Which device measures flow by causing a pressure drop across a constriction in a pipe?

Prepare for the American Water Works Water Treatment Plant Operator Test. Study with multiple choice questions, each with hints and explanations. Get ready to excel!

Flow is measured in a pipe by creating a pressure drop across a constriction with a Venturi meter. The pipe narrows at the throat, so the fluid speeds up there and the pressure drops relative to the upstream section. The difference in pressure, together with the known throat area and pipe geometry, is used with Bernoulli’s principle and continuity to calculate the flow rate. This method gives accurate results with relatively low head loss. Weirs and Parshall flumes measure open-channel flow by relating water depth to discharge, not by a pressure drop in a pipe, and a transformer is an electrical device, not a flow meter.