peristaltic pump (Peristaltic pump)

A Peristaltic Pump moves fluid by rhythmically squeezing a flexible hose or tube against a curved track using rotating rollers or shoes. The compressed section of tube creates a moving pocket of fluid that travels with the rotation, while the wetted tube prevents any contact between the pumped fluid and the pump mechanism itself. This contact-free design is the defining advantage of peristaltic pumps: there are no shaft seals to leak, no valves to clog, no impellers to wear out from contact with the fluid, and the only consumable is the tube itself. The principle is borrowed from biology — the same mechanism propels food through human intestines, hence 'peristaltic.'

Peristaltic pumps fall into two scales. Low-flow precision peristaltic pumps (Watson-Marlow 120, Cole-Parmer Masterflex) deliver 0.001–500 mL per minute with dosing accuracy of plus-minus 0.5–1%, used for chemical metering, laboratory analysis, and pharmaceutical filling. Industrial hose pumps (Watson-Marlow Bredel SPX, Verderflex Dura) deliver 1–50 m3 per hour at pressures up to 16 bar, used for slurry transfer, polymer dosing, mineral processing, and food handling. For Indian CBG and recycling plants, peristaltic pumps are essential for polymer dosing in dewatering centrifuges (accuracy of plus-minus 1% directly affects cake dryness and polymer cost), antifoam dosing in digesters (small volumes, intermittent), chemical metering of caustic and acid for pH control, and sludge transfer in small dewatering trains.

The trade-offs that drive peristaltic pump selection are clear. Advantages: no contamination of the fluid by pump components, ability to handle corrosive or shear-sensitive fluids without special metallurgy, accurate metering at variable speed, dry-run tolerance (the pump cannot be damaged by lack of fluid), and reversible flow simply by reversing the motor. Disadvantages: hose is the only consumable but replacement frequency is high (typical hose life is 1,000–4,000 hours for industrial models, 500–2,000 hours for precision models), pressure limitation (above 16 bar requires specialised hose pumps), pulsating flow that may need a pulsation dampener for sensitive applications, and capital cost roughly 1.5–2x higher than equivalent positive displacement pumps. Capital cost in Indian market: Rs 50,000–1.5 lakh for a precision dosing pump, Rs 3–10 lakh for an industrial hose pump rated 5–20 m3/hr. Hose replacement cost is Rs 8,000–30,000 per hose, typically replaced once or twice per year. The total cost of ownership analysis usually favours peristaltic over diaphragm metering for polymer dosing because of better accuracy and the absence of valve clogging issues that plague diaphragm pumps on slurries.