Swing-out rotors mean that the buckets swing out horizontally. This means that the user will achieve flat separation. A fixed angle rotor means that the tubes are loaded into the rotor at a fixed angle, usually between 30° and 40°. This means that the separation with be at an angle.

The advantage of a fixed angle rotor is that you can achieve much higher speeds. This is because of the aerodynamic shape of the rotor. Although a swing-out rotor cannot reach the same speeds, it does result in flat separation, which is what the majority of users require.

Swing-out rotors are used for most biological applications and fixed angle rotors only tend to be used when a greater speed is required to separate the substance.