Beer Foam? Lowering Keg Pressure is Not the Answer


Beer flowing too fast and foamy? First thought is to turn down the CO2 pressure on the regulator, right? Wrong.

It is amazing how often service calls are made because the CO2 gas regulator has been improperly adjusted. The regulator has been turned way too low because the beer was too fast, but this fast flow is not even clear beer but foam! Instead of addressing the issue as to why there is foam, a natural inclination would be to somehow slow down this perceived fast flow so that clear beer will go into the glass.

It is helpful to understand carbonation to know a little bit about what’s going on inside your keg of beer as you dispense it. This will help you serve better draft beer.

Carbonation = Carbon dioxide dissolved in a liquid. Whether it is water (seltzer), soda, champagne or beer, dissolved carbon dioxide is the component of the drink that gives it fizz. This fizz is a natural by-product of fermentation that is produced by the yeast involved – a natural compound for use in beer. Carbon Dioxide or CO2 is a clear, colorless gas that is a key component of our atmosphere.

Many draft service calls encounter systems using 100% CO2, but the pressure setting to the keg is only around 7-8 PSIG. Doing a little detective work, the problem comes to light: the retailer says that if he used the recommended 12-14 PSIG, that a fresh keg just coupled would foam like the dickens and this foam was shooting out of the faucet.

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Further detective work finds that the keg was just delivered or was a backup in warm storage. Beer temperature was not 38°F, maybe closer to 50°F or worse. If the retailer lowered the pressure to 7-8 PSIG, the beer (foam) was easier to catch. As a matter of fact, they claimed that eventually the beer would clear. All that foam that was dumped out of the faucet was the actual carbonation in the beer. The beer’s gas content is reduced to the point of being flat. The retailer is now happy because the beer is going into the glass versus down the drip tray, but profit is being reduced.

Unfortunately, many retailers actually believe that the low 7-8 PSIG to the keg was ideal and the kegs should always foam when first coupled. The retailers’ pour cost of dispensing in this fashion sky rockets since most of the beer was going down the drip tray. Not to mention customers not asking for another pint. Who likes flat beer?

They would be better off placing a cup on top of the tap marker and wait until the next day to dispense. It takes that long for a warm keg to acclimate to the keg cooler.

The reason that tapping warm kegs results in foam is simple. The gas in the beer is very, very sensitive to temperature – particularly warm temperatures. This carbon dioxide gas is looking for any reason to jump out of the beer. More so when the beer is warm since gas expands when heated.

The bottom line for keeping pour cost low, resale high and to enjoy beer as the brewer intended is to manage your inventory to avoid dispensing from a warm keg while applying the correct PSIG. Keep your fingers off of that regulator if foam is barreling out of the faucet. Be patient and once the keg has acclimated, clear beer will appear.

And remember – beer has gas and its temperature trumps everything when dispensing.

For more information on how to serve the best draft beer, visit