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What is the principle of PM2.5 detection instrument?

Update: 2019-12-16 17:05 Source: LUFTMY Reading: ↻ News

PM2.5 dust sensor (dust detector) is a set of aerodynamics, digital signal processing, photoelectric integration of high-tech products, mainly used in detection of atmospheric dust mass concentration (PM), suitable for indoor air monitoring, urban grid detection of the monitoring, mobile monitoring, and other fields and occasions, is the core of the atmospheric quality detection system module.

PM2.5 monitor
PM2.5 monitor

Currently, the sensors used to measure PM2.5 are infrared and laser, which can be divided into turbidity method and particle count (laser cutting) method.

Infrared method and turbidity method:

Due to insufficient light intensity, the infrared can only be measured by turbidity method. The so-called turbidity method means that one side emits light and the other side receives it. The more cloudy the air is, the more energy the light loses, so as to determine the current turbidity of the air.

The infrared principle method can also accurately measure PM2.5, but the emission and receiving part of the light will directly lead to inaccurate measurement once covered by electrostatic dust adsorption.

HPD05 Infrared dust sensor
HPD05 Infrared dust sensor

Infrared light scattering dust sensor HPD05 sensor with an infrared light-emitting diode and a high sensitivity photoelectric receiving sensors, infrared leds emit light reflected light can be created in case of dust, photoelectric sensor by measuring the intensity of the reflected light to measure the concentration of dust in the air, sensor output PWM signals directly, the concentration of the current numerical PWM width.The HPD05 air testing instrument has the advantages of stable testing ability and high production efficiency. HPD05 has the characteristics of small volume, high precision, low power consumption, short response time and stable operation under high dust concentration. This infrared high-precision dust sensor can be applied in PM2.5 detection instruments.

Laser method and particle counting method:

Many related papers, is the laser scattering method, and is not a direct measurement of turbidity, this kind of the common characteristic of the sensor is inseparable from the fan (or pump suction), because this method without air flow is measured less than suspended particulate matter in the air, and through the mathematical model can be roughly calculated through the example of the gas sensor size directly, air flow, etc., through complex mathematical algorithm, finally get the real PM2.5 numerical compare, this kind of sensor is the laser scattering, immune to electrostatic adsorption of dust, of course, if is blocked with dust sensor, nature also can't be detectable.

The disadvantage is that the life of the laser is short, if the continuous operation is basically more than a year of life, this is still the factory optimization algorithm can achieve the life, but in the vast majority of occasions has been enough, and if the discontinuous operation, the life of the laser can be longer.

LD11 Laser dust sensor
LD11 Laser dust sensor

The laser dust particle sensor module LD11 can continuously collect and calculate the number of suspended particles with different particle sizes in the air per unit volume, that is, the particle concentration distribution, and then convert it into mass concentration, and output it in the form of a universal digital interface. Laser dust particle sensor LD11 has a small volume of high precision, strong anti-interference ability, low power long life, zero error alarm rate response time is short features, such as the high sensitivity of fine particulate matter sensors can be embedded in a variety of related to the concentration of suspended particles in the air, such as PM2.5 testing instrument instrument or environment to improve the equipment, to provide timely and accurate concentration data.

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