Hello All,
I have been following the thread on hygienic behavior.  If we follow Allen's
advice (and Steve Tabor's before him) a number of folks will be using, or
attempting to use liquid nitrogen (LIN).  I think the information on Allen's
website is excellent.  I just want to talk a little about the safe handling
of the product.

There are two major hazards associated with LIN.  First, the obvious, cold
temperature.  LIN can freeze flesh on contact.  The best protection comes
from LOOSE FITTING leather gloves thick enough to offer cold protection.
Leather welding gloves are excellent for this.  There are also some
leather/polyester combination gloves sold for handling cryogenic products.
It is important that the glove is loose fitting.  In the event that you
spill (and you will) or come in direct contact with the LIN it is important
to quickly remove the glove.  You can shake off a loose fitting glove with
one hand.  If the glove is tight, the time spent trying to remove it can
allow a burn to occur.  (Cryogenic "burns" are painful).  Do not use plastic
or rubber gloves as they offer little thermal protection.  When pouring the
LIN it will spatter and splash, similar to a drop of water on a very hot
pan.  For this reason I highly recommend using safety glasses.

The other hazard is the liquid to gas expansion ratio.  One volume of LIN
will expand to 697 equivalent volumes of gas.  This is a major concern when
working in a confined space where the oxygen can be displaced by the
nitrogen resulting in an asphyxiation hazard.  If you are working outside,
or in areas of good ventilation this hazard is greatly reduced.  However,
this expanding gas will build pressure rapidly if confined.  There was a
suggestion that LIN can be transported in a coffee thermos.  Although they
are not sold for that purpose I suppose they work, although I would not use
a plastic one. At cold temperatures the plastic will become brittle and
break. Most importantly, DO NOT SEAL THE THERMOS with its cap.  A piece of
loose fitting Styrofoam with a small vent hole can be safely used as a lid.
This will allow the expanding gas to escape without building pressure while
keeping the liquid from spilling out.  Periodically check to ensure it is
loose and has not become a frozen plug.

For additional safety information on liquid nitrogen you can visit the below
website.

http://www3.airproducts.com/productstewardship/product-safety/safetygrams/sf
grm7.pdf


For a liquid nitrogen material safety data sheet (in Microsoft Word format)
visit:
http://www3.airproducts.com/productstewardship/product-safety/msds/lookup.as
p?letter=N

To get a faxed copy of the MSDS:
http://www3.airproducts.com/productstewardship/product-safety/msds/

I hope this information is helpful.

Ron Bogansky
Kutztown, (eastern) PA, USA

Although I hate disclaimers:
The above information and opinions are my own and are not associated with
nor do they reflect that of my employer.


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