Originally Posted by Straight6TT
My kegs are naturally carbonated to the proper volume, but being served with beergas, you are saying they will lose pressure i.e. go flat over time?
That is what I'm saying. If you want 2.5 volumes of CO2 in your beer, and you serve at 40 degrees, you need to maintain ~12.3 psi of CO2 over your beer. If you have 75/25 beergas and you're applying 25 PSI, that means you have 6.25 psi of CO2 over your beer. That's only 1.9-2 volumes of CO2, which is undercarbed for many styles. If you're serving an English style ale or a stout, that might be fine, but for an American style ale, a Belgian, Hefe, IPA, etc. it's pretty low. If you crank down the temperature in your kegerator you can sneak some more carbonation into it with the beergas, but then your stout (or whatever you're pushing through the restrictor faucet) is going to be overcarbed and you'll probably get too much foaming when you pour. And like I said, the pours will be foamy until the carb level drops, which might take a little while.
I'm not totally sure how a restaurant/bar does it, but my guess is they blend the beergas themselves. So they have a tank of nitrogen and a tank of CO2, and they'll keep enough CO2 pressure on the keg to maintain the carb level, then apply nitrogen pressure as needed to push it up to the faucets.