Fire Detection Systems fall broadly into two groups – conventional systems or analogue addressable systems.
Conventional fire alarm systems
Conventional fire alarm systems, in their various forms have been around for any years and have changed little in that time in terms of technology although design and reliability have improved significantly. However, conventional fire alarm systems are a well proven technology protecting hundreds of thousands of properties worldwide. A conventional system is the natural choice for smaller systems. These systems are hard wired on to a circuit or zone. They signal fire or fault conditions to a control panel by changing from a high to a low impedance. The panel detects this impedance change by current monitoring and identifies the zone.
With this type of detection system, individual detectors cannot be identified.
Analogue addressable fire alarm system
Analogue addressable fire alarm systems differ from conventional systems in a number of ways and certainly add more flexibility, intelligence, speed of identification and scope of control. For this reason analogue addressable fire alarm systems are the natural choice for commercial premises and more complex system requirements.
In an analogue addressable system, detectors are wired in a loop around the building with each detector having its own unique address. The fire alarm system may contain one or more loops depending on the size of the system and design requirements. The fire control panel communicates with each detector individually and receives a status report (healthy, in alarm, in fault). As each detector has an individual address the fire control panel is able to display/ indicate the precise location of the device in question, which helps speed the location of an incident.
Addressable detectors are, in themselves, intelligent devices which are capable of reporting far more than just fire or fault conditions, for example most detectors are able to signal if contamination within the device reaches a pre set level enabling maintenance to take place prior to problems beings experienced. Addressable detectors are also able to provide pre alarm warning when smoke/heat levels reach a pre set level, enabling investigation of the fire condition to take place prior to a full evacuation alarm.