Re: Magnet location
J Chris Johnston (James.C.Johnston@lerc.nasa.gov)
Wed, 16 Dec 1998 15:03:49 -0500
At 11:38 AM 12/16/98 -0600, you (Keith Brown) wrote:
>
> We are in the process of designing a new addition to our building and
>there are those who would have me relocate the nmr lab from its current
>location in the basement to the third floor of the new building. Since I
>have always thought that cryomagnets should be located on a vibration free
>surface, this suggestion disturbs me. Are there any of you who have any
>opinions/horror stories/suggestions concerning this topic?
>
Our lab building was renovated recently. We had an AM 300 and an AC 200 in
the basement of the building, and we moved the AM 300 to a second floor
office in another building and stored the 200. The 300 worked ok on the
second floor but we did install vibration dampers on it while chasing a
problem that (two years later!) turned out to be dualing clocks. We didn't
see any significant difference between having the dampers inflated and
having the instrument on the floor.
When we moved back, the 300 and our new 400 went into what was originally
the vault for a smale nuvclear reactor, which seems to be a really stable
site. The 200 moved upstairs and, until we modified the 300's dampers to
fit on it we saw a lot of vibration noise - the vibration peaks were a few
percent of full scale.
So it all depends on what the vibration level of the building is. Some are
pretty quiet and some aren't. Our new building seemed to have most of its
vibration from the blowers for the fume hoods so it was all fairly high
frequency and our "rubber tire" dampers work well.
Chris Johnston
J. Chris Johnston
Polymers Branch, Materials Division (216)433-5029
NASA Lewis Research Center (216)977-7132(fax)
21000 Brookpark Rd MS 49-3 James.C.Johnston@lerc.nasa.gov
Cleveland, Ohio 44135
http://polly.lerc.nasa.gov/MDWeb/5150/Polymers.html
Resistance is Futile!