Dispenser for liquid products
Volumetric and gravimetric dispensers for liquid products: operating principle, dosing accuracy, throughput and integration into a food line.
A dispenser measures out a set portion of liquid product and delivers it into a container. Its accuracy directly determines losses: underfilling causes complaints, overfilling is product given away for free. In this article we break down the two main types of dispensers, their accuracy, throughput and how to select a dispenser for a product.
Volumetric and gravimetric dispenser: what is the difference
All liquid product dispensers fall into two classes by the principle of measuring a portion. A volumetric dispenser measures out a fixed volume — by a piston cylinder, a measuring chamber or by valve opening time. It is simple, fast and inexpensive, but its accuracy depends on the product’s density and temperature: when the temperature changes, the volume stays the same but the mass changes.
A gravimetric dispenser measures a portion by weight — the container stands on a load cell, and the valve shuts when the set mass is reached. It is more accurate and independent of density but more expensive and slower, since it needs time for the weight to stabilise. The choice between them is always a compromise of accuracy, speed and price.
Where dispensers are used
On our projects dispensers are integrated into filling lines for various products:
- Oil and sauces — filling into bottles and jars, where portion stability matters.
- Marinades and brines — pouring into containers with vegetables, mushrooms, fish.
- Dairy products — filling yoghurts, sour cream, drinks.
- Viscous products — honey, condensed milk, pastes — here piston dispensers are needed.
- Chemical solutions — detergents, concentrates in non-food production.
The product type determines the design: viscous liquids need a heated piston, aggressive ones need AISI 316L stainless steel, foamy ones need a special filling nozzle shape that reduces foaming. We separately account for product temperature: hot filling of marinade or sauce needs heat-resistant seals and pipelines rated for 90–95 °C, while cold filling of dairy products runs in the 4–8 °C range, where material resistance to condensate matters.
Accuracy and throughput
Dispenser accuracy is expressed as a percentage of the nominal portion. Below are indicative characteristics of typical dispensers by operating principle.
| Dispenser type | Accuracy | Throughput | Optimal product |
|---|---|---|---|
| Volumetric piston | ±1.0–1.5% | 20–40 cycles/min | Viscous, pastes, sauces |
| Volumetric measuring chamber | ±1.5–2.0% | 30–60 cycles/min | Low-viscosity liquids |
| Volumetric flow-timed | ±2.0–3.0% | 40–80 cycles/min | Water, juices, marinades |
| Gravimetric load-cell | ±0.3–0.5% | 15–30 cycles/min | Expensive products, exact norms |
Engineer’s tip. If your product is expensive, we almost always recommend a gravimetric dispenser. The accuracy difference between ±2% and ±0.5% seems trivial, but on a flow of thousands of packs a day that one and a half percent of overfill is a tangible sum going into containers for free. A gravimetric dispenser pays back the price difference within a few months.
Integration of the dispenser into the line
A dispenser does not work on its own — it is part of a filling line. Before it a conveyor feeds empty containers, the dispenser stops them, fills them and releases them onward — to capping, labelling, packaging. The conveyor speed is coordinated with the dispenser cycle so there is neither downtime nor a jam.
For multi-stream lines we fit several dosing heads in parallel: throughput grows in proportion to the number of heads without loss of accuracy. All contact units are designed disassemblable for CIP cleaning. We make the dispenser as part of custom equipment for the customer’s specific product and container.
Typical operating mistakes
Most dosing problems arise not from a dispenser malfunction but from small setup details. The first and most common is ignoring product temperature. A volumetric dispenser calibrated on a cold product starts to underfill by mass after the product is heated, because warm liquid is less dense. We always confirm the temperature at which the product is actually filled and calibrate the dispenser to it.
The second mistake is the wrong filling nozzle shape for foamy products. If the stream falls from a height into an open container, it whips up foam that takes up volume and distorts the dose. The solution is submerged filling: the nozzle is lowered into the container and rises with the product level. The third mistake is worn piston seals: an unnoticed loss of tightness gradually shifts the dose, and the defect is found only at the batch control weighing. So we add dispenser seals to the planned maintenance schedule as a consumable.
Conclusion
A dispenser is a unit whose accuracy directly determines product losses. A volumetric dispenser wins on speed and price, a gravimetric one on accuracy and independence from density. The choice is dictated by the product type, its cost and the requirements for the norm. If you are designing a filling line — get in touch, and we will select a dispenser for your product and throughput. More on the topic under the tag dispenser.
