Fire Extinguisher Size Ratings

If you look on your fire extinguisher and see what looks like an incredibly cryptic, unreadable code that looks something like 3A:21B:A, those numbers simply indicate the size rating of the agent inside the extinguisher itself. Also, the codes can tell you how effective the extinguisher is relative to other fire extinguishing apparatus.

Here’s the breakdown:

Class A size ratings discusses Water equivalency. So on the code the first number is 3A. Each number on that code represents 1 ¼ gallons of water. So above, our extinguisher is as good as 3 ¾ gallons of water. So 3A is the same as 3 ¾ gallons of water.

Class B Rating lets you know the range or square footage the agent can cover. On this code, it says 21B. The number is simply the range relative to feed. So if we took this extinguisher and sprayed it all over, we could cover about 21 square feet.

Class C rating is simply the class of fire extinguisher you’re using. In this case, it’s for ordinary fires.

Therefore, the full code: 3A:21B:A basically lets you know that this particular extinguisher shoots an agent the equivalent of about 3 ¾ gallons of water about 21 square feet – and is best used to put out ordinary fires.

So now you know! And if you need help trying to figure out what extinguishers are most relevant to your surroundings, please contact Protegis Fire & Safety.

Fire Prevention Basics

When is the best time to review fire basics? Now.

Some of the items we are going to cover may be basic, but it never hurts to refresh your memory when it comes to your life.

Rules for Fighting Fires:

  • Activate fire alarm or call 911
  • Get everyone out of the building
  • Only after 1 and 2 are done, do you attempt to extinguish the fire yourself

Fire Safety Tips:

  • Keep fire extinguishers close to any potential fire sources, in plain sight and in easy reach.
  • Have extinguishers serviced professionally at least once a year.
  • Maintain smoke detectors in all areas where fire could possibly occur.
  • Have a plan in case of fire. Have a practice drill every few months.

4 Things Required for a Fire

  • Fuel
  • Heat
  • Oxygen
  • Chemical Reaction

To stop a fire, simply remove any ONE of these things.

5 Classes of Fires

  • Class A: ordinary combustibles like wood, paper, cloth, trash and plastics
  • Class B: flammable liquids like gasoline or flammable gases like propane or butane
  • Class C: energized electrical equipment like motors, transformers and appliances, removing the electrical power turn this into one of the other classes of fire
  • Class D: combustible metals like potassium, sodium, aluminum and magnesium
  • Class K: cooking oils and greases like animal fats and vegetable fats

6 Main Types of Fire Extinguishers

  • Water and Foam – Removes heat and/or oxygen and for Class A fires only
  • Carbon Dioxide – Removes oxygen and heat and for Class B & C fires
  • Dry Chemical (with or without cartridges) – Stops the chemical reaction and for Class A & B & C fires
  • Wet Chemical – Removes heat and creates barrier between oxygen and fuel to prevent re-ignition and for Class K fires
  • Clean Agent – Stops the chemical reaction and for Class B & C fires
  • Dry Powder – Separates the fuel from the oxygen or removes the heat and for Class D fires only

These are just a handful of fire basics. If you have any questions on these or other fire protection topics, please contact Protegis Fire & Safety.