Simplifying the calculation of equivalent diameter in sedimentation tests

Abstract

In sedimentation tests, the equivalent diameter of particles, D, is calculated using an equation derived from Stokes’ law and a factor K interpolated from a table listing values of suspension temperature and the specific gravity of solids. This paper explains how to start with Stokes’ law and obtain the equation used in standards. Then it provides two equations for K, both of which are accurate for the usual temperature range for hydrometer tests, and for any specific gravity. The two equations can be used in spreadsheets to automatically calculate D, an easier process than obtaining or interpolating K from a table.