We have a high pressure Quantum Design system but we run in “bag-less”
mode with direct recovery for 90 % of the time. We have been doing this for
almost 2 years, more by accident than design due to supply-chain issues. But
we ended up liking it so much we kept running that way.
The issue is the ATL has an internal 0.2 PSI check valve inline in the direct
recovery input. So you need to fine tune pressures of magnets and other safety
valves to get it to work. Another issues is that this valve gets stuck occasionally.
QD thinks this is because we fill directly from the ATL and not into a transfer
dewar creating back pressure against the valve seat. We pressurize the dewar
through the recovery input so not sure I fully agree with this.
We have recently bypassed this check valve by feeding gas into the system through
the “pump out connector” using the adapter QD provided. It does
not seem to have the same check valve. We will remove the direct recovery valve
at some point., and replace it with an external valve that can be serviced/removed.
It is apparently not hard to do but needs a full warm up
In our set up We have the ATL set at .04 PSI and the Magnets are set about
0.5 PSI above atmosphere. Safety relief valves are set at 0.4 in the line and
0.7 at the magnet.
During fills, excess helium by-passes the ATL through an 0.33 PSI one-way
check valve downstream of the ATL.
We have 120L (liquid) storage capacity as gas. We run the purifier rarely
(every 3-4 months).
As a previous poster said. This way you avoid a lot of impurities. Passing gas
through the bag definitely adds impurities at some point in the recovery cycle.
We have done everything we can to trace leaks etc. but they are still getting
in somewhere. I wonder if the compressor is the culprit.
David
Associate Professor
Dept. Of Pharmacology
University of Colorado
School of Medicine
Tel (303)-724-3600
On Jan 31, 2024, at 7:21 AM, Martha Morton via groups.io <marthadmorton=gmail.com_at_groups.io> wrote:
The QT helium recovery system has a multiple speed compressor which is always on.
It ramps to pressure changes in the helium header. The compressor compresses into
a buffer tank that is set at a higher pressure than your storage tanks. It works OK.
There are a lot of joints and, as we know, any of them could leak. I have a QT
system and can operate many functions remotely via TeamViewer. Like all recovery
systems, the learning curve is steep and annoying.
On Wed, Jan 31, 2024, 07:23 Spin-Doc <bert.heise_at_spin-doc.net<mailto:bert.heise_at_spin-doc.net>> wrote:
Dear Chris,
I may of course be missing something - unfortunately the quantum-technology
webpage doesn't appear to contain any detailed information about their "Picasso" NMR setup -
it's not really clear to me how they handle the vastly different scenarios of
very small boiloff over weeks and months where you cannot have a large compressor
running continuously without risk of boiling off all helium, and then needing to
pump much larger quantities during a helium refill. Possibly by having two compressors,
one very small, running continuously to capture normal boiloff and a larger one
during refills? At any rate, without "zero-pressure" storage a pump must operate
continuously and in a delicately controlled manner to avoid any over- or underpressure,
both being potentially dangerous for the magnet.
The company provides, however, a link to their customer Astra Zeneca in Mölndal,
Sweden as well as mentioning the Swedish NMR centre in Göteborg - maybe not a
bad idea to contact them about it? Probably the Astra Zeneca setup will be the more
"interesting" one as the Göteborg NMR centre operates four pumped magnets which
are constantly boiling off a large amount of helium - so not really close to a "typical"
NMR lab (but an excellent setup for a helium recycling plant).
Just my 0.02 EUR,
Bert
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