With funding from the US Bureau of Reclamation, California – Great Basin Region (Region 10), the Cal Poly Irrigation Training & Research Center (ITRC) performed testing on magnetic flow meters to examine issues related to upstream chemical injection. Two sets of tests were completed:

Meter Accuracy Testing – This testing determined the flow measurement accuracy of ten (10×) meters. Previously, all the meters had been installed in irrigation pipelines immediately downstream of chemical injection and showed significant fluctuations in flow measurement readings.

Upstream Chemical Injection Testing – This testing quantified the variability of flow rate measurements at various rates of upstream chemical injection.

The testing revealed that significant flow measurement fluctuations can occur when a chemical is being injected into irrigation water upstream of a magnetic flow meter. This is believed to occur due to non-uniform and rapidly changing fluid properties in the liquid flowing through the meter. While small injections at low to medium frequency resulted in minimal fluctuations, large, continuous injections resulted in significant (≥50%) fluctuations. In fully mixed solutions of chemicals and irrigation water, fluctuations were negligible.

The magnetic flow meters that were tested are described in Table 1. The layout, procedures, and results of both tests are found in the body of this report.


Bioresource and Agricultural Engineering

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URL: https://digitalcommons.calpoly.edu/bae_fac/111