We have all used one in a laboratory. We have put test tubes into them, heard the motor swirl, watched the mechanism rotate and spin, and see if a precipitate was produced. Like many devices, we simply accepted the centrifuge for the task that it produced. But did we ever stop to think about how and why it was able to accomplish this task? Outside of former physics majors, I doubt many readers could provide the answer to this question. Two aspects of physics are responsible for the centrifuges functionality – centripetal force combines with the sedimentary principle to produce the desired result.

Centripetal Force: Centripetal force is created by the concept of centripetal acceleration. This is based on Newtonian physics which states that an object in motion will stay in motion (in the same direction) unless another object or medium acts upon it. In the case of a centrifuge, the objects contained attempt to move in a consistent straight line (ever changing) in the direction that they are presently being moved, with the centrifuge’s construction forcing that motion into a curve. As a display of this, let us consider the centrifuge. We know that objects contained are moving in a curve due to the rotary motor of the device. However, let us imagine that the centrifuge merely disappeared mid rotation, but that the objects it is spinning remained. The objects would not continue to curve and spin in a circle without the circular force being constantly applied. With the centrifuge now disappeared, the objects would actually jet off in straight lines determined by the direction that they were pointing at the very last moment of the centrifuge’s existence.

Sedimentary Principle: This principle states that heavier particles in suspension of a given fluid will settle out to the bottom of the solution over time. This does require some force to act upon them, but in the absence of an outer space vacuum, gravity often will suffice. The falling and gathering of these particles into clumps is often referred to as the precipitate – which is typically what a centrifuge is aiming to produce (or at least determine if it can be produced for scientific experiments where the overall outcome is unknown.

These two physical laws act in tandem and are accelerated by the centrifuge to spin denser (or heavier) particles out of solution and create the aforementioned precipitate.

Types of Centrifuges: It should be noted that there are more than one type of this device. While they are labeled the same based upon the physical forces used and the desired effects, the mechanisms and machinery working together to create this effect can vary. Types of scientific centrifuges include preparatory, analytical, angle fixed, and swing head. Industrial centrifuges server a more large scale purpose to separate product out of a mixture for further processing (or as an end result in rare instances). Examples of these types of centrifuges may be basket, bowl, chamber, disc or peeler.

However, regardless of the type of centrifuge used, it is those two basic physical laws that make the process possible. The devices would not exist without them.

Author Bio: By Felix Chesterfield III
If you would like to learn more about centrifuges (including industrial variations such as basket centrifuges), please contact the author. There is also a great deal more information available on the topic via Wikipedia’s section on centrifuges. But we would recommend sticking to the documentation section for the most reliable information.

Category: Computers and Technology
Keywords: Centrifuges, lab equipment, industrial equipment