Sedimentation analysis is based on the principle that particles suspended in a fluid settle at rates depending on their size and density under the influence of gravity. Larger and denser particles settle faster, whereas finer and lighter particles settle more slowly.

In this method, an Andreasen pipette is used to extract liquid samples from a fixed depth in the suspension at specific time intervals. The amount of solid material remaining in suspension at each interval is measured to determine the particle size distribution.

This technique is governed by Stokes’ Law, which relates the settling velocity of spherical particles to their diameter, the viscosity of the fluid, and the density difference between the solid and liquid phases.

Formula:
V = D²(ρₛ − ρf)g / 18η

Where:
V = Settling velocity of the particle
D = Diameter of the particle
ρₛ = Density of the solid particles
ρf = Density of the fluid
g = Acceleration due to gravity
η = Viscosity of the fluid