The working principle of the dust detector is mainly the principle of light absorption, light scattering, β-ray and AC static induction.
Principle of light absorption:
The air pump draws a certain volume of dusty air, and the dust is retained on the filter paper. The beam-transparent filter paper is applied to the silicon photocell, and the change in the illumination received by the silicon photocell causes a change in the output current intensity of the silicon photocell. Within a certain range, the amount of dust retained by the filter paper and the output current of the silicon photocell are linear and wide, and are displayed by the calculation program set in the detector to be converted into dust concentration.
Principle of beta radiation:
When the β-ray generated by the radiation source in the detector passes through the dust particles, the dust particles absorb the β-ray, and the dust concentration is calculated based on the linear relationship between the amount of the dust-absorbing β-ray and the dust mass.
Light scattering principle:
The dust meter sucks the aerosol to be tested into the detection chamber through the gas pump, and the aerosol to be tested is divided into two parts at the branch, and a part is filtered through a high-efficiency filter and filtered into clean air to protect the sensor chamber as a sheath gas. The device is not contaminated by the gas to be tested. Another part of the aerosol enters the sensor chamber directly as a sample to be tested. In the sensor room, the main components are laser diodes, lens groups and photodetectors. In the detection, the laser light emitted by the laser diode is first formed into a thin-layer light source through the lens group. When a thin layer of light is irradiated through the aerosol to be tested flowing through the sensor chamber, scattering occurs, and the scattered light intensity of the light is detected by the photodetector. The photodetector produces an electrical signal after exposure to light, proportional to the mass concentration of the aerosol. It is then multiplied by a voltage calibration factor that is obtained by measuring a specific concentration of aerosol.
Electrostatic AC induction principle
Signals are generated by dynamic charge sensing between the probe and the probe as it flows through the probe. The AC electrostatic technique monitors the standard deviation of the charge signal to determine the amount of disturbance of the AC signal and determines the amount of dust emissions by the amount of instantaneous disturbance.