User Manual

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Siemens Switzerland Ltd
Building Technologies Division
3.1.3. Deceptive phenomena
A fire detector has the task of detecting fire from fire aerosols, heat and radiation at an early stage and triggering
an alarm. Aerosols, heat and radiation, however, are also generated by production processes, by electrical
equipment such as motors, or by environmental factors such as sunlight. If these deceptive phenomena are
sufficiently intense and exist over a certain period of time, they may influence fire detectors enough to trigger an
unwanted alarm.
State-of-the-art fire detectors are largely capable of distinguishing between deceptive phenomena and genuine
fires. If, however, massive deceptive phenomena are to be expected, it is often necessary to combine different fire
detectors to provide the best possible solution for that particular application.
3.1.4. Fire detection system
The tasks of an automatic fire detection system are to detect a fire as early as possible, to sound the alarm and to
activate the preprogrammed control functions.
State-of-the-art fire detection systems are capable of detecting fire very early and consequently minimizing any
damage that may be caused. By optimal product selection and appropriate knowledge it is possible to build
systems that virtually eliminate unwanted alarms.
The principal requirement on a fire detection system is early and reliable alarming in the event of fire. As a
consequence of this:
· All persons in the danger zone should be able to save themselves
· Fire control systems can be activated to prevent the fire from spreading to more than one fire sector
· Firefighting can be initiated as early as possible, so that damage to property can be kept to a minimum