Ultrasonic Level Measurement

Ultrasonic Level Measurement

Endress+Hauser’s ultrasonic level portfolio (Prosonic) provides continuous, non‑contact measurement for liquids and bulk solids using time‑of‑flight acoustics. The range spans compact two‑wire instruments, separate sensors paired with field or panel transmitters, and hygienic variants, covering common industrial protocols (4–20 mA/HART, PROFIBUS) and FLEX tiers from Fundamental to Xpert. Typical duties include tank level, sump/basin monitoring, and open‑channel flow with integrated totalization. The global portfolio page summarizes 13 ultrasonic items across “sensor,” “sensor with transmitter,” and “transmitter” categories, sized for water & wastewater, chemicals, mining, power, and more.

Prosonic FDU sensors are the workhorses. FDU90 is a compact PVDF sensor for short ranges (up to 3 m in liquids) with optional anti‑icing heater and cable runs up to 300 m to the transmitter. FDU91 extends to 10 m (liquids), and FDU91F adds a fully welded 316L body and hygienic connections (CIP/SIP ratings). For larger vessels, FDU92 reaches 20 m, FDU93 25 m, and FDU95 addresses tall, dusty solids silos up to 45 m. All integrate temperature compensation, are flood‑proof (IP68), and are specified as largely independent of DK, density, and humidity, with a self‑cleaning face that minimizes build‑up effects.

For centralized measurement and control, Prosonic FMU90/95 transmitters provide robust signal evaluation and application functions. FMU90 drives up to two sensors with an envelope‑curve display for diagnostics, linearization tables, pump and rake control, and open‑channel/weir flow calculations, including storm‑overflow schemes, with measuring distances (sensor‑dependent) up to 45 m. FMU95 scales the concept to 5 or 10 channels, enabling multi‑point monitoring (e.g., large basins, tank farms) with menu‑guided setup, HART/PROFIBUS integration, and automatic FDU sensor recognition. Both are available in field housings or top‑hat rail designs.

Where a compact, two‑wire device is preferred, Prosonic FMU30 integrates sensor and transmitter for utilities and infrastructure. It offers quick commissioning from a four‑line display, on‑screen envelope curves, linearization (volume or open‑channel flow), and ranges up to 8 m in liquids (sensor‑dependent). FMU30 is well suited to wastewater plants, process‑water tanks, lift stations, and general storage/buffer vessels where simplicity and low installed cost are priorities.

Why ultrasonic, and when to choose which model? Ultrasonic’s non‑contact principle eliminates wetted diaphragms and impulse lines, reducing fouling and maintenance. The guided setup, temperature‑of‑flight correction, and interference‑echo suppression in the FMU platform stabilize measurement through changing conditions; hygienic models (FDU91F) support sanitary tanks; long‑range solids sensors (FDU93/FDU95) tackle silos, bunkers, conveyors, crushers, and stockpiles. For basins and channels, FMU90/95 deliver flow computation and relay logic for pump control. Apply ultrasonic broadly in water/wastewater, utilities, chemicals, and bulk solids, selecting sensor range/materials for the geometry and environment.

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