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NEW! Smoke Detectors also triggered by sound
World-unique review of smoke detectors and vibrations
- Major additional costs for automatic fire alarms – Real Estate owners unaware – Alarm companies unaware – Fire dpd. unaware -
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Are smoke detectors used in your house ?
Be aware that those are constructed with errors,
the smoke detectors react both to smoke and sound !
Now we have reviewed some common fire detectors.
These are small appliances that are placed on the ceilings or on the walls and should detect if a fire starts:
Picture of a typical smoke detector
Smoke detectors are installed in all public buildings, such as schools, hospitals, authorities, companies, sports centers, etcetera, and they are often connected to an automatic fire alarm that goes directly to the SOS alarm (”Alarm Center”).
The automatic fire alarm can be set in slightly different ways, – either, the rescue service shuts out immediately after the automatic fire alarm has signaled, or there is a tolerance time of a few minutes so that one have the option of switching off the automatic alarm if there isn’t a fire somewhere,
- and then also avoid the cost that it causes having the rescue service turned out.
- Ionizing, optical, or water spraying -
A smoke detector can be constructed in several different ways:
Sometimes it is ionizing, and that means that there is a radioactive substance that sends alpha particles to two metal plates inside the smoke detector.
The smoke detector can also be optical and thus visually react to smoke/fog,
or consist of a water-sprayer that will spray water if a fire starts.
- Triggered by vibrations -
The problem with these detectors is that they not only sense smoke/heat/fire, but also react to vibrations.
And there are often loud and high sounds that cause the lenses/plates in the smoke detector to react.
Image of the internal camera/smoke collector on an optical smoke detector. The orange arrow shows the aisles where the smoke comes in and becomes visible to the cameras that are inside the smoke detector.
Many property owners/construction firms who order smoke detectors for their properties, order them in the belief that they should only detect smoke, but they are often surprised by how many automatic fire alarms are triggered, even though no smoke development has been seen.
Every false automatic fire alarm on which the emergency service turns out, costs several hundred dollars for the operation manager/property owner.
- False automatic alarms stress the fire department -
When the rescue service arrives at a property where there has been an automatic fire alarm, but where one cannot find any fire or smoke, the firefighters often become stressed and confused, because when they have to equalize the automatic alarm, they must sometimes look through the entire property after the correct alarm, because there is no fire or smoke odor to take help of to find out which automatic alarm that has dissolved.
Add to this that the property maps used by the emergency services to look for a fire alarm, may not be correct due to renovations,
and it also happens that the keys that the emergency services have, do not fit, because the locks are changed, and so on.
Our review of smoke detectors has shown that these don’t really work as intended and that this causes extra costs for businesses and property owners.
Smoke detectors do not only detect smoke, but misinterpret the information they get from vibrations of loud and high sounds and think that this is smoke.
The smoke detectors can, for example, react to a vacuum cleaner that emits a high noise, sports centers where soles rub against the substrate and where athletes often shout, or in concert halls, where loud musical tones flow towards the roofs and walls.
Example of a frequency curve of sound
Our survey showed that smoke detectors are misconstructed and that no instances are aware of this – neither the suppliers of smoke detectors, the property owners, nor the fire departments.
It’s therefore no wonder that the proportion of automatic fire alarms is very high.
A tip for those who manufacture smoke detectors may be to do some sound tests before the smoke detector is delivered, and then fine-tune the smoke detector so that it only reacts as intended.
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Extra information
Finally, here are some examples of activities where smoke detectors could be triggered by sound vibrations:
Music events
A concert is a typical example of phenomena where a smoke detector could signal. The continual tones from the voices form very powerful sound vibrations, which the smoke detector could misinterpret as smoke.
Vacuuming
The high frequency bi-noise of the engine of the vacuum cleaner could cause a smoke detector to start alarming.
Sport events
Screaming, crying, and shoelace’s chirping sound to the ground could trigger a smoke detector !
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An optical smoke detector is a device that consists essentially of a few cameras, possibly a heat sensor and some warning lights that start to illuminate when the alarm is activated.
Here’s how an ionizing smoke detector works:
A. Normal mode (Left side): The battery sends power to two metal plates. The radioactive substance at the bottom sends up alpha particles that travel upwards and downwards towards the metal plates and form a closed circuit. The alarm is silent !
B. Alarm mode (Right side): The smoke particles entering the fire detector cause the alpha particles to become uncharged and stop traveling towards the metal plates. The circuit becomes open (broken) and the smoke detector will start to alarm.
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Review information:
Our investigation of smoke detectors and vibrations took place between 2008 and 2018 and we have only reviewed smoke detectors placed in public buildings (Not fire detectors for home use).
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