Determining the Right Pressure for Your Draft Beer System

regulator
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!

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

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 determining 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.
Draft Beer System Parts

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!

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24 Comments

  • Mark May 21, 2015 @ 3:46pm

    I have 2 1/6 barrels and I wait till they’re both empty to change them. When I do, I can never get them to pour at the same pressure even though the run off the same tank and regulator. All lines are equal at 5′ long. When they get down to 3/4 full, they balance out. But at first, one will come out like a fire hose and the other just a trickle.

    • Caleb Houseknecht May 22, 2015 @ 9:10am

      Hey Mark,

      That seems odd. Are they different styles of beer? The only thing I can think is if they’re different styles, your system is trying to find equilibrium, and once it’s balanced, they are pouring properly. Let us know!

  • Hugh Topham June 18, 2015 @ 9:53am

    I am building a remote draft system from my basement to my taps. total rise is 11 feet, total line length is 15 feet. considering using 1/16 beverage line in a commercial trunk. Tap tower has 3 standard flow control faucets and two guiness taps. Can I serve both tap styles off the same tank using the same gas blend on regulators set up in series to give me the different serving pressures? Can I fill co2 tanks with the beer gas? My regulator is currently a lab grade o2 model set up on a standard 20lb tank filled with co2.

    • Caleb Houseknecht June 18, 2015 @ 10:20am

      Hey Hugh,

      This is a pretty complex question, but we may be able to help. I’m going to give you the number of one of our draft beer specialists here, Jim Rozycki. You can reach him directly at (716) 362-9212 ext. 198.

  • Evan Holloway August 27, 2015 @ 5:19pm

    I have a very unique system. Two separate bars fed from the same keg draw system. One bar runs an underground line (3/8ths) 160 feet, with a tower approx. 6ft off the ground. The second bar is an overhead 120ft run (also 3/8ths line), dropping into wall mounted taps approx 6.5ft off the ground. To further complicate matters, we have a keg shelving unit designed with space in mind, meaning half the kegs are on the ground, the other half approx. 4ft up. We have a bulk Co2 unit (400lbs) and a GreenAir nitrogen regulator for blending and pressures, so we don’t have to worry about switching canisters or the like. Any suggestions how I should calculate my pressures?

    • Andrew November 20, 2015 @ 8:19pm

      In the industry we typically set systems like that to 22lbs and play it by ear. When you have 2 dispensing locations like that, they can act differently. I’d recommend getting the one furthest away pouring correctly, and then messing with restriction of your lines going to the closer location by adding 3/16th line.

  • Chris Floyd September 13, 2015 @ 3:59pm

    Can you tap, untap, then retap a quarter barrel?

    • Caleb Houseknecht September 15, 2015 @ 11:05am

      Hey Chris,

      You can indeed, but if you’re using an air pump, make sure you drink it quick and keep it cold or else the CO2 will fill the empty space and the beer will go flat.

  • Shawn January 12, 2017 @ 9:56am

    I’m building a keezer that will be kept in a closet with taps on the other side of the wall behind bar. I have 1/4 line / parts available that I’d like to use – but not sure if it will work or I need to move down to 3/16. Any help appreciated – here’s some details:
    – 4 kegs / taps
    – 4-way CO2 secondary regulators
    – from keezer to wall tap: ~5-6 feet with ~3ft vertical -line to run through PVC tubing, cooled via blower from inside keezer, with an insulated box for shanks.

    Key Question: Can I get 1/4 line to work for this system end to end – or would I need to run a ton of line to increase resistance more?

    Appreciate any help!

    • Shawn January 12, 2017 @ 10:14am

      Here’s the math I’ve done based on available keg line/regulation calculators I’ve found:

      Assuming:
      – Keg Pressure @12 PSI, targeting 1 PSI at tap
      – Height 1 foot above keg
      – 1/4 line resistance of 0.85
      (12-1-(1/2))/0.85 = 12.35 length needed.

      That said – any confirmation / feedback appreciated

    • Caitlin January 17, 2017 @ 9:22am

      Hey, Shawn! The three foot vertical is going to be a problem without resistance increasing. You may want to splice it to 3/16 at that point.

  • Ted MacDonald March 18, 2017 @ 3:47pm

    Is there a minimum pressure? These formula seems to to just overcome line resistance and the gravity needed to get the beer to the faucet. If I do the calculation with 5 feet of 1/4 hose with faucet 1/2 foot above the 2 foot high keg I get 4 psi. It would seem you need a certain pressure just to keep the beer carbonated.
    I have a 30 litre keg in a fridge with the a hole drilled through the door for the shank and faucet.
    Thanks

  • Scott March 18, 2017 @ 10:28pm

    Balancing issues. Every equation I come up with ends the same, and I don’t think I’m balanced although my beer is pouring well in terms of carbonation, but it is a really slow pour.
    Specs:
    – 5/16″ vinyl line
    – 1′ height (center of keg up to the tap)
    – line length 6.5′
    – temperature is 4C (39.2F)

    Anything more than 4psi and I get wild pours. Of course at 4psi it take a long time to pour a pint (like 30 seconds approx.) I’m thinking I need a lot more line resistance (longer, narrower). Thoughts anyone ????

    • TedM April 8, 2017 @ 9:45am

      Scott: I think we may be having the same problem. Here is another article on balancing your system. It basically says set your psi to around 12 and use hose length / diameter /tap height to reduce pressure at tap to near 1. I think in fridge systems with a shorter run have opposite problems to commercial systems that have longer runs.

      http://beersmith.com/blog/2011/07/14/keg-line-length-balancing-the-science-of-draft-beer/

      • TedM April 8, 2017 @ 10:09am

        Here is a great explanation on Youtube complete with spreadsheet.

        • TedM April 8, 2017 @ 9:40pm

          Here is the link. I changed my 3/16 hose length from 4 to 10 feet and it really worked. Fixed the foam problem. It pours slowly but I will experiment with length on my next keg.
          https://www.youtube.com/watch?v=w6whE1jrVQ4

  • TedM April 8, 2017 @ 9:03am

    After doing a bit more research I think one point of the article is not necessarily to reduce the psi but to keep the original psi up, say 12 but to use a combination of length of hose and diameter to lower the psi at the tap. So lengthen the hose to reduce psi on gauge, maybe 12 to around 4 at the tap by having a longer hose.

    Could the author of the article or another export confirm this?

    • Scott April 24, 2017 @ 5:59pm

      TedM – thanks so much for the help!! I fully understand the principle of high pressure at the keg and low pressure at the tap. I am changing kegs today and am going to use 12′ of 5/16 ID line and see where that puts me. Unfortunately, the formula you had me look at earlier didn’t seem to solve anything, as it was telling me to use 134′ (or something) of line. I’ll post here to let you know how it goes.
      So I am going to have 12′ of 5/16 ID line. Center of keg to tap is about 9″ (.75′). I’m going to keep the line coiled as flat as I can on top of the keg, to avoid any peaks & valleys in the line. Fingers crossed!! Then I will play with my pressure and see where that puts me. I can always drop my line lower if needed as well.

      • ScottM April 27, 2017 @ 10:46am

        FAIL. I am about ready to pull my hair out. Let me be very clear. My lines, tap, spigot, fittings, connections etc are all clean. So… I have fridge temperature at 3C (38F). The center of the keg is 9″ below the tap. I have 12′ of 5-16″ ID vinyl tubing running from the keg to the tap. The tubing is coiled flat and laying on top of the keg. There are no peaks or valleys in the line run. And I still get nothing but wild pours and foamy beer on every pint. My pressure is set currently and 4psi. And I have had my gas regulator checked and calibrated. I am at a complete loss.

        • Caitlin April 28, 2017 @ 1:57pm

          Hi, Scott. You should try raising the pressure. We recommend 10-12 psi for 5 ft of 3/16″ line which has more restriction.

          • ScottM April 29, 2017 @ 8:47am

            Caitlin,
            Thanks!! I spent a load of time on Friday researching formulae, set ups etc. And the consensus data I found matches with what you said. My exact specs I’m going to try are 3/16″ line, 5′, 10 psi. Seems to be the general agreed specs. Fingers crossed…

          • Caitlin May 11, 2017 @ 9:53am

            Good luck! Let me know if it works out.

  • Ted May 24, 2017 @ 6:12am

    Hi,

    I understand how the different length and diameter of lines and gravity play a part in pressure needed to pass the beers from the kegs to the taps. Hence the pressure needed to pass beer out in a balanced manner is sum of the pressure from tubing and gravity.

    But firstly, should we consider the pressure at the facet to be 1 psi? I am assuming the formula mentioned in the article is setting the facet psi to be 0

    Secondly, as different beers have different co2 volumes and are served at different temperatures, hence they require different gas pressures to be expelled from the keg. In considering the ideal gas pressure to ensure the beer is neither over or under carbonated AND the overall system is balanced, I would need to have different tubings lying around? or to shift keg higher or lower to achieve this?

  • AdamJ July 8, 2017 @ 7:03am

    Hello.

    So I am looking at an 8 faucet cooled tower setup here. I sold house with my old kegerator. In my new house I am going to put the faucet on a bar upstairs (first floor). I just ordered a 17.5 cb ft chest freezer for the basement. I want to then run the lines up from the keezer. I am trying to figure out what diameter lines to use. It looks like your tower have lines connected already and that I should use 3/8 tubing from the keezer and then have them connect and restrict down the last six feet? Is that the best way to do this? I would rather have size lines run from keg to tap and have no coupler to worry about teaks. I plan to inclose the lines in insulated pvc pipe.

    So can I just use a single id vinyl tubing and if so what should that be for 18-20′ of line with approximate lift of 14′ (top of keg to tap)?

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