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Hydraulics
Pressure Drop Calculator
Enter values in the stated units. Example inputs are provided to help you explore the method.
Results
Your results will appear here after calculation. Changing an input clears the previous result.
Method & assumptions
- Calculates pressure drop using the Darcy-Weisbach equation
- Uses Darcy friction factor: 64/Re below Re 2300, otherwise the Swamee–Jain approximation. The 2300–4000 transition range is uncertain; this implementation does not reproduce EPANET’s transitional interpolation.
- Assumes steady, fully developed, single-phase incompressible flow in a full circular pipe. Input dynamic viscosity, density and roughness for the operating conditions.
- Returns straight-pipe friction loss only. Fittings, valves, elevation changes and acceleration are excluded. The friction factor is Darcy, not Fanning.