How to Use a Fire Extinguisher

Author By: Ana M. Ferrer
Updated Date: September 23, 2014
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Having a fire extinguisher in the house could be what saves your life in the event of a fire. But do you know how to use one? Learning to use a fire extinguisher is an important task that everyone in the household should learn. Keep reading to find out how to use a fire extinguisher and learn more about the different types of extinguishers available. 

Types of fire extinguishers 

All fires need oxygen, heat and fuel to burn, and a fire extinguisher's purpose is to eliminate one of those elements. Different materials require different suppression tactics--hence different types of fire extinguishers. They will either cool the burning fuel or remove/displace the oxygen. 
  • Water extinguishers are filled with water and pressurized with air. The most common way to remove heat from a fire is to douse it with water. However, depending on the type of fire, this may not be the best course of action. These extinguishers are suitable for Class A fires only--if used on class B it could spread the flammable liquid and if used in class C, it could create a shock hazard. 
  • Dry chemical extinguishers are filled with foam or powder, either potassium bicarbonate or sodium bicarbonate, and pressurized with nitrogen. Baking soda is effective because it decomposes at 158 degrees F and releases carbon dioxide which smothers oxygen. Dry chemical extinguishers interrupt the chemical reaction of the fire by coating the fuel with a thin layer of powder or foam and separating it from the oxygen. These are suitable for class C fires.
  • Carbon dioxide (CO2) extinguishers are filled with pressurized CO2, a non-flammable gas that removes the oxygen component of the fire. Because they are so highly pressurized, it's common for particles of dry-ice to come out as well. These are suitable for class B fires. 
  • Multi-purpose dry chemical extinguishers are suitable for use on class A, B and C fires. 

Using the fire extinguisher 

No matter what type of extinguisher you have, they are all operated the same way. Remember this: P-A-S-S. 
  • Pull: Pull the safety pin from the handle and nozzle
  • Aim: Aim the nozzle toward the fire
  • Squeeze: Squeeze the handle to let the water/CO2/dry chemical release
  • Sweep: Sweep side to side at the base of the fire until it goes out. 

If the fire reignites, repeat the steps until it is completely out. 

You should evacuate immediately if:

  • The fire has gone past the early stages and has extended beyond the original ignited material
  • You have any doubts about your ability to extinguish the fire
  • The fire extinguisher is empty and flames are still present

Fire classes 

As stated previously, there are different types of fires and the specific extinguishers needed for each one are classified using a letter-symbol system. 
  • Class A: Class A fires consist of ordinary combustibles such as wood, paper, fabric, plastic and most trash. 
  • Class B: Class B fires consist of gasoline, oil, paint and other flammable liquids.
  • Class C: Class C fires include electrical fires involving energized electrical equipment such as motors, transformers and appliances
  • Class D: Combustible metals like potassium, sodium, aluminum and magnesium are considered Class D fires. Class D fires require specialized extinguishers labeled "D." 
  • Class K: These fires consist of cooking oils, greases, animal fats and vegetable fats.