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
You get
- Line length (ft) 3
Details, formula, and sources
at balance the applied CO2 pressure equals the line restriction (R per foot x length) plus the rise (0.5 psi/ft) plus the faucet (~1 psi), so line = (pressure - 0.5 x rise - 1) / R. A 12 psi system with a 4 ft rise on 3/16" vinyl (3.0 psi/ft) needs 3.0 ft of line. Set the pressure to the carbonation level first, then balance the line; restriction values are nominal per tubing size (3/16" vinyl 3.0, 1/4" 0.85, 3/16" barrier 2.2, 5/16" 0.4 psi/ft). Per the Brewers Association Draught Beer Quality Manual; measure the pour rate and trim.
line_length_ft = (applied_pressure_psi - 0.5 x rise_ft - 1) / R, where R is the tubing restriction (psi/ft): 3/16" vinyl 3.0, 1/4" vinyl 0.85, 3/16" barrier 2.2, 5/16" vinyl 0.4.
Draft-beer line balancing (the Brewers Association Draught Beer Quality Manual system-balance equation), by name; the dispense system and the beer govern.
The system-balance relation (applied pressure = total restriction) is published draught-beer practice; the tubing restriction is a nominal material property.
Estimate. AHJ and licensed professional govern.
Field names used by the API: applied_pressure_psi, rise_ft, tubing_type, line_length_ft
- Tubing restriction 3/16" vinyl 3.0, 1/4" vinyl 0.85, 3/16" barrier 2.2, 5/16" vinyl 0.4 psi/ft (nominal, cellar temp)Brewers Association
- Rise and faucet 0.5 psi per foot of vertical rise, plus ~1 psi faucet allowanceDraught Beer Quality Manual