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ADVANTAGES OF UV / IR FLAME
INFORMERS
Fire flame informers (FI) are optimal
sensors that respond to the appearance of
open fire almost immediately after its
emergence. It is possible because the
operation of FI is based on the registration
of electromagnetic radiation of the flame.
Principle of
operation
It is well known that the flame of flammable
gases, vapors and liquids is accompanied
with electromagnetic radiation, which has
characteristic features in various spectrum
ranges and significantly differs from the
spectra of the heated bodies and the
sunlight. Since the electromagnetic
radiation propagates with immense velocity,
the reaction time of the flame informers is
defined by only time necessary for the
radiation reception, extraction of the
informative signal and its treatment, which
makes up for only few seconds. High
sensitivity and low noise level of modern
electromagnetic detectors in different parts
of the spectrum: ultraviolet (UV), visible,
near and middle infrared (IR) - allows to
register and extract the flame irradiation
at the large distance – 75 meters and more.
Also such flame feature as its low-frequency
modulation (2..20 Hz) is used. Modern
elemental base of electronics allows for
enhancement of modulated signals and
execution of its preliminary treatment.
Microcontrollers give an opportunity to use
special algorithms of signal treatment which
lets to significantly diminish the
possibility of false launches because of the
influence of various noises.
Specifics of use
Irradiation of heated bodies and sunlight
can be received by electromagnetic detectors
of FI. In order to avoid the effect of such
‘parasite’ signals on the decision of alert
signal, the most advanced, noise-stable
flame informers are made as many-channeled
(for example, two IR-channels) or combined (IR
and UV channels).
Selectivity
The comparison of the signals in two
spectral ranges allows for the certain
identification of the fire. For example,
double-channeled IR informer may have two
electromagnetic detectors with optic
filters, reacting at the radiation with the
wavelengths of 4.4 micrometers (work
channel) and 4 micrometers (insurance
channel). When a heated body or the sunlight
affects the FI, the signal through the work
channel is always lower than through the
insurance one. When there is the flame
irradiation, the signal of the work detector
is always higher than of the insurance one.
The combined informer employs the
characteristic feature of the flame which is
the broad spectral range of the radiation:
from the severe UV (spectral range with no
sunlight and heated bodies irradiation) to
the medium and far IR range. The UV channel
in the FI can react only at the radiation of
the open fire, welding or special lamps. Two
last sources or the radiation virtually do
not have the IR irradiation in the area of
4..5 microns. From the other hand, the
heated bodies and the sunlight do not have
features in the severe UV area. Thus, the
simultaneous appearance of the signal in the
UV and IR channels signifies the flame
presence around the FI.
The comparison with
the other informers
Other types of the fire informers – smoke,
heat, gas ones – react at the fire
components that need pretty much time to
travel to the sensor and initiate its
launch. Also, the effect of various external
factors (wind, smoke diffusion, air draught,
sensor cooling or the presence of many
people exhaling carbon dioxide)
significantly limits the area under control
of these informers or increases the
probability of false launches. So under the
conditions of the most possible appearance
of the open fire (flammable vapors, gases
and liquids), fire informers is the optimal
choice for the effective measures of
firefighting at the early stages of the
flame appearance and proliferation.
There are also single-channeled ultraviolet
and infrared informers. They are cheaper but
their use is appropriate only in the simple
situation – if there are no noise sources
(for example, heated machines or ultraviolet
irradiation sources) or if the possibility
of the wrong decision after false launch of
the FI is decreased by other means (for
example, the additional control of an
operator).
The choice of the fire flame informers has
to be made taking to the account the
specifics of the irradiation sources,
located in the area of the informers’
control.
- Test
Flashlight ITES
It is intended to check the flame informers
IPES, is manufactured as the explosion-proof
version 1 ExdIICU and has a switch to select
the period of blinking which imitates the
flame.
- Fire Informer IPES
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