Fortunately dewers have become a lot less expensive too. I'm not sure that we really need to be that concerned with the safety of LN2 while cars and ladders st

Fortunately dewers have become a lot less expensive too. I'm not sure that we really need to be that concerned with the safety of LN2 while cars and ladders still exist. For a SEM where LN2 is only going to get used in a cold trap or for flash freezing a sample, I think the HV risk dwarfs the LN2. ... or maybe the risk of a vacuum mishap causing a fire in the diffusion pump. (or, if it's using a TMP instead of a diffusion pump-- a vacuum mishap causing a rapid unplanned disassembly)