The ultracentrifuge is a commonly used type of laboratory equipment. Rotors are exposed to enormous forces every time they are used. Rotors can fail catastrophically, resulting in destruction of the entire centrifuge and damage to a laboratory. As evidenced by the attached photographs, there is no doubt that serious injury could result should someone be present when a failure occurs. To prevent such failures, all ultracentrifuge manufacturers require that ultracentrifuge users maintain an up-to-date use log for each rotor, and also require that each time a rotor is used it must be given a thorough visual inspection for any signs of damage or weakness.
To understand the forces involved, a standard “run” for separating components of a cell nucleus disruption might require 55,000 revolutions per minute (RPM) for 600 minutes. This force easily generates 100,000 times the force of earth’s gravity (G-forces or “Gees”) within the sample containers for the entire run. A standard 20-pound fixed chamber ultracentrifuge rotor at these conditions holds over a million joules of energy, which is roughly equivalent to the energy released by exploding several 1" sticks of dynamite. Subjecting a rotor to such forces over time will lead to violent failure, and while centrifuges are designed to contain a rotor failure, they will at the very least be destroyed. The purpose of the use log is to ensure that the amount of stress imposed upon the rotor is known exactly, so that the rotor may be used for its full lifetime without risking excess stress. A rotor can also be “de-rated” by a qualified service technician who establishes a new, lower RPM and G-force limit. This can extend the rotor’s useful life as long as it is never exposed to conditions that exceed the reduced rating.