Based on the sweating I see on the helium turret, there might not be much
to do other than a rebuild. If the magnet vacuum is going bad you can
try pumping on the magnet without doing a rebuild but that's often just a
band-aid approach if it does work. Is there moisture or ice on other
places on the magnet?
It's usually a good idea to check o-rings in these situations--they do fail
and get lost, and the one on the fill port gets more wear than the rest do.
I've also seen the ones around the helium sensor fail. And that seems like a
lot of bubbles to see for a helium leak around there. Usually I'm used to
seeing little pinhole leaks that might bubble a bit, or you might have to track
down with a leak detector. I'm not sure I'd expect that amount of bubbles
unless something was under some amount of pressure. You've got #heliumrecovery
in the subject line of the email--is this magnet connected to a recovery system?
And are all the valves to that system in the appropriate positions? There
was one case I know of where the wrong valves got closed at the wrong times and
it allowed the pressure inside the magnet to get higher than normal.
Cheers,Mike
On Monday, September 30, 2024 at 09:43:10 AM MDT, Hla Win wrote:
Hello Everyone,
I hope all are well on your side. We have a 500MHz Oxford 22-year-old
magnet that is leaking LHe. Picture attach. The normal LHe boil-off
is 5 cc/h, and the average loss is 0.43%, about 23 mL/h. LHe fill is
every 90-100 days. It uses about 45-50L the most. We’ve
lost LHe this week 4x higher than normal. You will see bubbles around
the base, by the transfer port, by the little "black" seal. If you
know of anyone who repair magnet, please let me know. In the meantime,
I would appreciate any recommendations on what I should do to minimize the
loss.
Thank you.
Hla Win
Organic & NMR Lab Coordinator
Department of Chemistry
Western Washington University
516 High Street, Bellingham WA 98225
winpiah_at_wwu.edu | 360-650-2261
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