Cold Pumping Magnets
A.R.Garber, NMR Services (GARBER@psc.psc.scarolina.edu)
14 Dec 93 08:45:13 EST5EDT
I do not have any experience with the Varian R2D2 magnets, but I do
with Bruker/Oxford magnets. I maintain a crash cart which consists
of a rough pump, oil type diffusion pump (standard glass model used
in vacuum lines in the labs upstairs), a muck trap, and TC and cold
cathode gauges, all mounted on a small wheeled cart. I attach this
system to a magnet through a very heavy red rubber vacuum hose. By
pumping the hose down to ca 10E-05 before opening the vacuum valve on
the cryostat, I am able to test for leaks before committing to
cracking the vacuum in the cryostat. I have used this system to pump
He out of magnets after quenches, without warming the magnet, and
have even used it to maintain a live system with a slow leak until
equipment to shut it down and repair it could be shipped to me. As
long as the muck trap is kept full and no one messes with the hose,
this is probably fairly safe, even with a live magnet. I would not
punp on a live magnet overnight or when I can not keep an eye on the
system.
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Dr. A.R. Garber Phone: (803)-777-2088
NMR Services FAX: (803)-777-9521
Dept. of Chemistry email:Garber@chem.scarolina.edu
University of S. Carolina
Columbia, SC 29208
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