V-NOTCH and Flow Meters
Water flow monitoring in open channels is widely employed in environmental and geotechnical field. Leakage measurement is one of the most important indicator of the overall performance of earth/rock-fill and concrete dam.
The leakage rate is a function of the water level in the reservoir and depends either of the construction and of the behaviour of the dam.Consequently, leakage monitoring provides data for the evaluation of the long term stability of the dam constructions. Leakage water is usually impounded downstream of the dam and diverted to a basin in a weir-station.
Resistive pressure transducer sensor is a spin off from thick film technology using the piezo-resistive characteristic of specific resistive inks. Resistors, formed using screen printing techniques, are deposited on a deformable ceramic diaphragm substrate to form strain gauge arrays. Strain changes from external loads applied to the deformable ceramic diaphragm result in resistance changes of the strain gauge arrays.
The electric signal from the strain gauge arrays is directly proportional to the stress applied to the diaphragm. Sensor is constructed of a ceramic, analogous to a crystal structure, to form a pressure diaphragm chemically inert with near perfect mechanical characteristics. Screen printed resistors are deposited onto the diaphragm to form a 4 arms Wheatstone bridge.
A fixed excitation voltage is applied to one diagonal of the circuit. Strains experienced by the diaphragm will change the values of the individual resistors within the Wheatstone bridge resulting in a bridge unbalance. This unbalance produce an output signal from the other diagonal of the Wheatstone bridge, directly proportional to the applied stress.
An electronic board converts this signal into 4-20 mA suitable for transmission over long distances to remote readouts or to data acquisition systems.