Cross Main Pipe Sizing Calculator

Size cross main piping for sprinkler systems based on total flow demand and Hazen-Williams formula.

Input Parameters

Results

--
Minimum Pipe Size
in
--
Flow Velocity
ft/s
--
Total Friction Loss
psi
--
Friction Loss per Foot
psi/ft
Note: Cross mains carry flow from the riser to branch lines. Size to keep total friction loss within available pressure budget. Include equivalent lengths for tees, elbows, and other fittings per NFPA 13 Table 28.2.3.4.1.

Reference

Hazen-Williams: p = (4.52 × Q^1.85) / (C^1.85 × d^4.87) psi/ft Velocity = 0.4085 × Q / d^2 Total Friction Loss = p × L Max recommended velocity: 25 ft/s for cross mains