Knowledge centre · Product properties
Viscosity decides which pump can move your product at all. A little measurement discipline at the start saves the biggest problems at the end.
Viscosity is resistance to flow — how thick a product is at a given temperature. It is the first property we ask about, because it decides the pump family: thin liquids (milk, beverages, edible oil) suit gear pump fillers; creams, gels and sauces suit rotor pump fillers; and thick pastes and fillings with particles sit firmly in the rotor pump range up to ≈300,000 cSt.
| Method | What you get | When it helps |
|---|---|---|
| Laboratory viscometer (Brookfield-type) | Viscosity in cSt or cP at a set temperature | The number your supplier needs for pump sizing |
| Rotational / spindle test | Viscosity curve across shear rates | Thixotropic or shear-thinning products |
| Simple flow cup (e.g. Ford cup) | Seconds to empty a calibrated cup | Quick plant-side comparison of batches |
If you do not have a viscometer, a practical shortcut is to describe the product honestly: "flows like honey", "like toothpaste", "holds a shape when scooped". This is enough for a first pump recommendation, and a filling test will confirm it.
Viscosity at filling temperature is the first field on Grounton Pak's configuration sheet — and the reason one metering-grade rotor pump family can cover products from 50 cSt to 300,000 cSt.
Viscosity falls as temperature rises — sometimes dramatically. Hot-fill sauces can drop several viscosity classes between ambient and filling temperature. Always state viscosity at the actual filling temperature, not at storage temperature. If your process heats or cools the product before filling, say so in the equipment enquiry; it changes pump sizing, nozzle design and accuracy expectations.
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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