Hi Bert,
Sorry for the long answer! It's difficult to explain in a few sentences. The
tl;dr is my comment about valve closing only makes sense given the very specific
circumstances for my setup.
I should clarify; these ball valves do not allow/prevent exhaust gas leaving
the magnet, rather they control the flow path. The intention behind the valve
is to allow a switchable setup for including a boil off meter. Fills have too
much volume for those meters to handle. The flow path with meter is for routine,
and pathway with wider inner diameter is for fills. For magnets without a flow
meter (or alternative accessory reasons) the ball valve could be completely
removed without affecting function.
To address backpressure, I put my helium check valves into a different location
on the manifold than I think is typical. It makes the ball valve position
extremely relevant. In this setup, the valve position for routine use with
boil off meter sends gas through the check valve. The position for fills
bypasses the check valve entirely.
The check valve works based on pressure differential at either end. That means
the magnet has to pressurize slightly to open the valve. I would've preferred
to send exhaust through the valve at all times. However, the backpressure I
had observed was enough to create an unacceptably high risk of quench. So
I did everything I thought possible to minimize pressure during fills.
In my case, opening the valve effectively removes all protection offered by
the check valve. Since I usually fill these two magnets on the same day I
want to depressurize both of them beforehand, i.e. open their valves. The
header also connects the magnets like an umbilical cord. My comment about
closing the valve was a reminder that it's unwise to fill magnet X while
magnet Y is unprotected. Adjusting the ball valve before/after fills is
already a normal part of using this type of manifold. My setup tosses the
1-2 additional steps into the mix.
Kind regards,
Luke
Luke Fulton, PhD
CHEM BLDG R003
NMR Core Facility Director
Unit 3060
COR2E & Department of Chemistry
55 N Eagleville Road
University of Connecticut
Storrs, CT 06279
email: fko24003_at_uconn.edu
(alias): luke.fulton_at_uconn.edu
mobile: (603) 953-5275
Office: (860) 486-4069
________________________________
> From: main_at_ammrl.groups.io on behalf of Spin-Doc via groups.io
> Sent: Thursday, June 12, 2025 4:04 PM
> To: main_at_ammrl.groups.io <main_at_ammrl.groups.io>
> Subject: Re: [AMMRL] Quench narrowly avoided? Filling small magnets connected to helium recovery
Hi Luke,
Sounds great! There’s only one practice I‘m not so sure I‘d
be a fan of: closing the valves on other magnets before the helium refill of
another…:
- if there’s a quench all check valves will close anyway and won’t let
any helium pressure into the other magnets (might be that a very small amount can pass
before the check valve has time to close). After the incident they will open again by themselves
- what you haven’t touched you can’t forget (especially during/after
the upheaval created by a quench that hopefully never happens). If you forget to
re-open one of them and your magnets don’t have an emergency blowoff valve
you may have the next quench approaching fast…
Cheers
Bert
-> Sent via mobile <-
Spin-Doc
Magnetic resonance equipment, service, training & more
Dr. rer. nat. Bert Heise
Owner, applications scientist
Kiefernweg 13
58239 Schwerte
Germany
Web: http://www.spin-doc.net
Mail: bert.heise_at_spin-doc.net
Phone: +49-171-5135315
Representing MestreLab, Stelar & Barthel HF
Am 12.06.2025 um 19:24 schrieb Fulton, Luke via groups.io:
Hi all,
Update:
Yesterday was the first helium fill since discussing dangerous backpressure
a few months ago. Thanks again to everyone for feedback and advise. I redesigned
the manifold connections and things are now much safer. Still a little higher
than the old days before HRS, but nothing to worry about. May I never again
see liquid shoot out from a fill port. Pictures attached for the before/after.
Key changes:
-repositioned helium check valve
-increased ID on hose barb adapters
-open ball valve day before to relieve pressure
(header pressure jumped ~0.03 psi, triggered the system's larger compressor)
(during fill keep valve open, but as precaution close valve on other magnets
in case of quench)
-track fill progress by monitoring collected exhaust gas (rough estimations
remarkably accurate for 1st attempt)
Kind regards,
Luke
Luke Fulton, PhD
CHEM BLDG R003
NMR Core Facility Director
Unit 3060
COR2E & Department of Chemistry
55 N Eagleville Road
University of Connecticut
Storrs, CT 06279
email: fko24003_at_uconn.edu
(alias): luke.fulton_at_uconn.edu
mobile: (603) 953-5275
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Received on Thu Jun 12 2025 - 16:20:34 MST