This revision keeps the defining roller, tube and raceway topology while separating a declared geometric displacement reference from real calibrated pump performance.
Peristaltic Raceway Geometry Explorer
Choose tube bore, raceway centerline radius, rotor speed and roller count. The worksheet reports a declared 240-degree wrapped-path volume and its ideal geometric rate.
Equation Used
- The tube has a circular recovered bore of the selected inside diameter.
- The tube centerline follows a fixed 240-degree arc of radius R.
- One rotor revolution advances one wrapped-path volume in the ideal geometric reference.
- Rollers are equally spaced and rotate as one rigid rotor; roller count sets pass frequency, not the geometric volume per revolution.
- Pressure, tube elasticity, occlusion, slip, viscosity, pulsation, wear, chemistry and calibration are excluded.
Corrects roller double-counting by treating adjacent trapped segments as a partition of one declared wrapped path; real flow requires calibration.
Rollers move constrictions along a flexible tube
US patent 8118572 describes the basic mechanism: one or more rollers rotate along tubing in a raceway, and the moving constrictions propel fluid through the tube. The FDA likewise describes a roller compressing tubing and rolling along its length to squeeze fluid from one end to the other.
The animation shows equally spaced rollers on one rigid rotor pressing a declared 240-degree tube path. It illustrates topology, not tube deformation or contact stress.
An isolated flexible-tube fluid path
Watson-Marlow's operating documentation describes tube compression followed by elastic recovery. Specific suitability, accuracy, pressure, chemistry and service life depend on the selected pump head and tubing and must come from their validated data.
This worksheet does not recommend a pump or tube for medical, pharmaceutical, chemical or other service.
A declared geometric displacement reference
The recovered tube-bore area is multiplied by the declared 240-degree centerline path. Multiplying that ideal volume per revolution by rotor rpm gives an ideal geometric rate.
Roller count sets roller-pass frequency nN. It does not multiply displacement again because the adjacent trapped segments together partition the wrapped path.
A declared geometry example
For 6.4 mm ID tubing on a 70 mm centerline radius, the 240-degree wrapped path is about 293.2 mm and ideal displacement is about 9.433 mL/rev. At 60 rpm that geometric rate is about 565.96 mL/min. Three rollers make 180 passes per minute.
Geometry is not a delivered-flow rating
Real flow depends on occlusion, tube recovery, pressure, viscosity, slip, pulsation, tolerances and wear. A physical pump must be calibrated with its actual head, tubing, fluid and operating conditions.
The former manufacturer-specific accuracy, pressure, life, chemical-compatibility, speed-band, maintenance and pharmaceutical case-study claims are removed because this geometry model cannot support them.
Peristaltic-pump calculation questions
Why does roller count not multiply ideal volume per revolution?
Adjacent trapped segments partition the same wrapped tube path. Counting both every segment and every roller would double-count volume.
Does ideal geometric flow equal measured flow?
No. It is a reference that omits tube and fluid behavior.
Does this model specify occlusion or pressure?
No.
Can it select tubing for a chemical or medical application?
No.
Peristaltic-pump references
- US patent 8118572B2: roller constrictions, raceway tubing and flow dependence on angular velocity and trapped volume.
- Watson-Marlow Quantum 600 user manual: tube compression and recovery mechanism.
- US FDA 510(k) correspondence K200893: roller compression moving along tubing to propel fluid.
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