Which device measures flow based on pressure difference across a constricted section?

Which device measures flow based on pressure difference across a constricted section?

• A. Pitot Tube
• B. Venturi Meter
• C. Orifice Plate
• D. Ultrasonic Meter

Answer: (B)

Measuring flow by looking at the pressure difference created by a narrowed path uses the differential pressure produced by a constriction to infer how much fluid is moving. In a Venturi meter, the pipe smoothly narrows to a throat; as the fluid speeds up through that throat, its static pressure drops. The difference between the upstream pressure and the throat pressure is proportional to the flow rate. By applying Bernoulli’s principle (and a discharge coefficient that depends on the geometry), this pressure drop is translated into a volumetric flow rate. The Venturi design minimizes energy loss and provides a stable relationship between ΔP and Q, making it a reliable differential-pressure flow meter. While a constriction is also present in other devices, such as an orifice plate, the Venturi’s gradual contraction offers better accuracy and lower losses, and a Pitot tube or ultrasonic meter operate on different principles.

Measuring flow by looking at the pressure difference created by a narrowed path uses the differential pressure produced by a constriction to infer how much fluid is moving. In a Venturi meter, the pipe smoothly narrows to a throat; as the fluid speeds up through that throat, its static pressure drops. The difference between the upstream pressure and the throat pressure is proportional to the flow rate. By applying Bernoulli’s principle (and a discharge coefficient that depends on the geometry), this pressure drop is translated into a volumetric flow rate. The Venturi design minimizes energy loss and provides a stable relationship between ΔP and Q, making it a reliable differential-pressure flow meter. While a constriction is also present in other devices, such as an orifice plate, the Venturi’s gradual contraction offers better accuracy and lower losses, and a Pitot tube or ultrasonic meter operate on different principles.