Draught Operations > A Matter of Balance > Balancing Draught Systems

Having reviewed all the concepts behind draught system balance, let’s examine three example systems to see how these variables are adjusted to create balanced draught systems in several different settings.

Example 1: Direct-Draw System

• Beer Conditions:
  • – Beer temperature: 38°F
  • – Beer carbonation: 2.8 volumes of CO₂ per volume of beer
  • – Dispense gas: 100% CO₂
  • – Gas pressure needed to maintain carbonation = 14.5 psig
• Static Pressure:
  • – Vertical lift = 5 ft.  (Tap 5 ft. above the center of the keg)
  • – Static resistance from gravity = 5 ft. x 0.5 pounds/foot = 2.5 pounds
• Balance
  • – Applied pressure of 14.5 psi must be balanced by total system resistance
  • – Since static resistance equals 2.5 psi, a total of 12 pounds of system resistance will be needed:  Restriction = 14.5 – 2.5  = 12 pounds
  • – To achieve this: 4 ft. of 3/16” polyvinyl beer line (choker) @ 3 pounds per foot = 12 pounds)

Example 2: Long-Draw, Closed-Remote System

• Beer Conditions:
  • Beer temperature: 35°F
  • Beer carbonation: 2.6 volumes of CO₂ per volume of beer
  • Dispense gas: 65% CO₂ / 35% nitrogen blend
  • Gas pressure needed to maintain carbonation = 22 psig
• Static Pressure:
  • Vertical lift = 12 ft. (Tap 12 ft. above the center of the keg)
  • Static resistance from gravity = 12 ft. x 0.5 pounds/foot = 6.0 pounds
• Balance
  • Applied pressure of 22 psi must be balanced by total system resistance
  • Since static resistance equals 6 pounds, it has a total of 16 pounds of system resistance
  • Restriction = 22 – 6 = 16 pounds

    (120 ft. of 5/16” barrier @ 0.1 pounds per foot = 12 pounds & 1.25” choker = 4 pounds)

Example 3 of Forced-Air, 10-ft. run

• Beer Conditions:
  • Beer temperature: 33°F
  • Beer carbonation: 2.8 volumes of CO₂ per volume of beer
  • Dispense gas: 100% CO₂
  • Gas pressure needed to maintain carbonation = 10 psig
• Static Pressure:
  • Vertical fall = 10 ft. (Tap is 10 ft. below the center of the keg)
  • Static resistance from gravity = 10 ft. x -0.5 pounds/foot = -5.0 pounds
• Balance
  • Applied pressure of 10 psi must be balanced by total system resistance of 15 pounds
  • Since static resistance equals -5 pounds, the system has a total of 15 pounds of resistance
  • Restriction = 10 – (– 5) = 15 pounds

    (10 ft.of 1/4” barrier @ 0.3 pounds per foot = 3 pounds & 4 ft. of choker = 12 pounds) = 3 pounds + 12 pounds = 15 pounds

Direct Draw Draught System Balance

At 38ºF