Date: Fri, 6 Feb 2026 16:27:10 +0000
Hi Luke,
We also have a Quantum Tech all-metal MP storage tank HeRS (installed Nov. 2025),
and like Sameer and Tara I have also observed 10-15% variations in the
daily LHe collected in the production dewar which directly correlate with variations
in the local barometric pressure; and we have had some wild ones here so far this
winter with values ranging from the 980's to 1040mbar.
Hf your production is stagnant I agree with Mike that this may point to a leak
somewhere in the system.
Back during commissioning I discovered leaks in the magnet stack on two of our
Brukers in the facility (both 600's).
See photos.
The leaks were significant enough that each magnet could not overcome the 0.3psig
pressure in the header
Bruker came out and it was an easy fix to change the O-ring and reseat them
properly, and only then did I connect those magnets to the system.
The little handheld He leak detector has been invaluable to us for
pinpointing/ruling out He leaks.
Good luck!
J
----------------------------------------------------
James Aramini, Ph.D.
Senior Research Associate
Dept. of Molecular Genetics
Rm 1233, Medical Sciences Building
University of Toronto
1 King's College Circle
Toronto, ON M5S 1A8
Cell: 437-326-6427
Phone: 416-978-6229
----------------------------------------------------
________________________________
> From: main_at_ammrl.groups.io on behalf of Ulrike Werner-Zwanziger via groups.io
> Sent: Friday, February 6, 2026 10:13 AM
> To: main_at_ammrl.groups.io <main_at_ammrl.groups.io>
> Subject: Re: [AMMRL] Helium Boil Off Question
Dear all,
I echo Sameer's and Tara's statements. Our system is similar to Sameer's and
Tara's. We regularly observe that the magnet's boil-off, as instantaneously
measured by the flow meters on the magnet exhausts, varies depending on=
the atmospheric pressure and the state of the system (transfer happening,
just happened, or all settled down).
Happy resonating
Ulli
On Fri, Feb 6, 2026 at 10:13 AM Tara Sprules via groups.io wrote:
Hello,
Despite the closed loop and no bag- we also have a QT system- the pumped magnet
pressure during a fill is directly correlated to the atmospheric pressure. I
don't know if having an APD related to the pressure control for the pumped
magnet is what affects that (Sameer?).
I've never calculated it out, but have always felt that after a few days of
higher or lower than usual atmospheric pressure there is a small difference
in liquid levels. We recover around 90% and assume that we are still losing
around the old flowmeters on the oxford/varian magnets that we've never
removed- so I guess the system isn't 100% closed...
Tara
*********************************************
Tara Sprules
0.6 FTE, Working days: Monday, Wednesday and Thursday
QANUC
Quebec/Eastern Canada High Field NMR Facility
http://www.nmrlab.mcgill.ca
phone: (514) 398-1721
fax: (514) 398-8254
3420 University St., Rm 023
McGill University
Montreal, QC, H3A 2A7
SHIPPING ADDRESS:
Department of Chemistry, McGill University
Rm. 41 801 Sherbrooke St. W
Montreal QC
H3A 0B8
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(image/jpeg attachment: HeLeak_SSB600_111725_photo1.jpg)
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