A fire extinguisher is a metal cylinder filled with water or a smothering agent that you can deploy to put out a small flame or slow its progression until emergency services arrive. These devices are a valuable tool to have in any household, office building or business. They are used to protect people and property from the destructive power of a fire, but you must be prepared and understand how to use them. Fires double in size every 60 seconds, so it is important to act quickly. You must also know your escape route before a fire becomes too large to exit through an existing door. Fire extinguishers are designed to be used by anyone, including children and people with disabilities.
There are five different types of fire extinguishers, and each type is used to fight a specific class of fire. Classes of fire are categorized by the type of fuel they burn, with class A fires burning ordinary combustible materials such as paper, wood, cardboard and most plastics, and class B fires burning flammable liquids such as gasoline, oil and kerosene. Handheld fire extinguishers are typically marked with a numerical rating that indicates how much of a particular kind of fire it can suppress, and they feature a green triangle symbol to indicate class A fires.
Carbon dioxide fire extinguishers, which are usually marked with a red square, discharge a gas that smothers the fire by cooling it and depriving it of oxygen. The carbon dioxide emitted from these fire extinguishers is safe for humans, but you must be careful not to inhale it or touch the plastic discharge horn, which can get very cold. These units use air under high pressure to discharge the smothering agent from a small opening at the top of the cylinder.
Class D fires involve metals that can be melted or burned, including iron, steel and copper. These types of fires are difficult to extinguish because they can re-ignite even after the fire has been suppressed. A gaseous agent called halon is used in some class D extinguishers, which are marked with the red square symbol. Halon has been banned from new production under the Montreal Protocol as a result of its ozone-depleting properties, but it is still used to refill some older fire extinguisher cylinders.
A dry chemical fire extinguisher consists of a metal cylinder that contains a powdered agent such as sodium bicarbonate. When you depress the operating lever on a dry chemical fire extinguisher, the smothering agent is discharged through a hose at the end of the cylinder. During the operation, keep your hands away from the nozzle, and move the hose or nozzle in a sweeping motion over the base of the fire. Be sure to move around the fire area as it diminishes to ensure that the blaze is not reignited, and call the fire department once you have completed your work. You should also continue to watch the area until the fire department says it is out.