Working principle of vortex flowmeter
If the fluid does not flow in the pipe, it will not form vortices. Once the fluid starts to flow and reaches a certain velocity, it will gradually form vortices downstream of the baffle. These vortices are alternately separated on both sides of the baffle and taken away by the fluid. A high pressure and low pressure area is formed downstream of the baffle, and a phenomenon called “Karman vortex street” appears. These pressure differences match exactly the frequency of the vortices and are accurately measured by mechanical sensors. The distance between the two vortices corresponds to the specific volume of the fluid. Therefore, the total flow can be calculated by counting the passing vortices. The higher the velocity is, the higher the frequency of the measured fluid is.
Reasons for large measurement error of vortex flowmeter
1) The length of straight pipe is insufficient.
2) Analog conversion circuit zero drift or full scale adjustment is not correct.
3) The supply voltage changes too much.
4) The instrument exceeds the verification period.
5) There is a big difference between the inner diameter of the sensor and the pipe.
6) The installation is not concentric or the gasket protrudes into the pipe.
7) Sensor contamination or damage.
8) There are two-phase flow or pulsating flow.
9) Pipeline leakage.
Solution to measurement error of vortex flowmeter
1) Lengthen the straight pipe section of vortex flowmeter or install flow regulator.
2) Calibration of zero and span scales.
3) Check the power supply.
4) Timely submission for inspection.
5) Check the inner diameter of piping and correct the instrument coefficient.
6) Adjust the installation and trim the gasket.
7) Clean and replace the sensor.
8) Eliminate two-phase flow or pulsating flow.
9) Vortex flowmeter eliminates leakage.