transporting liquid nitrogen

Dr H.R. Powell hrp1000 at CUS.CAM.AC.UK
Tue Jul 25 06:27:05 EST 1995


>>> A thermos _is_ a dewar flask.  See if you can round up enough for the 
trip.
>>> A thermos _is_ a dewar flask.  See if you can round up enough for 
the trip. 

>> Have you actually tried this? It could be bad advice to recommend this
>> if you're not sure it'll work. Two things that might go wrong: first,
>> the thermos might break immediately from thermal shock. Second, it
>> might break somewhere en route due to material brittleness at low
>> temperatures.

> I have tried it on numerous occasions.  It works.  I use a
> stainless-steel thermos; I suspect you wouldn't want the kind with a
> glass interior.



Sorry to go on about this, but the GLASS thermos flasks that you get from 
Woolworth's, K-Mart etc SHOULD be perfectly okay for liquid nitrogen 
storage/transportation; I used them (along with all the other synthetic 
chemists in the lab) for putting on cold traps on my vacuum line for 
two years whilst post-doccing; in that time we didn't have a SINGLE 
breakage due to thermal shock etc. The only time any broke were when 
someone dropped one or dropped something heavy and hard into one.

I don't think the brittleness of glass increases that much at cryogenic 
temperatures (most glasses are pretty brittle at ambient temps!), so I 
don't think this is a worry.

If you follow the normal safety rule when using glass dewars, you are
unlikely to have a big enough thermal shock anyway (i.e. pour about 15 -
25 ml of liquid nitrogen into the vessel, let it evaporate completely,
then carefully fill up the container). 

# Harry Powell
# Cambridge Crystallographic Data Centre
# 12 Union Road
# Cambridge
# United Kingdom
# CB2 1EZ
#
# 'phone: +44 1223 336015
# fax:    +44 1223 336033






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