Thanks much already for the comments back about both my questions
about He boiloff oscillations -- we got lots of good ideas, and I
will post the cause and solution when we find them -- and about
moving a 500 MHz magnet.
Interestingly, we have a lot of experience moving smaller magnets.
The faculty member that is so opposed to the move is very
knowledgable about the subject, so I need good sources of
information to counter his arguments (and AMMRL is definitely
one of the best sources for this kind of information!!).
We already knew that a magnet of this age will likely need
new o-rings sometime soon (all the more reason to consider
warming up the magnet and moving!!), but I wanted to keep your
responses unbiased. Your responses, 24 so far, give me a lot
of help in convincing everyone here that the move should happen
and that the risk involved is minimal. The current location of
the magnet really is poor.
Thanks again for all the help.
Charlie Fry
Director-Magnetic Resonance Facility
University of Wisconsin-Madison
fry@chem.wisc.edu
(608)262-3182
>I have two questions to bounce off you:
>
>1. About a month ago, we started experiencing significant oscillations
> in the He boiloff on one of our Oxford 500MHz magnets. The
> flow meter oscillates with a 4-5s rate from 4 to 12 cc/h. We
> have added 100 ft of tygon in front of the flow meter, and
> also put a ballast valve (not sure of the type, but was
> installed last year on a new AC we got from Bruker); neither
> have changed the situation significantly. The problem shows
> up in 2D spectra with ~60 Hz T1 noise, and we initially looked
> for grounding problems before noticing the boiloff fluctuations.
> We've confirmed the boiloff is giving the T1 noise by venting the
> He dewar and watching the noise come back. Any suggestions
> about what the problem might be and how to alleviate it would
> be greatly appreciated.
>
>2. I have another Oxford 500MHz magnet that we need to move down
> a hallway to another room (same floor, no steps). We have a
> faculty member that is adamantly opposed to moving the magnet,
> however, for fear of it getting damaged during the move (it's
> ten years old). My request is the following: please let me
> know if you know of a magnet that was irreparably damaged
> during a move due to just moving it (i.e., not due to '
> inappropriate handling of energization leads during bringing
> the field down, or similar).