Marine Installation Manual 2021-08 1-12
1 Engine Summary
1.3 Fuel operating modes
X72DF
1.3.4 Changeover between operating modes
The changeover between operating modes is the process of the engine changing
between different fuel operating modes (see section 1.3,  1-6).
Depending on the type of changeover between operating modes, the time re-
quired will vary. Generally, a changeover of operation mode from gas to liquid
fuel is executed immediately. However, the introduction of gas will take a few
minutes depending on the operating modes.
All changeovers are restricted by the engine power availability of each operating
mode (see Figure 1-3,  1-6).
Transfers and gas trips
The changeover between operating modes can be categorised in two ways. If the
changeover introduces or continues to use gas fuel, it is called a transfer. If the
changeover between operation mode stops the use of gas fuel, therefore de-
faulting to diesel mode, then the changeover is called a gas trip (or just a trip).
Often a gas trip is associated with automatic initiation as part of a system safety
procedure, but it can also be internally initiated by the operator. In comparison
to a gas trip, the transfer between operating modes can only happen from oper-
ator initiation.
Figure 1-8 Fuel transfers and gas trips
Gas mode: No overload is available in gas mode, as the maximum continuous
output is 100% of rated power
Diesel mode: An overload of 110% is permitted in emergency conditions
(SOLAS Regulations II-1/3.6)
SM-0185
Fuel Sharing Mode
Gas Fuel
Operation
Diesel Only
Operation
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Gas Trip
T
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D
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Gas Mode
Diesel Mode
HFO MGO
MDO
GAS
MGO
MDOGAS
HFO MGO
MDO
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