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660 Chapter 36__________ . _____________1945 Guide . important applications in certain hospital wards such as nurseries for premature infants, oxygen therapy chambers, heat, therapy rooms or cabinets, allergy wards41, operating rooms and recovery wards. 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--usual heating 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 window 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 advantage from May to October, and in tropical climates almost con tinuously throughout the year. 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, and in a variety of other ailments which often accompany summer heat waves. Considerable research is in progress on the influence of air conditioning upon a wide variety of diseases such as pneumonia, upper respiratory diseases, tuberculosis, arthritis, nervous instability, hyper-thyroidism, essential hypertension, skin diseases, and vascular disorders. 4lLoc. Cit. Note 37. -- ------------ '-------------CHAPTER 37 reimportation ~sdir C^onditi toning. Railway Passenger Car Ventilation, Method of Air Distri bution, Air Cleaning', Winter and Summer Air Conditioning, Humidity and Temperature Control, Summer Air Condition ing for Buses and Automobiles, Airplane Air Conditioning THE principles of air conditioning used in connection with stationary applications: such as stores, restaurants, hospitals, theaters, and homes are in general applicable to such mobile applications as railway passenger cars, passenger buses, automobiles, and ships. However, the equipment used for these mobile applications, differs from that used for stationary purposes in that it must meet additional requirements. Especially important are the features of compactness with the retention of ready accessibility for quick inspection and servicing, and low weight. Freedom from vibration which could be transmitted to.the supporting vehicle and thus to the passengers is essential. (For Air Conditioning of Ships see Chapter 38.) RAILWAY PASSENGER CAR VENTILATION In non-air-conditioned cars, ventilation is accomplished by exhaust fans, roof ventilators, and open doors and windows. This practice provides an ample supply of outside air but does not prevent the entrance of smoke, cinders, and other dirt. 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 the other constituents can be successfully handled only by proper ventilation and air cleansing. In the average car from 2000 to 2500 cfm should be circulated by the air conditioning unit. Some of this air may be recirculated, but a portion:of it should always be brought in from the outside. The amount of outside air required depends upon the type of car, number of passengers, air temperature, humidity, odors, and whether or not occupants are smoking, and will vary from 15 to 90 per cent 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 to supply more ventilation than is necessary. Conditioning this outside air is a major factor in determining the size of both summer and winter con ditioning equipment. With present average ventilation requirements, about 30 per cent of the cooling equipment and sometimes as high as 50 per cent of the heating equipment is necessary to handle only the outside air load. For normal conditions, 10 cfm of outside air per passenger is sufficient. When smoking is permitted, at least 15 cfm should be admitted. In some of the dining cars and de luxe sleeping cars, outside air rates as high as 20 and 30 cfm per occupant are used. Method of Air Distribution The fact that the amount of space devoted to railway passengers may be as low as 60 cu ft per person (ranging as high as 190 cu ft per person) and the high air flow rates made necessary by severe ventilation and sun