Centrifugal Separator Working Principle

When a suspension of fine particles is left undisturbed, the particles gradually settle due to the force of gravity. Heavier particles sink faster, while those with a lower density than the liquid will float. The speed at which the particles move under the influence of gravity is related to their size, shape, and density, as well as to the intensity of the gravitational field and the viscosity of the liquid.

Moreover, when matter settles in a medium, it is accompanied by a phenomenon of diffusion. Diffusion is unconditional. It is inversely proportional to the mass of the substance; the smaller the particles, the more severe the diffusion. In contrast, settling is relative and conditional, requiring an external force to move. Settling is directly proportional to the weight of the object; the larger the particles, the faster the settling. For particles smaller than a few micrometers, such as viruses or proteins, they exist in colloidal or semi-colloidal states in solutions. It is impossible to observe the settling process solely by gravity, as the smaller the particles, the slower the settling, and the more pronounced the diffusion phenomenon becomes. Therefore, it is necessary to use a centrifuge to generate strong centrifugal force to force these particles to overcome diffusion and initiate settling movement.
Centrifugation utilizes the strong centrifugal force generated by the high-speed rotation of the centrifuge rotor to accelerate the settling speed of particles in the liquid, separating substances with different sedimentation coefficients and buoyant densities within the sample.