FIRE ALARM SYSTEM
A fire alarm is a unit made of several devices, which uses visual and audio signalization to warn people about a possible fire, smoke, or carbon monoxide occurrence in the area of coverage.
Fire alarms are usually set in fire alarm systems to provide zonal coverage for residences and commercial buildings.
The warning signal is either a loud siren/bell or a flashing light, or it can include both. Some fire alarm systems use additional warnings, such as sending a voice message or making a phone call.
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| flashing light |
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| loud siren |
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| Bell Type 24V DC |
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| Bell Type 220V AC |
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| sending a voice message |
Depending on the functionality and the integrated components, there are several classifications of fire alarm systems.
Automatic fire alarm systems are activated through fire detectors, such as smoke or heat sensors. Manual fire alarms are activated with manual call points or pull stations. There is no reason for a fire alarm system to exclude one or the other. Both can be included in the same system.
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| manual call points |
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| Pull stations |
Conventional fire alarms work as one unit and cannot pinpoint the exact area of activation unless inspected.
A Conventional Fire Alarm System normally consists of a control panel linked to a number of lines of fire detectors and manual call points, normally called detection zones, and a number of sounder or alarm circuits.
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Control Panel
The Control Panel drives the detection zones and sounder circuits,
provides LED indications of fire, fault or normal conditions and
contains switches to allow the sounders to be activated or silenced and
the detectors to reset following and alarm. The control panel is powered
from the mains (230VAC) and will contain back-up batteries to allow the
system to function for a minimum of 24 hours, dependent on the
application, in case of main failure.
Fire Detection and Alarm Zones
- Most conventional fire alarm panels have several detection zones comprising a mixture of automatic fire detectors and manual call points.
- In order to limit the effect of faults, and to limit the search area in the case for fire, the size of fire detection zone is limited to 2000 m², with a maximum travel distance within the zone to locate a fire of 60m.
- In addition, zones should not cover more than one storey, unless the total floor area of the building is less than 300m².
- As a result unless the site is very small, the system will comprise several detection zones.
Addressable fire alarms have a specially dedicated address for each fire alarm detector that is connected to the control panel, for easier identification of the source of the danger.
- To determine the most suitable fire alarm system, start by identifying your specific needs.
- Think about how many detectors need to install in your building. Go for a fire alarm system that is compatible with your current security system.
- Shop around for equipment that fits within your budget without sacrificing quality.
- Work closely with the vendor of the fire alarm system to correctly
install the fire alarm system and properly integrate it with your
existing monitoring and security system.
- Give preference to systems that include additional features—such as a hush button, voice alarm and backup battery—to improved usability.
- If you’re unsure about whether a specific feature of a fire alarm system serves your specific, contact the support of one or more vendors.
Key Components of a Fire Alarm System
- Fire alarm panel
- Detectors and bases
- Call points
- Sounders and flashers
- Power supply accessories (fire alarm batteries)
Wireless fire alarm systems do not use any wiring between the fire control panel and the other devices. Most fire alarms used today are wireless. The most advanced use smart technology, and can be integrated into a smart home with various software applications.
The fire alarm panel (or the fire alarm control panel - FACP) is the base or the control hub of the system. It controls the settings of the other components and communicates the information through the system. A new requirement for the 2019 edition of NFPA 72 also specifies the maximum and minimum mounting heights for control equipment as 6 ft (1.8m) and 15 in. (375 mm), respectively.
Fire detectors can be heat, smoke or carbon monoxide sensors. They are placed around the building to trace the presence of such emergencies. Some advanced sensors can even detect radiation. Call points or pulls belong to manually-controlled fire alarm systems. Most residential properties don’t use them, but many business facilities still do. Sounders emit a loud siren signal. Flashers are for visual warnings and emit intermittent or rotating flashes (typically red or white).
A fire alarm system can use the main electricity power supply as a
primary source. In case of power failure, the system switches to the
secondary power supply, consisting of a fire alarm battery. Conventional
fire alarms need frequent battery replacements. Some of them require basic technical skills, such as using a screwdriver to mount their parts on a wall or ceiling.
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