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Draft Beer 101

Determining the Right Pressure for Your Draft Beer System

A common question we get from our customers is: “At what pressure should I set my CO2 regulator for my beer to pour perfectly?” It’s a great question. To pour a perfect beer you need to counter the pressure flowing through your system with a regulator. 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!

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There is a rather simple formula to determine the appropriate pressure (PSI) for your draft beer system.

Pressure = (Length of Beer Line in Feet x Line Resistance) + (Gravity x .5)

All you need is 3 factors: Length of Beer Line, Line Resistance, and Gravity. This article will walk you through how to determine each of these factors, and thus, the ideal pressure for your draft beer system:

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″ Inside Diameter 1.20 lb
1 foot 5/16″ Inside Diameter .30 lb
1 foot 3/8″ Inside Diameter .12 lb

Example:
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.

Example:
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)

Example:
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

Setting your draft beer system to the right pressure will help you pour the perfect beer and eliminate waste.

So, get pouring.

If you need more help with figuring out the appropriate pressure for your draft beer system, or another draft beer questions, leave a comment below or hit us up on Facebook!

KegWorks

KegWorks

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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