_at_Spin-Doc
„30 liters of liquid-equivalent“ in it are the fill losses
as well as the warmed up Helium gas from the dewar (around 7.5 m³; 10l
liquid-equivalent). The fill loss would be in this case around 20%.
Best regards,
Sebastian Kemper
From: main_at_ammrl.groups.io <main_at_ammrl.groups.io> On Behalf Of Spin-Doc
Sent: Mittwoch, 30. Juli 2025 09:29
To: main_at_ammrl.groups.io
Subject: Re: [AMMRL] Helium recovery - bag size
_at_ Robert:
A loss of a whopping 30% at each refilll does sound a bit excessive to me and
triggers some questions:
- do you use one single helium transfer line each time? Sure that its vacuum
is still OK? Tried to open its valve, clean & re-grease the O-ring and
pump out on a turbo for a few hours?
- what is the pressure in the helium dewar used during transfer?
-> 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 30.07.2025 um 02:49 schrieb Kim, Yong Wah via groups.io:
Hello,
We have just installed a Medium pressure Helium recovery system by Quantum
Design, QD. We had recently transferred 119 liters of liquid into our 600
MHz magnet. Our Renner helium compressor seems to be able to keep up with
the boiloff during liquid helium transfer. We are told by the installers
to keep the oil temperature of the compressor below 60C. I would love to
hear about your experience with a similar system.
We had chosen the QD system with 3 X '1000-Liters' storage tanks because the
contamination level is much lower than the "bag' system. So far it seems
to be a robust system. We opted for a mechanical backpressure controller
and the pressure in the magnet do goes through cycles of pressure fluctuations
of less than 0.3 inches of H2O every 90 seconds. No impact on NMR data has
been detected so far. The tanks have 29" diameter and 92" high.
Best regards
Yong-Wah Kim,
________________________________
> From: main_at_ammrl.groups.io on behalf of Sebastian Kemper via groups.io
> Sent: Tuesday, July 29, 2025 8:30 AM
> To: 'main_at_ammrl.groups.io'
> Subject: [EXTERNAL] [AMMRL] Helium recovery - bag size
Hello everyone,
I would like to modify my helium recovery system so that I can collect helium
during the filling procedure. Due to the relatively limited space, I have a
few questions about balloon size and compressor performance and I would be
very grateful for any experience from colleagues so that I can purchase
the right equipment.
- How much helium will be produced with a fill of 80-90 liters? I calculated
for 80 liters with a fill loss of 15% that max. 16 m³ will be released
during the fill (assuming the cold replaced gas will warm up from 4 K to 298 K).
What are the real numbers? Are there any empirical values?
- I probably only have space for a balloon of 10-12 m³. Do you have a
setting where the compressor starts during filling and compensates for a
balloon that is ‘too small’? A colleague told me, that it is
possible, but I don't want to miscalculate and it would be very helpful to
hear about other cases. If you have such a setting, what size balloon do
you have? What is the compressor's flow rate? At what percentage of the
balloon volume does the compressor activate?
Best regards,
Sebastian
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Received on Thu Jul 31 2025 - 10:26:03 MST