Another Keg Carbonating Question

[tdiowa]

I recently started down the road of Kegging. I have read all the articles on force carbonating both fast and gradual but I have noticed something on my last two kegs. When I fill the kegs I always purge the headspace of oxygen with CO2. I then let the kegs condition for several weeks. When I go to "Fast" carbonate at 40 degrees I first put my Keg Pressure Tester on and it always reads 35 - 40 PSI. I will purge the tank and the pressure will always go back up to 35 - 40 PSI.

My question is how do I force carbonate when the pressure is already that high and is the beer already carbonated since I have already filled the headspace with CO2 after purging and letting the beer sit for several weeks?

Any help on this would be most appreciated.

TD

 

[rdwj]

Sounds like you're priming in the keg. There shouldn't be any pressure. If you want to force carb, you don't use priming sugar; just C02.

 

[tdiowa]

Nope, no priming of the keg....

 

[Drunkensatyr]

Are you letting it sit at 35-40 psi hooked up to gas? You should only run 30 psi for about the 1st 24 hours. Then just unhook the gas and let it sit till the pressure comes back down (saturates into the beer) then just keep it at serving pressure. I apologize if I misread your question.

 

[Sea]

Yeah, what he said. If th keg is already carb'd (you're using priming sugar), then all your doing is letting th co2 out of th headspace of the keg. Then some of the CO2 in the beer itself comes out of solution to fill the headspace, evening out the pressure differential. Your could do this over abd over, and would get progressivly lower pres. readings each time.

I simply keg (no sugar), connect to co2 @12 PSI (my carbing and serving pres.), purge the headspace, and let her sit. It takes a week or 2 to fully carb at this pressure, but I need that time for aging anyways.

Cheers!

 

[Funkenjaeger]

The pressure in the headspace at equilibrium at a particular temperature is directly proportional to the amount of co2 dissolved in the beer.

Have you actually checked the beer to see if it comes out carbonated?

And just to verify, when you are checking the keg pressure, that is WITHOUT the co2 hooked up to it, right?

Refer to this page for a carbonation table:
http://sdcollins.home.mindspring.com/ForceCarbonation.html
If you are seeing 35-40psi in the headspace after purging and letting it equilibrate again, then there has to be a fair amount of co2 already in the beer. If the beer is at 70F, 35-40psi would correspond to probably 2-3 volumes of co2, which is a normal level of carb for many styles. If you're reading 35-40psi and the beer has already been cooled to 40F, you're looking at 4-5 volumes of CO2, which is very high.

Either way, if you're seeing 35-40psi in the headspace at equilibrium at any reasonable temperature, unless you shook it up or something, then your beer must be carbonated, at least to some degree. I don't think that gassing it to 40psi a single time and then disconnecting it would be enough to fully carbonate it, provided the keg wasn't like half empty when you started.

I would say that one of the very first things you should do is actually test the beer to see if it is carbonated or not, because if it's already carbed then obviously you don't need to go to the trouble of trying to force-carb it.

 

[tdiowa]

I simply keg (no sugar), connect to co2 @12 PSI (my carbing and serving pres.), purge the headspace, and let her sit. It takes a week or 2 to fully carb at this pressure, but I need that time for aging anyways.

Cheers!

When I Keg I purge the headspace with CO2. I have never taken a reading as to what the pressure is after purging. Could I be "force carbonating" while letting the keg condition? Should I, after purging the headspace with CO2 take a Keg Pressure with my tester and keep it at a certain PSI while conditioning? Am I all ready carbonating the keg by having such high PSI and if I am should I bleed the keg to an acceptable stable PSI?

TD

 

[Funkenjaeger]

Keeping a high pressure on the keg will carbonate it - if you shake it up it will carb it very quickly, otherwise it takes quite a while for the CO2 to dissolve into solution, as Sea mentioned.

If you are just purging, applying a high pressure, and then disconnecting the CO2, then you are not going to get a lot of carbonation because as soon as the beer absorbs some of the co2 the headspace pressure drops until it reaches equilibrium again. That's why if you KEEP the co2 hooked up to it, it will keep the pressure constant so the beer keeps absorbing co2 until it reaches equilibrium at the desired carbonation level, as determined by A) pressure and B) temperature - this is exactly what carbonation tables are meant for (like the one I linked above)

If you are conditioning at room temp, you would need a pretty high pressure to force carb, which is why force carbing is usually done once the keg is chilled, in which case you can usually get an ideal carbonation level with a much more reasonable pressure (like 10-12psi), allowing you to keep it carbonated AND dispense, without having to change the pressure around.