FIRE EXTINGUISHERS
2
100-CAH-01-IGDO © 2025, Workplace Safety & Prevention Services (WSPS)
1 877 494 WSPS (9777) | 905 614 1400 | WSPS.CA
Fire Extinguishing Methods
Fires can be extinguished in one or four ways:
1. By cooling: Water is used to cool the burning material below the temperature at which it starts to burn
2. By smothering: Carbon dioxide (CO
2
) or foaming agents are used to smother the burning material so
that air is excluded
3. By removing the fuel source: (an example is turning off a fuel line)
4. By disrupting the chemical chain reaction or interrupting the flame: Dry chemicals or halon are used
to do this
Types of Fire Extinguishers
To help in choosing the proper fire extinguisher, fires are classed A, B, C, or D, according to the type of
fuel (e.g., paper, grease, oil) that is involved in the fire. Fire extinguishers are available for use on one or
more classes of fire, depending on the extinguishing agent they contain (e.g., water, chemicals). Figure 1
(below) will help you to match types of fire extinguishers to different classes of fire.
Figure 1: Matching Classes of Fire and Types of Fire Extinguishers
FUEL SOURCES CLASS OF FIRE TYPE OF FIRE EXTINGUISHER
(EXTINGUISHING AGENT)
Ordinary combustibles
(e.g., trash, wood, paper, cloth)
A
Water; chemical foam; dry chemical
1
Flammable liquids
(e.g., oils, grease, tar, gasoline,
paints, thinners)
B
Carbon dioxide (CO
2
); halon
2
; dry
chemical; aqueous film forming foam
(AFFF)
Electricity
(e.g., live electrical equipment)
C
CO
2
; halon; dry chemical
Combustible metals
(e.g., magnesium, titanium)
D
Dry powder (suitable for the specific
combustible metal involved)
1
Dry chemicals, CO
2
and halon can be used on Class A fires, but may not be effective on their own. They may needto be
supplemented with water.
2
Halon fire extinguishers are no longer made, but some may still be in use. Dangerous gases are formed when halon is
used to put out fires. Wear proper respiratory equipment, particularly in enclosed spaces. After use, do not allow anyone
to enter the area until it has been well ventilated.
WSPS.CA
