Flow Meter Accuracy Calculator
Turn a flow meter accuracy specification into the actual error at each flow. Compare % of reading (rate), % of full scale and Coriolis style zero stability.
- Error = 1 % × 100 = 1
- As % of reading = 1 ÷ 20 × 100 = 5 %
Error across the range
| Flow (% of FS) | Flow | Error | % of reading |
|---|---|---|---|
| 100 % | 100 | ± 1 | ± 1 % |
| 75 % | 75 | ± 1 | ± 1.33 % |
| 50 % | 50 | ± 1 | ± 2 % |
| 25 % | 25 | ± 1 | ± 4 % |
| 10 % | 10 | ± 1 | ± 10 % |
| 5 % | 5 | ± 1 | ± 20 % |
Accuracy Formulas
% of rate: error = a × Q
With zero stability: error = a × Q + ZS
Error % of reading = error ÷ Q × 100
a is the accuracy as a fraction, FS the full scale flow, Q the actual flow and ZS the zero stability in flow units (common on Coriolis meters). Accuracy specs usually apply at reference conditions and within the stated turndown.
Worked example
A ±1 % of full scale meter on a 100 m³/h range has ±1 m³/h error everywhere. At 20 m³/h that is ±5 % of reading, while a ±1 % of rate meter stays at ±1 %.
Frequently Asked Questions
What does % of full scale mean?
The error is a fixed amount equal to the percentage of the maximum flow, so the relative error grows as flow falls.
What does % of rate mean?
The error is a percentage of the actual reading, so it stays the same relative size across the range.
What is zero stability?
A small fixed flow error around zero, quoted for Coriolis meters. At low flow it dominates the total error.
Learn more on the blog
What factors affect the stability of flow meter readings?
A practical, field focused guide on instrumentationblog.in that explains the theory behind this calculator and how engineers apply it on real plants.
Read Full Article