LN₂ Handling—Fact and Fiction

Extract

“I will be getting my first SEM/EDS shortly, and to obtain the required operating permit from my safety group, I need a written procedure for handling LN₂. Specifically I need a written procedure for filling the 3 L dewar on the EDS detector from a 50 L dewar mounted on a cart. I plan to make the transfer by using a lab source of LN₂ to pressurize the 50 L dewar and have obtained all the valves and fittings required to do this from another SEM lab. I would appreciate copies of the procedure.”

This question recently posed to the Microscopy List Server unleashed a flurry of comments, not only on the safety of various LN₂ procedures but on the safety of other materials as well. Also discussed was the necessity of formal LN₂ handling procedures.