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550 CHAPTER 29 1965 Guide And Data Book For balancing, air systems may be equipped with dampers in supply, return, and outdoor air ducts, splitter dampers, or dampers in outlets. In selecting the desired type of damper or balancing method, the following points should be kept in mind: *' 1. Unfavorable effect on air stream and noise level should be avoided. This will often rule out blank-offs or dampers in out lets, unless such dampers are of special design. 2. It should be posable to alter outlet volume without'alteN ing the direction of discharged air, and to measure the amount of air handled without difficulty. Blanking off part of the area of supply outlets 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 Chapter 30 for discussion of various air distribution control devices.) 1 "' Instruments for balancing include instruments for meas uring air quantities, static pressure, temperature and hu midity. Commonly used instruments are the rotating vane anemometer, deflecting vane anemometer; thermal ane mometer, 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 manu facturer for the tube used. (See Air Flow Measurement in Chapter 16.) 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 anemometer inside the fan inlet plenum. For ex haust fans the discharge outlet will often serve. 3. Measure fan motor input. ' ;, 4. Begin balancing the supply system at the last outlet on the branch farthest from the fan (branch number 1). This is outlet Dumber 1, number 2 is the next to last outlet. - 5. Measure the air flow at outlet number l'(Q) and compare with the design air flow fqr that outlet (Qj), record the ratio, (.QJQ*).* 6. Measure the air flow at outlet number 2 and determine the ratio {QJQi)t. Compare (Qm/QJ)* and (Q/QA. 7. If these ratios are not within 10 percent of each other, adjust outlet number 2 to bring ratios into closer agreement. . Do ant adjust outlet number 1. 8. Measure and again determine (Q^/Qj)i and (Qm/Qe)i and compare. If these are within 10 percent of each other, no further adjustment is necessary. Proceed to outlet number*3. 9. Determine (QJQd)t and compare with (Qm/Q*)\- If necee-. saiy, adjust number 3 so that (Qm/QJ)s and (QwjQJ)do not vary by more than 10 percent. Do not adjust outlets I art. (Adjustment of outlet 3 automatically changes the Qm/Qi ratios of ontlets 2 and 1. The ratios for all these outlets approach the same values. For this reason, once the outlet has been adjusted, it does not re quire further adjustment.) 10. Proceed to outlet number 4 and adjust to obtain agreement between (QAQA and (Q_/&)>- 11. After all outlets on branch number 1 are proportionately balanced to each other, proceed to branch number 2, etc. 12. Upon completion of proportionate balancing of all outlete the branches should be proportionately balanced. 13. Select typical outlets in branches 1 and 2.... Adjust number 2 branch damper to obtain agreement of the Qm/Qi ratios for the two branches. Proceed in like manner to obtain agreement between branches 2 and 3,3 and 4, etc.. 14. Upon completion of proportionate balancing, recheck the fan capacity. Adjust the fan speed to obtain a Qm/Qi ratio of 1.0 at the fan. Since the system has been proportionately adjusted, the Qm/Qi ratio throughout the system wiu bo approximately 1.0 and the flow from each outlet will be the design air flow rate. (The 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 installation. 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 de termining how carefully or thoroughly, a system must be tested and adjusted. REFERENCES 1 Alfred Koestel and G. L. Tuve: ASHAE Research Report No. 1553--Performance and evaluation cf room air distribution systems (ASHAE Transactions, VoL 61, 1955, p. 533), and J. J. Reinraann, Alfred Koestel, and G. L. Tuve: ASHKAE Re search Report No. 1697--Evaluation of three room air distri bution systems for summer cooling (ASHRAE Transactions, Vol. 65, 1959. p. 717). * John Rydberg and Per Norback: ASHVE Research Report No. 1362--Air distribution and draft (ASHVE Transactions, VoL 55, 1949, p. 225). * F. C. Houghten, Carl Gutberlet, and Edward Witkowski: Draft temperatures and velocities in relation to skin temperatures and feeling of warmth (ASHVE Transactions, VoL 44, 1938, P- 289). * H. E. Straub, S. F. Gilman, aind S. Konzo: Distribution of Air Within a Room For Year Round Air Conditioning--Part I (Uni versity of Illinois Engineering Experiment Station Bulletin No. 435. July 1956) and H. E. Straub and M. M. Chen:.Distribution of Air Within a Room For Year Round Air Conditioning--Part II (University of Illinois Engineering Experiment Station Bulletin No. 442, March 1957). * J. Rydberg: Perforated Ceilings For Air Injection (Kylteknisk Tidsfcrifl, nr 2, April 1963. * J. Rydberg: Cooling Effects and Air Quantities Permissible in Space Air Distribution (Kylteknisk Tidskrift, nr 3, June 1963. I G.L.Tuve: ASHVE Research Report No. 1476--Air veloci ties in ventilating jets (ASHVE Transactions, VoL 59, 1953, p. 261). * H. B. Nottage, J- G. Slaby. and W. P. Gojsza: ASHVE Re search Report No. 1458--Outlet turbulence intensity as a factor in isothermal-jet flow (ASHVE Transaction's, Vol. 58, 1952, p. 343). * G. E. McElroy: Air Plow at Discharge of Fan-Pipe Lines in Mines (U. S. Bureau of Mines Report qf Investigations, R. I.. 3730, November 1943, p. 19). ' Alfred Koestel, Philip Hermann, and G. L. Tuve: ASHVE Research ReportNo.-1366--Air streams from perforated panels (ASHVE Transactions, Vol. 55,1949, p. 283)- - II Air Diffusion Council Test Code 1062 III.(Air Diffusion. Council). ** Alfred Koestel, Philip Hermann, and G. L- Tuve:' ASHVE Research Report No: 1404--Comparative study of ventilating jets from various types of outlets (ASHVE Transactions, Vol. 56, I960, p. 459). u R. D. Madison andW. R. Elliot: Throw of air from slots andjets (ASHVE Journal Section, Heating, Piping and.Av Condi-, Honing, November 1946, p. 108). Entrainment in Ventilating Jets (Case Institute of Tech nology, unpublished paper). u H. B. Nottage, J. G. Slaby, and W. P. Gojsza: ASHVE Research Report No. 1443--Isothermal ventilation--jet funda-) mentals (ASHVE Transactions, VoL 58,1952, p. 107). Alfred Koestel and J. B. Austin, Jr.: ASHAE Research Re port No. 1580--Air velocities in two parallel ventilating jets (ASHAE Transactions, VoL 62,1956, p. 425). 17 Alfred Koestel: ASHAE Research Repost No. 1618--Jet velocities from radial flow outlets (ASHAE Transactions, VoL 63,1957, p. 505). 11 Alfred Koestel: ASHAE Research Report No. 1534--Paths of horizontally projected heated and chilled air jets .(ASHAE Transactions, VoL 61,1955, p. 213). * Alfred Koestel: ASHVE Research Report No. 1512--Com-, puting temperatures and velocities in vertical'jets of hot or cold , air (ASHVE Transactions, Vol. 60, 1954, p. 385). Space Air Distribution 551 * D. W. Nelson, D. H. Krans, and A. F. TuthOl: ASHVE, Research Report No. 1155--The performance of stack heads ' fASHVE Transactions, Vol. 46, 1940, p. 205). ^ *> D. W. Nelson, D. H- Lamb, and G. E. Smedberg: ASHVE Pftf.Hflg Report No. 1206--Performance of stack beads equipped with grilles (ASHVE Transactions, VoL 48,1942, p. 27o9).b- ; W7 Nelson and G. E. Smedberg: ASHVE Research Report No. 1226--Performance of side outlets on horizontal ducts (ASHVE Transactions, VoL 49,1943,jj. 58). ' ** Alfred Koestel and G. L. Tuve: ASHVE Research Report No. --The discharge of air from a long'slot (ASHVE Transactions, Vol. 54, 1948, p. 87). * Alfred Koestel and C. V. Young: ASHVE Research Report No. 1429--The control of air streams from a long slot (ASHVE Transactions, Vol. 57,1951, p. 407). 0 Testing and Balancing Manual for Ventilating and Air Con ditioning Systems. (Veatilatingand Air Conditioning Contractors Association of Chicago). BIBLIOGRAPHY Note: This guide to the literature on air distribution is pur-' posely restricted to papers resulting from research sponsored by ThbAmrucan Soqett op Heating and Ara-CoNDmoioNa Enginbss and other easily accessible material. ASHAE Research Laboratory Cyril Tasker: ASHVE research in air distribution and air duct friction (ASHVE Journal Sechon, Heating, Piping and Air Conditioning, April 1948, p. 125). H. B. Nottage: Ventilation Jets in Room Air ' Distribution. Originally submitted as a Ph-D. thesis to Case Institute of Tech nology (3 volumes). Loan copies available from ASHRAE. Volume I: Data and Interpretations of Teste for Ventila tion Jets Discharging Horizontally into a Large Confining Space (131 pages + 67 figs. + 9 tables). Volume II: Appendix A. Survey of the Literature on the Problems of Ventilation Jets and the Related Fundamentals of Turbulent Flow (499 pages incl. figs, and tables). Volume HI: Appendixes B to H. General Features of lhe Experimental Installations, Instrumentation, and Operations, Boundary-layer Theory and Work-energy Treatment (142 pages incL figs.). He following papers baaed on the above report have been pub lished: H. B. Nottage: ASHVE Research Report No. 1360--Turbu lence--a fundamental frontier in air distribution (ASHVE Transactions, Vol. 55, 1949, p. 193). H.B. Nottage: ASHVE Research ReportNo. 1402--A simple heated-thermocouple anemometer (ASHVE Transactions, VoL 56, 1950, p. 431). H. B. Nottage, J. G. Slaby, and W. P. Gojssa: ASHVE Re search Report No. 1443--Isothermal ventilation-jet funda mentals (ASHVE Transactions, VqL 58, 1952, p. 107). H. B. Nottage, J. G. Slaby, and W. P. Gojsza: ASHVE Resrabch Report No. 144!--A V-wire direction probe (ASHVE Transaction, Voi. 58, 1952, p. 79). H. B. Nottage, J. G. Slaby, and W. P. Gojssa: ASHVE Re search Report No. 1458--Outlet turbulence intensity as a fac tor in isothermal-jet flow (ASHVE Transactions, VoL 58, 1952. p. 343), H. B. Nottage, J. G. Slaby, and W. P. Gojssa: ASHVE Ressarcb Repost No. 1461--A smoke-filament technique for ex perimental research in room air distribution (ASHVE Trans actions, Vol. 58, 1952, p. 399). H. B. Nottage. J. G. Slaby, and W. P. Gojsza: ASHVE Ressabch Report No. 1459--Exploration of a chilled jet (ASHVE raANSACnoNS, VoL 58, 1952, p. 357). ASHAE Cooperative Research at Case Institute of Tech nology G. L. Tuve, D. K. Wright, Jr., and L. J. Seigel: ASHVE Re search Repost No. 1140--The use of air velocity meters (ASHVE Transactions, VoL 45, 1939, p. 645). G. L. Tuve and D. K. Wright,.Jr.; ASHvi/ Rsssabch Report No. 1163--Air flow measurements at intake and discharge open ings and grilles (ASHVE Transactions, Vol. 46, 1940, p. 313).' G. L. Tuve, G. B. Priester, and D. K.-Wright, Jr.: ASHVE Research Report No. 1204--Entrainment and jet-pump action of air streams (ASHVE Transactions, VqL 48, 1942, p. 241). G. L. Tuve and G. B. Priester: ASHVE Research . Report No. 1248--Control of air streams in large spaces (ASHVE Transactions, VoL.50, 1944"p. 153). . Alfred Koestel and G. L. Tuve: ASHVE Research Report No. 1328--The discharge' of air. from a long "slot (ASHVE Transactions, .VoL 54, 1948, p..87). Alfred Koestel, Philip Hermann, and G. L. Tuve: ASHVE Resbabch Repoht No. 1366--Air streams from perforated panels (ASHVE Transactions, VoL 55, 1949, p. 283). Alfred Koestel, Philip Hermann, and G. L. Tuve: ASHVE Research Report No. 1404--Comparative study of ventilating' jets from various types of outlets (ASHVE,Transactions, Vol 66, 1950, p. 459). . Alfred Koestel and C. Y. Young: ASHVE Research Report No. 1429--The control of air streams from a long slot (ASHVE Transactions, VoL 67,'1951,.p..407). ,. G. L. Tuve: ASHVE Research Report No. 1476--Air veloci ties in ventilating-jets (ASHVE Transactions, Vol. 69,1953, pi 261). ASHVE Cooperative Research at Kansas State College Linn Helandcr and C. V. Jakowatz: ASHVE Research Re port No. 1327--Downward projection of heated air (ASHVE Transactions, Vol. 54, 1948, p. 71). Linn Helander, S. M. Yen, and R. E. Crank: ASHVE Re search Repost No. 1475 (In cooperation with the Industrial Unit Heater Asociotion)--Maximum downward travel of heated jets from standard long radius ASME nozzles (ASHVE Transactions, VoL 59, 1953, p. 241). Linn Helander, S. M. Yen, and L. B. Knee: ASHVE Re search Report No. 1511--Characteristics of downward jets of heated air from a vertical delivery discharge unit heater (ASHVE Transactions, Vol. 60, 1954, p. 359). S. M. Yen, Linn Helandcr, and L. B. Knee: AfiHAF, Research Repoht No. 1562--Characteristics of downward jets from a verti cal discharge unit heater (ASHAE Transactions, Vol. 62, 1956, p. 123). Lina Helander, S. M. Yen, and Wilson Tripp: ASHAE Re search Report No. 1601--Outlet characteristics that affect the downthrow of heated air jets (ASHAE Transactions, VoL 63, 1957, p. 255). Rudiger Knaak: ASHAE Research Report No. 1619--Veloci ties and temperatures on axis of downward heated jet from 4-inch long-radius ASME nozzle (ASHAE Transactions, Vol. 63, 1957, p. 527). ASHVE Cooperative Research--General E. L. Davies: ASHVE Research Reports No. 857, 911, and 966--Measurement of the flow of air through registers and grilles (ASHVE Transactions, Vol. 36, 1930, p. 201; Vol. 37, 1931, p. 619; and Vol. 39,1933, p. 373). D. W. Nelson and D. J. Stewart; ASHVE Research Report No. 1076--Air distribution from side wall outlets (ASHVE Transactions, Vol. 44,1938, p. 77). A. M. Greene, Jr. and M. H. Dean: ASHVE Research RspobtNo. 1092--The flow of air through exhaust grilles (ASHVE Transactions, VoL 44, 1938, p. 387). D. W. Nelson, D. H. Krans, and A. F. Tuthill: ASHVE Re search Report No. 1155--The performance of stack heads (ASHVE Transactions, Vol. 46, 1940, p. 205). A. P. Krate, A. E. Herehey, and R. B. Engdahl: ASHVE Re search Report No. 1165--Development of instruments for the study of air distribution in rooms (ASHVE Transactions, VoL 46, 1940, p. 351). D. W. Nelson, D. H. Lamb, and G. E. Smedberg: ASHVE Research Report No. 1206--Performance of stack heads equipped with grilles (ASHVE Transactions, Vol. 48, 1942, p. 279). D. W. Nelson and G. E. Smedberg: ASHVE Research Rb-