Published 05.08.15

The ABC’s of Fire Extinguishers

In order for a fire to start there are three main components that must be present, a fuel source, oxygen, and a heat source.
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These three elements are commonly known as the “Fire Triangle.” When all three of the elements are present, a fire ignites and can quickly become a very large problem for you and your business. Fire extinguishers are a great way to prevent small fires from becoming large ones, but how do you know which extinguisher to use on which kind of fire?

Fires are classified into specific “types” based on their fuel source.

  • Class A – ordinary combustible materials like cloth, paper and wood
  • Class B – for flammable liquids like gasoline, alcohol and paint
  • Class C – for electrical fires
  • Class D – for combustible metals
  • Class K – for vegetable oils, animal oils or fat used in cooking appliances

The ABC multipurpose fire extinguisher is the most common fire extinguisher and serves as a great “all purpose” fire extinguisher for common areas and paths of egress within your facility. The agent within an ABC fire extinguisher is comprised mainly of mono-ammonium phosphate and ammonium sulphate which acts like a heat seeking missile when introduced onto a heat source. It attaches itself to the material that is heated and smothers the fire until it is suppressed.

The advantage of the ABC multi-purpose fire extinguisher is it’s diverse application under multiple fire conditions. A disadvantage is the agent within this extinguisher is a dry powder and if discharged in a room with sensitive equipment the powder can damage the equipment and can be difficult to fully clean up and remove.

If you find a fire extinguisher other than a standard ABC hanging it is most likely because it is protecting a specific hazard located nearby. For example, in kitchen cooking areas where there is open flame and cooking media, there will always be a silver K-Class extinguisher hanging on the wall. The agent within the extinguisher is a specialized potassium acetate based, low PH liquid designed specifically to coat cooking oil fires and suppress potentially catastrophic kitchen grease fires.

There are several other types of specialized fire extinguishers, including 
D-Class fire extinguishers, clean agent fire extinguishers, water fire extinguishers and more. Take notice of the different types of extinguishers within your facility and ask your Cintas Fire Protection service technician to help you better understand what their purpose is.

Knowing the right fire extinguisher to use at the right time could save your business and even your life, so make sure to educate yourself about the proper application and operation of fire extinguishers.


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