User Manual

33
with a fine water mist. The nitrogen effectively reduces
the oxygen content of the room atmosphere, while the
water mist provides additional cooling and prevents re-
ignition, without causing damage to the stored objects.
IT and electrical plant rooms
A gas extinguishing system can provide efficient fire
protection for electrical and electronic installations. This
would be an appropriate solution for the protection of
server rooms, particularly as no residues are left behind
after an extinguishing incident and fire damage can be
kept to a minimum. Such systems are very effective in
putting out fires and preventing re-ignition, allowing
normal operation to be resumed as quickly and smoothly
as possible.
Standard applications include centralized systems and
modular systems. In a centralized system, all gas cylinders
are installed in a central location outside the protected
zone and preferably in a dedicated storage room.
Centralized systems always require a site-specific design,
as all pipe diameters and nozzles must be calculated
individually according to the particular application.
Modular and centralized extinguishing systems
Modular systems, on the other hand, consist of space-
saving compact units that are installed within the
protection zone itself. These units combine fast and
reliable detection with quiet and safe extinguishing in one
compact package. Such systems are particularly suitable
for the protection of small enclosures with volumes up to
132 m
3
that contain electronic and electrical equipment.
The main cost-saving advantage of such systems is that
they can be installed quickly and easily, and service and
maintenance costs are very low.
Several years ago the fire protection industry became
aware of potential disruptions to magnetic hard disk
drives and storage systems during the discharge of gas
extinguishing systems. Studies by Siemens and
independent organizations concluded that it was
primarily the high noise level generated by conventional
extinguishing systems during the discharge process that
created the hard disk drive malfunctions. The findings
conclude that all magnetic hard disk drives available today
are noise sensitive. However, by selecting the appropriate
extinguishing system and nozzle as well as implementing
the appropriate silent extinguishing measures, noise-
induced disruptions to hard disk drives and entire storage
systems can be minimized. For more information please
refer to the white paper on this topic.
Kitchens
The fire risk in kitchens is relatively high. This is due to
a combination of the cooking materials used (cooking
oils, fats, etc.) and the heat from the hot cooking equip-
ment (hot-plates, ovens, vats, etc.). Kitchen fires are
predominantly fat fires, which often start spontaneously
and rapidly generate an intense heat. The flames are also
fed by the highly combustible fat vapors and can only be
checked by interrupting the oxygen supply and reducing
the temperature of the cooking oil.
An additional problem related to kitchen fires is their
inherent ability to spread through the kitchen’s own air
extraction system to the rest of the building. The critical
areas (e.g. cooking range, deep fat fryers, ovens and air
extraction system) should be protected by specially
designed extinguishing systems. Wet chemical fire
extinguishers (Class F) should also be provided.
When extinguishing systems are used in commercial
kitchens, then these are generally wet chemical systems,
which are installed immediately above the protection area
or within the air extraction hoods. They are stand-alone
systems, which both detect the fire and extinguish it
automatically.
The effectiveness of this extinguishing agent relies on the
cooling of the hot surfaces together with a highly
efficient fire suppression mechanism. On contact with the
hot fat, the extinguishing agent foams up to produce
a soapy layer. This creates a dense barrier between the
hot fat and the surrounding air, effectively preventing the
highly volatile fat vapors from escaping and re-igniting
the fire.
If the building is equipped with a sprinkler system, then
this should be extended to protect the other parts of the
kitchen. However, it must be ensured that the water spray
from the sprinklers cannot reach the critical areas of the
cooking range, deep fat fryers, ovens and air extraction
system.