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If liquid reaches the radar antenna during an overfill event, a normal-looking display after the level falls is not sufficient evidence for return to service. Radar antenna flooding can change the measurement conditions and leave residue or damage. The event also raises a separate question: why did the level reach that position?
Stabilise the process before inspecting the instrument
Follow the site's incident and isolation procedures. Do not loosen the process connection, remove the instrument or open an unsafe enclosure while pressure, temperature or hazardous conditions remain. Preserve available event records before resetting alarms or clearing diagnostics.
Record the highest known surface, duration, liquid identity and associated pressure or temperature changes. Establish whether the antenna alone was contacted or external electrical parts were also exposed. Those are different inspection scopes and should not be described by one generic statement that the sensor "got wet."
| After-event check | Question to resolve |
|---|---|
| Process assembly | Was the selected connection and material construction exposed within its permitted conditions? |
| Antenna surface | Does residue or visible damage require an approved cleaning or service assessment? |
| Electrical enclosure | Were entries, cables or housing exposed in a way requiring separate inspection? |
| Measurement | Does the restored reading agree with an appropriate known condition? |
Do not interpret radar antenna flooding through an IP label alone
Enclosure protection concerns specified ingress conditions; it does not establish measurement through a flooded antenna or suitability for every process liquid. The METRAVON MV-RD12 must be assessed using its selected connection, seal, housing and operating conditions.
The normal non-contact measurement path is from the antenna to the liquid surface through the space above it. When that arrangement is lost, do not assume the previous level interpretation remains valid. Confirm the applicable fault response and recovery checks for the supplied configuration.
Check where the highest permitted surface can reach
Reconcile the installed radar reference with the highest permitted liquid surface, not just the normal setpoint. Include foreseeable overshoot, waves or foam where these affect the closest approach. Use the supplied instrument procedure to assess the near-range requirement; there is no universal clearance established by the MV-RD12 name. If an allowed operating state can wet the antenna, review the mounting and stopping sequence rather than treating cleaning as a permanent correction.
Review the cause as well as the recovered signal
Compare the event with the permitted upper level, configured span and actual stopping sequence. Check whether the measurement became unavailable before the process stopped, whether the receiver held an old value, and whether another part of the control chain failed. The normal level transmitter must not be assumed to provide an independently qualified overfill protection function.
After approved inspection and any required service, verify local measurement and receiver behaviour before release. If cleaning changes the installation or leaves uncertain residue, include that in the test scope. Keep the unresolved incident cause visible even if the instrument itself passes its checks.
When the incident has latched an alarm or stopped a transfer, use the alarm acknowledgement and restart checks alongside the physical inspection. Clearing an alarm display does not establish that the stopping cause has been corrected or that operation may restart.
Q1. Can lowering the level automatically clear the incident?
It can restore the normal measurement path, but does not establish assembly condition, correct alarm response or the cause of the overfill. Those need separate review.
Q2. Should the blocking distance be reduced after the event?
Not as an automatic remedy. Establish the physical near-range requirement and the documented meaning of the setting; a software change cannot repair an unsuitable installation.
Summary
Separate measurement recovery from approval to resume operation. Provide the MV-RD12 identity, exposure details and event trend for the instrument assessment alongside the site's incident review.
