Velocity Calculator
Calculate fluid velocity and determine flow regime based on flow rate and pipe diameter for accurate piping system design and analysis.
Internal diameter of the pipe
Default: 1000 kg/m³ (water at 20°C)
Default: 1.0 cP (water at 20°C)
Calculation Results
Enter your parameters and click "Calculate Velocity" to see results
How to Use the Velocity Calculator
Input Parameters
- Flow Rate: Volumetric flow rate (L/s or GPM)
- Pipe Diameter: Internal diameter of pipe (mm or inches)
- Fluid Density: Density of fluid (default: water)
- Dynamic Viscosity: Fluid viscosity in centiPoise
Calculation Results
- Fluid Velocity: Average velocity in m/s or ft/s
- Reynolds Number: Dimensionless flow parameter
- Flow Regime: Laminar, transitional, or turbulent
About the Calculation
This calculator determines fluid velocity using V = Q / A, where V is velocity, Q is volumetric flow rate, and A is the cross-sectional area (π × D² / 4). It also calculates the Reynolds number (Re = ρ × V × D / μ) to determine the flow regime.
Understanding Flow Regimes:
- Laminar Flow (Re < 2,300): Smooth, layered flow with predictable patterns. Lower friction losses but poor mixing characteristics.
- Transitional Flow (2,300 < Re < 4,000): Unstable flow regime with characteristics between laminar and turbulent. Generally avoided in design.
- Turbulent Flow (Re > 4,000): Chaotic, well-mixed flow with higher friction losses but better heat transfer and mixing properties.
Recommended Velocity Ranges
Water Systems
- • Residential supply: 1.5-2.5 m/s (5-8 ft/s)
- • Commercial supply: 2.0-3.0 m/s (6-10 ft/s)
- • Suction lines: 1.0-1.5 m/s (3-5 ft/s)
- • Drainage: 0.6-3.0 m/s (2-10 ft/s)
HVAC Systems
- • Heating water: 1.2-2.5 m/s (4-8 ft/s)
- • Chilled water: 1.5-3.0 m/s (5-10 ft/s)
- • Steam (low pressure): 15-25 m/s
- • Condensate return: 1.0-1.5 m/s
Important Considerations
- • High velocities can cause erosion, noise, and water hammer
- • Low velocities may lead to settling in slurry systems
- • Velocity affects pressure drop and pumping costs
- • Consider system-specific requirements and industry standards
- • Verify calculated velocities are within acceptable ranges for your application