Technical Characteristics and Performance
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Extended Measuring Range: The FDU91 provides a reliable measuring range of up to 10 m in liquids and 5 m in bulk solids. This makes it ideal for medium-sized silos, wastewater basins, and large-scale industrial sumps.
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Time-of-Flight Precision: By emitting ultrasonic pulses and measuring the return time, the sensor determines the distance to the product surface. An integrated temperature sensor provides real-time compensation for the speed of sound, ensuring accuracy even in outdoor installations with fluctuating temperatures.
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Extreme Chemical Resistance: The sensor is hermetically welded and made of PVDF, making it highly resistant to aggressive chemicals, acidic vapors, and corrosive industrial environments.
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Self-Cleaning Membrane: The ultrasonic transducer vibrates during operation, which creates a self-cleaning effect that prevents the accumulation of dust, moisture, or light build-up on the sensor face.
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Robust IP 68 Protection: The FDU91 is completely flood-proof and weather-resistant. This durability allows for reliable performance in wastewater treatment plants, outdoor flumes, and heavy industrial sites.
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Seamless Integration: The sensor is automatically detected by the Prosonic FMU90 or FMU95 transmitters, allowing for “plug-and-play” setup and simplified commissioning.
Technical Specification Matrix
| Feature | Technical Details |
| Measuring Principle | Ultrasonic (Non-contact) |
| 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 +80 °C (-40 to +176 °F) |
| Process Pressure | 0.7 to 4 bar (10 to 58 psi) |
| Sensor Material | PVDF (Hermetically welded) |
| Degree of Protection | IP 68 |
Primary Applications
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Medium-Sized Liquid Storage: Monitoring levels in chemical tanks, oil-water separators, and wastewater wet wells.
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Open Channel Flow: Measuring high-volume flow in large flumes and weirs for municipal water management.
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Bulk Solid Monitoring: Level detection for sand, plastic pellets, or grain in medium-height silos or on conveyor discharge points.
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Flood-Prone Areas: Due to its IP 68 rating, it is perfect for level monitoring in storm-water overflow basins.
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Hazardous Environments: Fully certified for use in areas where explosive gas or dust atmospheres may be present.
