ABSTRACT
Weirs are apertures in the top of a dam across a channel through which flows the liquid to be measured. Extreme accuracy is not claimed for flow measurement using this device; however, measurement is very dependable with minimum maintenance and good repeatability. Accuracy is adequate for most applications to irrigation, waste, and sewage flows. The Palmer Bowlus Flume is actually a set of principles rather than a specific design. The Kennison Nozzle, Parabolic Flume, and Leopold Laggo Flume are typical proprietary products designed primarily for end of pipe flow measurement of waste, sewage, and the like, where the liquid flow to be measured emerges from a cylindrical pipe or conduit which usually is not completely full of liquid. These devices are available in medium to large sizes. Another open-channel flowmeter that does not need a primary element uses a robotically operated magnetic flowmeter probe to scan the velocity profile in the open channel.
