Ionisation VS Photoelectric

Ionisation and Photoelectric are the two common types of smoke alarms and work in different ways to detect smoke. Both alarms are capable of meeting Australian Standard AS3786:2015 and can be legally purchased and installed in Australia. But which is better? Which alarm is recommended by the Fire Authorities in Australia?

Ionisation alarms are quicker at sensing flaming, fast moving fires that don’t emit much visible smoke. These alarms use a small amount of radioactive material which reacts to particles emitted in a fire and sets off the alarms.

Photoelectric alarms are more effective at detecting early, smouldering fires, which is more suitable for detecting house fires as smouldering fires can be lethal. Many house fires smoulder and emit large particles for some time before reaching the blazing stage. The early warnings that photoelectric alarms can potentially provide might amount to a life-saving difference.

Smoke detector with smoke

While ionisation alarms are generally cheaper, they can also be prone to nuisance alarms from cooking and steam. They give us a false sense of security as they go off when we were cooking, resulting in 30 percent of Australians disabling their ionisation alarms, leaving them with no protection at all, according to The New Daily.

Photoelectric alarms are the best type for homes, as recommended by most fire authorities. Photoelectric smoke alarms are usually much faster at detecting smoke from smouldering synthetic material than ionisation alarms. In a typical house fire, burning material smoulders and smokes for a long time (possibly a few hours) before flaring into flames. It's crucial to detect the fire early in the smouldering phase so you can deal with the fire or escape the house; the longer the fire goes on, the more smoke can fill the home and become an inhalation and visibility hazard.

Studies have shown that photoelectric alarms typically respond to smoky fires within about three to five minutes. Ionisation alarms can take much longer – up to 20 minutes or more – by which time escape can be much more difficult.

There is also new legislation in Queensland that requires home owners to replace their alarms with photoelectric smoke alarms which comply with Australian Standards (AS) 3786-2014. It is also recommended that the smoke alarms are installed in every bedroom and hallway, and the alarms must be interconnected.

Courtesy of 7 News


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