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METRAVON MV-RD21-120G is listed as a 120 GHz radar level meter for bulk-solid silos. Specify it from the required measurement task and an approved configuration sheet, rather than transferring the range, lens or electrical data of another radar in the same series. Selection starts with the nearest and farthest material surfaces, the filling conditions and the available mounting position.
Decide what the silo reading must control
A radar reports the distance to a reflecting surface within its beam. Converting that distance to level requires the correct mounting reference and silo height. A single reading does not directly measure average fill height, volume or tonnes. For a filling stop, define the maximum permitted surface at the chosen measurement point and allow for material still moving through the conveyor or pneumatic line after the stop command. For stock reconciliation, agree how pile shape and bulk density will be checked independently.
Send a silo section showing the roof, inlet, outlet, braces, ladders and expected pile during both filling and discharge. The beam widens with distance, and a narrow-beam designation cannot make an unrepresentative mounting point suitable. An apparently stable reading from an empty silo is not proof that the antenna will see the material through a dusty delivery.
MV-RD21-120G configuration checks before ordering
| Item | Information for the quotation |
|---|---|
| Medium and range | Bulk-solid silo duty. Supply nearest and farthest surface distances; obtain the offered measuring span and near-zone limits for the quoted configuration. |
| Antenna and beam | Provide nozzle bore, length and nearby obstructions. Obtain the antenna dimensions, materials and beam specification before approving the roof layout. |
| Connection | Send the mating flange or thread drawing, required sealing arrangement and available service access. Confirm the supplied connection rather than selecting from a similar photograph. |
| Process limits | List normal operation, filling, cleaning and credible excursions as temperature-pressure pairs. Require the offered assembly limits, including the enclosure environment. |
| Instrument accuracy | State the permitted installed level error and reference method. Require a model-specific distance specification and test conditions; do not apply it directly to inventory mass. |
| Power and output | Identify the receiving PLC or RTU input and available power. Confirm the offered output, supply, terminal drawing and protocol documentation as one configuration. |
| Housing and approval | Confirm enclosure material, ingress protection and cable entries. For a classified area, obtain a certificate and installation conditions covering the exact supplied assembly. |
The approved configuration sheet should identify the antenna, process connection, seal, housing and electronics together. Require the quoted model designation and drawing revision on the order, along with the applicable operating limits. An offer for a related model is not sufficient evidence for this assembly.
Plan for dust, purge and maintenance
Choose the roof position before deciding whether to add purge air. Avoid the falling feed stream and check where dust returns during filling. If a purge-equipped antenna is proposed, confirm its availability and construction for this model. Purge does not substitute for a clear measurement path or a cleanable installation. If it is required, specify the air source, piping, isolation and maintenance access on the quotation. Do not assume that the purge connection is included in the basic unit.
Commission against a known material condition. Record raw distance, selected echo, displayed level, process state and the corresponding PLC or RTU value. Repeat during filling and discharge when those states determine the control decision. If a later reading jumps, compare the saved echo and process events before changing suppression or damping; aggressive filtering can hide a real high-level change.
Questions before ordering
Q1. What measurements are needed to specify the distance range?
Measure from the intended radar reference plane to the lowest required surface and the closest permitted pile. Include the roof nozzle and material remaining in transit after a filling stop. Compare both distances with the offered configuration, then verify the difficult filling state during acceptance; tank height alone does not establish a usable span.
Q2. When should the purge interface be specified?
Consider it when dust accumulation on the lens is a credible maintenance problem and a suitable clean, dry air supply can be provided. Confirm the purge hardware and air requirements for the ordered unit; include safe access to inspect the lens even when purge is fitted.
Q3. Can this instrument report silo tonnes directly?
No. It measures distance. A volume estimate needs a vessel model and a representative surface assumption; mass also depends on bulk density. Validate those conversions separately if the reported quantity will be used for inventory or settlement.
Q4. Can HART and Modbus be assumed on the same delivered unit?
No. Select the electrical version for the receiving input. For an RS485 network, obtain the supplied register map, power requirements, address and fault-status definition. For a 4-20 mA loop, verify the receiver scaling and available supply voltage.
Q5. Is IP67 evidence of approval for combustible dust?
No. Ingress protection and hazardous-area approval are different checks. Submit the site classification and request the certificate, marking and installation conditions for the exact assembled instrument before accepting it for the classified location.
Send a usable enquiry
Provide the silo section, material description, filling and discharge arrangement, nearest and farthest surface distances, dust and buildup history, temperature-pressure cases, flange drawing and required PLC or RTU interface. State whether the reading is for filling control, operator indication or stock estimation. Ask METRAVON to confirm the MV-RD21-120G configuration against those conditions before the mounting and cabling are fixed.
