Document KGyqgR43ym1orkbx4Y7aeMxR6

HEATING VENTILATING AIR CONDITIONING GUIDE 1944 Portable Climate, American Buys 12 Plane Air Conditioning Units (Aviation, 36:59, September, 1937). Steam Heating in the Sky (Healing, Piping and Air Conditioning, October, 1938, p. 631). Altitude Conditioning (Heating and Ventilating, August, 1940, p. 16). Comfort in High Altitude Flying, by D. W. Tomlinson (A.S.H.V.E. Transaction's, Vol. 47, 1941, p. 57). Ships Ventilation and Air Conditioning of the S. S. Panama (Heating and Ventilating, September, 1939, p. 47). Air Conditioning the New Mauretania (Heating, Piping and Air Conditioning, July, 1939, p. 431). Heating, Ventilating and Air Conditioning on Shipboard, by J. H. Clarke (Heating, Piping and Air Conditioning, August, p. 467; September, p. 529; October, p. 610, 1940). Care of Cargo at Sea, by O. D. Colvin, W. H. E. Hahne and M. R. Colby (Trans actions of the Society of Naval Architects and Marine Engineers: Part I, Vol. 46, 1938, p. 109; Part II, Vol. 49, 1941, p. 208). Ventilation of Ships, by J. Dawson (Journal of The Institution of Heating and Venti lating Engineers, London, Vol. 10, June-July, 1942, No. Ill, p. 89). 704 CHAPTER 39 ~3ndu.striai^iV Cdondililonincf Atmospheric Conditions Required, General Requirements, Classification of Problems, Control of Regain, Moisture Con- tent and Regain, Conditioning and Drying, Control of Rate of Chemical Reaction, Control of Rate of Biochemical Re- actions. Control Rate of Crystallization, Elimination of Static Electricity ACOMPLETE knowledge of the problems involved is necessary before a satisfactory solution can be made of industrial air con ditioning problems. Individual processes and machines are changing rapidly and air conditions must be constantly revised to meet the new conditions. ATMOSPHERIC CONDITIONS REQUIRED The most desirable relative humidity for processing depends upon the product and the nature of the process. As far as the behavior of the material and its desired final condition are concerned, each material and process presents a different problem. The desirable relative humidity may range from a low of 5 per cent, as in certain industrial applications, such as insulation winding processes, up to a condition approaching saturation, as in processes relating to textiles, tobacco and baking industries. Similarly, the most favorable temperature will vary according to the specific material and particular process. Frequently a compromise between the known optimum condition for processing and that required for reasonable worker comfort is desirable. This is particularly true where unconfined processes are required in departments where people are working and their health, comfort and productive efficiency must be considered. It is generally recognized that relative humidities of .50 per cent or less are on the dry side. Such conditions are conducive to low regains in hygroscopic materials, drying out, increased brittleness of fibrous materials, prevalence of increased static electricity and tendencies toward increased dust liberation from the product. Relative humidities higher than 50 per cent are considered to be on the damp side. These con ditions are conducive to high regain, promote softness and pliability in materials, decrease static electricity and' tendencies toward reducedgeneration of product dust which represents a loss in weight of the material in process. 705