Fill-To-Level Versus Fill By Volume Machinery
A topic that we have covered before, but one that is always worth revisiting, is the difference between a filling machine that fills to a level and those that fill by the volume of the liquid. These different filling principles provide different benefits for packagers, but outside of those that are familiar with filling machines, the difference may not be immediately obvious.
There are a variety of different filling machines that use a volumetric fill principle. The first, and most simple, is the gravity filler, which holds product in a tank over the nozzles and uses the force of gravity to assist in the fill. Pump filling machines and piston fillers also use a volumetric principle when it comes to placing liquid in the bottles or containers. But rather than rely on gravity, the pumps or pistons will give an extra boost when moving the liquids, which makes these fillers better for higher viscosity products. Simply put, when filling by volume, the same amount or quantity of product will enter each container. But when bottles are manufactured, they may not all be created equally. In other words, each and every bottle may not be exactly the same, with slightly different interior volumes, though this will likely not be apparent when just eyeing the bottles. It may become noticeable, however, when product is added, in the form of inconsistent levels from bottle to bottle. Though rare, inconsistent fill levels can be an issue for some packagers, especially those with clear containers where the liquid is visible to the consumer.
Imagine a beverage sitting on the shelf in a grocery store, with the liquid level in each container reaching a different level. While the bottles may all contain the same amount of product, consumers may be wary for a number of reasons, ranging from tampering to feeling like they were being cheated if they had to take a bottle filled to a lower level. Packagers may work with their bottle manufacturer, or even change their bottle, to get better results. But another option is filling containers with the unique, fill-to-level overflow filling machine. The overflow filler uses a unique nozzle that allows product to enter a bottle until it reaches the desired fill level. Once that level is reached, a second opening in the nozzle allows product to "overflow" back to the holding tank, keeping the fill at the same level when the cycle is complete. Now, in contrast to the volumetric fillers, bottles will be filled to the same level, though volume may vary slightly in each container. Of course, the manufacture of containers may still be an issue, if there is great variance from bottle to bottle, but finding great variance is rare as well. Even for products in clear bottles that must meet a certain tolerance when it comes to volume, such as distilled spirits, the overflow filler can be an ideal solution. The overflow aspect of this liquid filler can also help to control foam, though very thick products can be an issue.
In many cases, either volumetric or fill-to-level principles will work for the same products. However, each offer their own benefits, and details of a packaging project, such as the container, the product itself, speed desired and other factors will help identify which of these solutions will work the best. For more information on any of the filling machines manufactured by Liquid Packaging Solutions, feel free to contact an LPS representative today.