Choosing the Right Trunk Line for Your Draft Beer System
Your draft system’s trunk line (also called insulated bundle line) is the highway that carries beer and cooling from the walk-in cooler to the taps. Correct sizing ensures balanced restriction, stable carbonation, and proper cooling across the full run.
Beer Line ID
Smaller inside diameters (ID) hold less beer, meaning:
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Less waste during cleaning
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Less cooling power required
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Higher restriction (better for shorter runs)
Sizing guidelines:
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1/4" ID: For runs up to 50 ft. ~0.30 lbs/ft restriction, holds ~1/3 oz/ft.
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5/16" ID: For runs up to 120 ft. ~0.10 lbs/ft restriction, holds ~1/2 oz/ft.
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3/8" ID: Standard for long-draw runs up to 200+ ft. ~0.06 lbs/ft restriction, holds ~3/4 oz/ft.
Additional restriction comes from elevation (~0.5 lb/ft) and the lines inside the tower and cooler.
Beer Line Material
All trunk lines use flushable barrier tubing to reduce oxygen permeation and protect beer flavor.
Insulation
Each trunk line includes:
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3/4" insulation tube with vinyl jacket or tape
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Moisture barrier and aluminum foil wrap for consistent cooling and condensation control
Length Planning
Always allow 15–20% extra length to cover bends, cooler routing, and tower connections.
Need assistance selecting the right trunk line? Contact us for help with your setup.
