1. Liquid Nitrogen

2. Liquid Nitrogen Bp: -320 ˚F (-196 ˚C, 77 K) Expansion ratio: 1 : 694
Burns – similar to frostbite or thermal buns
Explosions (Texas A&M, 2006; $~500,000)
Relief valve was sealed shut
Asphyxiation( 8 deaths/yr in US)
Oxygen deficiency from not being able to breathe normally
Liquid N2 ingestion (18th birthday celebration, England, 2012)
Emergency surgery to remove stomach after drinking a cocktail containing liquid N2
More on the Texas A&M 2006 incident:
The cylinder had been standing at one end of a ~20' x 40' laboratory on the second floor of the chemistry building. It was on a tile covered 4-6" thick concrete floor, directly over a reinforced concrete beam. The explosion blew all of the tile off of the floor for a 5' radius around the tank turning the tile into quarter sized pieces of shrapnel that embedded themselves in the walls and doors of the lab. The blast cracked the floor but due to the presence of the supporting beam, which shattered, the floor held. Since the floor held the force of the explosion was directed upward and propelled the cylinder, sans bottom, through the concrete ceiling of the lab into the mechanical room above. It struck two 3 inch water mains and drove them and the electrical wiring above them into the concrete roof of the building, cracking it. The cylinder came to rest on the third floor leaving a neat 20" diameter hole in its wake. The entrance door and wall of the lab were blown out into the hallway, all of the remaining walls of the lab were blown 4-8" off of their foundations. All of the windows, save one that was open, were blown out into the courtyard.
More 18th birthday celebration :
if swallowed, liquid nitrogen can cause cold burns to the mouth, throat and stomach, killing the tissue.
As the frozen vapour hits the stomach it rapidly warms, releasing large volumes of air which can burst the stomach.

3. Liquid Nitrogen Liquid N2 in the lab Liquid oxygen is pale blue
Can solidify with a vacuum pump (mp 60 K)
Can condense oxygen (bp 90 K)
Liquid O2 can cause explosions
Don’t leave liquid nitrogen traps open to atmosphere!
If liquid O2 formation is suspected, alert other sto the danger and evacuate the area.
Allow the vented system to warm to room temperature
Can condense argon
Use nitrogen gas instead
Liquid oxygen
is pale blue

4. Controls
Always wear appropriate PPE (cryo gloves, lab coat, and goggles) and never allow any unprotected part of the body to come into contact with LN2 or any uninsulated vessels or pipes.
Do not overfill vacuum flasks and never store LN2 in a sealed container at a temperature above the BP of LN2.
Always inspect and maintain vacuum flasks. If they are cracked, they may fail explosively.
Eliminate sources of ignition around the LN2. The risk of O2 condensation is also reduced when working with smaller quantities of LN2.
If pale blue liquid O2 is seen, remove LN2 traps (if any), flammables, and any ignition sources and let O2 boil off slowly.

5. References
Material Safety Data Sheet: Nitrogen, Refrigerated liquid. <
Asphyxiation with liquid nitrogen – hazard alert, Monash University. <
Standard operating procedure (SOP) for handling cryogenic (liquid nitrogen). <