What are aerosols? What are the methods for particle measurement?

Aerosol refers to a stable multi-phase system composed of solid and liquid particles suspended in a gas carrier, such as smoke, fog, haze, flying dust, dust, etc., with a wide range of particle sizes, from nanoscale to millimeter-scale blowing sand, raindrops, Even centimeter-sized hail.

The lifespan of aerosol particles, that is, the residence time in the atmosphere, is related to the size, shape, chemical composition of the particles, and the height of the atmosphere. Fine particles collide and merge with each other due to Brownian motion, and become large particles, which are then settled due to gravity. Lower to the ground.

Atmospheric particles for room cleanliness and weather forecasting are the most common aerosol measurements, usually with particle counters. In laboratories and industries, aerosol classification, elutriation method for purification, membrane filter method, cyclone separator, jet impactor, centrifugal classifier, electrostatic classifier (also called electromigration analysis), diffusion battery, etc. , are all methods of measuring aerosol particle size in use.

In fact, some particle size measurement methods used in the powder industry, such as laser particle size measurement, image method, light scattering method, etc., have also been studied and applied in aerosol particle size measurement work for a long time.