Top pressure carbonating

Fri Sep 24, 2010 3:04 pm

If I have 10 gallons of beer in a 15.5 gallon keg. How much pressure for how many hours will give me 2.5 volumes of co2 at 37F?

Anybody worked out a system besides taste and check every few hours? That does sound fun though.....

I know my equilibrium pressure will be around 11psi.

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Re: Top pressure carbonating

Fri Sep 24, 2010 3:38 pm

If you set the pressure right at 11 psi to carbonate it will take something like a week and a half or so. I;ve heard a week but my experience has been that it takes a bit longer. What I do when I want a faster carb time but don't want to do the shake, rattle, and roll method is set the pressure for 30ish psi for about two days and then drop the pressure down to the serving pressure for the last day or so to finish carbing.

Really the only way to do it in hours time is to shake the hell out of the keg while it's under pressure which could be a bit tiring with a full 1/2 bbl keg! :drink
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Re: Top pressure carbonating

Fri Sep 24, 2010 4:00 pm

I am hoping there is a chart or someone has the knowledge of time vs temp vs pressure like 50 psi for 12 hours gets you in the ball park. Head space probably plays into the equation too. I'll die of thirst in a week and a half!
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Re: Top pressure carbonating

Fri Sep 24, 2010 4:08 pm

Newbie wrote:I'll die of thirst in a week and a half!

Brew more
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Re: Top pressure carbonating

Wed Sep 29, 2010 6:32 pm

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Re: Top pressure carbonating

Tue Oct 05, 2010 3:43 pm

If you don't want to carbonate above the storage pressure, but want to decrease the time needed, try turning the keg on the side. The rate of transfer is related to the difference in partial pressure between the dissolved gas and the head space, the depth of fluid and the surface area. turn the keg on the side and the surface area goes up and depth goes way down.
There wont be any charts because the process is VERY complex, well at-least our situation is complex from a physics stand point. you would need to know things like how the fluid convection currents are occurring (function of temperature swing, and would need to be known to something like 0.0001 degree changes), the diffusivity of the beer, which will change between batches, pressure, how much beer is in the keg.
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Re: Top pressure carbonating

Fri Oct 15, 2010 1:24 pm

I have a shake formula.

30 psi through the liquid side. Turn keg on its side and roll back and fourth with the liquid dip tube on the bottom (near the floor). Let rest for about 6 hours, relieve pressure and serve. Carbonation isn't perfect, but is close.

On a 5 gallon corney keg.
5 minutes = 3.0 volumes CO2
4 minutes = 2.5 volumes CO2
5 minutes = 2.0 volumes CO2

Give or take.
I've consumed all of my homebrew. I'm worried. I can't relax. Now what?

Pvt. 1st Class BN Army
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Re: Top pressure carbonating

Tue Dec 04, 2012 8:31 pm

For math geeks, I think I worked it out. (I can resurrect an old thread if I started it I hope!)

Co2 equilibrium / percent empty

Say the beer is flat and 37f and you want ~2.5 vols of co2. Say you have 10 gallons in a sanke.

11/(5.5/15.5) =31psi worth of top pressure, remove the co2. The beer will equalize at 2.5 vols.

If you have 4 gallons in a corny keg at 40f:

12.5/(1/5) =62.5psi

This formula assumes you know how to use a co2 chart and will not exceed the working pressure of your keg.

I have been doing this and the beer (to me) has the right levels of co2 after a few days. The colder the beer the faster the equilibrium.
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