Fuel and oxygen are just two components for a fire to ignite and grow in an environment. Depending on the environment and the fuel present depends on the classification of a fire and how each fire should be extinguished. Knowing each class and how to handle a situation, should it occur, can help prevent loss of property or life, or help guide first responders to a better understanding of the situation.
Class A fires are ordinary combustibles, or what you typically may think of when thinking of fuels for fires; wood, paper, cloth, trash and plastics are all in this category.
Removing an essential component is key to fighting these types of fires. Smothering a fire can reduce the presence of oxygen, while dousing the flames with water can remove heat and fuel source. Sometimes, physically removing the fuel source can be a way to reduce and maintain the fire.
Fires classified as Class B are fueled by flammable liquids or gases, such as gasoline, petroleum, paints, non-cooking oils, propane and butane.
To extinguish these fires, the use of water is ineffective and can cause more damage. Because of the nature of the fire and fuel source, sometimes these fires are quick and will burn out without the fuel source. However, foam is commonly used in this type of fire. Assessing the danger is key to any fire, especially when dealing with Class B and the proximity and amount of fuel because it can be very dangerous.
Energized electrical equipment found in appliances and motors will classify a fire as Class C. This means, toasters, lamps, coffee makers, overloaded outlets and other common appliances found around the house or office.
These classes of fires can not be fought with water or foam because they will create a greater risk due to the presence of electricity. Carbon dioxide fire extinguishers or ones loaded with dry chemical are effective. If possible, the first step is to cut the source of power.
Believe it or not, certain metals are combustible depending on the presence of a source of ignition that causes a chemical reaction. The alkali metals, sodium, potassium, lithium, rubidium and cesium are the most reactive class of metals. These can react with something as common as water to cause ignition. Aluminum can be combustible if in a finely divided powder or dust state.
If water didn’t initially start a reaction and the fire, it can certainly energize these type of fires. Dry powder is the most effective way to extinguish and control these types of fires. The powder absorbs the heat and acts to smother the flames by cutting off their supply of oxygen.
Fires that result from cooking oils, butter and greases are known as Class K fires. These can occur from the ignition of vegetable and animal fat that reacts with a heat source, such as an open flame or stove top.
These fires tend to burn hot, so some previous methods will not work. Due to the fuel type, splashing and subsequent burns are highly possible, so attempting to extinguish the flames should be done with extra care. Some fire extinguishers are equipped with hoods used to reduce supply of oxygen by lowering over the flame. Extinguishers rated for Class K fires will contain a wet chemical which essentially turns the grease into soap.
For each type of fire, it is important to remain calm and act quickly with proper understanding and knowledge. Notifying first responders through the phone or by pulling an alarm could be a life-saver if the situation is out of your control. Knowing a fire is beyond your control means if the fire is not small and contained, if there’s presence of toxic smoke, and if your instincts tell you whether you’re safe or not. Remember, being prepared and understanding how to react should a situation arise could help prevent unforeseen damage and loss.
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