Technical Characteristics and Safety Performance
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Universal Vibronic Principle: The tuning fork vibrates at its resonance frequency. When submerged in liquid, the frequency drops; the electronics detect this change and trigger the switching state. This principle is extremely robust against changing process conditions.
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SIL 2/3 Functional Safety: The FTL51B is 3rd-party approved for the highest safety requirements. It features a “Second Line of Defense” (gas-tight feedthrough), ensuring that even if the primary sensor diaphragm is damaged, the process media cannot escape into the electronics housing or the environment.
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Guided Proof Testing: Mandatory periodic safety tests (SIL or WHG) are simplified via the SmartBlue App. Guided wizards walk the operator through the process, and the device generates automated documentation upon completion, significantly reducing manual paperwork and human error.
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Heartbeat Technology: This suite provides continuous internal self-diagnostics. It can detect sensor corrosion or heavy buildup in real-time, allowing for predictive maintenance. Verification can be performed at any time without interrupting the process or opening the vessel.
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Digital Communication and Asset Management: With integrated Bluetooth and optional digital protocols, the FTL51B provides real-time data access. Users can monitor device status and process parameters remotely, facilitating centralized asset management and faster troubleshooting.
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Extension Tube Versatility: Unlike compact versions, the FTL51B features an extension tube that can be customized to the exact length required for high-level or low-level switching in deep tanks.
Technical Specification Matrix
| Feature | Technical Details |
| Measuring Principle | Vibronic (Tuning Fork) |
| Device Design | Extension tube version |
| Process Temperature | -50 to +150°C (-58 to +302°F) |
| Process Pressure | -1 to +100 bar (-14.5 to +1450 psi) |
| Sensor Material | 316L Stainless Steel or Alloy (e.g., C22) |
| Output Signal | FEL61 (AC), FEL62 (DC-PNP), FEL64 (Relay), FEL67 (PFM), FEL68 (NAMUR), IO-Link |
| Safety & Compliance | SIL 2/3, WHG, ATEX, IECEx, Marine approvals |
Primary Applications
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Critical Overfill Prevention: Serving as the final safety barrier in chemical and oil & gas storage tanks to prevent environmental catastrophes.
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High-Pressure Process Vessels: Reliable switching in reactors and separators where pressures reach up to 100 bar.
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Corrosive Media Detection: Utilizing Alloy sensor materials to monitor aggressive acids or bases that would corrode standard stainless steel.
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Safety Loops (SIS): Integration into safety-instrumented systems where high-demand or low-demand reliability is required.
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Turbulent Liquid Monitoring: Level detection in mixing tanks with heavy agitation or gas bubbles where float switches or ultrasonic sensors might fail.
