Fires have four elements in order to exist. They must have oxygen, heat, a chemical reaction and fuel. In order to successfully extinguish a fire, one of these elements must be taken away, that is, extinguished.
There are five different classes of fires. These fires are lettered A, B, C, D and K. Each of these fires has a different fuel.
Class A fires comprise of ordinary combustibles, occurring in wood, paper, plastic, trash or cloth.
Class B fires are comprised of flammable liquids and gases, which include gasoline, paint, petroleum oil, propane, and butane (cooking oil and grease are not included in class B).
Class C is comprised of fires that involve electrical equipment such as home appliances (often kitchen related), motors, and transformers.
Class D fires are caused by Combustible Metals ; that is, materials such as potassium, magnesium, sodium and aluminum.
Class K fires occur due to cooking oils and grease, including animal and vegetables fats.
Next, there are six main kinds of fire extinguishers. Having a basic understanding of each kind of extinguisher will help you determine what kind you may need to purchase for the safety of your family and home.
The first type of extinguisher uses water or foam. These extinguishers take away the heat, and the foam extinguishers also separate the oxygen. Water extinguishers can only be used on class A fires; if they are used on other types they can actually do more harm than good. Foam extinguishers can be used on classes A and B only.
The next type of extinguisher is a carbon dioxide extinguisher. It takes away the heat, as well as dispersing the oxygen. It is recommended they be used on class B and C fires; they often prove to be unsuccessful on class A fires.
The third type of fire extinguisher is one that utilizes dry chemicals. They work by disrupting the chemical reaction of the fire. This kind of extinguisher is popular because it has proven to be effective on classes A, B, and C fires. Be sure to use a multipurpose dry chemical extinguisher...a simple dry chemical extinguisher will not work on class A fires.
Wet chemical fire extinguishers are effective on class K and sometimes class A fires as well. They were originally invented to aid in commercial kitchen or deep fat fryers, which often found in fast food joints or restaurants.
Clean agent fire extinguishers have halon agents as well as agents that are good for the environment. These extinguishers are often used on class B and C fires, though large clean agent extinguishers can be effective on class A fires as well.
Finally, dry powder extinguishers are often used only on class D fires or combustible metal fires. These extinguishers remove the heat in addition to separating fuel from the oxygen.