Which type of centrifuge has tubes that rotate outward from vertical to horizontal during operation?

• A. Angle head centrifuge
• B. Micro-haematocrit centrifuge
• C. Swing-out centrifuge
• D. Ultracentrifuge

Answer: (C)

In a centrifuge, how the tubes sit during spinning depends on the rotor design. A swing-out (swinging-bucket) rotor has buckets that hang vertically when at rest but swing outward to a horizontal position as speed increases. This outward swing causes the tubes to become horizontal during operation, which is the characteristic described in the question.

This is different from an angle head rotor, where tubes are fixed at a tilted angle and do not swing outward. A micro-haematocrit centrifuge uses fixed-angle tubes designed for rapid blood separation, not swinging to horizontal. Ultracentrifuges can use either fixed-angle or swinging-bucket rotors, but the outward horizontal orientation during spinning points to the swing-out design.