The only certainty in dousing an electric-vehicle fire is that there are no certainties
I now know more about fire engines than I ever thought would be necessary. For instance, did you know fire trucks and fire engines are not the same thing?
An engine, as it turns out, is the vehicle that carries and pumps the water; a “truck,” on the other hand carries hardware, emergency gear, and perhaps the ladders required to reach the upper floors of tall buildings, but no water.
I also know, mainly because I couldn’t believe the numbers that I am going to spring on you, that fire engines generally hold between 500 and 1,500 gallons of water.
The norm is about 750 gallons, but let’s be generous — and also avoid some difficult math down the road — and call it an even 1,000.
The reason you’re going to need that long division is that, according to an article by the International Association of Fire and Rescue Services — which quotes Austin Fire Department Division Chief Thayer Smith — it can take as many as 40,000 gallons of water to completely extinguish a roaring Tesla fire.
That is — and now you see why I rounded up — equivalent to 40 fire engines. Even the lowest estimate I could find for extinguishing an EV — 8,000 gallons — would challenge any fire department, if some kind of reservoir wasn’t close by.
More numbers: First, the average fire truck typically pumps somewhere around 200 gallons of water a minute through a one-and-3/4-inch hose. Some more long division says it would take one truck more than three hours — not to mention a hydrant — to pump that much water.
And, even then, said fire might not be out. EV battery fires can smoulder for hours before reigniting.
So much so that the International Association of Fire Chiefs suggests that not only must towing services be alerted to the possible dangers of re-ignition, but that there should also be “50 feet of clear space around the vehicle once stored.”
One salvage operation in California found that out the hard way, a Tesla Model X, its flames long thought dormant, re-igniting six days after it was tossed onto the junk pile.
Another number: A typical internal-combustion engine, if ablaze, takes about 500 to 1,000 gallons of water to fully extinguish. In other words, one truck — er, engine — should be good enough.
I also did a little rudimentary research, and it would seem that a small to moderate house fire might take as little as 1,500 to 3,000 gallons to extinguish.
In other words, if your local FD has two engines, they might not even have to break open a hydrant. A real doozy, meanwhile, might take 20,000 gallons. But that is only for large fires — and I quote — “that take hours to control.”
All manner of innovative methods have been tried to temper EVs’ “runaway thermal events.” For instance, one oft-recommended technique is to literally submerge the whole car in water and just leave it there.
Of course, any container large enough hold a car — like a sea-can — is going to bring its own impracticalities.
One quick-thinking team of fire fighters in Sacramento, California, confronted with another Tesla that would not go out, tilted the offending Model 3 on its side, dug a pit beneath it (targeting the part of the floor that housed the battery), filled the pit with water, and then just tossed the Tesla into the hole.
Whatever the machinations, you don’t need to be a fire chief to understand that none of these systems are particularly practical. Too much water is needed, and the equipment required is not easily transportable, not to mention that digging a pit beneath a flaming car is not always within the realm of possibility.
It can take as many as 40,000 gallons of water to completely extinguish a roaring Tesla fire — equivalent to 40 fire engines
Finding a solution, however, requires addressing the root problem surrounding the difficulty in tamping down “runaway thermal events.” And the reason that so much water is needed — and why submerging, at least currently, is the only truly reliable method of confirming the kill — is that, in hosing down an EV, you are only cooling down the exterior of the fire.
Or, more accurately, the shell. An EV fire happen on the cellular level, by which I mean within the battery’s pouches or cylindrical cells. But those are housed inside the battery’s casing. So, while the inferno rages inside the housing, fire fighters are only cooling the outside.
Hence why so much water is needed. Or why the darned things keep reigniting. You’re never directly attacking the heat source.
New methods are, however, being found to both minimize the amount of water — and time! — need to control the blaze, and also make said extinguishing more reliable.
The first, as per Motor Trend magazine, is the Swedish ColdCut “Cobra” system, which uses an Ultra High Pressure Lance (UHPL) with more than 4,000 pounds of water pressure — along with an abrasive material — to cut through the battery casing to get direct access to the enflamed battery cells.
The Cobra is as much sandblaster as fire extinguisher, and tests by the Swedish Civil Contingencies Agency claim a Toyota Hilux-mounted Cobra can stop an EV fire from spreading in fewer than 10 minutes and using but 60 gallons of water.
Even more efficient and innovative is Rosenbauer America’s Battery Extinguisher System Technology (seen in the video below).
Another high-pressure system, Rosenbauer’s BEST uses about 600 psi of pressurized air to punch a spike through the underside of the battery casing. Then it’s just a simple matter of flooding the interior of the battery pack.
Ernie Young, a sales specialist with Rosenbauer — a South Dakota company that manufactures fire engines — told KELO-TV that dousing a battery fire then requires as little as eight gallons of water a minute, about the same as the average garden hose.
That reduced volume of H2O comes in handy when an electric car catches fire on the highway, says Young, “where there’s no hydrant.”
There are many lessons to be learned here, but one of the most logical would be that it probably behooves us to engineer electric-vehicle crashworthiness significantly better than that of ICE-powered vehicles.
Insurance companies, as recently discussed, are so worried about the dangers of damaged batteries that they are writing off EVs if the battery’s outer casing is but scratched.
The second thing we need to truly appreciate are the firefighters who have to try to contain these incredible conflagrations. A lithium-ion blaze emits fumes noxious even by fire standards.
By Tesla’s own reckoning — its on page 20 of its Emergency Response Guide — a burning battery releases sulfuric acid as well as oxides of carbon, nickel, lithium, copper, and cobalt. It says first responders “should wear full PPE including a SCBA [self-contained breathing apparatus].”
It’s also worth noting that that same emergency guide runs some 26 pages and, while not all of it is specific to the dangers of combating a battery fire, the number of warnings regarding which power lines not to cut — and, of course, those which to deliberately shred — as well as admonishments not to bend the battery and the like does give one pause.
And since this guide was for but one year and one model of Tesla, the sheer number of variations of dos and don’ts that go into extinguishing all the possible iterations of an EV fire would seem daunting.
So not only must firefighters be brave — see 9/11, the Twin Towers — but now they must also be trained technicians, not only able to memorize every EV’s different “no-cut zones,” but also cool enough under pressure to recall all those cautions while literally under fire.
But then they are firefighters, heroes all and the most venerated of first responders.
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Dave
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EVs, Unsafe at any speed🔥🔥🔥
Ban these things now!!
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