CRANKCASE EXPLOSIONS: and their prevention

IT is frequently assumed, in all discussions on crankcase explosions, that (1) the oil and the air mixture in an engine crankcase is normally too rich to burn, and (2) piston blow‐by consists primarily of the products of combustion. In a paper read before the Fifth Annual Conference on Petroleum Mechanical Engineering, organised recently by the American Society of Mechanical Engineers, F. V. Cooke, Master Mechanic to the Service Pipe Line Co., U.S.A., maintained that these assumptions are fallacious. He went on to say that explosions result from ignited mixtures of vapour and air that fill spaces between the droplets of oily mist in the crankcases and that piston blow‐by is negligible except during the compression stroke.