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.
