Ultrasonic level measurement is widely used across industrial applications because it is non-contact, reliable, and relatively easy to integrate. However, installations can sometimes experience unstable readings, false echoes, or performance issues that are often misattributed to sensor malfunctions.
In practice, most ultrasonic level measurement problems stem from application and installation oversights rather than sensor electronics. Understanding these factors early helps engineers avoid rework, commissioning delays, and unnecessary technology changes.
Blind Zones Are Overlooked During Sensor Placement
Every ultrasonic level sensor has a minimum sensing distance, commonly referred to as the blind zone. Any target inside this zone cannot be measured reliably.
Issues arise when sensors are mounted too close to maximum fill levels or when tank drawings reflect nominal rather than real operating conditions. Buildup on tank walls, temperature related sound velocity changes, and mechanical tolerances further reduce usable range.
In applications that require the tank to be completely filled a riser can be used to mount the sensor above the tank, but they must be sized and positioned to remain fully outside the sensor’s blind zone.
Leaving sufficient margin between the maximum process level and the sensor’s blind zone is one of the most effective ways to improve ultrasonic level measurement stability.
Internal Tank Obstructions Cause False Echoes
Ultrasonic sensors measure distance by detecting reflected sound waves. Internal structures such as ladders, agitators, fill pipes, stiffeners, or weld seams can reflect sound just as effectively as liquid surfaces.
When these objects fall within the sensor’s beam width, the sensor may lock onto the wrong target, produce unstable outputs, or appear to fail intermittently. These issues are rarely solved through filtering alone.
Beam angle, mounting orientation, and standoff distance typically have a greater impact on performance than raw resolution or output scaling.
Liquid Surface Conditions Affect Measurement Stability
Ultrasonic level sensors rely on a consistent acoustic reflection from the target surface. Process conditions that disrupt this reflection can reduce accuracy or response time.
Common challenges include surface turbulence during filling or emptying, foam layers that absorb sound waves, and sloped or uneven liquid surfaces. While ultrasonic sensing may still function in these conditions, stability often degrades. That is why in turbulent or sloshing applications, stand pipes are often used to create a calm, consistent measurement surface
Evaluating surface behavior during normal operation is critical when selecting ultrasonic sensors for tank level measurement.
Output Selection
Many ultrasonic level measurement issues originate downstream of the sensor. Output type selection directly affects signal integrity and system reliability.
Voltage outputs can perform well in short cable runs and controlled panel environments. In industrial installations with long distances or electrical noise, 4–20 mA current loops are generally more robust.
Choosing the output type early, based on the entire control system, reduces commissioning issues and unnecessary troubleshooting.
Hazardous Location Requirements Add System Complexity
In hazardous area applications, the ultrasonic sensor is only one part of a compliant system. Safety barriers, grounding methods, cable selection, and certification requirements are all needed for an intrinsically safe system.
Confusion between Zone and Class/Division approval systems is common, particularly in global OEM designs. Assuming approvals are interchangeable often leads to redesigns late in the project lifecycle.
Clarifying hazardous area requirements early helps ensure both compliance and long-term measurement reliability.
Conclusion
Ultrasonic level measurement performs extremely well when applied intentionally. Most failures are not inherent technology limitations but the result of design oversights made early in the project.
Engineers who account for blind zones, beam behavior, internal obstructions, surface conditions, output integration, and hazardous area requirements typically achieve stable, repeatable results.
Ultrasonic sensing delivers the most value when it is selected for the right application and installed with real operating conditions in mind.