Operation of explosion relief valve of a marine diesel engine
The diesel engine is a type of internal combustion engine which ignites
the fuel by injecting it into hot, high-pressure air in a combustion
chamber. In common with all internal combustion engines the diesel
engine operates with a fixed sequence of events, which may be achieved
either in four strokes or two, a stroke being the travel of the piston
between its extreme points. Each stroke is accomplished in half a
revolution of the crankshaft.
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. A light spring holds the valve closed against its seat and a seal ring completes the joint.
A deflector is fitted on the outside of the engine to safeguard personnel
from the outflowing gases, and inside the engine, over the valve
opening, an oil wetted gauze acts as a flame trap to stop any flames
leaving the crankcase. After operation the valve will close automatically
under the action of the spring.
Machinery Spaces.com is about working principles, construction and operation of all the machinery
items in a ship intended primarily for engineers working on board and those who working ashore . For any remarks please