Document Lppv07KgKqLQB7Zb6BXEDmOJw

892 CHAPTER 45 1949 Guide tive humidity of 88 to 90 per cent is necessary to hold shrinkage to a mini mum and, at the same time, develop the rind so it will be sufficiently tough to permit handling. Tobacco from the field to the finished cigar, cigarette, plug or pipe tobacco, offers another interesting example of what may be done by indus trial air conditioning in the control of color, texture and flavor. In the processing of tobacco, control of moisture regain, and of chemical and bio chemical reactions, is involved and only through close atmospheric control can the best quality of leaf be developed. Control of Rate of Crystallization The rate of cooling of a saturated solution determines the size of the crystals formed. Both dry- and wet-bulb temperatures are of importance, as the one controls the rate of cooling, while the other, through evapora tion, changes the density of the solution. In the coating pans for pills, gum and nuts, a heavy sugar solution is added to the tumbling mass. As the water evaporates, each separate piece is covered with crystals of sugar. A smooth, opaque coating is only accom plished by blowing into the kettle the proper amount of air at the right dry- and wet-bulb temperatures. The wet-bulb depression determines the rate of moisture pick-up or drying by the air and may be termed the drying head. Of equal importance is the uniformity at which the wet-bulb is maintained. If this is allowed to vary, poor results will follow due to checking and cracking of the unfinished coating. Elimination of Static Electricity The presence of static electricity is very detrimental to the satisfactory and economical processing of many light materials, such as textile fibers, paper, etc. It is also extremely dangerous where explosive atmospheres or materials are present. Fortunately, this hazard is minimized by in creasing the relative humidity if the material being processed is not dam aged thereby. In attempting to eliminate static electricity, it must be borne in mind that for successful elimination the air that actually comes in contact with the material in the machine must be at a relative humidity of 50 per cent or more. As some machines consume a great deal of power which is con verted directly into heat, the temperature in the machine may be consider ably higher than the temperature adjacent to the machine where the relative humidity is normally measured. 'In such cases, the relative hu midity in the machine will be. appreciably lower than that elsewhere in the room, and it may be necessary to maintain a room relative humidity of 65 per cent, or even more, before the desired results can be obtained inside the equipment. CALCULATIONS The methods for determining the heating and cooling loads for the various industrial processes are similar to those outlined in Chapters 14 and 15. The several other chapters.previously cited call attention to addi tional phases of calculation which may be needed.- Because of the large number of motors and heat producing units usual in an industrial applica tion, it is particularly important that, operating allowances for the latent and sensible heat loads be definitely ascertained and used in the calculations to determine the total design load.,. .. . Industrial Air Conditioning 893 BIBLIOGRAPHY ' HEALTH, SAFETY AND EFFICIENCY Lectures, The Inservice Training Course in Environmental Controls for Industrial Processes, University of Michigan School of Public Health, 1946: Environmental Controls in Industrial Health, by R. R. Sayers; Principles of Industrial Process Ventilation, by W. N. Witheridge; The Selection and Maintenance of Equipment for Process Control, byR. P. Warren; Environmental Control of Industrial Processes as Affected by Foundry Lay-out, by John Linabury; Foundry Ventilation, by: J. M. Kane; Control of Welding Hazards, by W. C. L. Hemeon; Environmental Control of the Metal Cleaning Processes, by F. A. Patty; Painting, by T. F. Mooney; Health Hazards in the Electroplating Industry, by William Blum; Industrial Housekeeping and Sanitation, by John Soet. '. - Air Sanitation and Industrial Ventilation, by W. N. Witheridge, Detroit, 1945. Ah Investigation of the Bacterial Contamination of the Air of Textile Mills with Special Reference to the Influence of Artificial Humidification, by W. F. Wells and E. C. Riley (The Journal ofIndustrial Hygiene and Toxicology, Vol. 19, No. 10, Decem ber, 1937). Industrial Cooling as a Production Aid, by J. Partington, Jr. (Heating and Ven tilating, April, 1944, p. 47). Industrial Exhaust Ventilation in Industrial Hygiene, by A. D. Brandt (A.S.H. V.E. Transactions, Vol. 50,1944, p. 331). Control of Industrial Atmospheres, by W. N. Witheridge (A.S.H.V.E. Transac tions, Vol. 51, 1945, p. 227). Mine Ventilation and its Relation to Health and Safety, by D. Harrington (A.S.H.V.E. Transactions, Vol. 61,1945, p. 243). ' Ventilation Requirements for Industrial Solvents, by W. C. L. Hemeon (Heating and Ventilating, December, 1945, p. 95, January, p. 69, March, p. 82, and April, p. 79, 1946). ' Guides for Industrial Ventilation, by Allen D. Brandt (Heeding and Ventilating, March, 1946, p. 67). Industrial Dust Explosions, by Hylton R. Brown (Heating and Ventilating, March, 1946, p. 73). ' Supply Air in Plant Ventilation, by J. B. Skinner and William M. Pierce (//eating and Ventilating, May, 1946, p. 57). What Air Conditions Make for Comfort in Industry?, by H. A. Mosher (Healing, Piping and Air Conditioning, April, 1946, p. 106). Air Conditioning Requirements for Workers in Factories, by H. A. Mosher (Heating, Piping and Air Conditioning, August, 1946, p. 82). Hot Weather Limits Hard Work. (Brief summary of investigation done for Ariny Quartermaster Corps, by Department of Physiology, Medical School, University of Indiana. Heating and Ventilating, August, 1947, p.. 110). MethodsUsed in Determining the Health Hazards Arising from the Inhalation of Various Chemicals, by Francis F. Heyroth (A.S.H.V.E. Journal SiX-rlON, Healing, Piping and Air Conditioning, January, 1947, p. 109, and discussions, Heating, Piping and Air Conditioning, April, 19-17, p. 113). Air Recirculation from Exhaust Systems, by John M. Kane (Healing and Ventilat ing, April, 1947, p. 75). Should Air Be Recirculated from Industrial Exhaust Systems? by Allen D. Brandt (Heating, Piping and Air Conditioning, August, 1947, p: 69). Dehumidification Methods and Applications, by John Everetts, Jr. (A.S.H.V.E. Journal Section, Heating, Piping arid Air Conditioning, December, 1946, p. 121). Rating Dynamic Dehumidification Equipment, by E. R. Queer and E. R. McLaughlin (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, January, 1947, p. 103). Processing - Refrigerating Data Book, Refrigeration Applications Volume, Second Edition, 1946, Section VIII, Industrial Air Conditioning, Chapters 67 to 76, and Section III, Refrigeration in Food Manufacture, Chapters25 and 26, American SocietyofRefrigera ting Engineers. . Air Conditioning forSausage Manufacturing Plants, by M. G. Harbula (A.S.H. V.E. Transactions, Vol. 28,1922, p..343).. y