How a Fire Extinguisher Works

  •  Portable fire extinguishers apply an extinguishing agent that will either cool burning fuel, displace or remove oxygen, or stop the chemical reaction so that a fire cannot continue to burn.
  • When the handle of an extinguisher is compressed, agent is expelled out of the nozzle.

DID YOU KNOW?

For fire to exist, the following four elements must be present at the same time:

  • Enough oxygen to sustaincombustion;
  • Enough heat to raise thematerial to its ignition

    temperature;

  • Some sort of fuel orcombustible material; and
  • The chemical reaction thatis fire.

 

Types of Fire Extinguishers

 All extinguishers are given an alpha-numeric classification based on the type and size of fire they will extinguish.

 The numbers serve as a guide for the amount of fire the extinguisher can handle. The higher the number, the more fire-fighting power.

 The letters represent the type(s) of fire for which the extinguisher has been approved.
 The following table provides information regarding the type of fire and which fire extinguisher should be used:

EXTINGUISHER TYPE

TYPE OF FIRE/ LOCATION

A: Ordinary Combustibles

SYMBOL

Air-Pressurized Water (APW)

Fires in paper, cloth, wood, rubber, and many plastics require a water type extinguisher labeled A.

Locations:

APWs are found in older buildings and offices, particularly in public hallways.

IMPORTANT: Never use water to extinguish flammable liquid or electrical fires.

B: Flammable Liquids

Fires in oils, gasoline, some paints, lacquers, grease, solvents, and other flammable liquids require an extinguisher labeled B.

C: Electrical Equipment

Fires in wiring, fuse boxes, energized electrical equipment, computers, and other electrical sources require an extinguisher labeled C.

Locations:

Carbon dioxide extinguishers

CO2/ Dry Chemical

are found in industrial vehicles, mechanical rooms, offices, computer labs, and flammable liquid storage areas.

A: Ordinary Combustibles B: Flammable Liquids C: Electrical Equipment Locations:

Multi-Purpose

These extinguishers are found in public hallways, laboratories, mechanical rooms, break rooms, chemical storage areas, offices, commercial vehicles, and other areas with flammable liquids.

K: Kitchen Fires

Fires involving combustible cooking fluids such as oils and fats.

Locations:

Dry and Wet Chemical

These extinguishers are found in commercial cooking operations such as restaurants, cafeterias, and other locations where food would be served.


 

How to Use a Fire Extinguisher

 Follow the P.A.S.S technique to put out a fire:

1) PULL…Pull the pin. This will break the tamper seal.

2) AIM…Aim low, pointing the extinguisher nozzle (or its horn or hose) at the base of the fire. (Note: Do not touch the plastic discharge horn on CO2 extinguishers. It gets very cold and may damage skin!)

3) SQUEEZE…Squeeze the handle to release the extinguishing agent.
4) SWEEP…Sweep from side to side at the base of the fire until it appears to be out.

Watch the area. If the fire reignites, repeat steps 2 – 4.

NOTE: IF YOU HAVE EVEN THE SLIGHTEST DOUBT ABOUT YOUR ABILITY TO FIGHT A FIRE, EVACUATE IMMEDIATELY!

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