>>> A thermos _is_ a dewar flask. See if you can round up enough for the
>>> A thermos _is_ a dewar flask. See if you can round up enough for
>> 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
> 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
# United Kingdom
# CB2 1EZ
# 'phone: +44 1223 336015
# fax: +44 1223 336033