Which of the following is NOT an example of a flow-measuring device?

The selection of the manometer as the correct answer stems from understanding the purpose and function of various flow-measuring devices. A manometer is primarily used to measure pressure rather than directly measuring flow. Manometers work by comparing the pressure of a fluid in a system with the atmospheric pressure, typically utilizing a column of liquid. This makes them suitable for applications that require an understanding of pressure differentials, but not for directly measuring the volumetric or mass flow of a fluid.

In contrast, weirs, magnetic flow meters, and Parshall flumes are all designed specifically for flow measurement. Weirs control the flow of water and measure the height of water flowing over a notch, indirectly providing a flow rate. Magnetic flow meters operate based on Faraday’s law of electromagnetic induction, allowing precise measurements of conductive liquids. Similarly, a Parshall flume is a type of flow measurement device that provides accurate flow measurements by creating a specific relationship between the height of water flowing through the flume and the flow rate.

Understanding these distinctions clarifies why the manometer does not belong in the same category as the other examples of flow-measuring devices.