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Comparing radar vs ultrasonic in closed tanks requires more than checking the liquid and distance range. The space above the liquid is part of an ultrasonic measurement path, while the installed sensor also forms part of the vessel assembly. Gas conditions and mechanical pressure suitability must therefore be evaluated separately.
What changes in the space above the liquid?
Ultrasonic instruments send sound through a medium. Gas composition and temperature affect sound propagation, and a vacuum does not provide the ordinary gas path needed for that measurement. An electromagnetic radar signal does not depend on an acoustic path. This distinction can support a radar assessment, but it is not a blanket performance guarantee for every vapour, foam or vessel condition.
Describe normal operation and transitions: evacuation, gas purging, filling, heating and venting. A measurement that works in an open vessel during testing may encounter a different path after the tank is closed and the process starts. Do not use the commissioning atmosphere as the only basis for selection.
Radar vs ultrasonic in closed tanks: two separate reviews
| Review | Questions that need an answer |
|---|---|
| Propagation | What gas, temperature and pressure states exist above the surface, and how do they change? |
| Target | What liquid surface, foam, condensate or agitation will the instrument encounter? |
| Assembly | Are the connection, seal and exposed components suitable for the complete pressure-temperature duty? |
| Availability | Must the reading remain valid during evacuation, purging and other transitions? |
A radar alternative still needs a pressure specification
The METRAVON MV-RD12 is a liquid radar offered in different process configurations. Do not treat its measurement principle as proof that any supplied version is suitable for vacuum or a particular positive pressure. Request confirmation for the specified connection, seal, temperature and pressure range, including the lowest absolute pressure where relevant.
Write whether each pressure value is absolute or gauge. A pressure figure without that reference can be misunderstood, especially when discussing vacuum. Supply transient conditions as well as normal operating values; this article provides no universal pressure rating or allowable rate of pressure change.
Test during the conditions that change the path
Where a trial is required and authorised, compare the indicated distance or level with a suitable reference through representative process states. Record loss of measurement or invalid-value handling as well as the readings that succeed. Do not deliberately move a vessel outside its operating limits to prove an instrument.
Q1. Can temperature compensation correct every gas change in an ultrasonic system?
Temperature compensation alone cannot account for an unknown change in gas composition. Check which gas conditions the specific ultrasonic instrument supports and whether those conditions cover purging, evacuation and normal operation. A successful test in ambient air does not establish performance throughout that cycle.
Q2. Does choosing radar remove the need to review condensate?
No. Deposits or condensate at the antenna and changes at the target remain application questions. Review the actual exposure rather than transferring an advantage in propagation into immunity to installation problems.
Summary
Match the measurement path and the mechanical assembly to the closed-tank duty. Send the gas states, pressure reference, temperature and vessel geometry for a documented radar selection assessment.
