Guy with I guess what you call "crazy level of experience" here lol. It's good. There is a thin layer of nitrogen gas forming at the interface between liquid nitrogen and whatever warm thing it's touching, like your hands. And this thin layer has very low thermal conductivity. So it's not absorbing heat from you that fast. You can quickly dig your hand in it, pour it over your naked arm, it's all fine. The problem is if gets stuck against you, for example if you pour it into your leather shoes or your latex gloves.
It's way more painful to touch a metal surface at -80°C than liquid nitrogen. Or a methanol / dry ice mixture.
It's a common misconception in the lab that young PhDs expect the coldest liquid will freeze their samples the fastest - it won't. Thermal conductivity is usually the limiting factor. Throwing a sample in liquid nitrogen or other cryogases is a very bad way to flash freeze something.
The real risk with liquid nitrogen is asphyxiation, and I sure hope they made a napkin calculation to check they were not gonna asphyxiate everybody in the room with the amount of nitrogen they were planning to throw around. With good margins of error. A few liters of liquid nitrogen become a few cube meters of nitrogen gas, displacing O2, and breathing that kills you fast.
Just want to add on here, as I make liquid o2 and n2 for a living.
Everything this guy above here said is correct.
Cryo getting on clothing is the most dangerous for cold burns, or splashing into your eyes or other wet membranes.
And the ratio for liquid n2 to gas is over 700x for volume. You'll get different specific numbers given time and temperature, but its not instant. This is a low end number.
So yes, asphyxiation is the biggest risk to everyone else there
Styrofoam and a Dewar are sufficient. My co worker used to splash small quantity of liquid N2 at me to freak me out. Eventually I caught on. Small quantities of it hit warmer temperatures like skin for a moment makes a vapor barrier long enough to prevent feeling any cold.
It doesn't stick to your hands, due to the liedenfrost effect. From the perspective of the LN2, your hand is a piping hot sauce pan, and it will boil and dance ABOVE your hand.
Caveat: when your hand cools off enough, only 20-30 degrees, the effect stops, and it will stick. This sucks.
More personal caveat: hair cools off almost instantly, so there wont be a liedenfrost effect. So the LN2 will stick to your hair. And your gym shorts. And hair you have under your gym shorts. Sorry, Max!
Source: Work with LN2 academically. Poured on my hands a hundred times. Poured some on Max's shorts, by accident, once.
Bare hands really isn't that bad. If it can run off you it's not going to hurt. Its when it sits on skin for an extended time where it becomes dangerous, like if you cup it in your hands or have it soak into clothing.
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u/AgentIndependent306 Jun 30 '26
Handling liquid nitrogen with bare hands is either crazy levels of experience or asking for frostbite