To pour a perfect beer you need to make sure the pressure of your draft beer system is set properly.
One of the trickiest parts of having a draft beer system is setting the pressure so that you don’t get either a trickle of liquid coming out of your tap or a blast of foam flying at you. How to determine the correct pressure for your draft beer system is a question we get often, and we’re here to help you find the right balance.
Common CO2 Keg Pressure Settings for Different Styles of Beer
Depending on the style of beer you are pouring there are some basic parameters that can be used to determine an ideal pressure setting. For most ales (including pale ales, IPAs, ambers, etc.) that come from the brewery with a carbonation volume of about 2.1 to 2.6, you want to set your regulator from about 7 to 13 psi. For lagers, a regulator set between 10 and 14 psi works best. Continental and light pilsners require slightly higher CO2 regulator settings, from 11 to 16 psi. Wheat beers, Belgian beers, and common American sours are generally the most carbonated beers, requiring about 15 to 20 psi. Stouts should be poured with beer gas and a stout faucet, using a nitrogen regulator at about 35 to 38 psi.
Determining the Right Pressure for Your Long-Draw Draft Beer System
The basic settings above are a great starting point for those that have kegerators or a direct-draw draft system. Things get a little more involved when it comes to complex long-draw draft systems. We have to take into account the path the beer takes from keg to tap to help determine the appropriate pressure (PSI). Luckily, there is a rather simple formula to determine this.
All you need is 3 factors: Length of Beer Line, Line Resistance, and Gravity. This section will walk you through how to determine each of these factors, and thus, the ideal pressure for your draft beer system:
Pressure = (Length of Beer Line in Feet x Line Resistance) + (Gravity x .5)
1. Determine Length of Beer Line
If you don’t know the length of your beer line, simply measure the length of line from your shank to your coupler. You will need this measurement to be in feet.
2. Determine Line Resistance
Line Resistance may also be called “Restriction Value”; the two terms are interchangeable. This just means the amount of pressure being pumped through a line. Every foot of beer line has a set, average Line Resistance. The smaller the Inside Diameter of your beer line, the higher the Line Resistance; The larger the Inside Diameter, the lower the Line Resistance. Below are two charts of Line Resistance for various common diameters of both vinyl and stainless steel beer lines.
Vinyl Beer Line
|Line Length||Hose Diameter||Line Resistance|
|1 foot||3/16″ Inside Diameter||2.20 lb|
|1 foot||1/4″ Inside Diameter||.65 lb|
|1 foot||5/16″ Inside Diameter||.40 lb|
|1 foot||3/8″ Inside Diameter||.20 lb|
|1 foot||1/2″ Inside Diameter||.025 lb|
Stainless Steel Beer Line
|Line Length||Hose Diameter||Line Resistance|
|1 foot||1/4″ Outside Diameter||1.20 lb|
|1 foot||5/16″ Outside Diameter||.30 lb|
|1 foot||3/8″ Outside Diameter||.12 lb|
Your beer line from tower to your keg measures 5 feet.
Your beer line is 3/16” Inside Diameter.
Multiply Length (5 Feet) X Line Resistance from the chart above (2.20 lb)
Line Resistance = 11 lb
3. Determine Gravity
The Vertical Rise or Vertical Fall of your draft beer system determines your system’s gravity. It is measured between the two horizontal planes of your system: the center of the keg and your faucet. On average, for each foot of gravity in your system a value of .45 PSI will need to be applied. You can round to .5 PSI to make this calculation easier.
Your faucet is 2 feet above your keg.
Your keg is 2 feet high.
Add your faucet height (2 feet) + you keg height / 2 (1 foot).
Gravity = 3 feet
(Note, in the end calculation, you will need to multiple Gravity by .5 PSI. We will walk you though this in the next step.)
4. Determining Ideal Pressure (PSI)
Now that you have each of the 3 factors, you are ready to determine the ideal pressure for your kegerator or draft beer system.
Use the formula from above:
Pressure = (Length of Beer Line (in feet) x Line Resistance) + (Gravity x .05)
Length of Beer Line = 5 feet
Line Resistance per foot = 2.2 lb
Gravity = 3 feet
(5 feet x 2.2) + (3 x .5)
11 + 1.5
Ideal Pressure = 12.5 lb
Because a draft beer system is a closed system, what you put in directly corresponds to what you get out. Setting your CO2 gauge correctly when you tap the keg will prevent both over- and under-carbonation. When the pressure of your system and the pressure you apply from your regulator are equal, your system is balanced. If your system is balanced, you can pour about one gallon of beer per minute, or 2 ounces a second!
There are a few ways to tell if your pressure is not set correctly.
Signs of Over-Carbonation
- Looks: It resembles a pint of seltzer water, with lots of small bubbles rushing up from the bottom of the glass.
- Taste: It’s sharp and acidic. When you combine CO2 with water you get carbonic acid. Bitey beers that weren’t intended to be bitey are not fun to drink.
- Smell: You may be able to pick up a bit of the acid as the bubbles pop in the general vicinity of your sniffer.
- Texture: Feels like Pop Rocks in your mouth (in a bad way).
Signs of Under-Carbonation
- Looks: It’s practically still, like apple juice.
- Taste: Flat and dull. Not a whole lot going on.
- Smell: You perceive less aromatics than you would with a properly carbonated beer.
- Texture: It feels thinner or more watery than you would expect it to.
Setting your draft beer system to the right pressure will help you pour the perfect beer and eliminate waste. For more information about CO2 when it comes to draft beer systems, check out our 8 Answers to Frequently Asked Draft Beer CO2 Questions. If you’re still having problems with pouring pints from your kegerator or draft beer system, then check out our tips for Troubleshooting Your Draft Beer System.
KegWorks has been selling cool tools for drinking and serving knowledge on tap since 1998. We are all about enjoying good drinks with good friends.
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