ABSTRACT
Particle size data are essential to anyone treating powders. If particles are spherical, it is easy to define the particle size because the diameter is the unique expression of their size. The sedimentation method is a precise particle size analyzer, and is important. In the case of analyzing the particle images, the particle size is commonly expressed with the equivalent area diameter or Feret’s. The laser scattering diameter is the most common because the particle size analyzers based on the laser scattering theory are very widely used. If a size distribution obeys the log-normal form, the distribution converted by Equation also obeys the log-normal form. Their geometric standard deviations are the same, and the median diameters are different but can convert each other.
