Found a scary sign today… (Patreon)

You know I have an affinity for scary warning signs, and today I glanced at my LN2 dewar and saw this.

Because pretty much everything in the universe is warmer than LN2, it will always boil away and create a lot of gas. This is why dewars are never fully sealed — they’d eventually all explode.

That gas then inevitably leaves the dewar and escapes into the environment. If you’re not careful, i.e., if the room is small, sealed, no ventilation, then the nitrogen displaces the O2 in the room, and that can…well…kill you.

This sign is also the reason why Allen Pan told me to open my car windows when traveling with the dewar.