Document Bya4Jrqqq477Lkbbvnyoo23jJ

288 W. N. WITHBRIDGE of .the fact that sufficient outdoor air will find its way into the structure by natui forces. Certainly the advisability of operating ail air-conditioning system with.^j the use of outdoor air will depend upon future discoveries in the realm of; "freshness" and whether it proves possible to convince most persons that a e* thetic environment is just as fresh and healthful as outdoor air. Ventilation rates for the control of tobacco smoke and body odors in varip applications are suggested in Table 2. Outdoor air (c.f.m./ person) TABLE 2 Recommended Quantities of Outdoor Air per Person0 Type of space or occupancy 6-10 10-15 15-20 20-30 30-60 High-ceiling space such as: bank, auditorium, church, department store,? theater; room with no smoking Apartment, barber shop, beauty parlor, hotel room; room with light. smoking .f Cafeteria, drug store with lunch counter, general office, hospital room,' public dining room, restaurant; room with moderate Bmoking Broker's board room, private office, tavern; room with heavy smokini Conference room, night club: crowded room with heavy smoking "Air-cleaning or odor-removing devices not used. (Space not less than 150 cu. ft. per pe or floor area not less than 16 sq. ft. per person.) State and city codes should be consulted to make certain that min.mum outdoor-a quirements.are-followed.------------- ------ -- -- -- - - - --------------------------------- C. EFFECT OF ROOM SIZE ON VENTILATION REQUIREMENTS A series of experiments8,5 on ventilation requirements for human occup1 demonstrated that ',f ' air space per occupant in a room not only affects the disappearance rate of bod^-jSl and hence ventilation requirements, but also the efficiency of ventilation systems. Larg^jj. have an advantage over small ones, as they act like reservoirs, allowing body odors td^disa with a minimum supply of outdoor air and maximum ventilation efficiency. A small) would require a greater air supply per occupant for the control of body odor. An increa|_ supply entails a loss of ventilation efficiency, as the air passes quickly to the exhaust..wi removing a full share of odors, heat, and moisture.0 . Table 3 summarizes the results of these experiments. With respect to tobacco odors, however, their tendency to becoml offensive during the first few hours after smoking indicated that retaining! longeT^in the occupied, space by .increasing the volume of the space actual^ a handicap. The conclusion was that for control of tobacco smoke by di ventilation, small volumes of air space and high ventilation rates per capita^' be a preferable combination. 0 C. P. Yaglou and W. N. Witheridge, Trans. ASHVE, 43, 423 (1937). VENTILATION 289 TABLE 3 Requirements of Outdoor or Odor-Free Air for Dilution of Body Odors* Clean air supply i./person0) Type of occupants and kind of ventilating equipment6 At3iiq, * Tl 29 School children; av. personal hygiene 25 Sedentary adulta 22 School children; best personal hygiene 38 School children; poor personal hygiene 23 Laborers 21 School children; av. personal hygiene 18 School children; above av. personal hygiene 16 Sedentary adults 12 Sedentary adults; air washed by centrifugal atomizing humidifier <4 Sedentary adults; summer season; air cooled and de humidified by spray washer; water changed daily 17 School children 12 Sedentary adults 11 School children 7 Sedentary adults |||ased on impressions of persons entering experimental room from relatively clean air at -Jjlpui'' odor intensity. Allowable odor intensity of 2 on a scale ranging from 0 for no ||ti6le odor to 5 for nauseating or overpowering odor. Tgfifating season, air not washed or conditioned, except as noted. |||| D. MINES, TUNNELS, AND UNDERGROUND SPAQES has burrowed underground for many years, and the deeper he goes, acutely conscious he becomes of excessively high temperatures and `SfA'vili88 ant^ Presence dangerous gases. The removal of industrial and quarters to underground air-raid shelters makes the ventilating and "vlllr 9ninS sngineer a highly essential member of the design organization. hygienists are now generally aware that the conditioning of under^Pmospheres is indispensable in the safe operation of deep mines. Tfe^specialized problems of underground ventilation will not be discussed Spreader is referred to comprehensive publications on this subject.6 II. General Ventilation |||i|ra] ventilation may be classified in several ways to accommodate such P||||!i8'a8 (1) natural or mechanical, (2) supply or exhaust, ('.?) directional <^pl|FMcElroy, XJ. S. Bur. Mines Bull. No. 385, 1935; D. Harrington and 8. J. Daven- U' S' BuT' Mines CiTC' No' 7001' 1938' Part 2' ibid-> No- 7182, 1941; D. Har- iftiSr Piping' Air Conditioning, 17, 275 (May, 1945); G. E. McElroy, A mine air- '>@18-.'hart, U. S. Bur. Mines Rept. Invest. No. 4165, 1947; I. M. Rice, Heating, ven- , . KsISffd.air conditioning of underground installations, Quart. Colo. School Mines, 46, 258 51951). I