To select a flowmeter that suits one's application, many factors need to be considered. The most important ones are fluid phase (gas, liquid, steam, etc.) and flow condition (clean, dirty, viscous , abrasive, open channel, ect.) The matching of fluid phase and flowmeter technology can be found in the flowmeter selection page.
The second most important factors are line size and flow rate (They are closely related). This information will further eliminate most submodels in each flowmeter technology.
Other fluid properties that may affect the selection of flowmeters include density (specific gravity), pressure, temperature, viscosity, and electronic conductivity. On the flow part, one needs to pay attention to the state of fluid (pure or mixed) and the status of flow (constant, pulsating, or variable).
Moreover, the environment temperature, the arrangements (e.g., corrosive, explosive, indoor, outdoor), the installation method (insertion, clamped-on, or inline), and the location of the flowmeter also need to be considered, along with other factors which include the maximum allowable pressure drop, the required accuracy, repeatability, and cost (initial set up, maintenance, and training).