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Expert Insights Ensuring Accurate and Reliable Level Measurements in Tanks with Obstructions

Source: Press release Emerson 7 min Reading Time

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Sara Anderberg, non-contacting radar product manager at Emerson, explains how intelligent signal processing technology in modern transmitters enables organizations to meet the challenges of tank obstructions interfering with radar signal reflections.

Smart Echo Supervision reduces and often eliminates the need for intervention against false echoes. However, when intervention is required, it can be performed quickly and easily through a graphical user interface, simply by right clicking an echo to suppress it.(Source: Emerson)
Smart Echo Supervision reduces and often eliminates the need for intervention against false echoes. However, when intervention is required, it can be performed quickly and easily through a graphical user interface, simply by right clicking an echo to suppress it.
(Source: Emerson)

Non-contacting radar level transmitters are widely implemented throughout the manufacturing and process industries, especially in measurement applications where high accuracy, reliability and minimal maintenance are important requirements. These versatile devices are suitable for measuring the level of liquids, sludges, slurries and solids. However, one of the most challenging applications for this technology has traditionally been measuring level in tanks with internal obstructions, such as agitators, heating coils, pipes, ladders or baffles, for example.

This application creates difficulty for non-contacting radar devices because tank obstructions can interfere with their mode of operation. Radar level sensors work by emitting microwave signals that bounce off the material surface and are reflected back to the transmitter. These reflected signals are known as echoes and they enable the material level to be calculated. Obstructions within a tank can, however, also reflect microwave signals, creating what are known as false echoes. When this happens, it can become challenging for the radar system to identify which echo is from the material surface and which are false echoes coming from obstructions. As some liquids have a low dielectric constant – meaning that they poorly reflect radar signals – even slight interference from obstructions can have a major impact on the signal in these cases, which further complicates level measurement.

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