Flow Signal Characteristics of Small Scale Electromagnetic Flowmeter in Low Conductivity Fluid Measurement

In order to scrutinize the fluid conductivity effects on the electromagnetic flowmeter(EMF) characteristics, a small scale EMF was designed and fabricated. The measuring tube has a 3 mmⅹ4 mm rectangular cross-section, 9 mm length, and a 2 mmⅹ3 mm plate electrode and a ϕ 1.5 mm point electrode. The design parameters, such as the magnetizing frequency and the number of coil turns, and the diameter were optimized. The EMF was tested with a gravimetric calibrator and showed good linearity in the range of 0 to 1.17ⅹ10^-5 m³/s. The fluid conductivity was varied between 3 and 11μS/ cm , and the magnitude of the flow signal was proportional to the fluid conductivity and the wetted area of the electrode. The design information and the test results provide flow measurement techniques for very low flowrate.