Classification Of Dusts Relative To Electrical Equipment In Class II Hazardous Locations.
Commission on Engineering and Technical Systems, National Materials Advisory Board, National Research Council, National Academy of Sciences, Washington, D.C., 1982:51 pages
Classifications of combustible dusts in hazardous locations are reviewed. The rationale for classifications is presented. Four premises for classification are considered: the close relationship of the classification method to standards for selection and installation of electrical apparatus; the classification of dusts with extremely high fire or explosive potential is not encompassed; classification is permitted within easily determined parameters and allows for identification of dusts that present a fire hazard but not a serious explosive hazard; and the method must permit classification of plastic and chemical dusts as well as agricultural, carbonaceous, and metallic dusts. Consequences of the premises are explored. Dust classification methods are presented using the National Electrical Code (NEC) resistivity guidelines. A scheme for classification of dusts is illustrated which classifies dust into: oxidizers, explosives, and pyrophoric materials; noncombustible dusts; and combustible dusts with various ignition sensitivities that have either conductive or nonconductive resistivity. Maximum surface temperatures of electrical operating equipment for the various classes of dusts are tabulated. Test apparatus used to determine layer ignition temperature and resistivity, and methods for their determination are described. Dusts classified by the NEC are listed.
NIOSH-Contract; Contract-210-78-0120; Safety-research; Health-hazards; Environmental-exposure; Environmental-hazards; Air-quality-control; Air-sampling; Sampling-equipment; Air-conditioning; Pulmonary-function-tests;
NTIS Accession No.
Commission on Engineering and Technical Systems, National Materials Advisory Board, National Research Council, National Academy of Sciences, Washington, D.C., NTIS PB82-263-153, 51 pages, 2 references