49 - Measurement of fluid flow

Abstract

This chapter discusses the measurement of fluid flow. Fluid flow is one of the most difficult of the industrial measurements to carry out, as the flow behavior depends on a great many variables concerning the physical properties of a fluid. There are available a large number of fluid flow measuring instruments, generally called flow meters that can measure the flow rate of liquids or the mass flow rate of gaseous fluids (in kg/s). The two main categories of flow meters are differential pressure flow meters and mechanical flow meters. The flow rate of the fluid can also be determined from a measurement of the difference between the pressures on the walls of the pipe at specified distances upstream and downstream of the flow meter. Such devices are known as differential pressure flow meters. Examples of differential pressure flow meters commonly used include: orifice plate, venturi tube, flow nozzles, and pitot-static tube.