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Classes of Fires

This article outlines the different classes of fires, the materials involved, and how to deal with them.

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Class A fires are those which involve ordinary combustible materials such as wood, paper or cloth. These fires should be extinguished by using a dry chemical extinguisher. Water is effective in extinguishing these types of fires, however, water extinguishers are rarely found in the Medical Center.

Class B fires are those which involve flammable liquids, gases, oil, paint and greases. Either dry chemical or carbon dioxide extinguishers should be used to extinguish these types of fires. Note: flammable liquids may re-ignite after being extinguished. DO NOT USE WATER!

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Class C fires are those which involve electricity. Either dry chemical or carbon dioxide extinguishers should be used to extinguish these types of fires. DO NOT USE WATER!

Class D fires are those which involve combustible metals such as magnesium or sodium. Water can react with sodium and other alkali metals explosively, therefore DO NOT USE WATER! Also understand that CO2 extinguishers are unlikely to be able to contain a Class D fire.