What Arrangements are Made to Locate the Lube Oil Pump Suction in the Sump


Dear Expert, 

I read the interesting incident of expansion tank low level, lube oil emulsion, no 3 Piston seizure etc.

Here is my question.

What arrangements are made to locate the lube oil pump suction in the sump (believe some ten inches high from sump bottom) & the type of strainer used? Also, which type of filters should not be used to avoid Removal of additives.

Mfame Expert Reply:

Good day to you Engineer!

Nice to note that you follow MFAME on a regular basis. Here is my 2 cents…

In a marine Two stroke slow speed Engines, the Strainers are used in the suction side of the pump (usually in the low pressure side). Suction strainers are mostly Bucket type strainers which does the function of coarse filtration. Basically this strainers are furnished to avoid any bigger particles get sucked. Apart from the strainers, fine filters will also be provided in the Lube oil line.

The suction will be few inches higher than the bottom of the sump. Height Primarily depends on the Sump size (spec of the Engine, as bigger engines of higher BHP/KW will have bigger sump). Usually sufficient height is furnished to ensure that the settled heavy particles / deposits at the bottom are not taken for suction. As we know the bottom deposits are cleaned during major overhaul of the Engines.

Furthermore, additives cannot be removed by any filters. Filters does the job of removing hard particles or dirts that can clinch to the surface while the fluid is allowed to pass through it (primarily due to micron sizes). On other hand, additives are blended with Base oils as per the formulation and it remains as an integral part of the base oil. Additives usually deplete due to various reasons which includes effects of by products of combustion (in neutralizing the sulfuric acid produced) etc.

Hope the above clarifies.

Mfame Expert

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