What is the difference between dust particle counter and dust detector

Dust detector and dust particle counter are both instruments to detect target particles through the principle of light scattering, but their application scenarios are quite different. What is the difference between them? Dust detector is mainly used to measure the atmospheric environment, suitable for all kinds of environmental research institutions, meteorology, public health, environmental supervision, air pollution research, the use of environmental applications in the center for Disease control and prevention, mining, metallurgy, power plants, chemical manufacturing, health supervision, environmental protection, environmental online monitoring. The particle counter is used in clean rooms, such as medicine, electronics, precision machinery, semiconductor, biological engineering and other industries, to monitor the purification effect and cleanliness of various clean levels of workbench, purification room, purification workshop, to ensure the production quality of products. What are the specific differences between a dust detector and a dust particle counter in addition to the application scenarios? Let's start with the word "aerosol," which I'm sure you've heard a lot about in recent years because of the pandemic. It's a gaseous dispersion system made up of solid or liquid particles suspended in a gaseous medium. The density of these solid or liquid particles may differ slightly or greatly from that of the gaseous medium. Aerosol particle sizes usually range from 0.01 μm to 10μm, but they range widely due to sources and formation, such as: The particle size of plant aerosols such as pollen is between 5-100μm, and the particle size of aerosols produced by wood and tobacco combustion is usually 0.01-1000μm, so the particle shapes are various, can be nearly spherical, such as liquid fog beads, can also be flake, needle and other irregular shapes. From the perspective of fluid mechanics, aerosol is essentially a multiphase fluid with gas as continuous phase and solid and liquid as dispersed phase. Clouds, fog and dust in the sky, smoke from unburned fuels in boilers and engines used in industry and transportation, solid dust from mining, quarries and stone processing and grain processing, artificial masking smoke and toxic smoke are all specific examples of aerosols. PM2.5 and PM10 are solid particles in atmospheric aerosols. So dust detector can also be called aerosol detector. Dust detector Dust detector inhales the aerosol to be measured into the detection chamber through the gas pump, and divides the aerosol to be measured into two parts at the branch. One part is filtered into clean air after passing through a high efficiency filter, which is used as a protective sheath gas to protect the components of the sensor chamber from the pollution of the gas to be measured. The other part of the aerosol, as the sample to be measured directly into the sensor chamber. In the sensor room, the main components are laser diode, lens group and photodetector. In the detection process, a laser diode emits a laser through the lens group to form a thin layer of light source. When the thin layer of light irradiates through the aerosol to be measured in the sensor chamber, the scattering intensity of light is detected by the photodetector. The electrical signal generated by the detector 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. Dust particle counter Dust particle counter principle: The particle counter through the sampling pump sampling gas. In the laser chamber, by irradiating the sampled gas with the laser, the frequency of the flash reflected from the particles represents the number of particles, and the intensity of the reflected light represents the particle size. Since the components in the laser chamber are not protected by sheath gas, the laser particle counter should be used in a clean environment to prevent damage to the laser sensor. If there are loose particle materials, dust sources, or spray sites, keep at least 12 inches away from the inlet and outlet pipes to avoid contamination of sensors and lines with particles and liquids. To sum up, the laser dust meter not only uses the sheath gas protection function of the clean gas path, but also the internal detection sensor structure is more complex, which effectively protects the components and prevents the components from being damaged by pollutants. Therefore, it can be used for a long time in a relatively complex and heavily polluted environment. The dust particle counter can only be classified according to several effective particle sizes due to the lack of sheath gas in the gas path design and the relatively simple structure of the detection sensor. The error is larger when converting to dust concentration (the calculation error is greater than 30% when estimating the classification of 8 channels; 2 channel classification, the calculation error is greater than 50%), so the particle counting measurement can only be conducted in a relatively clean space.