It’s important to understand how fire extinguishers are classified in order to choose the correct model. First Alert® safety products offer a wide range of residential, marine, commercial, and automotive fire extinguishers. The classifications are categorized by A-B-C or a combination of the three.
Fire extinguishers with a Class A rating are effective against fires involving paper, wood, textiles, and plastics. The primary chemical used to fight these fires is monoammonium phosphate, because of its ability to smother fires in these types of materials.
Fire extinguishers with a Class B rating are effective against flammable liquid fires. These can be fires where cooking liquids, oil, gasoline, kerosene, or paint have become ignited. Two commonly used chemicals are effective in fighting these types of fires. Monoammonium phosphate effectively smothers the fire, while sodium bicarbonate induces a chemical reaction which extinguishes the fire.
Fire extinguishers with a Class C rating are suitable for fires in “live” electrical equipment. Both monoammonium, phosphate and sodium bicarbonate are commonly used to fight this type of fire because of their nonconductive properties.