Komatsu WA600-8 Operation & Maintenance Manual page 221

OPERATION
DEF is supplied from DEF system into the exhaust system.
DEF system consist of DEF tank (1), DEF hose (2), DEF pump
(3), and DEF injector (4). SCR Ass'y is indicated by (5).
In the event that indications of potential degradation of nitrogen
oxides conversion efficiency are detected, the active regenera-
tion is triggered to rejuvenate Urea SCR system even if the
amount of soot accumulated in the KDPF has not reached to
the regeneration thresholds.
For details of Aftertreatment Devices Regeneration, see "HAN-
DLE Komatsu Diesel Particulate Filter (KDPF) (3-143)".
k k
Fill ONLY DEF into DEF tank. Foreign material in the DEF
system or urea deposits caused by evaporation may hin-
der operation of the devices.
NOTICE
• Do not disassemble any devices of the DEF System
other than the filter for change. Do not modify any de-
vices of the DEF System.
• Paint may cause deterioration of the devices. When
painting the surrounding areas, take care not to get
any paint on the injector and the supply pump.
• Always use DEF that conforms to the quality standard.
If any additional additive agents or water is mixed in
DEF and that mixture is used, the devices will not
function properly, and conformance to the exhaust gas
regulations will be lost. In addition, it may cause fail-
ures in the engine system. If DEF out of the standard
is filled or used by mistake, contact your Komatsu dis-
tributor.
About the operation of Urea SCR system
The Urea SCR System automatically starts operating as soon as the engine is started.
Even after the engine starting switch is turned to the OFF position, the devices will still be in operation for sever-
al minutes to purge any DEF in the lines, the injector and the supply pump back to the DEF tank. It does not
indicate any abnormality. When DEF has been returned to the tank, the devices stop.
Do not turn OFF the battery disconnect switch while the devices are still in operation. When the devices com-
plete their shutdown process, the system operating lamp will go out, and the battery disconnect switch may be
disconnected.
About the operation in cold weather
DEF freezes at –11 °C.
Urea SCR system is equipped with a heating system to thaw frozen DEF once it is frozen, for example, during
parking and to prevent DEF from freezing during operation.
In case DEF freezes during parking, once the engine starts running the heating system automatically starts pro-
viding heat to thaw frozen DEF. The pump and the injector start working only after a proper amount of DEF is
thawed. This may be noticed as a delay in the start of functioning of the pump and the injector.
The heating system is also activated automatically during operation to prevent DEF from freezing whenever the
ambient temperature drops below a certain threshold where DEF in the system may freeze. In the event that the
ambient temperature drops further than a temperature where the heating system is capable of maintaining fluidi-
ty of DEF, the DEF system automatically starts purging the remaining DEF back to the tank and stops pumping
WARNING
EXPLANATION OF COMPONENTS
3-153