Centrifugal Separation: Keep Rotor Radius Beside RPM

Define the Interface or Transport Basis

Eppendorf's rotor manual, section 5.1 calculates relative centrifugal force from spinning radius and squared RPM. Written with radius r in centimetres, RCF is approximately 1.118×10⁻⁵·r·RPM² in multiples of g. Keep the radius location with the conversion rather than treating RPM as a transferable separation condition.

Review a Hypothetical Comparison

For a purely hypothetical comparison at 3000 RPM, a location at 8 cm radius gives approximately 805×g, while one at 16 cm gives approximately 1610×g. Both rotate at the same RPM but the second location has twice the relative acceleration. Conversely, maintaining an assigned RCF when radius doubles would require RPM divided by the square root of 2, rather than RPM divided by 2. These calculations do not choose a real rotor speed.

Keep the Evidence with the Decision

Record whether the stated radius is minimum, mean, maximum or another defined sample location. Match that convention when transferring a reported condition. Preserve rotor geometry and the independently relevant sample and separation evidence. If a report supplies only RPM, request the radius before claiming it matches another setup.

A matched RCF does not guarantee identical sedimentation, run time or material separation in different geometries. Follow the actual equipment documentation for operating decisions; this worksheet makes no approved speed or loading assertion.

Which relative centrifugal acceleration follows at the specified particle location?

This blank worksheet is for your own project. It contains no H M machine trial result.

Customer Questions

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• Eppendorf's rotor manual, section 5.1
• Reference from hmpharmamachines.com