Evaluating Industrial Flowmeters

Flow measurement plays a critical role throughout the chemical process industries (CPI). Repeatable measurements are needed to maintain consistent production and quality standards in a wide range of process-control applications. Inaccurate liquid- and gas-flow measurements can mean the difference between profit and loss, and in some cases, can lead to more serious consequences. This article provides an overview of important flowmeter-selection criteria. Practical advice for evaluating common meter designs and for pairing the right instrument technology with various flow-measurement applications is offered. In addition to evaluating the various flowmeter designs, users should also consider intangible factors when selecting a meter. These factors include familiarity of plant personnel, their experience with calibration and maintenance, spare parts availability, and mean time between failures at the particular installation site.   Principles of flow With most liquid-flow measurement instruments, the flowrate is determined inferentially by measuring the liquid’s velocity or change in kinetic energy. Velocity depends on the pressure differential that forces the liquid through a pipe or other conduit. Because the pipe’s…