Document 4vQ2ngzymDoY4N8Yk2zjb3Rqx

HEATING VENTILATING AIR CONDITIONING GUIDE 1943 Table 2. Regain of Hygroscopic Materials Moisture Content Expressed in Per Cent of Dry Weight of the Substance at Various Relative Humidities--Temperature, 75 F ClassiriCATION Matesial Description Relative Humiditt--Peb Cent Authohitt 10 20 30 40 SO 60 70 80 90 Cotton Sea island--roving 2.5 3.7 4.6 S3 6.6 7.9 93 113 14.1 Hartshorne Cotton American-- cloth 2.6 3.7 4.4 5.2 5.9 63 8.1 10.0 143 Sehloeslng Cotton Absorbent 4.8 9.0 1?.5 15.7 183 20.8 223 243, 253 Fuwa Natural Textile Fibers Wool Silk . Linen Australian merino--skein 4.7 7.0 8.9 108 123 14.9 173 19.9 23.4 Hartshorne Raw chevennes--skein 3.2 5.5 6.9 8.0 8.9 10.2 11.9 143 18.8 Schloeeing 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 63 73 8.1 8.9 9.8 11.2 13.8 Somme- Jate Hemp Avenge of several grades 3.1 5.2 6:9 83 10.2 123 14.4 17.1 20.2 Storch t.iManila and steal--rope 2.7 6.0 7.2 83 9.9 11.6 13.6 15.7 Fuwa Rayons, Viscose NitrooeQuioee Capramonium Average skein - CeUaloes Acetate Fibre 4.0 5,7 63 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 3Jr 4.0 4.7 53 6.1 7.2 8.7 10.6 U. S. B. of S. H. M. F. Writing Wood pulp--3% ash 3.0 4.2 53 6.2 7.2 83 9.9 11.9 14.2 U. S. B. of S. Paper White Bond Com. Ledger Kraft Wrapping Rag--1% ash 75% rag--1% ash Coniferous 2.4 3.7 4.7 53 63 73 83 10.8 133 IT. 8. B. of S. u. a3:2 4.2 5.0 5.6 6.2 6.9 8.1 103 13.9 B. of S. a a3 4.6 5.7 6.6 7.6 8.9 105 12.6 14.9 U. B. of S. Leather Sole oak--tanned 'S.0 8.5 113 13.6 16.0 183 20.6 24.0 293 Phelps Catgut Racquet strings '4.6 7.2 8.6 102 12.0 143 173 193 21.7 Fuwa Glue * Mise;^ OtgafflC Rubber . Materials Wood Hide Solid tire Timber (average) 3.4 4.8 5.8 6.6 7.6 9.0 107 113 123 Fuwa an 0.21 032 0.44 034 066 0.76 0.88 0.99 Fuwa 3.0` 4.4 5.9 7.6 93 113 14.0 173 22.0 Forest P. Lab. Soap White 1.9 3.8 ,5.7 7.6 10.0 12.9 16.1 19.8 233 Fuwa Tobacco. Cigarette 5.4 8.6 11.0 133 16.0 193. 25.0 333 50.0 Ford Foodstaffs White Bread Crackers Macaroni Flour Starch 03 1.7 33 43 63 83 11.1 143 19.0 Atkinson . H2.1 23 3.9 5.0 63 83 109 14.9 Atkinson 5.1 7.4 8.8 10.2 11.7 13.7 163 19.0 22.1 Atkinson 2.6 4.1 S3 63 8.0 9.9 12.4 15.4 19.1 Bailey 2.2 .3.8 5.2 6.4 7.4 83. 93 10.6 12.7 Atkinson Gelatin 0.7 1.6 2.8 33 4.9 6.1 7.6 93 11.4 Atkinson Asbestos Fiber Finely divided 0.16 0.24 0.26 032 041 031 0.62 073 0.84 Fuwa Silica Gel Misc. Inorganic Domestic Cob . Materials Activated Charcoal Steam activated Sulphuric Add StSOi 5.7 9.8 12.7 15.2 17.2 183 203 213 22.6 Fuwa 0.20 0.40 0.61 0.81 1.03 1.24 1.46 1.67 139 Selvig 7.1 163 22.8 263. 283 293. 30.6 3L1 32.7 Fuwa 33.0 41.0 47.5 523 57.0 613 67.0 733 823 Mason 724 CHAPTER 39. INDUSTRIAL AIR CONDITIONING content of materials having a vegetable or animal origin, and to a lesser extent minerals in certain forms, comes to equilibrium with the moisture of the surrounding air. In industries where the physical properties of a product affect its value, the percentage of moisture is of special importance. With increase in moisture content,' hygroscopic materials ordinarily become softer and more pliable. Standards of regain are firmly fixed in trade with fair penalties for excesses. Deficiencies result in loss of revenue to seller and loss of desirable quality to buyer. Manufacturing economy therefore requires that the moisture content be maintained at a percentage favorable to rapid and satisfactory manipu lation and to a minimum loss of material through breakage. A uniform condition is desirable in order that high speed machinery may be adjusted permanently for the desired production with a minimum loss from delays, wastage of. raw material and defective product. In the processing of hygroscopic materials, it is usually necessary to secure a final moisture content suitable for the goods as shipped. Where the goods are sold by weight, it is proper that they contain a normal or standard moisture content. Moisture Content .and Regain The terms moisture content and regain refer to the amount of moisture in hygroscopic materials. Moisture content is the more general term and refers either to free moisture (as in a sponge) or to hygroscopic moisture (which varies with atmospheric conditions). It is usually expressed as a percentage of the total weight of material. Regain is more specific and refers only to hygroscopic moisture. It is expressed as a percentage of the bone-dry weight of material. For example, if a sample of cloth weighing 100.0 grains is dried to a bone-dry weight of 93.0 grains, the loss in weight, or- 7.0 grains, represents the weight of moisture originally contained. This expressed as. a percentage of the total weight (100.0 grains) gives the moisture content or 7 per cent. The regain, which is expressed as a per centage of the bone-dry weight, is 7.0 93.0 or 7.5 per cent. The use of the term regain does not imply that the material as a whole has been completely dried out and has re-absorbed moisture. During the processing of certain textiles, for instance, complete drying during manu facturing is avoided as it might appreciably reduce the ability of the material to re-absorb moisture. A basis for calcularing the regain of. textiles is obtained by drying, under standard conditions a sample from the .lot and the dry weight thus obtained is used as a basis in the calcu lations to determine the regain. The moisture content of an hygroscopic material at any time depends upon the nature of the material and upon the temperature and especially the relative humidity of the air to which it has been exposed. Not only do different materials acquire various percentages of moisture after prolonged exposure to a given atmosphere, but the rate of absorption or drying varies with the nature of the material, its thickness and density. Table 2 shows the regain or hygroscopic moisture content of several' 725