Liquicap M FMI51

Summary

Product Identification

• Product Name: Liquicap M FMI51
• Type: Capacitive Level Sensor
• Part Number: TI01490F/00/EN/03.21, 71510170
• Manufacturer: Endress+Hauser

Application

The Liquicap M FMI51 is designed for continuous level measurement of liquids. It is independent of the dielectric constant (DC) for liquids with a conductivity of 100 µS/cm and higher, eliminating the need for recalibration in such applications.

• Process Connections: Flanges and threads available.
• Process Pressure: Capable of handling vacuum up to +100 bar (+1,450 psi).
• Measuring Range: 0.1 to 4.0 m (0.3 to 13 ft).
• Temperature Range: -80 to +200 °C (-112 to +392 °F).
• Certificates and Approvals: Includes international explosion protection, WHG (overfill prevention), SIL, hygienic certificates, and marine approvals.

Operating Principle

The device operates on the principle of capacitance measurement. The probe and the container wall (or a ground tube) form a capacitor. Changes in the liquid level alter the capacitance, which is then converted into a proportional signal. For liquids with conductivity of 100 µS/cm or higher, the measurement is independent of the dielectric constant. The system can also compensate for buildup on the probe rod.

Measuring System

The complete measuring system consists of:

• Liquicap M FMI52 level probe
• FEI50H electronic insert (4 to 20 mA output with HART protocol) or FEI57C electronic insert (PFM output)
• Transmitter power supply unit

Output Signal

• FEI50H: 4 to 20 mA with HART protocol (version 5), signal range 3.8 to 20.5 mA.
• FEI57C: PFM signal (current pulses, 60 to 2,800 Hz) superimposed on the supply current.

Signal on Alarm

• FEI50H: Indicated by a red LED, error symbol, plain text on display, 22 mA current output, or HART status error message.
• FEI57C: Indicated by a red LED on the local display or at switching units.

Linearization

• FEI50H: Enables conversion to desired length or volume units. Pre-programmed linearization tables for cylindrical and spherical tanks are available. Custom tables with up to 32 value pairs can be input.
• FEI57C: Linearization is performed in the transmitters.

Power Supply

• FEI50H:
  • Non-hazardous area: 12.0 to 36.0 VDC
  • Hazardous area (Ex ia): 12.0 to 30.0 VDC
  • Hazardous area (Ex d): 14.4 to 30.0 VDC
• FEI57C: 14.8 VDC from the associated supply unit.
• Both electronic inserts feature integrated reverse polarity protection.

Power Consumption

• FEI50H: Minimum 40 mW, Maximum 800 mW.
• FEI57C: Maximum 250 mW.

Current Consumption

• FEI50H: 3.8 to 22 mA (4 mA for HART multidrop).
• FEI57C: 0 mA, 8 mA, 16 mA (with frequency 60 to 2,800 Hz).

Performance Characteristics

• Reference Operating Conditions: Room temperature +20 °C (±5 °C), Span ∆C = 25 to 4,000 pF.
• Maximum Measured Error: Non-repeatability ±0.1 %, Non-linearity ±0.5 %.
• Influence of Ambient Temperature: < 0.06 %/10 K for electronic insert.
• Influence of Process Pressure: < 10.0 % related to full scale value for fully insulated probes in conductive liquids.

Switch-on Behavior

• FEI50H: 14 s, stable measured value after switch-on, starts in safe status (22 mA).
• FEI57C: 1.5 s, stable measured value after switch-on, starts in safe status (22 mA).

Measured Value Reaction Time

• FEI50H: Dead time t1 ≤ 0.3 s (Operating mode) or t1 ≤ 0.5 s (SIL operating mode).
• FEI57C: Dead time t1 = 0.3 s.

Response Time

• FEI50H: Factory setting for time constant τ = 1 s; adjustable from 0 to 60 s.

Accuracy of Factory Calibration

• Probe length < 2 m: ≤ 5 mm.
• Probe length > 2 m: Approximately ≤ 2 %.
• Reference Conditions: Medium conductivity ≥ 100 µS/cm, minimum distance to tank wall = 250 mm.

Resolution

• FEI50H: 11 bit / 2,048 steps (8 µA analog resolution).
• FEI57C: Sensitivity of electronic insert = 0.685 Hz/pF.

Installation

Rod Probes

• Can be installed vertically in conductive (metal) or nonconductive (plastic) tanks.
• Avoid contact with the container wall and the filling curtain.
• Maintain a safe distance from agitators.
• Minimum distance of 500 mm between adjacent probes.
• Ensure good electrical connection between the process connection and the tank.
• Fully insulated rod probes cannot be shortened or extended.

Probe with Separate Housing

• Maximum combined cable and rod length is 10 m (33 ft).
• Maximum cable length between probe and separate housing is 6 m (20 ft).

Environment

• Ambient Temperature Range:
  • F16 housing: –40 to +70 °C (–40 to +158 °F).
  • Other housings: –50 to +70 °C (–58 to +158 °F).
• Storage and Transport Temperature: –50 to +85 °C (–58 to +185 °F).
• Vibration Resistance: DIN EN 60068-2-64/IEC 68-2-64: 20 to 2,000 Hz, 0.01 g²/Hz.
• Shock Resistance: DIN EN 60068-2-27/IEC 68-2-27: 30 g acceleration.
• Degree of Protection: IP66, IP67, IP68 (with specific configurations), NEMA 4X.

Electromagnetic Compatibility (EMC)

• Interference emission to EN 61326, Electrical Equipment Class B.
• Interference immunity to EN 61326, Annex A (Industrial) and NAMUR Recommendation NE 21 (EMC).

Process

• Process Temperature Range:
  • Probe with compact housing: -80 to +200 °C (-112 to +392 °F).
  • Probe with separate housing: -80 to +200 °C (-112 to +392 °F).
• Process Pressure Limits: Depend on the process connection. For example:
  • Probe ⌀10 mm: -1 to 25 bar.
  • Probe ⌀16 mm: -1 to 100 bar (or 63 bar with inactive length).
  • Probe ⌀22 mm: -1 to 50 bar.

Mechanical Construction

Weight

• Housing (F15, F16, F17, F13): Approximately 4.00 kg (8.82 lb).
• Housing (T13): Approximately 4.50 kg (9.92 lb).
• Housing (F27): Approximately 5.50 kg (10.1 lb).
• Flange Weight: Varies by probe rod diameter.

Materials

• In contact with the process: 316L (1.4435), PFA, PTFE.
• Not in contact with the process: 304 (1.4301), Polyamide (PA), Brass, Polyester, Silicone, EPDM, FVMQ.

Operability

• Operating Concept: Can be operated locally via electronic insert keys, optional display module, or remotely via HART protocol with Commubox FXA195 and FieldCare software, or a HART handheld terminal.

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Disclaimer: This extracted summary may not include all figures, footnotes, or revisions. Contractual data must be confirmed against the specific OEM PDF revision used for the project.

Official datasheet (PDF)

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