Owning a fire extinguisher and knowing how to use it could save your vehicle from a slow and painful death. Every off-road vehicle should be equipped with a working fire extinguisher of the proper size and class. I highly recommend safely mounting a multi-class (ABC) extinguisher in your vehicle as this will combat most common sources of a vehicle fire.
There are basically four classes of fire extinguishers. Each class is designed for a specific fire source. Many fire extinguishers are rated for multi-purpose use and will be labeled as A, B, C, D or some combination of these codes. Newer fire extinguishers use a picture/labeling system to designate which types of fires they suppress. Older fire extinguishers are labeled with colored geometrical shapes with letter designations.
CLASSES / TYPES:
Class A Extinguishers
Put out ordinary combustible fires, such as wood and paper. If the flame creates Ashes, then Class A will extinguish it.
Class B Extinguishers
Should be used on fires involving flammable liquids, such as grease, gasoline, oil, etc. Remember, most gas caps are not designed to hold back fuel should your vehicle become over-turned.
Class C Extinguishers
Are suitable for use on electrically fires. This class of fire extinguishers does not have a numerical rating. The presence of the letter “C” indicates that the extinguishing agent is non-conductive.
Class D Extinguishers
Are designed for use on flammable metals and are often specific for the type of metal in question. These extinguishers generally have no rating nor are they given a multi-purpose rating for use on other types of fires. An example of flammable metal is Zinc which will spontaneously combust once it has reached critical temperature.
Using the Fire Extinguisher:
Begin by standing back approximately 8 feet from the fire. Have someone grab the back of your belt and stand behind you. This individual can help you spot trouble, and can quickly pull you away should you be overcome by the flames or fumes. The acronym PASS can help you remember the steps for using your extinguisher.
Pull - the pin that keeps the handle secure.
Aim - the nozzle towards the base of the fire.
Squeeze - the handle to discharge the extinguisher.
Sweep - the nozzle back and forth at the base of the fire.
The ideal size extinguisher to put out an engine fire is 5 pounds or larger. Units smaller than 5 pounds become exhausted before flames are under control.
During a collision, the forces of gravity will cause loose objects inside your vehicle to become dangerous projectiles. It is critical that you mount your extinguisher in a safe and sturdy manner. Keep in mind that it must still be readily accessible in case of a fire. I recommend a commercial metal bracket available at most fire extinguisher stores. Most new extinguishers come with a plastic hanger intended to hold your extinguisher in place on a household wall. They are not designed to withstand the forces encountered during a collision.
Maintaining your fire extinguisher:
Fire extinguishers require regular monthly maintenance. This is a simply matter of checking the gauge to insure that pressure is within limits and to stir up the dry chemicals contained within the extinguisher. This can be done by simply turning over the extinguisher and striking the bottom with the palm of your hand. You should hear a granular substance (sounds like sand) slide back and forth inside the extinguisher as you turn it over. Otherwise you may need to carefully tap the bottom of the extinguisher with a rubber mallet. Be VERY Careful not to damage the cylinder as the contents are under great pressure! If the dry chemical powder is allowed to clump-up inside the extinguisher, it may not effectively extinguish fire.
Be aware that ABC class extinguisher normally contain dry chemical powders. These powders are quite messy and will get into every crack and crevice of your vehicle. Expect to spend some time cleaning up after use. Halon type extinguishers are very popular in the restaurant industry as they don't leave a messy film on everything. These are becoming hard to find as they are no longer produced due to their effects on the ozone.