Hi Josh,
I cannot really comment on the specific dewar or its suitability for
refilling magnets, except that the design seems quite odd to me with its
non-removable "head" and the total impossibility of even just looking
inside.
However, a few years ago, we had to move a 400WB magnet (shielded - 5G
line just outside the magnet legs) by a few meters. The Bruker guys did
this by stacking some wooden blocks on a pallet jack (a regular one,
definitely very magnetic) to reach the bottom plate, lifted the magnet
up and wheeled it to its new location. All on field and without any
incident.
So personally I would not worry too much about the dewar being slightly
magnetic.
Cheers,
Matthias
On 23/10/2024 16:18, Josh Kurutz wrote:
> Hi AMMRL Community. Happy Mole Day!
>
> I’d like your help determining whether a particular liquid nitrogen
> transport dewar is safe to use for magnet fills. According to its
> labeling, it’s a model LP230 from Custom Biogenic Systems. I’m hoping my
> question about this dewar can lead to some more general discussion about
> identifying liquid nitrogen dewars that are sufficiently nonmagnetic for
> us to use.
>
> Key points:
>
> * Our dewar in question is NOT specifically labeled “non-magnetic”
> like some others we use
> * Applying a strongish non-rare-earth magnet to its main body
> indicates the main body is basically nonmagnetic. See video here:
> https://uchicago.box.com/s/u4qn83bjy9ywaadj976q7g313itf0716
> <https://uchicago.box.com/s/u4qn83bjy9ywaadj976q7g313itf0716>
> o The casters and wheels are magnetic, which may not be a problem
> o The misc hardware and gauges on top of the dewar feel basically
> nonmagnetic
> o The cylindrical part at the center of the top of the dewar does
> feel weakly magnetic, so I wonder what’s going on inside (see
> last part of the video)
> * The manufacturer appears to have discontinued this product, since
> it’s not on their website, and they don’t have the user manual or
> product information posted online
> * A customer service rep (first name only) assured me the main body is
> nonmagnetic stainless steel, the casters are magnetic, and the
> gauges are magnetic (though they don’t feel magnetic to me)
> * The user’s manual sent by the representative had no information
> about its magnetic properties and contained no information about
> whether it was safe to use around MRIs or other high-magnetic field
> environments. So we have no documentation that declares it is safe
> in our environment.
>
> OUR DECISION: Do we use this dewar or not? We were gifted it by staff
> who had broken one of our good dewars. But this dewar is not new (seems
> to have belonged to a lab that left the university without taking it),
> and may not even perform well. If is not suitable for us, we would need
> to pressure these staff to buy us a new dewar that meets or our specs.
>
> One consideration: the 5-gauss radii on all our magnetics are at most
> just outside our magnet legs.
>
> What advice do you have for this situation? Many practical factors
> indicate we could probably use it reasonably safely, but the lack of
> explicit safety guidance makes me nervous. When shopping for a new
> dewar, what must we look for?
>
> Thanks for your help.
>
> * Josh
>
> Josh Kurutz, PhD
>
> NMR Facility Manager, Chemistry Dept.
>
> University of Chicago
>
> https://chemnmrlab.uchicago.edu/ <https://chemnmrlab.uchicago.edu/>
>
> jkurutz_at_uchicago.edu
>
>
--
Dr. rer. nat. Matthias Brandl (he/him or they/them)
Technical University of Munich
TUM School of Natural Sciences - BNMRZ
Chair of Biomolecular NMR Spectroscopy (Prof. Sattler)
Lichtenbergstr. 4 (postal)
Ernst-Otto-Fischer-Str. 2 (physical)
85748 Garching b. Muenchen
Phone +49 89 289-52617
matthias.brandl_at_tum.de
https://www.sattlerlab.de/
https://www.bnmrz.org/
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Received on Wed Oct 23 2024 - 08:24:14 MST