Weirs are used for the measurement of flow rates in open channels and drainage channels.
The measurement system consists of a weir with notch (with section chosen from traditional triangular, rectangular and trapezoidal shapes, depending on specific requirements) and a level meter of mechanical manual type (graduated staff gauges, in enamel sheet or profiled etched in enamel sheet or profiled etched in stainless steel) , or electrical with various sensors (LVDT with float, radar, ultrasound, piezometric or
other), for automatic measurement in remote locations.
Due to regulation of the flow ensured by the weir, which has an overflow section note, instantaneous flow rates can be calculated using the water surface level values measured upstream of the weir.
Flow rate measurement in open channels is very used and applied in environmental and geotechnical fields. This method is, particularly used in the measurement of leakages in earthfill or concrete dams, is one of the most important indicators of health status and work performance of the structure.. The amount of leakage is a function of the hydraulic level in the reservoir and depends on the characteristics and behaviour of the dam and is an indication of its structural condition and performance.
Typical applications for this instrument are level measurements in:
The weir can be triangular, with 30 °, 45° or 90 ° angles, or rectangular or trapezoidal.
Specific requirements, depending on flow rates envisaged, or size required, are possible on request.