Marine Installation Manual
2022-03
1-18
1 Engine Summary
1.3 Fuel operating modes
X62DF-S2.0
Gas trip
A gas trip will always stop the use of gas as the fuel, this therefore always results
in a changeover to diesel mode. The gas trip is completed within a single revolu
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tion of the engine and can occur at any engine power and any operating mode
where gas is in use. This includes any point of transfer between operating modes.
While the engine runs in gas mode, the liquid fuel backup system is always on
standby with MGO or MDO. This is different to fuel sharing mode which is
backed up by the selected fuel type (see
).
Although the operator can initiate a gas trip to diesel mode, if the engine control
system initiates an automatic gas trip it is a result of either an unacceptable oper
-
ating condition, a detected failure or a command received from an external
system (e.g. the engine safety system). If an automatically initiated gas trip oc
-
curs, then the cause must be investigated. Transferring to an operation mode
with gas is therefore prohibited and disabled until the problem is resolved and the
alarm is reset.
Failures causing a gas trip are described in detail by the document that follows:
2-Stroke Dual-Fuel Safety Concept
Transfer
introducing gas
The transfer from diesel mode to either gas mode or fuel sharing mode introduces
gas fuel. Both the GVU and the iGPR must complete a system safety test before
this gradual changeover can take place.
Gas mode
The transfer to gas mode is prohibited (and therefore disabled) when the engine
is running on HFO. Before changing to gas mode, the engine must stop using
HFO and operate with MGO or MDO until the fuel system is fully flushed of
HFO. This ensures that the main fuel oil system (i.e. the liquid fuel backup
system, on standby with MGO or MDO) does not become clogged by HFO.
CSM or FSM
If the engine is running at approximately 10 % engine power (or above) for CSM
or at 50% engine power (or above) for FSM, the transfer to the selected mode
and operating within that mode is possible with HFO, MDO and MGO. When
the engine power is reduced below the mode’s operating range, an alarm message
is released. If the engine power is not increased within the required time period,
a gas trip is initiated.
Transfer
between liquid fuels
Similar to WinGD diesel engines, changing the fuel input from HFO to either
MGO or MDO and vice versa can be done at any time (assuming HFO is per
-
mitted in the operating mode) without interruption of engine operation. The fuel
oil transfers are managed by external systems.
NOTE
The fuel sharing mode must be contracted. It is an available option at
an additional cost.
