Fundamental force carbonation question

Discussion in 'Homebrewing' started by cpferris, May 15, 2014.

Thread Status:
Not open for further replies.
  1. cpferris

    cpferris Zealot (512) Jan 22, 2008 Indiana
    Trader

    This thread spilled over from another item in the home bar forum, but thought I might move it here in case others are interested. When it comes to force carbing, I am fully aware of the carbonation charts and how temp/psi are used to achieve the correct vols of CO2.

    Lets assume you made an IPA and it required 2.5 vols of CO2. According to the charts, that would require 12-13psi @40F. There seem to be two schools of thought....those who "set it and forget" at 12-13psi @40F and let the brew force carb slowly and achieve proper vols of CO2 in 7-10 days. Then there are others who might apply 30psi for 24h, then vent and reduce to 12-13psi and achieve the 2.5 vols in maybe 3 days.

    But if 12-13psi @40F should get you to 2.5 vols over time, couldn't you rock a 40F keg until it stops bubbling (meaning no additional CO2 can be absorbed into solution)? Given the lower pressure, would it still be possible to over carbonate? Is there a reason that wouldn't work?
     
  2. mikehartigan

    mikehartigan Maven (1,421) Apr 9, 2007 Illinois

    If the temp and pressure are set according to the charts (which are based on the laws of Physics), then there's no danger of overcarbing, no matter what you do to it. Yes, you can speed up the process using the shake, rattle, and roll method, the high-pressure method, or both. But it's too much work and I've got time and plenty of beer in the pipeline to wait :slight_smile:. 'Set it and forget it' also allows things to settle out a bit before serving.
     
  3. cpferris

    cpferris Zealot (512) Jan 22, 2008 Indiana
    Trader

    Thanks Mike, your answers are always appreciated. Not sure I will do this, but wanted to make sure I wasn't misunderstanding a basic somewhere.
     
  4. jbakajust1

    jbakajust1 Pooh-Bah (2,552) Aug 25, 2009 Oregon
    Pooh-Bah

    Should work as @mikehartigan said. With the shake method you can risk scrubbing out hop aromatics into the head space too. For my beers with dry hopped or oak I usually keg warm and leave warm while carbing at a higher psi then drop psi and put in fridge after 3-4 days. Cuts the lag time down, and seems to get the hops in there better.
     
    mattbk likes this.
  5. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,375) Dec 15, 2005 Pennsylvania
    Society Pooh-Bah

    Something to keep in mind is that while CO2 can go in solution in a relatively short timeframe there is another aspect to carbonation: CO2 hydration. The aspect of CO2 hydration takes longer (e.g., weeks).

    Cheers!

    P.S. Below is something that Martin Brungard posted on another beer forum:

    “We know we can infuse CO2 into solution fairly quickly. The soda manufacturers do that every day. Nice coarse and effervescent bubbles are formed. But with time, CO2 is hydrated and I feel that this mechanism is key to the change in carbonation quality that we brewers desire. The hydration of CO2 is a very time-dependent process and it cannot be accelerated. That is why you can force carbonate a keg in minutes, yet not have acceptable foam for a few weeks.”
     
    mattbk likes this.
  6. mikehartigan

    mikehartigan Maven (1,421) Apr 9, 2007 Illinois

    That probably explains why a beer that's been carbed for a few months has a nice fluffy head, while the head on a beer that was carbed yesterday looks more like soap suds.
     
  7. mattbk

    mattbk Savant (1,111) Dec 12, 2011 New York

    This.

    I'd like to work out a calculation where you determine the total pressure to jam into head space that will carbonate a volume of beer to a volume of CO2, without shaking. So, ideally, you would slam the head with this pressure, then back it down to the nominal pressure. My feeling is that this would be the fastest way to get a beer carbonated without risk of overcarbonation or scrubbing out flavors; the higher pressure should cause the CO2 to diffuse into the liquid even faster. On my list to do (which is fairly long as it is). Does anyone know the mathematical relationship between temperature, volumes of CO2, and pressure?
     
  8. JackHorzempa

    JackHorzempa Grand Pooh-Bah (3,375) Dec 15, 2005 Pennsylvania
    Society Pooh-Bah

    Matt, I think below is the equation you are seeking:

    P = -16.6999 - 0.0101059 T + 0.00116512 T^2 + 0.173354 T V + 4.24267 V - 0.0684226 V^2

    Pressure = F(Temperature, Volume) Temperature is is Fahrenheit, Volumes is in Volumes of CO2 required. Please remember your order of operations! And to convert Celsius to Fahrenheit the formula is C¡ = (F¡ - 32) x (5 / 9) . The way to do it in your head is: Centigrade to Fahrenheit double the number, subtract 10%, then add 32.

    I obtained this from: http://www.brainlubeonline.com/GasLawsBeer.html

    Cheers!
     
  9. mattbk

    mattbk Savant (1,111) Dec 12, 2011 New York

    Actually, I ran this using the ideal gas law, and the pressure to do this would be very, very high. I guess I'll stick to set it and forget it.
     
    JackHorzempa likes this.
  10. billandsuz

    billandsuz Pooh-Bah (2,097) Sep 1, 2004 New York
    Pooh-Bah

    I agree, mostly.

    if you do not burp the keg after applying high pressure then there is no reason the high pressure roller method is in any way different than the set it and forget it method.

    after all, once the vols are achieved it's all the same, no matter how fast you got there.

    now, if you crank 40 psi overnight and the proceed to vent the headspace the next morning, sure you could very well blow out hop aroma. so don't do that. let it ride and everything will be kosher.
    Cheers.
     
Thread Status:
Not open for further replies.