The question of what pressure to run your beer gas setup seems to be a topic folks struggle with. Below is my attempt to clear this up.
I have easy accessibility to a 25/75 blend of CO2 and N2. When you see a blend the first number will always be CO2 the second N2.
I will use a target of 1.2 volumes of CO2 for the bourbon barrel stout. This is the same level used for Guinness.
Using a calculator like brewersfriend and my kegerator temperature of 38° we are informed we need a pressure of -2.5 psi to get 1.2 volumes. The important thing to note here is the result we are given is in psig for gauge. Our gauges are set to read 0 at 1 atmosphere or 14.7 psi at sea level.
- The first step is to first convert to psia or actual by adding the 14.7 psi for 1 atmosphere of pressure. If you are at high elevation you should look up the appropriate value for you.
-2.5psig + 14.7 = 12.2 psia - Next we account for the fact that our gas is only 25% CO2.
12.2psia / 0.25 = 48.8 psia - Now we convert back to psig so we know what to set our regulator to.
48.8 psia – 14.7 = 34.1 psig
McDantim has some great calculators. I use this one. It accounts for some additional factors like ABV and elevation.
