A Guide to Fire Alarm System Types
The main fire alarm systems types are conventional, addressable, and wireless. A fire alarm system has a number of devices working together to detect and warn people through visual and audio appliances when smoke, fire, carbon monoxide or other emergencies are present.
The choice of fire alarm system depends on the building structure, the purpose and use of the building and current legislation. All existing buildings except domestic premises are subject to The Regulatory Reform (Fire Safety) Order 2005 and the Responsible Person, as defined in the order, has to conduct, and keep updated, a fire risk assessment (FRA). Based on the findings of this assessment, they must ensure that adequate and appropriate fire safety measures, including fire detectors and alarms, are in place to minimise the risk of injury or loss of life in the event of a fire.
Guidance on the design, installation, and maintenance of fire alarm systems can be obtained from BS5839 Pt1:2017.
All fire alarm systems essentially operate on the same principle. If a detector detects smoke, heat, carbon monoxide or someone operates a break glass unit (manual call point), then alarm sounders operate to warn others in the building that there may be a fire and to evacuate. It may also incorporate remote signalling equipment which would alert the fire service via a central station.
Fire alarm systems can be broadly broken down into “conventional” fire alarm systems and analogue addressable “intelligent” systems, each type best suited to different kinds of premises. They may be also divided into categories depending on whether their aim is to protect life or property, or whether they are manual or automatic.
Conventional Fire Alarm System
Conventional fire alarm systems have been widely used in smaller properties such as shops and restaurants for many years. They work by dividing the building into a number of detection zones where detectors and call points within each zone are hardwired on dedicated circuits to the fire alarm control panel. A Zone is a circuit and typically one would wire a circuit per floor or fire compartment. The Fire Alarm Control Panel has a number of Zone Lamps. The reason for having Zones is to indicate the zone from which the fire alarm has originated, but the area then has to be manually searched to pinpoint the individual device. This is important for the Fire and Rescue Service and of course for the building management. The accuracy of knowing where a fire has started is controlled by the number of Zones a Control Panel has and the number of circuits that have been wired within the building.
The detection principle of an addressable system is similar to a conventional system except that the Control Panel can determine exactly which detector or call point has initiated the alarm. The Control Panel is programmed to display the information required when that particular detector is operated.
Analogue Addressable Fire Alarm Systems
Analogue addressable fire alarm systems are often known as ‘intelligent’ fire alarm systems which give details on individual detectors, whereas conventional systems only give information about specific circuits or zones. They are designed for large commercial premises and more complex networked systems, since they are much more expensive and more complicated than conventional systems, having increased flexibility, intelligence, speed of identification, and scope of control.
With a true ‘intelligent’ analogue system, each detector effectively incorporates its own computer which evaluates the environment around it and communicates a status report, and exact location, from each device to the Control Panel whether there is smoke, heat, a fault or the detector head needs cleaning.
Wireless Fire Alarm Systems
Wireless fire alarm systems are an effective alternative to traditional wired fire alarm systems when wired installations are not suitable (such as in grade-listed properties where wiring may be prohibited). They are more expensive to buy but more flexible, cheaper, and much quicker to install.
Wireless, or battery-powered radio-linked, fire alarm systems provide just as much protection as conventional wired systems. They utilise secure, licence-free radio communications to interconnect the sensors and devices (smoke detectors, call-points, etc.) with the controllers. It is a simple concept, which provides many unique benefits and is a full analogue addressable fire detection system without the need for a cable.
Wireless systems need to comply with BS EN 54-25.
Please note that this article provides basic easy-to-understand guidance of fire safety provisions and the key fire safety information required to comply with legislation. Our articles are reviewed regularly. However, any changes made to standards or legislation following the review date will not have been considered. We aim to assist you to understand the fire-related terms within your Fire Risk Assessment. It does not provide detailed technical guidance on all fire safety provisions, and you might require further advice or need to consult the full standards and legislation.
Fire Risk Consultancy Services have the knowledge and experience to assist your business to comply with all legal requirements surrounding fire safety including legislation. Be sure to read our accompanying guides: British Standards Relating to Fire Alarms, Categories of Fire Alarm Systems, Different Types of Fire Detector Head, Fire Alarms in the Home, AND Fire Extinguishers, Emergency Lighting, Fire Door Regulations, Fire Safety Signs, also published on this site.
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