Liquiphant FTL31-AA4M2ABWBJ Vibronic Level Detection Pressure Transmitter 4-20mA Output SIL Certified

What is the Liquiphant FTL31

• The Liquiphant FTL31 is a point level switch designed for detecting liquid level (or the presence/absence of liquid) at a specific point (as opposed to continuous level measurement).
• It uses the vibronic / tuning fork principle: a fork vibrates at a given resonance frequency; when the fork is immersed in a liquid, that resonance frequency shifts, which is detected by the electronics.

Key Technical Specifications

Here are some of its main specs & capabilities:

Applications / Use Cases

• Overfill protection: to detect when liquid reaches a certain high level to prevent spillovers.
• Dry-run protection: detecting when a pump’s liquid level drops too low.
• Lower level detection: as a safety / control switch in tanks, vessels, pipes.
• Industrial machinery, cleaning systems, anywhere a simple reliable point-level detection is needed.

Key Advantages

• Reliability & Safety: It has built-in continuous self-monitoring, meaning if power is lost or there's a fault, the sensor gives a safe (fail) signal.
• Insensitive to many disturbances: Turbulence, flows, air bubbles, conductivity, foam-build-up or changing media properties have little to no effect. The resonance-based tuning fork is fairly robust in these conditions.
• No calibration needed: Reduces setup time and maintenance.
• Compact and rugged design: Stainless steel housing; various mounting and connection options; high pressure/temperature capability.
• Multiple output / electrical versions: Good flexibility to match with different control systems (DC, AC, PNP, etc.).

Things to Consider / Limitations

• Minimum density requirement: Standard versions require medium density >0.7 g/cm³. If your liquid is lighter, you’ll need the optional version (>0.5 g/cm³).
• Not suitable for all hazardous-area use: The FTL31 is not suited for some hazardous area classifications; for hygienic or especially demanding environments, other models (e.g. FTL33) might be more appropriate.
• Switching point location depends on installation: Orientation, mounting, distance from walls, etc., can affect the exact switch point. Proper installation is important (vertical, horizontal, ensuring fork drains off etc.).
• Response time / hysteresis: There is some delay when the fork is covered vs uncovered, and hysteresis (difference between on/off switching) to be considered in tight control loops.