Typically three procedures are employed to measure particle size: sieve, Microtrac Laser Diffraction and Fisher Sub-Sieve Sizing.
Almost all particle sizes listed in the section are based on Fisher Sub-Sieve Sizing, however, please bear in mind that the Fisher size must be looked upon only as a general guide to powder fineness and not as a measure of actual particle size distribution.
Should a particle size be expressed as -325 mesh, this powder will pass through a 325 mesh sieve and the particles will be smaller than 325 mesh. If a powder is defined as -200, +325 mesh, the powder will pass through a 200 mesh sieve but will be retained by a 325 mesh. Please note that the material that is less than 200 mesh but greater than 325 mesh in size, may vary in size, depending upon the position of the particle relative to the sieve openings as it passes through.
|Mesh Size||Approximate Micron Size||Millimetres|