Which of the following is NOT considered a flow measuring device?

A manometer is primarily used to measure pressure differences in fluids rather than directly measuring flow rates. It measures pressure in a liquid column and can indicate pressure changes within a system. While it can provide information related to flow through pressure measurements (e.g., in a system using the Bernoulli principle), it does not function as a dedicated flow measurement device like the other options listed.

In contrast, the other devices specifically measure flow. A Parshall Flume, for example, is an open channel flow measurement device that measures the flow rate by evaluating the water level and geometry of the flume. A Mag Meter uses electromagnetic fields to measure flow velocity in conductive fluids and can directly calculate flow rates based on its readings. Similarly, a Venturi Meter works on the principle of pressure differences created by varying diameters in a pipe to measure the flow rate. Each of these devices has a primary function of measuring the flow of liquids, making them distinctly different from a manometer in that regard.