| Abstract | A brief sketch is given of the history and problems of the ignition of agricultural dust clouds by mechanical sparks. It is shown that there is a known hazard from large, hot bodies, and also from pyrophoric sparks, but that the intermediate situation of "ordinary" mechanical sparking is relatively unknown. A sketch is given of the chronological development of tests made by the author, which finally led to securing ignition of a grain dust cloud of 3% concentration by a mechanical spark, having an input energy of 425 foot-pounds, using as the striker a magnesium/aluminum alloy A280 (90% Mg., 10%Al.) and as the anvil a rusted steel boiler plate. It is suggested that more study should be given to this problem. |
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