How Does An Overflow Filler Work?

The overflow filling principle stands out for its ability to fill bottles to the same level, even if that results in slight variations in volume. For retail products packaged in clear containers, this visually-appealing evenness is an important way to appeal to your customers. Without this system, slight variations in the interior shape of your containers could make it look as though your products are filled unevenly, even when they are not. Your customers may reject a bottle that looks as though it contains less than the others, which could result in unsold units. Maintaining an even fill-line prevents this perception, while also looking more professional.

The obvious advantage of the fill-to-level system is a machine that allows products packaged in clear containers to have a consistent appearance when on the shelf. Items such as bottled water, distilled spirits, window cleaners and more, benefit in appearance and build consumer trust when each container appears filled to the same level with the same amount of product. In addition, the overflow filler is a great way to consistently and reliably fill products that foam. As products - think soap - foam in the bottle during the fill, the overflow basically allows liquid to continue to flow into, and overflow out of, the bottle until the foam is eliminated.

Overflow filling works best with thin to medium viscosity products, and this method can fill bottles at a fast rate. Any leftover product left in the filling tubes is pushed back into the storage tank to prevent waste.

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Overflow Filler Working Principle

Overflow Filler Working Principle
Overflow Filler Working Principle
This type of filler is best suited for liquids with low to medium viscosity.

The supply side (dark blue) of a two-part nozzle is used to pump product into the container. When the container fills up to the target fill height, the excess product and foam are forced out of the container (red arrows) via the return side to the original product source tank.


Sauces, syrups, light gels and shampoos, foamy cleansers and chemicals, water, and other non-carbonated aqueous beverages


High performance, easy to clean, easy to operate, expandable at low cost. Offers the greatest flexibility at the lowest cost.

Automatic Overflow Filling Machine

Automatic Overflow Filling Machine

Introduction The linear overflow defoaming liquid filling machine is suitable for filling liquids that are prone to foaming, and it is also suitable for liquids that do not foam. The filling liquid can not only prevent foam from overflowing, but also keep the liquid level consistent. It can...

Application Scenarios Of Overflow Filling Machine

When liquid products are lined up in transparent bottles on the shelves in a retail store, they make the best impression if the fill levels of each container are consistent all the way across. One obstacle to achieving this pleasing uniformity is that containers – especially ones made of glass – sometimes have irregular shapes on the inside. If the exact same quantity of product is put into irregular containers, the fill levels won’t match, and the containers will (incorrectly) appear to each have different amounts of product in them.

There are some cases where this would not be a cause for concern. For example, a vial holding a single dose of medicine must have the precise amount of content, no matter what it looks like. Another case is when the container is opaque enough that the fill line is invisible.

Maintaining uniform fill levels matter most for retail items where the customer is making a decision based in part on how the products look. A row of bottles of mouthwash with different fill levels can give the impression that the company is careless in its manufacturing, and the customer may decide to move down the aisle to select a different brand. A container with a noticeably low fill level may also be the last one left on the shelf, until finally the retailer has to return or discard it, wasting money for the manufacturer. Adjusting the actual volume by an almost imperceptible amount won’t affect the value a customer gets from the product, but it could have a big impact on sales.

The Best Liquids for Overflow Fillers

Overflow fillers are meant to be used with low to medium viscosity liquids and foamy liquids (non-carbonated). They can also process these same fluids with the addition of particulates that are 1/16” in size or smaller. Specific applications include personal care, cleaning chemicals, pharmaceutical, cosmetic, beverage and food.

Overflow filling has been used has been used to fill low viscosity liquids for many decades, if it’s used for the right product and a correct set up it will give you a very accurate fill

The overflow filler will give you the fill level by the depth off the return tube inside the container, once the product reaches these tube It will go through the tube instead of continuing to fill your container. If you reach the overflow tube in four seconds and leave it filling for more time the fill level in theory will be the same, keeping this in mind when you set-up an overflow machine will help you understand that you only need to fill for enough time so all the nozzles have overflown. All fill nozzles will not fill at the exact same rate and it won’t matter, if you leave the machine filling for enough time eventually all containers will fill and you will get an even fill.

There are many settings but you can have an overflow filler some machines Have the capability of filling at different speeds at different times, this is very useful specially on larger containers because you will be able to fill at very high speeds at the beginning and slow down at the end to avoid splashing, if you don’t have this option you will have to fill all the container at the highest speed on which the machine will not splash.

By far, the biggest limitation of an overflow liquid filler is not being able to fill thick products, or high viscosity products.

Overflow Filling Requirements For Bottles

When bottles are manufactured, an attempt is made to keep the process as consistent as possible for obvious reasons. Most packagers want each and every container to look similar to help boost shelf appeal and even small inconsistencies may not be identifiable using the naked eye. However, when liquids are added to bottles with slight variations in interior volume, the visible fill level can vary, even though the same amount of product is present in each container. The overflow filling machine is used to combat these inconsistencies in volume by filling each and every bottle to the same exact level, regardless of interior volume.
Overflow fillers achieve this level fill by using a unique nozzle that not only seals over the bottle opening, but allows product to flow back through the nozzle to the holding tank or reservoir, thus eliminating product waste as well. As the nozzle seals over the bottle, the fill port is opened, allowing product to enter the bottle. Once the product reaches the specified level in the container, controlled by using spacers on each of the fill heads, the product exits the bottle via the return port, "overflowing" out of the bottle and back into the tank or reservoir. This principle can be used for free-flowing products in containers both large and small, though great variations in size may require different nozzle sizes for efficiency purposes.

As noted above, the level fill can mean that the actual volume of product will vary from container to container. While this can be a concern to industries such as distilled spirits, pharmaceuticals and others with volume requirements, almost all industries will have a target volume along with an acceptable range. In most cases, the change in interior volume will be so slight that the danger of falling outside of the acceptable range is nearly non-existent. However, packagers with this concern will want to check with their bottle manufacturers to ensure that interior volume will not vary greatly and may want to (or even be required to) include some type of quality control check in their own packaging process.

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