Newbie Carbonation Questions

[Dan2539]

So this is my second time kegging a beer and I don't want to use shake carbing like I did with the first batch. I'm using beersmith software to find out what my carbonation temp has to be for my desired co2 volumes. Does this temp have to be the serving temp or just the temperature that I'm force carbing at? For example, I'm kegging a Hefewizen that will be at 3.5 volumes of co2. I don't currently have a keggerator so I put my kegs on ice for serving or draft bottle filling. My basement is at a consistent 60 degrees so the program estimates the pressure to be 37.3 PSI. If I keep my beer carbed in my basement at this temp, will my beer be properly carbed when I ice it down for serving? I don't intend to bottle this brew btw because I think the carbonation is a little to high for the bottles I have.

Also, during the force carbonation process do I keep my keg connected to the gas for the whole process or can I just fill the keg to the pressure desired and then just monitor the pressure with my bleeder valve / gauge setup?

Sorry for the long post... just have a lot of questions and I don't want to wind up over-carbonating my beer like last time.

 

[Suthrncomfrt1884]

When kegging, the keg should ALWAYS be left on gas. If you shut off the flow of CO2 to your beer, it will eventually go flat.

As for your issue... you're going to be using a ton of CO2 to carbonate that beer at 60 degrees. You don't necessarily have to carbonate at your serving temps, but it will probably take longer and as I said, more CO2.

You're smart to avoid the shaking method. All it does is overcarb your beer 90% of the time and then you have to wait until it balances out anyways, so you're not saving any time.

 

[AiredAle]

You should set your regulator to deliver the PSI for the temperature of the beer when you carb it, not for the temp you plan to serve it at. In your example above, 3.5 volumes at 60 degrees is 37 psi, if you serve it at 40 degrees, the pressure will be 23 psi for the same 3.5 volumes.

The volumes of CO2 will be constant but the pressure will drop when the beer is cooled. Just to be clear, one volume of CO2 is one liter of CO2 at standard temperature and pressure dissolved in one liter of beer. Or one gallon of CO2 in one gallon of beer. You won't use more or less CO2 to achieve a given number of volumes in the beer whatever the temperature of the beer is when you carb it, because the volumes are independent of the temperature.

The pressure of a given amount of gas in a closed system goes up or down as the temperature does. This is only true for beer in a keg when it is completely carbed up, (at equilibrium) at the pressure you set the regulator.

When I carb a cornie keg, I set the regulator for the pressure I need to achieve the number of volumes of CO2 I want at the temp the beer is at, and shake the keg to speed up the carbing process. I have also set kegs on their sides, with the gas post up, and the CO2 line connected and rocked them back and forth. I believe this carbs them faster because there is more surface area exposed to the gas than when the keg is upright. By setting the regulator at the desired pressure, instead of at a higherr pressure, you can avoid the overpressure problem.

Leave the CO2 on the keg as long as you are carbing it because it takes time to reach equilibrium. We do stuff like rocking and shaking to speed up the gas absorbtion process. Also, when your serving leave the keg on gas at the same pressure as you need to get your desired volumes. That is, in your example, leave it at 23 psi if you serve it at 40 degrees, that way you don't alter the amount of CO2 in the beer.

 

[TipsyDragon]

the temp in beer smith and other calculators is the highest temp your brew got to between the end of fermentation and bottling. there is residual CO2 in your beer from the fermentation process. cold beer holds onto the CO2 easier than warm beer. as the beer warms up gas escapes and you need to add more to get the same level of carbonation.

 

[AiredAle]

Typsy,

All you say is correct, but the fermentation temperature is most relevant if carbonation is done by adding sugar to get so-called "natural carbonation", to prevent overcarbonation. It is irrelevant if force carbonating the beer, except as you say, you will need more CO2 in a warm fermented beer than a cold fermented beer to reach the same CO2 volume.