Chinese
Spanish
Russian
Portuguese
French
German
Indonesian
Thai
Vietnamese
Arabic
Italian
Turkish
Polish
Japanese
A tank inventory report can disagree with a transfer record even when the radar follows the liquid correctly. Oil tank radar inventory discrepancies should be traced through the calculation chain before an offset is entered into the transmitter. Changing a valid level to make a volume total agree can leave the next operating point wrong.
Identify which quantities are being compared
Start with the labels and units on both reports. Liquid level, ullage, observed volume, temperature-corrected volume and mass are different quantities. A comparison is meaningful only after the datum, time and calculation basis are aligned.
Record the original radar distance as well as the displayed tank value. The METRAVON MV-RD12 is a liquid distance-measurement component; its product specification does not establish a complete oil accounting method. The host's conversions and additional measurements require their own verification.
| Comparison stage | Question that isolates a discrepancy |
|---|---|
| Distance to level | Are the antenna reference and tank zero the same as those used in the approved setup? |
| Level to volume | Does the correct tank table, revision and unit apply to this vessel and datum? |
| Volume correction | Are the required temperature, product and correction inputs valid and time-aligned? |
| Net quantity | Are water bottom, unavailable stock and any applicable roof corrections handled consistently? |
Check the reference after mechanical work
Suppose an illustrative installation has a reference-to-zero distance of 10.00 m and measures 3.00 m to the liquid: the calculated level is 7.00 m. Raising the antenna by 0.15 m changes both distances. With E = 10.15 m and d = 3.15 m, the level is still 7.00 m. Retaining the old E would instead report 6.85 m.
This example shows a reference error, not a failed radar. Use actual surveyed values for a real tank. Do not apply a compensating volume offset before establishing whether the antenna, nozzle or tank datum changed.
Investigate oil tank radar inventory discrepancies at the first differing stage
If local distance agrees with an appropriate independent observation but host level does not, inspect the conversion and units. If level agrees while volume differs, inspect the tank-table identity and interpolation. If observed volume agrees while corrected quantity differs, investigate the additional inputs and calculation method.
For a tank with changing cross-sectional area, one level offset does not produce the same volume difference throughout the range. Test useful low and upper conditions rather than making a single mid-level result match. Retain both raw observations and calculated outputs so the correction remains auditable.
Where a roof or a water layer affects the accounting, use the approved method for that tank. A top-surface value alone cannot establish water-bottom quantity. Similarly, a floating structure must not be interpreted as liquid surface without a valid measurement arrangement.
Compare records at the same time and operating state
Check clock alignment, transfer start and finish times, settling conditions and any stale or substituted input. Do not compare a late manual reading with an earlier historian total while the tank is filling. Keep the site's authorised measurement and access procedures in place.
For commercial settlement, the responsible metrology or accounting authority must approve the complete method and evidence. An instrument's nominal accuracy and a successful calculation example do not establish custody-transfer suitability.
Q1. Should the radar be recalibrated whenever inventory differs?
No. First determine whether the disagreement begins in distance, level conversion or a later quantity calculation. Calibration cannot correct the wrong tank table or an outdated temperature input.
Q2. What data should be sent for technical review?
Provide time-matched raw distance, local level, host level and reported quantity, together with the reference drawing and a record of recent changes. Identify which values are measured and which are calculated.
Summary
Find the first stage that disagrees before changing the sensor. Send the MV-RD12 readings and inventory conversion details to distinguish a measurement problem from a system-calculation problem.
