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 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 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 OUR 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 judgment
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.
HOW TO EXTINGUISH SMALL
FIRES
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.
Carbon dioxide or halon extinguishers are provided for most labs and
computer areas on campus.
HOW TO IDENTIFY THE PROPER
FIRE EXTINGUISHER
All ratings are shows on the extinguisher faceplate. Some
extinguishers are marked with multiple ratings such as AB, BC and
ABC. These extinguishers are capable of putting out more than one
class of fire.
Class A and B extinguishers carry a numerical rating that indicates
how large a fire an experienced person can safely put out with that
extinguisher.
Class C extinguishers have only a letter rating to indicate that the
extinguishing agent will not conduct electrical current. Class C
extinguishers must also carry a Class A or B rating.
Class D extinguishers carry only a letter rating indicating their
effectiveness on certain amounts of specific metals.
