It need's to be on a blended gas of 75%N/25%CO2, just like Guinness.They carbonate the beer to about 1.4 volumes first, then pressurize kegs to about 35 psi at 38F with the
blended gas to nitro the beer before shipping out. There's probably enough resistance from the restrictor plate in the faucet to work with most line set-ups. You need the high percentage of nitro to get the small, creamy, and tight head that we could eat with a spoon, it comes from the nitro breaking out of solution as it come's through restrictor plate.This won't happen on straight co2 alone or even the beer gas blend of60%Co2/40%N. It's to much CO2 and not enough nitro, you would be overcarbed at the needed 30psi and lack the nitro to get proper effect. Straight nitro will give you no carbanation at all, so that won't work at all. At our pub I carb my stout in our uni-tanks at 6-8 psi/@45F for
about a week, this is after fermentaion,crash cooling and racking off yeast of course. Then I keg off uni-tank into 1/2 BBL kegs, and put them under 30-35psi head pressure of the 75%/25% nitro @ 38F for a week or so, and you should be good to go. hope this help's. Cheers!!!