I'll second the PTFE. It stays nice and flexible with LN2 flowing through it.
Bruker sells a kit
https://store.bruker.com/products/nitrogen-refill-set
with a chunk of silicone tubing on each end and the PTFE in the middle. And an
adapter for the larger fill ports on the newer Bruker magnets. People definitely
have to replace the silicone tubing occasionally but that PTFE stuff will last a long time.
Cheers,Mike
On Monday, January 5, 2026 at 08:23:33 AM MST, Plant,Daniel via groups.io wrote:
A friend of mine uses PTFE...haven't tried it but it sounds good...for fills.
(wasn't the original poster asking about N2 vent tubing...?)
....Yea we stopped using the rubber connections because it eventually fractures
and can shoot pieces out when it does. We have been using bellowed PTFE for a
few years now. The lower end of the temperature range is -450F. It is a little
costly but worth it. They last a few years but will finally start leaking on
the magnet side from strain. I buy a 6 or 10 foot section and then add a 1
foot section to the end so that it can be replaced if it fails preserving the
lengthy piece. The ID of the of the tube in the link (.47”) snuggly
fits most of our magnets nitrogen turrets so no need for the rubber connector.
https://www.mcmaster.com/51155K68/
> From: main_at_ammrl.groups.io on behalf of Cathy Clewett via groups.io
> Sent: Monday, January 5, 2026 9:21 AM
> To: main_at_ammrl.groups.io
> Subject: Re: [AMMRL] Real Natural Rubber Tubing [External Email]
Hi all,
The pipe insulation may work well for the purpose described, and be aware that
some of this material is magnetic. Way back another lifetime ago, we
used to use it to insulate heating air going to our probes. We found that the
material was magnetic and affected our shims. It also has a tendency to pill
and shred with repeated use. I would suggest being careful with it around magnets.
Cheers!
Catherine F. M. Clewett, Ph.D.
Asst. Director Magnetic Resonance
Chemistry Instrumentation Center
University of Wisconsin Madison, Department of Chemistry
1101 University Ave Room 2201c, Madison, WI 53706
clewett_at_wisc.edu, (608)262-8196,
https://pbcic.chem.wisc.edu
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Received on Mon Jan 05 2026 - 07:48:20 MST