Radar Installation in Bulk-Solids Silos: Dust, Piles and Filling

Bulk-solids silos do not present a flat, stable target. Filling creates a peak, discharge can form a valley or rathole, and the surface moves differently at different points. Radar mounting must therefore be chosen from the material flow pattern and the intended measurement: local surface distance, usable inventory or high-level protection.

Map the material surface before selecting a nozzle

Identify filling and discharge locations, angle of repose, expected bridging and the normal operating range. Choose a measurement point that represents the control objective and remains clear of the filling stream. A centre-mounted radar may see a peak; an offset unit may see a slope. Neither automatically equals average inventory.

For irregular silos, compare level with weigh data, delivery records or a survey during commissioning. State the expected difference between point level and calculated volume.

Keep the beam clear of structures

Plot beam width from the antenna to the lowest measured level and include ladders, stiffeners, braces, feeders and wall curvature. Ensure the antenna projects as required beyond a restrictive nozzle and is aimed according to the manufacturer's guidance.

High-frequency radar can provide a narrower beam, but a poorly located nozzle still creates near-field reflections. Save an empty-silo echo curve before filling when access and safety conditions allow.

Manage dust and filling impact

Airborne dust may attenuate some instruments and can coat the antenna. Select a device and antenna proven for the material and range, and position it away from direct impact. Never use the radar housing or antenna as a wear plate.

If purge air is proposed, confirm that it will not introduce moisture, disturb combustible dust controls or pressurize the process connection improperly. Often a good location and suitable antenna are more reliable than continuous purge.

Account for buildup, static and hazardous dust

Check whether sticky powder can bridge across a nozzle or coat the antenna. Provide safe inspection and cleaning access. Review dust hazardous-area classification, surface temperature, certificates, cable glands, grounding and bonding for the complete installed assembly.

Static electricity and pneumatic filling can be significant. Follow the plant's electrical and explosion-protection design; measurement selection does not replace dust-hazard assessment.

Convert distance to inventory honestly

Volume depends on silo geometry and the actual surface shape. Mass additionally depends on bulk density, which can change with aeration, moisture and compaction. Use a documented strapping or geometric model and reconcile it with known transfers.

Exclude material in transit during filling and discharge when comparing instruments. Acceptance should cover empty, filling, stable and discharge states, with tolerances appropriate to operations rather than an unrealistic single-point promise.

Field checklist

Document filling point, discharge pattern, angle of repose and bridging risk.
Plot beam clearance past nozzles and internal structures.
Assess dust, antenna buildup, impact and cleaning access.
Verify hazardous-dust certificates, grounding and cable entries.
Validate point level and inventory conversion through a full operating cycle.

Common questions

Where should radar be mounted on a conical silo?

Choose the point from the filling and discharge pattern, not a universal fraction of diameter. The beam should avoid the inlet and structures while representing the control objective.

Can radar provide exact tonnes?

Radar measures distance. Tonnes require geometry and bulk-density assumptions, so reconcile the calculation with known transfers or weighing.

Why is the reading unstable during pneumatic filling?

The filling stream, dust cloud and changing pile can compete as targets. Review the echo curve, location and required update behavior during filling.

Need application support? Send the silo drawing, filling method, material properties, operating sequence, mounting photos and required inventory accuracy. Contact METRAVON with the site information so the recommendation can be checked against the actual operating conditions.