The rotor is one of the most important components of a centrifuge, since it determines the maximum centrifugal force, sample capacity, how samples are held, and which separation techniques the instrument can support. This cluster covers the main rotor types used in laboratory centrifuges along with the accessories used to adapt them to different sample formats.

What are fixed-angle rotors?

Fixed-angle rotors hold sample tubes at a fixed angle, typically between 20 and 45 degrees relative to the vertical axis. It causes particles to sediment toward the outer wall and bottom of the tube. This design allows for faster sedimentation and shorter run times compared to swing-out rotors. It makes fixed-angle rotors well suited to routine pelleting tasks such as cell harvesting or precipitate collection.

What are swing-out rotors?

Swing-out rotors, also called swinging-bucket rotors, hold tubes in individual buckets that pivot outward to a horizontal position as the rotor spins, then return to a vertical hanging position when the rotor stops. This produces a flat, even pellet at the bottom of the tube and is preferred for applications such as density gradient separations, where a smooth, undisturbed liquid layering is important to the result.

What are hematocrit rotors?

Hematocrit rotors are specialized rotors designed to hold small capillary tubes for hematocrit testing, spinning blood samples at high speed to separate red blood cells from plasma for volume percentage measurement. Their compact design allows a large number of capillary tubes to be processed simultaneously. This makes them common in clinical and hematology laboratories.

What are tube adapters?

Tube adapters are inserts placed within a rotor’s tube cavities that allow smaller tubes to be securely held in a rotor originally designed for a larger tube size. They allow a single rotor to accommodate multiple tube volumes without requiring a separate rotor for each format. This improves flexibility for laboratories running varied sample volumes.

Buckets

Buckets are the individual tube-holding components of a swing-out rotor, attached to the rotor body and free to pivot outward during rotation before returning to a vertical position at rest. Each bucket is designed to hold a specific tube or plate format. Buckets must be matched in pairs of equal weight across the rotor to maintain balance during a run.

Buckets are typically interchangeable, allowing different tube sizes, bottles, or microplates to be used with the same swing-out rotor, provided they are approved by the manufacturer.