Float Level Sensor (HART) — S-MELS-FT

S-MELS-FT is a threaded, non-contact* float level sensor for continuous level measurement. It mounts directly into the process via a standard process connection. A float with an integrated ring magnet travels along the guide tube and actuates a measuring chain inside the stem. The resulting resistance signal—proportional to the float height—is processed by the electronics and converted to a 4–20 mA output with HART.

*no moving parts penetrate the tank interior beyond the guide tube.

Key features & specifications

• Measuring principle: float (ring magnet with internal measuring chain)
• Electronics: completely potted for robustness
• Wetted material: stainless steel 1.4571 (AISI 316Ti)
• Process connections: 1", 1.5", 1" NPT
• Output: 4–20 mA (HART)
• Configuration: via software (HART)
• Electrical entry: lateral or top entry
• Connectors available: M12, Superseal, Deutsch, bayonet, valve, or cable pigtail
• Protection rating: at least IP65

How it works

1. The float follows the liquid surface along the guide tube.

2. Its ring magnet switches the internal measuring chain, generating a resistance value proportional to level.

3. The onboard electronics linearize and convert this to a 4–20 mA/HART signal for the control system.

Area of application

Designed for industrial plants, terotechnology (maintenance engineering) and public utilities—e.g., hydraulic-oil tanks. Thanks to the HART interface for simple configuration and the wide choice of electrical connections, S-MELS-FT is well suited for applications with higher requirements.