The flow pattern over a notch or weir is complex and there is no analytical solution to the relationship between discharge and head so that once again a semi-empirical approach has to be used. For small scale applications, weirs are often referred to as notches and invariably are sharp edged and manufactured from thin plate material. Hydraulics Bench incorporates a weir channel which is 158mm wide tapering to 152mm wide at the bottom, x 150mm deep x 735mm long in the working surface. The weir channel is fitted with an acrylic 60 triangular notch weir with an integral scale which can be used to provide an approximate indication of the flow rate. In open channels, weirs are commonly used to either regulate or to measure the volumetric flow rate. The Hook Gauge and Scale is an essential accessory for the accurate measurement of the upstream head. They are of particular use in large scale applications such as irrigation schemes, canals and rivers. For a detailed study of the discharge over weirs, provided two sets of weirs and a hook gauge.
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