Saturday, February 27, 2016

Accurate Flow Measurement in Harsh Environments with Vortex Flowmeters

Yokogawa digitalYEWFLO
Yokogawa digitalYEWFLO vortex flowmeter
The Yokogawa digitalYEWFLO vortex flowmeter is accurate and stable, even in harsh process conditions, and has a highly reliable and robust design that delivers improvements in plant efficiency and reduced operating costs

Operating Principle

When a shedder bar is placed in a flow, Karman vortices are generated on the downstream side of the bar. The Karman vortices are detected by two piezoelectric elements installed in the upper part of the shedder bar. The vortex frequency is proportional to the  ow velocity in a specific range of Reynolds numbers. Therefore, flow velocity or flow rate can be determined by measuring vortex frequency.

Noise Reduction

Noise caused by strong piping vibration may affect the accuracy of vortex frequency detection. The two piezoelectric elements in the digitalYEWFLO are installed in a configuration that is polarized, so they are not affected by vibration in the  ow or vertical directions. The noise of vortex (lift)- direction vibration is reduced by adjusting the outputs of the piezoelectric elements. Combining these features with the Spectral Signal Processing (SSP) function provides optimum and stable measurement.