Calculating k Factor

Most researchers refer to the maximum speed of a rotor to compare efficiency. This can be misleading as factors such as tube geometry and temperature contribute to rotor performance and must also be considered.

Separation is affected by maximum speed and radius which together determine maximum g-force. However, particle pathlength also affects separation time. A simple measure of overall rotor efficiency incorporating both g-force and particle pathlength is the Factor. Generally, the lower the Factor, the shorter the run time. This makes the Factor one of the most important considerations when selecting a rotor. 

Particle Separation in Swinging Bucket, Fixed Angle, Near Vertical and Vertical Tube Rotors

Darker shading represents pelleted material.  Lighter shading depicts floating components. Bands indicated by black lines.

Swinging Bucket Rotors

Typical Example: SW 60 Ti

Pathlength: 57.2 mm

k Factor: 45

 Swinging Bucket Rotor Pathlength

Fixed Angle Rotors

Typical Example: 90 Ti

Pathlength: 42.3 mm

k Factor: 25

 Fixed Angle Rotor Pathlength

Near Vertical Tube Rotors

Typical Example: NVT 90

Pathlength: 18.7 mm

k Factor: 10

 Near Vertical Rotor Pathlength

Vertical Tube Rotors

Typical Example: VTi 90

Pathlength: 13.2 mm

k Factor: 6

 Vertical Tube rotor pathlength