This article deals in the information regarding the scavenge space inspection done on the marine diesel engines and what importance it holds. Scavenge space, is the space in the 2 stroke diesel engines, which is used for the scavenge air, including the space below the piston. The air supplied by the auxiliary blowers or the turbocharger for the combustion comes here first and then goes to the combustion space.
During inspection apart from this space, engineer
will also check the condition of piston rings etc; we will discuss it in a more detailed manner in later discussion.
So, this becomes imperative to keep the check on this space by regular inspections, and frequency for it depends upon the practices that are being observed in the company.
Note: After the opening the scavenge space doors, it becomes necessary to keep the space ventilated and properly lit all the time. Also, make sure that you have removed everything out of the space like rags etc, after the inspection. That is why, you should count number of rags that you are taking
in, and so that in the end you are sure that you have taken out, all of them!!!
Scavenge Space Inspection-What to check
Here are some of the things, that a good engineer will like to check inside the scavenge space:
1) The soot deposits inside it. Over the time, the carbon soot from the combustion space will come out of the scavenge ports to this space. Thus it becomes necessary to remove them, to avoid the chances of fire.
2) The scavenge drains are not clogged.
3) Check the piston ring clearance by using the feeler gauges. And match with the previous records. Too much clearance, will lead the blow by, and gases will escape the other side of the piston, hence resulting in poor combustion.
4) Check the thickness of coating on piston rings. Generally you have device (electronic), to measure the thickness of this film.
5) Check the top land of the piston for any cracks or leaks from injector.
6) Check for liner condition, by taking photographs.
7) Check for excessive oil accumulation near the stuffing box area.
8) Check for any broken piston rings.
Scavenge Space Inspection Importance
As said earlier, this space is constantly supplied by the fresh air. Over the time, soot from the piston space will accumulate here, and thus posses the possible cause of the fire in the scavenge space. It is important to check the condition of piston rings for better compression and combustion quality. A broken piston ring, will not only affect the compression process, but will also damage the liner, and may siege the piston as well. Which, then becomes a very big job, costing much more money as compared to changing a piston ring.
These inspections will also give you the hint about the quality of combustions and the quality of fuel. More soot in the scavenge space means bad
oil and combustion. This inspection also gives the hint towards the decarb of that particular unit. If the condition of rinds and piston is good, then you can extent the duration of the next de-carb of the main engine to be done.
So this was all from this article on the scavenge space inspections, hope you enjoyed reading it.