Atlas Copco PNS 1250 Cud S3A/T3 APP, Instruction Manual

Page: 27 / 114

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3.5.3 Fuel system
Description
In case of internal fuel supply, fuel from the fuel tanks
(FT) is circulated by the engine fuel pump (FP
E
). The
fuel is pumped through a 3-way valve (TWV) to two
primary coarse fuel filters (FF
PC
).
The fuel then passes through the secondary fuel filters
(FF
SE
) and enters the engine (E).
The fuel, which is not used by the engine to combust,
returns via the air-cooled fuel cooler (FC) and the 3-
way valve to the fuel tanks.
Normally the primary fuel filters are in parallel. By
means of the fuel shut-off cock (FSC), seated on the
housing of the filters, one of the filters can be shut off
when it has to be serviced. This can even be done
while the engine is running.
An electrical priming pump (EPP) is comprised in the
system to fill up filters and fuel lines after
maintenance and servicing. A description of this
procedure can be found on page 61.
Instead of internal fuel supply via the fuel tanks,
external fuel supply is possible.
When using external fuel, both the supply and the
return hose must be connected to the external fuel
supply couplings (EFC).
No restrictions are allowed in those hoses.
Take the necessary precautions to keep the fuel return
hose opened and connected, while the unit is running.
Check that the primary fuel filters are not both shut
off.
Restart the unit.
Do not put the fuel shut-off cock in
the lowered position (the handle
pointer points up) when the engine
is running, because both filters will
be shut off and no fuel will flow to
the engine.
!
The unit must be stopped before
switching from the internal to an
external fuel source.
!