Fire Extinguisher Classes

In the case of a fire, it is critical to use the right fire extinguisher for the job. Selecting the wrong one can actually be more dangerous and contribute to hazards like explosions or electrical shocks. Fire extinguishers are sold with class ratings: class A, Class B, and Class C, determined by the contents. Each class is identified with a symbol and pictogram representing the type of fire it will put out.

  • Class A Rating: Class A fire extinguishers are meant to be used against fires involving paper, wood, plastic, cloth and other ordinary combustible materials. Identified with the letter A inside a green triangle.
  • Class B Rating: Extinguishers with a Class B rating are meant for putting out fires cause by flammable liquids such as gasoline, oil, and paint. Identified as the letter B inside a red square.
  • Class C Rating: Class C extinguishers are designed to be used on fires involving live electrical equipment. Identified with the letter C inside a blue circle.
  • Class D: Fire extinguishers with a Class D rating should be used for combustible materials and combustible metal alloys. Identified with the letter D inside of a yellow star, this is also the only class that does not have a commonly used pictogram.
  • Class K: Extinguishers identified with the letter K are meant to be used on fires involving cooking media such as vegetable oil, animal fats, and grease. Marked with the letter K inside of a hexagon. 

There are multi-purpose fire extinguishers that can be used on more than one type of fire or material; these extinguishers are typically identified as ABC or BC extinguishers. It is critical for employees to be trained on the different Fire Classes for extinguishers, as well as the symbols and pictograms used on portable fire extinguishers. Fire extinguishers should be labeled with large, easy-to-read labels and kept in an easily accessible location.

 
NFPA Labeling Guide
 
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