Carbonating Nitro-Beers

I brewed an AG stout recipe and transfered the beer into my cornelius keg. I hooked up my CO2 tank and purged the head space. I am now trying to determine how to force carbonate this beer before I am ready to push it with my Nitrogen/CO2 tank.


Questions:

1. I was told that I should pressurize to only 1.2-1.5vols of CO2, but if I am serving with 32lbs of Nitrogen/CO2 (75%/25%), wouldn't I want to charge with 8lbs of CO2 since that would be equal to the partial pressure of CO2 before hooking up the mixed blend? - 8lbs@38°F is 2.2vols - what am I missing here? Thirty-two pounds has always worked perfectly in the past to push commercial stouts with a glorious cascade effect and perfect head - wouldn't I then pressurize to 8lbs of CO2 (2.2vols) for several weeks until fully carbed?

2. My CO2 tank is OUTSIDE the cooler (70°F), and the beer is INSIDE (38°F). If I want to charge my beer with CO2 at a pressure of 8PSI, do I have to adjust the pressure taking into account the temperature change? Do I set the pressure for the 70° temperature or the 38° temperature?

The 1.2-1.5 vols is probably based on 55F, not 38F.

The pressure from the regulator does not depend on temperature.

david_42 said:

The 1.2-1.5 vols is probably based on 55F, not 38F.

The pressure from the regulator does not depend on temperature.

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Where I get conflicting information is where people say to only lightly carb a nitro-beer to 1.2-1.5vols of CO2 (at ANY temperature), and yet when I ultimately hook up the mixed blend of gas I am sustaining a CO2 pressure of 8lbs (2.2vols) of CO2 (32psi with a mixed blend will be 24lbs of Nitrogen and 8lbs of CO2). My question is should I go with my gut and charge with 8lbs of CO2@38°F (2.2vols) until it is balanced, or will I end up over-carbing the beer for some reason - and if so, what IS the reason?

As far as the temperature question - if I have set my regulator to 8lbs of pressure at the tank (70°F) going into the cooler (38°F), is there a difference in the outcome of CO2 volume I will acheive in my beer if the CO2 tank was instead inside the cooler and also at 38°F? There is a 32° difference in temperature from the regulator at 8PSI outside the tank to the actual beer at 38°F inside the tank.

I know that force carbing a beer to a certain volume when both units (the keg and the tank) are at 70° calls for one pressure setting, and force carbing a beer to the same aformentioned volume when both units are at 38° calls for a far less pressure... If the tank is at 70° and the beer it is charging is at 38° - which pressure on the chart do I carb with - the 38° or the 70°? Or is there an equation for something in the middle?

I do not know what to suggest on the carbonating for the stout as far as co2 vs beergas, but for the setting of pressures, you set it based on the beer temp.

The temp of the tank does not matter. I have used mine with tank in the kegerator, and out, and I always set it based on beer temp.

cyberbackpacker said:

I do not know what to suggest on the carbonating for the stout as far as co2 vs beergas, but for the setting of pressures, you set it based on the beer temp.

The temp of the tank does not matter. I have used mine with tank in the kegerator, and out, and I always set it based on beer temp.

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Thank you both for your timely replies. I will be sure to let you know how it goes!