Roller Peristaltic Pump: Occlusion & Flow Ripple

Pump Settings

Rotor speed 60 RPM

Rollers on rotor

Tube inner diameter 4.0 mm

Occlusion (tube compression) 115%

Live Readouts

Avg. flow rate

0 mL/min

Pulsation ripple

Instantaneous fluid velocity

0 mm/s

How it works

A roller (rotary peristaltic) pump has n rollers mounted on a rotor spinning inside a curved housing. Each roller presses the flexible tube shut against the outer track as it passes, "milking" the fluid ahead of it forward — the tube itself is the only wetted part, so nothing touches the fluid but the tubing.

Average flow:  Q = A · L · RPM / 1000   [mL/min]
  A = π(d/2)²  — tube bore cross-section
  L = R_rotor · θ_arc  — tube length wrapped around the rotor track
  (every point on the wrapped arc is fully occluded once per
   revolution, so Q depends on RPM and geometry, not on n)

What does depend on the roller count is smoothness: with only one occluding point in contact at a time, flow pulses once per roller pass. More rollers overlap their occlusion zones, so the ripple shrinks roughly like 1/n — this sim models that trend as an illustrative ripple ≈ k/n curve, not a manufacturer's exact spec.

Rotor speed — sets revolutions per minute and therefore average throughput.
Rollers — more rollers smooth the pulsation but don't change average flow.
Tube diameter — sets bore area A; flow scales with d².
Occlusion — below 100% the tube isn't fully pinched shut, so fluid slips backward past the roller (leakage/back-pressure loss); above 100% the tube is over-compressed, which improves sealing but accelerates tube wear in a real pump.

Real-world relevance: this is the exact mechanism inside IV infusion pumps, dialysis machines, peristaltic dosing pumps and lab fluid handlers — chosen because the fluid never touches a seal, valve or bearing, so it stays sterile and the pump can't leak at the drive.

Fluid slug Occluding roller

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