Mobile Flume for Pipe Flow

Discharge measurement in partially filled pipes, as occurs in sewage and drainage engineering, is considered with an improved device. The so-called pipe flume is suited for mobile discharge measurement either for a single discharge reading or for the determination of daily or weekly hydrographs. It can easily be mounted in commercially fabricated pipes, and sediment transport does not detract from its accuracy. The device has been extensively tested in a hydraulics lab and the device has an accuracy of ±5% in optimum field conditions. Simplifications compared to the original design include the head determination in the cylindrical container, by which surface fluctuations are practically removed, and effects of pipe slope are eliminated. A discharge-head equation is established for pipe flumes having a diameter larger than 200 mm, where effects of scale are negligible. The discharge-head equation accounts for the pipe filling and the constriction rate, as well as for the position relative to the pipe outlet section.