As anyone who has spent time at off-roading events can attest, fires happen. Since a fire in your rig can potentially leave you stranded, miles from civilization, it is good to take friends along who can help. Make sure one of those “friends” is a quality fire extinguisher.
To start and grow, a fire needs fuel, oxygen, and heat – elements that abound in an automotive environment – particularly in an off-road environment. Not all fire extinguishers are created equal. There is a lot of misinformation out there regarding fire extinguishers and what is suitable for automotive use.
First, let’s consider common fire types.
- Class A: Ordinary combustibles. These fires involve ordinary combustibles such as paper, wood, cloth, rubber, and plastic – anything that leaves an ash behind.
- Class B: Flammable liquids. These fires involve any liquid that will ignite – brake fluid, lubricants, gasoline, oil-based paint, etc.
- Class C: Electrical. Any fire involving live electrical equipment – wiring, fuse boxes, electric motors, computers, etc.
- Class D: Flammable metals. Magnesium, titanium, potassium, etc.
- Class K: Fire Extinguishers: Cooking oils and fats like those found in commercial kitchens.
For an off-road enthusiast, fire extinguishers rated for A, B, and C-class fires are a good choice as long as you know what you are getting. With this type of extinguisher, you are covered for the most common types of automotive fires – common combustibles and flammable liquids, and you know there is no danger of electric shock, thanks to the C rating.
Let’s look at the types of extinguishers you might encounter on the market and their pros and cons.
But first, a quick note. We are only going to consider UL-listed fire extinguishers. Underwriters Laboratories tests and rates fire extinguishers using standardized, repeatable tests. These ratings allow for comparison of different sizes and types of extinguishing agents on different sizes and types of fires. Things like how long the extinguisher takes to discharge and how far one needs to stand back from the fire all come into play.
There are a number of gimmicky fire extinguishers on the market that can appear attractive at first glance. Not only are they illegal in many states, but any claims as to the effectiveness of a non-UL listed fire extinguisher are meaningless because the extinguisher has not been tested to a recognized standard. Don’t fall for hairspray bottle type, “fire extinguishing sprays,” or other non-standard looking, non-UL listed products. Some of these products require standing unsafely close to the fire for an extended period. With a UL-listed extinguisher, you know it is designed to put out a certain size and type of fire quickly.
Water extinguishers
- Pros: Suitable for Class A fires, they work by cooling the fire and removing its heat.
- Cons: These are not suitable for class C fires.
Foam extinguishers
- Pros: Suitable for Class A and B fires, they work by smothering the fire and preventing the release of flammable vapors.
- Cons: Not suitable for class C fires and can cause damage and require cleanup.
Carbon dioxide (CO2) extinguishers
- Pros: Suitable for Class B and C fires, they work by removing oxygen and cooling the fire.
- Cons: No effectiveness on A-class fires, and these are dangerous to use in enclosed, occupied spaces because CO2 displaces oxygen, which can lead to asphyxiation.
Dry chemical extinguishers (Monoammonium Phosphate)
- Pros: Suitable for Class A, B, and C fires and combustibles. They work by smothering the fire and interrupting the chemical reaction that sustains it.
- Cons: Makes a corrosive mess that can be difficult/expensive to clean up.
Wet chemical extinguishers
- Pros: Suitable for Class K fires, they work by cooling the fire and creating a barrier between the fuel and the oxygen.
- Cons: Not rated for class A, B, or C fires.
Clean agent extinguishers
- Pros: Suitable for Class A, B, and C fires, they work by removing heat and interrupting the chemical reaction that sustains the fire. As the name implies, this agent leaves no residue, causes no damage, and requires no cleanup.
- Cons: Though the agent is rated for A-class fires, only the larger sizes receive an A rating.
Our Recommendation
Considering the array of extinguishers available, what should you buy? We’ve already mentioned that an ABC rating is a good choice, but what type of agent? Most ABC-rated extinguishers contain monoammonium phosphate, a dry chemical. Not only are these extinguishers effective, but they are relatively inexpensive – at least on the front end. However, they are corrosive, and cleanup can be a challenge.
Fire Extinguisher Test
No article on fire extinguishers is complete without a test of those extinguishers. We decided to test the effectiveness of the Element, Dry Chemical, and Clean Agent extinguisher.
Our tests were done at a local fire department training facility (Georgetown, California) with firefighter Nick Cimmarusti. Two additional firefighters from Georgetown were on standby. We used a burned-out Chevy Suburban hull with a fire bucket in the engine compartment for the test.
This isolated the test fire where most vehicle fires happen while wheeling, in the engine compartment. In the fire bucket, we added roofing tar paper (equal amounts each time) and a cup of flammable liquid (equal parts gasoline and diesel) and let the fire take hold for one minute.
The first test of the material and the flammable liquid was with an Element Flare Style extinguisher; these are not UL-approved but have become popular among auto enthusiasts because of their small size. We only let the test fire pre-burn for 20 seconds, struck the Element Flare, and proceeded to put the fire out. In this test, the Element Flare worked in extinguishing the flames, but we also noted that the roofing tar paper had not yet ignited; all that was burning was the flammable liquid. It did take the whole flare to extinguish the flames, and you needed to be very close to the flames for it to be effective (too close, in the opinion of our firefighters).
On the second test, we ran the test again with a pre-burn of 60 seconds (we used this standard for all remaining tests.) Using another Element Flare extinguisher on the second test, we noted that the fire was untouched and continued to burn with no relief when using the Element.
The third test used the clean agent extinguisher from H3R, branded as the HalGuard Clean Agent Automotive Extinguisher. We used the same amount of roofing paper and flammable liquid again with a 60-second pre-burn; the Clean Agent extinguisher put out the fire, flame, and burning material within 3 seconds. No flame or burning material was left on fire. We then blew off the rest of the extinguisher to empty it and see what total spread time we had. What remained was another 6 seconds, giving the extinguisher a total of about 9-10 seconds of disbursement. We also noted that the fire extinguisher worked from a good distance from the fire, making it safer to handle.
The fourth test used the Dry Chemical agent extinguisher from H3R, branded as the Max Out Dry Chemical Automotive Extinguisher. The test results were identical to those of the Clean Agent extinguisher in every way.
Conclusions:
The Element is a gimmick and should not be used as advertised.
The Dry Chemical Extinguishers are less expensive but can be corrosive to vehicle parts such as chrome, aluminum, and paint.
The Clean Agent Extinguishers are superior for automotive applications where corrosive chemicals can damage expensive parts.
The more extinguishers you have, the better your chance of saving your vehicle; be over-prepared, not under-prepared.
Thanks to H3R for providing fire extinguishers for testing https://www.h3rperformance.com/ and the Georgetown Fire Department for use of their training facilities and personnel.
