Filler Identification and Selection for Liquid Foods

November 2019


Fillers in the food industry are devices that are used to accurately and cleanly place a specified amount of product into a container. The objectives of this fact sheet are to describe the types of fillers available for liquid food products and provide selection criterion for the best alternative.

National Institute of Standards and Technology

The National Institute of Standards and Technology (NIST, 2019) publishes the official guide for testing the net contents of packaged products sold in the United States (Available at: Enforcement organizations follow the NIST standard for label compliance of net contents. Food manufacturers should be aware of the testing methods and pack products accordingly. Agencies responsible for packaging regulations include: Alcohol and Tobacco Tax and Trade Bureau, FDA, local weights and measures, state and local weight and measures, and U.S. Department of Agriculture Food Safety and Inspection Service.

National Institute of Standards and Technology

Types of Fillers Available

Liquid fillers for foods are available from a number of manufacturers in a variety of designs. Most fillers are primarily constructed of stainless steel, plastics and elastomeric materials. Table 1 lists broad categories of filler designs that are popular.

Table 1. Popular filler types for liquid food products.

Popular filler types for liquid food products.

Criterion for Filling Liquid Foods

Table 2 lists some of the criterion that may be considered when selecting a filler for liquid foods. To make the most of the criterion, the user can assign a numerical weight to each of the criterion that is deemed important (e.g. weight from 1 to 10; where price might be assigned a weight of “10,” most important criterion, and enclosures a weight of “2,” much less important criterion). Next the user may score each filler choice on the important criterion, according to their judgment (e.g. price of filler A scores “1,” lowest value and price of filler B scores “5,” mid-range value). Multiply the assigned weight by the score for each criterion to compute the weighted score for each criterion. Sum the total of the weighted scores. The filler with the highest sum of weighted scores is selected for purchase. A shortened example of an evaluation of alternative fillers using weighted scores is shown in Table 3. Based on the overall weighted score in Table 3, filler alternative “A” should be selected over “B.”

Table 2. Criterion for selecting a liquid food filler, incomplete list in alphabetical order.

Criterion for selecting a liquid food filler, incomplete list in alphabetical order.

Table 3. Abbreviated example of an evaluation of alternative fillers “A” and “B” by weighted score.

Abbreviated example of an evaluation of alternative fillers “A” and “B” by weighted score.

Sources for locating filling equipment are available online. Examples include:,, and

Considerations for Glass Containers

Glass containers are prone to breakage, and glass pieces are hazardous and regarded as an adulterant. Detection of broken, cracked or chipped glass during filling operations should trigger a sequence of corrective actions. Corrective actions might include: clearing of broken containers and glass pieces from the production line, repair or adjustment of machine elements and product holds for inspection. Line speeds for glass containers may be limited to reduce handling issues and consequential breaks. Fillers with nozzles that do not contact, or minimally contact, the glass surface may be selected to reduce opportunity for glass chipping and breakage.

Considerations for Plastic Containers

Rigid plastic containers may deform easily when handled, especially if they are filled with hot product. Improved plastic formulations and increased wall thickness may be required to fill hot products. Some plastic containers have reinforced neck areas and flanges, or other features that facilitate handling during filling and capping for properly equipped machines. Inert gas (e.g. N2) may be dosed into the headspace of filled containers to increase internal pressure and decrease container paneling. Non-rigid plastic containers (pouches) are normally handled by their spout or neck area.


Product safety is impacted by filler design. Fillers should protect the product from exposure to outside contaminants. Protection from contaminants might include the body of the filler, covers, shrouding, and filtered air or inert gas blankets. Fillers must be cleanable (inside and out), to prevent accumulation and growth of unwanted organisms and biofilms. A viable cleaning and sanitation plan must be prepared for all product contact surfaces.

Human safety is integral to filler design. Dangerous conditions should be eliminated in preference to safeguarding. Pinch points, rotating shafts, belts, gears and components must be guarded. Hot surfaces should be inaccessible or protected from human contact. Machine adjustments undertaken during operations (such as fill cycle speed, air pressure and conveyor speed) must be accomplished outside of the guarded or danger areas. Stairs, platforms and ladders (if supplied) must be designed to regulatory specifications. Safety interlocks, emergency stop and lock-out-tag-out features must be effective and straightforward to use. Noise level of the machinery should be minimized. Operator ergonomics need to be considered (height, reach and dexterity) for controls, change parts, maintenance and cleanup. 


Filling operations are at the heart of a liquid food processing line. A wide range of filler types and options are available from a large number of manufacturers and suppliers. Identification and selection of the best filler is an important step in the design of a successful processing line. A filler type can be identified based on the descriptions in Table 1. Suitability of a given filler, installed in a specific facility, may be assessing by applying criteria listed in Table 2, considering the unique product(s) and container(s) intended for filling. 

Gravity overflow rotary filler for syrup.

Figure 1. Gravity overflow rotary filler for syrup.

Pump rotary filler for dairy products.

Figure 2. Pump rotary filler for dairy products.

Piston filler with manual container handling.

Figure 3. Piston filler with manual container handling.


NIST. 2019. Handbook 133-2019, Checking the Net Contents of Packaged Goods. Available at: Accessed September 17, 2019.

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