The working principle of the dust monitor is mainly the principle of light scattering and the principle of electrostatic AC induction.
Light scattering principle:
The dust meter sucks the aerosol to be tested into the detection chamber through the gas pump. The aerosol to be tested is divided into two parts at the branch, and one part is filtered into clean air after passing through an efficient filter, which serves as a protective sheath gas to protect the sensor chamber. The device is not contaminated by the gas to be measured. The other part of the aerosol directly enters the sensor chamber as the sample to be measured. In the sensor room, the main components are a laser diode, a lens group and a photo detector. When testing, first the laser light emitted by the laser diode passes through the lens group to form a thin layer light source. When a thin layer of light is irradiated on the aerosol to be measured flowing through the sensor chamber, it will cause scattering, and the scattered light intensity of the light is detected by a photo detector. The photo detector generates an electrical signal after being illuminated, which is proportional to the mass concentration of the aerosol. It is then multiplied by the voltage calibration coefficient, which is obtained by measuring the aerosol at a specific concentration. The test aerosol commonly used for calibration is Arizona test dust (or ISO 12103-1, A1 test dust).
Electrostatic AC induction principle
Use the dynamic charge induction between the dust particles and the probe to generate a signal. AC electrostatic technology uses the standard deviation of the charge signal to monitor the disturbance of the AC signal, and determines the amount of dust emissions based on the magnitude of the instantaneous disturbance.