valves can be opened automatically � either locally
or remotely � or manually using pneumatic,
electric or mechanical valve actuators. Two or
more areas can be protected with a single group
of CO2 cylinders by means of directional or
selector valves.
On release, CO2 discharges as a colourless,
odourless, electrically non-conductive, and non-
corrosive gas that quickly floods the entire
protected area and extinguishes the fire. This is
achieved mainly by reducing the oxygen level to
less than the 15 percent necessary to allow
combustion to take place. The gas also provides a
measure of localised cooling.
This permeation of the CO2 gas, coupled with it
being heavier that air, makes it ideal for suppress-
ing fires in the ducts and voids beneath raised
floors that are commonly used in switchroom
enclosures to house extensive cabling. This cabling
can represent a significant fire hazard that may be
difficult to locate, with the potential to cause
serious damage if it is not quickly extinguished.
CO2 can be compressed into a liquid state
which, when maintained under pressure, requires
a smaller storage footprint than many of the other
gaseous suppression agents on the market.
Another factor in CO2's favour is its low cost in
comparison with many alternative suppression
agents. Additionally, as CO2 has so many other
commercial uses, refills are readily available
throughout the world.
Local discharge
Not all fire risks lend themselves to total flooding
suppression; portable extinguishers are frequently
the only workable solution, and CO2 portable
extinguishers have been used successfully for
many years.
This is borne out by the sheer number of fires
that are extinguished every year using portables,
and without the need for the intervention of the
fire and emergency services. According to figures
produced by Britain's Fire Extinguishing Trades
Association � now merged with the British Fire
Protection Systems Association to form the Fire
Industry Association � portable extinguishers save
the British economy alone around �500 million
every year and completely extinguish around
66,000 fires. This compares with statistics from the
Department of Communities and Local Govern-
ment that show that the fire and rescue service in
the UK attended 88,400 fires in buildings in the
UK in 2006.
However, there is a tendency to view portable
extinguishers as commodity products; an attitude
that should be avoided at all costs. The difference
between a quality extinguisher and one of some-
what dubious origin or manufacturing pedigree is,
at most, a few pounds. Compare this with the
portable's potential ability to immediately suppress
a fire without the need to evacuate the premises,
call for assistance from the emergency services, or
risk damage to business critical equipment, and
the cost saving plunges to the realms of the
ridiculous.
So, with the proviso of ensuring the build
quality and reliability of the portable extinguisher,
CO2 is an eminently suitable suppressant in many
commercial and industrial situations, and is
particularly suitable for use on electrical fires. IFP
INTERNATIONAL FIRE PROTECTION 81
CO2 SUPPRESSION � EFFECTIVE, VERSATILE AND COST-EFFECTIVE
CO2 SUPPRESSION

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