Pipe diameter calculator
Easily calculate pipe diameter and flow rate using the continuity equation. Our pipe flow calculator helps determine the correct pipe size based on volumetric flow rate and velocity, making it ideal for both liquid and gas flow applications.
Suitable for engineering, HVAC, plumbing, and fluid dynamics.
How Does the Pipe Diameter And Flow Rate Calculator Works?
The calculator applies the continuity equation.
The continuity equation is a fundamental principle in fluid mechanics based on the conservation of mass. It states that for an incompressible fluid (constant density), the mass flow rate remains constant along a streamline. The equation is:
Where:
- 𝑄 = Volumetric flow rate (m³/s)
- 𝐴 = Cross-sectional area of the pipe (m²)
- 𝑉 = velocity (m/s)
Since the cross-sectional area of a circular pipe is:
We can rewrite the equation as:
Solving for Pipe Diameter (D):
where:
- D = internal pipe diameter (m)
- Q = volume flow rate
- V = velocity (m/s)
Mass Flow Rate vs. Volume Flow Rate: Formula and Conversion Guide
The relationship between mass flow rate (m) and volume flow rate (Q) is given by:
Solving for Q:
The density (ρ) of a perfect gas is given by the perfect gas law, in the next chapter.
Perfect Gas Density Formula: How to Calculate Gas Density Using Pressure and Temperature
The density (ρ) of a perfect gas is given by the ideal gas law:
where:
- ρ = Gas density (kg/m³)
- P = Absolute pressure (Pa)
- T = Absolute temperature (K)
- R = Specific gas constant (J/kg·K), defined as 𝑅=𝑅𝑢/𝑀, where 𝑅𝑢 is the universal gas constant and M is the molar mass of the gas.