# Force Carbonating Question

### Help Support Homebrew Talk:

#### Nathan Hassey

##### Supporting Member
HBT Supporter
I am starting to "force carbonate" my beers and had a question about volumes of C02. I want to do the set to a set PSI and leave for a week to carbonate but don't have the ability to keep the keg in a 38-40 degree area so I am carbonating it at 50 degrees.

My question is, if i carbonate to 2.5 volumes at 50 degrees and then bottle it and chill the bottles down to 40 degrees, will it still be 2.5 volumes or does the temp drop increase the carbonation?

I know this probably isn't a common way to bottle beer but I find more consistency with force carbonating than bottle conditioning.

#### Dustin_J

##### Well-Known Member
The pressure changes with temp, but not the volumes of carbonation - so you'll be fine. For your health!

#### day_trippr

##### Covid-19 Vaccine Effectivity Test Subject
There's more than one way to carb a keg

If you look at our favorite carbonation table and in particular look at the jagged gray-to-green line you can see there are myriad temperature vs pressure combinations that will yield the same carbonation level. As long as the keg sees a valid combination for the carbonation level you desire it won't change...

Cheers!

OP

#### Nathan Hassey

##### Supporting Member
HBT Supporter
Yea I've been using these charts but didn't know how to follow it down for a bottle that was bottled at 50 degrees but then chilled down to 38-40. Didn't know which direction to follow my finger down the chart.

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
The pressure changes with temp, but not the volumes of carbonation - so you'll be fine. For your health!
True.

The issue will be with trying to bottle from a keg at 50°F. You will likely have foaming issues, which will reduce the carbonation of the beer that gets bottled. The standard advice for bottling from a keg is to have the keg and bottles very cold.

Brew on

OP

#### Nathan Hassey

##### Supporting Member
HBT Supporter
I have a blichmann beer gun and it bottles fine at 50 degrees. I just keep the psi low when filling.

#### day_trippr

##### Covid-19 Vaccine Effectivity Test Subject
Yea I've been using these charts but didn't know how to follow it down for a bottle that was bottled at 50 degrees but then chilled down to 38-40. Didn't know which direction to follow my finger down the chart.
Follow the temperature. In this case, "up"

Generally one wants to know what pressure to use for a given temperature to hit the desired carbonation level. So find the temperature first, then run along that row to the desired carbonation level (expressed as "volumes of CO2" where ~2.4 volumes is about the middle of most ales) then run up that column to find the pressure to use...

Cheers!

OP

#### Nathan Hassey

##### Supporting Member
HBT Supporter
Copy thanks. For some reason I was thinking the volumes would change in the bottle after I chilled it but that's the public education system for you!

#### HopsAreGood

##### Well-Known Member
To piggyback on this.. If I want to carb my beer to approximately 2.3 volumes and want to use the set and forget method...

If I stick my keg in freezer at 36 degrees and 8 psi this will result in 2.3 volumes.

BUT:

If I want to then serve the keg at 50
Degrees, I’d need 15psi to still be at 2.3 volumes. I know I could just set and forget at 50 and 15 but it will go much faster at 36 degrees.

My question is won’t much of the disolved co2 come out of solution as I let it warm up to 50?

Would I just let it rise to 50 then purge the headspace and then set to 15?

Thanks

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
To piggyback on this.. If I want to carb my beer to approximately 2.3 volumes and want to use the set and forget method...

If I stick my keg in freezer at 36 degrees and 8 psi this will result in 2.3 volumes.

BUT:

If I want to then serve the keg at 50
Degrees, I’d need 15psi to still be at 2.3 volumes. I know I could just set and forget at 50 and 15 but it will go much faster at 36 degrees.

My question is won’t much of the disolved co2 come out of solution as I let it warm up to 50?

Would I just let it rise to 50 then purge the headspace and then set to 15?

Thanks
Some CO2 will come out of solution when you raise the temp, but that will increase the headspace pressure, which will reduce the additional amount of CO2 that can come out of solution. You will eventually achieve equilibrium again at the new temp. The larger the headspace to beer volume ratio, the more carbonation you will lose from the temperature rise. Small headspace - you won't notice the difference. Almost empty keg - big loss of carb.

I would recommend just carbing at serving temp and appropriate pressure for the carb level you want. Beer doesn't really absorb CO2 faster at lower temps, it just absorbs more at a given pressure. Carb rate at 8 psi and 36°F shouldn't be much different than 15 psi at 50°F.

Brew on

#### bracconiere

##### Jolly Alcoholic
HBT Supporter
Yea I've been using these charts but didn't know how to follow it down for a bottle that was bottled at 50 degrees but then chilled down to 38-40. Didn't know which direction to follow my finger down the chart.

do it by weight? i just got the tip for a great postal scale that stays on....put the keg on it and just let it sit till it's the right weight.....

not sure if this would help....

http://www.airproducts.com/Products...ht-and-volume-equivalents/carbon-dioxide.aspx

but it tells me 4.5 ounces for 2.5 volumes.....and i got a postal scale that is good to 110 pounds, and acurate to 0.1 ounce.....

using weight you should be able to hit it with like 50 psi, and just watch the scale also....

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#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
do it by weight? i just got the tip for a great postal scale that stays on....put the keg on it and just let it sit till it's the right weight.....

not sure if this would help....

http://www.airproducts.com/Products...ht-and-volume-equivalents/carbon-dioxide.aspx

but it tells me 4.5 ounces for 2.5 volumes.....and i got a postal scale that is good to 110 pounds, and acurate to 0.1 ounce.....

using weight you should be able to hit it with like 50 psi, and just watch the scale also....
I just bought the same scale (based on @bracconiere 's review.) Measuring weight gain is a good way to follow the progress of carbonation. The thing you have to be careful with is that the beer starts out with about 0.85 volumes of carbonation (depending on fermentation temperature), so for say 2.3 volumes total carb, you would only want to add an additional 2.3 - 0.85 = 1.45 volumes. One volume of carbonation is equal to 1.977 g/L or 0.264 oz/gal. So, for 5 gal of beer needing 1.45 additional volumes of CO2, you want to add 5 [gal] * 1.45 * 0.264 [oz/gal] = 1.914 oz.

Edit: I looked at the link in the previous post, and couldn't figure out how to use the information there to determine necessary weight of CO for desired level of carbonation. I can provide derivation of my numbers above if desired.

Brew on

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