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Compressed Air Pipe Sizing

SCFM + Pressure + Length → Pressure Drop · Pipe Size

When to use: Use to size compressed air distribution piping from flow demand (SCFM), system pressure (psig), and run length. Uses a simplified Darcy-Weisbach formula for compressible flow. Target pressure drop is typically 2 psi or less per 100 ft, with air velocity under 30 ft/s. Used for plant air, instrument air, and pneumatic tool systems.

System Parameters
Standard cubic feet/min
SCFM
Operating pressure
psig
Include equivalent lengths
ft
Recommended Size
4"
ΔP = 0.847 psi · 2.4 ft/s
Pressure Drop by Pipe Size
SIZEΔP (psi)STATUS1/2"9621.406✗ High3/4"2358.057✗ High1"705.201✗ High1-1/4"178.976✗ High1-1/2"82.806✗ High2"23.740✗ High2-1/2"9.763✗ High3"3.295✗ High4"0.847✓ OK6"0.109✓ OK
References
Target ΔP: 2 psi max per 100 ft run
Max velocity: 30 ft/s to reduce noise
Add 50% equivalent length for fittings
Instrument air: use stainless or copper pipe