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Bulk-solid radar level performance established for one grade should not be assumed unchanged after a material substitution. Moisture, fines, particle size and filling behaviour can change together. Keep the radar distance record separate from any calculated inventory mass so a changed density assumption is not mistaken for a sensor fault.
Record what changed in the material
Ask production or procurement to identify the new grade, supplier specification and expected variability. Do not describe every powder as the same duty because it occupies the same silo. Note whether transport, aeration or discharge has also changed; these can alter dust conditions and the shape of the surface being observed.
The METRAVON MV-RD21 is intended for bulk solids and has a 76 mm PTFE lens with a nominal 3-degree beam. Those physical specifications do not establish equal echo margin for every grade. The product selection needs material and operating evidence as well as silo dimensions.
Bulk-solid radar level checks after a grade change
| Change | Evidence to compare |
|---|---|
| Moisture | Material condition, deposits and readings at comparable surface positions. |
| Fines | Filling-period dust and whether valid surface tracking is retained. |
| Flow | New peaks, valleys or buildup that shift the surface region seen by the radar. |
| Density | The separate basis used to convert inferred volume into mass. |
| Cleaning | Any changed procedure affecting the antenna, seals or deposited material. |
There is no universal moisture percentage at which this model becomes suitable or unsuitable. Compare representative grades at the required low, intermediate and high operating levels. A stronger return from one sample does not justify reducing the review to moisture alone, because coating and surface movement may change at the same time.
Keep the original trial and the new acceptance record
Retain the previous configuration before an authorised adjustment. Record grade identity and process state with each new observation, including filling and discharge periods. If only one grade has been tested, state that limitation rather than approving the complete future material range.
When the distance looks consistent but displayed tonnes change unexpectedly, inspect the conversion model before changing radar calibration. The inventory conversion review explains why density and pile profile need independent treatment.
Material-change questions
Q1. Is an unchanged chemical name enough to retain acceptance?
No. Different grades can have different particle distribution, moisture and handling behaviour. Compare the characteristics relevant to the installed measurement, not just the name on the purchase order.
Q2. Should the radar be retuned for every delivery?
Routine unexplained retuning can hide an unstable application. Investigate recurring differences and establish an accepted operating envelope; make configuration changes through a recorded procedure.
Summary
Treat a material substitution as a change to the measurement duty. Provide old and new grade information, silo geometry and operating trends for an MV-RD21 reassessment.
