I’ve used both natural rubber tubing as well as a braided stainless
steel transfer line for liquid nitrogen fills, in addition to a high density
polyethylene transfer line that Bruker supplied us with our Ascend 850 magnet.
I’ve been using the same 6’ long latex hose for 12+ years for
our lower field magnets. Each time I do the fills, I always check the hose
to make sure that there aren’t any signs of cracking, etc. Once in
a while, I’ll spray down the exterior of the hose with some Armor-All.
I figure it can’t hurt…
I’ve also been using the same 12” lengths of natural rubber
tubing on the outlet ports of the magnets for 12+ years now.
I bleed off the gas pressure in the liquid nitrogen dewars until they drop
down to 5 psi, and then do the fills.
Besides, there’s a warning sticker on just about every Bruker magnet
I’ve seen that specifically states that you don’t want to
exceed 5 psi / 0.35 bar of pressure while doing a liquid nitrogen fill, and
while it may be overkill, it’s better to be safe than sorry.
It’s inevitable that natural rubber tubing will fail eventually, but
I’d have to guess that keeping the fill pressures low should greatly
increase the lifespan of natural rubber tubing.
Ronald Shin
University of Alabama at Birmingham
Central Alabama High Field NMR Facility
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Received on Tue Sep 03 2024 - 19:33:56 MST