Foundry Sand Silo Level Measurement and Radar Installation

Foundry sand silos feed time-sensitive moulding and core-making processes. Fine dust, abrasive particles, pneumatic filling and uneven piles can challenge the instrument, while an unexpected low inventory can stop a mixing line. A useful design connects continuous level with replenishment and batching data but keeps blockage and overfill protection as clearly defined duties.

Characterize the sand system

Record new sand, reclaimed sand and additive grades separately, including particle-size distribution, moisture, bulk density, temperature and dielectric behaviour. Reclaimed material may contain fines or binder residue that changes flow, reflection and wall buildup.

Document conveying method, refill rate, batch consumption and the time between a delivery command and material reaching the silo. These values determine useful alarm margins more directly than a generic percentage.

Map fill and discharge geometry

Locate pneumatic or mechanical inlets, filters, roof steelwork, mixer outlets and any flow aids. Filling often creates an eccentric peak; discharge can create a moving valley. Place the beam on a representative surface and outside the direct impact stream.

Bridging or rat-holing may leave material above a starved mixer. Combine level with feeder current, batch weight or suitable flow detection when continuity of supply matters.

Control dust and abrasion

Select antenna aperture, frequency and beam angle for the weakest expected return through dust. Avoid long narrow nozzles that collect packed fines. Provide the specified antenna projection and safe inspection access without fitting an impact plate inside the beam.

Non-contact radar removes a probe from the sand, but antenna face, flange, bracket and cable can still be abraded or struck. Inspect early for erosion and loose alignment after high-throughput operation.

Treat inventory as an estimate

Radar measures one point on a sloping surface. Volume depends on silo and pile geometry, and tonnes require bulk density that varies with moisture, fines and compaction. Preserve raw level and show only justified precision.

Reconcile inventory against delivery weights and mixer batch totals using matching sand grades and timestamps. Separate errors due to material in transfer lines, density assumptions and the measured surface point.

Design alarms for operations

For high level, include signal damping, control delay, blower or conveyor stopping time and sand already in the line. For low level, allow enough stock for reorder and delivery delay while protecting the mixer from starvation.

Configure lost echo and held values as explicit quality states. A stale normal-looking number must not continue satisfying an automatic refill or feeder permissive.

Commission representative cycles

Capture echo curves at low level, during refill, after settling and while batches discharge. Verify local reading, PLC scaling, trend, alarms and any inventory calculation. Record sand grade and moisture condition with the test.

Use as-found deposits and signal margin to set inspection intervals. Reassess after filter, conveying, reclaim or binder-system changes. Observe at least one complete replenishment cycle and compare radar change with delivered mass and mixer consumption; this exposes timing and material-in-line errors that a static level check cannot show.

Engineering checklist

Record each sand grade and density range.
Map inlet impact, pile and mixer outlet.
Verify dust echo margin and antenna protection.
Separate level from flow and mass.
Include conveying delay and material in transit.
Commission during refill and batch discharge.

Frequently asked questions

Can radar detect a bridge above the mixer outlet?

Not reliably by itself; use feeder or flow evidence when blockage must be detected.

Does non-contact radar eliminate abrasion?

It avoids a wetted probe, but exposed antenna and mounting still require protection.

Can level be converted directly to tonnes?

Only as an estimate using validated geometry, pile and bulk-density assumptions.

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