Steam Flow Calculator
Estimate steam mass flow through a pipe from pressure, pipe size and velocity — quick sanity check for steam distribution.
Inputs
Design: 80–120 ft/s for saturated, up to 200 for superheated.
Zero for saturated steam.
Results
Formula
ṁ (lb/hr) = ρ_steam × A × V × 3600; ρ_saturated ≈ 0.00286 × (psia)^0.9346.
Worked example
A 4-inch schedule-40 pipe (ID ≈ 4.03 in) carrying 100 psig saturated steam at 100 ft/s: ρ ≈ 0.258 lb/ft³, A ≈ 0.088 ft², ṁ ≈ 8,200 lb/hr.
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Frequently asked questions
What velocity should I design for?
80–120 ft/s for saturated steam mains, up to 150 ft/s for superheated. Higher velocities save pipe but cause noise and erosion.
Can I use this for wet steam?
Only as a rough estimate — wet steam has substantially higher density and different flow behaviour.
How accurate is the density formula?
Within ~3% of NIST steam tables from atmospheric up to 600 psig. For high-pressure or superheated service, use full steam tables.
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