Exam Question

(a) Below is the drawing of a diesel engine air start system. The air compressor will compress air to about 30 bar and store it in large air bottles. When the air start valve in the start air bottle is opened, air will flow to the automatic valve.
When the start command is given to the engine, control air will open the automatic air start valve and the compressed air will flow to the start air manifold and start air distributor. The start air distributor will supply air to open the air start valve on the main engine whose piston has just passed TDC. The high-pressure compressed air from the manifold will flow into the cylinder, pushing the piston down. As the piston moves down, the other unit, which has just passed TDC, will open the air start valve and bring the engine to the revolutions required for starting the engine.
(b) Safety Devices and Interlocks in the Starting Air System
Flame Trap/Flame Arrestor: Prevents flames from entering the airlines and reaching the air bottles in case leaking air start valve