Ultrasonic Level Measurement

Ultrasonic Level Measurement

Ultrasonic level measurement provides continuous level measurement in liquids and solids using ultrasonic level sensors. The instrument emits an ultrasonic pulse and measures the time-of-flight of the echo returning from the product surface; distance is converted to level using the tank geometry. Because it is typically non-contact, it is often selected for open vessels and utility services where wetted probes are undesirable and installation simplicity is valued.

Strengths include cost-effective continuous measurement, straightforward mounting, and minimal product contact concerns. Ultrasonic is widely used in water and wastewater environments because it can measure level over open channels, basins, and wet wells without touching potentially corrosive or contaminated liquids. With proper configuration, it also supports level measurement in bulk solids bins where dust loading and surface stability are manageable.

The principal limitations are tied to acoustic propagation. Speed of sound varies with temperature and gas composition, so temperature compensation is often essential for accuracy. Foam, heavy vapor layers, turbulence, and strong air currents can scatter or absorb the signal and reduce echo quality. Ultrasonic sensors also have a near-field “dead band” close to the face where measurement is not valid, which must be considered in nozzle and maximum-fill design.

Common applications include lift stations, pump sumps, equalization basins, clarifiers, chemical day tanks, and general service storage where reliable trending is more important than high-end custody-transfer precision. In solids handling, ultrasonic can be used for moderate-range inventory measurement in bins containing granulates or powders when installation geometry keeps the acoustic path clear of filling streams and obstructions.

Selection focuses on range, beam angle, mounting height, and the vessel’s internal geometry to avoid false echoes from ladders, braces, and inlets. Where echo conditions are challenging, stilling pipes, baffles, or alternate technology may be more appropriate. Integration typically includes signal damping tuned to process dynamics and diagnostics/alarming designed to distinguish “no echo” conditions from real level change.

George E. Booth Co., an exclusive authorized representative of sales and service for Endress+Hauser.