Calculation of a flowmeter with depressurizing element
Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full

Over the last century, many experimenters have measured discharge coefficients. $C$ of various depressant organs. The data were first collected in tables, then smoothed out in the form of empirical relationships that could be processed by desktop numerical calculators, then by microcomputers; these relationships are therefore evolving, and the formulation due to Stolz, used since 1980 for diaphragms, is tending to become obsolete in favor of the Reader-Harris/Gallagher equation.