I seek some advice relating to routine nitrogen fills of Bruker
magnet systems. Ours is a 400 MHz instrument.
The manual seems quite emphatic that the transport dewar pressure
be first dropped to no more than 0.35 bar (5 psi) prior to transfer.
That's a lot lower than the way it comes (10-25 psi). It takes
quite some time (and a very lot of noise) to get it down to that
pressure, and once there, at least by the gauge on our dewar, there
is essentially 0 transfer rate. Filling has taken an hour, and that
was only by increasing the pressure in the dewar. This seems quite
excessive to me.
Questions:
1) How long does it take to fill your cryostat with liquid nitrogen?
[ ] 300 MHz
[ ] 400 MHz
[ ] 500 MHz
2) Do you drop the pressure in the transfer dewar to 5 psi as specified?
3) How do you judge that the transfer is occurring at a satisfactory
rate?
(Exhaust looks like..., etc.)
Thanks.
Bob Hanson
--
Robert M. Hanson, hansonr_at_stolaf.edu, 507-646-3107
Associate Chair for Curriculum, Department of Chemistry
Associate Professor of Chemistry, St. Olaf College
1520 St. Olaf Ave., Northfield, MN 55057
mailto:hansonr_at_stolaf.edu
http://www.stolaf.edu/people/hansonr
Received on Fri Jan 03 2003 - 16:16:02 MST