Expert’s answer: What’s the best way to do a meter accuracy test?
If you want to do a meter accuracy test and check your flow meter to see if it needs maintenance or calibration, you can do that using a clamp-on flow meter. The external measurement will allow you to compare the inline meter and the clamp-on.
Of course, the inline meter should give you more accurate values than the clamp-on, as it’s integrated into your system. That’s okay though, because you only need a comparison. The clamp-on will help diagnose the inline, not replace it.

Today, you can find flow meters with self-tests that check sensors, electronics and output conditions. The self-test also has a health verification which can give you a simple or detailed report about the flow meter conditions. Sometimes you can use the report to align with ISO 9001. Then you can schedule your maintenance following the report, thus saving time and money by avoiding downtime.
For more about clamp-on flow meters, see the following:
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