Warm carbing - sanity check please

[Kealia]

When I read threads like these I smile - and state again in my mind that bottling isn't so bad.

Hehe, normally it's very simple: Set at desired psi and forget about it. This dance between temps is the monkey-wrench. Normally, I just fill one big bottle (read: keg).

Gas chart I use.

FIT, that's the chart I am referring to - which works fine if you carb and serve at the same temp. It's the move from one temp to another that has me scratching my head on how the psi/volumes of CO2 re-equalize.

[Knightmare]

Ok. I admit I skipped most of the past at on this thread. But to answer the OP, the beer can only absorb so much CO2 at a certain temp. Even the pressure in the keg head space is so minimal it will hardly make a difference by chilling to serving temperature. I don't have the chart in front of me, but let's say you carb at say 28 psi at room temp for 14 days to hit your desired carb level. All you have to do after putting it in the kegerator is drop the pressure to serving pressure (10-12 psi) and vent the keg if you want. A little CO2 may release out of the beer until it gets cold. But then it will re-absorb back into the beer. The carb level will remain the same. And will stay the same as long as serving pressure matches carb levels for the temperature. Make sense? Easy as pie!

[Inkleg]

^This^ is what I've been thinking, but Ron had to make my head hurt with math.
If you carb at the higher psi at room temperature then it will have the same CO2 by volume when chilled as if carbed at the lower psi to achieve the same volume at the lower temperature.

Now stop it, just stop it and go play with some beer.

[Dawg LB Steve]

Throwing in my two cents, IMO over-thinking it guys, once you get your CO2 volume your shooting for, it won't change. Go to your warm setting for your volume, when you want to refrigerate lower the reg. bleed off the head space.
Think about bottle conditioning, you can go from warm to cold to warm to cold over and over, the carbonation will be the same. Higher pressure warm, lower pressure cold.

[Knightmare]

To make it simple, the beer can only absorb a certain amount (volume, aka standard cubic feet) at a certain temperature and pressure. If we disconnect from the supply gas, and cool the keg, it does not absorb anymore gas because we have removed the supply. The amount of CO2 remains the same. We have not changed the volume, therefore the carb level remains the same. This is called the Gay Lussac Law of gas. Now if we had left it hooked up to same supply gas pressure (28 psi) that we used at room temp, it would be able to absorb more CO2 as the temperature is lower allowing more volume to be absorbed into the beer. Pressure drops linear with temperature but the volume remains the same. Make sense?

[John Sand]

That's what I was getting at, the mass of the gas, not the pressure. But he said it better.

[Kealia]

This wouldn't be the first time that I've over-thunk something.

Thanks for all the comments, input and education. What you've said makes perfect sense and was my original thinking.....then I thought I was smarter than I really am. Then I confused myself.

Must be the lack of beer consumption this week.
Cheers.

[RickBeer]

[DaYooper]

I too will hit with gas around 4-5 points higher than intended at room temperature and let it sit. If I get bored or feel like getting a workout I will lug the keg over to the kegerator and hit it with kegerator pressure. Only take around 3 days in the kegerator for me assuming it has been sitting around for a week or two. The first blast is at room temperature, then next 1-3 are at around 50F which is what my pantry is at 9 months out of the year.