Fire protection hydraulic calculations use the Hazen–Williams formula to turn flow, pipe size and pipe roughness into friction loss. Enter the flow, pick the pipe and its C-factor, add the length plus the equivalent length of the fittings, and you get the loss in bar and psi together with the water velocity.
How to use it
- Enter the flow in the pipe section (L/min) — the sum of all sprinklers downstream of that point.
- Select the pipe size; the internal diameter of schedule 40 steel is filled in, or type your own.
- Use C = 120 for wet steel systems and C = 100 for dry pipe and preaction systems.
- Add the equivalent length of elbows, tees and valves to the straight length before reading the total loss.
Step-by-step guides
- Sprinkler Hydraulic Calculation: A Step-by-Step Worked Example
- Fire Pump Sizing to NFPA 20: Rated Point, Curve Checks and Jockey
More free tools
- Sprinkler Hydraulic Calculator — Full Remote-Area Calculation
- Sprinkler Flow & Pressure Calculator (q = K√p)
- MEP Unit Converter — kW, BTU/h, TR, CFM, L/s, bar, psi
- All free MEP calculators
- MEP Library
Results are for preliminary design and checking. Always confirm against the standard edition and local regulations that apply to your project.
Online course · certificate included
Fire Protection & Suppression Systems Design (NFPA)
20 narrated modules with animated diagrams, two complete worked projects (DWG + DXF), the Fire Calc Workbook and an online calculator.
Modules 1–3 are free, no account needed · full course €15,00 one-time