On 20180306 11:41, Lingchao Zhu wrote:
> Hello AMMRL,
>
> We have an old Thermo LTQ FT Ultra Mass spectrometer waiting for its
> retirement. *(Model: Finnigan LTQ FT Serial No: SN06036F)* It has a
> horizontal Oxford magnet*(Part No: AJH0280)* and we are not going to
> reuse this magnet. We don't have any magnet book or charging rod of it.
> According to the student in the lab, it has 7T magnetic field.
>
> Without too much information from the lab, we decide to dry-quench this
> magnet, meaning we will let the cryogen boiloff itself to induce a
> quench. I have following questions to ask and would appreciate any input
> from AMMRL community:
>
> 1. Should we let the liquid nitrogen go dry completely first and then
> waiting for all liquid helium boiloff? Or we need to keep filling liquid
> nitrogen until the liquid helium level is low then stop filling liquid
> nitrogen? Which way is safer?
> 2. Please see the attached photo for top part of this magnet. It has
> helium exhaust port built on top of it so when quench happens all the
> helium gas will blow out through this big pipe. Anything we need to
> check before the quench happens?
> 3. Any other important notes before the quench? We will definitely block
> the lab room when the cryogen is low.
>
> Thank you.
>
> Lingchao
>
Hi Lingchao,
Do you have the ability to open the vacuum space of the magnet? If you
can do that when the cryogens get low, a quench will happen fairly
quickly. That way you can have some control over the quench timing.
If you have anyone interested in re-using the magnet, then dry nitrogen
gas is the best way, otherwise it won't matter.
Regards,
Phil.
--
Dr Phil Dennison
NMR Facility Director (949)824-6010 (office)
Department of Chemistry (949)824-5649 (lab)
University of California (949)824-8571 (fax)
Irvine, CA 92697-2025 dennison_at_uci.edu
USA
Received on Tue Mar 06 2018 - 17:06:18 MST