Filling a bottle is a simple process. The methods are based on ancient principles such as gravity and pumping. The hard part is measuring when a bottle is full and stopping the fill. Since liquids, unlike dry products, are usually sold by volume rather than weight, most liquid fillers have shut off mechanisms that measure volume. This can be as simple as an overflow that works like the overflow on a bathtub to more sophisticated servo drives and air sensor level detectors.
Vacuum fillers have a long and storied history. Companies such as US Bottlers and Horix have been producing them since the early Twentieth Century. 30 years ago, they were the most common type of liquid filler in packaging plants.
A vacuum filler inserts a nozzle into a bottle and seals the bottle airtight with a gasket. The nozzle contains 3 passages: one is the supply from liquid product tank, one is an overflow back to the product tank and the third is a vacuum line. As soon as the airtight seal is created, the vacuum line sucks all the air out of the bottle and liquid from the product tank pours in to fill the vacuum. When the level of liquid in the bottle gets above a certain height, it begins spilling into the overflow line which takes the excess back to the tank. Then the nozzle is withdrawn, the vacuum is broken and the liquid immediately stops flowing.
Vacuum fillers are a very efficient method for filling liquids except they have one major limitation. They require a rigid container that can withstand vacuum, in other words, a glass bottle. When the industry went over to plastic bottles in the 1970’s and 80’s, it spelled the death knell for the vacuum filler. Very few are produced anymore. However, there are still a lot of them on the used market and they sell at a discount to pressure fillers. If you are filling glass bottles with liquid, a vacuum filler might be the cheapest way to go.
Pressure Fillers are similar to vacuum fillers except that the liquid is pushed into the bottle under pressure. These are probably the most common fillers today. Fillers by many manufacturers, such as Horix, MRM-Elgin, Biner Ellison, Cemac and US Bottlers are available. The nozzel is slightly different from a vacuum filler. The bottom is sealed until it is fully inserted into the bottle, at which time a spring loaded valve opens up and allows the liquid to pour into the bottle. There is an overflow passage just like with a vacuum filler. The pressure is usually provided by a pump but it can also be provided by placing the supply tank above the filler and letting gravity take over. Gravity fillers are, for obvious reasons, not as fast as fillers where the pressure is provided by a pump but they are often used in the wine and liquor industries because they are gentler and a vacuum cannot be used because it would tend to evaporate the alcohol.
Pumps for pressure fillers are normally centrifugal type but can also be positive displacement. These fillers can be configured in a straight line or rotary layout. Rotary fillers are more expensive and are generally built for higher speed operations. In a rotary filler, the lowering and raising of the nozzles is done with a cam while, in a straight line fillers, it is normally done with pneumatic pistons controlled by an electronic timer.
A variant of the Pressure Filler is the Counter Pressure Filler which is used in the beer and soft drink industries. In a counter pressure filler, CO2 is injected in the bottle prior to filling. The CO2 pushes out all the air and keeps the beverage from decarbonating.
These are also called positive displacement fillers. Herman Laub of San Gabriel, California was one of the developers of this type of filler. Laub Engineering, founded in 1950, (Now called Laub Hunt Packaging) is still a major manufacturer. This type of filler uses a volumentric piston pump to measure out the volume of the liquid that is to be filled. The positive displacement filler differs from a piston filler in that there is a hose that runs to a check valve that fills the container.
Another important company in the development of volumetric liquid fillers is Filamatic, founded by Sidney Rosen of Baltimore, MD in the early 1950’s. The Filamatic AB and DAB series fillers are probably the most popular fillers of this type. Filamatic produces straight line automatic fillers while Laub produces rotary fillers. Also, the Cozzoli company of Somerset, NJ has been a significant developer of inline pump fillers.
Volumetric fillers are more accurate than other types of liquid fillers but also more expensive. Therefore, they are used largely for small dose filling jobs where accuracy is of paramount importance.
Level Sensing Fillers, such as the Horix Hytamatic® filler have an air sensor which calculates when the bottle is full based on air that escapes from the container. Time Pressure fillers, such as the Versa-Fil®, calculate the volume of the fill by filling under pressure for a certain amount of time. Liquid Scale Fillers, such as Crandall drum fillers, fill by gross weight. Other companies, such as Epak, produce net weight fillers. Servo Fillers, such as manufactured by Oden, use the number of turns of a gear pump to calculate the volume of fill. These will become more and more common in the future.
There are also fillers that operate on the siphon principle. These are usually semi-automatic and have about 6 spouts. They are popular in home winemaking industry and other low end applications.