What is the Meaning of the Ratings for Fire Extinguishers?

Posted November 13, 2019 by Koorsen Fire & Security

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Before you can understand the ratings of fire extinguishers, you’ll first need to understand the different classifications of fire. There are five different classifications of fire:

  • Class A – Ordinary Combustibles (wood, paper, or textiles)
  • Class B – Flammable Liquids/Gases (gasoline, propane, and solvents)
  • Class C – Energized Electrical (computers or fax machines)
  • Class D – Flammable Metals (magnesium, lithium, or titanium)
  • Class K – Kitchen Media (cooking oils and fats)

The rating of a fire extinguisher is designed to help users understand the class and size of a fire in which the extinguisher is meant to be used. Only two classifications of fire include a number with the rating, Class A and B. This number has a different meaning for each class.

For Class A, the rating is to help measure how many gallons of water the extinguisher is equivalent to when fighting the fire. 1A is equal to 1.25 gallons of water. For example, a 4A rated extinguisher would be equivalent to using 5 gallons of water to fight the fire.

The number rating for Class B fire extinguishers is based on square footage as opposed to gallons like the Class A rating. 1B is interpreted as the extinguisher being capable of extinguishing a 1 square foot Class B fire. For example, a 40B extinguisher should allow a novice operator the ability to cover and extinguish a 40 square feet Class B fire.

Know Your Ratings

It is important that everyone understands the ratings behind fire extinguishers. Having this knowledge can be crucial in the event of a fire. If you’re around a fire, you’ll want to know which type or class of fire it is, so you know which type of fire extinguisher you need to use. The next step would be understanding the rating / size of that extinguisher, so you know what you’re up against. The most common fire extinguisher is the ABC fire extinguisher. This means that the extinguisher can be used in a Class A, B, or C fires. Now how does this work for ratings? The ratings on ABC fire extinguishers vary, but let’s say the one available to you is 10A:120B:C. This means that the extinguisher is equivalent of having 12.5 gallons of water to fight a Class A fire and could cover 120 square feet of a Class B fire. Since it carries the C rating, it is also safe to use on an energized electrical fire.

Do You Need Extinguishers for Your Building or Facility?

There’s a lot that goes into purchasing, placement, maintenance, and testing of fire extinguishers for your business. Contact a fire extinguisher expert from Koorsen Fire & Security today to have all of your questions answered. In the event of a fire, you want to ensure you have the correct type of fire extinguisher for that area of your facility.

Contact Koorsen today for assistance in finding the solution to all of your fire extinguisher needs. One of our highly trained and certified technicians can visit your business to discuss all fire extinguisher options and what works best for your facility in more detail.

Topics: Fire Extinguisher

Disclaimer: The information in this article is for informational purposes only. It is believed to be reliable, but Koorsen Fire & Security assumes no responsibility or liability for any errors or omissions in the content of this article. It does not constitute professional advice. The user of this article or the product(s) is responsible for verifying the information's accuracy from all available sources, including the product manufacturer. The authority having jurisdiction should be contacted for code interpretations.