Document 3QN0KXXQXka0qRq3BbbR5wwda

HEATINC VENTILATING AIR CONDITIONING GUIDE 1942 Steam Heating in the Sky (Heating, Piping and Air Conditioning, October, 193s p. 631). Steam Heating for Modern Air Transports, by Jack McQuire (Heating and Ventilatinp February, 1939, p. 37). Altitude Conditioning (Heating and Ventilating, August, 1940, p. 16). 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)! 716 Chapter 39 INDUSTRIAL AIR CONDITIONING 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 Crystallisation, Elimination of Static Electricity IN the application of air conditioning to industrial processes, too much stress cannot be laid upon a thorough understanding by the air con ditioning engineer of the problems involved. A complete knowledge of these problems is necessary before a satisfactory design can be made. Individual processes and machines are changing rapidly and air con ditions must be constantly revised to meet the new conditions. % ATMOSPHERIC CONDITIONS REQUIRED The most desirable relative humidity during processing depends, upon the product and the nature of the process. As far as the behavior of the material itself and its desired final condition are concerned, each material and process presents a different problem. The best relative humidity may range up to 100 per cent. Similarly the most desirable temperature may range between wide limits for different materials and treatments. Ex tremes in either relative humidity or temperature require relatively expensive equipment for maintaining these conditions automatically. In departments where people are working, their health, comfort, and productive efficiency must be considered and often a compromise between the optimum conditions for processing and those required for the comfort of the worker is desirable. It is generally considered that relative humidities below 40 per cent are on the dry side, conducive to low regains, a brittle condition of fibrous materials, prevalence of static electricity, and a tendency toward dryness of the skin and membranes of human beings. At the other end of the scale, humidities above 80 per cent are relatively damp, conducive to high regains, extreme softness, and pliability. Table 1 lists desirable temperatures and humidities for industrial pro cessing. In using this table, care must be taken in qualifying the process. In preparing many materials, conditions are not maintained constantly, but different temperatures and humidities are held for varying lengths of time. 717'