System components:
Change over valve for leak fuel1V13Black start fuel oil pump unit1N13
Flexible pipe connections1HX0
Pipe connections:
Pilot fuel inlet112Leak fuel drain, clean fuel103Fuel inlet101
Pilot fuel outlet117Leak fuel drain, dirty fuel104Fuel outlet102
HFO pipes shall be properly insulated. If the viscosity of the fuel is 180 cSt/50°C or higher,
the pipes must be equipped with trace heating. It shall be possible to shut off the heating of
the pipes when operating on MDF (trace heating to be grouped logically).
Starting and stopping
In diesel mode operation, the engine can be started and stopped on HFO provided that the
engine and the fuel system are pre-heated to operating temperature. The fuel must be
continuously circulated also through a stopped engine in order to maintain the operating
temperature. Changeover to MDF for start and stop is not required.
Prior to overhaul or shutdown of the external system the engine fuel system shall be flushed
and filled with MDF.
Changeover from HFO to MDF
The control sequence and the equipment for changing fuel during operation must ensure a
smooth change in fuel temperature and viscosity. When MDF is fed through the HFO
feeder/booster unit, the volume in the system is sufficient to ensure a reasonably smooth
transfer.
When there are separate circulating pumps for MDF, then the fuel change should be performed
with the HFO feeder/booster unit before switching over to the MDF circulating pumps. As
mentioned earlier, sustained operation on MDF usually requires a fuel oil cooler. The viscosity
at the engine shall not drop below the minimum limit stated in chapter Technical data.
Number of engines in the same system
When the fuel feed unit serves a single Wärtsilä 46DF engine only, a feeder/booster unit (1N01)
shall be installed. On multiple installation of W46DF engines, it’s possible to install a single
feeder/booster unit (1N01) followed by one individual circulation pump before each W46DF
engine (1P12). It’s anyhow recommended to consider redundancy of feeder/booster unit (1N01)
for higher installation reliability.
In addition the following guidelines apply:
Twin screw vessels with two engines should have a separate fuel circuit for each propeller
shaft. Twin screw vessels with four engines should have the engines on the same shaft
connected to different fuel circuits. One engine from each shaft can be connected to the same
circuit.
Main engines and auxiliary engines should preferably have separate feeder/booster units
(1N01). Regardless of special arrangements it is not recommended to supply more than
maximum two main engines and two auxiliary engines, or one main engine and three auxiliary
engines from the same fuel feed unit. Pilot line of multiple W46DF engines can have a single
pilot fuel feed pump (1P13), at condition that any flow balancing distribution is prevented.
Feeder/booster unit (1N01)
A completely assembled feeder/booster unit can be supplied. This unit comprises the following
equipment:
DBAD209883 6-41
6. Fuel SystemWärtsilä 46DF Product Guide
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