Safety First: The Whats and Hows of Fire Alarm Sounders

Whether it’s at home, on the job, or just taking your seat in a restaurant, we depend on a surprisingly intricate combination of warning systems installed at those locations to inform us whenever a dangerous situation arises. And in no case is that danger more prevalent than the moment a fire breaks out.

Higher quality construction materials, better heat and smoke detection, improved suppression and sprinkler systems, and just plain public education are critical for minimizing the damages incurred during a fire. At the heart of the warning system, however, is the notification process: the audible and visual notification that a condition exists that warrants vacating the premises immediately.

The signalling equipment used in the notification process are the primary tools relied on for ensuring personal safety, so let’s take a look at them and the role they’re expected to play under the worst of circumstances.

Alarms and sounders

close-up of fire alarm sounder

Make no mistake: there’s a reason that the Building Codes of Australia (BCA), along with the rules and regulations for fire safety for both commercial and residential settings are as complex as they are. Fire safety can’t be a second thought – it can only be a first priority. That’s why when it comes to selecting notification appliances, the specifications for fire alarms and fire alarm sounders don’t leave anything to speculation.

Regardless of the setting though, only IP-rated, fire-retardant notification equipment should even be considered. Depending on the intended mode of notification (either public or private), the equipment should also be capable of providing a staged level of information to first responders as to the nature of the emergency as well.

With that knowledge, it’s important to understand what the most basic types of sounders are and what kind of environments they’re best suited for.

Types of sounders

close-up of fire alarm system

All sounders inherently serve the same function, but there are three widely varied characteristics that are responsible for determining how suitable they are for any particular environment:

·   The distance the notification has to travel.

·   The environment the notification has to travel through.

·   How high or low the frequency of the notification needs to be.

Given these environmental considerations, there are three types of sounders:

Siren sounders

Siren sounders, either electronic or motor driven, provide a single, but powerful low frequency warning. They inherently lack volume control or tone modulation, but produce a sound with an effective distance of up to 500m at a maximum of 127dB(A).

With their large, simple blade/impeller design and high power draw, siren sounders also produce the most commonly recognizable of all notifications. As such, they’re ideal for locations where the signalling needs to travel long distances or would possibly need to penetrate through a series of dense barriers.

Electronic Sounders

Electronic sounders come in a variety of higher frequency variations, and are capable of producing controlled volume signals to an effective distance of up to 200m at a maximum of 125dB(A). Unlike siren sounders that can only produce a single continuous tone, electronic sounders can either be programmed to produce up to 45 different tones under a selectable range of emergency conditions, or to play MP3 file recordings directly through their onboard SD card slots.

These sounders are ideally positioned at multiple locations where ambient noise is high but where their adjustable volumes, tones, and frequencies can specify different types and stages of emergencies, as well as trigger different types of response contingencies.   

Electronic sounders with beacon

An electronic sounder with a beacon provides optimal flexibility during an emergency notification. With audible signalling up to 60m at a maximum of 117dB(A), these sounders can also be programmed to produce a range of selectable tones at different frequencies. They are combined with either 200 candela Xenon or LED 3cd beacons with varying flash and strobe rates.

Together, these combination sounders are ideal for large, compartmented locations where the levels of ambient noise would be high enough to warrant the wearing of hearing protection. Depending upon the nature of their usage, the messaging these appliances provide can be tuned and prioritized almost infinitely, and wired to operate either simultaneously or independently.

Location is everything

There are typically three alternatives for sounder mounting:

·   Wall mounting (vertically);

·   Ceiling mounting (horizontally); and,

·   Pole mounting (free standing).

It’s crucial to remember that because sounders need to satisfy a range of accessible and occupational requirements, that they have to be located in a manner that elicits immediate attention and action. A strictly audible notification alone may not be sufficient for a noisy environment.

One that’s relying entirely on visual signalling may not be inappropriate in an environment where visibility may be organically impaired, or by the emergency itself. Optimal positioning allows for sounders to project their signally over the largest possible area with the least amount of interference, and how a sounder is mounted will affect every aspect of how effective the signally actually is.  

The sounder conclusion

Close-up of fire alarm sounder

At the end of the day, it’s important to remember that sounder selection comes down to how quickly and effectively the signalling can be identified, regardless of whether it’s audible or visual.

For audible fire alarm sounders, the emphasis needs to be on devices that are both louder than the surrounding environment, and that there’s sufficient sound differentiation between them and the environment. For visual sounders, the emphasis needs to be on the intensity of the light source.

Ultimately, you always want to make sure that when you’re shopping for notification appliances that the equipment integrates within your existing fire control strategy. And that the strategy meets the fullest extent of the danger. It’s a matter of safety, and the equipment you purchase needs to be up to the job.