A smoke detector is a device which
indicates a fire. Smoke detectors are very helpful in homes, offices, schools
and industries. The smoke detector camera is a handy device
because the harm caused by fire accidents is unbearable. Nowadays, the cost of
smoke detectors and smoke alarms is very less because their use is growing and
the manufacturing cost is declining.
Various
types of smoke detectors:- There
are five types of smoke detectors.
• Photoelectric smoke detector
• Smoke detector by ionisation
• Projected beam smoke detector
• Smoke detector aspirant
• Smoke detection video
• Photoelectric
smoke detector:- A pulsed light beam from a light emitting diode (LED) with
its connected optics is predictable through the interior of a blackened chamber
that could contain smoke to be detected. A photocell, through its optics, looks
at the beam projected next to a line perpendicular to the beam. When the smoke enters
into the chamber, the smoke particles are reflecting in a small part of the
beam of light near the photocell, which provides a voltage that is amplified
and causes an alert. The light source is observed in front of the smoke chamber
and synchronised to stop the discrepancy of the intensity of the light and
create erratic operation of the detector.
•
Smoke detector by ionisation:-
A small amount of radioactive material ionises the air inside a chamber that
releases the ambient air. It allows a little amount of calculated electric
current to flow via the ionised air. Some small products of solid particles of
combustion that enter the chamber, as an output of the fire, interfere with the
constant movement of the ions (current) and when the current lowers, the alarm
sounds.
•
Projected beam smoke detector:-
The projected beam smoke detector works according to the principle of darkening
of the light and contains a transmitter and projected beam lens, the light
receiver and the light reflector (not in all cases). The light emitter emits an
invisible beam of light that receives a recipient under normal conditions. The
receiver is calibrated to stand for the sensitivity level based on a percentage
of total dimming. When the smoke obscures the beam, an alarm signal is turned
on.
•
Aspirating smoke detector:-
An aspiration smoke detector is a sensitive light sensor or nephelometer, which
works by dynamically extracting an air sample and added contaminants through a
network of pipes to a detection chamber. It consists of the following main
components: a system of small diameter pipes, particle filter, a detection
chamber, focused light source and also a sensitive light recipient. When the
smoke enters the detection chamber via the path of the light beam, the light is
scattered or hidden by the smoke particles, which is identified by the sensor.
•
Video smoke detection:- Video
smoke detection (VSD) based on a computerised analysis of video images given by
standard video cameras (CCTV). A video smoke detection system consists of the
following parts: more than one video cameras, computer and software to examine
the video signal. The computer uses specific software to recognise the
individual movement and smoke pattern. This unique signal identifies activated
an alarm.
Smoke alarms also vary in the way they
are available. In the market various wireless
smoke detectors are available, but battery-powered smoke alarms are
accessible due to t low cost.
