Page 51 - Introduction to Marine Engineering

38 Diesel engines

Spindle
Packing piece

i____Spring

Valve

Figure 2.23 Cylinder relief valve

Explosion relief valve
As a practical safeguard against explosions which occur in a crankcase,
explosion relief valves or doors are fitted. These valves serve to relieve
excessive crankcase pressures and stop flames being emitted from the
crankcase. They must also be self closing to stop the return of
atmospheric air to the crankcase.
Various designs and arrangements of these valves exist where, on
large slow-speed diesels, two door type valves may be fitted to each
crankcase or, on a medium-speed diesel, one valve may be used. One
design of explosion relief valve is shown in Figure 2.24. A light spring