A fire extinguisher is a metal cylinder that holds a liquid or solid material. When the handle or lever is depressed, a nozzle sprays the material onto the fire and smothers it. There are many different types of fire extinguishers, each designed to handle a certain type of fire or group of fuels. They are rated based on the fire hazard they can handle and are typically labeled with a picture of a fire hazard icon and a numerical rating.
Handheld fire extinguishers are the most common and typically used in homes. There are also cart-mounted fire extinguishers, which are usually larger and more heavy duty. Both handheld and cart-mounted extinguishers are typically made of steel, with the cylinder holding a smothering agent under high pressure. The nozzle is connected to the cylinder via a plastic siphon tube that opens with the depressing of the lever. A spring-mounted valve blocks the passageway between the cylinder and the nozzle when not in use.
The cylinders are filled with water, carbon dioxide or dry chemicals. Water is useful for class A fires, putting out the flames by cooling the burning materials and displacing oxygen. Carbon dioxide is used to fight class B and class C fires by replacing the air surrounding the burning fuel and smothering it. Dry chemical fire extinguishers use a specialized form of sodium bicarbonate or potassium bicarbonate, which are similar to baking soda, to interrupt the chain reaction of the burning fuel and absorb moisture in the process.
Extinguishers with a class K rating are essentially the same as a dry chemical, but they also use an insulation of foam to smother the fire. These are commonly found in restaurants because they will not damage cooking equipment and food.
Most home and business owners keep a couple of fire extinguishers in easy reach to deal with small house or office fires. It is important to be familiar with how to use them so that you can quickly and efficiently put out a fire.
In addition to knowing which type of fire extinguisher to use, it is important to keep them properly maintained. This includes regular testing and cleaning. The testing procedure is simple, requiring only that you check the pressure gauge and make sure that the nozzle is not clogged by bugs or debris. The cleaning is a bit more involved and involves removing the nozzle, wiping down the inside and outside of the cylinder, and shaking it to ensure that the chemicals are fully packed.
In addition to keeping fire extinguishers in good working order, it is important to know where they are located and to share their location with all household members. It is also a good idea to have a family fire drill and to discuss escape routes in case of a real emergency. It is also important to keep them in a visible place in the house, so that babysitters and other long-term visitors are aware of their location.