Endress+Hauser Liquipoint T Series - User Manual

Technical Information
TI 375F/00/en
Level Limit Detection in Liquids
liquipoint T FTW 31, FTW 32
Level limit switch for multiple point detection
in conductive liquids
Applications
Liquipoint T sensors are used in
conductive liquids (as of 10 µS/cm) for
determining level limits.
Depending on the number of measuring
points (up to 5 rods or ropes), measuring
tasks such as overspill protection, dry
running protection, two-point control of
pumps or multiple point detection can be
implemented for an existing process
connection.
Your benefits
• Detect up to five level limits with one
probe
• Two-point control and additional
maximum and minimum detection
• Option between rod or rope version for
optimum adaptation to the application
• Flexible instrumentation:
– with built-in electronic insert, either
transistor or relay output for 2 or
3 rod/rope probes
– for connection to a separate
transmitter power supply unit
• No calibration required;
standard setting for the most common
conductive liquids
• No moving parts in the tank:
– long service life
– reliable operation with no wear or
blockages
• WHG approval
• Four measuring ranges can be set
100 Ω, 1 kΩ, 10 kΩ, 100 kΩ
• Cost-effective probe for conductive
liquids
• Electronic inserts for:
– NAMUR output
– Relais output
– Transistor output

Summary

Function and System Design

Measuring Principle

Explains the alternating voltage principle for level detection in conductive liquids.

Measuring System

Details the components of the measuring system: probes and control units.

Probes without Integrated Electronic Insert (One or Two-Point Detection)

Describes probes for one or two-point detection without integrated electronics.

Probes without Integrated Electronic Insert (Multiple Point Detection)

Details probes for multiple point detection without integrated electronics.

Input and Output Signals

Input Parameters

Specifies measured variable, range, and input signal characteristics.

Output Signal FEW 52 (DC-PNP)

Details the FEW 52 electronic insert with PNP output and fail-safe modes.

Output Signal FEW 54 (Relay)

Describes the FEW 54 electronic insert with relay output and its settings.

Fail-Safe Mode for Relay Output

Explains selecting fail-safe modes for relay outputs (MAX/MIN).

Measuring Ranges for Relay Output

Details the four settable measuring ranges for the relay output.

Output Signal FEW 58 (NAMUR)

Covers the FEW 58 electronic insert for NAMUR standard output.

Power Supply and Connections

Electrical Connection Diagrams (FEW 52)

Provides wiring diagrams for the FEW 52 electronic insert.

Compact Instrumentation with FEW 54

Details the FEW 54 relay output circuit and protection.

Compact Instrumentation with FEW 58

Explains the FEW 58 NAMUR electronic insert and its signal transmission.

Separate Instrumentation Configurations

Two-Rod;Rope Probes with Cable Monitoring

Wiring for two-rod/rope probes with cable monitoring.

Three-Rod;Rope Probes with Cable Monitoring

Wiring for three-rod/rope probes with cable monitoring.

Five-Rod;Rope Probes with Cable Monitoring

Wiring for five-rod/rope probes with cable monitoring.

Cable Entry and Specifications

Cable Entry Options

Details M 20x1.5 and NPT 1/2" cable entry types.

Cable Specifications

Recommends using commercially available cable with specific resistance.

Accuracy and Installation

Accuracy Specifications

Details measuring error, repeatability, hysteresis, and temperature influence.

Installation Conditions

Covers mounting location and piping usage for probes.

Orientation and Dimensions

Rod Probes (Dimensions)

Shows mounting orientations and dimensions for rod probes.

Rope Probes (Dimensions)

Illustrates mounting orientations and dimensions for rope probes.

Example Applications

Level Limit Detection

Depicts standard level limit detection scenarios.

Two-Point Control (Pump Control)

Shows two-point control setup using the device.

Environmental and Process Conditions

Ambient and Storage Temperature Range

Specifies ambient and storage temperature limits.

Climate Class and Degree of Protection

States climate class and IP66 degree of protection.

Vibration and EMC Requirements

Covers vibration resistance and electromagnetic compatibility.

Medium Temperature Limits

Shows temperature limits based on housing and medium temp.

Conductivity and Pressure Range

Specifies minimum conductivity and permissible medium pressure.

Mechanical Construction Details

Design and Dimensions (G 1 1;2 Connection)

Provides dimensions for rod/rope probes with G 1 1/2" connection.

Design and Dimensions (NPT 1 1;2 Connection)

Provides dimensions for rod/rope probes with NPT 1 1/2" connection.

Weight Specifications

Lists weights for different configurations of FTW 31 and FTW 32.

Material Specifications

Details materials used for probes, housing, and covers.

Rod Probe Details

Specifies dimensions and forces for rod probes.

Rope Probe Details

Details diameter, lengths, insulation, and forces for rope probes.

Human Interface

Operating Elements (DIL Switches)

Describes DIL switches for min/max, delay, and range settings.

Display Elements (LED Indicators)

Explains LEDs for fault and operation status on FEW inserts.

Certificates and Approvals

CE Marking and Overspill Protection

Confirms EC directive compliance, WHG, and leak test approvals.

Standards and Guidelines

Lists observed standards like low voltage, safety, and EMC.

Ex-Approvals and Type of Protection

Specifies ATEX Ex types and protection for FEW inserts.

Ordering Information

Liquipoint FTW 31 Model Configuration

Provides coding structure for ordering FTW 31 models.

Liquipoint FTW 32 Model Configuration

Provides coding structure for ordering FTW 32 models.

Accessories and Documentation

Available Accessories

Lists available accessories like lock nuts and electronic inserts (FEW 52, 54, 58).

Supplementary Documentation and Certificates

Lists operating instructions and relevant certificates (WHG, ATEX).

Overview

1. Function Description
2. Important Technical Specifications
3. Input
4. Output (Electronic Inserts)
5. Accuracy with built-in electronic insert
6. Environment
7. Process Conditions
8. Mechanical Construction
9. Usage Features
10. Maintenance Features

The Liquipoint T FTW 31 and FTW 32 are level limit switches designed for multiple point detection in conductive liquids, with conductivity starting from 10 µS/cm. These devices are suitable for various applications such as overspill protection, dry running protection, two-point control of pumps, and general multiple point detection within an existing process connection.

Function Description:

The measuring principle relies on an alternating voltage applied between the rod probes in an empty tank. When a conductive liquid connects the ground probe rod with a maximum probe rod, a measurable current flows, causing the Liquipoint T to switch. For level limit detection, the device switches back once the liquid clears the maximum probe. In two-point control, the Liquipoint T only switches back after both the MAX and MIN probes are cleared. The use of alternating voltage prevents corrosion of the probe rods and electrolytic destruction of the product. The system is designed as a closed, potential-free circuit between the probe rods and the electronics, making the tank wall material irrelevant for measurement. The probe rods are safe to touch during operation.

The measuring system can consist of FTW 31 or FTW 32 with two or three rods/ropes and an integrated electronic insert, or it can be a separate-instrument version without an integrated electronic insert, requiring connection to external control units like Nivotester FTW 325 or FTW 470 Z. The compact-instrument version with three probes or rods always operates in "As" mode. For multiple point detection, the separate-instrument version can accommodate up to five rods or ropes, requiring two Nivotester FTW 325 or FTW 470 Z units.

Important Technical Specifications:

Input:

• Measured variable: Resistance change between two conductors due to the presence or absence of a conductive product.
• Measuring range (application): Dependent on mounting location. Rod probes can be up to 4000 mm long, and rope probes up to 15000 mm.
• Input signal: A measurable current flows when probes are covered; no measurable current flows when probes are uncovered.

Output (Electronic Inserts):

• FEW 52 (DC-PNP):

  • Output signal: Three-wire direct current version, preferred for programmable logic controllers (PLC). Positive signal at the switch output (PNP). Output blocked after level limit is reached.
  • Fail-safe mode: Output voltage is 0 V if switch point is exceeded (max. fail-safe) or undershot (min. fail-safe), a fault occurs, or power supply fails.
  • Switching delay: 2.0 s (activatable/deactivatable via DIL switch) or approx. 0.3 s (when set to 0 s).
  • Power supply: U= 10.8 V...45 V. Load connection: open collector; PNP. Switching voltage: max. 45 V. Connected load: continuous max. 200 mA. Protected against reverse polarity.
  • Power consumption: P < 1.1 W. Current consumption: I < 25 mA (without load).

• FEW 54 (Relay):

  • Output signal: AC/DC connection with relay output. Two potential-free change-over contacts switch simultaneously. Spark barrier recommended for high inductance loads. Fine-wire fuse protects against short-circuits.
  • Fail-safe mode: Relay de-energizes if switch point is exceeded (max. fail-safe) or undershot (min. fail-safe), a fault occurs, or power supply fails.
  • Switching delay: 2.0 s (activatable/deactivatable via DIL switch) or approx. 0.3 s (when set to 0 s).
  • Signal on alarm: Relay de-energized in case of power failure or damaged probe.
  • Load: I~ max. 4 A, U~ max. 253 V; P~ max. 1000 VA (cos φ = 1), P~ max. 700 VA (cos φ > 0.7); I- max. 4 A to 30 V, I- max. 0.2 A to 150 V. Max sum of relay output and power supply voltages: 300 V (for functional extra-low voltage circuit).
  • Galvanic isolation: All input/output channels and relay contacts are galvanically isolated.
  • Power supply: U= 20 V...55 V DC or U~ 20 V...253 V AC, 50/60 Hz. Peak inrush current: max. 2 A, 400 µs.
  • Power consumption: P < 2.0 W. Current consumption: 60 mA.

• FEW 58 (NAMUR):

  • Output signal: For connecting to isolating amplifiers (IEC 60947-5-6). Output signal jumps from high to low current on limit (H-L-edge). Signal transmission on a two-wire line: H-L-edge 2.2...6.5 mA / 0.4...1.0 mA. Cycle time must be at least 2 s when using a multiplex.
  • Fail-safe mode: Output signal is < 1.0 mA if switch point is exceeded (max. fail-safe) or undershot (min. fail-safe), a fault occurs, or power supply fails.
  • Switching delay: 2.0 s (activatable/deactivatable via DIL switch) or approx. 0.3 s (when set to 0 s).
  • Signal on alarm: Output signal < 1.0 mA with damaged sensor.
  • Power supply: Refer to "Technical Data" datasheet of the connected isolating amplifier.

Accuracy with built-in electronic insert:

• Reference operating conditions: Ambient/medium temperature 23 °C, medium must release probe, pressure 0 bar, vertical installation from above.
• Measuring error: +/- 10% at 100 Ω - 100 KΩ; +/- 5% at 1 KΩ - 10 KΩ.
• Repeatability: +/- 5% at 100 Ω - 100 KΩ; +/- 1% at 1 KΩ - 10 KΩ.
• Hysteresis: 10% for MAX probe, relative to switch point.
• Switch-on delay: < 3 s.
• Influence of ambient temperature: < 0.05 %/K.

Environment:

• Ambient temperature range: -40...70 °C (-40...60 °C for FEW 58 NAMUR).
• Storage temperature: -40...80 °C.
• Climate class: Tropicalised as per DIN EEC 68, part 2-38.
• Degree of protection: IP66.
• Shock resistance: Practical test.
• Vibration resistance: DIN 60068-2-64 / IEC 68-2-64: 20...2000 Hz, 1 (m/s²)²/Hz.
• Electromagnetic compatibility: Interference Emission to EN 61326, Electrical Equipment Class B; Interference Immunity to EN 61326, Annex A (Industrial). Screened cable recommended for separate-instrumented probes.

Process Conditions:

• Medium temperature limits: Permissible ambient temperature T₁ at housing as a function of measuring material temperature T₂ in vessel. No restrictions for separately instrumented devices (without FEW 5?).
• Conductivity: ≥ 10 µS.
• Limiting medium pressure range: -1...10 bar.

Mechanical Construction:

• Housing: F24 (separate-instrument version) - PPS housing, PBT cover. F16 (compact-instrument version) - PBT housing, PBT cover, PBT adapter.
• Process connections: G 1 1/2", NPT 1 1/2".
• Rod probes: Rod: 1.4404 (316L), PP insulation. Diameter without insulation: 4 mm. Max rod length: 4000 mm. Min rod length: 100 mm. Insulation thickness: 0.5 mm. Non-insulated area at tip: 20 mm. Extraction forces: 1000 N.
• Rope probes: Rope: 1.4571 (316Ti), FEP insulation. Weight: 1.4435. Diameter without insulation: 1 mm. Max rope length: 15000 mm. Min rope length: 250 mm. Insulation thickness: 0.75 mm. Weight length: 100 mm (not insulated). Weight diameter: 10 mm. Extraction forces: 500 N.
• Cable entry: M 20x1.5 or NPT 1/2". Degree of protection: IP66. Quantity in F24 housing: 1 (separate-instrument), 1 (compact-instrument). Quantity in F16 housing: 2 (compact-instrument). Conductor cross-section: 2.5 mm.

Usage Features:

• Flexibility: Detects up to five level limits with one probe. Supports two-point control and additional max/min detection. Available in rod or rope versions for optimal adaptation.
• Instrumentation: Options for built-in electronic inserts (transistor or relay output for 2/3 probes) or connection to separate transmitter power supply units.
• Ease of use: No calibration required, with standard settings for common conductive liquids.
• Reliability: No moving parts in the tank ensures long service life, reliable operation, and prevents wear or blockages.
• Measuring ranges: Four selectable ranges (100 Ω, 1 KΩ, 10 KΩ, 100 KΩ) via DIL switches.
• Cable monitoring: For probes without an electronic insert, an additional PCB can be installed to enable cable monitoring (switched/connected between rod/rope 1 and 2).

Maintenance Features:

• Self-monitoring: The red LED flashing continuously indicates that a more sensitive measuring range needs to be set to ensure a safe switch point, even with slight variations in medium conductivity.
• Approvals: WHG approval and leakage test ensure compliance and safety. Meets CE mark, Low Voltage Equipment Directive (73/23/EEC), DIN EN 61010 part 1, and EN 61326 EMC requirements. Available in Ex versions (ATEX EEx ia and ATEX EEx nA/C(L)).

Endress+Hauser Liquipoint T Series Specifications

General

Brand	Endress+Hauser
Model	Liquipoint T Series
Category	Accessories
Language	English