Kegging pressures - What's the deal??

HopHeadHowie · Jul 19, 2012

I am a little confused. If the "serving pressure" is less than the original pressure used to obtain the volumes required for proper carbonation, won't it eventually be too low and go flat? My understanding is that "Serving pressure" is just an amount sufficent to obtain a good pour taking all other factors into consideration such as resitance of beer line etc. But doesnt it still need to be under sufficent pressure to prevent it from going "flat". The reason I ask is I had a keg that was dialed in absolutely perfect.....the carbonation was right and the serving pour perfect. But after a few weeks it got flatter and flatter with no change to serving pressure at all. What's the deal?

LarryBrewer · Jul 19, 2012

Correct, when the keg pressure it turned down, CO2 goes back out of solution, and the beer goes flat. If you turn your regulator down, beer can also go backwards up the gas line and foul the regulator (nasty mess).

Think of it this way, if you are having a party and plan to drink the entire keg in one night, then the concept of serving pressure makes sense. However, if you are planning on keeping the keg around for a long period of time, then you want to set the regulator for the desired volumes of CO2 and leave it. You can adjust your pour by getting a longer line. Some people use an 8ft line between their keg and tap so there is less foam. I get by just fine with a 3 ft line, 38F, and a PSI setting of about 10. There is still some foam in my pint glass, just not enough to annoy me too badly.

Here is a link with more info:
http://www.brewersfriend.com/2009/07/18 ... -pressure/

BrewHop · Jul 20, 2012

I have wondered about this too. The "simple" solution is to purge CO2 and turn down the regulator before you pour the beer. Whe you are done serving then turn it back up. I have also read that people will put twisted peices of plastic in their down tubes to disperse the CO2 more effectively to prevent foaming and such (should probably google search that one)... I just deal with a little foam myself, or turn it down and back up which is kind of a pain.

chessking · Jul 20, 2012

Leave the pressure alone and get some longer beer line. Plastic is cheep.

cearum · Jul 20, 2012

I also got myself a Perlick Flow Control Faucet. It's an absolute dream and saves on trying to fit 8 feet of beer line in my kegerator. It can also be adjusted on the fly. So if your line isn't as cold the first pull, you can turn it down so it doesn't foam as much. Then turn it back up once it gets to a reasonable temperature. As they state on the website, it can also be useful for different size/temperature glasses.