• Welcome to the new forum! We upgraded our forum software with a host of new boards, capabilities and features. It is also more secure.
    Jump in and join the conversation! You can learn more about the upgrade and new features here.

Some questions on keg carbonating...

T

therobot

So here's my question.  Say I carbonate at room temperature, using the pressure calculation from BeerSmith.  When it's finally carbonated, the keg will have that same pressure in the headspace, correct?  Now, if I chill the keg afterwards, since the beer can take more CO2 at a colder temp, will it slowly absorb CO2 from the headspace until the pressure there is less, and there's slightly more carbonation in the beer?

I was just thinking of major breweries and how they do it.  Do they carbonate at lower temperatures, or higher ones.  Is the extra headspace pressure why kegs at a bar always pour so foamy at first? (I was a bartender for a couple of years.), etc.
 
I've have not much kegging knowledge, But I think it depends on the brew. I run mine around 8-15 psi., I'm sure there are fellas on here that have the knowledge for the science of it (ask preston or sleepy sam, they'd know). From exsperience so far, if a pale ale is warmer you get more foaming than you would with a more chilled version (I tend to drop the pressure if thats the case) I assume it's bubbling abit more than when it's cold
  I'm no expert but after I get where my own beers are comfortable to pour, I leave it at that and pour smooth beers. I'm sure it would be different if you were looking for a consistant beer everytime,
I'm no scientist, so at the same time, I'm curious about this question as well. Thats my input from what I know so far, I'm sure I've helped nothing at all, lol.
Cheers friend
 
The answer to your question is YES, but the change in carbonation ratio will be very small unless you have a very large headspace.

With respect to the major brewers, I think that they stop venting their fermenters so that the fermentation process provides most of the carbonation.  That way they do not have to force carbonate very much.
 
+1 baj475
Agree. If the head space was larger then you would see an increase during force carbonation. Most likely you will never see any change using Cornie's.

The Pro brewers in the small breweries I have visited in the Seattle area use Brite tanks with a venting system that keeps the beer from being over carbonated. I have looked into creating a setup that fits to the top of a corny keg where the vent is in an effort to recreate this setup. I have 6 extra Cornie's that I was going to turn into fermentation chambers. But have not purchased anything yet.

Cheers
Preston
 
Preston,
So you set up a pressure cooker like valve to allow 8-10 psi in the keg and vent the rest, use the keg as a secondary, when fermentation is complete you rack out the sediment and only use your CO2 tank for dispensing the beer?

I like!

-John
 
I got the idea from another forum which you can read for yourself here: http://www.homebrewtalk.com/f13/closed-system-pressurized-fermentation-technique-44344/

The premise is that the yeast work harder/faster at around 15psi , or .01 bar with less krausen. My idea was to use an inverted corny instead of a Sanke keg. The Spunding valve would be on the out side of the Corny keg, and I could use the vent to clear the yeast from the vessel for secondary similar to a conical fermentor. Then transfer out of the Corny using the in side of the corny.

I have an extra Sanke keg that I may use as the OP has. As I said, I have not started this project. I am merely in the "What if" stages. I also found this about lagers and diactyl production using a pressurized fermentation setup from the same thread:  http://www.homebrewtalk.com/wiki/index.php/Fermenting_Lagers
 
Preston,

For a vented Corney Keg Brite Tank, you could use something like the B3 pressure relief.  See http://morebeer.com/view_product/16771//Adjustable_Pressure_Relief_Valve.  Just pressurize an empty keg through the liquid out port to the pressure limit you want and adjust the relief valve to just start relieving at that pressure.  If you want to monitor the pressure it comes with a gauge.  http://morebeer.com/view_product/16772/102301/Ball_Lock_QD_Adjustable_Pressure_Valve_W_Gauge

According to BeerSmith it only takes 3.76 oz of sugar (dextrose) or 5.26 oz of DME in 5 gallons to reach a 2.6 carbonation ratio at 50F.  At 70F the numbers are 4.73 oz sugar and 6.62 oz DME.  This corresponds to a gravity of 1.002 to 1.004, so you would probably want to be within .003 to a maximum of .005, depending on temperature, of your final gravity before transferring to your Corney Brite Tank.  This takes into account that at 50F your beer in an atmosphere of 100% CO2, i.e. fermenter, will have 1.1 volumes of dissolved CO2.  At 70F your beer in an atmosphere of 100% CO2 will have 0.7 volumes of dissolved CO2, which is why slightly more sugar or DME is required.
 
Thanks, that's great info!

I will need to order one of those!

Cheers

Preston

 
Awesome, thanks for the input ya'll!

So, let's further the question.  Say I room temp carbonate (no fridge  :() and then want to put the keg on ice for a party.  Should I bleed the headspace and then repressurize it to a serving pressure?
 
Back
Top