are likely to start. The AFFF system mixes
FIRE-EXTINGUISHING SYSTEMS
concentrated AFFF with seawater from the
The fire-extinguishing systems discussed in this
firemain. A mixture of 6 percent foam and
section are limited to fixed equipment. The
94 percent seawater is used to blanket (smother)
portable fire-fighting equipment is mentioned for
a fire. After the water is initially drained off, a
information purposes only. The fire-fighting
film remains denying oxygen to the fuel source.
Being sealed off from reignition allows time
systems are numerous and vary among the
different ship classes. The fire-fighting systems
for cooling off. Each AFFF station aboard ship
supports several hose reel/sprinkling heads in
discussed here include the Halon 1301 system, the
aqueous film forming foam (AFFF) system, and
its area. Each AFFF station usually has a con-
the fixed CO2 system. Other systems or fire-
centrate storage tank and a foam proportioner.
fighting equipment used onboard ship include the
The mixture discharged from the proportioners
aqueous potassium carbonate system, portable
is piped either to sprinkling heads or hose
CO2 fire extinguishers, and portable potassium
connections.
bicarbonate (PKP) extinguishers. You will have
to qualify on the systems pertinent to your ship
during your general damage control qualifications.
HALON 1301
installed in the GTE modules and certain other
FIRE-EXTINGUISHING SYSTEM
auxiliary spaces on various classes of ships. When
CO2 release is activated, a time delay permits
Halon fire extinguishing is accomplished by
personnel to escape from the space before CO2
flooding a space with Halon 1301 gas to interrupt
is actually released. A pressure switch in each
the chain reaction during combustion. Halon 1301
system activates audible and visual alarms locally
is a colorless, odorless, electrically nonconductive
and remotely (usually at the DCC). Ventilation
vapor that puts out fires by using a different
fans serving the affected area are also shut
principle than most other fire-extinguishing
down.
systems. While CO2, water, or foam attack fire
by smothering, cooling, or separating the fuel
from its oxygen source, Halon combines with the
fuel vapors/oxygen molecules in such a way as
SUMMARY
to stop the combustion process from occurring.
The amount of Halon 1301 gas stored on the
We have described the functions and opera-
various class ships is solely dependent on the
tions of the following auxiliary and support
number and volume of the spaces being protected.
systems for the gas turbine powered ships in this
Although Halon 1301 is a very low toxicity
chapter: the LO fill and transfer system, the main
vapor allowing limited exposure without detri-
LO system, the FO systems, the bleed air system,
mental effects, it decomposes upon contact with
the compressed air systems, the drainage and
flames and on hot surfaces above 900F. While
ballast systems, the firemain system, the seawater
this action is necessary for the product to
service system, the steam and waste heat systems,
function effectively as a fire-extinguishing agent,
and the fire extinguishing systems. You will need
it also results in the formation of several
to become familiar with all of these systems to
new chemical compounds, which have different
properly operate the engineering plant. While the
properties. These post combustion products are
main engines are the heart of the engineering
lethal in large concentrations, but they are easily
plant, without the support systems the ship would
detectable at sublethal levels by eye, skin, and
not operate.
mucous membrane irritation. At higher sublethal
levels, a sour taste becomes evident.
As you can see in reading through this chapter,
the systems vary greatly between ship classes and
even between ships of the same class. You should
AQUEOUS FILM FORMING
study your own ship's engineering plant and read
FOAM SYSTEM
the ship's EOSS and technical manuals to be able
The AFFF system provides fire protection for
to operate, repair, and maintain your individual
ship's equipment.
areas of the ship where major fuel and/or oil fires
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