Draft Beer Line Balancing
The beer-line length that balances a draft system so it pours right, not foamy or slow.
Example
You enter
- Applied CO2 pressure (psi, = carbonation level) 12
- Vertical rise, keg to faucet (ft) 4
- Beer line vinyl_316
- Tower / fixture resistance (psi, 0 if none) 0
You get
- Line length (ft) 3.333
Checked against published worked examples from: Brewers Association.
Details, formula, and sources
Scopeat balance the applied CO2 pressure equals the line restriction (R per foot x length) plus the rise (0.5 psi/ft) plus any tower resistance (faucets and couplers are negligible), so line = (pressure - 0.5 x rise - tower) / R. A 12 psi system with a 4 ft rise on 3/16" vinyl (3.0 psi/ft) needs 3.3 ft of line. Set the pressure to the carbonation level first, then balance the line; restriction values are the manual's Table 4.1 (3/16" vinyl 3.0, 1/4" 0.85, 5/16" 0.4, barrier 1/4" 0.30, 5/16" 0.10, 3/8" 0.06 psi/ft). Per the Brewers Association Draught Beer Quality Manual; measure the pour rate and trim.
Formula or tableline_length_ft = (applied_pressure_psi - 0.5 x rise_ft - fixture_psi) / R, where R is the tubing restriction (psi/ft, DBQM Table 4.1): 3/16" vinyl 3.0, 1/4" vinyl 0.85, 5/16" vinyl 0.4, 1/4" barrier 0.30, 5/16" barrier 0.10, 3/8" barrier 0.06; 3/16" barrier 2.2 is not a table value.
Source and editionDraft-beer line balancing (the Brewers Association Draught Beer Quality Manual system-balance equation), by name; the dispense system and the beer govern.
Free accessThe system-balance relation (applied pressure = total restriction) is published draught-beer practice; the tubing restriction is a nominal material property.
What governsEstimate. AHJ and licensed professional govern.
API field namesapplied_pressure_psi, rise_ft, tubing_type, fixture_psi, line_length_ft
- Tubing restriction 3/16" vinyl 3.0, 1/4" vinyl 0.85, 5/16" vinyl 0.4, 1/4" barrier 0.30, 5/16" barrier 0.10, 3/8" barrier 0.06 psi/ft (nominal, cellar temp); 3/16" barrier 2.2 is offered but is not in the tableBrewers Association Draught Beer Quality Manual, 4th ed. (2019), Table 4.1
- Rise and fixtures 0.5 psi per foot of vertical rise (the manual's convention; water is 0.43); couplers and faucets negligible; a tower 0-8 psi per its maker, entered as the fixture resistanceDraught Beer Quality Manual, Ch. 4