Measure for the size of irregular shaped particles which is, for instance, used in the determination of particle sizes in soils and sediments
Soil particles are of irregular shape and their size is difficult to determine. Therefore, the so called ‘equivalent diameter’ is used as measure which refers to the diameter of a sphere which behaves like the respective soil particle.
If particle sizes are determined by mechanical sieving, the equivalent diameter refers to the diameter of a sphere which barely passes through a defined sieve pore.
Smaller particle sizes are often determined by sedimentation in an aqueous medium and the equivalent diameter refers to the diameter of a sphere with the same density and the same sedimentation velocity.