Air Starting System

Question 1

1. With reference to a main engine air starting system:

a) List 5 important safety features fitted to the system.

Answer 1

a) Flame traps on each of the cylinder start air branch pipes.
A relief valve on the start air manifold.
A non-return valve between the start air manifold and the main start air valve. An automatic shut off when the correct revolutions are reached and fuel is put in the engine. Bursting discs on each of the cylinder air start branch pipes.

Question 2

1. With reference to a main engine air starting system:
   a) List 5 important safety features fitted to the system.
   b) State how a leaking air start valve may be detected.

Answer 2

b) The start air branch pipe local to the affected unit will become hot and may glow red

Question 3

3. With respect to two stage reciprocating compressors used for air start purposes: a) State 4 reasons for taking too long to fill the main starting air bottles.

Answer 3

a) There’s a leak in the system.
Blocked air inlet filters.
Worn liners or piston rings.
Incorrectly seated valves.

Question 3

1. With reference to a main engine air starting system:
   a) List 5 important safety features fitted to the system.
   b) State how a leaking air start valve may be detected.
   c) Briefly describe the dangers of allowing the condition mention in (b) persists.

Answer 3

c) If the leak is allowed to persist, hot exhaust gases could leak by and cause start air explosions in the manifold that will travel back to the air reservoir.

Question 4

3. With respect to two stage reciprocating compressors used for air start purposes: a) State 4 reasons for taking too long to fill the main starting air bottles. b) State 4 safety devices that may be fitted.

Answer 4

b) Bursting disk, safety valves on every branch of the air start manifold. Pressure relieving safety valves on intercoolers and after coolers. Safety valves on main air starting bottles.
Bursting diaphragm on air compressors cooling jacket.