How to Force Carbonate Beer with Carbon Dioxide

carbonate beer co2

What is Force Carbonation?

In home brewing, force carbonation is used to infuse or “force” carbon dioxide into your beer. Instead of waiting weeks for the yeast and sugar to naturally create the carbonation, you'll get it directly from a CO2 gas cylinder.

Force carbonation is considered the fastest carbonating process and results in less sediment and a quicker-clearing beer. This is why it is popular with home brewers.

In order to force carbonate beer here are two simple methods we've found. The only difference between them is time it takes.

Materials Needed to Force Carbonate Beer

Unlike natural carbonation in bottles using sugar and yeast, force carbonation uses a keg and a high-pressure cylinder of CO2. Here is what you need to get started:

  • A Cornelius (aka Corny or soda) keg
  • Gas and liquid hoses, connectors and fittings
  • CO2 cylinder with pressure regulator
  • Brewing sanitizer

Once you have your materials, it is essentially off to the carbonation races. Here is our step-by-step guide to force carbonating your beer.

Force Carbonation Process

  1. Let your brew rest before starting. When the specific gravity remains constant in the 1.005-1.015 range over 2 days you're ready to go.
  2. Clean your empty corny keg and lid with sanitizer. You can use the CO2 tank pressure to remove all the sanitizer. This insures the inside of the dip tube is also sanitized, and the CO2 will displace the oxygen in the keg.
  3. Fill your keg with beer, but not completely. You need to leave a few inches of headspace for the CO2 gas.
  4. Connect the CO2 tank and turn the pressure up to 30 psi to seal the lid.
  5. Burp the keg's pressure relief valve 3 or 4 times to remove any remaining oxygen in the headspace.
  6. Check carefully to see if there are any leaks around the lid. A gas leak will make a hiss or show up as bubbles around the lid if sprayed with sanitizer.
  7. Use a portable CO2 leak detector if you are force carbonating in an enclosed area.

Fast or Slow Force Carbonation

To see a general differentiation between the force carbonation methods, we will call these carbonation methods "fast" or "slow."

The Slow Method

Use this force carbonation table to determine where to set the CO2 on the regulator and wait. The pressure from the tank will slowly infuse the beer with CO2. In anywhere between 2-14 days depending on the amount of carbonation desired your beer will be ready. Chill the keg, lower the gas supply to a 5psi "serving" setting and spew out delicious brew to your guests. 

The Fast Method

To carbonate quickly you need to go through all the above steps. However, your beer is ready to drink in as little as 1-2 days! The secret is to pre-chill the beer (CO2 mixed faster in cold liquid), keep the CO2 pressure in the cylinder at 30psi and to agitate the keg to mix the gas and liquid.

For the fast method, lay the keg on its side and rock it back and forth for 2-3 minutes to mix the CO2 gas in the headspace with the beer. Then disconnect the CO2 valve and put the keg in the refrigerator to settle for at least half an hour. At this point, you can test the beer. If you're happy with the carbonation, you're done! However, depending on the beer you may need to repeat this process several times over a day or so to get just the right carbonation.

If you'd rather watch a video than read, this video created by the team at Craft Beer and Brewing is a great resource that describes the process step by step.

Beer Carbonation Tips

As you try to create the perfect ratio of carbon dioxide to beer there are often times where challenges will present themselves. Below are a few tips and tricks to ensure your carbonation process runs as smoothly as possible.

  • If you aspire to being a "brewing God" always remember that "cleanliness is next to godliness." Reusing kegs, hoses and fittings without sanitizing them between batches may not only be unhealthy - it can ruin a perfectly good brew.
  • Oxygen is your enemy. Once the keg is sealed and the pressure relief valve is "burped" to remove all the oxygen in the headspace, do not open the keg again.
  • Temperature plays a vital role in the process. The lower the temperature, the faster the CO2 dissolves in the beer and the quicker to carbonation.
  • The volume of CO2 gas required for carbonation differs depending upon the pressure to volume ratio and the type of beer. Use this force carbonation calculator for different brews for easy reference.
  • Not all CO2 gas is the same. Industrial CO2 isn't as pure as food grade CO2 and can introduce small amounts of other gases in your beer.
  • Patience is a virtue. Allow a bit of time between steps. Make sure the specific gravity of the beer is stable before you transfer the beer from the fermenter to the keg. Transfer the beer slowly so you do not mix oxygen into the beer. After the transfer, wait before you begin forced carbonation. Let the beer settle before you tap the keg.
  • If you're fermenting indoors, keep the windows open or use the appropriate gas detection equipment. A CO2 leak in an enclosed area can be deadly.

Finally, we spoke with several brewers, read articles and watched many videos  before we wrote this one. While the general process is the same, each had their own tips, tricks and opinions about force carbonation. In the end, it is up to you to experiment with your own brew to find the perfect combination.

CO2 Gas Detectors for Brewery Safety

You can not see, smell, or taste carbon dioxide. While some experienced brewers say they can smell it in fermentation tanks only a carbon dioxide safety monitor that can detect it.

For brewers looking to purchase a personal safety device, we recommend the SAN-10 personal CO2 Safety Monitor. For breweries looking at a fixed gas detection system that meets all code requirements, we recommend a CO2 Storage Safety Alarm.

Carbonated Beer at it's Best

Learning how to carbonate your beer takes time and patience. Yet it also allows for creating a truly crisp and incredibly refreshing beverage full of "fizz" for everyone to enjoy. With the right safety equipment and instructions you will be on your way to carbonating with ease.

For more information on carbon dioxide in breweries or CO2 safety monitoring solutions contact us today.

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