The Importance Of Treating Marine Diesel Engine Fuel And Lube

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Marine diesel engines usually utilize heavy fuel oil (HFO) or marine diesel oil (MDO). Furthermore, lubricating oil is used for coating revolving parts to dissipate heat caused by friction. Both fuel and lube oil must be high quality and clean for efficient engines.

Contaminants and other impurities in either of these can compromise the function of the engine. It can also damage the system altogether. Thus, it is imperative to conduct proper treatment. 

Onboard treatment involves use of multiple pumps, coolers and heaters for maintenance of optimum pressure and temperature. It also requires different centrifuges and filters. Let’s have a brief look at these components.

Oil filters and screens
A good set of filters can help maintain clean supply of both fuel and lube oil. The bunkers where the fuel oil is stored are equipped with steam heating coils. Heating helps maintain the viscosity of fuel oil. Fuel oil is drawn from here through several medium and fine mesh screens, and then passed through the heaters to finally enter the centrifuges for further treatment. The circulating lube oil pump draws out the lube oil through a series of duplex filters. It is also passed to the centrifuge for filtration purposes.


Disc bowl centrifuges are the most common types used in marine engine. Heavy fuel oil is passed through multiple screens and a heater, before entering the centrifuge through the inlet pipe. 

Fresh water enters the centrifuge through a similar inlet and forms a seal to prevent outflow of oil.Spinning at high revolutions per minute, the centrifuge separates water and 

particles from the fuel oil. The liquid sludge and water is removed through the lower outlet into the sludge tank.

The clean oil is forced out from the upper outlet. It is piped to the day tanks through a transfer pump equipped with filters on suction and/ or discharge pipework. Fuel oil then finally proceeds towards the engine. 

Lube oil is treated the same way; however, it is taken from the main engine sump and is heated before it enters the centrifuge.
The cleaned lube oil is also transferred through discharge filters and sent to the main engine’s lube oil cooler. Here the lube oil is cooled using seawater. Finally, the cooled, filtered oil is returned to the engine sump under pressure through crankshaft and crosshead bearings, and engine guides.

Proper treatment requires efficient functioning of each individual component. Any failure or damage can compromise the whole treatment process.
It is therefore important to keep all the parts updated. We supply marine main engine parts, purifiers, other component spare parts and marine spare parts service for proper maintenance and function.

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