Análise experimental da variabilidade induzida por acidentes de linha na medição de vazão ultrassônica por tempo de trânsito

Abstract

This work is dedicated to flow measurement and aim to handle with peculiarities related to this subject, analyzing experimentally the effects installation on the variability of an measurement by ultrasonic flowmeter. Such installation effects are commonly found in industrial plants. To proceed this, it was evaluated the influence of four distinct types of installation, positioned at distinct distances from the ultrasonic flowmeter. . It was used a wind tunnel operating with atmospheric air, induced by a compressor and the flow level was varieted as well by means of a valve. The results demonstrates how peculiar is the flow measurement as well as the amount of research necessary, since it was gotten different behaviors from those observed by inadvertent observers. For example, beside the flow was kept under control, as demonstrated by the small deviations between collected data (maximum deviation around 2%), after many runs it was observed from the installation composed by two elbows in orthogonal plans resulting a distinct behavior from the others installations. In this case, the standard deviation was greater when the installation was mounted at a longer distance from the flowmeter, diverging from the recommendations of fabricants and norms. Usually they recommend a minimal distance from which the measuring reaches good quality. So, the measurements are liable to the flow dynamics and the best place to install a flowmeter should be choose considering the variability induced by each configuration installation.