Functions
Crankcase relief valve has mainly two functions
> To prevent the flames inside the crankcase from coming out and causing further damage
Working
As shown in the figure, the crankcase relief valve consists of a light spring that holds the valve closely against its seat. The whole arrangement is enclosed in a cover, which is tightly bolted from all the sides. The assembly is mounted on the door of the crankcase. On the outside of the valve a deflector is fitted which safeguards the personnel from escaping pressurized gases. On the inside of the engine, an oil wetted gaze acts as a flame trap to prevent any flame leaving the crankcase.
When the pressure inside the crankcase increases the valve raises compressing the spring. The excess pressure is released to the atmosphere. The Oil wetted Gauze assembly prevents the flame in the crankcase from escaping. The valve closes automatically under the tension and action of spring once the pressure reduces.