Venturi tube
<img src="https://eng-calculations.com/SVG/Hydraulic_engineering/Flow_meters/Venturi tube.svg" alt="Venturi_tube" title="Venturi_tube">
https://eng-calculations.com/SVG/Hydraulic_engineering/Flow_meters/Venturi tube.svg
<img src="https://eng-calculations.com/SVG/Hydraulic_engineering/Flow_meters/Venturi tube.svg" alt="Venturi_tube" title="Venturi_tube">
https://eng-calculations.com/SVG/Hydraulic_engineering/Flow_meters/Venturi tube.svg