Date: Wed, 08 Apr 2026 08:41:58 -0700
Hi Luke, Mike (x2) and Ulli,
I'm now realizing that I'm posting every response to the group, so let me do
it with one shabang.
Hmmm... I guess I'm not sure what you mean by 'helium tower', and the only
NMR 'christmas tree' I know of is the Varian lock/pulse indicator, which
some of us still have (but this wouldn't have anything to do with helium
recovery).
We purchased a very good helium leak detector, the PI spent around $5k I believe,
which I thought was overkill, but it works in magnetic fields, and now I'm
grateful for that. Ours is an Ion Science, Ltd, and is called a "Tesla"
(I guess they're not just EVs!). My one annoyance with it is that once it
detects a lot of He gas, it goes off, and then it keeps going off, so I have to
re-zero it to read normal again.
When we did the 'trunk test' where we closed all accesses to other instruments and
pressurized this "trunk" (piping that leads from the various instruments into the
basement), so where the EPR or the MCD connect, the valves were closed and they
normally are. We only open them when we're using helium on those instruments.
And the pressure in this 'trunk' held at 21psi for over 24h.
You may have seen my response to Greg above regarding the gas compressor. Had to
wait a few days to get an appreciable amount of gas in the bag, then opened the thing
up yesterday (took the cover off, which was a royal pain), and while compressing the bag,
looked for leaks to no avail. Also checked the valves to the medium pressure cylinders.
Someone who sent me a direct mail suggested to turn off the gas valve into the purifier.
I don't have a gas valve for this, but the connection uses an Aeroquip, so I disconnected
this line and will see if what collects in the bag and then medium storage cylinders,
to see if it's upstream or downstream from the purifier.
I am doing plots of 'totals in the system', by converting the psi in the medium storage
cylinders into equivalents of liquid, and plotting these vs. time. For what it's
worth, I'm attaching a couple of screenshots from January and February this year.
IF I was recovering anything, then the January plot should be increasing with time, but
it is flat, and maybe even goes down slightly.
This is a bit of a frustrating problem to have, especially now, so I appreciate everyone's
input and suggestions. Thank you so much!
Cheers,
Monika
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(image/png attachment: UVM-HeR-levels-2026-Jan.png)
(image/png attachment: UVM-HeR-levels-2026-Feb.png)