Re: N2 gas

Jane Strouse (mjs@argon.chem.ucla.edu)
Fri, 24 Feb 95 08:43:10 PST

>AMMRL,
>
>Our house nitrogen is being shut off permanently by the end of this month.
>We plan to use the boil-off from two 5-foot-tall N2 dewars which we'll plumb
>into the old house N2 lines in our lab facility. Has anyone else had
>experience with setting up an isolated, stable nitrogen gas delivery system
>in your NMR lab/facility?
>
>Also, if you purchase liquid nitrogen to be used as the spectrometer gas
>supply in the form of N2 boil-off, how do you recoup the cost of the N2
>liquid? Do you charge facility users, and if so, what charge scheme has
>worked best?
>

We also use the Balston air drier/filter systems for all the NMR
spectrometers. However, should you want to use variable temperature with a
liquid nitrogen bath you will need to switch over to nitrogen gas for
spinning, etc. Therefore we have a nitrogen manifold in addition to the air
manifold. There are labeled manual valves on the wall at each spectrometer
to accomplish the switching. We purchase 160 liter tanks of liquid nitrogen
with a heat exchanger that delivers room temperature nitrogen at approx. 200
psi. (I have heard these variously referred to as "VGL's" or "gas packs".
I am sure your liquid nitrogen supplier would know what they are. We use 2
of these attached to an Air Products "LC-91 Liquid Gas Manifold System"
which will automatically switch to the second dewar when the pressure in the
first drops too low.

Jane Strouse
Dept. of Chemistry
and Biochemistry
UCLA