Hello Jerry,
I am quite surprised that most responses do not see an increase in helium
fill times into the recovery system. Our fill time on our 400MHz magnet
(Magnex) has about doubled. We have a QT system with medium storage
pressure tanks and the liquifier, i.e, we do not capture the helium into a
bag. Maybe that is where the difference comes in. We regulate the flow into
the transfer tank so that the 0.4psi blow off valve in the liquifier unit
stays closed, typically around 0.3psi. And yes, that flow into the
transfer dewar is about half of what we used to use when filling into the
open air. I do not raise the pressure into the source dewar much. That
mostly depends on the diameter of the transfer line. But most importantly
it is set for keeping the blow off valve (0.4psi ) from doing its business
as mentioned. I am mostly worried about not damaging the magnet with too
much pressure, so we take the extra time.
The "overhead", i.e. gas volume per liquid helium filled into the magnet
has not changed much. I don't worry about that, because it is recovered.
I hope this helps.
Happy resonating and Easter,
Ulli
On Fri, Apr 3, 2026 at 10:38 AM gregory.wylie via groups.io wrote:
> Hi Jerry
>
> We have kept records on fills from before and after our recovery system.
> We see no change in duration, helium used, or pressure in the supply dewar.
> We consistently use the same Dewar PSI and flow before and after recovery
> system install, we also are very consistent on when we fill magnets so
> helium used and duration of fills are consistent.
>
> I have put pressure gauges on our recovery lines during fills and never
> had anything go over 0.1 PSI. This was just after our heat ex-changers and
> further down the main line as well.
> Design of your system can be a factor here too! If you try to use too
> small of an exhaust line or main line you could have issues.
>
> Hope that helps
> Greg
>
> Gregory P. Wylie, Ph.D
> NMR Facility Manager
> Texas A&M University
> Department of Chemistry #3255
> 580 Ross St.
> College Station, TX 77843-3255
> gpwylie_at_tamu.edu
> 979.458.0705 (voice)
> 979.845.4719 (fax)
> 706.206.0007 (cell)
> http://nmr.tamu.edu
>
>
--
Dr. Ulrike Werner-Zwanziger
Adjunct Professor
Department of Chemistry, NMR-3,
Dalhousie University
6245 Castine Way
PO BOX 15000
Halifax, NS B3H 4R2
e-mail: Ulli.Zwanziger_at_Dal.ca
Tel. 1 902 494 8085
FAX: 1 902 494 1310
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Received on Fri Apr 03 2026 - 08:16:12 MST