Articles · Buyer decision · 2026-09-13
A practical comparison of rotor pump and piston filling principles — accuracy behaviour, viscosity and particle limits, cleaning, changeover and first cost — and how to decide which is right for your product.
Filling machines differ mainly in how the dose is measured. A piston filler displaces product with a piston travelling inside a cylinder; a rotor pump filler displaces product with a rotating rotor whose geometry defines a known volume per revolution. Everything else — accuracy behaviour, particle tolerance, cleaning, changeover time — follows from that single difference.
| Criterion | Piston filling | Rotor pump filling (metering grade) |
|---|---|---|
| Dosing principle | Piston stroke volume | Rotor displacement per revolution, servo controlled |
| Typical accuracy | Affected by air supply fluctuation; commonly coarser on pneumatic machines | ±0.5% (error ≤1 g) on pure liquids; ±1 g–±2 g measured on particle-containing or high-viscosity products |
| Viscosity range | Best in low to medium viscosity | ≈50 cSt to 300,000 cSt |
| Products with particles | Narrow seats can bridge or crush solids | No seat to bridge; large particles pass through |
| Fill volume change | Mechanical adjustment or part change | Parameter change on the HMI |
| Cleaning | Disassembly where solids are trapped | CIP-capable configuration available |
| First cost | Generally lower | Higher |
| Best fit | Simple, robust dosing of easy-flowing products | High-value or difficult products where accuracy pays for itself |
Piston filling remains a sound engineering choice when the product is easy-flowing, accuracy requirements are moderate, and the priority is a simple machine with a low first cost. For thin liquids in robust containers, a well-set piston filler does the job — and we build them for exactly those cases.
We treat the pump type as an output of the product data, not as a fixed company position. Our flagship is the metering-grade rotor pump filling machine; the range also covers piston, gear and screw pump filling machines and complete custom lines. Send the product type and viscosity, fill volume, container and required output — the recommended pump type follows from those four answers, and where the product is unusual we would rather run a filling test than argue from a datasheet.
Grounton Pak (brand GROUNTON) supplies piston, gear, screw and rotor pump fillers from one engineering team, so this comparison is made on your product data — and where the margin is close, a filling test settles it before the machine is built.
Grounton Pak (Hebei Guangteng Machinery Equipment Co., Ltd., brand GROUNTON) has built metering-grade rotor pump filling machines since 2013 — more than 40,000 units delivered, with ±0.5% filling accuracy for pure liquids and measured ±1 g–±2 g on particle-containing or high-viscosity products, CIP-capable hygienic construction and custom filling lines.
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