Pressure Drop Calculator

Darcy-Weisbach Equation

The Darcy-Weisbach equation is the fundamental equation for calculating pressure loss due to friction in pipes:
ΔP = f × (L/D) × (ρv²/2)
Where:

• ΔP = Pressure drop (Pa)
• f = Darcy friction factor (dimensionless)
• L = Pipe length (m)
• D = Pipe diameter (m)
• ρ = Fluid density (kg/m³)
• v = Flow velocity (m/s)

Minor Losses

Minor losses occur due to fittings, valves, and other components in the piping system. They are calculated using:
ΔP = K × (ρv²/2)
Where K is the loss coefficient specific to each fitting type. The equivalent length method can also be used, where each fitting is converted to an equivalent length of straight pipe that would cause the same pressure drop.

Friction Factor Methods

The calculator supports three methods for determining the friction factor:

• Colebrook-White Equation: Most accurate for turbulent flow, but requires iterative solution
• Haaland Equation: Explicit approximation of Colebrook-White with 1-2% accuracy
• Swamee-Jain Equation: Another explicit approximation with good accuracy for most engineering applications