Formulas - Calculating Drip Leg Sizing
Drip legs should be installed roughly every 300 feet and never more than
500 feet. In a supervised warm up drip legs should be minimum of 10 inches
long. Drip legs on automatic warm up systems should be a minimum of 28 inches
long. As a rule of thumb drip leg length should be 1.5 times the diameter of
the steam main. Drip leg diameter should match steam mains up to 4 inches.
Above 4 inches the drip leg should be at least half the diameter of the steam
main.
NOTE: Drip legs that are too narrow can cause a venturi “piccolo” effect
that actually pulls condensate from the trap.
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