Fire is the third leading cause of accidental deaths in the United States, yet
most people ignore it. More than 1000 residential fires occur every day..
CHEMICAL REACTION - A chain reaction can occur when the three elements of fire are
present in the proper conditions and proportions. Fire occurs when this rapid oxidation,
or burning takes place.
Take any one of these factors away, and the fire cannot occur or will be extinguished if
it was already burning.
Certain combustible metals, such as magnesium, titanium, potassium and
sodium. These metals burn at high temperatures and give off sufficient oxygen to support
combustion. They may react violently with water or other chemicals, and must be handled
with care.
Class A Ordinary combustibles:
Keep storage and working areas free of trash Place oily rags in covered containers. Good
housekeeping is helpful in preventing fires.
Class B - Flammable liquids or gases:
Don't refuel gasoline-powered equipment in a confined space, especially in the presence of
an open flame such as a furnace or water heater.
Don't refuel gasoline-powered equipment while it's hot.
Keep flammable liquids stored in tightly closed, self-closing, spill-proof containers.
Pour from storage drums only what you'll need.
Store flammable liquids away from spark-producing sources.
Use flammable liquids only in well-ventilated areas.
Class C - Electrical equipment:
Look for old wiring, worn insulation and broken electrical fittings.
Prevent motors from overheating by keeping them clean and in good working order. A spark
from a rough-running motor can ignite the oil and dust in it.
Utility lights should always have some type of wire guard over them. Heat from an
uncovered light bulb can easily ignite ordinary combustibles.
Don't misuse fuses. Never install a fuse rated higher than specified for the circuit.
Investigate any appliance or electrical equipment that smells strange. Unusual odors can
be the first sign of fire.
Don't overload wall outlets. Two outlets should have no more than two plugs.
Class D - Flammable metals:
Flammable metals such as magnesium and titanium generally take a very hot heat source to
ignite; however, once ignited are difficult to extinguish as the burning reaction produces
sufficient oxygen to support combustion, even under water.
In some cases, covering the burning metal with sand can help contain the heat and sparks
from the reaction. Class D extinguishing agents are available (generally as a dry
powder in a bucket or box) which can be quite effective, but these agents are rare in
the workplace.
If you work in a industry where there are flammable metals you should ask your employer if
a five or ten pound container of Class-D extinguishing agent is available.
Pure metals such as potassium and sodium react violently (even explosively) with
water and some other chemicals, and must be handled with care. Generally these metals are
stored in sealed containers in a non-reactive liquid to prevent decay (surface
oxidation) from contact with moisture in the air.
White phosphorus is air-reactive and will burn/explode on contact with room air. It must
be kept in a sealed container with a non-reactive solution to prevent contact with air.
Class A - Extinguish ordinary combustibles by cooling the material below its
ignition temperature and soaking the fibers to prevent re-ignition. Use pressurized water,
foam or multi-purpose(ABC-rated) dry chemical extinguishers. DO NOT USE carbon
dioxide or ordinary (BC-rated) dry chemical extinguishers on Class A fires.
Class B - Extinguish flammable liquids, greases or gases by removing the oxygen,
preventing the vapors from reaching the ignition source or inhibiting the chemical chain
reaction. Foam, carbon dioxide, ordinary (BC-rated) dry chemical, multi-purpose dry
chemical, and halon extinguishers may be used to fight Class B fires.
Class C - Extinguish energized electrical equipment by using an extinguishing agent
that is not capable of conducting electrical currents. Carbon dioxide, ordinary (BC-rated)
dry chemical, multi-purpose dry chemical and halon* fire extinguishers may be used to
fight Class C fires. DO NOT USE water extinguishers on energized electrical equipment.
* Even though halon is widely used, EPA legislation is phasing it out of use in favor
of agents less harmful to the environment.
Class D - Extinguish combustible metals such as magnesium, titanium, potassium and
sodium with dry powder extinguishing agents specially designated for the material
involved. In most cases, they absorb the heat from the material, cooling it below its
ignition temperature.
NOTE: Multipurpose (ABC-rated)chemical extinguishers leave a residue that
can harm sensitive equipment, such as computers and other electronic equipment. Because of
this, carbon dioxide or halon extinguishers are preferred in these instances because they
leave very little residue. ABC dry powder residue is mildly corrosive to many metals. For
example, residue left over from the use of an ABC dry powder extinguisher in the same room
with a piano can seriously corrode piano wires.
Look at the gauge and feel the weight. Is the extinguisher full? Does it need to be
recharged?
Water, some foam, and dry chemical extinguishers have gauges indicating the pressure
inside the extinguisher. The pressure needle should be in the "green" area (generally
100-175 lbs., depending on the type of agent).
CO2 (carbon dioxide) extinguishers are high pressure cylinders with
pressures ranging from 1500 lb psi. to 2150 lb psi. These extinguishers DO NOT have gauges
and must be weighed to determine the amount of contents remaining.
Make sure the pin, nozzle and nameplate are intact.
The APPEARENCE of different types of extinguishers:
Generally, you can tell with a glance which type an extinguisher is hanging on
the wall, or in the cabinet, just by looking at its shape. Check the labels of the
extinguishers in your area and note the color and shape/size of the extinguisher. This may
help if someone runs in to help you fight a fire with the WRONG extinguisher (i.e.
water on an electrical fire) - you can STOP them before they are injured or make
matters worse!
ABC-rated multipurpose dry powder extinguishers are the most common, particularly
in the corridors of commercial and academic buildings. They are almost always RED in color
and have either a long narrow hose or no hose (just a short nozzle). These
extinguishers are very light (5-25 lbs total weight) Halon extinguishers look
virtually identical to ABC multipurpose dry chemical extinguishers.
Water extinguishers are not often used in a commercial setting and are usually SILVER (chrome-metal)
in color, have a flat bottom, have a long narrow hose, are quite large (2-1/2 gallons).
Foam extinguishers look similar and the type without gauges have a handle inset in the
flat bottom (you turn the extinguisher upside down to start it and use it)
CO2 (carbon dioxide) extinguishers are generally red (often yellow around
aircraft or on military sites), have a LARGE "tapered" nozzle (horn),
are VERY HEAVY (15-85 lbs.) -some CO2 extinguishers for aircraft hangers or special
industrial use are so large as to require roll-around carts to move them. These are all
high-pressure cylinders.
Care should be used NOT TO DROP a CO2 cylinder; if it is damaged it can become a missle
due to the pressure contained in the cylinder. (The containers are quite sturdy, but
don't abuse them.) CO2 cylinders do not have a pressure gauge - they must be weighed
to determine the amount of contents. Back to Top
The last one out of the room should not lock the door, just close it. Locking the door
hinders the fire department's search and rescue efforts.
Proceed to the nearest exit.
NEVER, NEVER use elevators under any circumstances.
Stay low to avoid smoke, so crawl if necessary.
If possible, cover your mouth and nose with a damp cloth to help you breathe.
If you work in a building with multiple stories, a stairway will be your primary escape
route. Most enclosed stairwells in buildings over two stories are "rated"
enclosures and will provide you a safe means of exit; don't panic descend stairs slowly
and carefully.
Once in the stairwell, proceed down to the first floor. Never go up.
Once outside the building, report to your meeting place so that a head count can be
taken.
FUEL - Fuel can be any combustible
material - solid, liquid or gas. Most solids and liquids become a vapor or gas before they
will burn.
OXYGEN - The air we breathe is about
21 percent oxygen. fire only needs an atmosphere with at least 16 percent oxygen.
HEAT - Heat is the energy necessary
to increase the temperature of the fuel to a point where sufficient vapors are given off
for ignition to occur.
