Force Carbonate Your Homebrew

Does trying to force carbonate your homebrew seem intimidating? It really isn't that difficult. Here are a couple of techniques you can use.

When your beer has finished fermenting it's time to carbonate. You can prime in the keg and wait the required two to three weeks, or try force carbonating your beer in just a few minutes. To force carbonate the new beer, first decide how much carbonation you want.

Download the Keg Carbonation Chart and save it in your reference library:

Click here to download the force carbonation chart in pdf form, then save a copy to keep by your kegerator or chest freezer..

How to Use the Keg Force Carbonation Chart

Find the beer's temperature on the chart above. Let's assume the beer is at 36°F (2.22°C). For most beers 2.2-2.6 volumes of CO2 is normal. By using the chart you learn you'll need about 7.2 psi at 36°F (2°C) for 2.2 volumes of CO2. So for this style of beer, at this temperature you want to apply 7.2 psi (round to nearest whole number 7 psi) of pressure until the beer is saturated and won't accept any more CO2. The colder the beer is, the less pressure you need to force carbonate it.

How to Force Carbonate Your Beer

Keg Preparation Before You Force Carbonate:

This is the way I've always used to force carbonate my beer.  You simply leave all the connections on your corny keg just like you always keep them, ie. grey quick connect on gas-in post (the short post). 

Another keg setup you can try to force carbonate, and I'm sure many are already doing it this way, is to switch out the connections on your gas line from the grey to black quick connect.  You will then connect the gas line to your "beer out" post on the keg.  This will send the CO² down the line and back up through the beer (if you are standing the keg upright). Just be sure to change the quick connects back.

Make sure your beer is cold (like lagering temperature 34°F) before you try to quick carbonate your beer.  Connect your gas line to the gas post on your corny keg.  Check all connections to make sure there are no leaks at any connection or around the seals on the keg.  You can check by spraying some soapy water, or even StarSan on the seals and connections while they are under pressure.  Look for bubbles and tighten the connection if found.

Quick Force Carbonate Method

Open the purge valve for about 20 seconds to purge all oxygen from the keg's head space with CO2.  Adjust the screw on the regulator to set it for 30 psi.

You will hear gas bubbling inside the keg. It will continue for a little while and then stop. This is because the keg is standing upright and there is only a small amount of surface area for the CO2 to dissolve into.

If you have switched out the connections and have CO² going down the beer out line, you will want to shake the keg back and fourth while it is still standing so the CO² will migrate up through the beer. 

If you keep your connections the same as usual, then you can lay the keg on its side to increase the surface area of the head space.  Be sure and place a towel on your lap because it's pretty cold at this point.  Be sure to keep the gas quick connect down while the keg is on it's side.  This will force the CO² to rise up through the beer.  It also helps by letting you hear the rate at which the bubbles are coming out and going into suspension.

As long as you keep shaking and rolling the keg, CO² will continue to flow and you will hear bubbles in your keg.  When you stop rolling the keg, listen for the bubbles to stop.  It is going to take a little while at first, but as you get more CO² dissolved into the beer, it will take less and less time for the bubbles to stop.  This is telling you that your beer is carbonating.

Shaking or rolling the keg will start the flow of CO² again. If you let it go long enough, eventually no matter how much you roll or shake the keg, no more carbon dioxide will go into solution and you won't hear any more bubbles in the keg. Your beer is now fully and probably over-carbonated.

I generally don't let it go that far.  I normally roll the keg for about 4 minutes.  And when I say I roll it for 4 minutes, I mean I really get after it, keeping the keg rolling vigorously the entire time, stopping for a short time to check how fast the bubbles stop flowing.  It always seems that around 4 minutes, it doesn't take but a few seconds for the bubbles to stop flowing.  This is my indication that it's time to stop.

Of course, you will have to adjust the time based on how vigorously you roll and shake the keg.  The word "vigorously" is relative and will be different for each person.  So, you might want to let it go for 3 or 4 minutes the first time and check the carbonation level in a couple of hours to see if it is to your liking.

It's best to let the keg set inside your kegerator or your chest freezer for a few hours to settle down before you try to dispense it. Patience young homebrewer. 

Once it's carbonated, set the keg back in the kegerator, set the pressure according to the chart and the temperature inside the kegerator or cooler, and forget it for a while.

The CO2 inside the beer will equalize with the pressure set on your regulator. If you find you have over carbonated your beer, lower the pressure on the regulator and pull the pressure relief valve. The CO2 will come out of solution to re-pressurize the head space.  By releasing the pressure frequently, the beer will lose carbonation and will equalize to the correct pressure you set on the regulator.

If you under-carbonated the beer, more will go into solution until it is equalized with the pressure you set on the regulator per the chart (or if you are still in a hurry, repeat the process of purging the head space, putting 25-30 psi on the regulator and agitate the keg for a few more minutes...let it settle a couple hours and check it again).

Check Your Gas Line for Beer Make sure you have a check valve in your gas line or beer can get into the line and regulator and ruin it. Just to be safe, I usually disconnect the gas line from the keg, hold the quick connect against the towel and depress the pin inside the quick connect with a long slender object like a pen. All the beer in the line will shoot into the towel. Keep depressing the pin until the gas line is purged of beer.

When beer does get into the line, turn off your CO2, disconnect the gray quick-connect, fill the line with cleaner to soak. I then go through the purge sequence again to get the cleaner out and then do it all over again with sanitizer. As you can see, it's best to keep beer out of the gas line to begin with but sometimes it is unavoidable. (If anyone knows of a check valve that you can attach to the gray gas quick connect to prevent gas from ever getting into the line at all be sure and post a comment so everyone can check it out).

The Slow Force Carbonate Method

Another way to force carbonate your beer is to use the force carbonation chart to find the correct pressure you need for the amount of carbonation you want at the temperature inside your cooler. Just keep the keg in the kegerator or fridge, set the pressure and forget it.  Setting the pressure to 7 psi will give you 2.4 volumes of CO² at 36°F (2.22°C) according to the chart.

The CO2 will go into solution over the course of a few days. This is the easy way to force carbonate your beer, but it does take some time. If you shake or roll the keg every once in a while it will happen quicker. When using this method, spray a little soapy water around all the connections and the lid to make sure you don't have a leak. If you detect a leak, fix the problem before reapplying pressure. Once you lose an entire tank of CO2 in a day, you'll know why this is important.

Note:  If you plan on lowering the temperature of your keg, from 42°F say down to 34°F before you force carbonate your home brew, add a few extra pounds of pressure first. The gas in the head space of your keg will dissolve quickly as the temperature drops and if the o-ring on you lid is not seated properly, it could leak.

When you reach your desired temperature, the gas will come out of solution and escape out the leaky o-ring, leaving your beer with no carbonation. It is always a good idea to give a quick spray of soapy water on all the keg fittings and connections to make sure there are no leaks (wait till you open your kegerator one day to find two inches of beer in the bottom).

Blichmann Engineering QuickCarb Keg Carbonator


Purchase yours at MoreBeer.com

No one likes waiting, and the QuickCarb is the way to eliminate the wait from carbonating your homebrew.  This high-pressure co2-injection system from Blichmann Engineering™ will carbonate a keg in 30 minutes, with no chance of over carbonating your beer.  All connectors are included, and the unit hangs from the front of your keg.

Use is simple,  just sanitize the unit using the built in pump, and connect hoses to your Keg and CO2 system.  Turn on the gas, plug in the unit, and 30-40 minutes later, your beer will be perfectly carbonated.  Cleanup is just as easy, as you can run cleaner and sanitizer through the system using the pump as well.


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