Crankcase Explosions: An Investigation into Some Factors Governing the Selection of Protective Devices

Abstract

Remedies which have been suggested for crankcase explosions include the use of warning devices to detect over-heating in the crankcase, and the provision of relief vents to limit the explosion pressure to a safe value. Data were obtained experimentally at the Thornton Research Centre for the conditions necessary for the ignition of mists of lubricating oil in air in order that the margin of safety offered by a detector of overheating might be more fully assessed. The venting of explosions was also studied both on a rig scale and in the crankcase of a Diesel engine of 1,100 h.p. The results indicated that it would not be practical to provide sufficient venting area on an engine of this size, to limit the maximum explosion pressures to a safe value for the more violent explosions which might occur. For venting to provide complete protection, it would seem necessary to take measures to prevent the flame from spreading throughout the whole crankcase.