What is it?
Counter pressure or Isobaric filling is a technology used by all large scale beverage producers to package liquids. It is the preferred method because it gives the operator complete control over the atmosphere inside the can during the fill process.
The method involves a series of valve operations and pressurization that allows faster filling while simultaneously preventing oxygen absorption and product loss. The method is less commonly used by smaller craft beverage producers mostly because the technology was not previously available for small scale production. Now there are a few equipment manufacturers that have successfully scaled down the technology and made it available for craft beverage producers at an affordable price.
The alternative to counter pressure filling is gravity filling. Although gravity filling has several disadvantages compared to counter pressure, it is commonly used in small craft beverage production due to its availability. Gravity fillers are supplied directly from the brite tank and rely on head pressure and liquid temperature to control fills. By using a gravity filler, the operator loses control over fill levels and product loss because liquid is exposed to the atmosphere during the entire fill process. Foaming becomes difficult to control causing unnecessary overflow and oxygen is absorbed as liquid is piped into cans. Oxygen absorption adversely affects aroma, flavor, color, nutrient retention, and shelf stability of packaged beverages. To better understand how counterpressure works and its advantages, we thought we would break it down into a step by step process.
How it works
Liquid is pumped from the brite tank into a pressurized bowl or tank.
Cans move under fill heads.
Fill heads lower onto cans and seal from outside air.
Cans are purged of ambient air by flushing with carbon dioxide(CO2). CO2 is 3 times heavier than oxygen causing it to sink to the bottom of the can and force the oxygen up and out a vent. (Multiple purge cycles can be performed at the user’s discretion to eliminate any residual oxygen)
CO2 valve opens to pressurize cans to equal the tank pressure. The pressure of the gas above the liquid is important because the solubility of a gas in liquid is directly proportional to the pressure of the gas above the liquid. By keeping the pressure the same throughout the fill process, carbonation levels are maintained.
Fill valve opens and liquid flows into cans. A vent valve opens simultaneously to maintain a constant pressure as liquid level rises.
When the can is full, the snift valve slowly releases pressure until the pressure inside the can is equal with atmospheric pressure. The slow release of pressure helps control foaming as CO2 breaks out of solution (similar to opening a bottle of soda).
Cans move from under the fill head and continue to the seamer.
Why you should care
Counter pressure filling offers several advantages over gravity filling.
First, by equalizing the pressure from tank to can, cans can be filled faster with little to no foaming.
Second, carbonation levels are maintained from the brite tank to filled cans. By keeping liquid under pressure throughout the fill process, CO2 is kept in solution for a beverage that tastes the way you intended.
Third, counter pressure fillers are ideal for filling widget cans(for nitrogen-infused beverages) because there is no fill tube that interferes with the widget. Nitrogenating beverages is becoming increasingly common because it can improve flavor profile, mimic sweetness without adding sugar, and add a creamy finish to achieve a unique beverage. Guinness was the original nitrogenated beverage, but now coffees, teas, cocktails and juices are trying it with much success.
Fourth, oxygen absorption is prevented by sealing cans from the atmosphere and purging cans with a product stable gas before filling. Oxygen is a beverage’s worst enemy. Evidence of oxidation has been described as a stale, leathery, cardboard-like, or vinegary flavor or aroma. Oxidation not only affects taste, but also reduces shelf life and nutrient retention of a beverage. It is crucial for maintaining quality to mitigate oxygen absorption during the packaging process.
Finally, the snift feature allows pressure to release slowly for control over foam cap formation and reduced product loss as compared with gravity fillers.
Although counter pressure fillers can have a higher cost of entry, the benefits quickly outweigh the costs. You will not only preserve the intended flavor and aroma of your beverage, you will reduce product loss from overfilling and extend shelf life for wider distribution. Maintain quality control of your beverage from the supply tank until the canned beverage touches your customers lips with a counter pressure filler.
CODI Manufacturing is ready to help your beverage company can your creations. Contact our sales team at sales@codimfg.com to learn more about our full lineup of canning system equipment. We not only offer counter pressure filling technology on all of our filling machines, but we can also provide you with depalletizers, twist rinses, conveying and packout equipment.