Re: nitrogen

Dear Michael Moroney:

"Michael Moroney" <moroney@xxxxxxxxxxxxxxxxxxxxxxx> wrote in
message news:ers9lc$qo5$2@xxxxxxxxxxxxxxxx
Salmon Egg <salmonegg@xxxxxxxxxxxxx> writes:

On 2/24/07 7:22 PM, in article
Hh7Eh.19053$Mp2.6443@xxxxxxxxxxxx, "N:dlzc
D:aol T:com (dlzc)" <dlzc@xxxxxxx> wrote:
....
Nitrogen is also used cryogenically. Someone want to
freeze sperm or warts or make frozen sections for the
pathologist. It is also necessary for MRI to keep the
cryogenic helium from evaporating too fast. Anything
requiring a good vacuum, such as an electron
microscope or a linear accelerator, will need liquid
nitrogen.

I suppose a hospital may have an air liquification facility
onsite to produce the oxygen it uses. The liquid
nitrogen mey be a byproduct it sells.

I wouldn't think even a very large hospital complex would warrant
the necessary multi-tons a day of production capacity, and the
team of associated maintenance folks, to warrant cryogenic
production. VPSA and PSA are much less labor intensive, and only
slightly more expensive (per pound of product) than cyrogenic...
and (pure) nitrogen is not a byproduct of the PSA/VPSA process.
Just an air stream that is depleted of oxygen (around 14% rather
than 21%).

David A. Smith


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