In counter-pressure (or isobarometric) filling, product flows from a pressurized tank into a pressurized can, either via hydrostatic pressure or as controlled by a pump. While this method can require more knowledge of filling technology and packaging, as well as a slightly higher investment than open-air filling, it also allows for a greater flexibility in product range, from still to high carbonation products (up to 4.1 Vols of CO2), and is the preferred method for high production environments. Working with a supplier who understands counter-pressure technology is critical.
Counter-pressure filling also offers precise control over production variables by filling into a purged, sealed container, using easily-adjustable machine parameters (e.g., purge length, purge cycles, etc.), and is less impacted by temperature variations. CO2 loss and DO pickup are minimized.
Filling Basics
Counter-pressure filling allows for the filling of highly-carbonated beverages (in excess of 2.7 Vols of CO2), and is the industry standard for high-speed rotary filling, in addition to still and lower carbonation products. Equivalent pressure in the can (P1) and product tank (P2) prevents breakout. The process is a gently, gravity-only fill, with consistent head pressure, and the tank to fill valve distance does not change, regardless of container size. The filling process follows these steps:
1. The can is pre-loaded under the fill head
2. Fill head valve seals to the can
3. CO2 is flushed
4. The can is pressurized and filling begins
5. Filling ends
6. First pressure relief/pause
7. Second pressure relief/pause (optional)
8. Can is released
9.Can exits