How does a Centrifuge Work?
Centrifuges are very useful tools in today’s world. You might not know it, but almost everyone has a centrifuge at home – clothes washing machine. When you visit the doctor and take a blood test, a centrifuge is used to determine the results at a lab. Other uses of centrifuges are during the rides in an amusement park, and testing equipment for astronauts to test gravitational forces on the human body. Centrifuges are even used in nuclear and experimental research by scientists in large institutions and research centers.
The Concept
The concept behind how a centrifuge works is pretty simple. A centrifuge includes a compartment which spins around an axis. The compartment is usually driven by a motor and can travel very quickly, revolving hundreds to thousands of times around the axis in a minute. The speed of a centrifuge is measured by RPMs (revolutions per minute). While small centrifuges have extremely high RPMs, larger centrifuges like those used by astronauts to test g-forces have much slower RPMs due to the distance they must travel around an axis per minute.
An Example
Going back to our home centrifuge found in a household washing machine – this centrifuge works when we put wet clothes in an inner tube with perforated holes that spins around a center axis. Besides an inner tube, there is also an outer tube located inside our washing machine. When wet clothes spin, the centrifugal force (force created by the centrifuge revolving around an axis very quickly) pushes the clothes against the inner tub with the holes, and the water carrying dirt flows through these holes to the outer tub which leads the water to the drain. You have probably noticed your washing machines has a spin cycle, this is the cycle in which centrifuge not only removes dirty water form your clothes, but helps removes moisture as well. Most washing machines have a motor along with a belt to turn the inner tub extremely fast. While not as fast as most lab centrifuges, your washing machine includes a centrifuge nonetheless.
Use of Centrifugal Force
Centrifugal force forces a body whether solid, liquid or gas, to be pushed away from the center of rotation. This force is used in many technologies such as blood testing, where separate substances of greater and lesser densities are separated easily to be evaluated. In fact, the first centrifuges were made to separate cream from milk and help make butter.