A separate question is what level of helium purity are you willing to admit
into your recovery system, given whatever maintenance you have to do to keep
your purifier in operation, and how often you want to be tasked with that.
In our case, we want 99% helium minimum (even higher is better), and we vent
the transfer line precool gas. We have a passive zeolite based purification
system, and found it was quite annoying to deal with frequent changes of
the zeolite insert and regenerating the saturated zeolite. A significant part
of our learning curve with the recovery system was figuring out how to
exclude the maximum amount of atmospheric contamination. Now we can get
several months between purifier maintenance cycles, but in our helium economy,
anything less than 99% helium is too expensive to purify.
David VanderVelde
Manager, Liquids NMR Facility, Caltech
davidv_at_caltech.edu
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Received on Wed Jun 18 2025 - 11:25:56 MST