Hi Luke,
We have a Quantum Technologies HRS with medium‑pressure storage tanks.
I’d describe our system as almost closed-loop, since the recovery header
pressure is held at ~0.2 psi above atmospheric via a regulator which effectively
“senses” atmospheric pressure.
When we first brought the system online, we noticed that the amount of passive
boil‑off we collected varied slightly from day to day. After adding an
atmospheric pressure sensor to our monitoring setup, we saw a pattern: on days
when atmospheric pressure is rising, we collect less helium; when it’s
falling, we collect more. For us, the day‑to‑day swing is under
±10% even when the weather brings big pressure changes.
Best,
Sameer
--
Sameer Al-Abdul-Wahid, Ph.D.
Manager, Nuclear Magnetic Resonance Centre <
http://nmr.uoguelph.ca/>
University of Guelph
519-824-4120 x58914 / s.wahid_at_uoguelph.ca
> From: main_at_ammrl.groups.io on behalf of Michael Groves via groups.io
> Date: Thursday, February 5, 2026 at 19:08
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] Helium Boil Off Question
Hi Luke,
"Maintaining accumulated volume but failing to liquefy any additional gas"
So the level of liquid in the magnets is dropping but the level in the storage
dewar stays the same? You sure you don't have a leak somewhere? Unless it
was all somehow getting shoved into the MPTs and just sitting there.
I would also expect an instrument with that kind of liquefier to be pretty
insensitive to air pressure changes, but if there was a leak then that would
provide a mechanism for the ambient pressure to affect the boiloff rate.
Anyway, that's my $0.02. Worth more or less depending on the local exchange
rate...
Cheers,
Mike
On Thursday, February 5, 2026 at 02:24:21 PM MST, Fulton, Luke via groups.io wrote:
Hi spinlanders,
We (hopefully) finished troubleshooting an issue with our helium recovery
system this week. It was maintaining the accumulated volume but failing to
liquify any additional gas into the production dewar. Turned out the automated
threshold settings were out of sync with our magnet's boil off rates. During
our communications with the manufacturer a curious question came up.
The HRS design is a closed loop. We have medium pressure storage tanks rather
than a gas collection bag, and it's an all-in-one system. Gas is pulled directly
from the header into a purifier, and from there goes to the liquefier. Under
high exhaust conditions, such as a helium fill, the gas is temporarily redirected
towards the MPT's, and purified/liquefied later. We discussed variable boil off
rates due to weather patterns, and the manufacturer suggests that under this
system the magnet boiloff should be agnostic to atmospheric changes.
Now I can empirically attest that my magnets are still an effective weather
-wise. And it has me pondering, why? Perhaps the manufacturer was mistaken
on this detail. Or, perhaps it's a clue that something else still requires
my attention. My instincts lean towards the former, but I've learned to check
the alternative just in case. Anyone have an opinion they'd be willing to
share?
Kind regards,
Luke
Luke Fulton, PhD
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Received on Fri Feb 06 2026 - 04:42:08 MST