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FM-200™ is a clean, safe
fire fighting agent for use on total flooding automatic extinguishing
systems. It is intended as a long term replacement for Halon
1301 and, whilst maintaining the excellent fire suppression properties
of Halon, has none of the environmental problems. Storage and
distribution requirements are similar to Halon and the majority
of system components are identical. However, FM-200™ design
concentration is not a direct replacement for existing Halon
1301 installations due to the difference in agent quantity and
discharge characteristics. The FM-200™ design concentration
for 'normal' risks is 7 1/2% and therefore requires approximately
60% additional storage capacity over that required for Halon
in the same area.
The manufacturers claim that
FM-200™ is safer than Halon 1301 for use in total flooding
applications and the US Environmental Protection Agency (EPA)
accepts extended use exposures of upto 9%. This has been further
confirmed by a recently published HAG report. FM-200™ is
rated as Zero Ozone Depletion (ODP), is electrically non-conductive,
clean, and leaves no residue.
The U.S. EPA, in the Federal
Register, May 12, 1993, recognised the inherent safety of FM-200™
in accepting it for use in occupied space protection at upto
9.0% v/v without mandated egress times, or upto 10.5% v/v with
mandated egress times. This means that occupied spaces can be
safely evacuated, even in the presence of FM-200™ at design
concentrations.
The United States Environmental
Protection Agency (US EPA) states, "HFC-227ea (FM-200) does
not deplete stratospheric ozone. In addition, HFC-227ea is the
most effective of the proposed HFC substitutes for Halon 1301."
FM-200™ (HFC-227ea) is
a clean, gaseous agent containing no particulates or oily residues.
It is produced under ISO 9002 guidelines to strict manufacturing
specifications ensuring product purity. FM-200™ leaves
no residue or oily deposits on delicate electronic equipment,
and can be removed from the protected space by ventilation.
FM-200™ is thermally
and chemically stable, but without the extremely long atmospheric
lifetimes associated with other proposed Halon replacements.
The atmospheric lifetime of FM-200™ has been determined
to be between 31 and 42 years. The US EPA does not consider FM-200™
to be a long lived substance and as such has placed no restrictions
on its use.
FM-200™ can decompose
at high temperatures to form halogen acids. If so, their presence
is readily detected as a sharp, pungent odour long before hazardous
maximum exposure levels are reached. Fire toxicity studies conclude
that generally decomposition products from the fire itself, especially
carbon monoxide, smoke, heat, and oxygen depletion, create a
greater hazard.
ARGONITE fire extinguishing
systems, utilise a pure 50/50 gaseous mixture of Nitrogen and
Argon. Both gases are naturally occurring and pose no threat
to the environment. The extinguishant is stored in high pressure
cylinders normally filled at 150 or 200 bar at 15 degrees C.
(Refer to actual rating label on the cylinders). ARGONITE will
safely and effectively extinguish fires in most applications.
Systems are designed to provide
a residual oxygen level of 12.5%, thereby allowing operation
in automatic mode whilst personnel are present; (As laid down
in the Halon Alternative Group report "Review of Toxic
and asphyxiating hazards of Clean Agent Replacements for Halon
1301".)
The fire extinguishing capability
of ARGONITE is achieved by the reduction of atmospheric oxygen
level to below that which supports combustion. For most materials
this is below 15% but above 10% LOEL (Lowest Observable Effect
Level), and the level which can support human life with minimal
effect and discomfort. Systems are designed to provide a residual
oxygen level of 12.5%, thereby providing a margin of safety on
extinguishing and survivability.
ARGONITE systems generally
comprise of a number, or bank of high pressure cylinders, each
connected to a series of cylinder manifolds via flexible high
pressure hoses and non-return valves. The main manifold is fitted
with a pressure reducing orifice prior to its connection to the
distribution pipe work
Carbon Dioxide (CO2) is a Standard
Commercial Product with many other uses and it is readily available
throughout the World.
At normal temperatures and
pressure Carbon Dioxide is an odourless and colourless inert
Gas with a density of approximately 50 per cent greater than
the density of Air.
It is an Inert Gas, Non-Corrosive
with no harmful effect on most materials. It will not contaminate
foodstuff. It disperses leaving no material trace.
It has great Dielectric strength
and can be applied safely to live electrical equipment.
It is discharged as Gas and
it will penetrate into otherwise inaccessible positions.
It provides its own pressure
for discharging through Valves, Pipework and Nozzles.
CO2 extinguishes fire by reducing
the Oxygen content in the atmosphere to a point where it will
not support combustion.
Reducing the Oxygen content
from the normal 21% on Air to 15% will extinguish most Surface
Fires. For some materials, however, it must be reduced even lower.
The dilution of the Oxygen
in the Air, by the CO2 Concentration that will extinguish fire,
may create atmospheres that will not sustain life. Such atmospheres
will be produced in spaces protected by CO2 Total Flooding and
may be produced by any large volume discharges drifting into
adjacent low places.
Persons rendered unconscious
in these atmospheres can usually be revived without any permanent
ill effects when promptly removed from such atmospheres.
Large volume discharges of
CO2 may seriously interfere with visibility during and immediately
after the discharge period.It is therefore essential that all
precautions are taken and the correct locking off procedures
are followed as well as the system being well maintained.
The pressure within the C02
Cylinder varies with changes in ambient temperature, the pressure
increases with rising temperature. At 21°C (70°F) the
pressure would be 850lb/in2.
Each Cylinder Valve incorporates
a Safety Disc designed to rupture and discharge the CO2 contents
at a pressure safely below the cylinders test pressure.Care must
be taken, therefore, to ensure that the CO2 cylinders are not
installed in a position where the temperature is likely to exceed
60°C (140°F).
Pyramid
Fire Protection Limited
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fire
extinguishing systems
