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CO2 volumes calculator

The CO2 actually dissolves into the beer, much like sugar or salt dissolve into water, but it takes some time. The carb chart tells you the final volumes you will reach if given enough time. It takes a week or two with the CO2 maintained at the indicated pressure.

CO2 transfers into the beer at the surface where gas and liquid touch each other. Increasing how much they touch speeds up the process. You can speed up the process by shaking or rolling the keg. Bubbling the CO2 through the beer by turning the keg upside down won’t help much.

Setting the pressure higher than what the chart says does help to force the CO2 into the beer a bit faster but that will risk over-carbonating. The only way to over-carb the beer is to set the pressure higher than what the carb chart says for the given temperature. At the indicated temp and pressure for the desired volumes, you can not overcarb, no matter how much you shake, rattle and roll the keg.

Thank you all, this was very helpful!

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Food for thought… Hook up your gas line (flared fittings,yes?) to liquid disconnect… I’d put it at even 20 PSI’s… Yes, do shake it… Then, once it’s done accepting CO2… Disconnect and then put your gas back as it was… Hook up the lines and pour a few pints… It may be foamy for a few pints, but it’ll settle down and you’ll be imbibing sooner rather than later… :beers::mask:

My SOP is to put keg in kegerator and crank CO2 to 30 psi for 24 hours, then drop to 20 psi for 2-3 days then sample. My serving pressure is right about 8 psi for my kegerator. I’m typically not patient enough to wait 3 weeks to carb. If I had a keezer setup where I could carb two and serve two, I’d definitely do that option to get them ready while I’m workin through the active kegs.


I look at that chart, WT_. I understand #s on the left. The lbs of the regulator on top. What are the #s in the middle mean?

The numbers in the middle are the volumes of CO2 you should end up with at the end, if I’m not mistaken.

Sounds good, I’ll try this method probably. I appreciate it

I got beer in my regulator trying this, luckily I have two regulators… Not sure what I did wrong.

Yep. Correct.

By pass the check valve? It won’t let a higher pressure feed back into the gas line.
I’m sorry you got something more to look at now… This has worked for me so many times…

How do you get to those #s?

This article gives a reasonably easy to follow explanation. Master the Action: Carbonation - Brew Your Own

I’m not sure if you are asking how the Volumes of CO2 are derived from the chart? Cross reference your beer temp by psi of CO2 at equilibrium. i.e. A keg at 32* F stable (at equilibrium) for two weeks at 12psi of CO2 will have 2.9 volumes of CO2.
Now if your asking about the math behind the table, I could have helped you back in the early 1980’s when I tutored freshman chemistry for beer money, but a quick glance at millimoles and avagadro’s number tonight was enough to deter any attempt on my part to go any further!

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Good time to put on the coasters brakes!!! :roll_eyes::mask:

Not a problem, it was an older regulator, not sure it has a check valve. I’m using a tap rite regulator now, which I think all have check valves. I’m going to tear the other one down and clean it up, should be good to go.


The math behind the table… holy sh–!:tired_face:

The numbers in the middle are volumes of CO2.

Picking how many volumes you want is really about beer style and preference. More volumes means more highly carbonated beer.

I’ve not looked at " these technical" places you guys speak of… BUT… You say volume as you are shoving 15 gallons of CO2 into an already full 5 gallon keg… Is that a close assumption? :mask:

The CO2 both dissolves into the beer and compresses under pressure so it takes up less space.
Say we took a 5 gallon keg of beer and held it at the appropriate temp and pressure for 2 or 3 weeks to get the carbonation to 3.0 volumes. Then we disconnected the CO2 supply, attached an empty giant balloon to the gas post and let it sit at 32 degrees F long enough for all of the CO2 to come back out of solution, we would have 5 gallons of flat beer in the keg and the balloon would expand to a size of 15 gallons.

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You are correct. Taprites do have a check valve. Lots of older and cheaper regs do not.

I’m normally a set it and forget it kind of guy but when in a rush I’ve employed @radagast’s method as well as keg rolling. You can overcarb pretty easily by rolling if you’re overzealous and have the gas up high. I find 48 hours at 25-30psi, gas off, burp it, then 9-10 and it’s generally drinkable but will be fully carbonated at about 2 weeks regardless of the method you use.

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