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METRAVON MV-RD705 is a guided wave radar for high-pressure liquid level measurement, with assemblies intended for demanding process temperatures. Selecting this instrument requires more than a maximum pressure and a probe length. The process seal, connection, probe and thermal isolation must be suitable for the same operating conditions, including startup, shutdown and cleaning.
Pressure and temperature must be reviewed together
The high-temperature option is listed up to 400 deg C. Pressure options are listed at 20 MPa and a separately specified 40 MPa configuration. These values describe available configurations, not a universal 400 deg C at 40 MPa operating point. Request the permissible pressure-temperature envelope for the exact assembly before approving it for the vessel.
| Order item | Evidence needed for approval |
|---|---|
| Process envelope | Normal and maximum pressure with the corresponding temperature at each operating state. |
| Pressure boundary | Connection standard, pressure class, facing, gasket and compatible process-seal construction. |
| Probe assembly | Drawing identifying rod, cable or other specified construction, insertion length and end attachment. |
| Listed distance range | 0.3-15 m; verify the span available from the ordered probe form. |
| Thermal installation | Insulation thickness, ambient exposure and clearance around the thermal-isolation section. |
| Control-system connection | 24 VDC two-wire 4-20 mA/HART, or an explicitly selected RS485/Modbus arrangement. |
Installing guided wave radar for high-pressure liquid level
Send a section drawing of the vessel nozzle and insulation. The heat-isolating section between the process connection and electronics needs to remain effective after installation; do not bury it in insulation without an approved arrangement. Process temperature is not the electronics ambient-temperature rating. Nearby hot pipework and direct sun also belong in the installation review.
Plan installation and removal during an appropriate isolated, depressurised and temperature-safe condition under the site's procedure. A high-pressure rating does not make the probe safe to loosen while the vessel is operating. Check maintenance headroom before ordering a rigid probe, and identify how a cable assembly would be restrained without contact with internal equipment.
Steam, cryogenic service and special configurations
Steam-drum measurement needs assessment of vapour conditions and any required compensation. Do not treat a high-temperature rating as proof that steam compensation is included. Cryogenic duty likewise needs a specifically approved low-temperature seal, material and connection arrangement; it cannot be inferred from the high-temperature version.
For a lower-duty liquid tank, compare the MV-RD701 rod or cable instrument after defining the operating envelope. Selecting RD705 only because its family limits are higher can add cost and installation complexity without addressing the actual measurement problem.
Acceptance must include operating conditions
Check the delivered model, probe drawing, materials and pressure-boundary documentation against the order before installation. Then confirm the level reference, measuring endpoints and receiving-system scaling. Where feasible, compare the reading with an independent reference after the vessel reaches normal operating temperature and pressure, as well as during the initial cold test.
For a digital connection, verify the selected measured variable, units, update behaviour and failure indication at the PLC or RTU. Do not assign a safety function solely because the instrument provides a continuous level signal; hazardous-area and safety requirements need documentation applicable to the supplied configuration.
Questions before requesting a price
Q1. Is every MV-RD705 supplied for 40 MPa?
No. The 40 MPa configuration must be specified and confirmed with its temperature limits and process connection. A quotation that states only the family model and maximum pressure leaves the pressure-boundary selection incomplete.
Q2. Can the 15 m range be applied to any probe construction?
No. The required length must be available for the chosen probe form and mounting. Obtain the assembly drawing with the usable measuring span and dead zones; do not order a long rigid probe merely because the family listing extends to 15 m.
For a high-pressure level quotation, provide the fluid, operating-state pressure and temperature pairs, nozzle drawing, insulation details, level span, output and required documentation. This lets the quotation identify the pressure-rated assembly and any special compensation separately.
