Internal combustion engine procedure :
The fuel oil system for a diesel engine can be considered in two
parts—the fuel supply and the fuel injection systems. Fuel supply deals with
the provision of fuel oil suitable for use by the injection system.
Fuel oil supply for a two-stroke diesel engine
A slow-speed two-stroke diesel is usually arranged to operate continuously
on heavy fuel and have available a diesel oil supply for
In the system shown in Figure , the oil is stored in tanks in the
double bottom from which it is pumped to a settling tank and heated.
After passing through centrifuges the cleaned, heated oil is pumped to a
daily service tank. From the daily service tank the oil flows through a
three-way valve to a mixing tank. A flow meter is fitted into the system to
indicate fuel consumption. Booster pumps are used to pump the oil
through heaters and a viscosity regulator to the engine-driven fuel
pumps. The fuel pumps will discharge high-pressure fuel to their
The viscosity regulator controls the fuel oil temperature in order to
provide the correct viscosity for combustion. A pressure regulating valve
ensures a constant-pressure supply to the engine-driven pumps, and a
pre-warming bypass is used to heat up the fuel before starting the
A diesel oil daily service tank may be installed and is connected
to the system via a three-way valve. The engine can be started up and
manoeuvred on diesel oil or even a blend of diesel and heavy fuel oil.
The mixing tank is used to collect recirculated oil and also acts as a
buffer or reserve tank as it will supply fuel when the daily service tank is
The system includes various safety devices such as low-level alarms
and remotely operated tank outlet valves which can be closed in the
event of a fire.
Operation on Heavy Fuel Oil
Main engines designed to manoeuvre on heavy fuel oil are to be operated according to the manufacturer’s instructions. All other types of main engines are to be manoeuvred on diesel oil according to the manufacturers’ instructions.
In the event of problems during manoeuvring on engines using heavy oil there must be no hesitation in changing over to diesel oil irrespective of whether the engines are being operated using bridge control, or using engine room control.
It is the Chief Engineer's responsibility to inform the Master of the particular engine type’s maximum period that it can safely remain in the stopped position. He is also to inform the Master of the procedures which will have to be carried out if the particular engine type’s maximum period at standstill during manoeuvring is exceeded.
The function of the fuel injection system is to provide the right amount
of fuel at the right moment and in a suitable condition for the
combustion process. There must therefore be some form of measured
fuel supply, a means of timing the delivery and the atomisation of the
fuel. The injection of the fuel is achieved by the location of cams on a
camshaft. This camshaft rotates at engine speed for a two-stroke engine
and at half engine speed for a four-stroke. There are two basic systems
in use, each of which employs a combination of mechanical and
hydraulic operations. The most common system is the jerk pump; the
other is the common rail.
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