Hello everybody,
Our EPR users run their experiments at low temperatures (6-20 K) and use
liquid helium for cooling. The special transfer line (Oxford) they use
allows them accurate flow control. However, the part of the transfer
line which goes inside the helium dewar is only 53 inches long. We
usually order 100 L tanks. Sometimes the dewars are just too high and we
are not able to use all of the cryogen. I've contacted several vendors
already and learned that there are generally three designs of 100 L
dewars used by major suppliers. When I place an order the vendor sends
me whatever is available at the moment. The specific type of tank seems
to be beyond their control.
I don't think it will be possible to install any extension on our
transfer line. Maybe we should switch to 60 L dewars (are they
shorter?). However, we want to use any leftover He after NMR refills for
EPR (and these are always 100 L tanks). The obvious (but too expensive)
solution would be to purchase our own "short" 100 L dewar.
Any other suggestions.
Piotr
Piotr Dobrowolski, Ph.D.
NMR/EPR Manager
Department of Chemistry and Biochemistry
Utah State University
0300 Old Main Hill, Logan UT 84322-0300
telephone: (435) 797-1673
fax: (435) 797-3390
Received on Tue Jun 21 2005 - 17:52:14 MST