Keep your draft beer pouring perfectly and improve the quality of your brew by maintaining the proper pressure.
As CO2 enters a keg it displaces your beer at a constant pressure, replacing poured beer by occupying the space that otherwise would be empty. The empty space in the keg is referred to as "head space." The CO2 fills the head space and maintains the pressure inside of the keg at the PSI set on your CO2 regulator. Maintaining a constant PSI keeps your beer perfectly carbonated by preventing the CO2 that's dissolved in the beer from leaking out of the keg.
Store your air tank upright
Your CO2 tank will not work properly if it's not stored upright, and could even cause damage to your regulator.
Find your PSI
Most US-produced ales and lagers dispense well at 10-12 PSI, while stouts or other nitrogen-dispensed brews work well at 25-30 PSI. If you're having problems utilizing these general guidelines, check with the local distributor from which you got the keg; they may have a suggestion for that particular beer.
Too much pressure? Indicators and how to fix it:
Initially, too mush pressure results in fast pouring, extremely foamy beer. Think fire hose. Foam in over-carbonated beer will appear tight with large bubbles.
Fix over-carbonated beer by immediately adjusting your regulator to a proper, lower level and either pour off a few foamy pitchers or bleed off some of the extra pressure via the relief valve on the regulator. This way, your system can find its balance. If you leave your system at too high a pressure for longer than 24 hours, your keg will be permanently over-carbonated and excessively foamy.
Not enough pressure? Indicators and how to fix it:
If air pressure isn't high enough, your beer will be over foamy too, but it will look more loose than if there's too much pressure; small bubbles that are often described as "soapy" looking. Another sign that your beer is under-carbonated is if foam and/or bubbles actually rise into the beer line. If you don't raise pressure to a proper PSI soon enough, your beer will become flat.
To correct low pressure, first check to make sure your air tank isn't empty and that it's turned on. This seems like a "duh" suggestion but sometimes it's the simplest issue that causes the problem. Next, check your regulator to be sure it's set at the right level. If the tank is functioning and there aren't any obstructions in your air line, and your regulator is set to the correct PSI, then most likely your regulator or gauge needs to be replaced. Unfortunately, regulators do wear out and typically need to be replaced every 4-6 years or so.
Hope these pressure pointers do you and your draft beer some good. Cheers!