Everything you wish you knew before buying a photoelectric smoke alarm

 

In the first of this multi-part series we will review Australian Standard 3786:2014 and take a look at what it means for smoke alarm conformity in Australia.

The full name of the standard which encompasses smoke alarm conformity in Australia is ‘Australian Standard 3786:2014 Smoke alarms using scattered light, transmitted light or ionization’. Standards are documents that set out specifications, procedures and guidelines that aim to ensure products are safe, consistent, and reliable. When a standard such as AS 3786:2014 is referenced by state or national legislation, then it becomes mandatory in the eyes of the law.

The Australian Standard document is broken down into several key components – the two of interest that we will be reviewing throughout this multi-part series are the ‘tests’ and ‘general requirements’ for smoke alarms.

Section 4.17 of the Australian Standard states that; ‘The smoke alarm shall be so designed that a sphere of diameter larger than 1.3 ±0.05 mm cannot pass into the sensor chamber(s)’.  This requirement is intended to restrict the access of foreign bodies such as insects into the sensitive parts of the smoke alarm (to prevent nuisance alarms). It is known that this requirement is not sufficient to prevent the access of all insects; however, it is considered that extreme restrictions on the size of the access holes may introduce the danger of clogging by dust, etc.

How does this requirement translate into the design and manufacture of your smoke alarm? The image below shows the compliant internal component from our Premier Range wireless interconnected photoelectric smoke alarm. The stainless-steel mesh surrounds the sensitive photoelectric chamber within the alarm and contains thousands of tiny holes, each perfectly engineered, no larger than 1.3mm in diameter. The tiny holes prevent most insects from accessing the internal chamber whilst still allowing air (and smoke) to pass through. 

Mesh screen surrounding the photoelectric smoke alarm internal sensor chamber

As per Australian Standard 3786:2014 - holes must be no larger than 1.3mm diameter

In addition to this internal mesh screen around the perimeter of the photoelectric chamber, the Premier Range wireless interconnected photoelectric smoke alarm also has an outer grill which forms part of the external housing of the smoke alarm. As you can see in the images below, the external grill also prevents larger foreign bodies from entering the alarm itself. Foreign bodies (i.e., insects) are a common cause of false / nuisance alarms because they can enter the sensitive internal components and disrupt the photoelectric light beam.

Design feature of this smoke alarm incorporates a grill into the external housing

This exterior grill prevents larger foreign bodies from entering the smoke alarm

We hope you have enjoyed the first of our multi-part series looking at Australian Standard 3786:2014 and how it translates to the design of your smoke alarm. Whilst many smoke alarm retailers might profess to be aware of the standard, very few can claim to have read it from cover to cover or have a genuine understanding of what it means.

Photoelectric Smoke Alarms Australia – Australia’s trusted online smoke alarm store

www.photoelectricsmokealarms.com.au