Renovated oil tank (2T05)
This tank contains renovated oil ready to be used as a replacement of the oil drained for separation.
7.3.2 System oil tank (2T01)
Recommended oil tank volume is stated in chapter Technical data.
The system oil tank is usually located beneath the engine foundation. The tank may not protrude under the
reduction gear or generator, and it must also be symmetrical in transverse direction under the engine. The
location must further be such that the lubricating oil is not cooled down below normal operating temperature.
Suction height is especially important with engine driven lubricating oil pump. Losses in strainers etc. add
to the geometric suction height. Maximum suction ability of the pump is stated in chapter Technical data.
The pipe connection between the engine oil sump and the system oil tank must be flexible to prevent
damages due to thermal expansion. The return pipes from the engine oil sump must end beneath the min-
imum oil level in the tank. Further on the return pipes must not be located in the same corner of the tank
as the suction pipe of the pump.
The suction pipe of the pump should have a trumpet shaped or conical inlet to minimise the pressure loss.
For the same reason the suction pipe shall be as short and straight as possible and have a sufficient dia-
meter. A pressure gauge shall be installed close to the inlet of the lubricating oil pump. The suction pipe
shall further be equipped with a non-return valve of flap type without spring. The non-return valve is partic-
ularly important with engine driven pump and it must be installed in such a position that self-closing is en-
sured.
Suction and return pipes of the separator must not be located close to each other in the tank.
The ventilation pipe from the system oil tank may not be combined with crankcase ventilation pipes.
It must be possible to raise the oil temperature in the tank after a long stop. In cold conditions it can be
necessary to have heating coils in the oil tank in order to ensure pumpability. The separator heater can
normally be used to raise the oil temperature once the oil is pumpable. Further heat can be transferred to
the oil from the preheated engine, provided that the oil viscosity and thus the power consumption of the
pre-lubricating oil pump does not exceed the capacity of the electric motor.
Fuel gas in the crankcase is soluble in very small portions into lubricating oil. Therefore, it is possible that
small amounts of fuel gas may be carried with lubricating oil into the DF-engine system oil tank and evap-
orate there in the free space above the oil level. Therefore, the system oil tank has to be of the closed-top
type. The DF-engine system oil tank has to be treated similarly to the gas pipe ventilation or crankcase
ventilation. Openings into open air from the system oil tank other than the breather pipe have to be either
closed or of a type that does not allow fuel gas to exit the tank (e.g. overflow pipe arrangement with water
lock). The system oil tank breathing pipes of engines located in the same engine room must not be combined.
The structure and the arrangement of the system oil tank may need to be approved by a Classification
Society project-specifically. Any instrumentation installed in the system oil tank has to be certified Ex ap-
paratus.
Product Guide Wärtsilä 34DF - 3/2012
75
Product Guide
7. Lubricating Oil System
