Document doG9Z4GEQVBzGRvxaBN5jk5R

1154 CHAPTER 46 1958 Guide Table 2. Regain, of Hygroscopic Materials Moisture Content Expressed tn Percent of Dry Weight of the Substance at Various Relative Humidities--Temperature, 75 F ClassifiCATION Material Relative Humidity--Percent 10 2f 50 Authob90 Cotton Cotton Natural . Textile Fibers Cotton Wool Silk Linen Linen' Jute Hemp Sea island-- roving American-- cloth Absorbent Australian me- rino--skein Raw cbevennes --skein Table cloth Dry spun-- yarn Average of sev- eral grades Munilii and sisal--rope 2.5 3 2.6 3. 4.8 9 4.7 7 3.2 5 1.9 2 3.6 5 3.1 5 2.7 4 7.9 11.5 14.1 4.4 6.8 10.0 14.3 112.5 15.7 18.5 20.8 22.8 24.3 25.8 8.9 10.8 12.8 14.9 17.2 19.9 23.4 8.9 10.2 11.9 14.3 6.1 8.4 10.2 8.9 111 :2 13.8 HartshnrpB Schloee* ing Fuwa Hart- shame Schloea- ing Atkinson Sommer |l0.2 |l2.2 14.4 17.1 i.2 Storch 8.5 9.9 11:6 13.6 |15.7 Fuwa Rayons Viscose Nitrocellulose Cupramonium Celulose Acetate Average skein Paper M. F. Newsprint H. M. F. Writing White Bond Com. Ledger Kraft Wrapping Wood pulp-- 24% ash Wood pulp-- 3% ash Rag--1% asb 75% ns--1% ash Coniferous 4.0 5 0.8 1 a2.1 3.0 4 2.4 ; 3.2 3.2 Leather Misc. Organic Materials Catgut Glue Rubber Wood Soap Tobacco Sole oak-- tanned Racquet strings Hide Solid tires Timber (average) White Cigarette 5.0 4.6 3.4 0.11 3.0 1.9 5.4 9.2 110.8 112.4 Il4.2 16.0 Robert son 2.4 3.0 3.6 4.3 5.3 Robert son 10.6 NBS 14.2 NBS 5.7 6.8 7.6 10.8 113.2 NBS 10.3 Il3.9 NBS 10.5 14.9 NBS 111 .2 |l3.6 16.0 18.3 24.0 29.2 Phelps 8.6 |10.2 12.0 14.3 |l7.3 19.8 21.7 Fuwa 5.8 6.6 7.6 9.0 |l0.7 11.8 12.5 Fuwa 0.32 0.44 0.541 0.66 0.76 0.881 0.99 Fuwa 5.9 7.6 9.3 111.3 14.0 117.5 |22.0 Forest P. Lab., . 5-7 7.6 110.0 12.9 16.1 119.8 Fuwa Ill.O Il3.3 16.0 19.5 25.0 133-5 50.0 Ford Foodstuffs White Bread Crackers Macaroni Flour Starch Gelatin Misc. Inorganu Material! Asbestos Fiber Silica Gel Domestic Activated Charcoal Sulfuric Acid Finely divided Steam activated HtSO* 0.5 4.5 6.2 8.5 lll.l 14.5 19.0 2.1 3.9 5.0 6.5 8.3 110.9 14.9 5.1 |l0.2 111.7 |l3.7 |l6.2 19.0 22.1 |l0.62.6 6.5 8.0 9.9 112.4 15.4 19.1 2.2 6.4 7.4 3.3 9.2 12.7 0.7 3.8 4.9 5.1 7.6 9.3 11.4 0.16 0.24 0.26 0.321 0.41 0.6! 0.73 0.841 5.7 0.20 9.8 112.7 |15.2 |l7.2 |18.8 |20.2 |21.5 |22.6 0.40 0.61 0.81 1.03 1.24 1.46 .67 1.81 Fuwa Selvig 7.1 14.3 22.8 1.2 28.3 29.2 30.0 31.1 2.7 Fuwa 33.0 41.0 47.5 152.5 57.0 61.5 67.0 73.5 2.5 Mason. Process and Product Air Conditioning 1155 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. 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. Control of Temperature for Close Machining Tolerances Where tolerances must be held within 2 or 3 ten-thousandths of an inch, a m the manufacture of precision instruments, tools, and high quality