GE 033.733.002 DC Channel card

033.733.002 Analogue Input Cards

“Flow” can refer to volumetric flow (the amount of fluid passing per unit of time), mass flow (the number of units of fluid mass passing per unit of time), or even standardised volumetric flow (the amount of gas flowing, assuming that the pressure and temperature values are different from the actual process line operation). GE 033.733.002 flowmeters configured to work with gas or vapour flows are generally not usable for liquid flows. The dynamic behaviour of the fluid itself varies with the flow rate.

Most flow measurement techniques cannot achieve satisfactory measurement linearity from maximum rated flow all the way to zero flow, regardless of how well they are matched to the process application. In addition, the performance of most flowmeter technologies is critically dependent on proper installation. One cannot simply hook up a flow meter anywhere in the pipework and expect it to function as designed. This is a source of constant friction between piping (mechanical) engineers and instrumentation (control) engineers on large industrial projects.

GE 033.733.002 Piping layouts that can be considered excellent from the standpoint of process equipment functionality and economics are usually (at best) poor for good flow measurement and vice versa. In many cases, flowmeter equipment is not properly installed and the instrumentation technician must deal with the resulting measurement problems during start-up of the process unit. Even where a flowmeter has been properly selected for a process application and properly installed in a pipeline, problems may arise due to variations in process fluid properties (density, viscosity, conductivity) or the presence of impurities in the process fluid.

Flowmeters are also more susceptible to “wear and tear” than most other major sensing elements because the sensing element of the flowmeter must be located directly in the path of a potentially abrasive fluid stream. Given all these complexities, the instrumentation professional must understand the complexity of the process Measurement. It is of paramount importance that you fully understand the physical principles upon which each flowmeter is based. By understanding the “first principles” of each technology, appropriate applications and potential problems are easier to identify.