Crankcase Explosion Analysis

Causes of crankshaft explosion

1.       High temperature due to the reciprocating movement of the piston.
2.       Increase in bearing temperatures.
3.       Sparks entering the crankcase due to leaky piston rings or piston blow past.
4.       Reduction of flash point of lube oil.
5.       Friction between moving parts inside crankcase

crankcase broken
Bigend bearing broken

Massive damage inside the crankcase
Connection rod bended

Sequence of crankcase explosion

When hot spots temperature rises at 200 degree Celsius and lubrication oil splashed on it in the crankcase, the oil gets vaporised. When these vaporised particles travel to the cooler part of the crankcase they get condensed into a white mist which has oil particles properly dispensed in it. The droplet in the oil mist is very small -5 to 10 microns in diameter. The process that takes place is somewhat similar to atomization. This white mist when again travels to the hot spot area, can easily catch fire, which might also lead to an explosion. The fire or the explosion creates immense pressure and temperature (about 850 degree Celsius) inside the crankcase and if this pressure crosses the permissible limit, crankcase explosion takes place. The explosion will rupture the crankcase doors and even cause heavy damage to the inside of the engine.

How to prevent crankcase explosion

1.       Proper cooling of the engine and lube oil
2.       Check the temperature of main bearing
3.       Ensure proper lubrication of the engine
4.       Ensure proper purification of the engine
5.       Ensure schedule checking of the piston rings
6.       Check abnormal frictional noise inside crankcase
7.       Check the spring tension of the pressure relief valve
8.       Check Oil mist detector (OMD)
9.       Check the flame trap


Q:How OMD prevent crankcase explosion? 
 How a breather helps to prevent explosion?

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