Why Are Pump and Piston Fillers Better Choices for High Viscosity Products?

At Liquid Packaging Solutions, four different filler types make up a majority of the filling equipment manufactured at the LaPorte, Indiana plant. When dealing with packaging projects involving thin, free-flowing liquids, LPS representatives will typically discuss overflow and gravity filling machines. For thicker, more viscous products, piston and pump fillers will be the main topic of conversation. While there are exceptions, these machines usually fit into these two categories. But why to piston and pump fillers work better for viscous products?

To explain, let's briefly look at the two machines that handle the more free-flowing products. Gravity filling machines, as the name suggests, uses the force of gravity to complete a fill. A simple gravity filler will include a tank that sits over the fill heads. When the heads are activated, ball valves or other simple valves will open, allowing the product to flow from the tank and into the waiting containers. No other force is used to make the product flow. For this reason, slow flowing or thick products would take extra time to complete the fill, making the gravity filler a poor choice for thicker products.

Overflow filling machines, also often used for free-flowing products, use a special nozzle that allows bottles to be filled to a specific level, rather than by a pre-set volume. An overflow filler will use a pump to push product through the nozzles. When the desired fill level has been reached, liquid flows through a return port on the nozzle back into a holding tank - basically recirculating to be used again. While the pump can push product into the bottles, thicker products may cause issues in trying to get the liquid to recirculate. From long fill times to clogged return ports, overflow fillers simply work better with thin to medium viscosity products.

Piston and pump fillers, however, provide two ways to achieve accurate volumetric fills for high viscosity products without the issue of recirculation. Pump fillers provide an extra push by using a single pump for each fill head on the bottle filling machine. The pumps provide the extra push to quickly move thicker liquids through the product pathway and into the waiting bottles or containers. Furthermore, the pump used can be matched to the product to ensure consistent, reliable and efficient fills for each cycle run.

Piston filling machines will pull product into an empty cylinder to be pushed out by the piston with each cycle run. Like the pumps, the piston provides a little extra push to move thick products reliably and consistently while allowing for highly accurate volumetric fills. The extra push from pumps or pistons is what makes these two filling machines ideal for thick, highly viscous liquids.

As noted above, there are exceptions to the general rule, and the given filling machine for any project will depend not only on the product or products being packaged, but also on a number of other factors including space, automation, demand and more. To learn more about any of the filling machines manufactured by LPS, contact a Packaging Specialist today at 1-219-393-3600.