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on video What is a Fire Alarm System?

 




Fire alarm systems are designed to alert us to an emergency so that we can take action to protect ourselves, staff and the general public.


Regardless of the detection method, if the alarm goes off, sirens will sound to warn people in the building that there may be a fire and to evacuate.




In this video we will see the structure and types of "Fire Alarm Systems".


The “brain” of the system is the fire alarm control panel. It is the central hub for all hard-wired detector signals and provides status indication to users.


The unit can also be configured to simulate an alarm for use in routine fire and evacuation drills, so all personnel know what action to take in the event of a real fire.


There is a wide range of different types, but we can divide them into groups including heat detectors, smoke detectors, carbon monoxide detectors, multi-sensor detectors and manual call points.




A heat detector can either operate on a fixed temperature basis, where it will sound an alarm if the temperature exceeds a preset value, or operate on the rate of temperature change.


There are three basic types of smoke detectors, namely ionization, light obscuration, and light scattering.


In the light-obscuring smoke detector, smoke interferes with a light beam between a light source and a photocell. The photocell measures the amount of light it receives.


The variation of the photocell output is used to trigger an alarm. This type of detection can be used to protect large areas with the light source and the photocell positioned at a certain distance.


The light scattering smoke detector operates on the Tyndall effect; a photocell and a light source are separated from each other by a darkened chamber so that the light source does not fall on the photocell.


The photocell output is used to trigger an alarm.




Carbon monoxide detectors are also known as CO fire detectors and are electronic detectors used to indicate the outbreak of a fire by sensing the level of carbon monoxide in the air.


Carbon monoxide fire detectors use the same type of sensor as home detectors, but they are more sensitive and respond faster.


Carbon monoxide detectors have an electrochemical cell that detects carbon monoxide, but not smoke or any other combustion products.


Multi-sensor detectors combine inputs from optical and thermal sensors and process them using a sophisticated algorithm built into the detector circuitry.


When interrogated by the control panel, the detector returns a value based on the combined responses of the optical and thermal sensors. They are designed to be susceptible to a wide range of fires.




A manual call point or glass break call point is a device that allows personnel to raise the alarm by breaking the frangible element on the fascia; this then triggers the alarm.


Fire alarm systems can be divided into four main types; “Conventional”, “Addressable”, “Intelligent Fire Systems” and “Wireless Systems”.


In a conventional fire alarm system, physical wiring is used to interconnect multiple call points and detectors, whose signals are fed back to the main control unit.


The detection principle of an addressable system is the same as that of a conventional system, except that each detector is given a set address (usually by means of a DIP switch) and the control panel can then determine exactly which detector or call point triggered the alarm. .


In our next type of system, which is an intelligent fire alarm system, each detector effectively integrates its own computer which assesses the environment around it and communicates to the control panel if there is a fire, fault or whether the detector head needs to be cleaned.


The last type of system we will consider is the wireless fire alarm system. It is an effective alternative to traditional wired fire alarm systems for all applications.

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