Re: [AMMRL] Quench narrowly avoided? Filling small magnets connected to helium recovery

From: Fulton, Luke via groups.io <fko24003=uconn.edu_at_groups.io>
Date: Fri, 13 Jun 2025 14:41:01 +0000

Hi David,

The former. 3x magnets all connect to a shared copper pipe from which gas
feeds into the larger recovery equipment. Picture attached. Each magnet has
its own check valve to prevent exhaust from one magnet directly backflowing
into the other two. Those check valves should close if/when header pressure
spikes.

There's an additional ball valve where the whip connects to the copper pipe.
I only use it to isolate the header in case of maintenance on whip/manifold.
This one does seal off exhaust off flow, which as Bert pointed out is dangerous
if closed and forgotten.

The copper header ranges from 0.2-0.29 psi and a small compressor pulls that
gas into the purifier/liquefier. If header pressure reaches 0.3 psi, as always
does during fills, a larger compressor moves gas into 3x medium pressure tanks
(MPT) for temporary storage. If for some reason the header reaches 0.4 psi then
a relief valve will open to vent excess pressure to atmosphere.

Conjecture on my part: I think everyone equips their magnets with a check valve
for routine operation to prevent atmosphere backfilling and creating ice blocks.
In labs without helium recovery, perhaps for half of the magnets we remove that
valve during fills and vent directly to atmosphere. Filling always pressurizes
the magnet. The question is how much, and technique and setup play a role. The
check valve adds a little more, 0.22 psi (15 mbarr) in my case, and the header
more on top of that. Empirically I think the dimensions of the manifold/tubing
can magnify those numbers, though my grasp on the physics is too slippery to
explain properly.

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 David Richardson via groups.io
> Sent: Thursday, June 12, 2025 8:31 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,

You mentioned they are chained together in some manner. Does the exhaust from
filling one magnet pressurize the other all way up to the ball valve? Or is
there an additional manifold and/or backflow control on the wall preventing
the exhaust of one from reaching the other?

Regards,
David



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Received on Fri Jun 13 2025 - 08:21:47 MST