Foundry sand silo level measurement needs separate checks for new sand and reclaimed sand. Reclaimed material may arrive hotter and with a different distribution of fines or residual binder. A radar accepted on a clean, cool sand delivery should not automatically be accepted for the return-sand stream.
Start with the return-sand temperature
The METRAVON MV-RD21S uses a PE lens and is specified for -40 to 80 deg C process conditions. It is a candidate for sand storage only within that thermal duty and after the surface return has been assessed. Measure or establish the credible incoming-material and gas exposure, including restart conditions.

For a hotter duty, assess the MV-RD21G hot-solids assembly against the actual conditions. Its 200 deg C published upper limit is not a guarantee for an unspecified flange, seal or electronics environment. Keep the accepted assembly details attached to the purchase specification.
Make foundry sand silo level measurement useful to the mixer
The mixer needs available material, not merely a plausible number on the silo display. Position the radar to observe a meaningful surface during filling and discharge, while keeping it clear of falling abrasive material. The outlet, cone geometry and any buildup affect whether indicated stock is accessible.
| Duty | Selection detail | Acceptance evidence |
|---|---|---|
| New sand | Particle distribution and filling position | A usable echo during delivery and at the lowest operating level. |
| Return sand | Temperature, fines and binder residue | Performance on the real return stream, including deposits after operation. |
| Mixer feed | Extraction arrangement and minimum usable reserve | Level trend compared with actual feeder and mixer demand. |
| Stock estimate | Pile profile, vessel conversion and bulk density | Reconciliation against independent material records. |
Do not turn a feed interruption into a calibration adjustment
If the mixer runs short while the radar still reads high, compare feeder operation and the material path first. A bridge or dead region can leave material in the silo without supplying the outlet. Changing the empty-distance setting cannot correct that mechanical condition.
If the radar itself jumps or loses the surface, examine the echo and lens condition. Distinguish a changing pile from a fixed reflection or accumulated material near the nozzle. After cleaning, restore the recorded orientation and confirm the reading before changing suppression or filtering.
Questions for a sand-handling retrofit
Q1. Can the same instrument configuration be used on both silos?
Possibly, but only if both duties fit its temperature, mounting and measuring requirements. Compare the two process descriptions explicitly; common flange dimensions do not make new and reclaimed sand equivalent applications.
Q2. Will level provide the mixer batch weight?
No. Silo level supports reserve and filling decisions. Batch weight requires the appropriate weighing or dosing measurement; converting a changing sand pile into tonnes does not turn the silo radar into a batch scale.
Q3. Which interface should be specified for an existing PLC?
Use the available input and required diagnostics to choose the ordered 4-20 mA or RS485/Modbus RTU configuration. Verify the supply and scaling at both ends. Request the matching terminal and register information rather than assuming it is identical to the removed sensor.
Summary
For a foundry-sand level quotation, identify new or return sand, thermal exposure, fill and extraction positions, and the reserve required by the mixer. These details determine whether MV-RD21S is suitable or a different thermal assembly needs review.
