Photoelectric smoke alarm with smoke swirling near ceiling

Photoelectric smoke alarms: a clearer picture

2 July 2019
How can you tell the different types of smoke alarms? Smoke alarms don’t seem different when they are on the ceiling. However, most states and Fire Authorities recommend the use of photoelectric alarms for compliancy in rental properties.

Photoelectric alarms detect smoke in a different way to ionisation alarms. Ionisation alarms are easily identified by a radioactive sticker on the base of alarm. The question is: Why are photelectric smoke alarms recommended over ionisation? This can be distinguished through two main points.  

1. The way they work

Photoelectric smoke alarms work through a beam of light positioned above a light sensor within its smoke chamber. When smoke begins to spread within a property, smoke particles will enter the alarm and deflect light from the beam of light positioned within the alarm, interfering with the path of the beam and triggering the smoke alarm when it detects smoke. Think of it like a laser sensor in a spy movie that will trigger if something breaks its path, but instead of going off from body detection, it reacts to smoke particle detection. This is a preferred smoke alarm type as it has a clean detection system that doesn’t require the use of radiation to detect smoke particles like an Ionization smoke alarm would.

2. How quick it works

The time it takes a photoelectric smoke alarm to detect smoke in a property has also made the photoelectric alarm popular. The smoke alarm triggers off the reflection of smoke particles from its light sensor, which is a quicker trigger for the smoke alarm and sound to alert those in a property.

Smoke alarms like ionization alarms require their smoke chamber to absorb enough smoke particles to break a radiation circuit and trigger the alarm. Photoelectric smoke alarms will trigger in the earlier stages of smoke build up as it only needs smoke particles to break the laser beam rather than fill up with enough smoke to recognize a smoke situation. 

Because of its streamlined detection functionality and its ability to detect smoke in its early stages, photoelectric smoke alarms are recommended.

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