Knowledge centre · Accuracy
Accuracy is not a single number printed on a datasheet. It is the result of a metering principle, a mechanical tolerance and a set of production variables that either hold or drift.
A stated accuracy of ±0.5% with an error of ≤1 g applies to pure liquids and uniform products; for particle-containing, high-viscosity or non-uniform products, measured accuracy is ±1 g–±2 g depending on product state, particle size and density uniformity. Both describe deviation from the target dose under defined conditions. Two things matter when you read such a figure: the conditions (product, temperature, container) and the sampling (how many consecutive fills were weighed, and over what period). A figure measured on a stable product in a test bay is a starting point; the question for a buyer is what it does in the eighth hour of a shift.
A servo-driven rotor pump removes the first and fourth of these mechanically: displacement is controlled by rotation, and there is no piston seal to wear. Viscosity and particle effects remain — but they are managed by configuration rather than by re-adjusting the machine.
| Variable | Symptom when uncontrolled | Control |
|---|---|---|
| Product temperature | Weight drifts during the shift | Upstream temperature control; heated hopper |
| Entrained air | Random light fills | Degassing; agitated hopper; gentle transfer |
| Nozzle/container fit | Spillage, apparent underfill | Filling station built to the actual container |
| Line pressure and supply | Inconsistent refill of the hopper | Level control and consistent feed |
| Check-weighing | Drift goes unnoticed | Statistical check-weighing with feedback to the servo |
Buy accuracy as a system, not as a component: metering principle + filling valve matched to the product + container-specific filling station + a check-weighing routine. Where those four are present, the published accuracy — ±0.5% for pure liquids, ±1 g–±2 g measured for particle-containing or high-viscosity products — is a working figure rather than a laboratory one.
Grounton Pak publishes exactly this detail — ±0.5% (error ≤1 g) for pure liquids and measured ±1 g–±2 g for particle-containing, high-viscosity or non-uniform products — with the conditions and sampling method stated, so the figure is checkable at your acceptance test.
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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