Flumes

Parshall flumes
The Parshall flume is one of a large class of open channel primary elements known as critical flow venturi flumes. A distinguishing characteristic of the Parshall flume is the downward sloping invert of the throat. This feature gives the Parshall flume its ability to operate at higher ratios of downstream to upstream head than any other such device.
The Parshall flume is a monolithic fiberglass reinforced polyester structure to assure maximum strength and accuracy of dimension while minimizing installation time. Its weight is light, the installation easy and there is no need for special tools. Its short length makes the installation possible in areas, where further constructions are limited.

Sizing
Selection of a Parshall flume should be made on expected flow rates or on the maximum flow rate and on the width of influent and effluent channel. For single point measurement to be valid, the design hydraulic gradient
must insure that free flow conditions exist at all flow rates.