|
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
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 (Select
images for a closer view) |
 |
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. Normally Sodium Bi Carbonate is used
in Dry Chemical Powder (DCP) and Mono Ammonium Phosphate
(MAP) is used in ABC type fire extinguishers. |
 |
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 as they 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. These are being phased
out due ozon layer deplition. In India use of Halon1211 is
banned now but in several under developed countries this
agent is still in use. |
 |
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! |
 |
Congratulations
-- you did it!!! |
|