• NuXCOM_90Percent@lemmy.zip
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    3 months ago

    I mean, it’s funny and ironic in that Alanis Morrisette kind of way. But it actually makes sense.

    Fire hydrants are heavily engineered hunks of metal. Metal getting rammed into at speed is a great way to generate sparks. And lithium fires are scary as hell. There is areason ANYONE futzing around with lipos should have a bucket of sand handy and why, as the article states, first responders need to handle these specially.

    It is a similar principle as to how you don’t pour water on a grease fire.

    • ch00f@lemmy.world
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      3 months ago

      Ok a few things:

      Batteries don’t need “a few sparks” to catch fire. They will generate plenty of heat if punctured and self-ignite.

      You don’t pour water on a grease fire because grease floats and it will spill out of your pot and catch the rest of your kitchen on fire. Also the water will boil and splatter oil everywhere.

      Also pouring water on a battery fire is the preferred way to put it out. Many of the chemicals in the battery will release oxygen when heated, so the best way to put it out is to cool it down as much as possible by dousing it with a shitload of water. It isn’t always possible to apply enough water to the core of the fire which is why they are hard to put out. Sand won’t do anything because the fire is self-oxidizing.

      Yes lithium metal reacts with water, but that’s not what makes batteries hard to put out.

      • Lost_My_Mind@lemmy.world
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        3 months ago

        Well now I don’t know WHO to upvote. Guy before you sound smart. You sound smart too! Me dumb! Me bang rocks together!!! RAAAHHHH!!! RAHHH!!! BORED! BORED! RIP OWN HEAD OFF!!! RAAAAWWWWWW!!!

      • hikaru755@lemmy.world
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        3 months ago

        Sand won’t do anything because the fire is self-oxidizing.

        From my understanding the recommendation to have a bucket of sand around when handling lithium batteries is not to put the fire out with it, but to have something to throw the battery into that’s not gonna catch fire as well, and then to carry the whole bucket somewhere where the battery can just burn out on its own. Is that wrong?

        • LowtierComputer@lemmy.world
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          3 months ago

          Yes and no. I think.

          What I was taught was to dump the battery in the sand and cover it in sand. Then drench with water if possible. This also keeps the now toxic water from reaching a drain.

      • boaratio@lemmy.world
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        3 months ago

        I worked at a lithium ion battery company for 11 years. Water won’t do it. When ruptured, a lithium ion battery goes into something called thermal runaway. You need to use CO2 fire extinguishers to cool the batteries to get the fire to stop. Otherwise, it will burn until all the energy is used up. I suppose it’s possible to use water that’s cold enough to stop the reaction, but I highly doubt it.

        • ch00f@lemmy.world
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          3 months ago

          Water turning into steam soaks up an enormous amount of heat. I assume that thermal runaway happens somewhere above 100C, right?

          CO2 extinguishers work by displacing oxygen, not by cooling.

          • nilloc@discuss.tchncs.de
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            3 months ago

            The rapidly expanding co2 does get very cold though. It’s not any different from freezing things with compressed air cans.

            I don’t hover, know which would absorb more heat per pound though. Someone who knows more math than I can do it though.

            • ch00f@lemmy.world
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              3 months ago

              If I’m reading Wikipedia correctly, it takes 348 Joules of heat to boil a gram of CO2.

              Water is 2257 Joules per gram. As long as you don’t need anything cooled under 100C, water is the way to go for cooling. It’s also a hell of a lot cheaper and easier to deal with than liquid CO2.

      • dorron@lemmy.world
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        3 months ago

        You don’t pour water on a grease fire because grease floats and it will spill out of your pot and catch the rest of your kitchen on fire

        I expect you know as you were mainly talking about batteries (on this post about batteries) - but grease fires are not quite dangerous just because grease floats and adding water causes it to spill fire - when you introduce the water it does sink, but then it superheats to vapour, rapidly expanding and almost erupts the oil, chucking a poor man’s napalm round everything in the vicinity

        It doesn’t have to even be on fire, if the oil is >100 degrees and there’s enough of it to superheat adding water will do the same thing (minus the flames) - a melted face is better than a melted face and a house fire, but neither are recommended

      • Albbi
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        3 months ago

        I’ve heard plenty of times to never use water on a grease fire, but never learned why or what happens if you do. Thanks for that!

      • takeda@lemmy.world
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        2 months ago

        I’m wondering if EVs shouldn’t have mechanism where if fire is detected the bottom part (which holds the batteries) would simply separate and fall to the ground exposing the batteries to firemen and making it easier to stop the fire.

        • almost1337@lemm.ee
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          2 months ago

          Sounds like it could also work as a hot-swap battery pack, where you could drive up to a carwash style apparatus which takes your low charge battery and puts in a fully charged one.

        • Longpork3@lemmy.nz
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          2 months ago

          In the majority of cases, its still going to be stuck under a mangled car that you cant move because it is on fire. A better solution might be to route multiple ‘flood tubes’ to the battery compartment and place them in easy accessible places. That way you would just need to pop pff an access panel and hook up a hose.

        • ch00f@lemmy.world
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          2 months ago

          Could help, but could also add a lot of weight and complexity to handle an issue that is exceedingly rare.

          Do ICE vehicles ever eject their gas tanks?

      • NuXCOM_90Percent@lemmy.zip
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        3 months ago

        Yes. Apologies. I did not do a proper deep dive as a “Well ackshually” response to a joke post. I will endeavor to do better in the future.

  • Empricorn@feddit.nl
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    2 months ago

    “You know what this life-saving water needs? Some fire!

    –Xitter’s Elon Musk, probably

  • azimir@lemmy.ml
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    3 months ago

    I like the main debates in this thread are about how to put out battery fires, not any defense of the Cyberdump. We really do focus on what truly matters some days.

  • BruceTwarzen@lemm.ee
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    3 months ago

    I love how the featured article is: cybertruck got turned into a warthog with a working machine gun. At least something is working.