62 (93) BRUKER CryoProbe Installation
Troubleshooting
Leak in He supply 5.2.5
If the He Regulator or the He Hose between He steel-cylinder and CryoCooling
Unit are accidentally damaged, close the He steel-cylinder main valve immediate-
ly, then close the He Regulator. If time permits, watch the pressure gauges and let
the remaining He gas escape before closing the He Regulator.
WARNING: If a large quantity of helium gas escapes from the He steel-cylinder
during a short period, there is a danger of suffocation, particularly in small rooms.
Moreover, high local concentrations of helium gas can penetrate the seals of an
NMR magnet, thereby spoiling its vacuum insulation and eventually lead to a
quench. Care for good ventilation and fresh air supply after an accidental release
of large quantities of helium gas.
Cool-down problems 5.3
0
COOL DOWN command is ignored 5.3.1
A cool-down can only be initiated when the whole CryoProbe System is at room
temperature. If a passive warm-up has occurred a few hours ago, the system may
not be completely warm yet. In this case, the CryoTool will display
Waiting for
system to passively warm up.
Insufficient vacuum 5.3.2
If the CryoController reports
Insufficient vacuum and stops the vacuum
pumps, or if the vacuum pumps sound strange,
- the vacuum bellows may not be properly connected at the CryoProbe or
at the Transferline Support,
- the Vacuum Adapter may not be locked tightly to the CryoProbe bottom
or its o-ring might be bad,
- the Vacuum Plug may sit inside the CryoProbe instead of being drawn
out with the Vacuum Adapter,
- the o-rings in the vacuum bellows connections might be bad,
- if the He Transferline had been twisted recently, the vacuum flange on
the He Transferline may be closed properly, see "Joining the CryoCou-
pler" on page 34,
- if you hear a squeal sound that comes and goes, the turbo vacuum pump
may not come to speed. Check its status display inside the CryoCooling
Unit cabinet to the left.
General vacuum test
Press
COOL DOWN and wait for diagnostic messages.
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