Housing fires still claim numerous victims each year. In the meantime, smoke detection is mandatory in all federal states in the USA. Smoke detectors save lives by detecting smoke and sounding alarms. Thus, residents of apartments and houses gain valuable time to get out of the burning buildings in safety and to inform the fire department.
The prescribed smoke detectors, according to the standard and in the building codes called “smoke detectors,” are so-called optical or photoelectric smoke detectors. They work according to the scattered light method and are particularly well suited for the early detection of smoldering fires, but without triggering even with light smoke, such as cigarette smoke.
How do smoke detectors work?
The first photoelectric smoke detectors, as we know them today, were developed at the beginning of the 60s. In the optical chamber of the smoke detector are an infrared light emitting diode and a photosensitive sensor, a so-called photodiode. The infrared LED continuously emits a beam of light that is invisible to the human eye and oriented so that it does not strike the photosensitive sensor directly.
If smoke particles are now in the air and penetrate the optical chamber of the detector, the emitted infrared light beam of the LED is scattered by the smoke particles and thus deflected. If enough scattered infrared light falls on the photosensitive photodiode, the smoke detector sounds an alarm.
Photoelectric smoke detector – what happens with a false alarm?
However, compared to other types of smoke detectors, such as ionization smoke detectors (banned in Germany, however, because of their radioactivity for households), photoelectric smoke detectors can cause false alarms under certain circumstances due to their design.
- Cooking vapors in the kitchen or steam in the bathroom can penetrate the optical chamber of the photoelectric smoke detector and trigger a deceptive alarm. Therefore kitchens and bathrooms are excluded from the obligation to smoke detectors. For kitchens where something burns relatively quickly, smoke detectors with mute are recommended.
- Insects penetrating the interior of the smoke detector can also cause a false alarm if they scatter the light from the infrared LED and hit it on the photosensitive sensor. For this reason, high-quality photoelectric smoke detectors are equipped with a very fine mesh insect screen.
- Construction work such as sawing, grinding, welding and soldering processes contaminate the air, whose particles are misinterpreted by the sensors of the optical smoke detector. This often also leads to a deceptive alarm. Therefore, when renovating or remodeling the home or house, the smoke detectors must be removed and kept away from dust. The reinstallation after the renovation but do not forget! Therefore, no smoke detectors need to be installed in workshops and hobby rooms with high levels of dust.
Pay attention to “Q” like quality
Anyone who pays attention to certified smoke detectors with the quality mark “Q” not only benefits from excellent quality but also does not have to worry about replacing the battery. Because such smoke detectors are characterized not only by increased protection against the ingress of foreign bodies such as insects and dust – they also have a factory-installed 10-year battery. Thanks to high-quality electronics and improved stability of the device components, Q-smoke detectors are less prone to false alarms throughout ten years. Quality that pays off.