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Learn about the chemical reaction of fire, its ingredients, classes (such as A, B, C) and appropriate extinguishing methods. Get insights on fire extinguisher ratings and use for different fire classes.
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What is Fire? A chemical reaction that involves the evolution of light and energy in sufficient amounts to be perceptible.
What are the ingredients needed to make fire? Oxygen Fuel
What are the ingredients needed to make fire? Fuel Oxygen Heat
What are the ingredients needed to make fire? Fuel Oxygen Chemical Reaction Heat
What are the classes of fire? “A”, “B”, “C” “D” “E” & “K”
Class “A” fire • Classification of fire involving ordinary combustibles such as wood, paper, cloth, plastics, and rubber.
Class “B” fire. • Classification of fire involving flammable and combustible liquids, gases, and greases. Common products are gasoline, oil, alcohol, propane and cooking oils.
Class “C” fire. • Classification of fire involving energized electrical equipment, where the electrical nonconductivity of the extinguishing media is of prime importance.
Class “D” fire • Classification of fire involving combustible metals and alloys such as magnesium, sodium, lithium and potassium.
Class “E” fire • Classification of fires involving nuclear materials. Due to radioactive contamination, smoke from fires involving nuclear materials may produce more harm than the fire itself.
Class “K” fire • Classification of fire that involves fires in combustible cooking fuels such as vegetable or animal oils and fats. In the kitchen
Class “A” • Water is used in a cooling or quenching effect to reduce the temperature of the burning materials below its ignition temperature.
Class “A” • Water can also be used to suffocate the fire by creating steam which displaces the oxygen needed for combustion.
Class “B” • The most effective method of extinguishing this type of fire is to smother with foam or to remove the fuel.
Class “B” • Another method of extinguishing is temperature reduction which can be accomplished by applying water fog.
Class “C” • These fires can sometimes be controlled by a non-conducting extinguishing agent such as Halon, dry chemical, or carbon dioxide.
Class “C” • The safest method of control is to first de-energize the circuit then treat as the class of the fuel involved.
Class “D” • There is no single agent that will control or extinguish fires in all combustible materials.
Class “D” • Water is ineffective and may in fact cause more harm. Hitting some class “D” fires with water will cause them to explode and burn hotter.
Class “D” • Certain metals will continue to burn until they have exhausted the fuel supply.
Ratings of Fire Extinguishers • Class “A” and “B” extinguishers are rated by the size fire they should be able to put out.
Ratings of Fire Extinguishers • Class “C” and Class “D” extinguishers are only labeled for the materials they extinguish.
Ratings of Fire Extinguishers • Class “D” extinguishers are also labeled to indicate the specific metal they are to be used on.
Ratings of Fire Extinguishers • Class “A” ratings are 1A to 40A. • A 1A extinguisher contains 1 ¼ gallons or 5 L of water… A rating of 2A contains 2 ½ gals or 10 L • A dry chemical extinguisher with a 10-A rating is equivalent to five 2 ½ gal. extinguishers.
