Which of the following is NOT a type of flow meter?

The primary function of a flow meter is to measure the flow rate of liquids and gases in various applications, including drinking water systems. Among the options listed, magnetic, propeller, and Venturi are well-established types of flow meters used widely in the industry.

Magnetic flow meters operate based on the principle of electromagnetic induction and are particularly effective for measuring the flow of conductive fluids. Propeller flow meters utilize a rotating propeller to determine the speed of fluid flow, which can then be translated into a flow rate. Venturi flow meters rely on a pressure differential created by a constriction in the flow path to calculate flow rate, making them useful for various fluid measurement applications.

Thermal flow meters, while a method of flow measurement, may not relate directly to the common context of flow meters used for water distribution, as they typically measure the mass flow of gases or liquids based on temperature changes. While they are indeed utilized in some specialized applications, they are not classified in the same category as the other three types listed, which are more traditional and commonly recognized as flow meter types. Therefore, thermal measuring methods do not fit the standard characterization expected in this context, making it the correct answer for the question of which option is not a type of flow