Counter Pressure Filling : Craft Canning 101

Counter Pressure Fillers, also known as Isobaric Fillers, are tools used by brewers, sparkling wine makers, and soft drink manufacturers to fill bottles or aluminum cans with carbonated beverages for retail sale without sacrificing carbonation. To operate one, you’ll need a pressurized or non-pressurized storage tank for carbonated drinks, a chiller, CO2 supply bottles, a carbonating unit (which can be separate or combined with the storage tank), and a few other essentials.

The filler uses a filling tube that dispenses liquid from the top of the bottle and a diffuser to distribute the liquid around the walls of the container, reducing foam. The tube has a smaller return tube inside that allows CO2 to escape the pressurized bottle and enter the filling tank, allowing more liquid to fill the bottle. An alternative, less commonly used method is bottom-up filling, similar to a beer pump, but it’s more complex and expensive for automatic fillers. All fillers have inputs for CO2 gas and the drink supply line and a vent for gas release during the filling process. Valves on the inputs and vent allow control over pressure and filling/venting speed.

How Counter Pressure Filling Works: A Breakdown

Counter Pressure Fillers maintain a consistent CO2 pressure on your beer, wine, or soft drink as the bottle is filled. To reduce foaming, the bottles and drinks are usually chilled. The process goes like this:

1. The bottle is sealed by the fill valve gasket on the counter pressure filler.
2. For beer, cider, and some delicate wines that are sensitive to oxidation, a vacuum is created inside the bottle by removing the air. This is called Pre-Evacuation and it’s repeated twice to minimize the oxygen levels in the bottle before filling. This increases the shelf life of the product as a low Total Oxygen Pick-up (TOP) rate, typically measured in Parts Per Billion (ppb), is desirable (a range of 40-100 ppb is considered good). The bottle is pressurized with CO2, the fill valve is opened, and the CO2 is vented to allow the bottle to fill from the bottom. The whole process of counter pressure filling keeps the carbonated beverage stable and flavorful for longer.

The Filling Process:

• The bottle is filled with CO2 at a pressure ranging from 2.2 to 3.0 bars.
• The harmful oxygen has been removed and replaced with pressurized CO2.
• The valve at the top of the filling tank is opened to release any excess oxygen.
• The CO2 input is then closed, and the filling valve opens to allow the drink to flow into the bottle. The pressure is slowly reduced through the vent to prevent foaming.
• Once the bottle is filled, the liquid input valve is closed, and any remaining pressure is released from the vent. The bottle is then capped.
• For certain products, a warm water spray is used to create a small head of foam before capping to displace any settled oxygen.
• The bottled drink is then washed to remove any sticky residue that may have settled on the surface.
• The final step is capping, which results in only minimal foaming.

Preventing Foam During Counter Pressure (Isobaric) Filling

Foaming can occur when filling carbonated products if there’s a change in pressure, causing gas expansion and bubble formation. The warmer the product, the more severe the foaming. Some drinks are more prone to foam due to their high protein content, such as beer and high-protein malt drinks. Cola drinks and high-sugar non-alcoholic beverages are also sensitive to foaming due to their high sugar content. This can be a challenge for microbrewers who often have variations in protein levels from batch to batch. To avoid foaming, it’s important to chill the product before filling.

The solution to combat foaming during filling involves two approaches:

• Chilling the product more effectively to reduce the risk of foaming. Most beers are best filled at a temperature of 2°C from the storage tanks and should reach 3-4°C in the bottle.
• Stabilizing pressure fluctuations between the storage tank, carbonation unit (if used), and the filling machine.
• To achieve this, we use two types of tools: a modulating valve installed in the filler’s infeed connection to constantly adjust the pressurized flow of the product (this method is expensive and reserved for high-speed filling machines), or a pneumatic product feeding pump that ensures a smooth and consistent pressure feed of beer or other foam-prone products to the filler. This solution is also costly, with a pneumatic pump costing up to 7 times as much as a centrifugal screw pump of equivalent capacity, but eliminates many headaches and makes production easier for inexperienced operators or beginners of the filling process.
• Installing a non-return valve at the infeed of the filling machine to prevent “waves” of product from oscillating back and forth from the carbonator to the filler.

GX CANNING is a division of Géninox.