Bruker 300'89 Ascend, User Manual

Page: 43 / 100

43 ZTKS0168 / Z31960 / 05
Troubleshooting
Table continued
Indicator Possible reason Solution Performed by
RT vessel
becomes cold and
wet. Vacuum is broken
or less than
10
-3
mbar.
• Keep the pumping unit
connected until filling with
liquid helium is finished.
• Continue as in problem
Vacuum in RT vessel
does not reach
10
-6
mbar.
Bruker Service
Cold leak after
transportation.
1. Stop cooling.
2. Warm the cryostat.
Bruker Service
Cold spot in the RT
bore. Alignment not
correct.
1. Stop cooling.
2. Warm the cryostat.
3. Align the vessels.
Bruker Service
The helium flow
system becomes
very cold and icy
during flushing with
helium gas. Liquid nitrogen
remains in the
helium vessel,
boiling off strongly
during flushing.
1. Stop flushing.
2. Carefully remove all
liquid nitrogen using the
precooling tube.
3. Use the dipstick to check
that the helium vessel is
empty (no liquid nitrogen
or frozen nitrogen).
Bruker Service
After some
intervals of flushing
it is not possible to
reach a vacuum in
the range of
1 mbar. 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 using
warm helium gas.
3. Apply a small amount of
grease to the O-rings and
check the position of the
globes.
4. Use the dipstick to check
that the helium vessel is
empty (no liquid nitrogen
or frozen nitrogen).
Bruker Service
Liquid nitrogen
remains in the
helium vessel,
boiling off strongly
during flushing.
1. Stop pumping.
2. Use the precooling tube
to remove all liquid
nitrogen.
3. Use the dipstick to check
that the helium vessel is
empty (no liquid nitrogen
or frozen nitrogen).
Bruker Service