Originally Posted by AmusedBystander
What is beergas?
It's used with a stout faucet to give your beer a 'guiness type' pour (you know, with the cascading creamy head). You can serve any beer this way but it's typically done with dark beers. It's a matter of taste but I strongly prefer it for serving my stouts and even porters.
Basically the nitrogen doesn't readily dissolve into the beer like CO2 does so you can serve the beer with tremendous pressure (typically about 30psi) without worrying about the beer being overcarbed. You need this pressure to serve the beer with the stout faucet. The stout faucet has a little disk in it with tiny holes (a 'restrictor plate') that the beer is forced through. This is what makes all the bubbles in the cascading foamy head. If the beer has too much CO2 in it then it'll will just be all foam and will take forever to settle.. so that's why you use the beer gas - so you can serve with a lot of pressure but only have a lightly carbonated beer with a foamy but not overly foamy head.
It's a combo - beer gas + stout faucet. You need both for a 'nitrogen' served beer.