A Flow Measurement Technique Using a Noncontact Capacitance-Type Orifice Transducer for a Conducting Liquid

The ordinary orifice transducer widely used in process industries for flow rate measurement produces a differential pressure which is generally measured by a DP cell and thus may suffer from various problems like leakage of process fluid, corrosion of diaphragm materials, etc. In this paper, the design of a noncontact capacitance-type orifice transducer for the measurement of flow rate of a conducting liquid through a pipeline has been described. In the proposed transducer, the use of a diaphragm-type DP cell is not needed, and thus, the problems associated with DP cell are avoided. The theoretical analysis of the flow transducer is presented in this paper. The performance of the flow transducer along with that of the signal conditioner for flow of tap water through a pipeline has been tested experimentally. The experimental results are presented in this paper. A good linearity and repeatability of the sensor capacitance, transducer output, and signal conditioner output with flow rate have been observed.