Undercarbonated or More Patience?

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TeflonTom

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Last week on Thursday I kegged 3 different beers in my Corny kegs and have force carbonated and put them back under pressure. I went the usual route of pressuring the kegs at 30PSI and rolling them for about 7-8 minutes for my Kolsch and Blonde Ale, but I decided to roll my IPA for about 16 minutes since I read some results saying to roll for 10 minutes and other for 20. I have them back on the tees at 18PSI and the IPA seems to be the only one having a good head and more thorough carbonation. The former 2 will pour with some fizz but don't taste like they have much to them in comparison. Could I need to reseat the lids on the 2 and roll them again, or do I just need more time? Or could it just have been the extra time rolling the IPA that gave it the head start?
 

doug293cz

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What temperature was the beer when you rolled at 30 psi? What temperature has the beer been at while it has been on 18 psi? Has the 18 psi been applied continuously, or only intermittently? Did you purge the headspace with CO2, either before or after filling with beer?

Some unsolicited advice: I recommend against agitating kegs at higher than chart pressure for the current temp and desired carb level. Doing so is the easiest way to over carbonate beer. A simple way to get beer ready to drink in 2 - 3 days is to cool the beer, apply 30 psi for 24 hours, then vent and set to the chart pressure based on temp and volumes of CO2 desired. There is very little chance of over carbonating with this method.

Brew on :mug:
 
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TeflonTom

TeflonTom

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Each beer was agitated at 50 degrees initially for the 30 PSI. I then put the kegs into my tap cooler to cool to 33 degrees and waited about 4 days until I put them back on the tees at 18 PSI. I did not purge the headspace at all, I suppose it didn't cross my mind. Is there still a way to handle the situation with the 2 beers that don't seem to be all that carbonated?
 

doug293cz

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Each beer was agitated at 50 degrees initially for the 30 PSI. I then put the kegs into my tap cooler to cool to 33 degrees and waited about 4 days until I put them back on the tees at 18 PSI. I did not purge the headspace at all, I suppose it didn't cross my mind. Is there still a way to handle the situation with the 2 beers that don't seem to be all that carbonated?
Ok. Not purging the headspace means you have 14.7 psi absolute (psia) of something other than CO2 in the headspace. The absolute pressure equals gauge pressure + atmospheric pressure (14.7 psi) and carbonation levels are based on absolute pressure, but the charts and calculators adjust to gauge pressure (assuming 100% CO2 in headspace) since that is what you can set by reading the gauge.

So, at 30 psi gauge (psig) with 14.7 psia of air in the headspace, your effective CO2 gauge pressure is 30 - 14.7 = 15.3 psig. 15.3 psig at 50°F will give you 2.3 volumes of carbonation, if and only if you reached equilibrium with the amount of agitation you did.

With unpurged air in the headspace, your 18 psi works out to a 3.3 effective CO2 psig, which will only give you 1.9 volumes of carbonation, which would be under-carbonated for the beer styles you have.

You need to get all of the air out of the keg headspace before carbonating because of what's explained above, or you will be under-carbonated.

You also need to purge the headspace to get rid of the O2 that is 21% of the original air. This O2 will oxidize your beer in a matter of days, and will be particularly bad with hoppy beers, like your IPA. The rolling you did with unpurged headspace will accelerate the oxidation.

I recommend you run at least 10 pressurize and vent cycles at 30 psi to clear out the air and oxygen in the headspace as soon as you can. Then pressurize as per the chart below to get your desired volumes of carbonation. It is probably too late to save your IPA. It will still be beer, but the taste will probably be very meh.

Carbonation Chart.png


Brew on :mug:
 
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TeflonTom

TeflonTom

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Ok. Not purging the headspace means you have 14.7 psi absolute (psia) of something other than CO2 in the headspace. The absolute pressure equals gauge pressure + atmospheric pressure (14.7 psi) and carbonation levels are based on absolute pressure, but the charts and calculators adjust to gauge pressure (assuming 100% CO2 in headspace) since that is what you can set by reading the gauge.

So, at 30 psi gauge (psig) with 14.7 psia of air in the headspace, your effective CO2 gauge pressure is 30 - 14.7 = 15.3 psig. 15.3 psig at 50°F will give you 2.3 volumes of carbonation, if and only if you reached equilibrium with the amount of agitation you did.

With unpurged air in the headspace, your 18 psi works out to a 3.3 effective CO2 psig, which will only give you 1.9 volumes of carbonation, which would be under-carbonated for the beer styles you have.

You need to get all of the air out of the keg headspace before carbonating because what's explained above, or you will be under-carbonated.

You also need to purge the headspace to get rid of the O2 that is 21% of the original air. This O2 will oxidize your beer in a matter of days, and will be particularly bad with hoppy beers, like your IPA. The rolling you did with unpurged headspace will accelerate the oxidation.

I recommend you run at least 10 pressurize and vent cycles at 30 psi to clear out the air and oxygen in the headspace as soon as you can. Then pressurize as per the chart below to get your desired volumes of carbonation. It is probably too late to save your IPA. It will still be beer, but the taste will probably be very meh.

View attachment 766069

Brew on :mug:
Sounds good, thanks for the help. With a pressure and vent cycle what should the time of the operation be? Vent, then add in the 30 psi for a couple minutes then repeat?
 

doug293cz

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Sounds good, thanks for the help. With a pressure and vent cycle what should the time of the operation be? Vent, then add in the 30 psi for a couple minutes then repeat?
You only need to wait about 10 seconds after pressurizing to vent.

Brew on :mug:
 
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TeflonTom

TeflonTom

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Thanks, youve been a huge help! Glad I asked before I waited any longer. I'll go ahead and take care of this before I go to bed tonight.
 
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