Conductivity level switch for multiple point detection

Liquipoint T FTW31

11-35 Pcs.




  • Detect up to five level limits with one probe

  • Flexible instrumentation (compact/separate)

  • No moving parts

  • No calibration required

Product: liquids as of 5 µS/cm



Measuring points:

up to 4 measuring points

with 5 rods

Product temperature:

-40 to +100 °C

Process pressure:

-1 to +10 bar

Product/VersionPrice/pcs. in NZ$Order code
Liquipoint T FTW31
ApprovalElectronics; OutputSensing Point1 to 34 to 1011 to 35
Non-hazardous areaProbe only Separate instrumentation3 x 2000mm rods, 316L270.-251.-238.-FTW31-A1A3DA0A
5 x 2000mm rods, 316L310.-288.-273.-FTW31-A1A5DA0A
Compact Instrument Version (FEW54)2 x 2000mm rods, 316L380.-353.-334.-FTW31-A1A2DA4A
3 x 2000mm rods, 316L420.-391.-370.-FTW31-A1A3DA4A
The above models are ex stock. Please ask for pricing and delivery time of other FTW31 versions.

Prices are net, ex store Auckland, GST additional and valid until 30/9/2016.
EMC's standard Terms and Conditions of Supply are applicable.


Liquipoint T sensors are used in conductive liquids for determining point levels. Depending on the number of measuring points, measuring tasks such as overspill protection, dry running protection, two-point control of pumps or multiple point detection can be implemented within an existing process connection.


An alternating voltage exists between the rod probes in an empty tank. As soon as the conductive liquid in the tank creates a connection between the ground rod probe and the maximum rod probe, for example, a measurable current flows and the Liquipoint T switches.

By using alternating voltage, corrosion of the probe ends and electrolytic destruction of the product is avoided. As the system is designed as a closed potential-free circuit between the probe rods and the electronics, the materials used in the tank walls is unimportant and there is no danger if the probe rods are touched during operation. 

Application Examples


Probes with integrated electronic insert
(compact instrument version)

The measuring system consists of:

  • FTW31 with two/three rods or ropes and an electronic insert
  • Control units, switches or signal transmitters. e.g. process control systems PLC, relays or NAMUR isolating amplifier according to IEC 60947-5-6


Probes without integrated electronic insert

(separate instrument version)

The measuring system consists of:

  • FTW31 with two to five rods or ropes
  • Nivotester FTW325
  • Control units, switches or signal transmitters, e.g. process control systems PLC, relays, etc.


The number of Nivotester depends on the number of measuring points (e.g. 4 measuring points with 2 Nivotester FTW).

Technical data

  • Version

Compact version:

two/three (Always ∆S-mode - only three rod versions) rods;

Separate version
(With integrated line monitoring - in combination with level limit switch FTW325):

two/three/five rods

  • Sensor length
Rod: 2000mm (other lengths on request)
  • Minimum conductivity
Compact version ≥ 10 µS/cm
Separate version (FTW325) ≥ 5 µS/cm
  • Cable specification

Use standard cable (25 Ω per core)

Operating conditions
  • Medium temp.
-40 to +100 °C
  • Ambient temp.
-40 to +70 °C
  • Pressure
-1 to +10 bar
  • Ingress Protection
IP 66
  • Process connection

G 1˝"

  • Electrodes

Rods: 1.4404 (316L)/insulation: PP;

weight: 1.4435 (316L)

  • Process connection
  • Housing F16
For compact instrument version;
housing: PBT;
hat: PPS;
adapter: PBT
  • Housing F24

For separate instrument version;

housing: PPS;

hat: PBT

Approvals (Compact instrument version)
  • Ex approval
ATEX II 2G EEx ia IIC T6 with FEW58
  • WHG approval

WHG Z-65.40-360 (DIBt)

Approvals (Separate instrument version)
  • Ex approval

Dimensions (in mm)

Rod-version with G 1˝"

Compact-instrument version with electronic insert (left)

Separate-instrument version without electronic insert (right)

L = Probe length
a) AF 55

Installation according to instruction manual

Electrical connection

Probes with electronic insert (compact instrument version)

Electronic insert FEW54
  • Supply voltage
20 to 55 V DC or 20 to 253 V AC, 50/60 Hz
  • Current consumption
60 mA
  • Peak inrush current
Max. 2 A, max. 400 μs
  • Pulse frequency
Approx. 1.5 s
  • Output
Two potential-free changeover contacts
  • Contact load capacity
U~ max. 253 V, I~ max. 4 A,
U = 30 V/4 A; 150 V/ 0.2 A
  • Power consumption
< 2.0 W

Connecting the FEW54 electronic insert

F1: Fine-wire fuse, 200 mA, semi-time lag

F2: Fine-wire fuse to protect the relay contact, load-dependent

M: Ground connection to protective earth (PE)

a) Mains

b) + c) Potential-free changeover contacts

d) Vessel

Probes without integrated electronic insert (separate-instrument version)


For evaluation one or more FTW325 processor units are needed.

Separate instrumentation for three-rod- or rope-probes with cable monitoring.

*1 = Printed circuit board for cable monitoring