Operation
0270−1/A1
Winterthur Gas & Diesel Ltd.
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Change-over from Heavy Fuel Oil to Marine Diesel Oil and
Back
1. General
When you change from heavy fuel oil (HFO) to marine diesel oil (MDO) or back, you
must keep the thermal stresses of the related fuel components as low as possible.
Thermal stress occurs because of the large temperature changes. Too fast change of
the temperature can cause damage to the fuel pump plungers and can cause
leakages in the fuel pipes.
During the change−over procedure the temperature of the fuel must not change more
than 2_C each minute. This prevents damage to the system, specially when you do
the procedure frequently. The small change rate is also because of the large
difference of viscosity between HFO and MDO/MGO.
You can do a change−over of the fuel only when the engine is running. While the
engine has stopped, there is no fuel flow through the fuel rail. Change-over is thus not
possible.
2. Automatic Fuel Change−over
WinGD recommends the installation and use of an automatic fuel change−over
system to prevent problems during the change−over procedure.
If an automatic change−over system is installed, follow the instructions in the
documentation of the manufacturer and the instructions for cylinder lubricating oil in
paragraph 5.
3. Manual Fuel Change−over
When you do a manual change−over of the fuel, you must make sure that the
change-over is safe, see the paragraphs that follow.
Specially make sure that during the procedures HFO never can flow into the MDO
tank and pipe system.
Note: WinGD recommends to do a manual change−over only, if an automatic
change−over system is not installed or if the automatic change−over
system is unserviceable.
4. Recommended Viscosity at Inlet to Fuel Pumps
For the temperature necessary to make sure that the fuel upstream of the inlet to the
fuel pumps is at the correct viscosity, see Fig. 1 Viscosity / Temperature Diagram in
0710−1. The viscosity for MDO must not be less than 2 cSt.
A viscosimeter measures the viscosity and thus controls the temperature of the fuel.
Make sure that you monitor the viscosity and the temperature of the fuel.
Operation
2017−08
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