MihsabaHow to use
A Venturi meter uses the pressure and velocity change between a larger inlet and smaller throat to estimate incompressible flow rate.
- Enter D₁ and smaller D₂.
- Enter pressure difference.
- Enter density and discharge coefficient.
- Review Q and both velocities.
How it is calculated
Q=CdA₂√[(2ΔP/ρ)/(1−(A₂/A₁)²)]
Example
For water with D₁=0.1 m, D₂=0.05 m, ΔP=10 kPa and Cd=0.98, the equation gives a flow of several liters per second.
Important notes
No elevation term is included; this version is horizontal. Compressible gases or large pressure ratios need a different model.
Frequently asked questions
Why must D₂ be smaller?
The throat is the contraction that raises speed and lowers pressure.
What is Cd?
An empirical discharge coefficient correcting part of the ideal-model error.
Outside diameter?
No, use flow-path inside diameter.