Performance Of A 2-Plane Multi-Path Ultrasonic Flowmeter

By D. Augenstein & T. Cousins, Caldon Inc.

The two plane multi-path ultrasonic meter is a very different meter from the usual multi-path ultrasonic meter. The two plane multi-path meter is composed of two separate four path meters, with the path’s plane orthogonal to each other. This configuration allows the meter to be considered as two separate single plane meters. However, when the two meters are combined, they form a single meter with powerful extra features. This two plane meter has the ability to withstand very poor installation conditions, to provide extra self-diagnostic capabilities, to provide path redundancy without loss of uncertainty, and to improve flow measurement accuracy.

This paper shows the meters’ immunity to installation, their ability to be able to predict the change in uncertainty by the use of diagnostic checks and their measurements of velocity profiles quantified as swirl (%) and “flatness ratio”. The flatness ratio is introduced as a metric of the velocity profile’s flatness and is used to predicted and correct for changes in calibration.

Data from meter calibrations are used to determine the influence factors relating the changes in “flatness ratio”, and hence the potential errors due to profile change. The meter operates in difficult installations with minimal effect on the calibration and may be considered a high quality master meter.