Canister Concept Provides Early Fire Warning in Mines.
Marshall-MD; Thimons-ED; Kneebone-DW; Gross-SS
Min Cong J 1982 Apr; 68(4):64-69
Presently, many metal-nonmetal mines have fire-warning systems that make use of a stench gas, which is released from the surface into the compressed-air lines and/or ventilation air. Usually the stench gas is the volatile liquid ethyl mercaptan, mixed with either freon 11 or freon 22 to render it inert. Time delays for the stench gas to reach underground mine personnel and the uncertainty of effectively distributing the gas throughout the mine are disadvantages of these surface-release stench systems. To avoid these problems, MSA Research Corp. and the Bureau of Mines have developed a stench gas canister with a heat-fusible release for use in mine locations susceptible to fire. In the event of a fire near the canister, the heat-fusible alloy melts, releasing the gas into the ventilation air and warning all miners downstream of the fire. With appropriate detectors on the mine exhaust, the tracer gas can provide warning of a fire during off-duty shifts or when no mine personnel are downstream of the release.
Min. Cong. J., V. 68, No. 4, April 1982, PP. 64-69