EN 61207-2:1994
(Main)Expression of performance of gas analyzers - Part 2: Oxygen in gas (utilizing high-temperature electrochemical sensors)
Expression of performance of gas analyzers - Part 2: Oxygen in gas (utilizing high-temperature electrochemical sensors)
Applies to gas analyzers using high temperature electrochemical sensors for measurement of oxygen in gas. Applies to both 'in situ' and extractive analyzers installed indoors or outdoors.
Angabe zum Betriebsverhalten von Gasanalysatoren - Teil 2: Sauerstoff in Gas (unter Verwendung von elektrochemischen Hochtemperatur-Sensoren)
Expression des qualités de fonctionnement des analyseurs de gaz - Partie 2: Oxygène contenu dans le gaz (utilisant des senseurs électrochimiques à haute température)
S'applique aux analyseurs de gaz utilisant des capteurs électrochimiques à haute température pour la mesure de l'oxgène contenue dans les gaz. S'applique aux analyseurs Ôin-situ' et extractif installés à l'intérieur ou à l'extérieur.
Expression of performance of gas analyzers - Part 2: Oxygen in gas (utilizing high-temperature electrochemical sensors) (IEC 61207-2:1994)
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-november-1998
Expression of performance of gas analyzers - Part 2: Oxygen in gas (utilizing high-
temperature electrochemical sensors) (IEC 61207-2:1994)
Expression of performance of gas analyzers -- Part 2: Oxygen in gas (utilizing high-
temperature electrochemical sensors)
Angabe zum Betriebsverhalten von Gasanalysatoren -- Teil 2: Sauerstoff in Gas (unter
Verwendung von elektrochemischen Hochtemperatur-Sensoren)
Expression des qualités de fonctionnement des analyseurs de gaz -- Partie 2: Oxygène
contenu dans le gaz (utilisant des senseurs électrochimiques à haute température)
Ta slovenski standard je istoveten z: EN 61207-2:1994
ICS:
71.040.40 Kemijska analiza Chemical analysis
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
NORME CEI
IEC
INTERNATIONALE
1207-2
INTERNATIONAL
Première édition
STANDARD
First edition
1994-04
Expression des qualités de fonctionnement
des analyseurs de gaz -
Partie 2:
Oxygène contenu dans le gaz
(utilisant des capteurs électrochimiques
à haute température)
Expression of performance of gas analyzers -
Part 2:
Oxygen in gas
(utilizing high-temperature electrochemical sensors)
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IEC Publication 1207-2
Publication 1207-2 de la CEI
(First edition - 1994)
(Première édition - 1994)
Expression of performance
Expression des qualités de
of gas analyzers
fonctionnement des analyseurs de gaz
Part 2: Oxygen in gas (utilizing high-
2: Oxygène
Partie contenu dans le gaz
temperature electrochemical sensors)
(utilisant des capteurs électrochimiques
à haute température)
C O R R I G E N D U M 1
Page 11
Ne concerne que le texte anglais
In Note 2, under equations (1), (2) and (3),
in the explanation of E, instead of
... from the cell in mV;
read
... from the cell in V;
May 1994
Mai 1994
May 1994
– 3 – 1207-2 ©IEC:1994
CONTENTS
Page
FOREWORD 5
INTRODUCTION 7
Clause
1 Scope
2 Normative references 9
3 Definitions
15 4 Procedures for specification
rvices 4.1 Specification of essential units and ancillary se
rformance 4.2 Additional terms related to the specification of pe
rformance 4.3 Important terms related to the specification of pe
5 Procedures for compliance testing
5.1 General
21 5.2 Testing procedures
5.3 Output fluctuation
5.4 Delay time, rise time and fall time
Figures
1207-2 © IEC:1994 - 5 -
INTERNATIONAL ELECTROTECHNICAL COMMISSION
EXPRESSION OF PERFORMANCE OF GAS ANALYZERS -
Part 2: Oxygen in gas
(utilizing high-temperature electrochemical sensors)
FOREWORD
The IEC (International Electrotechnical Commission) is a worldwide organization for standardization
1)
comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to
promote international cooperation on all questions concerning standardization in the electrical and
electronic fields. To this end and in addition to other activities, the IEC publishes International Standards.
Their preparation is entrusted to technical committees; any IEC National Committee interested in
the subject dealt with may participate in this preparatory work. International, governmental and
non-governmental organizations liaising with the IEC also participate in this preparation. The IEC
collaborates closely with the International Organization for Standardization (ISO) in accordance with
conditions determined by agreement between the two organizations.
The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on
2)
which all the National Committees having a special interest therein are represented, express, as nearly as
possible, an international consensus of opinion on the subjects dealt with.
They have the form of recommendations for international use published in the form of standards, technical
3)
reports or guides and they are accepted by the National Committees in that sense.
In order to promote international unification, IEC National Committees undertake to apply IEC International
4)
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
International Standard IEC 1207-2 has been prepared by sub-committee 65D: Analyzing
equipment, of IEC technical committee 65: Industrial-process measurement and control.
The text of this standard is based on the following documents:
Report on voting
DIS
65D(CO)3 65D(CO)8
Full information on the voting for the approval of this standard can be found in the report
on voting indicated in the above table.
IEC 1207-2 constitutes part 2 of the 1207 series of publications under the general title:
Expression of performance of gas analyzers.
Part 1: General
Part 2: Oxygen in gas (utilising high-temperature electrochemical sensors)
Part 6: Photometric analyzers
Part 7: Infra-red analyzers
Parts 3, 4 and 5 are under consideration.
1207-2 © IEC:1994 – 7 –
INTRODUCTION
This part of IEC 1207 includes the terminology, definitions, statements and tests that are
specific to oxygen analyzers, which utilise high-temperature electrochemical sensors.
Oxygen analyzers employing high-temperature electrochemical sensors operating at tem-
peratures usually in excess of 600 °C, have a wide range of applications for the measurement
of oxygen in gas samples. Such samples are typically the result of a combustion process.
analyzer, where the sensor is positioned
Two main types of analyzer exist, the in situ
within the process duct work, and the "extractive" analyzer, where the sample is drawn
from the duct via a simple sample system and presented to the sensor.
An analyzer will typically comprise a sensor head, mounted on the process duct, and a
control unit remotely mounted, with interconnecting cable.
1207-2 © I EC:1994 - 9 -
EXPRESSION OF PERFORMANCE OF GAS ANALYZERS -
Part 2: Oxygen in gas
(utilizing high-temperature electrochemical sensors)
1 Scope
This part of IEC 1207 applies to all aspects of analyzers using high-temperature electro-
chemical sensors for the measurement of oxygen in gas. It should be used in conjunction
with IEC 1207-1.
It applies to and extractive analyzers and to analyzers installed indoors and out-
in-situ
doors.
The object of this pa rt
is:
to specify the terminology and definitions related to the functional performance of
-
gas analyzers, utilizing a high-temperature electrochemical sensor, for the continuous
measurement of oxygen concentration in a sample of gas;
- to unify methods used in making and verifying statements on the functional perform-
ance of such analyzers;
- to specify what tests should be performed to determine the functional performance
and how such tests should be carried out;
- to provide basic documents to suppo rt the application of standards of quality
assurance ISO 9001, ISO 9002 and ISO 9003.
2 Normative references
The following normative documents contain provisions which, through reference in
this text, constitute provisions of this pa rt of IEC 1207. At the time of publication, the
editions indicated were valid. All normative documents are subject to revision, and pa rties
to agreements based on this part of IEC 1207 are encouraged to investigate the possibility
of applying the most recent editions of the normative documents indicated below.
Members of IEC and ISO maintain registers of currently valid International Standards.
IEC 654, Operating conditions for industrial-process measurement and control equipment
IEC 1207-1: 1994, Expression of performance of gas analyzers - Part 1: General
- 11 -
1207-2 ©IEC:1994
3 Definitions
3.1 High-temperature electrochemical sensor
The high-temperature electrochemical sensor can be constructed in two basic forms:
Galvanic concentration cell.
a)
b) Ion pump cell.
Most commercially available analyzers employ the
3.1.1 galvanic concentration cell:
galvanic concentration cell consisting of two gas chambers, separated by an oxygen ion
conducting solid electrolyte, and provided with a porous electrode on each side.
NOTES
1 Platinum is frequently used for the electrodes, and the ceramic electrolyte is usually zirconium oxide,
fully or partially stabilized with yttrium oxide, calcium oxide or thorium oxide, which when heated above
600 °C, allows the charge transfer mechanism to be predominantly oxygen ion conduction.
2 When the sensor is brought to a temperature at which the solid electrolyte conducts oxygen ions and
the e.m.f. between the two electrodes is measured, the output will be related to the logarithm of the ratio of
the partial pressures of oxygen at each of the electrodes in accordance with the Nernst equation:
E 4 F In
P
P^
= klogio P
P^
(mV) = 0,0496 Tlog ^ o p2
E
where
ial pressure of oxygen in the reference gas;
P1 is the part
is the partial pressure of oxygen in the sample gas;
P2
E is the electromotive force output from the cell in mV;
R is the gas constant (8,3144 J K -1 mo 1-1);
T is the absolute temperature (K);
3 C mo 1-1);
F is the Faraday constant (96,484 56 x 10
k is the Nernstian coefficient (slope factor).
then the potential difference
rtial pressure is known at one electrode (P 1 ),
Thus, provided the oxygen pa
between the two electrodes will enable the unknown oxygen pressure to be determined at the other electrode
(P2).
The Nernstian response of the high-temperature electrochemical ceramic sensor holds over a very wide
range of oxygen partial pressures differences, and the sensor output increases logarithmically with linear
ial pressure at a given temperature. The sensor output is directly proportional to
reduction of the oxygen pa rt
temperature, and hence for quantitative analysis, the temperature of the cell should be closely controlled or
measured, and the necessary corrections applied in equation (1).
1207-2 © IEC:1994 -13 -
3 Zero offset
Theoretically the output e.m.f. of the sensor, when the partial pressures of the sample gas and reference gas
are equal, is zero volts. In some sensors a zero offset is measured and is considered largely due to thermo-
electric effects, and thermal gradients across the electrodes. This offset can be considered theoretically as
an extra constant (asymmetry potential).
P
(4)
k logio P + UT E (mV) =
^
P
+ UT (5)
E (mV) = 0,0496 T logio
P^
where
UT is the asymmetry potential (mV).
Non-ideal oxygen ion conduction can also be compensated for by introducing modifications to the slope
factor k.
U to help
ffset may supply practical average values of
In practice, manufacturers whose sensors exhibit zero o
in calibration. Modern equipment will automatically compensate the asymmetry potential during air point cali-
bration (i.e. air in both chambers).
If a direct current is made to flow between the electrodes of a cell,
3.1.2 ion pump cell:
with air in one chamber and an inert gas in the other chamber, the current flow will cause
a pumping of oxygen molecules from one side to the other. The action obeys Faraday's
laws and the quantity of oxygen pumped by diffusion into the inert gas is given by:
/ (6)
Q
4F
where
Q is the quantity of oxygen pumped in mol s-1;
/ is the current (A);
mol-t).
3 C
F is the Faraday constant (96,484 56 x 10
This is used generally in two basic configurations.
3.1.2.1 Limiting current - a diffusion pinhole limits the rate of arrival of oxygen
molecules at the measuring electrode, and a constant voltage across the electrodes
ensures that all the oxygen arriving at the measuring electrode is pumped to the other
side. The current generated is quantitatively related to the number of oxygen molecules
transferred.
3.1.2.2 Fixed volume - this configuration consists of two sets of electrodes arranged
across a small fixed volume. The first set comprises a concentration cell, the second set
the ion pump. The volume is initially swept of oxygen molecules to a predetermined low
level. Pump action is then initiated until the concentration cell reading shows that the oxy-
gen concentration in the volume and that outside at the sample side, are the same. The
current and time required to achieve this are related to the oxygen concentration of the
sample gas.
1207-2 ©IEC:1994 - 15 -
All analyzers using the high-temperature electrochemical concen-
reference gas:
3.2
tration cell require a reference sample of known and constant composition - usually air is
employed.
NOTE - The sensor output is a function of the partial pressure of oxygen in the sample, provided the
reference has a constant pa rtial pressure of oxygen.
analyzer has the high-temperature electrochemical sensor
3.3 in situ analyzer: The in situ
situated in the sample; however the sensor may require a filter to remove particulates.
analyzer controls the temperature of the sensor in the
One version of the in situ
range 600 °C to 800 °C. In this case the sa
...
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