Hi David,
It looks like you done a proper job of connecting it. One of our users was
using a helium flow cryostat with a diaphragm pump (EPR System) and used
push to connect fittings. They are not tight and sucked air into the system.
Just a word of warning to anyone who might want to implement this….
Jeff Walton
On Sep 3, 2025, at 2:00 PM, Vander Velde, David via groups.io wrote:
We have been wondering what to do if that scenario happened, and it did over
the weekend ... we have a ~ 235 cu ft helium bag, and boiloff from our 7 NMR
magnets will fill it in about 30 hours. We tried switching our system over
to direct recovery, but the pressure in our helium recovery lines is very
low, and it wasn't enough to produce gas flow compared with the back pressure
in our purification setup. However, we found that an inexpensive diaphragm
pump (~ $600) connected between the bag and our storage cylinders did the
trick. The pump only produces a couple psi in the cylinders, but that is
enough to get through the purifier, and produce near normal amounts of liquid
helium by our standards, about a liter an hour. The pump pictured empties
the bag a bit faster than the magnets fill it, so we only have it on while
we are there to make sure the bag doesn't get completely deflated.
David VanderVelde
Manager, Liquids NMR Facility, Caltech
davidv_at_caltech.edu<mailto:davidv_at_caltech.edu>
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Received on Thu Sep 04 2025 - 11:43:58 MST