Calculate the volumetric gas flow rate through a pipe based on internal diameter and flow velocity. This tool is essential for HVAC engineers, piping designers, and fluid dynamics analysis.
Inches
mm
Meters
Enter the inner diameter, not the outer diameter.
m/s
ft/s
Average speed of the gas moving through the pipe.
Calculation Results
Cubic Meters per Hour:–
Cubic Feet per Minute (CFM):–
Liters per Minute (LPM):–
Cubic Meters per Second:–
Pipe Cross-Section Area:– m²
Understanding Gas Flow Rate
The volumetric flow rate of gas ($Q$) is a measure of the volume of gas passing through a cross-sectional area per unit of time. Unlike mass flow rate, which accounts for density and temperature changes, volumetric flow rate is strictly kinematic, calculated using the cross-sectional area of the pipe and the average velocity of the fluid.
The Formula
This calculator uses the continuity equation for incompressible flow:
Q = A × v
Where:
Q = Volumetric Flow Rate
A = Cross-sectional Area of the pipe ($\pi \times r^2$)
v = Average Flow Velocity
Why Velocity Matters
In gas piping design, velocity is a critical constraint.
Too High: Leads to excessive noise, vibration, and significant pressure drops due to friction.
Too Low: May result in sedimentation (if particulates are present) or require unnecessarily large and expensive piping.
Common Velocity Guidelines
Application
Typical Velocity Range (m/s)
Compressed Air
6 – 15 m/s
Low Pressure Natural Gas
5 – 10 m/s
Industrial Ventilation
10 – 25 m/s
Steam (Saturated)
15 – 30 m/s
Example Calculation
Let's calculate the flow rate for a compressed air line.