I'd like to hear any comment on re-commission magnet.
We are moving our 400 MHz NMR from the first floor to the new lab in the
basement.
The magnet is 12 years old. I think that it is essential to replace the seals
and the getter
(or baked getter). In the case of the superconducting magnet, the helium dewars
plays
the role of a cryopump. The vacuum is mainly limited by the helium gas in the
vacuum
space. The old getter and seals are saturated with helium gas, and can no long
hold any
more helium gas. The replacement of the seals and the getter is the key factor
to ensure
the long life of the magnet. However, the NMR vendor insists that they will
change the
seals only if it is "necessary". Their criteria are that it is not necessary to
change the
seals if the reasonable vacuum can be reached. My personal opinion is that is
simply
not good enough. I would appreciate any comment?
Chuan Wang, Ph.D.
Director of NMR Spectroscopy
Department of Chemistry
Rutgers, The State University of New Jersey
(908) 445-3967
wang@vxr400.rutgers.edu