Starting air line safeties

>What is Starting air line explosion ? 

Starting air line explosion is one of the major cause of fire in main engine system .
For fire to happen  Heat , Fuel & Air is required .
       
 In an air starting system of Main Engine, fuel may be present in the form of  lube oil which carried over from the air        compressor. oxygen is present in the system in abundance . The heat source come from leaking starting air valve fitted on cylinder head. combination of these three in proper ratio will lead to an air line explosion .

> Precaution and Prevention :-
 
For precautions different safeties are fitted which are followings:-

• Relief Valve: It is fitted on the common air manifold which supplies air to the cylinder head. Normally fitted at the end of the manifold and it lifts the valve in the event of excess pressure inside the manifold. The advantage of relief valve is it will sit back after removing the excess pressure and thus continuous air is available to engine in case of manoeuvring or traffic.

•  Disc: It is fitted in the starting air pipe and consist of a perforated disc protected by a sheet of material which will burst in case of excessive pressure caused due to air line explosion. It also consist of a protective cap such constructed that if the engine is required to run even after the disc has been ruptured, the cap will cover the holes when it is turned. This will ensure that in manoeuvring or traffic air is available for engine at all time.

• Flame Arrestor: It is a small unit consisting of several tubes which will arrest any flame coming out of the cylinder through leaking start air valve. It is fitted on every cylinder before the start air valve. 

 > prevention of starting air line explosion :-

• Ensure that all the safety devices which are  fitted are working correctly.

• Draining of the air bottle  is done at every watch.

• Auto drain to be checked for proper functioning.

• Air compressor should be well maintained to avoid oil carry over.

• The oil separator  at discharge side  of the compressor is working efficiently.

• The starting air manifold pipe should be cleaned and check for paint deformation, it indicates overheating of the pipe.

• Starting air valve to be overhauled regularly to avoid leakage.
• Starting air valve seat to be inspected and lapped