I’m not talking about something small to keep in the glove box to put out a small fire in the engine compartment before it does too much damage. I mean, if you’re driving along and come across someone trapped in a car engulfed in flames. Is there any size where you stand a reasonable chance of putting it out or at least keeping it a bay until fighter fighters arrive?
If I was just getting one, I’d just get the biggest one available. But I want to get several so there’s a cost issue.
FWIW I once emptied a smallish fire extinguisher (probably similar in size to the one I have in my kitchen pantry, which I just checked, and says it is 6 lbs capacity) in an attempt to put out a golf cart which had caught fire in the battery area (it was by no means yet “engulfed”) - it was hopelessly too small.
Well, damn. I just bought the largest one at the local Wal-Mart and it’s only 5.5lb.
One can never possess a fire extinguisher that is too large… Often they are too small for the job at hand… There is no formula for the size needed for all scenarios. If in doubt, go as large as you can accommodate.
I had one of the smaller ones they sell for keeping in your car and tried to use it on a trash can fire. It was useless. Get a big one.
Potentially upsetting story ahead:
This morning, my roommate and another friend were driving down a country road, and they came across an accident. A man had crashed into a tree and was trapped in his burning truck. They tried to get the driver side door open but it was stuck, my roommate went back to the car to find something to try prying it open with while his friend kept trying to open the door. He couldn’t find anything and by time he got back the truck was too hot to approach. About 12 people had stopped and in the panic and confusion no one even tried the passenger side door. Although it wouldn’t have made any difference because the man was trapped under the dash. There was a nearby house but no one was home. And no one had a fire extinguisher. There was nothing anyone could do, the man was screaming and they couldn’t help him and eventually the screaming stopped.
So now I’m trying to get as many fire extinguisher as I can to give out to people I know. But I don’t want to get a bunch of useless ones. But, of course, I don’t have unlimited money, so I’m trying to find a good compromise between quality and quantity. Obviously, people I know who can afford it, I’ll just strongly encourage them to get their own.
For most vehicles a 2A-10BC extinguisher should be adequate. One that size should cost about $30-$40. Just as important as having an extinguisher big enough is learning how to use it properly.
Back in the days when cars had carburetors, a driver screeched into the parking lot where I worked, popped open the hood to reveal flames spreading across the entire engine compartment. I grabbed a dry chemical (Class B/C) extinguisher that was roughly 18" tall by 10" in diameter and emptied the whole thing. It knocked back the fire but didn’t put it out entirely, and the flames started coming back by the time the fire dept. got there.
So I believe the correct answer is “bigger than you think.”
Putting out a truly burning vehicle takes hundreds of gallons of water/foam/etc. There is exactly nothing you can carry in your car that can stop a fully engulfed vehicle fire.
The time to get people out is when the fire is about the size of your shoe. After that you’re into the last few seconds for both rescuers and rescuees. Setting aside firefighters in silver suits who just happened to be standing there. And even they won’t last long working on a vehicle fire absent a firetruck to suppress the flames with water / foam.
As kunilou’s experience points out, even if you can get to an underhood fire you’re not going to do much. There’s plenty of flammable stuff, a nice draft with air coming up from below and able to escape out the top, and a large mass of metal already at high temps that isn’t cooling off any time soon. That metal mass itself is not normally hot enough to initiate combustion, but it acts as a thermal catalyst to whatever fire does get started by other means.
A few years ago a student of mine rear-ended my truck. Didn’t even scratch the chrome on my bumper, but it took her Honda back through the radiator. Just crushed it. As we got out to look at the damage, I saw flames starting under her hood. It took my small extinguisher and the one in the cop car that arrived almost instantly (did I mention that she hit me right in front of the local police station?) to knock down the fire.
Carry a big one (or two.)
Ok, thanks. So I guess around 10lb and hope if this type of situation comes up, you get there while it’s still small.
Knowing how to use one is almost more important. In a car fire there are so many things that burn. Is it an electrical fire? Gas, or just stuffing? Where is the fire. That is the hard part. Will the extinguisher be effective at putting out the fire or just slowing it down.