Halon 1211 and Halon 1301 are severe ozone
concentrations between 7 and 10 percent and Halon
depleting substances. These agents should be used
1211 concentrations between 3 and 4 percent,
o n l y a ga i n s t a c t u a l fi r e s . A ny H a l o n cy l i n d e r
personnel experienced dizziness and tingling of the
containing only a partial charge, or is being turned in to
extremities, indicative of mild anesthesia. At Halon
supply, shall not be vented to the atmosphere for any
1301 concentrations above 10 percent and Halon 1211
reason.
concentrations above 4 percent the dizziness becomes
pronounced, the subjects feel as if they will lose
Halon 1301 (known chemically as
consciousness (although none have), and physical and
bromotrifluoromethane) consists of one atom of
mental dexterity is reduced.
carbon, three atoms of fluorine, no chlorine atoms,
o n e b r o m i n e a t o m , a n d n o i o d i n e a t o m s . Fo r
The discharge of Halon 1211 to extinguish a fire
shipboard installation, Halon 1301 is super
may create a hazard to personnel from the natural
pressurized, with nitrogen, and stored in gas cylinders
Halon 1211 itself and from the products of
as a liquid. When released, it vaporizes to a colorless,
decomposition that result from the exposure of the
odorless gas with a density of approximately five
agent to the fire or other hot surfaces. Prolonged
times that of air Halon 1301 systems (fig. 6-18). It
exposure to concentrations greater than 4 percent
may be installed in main machinery rooms, fire
carries with it the possible risk of unconsciousness
rooms, engine rooms, auxiliary machinery rooms,
and even death. Although Halon 1211 vapor has a low
fuel pump rooms, ship service or emergency
t o x i c i t y, i t s d e c o m p o s i t i o n p r o d u c t s c a n b e
generator rooms, auxiliary boiler rooms, main
hazardous. When using Halon 1211 in unventilated or
propulsion or generator engine modules, helicopter
confined spaces, operators and others should avoid
recovery assist, securing and traversing (RAST)
breathing the gases, and should only use the agent
areas, machinery rooms, tactical towed array sonar
(TACTAS) handling rooms, and in spaces where
needed to accomplish extinguishment. Although they
flammable liquids are stored or issued. Aboard
are potentially hazardous, no significant adverse
aircraft carriers, gas-powered bomb hoist storerooms
health effects have been reported from the use of
may be protected by Halon 1301.
Halon 1301 or 1211 as a fire-extinguishing agent
since their introduction into the marketplace 30 years
ago.
WARNING
In flammable gas cylinder storerooms,
20 percent Halon 1301 is required to
extinguish a fire. Therefore, if the system is
activated, personnel must leave the space
immediately.
Direct contact with vaporizing Halon 1301 and
Halon 1211 liquid has a strong chilling effect on
objects and can cause frostbite and burns to the skin.
The liquid phase vaporizes rapidly during discharge
and therefore limits this hazard to the immediate
vicinity of the nozzle.
High velocity discharge from nozzles is sufficient
Figure 6-18. Halon 1301 system.
to move unsecured paper and light objects, which
could cause personnel injury. Discharge of a total
H a l o n s y s t e m s u s e o n e o r m o r e cy l i n d e r s
flooding system can cause noise loud enough to be
containing Halon 1301 in a liquid form. The function
startling.
of the system is to extinguish fires that are beyond the
capacity of portable fire extinguishing equipment, and
In humid atmospheres, reduction in visibility may
occur due to condensation of water vapor in the air.
where abandonment of the space is necessary.
6-15
