Something in the air? Dead air space and the risk it creates in a fire

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Identifying the Dead Air spaces for smoke detection in your properties

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In Ancient China, soldiers used to use smoke signals along the Great Wall as a way of communicating with one another to pass on information and warnings of danger. This method of communication has clearly been replaced with the evolution of transportation and communication, but one facet that remains from this form of long-distance communication is that smoke is an indication of danger. 

Where there is smoke, there is fire and with our Smoke Signal pieces, we wish to provide you with useful, interesting and insightful information on smoke alarm security. 

Smoke alarms are engineered to install on walls and ceilings and detect smoke within a property: this is the basic explanation of a smoke alarm's purpose. While this is true, there are other facets outside of functionality that need to be considered for a smoke alarm to do its job properly. A smoke alarm can be perfectly functional and still be delayed in detection. This comes down to the alarm positioned in dead air spaces. But what is dead air space and why does it affect a smoke alarm's ability to detect smoke?

Dead air space is a reference to the areas in a property that air gets trapped in preventing the alarms ability to detect the smoke. In a fire, smoke travels by rolling up the surface of walls within a property. If the smoke is rolling against a surface with a sharp turning point, then the smoke will not roll through to the turning point. It will instead float within that pocket of trapped air, leaving the space after the sharp turning point of a surface unable to detect smoke as it is stuck in an air bubble.

Dead air spaces generally occur in property spaces that contain cathedral ceilings, corner junctions between the wall and the roof of a property or between exposed floor joists. Alarm placement needs to be selective within these spaces to be in a position where they can detect smoke before it crawls into dead air space.

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Other areas that should be avoided when installing smoke alarms are as follows

  • Locations of excessive air movement that may push smoke away from detectors.
    Examples: Near windows, doors, fans and air conditioners.

  • Areas that create steam that may confuse smoke alarms detection.
    Examples: Saunas.

  • Anything within 1.5 meters to a fluorescent as flickering noise may affect smoke alarms

  • In the kitchen, as this is an environment filled with steam and smoke.
    Should there be no alternative solution, then it is recommended you install a photoelectrical alarm.

Being wary of where the dead air space builds up in your properties and the recommended areas of smoke alarm installation is valuable to help you know what sections of your property build undetectable air pockets or create some level of distortion that can affect your alarm's ability to detect smoke during a fire.