In cases where we want to place a wide area such as a salon of a factory or museum hall, etc., this type of detectors are used to cover
the fire alarm system and the installation of typical detectors is difficult or non-economic.
This type of detector has a transmitter (TX) that sends a rays to the receiver (RX). These two parts are installed on both sides of the hall,
and if a factor such as smoke occurs between the two elements and interrupts the radiation, it will cause danger. In some of these detectors,
the transmitter and receiver are located on one side and mounted on the side of a reflex reflector. These detectors can cover a space of 15
meters in length and 10 to 100 meters in length, with an installation height of between 2.7 meters and 25 meters. Their operating voltage is
24 volts DC and the current consumption is about 50 mA and at 70 mA. The higher the distance between the receiver and transmitter,
the higher the flow of consumption.
The principles of this Beam recognition are to compensate for the inadequacy of spot detectors. This kind of detector works in the form
of a projector and is divided into two types, separated by the first type of transmitter and receiver, and the second type of transmitter
and receiver are mounted on a frame and a refractor is used to return the optical radius. . The usual type is the second type.
Linear distance between transmitter, receiver and reflector
Coverable surface protected by the detector. At this level, the sensitivity of the detector is acceptable.
(Mirror) equipment that returns the light signal to reach the receiver.
Smoke detection capability at various protective levels. This sensitivity is most sensitive to the concentration, volume and magnitude
of smoke particles.
(Layering) of smoke layers, which depends on the degree of fire. Hot fires have large layers and hot fires in smaller layers.
The sensitivity of a smoke detector is measured in a transparent glass box or glass box.
This is part of the test standard and is used to test the application of this detector in poor weather conditions or to have clear barriers such as
glass in front of it.
The detector consists of a receiver and transmitter and a reflector. The transmitter sends an optical spectrum in the row of
the infrared spectrum symmetrically toward the reflector. Reflector light reflects (reflected), and the receiver of this light is taken,
the percentage of diffusion,
the percentage of light absorption, and the condition of the environment are examined. At the start of the test, the detector first places
the absorbed amount after setting the mirror and detector as a basis. If the percentage of light absorbed in the next steps is less
(by adjusting, for example, less than 60%), this stage is considered as an obstacle and sends alarms.
Settings: In the light settings, the transmitter is projected to be 100% and the percentage of light taken by the receiver (for example, 60%),
which is based on the Threshold, is the basis. 40% of the lost light due to asymmetry in the transmitter, low percentage of ambient dust,
no reflection by reflection, and a small percentage of reflection by the receiver, as well as changing the nature of light at this distance
due to environmental factors. It is noteworthy that the entire optical spectrum of the transmitter may not be homogeneous and not be
within a certain wavelength. Therefore, it is possible to change the state or not to convert it to the voltage-current in the receiver.
This problem is better at higher intervals. Given the fact that in this type of detector, the distance between the light spectrum is twice
the distance between the receiver and the reflector, the protective radius is calculated only from the mirror to the transmitter and receiver.
When working, the presence of gas particles, smoke, rigid bodies and fluids does not allow the radiator to reach the receiver and the alarms
appear there. In order to reduce the possibility of error, this state must be permanently detected in the detector for about 5 seconds,
so that the alarms appear. If the percentage of light reached the receiver is 100%, its sensitivity can be set between 30% and 90%.
Some detectors suffer from sensitivity of 30, 50 and 70. In this type of detector, low-light, radial, volumetric, and qualitative changes do not
trigger alarms in the receiver. In the calculation of sensitivity, the light ratio received to the damaged light is considered.
The standard (BS 5445.Part 5), (UL268) and (NFPA 72) defines the principles in this detector. This detector, such as spot optical detectors,
is sensitive to smoke and detects black smoke (optical radius absorber) faster.
Automatic Gain Control (AGN) Factor Adjustment
Some environmental factors such as humidity and dust create gradual forms in this type of detector. For example, the presence of permanent
dust in its environment or its encounter on a mirror or detector, and normally creates rand alarms after a while.
The introduction of the AGN system in the detector causes the gain or low sensitivity to be changed.
In this system, which uses an electronic microprocessor (microprocessor) with a special software, the dust and moisture content is
compensated for the detector, which is the percentage of the measured waste and is compensated by software. This percentage is limited
and in accordance with the Threshold, so the AGC will compensate for the decrease in detector gain. This issue continues until the detector
or mirror needs to be cleaned or replaced.
The existence of a peripheral device can convert this conventional detector to a addressable detector for the Beam detector. It can also be
used as a command system
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