Speed vs Centrifugal Force Graphs

If particles with densities (specific gravity) larger than the surrounding liquid are distributed in a solution or suspension, and if a force acts which overcomes random thermal motion of these particles, the particles will move to form a stable pellet. The velocity of sedimentation depends on the size of the particle, on the density difference between particle and solution, on the viscosity of the solution, and on the force which causes the movement the gravitation or the centrifugal force. 

The force produced in a rotating body is given as multiples of earth s gravitational field (9.807 m/s ), and relative centrifugal field (ref) is calculated by 

In a centrifuge rotor g ax is the maximal centrifugal force at maximal distance from rotor axis r ax (at the bottom of the tube), gmin is the minimal force at the top of the tube (rmin), and the arithmetic mean of both is called gav The difference of r ax and rmin is the sedimentation path length. 

The tubes of the swinging bucket rotor type are accommodated in a pivoted bucket moving from vertical to horizontal position during acceleration under the influence of the centrifugal field. The sedimentation path length is lowest in vertical rotors and highest in swinging-bucket rotors. 

The relations between rotor speed and centrifugal force for different rotors are illustrated by Figs. 5.1-5.3. 

---