A new crash recently in Alabama, but a reminder to something that we all know. Burning Teslas are far more difficult to extinguish than any other car.
A new crash recently in Alabama, but a reminder to something that we all know. Burning Teslas are far more difficult to extinguish than any other car.
So there’s basically two phases of an EV Fire.
The initial fire, a blazing hot heat that’s dangerous – You just hit it with water from a distance. You’re correct on the analysis here.
The “reignitions”. Li-ion batteries, once damaged, will reignite spontaneously for hours after the initial fire. So the fire “has been put out”, but we all know that its only for a few minutes. There’s enough time to winch the car into these containers and fill it up with water in practice.
Its #2 that you’re probably missing. Water / Foam / etc. etc. is only good at stopping phase 1 of the fire. But the next 8+ hours, you need someone to babysit the fire with a hose and keep dribbling water on it before the fire is permanently put out. Or… you know… do like a European and use a container and fill it with water, so it can babysit itself.
Sand and some types of foam prevent #2.
The person would be at risk while rigging it up, you would have to stop spraying while getting it into the box, giving it time to reignite while the person is right beside it.
This is like those fire suppression grenades, great concept, but fails in theory since they are massive safety concerns to go with them.
And it can’t babysit itself, the FD would still be onsite while the vehicle sits in the tub, just let it burn off at that point and than it’s dealt with in a couple hours.
I don’t see Europe actively using these from any research I’ve done, just a few concepts and nothing more. Since it’s a safety concern to be able to use these.
Do you have a demo of this working? A .pdf report on the amount of sand and/or foam needed to achieve this?
European fire-departments are moving towards this full-submerge tactic because it works. Its one of the big developments in firefighting technique over the last 5ish years.
When we’re dealing with 1000lbs / half-ton battery packs, the sizes needed to actually effect these fires grows dramatically. I don’t think that fire-departments will be in the business of carrying dumpsters full of sand to try to extinguish these fires… but I dunno, if you got some numbers on the quantity of sand needed to achieve the suppression of the fire we can compare notes.
Yes plenty of places in the states have sand as their official policy. No real difference than your water container than for the sand container, but you can also just cover it without the container as well, this is the preferred method for personal safety, just would need more.
Same is also easier to remediate than the water as well, some places use wet sand. Best of both worlds, but still need to remediate the water.
How does sand stop the internal exothermic reaction, though? I could see wet sand maybe, but just straight sand? It’s not a normal fire and is self-sustaining.
Wouldn’t the transport and storage of the sand be prohibitive?
Why would it?
Weighs less and is easier to store and transport than water. Also what about places that freeze? Gonna have an ice cube with a car in it after.
Not every place is with it easy access of fire hydrants, what about the middle of a highway? Both water and sand would essentially be equally cumbersome to get there.
What? Sand weighs in at about 13 pounds/gallon. Water is under 9.
While storage may be easier in some ways (you can just have a giant pile), you’d have to add storage spaces for it compared to the already ubiquitous water supplies like reservoirs, lakes, ponds, rivers, etc that a pump can fill up a fire tanker/tender with.
Then you run into how the hell the sand gets ON the fire. You can’t just pump sand on through existing equipment, that’s for sure. And, pumping sand is brutal on the equipment that’s designed for it. So you’d have to not only buy new trucks just for sand, but the upkeep is going to skyrocket.
As far as highways go, there are some places where hydrants are available along the route because highways are usually planned. And, again, that’s why they have tanker/tender trucks to bring in water in the thousands of gallons instead of the hundreds a regular fire truck carries. It isn’t any more cumbersome than handling a fire way out in the country with no hydrants.
Sand, there’s no such thing as hydrants at all. You CAN’T have them. You don’t have the flexibility of infrastructure to set up sand depots either, not reliably.
As far as freezing, that would be a good thing. The entire point is to bring down the temperature of the battery below the point where it is self sustaining. Which sand can’t do by itself in the first place. But, even if you did end up with a frozen block of ice (and you won’t because you don’t freeze a thousand gallons of water in a few hours, though you might get a small amount on top), that’s just a matter of patience.
Not that a shit ton of water that’s specifically there to suck up the heat is going to freeze faster than the battery reaction can heat it. You pump the water, you let it work, you let the water drain out. Boom. Minimum cleanup because you either pump the water back into a tank and transport out, or (where safe and realistic) just let it run off by itself.
You get a tank full of sand, you have to move that sand. It won’t flow away by itself. You can’t pump it back into a tank the same way you can water (it is possible, but it’s a damn sight more complicated and expensive).
I know not all of this is intuitive, but do you not know any firefighters? They have a lot of options for fires of various types. This includes sand, but sand just isn’t practical or useful for the vast majority of fires where smothering is going to work right. It’s just not efficient enough to be a primary, or even secondary secondary tool.
And that’s the other big issue. Sand isn’t a fast cooling thing. It isn’t going to work right for a battery fire. Again, you can’t smother them, they’re self oxidizing. That’s the entire reason for the extra efforts. Most car fires, they’re out in minutes (less if they’re small). Battery fires are so bad because you can’t extinguish them like you can with most fuels like gasoline. Sand just doesn’t pull the heat away fast at all. It even holds the heat as it pulls it from the source because the molecules involved are not able to move enough to do it. Water being a liquid is more efficient at that.
Just because some places freeze does not mean that all of the water will turn into an ice cube. Water freezes from the top, which then acts as an insulator for the liquid below. This is how ice fishing is possible. Are you just throwing objections at the wall to see what sticks?
A better objection with regard to freezing would be the fact that leaking water all over a highway presents a road hazard to other drivers. In which case, yes sand might be the better option. That’s why we have different methods for fighting them.
Water freezes from all sides… who told you that?
Rivers freeze from the top since the ground heats the bottom and sides….
How long do you seriously think it takes thousands of gallons of water to freeze? Especially with a heat source they are trying to extinguish? Can you seriously not accept that there are professionals who know a lot more about this than you?
Every fire puts a firefighter at risk. That’s not a valid argument. This system does not require a person to stand right next to the fire. That’s why the box is deployed by a mechanical arm.