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
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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
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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
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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
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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
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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
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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