WHITE PAPER A New Approach to Accurate Water Flow Measurement The Study of the FPI Mag® Accuracy McCROMETER, INC. 3255 W. Stetson Ave., Hemet, CA 92545 PH 951-652-6811 FAX 951-652-3078 © 2013 by McCrometer, Inc. Printed in U.S.A. 30121-37 Rev. 1.0/12-13

A New Approach to Accurate Water Flow Measurement - The Study of the FPI Mag® Accuracy Author: Nicholas Voss – FPI Mag Product Manager Abstract: Electromagnetic Flow Meters, or “Mag Meters,” are the most widely used meter technology to measure the flow of water in the world today. As populations expand, water measurement and management is becoming increasingly critical to preserve our water resources. To complicate the equation further, many existing water treatment and distribution systems that need to upgrade their technology cannot shut down or stop service to the communities they serve. The...

FPI Mag Test Protocol: The claimed accuracy for a calibrated FPI Mag meter is as follows: +/- 0.5% for Velocity 1ft/s (0.3m/s) to 32ft/s (9.8m/s) +/- 1.0% from 0.3ft/s (0.1m/s) to 1ft/s (0.3m/s) Testing was done at Utah State Water Research Laboratory (USWRL) in Logan, Utah. USWRL was chosen to perform these tests because they are a well-known, reputable water lab and because they have a very large range of line sizes and flow rates they can achieve. McCrometer chose to test the accuracy of a 30” FPI Mag at USWRL. This size was chosen instead of a smaller size due to the sheer volume of water...

Velocity (ft/s) Figure 1: 30” FPI Mag Error Plot Tested accuracy of the 30” FPI Mag compared against the master flow meter is better than +/1.0% for velocities between 0.3ft/s to 1ft/s. Tested accuracy above 1ft/s was better than +/-0.5% within uncertainty of the system. For the test point at 5.2ft/s, the tested FPI Mag accuracy was 0.66%. This is less than the total accuracy of measurement of 0.71% for the combined system. Conclusion: Results of the 30” FPI Mag test prove the FPI Mag meets the accuracy claims. The measured error of the 30” meter was equal to or better than the specified accuracies...

Appendix Accuracy of Measurement: When evaluating the accuracy of a flow meter, we must take into account the uncertainty of both the test meter and the system determining the actual flow rate. For the moderate and high flow rates of the 30” FPI Mag, the reported flow was compared against the flow rate of a USWRL Master Venturi flow meter. Venturi flow meters are a differential pressure type flow meter. Differential pressure (DP) type flow meters use a pressure drop across the primary element to determine a volumetric flow rate. The stated uncertainty of the Venturi master flow meter is +/-0.25%...