Fuel
Classification / Extinguisher Type
The
following refers to the U.S. classification of
fires. There is some minor distinction to that
used by the British.
All
fires are not the same, and they
are classified according to the type of fuel that
is being burnt. If the wrong type of fire extinguisher
is used on the wrong class of fire, it is quite
possible to have a worse situation on your hands
or even a fatality. It is therefore critical that
you understand the four different fire classifications.
Class
A - Wood, paper, cloth, and other
organic substances. Solid combustible
materials that are not metals leaving an ash after
burning
Class
B - Flammable liquids and gases:
gasoline, oil, grease, and acetone. Any
non-metal in a liquid state, on fire.
Class
C - Electrical: energized electrical
equipment. Fire of electrical origin.
Class
D - Metals: potassium, sodium, aluminum, magnesium
Unless you work in a laboratory or in an industry that uses these materials,
it is unlikely you'll have to deal with a Class D fire. It takes special extinguishing
media for extinguishment.
TYPES
OF EXTINGUISHERS ON CAMPUS
Water
Designed for Class A (wood, paper, cloth etc) fires only.
These usually come in a 2 ½ gallon stainless steel cylinder but there
are also some spray type in white cylinders with blue writing located on
campus. There is also a pressure gauge at the top which tells that the extinguisher
is ready fro use if the arrow is on the green area and need recharging if
the arrow is in the “recharge” area.
Never use water to extinguish flammable liquid fires. Water is ineffective
media to extinguishing this type of fire, and you may spread the fire rather
than contain and extinguish it.
Never use water to extinguish an electrical
fire. Water is a good conductor of electricity,
and there is the possibility of electrocution if
water is used to extinguish an electrical fire.
Carbon Dioxide
Designed for Class B and C (flammable liquid and electrical) fires only.
These extinguishers are filled with non-flammable carbon dioxide gas under
pressure. CO2 extinguishers are red and easily recognizable by their distinct
horn at the end of the discharge hose and the absence of pressure gauge and
range in size from 5 lbs to 100 lbs or larger.
Carbon Dioxide is a non-flammable gas that extinguishes fire by displacing
oxygen, or taking away the oxygen element of the fire triangle. It
may be ineffective in extinguishing Class A fires because it might
not be able to displace enough oxygen to put the fire out causing it to smolder
and re-ignite.
Precautions should be taken when using this extinguisher since it could create
an oxygen deficient atmosphere.
Dry Chemical Extinguishers
Designed for Class A, B and C (wood, paper, cloth etc flammable liquid and
electrical) fires OR B and C alone (flammable gases / liquid and electrical)
fires
Dry Chemical Extinguishers are usually composed of monoammonium
phosphate or sodium bicarbonate pressurized using nitrogen.
They are red and range in size
from 5 lbs to 20 lbs on campus. There is also a pressure gauge at the top which
tells that the extinguisher is ready fro use if the arrow is on the green area
and need recharging if the arrow is in the “recharge” area.
Dry chemical extinguishers put separate the fuel from the oxygen in the air
through a smothering process. They require some clean up after use but are
extremely effective at putting out fire.
