The first and most important function of the fire alarm systems is to give an alarm in case of fire, but more importantly, to give this alarm ONLY IN CASE OF FIRE. The annoying siren sounds that are generated unnecessarily make no more sense to the people who use that building after a while than a noise that no one reacts to. Moreover, if this situation becomes very uncomfortable, the sirens are silenced so that they can never sound again.
What do you think is more risky, to have a fire detection system in a building or a fire detection system that is like the boy who cried the wolf and constantly gives false alarms? I'm sure that most of us would say that the boy who cried the wolf is much more risky.
Why do the fire alarm systems give false alarms? Because fire detectors, which are the most important equipment of the fire alarm systems, generate false alarms.
Smoke and heat occur in every fire regardless of the type of fire. Fire detectors are also designed for detecting the emitted smoke or heat.
The smoke detectors consist of a light source, reflective surface and receiving unit. In the normal operation, the light emitted from the source is reflected from the surface and reaches the receiver. In case of fire, the emitted smoke enters between the light source and the receiver and the reflective surface, preventing the reflection of the light and alerting the detector. However, since it will have a similar effect on dust and steam, smoke detectors generate false alarms due to the intense dust and steam generated in the ambient.
The heat detectors monitor the temperature in the ambient or the rate of heat increase. It detects the heat that occurs in case of fire and switches to alarm condition. However, if there is an increase in temperature due to a reason other than fire in the ambient where it is used, the heat detector will also generate a false alarm.
If you say “Well, how will we prevent the false alarms?”, I recommend you to use a combined detector. The combined detectors generate alarms by monitoring both smoke and heat and the rate of heat increase at the same time. More importantly, they eliminate the risk of false alarms by using these three parameters in an algorithm simultaneously.
The combined detectors provide significant advantages for project designing, implementation and operation as well as eliminating false alarms. The uniformity of all detectors facilitates the project designing. It prevents the loss of labor and time arising as a result of incorrect detector installation during the application. It is not required to replace the detector and to keep an inventory separately for each of the different detector types when the intended use of the locations changes at the enterprise. The greatest contribution of using combined detectors to the enterprises, on the other hand, is that they prevent the loss of labor and time in case of evacuation of the building due to false alarms.
