Hengaode inhalable and lung inhalable particle detector laser dust analyzerPM2.5 PM10Operating principle

Item number:29516PM2.5andPM10The core operating principle of the dust detector is mainly based on the light scattering method, and some equipment also usesBTechnologies such as X-ray absorption or electrostatic induction.‌

‌working principle‌

Light scattering method is a commonly used technology for portable and online monitoring devices. The internal laser emitter of the instrument generates a stable beam of light. When the air sample is pumped in, dust particles pass through the beam area and scatter the light. Photodetectors at specific angles (such as90°）Receive scattered light signals and convert them into electrical signals. The microprocessor analyzes the strength and pulse frequency of electrical signals, combined with Mie scattering theory and preset conversion coefficients（KCalculate the mass concentration of particulate matter (such asmg/m³orμg/m³）.‌

3 This method has fast response speed, high sensitivity, and is suitable for real-time monitoring.‌

The beta ray absorption rule is considered a benchmark method with high accuracy. The instrument measures beta rays (such as carbon) through measurement-14The attenuation degree before and after the source penetrates the filter band, according to Lambert-Bill's law calculates the mass concentration of dust. This method is not affected by the chemical composition or color of particulate matter, but the equipment is complex and cannot achieve real-time response in seconds.‌

The electrostatic induction method is mainly used in industrial scenarios to calculate the concentration of dust particles by measuring the amount of charge generated in the electrostatic field. It is suitable for harsh environments such as high temperature and high humidity, but its accuracy is relatively low and it is susceptible to humidity interference.‌

‌operating procedure‌

Equipment operation usually includes the following steps:

‌Preparation before testing‌Confirm that the equipment is within the calibration validity period and use standard particles if necessary (such as0.5μmLatex balls are used to calibrate particle size and counting accuracy. When selecting sampling points, indoor testing should avoid air vents and pollution sources, and the recommended sampling height is1.2~1.5mOutdoor testing should be conducted away from buildings and roads.‌

4

‌Startup and parameter settings‌Start the device and preheat it30Minutes to ensure the stability of the laser source. Set the sampling flow rate (such as2.83 L/min）Sampling time (such as1Minutes) and particle size channels (such as0.3μmThe0.5μmThe2.5μm）.‌

‌Blank experiment and sampling‌Connect the air inlet to the "zero air generator" for operation and testing, and confirm that the zero count is ≤1grain/5minute; If it exceeds the standard, the equipment needs to be cleaned. During formal sampling, place the air inlet at the sampling point to avoid obstruction by personnel, and repeat testing at each point3Take the average value.‌

‌Data recording and processing‌Record parameters such as particle size, concentration, temperature, humidity, etc. If you need to convert the mass concentration, you can calculate it according to the formula: mass concentration=Particle number concentration×Average volume of particles×Particle density (such as default dust density)1.5 g/cm³）.‌

‌Precautions‌

The measurement results of light scattering method may be affected by the material, shape or color of particles, and need to be calibrated regularly; Excessive humidity may interfere with the accuracy of the charge induction method.‌

3 During operation, the air inlet of the equipment should be kept clean to avoid environmental factors such as wind speed3m/s）Interference detection results