Metal Finishing Guide Book


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finishing equipment & plant engineering SPRAY BOOTHS GLOBAL FINISHING SOLUTIONS, DALLAS, TEXAS Before learning the features, benefits, and uses for spray booths, it is important to know the basics that apply to all spray booths: the reasons for using a spray booth, what a spray booth can and cannot do, the various federal, state, and local agencies that give approval to a new spray booth installation, National Fire Protection Association Bulletin 33 (NFPA-33) as it relates to spray booth design and booth classifications, the difference between code compliance and environmental compliance, how to determine booth efficiency, and the most common types of spray booths and how they are used. The various codes and agencies that govern spray booth classification, installation and operation can be very confusing. Understanding the codes and how they apply to spray booths allows for identifying the most appropriate booth. The purpose of a spray booth is to confine the application of a hazardous material to a restricted controlled environment. Spray booths prevent hazardous overspray and volatiles from escaping confinement and causing fire or explosion hazard to nearby operations. They control the air-fuel mixture so that a combustible combination cannot occur. In addition, spray booths provide a clean environment in which to paint. REGULATION OF SPRAY BOOTHS The primary function of a paint spray booth is to reduce the likelihood of fires and explosions. A secondary consideration is protecting the operator from toxic materials. This protection is best done with respirators, protective clothing, and hoods. Spray booths cannot be designed to adequately protect the operator from overspray contamination. It is not unusual for part geometry to require the spray gun to be directed near the operator. A spray booth is not an emission control device even though some end users assume that a spray booth is an emission control device that must comply with Environmental Protection Agency (EPA) standards. EPA standards place limitations only on the amount of toxic material in the form of solvent vapor, known as volatile organic compounds (VOCs), entering the environment through the booth exhaust stack. A spray booth is designed to collect solid particulates only, not solvent vapors. To comply with EPA requirements, exhaust air may need to be treated with equipment installed outside the spray booth. A carbon adsorption system or an incineration system, for example, are acceptable methods for collecting VOCs. Traditional code inspections deal with the design of the spray booth. Inspectors evaluate hardware and installation methods for compliance with the Occupational Safety and Health Administration (OSHA) standards, National Fire Protection Association (NFPA) Bulletins 33 (Spray Applications) and 70 (National Electrical Code or NEC), and any local ordinances. A separate environmental quality review is conducted to determine the amount of pollutants the installation will emit. A new spray booth installation is approved or denied by the authority having jurisdiction. For example, in areas dealing with public and employee safety, the authority may be an official of a federal, state, or local agency. Or 769

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