Fire Extinguisher Rating - What does it mean?

Did you know that there is such a thing as using the wrong fire extinguisher.  Using the wrong one can make fires even worse!  For example, if you use a water-based fire extinguisher on an electric fire, you will end up spreading the fire and exposing yourself to electrocution.

Fire extinguishers are divided into different categories, based on different types of fires which are represented by the letters A, B and C.  Each fire extinguisher also has a numerical rating that serves as a guide for the amount of fire the extinguisher can handle.

Class A extinguishers are for ordinary combustible materials such as paper, wood, cardboard, and most plastics.

Class B fires involve flammable or combustible liquids such as gasoline, kerosene, grease and oil.

Class C fires involve electrical equipment, such as appliances, wiring, circuit breakers and outlets. Never use water to extinguish class C fires - the risk of electrical shock is far too great! Class C extinguishers do not have a numerical rating. The C classification means the extinguishing agent is non-conductive.

The number indicates the approximate relative fire extinguishing capacity of the extinguisher for that class (A or B) of fire. Generally the larger the extinguisher, the larger the numbers. The numbers are ONLY associated with the letters A and B.

For some examples, a 4-A extinguisher can put out approximately twice as much fire as a 2-A extinguisher, and a 20-B:C extinguisher can put out approximately twice as much flammable liquid fire as a 10-B:C extinguisher.

Multi-Purpose Dry Chemical (MPDC) Fire Extinguisher

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