Document 9JGYkgj5K3rokKE27Ld3ML6N7

1018 CHAPTER 45 1955 Guide . - Table 2. Regain of Hygroscopic Materials Moisture Content'Expressed in Percent of Dry Weight of the Substance at Various Relative Humidities--Temperature, 75 F ' Clabsifi- .Matebiai/ `''Description Relative Hcmiditt--Percent Author- to 20 30 40 50 60 70 80 90 ITT Cotton Cotton J .Cotton . Wool Natural Textile Silk Fibers Linen Linen - Jute . Hemp Sea island-- roving American-- cloth Absorbent Australian me- rino--skein Raw chevennes --skein Table doth Dry spun-- yarn Average of sev.- eral grades Manila and sisal--rope 26 3:7 4.6 5.5 6.6 7.9 9.5 11.5 14,1 Harts- horns 2.6 3.7 4.4 5.2 5-9 6.8 8.1 10.0 14.3 Schloes. in*" 4.8 9.0 12.5 15.7 18.5' 20.8 22.8 24.3. 25.8- Fuwa 4.7. 7.0 8.9 10.8 12.8 14.9 17.2 19.9 23.4 HarW shame 3.2 5.5 6.9 8.0 8.9 10.2 11.9 14.3 18.8 Schloes- in* 1.9 2.9 3.6 4.3 5.1 6.1 7.0 8.4 10.2 Atkinson 3.6 514 6.6 7.3 8.1 8.9 9.8 11.2 13.8 Sommer 3.1 5.2 0.9 8.5 10.2 12.2 14.4 17.1 20.2 Starch 2.7 4.7 6.0 7.2 8.5 9.9 11.6 13.6 15.7 Fuwa Rayons. - Viscose Nitrocellulose Cupramo. ilium Celulose-Ace- ' tate Average skein 4.0 5.7 6.8 7.9 9.2 10.8. 12.4 14.2 16.0 Robert0.8 1.1 1.4 1.9 2.4 3.0 3.6 4.3 5.3 Robert- Paper M. F. Newsprint H. M. F. Writing White Bond Com. Ledger Kraft Wrap- . ping Wood pulp-- 24% ash Wood pulp-- 3% ash . Rag--1% ash 75% rag--1% ash > Coniferous 2.1 3.2 4.0 4.7 5.3 6.1 7.2 8.7 10.6 NBS 3.0 4.2 5.2 6.2 7.2 8.3 9.9 11.9 14.2 NBS 2.4 3.7 4.7' 5.5 6.5 7.5 8.8 10.8 13.2 NBS 3.2 4.2 5.0 5.6 6.2 6.9 8.1 10.3 13.9 NBS 3.2 4.6 5-7 6.6 7.6 8.9 10.5 12.6 14.9 NBS Leather . Misc. ` Organic Materials Catgut Glue Rubber ' .'Wood Soap Tobacoo' Sole oak-- tanned Racquet strings Hide Solid tires' Timber (average) White Cigarette s:o 8-5 11.2 13.6 16.0 18.3 20-6 24.0 29.2 Phelps 4.6 3.4 0.11 3.0 7.2 4.8 0.21 4.4 8.6 10.2 12.0 14.3 17.3 19.8 21.7 5.8 6.6 7.6 9.6 10.7 11.8 12.5 0.32 0.44 0.54 0!66 0.76 0.88 0.99 5.9 7.6 9.3 11.3 14.0 17.5 22.0 1.9 3.8 5.7 7.6 10.0 12.9 16.1 19.8 23.8 5.4 8.6 11.0 13.3 16.0 19.5 25.0 33.5 50.0 Foodstuffs White Bread Crackers. Macaroni Flour Starch Gelatin 0.6 1.7 2.1 .2.8 5.1 7.4 2.6 4.1 2.2 3.8 0.7 1.6 3.1 4.5 6.2 8.5 11.1 14.5 19.0 3.3 3.9 5.0 6.5 8.3 10.9 14.9 8.8 10.2 11.7 13.7 16.2 19.0 22.1 5.3 6.5 8.0 9.9 12.4 15.4 19.1 5.2 6.4 7.4 8.3 9.2 10.6 12.7 2.8 3.8 4.9 6.1 7.6 9.3 11.4 Asbestos Fiber Silica Gel * Inorganic '.Materials _ Activated.Charcoal' Sulfuric Acid Finely divided " Steam activated HtSOt 0.16 0.24 0.26 0.32 0.41 0.51 0.62 0.73 0.84 6.7 9.8 12.7 15.2 17.2 18.8 20.2 21.5 22.6 Fuwa 0.20 0.40 0.61 0.81 1.03 1.24 1.46 1.67 1.89 Seivi* 7.r 14.3 22.8 26.2 28.3 29.2- 30.0 31.1 32.7 33.0 41.0 47.5 52.5 57.0 61.5 67.0 73.5 82.5 Industrial Air Conditioning 1019 is an oxidizing process dependent upon temperature. High relative hu-. . nudities have a retarding effect on the rate of oxidization at the surface, and iallow the internal gases to escape freely as the chemical oxidizers cure the varnish from withm. 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. Ah 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 51 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 evaporahon, 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 13 covered with crystals of sugar. A smooth, opaque coating is only accomPushed by blowing into the kettle the proper amount of air at the right tviy ant^. wet-bulb temperatures. If the cooling and drying are too slow, me coating will be rough and semi-translucent, and the appearance unRightly; if too fast, the coating will chip through to the interior. Only by glancing temperature, relative humidity, and volume of air to the sugar solution, can the proper rate be obtained and a perfect coating assured.