Flow Instrumentation: Principles and Formulas

The measurement of fluid flow is arguably the single most complex type of process variable measurement in all of industrial instrumentation. This is because there are vast array of flow metering technologies that can be used to measure fluid flow each one with its own limitations and individual characteristics. Even after a flow meter has been properly designed and selected for the process application and properly installed in the piping, problems may still arise due to changes in process fluid properties (density, viscosity, conductivity), or the presence of impurities in the process fluid. Flow meters are also subject to far more wear and tear than most other primary sensing elements, given the fact that a flow meter’s sensing element(s) must lie directly in the path of potentially abrasive fluid streams.

Given all these difficulties and complications of fluid flow measurement, it becomes imperative for any end user of any given flow meter technology to understand the complexities of flow measurement. What matters most is that you thoroughly understand the physical principles upon which each flow meter depends. If the “first principles” of each technology are understood, the appropriate applications and potential problems become much easier to identify and solved.
Here some basic principles and common formulas used in flow instrumentation are introduced.

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