ZIROX SGM5-EL User manual

Electrolysis Device SGM5-EL
FOR THE MODULATION OF DEFINED OXYGEN CONCENTRATIONS IN INERT GASES
OPERATION MANUAL
ZIROX Sensoren & Elektronik GmbH
Am Koppelberg 21, D-17489 Greifswald [phone], Fax: -29 e-mail: inf[email protected]

Electrolysis Device SGM5EL Content
2
Table of contents
1 General information ...................................................................................................... 4
1.1 Introduction.......................................................................................................... 4
1.2 Copyright ............................................................................................................. 4
1.3 Commonly used symbols..................................................................................... 4
2 Application fields........................................................................................................... 6
3 Safety regulations ......................................................................................................... 7
4 Functional description .................................................................................................. 8
4.1 Measuring principle.............................................................................................. 8
4.2 Measuring conditions........................................................................................... 9
4.2.1 General recommendations ....................................................................... 9
4.2.2 Gas flow quantity.................................................................................... 10
4.2.3 Accuracy of the measurement................................................................ 10
5 Technical data ............................................................................................................. 11
5.1 Characteristics................................................................................................... 11
5.2 Mechanical data / ambient conditions ................................................................ 11
5.3 Electrical data.................................................................................................... 11
5.4 Interface data..................................................................................................... 12
6 Composition of the SGM5-EL ..................................................................................... 15
6.1 General composition.......................................................................................... 15
6.2 Construction of the control unit .......................................................................... 17
6.2.1 Power supply.......................................................................................... 17
6.2.2 Front ...................................................................................................... 17
6.2.3 Rear ....................................................................................................... 18
6.2.4 Combi cell .............................................................................................. 18
7 Installation and initiation ............................................................................................ 19
7.1 Installation conditions ........................................................................................ 19
7.2 Set-up of operating state ................................................................................... 19
8 Operation and parametrization................................................................................... 21
8.1 Operation........................................................................................................... 21
8.1.1 Switch-on and measurement indication.................................................. 21
8.1.2 Gas flow adjustment............................................................................... 21
8.1.3 Data monitoring...................................................................................... 21
8.1.4 Status and error messages .................................................................... 22
8.2 Adjustable parameters....................................................................................... 22
8.3 Calibration ......................................................................................................... 25
8.3.1 Zero calibration ...................................................................................... 25
8.3.2 Span gas calibration............................................................................... 25
8.4 Fault clearance.................................................................................................. 26
8.5 Operation via PC ............................................................................................... 27

Electrolysis Device SGM5EL Content
3
9 Maintenance, overhaul and storage........................................................................... 28
9.1 General notes.................................................................................................... 28
9.2 Replace the equipment fuse .............................................................................. 28
10 Appendix...................................................................................................................... 29
10.1 Mounting instructions for Swagelok®-fittings .................................................. 29
10.2 Declaration of conformity ................................................................................ 30
10.3 Warranty conditions........................................................................................ 31

Electrolysis Device SGM5EL General
4
danger
1 General information
1.1 Introduction
This operation manual describes design, function and operation of the
Electrolysis Device SGM5-EL of the ZIROX GmbH.
Address of manufacturer:
ZIROX Sensoren & Elektronik GmbH
Am Koppelberg 21
17489 Greifswald
Germany
Tel.: [phone]
Fax: [phone]
E-mail: [e-mail]
The manufacturer guarantees that this manual was written in accordance with
the functional and technical features of the delivered SGM5-EL.
This manual is not subject to the amendment service. If the manufacturer
modifies the SGM5-EL with the aim of making technical improvements, the
user is responsible for inserting the additional or updated pages supplied.
Proper operation of the SGM5-EL can only be ensured if the contents of this
manual are known. Therefore, all chapters of this manual must be read
carefully prior to operating the SGM5-EL.
The values on the device display in this manual are examples or preset
parameters of the manufacturer. Process-specific parameters must be set by
the user.
Pages, charts and figures are numbered consecutively.
1.2 Copyright
This operation manual is copyright protected.
It must not be partially or completely reproduced, copied, or distributed, without
prior written permission of the manufacturer. The use for competitive
advantages or the distribution to third parties are not authorized either.
All rights reserved.
1.3 Commonly used symbols
Symbol for imminent danger:
This symbol refers to imminent danger to persons’ life and health.
In case of disregard fatal injuries may result.

Electrolysis Device SGM5EL General
5
attention
Symbol for indirect danger:
This symbol indicates indirect danger.
The degree of the damage depends on the circumstances and the actions of
the persons involved.
In case of disregard, destruction or damage of the SGM5-EL, its single
components or other material assets as well as minor injuries may result.
Symbol for proper handling:
This symbol appears where the manual refers to the adherence to rules,
instructions and proper operation.
In case of disregard, damage or destruction of the SGM5-EL or its single
components may result.
NOTE

Electrolysis Device SGM5EL Application
6
2 Application fields
One application field of electrolysis cells is the production of defined gas
atmospheres with a low oxygen concentration (approx. 1ppm O2in N2.
With
the SGM5-EL, a defined amount of oxygen can
be electrolyzed into or out of
the measuring gas (N2, argon). The downstream analysis cell
ensures that
the oxygen concentration is measured accurately.
Another application fie
ld is the use for the solid electrolyte coulometry
. In this
case the e.m.f.
of the analysis cell is kept constant as nominal value of an
automatic control loop. The current at the electrolysis cell, resulting from it,
is proportional to the oxygen exchange by the cell. With
the measurement of
I vs. t the oxygen exchange of arbitrary samples can be quantitatively
determined.
Furthermore, it is possible to set a defined humidity in a gas mixture. Oxygen,
for example, can be added to an argon hydrogen mixture.
With the
downstream analysis cell and a special evaluation electronics the dew point
and so the humidity can be calculated.
Designated use
Main fields of application
•Production of defined test gases e.g. for sensor tests
•Examination of the oxygen permeation of polymers (e.g. foils)
•Controlled outgassing of reactors
•System calibration and monitoring of TA systems (TG, DTA, TMA, DSC)
•Examination of the decomposition gases in thermal analysis
The introduction of explosive gas mixtures, halogens in high concentratio
n,
and sulphuric gases (e.g. SO2) into the SGM5-EL is not permitted.
With the SGM5-EL
Functions
•the oxygen concentration in a measuring gas can be maintained
•the electrolysis current can be maintained
•the change of the oxygen concentration caused by probe reactions
be quantified
•the oxygen output or uptake of a probe be quantified by
interpretation of the I*t-diagram
•technical inert gases can be adjusted at the requested purity
The requirements and limit values provided in the "Technical Data" must be
strictly observed.
Any other use is treated as non-authorized use.

Electrolysis Device SGM5EL Safety regulations
7
3 Safety regulations
The following regulations for industrial safety provide basic information about
potential danger during the operation of the SGM5-EL. Therefore, they must
be observed and strictly followed by the responsible staff.
•A failure-free and functional operating of the device can only be
guaranteed with knowledge of this manual. Therefore, all chapters of
this manual must be read carefully before the installation and initiation
of the device.
•The device is to be used for the functional operation only (see chapter
2).
The device is to be installed, operated, and serviced by trained staff
only.
•The SGM5-EL is to be connected to an isolated ground socket
(Schuko-socket) with the supplied cable.
Explosive gas mixtures, halogens in high concentration, and sulphuric
gases (e.g. SO2) are not permitted to be measured by this SGM5-EL.
Due to the high operation temperature of the sensor, the SGM5-EL
produces a lot of heat.
Make sure the device does not overheat because of covering.
Switch off and disconnect the device from the power supply before opening
the housing cover of the SGM5-EL.
Condensate destroys the combination cell.
If the device was used as a
humidity generator, appropriate action to prevent the combination cell from
condensate entry must be taken.
Special safety instructions for potential danger during certain working
processes are given in relevant text passages.

Electrolysis Device SGM5EL Functional description
8
4 Functional description
4.1 Measuring principle
Basic element of the SGM5-EL is the “combi cell”. An electrolysis cell and
additionally an analysis cell are located on a ZrO2solid electrolyte pipe
(general composition see chapter 6). Electrolysis and analysis cell are
electrochemical cells with two platinum electrodes each. The combi cell
separates the working substance from the ambient air.
If a current flows through the electrolysis cell, oxygen in chemically pure form
will be transferred from or into the gas room based on FARADAY`s Law:
FntI
⋅
⋅
=
⋅
4(I)
I - current in A n - amount of substance
t - time in s 4 - charge number
F - Faraday constant
The driving force for the current flow through the cell is the resultant from the
cell’s outside voltage u and the cell’s voltage Ueq. If the sign of the resultant
voltage corresponds to the sign of the cell voltage, oxygen flows through the
solid electrolyte wall in the direction of the concentration gradient. If the sign
of the resulting voltage reverses, oxygen is pumped against the
concentration gradient.
For the pumping performance (in cm3s-1) the following applies:
v (O2) = 0,06336·I/A
The real oxygen concentration of the measuring gas is determined by the
analysis cell. Its cell voltage Ueq in currentless condition depends on the
oxygen partial pressure in the working substance and in the air as well as on
the cell temperature. This correlation is based on the NERNST Law:
airO
gasmeasO
p
p
F
RT
U
,
.
2
,2
ln
4
=(II)
U - cell voltage in V
R - molar gas constant
T - measuring temperature in K
F - Faraday constant
pO2,air – oxygen partial
pressure at the reference
electrode in dry air in Pa
pO2,meas.gas – oxygen partial
pressure at the measuring
electrode in Pa.

Electrolysis Device SGM5EL Functional description
9
Based on the assumption that the total pressures of the gases are almost
the same at both electrodes (in this case the volume concentrations may
be used in the calculation instead of the partial pressures) and replacing
the parameters by numbers in equation (I) the following equation applies:
ϕ
O2=20.64 · e (-46,42 · ) (III)
U - potential difference in mV
T - measuring temperature in K
20.64 - oxygen concentration in air with a relative humidity
of 50% in vol%.
ϕ
O2 - oxygen concentration in the measured gas in vol%
4.2 Measuring conditions
4.2.1 General recommendations
The oxygen may be in free or bound form inside the measuring gas1.
Thereby, the following dependencies are valid:
– for free oxygen
– for bound oxygen
The equation (III) for calculating the oxygen concentration is valid for
measured gases with free oxygen as well as for reducing gas mixtures in
which oxygen only exists in bound form (e.g. in H2/H2O- or CO/CO2-
mixtures).
In reducing gas mixtures, the oxygen partial pressure is inversely
proportional to the temperature. For converting the measured value at the
measuring temperature into other temperatures special thermodynamic
equations are required.
Reducing gas
mixtures
1Different conditions of oxygen in the measuring gas must be distinguished:
Free oxygen: Oxygen molecules in the gas are independent without a bond to other gas components (inert gases
such as N2or Ar).
Bound oxygen: Free oxygen molecules do not exist in the gas, only in bound form e.g. as water vapor. Higher
temperatures cause a dissociation and oxygen molecules are available. Since the dissociation degree increases
with the temperature, the measurement result depends on the temperature.
Possibly, free oxygen can react with potential burnable gases at the hot platinum electrode. The result can be a
reducing gas.
U
T
U T~
U
T
~1

Electrolysis Device SGM5EL Functional description
10
4.2.2 Gas flow quantity
For exact measurements a flow
rate between 5 and 10 l/h of the measuring
gases must be ensured (see also chap. 8.1.2)
Contamination effects of the gas tubes (leaks, permeability, desorption) may
cause falsified measuring result if the flow rate is too low.
Asymmetric cooling of the sensor electrodes may cause falsified measuring
results if the flow rate is too high.
4.2.3 Accuracy of the measurement
The SGM5-EL can be used as an electrolysis device and as an oxygen
measuring device. For the measuring of oxygen the manufacturer
guarantees a measuring error of less than 3% (relative error) only at oxygen
concentrations within a range of 20.64*104... 10 ppm1. For measurements at
oxygen concentrations of 10 ... 0.5 ppm the relative error is less than 5% if
the gas inlet tube has no leakages or permeability.
During the electrolysis the limit values can only be reached if the measuring
gas is tuned to the measuring problem (e.g. It is not possible to get oxygen
concentrations in the “per-cent-area” from pure nitrogen).
For measurements of oxygen concentrations less than 10 ppm the following
aspects must be taken into account during evaluation:
• composition of the measuring gas (e.g. presence of burning
gases);
• specific characteristics of the production process (e.g. material
used);
• temperature of the measuring gas.
To reduce the measuring error in low oxygen concentrations, the following
conditions must be provided:
• All gas inlet and outlet pipes must be free of leakages.
• For measurements of oxygen concentrations of less than 100 ppm,
the use of steel pipes is necessary.
• If the measuring gas contains reducing components (e.g. alcohol), the
concentration of free oxygen cannot be determined correctly as
chemical reactions occur at the electrode. In such cases the measuring
gas should be filtered by an active carbon filter before entering the
SGM5-EL. (see Appendix)
1Throughout the manual the measuring unit "ppm" is defined as "vol.-ppm".
NOTE
NOTE

Electrolysis Device SGM5EL Technical Data
11
5 Technical data
5.1 Characteristics
Description............................................ Electrolysis device (SGM5-EL)
Application............................................ Modulation of oxygen concentrations in inert gases
Measuring range................................... 20.64*104... 0.5 ppm, (20.64... 0.5*10-4 vol.-%)
Measuring possible up to 10-20 ppm, see chapter 4.2
Accuracy at normal pressure ................ Relative error < 3% in the range of 20.64*104... 10 ppm
Relative error < 5% in the range of 10 ... 0.5 ppm
Gas flow quantity .................................. 5 ... 10 l/h for the given accuracy
Max. permitted pressure
of the measuring gas ........................... 100 mbar overpressure vs. ambient pressure
Max. permitted temperature of
the measured gas ................................. 80°C at the gas inlet
Pressure loss in the SGM5-EL............. Approx. 1 kPa (100 mm water column) at 10 l/h
5.2 Mechanical data / ambient conditions
Dimensions.......................................... Controlling device: 320×240×90
Combi cell: 262x119x119
Weight .................................................. Controlling device: 2.5 kg
Combi cell: 1.5 kg
Gas connection..................................... 3 mm Swagelok®
Ambient temperature/humidity .............. 10…40 °C, 95 % rH at 20 °C
Storage temperature/humidity............... -20…60 ° C, 95 % rH at 20 °C
5.3 Electrical data
Protection degree ................................. Controlling device: IP 30
Combi cell: IP20
Power supply
Voltage .......................................... 110 ··· 230 V/50 ··· 60 Hz
Power consumption ....................... 50 VA
Keypad and display
Keypad .......................................... Membrane keypad with 6 keys
Text display .................................. LCD dot-matrix

Electrolysis Device SGM5EL Technical data
12
5.4 Interface data
Serial interface RS-232
Transfer rate.................................. max. 19200 Baud, adjustable
Stop bits ........................................ 1
Data bits ........................................ 8
Parity............................................. none
Handshake .................................... none
Interface commands
All characters are ASCII - characters.
Each transfer is completed with 'CR' (CR = carriage return).
Command Reply (response) Description
M1CR M1x.xxE+xxCR Measuring value channel 1
M2CR M2x.xxE+xxCR Measuring value channel 2 (Electrolysis current [mA]
A1CR A1x.xxCR Voltage of the analysis cell [mV]
A2CR A2x.xCR Temperature of the analysis cell [°C]
u0CR u0 x.xCR Voltage of the analysis cell [mV]
u1CR u1 x.xCR Temperature of the analysis cell [mV]
u2CR Not used
u3CR Not used
u4CR u4 x.xxxE+xxCR Measuring value channel 1
u5CR u4 x.xxxE+xxCR Measuring value channel 2 (electrolysis current [mA])
u6CR u6 x.x x.x x.xxxxE+xxCR Vz [mV], Tz [°C], electrolysis current [mA]

Electrolysis Device SGM5EL Technical data
13
Modulation of the control parameter
r00CR R00 x.xxxxE+xxCR Read command variable
(values are read from the internal
memory)
R00 x.xxxxE+xxCR R00 x.xxxxE+xxCR Set command variable
0 - OFF
1 – Cell voltage [mV]
2 – Electrolysis current [mA]
3 – Oxygen concentration [ppm]
r01CR R01 x.xxxxE+xxCR Read setpoint
R01 x.xxxxE+xxCR R01 x.xxxxE+xxCR Set setpoint
r02CR R02 x.xxxxE+xxCR Read proportional value
R02 x.xxxxE+xxCR R02 x.xxxxE+xxCR Set proportional value
r03CR R03 x.xxxxE+xxCR Read reset time
R03 x.xxxxE+xxCR R03 x.xxxxE+xxCR Set reset time
r04CR R04 x.xxxxE+xxCR Read rate time
R04 x.xxxxE+xxCR R04 x.xxxxE+xxCR Set rate time
R!R! R! Save values
Error code Meaning
error0 Transcription error
error11 Measuring temperature too low
error16 Thermocouple defective
Error20 System error
Error99 No connection to the SGM5-EL
Pin assignment of the socket SUB-D 9-pol. F Pin assignment RS 232
Pin No
.
Marking
2 TxD
3 RxD
5 GNDA

Electrolysis Device SGM5EL Technical data
14
Analog output ............................... 0/4 ... 20 mA, adjustable, alternatively
0 ··· 5 V or 0 ··· 10 V (on request)
Alarm indication ............................ three potential free contacts (Changer),
max. 60 V DC, 1 A, 30 W or 125 V AC,
1A, 62 VA
Pin assignment of the socket analog output SUB-D 15-pol. F
Pin N
o
.
Marking
Legend
1 out1+ Analog output 1
2 out1- Analog output 1
3 out2+ Analog output 2
4 out2- Analog output 2
5
6
7 AL AK Alarm relay working contact
8 AL MK Alarm relay
9 AL RK Alarm relay break contact
10 GW1 AK Relay limit value 1
11 GW1 MK
12 GW1 RK
13 GW2 AK Relay limit value 2
14 GW2 MK
15 GW2 RK

Electrolysis Device SGM5EL Composition
15
6 Composition of the SGM5-EL
6.1 General composition
The SGM5-EL is composed of the control unit and the combicell. The general
composition and evaluation unit are shown in figure 1. The combi cell
consists of electrolysis cell and analysis cell (figure 2).
Fig. 1: Circuit diagram of the SGM5-EL
1 2 5 6 7 3 4
Measurig Gas
Fig 2: General composition of electrolysis and analysis cell
The electrolysis cell and the analysis cell consist of a tube made of zirconium
dioxide (2/1) with two platinum wire electrode. Inside the tube the measuring
electrode (2/3) is placed. The reference electrode (2/4) outside the tube has
a constant electrode potential. The measuring gas flows through the ceramic
tube. The electrodes and the ceramic tube form a galvanic cell (solid
electrolyte cell).
Measuring
cell
(sensor)
1 Ceramic tube
2 Ceramic cover of the
reference electrode
3 Measuring electrode
4 Reference electrode
5 Thermocouple
6 Reference electrode
connection
7 Measuring electrode
connection

Electrolysis Device SGM5EL Composition
16
In order to gain a higher oxide ion conductivity of the zirconium dioxide tube,
the sensor is heated up to 750°C. This also prevents interfering reactions
with combustible components of the measuring gas at the electrode due to
chemical unbalances. A thermocouple (2/5) inside the measuring cell
determines the actual electrode temperature. A heater control ensures a
constant temperature.
Sensor
heater
The heated combi cell produces lost heat. Make sure the device does not
overheat because of covering.
The measuring gas is pressed into the combi cell with low overpressure. For
the regulation of the gas flow a gas mixture device, needle valve or pressure
reducer can be used.

Electrolysis Device SGM5EL Composition
17
6.2 Construction of the control unit
6.2.1 Power supply
The SGM5-EL is connected with the power supply system with the supplied
cord set.
The SGM5-EL is designed as a desktop device. It is operated in horizontal
position with a maximum angle of inclination of 30°. The angle of inclination
of the SGM5-EL can be altered by pulling out the two attachment points of
the carrying handle between 0° and 30°. When the attachment points are
released, the carrying handle engages in the chosen position.
Operating
position and
inclination
adjustment
6.2.2 Front
Display and control elements are located on the front of the control unit.
Fig 3: Front of the control unit
measuring value
analysis cell
current
electrolysis cell
soft keys with explanation
ESC
enter key

Electrolysis Device SGM5EL Composition
18
6.2.3 Rear
All connections and the power switch are on the rear of the SGM5-EL.
Fig 4: Rear of the control unit
6.2.4 Combi cell
The combi cell is connected with the control unit with a 12pol cable. The
gas supply is connected via screw connections at the measuring head.

Electrolysis Device SGM5EL Installation
19
7 Installation and initiation
7.1 Installation conditions
The protective gas monitor must be set up in a dry and mainly dust-free
place.
• A socket, preferably as a separate electrical circuit, must be available
in immediate proximity of the installation place, protected with a 10 A
fuse.
• No heat sources or appliances which produce strong magnetic fields
(e.g. electric motors, transformers) should be put in the proximity of the
installation place.
• The SGM5-EL operates in horizontal position.
A vertical placement may cause damage by heat accumulation and is not
permitted.
A liquid entry can lead to severe damage or to the complete destruction
of the device. Do not place any items filled with liquids in immediate
proximity of the SGM5-EL!
7.2 Set-up of operating state
A temperature compensation is required after the transportation of the
SGM5-EL from cold surroundings to a site with higher ambient temperature
or humidity. A waiting time of about 2 hours before switching-on must be
considered.
1. Install the SGM5-EL in your favored place (see chapter 7.1).
2. Connect point of measurement and places of gas inlet and outlet of the
SGM5-EL. Pay attention to leak-tightness. For a fast measuring result the
dead volume of the gas lines must be kept low.
3. If a pressure limit is required, install a needle valve directly in front of the
gas inlet (available from manufacturer of the SGM5-EL).
On long transport routes and at unfavorable temperatures the material of
the connecting tubes must rule out any oxygen permeability. The
manufacturer recommends the following materials in dependence on the
measuring conditions:
Material of the
connecting
tubes
Oxygen concentration of < 100 ppm ............... Stainless steel tube.
Silicone can cause measuring inaccuracies because of its oxygen
permeability. Therefore, the manufacturer advises against use.
NOTE
NOTE

Electrolysis Device SGM5EL Installation
20
If the amount of water vapor in the measuring gas is likely to cause a
condensation of water in a cold gas pipe, a water trap must be installed in
front of the gas inlet. (The penetration of water into the hot measuring cell
can destroy it and therefore must be absolutely prevented.)
4. If you want to install an external flow meter, you have to install it behind
the gas outlet (where potential leaks do not have an influence on the
measuring result).
5. Connect the SGM5-EL with the power supply.
The measuring gas can also flow through the cold combi cell.
For using Swagelok®-fittings please note the manufacturer’s advice in the
appendix of this manual!
NOTE