REVIEW QUESTIONS
applications on some flight and hangar deck mobile
fire-fighting apparatus. Portable 20-pound Halon 1211
fire extinguishers are installed in MHC-51 class
Q12.
The CO2 flooding system is used for spaces
coastal minesweeping ships and air-cushion landing
that are normally occupied by personnel.
craft (LCAC). Halon 1211 is stored and shipped as a
liquid and pressurized with nitrogen gas.
1.
True
Pressurization is necessary since the vapor pressure is
2.
False
too low to convey it properly to the fire area.
Q13.
When using the CO2 hose-and-reel system,
Halon 1211 is not used in total flooding systems. It
you should always direct the CO2 discharge
has a low volatility combined with a high liquid
toward the base of the fire.
density, which permits the agent to be sprayed as a
liquid. As a liquid spray Halon 1211 may be propelled
1.
True
into the fire zone more effectively than is possible with
2.
False
other gaseous agents. Halon 1211 is used in twin agent
Q14.
Before operating an installed CO2 system,
systems installed on mobile firefighting apparatus on
you should ensure all openings in the
carrier type ships. For flight and hangar deck
compartment are closed and the ventilation
f i r e - f i g h t i n g p r o c e d u r e s , r e f e r t o N AVA I R
system for the space is secured.
00-80-R-14, NATOPS U.S. Navy Aircraft Firefighting
and Rescue Manual.
1.
True
Both Halon 1211 and 1301 chemically inhibit the
2.
False
flame front of a fire. Halon decomposes upon contact
with flames or hot surfaces above 900F (482C).
Decomposition products are principally hydrogen
fluoride and hydrogen bromide, which have a sharp
HALON SYSTEMS
irritating odor even at low concentrations.
Learning Objective: Recall the location, design
The short discharge time of Halon 1301
components, and capabilities of shipboard Halon
(10 seconds maximum) keeps the thermal
systems.
d e c o m p o s i t i o n p r o d u c t s w e l l b e l ow l e t h a l
concentrations. However, a real hazard lies in the
Halon is a halogenated hydrocarbon, which means
products of combustion from the fire such as carbon
that one or more of the hydrogen atoms in each
monoxide. These products combined with oxygen
hydrocarbon molecule have been replaced by one or
depletion, heat, and smoke pose a great hazard to
more atoms from the halogen series (fluorine, chlorine,
personnel.
bromine, or iodine). A Halon numbering system has
been developed to provide a description of the various
WARNING
halogenated hydrocarbons. The first digit in the
number represents the number of carbon atoms in the
Personnel should not remain in a space
molecule; the second digit, the number of fluorine
where Halon 1301 has been released to
atoms; the third digit, the number of chlorine atoms;
extinguish a fire unless some type of breathing
the fourth digit, the number of bromine atoms; and the
apparatus is worn.
fifth digit, the number of iodine atoms, if any. In this
system, terminal zero digits, if any, are not expressed.
Most people can be exposed to a 5 to 7 percent
concentration of Halon 1301 for a period up to 10
The two types of Halon used aboard Naval ships
minutes without danger to their health. However,
safety precautions dictate that spaces should be
commonly used type because it is installed and used in
evacuated anytime a Halon system discharge occurs.
fixed flooding systems for extinguishing flammable
liquid fires.
Human exposures to both Halon 1301 and to Halon
1211 have shown that Halon 1301 concentrations up to
Halon 1211 is a colorless gas that has a
a b o u t 7 p e r c e n t b y vo l u m e , a n d H a l o n 1 2 1 1
s w e e t s m e l l a n d i s k n ow n c h e m i c a l l y a s
concentrations of 2 to 3 percent by volume, have little
bromochlorodifluoromethane. It is used for twin agent
noticeable effect on personnel. At Halon 1301
aqueous film-forming foam (AFFF)/Halon 1211
6-14
