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I want to retrieve cryotubes from the bottom of a liquid nitrogen freezer without taking all the freezer racks out and draining the liquid nitrogen. I think I can accomplish this using a tool like this but I am not sure how well the tool will function at temperatures as low as -160 Celsius. Also, this particular tool is probably only about half as long as it needs to be.

Assuming I can find a longer version of such a tool, how can I determine whether or not I need to be concerned about using to retrieve cryotubes from a liquid nitrogen freezer? My main worry is that parts of the tool may become brittle and break or that the claw's ability grab may somehow become compromised. I am not concerned about the metal becoming excessively cold because I will be wearing gloves intended for such work.

Is there a chart or other resource that I can use to get a sense of metal's shear strength at cold temperatures?

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Metals become brittle as low temperature (and that's why you cool your Parr bomb in a dry ice bath, never in liquid nitrogen when you condense gases in). But the worst thing that can happen is that a claw might break off, which shouldn't cause any damage to equipment. Why not try in a small dewar first. Liquid nitrogen is cheap.

A good alternative to racks of storage boxes are storage canes, such as these.

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  • $\begingroup$ Thats a good idea to experiment in a small dewar first. I assume steel is a good metal for this kind of tool to be made of because its durable but I have no real understanding of how much variety there is to how brittle metals become in cold temperature or how quickly metals become brittle. $\endgroup$ – Slavatron Nov 12 '14 at 23:00

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