The centrifuge For the first time, a British engineer named Benjamin Robbins had created a rotating armpit to identify drugs. In 1879, Anthony Pringles used the first centrifuges for milk to be separated from the cream. In 1879, a person called Gathat showed that centrifuges could be used for business purposes. Different dimensions of centrifuges have been expanded and can be evaluated in a range of functions from 1 ml to 1 liter.


The image is from a centrifuge belonging to the 19th Century that spins around.

 Attention to micro-centrifuges was developed by a German company in 1962, and the company used micro-polymer systems for laboratory use.

Principles of centrifuge

If the centrifuge particles in a sample have different masses, they can be separated from each other based on the difference in mass and the effect of their gravity. To accelerate this, a method called centrifuge or ointment is used. The central core of the centrifuge is the centrifugal principle, which is one of the principles of the physics of the era.

 In fact, centrifugal separation by centrifugal force separates the suspension from the liquid. It can also cause the separation of two liquid with different densities. These fluids can be body fluids (such as blood, serum, and urine).

By centrifuging the force of gravity several times, it increases the natural rate of separation of particles with different densities.

At a glance, the centrifuge is a metal flywheel with holes in which the specimens are intended and a motor that rotates at a selected speed.

What is centrifuge

  A centrifuge or centrifugal device is a device that separates materials from the center of the centrifugal force. The enclosure, in which the detachable material is located, is usually used with the help of a motor speeding around a rotating axis for rotating the material at a high speed. Scientists usually use a centrifuge device to separate solids from a liquid or to split liquids into various components.

  The mixture is placed in a tube so that the device moves outward from the center and rotate to the horizontal. In this case, the centrifugal force wants to remove the mixture, in contrast to the center of the centrifuge, and away from this point. In this case, the heavier particles or heavier fluid is further driven outward (or substrate). When the centrifuge stops moving, the material remains unconsolidated. Blood and other biological samples are usually isolated by centrifugal machines

Different types of centrifugal devices are made for various uses. Household samples are used to separate water from vegetables such as lettuce and so on. Plasma samples are used to remove blood globulins. Industrial machines are powered by robust and large-sized engines for separating materials. The uranium enrichment plant also uses gas centrifuge devices

Centrifuge division according to the speed of rotation

1 centrifuge with high speed

2 centrifuges with low speed

3 ultrasonic centrifuges

High-end centrifuges

The round circumference is between rpm24000-21000 and a maximum rpm of 30000. High-speed centrifuges are used for most products. All are refrigerated.

There are two types of high-end centrifuges: low capacity and high capacity.

Low-capacity centrifuge: With discrete sampling, it can isolate microorganisms, cells, viruses and cellular organs.

High-density centrifuge: A continuous model for obtaining yeast and bacteria from the culture medium, the protein from the specimens and the virus and bacteriophage from the diluted specimens. (2)

Downstream centrifuges

Its round ranges range from 2000 to 6000 rpm with a maximum of 8000 rpm in both refrigerated and non-refrigerated form. More often, centrifugation of blood cells or bulk particles is not enough and it is not enough to separate fine particles.

Ultrasound Centrifuges

The ultra rpm is 100,000-75,000 with a maximum of 120,000 rpm. They are used to differentiate cellular ingredients. All have a refrigerator. Because during the high friction period (1), the air causes the device to heat up and thus destroy the proteins. Ultras are commonly used in research centers.

Properties of centrifuges based on their rotation: (Table 1)

Properties Ultra Centrifuge Above Far down
Speed ​​(rpm * 1000) 120-75 30-21 8-2
Refrigerator Everyone Everyone Some models
Vacuum system Everyone Some models No
accelerator mostly mostly Some

In the division, the other centrifuges are divided into three types of floating, fixed and axial angles:

Floating centrifuges:

In this type of centrifuge, in the state of the vertical stop, and in the period of time, the samples have a horizontal position with the ground.

In this type of centrifuge, suspended particles are driven by the influence of the centrifugal force on the external part, the end of the tubes and the deposit is formed as an almost uniform layer at the bottom of the tube. At the end of the operation, the tubes containing the sample are restored to the vertical, depositing at the bottom of the tube and a clear solution above it.

 Fixed angle centrifuges:

In this type of centrifuge, the tube contains a sample relative to the axis of a one-dimensional angle. This angle can vary from 25 to 45 degrees, and the suspended particles are driven by the centrifugal force to the outside of the axis, but, unlike centrifuges, the sediment floats are driven in the wall and in the part of the pipe bottom located on the outer side of the axis of the rotation. To be

Of course, as this angle is less in relation to the axis of the period, the precipitate is more in the wall, and if the angle is greater, the sediment is more concentrated in the floor.

The rotor shape of this type of centrifuge allows for a longer period of time and deposition of smaller particles. Therefore, the sedimentation rate of this type of float is higher.

If you want to use a floating point like a fixed angle, then the higher the temperature, the higher the friction with air, the temperature will increase.

Axial centrifuges:

In principle, the sample tube runs along its vertical axis (unlike ordinary centrifuges that run along the horizontal axis) .

Application of different types of centrifuges: (Table 2)

Isolation / Type Ultra Centrifuge Above Far down
The cell Yes Yes Yes
Sediment Everyone mostly Some
Membrane parts Everyone Some No
Ribosomal-poly-zoom Everyone Some No
Macromolecule Everyone Some No

Components of the centrifuge machine:

1. Motor (pump) 2. Rotor 3. Refrigerator 4. Control system 5. Device compartment

 Rotor: centrifuge

A typical centrifuge has a chamber called a rotor or head that works with the engine. Rotors have different types, but the types that are commonly used in laboratories are divided into two categories: the first group of rotors in which the tube contains a solid-liquid at a constant angle and therefore they are rotors Say with a fixed angle. The second group is the ones in which the tubes are located in metal chambers and are rotatably rotated externally and horizontally so that the fluid and the suspended material inside the pipes are exposed to centrifugal force. This rotor The rotors are called with a hanging compartment.

When the body rotates, technically, the centroidal force forces the object to move in a circular path with a constant radius, which forces the body to rotate to the center of the circle continuously. When the speed is constant, this force only causes the change On the other hand, the body is pulled by a force called the center of gravity, in front of the direction of movement, which is equal to the centroidal force and causes the body to move away from the curve of the circle of rotation in a straight and tangential direction. On the circle

The rotor specifications for different centrifuge methods are presented in Table 3

Rotor type Isopicric regional Sedimentation Differentiation
Fixed angle Good Weak Excellent
Vertical Good Good Weak
Floating Enough Good inefficient
zonal Enough Excellent Weak

Application of Centrifuge

In the sweetening of the highly concentrated syrup, the masonite consists of two solid parts (sugar crystals) and a liquid (non-crystalline section), which in turn is separated from each other by centrifugation. The sugar crystals are washed and then high-purity sugar is produced.

 So the water of this section, due to its significant amounts of sugar, is crystallized in several steps, eventually, the water, which can no longer be obtained from the crystal, is removed as molasses from the factory. In some factories, the molasses go to the molasses sugar mill and are recycled with molasses sugar powdered lime powder. In factories that produce sugar, centrifuges are used to convert sugar into sugar

 There are centrifuges in all of the parts that need to be isolated, and another example is its use in the food industry in dairy factories.

  • In the starching industry, coloring, knitting for the drying of chemical chemicals, clothing and so on.
  • Centrifuges can also be used to control air pollution at the site of production.

Types of centrifuges used in active sewage and sludge sources

1-centrifugal solid bowl (cylindrical)

2-Centrifugal Baskets (Perforated Basket, Basket Without Hole)

3rd Centrifuge Disc

Centrifugal cylindrical

Cylindrical centrifugal (tube bowl) is one of the important types that can easily produce a lot of centrifugal force. Cylindrical centrifuges can be cooled, which is an advantage in working with proteins.

In this type of suspension, centrifuge it usually enters the end of the tube and the transparent liquid is removed from the top. The solids in the solution form as a thick paste layer on the wall of the tube until it can be seen at the outlet of the solid. Injection continued, then shut off and finish the centrifuge. This interruption in operation is a major issue

The residence time of a liquid in a cylindrical centrifuge

Main cylindrical centrifugal equation (inlet feed)

The sedimentation centrifuge rate is only a function of particles and is independent of the specific centrifuges, but the amount in the bracket that is too long does not function as a particle and depends only on the type of centrifuge.

Filtering radiographs and their design equations

Centrifuge filter   (Centrifugal filter)

  • These filters are divided into two general types of continuous and discontinuous. Usually, these filters are used for solids that form a porous mold. To do this, the slurry is inserted into a rotating basket that has a grooved or lattice wall, or the filtering environment is covered with cloth or metal nets.

Types of Filtering Centrifuges

  • Discontinuous filtering
  • Continuous Filtering Centrifugation

Heterogeneous filtering from above (discontinuous)

Filter Cartridge with Reciprocating Cartridge (Continuous)

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