All You Ever Wanted to
Know
About Fire Extinguishers . . .
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 Underwriters 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.
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Fire Extinguisher
Ratings |
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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. |
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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. |
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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. |
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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. |
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Multi-Class
Ratings |
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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.
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This is the old style of labeling indicating suitability for use on Class
A, B, and C fires. |
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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. |
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Types of Fire
Extinguishers |
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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. |
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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. |
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Water These extinguishers contain water and
compressed gas and should only be used on Class A (ordinary combustibles)
fires. |
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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. |
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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
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Pull the pin at the top of the extinguisher
that keeps the handle from being accidentally pressed. |
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Aim the nozzle toward the base of the fire.
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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.
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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! |
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Congratulations -- you did it!!! |
Content provided by:
Document Number: INTERNET-1053, Rev. 0
URL:http://www.hanford.gov/fire/safety/extingrs.htm#fetypes
The Hanford Fire Department is operated by
Fluor Hanford, Inc. for the
U.S. Department of Energy, Richland Operations Office.
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