RE: Replacing O ring seals on magnet cryostats

RDUDLEY (rdudley@ARSERRC.Gov)
Tue, 07 Jan 1997 13:04:10 -0500 (EST)

I would like to put in my two cents worth on this topic. A little over two
years ago we moved two magnets to a new lab and replaced the console on the 400
mHz magnet. The 200 mHz magnet was moved at field (A Gemini-200 R2D2 magnet).
THe 400 Mhz magnet was decomissioned, the cyrogens removed and them it was
moved. After the move all the o-rings were replaced. One o-ring had a small
crack in it, but the magnet person said it was insignificant.

The magnet has been at field for two years now and the only thing that we have
noticed is the Helium hold time is longer. We still fill the magnet every 30
to 31 days. I do not know if this is because the o-rings were replaced or if
the magnet person did a better job of pumping down the dewar. I have heard of
a magnet that has been at field for twenty years without a problem. I would
say that if it is a relatively new magnet do not replace the o-rings, if it is
12 years or older (like our 400) consult with the manufacturer.

I would like to wish everyone a Happy New Year and I hope to see you all at the
ENC this year.

Bob Dudley
rdudley@arserrc.gov