Sharing this on behalf of Much Solar, a solar-equipment supplier. We publish free buyer-oriented guides, and this one may be useful when planning water-volume records for a solar-powered irrigation or borehole pump. The linked page is on our commercial website and includes product links.
Before ordering a flow meter, try writing down the lowest flow you need to measure and what the record must show: a momentary flow rate, a daily volume, or discharge during a pumping test. Those needs can lead to different checks.
A short worksheet for the meter supplier:
1. At the lowest expected flow, what accuracy or error limit is actually specified for this exact size and model? A display starting to move only shows that it has detected something; ask for the measurement specification too.
2. If the meter uses Q3 and an R ratio, calculate Q1 rather than comparing R alone. For an entirely hypothetical example, Q3 of 4 cubic metres/hour divided by R of 160 gives Q1 of 25 litres/hour. An assumed 10 litres/hour would fall below that boundary. This arithmetic is not a pump test or a prediction of how much water any meter misses.
3. What happens at low-flow cut-off, during power loss, or when a measurement is invalid? Ask which events affect the display, the output and the totalizer. A zero reading needs to be interpreted using the actual configuration.
4. Where will the meter sit? Check the selected instrument’s pipe-fill and installation requirements. A meter on the outlet of a storage tank records tank delivery, which may occur at different times from the pump filling it.
5. For a daily record, keep opening and closing totalizer readings with timestamps and note resets or missing periods. Check how the meter stays powered and preserves its reading when the solar pump stops.
Our longer reference, with links to OIML, Kamstrup and Endress+Hauser material:
https://muchsolar.com/solar-pump-flow-meter-minimum-flow/
The guide supports questions to ask a supplier; it does not select or calibrate a meter, establish sustainable borehole yield, or replace the installer’s and test professional’s assessment. This post was prepared with AI assistance and checked against the linked guide; no first-hand installation or field-test experience is claimed.
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