Optical smoke detectors work by sensing changes in the visibility of the surroundings, caused by the presence of smoke. These smoke detectors are intelligent and work by automatically “self diagnosing” the situation. They have a high tolerance range to false alarms caused by cigarette smoke, smoke from the kitchen, mosquito coils, steam, dust, etc.
Optical smoke detectors are also called photoelectric smoke detectors. They are in effect, small light sensors mounted inside a small casing. They are very light and can weigh less than 1 pound.
How do optical smoke detectors work?
The way optical/photoelectric smoke detectors work is quite simple in theory. A pulsing light emitted by a diode encased inside a compartment passes through a lens and it is outputted as a sharp beam of light. This beam of light constantly passes in front a photoelectric sensor at an angle, but does not fall on it. When smoke particles are present in large quantities in the air, the beam of light becomes scattered and consequently, some rays fall on the photoelectric sensor and triggers the alarm in the smoke detector.
Benefits of optical smoke detectors
The advantage of optical smoke detectors is they are good at detecting smoke from carbon-based heavy material like coal, fabric, and wood. These slow-burn fires typically produce a lot of soot laden smoke with large particles. But they are not as sensitive as ionization smoke detectors - Which have its pros and cons.
The upside is that there will be less risk of false alarms since they have a higher threshold of smoke tolerance. The downside is that in certain situations like for flaming fires that do not produce large smoke particles, by the time it sounds the alarm, the fire may have grown too large to be easily tackled.
Optical smoke detectors are small, cheap, and outfitted in most large fire alarm systems that are installed in commercial buildings because of their higher immunity to false alarms. Smoke detectors are often just 4 inches in diameter and under 2 inches high. Their typical operating temperature ranges from minus zero Celsius to about 60 degrees Celsius. They also typically weigh less than 500 grams.
If you’re looking for an optical smoke detector, get one with as many of these features as possible:
- Bright strobe escape lights – During an actual fire, visibility is extremely poor so these lights are useful.
- Remote controllable mute button to silence the alarm in case of false alarms.
- Lithium battery operated. Lithium batteries can last 10-15 years without changing.
- Secure battery compartments with auto lock to prevent children tampering with them.
- Alarm notification in case the batteries need changing.