Bruker RS - Page 91

91
ZTKS0156 / Z31820 / Rev.: 03
Troubleshooting
Continued from page before
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Indicator Possible reason Solution By
RT vessel becomes
cold and wet.
Vacuum is broken or
less than
1x10
-6
bar.
• Do not remove pumping
unit until liquid helium fill-
in is finished.
• Continue as in problem
Vacuum in RT vessel
does not reach
5x10
-8
bar above
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Cold leak after
transportation.
1. Stop cool down.
2. Warm up cryostat.
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Cold spot in the
RT-bore.
Alignment not
correct.
1. Stop cool down.
2. Warm up cryostat.
3. Align the vessels.
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The helium flow
system becomes
very cold and icy
during pumping and
flushing with helium
gas.
liquid nitrogen
remains in the
helium vessel,
boiling off strongly
during pumping.
1. Stop pumping.
2. Carefully remove all
liquid nitrogen through
the precooling tube.
3. Check with the dipstick to
be sure that the helium
vessel is completely
empty of liquid nitrogen
and of frozen nitrogen
(nitrogen ice).
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After some intervals
of pumping and flus-
hing it is not possible
to reach a vacuum in
the range of
0.001 bar.
The globes in the
quench valves are
not fitting correctly in
the O-rings and thus
the quench valves
are leaky.
1. Stop pumping.
2. Remove frozen air and
frozen moisture with
warm helium gas.
3. Slightly grease the
O-rings and check the
position of the globes.
4. Check with the dipstick to
be sure that the helium
vessel is completely
empty of liquid nitrogen
and of nitrogen ice.
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Liquid nitrogen
remains in the
helium vessel,
boiling off strongly
during pumping.
1. Stop pumping.
2. Carefully remove all
liquid nitrogen through
the precooling tube.
3. Check with the dipstick to
be sure that the helium
vessel is completely
empty of liquid nitrogen
and of frozen nitrogen
(nitrogen ice).
Bruker Service