Technical Characteristics and Sanitary Design
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Hygienic and Robust Construction: Unlike standard sensors, the FDU91F is hermetically welded in 316L stainless steel. This provides superior chemical resistance and allows for the use of hygienic process connections like Tri-Clamp, making it suitable for cleanable environments.
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Extended Temperature Range: The FDU91F can operate in process temperatures up to 105 °C, allowing it to withstand hotter cleaning cycles or higher-temperature process environments compared to standard PVDF sensors.
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Non-Contact Time-of-Flight: The sensor calculates level by measuring the time it takes for an ultrasonic pulse to travel to the surface and back. An integrated temperature sensor provides real-time compensation for changes in the speed of sound, ensuring high accuracy even during temperature fluctuations.
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Self-Cleaning Membrane: The high-frequency vibration of the stainless steel sensor face naturally sheds moisture and prevents dust build-up, ensuring the signal remains clear without the need for manual cleaning.
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Separate Installation Logic: The sensor is mounted in the process while the transmitter (FMU90/FMU95) is installed in a convenient location up to 300 meters away. This protects the electronics from harsh process conditions and makes commissioning easier.
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Weatherproof and Flood-Proof: With an IP 68 rating, the sensor is completely protected against water ingress, even if temporarily submerged, which is common in wash-down areas or outdoor flumes.
Technical Specification Matrix
| Feature | Technical Details |
| Measuring Principle | Ultrasonic (Non-contact) |
| Sensor Material | 316L Stainless Steel (Fully welded) |
| Max. Range (Liquids) | 10 m (33 ft) |
| Max. Range (Solids) | 5 m (16 ft) |
| Blocking Distance | 0.3 m (1 ft) |
| Process Temperature | -40 to +105 °C (-40 to +221 °F) |
| Process Pressure | 0.7 to 4 bar (10 to 58 psi) |
| Degree of Protection | IP 68 |
Primary Applications
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Food and Beverage Storage: Monitoring levels of juices, sauces, or dairy products in large storage tanks where hygienic connections are mandatory.
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Life Sciences and Biotech: Level measurement in buffer tanks or chemical preparation vessels requiring 316L compatibility.
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Open Channel Flow in Sanitary Plants: Measuring flow rates in flumes for treated wastewater or process water within food processing facilities.
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Aggressive Media in Storage: Monitoring acids or alkalis in tanks where a hermetically sealed metal sensor provides better longevity than plastic.
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Silos with Low Structural Height: Measuring powders or granules in silos where non-contact measurement is preferred to avoid mechanical stress on the vessel roof.
