"It is a VERY bad idea to secure the lid on a LN2 flask except during temporary transport. Otherwise what you will have is a bomb."
Well, that depends on the lid...
A non gas tight lid is fine, it stops it spilling if accidentally knocked over, reduces losses and doesn't result in a pressure buildup.
However leaving an open dewer in front of a door is genuinely daft...
Biting the hand that feeds IT
