Kärcher HDS 9/50 De Tr1 Service Manual page 177

NOTE
In the frost protection mode flow is recognised, however,
no pressure. This is OK in this operating mode and does
not lead to a fault message!
The fault message "water shortage" is deactivated with the
operating mode.
The frost protection mode has a maximum work time of 5
minutes, then the motor is switched off automatically.
In case of a faulty operation that leads to a pressure build-
up, the following could happen:
the safety valve opens or
–
the control switches off the diesel engine, as flow and
–
pressure are synchronous. After 5 seconds, the error
message ERROR 5 occurs
NOTE
Following the descaling, a maintenance of the pump is rec-
ommended.
1 Water pipes
2 High pressure hose
 Disconnect the trigger gun from the high-pressure
hose.
 Connect the high-pressure hose to the frost protection
inlet.
 Disconnect the water hose from the water supply.
 Connect the water hose to the return flow of the frost
protection.
 Set the operating mode switch to the operating mode
"frost protection".
 With cold engine only:
To preheat the motor, turn the key switch to the left and
hold it until the indicator light preheating goes out.
 Turn key switch to position "I". The indicator lamp for
operational readiness lights up.
The control voltage is switch on and the display shows
the operating status "Antifreeze".
 Turn the key switch to the right until the motor is run-
ning.
 The descaling fluid is pumped in the circuit through the
device.
 Repeat the procedure 3-4 times, then rinse with clear
water and, if necessary, some brine; collect the desca-
ling fluid for later environmentally friendly disposal.
 The dissolved rejects are filtered in the filter of the water
inlet. Finally clean it.
NOTE
In order to dispose of the descaling water in an environ-
mentally friendly way, it may be necessary to neutralise it.
 Dilute the collected descaling water with approx. 10-
20 litres of water.
 Dip pH indication paper 6.768-006.0 into the descaling
water and determine the pH value.
 While constantly stirring, add sodium acetate (1 kg:
6.287-172.0) until a pH-value of approx. 7 is reached.
The test is done with the pH indicator paper again.
 After that, the descaling water can be disposed of via
the public sewer system.
English 5.906-736.0 Rev. 00 (07/15)
177