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Types of Centrifuges – Some General Information

The demand for unique solutions to modern day challenges has led innovators to develop methods of taming natural forces and energy for commercial and domestic purposes. A centrifuge is an example of a solution that is used in the separation of solid components in fluids and liquid filtration. The centrifuge works by spinning objects in a circle on a fixed axis. This spinning action generates two radial forces in the centrifuge namely Centrifugal and Centripetal Force.
Centrifugal Force pushes components outward towards the edge of the circle, while Centripetal works in the opposite direction, pulling components inwards towards the centre of rotation. Centrifugal force is the stronger of the two in a centrifuge thus the heavier components get pushed to the outer parts of the centrifuge while less dense components collect near the centre depending on the specific centrifuge design.
In the 1860’s, a pair of brothers, Antonin and Alexander Prandtl, began working on the idea to make a dairy centrifuge for separating cream from milk. This work led them to develop the first fully functional butterfat extraction machine which they availed to the public in 1875, setting the stage for the development of centrifuges for a wide variety of applications all over the world.
Classification of Centrifuges
Centrifuges have several applications in our everyday life, from basic operations like drying out clothes in washing machines to large-scale industrial applications such as separating solids from liquids in municipal wastewater treatment plants. Since centrifuges vary greatly, there are several ways to classify them; some methods are listed here below.
1. Mode of Operation
There are two main modes of operation of centrifuges. This refers to how the machine works. The centrifuge can either be Sedimentation or Filtration type.
Sedimentation centrifuges are used for the purification of a suspension fluid by accelerating the natural deposition process. They consist of a single containment unit for the fluid where centrifugal force is used to force dense components to settle at the bottom and the liquid is drained off periodically. Examples of Sedimentation Centrifuges are Decanter, Conical plate, solid bowl, pendulum, and tubular centrifuges.

Filtration or Screen Centrifuges have a separation in the fluid containment unit with a perforated wall that has a filter or screen attached to it. When the centrifugal force is exerted, the fluid flows out of the container through the filter and the solids remain behind. Examples of Filtration centrifuges are scroll centrifuges, sliding discharge centrifuges, and inverting filter centrifuges and many more.

2. Classification by Purpose
Most people select centrifuges based on their intended use. This varies according to the type of fluid to be worked on and the requirements for successful separation of the fluid components. Examples of centrifuges classified by purpose are laboratory centrifuges, haematocrit centrifuges, and gas centrifuges among others.
There are many more methods of classification of centrifuges including rotor design, size, speed, and centrifugal fields (force generated) among others. Take your time when choosing your centrifuge because it has a big effect on the quality and consistency of the final fluid separation.


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