'dry' nitrogen dewars

Chris Hosfield chris at U16.N104.QueensU.CA
Sun Sep 20 22:51:42 EST 1998

Dear All,

Our lab is interested in purchasing a 'dry' nitrogen dewar for transportation of protein crystals
by FEDEX to remote synchrotron locations.  The listed temperature for such dewars are -150 degrees
celcius.   Our lab generally uses propane to freeze/store the crystals for trips to synchrotrons
within driving distance, and we were wondering if anybody uses these dewars for transporting
crystals in some sort of solid environment, as propane is when submersed in liquid nitrogen.  At
-150 degrees, propane is a gas, and even is a liquid.  Even nitrogen is gaseous at that
temperature.  Thus, I have a few questions:

1.  Is it possible to use a 'solid' chemical, like propane?
2.  If not, and if only nitrogen is used, won't the crystal (frozen in the cryovial) sustain any
damage since there is no liquid/solid solution surrounding it??
3.  If propane is possible to use somehow, does FEDEX even accept it??
4.  Which companies are the best suppliers of these dewars...ie. cost/quality, etc.

I thank you in advance for your replies,


Chris Hosfield
Queen's University

please reply to:  chris at crystal.biochem.queensu.ca

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