A Flowmeter for Low Discharges of Laboratory Flumes

Discharge measurements over a range from 1 L/s to as low as 0.03 L/s require special instruments. A flowmeter was designed on the basis of theoretical analysis and two major design criteria: (1) the flowmeter should be accurate and flexible in monitoring the full range of indicated discharge rates, and (2) instantaneous measurements of hydrographs should be possible. Furthermore, the relationship between the observed water level in the flowmeter and the actual discharge was linearized to the maximum extent possible. This article describes the design and test results. The calibration data from four flowmeters show that the design fulfills the above criteria and is replicable