because it tends to settle and blanket the fire. CO2 is a
dry, noncorrosive gas, which is inert when in contact
with most substances and will not leave a residue and
damage machinery or electrical equipment. CO2 is a
nonconductor of electricity regardless of voltage, and
can be safely used in fighting fires that would present
the hazard of electric shock.
displacing its oxygen supply.
If gaseous CO2 is
directed into a fire so that sufficient oxygen to support
combustion is no longer available, the flames will die
out. CO2 has limited cooling capabilities, and may not
cool the fuel below its ignition temperature. It is more
likely than other extinguishing agents to allow reflash.
Therefore, the fire fighter must remember to stand by
with additional backup extinguishers.
NOTE: CO2 is not an effective extinguishing agent
for fires in materials that produce their own oxygen
supply, such as aircraft parachute flares or fires
involving reactive metals, such as magnesium and
Halon is a halogenated hydrocarbon. Halon 1211,
known chemically as bromochlorodifluoromethane, is
colorless and has a sweet smell. Halon attacks the fire
by inhibiting the chemical chain reaction.
decomposes upon contact with flames or hot surfaces
above 900°F (482°C).
Halon 1211 is used for twin agent (AFFF/Halon
1211) applications on board flight and hangar deck
mobile fire-fighting equipment. For flight and hangar
deck fire-fighting procedures, you should refer to
NATOPS U.S. Navy Aircraft
Fire-Fighting and Rescue Manual.
Potassium Bicarbonate (Purple-K-Powder or PKP)
Potassium bicarbonate (PKP) is a dry chemical
principally used as a fire-fighting agent for flammable
When PKP is applied to fire, the dry
chemical extinguishes the flame by breaking the
PKP does not have cooling
capabilities on fire.
PKP is highly effective in
Although PKP can be used on electrical (class C) fires,
it will leave a residue that may be hard to clean. Also,
when combined with moisture, it may corrode or stain
the surfaces it settles on.
PKP does not produce a lasting inert atmosphere
above the surface of a flammable liquid. Therefore, its
use will not result in permanent extinguishing if
ignition sources, such as hot metal surfaces or
persistent electrical arcing, are present. Reflash of the
fire will most likely occur. The ingredients used in PKP
However, the discharge of large
quantities may cause temporary breathing difficulty
and, immediately after the discharge, it may seriously
interfere with visibility.
Q12-1. What are the four elements necessary to
Q12-2. What is the "fire point" of a substance?
Q12-3. What is the "flash point" of a substance?
Q12-4. What are the four classes of fire?
Q12-5. What are the primary fire-extinguishing
agents used aboard naval ships?
LEARNING OBJECTIVE: Recognize the
various systems and equipment used for
aircraft fire-fighting on board ships and shore
In assisting the crash fire fighters, you will use very
specialized equipment. A crash crew must bring its
equipment into action with every pump nozzle
delivering at its maximum capacity.
equipment is discussed in the following text.
You must get acquainted with the firemain system
throughout your ship. You should know the location of
the firemain and the riser piping that carries water to the
upper decks. You must be able to identify the plugs
where hoses can be attached to the mains. You must
know the location of all pumps, valves, and controls in
the vicinity of your duty and berthing stations.
Fireplugs have outlets either 1 1/2 or 2 1/2 inches in
diameter. Some plugs are equipped with wye gates that
provide two outlets, each are 1 1/2 inches in size. In
some cases, a reducing connection is used so that a
1 1/2-inch hose can be attached to a 2 1/2-inch outlet.
Connected to the fireplugs and stored in adjacent
racks are two lengths of either 1 1/2- or 2 1/2-inch
diameter hose. The 1 1/2-inch hose is used on smaller
ships and below decks on larger ships. This hose is
made up in 50-foot lengths, with the necessary end