Types of Fire Extinguishers

A fire extinguisher is a device that can put out small fires or contain them until help arrives. It should never be used in place of emergency services, but it is a good idea to have one in your home. There are many different types of fire extinguishers, each one designed to fight certain classes of fire. There are two categories: handheld and cart-mounted (also called wheeled) units. Handheld extinguishers can be carried and operate by an individual person, while the larger cart-mounted units require a trained operator.

This is the most versatile type of fire extinguisher and is rated to be used on Class A, Class B, or Class C fires. It discharges a spray of microscopic water molecules that fight the fire by cooling it and stopping its chemical reaction. This type of fire extinguisher is also nontoxic and doesn’t leave a residue. It is available in a variety of models that include dry chemicals, wet chemicals, and foam.

Sodium bicarbonate fire extinguishers (Class A, K) use a mixture of sodium bicarbonate and silica gel particles to stop the chemical reaction of the fire and soak up unburned fuel, which prevents it from contacting air. They are effective for a wide range of liquids and gases, including gasoline and propane. They are blue/red in color and can be discharged as either an aspirated (mixed and expanded with air) or nonaspirated (stored as a solid compound that is mixed upon squeezing the handle). Historically, these extinguishers were also made in a pre-mix model where the AFFF concentrate was housed in an external cartridge and mixed with plain water on discharge.

Dry chemical (Class A, B, C) fire extinguishers use pressurized dry agents such as copper sulfate for class A fires or graphite for class D fires. Graphite-based (G-Plus, G-1, and Lith-X) or dry powder fire extinguishers were first developed in the United States in 1949, with the Ansul Super-K and Purple-K being invented in the early 1960s. These are effective for a wide range of flammable liquids and can also be used on metal fires, such as magnesium.

Halon (Halon 1211 and Halon 1301) is a gas that inhibits the fire’s chemical reaction, cools the flames, and vaporizes to leave behind no residue. It was used extensively in the 1950s and 1960s, but its production is prohibited under the Montreal Protocol due to ozone depletion. Halon may still be recycled for use in existing cylinders.

Carbon Dioxide (Class B, C) fire extinguishers release a high concentration of carbon dioxide in the form of a gas/snow cloud that quickly evaporates after use, leaving no residue and no electricity-conductive properties. These are useful for protecting electronic equipment in computer rooms, laboratories and printing or duplicating areas.

Clean Agent (Class A, B, and C) fire extinguishers are nonconductive and noncorrosive and discharge a combination of gas and mist that penetrates the surface of the fuel to smother it. This type of extinguisher is commonly found in our kitchens and food preparation areas and is a great choice for Class A, Class B, or Class C flames.