Flowmeters are nothing but an instrument that is able to measure linear as well as non-linear and mass flow rate of gases or liquids. When it concerns selecting proper flowmeters you would at the very outset need to understand the type of application that it is being used for, and so it pays to invest your time and make a concerted effort in making a complete evaluation of the process fluid’s nature and how the meter is to be installed.
In the previous article about flow meters, we have discussed the basics of the selection procedure. To be sure, before selecting your flowmeters you need to answers questions such as the nature of fluid that is to be measured by the flowmeter and so you need to be sure whether you are going to measure air or water or some other medium. In addition, you need to determine whether there is a need for rate measurement or totalization when using the flowmeter and to also determine whether the fluid being measured is clean or not.
Local Display or Electronic Signals
Other questions that need to be answered with regard to selecting a flowmeter are determining whether a local display is required on the instrument or are electronic signals enough. In addition, you need to establish the minimum as well as maximum rate of flow, minimum and maximum process pressure as well as minimum and maximum temperature of the process.
Finally, you have to also determine whether the fluid is chemically compatible with whetted parts of the flowmeter, and in case the application is process oriented, what size of pipe should be used. In addition, you will also need to be concerned with the piping as well as area where the flowmeters can best be located.
Another aspect to deciding on using a flowmeter is comparing it in terms of performance with a point sensor that too can provide similar performance. As a rule of thumb, given that you need to choose between point sensors and flowmeters, the latter is the better option because the former cannot look to the complete flow and it is also only effective when inserted to a certain depth where flow velocity is neither too high nor too low.
So, before you specify your flow meter, it is recommended to check whether to use mass units or volumetric units to obtain most useful flow information. To be sure, volumetric flow is not very useful in the case of compressible materials that do not have constant density. In such cases, it may be better to use mass flow meters that are insensitive to density and pressure as well as variations in viscosity