo nished % in. thick and compressed to prene-coated and used as sound-ab A in. in application. sorbing insulation inside warm air or Armaglas Blanket Type Pipe Covering-- cooling ducts. 36 in. wide; A in. and 1 in. for irregularly shaped pipes operating thicknesses. Up to 250 F. up to 1000 F. 1 in., 1J in., 2 in., 3 in.,4 in. Armstrong Contract Service thick. Length: 2 in. This complete, nationwide service pro Armaglas Low-Pressure Pipe Covering-- vides materials, engineers, supervisors, for cold water, hot water and low-pres work crews, research and testing facili sure steam lines. Preformed of glass ties. Your nearest Armstrong office will Armaglas is manufactured by the Owens-Caming Fiberglas Corp. * Trade-Mark furnish prompt estimates, technical as sistance and product information with out obligation. 1665 Insulation The Celotex Corporation General Offices 120 South LaSalle Street, Chicago 3, 111. CeiloteX0BEG. . S. PAT. OFF. Celotex Insulation Board Products are made by felting long, tough cane fibers into strong, rigid boards. Manufactured under the exclusive Ferox* Process. Ferox-treated Celotex board has been and edges. Size 24 in. x 48 in., thicknesses 1 in., V/i in., and 2 in. Conductance, "C," of 0.33 Btu for nominal one inch thickness after coating. demonstrated by laboratory tests and years of use to be protected effectively against dry rot and termite attack. In tegrally waterproofed. Celotex Insulating Sheathing--For use in frame construction under wood siding, wood or asbestos shingles, stucco, or masonry veneer. Double-Waterproofed-- integrally treated, then asphalt-coated on all surfaces. Exceeds government vapor permeability requirements. Sizes: 4 ft wide x 8 and 9 ft long x in. or in. with square edges. 2 ft x 8 ft x 2%1 in. with V-type tongue and groove on long edges. Celotex 4 ft wide 2%2 in. Sheathing,applied vertically withovi comer bracing, greatly exceeds racking strength requirements set Flexcell* Expansion Joint Filler--Cane fiber felted into strong, resilient boards, then saturated with durable asphaltic compound. For expansion joint uses, perimeter insulation for concrete floors at grade, sill sealer, plate sealer, and vibration isolation. Thicknesses of J4 in. to 1 in. in various lengths and widths. Cemesto* Structural Insulating Panels-- Completely fabricated panels for curtain walls, roof decks, partitions, air con ditioning duct and roof machinery en closures. Consist of cane fiber board core surfaced on both sides with layer of cement-asbestos board. Sizes: 4 ft wide x 6 ft to 12 ft lengths. Specializes avail able. Thicknesses: in., 1)4 in., l^ie in., 2 in. ` forth in FHA Technical Circular No. IB (racking strength at least equal to hor izontally-applied , wood sheathing with let-in bracing is minimum requirement). Celotex Roof Insulation Celotex Spun Rock Wool Products-- Regular Blankets, full- or semi-thick, 15 in. x 96 in., 15 in. x 48 in., 15 in. x 24 in. Utility Blanket, 15 in. x 96 in. Reflective Blankets, standard thickness, 15 in. x 96 in. Also Loose, Granulated and Hand Pouring Rock Wool. Begular--Natural cane fiber board sur face. Provides excellent bond for pitch or asphalt. Meets requirements for Roof Insulation Board (Class C) of Federal Specifications LLL-F-321b, Commercial Standard CS42-49 of U. S. Department of Commerce, and ASTM Specification C208. Sizes: 23 in. x 47 in., 24 in. x Q-T* Ductliner--Sound absorbing ma terial designed for duct lining in air conditioning systems. Made of rock wool and specialbinder. Withstands air duct humidity, is fire-resistant and will not support combustion. Thermal conductivity of 0.30. 48 in. Thicknesses: )4 in., 1 in., \\4 in., 2 in. Celotex Sound-Conditioning Products-- Complete line of specialized acoustical Preseal--Coated with special asphalt on materials to comply with every require all surfaces and edges for additional ment, specification, or building code. moisture protection. Size: 24 in. x 48 Distributors in principal cities. in. Thicknesses: )4 '> 1 in., 1)4 in., 2 in. Channel-Seal--Specially fabricated with 1J4 6 in. x in. bevel on underside of all edges to form interconnecting channels for equalizing air pressure between roof Celotex Interior Finishes--Tile Board, Finish Plank, Building board--triple duty products that build, decorate, in sulate. Variety of sizes and finishes. ing and deck. Asphalt-coated all surfaces Beg. U. S. Pat. Off. For detailed information on &U Celotex products, see Sweet's Files or write The Celotex Corporation 1666 . . The Dow Chemical Company . Plastics Sales, Midland, Michigan Insulation STYROFOAM RIGID LOW TEMPERATURE BOARD INSULATION PROVIDES EXCEPTIONAL RESISTANCE TO WATER, ASSURES LONG SERVICE LIFE You'll find that Styrofoam . . . Dow's rigid low temperature board insulation ... is right for your job. Styrofoam combines all the factors you want: high thermal re sistance, low original cost, long service life and a minimum of maintenance. Commercial applications in many fields prove Styrofoam is an excellent rigid-type low insulation material. Its closed cellular structure provides exceptionally high re sistance to water and water vapor. Styrofoam's low "K" factor (0.25 Btu/sq ft/hr/F/ inches at a mean temperature of 40F) assures maximum thermal efficiency Styrofoam is available in two grades: Styrofoam 22 (regular) and Styrofoam 33. (self-extinguishing). For more detailed information contact your nearest sales office. Atlanta Boston Buffalo Chicago Cincinnati Cleveland Detroit Houston Los Angeles Minneapolis New York Philadelphia t St. Louis t San Francisco Seattle. STYROFOAM GIVES YOU ALL THESE ADVANTAGES FOR: Pipe Covering Insulated Vehicles * Refrigeration Equipment t Low Temperature Rooms Perimeter Insulation High Thermal Resistance Water Resistance, freedom from capillarity Long Insulation Life Low Cost Installation, Maintenance, Operation Odorless t Resistant to Rot and Mold t Light Weight # Easy to Fabricate * Sizes for any job Thicknesses: 1, 1)4, 2, 2)4, 3, 4, 5 in--Widths: 10 in. and 12 in.--Lengths: 36 in. and 9 ft. 1667 INSULITE DIVISION Minnesota General Office: 500 Investors Bldg., Insulation and Ontario Paper Company Minneapolis 2, Minnesota STRUCTURAL INSULATION BOARD For 42 years engineers and architects have specified Insulite materials for archi tectural uses, interior finish, and for other thermal insulation and sound control uses, Insulite materials have proved their merit through actual performance on the job. STRUCTURAL MATERIALS Condensation Control--To prevent con densation within walls, authorities rec ommend "sealing the warm side and venting the cold side" of the wall. Insu lite Insulating Wool Batts or Blankets provide the necessary vapor barrier on the warm side of the wall, thereby re ducing the flow of vapor into inner wall areas. On the cold side of the wall, vaporpermeable Bildrite Sheathing allows surplus vapor to escape toward the out side. Bildrite* Sheathing--A tough, durable, insulating sheathing material made from new wood fibers. Protected through out by an integral asphalt treatment. Bildrite (4 ft width) has more than twice the bracing strength of horizontal wood sheathing. 25^2'*n-thick. Sizes: 2 x 8 ft (V-joint on long edges) ... 4 x 8 ft to 4 x 12 ft (square edges). Thermal con ductivity: 0.37 Btu per inch thickness. Also available is 34~'n- Graylite Sheath ing. easier, better-looking shingled walls at low cost. Two widths: 13)4 in. for 12-in. shingle exposure, 15)4 in. for 14-in. shingle exposure. Four ft long. Applying shingles and Shingle-Backer A different Shingle-Backer System is used for asbestos-cement siding shingles. 11%-in. Shingle-Backer is .used to give modern shadow-lines. Also protects against breakage, helps sound condition house. Both systems give added insulation, greater structural strength and weather resistance. No building paper is re quired. Can be applied over Bildrite and Graylite* Sheathing. ROOF INSULATION Applying Bildrite Sheathing SHINGLE-BACKER Insulite Roof Insulation is fabricated from either Ins-Lite or Graylite insula tion board. The 34-in. thickness has square edges. The 1,134, and 2-in. thick nesses are multiple layers stapled or ce mented together. Available with either square or offset edges. Size: 24 in. x 48 in. Shingle-Backer is a fast-applying, in sulating undercourse material for double-coursed, shingled walls. Made from 5ye-in. insulation board, water proofed throughout with asphalt. There are two Shingle-Backer Systems. For wood-shingled sidewalls, Shingle- Backer panels take the place of low-grade wood undercourse shingles. Makes faster, INSULATING WOOL Insulite Insulating Wool is made from famous "Fiberglast," consisting of millions of long glass fibers bonded to gether with a thermo-setting resin. Available in the following forms: roll blankets, batt blankets, utility batts, plain batts and pouring wool. 1668 Insulite Insulation Perimeter Insulation--Fiberglas Per imeter Insulation guards against heat loss in basementless houses. Meets F.H.A. and specific job requirements. Type AE-6 (asphalt enclosed), Type PF-615 (paper faced) and Type PF-619 (paper faced, load bearing). , INDUSTRIAL INSULATION Choose from Six Types (1) Low Density Ins-Lite*--a low density board with high insulating effi ciency and maximum sound absorption. Density 10.0 to 12.5 lbs/cu ft. (2) Medium Density Ins-Lite--an insulating board which provides efficient insulation and structural strength. Density 12.5 to 15.0 lb/cu ft! (3) High Density Ins-Lite--designed to be used where insulation and struc tural strength are required. Density 15.0 to 17.5 lbs/cu ft. (4) Low Density Graylite--a highly efficient insulating board. integrally treated with asphalt for increased strength and resistance to water absorp tion. Density 13.5 to 16 lbs/cu ft. (5) Medium Density Graylite--an in sulating material integrally treated with asphalt. Has high strength and resistance to water absorption. Den sity 16.0 to 18.5 lbs/cu ft. (6) High Density Graylite--an insu lating material with maximum strength and resistance to water absorption. Density 18.5 to 21 lbs/cu ft. INTERIOR FINISHES Roof Deck--A 3-in-l fiber board product for roofs that serves as decking, insula tion and finished ceiling. Ceiling side has white, textured, flame-resistant surface. Available with or without vapor barrier. Size: 2 x 8 ft panels 1J4 in., 2 in. and 3 in. thicknesses. Graylite Building Board--A durable board, integrally treated with asphalt for maximum strength and moisture re sistance. Thermal conductivity is 0.37 Btu per in. thick. Sizes: 4 x 8 ft to 4 x 12 ft. Thicknesses: 34, %, and 1 in. Primed Graylite Building Board--Gray lite Building Board with a prime coating for easy painting. Sizes: 4 x 8 ft to 4 x 12 ft. Thicknesses 34 and % in. Smoothllte* Interior Board--A naturalcolored, factory-coated board, gloss finish. 67 per cent light reflection. Sizes: 4 x 6 ft to 4 x 12 ft. Thicknesses: % and H in. Wevelite* Interior Board--A practical, low-cost interior board with flame-re sistant finish in white. Sizes: 4 x 6 ft to 4 x 12 ft. Thickness 34 in. Durollte* Tileboard--A textured flameresistant finished board, in white and light ivory colors. Has flanged tongueand-groove joint. Thickness: 34 in. Sizes: 12 x 12 in. to 16 x 32 in. Durolite Plank--Flanged tongue-andgroove joints. Textured, flame-resistant surface finish: 34 in. thickness. Colors: ivory, pale green, sunlite yellow, and woodtone. Sizes: 8, 12, and 16 in. wide; and 8 and 12 ft long. Fiberllte* Acoustical Tileboard--A lowcost, highly efficient acoustical tile, has effective flame-resistant white finish. Sizes: 12 x 12 in. to 12 x 24 in. Thick nesses: yi and % in. Acoustilite* Perforated Tileboard--A rugged, sound-absorbing tileboard for residential and commercial interiors. Standard tile units contain 484 cleanlydrilled holes. 34 Va in. thickness. Also random drilled Acoustilite Tileboard in 34 or % in. thickness. White finish has high light reflection. Has effective flame resistant finish. Size: 12 x 12 in. Applying Insulite Roof Deck Reg. U. S. Pat. Off. Applying Random Acoustilite HARDBOARD PRODUCTS Insulite HardBoard is a rigid, durable, wood-fiber material with tremendous strength. Available in a range of densi ties from 55 to 68 lb per cu ft. Thicknesses from J4 to 546 >n. Sizes from 3 x 4 ft to 4 x 16 ft. t Reg. U. S. Pat. Off.--Made by Owens-Corning Fiberglas Corp. 1669 Insulation Johns-Manville Executive offices: 22 East 40th Street, New York 16, N. Y. Offices in All Large Cities Home Insulation Applying Spintex batts tn new home For Existing Homes and Buildings: J-M Spintex "Blown" Home Insulation J-M Spintex Home Insulation is nodu lated mineral wool which is blown pneu matically into the spaces between studs in outer walls and between roof rafters or attic floor joists. Insulation thickness in walls corresponds to stud depth, approximately in. The uni form fill assures maximum thermal effi ciency. This type of insulation is sold and installed only by carefully selected experienced and officially franchised J-M Blown Home Insulation Contrac tors. For complete information on J-M Spintex "Blown" Home Insulation and its application, write the address above or call your local Johns-Manville office. For New Construction: Spintex Batts and Blankets Johns-Manville Spintex Batts and Blankets are made of spun rock wool. Instead of short, coarse fibers, this J-M spinning process produces long, fine fibers which make better, more firmly felted batts and blankets that are stronger, lighter in weight, more resil ient, and have greater uniformity throughout. They are rotproof, fireproof, and assure the homeowner of maximum year-round comfort, protection and winter fuel savings. SPINTEX BATTS are strong and sturdy. They will not break down under rough handling but hold their factory:maae shape and uniform thickness . . . will not crumble or fray when cut to fit irregular spaces. Each batt has a vapor seal back ing to protect against the passage of abnormal humidity and a tacking flange for ease of installation. Spintex Batts are furnished Ful-Thik and Semi-Thik. Ful-Thik Batts have an average thickness of 3)4 in*; Semi-Thik, an average thickness of 2 in. Both types are available in sizes 15 x 24, 15 x 48, 19 x 24, 19 x 48, 23 x 24 and 23 x 48 inches. SPINTEX BLANKETS, made of the same firmly-felted long fiber spun rock wool, are fully enclosed in a permeable wrapping with an approved vapor seal backing and a tacking flange. Thick Blankets, approximately 3 in. in thickness, are furnished in sizes 15 in. x 48 in. and 23 in. x 48 in.; Medium Blankets, approximately 2 in. thick, in sizes 15 in. x 64 ft, 23 in. x 64 ft, 15 in. x 8 ft and 23 in. x 8 ft; and Service Blankets, approximately 1)4 in. thick, in sizes 15 in. x 8 ft and 23 in. x 8 ft. Airacoustic Sheets for lining Air-Conditioning Ducts J-M Airacoustic Sheets provide a firesafe, sound-absorbing material de veloped for use in ventilating ducts. Since they absorb a large percentage of the sound that strikes them, they pro vide a highly effective means of reducing undesirable duct noises. Composed of rock wool and a suitable binder, Aira coustic Sheets are available in size 24 in. x 36 in., and in thicknesses of )4 in and 1 in. Spintex Duct Insulations Spintex Duct Insulations are incom bustible . . . provide high insulating effi ciency and long service life. Their low installed cost is the result of JohnsManville's long experience in developing scientifically correct insulations and proper methods of application. They are furnished as blankets and semi-rigid boards. The densities range from 2 to over 6 lb per cu ft, providing flexible and stiff materials for round or rectangular ducts. 1670 Johns-Manville Pipe and Boi J-M FIBROCEL Insulation Insulations J-M 85% MAGNESIA J-M Fibrocel Pipe Insulation is a molded silica insulation developed by JohnsManville for use on hot, cold and chilled water lines, low pressure steam pipes,, and dual service heating and cooling sys tems. It can't shrink or expand which means no more gaping, unsightly joints with accompanying heat leakage. Its firm, hard texture resists deformation and its combination of thermal proper ties and recommended wall thicknesses in the services for which it is designed provide maximum economical insulation effectiveness. Fibrocel resists decay, fire and vermin. Lightweight, precisionformed for exact fit, and easy to cut and work on the job, it speeds application and keeps costs at a minimum. Fibrocel is furnished in three jacket styles: Fibrocel C with standard or special weight canvas jacket for steam, hot or cold water service from 60F to 300F; Fibrocel G with glazed white lastic-coated paper jacket for steam, ot or cold water service from 60F to 300F; and Fibrocel VB with vapor bar rier jacket, recommended for use on pipes subject to sweating and particu larly adapted for dual service heating and cooling svstems between 35F and 225F. PRE-SHRUNK ASBESTOCEL Cellular type insulation made up of alternate layers of plain and corrugated asbestos felts for use on pipes conveying low pressure steam and hot water. Three finishes: Glazed White, Asbestos Paper and Canvas. Furnished in3-ft sections to fit standard pipe sizes* and in standard thicknesses of 2 to 8 plies, each ply ap prox. in. thick. Temp, limit, 300F. ASBESTOCEL SHEETS AND BLOCKS For insulating medium and low pressure boilers, feed water heaters, warm air ducts, etc. Furnished 6 to 36 in. wide, 36 to 96 in. long, from )4 to 4 in. thick. * Also available to fit straight runs of copper tubing with nominal diameters of ? in. and up. The high insulating value and per manence of J-M 85% Magnesia Block and Pipe Insulation have been proved over many decades of satisfactory, trouble-free service. Blocks are fur nished 18 and 36 in. long; 3 and 6 in. wide (flat or curved), 1 through 4 in. thick; 9 and 12 in. wide (flat only), 1)4 through 4 in. thick. Pipe insulation is furnished in 3-ft lengths in sectional or segmental form for all standard pipe sizes, in nominal thicknesses up to 3 in.* Temp, limit 600F. SUPEREX COMBINATION Superex Combination Insulation (an inner layer of J-M Superex, a material with high heat resistance, and outer layer of J-M 85% Magnesia, a material with great insulating value) is recom mended for temperatures from 600F to 1900F. Both Superex and 85% Magnesia are available in sectional and segmental pipe covering and in block form. ROCK CORK Rock Cork is made of mineral wool and an asphaltic binder molded into sheets and pipe insulation for all low tempera ture service. It is strong, durable, and will not support vermin. Because of its unusual moisture-resistance, its high insulating value is maintained in service. Furnished in sheets 18 in. by 36 in., (18 in. by 18 in. available in 1 in. thick ness only), in 1, 1)4,2, 3 and 4 in. thick nesses. Lagging, for curved surfaces, supplied 18 in. long by 1)4 through 4 in. thick, 2 to 6 in. wide, depending on diameter. Pipe covering furnished in Ice Water, Brine, and Heavy Brine thicknesses, for all commercial pipe sizes.* Discs also available to a 36 in. max. diameter. DETAILS ON REQUEST For further information about J-M In sulations and J-M Application Service, write Johns-Manville, 22 East 40th St., New York 16, N. Y. Insulation Kimberly-Clark Corporation Neenah, Wisconsin KIMSUL MODIM I 01 KlmberlyClark INSULATION New York 17, N. Y., 250 Park Avenue Atlanta 3, Georgia, 900 Peachtree St., N. E. Chicago 3, Illinois, 8 S. Michigan Avenue San Francisco 4, Calif., 155 Sanbome Street Reflective and Pyrogard KIMSUL* is unique among building in sulations and acoustical materials be cause it is made of many individual plies --each one a continuous separate layer of soft, clean, creped, ashpalt-treated cellulose fibers. Each ply is controlled carefully inmanufacture both as to thick ness and crepe structure. The result is a flexible blanket, inherently uniform in thickness--an important factor in a thermal or sound insulating material. The Kimsul plies and cover of the creped Pyrogard* or creped Reflective Vaporseal are held together with rows of strong stitching that prevent sifting and settling. No heat-leaking thin spots, no money-wasting thick spots in the Kimsul blanket. Reduced to H its installed volume for easier shipment, handling and storage, the Kimsul blanket is expanded in installation. The stitching controls expansion to the density of a high degree of efficiency. KIMSUL IS NOW MADE IN THREE TYPES-KIMSUL 48 SHEATHING BLANKET --PYROGARD KIMSUL REFLECTIVE KIMSUL. Kimsul 48--Sheathing Blanket is Reflective Kimsul Insulation manufactured by the Kimberly-Clark Corporation to a width of over 48 inches, pre-cut to eight foot lengths which makes it possible to build a more heat-tight, air-tight and vapor-tight dwelling wall at lower cost than ever before. Kimsul "48" Sheathing Blanket retains the recognized insulating qualities of chemically treated wood fibres arranged in multi-ply layers of air cells that are well Known in Kimsul insulation material. It is a recognized fact that this construction of an insulating material produces outstanding results. Sheathing Blanket's wood fibre construction, extremely tough, three-ply, heat re flective, vapor sealing cover give the American home building industry a material which minimizes the problems of vapor and heat transmission which have always been most difficult to solve economically. SOME FEATURES OF KIMSUL 48 SHEATHING BLANKET Positive insulation incloseframing areas. No heat loss or cold air leaks in areas that couldn't be sealed before Kimsul "48". Positive insulation aroundelectricalreceptaclesand be hind conduit. Repairs and replacements of these items do not damage the insulating material. Complete insulation between the cold exterior wall and metal ductwork. Minimises Seating expense ... gives greater comfort. T. M. Reg. U. S. Pat. Off. Positiveseal ofexposed sub-floor ends. Eliminates colddrafts and heat losses. 1672 Kimberly-Clark Corporation Insulation Pyrogard and Reflected KIMSUL* Kimsul is also available for all conventional ceiling, wall, and floor construction in Pyrogard and Reflective types. . . . The differences in the two types are: Reflective Kimsul has a cover of aluminum foil that acts both as a vapor barrier to shut out condensation, and as a highly efficient reflective surface to turn back radiant heat. Reflective Kimsul has strong reflective tacking flanges for easy, secure attachment to framing. For heat flow downward. Reflective Kimsul provides additional insulating value. Pyrogard Kimsul has the fire-resistant cover. Fire-Resistant--Special permanent chemical treatment makes Kimsul resist fire. Pyrogard* Fire-Resistant Cover--(safety feature of Pyrogard Kimsul) resists flamespread. Creped Aluminum Foil Cover--(a fea ture of Reflective Kimsul) reflects heat, shuts out condensation. , Moisture-Resistant--asphalt treatment of each ply sheds water. Resists Mold, Rot, Vermin--The ma terials of which Kimsul are made offer no subsistence to vermin or insects. Special chemical treatment resists mold and fungus. "k" Factor--0.27 Btu/sq ft/hr/F. RejieU*fft l, tn*Utliea. Edge of fastening flange folded over face of framing completes the tapor seal. Air Space--is a prime requisite. Use a vapor-permeable building paper under ex terior finish. Ventilation in attics and floors should never be omitted. Use approxi mately one sq ft of louver area for 1000 sq ft of ceiling area. TYPE Pyrogard Kimsul (Red Package) Reflective Kimsul (Grey Pack age) GRADE RESISTANCE VALUES, fl) WALL CEILING FLOOR Heat Flow Hori Heat Flow zontal Up Heat Flow Down Heat Flow Down APPROX. SQ FT PER ROLL STANDARD ROLL WIDTHS 16. 20, 24 inch 48 inches APPROX NET WEIGHT PER 1,000 SQ FT APPROX SHIP PING WEIGHT PER 1,000 SQ FT Commercial Thick 1.85 Standard Thick 3.70 Double Thick 7.40 1.85 . 1.85 3.70 3.70 7.40 7.40 1.85 200 Sq Ft 500 Sq Ft 68 Lbs 3.70 200 500 120 7.40 100 250 225 75 Lbs 126 236 Medium Thick Double Thick 5.07 4.63 6.87 6.94 200 7.80 7.40 9.64 9.70 100 500 250 134 195 140 205 OR CARTON ("48") PER ROLL OR CARTON ("48") Kimsur`48" "48'' "48" "48" 3.28 3.28 3.38 640 Sq Ft 832 1024 75 Lb 97 120 SOUND DEADENING AND ABSORPTION Kimsul is effective both in deadening sound and absorbing it. It will absorb sound originated by diaphragmatic ac tion, and sound leaks, as well as cushion ing furring strip type construction. Kim sul prevents bridging or short circuiting of sound-resisting construction during erection. The average coefficients of sound asborption of Kimsul are:* Double Thick 75%^ Standard Thick 55% Commercial Thick 40% Kimsul should be spaced from one to six inches from reflecting surface, with cover side away from sound source to obtain greater absorption at lower frequencies. CONSTRUCTION DETAILS AMD HEAT FLOW (U) FACTORS KIMSUL GRADE HEAT FLOW HEAT FLOW HEAT FLOW HORIZONTAL UP DOWN Uninsulated Pyrogard Commercial Thick Kimsul 48 Sheathing Blanket Pyrogard Standard Thick Pyrogard Double Thick Reflective Medium Thick Reflective Double Thick "U" .25 .15 .12 .08 .10 .08 % -- 40 52 68 60 68 **U" .69 .25 .17 .10 .15 .10 % -- 64 75 85 78 85 "U" .48 .20 .15 .09 .10 .08 % __ 58 69 81 79 83 HEAT FLOW DOWN "U" .28 .16 % ___ 43 .12 57 .08 71 .09 68 .07 75 K Factor (KIMSUL plies) 0.27* authority of J, C. Peebles, Armour Institute. (Does not include value of reflective coyer.) * Factors expressed m Btu/he/sq ft/eF; k, per inch of thickness; "U", per assembled section of construction. Calculation based on FHA Technical Circular No. 7, dated Jan. 1949. % = % of uninsulated heat flow stopped in the insulated construction. Resistance of Kimsul 48 is 3.28 authority F. B. Rowley, University of Minnesota. (Includes value of reflective cover w/o air space.) * T. M. Reg. U. S. Pat. Off. 1673 Insulation Lockport Mills, Inc. Thermal and Acoustical INSULATION Dept C. Lockport, N. Y. Moisture-Resistant--Chemical treat ment, combined with natural protective coating on cotton fibres, enables cotton to effectively resist moisture. Prevents rot and mildew. Smooth Texture--No sharp particles to irritate the skin. Flexible--Cotton batt may be ex panded or contracted to fit any enclosure. Easy to Warehouse and Handle. Offers far more "compressibility." Requires one-third the trucking and warehouse space of ordinary insulation. Five featured types to meet every insu Simple and Economical to Install. Saves from 25 to 40 per cent in costs. lation need: (1) OPEN BLANKET backed by tough, waterproof, asphalt-coated kraft paper to form an effective vapor barrier. (2) ENCLOSED BLANKET. Insulation completely enclosed in enve lope, asphalt-coated paper on one side, porous or "breather" type paper on Designed to Maintain Maximum Util ity. Resists all types of deterioration. Won't sag or settle. Packaged in Rolled Form. Thicknesses--inches: 1, IK 2, 3, 3%. Width--16, 20, 24 in. centers. Lengths: other. (3) OPEN ALUMINUM FOIL. Standard from 12 ft up. All the features of Open Type (1) plus the extra value of aluminum foil backing. Effective vapor barrier . . . stops 90 per INSULATING VALUE OF VARIOUS INSULATORS4 cent of radiant heat. (4) ENCLOSED ALUMINUM FOIL. Superior in insula The coefficients of conductivity (4 value) are expressed in Btu per hour per square foot per degree Fahrenheit per 1 in. of thickness. tion plus values and thermal efficiency. (5) DOUBLE FOIL, aluminum foil on Type of Insulation Wgt;j>er 4 Cu Ft Value top and back, plus superior Lo-K Cotton: Insulating Batt.................. .875 0.24 Blanket efficiency for tops in insulating Rock Wool: Fibrous material made 10.00 0.27 value. Thermal Conductivity--The "k" value for cotton is 0.24 Btu/hr/sq ft/degree F/inch. (See table.) Light Weight--Weight of 1 cu ft is % lb. (See table.) Mineral Wool: Fibrous material made from mineral slag.............. Glass Wool: Fibrous material made from glass slag................................ Rigid Insulation made from sugar cane fibre......................................... Chemically treated wood fibre be- tween layers of paper................ . Eel grass between layers of paper.. Stitched and creped expanding fibrous blanket.............................. Sh&vings: Various from planer... Corkboard: No binder added. -... Rigid insulation made from wood 1.50 13.50 3.62 1.50 8.80 7.00 15.90 0.27 0.27 0.33 0.25 0.27 0.41 0-27 0.33 Flame-Proofed--Withstands 1800 blow torch heat. 4 Compiled from Chapter 9,1954 JMition. b "4" indicates temperature conductivity. -1674 Insulation INSULATION The Pacific Lumber Company 100 Bush Street, San Francisco 4, Calif. IDEAL PILL INSULATION FOR REFRIGERATION OR AIR CONDITIONED STRUCTURES REFRIGERATION REQUIREMENTS COMPLETELY FULFILLED BY VOID-FREE PALCO WOOL Extremely low thermal conductivity over a wide range of mean temperatures is due to low conductance through the material itself, void-free application pro viding full insulation without pockets or joints, and virtual elimination.of convec tion current losses. Initial and operating economy result from low material cost, simple structural requirements, ease of installation, efficiency minimizing re frigerating equipment requirements, and permanent effectiveness proved through exhaustive in-place field tests. Fire re tardant by nature, Palco Wool is further protected by the unique Saferized proc ess. Odorless, repellent to rodents and insects, and moisture resistant, Palco Wool is ideal for freezers, coolers, con trolled atmospheres. Am CONDITIONING EFFICIENCY INCREASED BY PALCO WOOL IN HOME OR COMMERCIAL USE Maximum performance of home or com mercial air conditioning and heating equipment is assured by Palco Wool's unique combination of qualities. It is recognized to have one of the highest efficiency ratings of ail insulations. Per manent resilience guards against settle ment, providing full insulating effective ness for the life of the building. Not only is natural fire retardance increased by the unique Saferized process, but Palco Wool also resists breakdown or melting under high temperatures. Free from odors, non-irritating, moisture resistant, repellent to rodents and insects, Palco Wool has proved its effectiveness for Eublic or private building insulation. ow cost, ease of installation, and light weight recommend it from the stand point of architects, designers, applica tors and users. . WRITE FOR THESE HELPFUL BOOKLETS AVAILABLE ON REQUEST NEW REFRIGERATION INSULATION MANUAL Handy illustrated reference manual covering details of design and construction for freezers, coolers, and controlled atmos pheres. Vapor proofing, void-free application of Palco Wool Insulation, U values of various types and thicknesses of in sulated walls and ceilings, and other valuable data are pre sented in easy-to-follow drawings, photographs, charts and text, compiled by experienced refrigeration engineers. FACTS ABOUT HOME INSULATION Attractive new booklet outlining the economic and comfort advantages of proper home insulation, showing where, how and when to insulate. Written in layman's language to help air conditioning and insulation merchandisers present a sound effective sales story. OTHER TECHNICAL DATA AVAILABLE--In-Place Tests, design data developed through refrigerated wall tests. Engineering Reports, on-the-job findings covering operation over periods of several years. Samples of Palco Wool Insulation. 1675 Insulation Tectum Division S*Sci,5 General Offices: 105 South Sixth Street, Newark, Ohio lectum SIDEWALL INSULATION Sales Offices: Atlanta, Geobgia--333 Candler Building Chicago 4, Illinois--855 Board of Trades Building ' Comtmbot 15, Ohio--3560 Le Veque-Lincoln Tower Philadelphia 3, Pa.--Suite 2718-2719 Lewis Tower Tectum is composed of fine grade .select wood fibers and a chemically-stable, in organic, water-insoluble hydraulic ce ment binder. Widely used in commercial and industrial buildings, Tectum's bene fits are so numerous that it practically Use Tectum to form insulated outside walls or partitions between areas--it also provides a noncombustible fire barrier. Meeting or exceeding normal insulating requirements, Tectum has high thermal qualities because of the nature of its cel lular structure. When used as a roof obsoletes other type materials of com deck, with built up roofing, Tectum pro parable cost. It's insulating vides "U" values from 0.22 to 0.15. This same structure provides acoustical values, supplying noise reduction coeffi It's structural cients up to 0.85, depending on thick It's acoustical ness.* a It's non-combustible Install Tectum Sidewall Insulation It's good-looking It's light weight It's easily worked It's fungus, termite and rot-resistant with screws or clips--it's quickly erected and may be sawed, kerfed, mortised or nailed with standard woodworking tools. Once installed. Tectum may be spray painted or left its natural, off- It's dimensionally stable white shade. Tectum gives you everything you want in sidewall insulation plus low original cost . . . long service lifd . . . and negli gible maintenance. Seldom do you find a For complete information on Tectum see your nearest sales office, or write for Bulletin No.C-100, (Sidewall Insulation) or No. A-100 (Roof Decks). Thickness; I?< in. to 3 in.; Widths, 24 in., 30 in. product that fills so many needs. and 32 in.; Lengths, 48 in, to 96 in. 1676 Insulation New Yohk Wood Conversion Company Dept. 220-6 First National Bank Building Chicago Buffalo St. Paul 1, Minnesota Boston Kansas Crrr . Detroit St. Paul San Francisco Atlanta EFFICIENT INSULATION FOR EVERY NEED For many years a leader in the insula tion field. Wood Conversion Company manufactures a complete line of flexible fiber and rigid insulation for all indus trial and domestic purposes. This in sulation is the product of scientific research, and is especially designed to embody the most desirable qualities for every use. Backed by the name of Wood Conversion Company this insula tion assures high efficiency and long, satisfactory service. Balsam-Wool* Sealed Blanket Insulation is a flexible insulation. The insulation blanket is made from new wood fibers, completely enclosed on both sides and edges with heavy asphalt saturated and coated kraft liners. Years of practical application and con stant testing are behind each of these Balsam-Wool features-- Integral, continuous vapor barrier Sturdy wind barrier Special spacer flange Double bonding of mat to liner Rot and termite treatment Highly fire retardant In addition, Balsam-Wool is manufac tured under rigid quality control; proved by more than a quarter century of ex perience. Tufflex--A soft, felted blanket material with exceptional insulating and cushion ing qualities. Tufflex is made from clean, new, cellulose fibers, felted and bonded into a fleecy, homogeneous mat, proc essed to resist mold and vermin. It may be moisture resistant or absorb ent. Surfacing of kraft paper can be fur nished on one or both sides; cottonette or scrim can be applied to one side of the plain mat. Wnere the use requires, Tufflex Type "U" can be furnished with a fire retardant treatment. The soft, but firm, felted construction of Tufflex gives the properties of low trans mittal of heat, sound or vibration, and of holding its shape after being cut. -4 replying Nu-Wood Interior Finith Applying Balsam-Wool Sealed Imutation NU-WOOD* STRUCTURAL INSULATION Nu-Wood Interior Finish--A multiplepurpose wood fiber material available in tile, plank and board. Nu-Wood insu lates, decorates and quiets noise. Nu- Wood's colors are soft and harmonious Nu-Wood Sheathing--A strong, struc tural insulating sheathing in % in. and 25/32 in. thickness, asphalt impregnated offering complete moisture protection. --will not fade. The Nu-Wood interior finish line includes Sta-lite, an insulating interior finish with more than 70 per cent light reflection. Nu-Wood Roof Insulation--Will fill all requirements of Federal specification LLL-F-321b. Furnished in any prac Bey. V. s. Pat. Off tical thickness. IM7.71GS 1677 Insulation Reflects American Flange & Manufacturing Co. Inc. 30 Rockefeller Plaza, New York 20, N. Y. Plaza 7-2200 Terrolherm Reg. U. S. Pat. Off. METAL INSULATION FULLY PROTECTED BY U. S. AND FOREIGN PATENTS an average of 25 per cent to 30 per cent. In ceiling (or roof) alone, Ferro-Therm will reduce fuel costs by 15 per cent to 20 per cent. During the summer, the in stallation of Ferro-Therm metal insula tion will reduce temperatures in the house by 10 F to 12 F. Gives the Protection of Metal Because Ferro-Therm is metal (1) It is not only non-combustible, it is an effec tive fire stop for wooden framework; (2) It prevents the penetration of termites, rodents and insects; (3) It does not ab sorb moisture or convey any wood-rot Fcrro-Therm is Stapled Permanently in Place ting moisture in framing members; (4) It, does not settle or pack down, as the sheets are stapled permanently in place. Ferro-Therm Metal Insulation, avail (5) It is absolutely permanent. able from sheets of aluminum or steel with a special alloy coating, reflects 90 per cent to 95 per cent of all radiant heat. This high reflectivity, combined Ferro-Therm is Easy to Install with extremely low heat storage capac ity, provides maximum insulating effi ciency in a minimum overall thickness. Ferro-Therm takes up considerably less space than mass insulation of equivalent efficiency. Laboratory tests and thou Reflects Heat from Either Side sands of applications have demonstrated that a wall of Ferro-Therm will provide insulating efficiency equivalent to mass Ferro-Therm's high reflectivity enables insulation approximately twice as thick. it to resist the penetration of heat from And Ferro-Therm can be installed either side. During the winter it reflects easily, quickly and economically. The heat in; during the summer it reflects heat out--assuring year 'round comfort and a considerable saving in fuel. In stalled in ceiling (or roof) and exterior walls, Ferro-Therm reduces fuel costs by sheets take up considerably less space than mass insulation. And they are light--easy to transport and handle. One man can install 1000 to 1200 sq ft of Ferro-Therm in a day. 1678 Infra Insulation, Inc, 525 Broadway, New York, N. Y. Telephone: WOrth 4-2241 Insulation FOR COLD STORAGE, CRAWL SPACES FOR CEILINGS. WALLS, FLOORS. NOTE Full ONE-INCH EXTRA AIR SPACE Infra Insulation Type 6 has 3 tough, aluminum sheets, 6 heat-ray-reflective surfaces, two outer, and four rows of inner reflective spaces. (Total, 6 reflective spaces.) Easily and quickly installed between wood joists, furring strips; steel trusses, studs, purlins; metal beams and girders, it gives the entire area between, up to the very edges, full, uniform-depth protection against heat flow and vapor flow. The normal installation rate between wood joists is 2,000 sq ft a day per man. The 2% cu ft carton contains 500 sq ft, weighs 52 lbs. For 12 in., 16 in., 20 in., and 24 in. centers. Heat flow through wall space, which is air, is about 7 per cent by Conduction; 15 per cent to 28 per cent by Convection; and by Radiation, 65 per cent to 80 per cent. RADIATION:--Each of Infra's 6 aluminum surfaces has a low absorptivity and emissivity of only 3 per cent, and a high reflectivity, 97 per cent, for radiation. The sur faces of most building materials have an absorptivity and emissivity of about 90 per cent with about 10 per cent reflectivity. CONDUCTION:--Infra's 6 deep air spaces have low density, therefore slight conduction. One sq ft of Type 6 weighs only oz, a ratio of 296 parts air to 1 part mass. CONVECTION; VAPOR:--Each of the 3, continuous, 375 ft long, tough alumi num sheets has almost ZERO permea bility to heated air, cold air, and water vapor. Infiltration under flat stapled flanges is slight. Each of the 2 fiber sepa rators and 3 aluminum sheets retard flow of heat by CONVECTION. Infra Insulation uses 99.4 per cent pure aluminum, made to special 3 per cent emissivity specifications, 0.002 in. and 0.0009 in. thick where exposed. It has 52 lb and 17 lb bursting strength (Mullen Test), and 80 grams and 28 grams tearing strength. This is up to 2600 per cent tougher than commonly used foils of less than 0.0005 in. thickness. Even tougher are Infra's newest, 3-ply, laminated alum inum sheets. FIRE:--Because its aluminum surfaces have very low emissivity (3 per cent) and a high melting point (1220F), Infra has often prevented the spread of fire. NON-CONDENSATION-FORMING:-- The 2 fiber separators which permanently prevent metal-to-metal contact, and the 3 aluminum Bheets create FOUR inner rows of reflective air spaces. This scien tific construction, and the low heat storage capacity, minimize condensation formation on or wdthin this type of insu lation. SANITARY:--Infra is inhospitable to in sects, and DOES NOT RETAIN odors. Mechanics like to work with Infra. It is CLEAN, free of DUST or lint, perma nently free from floating particles. Write for a free copy of "Heat Flow by RADIATION in Building Structures, Simplified Physics," a new, 48-page, il lustrated manual by Alexander Schwartz, president of Infra Insulation, Inc. 1679 Silvercote Products, Inc. 161 East Erie Street, Chicago, 111. S I LV E R CO T E* REFLECTIVE INSULATION Insulation Silvercote Heat Reflective Surfaces--The silver-like surface of Silvercote reflective insulation consists of a polished, heat reflective coating applied to a special kraft paper. The importance of using a Silvercote radiant heat reflective surface in modern building construction is obvious when it is realized that from 50 to 80 per cent of the heat transferred across a normal air space is in the form of radiation. REFLECTIVE SHEET INSULATIONS IN ROLLS SILVERCOTE DUPLEX--A thin flexible vapor barrier and insulation consisting of two sheets of Silvercote paper bonded together with asphalt. ThiB material, containing two exposed Silvercote sur faces, weighs approximately 50 lbs per thousand sq ft and is manufactured in 500 sq ft rolls in widths of 36 in. or 52 in. to span two 16 in. or 24 in. standard framing spaces. These widths permit bow-in of the Silvercote over the room side of the framing members to form an air space between the insulation and the interior finish. The water vapor per meability of Silvercote Duplex is 0.23 . grains per sq ft per hour per inch of mer cury vapor pressure difference. SILVERCOTE SIMPLEX--An econom ical vapor permeable reflective insula tion designed for use where a vapor barrier is not required. Silvercote Sim plex is a single sheet of special kraft paper coated on both sides with the Sil vercote surface. It weighs approximately 30 lbs per thousand sq ft and is manufac tured in 500 sq ft rolls in 36 in. or 52 in. widths to span two 16 in. or 24 in. stand ard framing spaces. These widths per mit bow-in of the Silvercote over the exterior side of the framing members to form an air space between the insulation and the exterior sheathing. The water vapor permeability of Silvercote Simplex is 99.2 grains per sq ft per hour per inch of mercury vapor pressure difference. Silvercote in rolls distributed by: Bird & Son, Inc., and The Flintkote Co. Reg. U. 8. Pat. Off. 1680 Silvercote Products, Inc. 161 East Erie Street, Chicago, HI. SILVERCOTE* REFLECTIVE INSULATION Insulation ON BLANKETS SILVERCOTE REFLECTIVE SURFACE ON VAPOR BARRIER SIDE A popular building insulation available in various thicknesses and faced on the vapor barrier side of the blanket with Silvercote paper. Manufacturers of this type of reflective blanket apply an as phalt coating to the back of the Silver cote paper for the twofold purpose of bonding the insulation material to the Silvercote paper and to lend vapor re sistant properties to the blanket at the room side of the insulation. SILVERCOTE REFLECTIVE SURFACES ON BOTH SIDES SILVERCOTE REFLECTIVE SURFACE ON BREATHER SIDE OF BLANKET INSULATIONS Silvercote paper is vapor permeable A deluxe insulation material utilizing the full insulation value of blanket insu lation, air spaces and two heat reflective surfaces. This double reflective blanket is manufactured with Silvercote Paper on the vapor barrier side and the breather side. and can therefore be used on the breather side of a blanket. When space permits the use of only one air space in conjunction with thick blanket insulations, it is de sirable that the air space be adjacent to the cold side (breather side). For this reason, many prominent manufacturers of mineral wool now furnish their re flective blanket with Silvercote on the breather side. Reg. U. S. Pat. Off. AVAILABLE UPON REQUEST Sllvercote's Handbook of "U" Values, 108 page Illustrated booklet listing 12,852 "U" values of various walls, floors and ceilings--Silvercote's Handbook of "U" Values is unique in that it provides sum mer as well as winter "U" values. The Handbook's special listing of ceiling "U" values, indicating characteristics of downward beat flow will be of interest to those who are concerned with Bummer comfort as well as winter fuel savings. 1681 Insulation ALFOL I NS ULAT I ON Reflectal Corporation A Subsidary of Borg-Warner Corp. 310 So. Michigan Ave., Chicago 4 ALFOL MULTIPLE LAYER REFLECTIVE INSULATION Introduced in 1929, ALFOL was one of the first reflective insulation blankets. Today, after nearly three decades of continuous development, ALFOL still is in the lead. Its patented blanket design insures high thermal efficiency, positive condensation protection and rapid, low cost application. Ideal for all types of residential, com mercial and industrial use. ALFOL is also favored in air conditioned structures, where the superiority of reflective insulations provides substantial cooling economies. What ALFOL Is: Insulation consists of multiple aluminum foil sheets that auto matically space themselves on applica tion to form two, three or four reflective air spaces. The number of these spaces varies with ALFOL Type, but all types have a liner sheet of rugged, vapor-proof paper that provides continuous moisture protection and positive application sup port. How ALFOL works: Radiant heat, as you know, normally accounts for 55 to 80 per cent of all heat loss through walls, roof or floor. Of all radiant heat, ALFOL foil sheets instantly, continuously re flect 95 per cent (or emit but 5 per cent). And the captive air spaces between these foil surfaces curb heat loss through con vection and conduction to check all forms of thermal loss. Practical advantages of ALFOL: Ther mal efficiency is the big factor, but there are other reasons for ALFOL popularity. Its heavy liner provides sag- and rip-re sisting application and a continuous vapor barrier. Its light weight (Ho lb/ sq ft) cuts rafter load. And ALFOL is as clean, odorless, durable as aluminum it self. Priced low . . . with compact design offering added savings in handling and application. ALFOL is quick and easy to apply: You simply cut to length and staple across the faces of studs, joists or rafters. An ALFOL Type for every purpose: Type 1--2 reflective air spaces. 12 in., 16 in., 24 in. widths. Type 1A--2 reflective air spaces, for furred-out masonry. 16 in. widths only. Type 2--3 reflective air spaces, our top seller! 12 in., 16 in., 20 in. widths. Type 3--3 reflective air spaces with foil base layer. 12 in., 16 in., 24 in. widths. Type 4--4 reflective air spaces for top efficiency. 16 in., 20 in., 24 in. widths. All ALFOL Types immediately available in handy 500 or S50 sq ft rolls. Write Dept. ASH for free data book. Other REFLECTAL insulation products ALFOL ASBESTOS: for central gas and oil heating equipment, water heaters, ranges, radiant heating seal and for all high temperature insulating requirements. ALFOL JACKETING: for refrigerator cars, trucks and other low temperature work. 1682 Insulation Iubb B.F. Goodrich SPONGE PRODUCTS DIVISION 274 Derby Place, Shelton, Conn. B. F. Goodrich SPONGEX Molded Cell-Tite TUBING for moisture-proof insulation Sponger Molded Cell-Tite tubing is made of tough, flexible rubber with uniform non-connecting cell structure. Especially efficient and convenient for pine insulation it will not absorb moisture nor support combustion. Insulation value is excellent. Easy application Wherever used, Spongex Molded CellTite may be easily secured with air-dry ing adhesive. Short lengths of tubing may be slipped on; longer ones may be slit lengthwise, snapped over pipe and adhesive applied to cut edges. These edges will not absorb moisture. Low water absorption Spongex Molded Cell-Tite meets ASTM specifications. Weight gain is under 10 per cent after 24 hours immersion in water; under 5 per cent after 3 minutes additional atmospheric pressure. Efficient insulation Thermal conductivity of Spongex Molded Cell-Tite is 0.28 at 75F with no deterioration in service. Low shrinkage and aging Spongex Molded Cell-Tite has no appre ciable change after 7 days at 200F. Resistance to weather-aging is good. Linear shrinkage, when aged 4 weeks at 158F is under 10 per cent, most shrinkage occurring in the first week. Wide range of density and firmness Standard grades of Spongex Molded Cell-Tite are ASTM 12 or 13 (from 5-13 psi to compress a one square inch disc to 75 per cent of its height). Can be made in practically any firmness. Density varies, depending upon size and firm ness, averaging 10 lb per cubic foot for soft, 15-20 lb per cu ft for medium, and 20-30 lb per cu ft for firm. Many sizes Spongex Molded Cell-Tite tubing is made with standard outside diameters of % in., 1 in., 1H in., 1H in., and can be made l^jj in., 1% in., and 2 in. Almost any inside diameter is available up to M in. of the outside diameter. Lengths up to 50 ft facilitate ease and simplicity of installation. Variety of colors Black is standard and can be furnished as non-staining to lacquer, enamel or plastic. (Tested for 24 hrs under ultra violet light or for 10 days at 158F). Any one color available for requirements of 7,500 ft or more. White, if specified, would be off-white. Please write for more information Insulation Screens Kaiser Aluminum & Chemical Sales, Inc. General Sales Office, Palmolive Building, Chicago 11, Illinois Executive Office, Kaiseb Building, Oakland 12, California KAISER ALUMINUM SHADE SCREENING* Patented Kaiser Aluminum Shade Screening is scientifically designed to keep interiors cool by blocking hot sun rays. Shade Screening is being widely used in con junction with air conditioning systems to reduce the solar load--thus permitting more economical operation by reducing the work load. . The effect of using Kaiser Aluminum Shade Screening is shown on these graphs prepared by Kaiser Aluminum engineers following a test procedure similar to that used at the ASHAE Laboratory (1, 2) during experimental work on the shading of sunlit glass. The accompanying charts illustrate the amount of instantaneous heat gain to a room both through unshaded windows and windows protected with Kaiser Shade Screening. Kaiser Aluminum Shade Screening has 17.5 louvers per inch permanently tilted at a downward angle. This stops sun rays before they hit the window glass. With sun angle (apparent) at 37 deg 100 per cent of sun rays are blocked. At 30 deg, 85 per cent. At 25 deg, 75 per cent. At 15 deg, 55 per cent. At 0 deg, 30 per cent. Thus Shade Screening can reduce the amount of instantaneous heat gain ' through unshaded windows by as much as 78 per cent, while still providing in sect protection. TYPICAL CALCULATIONS OF COOLING LOAD REDUCTIONS DURING PERIOD OF EXTREME MIDSUM MER SOLAR RADIATION AT 40" N. LATI TUDE. fihftilft Screening reduces the load on air-condition ing units . . . permits use of smaller units. These tvDic&l calculations show how this is possible: FIGURING 24 WINDOWS ON THE EAST SIDE 3*4'x 6' ,,,, Total area 3*4' x 6' x 24 504 Sq. Ft. Use 10:00 A.M. peak load Instantaneous Heat Gain through Unshaded Windows BTU/HR 504 Sq. Ft. x 138 BTU/HR per Sq. Ft........... 69,500 Instantaneous Heat Gain through Windows shaded by Kaiser Aluminum Shade Screen 604 Sq. Ft. x 35 BTU/HR per Sq. Ft........ 17,650 Quantity of Heat Gain Blocked by Shade Screen ..................................................... 51,850 Heat Blocked = 4,31 tons* of refrigeration FIGURING tl SOUTH WINDOWS 3*4' x 6' FIGURING 23 WEST WINDOWS 3*4' x 6' Total area 3*4'x 6'x 23 483 Sq. Ft. BTU/HR Use 4 K)0 P.M. peak load Instantaneous Heat Gain Unshaded Win* dows......................................... 111,000 Instantaneous Heat Gain through Windows shaded by Kaiser Aluminum Shade Screen............................................................ 34,800 Quantity of heat blocked by Kaiser Alumi- __ nnm Shade Screen...................................... 76.200 Heat Blocked 0 6.35 tons* of refrigeration Total Area = ZW x 6'x 11 = 231 Sq. Ft.___ Use 12:00 noon peak load BTU/HR Instantaneous Heat Gain Unshaded Win dows......................................................... 26,800 Instantaneous Heat Gain through Windows shaded by Kaiser Aluminum Shade Screen.............................................................. 8,550 Quantity of heat blocked by Kaiser Alumi- sum Shade Screen................................ ; 18,250 Heat Blocked = 1.52 tons* of refrigeration * 1 ton of refrigeration * 12,000 BTU/HR 1684 Kaiser Aluminum & Chemical Sales, Inc. Insulation Screens KAISER ALUMINUM SHADE SCREENING The instantaneous heat gain measure ments included transmitted direct solar radiation plus the absorbed heat gained by convection and re-radiation plus transmission of heat through the glass caused by inside-outside temperature differentials. Kaiser Aluminum Shade Screening reflects more heat than other commonly used materials thus the screening itself remains cool and emits at a very low rate. These factors of high reflectivity and low emissivity combine with the sun blocking feature of Shade Screening to produce cooler interior temperatures. -------------------- Total Solar Load -- -- --Instantaneous heat gain through unshaded windows. -------------------- -Instantaneous heat gain through windows protected by Kaiser Aluminum Shade Screening. ....................... % of heat blocked. 1. ASHVE Research Report, "The Shading of Sunlit Glass--An analysis of the effect of Uniformly Spaced Flat Opaque Slats," by G. V. Parmelee and W. W. Aubele, June 1952. 2. ASHVE Research Report, "The Shading of Sunlit Glass--An Experi mental Study of Slat-Type Sun Shades," by G. V. Parmelee, W. W. Aubele, and D. J. Veld, October 1952. 1685 Vibration Control Devices T. R. FINN & COMPANY INC Industrial Division 200 Central Avenue Hawthorne, New Jersey Specialists In Shock and Vibration Control FINNFIEX RUBBERIN-SHEAR VIBRATION MOUNTINGS Widely used for isolating vibration, shock and noise on air conditioning and similar machinery. Rated load from 40 to 4000 lbs. Complete, ready-to-use. Catalog RS-55. "FLOATING PILLOW" VIBRATION MOUNTING Heavy duty, high-deflection rubber-in shear mountings for efficient isolation of vibration, shock and noise of medium and heavy weight air conditioning equip ment. Load range from 500 to 2500 lbs. Catalog FP-55. FLOATING RAIL VIBRATION MOUNTINGS Rubber-in-Shear bases for use under pumps, compressors and fan-motor sets. A complete, ready-to-use mounting sup-, plied to specification. Catalog'F R-55. STEEL SPRING VIBRATION MOUNTINGS For superior vibration, shock and noise isolation of difficult-to-isolate low speed machinery, heavy air conditioning equipment, and for protection of deli cate instruments. Load range from 100 to 6500 lbs. Catalog SS-65. VIBRATION HANGERS Two types, Rubber-in-Shear (35-1600 lbs.) and Steel Spring (50-1000 lbs), pre vent transmission of noise from sus pended equipment and piping systems. Catalog VH-55. FLEXZORBER Seamless flexible bronze tubing covered with woven wire braiding and with standard copper tube female "slip fit tings" welded on both ends. Used to minimize noise and vibration in rigid piping conveying Freon in air condition ing and refrigeration units. Slip fittings sizes from % to 8 in. I.D. Catalog FZ-55. SOUNDZORBER Wire-reinforced, fabric-wrapped rubber pipe for reduction of water line noise and vibration. Sizes from M. to 12 in. I.D. with I.P.T. male fittings or with integral full-faced rubber flanges backed up with Series 15 or 30 steel flanges. Catalog SZ-65. ISOLANT The unusually high structural strength and resiliency of this special material provides excellent isolation of vibration, shock and noise. For use under massive air conditioning equipment and heavy machinery. Load range up to 6000 lbs per sq ft. Catalog IS-S5. EXPANDZORBER Stainless steel, welded diaphram type packless expansion joints used for con trol of vibration, expansion, and con traction in steam, chemical, oil and gas lines. Working pressure from vacuum to 1000 psi at -300 to +1800 F. Sizes from K to 72 in. with steel flanges or welded fittings. Catalog EZ-55. ENGINEERING COUNSEL Our engineering staff is always at your service to solve your individual problem. We shall be pleased to submit to you our analysis and recommendation for an efficient and economical solution to your vibration problems. 1686 Vibration Control Deuces The Korfund Company, Inc. 48-01R 32nd Place, Long Island City 1, New York or in "Thomas' Register." Specialists In Vibration & Noise Control for Over Half a Century. For a discussion of Vibration control theory and chart for determining deflections required, see "Controlling Vibration From Machine Mountings" at end of Chapter 41. If in doubt about product selection, submit data on make, type, rpm and model number`of equipment and type of floor for specific recommendations, without obli gation. STEEL SPRING VIBRO ISOLATORS provide greater deflec tions with isolation efficiencies approaching 100 per cent. Though more expensive than rubber or cork, they are sat isfaction guaranteed and provide maximum overall economy because: they eliminate bolting, speed equipment installation, usually eliminate special foundations, permit trouble-free upper floor installations, and will usually outlast the machine Series L Isolator THE SERIES L VIBRO ISOLATORS contain from one to . twelve steel springs of proper stiffness depending upon the loading and deflection desired. Loading: 75 to 23,000 lbs. Maximum deflection \y in. (special designs available for higher loads or larger deflections). Isolators are usually installed directly under machines (occasionally under steel bases or foundations supporting equipment). They have ad justable snubbers to control movement and built-in leveling bolts, a Korfund feature for over 30 years. SERIES V VIBRO HANGERS: load range 20 lb to 3,800 lb. Vxbro-HangeT Maximum normal deflection 1 in. (larger deflections on re quest). For suspended equipment installations, also as vibra tion-absorbing pipe hanger. RUBBER AND CORK provide good sound insulation. How ever, rubber is not very effective as a vibration absorber for disturbances below 1200 cpm, is fair from 1200-1800, and good above 1800. Cork is effective only above 1800 cpm. Slosto-Rib Pad SERIES R RUBBER-IN-SHEAR HANGERS: Similar to spring hanger illustrated but incorporating rubber mountings of varying stiffnesses for loads from 10-1,000 lb. ELASTO-RIB has a core of high-grade cork plate, permanently bonded between two layers of deep-grooved, Neoprene rubber. Just set the machine on Elasto-Rib--no fastening to floor is normally required but can be cemented or bolted if desired. Excellent sound insulation characteristics. Loading up to 60 lb per square inch. Also furnished as Elasto-Rib Dampers with load distributing top plate and built-in leveling bolt. Vibracork v,,,,, MMnr ,, ... BuM-in s&VfaxU ARMSTRONG'S VIBRACORK & KORFUND LIGHT DEN SITY MACHINERY CORK are strong, durable machinery isolation plates made of pure cork granules compressed and baked under pressure with accurately controlled density. Furnished in three densities for loads from 400-8,500 lb per square foot. 1 in., 2 in., 3 in., thicknesses. Plates 12 in. x 36 in. "r J3T...... (. DupUx Box,. DUPLEX TWIN RAIL FAN & MOTOR BASES: Rugged construction and built-in chocks to maintain alignment. Rubber or cork isolation. Advantages of separate fan and motor bases: no motor noise transmitted through ducts--complete adjustability permits job-site changes in motor position, belt length, rotation, equipment bolt location--quicker delivery of drawings and bases--easier handling--lower transportation costs. Integra! type bases also available. FOR ADDITIONAL DATA, SEE SWEET'S FILES OR WRITE FOR CATALOG 1687 Vibration Control Devices ' Vibration Mountings Inc. ' 98-01 50th Ave. Corona 68, N. Y. Engineers and Manufacturers of Vibration Control Devices Representatives in Principal Cities. See "Thomas Register**. Fig. 1. Type RB. Rubbcr^in-Shear Bate. Structural Steel Vibration Bases for Fans and Motors, Pumps, Compressors and Air Handling Units prevent motor misalignment, excessive belt wear and reinforce cast iron pump bases. Bolt hole locations are predetermined and fixed so that the vibration base becomes a template for lining, up the equipment and securing it in place. Rubber-in-Shear is generally used where a static deflection of % in. maxi mum is adequate. Mountings are per manently fastened between structural channels and flat steel base plates, as shown in Figures 1 and 2. Spring Mountings with bonded acous tical pads are recommended for the more critical locations. Static deflections up to in. provide isolation efficiencies ap Fig. t. Type RB. Base End Section. Fig. S Type VMRH Robber Hanger proaching 100 per cent. Structural angles form a rigid floating platform for the equipment as shown in Fig. 4. The mounting used is shown in Figure 5. Individual Mountings are used under equipment that does not require a sup plementary base. Rubber - in - Shear mountings typically illustrated in Fig. 7 can be furnished for individual loads of 5 to 2,000 lbs. Spring mountings as illustrated in Figures 5 and 8 support loads ranging from 50 to 18,000 lbs. Spring mountings are manufactured with built in leveling and damping Fig. 5 Spring-Flex Mount Fig. 6. Type RSH. Rubber-in-Shear and Spring Hanger. devices. Vibration Hangers using either rub ber-in-shear or steel springs or a com bination of both prevent the transmis sion of vibration and noise through the suspension rods. Open housings, not shown, or closed housings as shown in Figures 3 and 6 are made for attachment directly to the ceiling or insertion in the suspension rods. Standard hangers are made for loadings of 50 to 1,000 lbs. Spe cial units on request. Pad Type Materials are available in molded cross-rib neoprene as shown in Fig. 9, cork plates of thicknesses ranging from % in. to 4 in. as shown in Fig. 10, or in a bonded cork and neoprene pad, as illustrated in Fig. 11. Send for complete Flexible Hose and Vibration Control Data Book which in cludes tables of recommended isolation efficiencies for critical and non-critical area applications. Type R mount. Fig. 7. Spring-FIez Mount Fig.S Shear-Flex Pad Fig. 9 1688 Cork-Flex Pad Fig. 10 Cork-Rib Pad Frg.lt The Industrial Press 93 Worth Street, New York 13, N. Y. Publications Air Conditioning, Heating and Ventilating Engineering magazine for the men who design systems and specify equipment This monthly engineering magazine (established 1904) is read by the engi neers--by whomever employed--who design, specify, install, and maintain sys tems for heating, ventilating, air condi tioning, piping, plumbing, industrial refrigeration, process steam, and related services. These systems are installed in industrial plants, hospitals, office buildings, hotels, stores, schools, col leges, theaters., churches, institutions, government buildings, military installa tions, housing projects, etc. Readers include: Consulting engineers; engineers with architects, with large engineeringtype contractors, with utilities; engi neers with industrial plants and with large buildings; and others. To these men AIR CONDITIONING, HEATING AND VENTILATING brings, month after month, a steady stream of crisplywritten articles on the best current practice, boiled-down research results, mathematical short-cuts, bandy tables, charts and Data Sheets. Subscription rates in U. S. and Canada; One year, SS; two years, S5; three years, S6. In all other countries, $7 per year. Heating & Plumbing Equipment News The "new equipment" magazine serving Contractors and Wholesalers This monthly "new equipment" maga zine, published in tabloid format, reaches by controlled circulation 35,000 contractors, wholesalers and other groups concerned with the sale and in stallation of heating and plumbing equipment. Only publication that reaches all these categories: Radiator and warm-air heating contractors, oilburner dealers, gas-burner dealers, plumbing contractors, and the whole salers and distributors who supply all the foregoing. Editorial content con sists of concise, illustrated articles de scribing new and improved equipment, materials, and tools placed on the market, also new catalogs and bulletins issued by manufacturers. Inquiries total over 100,000 per year for informa tion about specific products such as: Boilers, furnaces, gas-burners, oilburners, toilets, sinks, pipe, fittings, valves, pumps, pipe-cutting and thread ing tools, hot water heaters, room coolers, water softeners, dishwashers controls, insulation, and many others! Sample copy and advertising facts upon request. Industrial Press Books Industrial Heat Transfer Design of Heating and Ventilating Systems Pipefitters Handbook Radiant Heating Snow Melting Design of Industrial Exhaust Systems Methods of Joining Pipe Fluid Flow in Pipes Exhaust Hoods Fuel Oil Manual Flow and Fan Plant and Process Ventilation 1689 F. W. Hutchinson F. W. Hutchinson Forrest R. Lindsey T. Napier Adlam T. Napier Adlam John L. Alden J. E. York Clifford McClain J. M. DallaValle Paul F. Schmidt C. Harold Berry W. C. L. Hemeon $6.00 --- O. 7.00 6.00 6.00 4.50 3.50 3.00 3.00 3.50 3.50 4.00 9.00 Publications American Society of Refrigerating Engineers 234 Fifth Avenue, New York 1, N. Y. lished internationally on refrigeration and allied subjects. Five issues and an index annually at $7.00. APPLICATION DATA SECTIONS The APPLICATION DATA Sections tell precisely how refrigeration is used in various fields, giving examples and specific information on the best practice known to date. A complete list of the subjects covered is available on request. Some 17 bulletins are available sepa rately at reasonable prices for single copies or quantity orders and can also be had bound with a paper cover, the complete set for $3.50. CODES AND STANDARDS LONG acknowledged the most au thoritative periodical in the field, Refrigerating Engineering has added steadily to the practical value of its con tents, and its number of readers has grown in proportion. This magazine is a must for men who keep in touch with all that is new and important in refrigera tion and air conditioning. The annual subscription price is $4. ASRE further contributes to refrigera tion progress by establishing codes and standards in the industry. These stand ards cover approved methods for-testing and rating various types of air condition ing and refrigerating equipment. Also included is the B-9 Safety Code for Mechanical Refrigeration. Sold sepa rately, or a complete set for $5.00. ASRE DATA BOOKS Published bi-annually since 1932, they now consist of two volumes, one issued each year. The Design Volume is a stand ard reference work containing funda mental data, refrigerant tables, descrip tion of the different cycles, systems, and component parts--a gold mine of in formation--$10.00 a copy. The Applications Volume is crammed full of how-it-is-done information on the use of refrigeration in many different applications. .A must for the design or application engineer--$7.50 a copy. REFRIGERATION ABSTRACTS A Journal devoted to brief condensa tions, by specialists, of all articles of refrigerating interest appearing in hun dreds of periodicals and reports pub REFRIGERANT TABLES, CHARTS, AND CHARACTERISTICS A handy 6% in. x 9 in. volume containing the thermodynamic properties of all re frigerants now in use (reprinted from ASRE Data Book), forms a convenient reference for design and application engineers, contractors, professors 'and students. Cloth bound, $2.00, paper bound, $1.50. MEMBERSHIP ACTIVITIES IT is the policy of the ASRE to treat in its meetings current subjects touching upon all phases of the art of refrigeration. Membership is in several grades with dues from $10 to $20. Sec tions hold meetings in 40 principal cities. More detailed information will be sent on request. To keep apace with progress in refrigeration and air cations and follow the activities of THE AMERICAN SOCIETY OP REFRIGE ATING ENGINEERS, 23* Fifth Avenue, New York 1, N. Y. 1690 Publications Coal-Heat Published at 20 W. Jackson Blvd., Chicago 4, Illinois Phone Wabash 2-9464 New York City, MUrray Hill 6-3772 To Get the Facts . about heating and fuel requirements, heating costs, operating and maintenance problems, the equipment situation, personnel, performance standards, fuel eco nomics, sales and service--this is what we are trying to do, here at COAL-HEAT. These are the fundamental factors that affect the market, the use and sale of fuel and equipment, one's job, or business. So, it is our aim to get and print "the low-down" on these in each of the following markets: 1. Apartment houses 2. Churches 3. Dept. & other stores 4. Dairies 5. Greenhouses . 6. Hotels 7. Hospitals 8. Institutions 9. Laundries 10. Municipal & govt, bldgs. 11. Mfg. plants 12. Office bldgs. 13. Residential 14. Schools 15. Theaters & other bldgs. To find out what each of us concerned should know about the particular needs, problems and possibilities in each of these fields, and to help make more of the facts known where they will do the most good--this is our purpose! Together, these groups represent some 20-million plants, buildings, homes, 160million tons of coal annually--the nation's largest fuel market, in either number of tons or customers. See "Heating-Fuel Markets"--$1.00 a copy. Many of these plants and buildings are old, the equipment is in poor condition, operation leaves much to be desired, costs are excessive. Since most janitors, building owners, members of school and hospital boards are not well informed about heating or the proper use of fuel, we face a tremendous ed ucational job a job that rests largely on the retail dealer and the salesmen because they alone come in periodic contact with these 20-million fuel users. To help pro vide the essential educational sales and service tools--that's what we're trying to do. To help keep more customers happy, get into more of the new buildings, help de velop new business--these are the objectives of COAL-HEAT. It can help you get more business! fuel and heating equipment--sales and service 1691 Publications Domestic Engineering Publications 1801 Prairie Avenue, Chicago.16, Illinois DOMESTIC ENGINEERING MAGAZINE Editorially, DOMESTIC ENGINEER ING Magazine is keyed to the total busi ness interests of the qualified contractordealers who specify, sell, install and service all types of heating, air condi tioning, plumbing and related products and appliances. It covers every phase of the contractor-dealers' functions on domestic, commercial, industrial and institutional projects. Now in its 66th year of service, DO MESTIC ENGINEERING Magazine has consistently maintained its position of leadership in this field. In recognition of its continuing "Leadership, in Ac tion" campaigns, it has won 15 major awards for outstanding editorial achieve ment in annual competitions with hundreds of business magazines. Year after year, through its meritori ous editorial programming, DOMESTIC ENGINEERING has earned, and con tinues to hold, the loyalty and confidence of its large audience of subscribers--a loyalty and confidence that pays divi dends to the DOMESTIC ENGINEER ING advertiser. Member Audit Bureau of Circulations Published Monthly Subscription rate: $5.00 per year DOMESTIC ENGINEERING . CATALOG DIRECTORY Here is the industry's most comprehen sive, single source of specifying and pur chasing information on heating, air con ditioning, plumbing and allied products. Its directory lists all known products used in this field and its various sections supply the catalogs, names and addresses and trade names of the leading manu facturers of these products. Published annually. Price $12.50 Together DOMESTIC ENGINEERING and DOMESTIC ENGINEERING CATA LOG DIRECTORY constitute the backbone of every well-conceived promotional program in the heating, air conditioning and plumbing industry. Together they afford the manufacturer effective two-way coverage of the important buying factors that make up this field. ^ 1692 , Publications Heating & Air Conditioning Contractor Scott-Choate Publications 92 Martling Avenue Tarrytown, New York Subscription rates--$4.00 per year. V. S., Canaaa and Pan Jimer. Foreign *5.00. Advertising rates on request. Subscription rales--94.00 per year, U. S., Canada and Pan Amer. Foreign 95.00. Ad vertising rates on request. Heating & Air Conditioning Contractor, formerly Sheet Metal Worker, is the oldest magazine in the warm-air heating, air conditioning, ventilation and sheet metal contracting industry. The magazine is edited primarily for the contractor, but is also read by the wholesaler and manufacturers who supply the necessary equipment and materials. Heating & Air Conditioning Contractor is a co-sponsor of the now-famous All Industry Air Conditioning Conferences, the most widely recognized forum of its kind in this field. "The 1956 Air Conditioning Industry" by Heating & Air Conditioning Contractor's editor-in-chief, is a detailed study of the residential and packaged commercial market. It has been distributed to several hundred manufacturers in the field. (Copies available on request). Heating & Air Conditioning Contractor appears in the new, easy-to-read, KingSize format. Through a combination of paid and controlled circulation, based on Dun & Bradstreet ratings, Heating & Air Conditioning Contractor provides maxi mum market coverage available in the industry. The Journal of Plumbing, Heating & Air Conditioning Scott-Choate Publications 92 Martling Avenue Tarrytown, New York The JOURNAL of Plumbing, Heating & Air Conditioning, formerly Plumbing and Heating Journal, is in its 75th year. It is edited primarily for contractors who sell, install, service and guarantee plumbing, heating and air conditioning equipment, and for the wholesalers and manufacturers who supply this equipment and other necessary tools and materials. The JOURNAL is a co-sponsor of the AU-Industry Air Conditioning Conferences, the most widely recognized forum of its kind in this field. More editorial material has been reprinted from The JOURNAL'S pages than from any other magazine in the industry. Some of the subjects covered include: Air Conditioning.Temperature Controls.Oil Heating-Baseboard Heating* Domestic Hot Water-Water Conditioning. The JOURNAL provides dissemination of technical, business and other industry news to the plumbing, heating and air conditioning contractors. All selected con tractor and wholesaler readers are Dun & Bradstreet rated. The JOURNAL appears in the modern, easy-to-read. King-size format. 1693 Publications KEENEY PUBLISHING COMPANY 6 North Michigan Avenue, Chicago 2, 111. Heating, Piping & Air Conditioning carries the Journal of the ASHAE as well as its own regular editorial section. Its field is that of industry and large buildings. It is devoted to the design, installation, operation, and mainte AMERICAN ARTISAN covers the field of warm air heating, residential air conditioning, and sheet metal contract ing. Its readers are warm air heating and sheet metal contractors, dealers, jobbers, manufacturers, and public util- nance of heating, piping and air condi tioning systems in plants, commercial, institutional and public buildings. Each January issue includes a com plete directory of commercial and indus trial heating, piping, and air condition ing equipment, which lists all products, their trade names, and the manufac turers' addresses. It is the established buying and specifying guide of the in dustry. . H. P. & A. C. is read by consulting en gineers and architects . . . contractors . . . and engineers in charge of heating, piping and air conditioning in industrial plants, and other large buildings, fed eral, state, and city governments, school boards, and public utilities. Most of ASHAE members are subscribers. Such coverage means, for the adver tiser, consideration at all points in the selling of a heating, piping, or air condi tioning product . . . consideration in its selection during the preparation of plans and specifications; in its actual purchase for installation; in its year-' round buy ing for operating and maintenance re quirements. Without waste, the manu facturer of air conditioning products and equipment cap reach through H. P. & A. C. those from whom he is seeking the necessary engineering acceptance. lty companies. Special features of each issue have been devoted to air conditioning since 1932, when it first became apparent that air conditioning for homes was to be along the lines of the central forced warm air heating system. As a result of the ready adaptability of this type of heating system to all air conditioning factors, hundreds of thousands of homes today have winter air conditioning-- supplied through forced warm air heat ing with air cleaning and humidification. Cooling apparatus can be attached to these systems readily whenever year- 'round air conditioning is desired. Each January issue includes a com plete directory of residential air condi tioning, warm air heating, and sheet metal products and equipment, which lists all products, their trade names, and the manufacturers' addresses. The key man in the residential air con ditioning picture is the warm air heating and sheet metal contractor-^ the one man experienced in "treating air" at a cen tral place and getting it properly dis tributed. And American Artisan is the key publication--because it reaches these key men with information that has made it the recognized authority on residential air conditioning practice. Member--A.B.P.--A.B.C. Member---A.B.P.--A.B.C. Subscription Prices-- U. S. fS per year. Subscription Prices--U.S. SS per year. Canada, Spain, Central and So.. A merit i--$4.00 per year. Elsewhere 16 per year. Publications Snips Magazine 5707 W. Lake St. Chicago 44, 111. This Friendly, Close to the Reader Periodical Provides The Real Push Behind Sales To those Contractors who handle Warm Air Heating, Sheet Metal Work, Ventila tion and Air Conditioning. PREFERRED as an effective advertis ing medium by many notable industrial advertisers year after year, and many . Prominent Jobbers who know their market well. During the past year over 400 firms used space with us. These valued patrons see in our 14,574 readers, a carefully selected and substantial buying group, worthy of "talking to" month after month. SNIPS is packed each month, from cover to cover, with hundreds of live news stories and exclusive pictures in cluding practical applications of latest advancements of the Sheet Metal, Heat ing, Air Conditioning and Ventilation trade. No long contributed stories. It's all field gathered material, secured the hard way, rubbing shoulders with the readers. Such work gets for the periodi cal a reader interest seldom found in a trade publication. You'll find this feature the basis of the sensational inquiry pulling power and sales producing value of advertising space in SNIPS. Rates for space have always been con servative. The carefully figured current rate with cream coverage available at an extremely low rate per thousand distribution is truly an exceptional value at this time. SNIPS is now Standard size--8J4 in. x 11 in. Special Issues January Annual & Winter Market &Number--March Anniversary Spring Market Issue--September Fall Market Issue--December Holiday Greeting Issue--Further information gladly sent on request. ABOUT SNIPS' MAILING LIST It's truly a select group that gets SNIPS. They are the outstanding firms and individuals in the trade whom the better supply houses are selling or trying to sell. They are the contracting and in stalling concerns whom the principal jobbers and distributors of the industry --people who really know their territor ies best--consider worthy of cultivation by mail, promotion and salesmen's calls. These advertising people always alert to serve you: H. F. Hoy, Nick Carter, and Ed Carter in the Home Office. In the East R. F. Duysters, 70 East 45th St., New York 17, New York, MUrray Hill 6-3772. In the West, Maurice A. Kimball Co., 2550 Beverly Blvd., Los Angeles 4, California, DUnkirk 8-6178, and Rm. 767, 681 Market St., San Francisco 5, Calif., EXbrook 2-3365. 1695 AMERICAN SOCIETY OF HEATING AND AIR-CONDITIONING ENGINEERS Headquarters: 62 Worth Street, Hew York 13, N. Y. (Tel. WHitehall 3-0377) OFFICERS and COUNCIL President..................... First Vice President. . Second Vice President Treasurer..................... Executive Secretary... -- John W. James ........... P. B. Gordon ..............E. R. Queer ... .R. A. Sherman' A. V. Hutchinson Three years: A. B. Algben, John Everetts, Jb., J. N. Livermore, J. H. Ross. Two years: B. W. Farnes, C. B. Gamble, W. A. Grant, D. M. Mills. One year: John H. Fox, John E. Haines, A. J. Hess, C. H. Pestebfield, B. H. Spurlock, Jr. hr--- Technical Secretary.............................................................................................................................Carl H. Flink Editor..........................................................................................;......................................................C. H. B. Hotchkiss Public Relations................................................................................................................................... W. M. Vidulich ASHAE Research Laboratory, 7218 Euclid Ave., Cleveland 3, Ohio Director of Research.............................................................................................................................. E. R. Kaiser Assistant Director of Research...........................................................................................C. M. Humphreys ADVISORY BOARD John E. Haines, Chairman; Lester T. Avery, M. F. Blankin, S. E. Dibble, S. H. Downs, E. 0. Eastwood, W. L. Fleisher, H. P. Gant, H. M. Hart, C. V. Haynes, L. N. Hunter, D. D. Kimball, S. R. Lewis, A. J. Opener, E. E.F. B. Rowley, L. Seeley, A. Stacey, Jr., Ernest Szekely, Reg. F. Taylor, G. L. Tuve, A. C. Willard, C.-E. A. Winslow and B. M. Woods. COUNCIL COMMITTEES \eculive: P. B. Gordon, Chairman; E. R. Queer, R. A. Sherman. 'inance: A. J. Hess, Chairman; W. A. Grant, J. N. Livermore, R. A. Sherman (Ex Officio). Membership: B. W. Farnes, Chairman; D. M. Mills, J. H. Ross. Program and Papers: W. A. Grant, Chairman; C. H. Pestebfield, John Everetts, Jr. (A. J. Hess, Chairman, Advisory Subcommittee). COMMITTEE ON RESEARCH B. H. Jennings, Chairman H. A. Lockhart, Vice Chairman Three years: F. H. Faust, F. K. Hick, M.D., R. C. Jordan, H. A. Lockhart, Arthur Nutting. Two years: R. C. Chewning, W. S. Harris, N. B. Hutcheon, B. H. Jennings, . R. A. Miller. One year: John Everetts, Jr., W. F. Friend, Carl F. Kayan, H. R. Limbacheb, E. F. Snyder, Jr. 1696 .PERATURE-FAHRENHEIT RATIO (W)-POUNDS WATER PER POUND DRY AIR ! CU FT OF AIR PER MINUTE F R IC T IO N L O S S IN IN C H E S O F W A T E R P E R IO O F T CU FT OF AIR PER MINUTE -- N> -- ' 04 r> O' <T> -4 <0 o ro o 04 * U! <J> 00 U) o o o o o o o oo o o o o o o o o o oo o o. o o o o o oo o o o o o o o oo o o o o o o o oo o o o o o o o o oo o o o o o o o oob o ro o 04 o b o o oo ro bi b 05 ro 04 05 03 O