Back to Basics: November 2014
November 3, 2014
By Mark van der Feyst
By Mark van der Feyst
The portable fire extinguisher is one of the most undervalued tools in the fire service. Every fire truck is equipped with at least one of these devices, and many trucks carry a variety of extinguishers.
|Photo 1: The majority of portable fire extinguishers found on apparatuses are dry-chemical ABC multipurpose devices.|
|Photo 2: On Class-B or C fires (flammable liquid and gas) a dry-chemical extinguisher is the choice tool to use.|
|Photo 3: A water extinguisher or water can is considered standard equipment on a dedicated truck company.|
|Photo 4: A firefighter can control nozzle discharge pattern of a water extinguisher by using a finger or thumb.|
Photos by Mark van der Feyst
Municipal firefighters do not often encounter the large, wheeled extinguishers, but it is important to know the types of extinguishers and their uses; it is important, however, for all firefighters to be proficient in the use of 10-pound, 20-pound and even 30-pound extinguishers.
The majority of portable fire extinguishers found on trucks are dry-chemical ABC multipurpose devices (see photo 1). These are great tools for suppressing Class-A, Class-B or even Class-C fires, inside or outside a dwelling. These small extinguishers are good tools to carry into calls for smoke in a building, a pot on the stove, an alarm sounding with nothing showing, or calls at which there may be a small fire that would require a quick and easy knockdown.
The downside to dry-chemical extinguishers is that they are messy when discharged and leave a chemical spill to be cleaned up by the resident or building owner after the small fire has been suppressed. This factor should be considered when deciding between a dry-chemical extinguisher or a water can. On a Class-B fire (see photo 2) or a Class-C fire, a dry-chemical extinguisher is the choice tool for suppression, but for a Class-A fire, a firefighter can choose to use a dry-chemical extinguisher or a water can.
A dry-chemical extinguisher does not provide cooling – only suppression. The extinguisher’s chemicals work by altering a fire’s chemical makeup in order to break the chain reaction and stop the flames from spreading, but they do not cool down the material that is already burning.
I responded to a call in which a sofa chair that was on fire in a room was treated with a dry-chemical extinguisher. The fire was suppressed, but the contents of the room were still hot and I could hear the sizzling as we waited for a hoseline to be brought in. Water was still needed to cool off the objects and prevent re-ignition. This is a scenario in which a 2 1/2-gallon water extinguisher comes into play.
On a dedicated truck company, a water extinguisher or water can is considered standard equipment (see photo 3). When a search team enters a structure, one member is usually assigned to bring along the water can. This allows the interior crew members to conduct a search; if they come across the fire, they can control it or knock it down enough to keep it in check.
Now the fire in question here is going to be a fire that can be controlled by a 2 1/2-gallon water can – we are looking at a fire in a bedroom and coming out into the hallway and making its way down the hallway. The water can has enough water in it to be able to knock back the fire in the hallway and keep the fire in the bedroom. This is where the search team can close the door to contain the fire while the search is completed.
A hoseline is necessary for any medium to large fire, but for a small fire in a room or building, the water extinguisher is all that’s needed. Once a small fire is knocked down, the burning item can be taken outside and hosed off further. A water extinguisher cools off both the item and the area around the item that was burning. This suppression tactic achieves two things: fire suppression and cooling. The water can is also good for overhaul operations since it is mobile enough to be brought into small areas, or to cool down or soak hidden fires in small, confined spots.
With a dry-chemical extinguisher, a firefighter cannot control the pattern that the nozzle discharges; it will discharge the powder in a straight, stream-style fashion, eventually dissipating into a dust cloud. By contrast, a firefighter can manipulate the nozzle discharge pattern on a water can by using a finger or thumb (see photo 4). As with a garden hose with no nozzle, the firefighter can create a straight stream, a broken pattern, or a fog stream. This option allows the firefighter to apply the water in a way that is beneficial to the operation. The firefighter can also bank the water stream off of other objects to achieve an indirect attack.
The 2 1/2-gallon water can may be a bit bulky and awkward to carry, but with practice and use, familiarity with the weight, size and height of the water can will become second nature. Knowing how long it takes to apply 2 1/2 gallons of water is also useful and will come with practice or training with the device.
The next time you get a call for a small fire, a pot on the stove, or an investigation, remember to bring along a portable fire extinguisher. A well-prepared firefighter carries the extinguisher in one hand and a hand tool in the other.
Mark van der Feyst has been in the fire service since 1999 and is a full-time firefighter in Ontario. Mark instructs in Canada, the United States and India and is a local-level suppression instructor for the Pennsylvania State Fire Academy and an instructor for the Justice Institute of BC. He is also the lead Author of Pennwell’s Residential Fire Rescue book. Email Mark at Mark@FireStarTraining.com