Document 5kbV6gEbRNOqq81Q0m78BYmjz

980 CHAPTER 45 1953 Guide Air Conditioning Requireinients for Workers in Factories, by H. A. Mosher {Heat ing. Piving and Air Conditioning, August, 1946,.p. 82). Hot Weather Limits Hard Work. (Brief summary of investigation done for Army Quartermaster Corps, by Department of Physiology, Medical School,-University of Indiana. Heating and Ventilating, August, 1947, -p. 110). Methods'Used in Determining .the Health Hazards Arising from the Inhalation of Various Chemicals, by FVancis F. Heyroth (A.S.H.V.E.-Transactions, Vol.53,1947, p. 113). Air Recirculation from Exhaust Systems, by John M. Kane {Heating and Ventilat ing, April, 1947,lp.,75). Should Air Be Recirculated from Industrial Exhaust Systems? by Allen D. Brandt (Heating, Piping and Air Conditioning', August, 1947, p. 69). _ Dehumidification Methods and Applications, by John Everetts, Jr. (A.S.H.V.E. Transactions, Vol. 53,1947,.p. 91). Rating Dynamic Dehumidification Equipment; by E. R. Queer and E. R. McLaughlin (A.S:H.V.E. Transactions, Vol. 53,1947, p. 101). I i i ! I i I .* i I ; !- CHAPTER 46 INDUSTRIAL -EXHAUST SYSTEMS Elements of Exhaust Systems, Hoods or Enclosures, Capture Velocities, Air Volume, Duct System Design, Calculations, Construction of. System, Materials, Details, Air. Flow Producing Equipment, Air Cleaning' Equipment, Make-Up. Air, Maintenance of Performance, Materials for Corrosion Resistance : IN industrial plants, some type of exhaust system designed to collect and remove dusts, fumes, mists, vapors, and gases is installed to protect health and safety of industrial personnel, promote worker '.efficiency, salvageUsable material, or improve plant housekeeping. This chapter will not include consideration of systems similar in design, but used to convey heavy loadings (100 or more grains per cu ft) of materials. Definitions of various air con taminants, their particle "sizes, maximum allowable concentrations, and upper and lower explosion limits are included in Chapter 8, Air Con taminants. 1 ;` : Exhaust systems are extensively used for control of contaminants from: 1. Mechanical cutting and abrading operations including abrasive blasting and rock cutting. 2. Fuel burning and exhaust gas producing operations. 3. Molten materials handling operations. 4. Welding, burning, and soldering operations. 5. Fibre handling operations. 6. Volatile and gaseous material handling operations. 7. Chemical processes. '. Local exhaust systems should be considered whenever possible rather' than general ventilation methods which allow contaminants to be dispersed within the workroom: More positive control, great reduction in exhaust volume handled, and reduced cost of air cleaning equipment will result. ELEMENTS OF EXHAUST SYSTEMS An exhaust system will consist of (1) hoods or enclosures at all sources of air' contamination, (2) branch and main ducts through which an air stream trans-' ports the contaminant to air cleaning device or to the outside atmosphere, (3) air moving equipment to produce required air flow into hoods or en closures, and (4) air cleaning equipment when required., See Chapter 34, Part II, for discussion of types, applications, and principles of operation., HOODS OR ENCLOSURES1 "9 Basically, hood design requires sufficient knowledge of a process or opera tion so the most effective hood or enclosure can be installed to provide mini mum exhaust volumes for effective contaminant control. The more com plete the enclosure, the more economical and effective will be the installation. Many designers develop their hoods by mentally enclosing the operation completely and then providing access and working, openings as indicated. From this complete enclosure concept are developed the familiar.hood shapes like booths, side or downdraft hoods (with. or without side shields). All 981