Selecting the right flowmeter
Congratulations! Your company has decided to purchase a flowmeter to measure flow through your pipes. Now the bewildering task of selecting the proper flowmeter begins.
Although it would be nice to have a single flowmeter technology which can be used to measure all your flowmeter applications, whether they are steam, liquid or gas, no such flowmeter exists. Each flowmeter technology has its particular strengths. The goal is to select the best flowmeter based on your specific flow criteria.
The following are questions to consider prior to selecting your new flowmeter:
What fluid is being measured?
Steam has different fluid properties than water, and meters are made to handle specific fluid properties. For example: A magnetic flowmeter meter is good at measuring conductive liquids such as water, but cannot measure good steam adequately.
What is the fluid temperature?
Flowmeters use different materials in their design, each design has temperature limits.
What is the fluid pressure?
Flowmeters are designed to measure up to a specific pressure, therefore knowing the fluid’s pressure helps narrow the options.
What is the required accuracy?
If the meter is being used for billing, higher accuracy is recommended.
What is the meter line size?
Meters come in different line sizes. Knowing the line size determines which meter can be used.
What is the flow range?
Knowing the range between the minimum and maximum flow rate is critical to meter selection. If the flow range is unknown and the process is not consistent sometimes the widest flow range, referred to as turndown, is the best solution.
Can the process be shutdown
If the process is critical, for instance at a hospital, and the flow cannot be shutdown then a meter which can be installed while there is flow in the pipe is the best solution.
How much straight run is available?
Flow meters need a consistent flow profile to measure accurately. This is achieved by adequate straight pipe runs before and after the meter and is referred to as straight runs. Meter technologies have different straight run requirements to meet their accuracy. If the straight run is limited, a flow technology which requires shorter straight runs will be recommended.
Content provided by Spirax Sarco, originally published in Steam News Magazine.