Calibrate and Know Your Number to Reduce Foam

While taking troubleshooting phone calls, the first question I always ask (since it’s normally the number one issue) is, “what is the temperature of the beer in your keg?” The most common answer? “Cold.”

Great. That’s helpful. There’s no pressure setting for “cold”. You need a number. Fahrenheit, Celsius, it doesn’t matter…as long as it comes from an accurate thermometer.

Not just any thermometer will do. It’s best practice to use a calibrated thermometer at all times. It could be an expensive one, but it doesn’t have to be. Cheap ones normally work well, too. Once you determine the temperature of your keg using a calibrated thermometer, then you know what CO2 pressure is being applied to the beer in the keg. Do not underestimate the importance of this number. The CO2 gas in the beer will tell you if you’re off, as it will foam sooner or later.

Calibration is easy, and the resources are generally readily available. All you need is a beer glass, ice (crushed is ideal), and water. Fill the glass with ice, and then water. Grab another hand full of ice and stuff it into the glass. Swirl your thermometer probe around in the ice water. It should read 32˚ F. If not, either adjust the thermometer so it does read 32˚ F. If it’s non-adjustable, fudge whatever degree required when taking the temperature of your beer.

The key temperature number you should target is that of the beer in the keg. For a simple direct draw kegerator, or those systems that utilize 3/16” ID beer line only, determine this temperature by pouring a beer in a glass and either dump or chug (acclimate the glass with the beer). Next, pour another beer in the same glass and use the calibrated thermometer to determine temperature. Adjust your pressure accordingly.

If your beer is 38˚ F, has 2.5 volumes of CO2 gas, and you are dispensing at sea level (1-1000’), then your pressure to the keg should be 13 PSIG. For every 2˚ temperature difference, adjust one psig – up for warmer, down for cooler. Each 2,000’ change in elevation above sea level requires an additional increase of one PSIG.

Limit the amount of foam by knowing that exact temperature number. Calibrate your thermometer on a regular basis. Keep that number constant, from the keg to the faucet, use the correct pressure, and enjoy trouble-free dispensing!