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Mechanical Engineering2D

Pipe Velocity Calculator

Calculate fluid velocity in a pipe from flow rate and pipe diameter.

Inputs
Enter your values below
Result
Flow Velocity
—
Enter values and click Calculate
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Formula
flow ÷ (π × (diameter ÷ 2)²)
Result unit: m/s

v = Q / A where A = π(D/2)². Flow rate in m³/s, diameter in m, result in m/s. Typical liquid velocity: 1-3 m/s.

Introduction

Calculate fluid velocity inside a pipe. For liquid lines, recommended velocity is 1-3 m/s; for gas lines, 10-30 m/s; for suction lines, under 1.5 m/s to avoid cavitation.

How This Calculator Works

v = Q / A where A = π(D/2)². Flow rate in m³/s, diameter in m, result in m/s. Typical liquid velocity: 1-3 m/s.

Step-by-step process:

  1. Enter your input values in the calculator above
  2. The engine converts all inputs to SI base units (meters, kg, Pa)
  3. The formula is evaluated: flow / (pi * (diameter/2)^2)
  4. Result is formatted with the appropriate unit and precision

Calculation Example

100 m³/h through 150mm pipe gives 1.57 m/s velocity.

Inputs: flow=100, diameter=150
Result: 1.57 m/s

Unit Conversion for Velocity

**Velocity units**

- 1 m/s = 3.28084 ft/s

- 1 ft/s = 0.3048 m/s

- 1 m/s = 196.85 ft/min

**Flow rate units**

- 1 m³/h = 0.2778 L/s = 4.403 US gpm

- 1 US gpm = 0.2271 m³/h

**Diameter units**

- 1 inch = 25.4 mm

- 1 mm = 0.03937 inch

Velocity is computed as V = Q / A, so keep flow and area in consistent units (e.g., m³/s with m², or L/s with cm²).

Engineering Applications

  • •Pipe sizing
  • •Pump system design
  • •Hydraulic calculations
  • •Flow measurement

Frequently Asked Questions

What is a good pipe velocity for water?

1-2 m/s for general water service, 0.5-1.5 m/s for pump suction, and up to 3 m/s for short discharge runs.

Why does velocity matter?

Too high causes erosion, noise, and high pressure drop. Too low means oversized pipe and higher cost, plus sediment deposition in slurry service.

How do I convert velocity between m/s and ft/s?

Multiply m/s by 3.28084 to get ft/s. Conversely, divide ft/s by 3.28084. For example, 2 m/s = 6.56 ft/s.

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Engineering Disclaimer: Calculations are for reference and educational purposes only. Always verify results independently for engineering design. See full disclaimer.
Reviewed by: Industrial Engineering Team
References: ASME B31.3, ASTM A36, Perry's Chemical Engineers' Handbook