• Rebecca Watson wrote a new post, Liquid Nitrogen Does NOT Turn Tear Gas Solid!, on the site Skepchick 4 months, 2 weeks ago

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    Transcript:

    Okay so the laptop I use to make these video has been in the shop for the past […]

    • I previously made this comment on the Patreon comments section, but suspect I did something wrong so I’m re-posting it here (more or less), mostly because it contain a major brag. 🙂

      A closed container (or one with only a small leak) of a liquid whose boiling point is below the external temperature can explode suddenly and with great energy when the liquid boils. This is called a Boiling Liquid Expanding Vapor Explosion, or BLEVE.

      The liquid can boil because the container is in a fire that heats the liquid above it’s boiling point. This is what often happens when tanker trucks or rail cars are involved in a crash or fire. The explosion is not caused by the flammable contents of the tank burning, though if the contents are flammable, it can make the results much more catastrophic. However, even water can explode this way. The Mythbuster’s launching a hot water heater through the roof of a house was a boiling water BLEVE.

      A BLEVE can also occur if the liquid’s boiling point is below normal room temperature and just heats up due to exposure to room-temperature air or water. This is what causes an uninsulated bottle of liquid nitrogen to explode, especially when it’s dropped in a bucket of water. (The water will warm up the nitrogen much more quickly than air would.)

      A strange case of a BLEVE is when the liquid in the tank is under great pressure. The pressure raises the boiling point of the liquid above surrounding temperature, so it won’t boil. However, if the tank springs a leak, the pressure will drop, and the boiling point will go down. When it drops below the external temperature, the liquid will boil and the tank will explode. I think this is what caused the high-pressure helium tanks to explode in both SpaceX Falcon 9 rocket explosions.

      If you look up BLEVE in Wikipedia, you’ll see my dad cited as one of the people who discovered and named the BLEVE. Woot!