Estimation of safety factors attributable to electrode materials in the spark test apparatus.
Proceedings of the 23rd International Conference of Safety in Mines Research Institutes, September 11-15, 1989, Washington, DC. Washington, DC: U.S. Bureau of Mines, OFR 27-89, 1989 Sep; :1191-1205
Underwriters laboratories UL 913, a national intrinsic safety standard, and U.S. Mine Safety and Health Administration (MSHA) testing procedures specify that tungsten and cadmium electrodes be used in the spark test apparatus when conducting intrinsic safety tests. However, tungsten and cadmium surfaces are rarely found in mining environments; therefore, sparking seldom occurs between these materials. Data that define the relative probability of spark ignition between more common materials may estimate the actual explosion hazard more precisely for realistic mining situations. The Bureau of Mines Pittsburgh Research Center is estimating the probability of spark ignition for common electrode materials such as aluminum, brass, copper, lead, tin, zinc, and stainless and cold- rolled steels in the standard spark test apparatus. By comparing currents that give the same probability of spark ignition at a given voltage or inductance, a safety factor may be associated with each material with cadmium assigned a safety factor of 1.00. Results to date are summarized.
Electrical safety; Electrical systems; Electrical equipment; Mine safety; Mining; Mining industry
OP; Conference/Symposia Proceedings
NTIS Accession No.
Proceedings of the 23rd International Conference of Safety in Mines Research Institutes, September 11-15, 1989, Washington, DC