subject: How To Select The Best Flow Meter For Your Application? [print this page] The Flow Meter The Flow Meter
A flow meter is a device that is used to measure the amount of fluid movement in a given time. The fluid may be either gas or liquid. There is a wide range of metering devices available, employing all techniques of measurement. Each of these devices not only have different technologies, by also differ in the range of flow measurements they can make, the way they are affected by viscosity, the chemical composition of the fluid and the line size. These factors notwithstanding, the apparent nature of the fluid, the temperature pressure induced changes in flow and the cost are some of the other factors that determine selection of a flow meter.
Understand the Fluid
When flowing through a pipeline, no fluid can be assumed to behave the same way as any other fluid. This is because each fluid has viscosity, a parameter that defines resistance to flow, which is different from that of other fluids. Irrespective of a fluid being gas or liquid, before choosing a flow meters it becomes necessary to understand the flow characteristics. This is done by evaluating the Reynoldss number of the fluid. Based on this number, a fluid is classified as Newtonian or Non Newtonian. While Newtonian fluids have predictable behavior functions, non Newtonian fluids do not show such relationships. This makes the science a tad bit difficult. However once the flow characteristic has been established, suitable choices for flow meters can be looked at.
Cost As a Factor
The flow meter is an essential part of the system. While the choices might be overwhelming, once the nature of fluid has been established, the cost should become easier to factor. A cheaper device is usually not better than one than that is costlier because the low price is most likely arrived by cuts in the quality, expertise and effective installation services. It may also mean poor after sales services. This does not suggest that the most expensive device is the best out there, but it suggests that good after technical back up, the reputation of the manufacturer and independent test data certifying the accuracy of the device, are characteristics of a cost effective flow measurement solution.
High Accuracy and Widest Turndown Are Essential
Accuracy is one stated parameter that determines the cost. A higher cost can be attributed to a more efficient technology which results in higher accuracy. However the desired precision levels can be decided up on by simply considering the application. Turndown is defined as the ratio of the maximum to minimum flow rates that can be measured. A bigger ratio means more variations in flow can be measured.
