Document 4Xo6rv3x8gaN31RzVJnmE18R

946 CHAPTER 44 1952 Guide . Table 2. Regain op Hygroscopic Materials Moisture Content Expressed in Percent of Dry Weight of the Substance at Various Relative Humidities--Temperature, 75 F Class]- Description Relative Hojudot--Pee Cent Authobitt 10 20 30 40 50 60 70 80 90 Cotton Sea island--roving 2.5 3.7 4.6 53 6.6. 7.9 93 11.5 143 HufhiKftpift Cotton American--cloth 2.6 3.7 4.4 5.2 33 63: 83 too 143 Schloesing Cotton Absorbent ' 4.8 9.0 12.5 15.7 183 203 223 243 25.8 Fuwa Wool Natural Textile Silk Australian merino--skein 4.7 7.0 8.9 103 123 14.9, 173 19.9 23.4 Hartahorne Raw chevennes--skein 3.2 '5.5 6.9 8.0 8.9 103 11.9 143 183 Schloesing linen Table cloth 1.9 2.9 3.6 43 5.1 6.1 7.0 8.4 103 Atkinson linen Dry spun--yarn 3.6 5.4 6.5 73 83 8.9 93 11.2 133 Sommer Jute Average of several grades 3.1 5.2 6.9 83 10.2 123 14.4 173 203 Storch Hemp Manila and sisal--rope 2.7 4.7 6.0 7.2 83. 9.9 ii-6 13.6 15.7 Fuwa Rayons Viscose Nitrocellu lose Cupramonium Average skein Cellulose Acetate Fiber 4.0 5.7 6.8 7.9 9.2 103 12.4 143 16.0 Robertson 0-8 1.1 1.4 1.9 2.4 3.0 3.6 43 53 Robertson M. F. Newsprint Wood pulp--24% ash 2.1 3.2 4.0 4.7 S3 63 73 8.7 10.6 U. St B. of S. H. M. F. Writing Wood pulp--3% ash 3.0 4.2 5.2 6.2 7.2 83 9.9 119 143 U. S. B. of S. Piper White Bond Rag--1% ash 2.4 3.7 4.7 53 63 73 83 10.8 133 U.S.B.of& Com. Ledger 75% rag--1% ash 3.2 4.2 5.0 5.6 63 6.9 83 103 13.9 U.S.B. ofS. Kraft Wrapping Coniferous 3a 4.6 5.7 6.6 7.6 8.9 10.5 12.6 14.9 U. S. B. of S. Leather Sole oak--tanned 5.0 83 11.2 13.6 16.0 183 20.6 24.0 293 Phelps Catgut Racquet strings 4.6 7 2 8.6 102 123 143 173 193 21.7 Fuwa Clue Hide 3.4 4.8 5.8 6.6 73 9.0 10.7 113 123 Fawn Organic Rubber - Sofid tires an a2i 032 044 034 066 076 0.88 099 Fuwa Wood Timber (average) 3.0 4.4 5.9 7.6 93 113 (4 0 173 22.0 Forest P. Lab. Soap WHta 1.9 3.8 5.7 7.6 10.0 12.9 163 193 233 Fuwa Tobacco Cigarette 5.4 8.6 11.0 133 16.0 193 25.0 33.5 50 0 Ford White Bread 03 1.7 3.1 43 63 83 113 143 19.0 Atkinson Crackers 2.1 2.8 33 3.9 5.0 63 83 10.9 14.9 Atkinson Food-' . Macaroni stuffs Flour 5.1 7.4 83 10.2 117 13.7 163 19.0 223 Atkinson. 2.6 4.1 53 6.5 8.0 9.9 12.4 15.4 193 Bailey Starch 2.2 33 5.2 6.4 7.4 83 93 10.6 12.7 Atkinson Gelatin 0.7 1.6 23 33 4.9 63 7.6 93 11.4 Atkinson Asbestos fiber Finely divided. 0.16 0.24 0.26 032 041 031 062 073 0.84 Fuwa Shea Gel' 5.7 9.8 12.7 153 173 183 203 213 22.6 Fuwa Inorganic Domestic Coke 0.20 0.40 0.61 0.81 1.03 134 1.46 1.67 139 Selvig Activated Charcoal Steam activated 7.1 14.3 223 26.2 283 293 30.0 313 32.7 Fuwa Sulfuric Acid HtSO* 33.0 41.0 47.5 523 S7.0 613 67.0 733 823 Mason surface of the solution, and maintains a solution of known strength through out the mercerizing period. Another well-known example in this class is the drying of varnish which is an oxidizing process dependent upon temperature. High relative hu midities have a retarding effect on the rate of oxidization at the surface, and IndustrialjAir Conditioning 947 allow the internal gases to escape freely-as the chemical oxidizers cure the varnish from -within. This produces a surface free from bubbles and a homogeneous film throughout. . Desirable temperatures for drying varnish vary with the type. A relative humidity of 65 percent is beneficial for ob taining the best processing results. Control of Rate of Biochemical Reactions - In the field of biochemical, control, industrial air conditioning has been applied to many different and well-known products. All problems involv ing,fermentation are classed under this heading. As biochemistry is a sub division of chemistry, subject to the same laws, the rate of reaction may be controlled by temperature. An example of this is the dough room of the modem bakery. Yeast develops best at a temperature of 80 F. A relative humidity of 70 percent is maintained to hold the surface of the dough open to allow the carbon dioxide gases formed by the fermentation to pass through and produce a loaf of bread, when baked, of even, fine texture without large voids. The curing of fruits, such as bananas and lemons, also comes under this classification. Bananas require a cycle of temperatures and relative hu midities for ripening. . The starches in the pulp of the fruit must be changed and the skin cured and colored, after: which the fruit is cooled to maintain as low a rate of metabolism as possible. Ideal storage conditions range between 56 and 60 F, with about 85 percent relative humidity, and ventilation at the rate of three or four air changes per hour. The curing of lemons is an entirely different problem. Bananas are cured for a quick market, while lemons are held for a future market. The process, therefore, varies in the- temperature used. Temperatures from 54 to 59 F have been found to be best suited for.this process. A high rela- tive humidity of 84 to 88 percent 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. If the cooling and drying are too slow, the coating will be rough and semi-translucent, and the appearance un sightly; if too fast, the coating will chip through to the interior. Only by balancing temperature, relative humidity, and volume of air to the sugar solution, can the proper rate be obtained and a perfect coating assured.