About Pipe Flow, Head Loss & Pressure Drop Calculator
Calculate fluid friction head loss (h_f) and line pressure drop (ΔP) through commercial pipes using the Darcy-Weisbach equation with explicit Swamee-Jain friction factors. Computes volumetric flow in m³/h and US GPM.
Key Capabilities & Features
- Darcy-Weisbach head loss formula with explicit Swamee-Jain friction factor algorithm
- Calculates friction head loss (meters of fluid) and pressure drop (kPa and PSI)
- Computes volumetric discharge in cubic meters per hour (m³/h) and US Gallons per Minute (GPM)
- Roughness presets for PVC/plastic, commercial carbon steel, cast iron, and corroded piping
- Covers laminar, transitional, and fully turbulent hydraulic regimes
How to Use Pipe Flow, Head Loss & Pressure Drop Calculator
Set Pipe Dimensions
Enter inside pipe diameter (mm) and total one-way run length (meters).
Input Velocity or Flow
Set design flow velocity (e.g. 1.5 to 2.0 m/s for water service).
Review Pressure Loss
Inspect total head loss in meters and line pressure drop in kPa and PSI.
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Frequently Asked Questions
What is the Darcy-Weisbach equation?
The Darcy-Weisbach equation calculates head loss due to pipe friction: h_f = f · (L / D) · (v² / 2g), where f is the Darcy friction factor, L is pipe length, D is diameter, v is velocity, and g is gravitational acceleration.
What is a typical design water velocity in piping?
For commercial building and industrial water piping, velocities are typically maintained between 1.2 m/s and 2.4 m/s (4 to 8 ft/s) to prevent both pipe erosion and sediment deposition.