The most important consideration in flowmeter selection is the appropriate technology. For example, some flowmeters are suitable for air and gas applications but not useful for liquids, while others may offer the most effective solution for steam monitoring. A thorough examination of the application parameters, including your plant layout, processes and installation environment can help save you time, money and headaches down the road.

In addition to mechanical and electrical requirements, other issues relevant to your plant’s operation that you may want to consider include maintenance schedules, energy-conservation initiatives and your maintenance personnel’s familiarity with flowmeter technology.

It also is critical to evaluate the piping requirements and flow characteristics of the fluid to be measured, including the expected minimum and maximum pressure and temperature values as well as normal operating values. In terms of the piping setup, you should account for the following: direction, size, material, pipe schedule, flange-pressure ratings, upstream or downstream turns, valving, and available straight-pipe run lengths.

Accuracy and rangeability are the most critical characteristics of a flowmeter. Most manufacturers provide these specifications for water, air or a specific gas. Ensure that these specifications meet the requirements of your particular fluid or process.

Some flowmeter installation procedures are more complicated than others, and it is important to determine if the meter you have chosen can be inserted directly into the process pipe or if the line must be cut, spliced or penetrated in various locations. The installation process can affect the complexity and cost of the flowmeter, as well as the instrument's ability to maintain specified accuracy.

Most flowmeters require a specific length of upstream and downstream straight-run pipe to generate a well-developed flow profile, and that length will differ from one technology to another. This is especially important in retrofit installations, where additional piping may increase the cost of installation.

Finally, consider the flowmeter's cost-of-ownership over its lifecycle. Some devices require frequent cleaning or removal from service for maintenance or recalibration. Some meters may have a low initial cost, but require frequent maintenance or have a short service life, whereas a more expensive instrument may be less costly to install, require less maintenance and provide a much better return on investment.