Document 7Mqagyxp2y4y938Vdbg3eDwao

686 CHAPTER 50 1959 Guide Table 1 .... Temperatures and Humidities Applicable to industrial Air Conditioning--(Continued) Frocea I Temp. F | R-H.% Procsn j Temp. F tut.% PRECISION MACHINING room...................................................... Gasket storage....................................... Cement and glue storage...................... Precision parts machining................... Accurate gaging and inspection ........ Precision gage manufacture and ad justment .............................................. Precision gear drive assembly............. Watch main spring calibration........... Gage room............................................... Precision parts--honing.-.................... 75-80 75-80 100 65 75 75 68-75 72 76 78 75-80 45-50 35-40 50 40 45-50 45-60 45-50 42-50 45 50 35-45 For product improvement and increased personnel efficiency some manufacturing areas are being provided with summer air conditioning, where air conditioning is not provided, an ample supply of outdoor air and air motion are relied upon to provide acceptable working conditions. Low relative humidity is usually maintained to prevent cor rosion. Temperature control within a narrow range is more important than temperature maintained. Dust control is required wherever polishing operations occur. Air distribu tion is important to maintain constant conditions through out the area. Proc r*Mp. f IH.% PRINTING Pressroom: 75-80 Newspaper and other web printing.. Stock room: Multicolor offset lithography........... Binding,'cutting, drying, folding, and 5 to 8% above pressroom 'k same as pressroom 75-80 73-80 70-80 70-80 73-80 46-48 50-55 b 45-50 50 Lithography requires constant humidity control of entire pressroom with paper conditioned 5 to 8 percent higher rela tive humidity at start. All printing requires conditioned paper otherwise it will not lie flat, with 40 to 45 percent R.H. low limit to eliminate static electricity; and 60 percent R.H. high limit to prevent swelling of the rolls and slow ink drying. Tem perature is not criticalTbut extremes should be avoidea due to softening of the rolls at high temperature and improper ink distribution at low temperatures. Hoods must be provided for gas dryers, with solvent recov ery recommended for all except job shops. Exhaust system with dust collectors incorporated is required for type and plate cleaning areas. Check use of gasoline and other solvents. Nor mal air cleaning is adequate. Air distribution must prevent drafts on paperio storage or process. Gas flame dryers impose unusual loads. Air frompress and storage rooms should not be recirculated through office areas. rmp. F X.H.% REFRIGERATION EQUIPMENT Compressor Assembly........................... Refrigerator Assembly.......................... Testing........................... ................. 75 70 to 76 75 65 to 82 40 30 to 45 30 to 50 RUBBER DIPPED GOODS Dipping surgical articles..................... Storage prior to manufacture.............. Laboratory (AJ3TM Standard)............ 90 80 75-90 60-75 73.4 25-30 25-80 40-50 50 Solvents used in manufacturing processes are usually ex plosive and toxic, requiring positive ventilation. Volume manufacturers usually install a solvent recovery system._______________ TEA Packaging................................................ 65 65 Ideal moisture content is 5 to 6% for quality and weight. Low limit moisture content for quality is 4%. TEXTILES Cotton: Opening.................................... Picking................................................. Carding, Winter................................. Carding, Summer....... ............. or Carding, Summer.......................or Carding, Summer....... Drawing......................... Roving............................ Ring Spinning Conventional............ Long Draft................ Frame Spinning. Spooling and Warping. Weaving......................... Cloth Room.... ......... Combing......................... Linen: Carding................ Spinning......................... Weaving......................... Woolens: Pickers............. Carding............... ....... Spinning....................... Dressing......................... Weaving light goods.............. Overcoating (32 oz.). D rawing........................ . Worsteds: Carding......... Combing....................... Gilling........................... Top Storage................. Drawing........................ Cap Spinning.............. Spooling ana Winding Weaving........................ Finishing...................... Silk: Preparatory........... Weaving........................ Dressing....................... Spinning....................... Throwing...................... Rayon: Spinning............ Throwing...................... Weaving Regenerated............. Acetate............ ...... Spun rayon.............. 70-75 75 75-80 83 85 87 80 80 80-85 80-85 80-85 78-80 78-80 75 75 75-80 75-80 80 80-85 80-85 80-85 75-80 80-85 80-85 75 80-85 80-85 80-85 70-85 80-85 80-85 75 80-90 80 80 80 80 55-60 55-60 55 90 80 70 60 60 70 55 55-60 65 '70-85 65-70 50-65 60 60 80 60 65-70 50-60 60 60 60-65 50-60 65 65-70 65-70 75-80 65 50-55 65-70 55-70 60 60-65 60-70 60-65 65-70 60 50-60 55-60 50-65 "55-60 80 Process and Product Air Conditioning 687 Table 1-------Temperatures ond Humidities Applicable to Industrial Air Conditioning--(Concluded) Prec... Temp. F TEXTILES (Continued) RJf.% Rayon (Continued): Picking................................................. Carding, roving, drawing................. Knitting Viscose or cuprammonium............ Acetate............................................. Laboratory (A8TM).......................... 75-80 80-90 80-85 80-85 70 50-60 50-60 65 60 65 Rayon synthetic fiber processing: Viscose Preparatory..................................... Weaving............................................ Celanese Preparatory.............................. Weaving............................................ Nylon Preparatory..................................... Weaving............................................ 80 80 80 80 80 80 60 60 70 70-75 50-60 50-60 Cotton: Relative humidity maintained in ring spinning de pends on staple, twist, ana whether. leather aprons are used for conveying long draft stock. Aprons readily absorb moisture causing cotton to stick when relative humidity is above 55 per cent. With conventional 3 or 4 roll spinning, relative humidity may be as high as 70 percent dependent upon draft, twist, and staple. Relative humidity carried in cotton weaving depends upon construction of the doth. When automatic rmuhinew are to be tended and the warps are heavily sized, it may be as high as 90 percent. Woolen: In woolen spinning, the relative humidity main tained for mules is generally 55 percent, with conditions over frame spinning at 55 to 60 percent. Both types of spinning de pend on the class of stock spun, also the regain in the roving. Worsteds; Top storage temperature depends on whether cellar long period conditioning at low temperature or quick conditioning at high temperature is used. Weaving relative humidity depends upon staple, quality, and construction. Filtration of air is essential. Rayon manufacture: The steeping room, where sheets of raw material are dipped in caustic soda then broken into a fino matted crumb, is held at 70 F and 55 percent relative humidity. Relative humidity is held down to prevent condensation on cold pipes and jackets. In churn room, where sodium cellulose is converted into cel lulose xanthate, temperatures of 75 to 80 F are muintft.pH while humidity control is not important. Room temperatures are held below 85 F during the summer months. The crumb u dumped into aging tanks located in a room held at 73 F with no humidity control. For spinning operations it is desirable to limit the tempera ture to 90 F with a minimum relative humidity of 70 percent for the summer, while 70 percent and 75 F are desirable for the winter months. In the storage room, where the material is held for later recessing, design conditions are 85 F and 100 percent relative umidity. The material is washed, desulfurized, bleached, and then washed again. It is then placed in a drier where controlled con ditions of 100 deg and u5 percent relative humidity are re quired to bring the rayon back to the proper regain. In the coning room, where winding machines place the rayon yarn on cones, temperature is held at a mwirnmn of 80 F. Rela tive humidity is held at 55 percent. Process 7map. F TOBACCO Cigar and cigarette making................. Softening...;........................................... Stemming and stripping. ................... Packing and shipping............................ Filler tobacco casing and condition* Filler tobacco storage and prepare- Wrapper tobacco storage and conditioning................................................... 70 to 75 90 75 to 85 74 to 76 75 78 75 55 to 65 85 to 88 70 to 75 65 75 70 75 In preparation for stripping, the tobacco undergoes a soften ing operation, whereby it is automatically heated, moistened, and then cooled. Control of moisture regain, and of chemical and biological reactions is required in tobacco processing. Exact temperature and humidity conditions maintained are usually trade eecreta as they affect the finished product. {Text continued from p. 881.) Moisture Content and Regain In the manufacture or processing of hygroscopic materials such as textiles, paper, wood, leather, tobacco, and food stuffs, the temperature and relative humidity of the air have a marked influence upon the rate of production and upon the weight, strength, appearance, and general quality of the product. The moisture 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. This moisture content is known as regain. Standards of regain are fixed in the trade, and are the fundamental h*-<riq for the control of certain physical qualities of the material during manufacture. Manufacturing economy requires that the moisture con tent be maintained at a level favorable to rapid and satis factory manipulation, and to a minimum loss of material through breakage. A uniform condition is desirable in order that high-speed machinery may be adjusted perma nently for the desired production with a minimum loss from delays, wastage of raw material, and defective product. Moisture content refers to free moisture (as in a sponge) and 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 per centage of the bone-dry weight of material. For example, if a sample of cloth weighing 100.0 g is dried to a bone-dry weight of 93.0 g, the loss in weight, or 7.0 g, represents the weight of moisture originally contained. This expressed as a percentage of the total weight (100.0 g) gives the moisture content of 7 percent. The regain, which is.expressed as a percentage of the bone-dry weight, is (7.0/93.0) x 100 = 7.5 percent. The use of the term regain does not imply that the material as a whole has been completely dried out and hag re-absorbed moisture. A basis for calculating the regain of textiles is obtained by drying, under standard conditions, a sample from the lot, and the dry weight thus obtained is used in the calcula tions to determine the regain. Table 2 shows the regain or hygroscopic moisture content of several organic and inorganic materials when in equi librium at a dry-bulb temperature of 75 F and various