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
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
- 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