Dueling Filling Machines - Overflow vs. Gravity

Though we have discussed this issue before, it always returns as new people enter the packaging industry on a daily basis! While a number of different filling principles exist, two popular machines for thin to free flowing liquids are the overflow filler and the gravity filler. Though both bottle fillers can handle virtually the same products, each offers a different method of filling bottles. The two principles offered by these filling machines are a fill-to-level principle and a volumetric principle.

An overflow filler fills each and every bottle to the same level, regardless of slight variances in the internal volume of the bottles. While volumes may vary slightly, this principle for filling bottles can be ideal for packagers using clear or transparent bottles. Bottled water, salad dressings, other foods and beverages may all be packaged in either glass or plastic see-through containers. The overflow filler allows these products to reach the shelf with a consistent look, which adds to the aesthetic value of the product. In addition, such a fill keeps consumers from feeling cheated when one bottle appears to have more or less product even if the volume were the same! Overflow fillers use a special nozzle that creates a seal over the bottle opening and allows product to "overflow" back to a holding tank once the desired level is reached in the bottle.

On the other hand, some products require accurate volumetric fills. Gravity fillers, as the name suggests, use gravity to allow product to move from a raised tank to waiting bottles during a timed fill. Individually timed fills for each head on a gravity filling machine allow for even greater accuracy and help to ensure that the right amount of liquid is placed in each bottle. Gravity fillers can use a range of different nozzles, matched to the project, product and containers being used by the specific packager.

At Liquid Packaging Solutions, overflow fillers have seemingly gained in popularity over the years, though both bottle fillers are still popular products. One reason for the slight increase in the popularity of the overflow filler may stem from the production of bottles. As processes improve, the interior volume of bottles vary less and less, meaning that in a number of cases, the overflow filler can provide a pretty accurate volumetric fill as well, and often hit industry tolerances for volume where they exist.

To learn more about these or other filling machines manufactured by Liquid Packaging Solutions, visit the Filling Machinery section of the LPS website. Or if not sure which filling machine would be the best solution for your own project, call an LPS Packaging Specialist for a free consultation today!