Fire Extinguishers

What Kind Of Fire Extinguisher Should I Use?

[AWN] I’ve been in three car fires. Two were relatively minor, but one was REAL scary… It progressed from a minor electrical short in the dash to a full-blown conflagration in less than thirty seconds, and the car BURNED TO THE GROUND in about two minutes. That fire is the reason that I carry fire-extinguishers in my cars. YOU should carry one, too. Don’t think that you’re safe from fire just because you don’t drive your car at the track… Or that it can’t happen to you because your car is modern, well-maintained, and unmodified. That big fire of mine happened on the street, in my uncle’s brand-new Ford sedan

There are two kinds of fire-extinguishers that are marketed for use in automobiles… There are the "dry chemical" extinguishers, which can be purchased very cheaply from any hardware store, and Halon extinguishers, which are harder to find and expensive.

If you already carry a dry chemical extinguisher in your car, pat yourself on the back for being so safety-conscious, then throw it out and go buy a Halon extinguisher… Dry chemical’s great for the kitchen, but PLEASE don’t use it in your car if you can help it. The deal is this: The old-style dry chemical will DESTROY aluminum or magnesium. It also eats through electrical insulation and will probably damage most plastic components.

Some modern dry chemical (one has the brand-name "Purple-K") are less corrosive than the old stuff. Nevertheless, it’s STILL a bad idea to use them, since the powder is FOREVER, and it gets EVERYWHERE. 

Words cannot describe the extent of the damage you’ll do… Unless you’ve seen the results of a dry chemical extinguisher activation inside a car, you wouldn’t believe it.

My advice to anyone who’s discharged a dry-chemical extinguisher in his car (or in the car’s engine compartment), is, "Sell it THIS INSTANT, before the chemical COMPLETELY whacks out your car. Take whatever you can get and cut your losses."

It’s IMPOSSIBLE to clean that stuff up; it’ll get into electrical connectors, gauge movements, switches, your stereo, air vents, etc. Needless to say, it’s unlikely to do much good in ANY of those locations.

With a burning-but-insured car in front of me and only a dry chemical extinguisher at hand, I’d be VERY ambivalent about discharging it.


There are two big problems with useful Halon extinguishers.

First, they’re physically large. The 5-pound bottle in my car — 5 pounds of Halon; the whole extinguisher weighs about 12 pounds — is a 15-inch-long, 6-inch diameter cylinder that doesn’t really fit anywhere.

Second, they’re expensive. A 2.5-pound handheld bottle (5-B:C) costs around $100, and you’ll pay over $300 to fill an 11-pound bottle.

However… You’re not going to find anything that works as well as Halon, so you just have to deal with those issues.

To be fair, I guess I should mention that Halon’s biggest advantage (the fact that it dissipates after it’s done its job, so you don’t have to sell your car after you’ve put out a fire) can also be a DISADVANTAGE in one particular situation:

If the fire’s being fed from a renewable source (like oil draining or being pumped onto an exhaust pipe), it may flare up after being "extinguished", requiring repeated blasts of Halon. You may have seen this on television… I remember seeing a crash last year in which a track worker used up bottle after bottle of Halon trying to keep an oil fire down.

Here’s the thing, though: The fires you’re likely to see are going to be (at first, anyway) very small electrical ones, not huge petroleum-fed infernos. Halon’s the best possible extinguisher for these small fires; its extinguishing capability in an enclosed space is — please excuse my exuberance — f—ing MIRACULOUS.

If I were a track worker faced with an unconscious driver trapped in a burning car, Halon dissipation might be an issue. I’m not, though… The extinguisher in my car will only be used by ME, so I’ll presumably be conscious and mobile when I activate it. In that situation, five pounds of Halon is sufficient to get me out of the car safely. If the fire flares up again… Well, that’s what insurance is for.

Also, Halon in an enclosed or semi-enclosed space isn’t directional; if you have a fire somewhere under the dash or behind some other obstruction, you can still put it out. Since most cockpit fires start this way, Halon is really the best choice.

By the way, those little 12-ounce Halon extinguishers are basically toys… I carry at least one of them in each of my cars, but only as a means of extinguishing VERY small fires — like from a cigarette ash on the carpet or something. One of my three fires started exactly that way, and if I’d had one of those little extinguishers at the time (or even a can of Diet Coke that I could have poured on it), I might still have that car.

[HS] Halon (sorry environmentalists!) is the *only* way to go.

  1. Best solution is an electrically-fired, "on-board" system (a 10-lb one) mounted in the nose or tail of the car somewhere... with alloy plumbing to the important locations (engine, cockpit). There's plenty of room in an NSX,
  2.    however, installation would not be fun (read: $$$).
  3. Any fire bottle mounted inside the cockpit must be *extremely* securely mounted -- lots of G-forces in a crash (especially at track speeds). Mount must be built as if it were to hold a 200-pound item.

How Should I Mount A Fire Extinguisher In The Car?

The quick and dirty (and cheap) way to temporarily mount a fire extinguisher (such as for a track event) is to wrap a small towel around your passenger door armrest and fasten (using plastic toothed ties) the extinguisher to it.

See Fire Extinguisher Mounting for information on more durable and attractive methods of installing a fire extinguisher in the NSX.