Document 7QLoj9adZb317kop3Yzr3y08

Heating Ventilating Air Conditioning GUIDE 1944 An Instrument of Service prepared for the Profession--Containing a Technical Data Sectiort OF REFERENCE MATERIAL ON THE DESIGN AND SPECIFICATION OF HEATING, VENTILATING AND AIR CONDITIONING SYSTEMS' BASED ON---- THE TRANS ACTIONS--the Investigations of the Research Laboratory and Co operating Institutions--and the Practice of the Members and Friends of the Society together with a Manufacturers* Catalog Data Section Containing Essential and Reliable Information concerning Modern Equipment ' also The Roll of Membership of the Society** WITH Complete Indexes ** to Technical and Catalog Data Sections *r Vol. 22 $5.00 per Copy . Published Annually by American Society of Heating and Ventilating Engineers 51 Madison Avenue New York, N. Y. A CHAPTER 40 industrial ddxliaudt Systems Classification of Systems, Hood Design Principles, Require ments for Suction and Velocity, Duct System Design, Col lectors, Resistance of System, Efficiency of Exhaust Systems, Types of Fans, Protection Against Corrosion IN many industries some type of exhaust system designed to collect and remove dusts and fumes is essential to the efficiency, economy, and safety of operation. General design information is included in this chapter which is intended to relate primarily to industrial exhaust systems. CLASSIFICATION OF SYSTEMS In general there are two basic layouts of exhaust systems, the central and the multiple unit system. In the central system a fan is located near the center of operations with a piping system radiating to the various machines to be served. In the multiple unit system, which is sometimes employed where the machines to be served are widely scattered, or where the operations are apt to be independent or intermittent, small individual exhaust fans are located at the center of the machine groups or at each machine. The unit arrangement has the advantage of flexibility. Exhaust systems'are also classified by the means employed to collect the material. The dust or refuse may be collected and- controlled by enclosing hoods or open hoods with positive inward air movement or by exhausting the general air of the room. With some classes of machinery it is not feasible to hood the machines closely and in these cases open hoods over or adjacent to the machines are provided to collect as much as possible of the dust and fumes. This class includes such machines as rubber mills, package filling machinery, sand blast, crushers, forges, pickling tanks, melting furnaces, and the unloading points of various types of conveyors. The open hoods should be placed as close to the source of dust or fumes as possible, with due regard to the movements of the operator and should be placed so that the operator is in no case in the path of the exhausted material. When the hood must be placed at some distance above the machine it should be large enough to cover a large area as diffusion is usually quite rapid. Some consideration should be given to the natural movement of the fumes. For those that are lighter than air, the hood may be over or above 717 HEATING VENTILATING AIR CONDITIONING GUIDE 1944 For additional information on dust and cinders, see Chapter 29 Air Cleaning Devices. ' RESISTANCE OF SYSTEM The maintained resistance of the exhaust system is composed of thre factors: (1) loss through the hoods, (2) collector drop, and (3) friction drop in the duct system. The loss through the hoods is usually assumed to be equal to the suction maintained at the hoods. Where possible the resistance of the particular collector to be used should be ascertained from the manufacturer. Friction drop in the pipes must be computed for each section where there is a change in area or in velocity. Find the velocities in each section of pipe starting with the branch most remote from the fan. The friction drop for these sections can be determined by reference to Table 6 and Fig. 2, Chapter 32. Total friction loss in the piping system is the friction drop in the most remote branch plus the drop in the various sections of the main, plus the drop in the discharge pipe. Table 7. Accepted Standards for Toxic Concentration of Fumes, Dusts and Mists4 ' Fumes Cadmium oxide ... , ....... .................................. ................... .............. Chlorodiphenyl______________________________________ _______________ Tead or oxides of load .......... ................... ........................................... .. Mercury or mercury compounds Penfachlnronaphthalene............................... ........................................., Trichloronaphfhalene........ ......... ........................................................ 7inc r>xide . Dusts Ashestns . .... Cpment ..... ....... ..... ....... ....... .................................... Gypsum . ................ ........... . T.ead or compounds of lead ..... . ............... .......... ....... ......... ........... Manganese ..................... ...................................................... ......................... Mflrhle . ............................................. .......................... Silica (more than 70 per cent free silicon-dioxide) Silica (more than 10 per cent free silicon-dioxide) Silica (less than 10 per cent free silicon-dioxide) Mists Chromic acid ........................... ............ ............................ Sulphuric acid...................................................................................................... Milligrams per Cubic Meter 0.1 1.0 0.15 01 0.5 5.0 15.0 Million Particles per Cubic Foot!) 5 100 100 0.15c 6C 100 5 10 100 Milligrams per Cubic Meter . 0.1 5.0 ^Adapted from Safe Concentrations of Certain Common Toxic Substances Used in Industry, by tl. Bowditch, C. K. Drinker, P. Drinker, H. A. Haggard, and H. Hamilton <Journal of Industrial 3ypins in Toxicology, Vol, 22, No. 6, June, 1940). Industrial Code Bulletin No. 35 (New York State Labor Depart ment). Study of Aabestosis in Asbestos Textile Industry (U. S. Public Health Bulletin No. 241, luJSU Chronic Manganese Poisoning in an Ore Crushing Mill (/. S. Public Health Bulletin No. 247, 1940).. bDetermined by light field or equivalent technique. ^Milligrams per cubic meter. 730 Vfvv '&L ---- ALFOL Alfol Insulation Company Incorporated .155 East 44th St., New York, N. Y. Agents in Principal Cities HEAT INSULATION for ALL PURPOSES ALFOL PRE-FABRICATED INSULATION PANELS FOR TANKS, TOWERS, AND ALL TYPES OF HEATED EQUIPMENT 4m> m Metal Jacketed Panels con taining insulation best suited for each particular condition. Removable and Replaceable by means of Lock-Joint con struction. Shop Fabricated with Cut outs for manholes and pipe connections. Pr'Uihncaled Panel. ,W Right-- A J plied to Tenner Easily and Rapidly Applied. by any type of labor. - Trim Appearance with mini mum of up-keep. FOR MORE DETAILED INFORMATION WRITE FOR ALFOL PANEL DATA BOOK ALFOL HOUSE INSULATION BLANKET Pure Aluminum Foil spaced on three-ply thick paper vapor barrier sheet. Single and Double Layers insure spaced sheet to; reduce conduction and convection. Ap plied between structural members or furring, Alfol Blankets give high insula-- tion value at low cost. Specifications Description ; Widths Net Area uNet Wesfiper Roll | perRml,-' Type I.-- ! Layer ALFOL i !6"-2U Type II.-2Layer ALFOL , 250 sq. ft, 1711b. 250 jq. ft. : - See technical data on Table 1, Section C, Pages 91-94, this volume. ALFOL RADIATOR REFLECTORS ALFOL REFLECTORS behind radiators reduce heat loss through wailsr save fuel. Temperature gradient to outside reduced 50 per cent. THIRTEEN YEARS' SERVICE PROVES LASTING VALUE OF ALFOL 1140 lion Insulation a Reynolds Metals Company d St. I;k New York Reynolds Metals Building Richmond, Virginia Chicago Louisville San Francisco 1 Pro- etc. OL, ; in itial me- . 13 dve . iS ing liar CELLULAR FIBRE INSULATION WATER-REPELLENT AND FLAME PROOF Reyn-O-Cell will not absorb water or moisture. It has successfully withstood flame tests up to 1500 F. REYN-O-CELL is one of the most effec tive sound absorption materials. Flexible (Blanket-Type) Insulation for Houses, Commercial Buildings, Industrial Structures and Special Insulation Purposes Reyn-O-Cell stops up to 73 per cent heat flow and permits complete air circu lation around framing. Thermal con ductivity is .24 Btu per hour, per square foot, per 1 F, per inch thinkness. (Au thority--Prof. J. C. Peebles, Armour Insti tute of Technology). Reyn-O-Cell is one of the most efficient barriers to the passage of heat that is commercially available today. It consists of heat retarding dead air cells. There are myriads of minute and hollow cellulose fibres, entwined and interlocked into a flexible, clean, resilient and light-weight mass. APPROVED AND ACCEPTED Reyn-O-Cell is manufactured under constant United States Government in spection and in strict accordance with Department of Agriculture specifications. It is approved for home and industrial insulating purposes by Federal, State and Municipal bureaus, builders, architects, | and heating engineers throughout the United States. Reyn-O-Cell is ideally suited for equip ment insulation. It can be furnished cut to size and in special widths up to 60 inches. COSTS LITTLE TO INSTALL Furnished in convenient blankets, or rolls, Reyn-O-Cell is adaptable to all constructions without expensive cutting or waste. REYN-O-CELL does not settle, sag or pack. For existing homes, as well | as for wails, ceilings or roofs of new struc| tures it provides maximum insulating ; efficiency. Labor costs for installation are ! exceptionally low. AIR CIRCULATES FREELY i Reyn-O-Cell permits free circulation of air on both sides of the insulation, thus allowing rapid evaporation of any moisture which may occur. Possible damp-rot, decay or other damage to structural materials is thereby minimized. RODENT AND VERMIN PROOF Reyn-O-Cell blanket type insulation insures utmost cleanliness, not only during installation, but during the lifetime of the structure. It is not subject to attack by rodents, and does not harbor vermin or other insects. It is odorless, and will not decay. REYN-O-CELL Is Easily Installed Send for literature describing Reyn-OCell; and its many advantages in existing houses as well as new construction. 1155 g gjjgj j