While is good to protect your house, office, factory from
thieves, it is equally important to protect your valuables from fire.
There are different kinds of fires and hence different types of fire detection sensors.
These sensors come in standalone version as well as in a Networked version. If the
standalone version the detector has a built in alarm and power back up too. In the
networked version all the smoke detectors communicate to a central panel (wired or
wireless) which in turn gives out the required alarm.
Mostly whenever there is a fire, there shall be smoke. Unfortunately, depending upon the
type of material getting burnt the volume of smoke emitted can vary greatly. Some Smoke
detectors make use of this principle to detect fire. They usually have a infrared light
beam falling on a receiver (within the smoke detector). When there is smoke around the
detector, the path of light gets interrupted and this makes the sensor to send the
required signal to central command. Such sensors are most often used though they have a
problem in case the material that catches fire does not produce adequate amount of smoke.
Also, whenever there is a fire, there is rise of temperature. This rise in temperature is
again unpredictable since if the place is ventilated, by the time the temperature rises to
alarming levels it may be too late. This principle is also used by some Fire detectors.
Earlier such sensors would be triggered at a specified temperature but this was not found
practical, specially where there was a great variation in temperature due to the nature of
work or simply the weather. The recent systems now use the rate of rise of temperature
instead of a pre-fixed absolute temperature. Such systems see that if the temperature rise
is more than a certain degrees within a small time interval then they give out the
required signal. These sensors are usually used in conjunction with the smoke detectors,
if at all.
The Fires are also associated with emission of various gases like Carbon di-oxide, carbon
mono-oxide etc. So it also possible to detect fire based on these products but then the
amount of such products also varies greatly with the type of ventilation and material
getting burnt. Ionization type of fire detectors use such principle. These are also seldom
used alone.
The selection of right kind of sensor would determine if you shall be able to get the
alarm before the fire spreads too far. For normal applications, Smoke detectors are good
enough, though it is advisable to plan your fire systems in consultation with experts. |
