fts cooler
Moobery (esm@nmrfam.wisc.edu)
Tue, 17 May 94 16:18:10 -0500
At NMRFAM we have used 4 fts coolers for years with great success. We
use them with our 400, 500s, and 600 spectrometers. We've run then for
weeks and months continuously at minimum temps of -20C and up to 50 C, i.e.
biological samples. We constructed solid supports to the legs of the
magnets, the 6 foot long tube usually provides adequate vibration
isolation. We originally bought the coolers with a two stage compressor
but found we could not get dry enough air (-100 F dewpoint is 1 ppm
water) so we had them converted to single stage compressors. (You
can now buy the single stage units.) A short piece of plastic tubing
with foam insulation and a glass ball joint works well enough to
connect to a standard Bruker probe. The inlet air should be about
20 C below the desired sample temperture for optimum regulation. (this
number was mentioned at a Bruker user meeting). It might be useful
to control the cooler temperature from the console for automated VT
runs although we haven't done this. Ed Mooberry NMRFAM