The value of the system lies less in the number of detectors than in getting the cause-and-effect right. Which doors release, which dampers close, where the lifts go and how suppression systems are triggered all have to be defined at design stage. We prepare the device layout, the wiring topology and the cause-and-effect matrix together, and test every device individually during commissioning.
ATypes and components
Conventional systems
Detectors are wired to the panel in zones; the panel shows which zone is in alarm but not which detector. An economical choice for small, simple buildings.
Addressable systems
Every device has its own address and the panel shows exactly where an alarm or fault is. Loop wiring with short-circuit isolators means a cable fault affects only a small part of the system; it is the standard choice for medium and large buildings.
Optical smoke and heat detectors
Optical smoke detectors pick up smouldering fires early and are the default for most indoor areas. Heat detectors, working on fixed temperature or rate of rise, are used where smoke detectors would cause false alarms, such as kitchens, car parks and dusty areas.
Multi-sensor detectors
Combine smoke, heat and, in some models, carbon monoxide readings. They reduce false alarms while keeping sensitivity to real fires.
Beam and aspirating detectors
Beam detectors cover large, high-ceilinged spaces such as factories, warehouses and atria. Aspirating systems (ASD) continuously draw air samples through a pipe network, giving very early warning in data centres and clean rooms.
Flame and linear heat detection
IR or UV/IR flame detectors see flames directly on flammable liquid and gas risks. Linear heat cable provides continuous detection along cable trays, conveyors, tunnels and car parks.
Call points, sounders and beacons
Manual call points along escape routes let people raise the alarm before the system does. Sounders and visual alarm devices are positioned so they can be heard and seen throughout the building; larger buildings use voice alarm systems.
Control panel and I/O modules
The panel processes incoming signals and runs the programmed cause-and-effect. Input/output modules link it to ventilation, lifts, door holders, pressurisation fans and extinguishing panels.
BHow it works
- Detectors continuously monitor for smoke, heat or flame, and anyone can raise the alarm at a manual call point.
- The control panel processes the signal, shows the alarm location and starts the cause-and-effect sequence.
- Sounders and beacons operate, and where a voice alarm is installed evacuation messages are broadcast.
- Ventilation stops, fire dampers close, lifts return to the designated floor and door holders release.
- The alarm is passed to the security desk, a remote monitoring centre or the building management system.
CAdvantages
- Early detection buys time for evacuation
- Addressable systems pinpoint the alarm location
- Automatic interfaces with suppression and ventilation
- Continuous monitoring of faults and disablements
- Compliance with regulations and insurer requirements
DApplications
- Residential buildings
- Office buildings and shopping centres
- Factories and warehouses
- Hotels and hospitals
- Schools and public buildings
- Data centres
EFrequently asked questions
Should we choose a conventional or an addressable fire alarm system?
For small buildings that can be managed with a few zones, a conventional system may be enough. As detector numbers, floor count or cause-and-effect complexity grow, an addressable system speeds up response and makes maintenance easier. Loop wiring also needs less cable, so on most projects the cost difference ends up in favour of addressable.
Why does our fire alarm keep giving false alarms?
The most common causes are the wrong detector type (a smoke detector in a kitchen, for instance), construction dust, steam, dirty detectors and devices disturbed during refurbishment. Repeated false alarms teach people to ignore real ones, so they must be fixed at the root. We go through the panel event log to identify the problem devices and conditions.
How often should a fire detection system be tested?
The user should test the system weekly from a call point, and a competent company should carry out periodic servicing. Common practice is an inspection every three or six months and, at least once a year, an individual test of every detector, call point and sounder. Battery capacity, the fault log and cause-and-effect outputs are part of the same service.