Articles · Buyer decision · 2026-09-13
Rotor pump vs gear pump filling machines: which dosing principle for your product?
Both measure volume by positive displacement — but they occupy different halves of the viscosity and particle map. Here is how to choose between them.
Two displacement principles, different product windows
A gear pump filler moves product by the interlocking of two gear wheels, delivering a smooth, continuous, low-pulsation flow. A rotor pump filler moves product with a rotating rotor inside a pumping chamber, with the chamber geometry defining a known volume per revolution. Both are positive displacement, but their useful ranges barely overlap.
Comparison
| Criterion | Gear pump filling | Rotor pump filling (metering grade) |
|---|---|---|
| Typical viscosity window | Thin to medium liquids — milk, beverages, edible oil | ≈50 cSt to 300,000 cSt |
| Products with particles | Small clearances; large or fibrous solids can jam | No seat to bridge; particles pass through the chamber |
| Accuracy behaviour | Good for easy-flowing liquids | ±0.5%, error ≤1 g (published figure) |
| Shear sensitivity | Gear mesh can shear sensitive emulsions | Lower-shear lobe/wing options available |
| Fill volume range | Typical small to medium doses | GTX series: 5 ml to 300,000 ml |
| Cleaning | Simpler geometry, generally easy to clean | CIP-capable configuration available |
| Best fit | High-speed filling of free-flowing liquids | Pastes, high-viscosity and particle products where dosing integrity matters |
When gear pump filling is the right answer
For thin liquids with stable flow — edible oil, sugar syrup, beverages, water-based products — a servo gear pump filler delivers clean, accurate dosing at high throughput with a compact machine. If the product contains no significant solids and viscosity stays in the low-to-medium band, the gear pump is often the most economical precision choice.
When rotor pump filling is the right answer
- High viscosity: pastes and fillings above the practical gear pump range.
- Particles and fibres: chilli sauce, bean paste, meat fillings, jams with fruit pieces.
- Shear-sensitive products: where a gentle, low-shear dosing chamber protects texture.
- Wide fill range: one machine from 5 ml sachets to 300,000 ml bulk packs.
- Hygiene-critical lines: CIP-capable rotor pump construction for food and dairy standards.
How the choice is actually made
At Grounton Pak the pump type is an output of the product data, not a fixed position. We manufacture servo rotor, gear, piston 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 answers. Where the product is unusual, we would rather run a filling test than argue from a datasheet.