fafnir CONDURIX Series Guide

FAFNIR GmbH • Schnackenburgallee 149 c • 22525 Hamburg, Germany • Tel.: +49 / 40 / 39 82 07–0 • Fax: +49 / 40 / 390 63 39
Technical Documentation
CONDURIX
The potentiometric level sensor
Edition: 2016-08
Version:
9
Art. no.:
207134

I Table of Contents

Table of Contents II
Table of contents
1Range of application.............................................................................. 1
2Safety instructions ................................................................................. 2
3Design and function............................................................................... 3
4Installation.............................................................................................. 5
4.1 CONDURIX Mono (single rod).............................................................................6
4.2 CONDURIX DU (two rods)...................................................................................6
4.3 CONDURIX MA (jacketed pipe)...........................................................................6
5Electrical connection .............................................................................. 7
6Parametrisation ...................................................................................... 9
6.1 Measuring span at the level sensor .....................................................................9
6.2 Current consumption in failure mode ...............................................................10
7Maintenance......................................................................................... 11
7.1 Overhaul ..........................................................................................................11
7.2 Return shipment...............................................................................................11
8Technical Data ...................................................................................... 12
9List of figures........................................................................................ 13
10 Annex.................................................................................................... 14
10.1 EC Declaration of Conformity ...........................................................................14
10.2 EC-Type Examination Certificate .......................................................................15
10.3 Safety instructions ............................................................................................18
© Copyright:
Reproduction and
translation are permitted only with the written consent of the FAFNIR GmbH. FAFNIR GmbH reserves
the right to make changes to products without prior notice.

Page 1/20 Range of application
1Range of application
The purpose of the CONDURIX level sensor is to provide continuous level gauging of elec-
trically conductive liquids (> 1 μS/cm). During the measurement no insulating layer must
be formed on the probe tube.
The level sensor is available in lengths of 200 to 6,000 mm.
With the “single-rod probe” model (CONDURIX Mono), the inside of the container must
have a conductive surface (metal containers / downpipes). The “two-rod probe” model
(CONDURIX DU) or “jacketed probe” model (CONDURIX MA) are both compatible with
non-conductive containers.
The standard sensors work by outputting the measured fill level as an analogue value in
the range 4 to 20 mA.
With the HART option, the configuration and retrieval of measured values by the digital
HART protocol are supported, see
•Technical Documentation CONDURIX with HART protocol, art. no. 350044
In conjunction with the standard level sensors, wetted parts are in stainless steel 1.4571
(316Ti), insulators are in PEEK (alternatively in PTFE). On request, the probe tubes are also
available in Hastelloy, tantalum, titanium or stainless steel 1.4404 (316L).

Safety instructions Page 2/20
2Safety instructions
The purpose of the CONDURIX level sensor is to provide continuous level gauging of liq-
uids. The level sensor must be used exclusively for this purpose. The manufacturer accepts
no liability for any form of damage resulting from improper use.
The level sensor has been developed, manufactured and tested in accordance with the
latest good engineering practices and generally accepted safety standards. Nevertheless,
hazards may arise from its use. For this reason, the following safety instructions must be
observed:
Do not change or modify the level sensor or add any equipment without the prior con-
sent of the manufacturer. The installation, operation and maintenance of the level sensor
must be carried out only by expert personnel. Operators, installers and service technicians
must observe all applicable safety regulations. This also applies to any local safety and
accident prevention regulations which are not stated in this manual.
The safety instructions in this manual are marked as follows:
If these safety instructions are not observed, it may result in the risk of acci-
dent or damages to the CONDURIX level sensor.
Useful information designed to ensure continued and correct operation of
the CONDURIX level sensor or helpful advice to make your work easier.

Page 3/20 Design and function
3Design and function
The design of the CONDURIX level sensor is illustrated in Figure 1 with the screw-in unit
version as an example. Inside the sensor head (1) of the level sensor and concealed by a
cap (2) are the protected terminals and configuration buttons. The electrical connection is
established by means of an M16x1.5 screwed cable gland (3) and screw terminals or by
an M12 plug-in connection. The potential equalization terminal (4) is required only in
conjunction with the CONDURIX Mono version (see section 5 Electrical connection). On
the probe neck, there is either a screw-in unit (5) or a flange (not shown) for installing the
probe in the container.
Figure 1: The CONDURIX level sensor
A current pulse generates a linear voltage drop (< 100 mV) on the probe tube (6) electri-
cally insulated from tank potential. The voltages at the bottom end and top end of the
tube are measured.
As long as the probe tube is not immersed, it has no path to tank potential. This state is
detected by the signal processor, which outputs an “empty” signal. As soon as the probe
tube is immersed, the voltage measured at the immersed tube end corresponds to tank
potential and the voltage measured at the top end is added to the voltage drop along the
non-immersed part of the probe tube.
With the probe tube fully immersed, the voltages measured at the top and bottom ends
of the tube are equal in respect of the potential reference point. The region in between is
mostly linear, depending on the tank geometry and the distance between the tube end
and tank bottom, which makes it possible to calculate the fill level from the ratio of the
measured voltages.

Design and function Page 4/20
The fill level is calculated from the ratio of the measured voltages by a microcontroller.
The ratio of the two voltages also enables the orientation of the CONDURIX sensor to be
detected, i.e. whether the sensor has been installed from top down or bottom up.
The level sensor is fed from a 2-wire 4 … 20 mA interface and requires a voltage of
between 8 and 30 V. The position of 4 mA and 20 mA points on the probe tube is freely
adjustable (see chapter 6, Parametrisation). To prevent galvanic processes from occurring
in the liquid, both the discharging and charging currents flow through a galvanically
isolating transformer. The alternating voltage produced across the very low-resistance
probe tube is in the 100 mV range.
The table below shows the signal characteristics of the sensor as a function of sensor ori-
entation and the measured value output setting (normal/inverted).
Measured value output
normal
Measured value output
inverted
Filling level
“Empty” sig-
nal
Filling level
“Empty” sig-
nal
Installation
top down
3.8 mA 20.5 mA
Installation
bottom up
3.8 mA 20.5 mA
Figure 2: Measured value output
Installation top down: The zero point is at the probe base
Installation bottom up: The zero point is at the sensor head
Normal measured value output: The 20 mA point is higher than the 4 mA point
Inverted measured value output: The 20 mA point is lower than the 4 mA point
20 mA
4 mA
4 mA
20 mA
20 mA
4 mA
4 mA
20 mA

Page 5/20 Installation
4Installation
All local safety and accident prevention regulations not expressly referred to
herein must be observed.
Figure 3: CONDURIX variants
Level gauging with CONDURIX is possible only in electrically conductive
liquids.
The level sensor can also be fitted into the tank from underneath. The
sensor must be configured accordingly.
CONDURIX Mono: If the probe tube is immersed in the liquid only a short
way, the linearity of the measurement is affected by the short distance
between the probe tube and reference potential.
AMXIRUDNOC CONDURIX DU
50
~160
29
50
112
8
onoMXIRUDNOC 50
ca. 161
5
Cap, SW 19
removable
Cable
gland
M16x1.5
Sensor head
Connector for
equipotential bonding
Jacketed pipe
Probe tube
Cap, SW 19
removable
Cable
gland
M16x1.5
Sensor head
Connector for
equipotential bonding
Screw-in
unit R ¾ min.
or flange
Flange or
screw-in unit R 2
Probe tube
∅6
Counter electrode
∅24
Measuring range Adjustment range
Measuring range
Measuring range
Installation length
Installation length

Installation Page 6/20
4.1 CONDURIX Mono (single rod)
With the single-rod probe, the tank acts as the counter electrode. For this reason, the
material on the inside of the tank must be conductive and there must be good electrical
contact between the tank and the sensor head. For this purpose, the potential equaliza-
tion terminal must be connected to the tank.
4.2 CONDURIX DU (two rods)
With the two-rod probe, the second rod acts as the counter electrode. As the distance
from reference potential is constant, the measurement result is unaffected by the geome-
try of the tank. While the second rod also adds to the stability of the mechanical design,
this does require a larger process connection for installation.
4.3 CONDURIX MA (jacketed pipe)
With the jacketed probe version, a pipe (coaxial in construction) surrounding the probe
tube acts as the counter electrode. As the distance from reference potential is constant,
the measurement result is unaffected by the geometry of the tank.
The jacketed pipe also provides a shield against electrical interference and facilitates
measurements in otherwise unfavourable measuring conditions.

Page 7/20 Electrical connection
5Electrical connection
For the wiring of the level sensor, you need a two-core unshielded cable, which is termi-
nated inside the sensor head of the level sensor.
It is essential that the correct cross section be selected: the supply voltage at the level sen-
sor must not fall below 8 V in the event of maximum current consumption (21.5 mA).
To connect the level sensor (see Figure 4):
(1) Unscrew cap (1) using an open-ended spanner (SW 19)
(2) Loosen union nut (2) of screwed cable gland (3)
Figure 4: Connecting the CONDURIX level sensor
(3) Feed two-core cable (4) through union nut (2) and fit screwed cable gland (3)
and then retighten the union nut.
(4) Connect the two-core cable (4) to the screw terminals on the sensor head
marked (+) and (–).
Pinout of the M12 plug-in connection:
Pin 1 = brown (+) Pin 3 = blue (-)
(5) Screw on cap (1)
5