Dear Ken
Our situations are not the same but perhaps something in this story will
offer some guidance.
The NMR labs here are in a building that is being re-roofed and
re-ceilinged to (hopefully) solve a roof leak problem. While the NMR labs
have been excluded from the re-ceiling part, 100+ years worth of rubbish
from the roof space has fallen into the surrounding rooms and corridors,
and the new roof structure involves construction-related mess through the
building and work above the NMR lab ceilings. Even with precautions and
daily cleaning and little of this work taking place inside the NMR labs,
every exposed surface in the NMR labs collects dust (brown/grey fluffy
stuff) and grit from construction-related particles (brick, plaster,
concrete). While the shielded 400 magnet has not collected any rubbish (so
far), the unshielded 500 magnet has been picking up small magnetic bits &
pieces that have managed to get into the lab, despite the precautions.
This is with work (mostly) outside the labs; your work will be inside the
labs...
My precautions (perhaps you can get some ideas):
Latex glove over the upper barrel all the time.
Everything with an exposed orifice (e.g. transfer lines, gas lines, dewar
ports, vents) sealed with a latex glove finger and rubber bands or covered
with plastic sheeting.
Plastic sheeting over the magnets (removable, because helium + nitrogen
servicing continues, and not tight, to keep some air flow around the heat
sinks).
Even with the consoles off, a low compressed air flow upwards through the
bore to maintain a positive pressure (requires some re-plumbing of the gas
lines).
Daily cleaning of the labs, especially in the magnet areas.
Foam/paper stuffing in the door frames.
The project manager, contractor, and the contractor's safety officer should
be made aware of the following, and this should be documented:
The environmental requirements for NMR magnets (share the relevant sections
of the NMR magnet site preparation guide).
The hazards of working in a strong magnetic field. Are all the workers
free of metallic implants & pacemakers? Apart from the grindings, what
happens if the worker lets go of his grinder? Near the magnet, the
worker's grinder may not work as expected, or go in the expected
direction. What if the worker slips and grinds something other than the
floor? If I read from the sign on my NMR lab door, "*Tools and Equipment
- Strong magnetic fields are present that could make some magnetic items
fly towards the magnet body which could cause personal injury or serious
damage. Do not take tools, equipment, or personal items containing steel,
iron, or other magnetic materials closer to the magnet than the 10-GAUSS
WARNING signs*."
The replacement cost of a damaged magnet (the contractor should have
insurance for this).
I would suggest resisting anything that will make a mess in your NMR
lab(s), anything that involves tools close to a magnet, anything that
involves uninitiated persons close to a magnet.
If the floor of your lab(s) looks a bit ugly in places because of cracked
and chipped paint, how about putting down anti-static carpet tiles or
anti-static linoleum for the peripheral lab area and leaving the magnet
area as-is?
Kind regards,
Craig.
On Sun, 9 Mar 2025 at 21:47, Kenneth Sharp-Knott via groups.io wrote:
> As part of the restoration of the basement in our building post flooding,
> it has been decided to redo the floors in all of the labs. The labs are
> painted with a heavy-duty resin based paint. This floor pain was cracking
> and chipping before the flood and its decay has been accelerated post flood.
>
> Most labs are empty pending replacement equipment, but the magnets in our
> facility survived the flood (the consoles, chillers, etc did not). We have
> had 3 systems installed since the flood. So, they plan to grind up the
> floor as close to the magnets as possible and move the consoles, chillers,
> etc. as necessary. The whole thing terrifies me a bit.
>
> Concerns:
>
> 1. While there will be significant dust mitigation, including 1) heavy
> duty vacuum systems attached to the grinders and 2) the magnets, consoles,
> etc, will be wrapped in plastic, I am concerned not only about the dus=
t,
> but also tiny metal dust from the grinder disc getting into the magnet=
s.
> Does anyone have any experience or recommendation about this part?
> 2. They've asked if they can use the handheld grinders closer to or
> under the magnets. I am not sure if this is a good idea. A high rpm
> spinning metal disk under the magnet??? How close is safe?
>
>
> Any advice, suggestions, etc?
>
>
> Ken Sharp-Knott
> Manager of Analytical Services and the NMR Facility
> Department of Chemistry
> Virginia Tech
>
> (540)267-6502 (Cell)
> (540)231-0885 (Office)
>
>
>
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Received on Mon Mar 10 2025 - 08:15:55 MST