The fire alarm system is a system that monitors situations of fire and provides instant communication to the occupants and security personnel about fire or the incident that may lead to a fire.
A complete fire alarm system constitutes
- Fire Detection System
- Notification / Alarm System
Fire, considered to be the worst disaster that spreads rapidly to destroy properties and life can be difficult to overcome at later stages of growth. With timely warnings, the intensity of occurrences of any calamity can be drastically minimized.
A fire alarm system that consists of automatic fire detectors, manual call points, sounders, etc. is designed for the purpose of providing early fire warnings. With these signs, occupants can take the opportunity to leave and also immediately take necessary action in suppressing the fire at its very early stage.
The fire detection part of the complete fire alarm system is responsible for detecting or sensing the presence of fire alone. The process of warning the occupants through audiovisual utilities such as sirens, hooters, etc. is taken care of by the alarm system.
The fire detection and alarm system function together to provide timely fire warnings to those in emergency zones.
Fire detection can either be
- Automatic
- Manual
Automatic Fire Detection:
Automatic fire detection is achieved by fire sensors/ detectors. Smoke or heat are considered the best indicators of fire. Hence, fire detectors use these parameters to sense the presence of fire.
Fire detectors such as smoke detectors, heat detectors, etc. act only as measuring instruments to measure values of smoke/heat in their surveillance. They automatically declare fire when the level of smoke/heat in its surveillance is beyond its pre-programmed threshold/upper limit value.
Once the detectors declare fire, the alarm sounders begin to operate automatically.
Manual Fire Detection:
Manual fire detection occurs when the manual call points or call stations are triggered manually by those who confirm fire or other situations of emergency.
By actuating the fire call points, the sirens, beacons, etc. will begin to sound warning the occupants of the fire.
Fire Alarm system constitutes fire detection system and alarm/notification system. Fire detection is achieved automatically with fire detectors such as smoke detector, heat detector, multi-sensors(smoke+heat sensors), etc. Fire detection can also be achieved manually through manual call points/call stations etc.
All the devices that initiate fire warnings such as fire detectors or manual call points etc. are regarded as alarm initiating devices.
The devices that respond to fire initiation and warn the occupants with audiovisual utilities such as sirens, sounder beacons, speakers, etc. are called notification/ alarming devices.
All of the initiating(detectors, call points, etc.) and notifications devices(sounder beacons, speakers, etc.) are altogether connected to one central and control unit called the Fire Alarm Control Panel. This is the central unit that controls and monitors the whole fire alarm system.
Fire detectors such as smoke detectors, heat detectors, etc. act only as measuring instruments to measure values of smoke/heat in their surveillance. The detectors send the measured values to the fire alarm control panel and it is the panel that compares the live values with the pre-programmed threshold values of smoke/heat. It then provides the instruction to the sounders to sound only when the level of smoke/heat is beyond its threshold/ fixed upper limit.
Fire alarm systems are of various types as listed below that differ in the suiting the size, complexity, or type of application/building the system needs to be installed in
- Addressable fire alarm system
- Wireless Addressable fire alarm system
- Conventional fire alarm system
- Standalone
A Zone is a specific area of a full building. Buildings are split into zones for identification purposes. For example, the first floor of a building can be identified as a zone. Similarly, the second floor the same can be another zone.
Zones are kept small enough for easy identification of the area. Buildings of large size and increased complexity can have multiple zones and a very small building can even be a single zone.
For example, In case a building is large-sized and complex, the zones can be split as below
First floor:
- Left side→ Zone 1
- Right side→ Zone 2
Second floor:
- Left side→ Zone 3
- Right side→ Zone 4 etc.
We can now identify zone 3 as the left side of the second floor. By increasing the number of zones or references for splitting the building, location identification can be made easier. The architecture of the building can also influence the number of zones.
In a fire alarm system, all devices such as fire detectors, call points, sounders, etc. will be wired together zone-wise to a common fire alarm control panel. In case of fire detected by any detector/ call point in the network, the zone that the initiating device is wired in will be indicated in the control panel.
As per the above example, if a smoke detector on the left side of the second floor has detected fire, the control panel will indicate a fire emergency at Zone 3. With this information, the area in an emergency can be identified with ease.
The conventional system is an old technique to construct a fire alarm system. All devices such as detectors, MCPs, etc. are wired zone-wise and is connected to the Conventional Fire Alarm Panel that has LED as indicators for each zone.
If a device detector goes into alarm, the control panel will be able to identify which zone has gone into alarm, but will not have the exact location of the fire or which device triggered the alarm.
Such a system keeps up to the basic necessities of an alarm system and is preferred for small applications or projects that work on a tight budget.
Large and complex applications may require finer diagnostic details of the location in the fire as it can be difficult to locate the spot with details of just the zone. With an Addressable type system, the location can be pinpointed for enabling immediate attention.
Every device in the Addressable fire alarm network will have a unique ID. When the alarm is raised, the control panel will be able to pinpoint the device that has raised alarm keeping its ID as reference.
