Critical Technical Advantages
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Elimination of Traditional DP Issues: By replacing oil-filled capillaries and impulse lines with digital cables, the FMD71 eliminates problems like “icing up,” clogging, leaks, and measurement drift caused by ambient temperature fluctuations affecting fill-fluids.
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Ceramic Sensor Robustness: The system utilizes high-purity (99.9% Al2O3) ceramic sensors. These are exceptionally resistant to vacuum, corrosion, and abrasive media, providing much higher mechanical stability than metallic diaphragms.
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Minimized Safety Risks: The electronic architecture removes the risk of process media leaking through impulse lines into the environment or the control room. The system is designed to provide high reliability in pressurized tanks and distillation columns.
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Multivariable Data via HART: From a single system, you can retrieve the calculated differential pressure, the absolute head pressure, and the individual temperatures of both sensors. This provides a comprehensive overview of the tank’s status.
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Superior Long-term Stability: The combination of digital signal processing and ceramic sensor technology ensures high reproducibility and minimal recalibration requirements, leading to a low total cost of ownership.
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Constant System Diagnostics: The FMD71 features continuous health monitoring. Because the connection between the sensors and the transmitter is digital, the system can instantly detect and report communication errors or sensor failures via HART diagnostics.
Technical Performance Matrix
| Feature | Details |
| Measuring Principle | Electronic Differential Pressure (2 Sensors) |
| Sensor Type | Capacitive Ceramic (Oil-free) |
| System Accuracy | Up to ±0.07% |
| Measuring Range | 100 mbar to +40 bar (6 to 600 psi) |
| Process Temperature | -40 up to +150°C (-40 to +302°F) |
| Output | 4 to 20mA with HART |
| Approvals | ATEX, IECEx, Hygienic (3-A, EHEDG) |
Primary Applications
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Pressurized Storage Tanks: Accurate level measurement in tanks where the gas phase pressure varies significantly.
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Distillation Columns and Evaporators: Monitoring levels and pressure drops in high-temperature vacuum or pressure environments.
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Hygienic Vessels: Level measurement in food or pharma tanks where impulse lines would create “dead legs” and cleaning risks.
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Outdoor Cold-Climate Installations: Eliminating the need for heat tracing or insulation on impulse lines to prevent freezing.
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Tall Vessels: Where long capillary lengths in traditional systems would cause excessive temperature-induced measurement errors.
