4. Water meters

4.1 General

A distinction must be made between flow measurements in free-surface flows and flow measurements in loaded pipes.

For the former, please refer to the article "Flow of liquids in the open air" in the Measurement and Control treatise. In current practice, these are weirs or throttling devices (Venturi channel), where the upstream level determines the flow value.

For the latter, a distinction is made between throttling devices (diaphragms, nozzles, Venturis), for which we refer you to the article