Getting Too Much Head???

David Green of Micro Matic's Dispense Institute is stressing proper technique when running glycol.

David Green of Micro Matic's Dispense Institute is stressing proper technique when running glycol.

Last week was spent learning the ins and outs of draft beer systems through Micro Matic's Dispense Institute in Northridge, California. The hands-on training experience with industry experts was packed with one-on-one teachings about dispense system installations (i.e. direct draw, short draw and long draw with glycol), cleaning techniques, and calculating resistance as beer travels from keg to faucet. Summarizing the class requires a printing press. However, a simple read explaining the hows and whys of foamy beer will save time, money, and painful trips to purchase over-the-counter headache medication.

Beer Temperature  

The target temperature for (most) beers are 38 degrees Fahrenheit where CO2 is stable and happy. By increasing the temperature, even one degree, CO2 becomes pissed off, agitating the beer and causing vast amounts of foam. Beer in the range of 38-44 degrees may appear unaffected, but it's warming up for chaos. Cross the 45-degree threshold and CO2 turns rapid, causing beer to froth like a milkshake. Every 2-degree increase in beer temperature results a rise in CO2 pressure by 1-pound. Therefore, a beer at a temperature of 48 degrees Fahrenheit is under an extra five pounds of force; and this five additional pounds will need balancing (more on this later). 

Warming a 1/2 BBL of beer ten degrees can two hours. However, lowering beer by ten degrees may take twenty hours. Therefore, keeping beer away from the sun and on ice is urgent.

Two easy methods to measure beer temperatureboth using a thermometer. 

It might look like pee, but a glass of yellow fizz is the perfect guinea pig practicing temperature readings . 

It might look like pee, but a glass of yellow fizz is the perfect guinea pig practicing temperature readings . 

1) Attach the keg with the coupler and pour beer from the faucet. Stick the thermometer in the center of the liquid but keep it away from the glass's edge. 38 degrees is the goal.

2) Hook up a party pump but don't press down. A carbonated keg of beer is under enough pressure to dispense beer for a temperature reading. Remember, party pumps use air (part oxygen) to move beer from the keg to a cup. Oxygen is a killer of flavor, so by pressing down, it's being injected with a healthy shot of oxygen. Allow oxygenated beer to sit, and it will take on flavors of stale cardboard.  

By measuring the beer temperature, we can now calculate how much extra pressure is inside the keg. 

Tip Everyone's equally guilty of putting ice on the top of kegs. However, beer efficiently cools from the bottom up. The head of a keg is only gas. When dispensing beer, all liquid is pulled from the bottom up; so if ice is on the keg's crown then only gas is being cooled. 

Applied Pressure 

Applied pressure is determined by the keg temperature. Applied pressure is the driving force of the beer system, think "engine." At a serving temperature of 38 degrees, a beer will be kegged at 2.5-2.7 volumes (click here for a table pressure chart) requiring 13 psi of CO2 to drive it from the keg to the faucet, and 13 psi of resistance to match. The resistance is important because it keeps the beer together and prevents it from foaming. (Calculating resistance is determined by measuring equipment hardware, gravity - lift or drop, altitude, and resistance from the beer line). For more info on measuring resistance click here).

If you're using a jockey box, you'll likely be using 100+ feet of 1/4" stainless steel coil to cool the beer. Steel is excellent, but it applies 3 pounds of resistance per 10 feet of line. Therefore, a beer pushed from keg to faucet through 100 feet of steel needs a kick of 30 psi of CO2. Anything less and expect a frothy milkshake. Below are two jockey box scenarios: 

TIP  Resistance = Applied Pressure

Scenario One: 

Beer: Kegged at 2.5-2.7 volumes = needs 13 psi of applied pressure
Jockey Box Restrictions: equipment + elevation = 3 psi
Line Restriction: 100 feet of steel coil = 30 psi
Beer temperature: 38 degrees Fahrenheit = stable so no need to increase pressure.

Resistance = 13 psi
Applied Pressure = 33 psi

The beer needs an extra 20 psi boost of CO2 so the beer will stay together and not foam.

Scenario Two: 

Beer: Kegged at 2.5-2.7 volumes = needs 13 psi of applied pressure
Jockey Box Restrictions: Equipment + Elevation = 3 psi
Line Restriction: 100 feet of steel coil = 30 psi
Beer temperature: 48 degrees Fahrenheit = not stable, needs +5 psi of CO2.

Resistance = 13 psi
Applied Pressure = 38 psi

The beer needs an additional 25 psi boost of CO2 to keep it from foaming. 

If you want cool, clean and carbonated beer, it begins with a properly built draft system.

If you want cool, clean and carbonated beer, it begins with a properly built draft system.

Cleanliness

Cleanliness is key for a million reasons. Beer is alive, and given the right conditions, it will grow. Gunky faucets and lines are a result of bacteria growth, which will harm a beer's flavor and contribute to foam. For cleaning tips and instructions click here.

Cleaning faucets, couplers and lines to prevent bacteria growth is key. Draft systems must be cleaned every 2-weeks, but weekly cleanings are even better. Also, jockey boxes aren't an everyday tool, so cleaning these after every use is equally important. 

From home brewers to bar owners, foamy beer is an issue everyone will encounter. But by maintaining the correct temperature, applying the right amount of pressure and keeping shit clean, 90% of beer pouring problems will be eliminated (10% is operator error).

If you have questions, please don't hesitate to comment below. We don't know everything, but we're not afraid to ask someone who does. Best of luck.