Collection: Centrifuges

RCF is relative centrifugal force — the actual g-force on the sample — and it is what a protocol specifies. RPM is only the rotor's speed, and the same RPM produces a different force in a different rotor because RCF depends on the radius. Two centrifuges running the same RPM can be spinning your sample at very different forces, so always convert and set by RCF.

A fixed-angle rotor holds tubes at a set angle, pellets against the tube wall and side, and generally reaches higher speeds — right for pelleting cells and precipitates. A swing-out rotor lets tubes rotate horizontal, so the pellet forms flat at the bottom and layers stay cleanly separated — right for gradients, blood separation and anything you will decant.

The rotor, not the centrifuge, sets what fits. Check the rotor's tube capacity and diameter, and whether adapters are needed to run smaller tubes. Also check the tube's own RCF rating against the speed you intend to run — the rotor will happily exceed what the tube can take.

Always, and by mass rather than by eye. Opposing positions should be filled with tubes of equal weight; an unbalanced rotor damages the bearings and, at speed, is a genuine hazard. Balance with a water-filled tube if you have an odd number of samples.