Automated flow-rate meter for flow-analysis systems

An automated flow-rate meter easy to construct and operate is described. This is controlled by a microcomputer connected to an analog/digital converter interface and by a control software. It uses two acrylic flow cells, each comprising a bicolor light-emitting diode and a phototransistor placed on opposite sides. The performance of this flow-rate meter was evaluated by applying it to three flow manifolds: one monosegmented flow titration system by binary sampling; one conventional monosegmented flow system, and one single-line FIA system. The FIA system flow rate was assessed by means of a Vanderslice's expression. The time range of measurement of the flow rates was of 3.5–19.5 seconds and relative errors of 0.2–2.6% as well as relative standard deviations from 0.4 to 3.1% were attained. The flow-rate meter allows one to optimize precision and velocity of measurements just by changing one of its parameters. Moreover, the flow-rate meter can be used with flow systems, therefore allowing one to perform on-line measurements, which facilitates a quick and effective control of the channels flow rate.© 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 97–104, 1999