Pressure Drop Calculator – Pipe Flow Loss
Calculate pressure drop and friction loss in pipe flow
How to Use
- Enter the pipe length in meters or feet
- Enter the pipe diameter in millimeters or inches
- Enter the fluid velocity in m/s or ft/s
- Enter the friction factor (typically 0.015-0.025 for smooth pipes)
- Click calculate to see the pressure drop
What is Pressure Drop?
Pressure drop is the reduction in pressure that occurs when a fluid flows through a pipe, duct, or other conduit. It's caused by friction between the fluid and the pipe walls, as well as turbulence within the fluid.
Understanding pressure drop is crucial for designing efficient piping systems, HVAC systems, and industrial fluid transport networks.
The Darcy-Weisbach Equation
The Darcy-Weisbach equation is: ΔP = f × (L/D) × (ρv²/2), where ΔP is pressure drop, f is the friction factor, L is pipe length, D is pipe diameter, ρ is fluid density, and v is fluid velocity.
This equation is widely used in mechanical and civil engineering for calculating pressure loss in pipe flow.
Understanding Friction Factor
The friction factor depends on pipe roughness, Reynolds number, and flow regime (laminar or turbulent).
- Smooth pipes (PVC, copper): f ≈ 0.015-0.020
- Commercial steel: f ≈ 0.020-0.025
- Rough pipes (old iron): f ≈ 0.030-0.050
- For laminar flow (Re < 2300): f = 64/Re
Applications
- HVAC system design
- Water distribution networks
- Oil and gas pipeline design
- Chemical process engineering
- Hydraulic system design
Frequently Asked Questions
- What is a typical friction factor for water pipes?
- For smooth pipes like PVC or copper carrying water, the friction factor typically ranges from 0.015 to 0.020. For commercial steel pipes, it's usually 0.020 to 0.025. Older or rougher pipes can have friction factors of 0.030 or higher.
- How does pipe diameter affect pressure drop?
- Pressure drop is inversely proportional to pipe diameter. Doubling the pipe diameter can significantly reduce pressure drop, making larger pipes more efficient for fluid transport but also more expensive.
- Can I use this calculator for gases?
- This calculator assumes an incompressible fluid (like water). For gases, especially at high velocities or pressure changes, you need to account for compressibility effects and use more complex equations.
- What causes pressure drop in pipes?
- Pressure drop is primarily caused by friction between the fluid and pipe walls, turbulence in the fluid, and resistance from pipe fittings, valves, and bends. Longer pipes, smaller diameters, higher velocities, and rougher surfaces all increase pressure drop.