Back in 2014, we wrote a blog about the difference between ionization and photoelectric smoke alarms, and the various reasons why photoelectric alarms are preferred by states and local fire authorities.
While we thought the debate had been settled, a recent 3-year-study conducted by FIre and Rescue NSW appears to have thrown this back into the spotlight.The study involved setting alight a dummy (but life-size) two-bedroom apartment 81 times. They varied the type of fire, the position of the alarms in the apartment, and importantly, the type of smoke alarm (either photoelectric or ionization).
The study confirmed the previously assumed benefits of each type of smoke alarm.
The study found that during a smouldering fire, photoelectric alarms sounded on average 30-seconds faster than ionization alarms. However, during flaming tests, ionization alarms were faster than photoelectric alarms.
For those not averse in fire types, a smouldering fire is a slow burning fire. This creates a lot of smoke and can lead to severe vision impairment or breathing difficulties as occupants attempt to escape. Comparatively, flaming fires typically have less smoke however burn faster. While both fires can occur in the home, the vast majority of home fires are smouldering fires. As mentioned above, photoelectric alarms respond more effectively in smouldering fires than ionization alarms, thereby tilting the debate in favour of photoelectric alarms.
A second important finding was the frequency of false alarms that occurred during the study. Ionizations alarms produced many false alarms. Increased false alarms are one of the main criticisms of ionization alarms as false alarms are the key cause of occupants removing the battery in their smoke alarm.
Ultimately, there are benefits and weaknesses of each smoke alarm type, which led the Assistant Commission of Fire and Rescue NSW to say the following – “It’s actually the number, the location and the interconnection of smoke alarms that gives you the best possible chance.”
At Detector Inspector, we are realistic about our attitude towards fire safety. Our experience has taught us the importance of having a reliable (less false alarms) smoke alarm that will provide improved protection for the most common risk event (smouldering fire). For this reason, we continue to follow current recommendations and install photoelectric alarms in all the properties we service.