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Liquid Nitrogen

Liquid Nitrogen. Liquid Nitrogen. Bp : -320 ˚F (-196 ˚C, 77 K) E xpansion ratio: 1 : 694 Burns – s imilar to frostbite or thermal buns E xplosions ( Texas A&M, 2006; $~500,000) R elief valve was sealed shut Asphyxiation( 8 deaths/ yr in US)

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Liquid Nitrogen

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  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 valvewas sealed shut • Asphyxiation(8 deaths/yr in US) • Oxygen deficiency from not being able to breathe normally • Liquid N2ingestion (18thbirthday celebration, England, 2012) • Emergency surgery to remove stomach after drinking a cocktail containing liquid N2

  3. Liquid Nitrogen • Liquid N2 in the lab • 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 O2condensation 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. <http://www.liquidnitrogenservices.com.au/safety/ln2_msds_e1.pdf> • Asphyxiation with liquid nitrogen – hazard alert, Monash University. <http://www.monash.edu.au/ohs/topics/hazard-alerts/liquid-nitrogen-asphyxiation.html> • Standard operating procedure (SOP) for handling cryogenic (liquid nitrogen). <https://eee.uci.edu/programs/chemstockroom/SOP/Liquid%20Nitrogen%20SOP.pdf>

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