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3 Fluid Flow Measurement Techniques

Enormous amounts of liquid and gaseous products are bought and sold daily around the globe. Commerce based on fluid products requires practical methods for measuring quantities of these liquid and gas substances. Over time, science and engineering have developed solutions for flow measurement techniques.

Fluids behave in specific and predictable ways under different conditions. Characterizing the dynamics of flowing fluids was explored by an Italian physicist named Giovanni B. Venturi. By measuring the loss of pressure across an obstruction in a flowing fluid he was able to determine its flow rate. His research ultimately led to the invention of plates for orifice fittings which are one commonly used technique in flowrate measurement today. Other types of flow meters include positive displacement, ultrasonic and magnetic flow meters.

Positive Displacement Flow Measurement

These flow meters work by dividing the fluid up into segments with a known volume. By counting the number of segments that pass a given point over time, a flow rate is calculated. These flow meters are favored when the accuracy of measurement is critical.

Ultrasonic Flow Measurement

Transmitting and receiving high-frequency soundwaves directed both with and against the direction of fluid flow in a pipe is the underlying technology for ultrasonic flowmeters. Measuring the time differences between signal transmission and reception enables the calculation of flow velocity. Factoring in the volume of a pipe’s cross-section allows for flow rate determination. Ultrasonic flow meters are favored when it is impractical to insert probes, paddle wheels or orifice plates into the fluid being measured.

Magnetic Flow Measurement

According to Faraday’s law of electromagnetic induction, a conductor moving through a magnetic field will generate a measurable voltage signal. Fluid velocity can be determined by applying this law to conductive fluids. The voltage signal generated increases in magnitude as the fluid velocity increases. As with ultrasonic flowmeters, velocity measurements allow for flow rate determination. Magnetic flowmeters are useful in measuring conductive fluids and are effective for slurries or dirty fluid applications.

The large variety of liquid and gaseous products traded in today’s economy require accurate metering technology. Buyers and sellers alike need to have a level of confidence in the quantities changing hands to support sustainable commerce. Different flow measurement technologies have produced workable solutions that keep these fluids flowing.