Hello Joe,
I have sometimes seen a leak from the fill port under the black rubber disk
on a few of our magnets, but not always. Once it starts to leak, there is no
stopping it. The disk is just plain frozen in it's misshapen state, and
will continue to leak until you are finished the fill.
I came up with one "solution" I had to this for one particularly problematic
magnet/transfer line combination:
I speculated that the rubber disk was ever so slightly concave. So, I
removed the disk from the stinger, flipped it over and then re-installed
it. Since then, I have seen much less cold helium "plume" escaping from
the fill port. Occasionally we will see some venting, but nothing like
we had seen previously.
Not only do we leave the large diameter one-way valve on the exhaust
port, but we are also tied into a helium recovery system. So we have
the additional back-pressure to deal with. So, I think this should work
for your magnets as well.
Good luck,
Bob.
On 2024-07-22 5:45 p.m., Joseph Dumais via groups.io wrote:
>
>
> As part of a recent console upgrade on our 600, I requested a new=
> Helium transfer line since we are pretty remote here and our other
> line has been in user for 16 years. I wanted to have a backup on
> site. When we fill our 600 we leave the Bruker supplied check valve on
> the exhaust port, it seems to be a very low pressure check valve that
> seems to be functioning just fine (no sticking detected and the
> pressure to open it is very low). The new transfer line is of a
> corrugated outer layer versus the braided outer layer on the older
> one. It is considerably lighter. For the magnet side of the transfer
> line we use the rubber disk which Bruker provided to seal the upper
> stack on both the older line and the newer transfer line. I checked
> the stinger length below the rubber disk and it was set to a depth
> which was no longer than it was on our older transfer line. As soon
> as we started to fill the magnet there was a plume of cold gas
> escaping from between the top surface on the upper stack and that
> rubber disk. It seemed like maybe there was not enough weight to seal
> that gap? I tried to wrap it with thread sealing tape but that was
> tough with the plume of cold gas coming out. I did not want that part
> of the upper barrel to end up loaded with condensation. In the end I
> decided to remove the check valve and that solved the issue.
> Has anyone else had this issue with the new transfer lines on one of
> the magnets which has that check valve?
> We always remove the wider ring and take that "top hat" assembly off
> and do not use the smaller diameter opening. We could use the narrower
> part of the cap if we had another one of those smaller diameter,
> knurled black caps which could stay on the stinger. That would be
> more like what I was used to on Oxford magnets.
> Joe Dumais
>
--
Dr. Bob Berno
Manager, NMR Facility
McMaster University, ABB-156
1280 Main St. West
Hamilton, ON L8S 4M1
T: 905-525-9140 x24158 or x24686
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