RE: AMMRL: RE: very scary nitrogen fill

From: Thomas Eubanks <thomas.eubanks_at_utrgv.edu>
Date: Wed, 31 Aug 2016 18:46:55 +0000

I would like to thank everybody that responded to my questions about the He fill on the Bruker 600 ultra shield. The Bruker engineer said that the He fill line should go in all but two inches. Also, I was pushing at 5lbs...he said that wastes He and recommended 3 lbs. The He out gas cloud should be no more than 10 inches and that will make it obvious when it's full. Here, as with most things, patience is a virtue


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Thomas Eubanks
Department of Chemistry
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From: Jan Lang [mailto:Jan.Lang_at_mff.cuni.cz]
Sent: Friday, August 26, 2016 4:50 PM
To: g-sukenick_at_ski.mskcc.org; David.Richardson_at_ucf.edu; ammrl_at_ammrl.org
Subject: RE: AMMRL: RE: very scary nitrogen fill

Hi all,

blockage of the nitrogen exhaust turret happened to me 2 - 3 times over 18 years in our 11.7 T Bruker magnet although it has a check valve.
As many others, I am refilling LN2 just prior to He fill and I am trying to fill helium fast, i.e. in around 30 - 40 min (55-60 liters). I think that the blockage occurred when helium fill was too slow and the magnet nitrogen manifold became probably too cold.

Best regards,
        Jan


---------------------------------------------------------
Jan Lang
Associate Professor

Charles University in Prague
Faculty of Mathematics & Physics
Department of Low Temperature Physics
V Holesovickach 2
CZ-180 00 Prague 8
Czech Republic

Tel.: +420 221912889
Fax: +420 221912567

http://nmr.mff.cuni.cz<http://physics.mff.cuni.cz/kfnt/nmr/>




From: g-sukenick_at_ski.mskcc.org<mailto:g-sukenick_at_ski.mskcc.org> [mailto:g-sukenick_at_ski.mskcc.org]
Sent: Wednesday, August 24, 2016 9:22 PM
To: David.Richardson_at_ucf.edu<mailto:David.Richardson_at_ucf.edu>; ammrl_at_ammrl.org<mailto:ammrl_at_ammrl.org>
Subject: Re: AMMRL: RE: very scary nitrogen fill

David,

Older instruments do not use check valves and use latex or similar tubing for exhausting nitrogen gas.
I have one 20 year old instrument with that setup, but I've never had ice buildup inside.
I fill nitrogen before the helium fill and keep the tubing in good condition.

Newer Bruker instruments have polyurethane tubing connected together with push in fittings to form a system with a check valve.
The Bruker engineer showed me that at each fill the tubing needs to be tested that they are securely in the fitting as they do come loose - and when they are loose, you have an open system, and air can get in.

Cheers

George



From: David Richardson <David.Richardson_at_ucf.edu<mailto:David.Richardson_at_ucf.edu>>
Date: Wed, 24 Aug 2016 13:42:35 +0000
To: AMMRL <ammrl_at_ammrl.org<mailto:ammrl_at_ammrl.org>>
Subject: AMMRL: RE: very scary nitrogen fill

Hi all,

Is it not standard to put a check valve (or one-way valve/back-flow preventer valve, whatever the appropriate name may be) on the nitrogen exhaust? I have never worried about the negative pressure in the nitrogen can during a helium fill because of the check valve, but with as long as this conversation has gone on without mention of using a valve I am starting to wonder if I need to consider the pressure despite using the valve.

David

David Richardson, Ph.D.
NMR Instrumentation Specialist
Chemistry Department
University of Central Florida
david.richardson_at_ucf.edu<mailto:david.richardson_at_ucf.edu>
407-823-2961
http://chemistry.cos.ucf.edu/nmr/




Received on Wed Aug 31 2016 - 08:46:59 MST