|
|
There are basically four different types or classes of fire
extinguishers, each of which extinguishes specific types of fire.
Newer fire extinguishers use a picture/labeling system to designate
which types of fires they are to be used on. Older fire extinguishers
are labeled with colored geometrical shapes with letter designations.
Both of these types of labels are shown below with the description of
the different classes of extinguishers.
Additionally, Class A and Class B fire extinguishers have a numerical
rating which is based on tests conducted by Underwriter’s
Laboratories that are designed to determine the extinguishing
potential for each size and type of extinguisher. Click on any of the
topics listed below for additional information that may be helpful to
know. |
|
Fire
Extinguisher Ratings |
 |
Class A Extinguishers will
put out fires in ordinary combustibles, such as wood and paper. The
numerical rating for this class of fire extinguisher refers to the
amount of water the fire extinguisher holds and the amount of fire
it will extinguish. |
 |
|
|
|
 |
Class B Extinguishers should
be used on fires involving flammable liquids, such as grease,
gasoline, oil, etc. The numerical rating for this class of fire
extinguisher states the approximate number of square feet of a
flammable liquid fire that a non-expert person can expect to
extinguish. |
 |
|
|
|
 |
Class C Extinguishers are
suitable for use on electrically energized fires. This class of fire
extinguishers does not have a numerical rating. The presence of the
letter “C” indicates that the extinguishing agent is
non-conductive. |
 |
|
|
|
|
Class D Extinguishers are
designed for use on flammable metals and are often specific for the
type of metal in question. There is no picture designator for Class
D extinguishers. These extinguishers generally have no rating nor
are they given a multi-purpose rating for use on other types of
fires. |
 |
|
Multi-Class
Ratings
|
 |
Many extinguishers available today can be used on different
types of fires and will be labeled with more than one designator,
e.g. A-B, B-C, or A-B-C. Make sure that if you have a multi-purpose
extinguisher it is properly labeled. |
| This is the old style of labeling indicating suitability for
use on Class A, B, and C fires. |
 |
 |
This is the new style of labeling that shows this extinguisher
may be used on Ordinary Combustibles, Flammable Liquids, or
Electrical Equipment fires. This is the new labeling style with a
diagonal red line drawn through the picture to indicate what type of
fire this extinguisher is NOT suitable for. In
this example, the fire extinguisher could be used on Ordinary
Combustibles and Flammable Liquids fires, but not for Electrical
Equipment fires. |
|
Types of Fire
Extinguishers
|
 |
Dry Chemical extinguishers are usually rated
for multiple purpose use. They contain an extinguishing agent and
use a compressed, non-flammable gas as a propellant. |
 |
Halon extinguishers contain a gas that
interrupts the chemical reaction that takes place when fuels burn.
These types of extinguishers are often used to protect valuable
electrical equipment since them leave no residue to clean up. Halon
extinguishers have a limited range, usually 4 to 6 feet. The initial
application of Halon should be made at the base of the fire, even
after the flames have been extinguished. |
 |
Water These extinguishers contain
water and compressed gas and should only be used on Class A
(ordinary combustibles) fires. |
 |
Carbon Dioxide (CO2) extinguishers are most
effective on Class B and C (liquids and electrical) fires. Since the
gas disperses quickly, these extinguishers are only effective from 3
to 8 feet. The carbon dioxide is stored as a compressed liquid in
the extinguisher; as it expands, it cools the surrounding air. The
cooling will often cause ice to form around the “horn”
where the gas is expelled from the extinguisher. Since the fire
could re-ignite, continue to apply the agent even after the fire
appears to be out. |
|
How to Use a Fire
Extinguisher
Even though extinguishers come in a number of shapes and sizes, they
all operate in a similar manner. Here's an easy acronym for
fire extinguisher use:
|
P A S
S -- Pull,
Aim,
Squeeze,
and Sweep |
| Pull
the pin at the top of the extinguisher that keeps the handle from
being accidentally pressed. |
| Aim
the nozzle toward the base of the fire. |
| Stand approximately 8
feet away from the fire and Squeeze
the handle to discharge the extinguisher. If you release the
handle, the discharge will stop. |
| Sweep
the nozzle back and forth at the base of the fire. After the fire
appears to be out, watch it carefully since it may re-ignite! |
|
