Smoke detection systems play a critical role in protecting the occupants of buildings from fire. However, an unintended consequence of this level of protection is the incidence of unwanted or false alarms that contribute to removal or disconnection of smoke detection systems, loss of occupant amenity, financial costs, loss of productivity, complacency and unnecessary fire brigade attendance.
The incidence of false alarms can be attributed to three main factors - external factors as a result of weather, electrical fault or monitoring network fault, occupants including cooking, steam and system maintenance and system malfunction including panels, wiring and detector malfunction. Five key issues have been identified to minimise the frequency of false alarms in houses and apartment buildings. These include:
1 - Know your system.
Firstly let's identify what is currently required by the National Construction Code. Within a house or apartment, smoke alarms are required on or near the ceiling in any story- containing bedrooms, where bedrooms are separated from the living area this may require more than one, where there is more than one alarm installed per dwelling, the smoke detection system must be interconnected and be installed in apartment building common areas except where the building is sprinklered and be connected to activate a building occupant warning system.
2 - Location of detectors.
At the design and installation stage, consider the installation of detectors in appropriate locations, keeping in mind that most false alarms are a result of kitchen fumes or steam from bathrooms.
3 - Smoke reservoirs.
Baffles around kitchen areas can act as a reservoir which restricts contaminants from reaching the detector. This can be achieved by installing bulk heads. Likewise, extending the cupboard doors below the base of the cupboard is a simple measure that can assist in delaying activation of the alarm. This curtain system forms a reservoir underneath overhead cupboards and retains cooking vapours and fumes.
4 - Ducting.
An externally ducted kitchen range hood disperses cooking vapours and fumes directly outside the building which assists in reducing the frequency of false alarms. It is recommended that exhaust be ducted directly to an external wall within a false ceiling or bulk head or where possible, vertically through the roof cavity.
5 - Tips for occupants.
Keeping these tips in mind the incidence of false alarms within apartment buildings in some cases can be linked to occupants opening entry doors to expel smoke upon activation of localised smoke alarms within the apartment, activating common area building occupant warning systems and building evacuation. Many smoke detection systems in apartment buildings are connected to a fire station dispatch centre, above the minimum requirements of the NCC. A fire alarm monitoring system, for example, a smoke detection system connected to a fire station dispatch centre is not required for most apartment buildings.
For the most part, false alarms can be attributed to occupant behaviour. Understanding how your alarm functions, considering alarm location and methods to prevent false alarms can significantly reduce the incidence of false alarms and increase the safety of occupants.