2. Turn adjusting nut
1
to loosen the tension on the belts until they can be removed from the pul‐
ley.
3. Install the new set of belts and use the adjusting nut
1
to adjust tension until the marker pin
reaches the lower end of the elongated hole.
4. Tighten the locking nut
2
.
10.10 Testing the pressure relief valve
In order to check the pressure relief valve, the machine's working pressure is raised above the
blowoff pressure of the valve.
The controller is switched to pressure relief valve checking mode to carry out this check. This
checking mode is intended for machines with maximum permissible working pressure less than
15 bar. Pressure relief valves in machines with permissible working pressures higher than 15 bar
must be removed from the machine and tested on a special rig.
Blow off protection and air system pressure monitoring are switched off during the test.
➤ Never operate the machine without correctly functioning pressure relief valves.
➤ Relief valves on machines with maximum permissible working pressure of 15 bar should
be tested only by KAESER Service.
The machine must be isolated from the compressed air network and completely vented be‐
fore undertaking any work on the pressure system.
Preparation for the test
Precondition The machine is switched off.
1. Close the user's shut-off valve between the machine and the air distribution network.
2. Read off the activating pressure on the valve.
(the activating pressure is usually to be found at the end of the part identification)
3. Scroll to parameter 3 "Pressure relief valve check mode" with the arrow keys and confirm by
depressing the «Enter» key for at least three seconds.
4. Enter the password "“BASIC" and confirm with the «Enter» key.
5. Use the arrow keys to select parameter "on" and confirm.
Carrying out the check
The machine starts in IDLE as soon as it is switched on.
As long as the «ON» key is depressed and held, the machine will run in LOAD operating mode and
pressure builds up in the oil separator tank. As soon as the «ON» key is released, the machine
switches back to IDLE and switches automatically to STANDSTILL when the idling period has
elapsed.
Precondition The machine is switched off.
10 Maintenance
10.10 Testing the pressure relief valve
68
Service Manual Screw Compressor
ASK T SIGMA CONTROL BASIC
9_5717 20 E
