Limitations of Smoke Alarms

Due to how both ionisation and photoelectric smoke alarms detect smoke, anything that replicates particles of ash can trigger a false alarm.

Ionisation smoke alarms are less sensitive to dust, insect, humidity related false alarms, as these are less likely to affect the ionised air within the chamber. However, are more sensitive to cooking and cigarette smoke.

Photoelectric smoke alarms are more susceptible to dust and insects, as they can both replicate a particle of ash and reflect the light within the chamber.

Due to these limitations, newer photoelectric smoke alarms have insect meshes surrounding the detection chamber, which help prevent excessive dust and insects getting inside. However, over time, dust, and insects will eventually make their way inside an alarm and increase the risk of it sounding, so regular maintenance is required to prevent false alarms.

Humidity and Smoke Alarms

Smoke alarms are tested to withstand up to 93% humidity, but with legislation changes in QLD requiring photoelectric smoke alarms to be installed in every room in all homes, smoke alarms were being installed in environments where humidity levels were reaching 100%.

During the night, the temperature decreases, and humidity rises, eventually reaching what is known as “dew point” — when moisture levels reach 100% and begin to form condensation on cool surfaces. If trapped moisture within a smoke alarm reaches dew point, the droplets of water from inside the detection chamber, cause a false alarm, usually at 3am.

PSA has developed a technology to combat this in the Advanced sensor alarms, which are more resistant to these types of triggers