Different Particle Measuring Systems and Their Applications

As modern urbanization continues to accelerate, air quality issues are becoming more and more of a focus of attention. At the same time, the quality testing of air filtration materials, masks, filters and other air purification products is also very important. Air quality monitoring, air filtration products testing equipment, are inseparable from the particle measuring systems. So what types of particle measuring systems can be divided into? What are their respective principles and applications? This article will introduce in detail.

Particle measuring systems can be divided into several categories according to different principles, such as photometers, optical particle counters (OPC), aerodynamic particle size spectrometers, condensation nucleus counter (CNC) and differential mobility analyzers (DMA).

1.       Photometers

A photometer is an instrument that uses optical principles to detect particulate matter. It extrapolates the concentration and diameter of particulate matter by measuring the intensity and angle of light scattered by the particulate matter in the light beam. This detector is suitable for most of the airborne particulate matter with particle size less than 1 micron, such as suspended particulate matter and smoke particulate matter.

Photometers are widely used in air quality monitoring, ambient air quality monitoring, industrial exhaust emission monitoring and indoor air quality monitoring. By monitoring and analyzing the concentration of airborne particles in real time, air pollution can be effectively prevented and controlled to protect people's health and life safety.

At the same time, the photometer can also be used in combination with an aerosol generator for on-site testing of installed filters in clean rooms. Test the system as well as the filter for the existence of leaks, has ensured the clean room clean level.

2.       Optical Particle Counters (OPC)

An optical particle counter is another common type of particle detector. It also uses the optical principle to detect particles by shining a laser light source onto tiny particles in the air, which reflect, scatter and absorb laser light. The optical particle counter acquires the characteristics of these reflected, scattered and absorbed light signals and calculates the number, size and distribution of the micro particles based on them. Unlike photometers, optical particle counters test the number and distribution of particles as a result. Depending on the particle size channel of the product, it can be used to detect particles of different particle sizes, such as 0.1μm, 0.2μm, 0.3μm, 0.5μm, 1.0μm, etc.

Optical particle counters are widely used in environmental monitoring, industrial production, medical and health care, food processing and other fields. It can be used to monitor the number and distribution of particles in various places such as the environment, clean rooms in industrial production, food processing, semiconductor industry, hospital operating rooms, wards, etc.

3.       Aerodynamic Particle Size Spectrometers

The principle of aerodynamic particle size spectrometer is based on the kinetic properties of the particles suspended in the airflow, using laser scattering, photoelectric sensing, electronics and other technologies, the particle size, shape and physical properties of the particles and other parameters for monitoring, analysis and calculation. Aerodynamic particle size spectrometer can measure particle size range generally from 0.1 microns to 100 microns, and can analyze the concentration and distribution of particles with different particle sizes.

According to different classification criteria, aerodynamic particle size spectrometers can be divided into laser particle size distribution instrument, multi-channel pulse count meter, light scattering particle measurement instrument and other types. Among them, laser particle size profilers can directly determine parameters such as volume concentration, particle size distribution and particle size distribution function. Multi-channel pulse counters use multiple channels to simultaneously record the pulses of the particles and calculate the number of pulses to determine the number and distribution of the particles. Light scattering particle meters are used to analyze particle size and concentration by scattering and diffraction of particles by laser light.

Aerodynamic particle size spectrometers are widely used in environmental monitoring, atmospheric science, air purification and other fields. In environmental monitoring, aerodynamic particle size spectrometer can be used to monitor the concentration and distribution of various types of particles, so as to provide scientific basis and technical support to guide environmental management and pollution prevention and control work. In atmospheric science, aerodynamic particle size spectrometer can study and simulate atmospheric physical and chemical processes to provide technical support for atmospheric environmental protection. In air purification, the aerodynamic particle size spectrometer can be used to monitor and control pollutants in indoor air to ensure that indoor air quality meets the requirements.

4.       Condensation Nucleus Counter (CNC)

A CNC is a device that uses the condensation principle for particle collection and detection. It works by passing air through a cooling unit that condenses the water vapor in the air into dew and causes the airborne particles to attach to the surface of the dew at temperatures below the dew point temperature to form particle nuclei that are counted by the counter.

According to different detection requirements and application scenarios, CNC can be divided into two categories, remote CNC and proximity CNC.

Remote CNC are generally used for outdoor environmental monitoring and air quality monitoring, and can be used for real-time monitoring under atmospheric conditions, with the advantages of wide detection range and accurate data. Proximity CNC, on the other hand, are mainly used for indoor air quality testing, with a smaller sampling flow rate, which can detect smaller particles and a relatively small detection range.

5.       Differential Mobility Analyzers (DMA)

The DMA is an instrument that uses the migration characteristics of particulate matter in an electric field to detect and analyze it. The basic principle is to separate the particles in an electric field and to determine the size, shape and number of particles according to the rate of their movement in the electric field.

There are two main types of DMA, those that rely on electro-migration and those that rely on scanning electron microscopy.

Among them, the DMA relying on electro-migration method is usually divided into two different types, namely coarse particulate matter detector and fine particulate matter detector. Coarse particulate matter detectors are generally used to detect coarse particulate matter in the air, such as sand and coal dust. While fine particulate matter detectors are mainly used to detect fine particulate matter less than 2.5 microns in diameter, such as smoke, car exhaust, etc.

The differential mobility analyzer, which relies on the scanning electron microscope method, is used to analyze and detect particulate matter by observing the morphology and size of particulate matter under a high-resolution scanning electron microscope.

Micro-mobility analyzers are widely used in many fields such as environmental protection, occupational health, medicine, and food safety.

In the environmental protection field, differential mobility analyzers are mainly used to detect airborne particulate matter, such as PM2.5 and other fine particulate matter, to assess the air pollution status. In the field of occupational health, differential mobility analyzers are used to detect harmful particulate matter in the workplace to ensure the health and safety of workers. In the medical field, differential mobility analyzers are used to detect respiratory diseases for diagnosis and treatment. In the field of food safety, differential mobility analyzers are used to detect harmful particulate matter in food to ensure the quality and safety of food.

Taken together, the particle detector is a very important technical tool. It can detect and analyze particulate matter in different ranges by different detection principles and methods. For different detection needs, we can choose different types of detectors for particulate matter monitoring and analysis. And through the use of particulate matter detectors, we can better grasp the air quality situation, so as to maintain the public environment and human health.