Table of Contents

Introduction Basic types of fire extinguishers Which kind of extinguisher should I use? Using fire extinguishers Disclaimer

Introduction

Fire is the most common serious hazard that one faces in the home. This document teaches you the basics about fire extinguishers -- proper types, how to use them, when and when not to use them as well as the proper procedures to follow should a fire occur. It is not a comprehensive guide; be sure to read the disclaimer given below.

If your clothing is on fire (and the floor is not), STOP, DROP and ROLL on the ground to extinguish the flames.

Return to top of this page

Basic types of fire extinguishers

The three most common types of extinguishers are pressurized water, dry chemical and carbon dioxide.

In addition, you may also have a specialized Class D dry powder extinguisher for use on flammable metal fires (in a pinch, a bucket of dry sand will do, but you really should have a Class D unit if you work with flammable metals). Water-filled extinguishers are not acceptable for flammable metals. If you have a water-filled extinguisher, have it replaced immediately.

If you are not familiar with fire extinguishers and have not been trained in their use, DO NOT attempt to use them!.

Return to top of this page

Which kind of extinguisher should I use?

First recognize that there are four different kinds of fires:

• Class A fires are ordinary materials like burning paper, lumber, cardboard, plastics etc.
• Class B fires involve flammable or combustible liquids such as gasoline, kerosene, and common solvents.
• Class C fires involve energized electrical equipment, such as appliances, switches, panel boxes, power tools, hot plates, etc.. Water is a particularly dangerous extinguishing medium for class C fires because of the risk of electrical shock.
• Class D fires involve combustible metals, such as magnesium, titanium, potassium and sodium. These materials burn at high temperatures and will react violently with water, air, and/or other chemicals. Handle with care!!

Some fires may be a combination of these! Your fire extinguishers should have ABC ratings on them. These ratings will often have numbers on them that look something like "3-A:40-B:C". Higher numbers mean more firefighting power. In this example, the extinguisher has a good firefighting capacity for Class A, B and C fires.

Here are typical uses for common extinguishers:

• Water extinguishers (not pictured and not found in laboratories) are suitable for class A (paper etc.) fires, but not for class B, C and D such as burning liquids, electrical fires or reactive metal fires. In these cases, the flames will be spread or the hazard made greater!

• Dry chemical extinguishers are useful for class ABC fires and are your best all around choice. They have an advantage over CO₂ extinguishers in that they leave a blanket of non-flammable material on the extinguished material which reduces the likelihood of reignition. They also make a terrible mess -- but if the choice is a fire or a mess, take the mess! Note that there are two kinds of dry chemical extinguishers!
  • Type BC fire extinguishers contain sodium or potassium bicarbonate.
  • Type ABC fire extinguishers contain ammonium phosphate.

• CO₂ (carbon dioxide) extinguishers are for class B and C fires. They don't work very well on class A fires because the material usually reignites. CO₂ extinguishers have an advantage over dry chemical in that they leave behind no harmful residue -- a good choice for an electrical fire on a computer or other delicate instrument. Note CO₂ is a bad choice for a flammable metal fires because CO₂ reacts with these materials. CO₂ extinguishers are not approved for class D fires!

• Metal/Sand Extinguishers are for flammable metals (class D fires) and work by simply smothering the fire. You should have an approved class D unit if you are working with flammable metals.

Check out the potential fire hazards in your area.  Is there an extinguisher available?  Do you know how to operate it?  Are your extinguishers suitable for the fires you may encounter?

Return to top of this page

Using fire extinguishers

You are not required to fight a fire. Ever. If you have the slightest doubt about your control of the situation DO NOT FIGHT THE FIRE. Please see the Disclaimer below.
1. Use a mental checklist to make a Fight-or-Flight Decision.  Attempt to use an extinguisher only if ALL of the following apply:
   The building is being evacuated (fire alarm is pulled)

   The fire department is being called (dial 911).

   The fire is small, contained and not spreading beyond its starting point.

   The exit is clear, there is no imminent peril and you can fight the fire
          with your back to the exit.

   You can stay low and avoid smoke.

   The proper extinguisher is immediately at hand.

   You have read the instructions and know how to use the extinguisher.

   
   

   IF ANY OF THESE CONDITIONS HAVE NOT BEEN MET, DON'T FIGHT THE FIRE YOURSELF.
   CALL FOR HELP, PULL THE FIRE ALARM AND LEAVE THE AREA.

   
   

   • Whenever possible, use the "Buddy System" to have someone back you up when using a fire extinguisher. If you have any doubt about your personal safety, or if you cannot extinguish a fire, leave immediately and close off the area (close the doors, but DO NOT lock them). Leave the building but contact a firefighter to relay whatever information you have about the fire.

   • Pull the pin on the fire extinguisher.

   • Stand several feet from the fire, depress the handle and sweep back and forth towards the fire. Note:
     • Do not walk on an area that you have "extinguished" in case the fire reignites or the extinguisher runs out! Remember: you usually can't expect more than 10 full seconds of extinguishing power on a typical unit and this could be significantly less if the extinguisher was not properly maintained or partially discharged.

     • The metal parts of CO₂ extinguishers tend to get dangerously cold -- practice using one beforehand or have someone show you the proper way to hold one.

     • Again, proper training is usually required by state or federal OSHA!

     • Direct the extinguisher at the base of the flames until the fire is completely out.

     • Recharge any discharged extinguisher immediately after use. If you discharge an extinguisher (even just a tiny bit) or pull the pin for any reason, arrange to have it recharged or replaced.

Return to top of this page

Questions?

Disclaimer: This page contains guidelines for the use of fire extinguishers and is not meant to be a comprehensive reference. There are many circumstances that these guidelines cannot foresee and you should recognize the inherent danger in relying solely on this information!

If you would like information on the proper use of fire extinguishers (including some hands-on training) contact your local fire department.

Return to top of this page