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Pump Troubleshooting
In the event of a power failure (momentary or long period) the
controller is switched off. When power is restored, the controller will
automatically restart.
Tab. 3
SYMPTOM
1.
Slow starting (more than
30 minutes).
2.
Slow pump-down due to
absorption of vapours on
pump and system walls.
3.
Slow starting or slow
pump-down.
4.
Current higher than
expected at any given
pressure.
2
l/s Ion Pump
/ 87-900-091-01
POSSIBLE CAUSE
Air leaks which limit pressure to
above 10
mbar and cause longer
-6
starting time.
Vapours and gases admitted to a
system are absorbed on the walls of
the system and pump. Subsequent
reduction in pressure depends on
the rate of depletion of this vapour.
Heavy hydrocarbons are most
troublesome because of their
relative low vapour pressure and
are very difficult to remove, even by
baking.
High voltage feedthrough is leaking.
Ion pump leakage current causing
higher pressure reading.
(E)
Technical Information
Pump Troubleshooting
CORRECTION PROCEDURE
Leak check the vacuum system
with a helium leak detector.
Heat the system walls, thereby
accelerating the desorption
process. Baking mobilizes the
vapours so they can be cracked
and pumped by discharge.
Replace the feedthrough.
Highpot the pump.
5
61/68
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