Friction Loss Calculator – Pipe Pressure Loss
Calculate pressure and head loss in pipes due to friction
Table of Contents
How to Use
- Enter the flow rate and select the unit (L/s, L/min, m³/h, or GPM)
- Enter the pipe diameter and select the unit (mm, cm, or inches)
- Enter the pipe length and select the unit (meters or feet)
- Enter the pipe roughness in millimeters (e.g., 0.015 for PVC, 0.046 for steel)
- Click calculate to see pressure loss, head loss, and flow characteristics
What is Friction Loss?
Friction loss is the loss of pressure or head that occurs in pipe flow due to the friction between the fluid and the pipe wall. It's a critical factor in hydraulic system design and fluid flow analysis.
This calculator uses the Darcy-Weisbach equation, which is considered the most accurate method for calculating friction loss in pipes for all flow regimes.
Darcy-Weisbach Equation
The Darcy-Weisbach equation calculates head loss as: h_f = f × (L/D) × (v²/2g), where:
- h_f = head loss (meters)
- f = friction factor (dimensionless)
- L = pipe length (meters)
- D = pipe diameter (meters)
- v = flow velocity (m/s)
- g = gravitational acceleration (9.81 m/s²)
Flow Regimes
| Flow Type | Reynolds Number | Characteristics |
|---|---|---|
| Laminar | < 2,300 | Smooth, orderly flow with friction factor = 64/Re |
| Transitional | 2,300 - 4,000 | Unpredictable, mixed flow characteristics |
| Turbulent | > 4,000 | Chaotic flow with friction factor from Colebrook-White equation |
Typical Pipe Roughness Values
| Material | Roughness (mm) |
|---|---|
| PVC, Plastic | 0.0015 - 0.007 |
| Drawn Tubing | 0.0015 |
| Commercial Steel | 0.045 - 0.09 |
| Galvanized Iron | 0.15 |
| Cast Iron | 0.26 |
| Concrete | 0.3 - 3.0 |
| Riveted Steel | 0.9 - 9.0 |
Applications
- Water distribution system design
- HVAC system sizing
- Fire suppression system calculations
- Industrial process piping
- Oil and gas pipeline design
- Pump and piping system selection
Frequently Asked Questions
- What is the Darcy-Weisbach equation?
- The Darcy-Weisbach equation is a fundamental formula used to calculate pressure loss due to friction in pipes. It accounts for pipe characteristics, fluid velocity, and flow conditions to accurately predict friction loss.
- How do I determine pipe roughness?
- Pipe roughness depends on the material and condition. New PVC pipes have roughness around 0.0015 mm, commercial steel around 0.045 mm, and concrete 0.3-3.0 mm. Use manufacturer data or standard tables for accurate values.
- What is Reynolds number and why is it important?
- Reynolds number is a dimensionless value that indicates the flow regime (laminar, transitional, or turbulent). It affects the friction factor calculation and helps predict flow behavior in the pipe system.
- Can this calculator be used for gases?
- This calculator is designed for incompressible fluids like water. For gas flow, additional factors like compressibility, temperature, and pressure changes need to be considered.