KNF SC 920G - Page 41

Vacuum Pump System SC 920G Troubleshooting
Translation of original Operating Instructions, English, KNF 121308-121311 07/18 41
Vacuum pump system as a whole
Problem
Cause
Solution
Leaks in venting valve.
 Temporarily close the ventilation
connection (Fig. 2/6, p. 12). If this
stops the leak, leaks are present in
the venting valve. In this case:
 Flush the venting valve:
1. Close the gas inlet (Fig. 2/7).
2. If necessary for safety reasons:
Connect inert gas to ventilation
connection. Observe the safety
instructions in chapter 3.
3. Run the vacuum pump system at
100% pump capacity in evacuation
mode.
4. Re-open the gas inlet.
 If problem persists, contact KNF
Service.
Condensation in pump
head.
 Dry system with fresh air or, if
necessary for safety reasons, with
an inert gas:
1. Using inert gas: Connect inert gas
source with gas inlet (Fig. 2/7, p. 12)
and start system up in evacuation
mode (100% capacity). Observe the
safety instructions in chapter 3.
2. Using air: Open gas line (Fig. 2/7, p.
12) to the surrounding environment
and start system up in evacuation
mode (100% capacity).
3. Close the gas inlet after 30 seconds,
and leave the vacuum pump system
running for 30 seconds under
vacuum.
4. Repeat this process 3–5 times.
 If this problem occurs frequently,
place the vacuum pump system at a
higher level than the vacuum
chamber.
Gas outlet blocked on high-
performance condenser.
Risk of bursting of high-performance
condenser!
 Eliminate blocking of gas outlet.
Worn diaphragms or valve
plates.

Replace diaphragms and valve
plates (chapter 9.3).
Replaced diaphragms and
valve plates.

Check that the correct diaphragm
spacers are placed under the
diaphragms.
 If necessary, carefully tighten the
pump head fixing screws (Fig. 17/2,
p. 36) in diagonally opposite
sequence.
Pump not activated on
process start-up, in spite of
pressure decrease command.
Hand terminal or software
not connected to vacuum
pump system.
 Make connection.