Improved vortex flow meter using pre-filter

The frequency of the vortex formation in a flow meter can be measured using a piezoelectric sensor. The piezoelectric sensor produces a raw signal, where the average frequency indicates volumetric flow rate. This sensor signal contains more information than just the frequency of vortex. The objective of this research is to optimize a typical flow meter with a measurement range of 0.5-4.5 l/min and also output a signal outside of this measuring range. A vortex-signal is taken directly from a piezoelectric sensor with a flow rate of greater than 4.5 l/min to investigate the sensors capability in sensing a vortex signal in a turbulence range, and to identify the various noises which distort the vortex signal. Based on experimental measurements, an analog pre-filter circuit system has been designed.