Bruker 600'54 Ascend ULH, User Manual

Page: 44 / 102

44 ZTKS0175 / Z31991 / 03
Troubleshooting
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Indicator Possible reason Solution By
Nitrogen ice in the
helium vessel. Times between
pumping and
flushing were too
long; remaining
nitrogen was boiling
off during pumping
and got frozen dur-
ing flushing.
1. Warm up the magnet coil
with warm helium gas
through the precooling
tube until the whole coil is
at 90 K or above.
2. Repeat pumping and
flushing and carefully
check with the dipstick to
be sure that the helium
vessel is completely
empty (no liquid nitrogen
or frozen nitrogen).
Bruker Service
Transfer of liquid
helium does not
start. Empty transpor-
tation dewar . Refill or replace transportation
dewar. Bruker Service
The transfer
pressure in the
transportation dewar
is too low. Increase the transfer
pressure. Bruker Service
The transportation
dewar is leaky, no
transfer pressure
built up. Check the transportation
dewar for leakage. Re-tighten
all connections. Bruker Service
The siphon or the
helium transfer line
are blocked with ice. Check the siphon and helium
transfer line for blockages,
remove ice with warm helium
gas. Bruker Service
The cooling down of
the magnet coil does
not continue
although helium is
transferred. The helium transfer
line is defective. Check the helium transfer line
for icing. If there are cold
spots visible, replace the
helium transfer line. Bruker Service
The extension piece
is not mounted on
the helium transfer
line. Mount the extension piece on
the helium transfer line.
Check the helium transfer line
to be inserted completely into
the siphon. Bruker Service