Hi All,
There was a similar thread started back in October but I wanted to again get
the group's experiences with liquid nitrogen boil off used for
instrument/probe gas requirements. Specifically, I am trying to gauge the
actual amount of product (liters of liquid/gas) that a particular instrument
needs per day. Due to pretty hefty budget cuts at NIH in the past 4 years,
we sought a cheaper solution than a standard bulk tank to replace compressed
air to our two instruments (INOVA systems, 400 and 500 MHz). We finally
settled on a 1000 liter Micro-bulk (Perma-Cyl) tank from Chart. My very
rough calculations led me to believe that this would be sufficient for at
least a week of use with some residual. However, I was wrong since we are
gobbling up > 200 L/day which necessitates twice weekly fills. The 400 is a
routine use machine (~20 users per standard work day) and the 500 uses much
less product (no spinning, infrequent eject/insert cycles).
My questions are the following: 1) For those of you with similar equipment
and who actually gauge this stuff, Is this standard usage? 2) How have you
tried to economize on gas usage? (I received some useful comments from
George Sukenick on this topic in October and just would like some other
ideas). My wish would be to keep the usage to ~100 L/day so we only need to
fill on a weekly basis. The gas is used for supply (probe cooling, VT and
spinning), eject, to raise the TMC legs (which should not consume after they
are raised) and a tiny amount for the coil gas.
I would also like to avoid returning any of the usage to compressed air if
possible (except perhaps for the TMC legs). We have looked very carefully at
the tank itself and it seems to be fine with no leaks in any of the piping
(shutting off the supply to the instruments overnight while valves on the
tank are open consumes almost no gas)
Thanks!
Cheers,
Joe
Joseph J Barchi Jr. Ph.D.
Laboratory of Medicinal Chemistry
National Cancer Institute Frederick
376 Boyles Street, PO Box B
Building 376 Room 209
Frederick, MD 21702
301-846-5905
301-846-6033 (FAX)
barchi_at_helix.nih.gov
Received on Tue Jan 18 2005 - 09:04:43 MST