How peristaltic pumps work

2021-06-02

Peristaltic pumps are like pinching a fluid-filled hose with your fingers, moving forward as the fingers slide forward. Peristaltic pumps are also the principle that only the roller replaces the finger. The fluid is pumped by alternately squeezing and releasing the flexible delivery hose of the pump. Just like pinching a hose with two fingers, as the finger moves, a negative pressure builds up inside the tube and the liquid flows.

The peristaltic pumps form a "pillow" shaped fluid in a section of the pump tube between the two rollers. The volume of the "pillow" depends on the inner diameter of the pump tube and the geometry of the rotor. The flow rate depends on the product of the speed of the pump head and the size of the "pillow" and the number of "pillows" produced per revolution of the rotor.

How peristaltic pumps work

The size of the "pillow" is generally constant (except when pumping a particularly viscous fluid).

Compared with a pump with the same diameter of the rotor, a pump with a larger "pillow" volume has a larger volume of fluid delivered per revolution of the rotor, but the pulsation is also greater. This is similar to the case of a membrane valve. Pumps that produce smaller "pillow" volumes have a smaller volume of fluid delivered per revolution of the rotor; moreover, a small, "pillow" formed quickly and continuously provides a smoother flow of fluid. This works in a similar way to a gear pump.

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