Explosions in Enclosed Crankcases of Reciprocating Engines: Their Cause, Effect, and Possible Remedy

Abstract

In this paper is treated the important problem of crankcase explosion prevention in practice. After dealing with the cause of such explosions the author concludes that, whilst much can be done to minimize explosions, to prevent them altogether is not practicable. The merits of ventilation of crankcases are discussed and ways are suggested to prevent bearings running hot, while means to detect a temperature rise in inaccessible bearings and pistons are described. Tests carried out with the object of preventing injury to personnel and damage to property in the event of an explosion are described. A relief valve which opens and closes instantly is described and illustrated. The danger of burning gases issuing from relief valves is discussed, and the experiments are described which resulted in the evolution of a simple but effective flame trap. Relevant particulars are given of a Diesel engine in which two crankcase explosions took place, one before and one after a relief valve was fitted. The gas pressure in the crankcase when damage resulted is estimated and views are expressed regarding the relation of crankcase cubic contents to the area of relief devices.