Bruker RS - During Cool down

90
ZTKS0156 / Z31820 / Rev.: 03
Troubleshooting
6.2.3 During Cool Down
a. see note on page before
Continued on next page
Indicator Possible reason Solution By
Precooling with
liquid nitrogen conti-
nue too slowly.
Empty transport
dewar.
Refill or change transport
dewar.
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Transfer pressure
too low.
Increase transfer pressure
slightly.
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Transport dewar is
leaky; no transfer
pressure may be
applied.
Check transfer dewar and
change if necessary.
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Precooling with
liquid nitrogen conti-
nue too quickly.
Transfer pressure
too high.
Stop precooling. Adjust
correct transfer pressure.
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Vacuum in RT vessel
does not reach
5x10
-8
bar.
O-rings may be
leaky.
Check and clean O-rings and
slots; change O-rings if
necessary:
• of the vacuum valve
• of the drop-off plate
• of the reduction and
sealing flanges
• of the bottom plate
a
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O-rings may be fro-
zen due to contact
with liquid nitrogen.
1. Stop precooling.
2. Warm up O-ring with
warm air
3. Wait until the vacuum
recovers.
4. Prevent liquid nitrogen
from splashing on
O-rings.
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Defective pumping
line.
Check pumping line between
the cryostat and vacuum
pumping unit; change if
necessary.
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Defective pumping
unit.
Check pumping unit:
A pressure below5 x 10
-8
bar
must be reached with a
closed sealing plug.
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