RV Fire Protection

From 2009 to 2013, an average of 5,540 fires a year involved motorhomes and other recreational vehicles, according to estimates provided by the National Fire Protection Association (NFPA). On average, those fires killed 36 people and injured 135 annually.

Once a motorhome fire starts, it is likely to spread rapidly, because of the highly flammable materials used in coach construction. And any number of areas within a motorhome are susceptible.

The large maze of electrical wiring can chafe, or connections can work loose, leading to an electrical fire. Fires also can occur in propane-fueled RV refrigerators, which use an absorption method of cooling that heats ammonia. If the cooling package springs a leak, hydrogen gases can escape and catch fire when they come in contact with a hot electric heating element of the propane burner.

Another common area for fires is the engine compartment of a rear-engine diesel chassis. An engine with a turbocharger can reach temperatures of 1,000 degrees Fahrenheit. If fuel leaks from the engine, the spray could come in contact with the turbocharger and ignite. In addition, engines with hydraulically driven side radiator fan motors can develop a leak that could cause the sprayed hydraulic fluid to ignite. And, electrical shorts are another potential cause of fires.

The NFPA code requires that every motorhome be equipped with a fire extinguisher. But an extinguisher that meets the code’s minimum standards may not be able to douse a blaze in your RV; many factory-installed extinguishers are undersized and not up to the task. In addition, fires are classified according to the type of fuel that is burning, and not all fire extinguishers are rated for every classification.

Motorhome owners, therefore, must be prepared by having the right type of fire extinguishers on hand and knowing how to use them. Some people may wish to install an automatic fire-suppression system, which provides an immediate response to a fire; later, I’ll describe the system I installed.

First, though, it’s important to understand fire itself. A fire is a rapid chemical reaction. To begin or sustain that reaction, three key elements, known as the fire triangle, must be present: fuel, oxygen, and heat. To extinguish a fire, at least one of those elements must be eliminated.

Obviously, oxygen is always present in the air. But a motorhome also has an abundance of potential fuel for a fire. Motorhomes are built using a large amount of wood and composite materials, as well as glues and insulating foams. In addition, propane and gasoline or diesel fuel are present, and there is plenty of wiring, which has burnable insulation. The interior furniture, bedding, drapery, and carpeting all allow a fire to spread rapidly.

Such materials need only be heated to their combustible temperature for ignition to occur. For example, an electrical short creates intense heat in a wire. Generally, wiring is run through or around highly combustible materials, such as wood paneling or carpeting, so a hot wire can cause those materials to ignite.

Class A fires involve solid combustible fuels such as wood, paper, cloth, and plastics. Class A fires produce ash, so think of “ash” to help you remember what an “A” fire is. A Class A fire can be extinguished by eliminating the oxygen or by cooling the fuels below their flash point. It’s the easiest fire to put out; water generally works fine. Ideally, adding a surfactant, such as soap, to the water will break the surface tension and separate the fuel from its oxygen, allowing the water to further cool the fuel.

Class B fires involve flammable liquids such as gasoline, oil, grease, diesel fuel, or alcohol. Liquids boil, so think of the word “boil” to remember what Class “B” fires are. Such fires cannot be extinguished with plain water, because the fuel floats on the water’s surface and spreads to other areas, which only worsens the situation.

Class C fires are electrical fires caused by energized circuits. The wire itself doesn’t burn, but the insulation and any surrounding materials do. Using water-type extinguishers on a Class C fire could create an electrical shock hazard. But once the circuit is de-energized, the fire can be treated as a Class A. Electrical wires conduct current, so you can associate the word “current” with a “C” fire.

According to the 2015 NFPA code, a motorhome must be equipped with a portable fire extinguisher with a minimum rating of 10-B:C, and it must be located in the RV interior within 24 inches of the primary means of escape. The number 10 means the extinguisher is rated to control a fire in a 10-square-foot area.

 Mac McCoy, better known as Mac the Fire Guy, is a respected authority in the field of RV fire safety. He recommends that a motorhome have at least three indoor foam fire extinguishers to aid in an escape: one near the door, one in the kitchen, and one in the bedroom. He also recommends that one be placed in an unlocked outside compartment or in the towed vehicle.

Many types of extinguishers are available, so it’s important to choose the right ones based on the types of fires you might encounter.

Water fire extinguishers remove the heat element of the fire triangle. Air pressurized water (APW) extinguishers are filled about two thirds with water and then pressurized with compressed air. Water squirts out the extinguisher’s hose and cools the fire below its flash point. Such extinguishers do not work on Class B fires. Nor should they be used on Class C fires because of the potential shock hazard from energized high-voltage circuits.

Aqueous film-forming foam plus (AFFF Plus) extinguishers are particularly effective on hydrocarbon fuel fires, which are Class B. The foam, which is nontoxic and biodegradable, smothers and cools the fire. AFFF Plus breaks down hydrocarbons so that they cannot reignite. The foam is not corrosive and won’t harm electrical components or connectors.

Carbon dioxide (CO2) extinguishers are filled with gas that is compressed to a very high pressure. Such extinguishers are easily identified by their large plastic horn rather than a nozzle. The CO2 exits at a high velocity and displaces oxygen to suffocate the fire. A side benefit is that the CO2 exiting the extinguisher is very cold, forming dry ice on the horn as it exits; this helps to cool the fire and lower it beneath its flash point. CO2 extinguishers are effective on Class B and C fires.

Multipurpose dry chemical extinguishers are the most common type of extinguisher, and are effective on Class A, B, and C fires. (Ordinary dry chemical extinguishers are for Class B and C fires only.) They are filled with a dry powder that is similar to baking soda, and pressurized with nitrogen.

Dry chemical extinguishers have drawbacks, however. After resting awhile, the powder can cake and compact in the bottom of the canister, so it’s recommended the extinguisher be shaken or given a whack with a rubber mallet once a year. The seals also can dry out, allowing the pressure to diminish, rendering the extinguisher ineffective. Most dry chemical extinguishers are inexpensive and many are nonserviceable, so their quality reflects that. In addition, the dry chemical is toxic and corrosive and will attack electrical components once heated, so after using such an extinguisher, the odds are good that some replacement of electronic equipment will be necessary.

Halon extinguishers, which are primarily used to fight Class B and C fires, don’t damage electrical equipment. An inert gas inhibits the chemical reaction of the fire. However, the gas is lightweight and can blow away, possibly allowing the fire to reignite. Halon extinguishers work best in an enclosed area, such as behind a refrigerator. They should never be used in an engine compartment where air is always moving. New production of such extinguishers has been banned, because halon contributes to ozone depletion.

Regardless of the type of fire or the extinguisher used to put it out, it’s possible a fire may reignite. If a fuel leak continues to spray, a blaze may flare up once the extinguisher is depleted. That’s why a warning system is almost as important as the extinguisher itself. Such a system alerts motorhome occupants that a fire has begun and gives them time to deal with the situation. This may require pulling off the road and shutting down the source of fuel or attacking the fire further with a handheld extinguisher. A warning system in combination with an automatic extinguisher provides precious time to determine whether to evacuate or further attack the fire.

Because our coach has a residential refrigerator, my primary concern was the engine compartment. I determined that a foam extinguisher was the best solution.

To help work out the details of my new fire-suppression system, I contacted Mac the Fire Guy, whom I’ve relied on previously. He’s a regular exhibitor and seminar presenter at FMCA Family Reunions.

On his website, Mac offers a number of automatic fire-suppression systems for engines, as well as for electrical, battery, generator, and refrigerator compartments, starting at $210. I chose his SS300-R4 system from Fire Fight Products LLC, which sells for $620. It consists of a 4-liter bottle filled with AFFF Plus, and a pair of remote sprinkler-style heads that connect to the bottle via two 4-foot-long Teflon-lined, stainless-steel braided hoses. I also ordered an optional pressure switch to trigger a dash-mounted alarm when the pressure in the bottle drops during a discharge.

Smaller cylinders are available, but I chose the 4-liter bottle for maximum runtime. If the system ever deploys and sounds the alarm, the additional capacity will give me that much more time to pull over, shut down the engine, and determine how to deal with the fire while minimizing the chance for a flare-up once the retardant is exhausted. Besides, I have plenty of room in my motorhome’s engine compartment. The dual remote heads allowed me to place one on each side of the engine for maximum coverage. The pressure sensor is necessary to operate the alarm.

I fabricated a mounting bracket for the 4-liter bottle and located it in a corner of the engine compartment. The bracket was fastened with self-drilling screws, and the bottle was held in place with three large stainless-steel, worm-drive hose clamps that were supplied with the bottle.

The provided alarm was a dash-mounted red LED light with a small piezo buzzer. I instead ordered a 2-inch round alarm from Fireboy, which featured a red alert LED, a green “ready” status LED, a reasonably loud siren, and a bypass switch to silence the alarm after the system had been used. I mounted this in the instrument panel and ran a 12-volt ignition-switched power wire and ground wire to the dash area; I then ran a third wire to the rear and connected it to one of the terminals on the extinguisher’s pressure switch. Finally, I ran a wire from the second terminal on the pressure switch to a good ground.

The alarm system uses constant power from the ignition switch to the alarm. Power then passes through the pressure switch, which normally is closed under pressure, and then to ground. This is a fail-safe design. It ensures that the alarm will sound whenever there is a break in the circuit, such as when a fire destroys the connection or another electrical failure occurs.

I mounted the two heads in the engine compartment, one on each side, and connected the two braided stainless-steel hoses to the bottle. I then removed the locking tab and opened the ball valve on the extinguisher to charge up the hoses. That’s when I found I had forgotten to tighten one of the fittings, so I quickly shut off the valve without losing much foam, retightened the fitting, and opened the valve again.

After a final inspection and the addition of some nylon cable ties to the hoses, the system was ready. I hope it’s never, ever needed, but if it is, it will be invaluable. I consider it to be insurance. Our engine bay is now protected, and we have peace of mind.

Everyone in a motorhome should know how to use a portable fire extinguisher. Here’s a simple way to remember the steps. It’s called P.A.S.S.

Pull the pin: This unlocks the operating lever and allows you to discharge the extinguisher.

Aim low: Point the nozzle or hose at the base of the fire.

Squeeze the lever above the handle: This discharges the extinguishing agent. Releasing the lever will stop the discharge.

Sweep from side to side: Moving carefully toward the fire, keep the extinguisher aimed at the base of the fire and sweep back and forth until the flames appear to be out.