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Radar level transmitter types cannot be identified reliably from the word "rod" in a quotation. A short rod-shaped antenna can transmit through the tank's gas space, while a guided-wave rod must extend into the measured material. Buying one as a replacement for the other changes the installation and the measurement path.
Two rod-shaped parts with different jobs
The METRAVON MV-RD901 uses a PTFE rod antenna for non-contact liquid measurement at 26 GHz. Its published antenna lengths are 50-250 mm. The antenna needs an unobstructed view into the vessel; it is not intended to span the tank depth as a contact probe.
The MV-RD701 is guided-wave radar. Its rod or cable carries the signal along a probe extending into the process. The listed maximum lengths differ: up to 6 m for a rod and 30 m for a cable. Those maximum physical lengths are not fully usable measuring spans because the end regions also need review.
Radar level transmitter types change the installation drawing
| Part | What the drawing must show |
|---|---|
| Rod antenna | Nozzle bore, antenna projection and the open path toward the liquid surface. |
| Rigid probe | Insertion depth, internal clearances and overhead room for removal. |
| Cable probe | Suspended length, possible movement, inlet forces and any approved end arrangement. |
The two model names also imply different material and process reviews. MV-RD901's described configuration is atmospheric, with a 0.3-10 m listed distance interval. MV-RD701 offers 304 or 316L probe metal. Neither a PTFE antenna nor a stainless-steel probe establishes compatibility with every liquid, cleaning agent or temperature.
Ask the supplier to mark the measurement path
Request a section drawing that labels the antenna or probe, the reference plane and the intended high and low surfaces. For free-space measurement, inspect beam obstructions across the operating range. For a guided probe, examine what can strike, pull or coat it during filling and discharge.
Keep the electrical choice separate from that mechanical decision. Both product families describe 4-20 mA/HART and separately specified RS485/Modbus arrangements. Matching an output name does not make their process connections, probe lengths or mounting loads interchangeable. Obtain the ordered version's terminal drawing.
Questions when the quotation only says "rod radar"
Q1. Can the antenna be lengthened to reach the liquid?
Do not modify it that way. An antenna extension and a guided-wave probe are different designs. Select the correct measurement principle and approved assembly rather than adapting a short antenna into a contact element.
Q2. Does a cable probe avoid every obstruction?
No. A cable can move under process forces and contact nearby structures. Its path must remain suitable during operation, not just while hanging in an empty vessel.
Q3. Is a photograph sufficient to identify an installed unit?
Use it with the nameplate, order record and dimensional drawing. Similar housings can contain different electronics, and a photograph may hide the process-facing part.
Summary
Specify whether the signal travels through open space or along an immersed probe before comparing prices. Send the existing assembly identification and tank section to distinguish an MV-RD901 antenna application from an MV-RD701 probe application.
