Centrifuges

1. Centrifuges

2. A centrifuge is a piece of equipment, generally driven by a motor, that puts an object in rotation around a fixed axis, applying force perpendicular to the axis.  The centrifuge works using the sedimentation principle, where the centrifugal force is used to separate substances of greater and less density.

3. Terminology Pellet - Material that has accumulated on the bottom of a tube after centrifugation (if any) is called the "pellet�. Material comprising the pellet is said to have "sedimented". Supernatant - The overlying fluid is called the "supernatant solution" or simple the "supernate�. Relative centrifugal force or Centrifugal effect - The force that the sample is subjected to, is expressed as some number times the force of gravity, or relative centrifugal force (RCF). Critical speed - Critical speed is the speed when the frequency of rotation matches the natural frequency of the rotating part and any vibration induced by slight imbalance in the rotor is highly magnified, resulting in high stresses and even failure of the equipment. Almost all centrifuges operate above the critical speed.

4. Basis of separation:-Size �Shape -Density Methodology:- Utilizes density difference between the particles and the medium in which these are dispersed- Dispersed systems are subjected to artificially induced gravitational fields.- The centrifugal force causes the sedimentation of heavier solid particles.