How do You Compare Centrifuges, by RPM or RCF?

Although a centrifuge is not particularly difficult to build, a good centrifuge requires good engineering. There are several centrifuge manufacturers out there offering their products by RPM and a few manufacturers specifying G force. So what really matters and how do you compare centrifuges?

What is RPM?  Revolutions Per Minute

What is RCF? RCF Relative Centrifugal Force or G force. How many times the force of gravity.

Since a centrifuge is a “high gravity” settling machine, knowing the G force is important.

G force is the actual power of the centrifuge, similar to horsepower of a motor.

You specify a motor by horsepower not RPM, for example, “My Dodge Charger has a 372 horse power motor,” not “My Dodge Charger has a 4500 RPM motor.”

RPM has little to do with actual power output in an engine or a centrifuge.

The COX gas engine in my model airplane runs at 17,000 RPM and produces .08 horsepower.

A stationary Diesel operates between 60 and 200 RPM and may produce over 100,000 horsepower.

Similarly, actual centrifuge power is not rated by RPM, but by G force.  For example, 1200 Gs is 1200 times the force of gravity.   3000 G is 3000 times the force of gravity. Now you have a way to compare the power of a centrifuge.

If a manufacturer doesn’t quote the G force, then they either don’t want you to know what it is, or they don’t know how to calculate it. Either way, you have no idea what you are buying if you don’t know the G force of the centrifuge. A properly engineered centrifuge starts with specifying the required G force, and then the machine is designed to meet the stresses produced at that G force. Building a centrifuge with no idea of the stresses produced when at running speed is like designing brakes on a car with no idea of how fast you will be going and the force required to stop.

Summarily, one should be skeptical of manufacturers offering centrifuges without specifying their G force.  How much engineering could be involved in a piece of machinery where the maker only knows how fast it goes?  Look under the hood. You wouldn’t buy a Corvette with a 4 cylinder engine. When shopping for a centrifuge, ask for the G force so that you can properly compare units.