Mechanical Operations
For a non-spherical particle, the sphericity

Has the dimension of length
Is the ratio of volume of a sphere having the same surface area as the particle to the actual volume of the particle
Is defined as the ratio of surface area of a sphere having the same volume as the particle to the actual surface area of the particle
Is always less than 1

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Mechanical Operations
Higher is the mesh number, smaller will be the aperture size of the screen. It means that the aperture size of a 200 mesh screen will be smaller than that of 20 mesh screen. This is valid for

German standard screens (DIN 1171) etc
British standard screens
All of these
American standard screens (ASTM and Tyler standard screens)

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