Ulvac CRYO-U Series, Instruction Manual

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Troubleshooting
A-2 ULVAC CRYOGENICS INCORPORATED
Confirm the safety of the gas which
may blow off from the pump before
removing the pressure relief valve.
Do not block the pressure relief
valve.
WARNING
Table A-1 Cryopump Fault Diagnosis
Problem Possible cause Corrective action
Ⅰ．
It takes too long to
rough pump the
cryopump.
Or, the pressure
buildup speed from
40Pa is greater than
1.3Pa/min.
1) A leakage through a pressure relief
valve.
Remove a cap of the pressure relief
valve rotating in anticlockwise
direction. Clean the O-ring and O-
ring sheet.
2) A large amount of gas with low
vapor pressure, such as water is
adsorbed on the charcoal of 15K
cryopanel (2).
Introduce dry nitrogen or argon into
the cryopump and repeat rough
pumping.
3) Inner kit is contaminated with oil or
deposition material.
Clean the inner kit or replace it with
a new one.
4) There is a leakage in the
cryopump or the vacuum system.
Find and stop the leak.
Ⅱ．
Neither the compressor
unit nor the cryopump
start.
Consult the instruction manual of compressor unit for details.
Ⅲ．
A compressor unit
starts, but a cryopump
doesn't start. Or the
cryopump is stopped,
but the compressor
unit is running
continuously.
1) A refrigerator power cable is not
connected to the refrigerator unit.
2) In case of multi-operation of the
refrigerator unit, ON/OFF state of
the refrigerator is decided with the
control signal of the system that a
user prepares. Therefore, check
your control method to judge
whether the halt condition of the
refrigerator is normal or not.
Turn off the compressor unit and
connect the refrigerator power cable
to the refrigerator unit.
Do not connect the refrigerator
power cable to the refrigerator unit
without turning off the compressor
unit. The refrigerator motor may be
damaged if this caution is not
followed.
CAUTION