Ask A Scientist© Chemistry Archive

name         Elizabeth T.
status       other
age          40s

Question -   Our daughter is currently on liquid ozygen 24 hours a
day.  She likes to go snowmobiling, as a passenger.  Will the oxygen be
okay outside in cold weather?  I realize that oxygen is very cold in
order to become a liquid and feel that this is not a problem.
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I assume you mean that oxygen gas is generated from liquid oxygen which is
stored in a portable dewar [vacuum insulated flask]. Outside cold weather,
of itself, will not affect the liquid oxygen.

However, in addition to the obvious concern in case of an accident, the
effect of low temperature on pressure regulators, valves, plastic tubing,
O-rings, and other parts would have to be considered very carefully.

Recall that several years ago a rather modest low temperature caused a space
shuttle disaster because a critical O-ring failed due to barely freezing
temperatures.

Vince Calder
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You are probably correct.  Liquid oxygen is so cold that even the
temperature outside on a bitterly cold day is very hot by comparison.
However, I am not sure how the oxygen Dewar (the insulated cylinder holding
the LOX) dispenses its contents.  If it just dispenses the boil-off from the
top, it may depend on a certain rate of heat flow from the outside to
maintain the oxygen flow.  If it dispenses liquid O2 from the bottom which
flash-evaporates on exit, you're fine.

Your best bet is to start by going on short trips and seeing how the flow
holds up.  If it is good, increase the time outside until you are sure there
are no problems.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois
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