How Does A Gravity Filler Work?

Gravity filling as the name implies uses gravity to complete the filling. Gravity filling machines allow packagers to fill the same volume of product into each bottle using the time-based filling principle. That's why it's also called a time gravity filling machine.

A gravity filler has a hopper placed up above a set of nozzles, which is then filled with the liquid to be bottled. Once the bottles are placed below the nozzles, the nozzle valves can open, and gravity works to draw the product down. The valve is timed to shut again after a precise amount of product has flowed into the containers, and then new containers can be set underneath the valves so the process can begin again.

Gravity Filler Working Principle

Thin liquids with no particles and bulk density/flow characteristics do not change.

The product bulk supply is pumped into a holding tank above a set of pneumatically operated valves. Each valve is independently timed by the filler’s master computer so that precise amounts of liquid will flow by gravity into the container. Gravity fillers built with bottom up fill capability can handle a wide range of flowable liquids including foamy products.

Gravity Filler Working Principle
Gravity Filler Working Principle

This type of filler is best suited for liquids with very thin viscosities that do not change with ambient temperature or with batch variation. This machine is also suited for applications where recirculation of the liquid in the fluid path is not desirable. Although this type of filler is used predominantly on products that do not foam, foam may be limited and controlled by subsurface/bottom-up-fill capability.


Water, solvents, alcohol, specialty chemicals, paint, inks, corrosive chemicals i.e. acids and bleach.


This is the most economical type of filling machine for a limited range of applications. It is especially well suited for corrosive chemicals.

The Best Liquids for This Method

These machines work best with low to medium viscosity or frothy liquids, such as water rather than mayonnaise. The product also should be free of any chunks or particles that could clog the nozzle, and it should have a uniform consistency throughout. The fill is volumetric based on time, with thicker liquids requiring a slightly longer fill time than the same volume of low viscosity liquids. The same volume of product will be dispensed each time.

This machine can be found in industries that include food and beverage, specialty chemical and cosmetics and personal care, provided the product is free-flowing and has a low viscosity. Most recently, many manufacturers have been using the gravity filling process to meet the high demand for hand sanitizer. Because hand sanitizer is flammable, the filler has to be customized with explosion-proof controls, and you can turn to our experts to guide you through the process.

Given the right set of conditions, gravity filling can be a good choice for a company looking for an economical and simple automatic process.

Automation of Gravity Filling

Finding the right level of automation depends on knowing which balance of speed and cost is best for your company. Unlike manual filling machines, which are used by a single operator to fill one container at a time, or semi-automatic filling machines that still require some manual operation, automatic filling machines like automatic gravity fillers are the best choice for large-scale companies with high production requirements. They take up the most space, are usually connected to conveyance systems, and require the least manual operation. VKPAK offers only fully automatic gravity filling machines.

Automatic Gravity Filling Machine

Automatic Gravity Filling Machine

Introduction This Filling Machine is gravity type filling machine which is suitable for filling thin fluid. The machine is made by in-line structure , filling head quantity can be custom-made according to different production capacity such as 6/8/10/12/16 /20 heads. The filling volume is controlled by filling time,...

VKPAK's gravity fillers provide volumetric time based filling solutions. An elevated tank on this bottle filler holds product until containers are in place under the fill nozzles. The fill tubes or nozzles then open and release product for a pre-set amount of time. Each fill head can be individually timed to allow for an accurate volumetric fill for each bottle. Gravity filling machines are best suited for free-flowing, low viscosity products like water and ink. Special nozzles for gravity fillers can also be used help prevent drips and control foaming with some products.

When working out which system best fits your budget, factor in the level of growth you are expecting over the next few years so the equipment you purchase today will continue to meet your production demands over time. The number of containers you can fill per hour depends on the viscosity of your product, the volume of your containers, and the number of fill heads used. When you have taken these variables into account, you can better project the cost savings of automation based on your own specific situation.

Ease of Use Gravity Filler

VKPAK fillers are made in the China. Our machines are designed to accommodate future upgrades, and all purchases are backed by our guarantee of quality and commitment to service. Some of the features of our gravity fillers include:

  • PLC (programmable logic controller) that brings the power of “smart” computers to a rugged industrial environment
  • User friendly touch screen HMI (human machine interface), through which you can adjust and control the speed and volume of fill
  • 6 to 20 fill heads available
  • Adjustable throttling valve on each fill head
  • A “no bottle/no fill” sensor to prevent loss and spills
  • Bottle back-up sensor that delays filler operation until any jam is cleared
  • Emergency stop for safety
  • Bottle counter
  • Tool-free adjustment, and more

While gravity filling machines can use a number of different nozzles, generally speaking the nozzles will open for a pre-set amount of time to allow product to flow from a tank into the waiting bottles or containers. On most machines, the fill time for each individual head or nozzle can be adjusted to allow for greater accuracy. Times can also be set to fractions of a second to also improve volumetric accuracy. Once the pre-determined time has been reached, the nozzles will cut off the flow of product. For semi-automatic machinery, simple operator activated switches are used to activate the cycle, while automatic machinery will use a PLC to achieve the same.

The choice to use a fill to level system or a fill by volume system will always depend on the characteristics of the unique project at hand. For packagers using clear containers, the trend is toward the overflow principle, allowing for an increase in shelf appeal and aesthetic value as a result of the level fills. For packager not using opaque containers, the gravity filler may offer a better alternative, especially when consistent volumes are important to the industry. But even exceptions to these rules may apply where containers or product themselves are unique. The best advice for a new packager is to not only know, but understand, the different options that are available for packaging your own unique product before selecting any packaging machinery.

Gravity Filler vs. Overflow Filler - Two Ways to Fill Free-Flowing Products

When looking for a filling machine for free-flowing products, a packager will likely come across a variety of different liquid fillers. Two of the most popular for low viscosity liquids are the gravity filler and the overflow filling machine. While handling the same product types, each machine offers a unique way of completing the fill.

Gravity filling machines offer a simple way to achieve an accurate volumetric fill. Product is held in a tank above the fill heads and, as the name suggests, gravity is used to move product into the waiting bottles. Valves will open and close according to pre-set times during which liquid will be released to allow each bottle to reach the desired volume. On VKPAK machines, the fill time (or time that the valve is open to allow product in) can be set for each individual head, allowing for added accuracy.

The overflow filler allows an alternative to a volumetric fill by filling each container to the same level, even if the internal volume of the bottles is slightly different. This type of fill is ideal for clear or nearly clear containers, allowing for a clean, aesthetically pleasing look when the product reaches the shelf. The overflow filler uses a unique filling nozzle that seals over the container opening. Product is then released into the container and will "overflow" back to the holding tank through a second port on the overflow nozzle when the desired level is reached. The recirculation of liquid also helps to reduce product waste.

While other filling machines may be used for free-flowing or low viscosity products, the gravity and overflow options will probably be seen more than any other fill principle. Automatic machinery uses an indexing system and a PLC to move bottles in and out of the fill area without the assistance of an operator for each cycle.

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