Become A Fireman

The Five Fire Classifications

January 1, 2009 by  
Filed under Firefighter News

In a firefighters world, types of fire are broken up into five different classes, so that those with firefighter jobs can have a better system of understanding for the types of fires they face. When people learn how to become a firefighter in a training academy they are fully educated about each fire class, and what methods should be used to fight each type of fire. Each fire class needs to be handled differently, requiring a different strategy to control it. The classifications of fire are listed under either A class, B class, C class, D class or K class. As a side note, in the United Kingdom, the K class is known as the F class.

Class A Fires

Class A fires are the most common in today’s firefighting world. These fires are caused by wood and other combustible materials. Other fires that are considered part of this class are campfires, candle fires, and fires caused by matches or lighters. A fire requires three things, also known as a fire triangle, to stay hot. These three things are heat, oxygen, and a source of fuel. Class a fires require all three of these things in order to continue. When oxygen is available, and the material becomes hot enough to cause combustion, flames often result, spreading the fire to other materials around it. Generally, a campfire is safe and contained, however under the right circumstances such as a wind gust or a spark landing in the surrounding brush the fire will leave the confines of the campfire into the surrounding area. This type of fire accident can quickly spread into surrounding forest. This is known as an A class fire. Water is commonly used to extinguish this type of fire, and it does so by removing the oxygen and heat. Certain chemicals such as those found in household fire extinguishers can also smother the flames.

Class B Fires

Class B fires use the same fire triangle as class A fires, however gasoline or another similar fuel is used as a substitution for wood. Class B fires cannot be extinguished easily with water so a foam or co2 based product is usually used to smother the fire. The K class is very similar to the B class with the only difference being the use of cooking oils as the source for the fire. Specially designed fire extinguishers are used for this class.

Class C Fires

Class C fires are caused by electrical devices or defective appliances. The fire triangle in this situation uses the electrical current in place of a lighter or match as the source of heat for the fire. Using water to extinguish this type of fire would result in electrocution, so it should never be used. Many firefighters have died while fighting this type of fire because of the electrical current traveling up the water stream into the hose. To extinguish a class C fire the oxygen section of the fire triangle must be interrupted. To do this, a special protein based foam is often used, or if possible, the source of the electricity is cut off. Special fire extinguishers can be used to fight this class of fire.

types-of-firesClass D Fires

Class D fires are fires that deal with metals. These metals can be magnesium, uranium, calcium, potassium, sodium, plutonium, or titanium. These types of fires are very hot, often reaching over 1200 degrees. Water should not be used to extinguish this type of fire because water actually makes the fire hotter in this case. A dry powder is often used to extinguish these fires, which smothers the oxygen supply to the fire.