Determining the optimum replacement periods of optical smoke detectors and alarms

This research has led to recommendations for the replacement periods of smoke alarms in domestic and smoke detectors in commercial premises.

This research study aimed to identify the optimum replacement periods for optical smoke alarms and detectors, which are used to detect the presence of a fire and provide early warning to occupants. Ten different models of each type were tested and suitable performance limits for these were established using smoke sensitivity measurement equipment. This portable equipment was then used to test 107 commercial smoke detectors and 85 domestic smoke alarms in the field, during the period from February 2019 to January 2020.

The stakeholder group, comprising the Fire Industry Association, Scottish Fire and Rescue Service, Scottish Government, Detector Testers and BRE Global, reviewed the data that was gathered.
It was observed that the sensitivities of smoke detectors and smoke alarms, tested in service environments, were relatively consistent independent of age. However, older domestic smoke alarms demonstrated a slight increase in the sensitivity leading to an earlier alarm response. It was observed that the sensitivity of both smoke alarms and detectors increased when they were dirtier.
By analysing the sensitivity responses with the age of the devices, the research group recommended replacement periods for commercial smoke detectors, with and without drift compensation, as well as for domestic smoke alarms. Further recommendations were also made to improve practices around the use of these life safety devices.

BRE Global are exploring a similar collaborative study with heat alarms (present in domestic kitchens) to investigate whether these devices, when contaminated with dust and oil, could result in a delayed response during a fire.

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