Document k6QGdK0n3oBaXor4BBpX8R1bJ

American Society of Heating and Ventilating Engineers Guide, 1929 Table 2. Drying Time and Conditions for Representative Materials Kind and Thickness or Material Temfehatube Deo. Fahr. Drtino Time Bedding................................................. ....................... ................ Cereals........................i-- --.............. ~...................... -........... Cocoanut--........................--IV...............'......... .'............ v............ Coffee.__i-_______ __ --................................................................ Cores, Oil Sand, for molding..................Yl in. - 1 in. thick Black sand with Goulac Binder . | in " : about 6/10 of time for oil sand cores 16 in " Feathers.._________________--.................................................. Films, Photographic............................... ................... ................. Fruits and Vegetables;--;...................................... ,................... Furs..;------------------------ ;...................-a--...........-........................ Glue i--.-............................................. .................... -a--;.............. Glue Size on Furniture............................................. ................. Gut........ ................................ ..................................................... -- Gypsum Wall Board...............................................{tinSh^* Gypsum Blocks....... ,.......................................................... -........ Hair Goods.................................................................................... Hats, Felt..................................... ................................................ Hops...... ............................................................................ -.......----Hides, Thin leather.................. '................--.......................... Ink, Printing...........................................................V-.i.-............................ Knitted Fabrics.............. V.................... ....................... ----.......... Leather, Thick Sole--............................................................... Lumber, Green Hardwood......................................................... Lumber, Green Softwood...;...:----............................................ Macaroni_________ ______ ......................................................... Matches.... ..................................................................................... Milk and other Liquid Foods (Spray Dried)....... ........... --. Molds, Green Sand-, C. I. Flasks (one Surface only exposed) 8 in. thick........................................................ 13 in. " .............. ;........................................ Nuts._....................................................................... Paper, Glued........................................................... Paper, Treated...;--.............................................. Rubber--....... ......................................................... Sand, loose, 1 in. deep.......................... ................ Shade Cloth......... ....................... ........................... Soap-- ............................... ;......,......;............... Starch.____.................. ;........... .--.............. --........... Stock Feed, Mixed--....... .................................... Sugar........... ............................................................ Tannin and other chemicals (Spray . Dried)----Terra Cotta (air-drying in conditioning room). Wall Board......................................... ................... 150-190 110-150 145-155 160-180 300 480 480 700 150-180 a 90 140 110 70-90 130 150 350 190 350-190 150-190 140-180 120-180 90 70-300 140-180 90 100-180 160-220 90-110 140-180 250-300 4--6 Hours 24 30 Minutes `lYl Hours AUC " 2-6 " 2-4 4 60 Minutes 8-16 Hours 1 Hour 2-4 Hours 4-6 " 3--180 Days 2-14 Instantaneous ' 600 700 75-140 130-300 140-200 80-90 300 240 125 180-200 180-220 150-200 250-300 150-220 200^250 6 Hours 13 24 6-12 10-15 Minutes 1--2 Hours 12 1-4 20-30 Minutes 20-30 Instantaneous 12-96 Hours 12-24 " 458 Chapter XXXI--Methods of Drying labor and loss of time. Fire resistance of doors is also important, in case of outside exposure to fiie'risks. Insurance rates must be considered in their relation to fire protective arrangements such as automatic sprinklers, fire doors and walls, steam jets for use in smothering fires that may start inside the dryer, etc. Ceilings of dryers should be as flat as possible and the space between the material and the walls and ceiling should be held to a minimum. .A factor often overlooked is suitable provision for ventilation of the space around the dryer openings so that warm moist air which may escape from the dryer when the doors are opened may be carried away before it has a chance to condense on the ceiling or windows of the building in which the dryer is located or into which it opens. Convenient arrangements for the operator should also be provided where tests can be made, records kept, and clothes changed, in case it is neces sary for the operator to work inside the dryer. SPECIAL PROBLEMS Practically every problem in air processing and drying presents its individual considerations which affect the over-all efficiency of the final installation. The peculiarities of the material to be dried, the allowable temperature and humidities, the most efficient means of handling the material, the speed with which the process must be effected, and the mechanical or physical limitations imposed by the plant conditions them selves are all factors' which must be carefully considered in the design of air processing and.drying equipment. The selection of the type and size of dryer, the method of heat supply, the method of moisture removal, the location and layout of the equip ment with reference to handling the material to best advantage, are prob lems which may require a different solution for each installation. Engi neers who specialize in the design of drying equipment have found it best to treat each case individually and develop a design and arrangement that will most nearly meet the specific requirements on the basis of research and experience. Drying is an extraordinarily interesting problem in engineering, and thousands of the products that are in common use every day go through some sort of.drying process during their manufacture. Wood when dried becomes 'a workable and dependable material, the leather used in shoes must submit to the drying operation, and the manner of its drying determines its value in the finished product. Clay when dried becomes ceramic ware, flour mixed with water when dried becomes macaroni, wood pulp dried becomes paper and gelatine dried and sensitized becomes photographic film. All textiles require the drying process at some time during their manufacture so that it is easy to see why the handling of each is a special problem. REFERENCES The American Society of Heating and Ventilating Engineers Transactions, Vol. 22, p. 479, Commercial Drying Apparatus, L. P. Dwyer; Vol. 23, p. 231, Artificial Drying with Special Reference to the Use of Gas, G. C. Shadwell; p. 255, Drying By Evaporation, F. R. Still; p. 265, Drying in Industrial Plants, J. G. Ross; pp. 339, 511, 529, 537, 545, Food Drying; Vol. 24, p. 7, High Temperature Drying, Burt S. Harrison; 459