Using k-Factor to Compare Rotor Efficiency
Most researchers refer to the maximum speed of a rotor to compare efficiency. This can be misleading, however, since other factors such as the geometry of the tube or temperature contribute to rotor performance and must be considered before a valid comparison between similar rotors can be made. Some rotors are more efficient at slower speeds than a comparable rotor at higher speeds, simply because of the influence of these additional factors. So, we recommend using the term k-factor, rather than maximum speed, to compare centrifugation labware.