Watson McDaniel Steam Design Guide

STEAM TRAP APPLICATIONS DRIP LEG DESIGN

Figure 1:

Proper DRIP LEG Designs

DRIP LEG DESIGN CRITERIA: 1) Locate prior to valves, bends in pipe (direction changes), low points, end of line and straight piping runs (max. 200 ft. apart). 2) Diameter: • Drip leg diameter (D L ) to be equal to steam main diameter (D) for steam main sizes up to 4” • Drip leg diameter (D L ) may be half the steam main diameter (D) for steam main sizes over 4”, but not less than 4” 3) Length (L): • For systems with automatic start-up, L to be 28” minimum (= 1 PSI minimum head pressure) • For systems with supervised start-up, L to be 1.5 x D L , but not less than 8”

FTT Trap

Strainer

Gate Valve

Drain Valve

DRIP LEG Draining Steam Main

DRIP LEG Before Regulator orControlValve

Isolation Valve

WFT Trap

Strainer

To condensate return line

Drain Valve

85

Tel: 610-495-5131 • Pottstown PA • USA •• www.watsonmcdaniel.com

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