If we want to prevent dust, we must first know the emission of these fumes, and then monitor the source of the fumes. At this time, the photoelectric sensor provides a great help for the monitoring of smoke and dust, and can effectively detect the turbidity. Dust turbidity in flue is measured by the change of light in the process of transmission in flue. If the flue turbidity increases, the light emitted by the light source is absorbed and refracted by the dust particles, and the light arriving on the sensor decreases. Therefore, the intensity of the output signal of the photoelectric sensor can reflect the change of the flue turbidity.
Clean Photoelectric Sensor
In order to detect the turbidity of submicron particles which are most harmful to human body and avoid the influence of water vapor and carbon dioxide on the attenuation of light source, visible light is selected as the light source. Generally, photoelectric sensors choose phototubes with spectral response ranging from 400 mm to 600 mm to obtain the corresponding electrical signals with the change of turbidity. In order to improve the detection sensitivity, an operational amplifier with high gain, high input impedance, low zero drift and high CMRR is adopted to amplify the signal. Calibration calibration is used to adjust zero and full calibration to ensure the accuracy of the test. The monitor is used to display the instantaneous value of turbidity. The alarm current is composed of a multivibrator, when the turbidity signal of the operational amplifier exceeds the specified value. The multivibrator works. The output signal is amplified to push the loudspeaker to send out an alarm signal.
Usually photoelectric sensors can be used to detect a variety of non-electric quantities. The optical devices affirmed by the different ways of light flux acting on photoelectric elements are various. According to their output properties, they can be divided into two categories: analogue photoelectric sensor detection system and switching photoelectric sensor detection system.
Cautions in the Use of Photoelectric Sensors
- The front end of the photoelectric sensor in use must be parallel to the surface of the detected workpiece or object, so that the conversion efficiency of the photoelectric sensor is the highest.
- When installing and welding, the minimum distance between the pin root of the photoelectric sensor and the pad should not be less than 5 mm, otherwise the core of the tube will be damaged easily during welding. Or cause the change of core performance. Welding time should be less than 4 seconds.
- The minimum detectable width of the counter-radiation photoelectric sensor is 80% of the width of the photoelectric switch lens.
- When using inductive load (e.g. lamp, motor, etc.), its transient impulse current is large, which may deteriorate or damage the photoelectric sensor of AC second line. In this case, please transfer the load through AC relay.
- Lens of infrared photoelectric sensors can be wiped with mirror paper, and diluted solvents and other chemicals are forbidden to avoid permanent damage to plastic mirrors.
- According to the actual requirements of users, under some harsh conditions, such as more dust, the sensitivity of the photoelectric sensor increased by 50% in order to meet the requirement of prolonging the maintenance period of the photoelectric sensor in long-term use.
- The photoelectric sensor must be installed in the place where there is no direct illumination of strong light, because the infrared light in the strong light will affect the normal operation of the receiving tube.