Those who work around heavy machinery or equipment know the importance of proper safety gear. Safety glasses protect the eyes, and hearing protection saves the ears. But what about keeping the space and material safe? In the event of a fire, a fire extinguisher must be on hand and ready to use. Many people think fire extinguishers are easy enough to use, and that there’s not much to it. But there is. Not only do fire extinguishers need to be used properly, but those fighting the fire also need to know which one to use.
Why Are There Different Fire Extinguishers?
There are different fire extinguishers because there are different kinds of fires because of the different types of fuels that create fires. Each fire requires a different type of fire extinguisher to address the various fuels to ensure that each fire is put out properly. In fact, if the right fire extinguisher is not used on the right fire, it could possibly spread and cause even more damage. The different fire extinguishers are available for safety purposes.
Types of Fires
There are a total of five different types of fires. Three of them are common classes, and two of them are specialty classes. The common classes are Class A, Class B, and Class C. Specialty classes of fires are Class D and Class K.
Class A Fires. Class A fires consist of what is referred to as common combustible fires that involve items such as paper, rubber, cloth, wood, trash, and plastic. Class A fires most often occur in commercial or residential settings, but they can happen wherever these types of items are present. The fire extinguisher used to put out Class A fires is a water extinguisher only.
Class B Fires. Class B fires consist of flammable liquids and gases. These include gasoline, oils, solvents, lacquers, paint, tar, and other oil-based or synthetic products. Class B fires typically spread quickly, and, if they are not properly secured, these fires can reflash even after the flames have been extinguished. The fire extinguisher primarily used to put out Class B fires is a dry chemical extinguisher.
Class C Fires. Class C fires consist of live electrical equipment and involve items such as motors, wiring, various types of controls, data-processing panels, appliances, circuit breakers, outlets, and similar items. Fires that are involved in this class can be created by something as simple as a spark, but they can also be caused by a power surge or a short circuit. These types of fires normally take place within the walls of residential or commercial properties, typically in locations that are hard to see or get to.
Water should never be used to try to put out an electrical fire, it could result in an electrical shock. Multipurpose, regular carbon dioxide and halotron extinguishers can be used for a Class C fire.
Class D Fires. Class D fires, which are considered specialty fires, consist of combustible metals such as sodium and magnesium. These types of fires are unique industrial hazards and required a special type of dry powder agent to extinguish. The only extinguisher recommended for use on a Class D fire is a dry powder fire extinguisher. When a dry powder fire extinguisher is used, it smothers the fire by absorbing oxygen and heat, which ultimately puts it out.
Class K Fires. Class K fires typically consist of combustible cooking materials such as grease, oils, and fats that are commonly used in kitchens. These types of fires are more often seen in the food service and restaurant industry, but they can also occur in the home. A wet chemical extinguisher is needed to put out a Class K fire.
Types of Fire Extinguishers
Most people are only familiar with one type of fire extinguisher, but there are many types, including
- Water and foam
- Carbon dioxide
- Dry chemical
- Wet chemical
- Cleaning agent
- Dry powder
- Water Mist
- Cartridge-operated dry chemical
Each of these types of fire extinguishers is best for a different type of fire, although there is some overlap. Fire extinguishers work by disrupting different parts of the fire triangle.
Water and Foam. Foam fire extinguishers normally are used in manufacturing plants, on construction sites, at race tracks, and at commercial storage facilities and fueling stations. Water-based fire extinguishers are used for Class A fires, whereas foam-based fire extinguishers are used for Class A and Class B fires.
Carbon Dioxide. Carbon dioxide fire extinguishers typically are used in areas that require cleanup or involve some form of contamination. They are mainly used in commercial settings such as food storage and processing areas, data-processing centers, laboratories, and telecommunication rooms. Carbon dioxide fire extinguishers are typically used for Class B and Class C fires.
Dry Chemical. A dry chemical fire extinguisher is used mostly for fires associated with automobiles, boats, laboratories and garages. A regular dry chemical fire extinguisher is used on Class B and Class C fires.
Wet Chemical. Wet chemical fire extinguishers are often used in kitchens because of the risk of fires that are caused by grease, fat, and oil. Wet chemical fire extinguishers are most effective on Class K fires.
Clean Agent. The clean agent fire extinguisher is an extinguishing gas designed to extinguish gaseous fires.
The clean agent fire extinguisher is installed in a fire-suppression system. It is made up of a gas solution comprised of 60–80% of tetrafluoroethane, between 10 and 30% pentafluoroethane, and roughly 10–30% carbon dioxide. This type of fire extinguisher contains a liquified substance while it is stored that turns into a gas upon being discharged into the air. It is mainly used in and most effective on Class B and Class C fires that normally involve propane, butane, oil, petrol, and similar substances.
Dry Powder. The dry powder fire extinguishers extinguish fires by separating the oxygen or heat from the fuel, preventing the fire from combusting. Dry powder fire extinguishers are mainly used for Class D fires or fires that specifically contain combustible metals.
Water Mist. Water mist fire extinguishers sprays deionized water in an extremely fine mist. The droplets cool an area down, making it harder for the fire to spread. These extinguishers are often used when contamination of the area is a concern because they don’t leave any chemical residue or leave the area soaking wet. Water mist fire extinguishers are best used on Class A and Class C fires.
Cartridge-Operated Dry Chemical. Cartridge-operated extinguishers put out fires by disrupting the chemical reaction that allows fire to burn by creating a barrier between the oxygen and fuel. You can get a cartridge-operated dry chemical extinguisher in a normal or multipurpose formula. Multipurpose ones can be used on Class A, B, and C fires, while normal ones are exclusively for Class B and C fires.
It is important to note that the wrong type of fire extinguisher should not be used on the wrong type of fire. For example, a Class A fire only requires pressurized water, but pressurized water should never be used on Class B or Class C fires. Using a water extinguisher in one of these situations could cause the fire to spread or electrify the area.