Endress+Hauser Prosonic FDU91F – Hygienic Ultrasonic Sensor for Level and Flow Measurement
The Prosonic FDU91F is a hygienic version of Endress+Hauser’s proven ultrasonic sensor series, designed for continuous non-contact level measurement of liquids, pastes, sludges and bulk materials, as well as flow measurement in open channels and measuring weirs.
With a fully welded 316L stainless steel construction, hygienic process connections and reliable ultrasonic technology, the FDU91F is especially suitable for applications where cleanability, chemical resistance and long-term measurement stability are essential.
Reliable Ultrasonic Measurement Without Medium Contact
The FDU91F uses the time-of-flight ultrasonic measuring principle. The sensor sends ultrasonic pulses toward the medium surface and calculates the distance according to the returning signal time.
Because the sensor does not contact the process medium, measurement is unaffected by changes in conductivity, dielectric constant or density, making it a flexible solution for different liquid and bulk material applications.
Key performance:
Measuring principle: Ultrasonic time-of-flight
Accuracy: ±2 mm + 0.17% of measured distance
Maximum measuring range:
Liquids: up to 10 m
Solids: up to 5 m
Blocking distance: 0.3 m
Process temperature: –40 to +105 °C
CIP temperature: Up to 135 °C for 30 minutes
Process pressure: 0.7 to 4 bar abs
Wetted parts: Fully welded 316L stainless steel
Protection rating: IP68 / NEMA 6P
Communication: Via FMU90/FMU95 transmitter with HART or PROFIBUS DP
Hygienic Design for Food and Life Science Applications
The FDU91F is developed for hygienic process environments where material compatibility and cleanability are critical.
The sensor features a fully welded 316L construction, helping provide excellent chemical resistance and reliable operation during cleaning processes. Hygienic process connections such as Tri-Clamp are available for sanitary installations.
Typical applications include:
Food and beverage tanks
Dairy processing
Pharmaceutical production
Biotechnology applications
Hygienic storage vessels
Clean process systems
Stable Measurement Even in Challenging Conditions
The FDU91F is designed to maintain reliable performance in demanding process environments.
The sensor provides a self-cleaning effect that helps reduce buildup on the measuring surface, improving measurement reliability in applications involving:
Sticky media
Sludge
Condensation
Changing process conditions
Frequent cleaning cycles
Integrated Temperature Compensation for Higher Accuracy
Ultrasonic measurement can be influenced by temperature changes because sound velocity varies with temperature.
The FDU91F includes an integrated temperature sensor that automatically compensates for temperature effects, helping maintain accurate measurement performance during changing operating conditions.
Flexible Installation with Separate Transmitter
The FDU91F uses a separated sensor and transmitter design, allowing installation flexibility in hygienic plants and demanding environments.
The sensor can be installed up to 300 m away from the transmitter, allowing electronics to be positioned in a convenient and protected location.
Compatible transmitters include:
This configuration simplifies installation while improving accessibility for commissioning and maintenance.
Reliable Solution for Level and Open Channel Flow Measurement
The Prosonic FDU91F is not limited to tank level applications. It can also be used for open channel flow measurement with suitable Endress+Hauser transmitters.
Typical applications include:
Liquid level measurement
Bulk solid level measurement
Sludge level monitoring
Open channel flow measurement
Measuring weirs and channels
Its hygienic construction and non-contact principle make it a reliable choice for applications where direct contact measurement is undesirable.
Frequently Asked Questions
What is the Prosonic FDU91F used for?
The FDU91F is used for continuous non-contact level measurement of liquids, pastes, sludges and bulk solids, and can also support open channel flow measurement.
What is the difference between FDU91 and FDU91F?
The FDU91F is the hygienic version of the ultrasonic sensor, featuring fully welded 316L construction and hygienic process connection options, while the standard FDU91 uses PVDF construction.
What is the maximum measuring range of FDU91F?
The FDU91F can measure up to 10 m for liquids and 5 m for solids.
Can the FDU91F be used in CIP applications?
Yes. The sensor supports CIP cleaning conditions up to 135 °C for 30 minutes depending on configuration.
Which transmitter works with the FDU91F?
The FDU91F is designed to connect with Endress+Hauser FMU90 and FMU95 ultrasonic transmitters.
Why choose ultrasonic measurement for hygienic applications?
Ultrasonic measurement provides non-contact level detection, reducing contamination risks and maintenance requirements while maintaining reliable process monitoring.
