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Precision level measurement should start with the error the process can tolerate, not the smallest number shown on a display. A tank may need close control near a pump limit but only approximate indication elsewhere. State where the error matters and under which operating conditions it will be assessed.
Convert the process need into an error limit
Specify the measured quantity first: distance from the antenna, height above a datum, or calculated volume. For a vessel with constant horizontal area A, a small level error e corresponds to a volume error A multiplied by e, using consistent units. This relationship is geometry, not an instrument guarantee; varying tank sections require their actual volume curve.
| Term | What it tells you | What it does not prove |
|---|---|---|
| Resolution | The smallest displayed or transmitted increment. | That increments of this size are accurate or repeatable. |
| Repeatability | Agreement under repeated, specified conditions. | Freedom from a consistent offset. |
| Error | Difference from the accepted reference value. | That the reference itself has negligible uncertainty. |
| Response | How the result follows a changing surface. | Static accuracy during rapid transfer. |
Precision level measurement with an installed radar
The METRAVON MV-RD12 product page gives a nominal accuracy figure for the instrument. Acceptance of a tank installation also depends on the reference plane, nozzle, observed surface and receiving system. Do not transfer the catalogue figure directly into a whole-tank volume guarantee.
Compare like quantities at compatible times. A manual reading taken before transfer stops is not a valid reference for a delayed, filtered radar value recorded later. Where the surface moves, define the observation interval and record the variation instead of selecting the most favourable pair of readings.
Build an acceptance record that explains disagreements
Choose accessible points covering the intended working interval and include the conditions that may change performance. Retain the raw distance where available, calculated level, output and controller value. This separates a sensing discrepancy from an offset, scaling or tank-table problem.
Record the reference method and its uncertainty, then agree the decision rule before testing. If the reference cannot distinguish the required tolerance, obtain a better method or revise the claim; adding decimal places to the report does not solve that limitation.
Q1. Does a repeatable offset justify immediate recalibration?
First verify the physical datum and the quantities being compared. An offset caused by measuring from different reference planes should be corrected in the configuration or record, not hidden in a sensor adjustment.
Q2. Can one calm-water test approve all operating states?
No. Foam, agitation, filling and changing geometry can affect the installed result. State which conditions were tested and which remain outside acceptance.
Summary
Request a level measurement acceptance review with the required tolerance, working levels and proposed reference method. A useful specification describes a verifiable result rather than an unexplained claim of precision.
