I was at a picnic where someone brought us a keg of beer. They left the keg, the tap, and bid us to have fun and left. And there we stood, baffled how to get this to work. Someone figured something out and we got our cups full of beer froth with a tiny bit of beer on the bottom.

I wouldn't want such a situation to repeat, so could someone give me a brief guide of how to assemble a beer stand (keg+tap) without getting it to explode into my face, get a proper stream going (instead of just a lot of froth), and pour it properly?

  • Pouring is rather simple. Start with the glass at about a 45-degree tilt, with the spout close to the inside of the glass. Slowly pull away and tilt to vertical as it becomes needed when the glass is near full. Stop just before it is completely full, to allow room for the head to rise. As for tapping a keg, I can't help you there.
    – user162
    Commented Jan 22, 2014 at 22:08
  • 1
    Another thing that can affect the poor is if you don't fully open the tap: this might have been the cause of the excessive head you got. Commented Jan 23, 2014 at 5:38

1 Answer 1


For a keg system to pour beer without excessive foam, the system must be balanced, and the serving line/faucet free of obstructions. Serving beer at too high a pressure, or through a half-open faucet/tap agitates the beer, causing the foam you saw.

The system is balanced by having the pressure inside the keg set to just a touch more (0.5-1psi) than the pressure resistance outside the keg. The pressure resistance outside the keg comes from the beer line and the tap - the longer the beer line, the more resistance. Also any increase in height between the keg and the end of the tap will increase resistance.

But even if the system was originally balanced, with the right dispensing pressure or adequate length of beer line, there are still some things working against you:

  • if the keg has been sloshed about, some of the carbon dioxide will have come out of the beer and into the headspace, creating more pressure. It takes several days for this to equalize again.

  • as the keg warms, the pressure inside the keg increases, since gas has a higher pressure at higher temperature with the same volume.

If you have a keg that is overpressured, you have 3 basic options:

  1. reduce the pressure inside the keg by venting some of the gas. Some kegs have a pressure relief valve that can be pulled to reduce pressure. But do it in small bursts, and try the beer after each until you see that the beer comes out not to quickly.
  2. increase the resistance outside the keg by using a longer beer line and/or placing the keg somewhere low and serving the beer higher. (e.g. keg at ground level and stand up to serve the beer.)
  3. dispense a large amount beer to a large jug - removing beer from the keg will reduce the pressure in the keg, and keeping it in a jug gives time for the head on the beer to settle down. While you're waiting, just pour some more beer from the keg - this will come out slower and have less foam.


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