Re: Replacing O ring seals on magnet cryostats
Jim Breeyear (jbreeyea@zoo.uvm.edu)
Wed, 08 Jan 1997 09:01:34 -0800
BANGERTER%KEKULE@BIOMED.MED.YALE.EDU wrote:
>
> Chuan Wang of Rutgers raised the question of the desirability of changing
> seals and getters on older cryostats. About a year ogo we needed to move a
> 11.7T magnet that had been cold and energized in one place for 12 years to
> another room. Since the seals were 14 years old, I thought it would be
> very advisable to warm the magnet up for the move, then replace the O ring
> seals before reenergizing. We had oxford do this in connection with the
> installation of a new system. When the old seals were examined, I was amazed
> by how good their condition was. There was no evidence on microcracks, and
> they were quite resilient (I know what my windshield wipers look like after
> a year). So we may have been able to get away with moving the magnet cold
> and under vacuum (though not energized) without problems. Since the consequence
> of losing the vacuum on a cold magnet would be most unpleasant, I guess it
> comes down to how lucky one feels. I would advise following the vendor's
> recommendations on this point, particularly if they accept responsibility
> for what may happen as a consequence of the move. Our He boiloff was the
> same after as before the move (I do not remember if we replaced the getter).
> We fill He on a 5 week schedule, so it is not a critical point. Personally,
> I would choose to err on the side of caution and do not relish facing the
> faculty if corner-cutting let to a serious mishap!
>
> Ben Bangerter
> Yale Univ.
Hi,
I fill my magnets with helium once a month. I almost got caught during
the winter when the delivery trucks couldnt run due to bad storms etc. I
have two magnets and order 30 liters once a month. Keep the xfer lines
pumped down also.
Jim Breeyear
Chem Dept
Univ of Vermont