User Manual

Siemens Switzerland Ltd 26
Building Technologies Division
Extinguishing is controlled either manually or preferably automatically by means of a fire detection system. Only a
quick, faultless actuation prevents consequential damage, as a fire should be extinguished during its formation
phase. However, to prevent human casualties, an alarm must first be sounded to warn people of the imminent
flooding of the area. The gas will only be released after a predefined delay has given people sufficient time to
evacuate the area.
When the system is actuated, the cylinder valves of high-pressure systems (or the container valves of low-pressure
systems) will be opened. Doors and other openings are closed automatically and any other air-handling
equipment (e.g. ventilation systems and smoke dampers) are controlled to ensure that the area is sealed off.
However, the inrush of the extinguishing gas into a closed room will automatically increase the pressure within
the room. To prevent damage occurring, overpressure relief dampers mechanisms temporarily open, before re-
closing again automatically.
The extinguishing gas is guided through a piping network to nozzles that are evenly distributed on the ceiling. The
gas quickly fills the room and a homogenous concentration is built up throughout the room. To completely
extinguish the fire, this concentration must be maintained over a sufficiently long period of time.
Figure 4.3.2-1 Principle of a gas extinguishing system