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Fuel Oil Transfer System

After careful consideration of the requirements for an ocean capable motor yacht, where large fuel capacity is a major consideration and where vessel “trimming” would be performed during any long passage, we have considered prudent, in all except small trawlers of say less than 40ft, that a complete, ship like F.O. transfer system should be fitted. A robust system, that allows for fuel to be pumped between all tanks on board.

It would be impractical to expect that fuel being “bunkered” from unknown terminals would always meet recognized standards of cleanliness. With this in mind we have taken the necessary precautions to have in place facilities that will quickly mitigate any possible loss of essential systems due to contamination.

To facilitate ease of checking for contamination, all fuel tanks are fitted with “low” sludge draw off cocks enabling the worst heavy sludges to be identified and removed. From this it is important to start a fail safe cleaning process. We achieve this by incorporating day tanks in the fuel storage, one port and one starboard sized to accommodate the needs of all fuel consumers; engines and generator sets running at full demand for a minimum 24 hour period.

W48 DSTank

Fuel is pumped to the day tanks via a fuel transfer system that incorporates a patented filtration system. Typically we specify an RCI filter, this ensures that while contaminated fuel may remain on board, the fuel contained in the day tanks will always be clean.

These two tanks are connected by a cross main which incorporates a dual Separ fuel filter as a next step to ensuring fuel cleanliness. Engine manufacturers will never supply and engine without its own fuel filter; this is their precaution.

To this end, the system is fitted with two electric transfer pumps; one main pump and one standby. The transfer valves are arranged in the form of a suction manifold and a discharge manifold clearly labeled with each tank number.

As a safety factor and also a requirement for any vessel built to any recognized standard such as Lloyds, the transfer pumps have remote emergency shutdowns located outside the Engine Room space.

F.O. Valves & Piping

Each suction valve to a deep tank must have remote closing capability from outside the Engine Room. For all other tanks the suction valves should be fitted at the top of the tank.

Great care must always be taken with valves and piping to ensure that there can never be cross flow between tanks at any time. Cross flow between tanks can seriously affect the stability of the vessel.

All fuel piping systems should be of seamless steel, copper or stainless steel. Never use plastic or rubber piping anywhere in the system. Non metal fuel piping would not be accepted by Classification Societies except for short lengths of flexible hose at the engine fuel pump connection.

Filters & Strainers

Fuel supplies from many sources can contain water and other contaminants and fuel left in a tank for long can develop “diesel bug” which is a bacterial growth in the fuel. Diesel bug is rarely troublesome in vessels with high fuel turnover, i.e. in commercial vessels, but can build up in some trawlers and yacht fuel tanks.

Most of these contaminants can be eliminated by regularly draining them off through each tanks drain cock.

All diesel engines have built in fuel filters but it is prudent to fit separate filter/water traps between the daily service tank and the engine. These should be of the dual type where each filter can be replaced without stopping the engine. Strainers should also be fitted in the F.O. transfer pump suctions.

As we have observed before; fire and flooding are by far the greatest risk for an ocean going motor yacht. We place great importance on the durability of materials used within the engine room. For example, piping conveying fuels or seawater is always fabricated from stainless steel with no rubber flexible joints, which increase risk of failure and will ultimately disintegrate.

The first duty of the fuel transfer system is to draw fuel from the storage tanks to supply the daily service tanks (D.S.T.), and secondly to transfer fuel between storage tanks for vessel trimming purposes.

Fuel oil transfer station

As can be seen in the photo above the fuel transfer system is consolidated in one easy to operate position.

Fuel requirements can be drawn from either both or separate DST via duel Separ filters. The daily service tanks are sized to the minimum 24 hour demand of all consumers at full power. Each tank is fitted with sight gauges and low level alarm.

These tanks should always be filled manually and a close watch kept on the process as if left to fill automatically there is a risk that fuel may be pumped out via the deck vents. While we do fit high level alarms there is always the risk of failure so the process should become part of the daily engine room routine.

Last Updated (Saturday, 29 August 2020 03:29)