One time co2 pressure for lagering

[surgical_ass]

I've got an Oktoberfest I brewed recently. I plan to lager it in a serving keg until October. I would like for it to be carbonated and ready to serve in October. I was wondering if there is a calculator or some way of figuring how much ONE TIME pressure to put on it to have it be properly carbonated in Oct. ? Am I over thinking it and all I need to do is put 10 psi (or whatever it calls for) to achieve correct volume? I typically have it it hooked to the gas line the whole time but I would rather not have it in the kegerator until ready. Thanks!

 

[day_trippr]

"Calling @doug293cz"

fwiw, my swag is you couldn't stuff enough CO2 pressure into the head space of a corny keg with 5 gallons of Octoberfest to hit the ~2.65 volumes of CO2 for the center of the style in a single shot without the PRV doing its thing...

Cheers!

 

[doug293cz]

"Calling @doug293cz"

fwiw, my swag is you couldn't stuff enough CO2 pressure into the head space of a corny keg with 5 gallons of Octoberfest to hit the ~2.65 volumes of CO2 for the center of the style in a single shot without the PRV doing its thing...

Cheers!

If the beer has 0.85 volumes of CO2 at the end of carbonation, then to get 2.65 total volumes, you need to add 1.8 volumes of CO2 during carbonation. That works out to 5 * 1.8 = 9 gal of CO2 at STP (standard temp and pressure.) The headspace volume is about 0.35 gal, so you would need to cram in excess of 9 / 0.35 = 25.7 gal worth of atmospheric pressure CO2 in the headspace. To do that the headspace pressure needs to be over 25.7 times atmospheric pressure, which is 25.7 * 14.7 = 378 psi.

So, @day_trippr is correct. You can't do a one-time CO2 charge to get your desired carb level.

The analysis above is very approximate, and doesn't take into account temp effects on pressure and CO2 solubility. A more precise analysis is not going to change the situation enough to help out.

Brew on

 

[ba-brewer]

You could just prime it with sugar and that would give you the appropriate carbonation level. Beersmith says use half the amount of sugar that you would normally use for bottling. That seemed to work OK for me when I have tried it. You can also pull the CO2 from the keg after a couple weeks and it will hold that pressure.

But I think if you cant keep the beer cold it would be better to brew it closer to the time you want to drink it.
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[surgical_ass]

If the beer has 0.85 volumes of CO2 at the end of carbonation, then to get 2.65 total volumes, you need to add 1.8 volumes of CO2 during carbonation. That works out to 5 * 1.8 = 9 gal of CO2 at STP (standard temp and pressure.) The headspace volume is about 0.35 gal, so you would need to cram in excess of 9 / 0.35 = 25.7 gal worth of atmospheric pressure CO2 in the headspace. To do that the headspace pressure needs to be over 25.7 times atmospheric pressure, which is 25.7 * 14.7 = 378 psi.

So, @day_trippr is correct. You can't do a one-time CO2 charge to get your desired carb level.

The analysis above is very approximate, and doesn't take into account temp effects on pressure and CO2 solubility. A more precise analysis is not going to change the situation enough to help out.

Brew on

I knew someone had a way! Thanks for the leg work! I've got a couple variations from your original formula but I don't think they will make a huge difference. I will have about a gallon of head space if not a bit more. I can just hook it up closer to time on constant flow. Thanks again!