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1156 CHAPTER 46 1958 Guide lenses, temperature variations may cause expansion And contraction of material to an extent that will seriously affect the quality of the work. This type of work usually requires close temperature control to assure accuracy and uniformity of the product. Usually the temperature level with respect to the product is not as important as controlling the temperature within close limits. For this reason, conditions are usually selected within`the comfort range. Control of Dew-Point for Protection of Polished Surfaces In the manufacture of certain metal articles, the presence of finger prints, tarnish, or etching can not be' tolerated in the finished article. If these articles are. manufactured under conditions of effective tempera tures that will cause the hands to perspire, an unsatisfactory product will result. The salt and acid contained in body perspiration, when deposited on the highly polished article, can show corrosion and rust within a few hours if examined under a microscope. It is therefore important to maintain temperatures and relative humidi ties (dew-point) low enough to prevent sweating of the hands. In addi tion, the manufacture of polished surfaces usually requires a better-thanaverage job of air filtering to avoid'abrasion of the surfaces. Control of Humidity for Reduction of Static Electricity The presence of static electricity is often 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 to at least 55 percent, if the material being processed is not damaged thereby. 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 55 percent or more. As some machines consume a great deal of power, which is converted directly into heat, the tempera ture in the machine may be considerably higher than the temperature adjacent to the machine where the relative humidity is normally measured. In such cases, the relative humidity in the machine will be appreciably lower than that elsewhere in the room, and it may therefore be neces sary to maintain a room relative humidity of 65 percent, or even more, to maintain the desired-humidity. Control of Conditions for Material Test Laboratories Laboratories having controlled conditions of temperature and humidity, are becoming more common, not only for the purposes of scientific re search, but also for routine testing and for quality production control. A control of temperature and humidity within fairly close plus or minus limits is usually required. Laboratories designed for scientific research may require control of conditions over a wide range, whereas the routine testing laboratory or quality control laboratory will usually be designed to maintain the A.S.T.M. Standard Conditions of 50 percent relative hu midity and 23 C (73.4 F) temperature. CALCULATIONS The methods for determining the heating and cooling loads for the various industrial processes are similar to. those outlined in Chapters U and 13. Some factors affecting heating or cooling requirements are give? Process and Product Air Conditioning 1157 in Table 1. Because of the large number of motors and heat producing units usually found in an industrial application, it is particularly important that operating allowances, for the latent and sensible heat loads, be defir nitely ascertained and used in the calculations to determine the total design load. BIBLIOGRAPHY Processing When Is Complete Air Conditioning of the Modern Factory Advisable? by H. A. Mosher (Healing Piping and Air Conditioning, June, 1945, p. 305 and July, 1945, p. 385). . Air Conditioning Design Conditions for Various Industries, by N. N. Wolpert (Beating and Ventilating, May 1949, p. 70; June 1949, p. 73; July 1949, p. 79;'Aug. 1949, p. 102). Air Conditioning Design Data for Commercial Applications, by N. N.-- Wolpert (Beating and Ventilating, Feb. 1950, p. 68). ' ' ASRE Data Book 1950 (American Society of Refrigerating Engineers). Refrigeration of Oranges in California, by H. M. Hendrickson and J. R. MacRill, Refrigerating Engineering Application Data, No. 17-R (American Society of Refriger ating Engineers). Refrigeration of Lemons and Grapefruit, by H.M. Hendrickson and J. R. MacRill, Refrigerating Engineering Application Data- No. 18-R (American Society of Re frigerating Engineers). Air Conditioning in the Bakery, by W. L. Fleisher (A.S.H.V.E. Transactions, Vol. 37,1931.p. 141). Air Condition the Bakery Throughout, by W. W-. Reece (Heating, Piping and Air Conditioning, August, 1936, p. 419). The Air Conditioning of Processes in the Bread Bakery,'by H. R. Gable (A.S.H. V.E. Journal Section, Heating, Piping and Air Conditioning, October 1947, p. 107). Air Conditioning in Candy Manufacture, by H. C. Hoffmann (Section 39, Refriger ating Engineering Application Data, Refrigerating Engineering, April, 1947). Proper Air Conditions for the Manufacturing of Confections, by A. E. Stacey, Jr. (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, October 1937, p. 640). . Air Conditioning for Sausage Manufacturing Plants, by M. G. Harbula (A.S.H.V.E. Transactions, Vol. 28, 1922,p. 343). Relation of Air Conditions to Tobacco Curing, by J. Johnson and W. B. Ogden (Wisconsin Agricultural Research Bureau 110:1-48,1931). Heating, Air Conditioning and Insulation for Penicillin Production, by J. C. Siegesmund (Heating, Piping and Air Conditioning, August, 1944, p. 475). Air Conditioning in Textile Mills, Research Department Technical Report, Textile Workers Union of America, C.I.O. . Air Conditioning for Textile Plants Making and Using Synthetic Yarns, by L. L. Lewis (Rayon Textile Monthly, July, August, September, 1930). Refrigeration for Textile Mill Air Conditioning, by P. L. Davidson (Heating and Ventilating, May, 1947, p. 57). k 7?r5,au Standards Studies Determine Press Room Conditioning Requirements, C. G. Weber (Heating, Piping and Air Conditioning, March, 1936, p. 137). Humidity in the Pressroom (Heating and Ventilating, May, 1932, p. 35). P* 3D1e).humidifying with Gas in a Printing Plant (Heating and Ventilating, May, 1935, . A!f Conditioning the Newspaper Plant, by R. T. Williams (Heating and Venlilat*n9 September, 1937, p. 63). P* *o). Conditioning in the Paper Industry (Heating and Ventilating, October, 1935, ,r>A'r. Conditioning Requirements of Multicolor Offset Printing, by C. G. Weber \aelngerating Engineering, December, 1936, p. 6). Wr c? * Lithographic Papers to Variations in Humidity and Temperature, January jg^er ar|d L. W. Snyder (U. S. Bureau of Standards Journal of Research, V Treatment of Offset Papers for Optimum Register, by C. G. Weber and M. N. q-f- y; S. Bureau of Standards Journal of Research, February, 1936). Rllca Cel Air Conditioning System Serves Rotogravure Printing Plant, by H. E. Airr Piping and Air Conditioning, August. 1937, p. 497). Juuilyv pl.t,609D).'n6 ir Clothing Research Laboratory (Healing and Ventilating,