NMR Folks,
Thanks for the answers some time ago to my question about
protecting our 400 unshielded magnet, not to mention the workers, during
construction in our NMR room. Some of you might be interested in what
worked for us.
First, the contract required a safety meeting between ourselves,
the contractor and all subcontractors who would work in the room. The
contractor had his own safety officer present which was very
comforting. The presence of a responsible university person was required
when work was going on in the room. By present, we meant close at hand and
constantly checking on the workers.
We ourselves built an OctaBox out of eight sheets of 4' x 8' 3/4
inch plywood standing on end. We wouldn't let our university people or the
contractor that close to the magnet to even build it. It extends beyond
the 25 gauss line which is shown by the blue tape on the floor in the
following photo. We had no problem using small hand tools (cordless
drill, reciprocating saw) to build the box from the outside.
http://www.umt.edu/chemistry/images/OctaBoxA.jpg
We vented the helium outside the box. A nearby wall just beyond
the 5 gauss line was coming down. We decided to leave some unsightly, no
longer used pipes since we weren't 100% sure that their removal could be
done safely and we weren't 100% sure if we could bring the homogeneity back
with just the RT shims.
The finished box shows additional plastic separating the box from
the wall to be demolished. We used duct tape on all seams and around the
door. The hatch-type door was useful for keeping nuts, bolts, electrical
box knockouts away from the magnet. It had a reinforced clear plastic roof
for part of it. No work was done above the box. The shutdown console and
computer were covered with a plastic tarp.
http://www.umt.edu/chemistry/images/OctaBox.jpg
The wall is down in the following photos. Those unused pipes are
sticking out to the side. An electrician found that a sizeable piece of
steel electrical conduit would stick to one of them! This magnetization
extended well outside the 5 gauss line.
http://www.umt.edu/chemistry/images/MagnitizedPipe5.jpg
http://www.umt.edu/chemistry/images/MagnitizedPipe2.jpg
All in all, things went rather well. We saw no build-up of dust
on the Dewar. We didn't have to "shave" the magnet. We were able to use
the spectrometer except during the dirtiest of work.
Finally, be sure to get your safety officer's approval before
proceeding on your own projects.
Thanks, again.
Ed Waali
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Edward E. Waali
Department of Chemistry
University of Montana
Missoula, MT 59812
Voice: (406) 243-4992
FAX: (406) 243-4227
E-mail: edward.waali_at_umontana.edu
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Received on Tue Aug 23 2005 - 19:18:10 MST
