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Are You Ready
For A
Fire?
Fire
is one of the most common disasters. Fire causes
more deaths than any other type of disaster. But
fire doesn't have to be deadly if you have early
warning from a smoke detector and everyone in
your family knows how to escape calmly.
HOW FIRES
START
Fire is a chemical reaction involving
rapid oxidation or burning of a fuel. It needs
three elements to occur:
 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.
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.
| HOW
FIRES ARE CLASSIFIED |
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CLASS
A |
| Ordinary
combustibles or fibrous material, such
as wood, paper, cloth, rubber and some
plastics. |
 |
CLASS
B |
| Flammable
or combustible liquids such as
gasoline, kerosene, paint, paint
thinners and propane. |
 |
CLASS
C |
| Energized
electrical equipment, such as
appliances, switches, panel boxes and
power tools. |
 |
CLASS
D |
| 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. |
HOW TO
PREVENT FIRES
 Class
A — Ordinary combustibles:
Keep storage and working areas free of trash
Place oily rags in covered containers.
 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. Report any
hazardous condition to your supervisor.
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 buring reaction produces
sufficient oxygen to support combusion, even
under water.
In some cases, covering the burning metal with
sand can help contain the heat and sparks from
the reaction. Class D exinguishing agents are
available (generally as a dry powder in a
bucket or box) which can be quite
effective, but these agents are rare on the
campus.
If you are planning a research project using a
large amount of flammable metals you should
consider purchasing a five or ten pound
container of Class-D extinguishing agent as a
precaution.
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.
All of these metals are not uncommon in labs
on the OU campus, but are generally only found
in small quantities and accidental
fires/reactions can be controlled or avoided
completely through knowledge of the properties
of the metals and using good judgement and
common sense.
WHEN NOT TO FIGHT A FIRE
Never fight a fire:
- If the fire is
spreading beyond the spot where it started
- If you can't fight
the fire with your back to an escape exit
- If the fire can block
your only escape
- If you don't have
adequate fire-fighting equipment
In any of these situations,
DON'T
FIGHT THE FIRE YOURSELF.
CALL FOR HELP.
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