Capacitance Level Measurement

Capacitance Level Measurement

Endress+Hauser’s capacitance level portfolio combines continuous transmitters and point‑level switches for liquids and bulk solids. A probe and the vessel wall (or a reference electrode) form a capacitor; as product covers the probe, capacitance changes, and the electronics convert this to level. Devices are available as rod or rope probes, with hygienic and heavy‑duty variants, and are organized across the FLEX tiers from Fundamental to Xpert to match cost, capability, and risk. The result is a mature, broadly applicable technology for simple tanks through demanding silos.

For continuous level, Liquicap FMI51 (rod) and FMI52 (rope) are fully insulated capacitance transmitters for liquids, including those that form build‑up or run at elevated temperature. They offer repeatability to 0.1%, operate from −80 to +200 °C and vacuum to +100 bar, and, crucially, become independent of dielectric constant once conductivity is ≥ 100 µS/cm, minimizing recalibration across product changes. Typical measuring spans are 0.1–4.0 m (FMI51) and ~0.42–10 m (FMI52). Approvals include SIL and WHG; remote inventory monitoring is possible via Fieldgate.

Where limit detection in liquids is the objective, Liquicap FTI51/FTI52 provides robust point-level measurement on highly viscous, sticky, or foaming media and can also detect interfaces. Active build‑up compensation and corrosion‑resistant wetted materials support stable switching under difficult conditions. Process limits extend to roughly −80…+200 °C and up to ~100 bar, with broad hazardous‑area and functional‑safety approvals enabling use in overfill protection and pump control (two‑point) schemes.

For bulk solids, Solicap FTI55 (rod) and FTI56 (rope) are heavy‑duty limit switches for fine to coarse material. They tolerate high mechanical loads (lateral up to ~300 Nm on rods; tensile up to ~60 kN on ropes), offer easy shortening on site, and include measures against electrostatic discharge in silos. Typical probe lengths span ~200–4,000 mm (FTI55) and ~500–22,000 mm (FTI56). Where compact, hygienic powder detection is needed, e.g., in food, Nivector FTI26 adds IO‑Link and high sensitivity for powders with very low DK, while maintaining excellent anti‑build‑up behavior.

Value‑oriented options cover both solids and hygienic liquids. Minicap FTC260/FTC262 deliver cost‑effective, no‑calibration limit detection for light bulk solids (grains, powders, cement) and include active build‑up compensation plus on‑site rope shortening to simplify spares. In hygienic water‑based liquids, Liquipoint FTW23 is a compact, CIP/SIP‑capable point switch with IO‑Link; it ships for media with DK > 20 and can be adjusted (via IO‑Link) down to ~DK > 1.5, making it a practical choice for storage tanks, mixing vessels, and lines. Across the range, analog 4–20 mA/HART and IO‑Link are available depending on the model.

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