The working principle of centrifuge and classification

- Oct 30, 2019-

Working principle of the centrifuge

When suspending liquid containing small particles let stand motionless, due to the effect of the gravity field of suspended particles sinking gradually. The heavier the particle, the faster the sinking, whereas density than the liquid small particles will rise. The speed of the particles in the gravitational field of mobile is associated with the size, shape and density of particles, and is related to the strength of the gravitational field and the viscosity of the liquid.

In addition, the material in the medium of the sedimentation was accompanied by a diffusion phenomenon. Diffusion is unconditional. Is inversely proportional to the diffusion and the quality of the material, the smaller the particle diffusion is more serious. And settlement is relative, conditional, subject to external forces to movement. The size of particles sedimentation is proportional to the mass of settlement. For less than a few microns particles, such as a virus or protein in solution into colloid or half colloidal state, it is impossible to just use gravity sedimentation process was observed. The slower because the smaller the particle sedimentation, and diffusion phenomenon is more serious. Develop a strong centrifugal force, so you need to use the centrifuge to force the particles to overcome the diffusion to produce subsidence movement.


Centrifugal is to use the strong centrifugal force produced by the rotation of the centrifuge rotor speed, speed up the settlement of particles in the liquid, the samples in different subsidence coefficient and buoyant density of the material.


The classification of the centrifuge:

Centrifuge classification method has three kinds: according to utility cent, according to speed and according to the structure.

Low classification: according to the use type centrifuge and the preparation of analysis, divided into preparation.

Preparation type centrifuge: only for separation, enrichment and purification of sample of the centrifuge.

Preparation of analysis of the centrifuge: not only can separation, enrichment and purification of sample, but also through the optical system of the settlement of sample process to observe and take photos, measurement, digital output, printing, automatic display of centrifuge.

Low classification of rotating speed: divided into centrifuge, overspeed, low speed centrifuge, and speed.

Low speed centrifuge: speed within 10000 RPM or relative centrifugal force within 15000 x g.

Within 10000 ∽ 30000 RPM speed centrifuge: speed within 15000 ∽ 70000 x g or relative centrifugal force.

Ultracentrifuge: speed above 30000 RPM or relative centrifugal force is more than 70000 x g.

"According to the structure classification:

As in speed and low speed centrifuge classified according to the structure and function, wide variety, GeChang naming also has no unified standard. Can be divided into the bench centrifuge, multi-tube trace centrifuge table centrifuge, smear, blood washing bench centrifuge, speed refrigerated centrifuge, large-capacity low-speed refrigerated centrifuge and low-speed refrigerated centrifuge, desktop speed refrigerated centrifuge, centrifuge table low speed automatic balance, etc. In addition there is the joint type (immovable type) speed refrigerated centrifuge, designed for continuous centrifugal.