IEC 61207-3:2019

IEC 61207-3 ®
Edition 3.0 2019-06
REDLINE VERSION
INTERNATIONAL
STANDARD
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Gas analyzers – Expression of performance –
Part 3: Paramagnetic oxygen analyzers

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IEC 61207-3 ®
Edition 3.0 2019-06
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Gas analyzers – Expression of performance –

Part 3: Paramagnetic oxygen analyzers

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 19.040; 71.040.40 ISBN 978-2-8322-7117-9

– 2 – IEC 61207-3:2019 RLV © IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope and object . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Procedures for specification . 16
4.1 General . 16
4.2 Specification of essential ancillary units and services . 16
4.2.1 Sampling system . 16
4.2.2 Services . 16
4.3 Additional characteristics related to specification of performance . 17
4.4 Important aspects related to specification of performance . 17
4.4.1 General . 17
4.4.2 Rated range of ambient temperature . 17
4.4.3 Rated range of sample gas temperature . 17
4.4.4 Rated range of ambient pressure . 18
4.4.5 Rated range of sample pressure . 18
4.4.6 Rated range of sample flow . 18
4.4.7 Rated range of sample dew point . 18
4.4.8 Rated range of sample particulate content . 18
4.4.9 Rated range of interference errors uncertainties . 19
4.4.10 Rated range of linearity error uncertainty . 19
4.4.11 Rated ranges of influence quantities . 19
5 Procedures for compliance testing . 19
5.1 Introduction Analyzer testing . 19
5.1.1 General . 19
5.1.2 Test equipment . 19
5.2 Testing procedures . 20
5.2.1 General . 20
5.2.2 Interference error uncertainty . 20
5.2.3 Wet samples . 21
5.2.4 Delay times, rise time, fall time . 21
Annex A (informative) Interfering gases . 23
Annex B (informative) Methods of preparation of water vapour in test gases . 27
Bibliography . 29

Figure 1 – Magnetic auto-balance system with current feedback . 10
Figure 2 – Thermomagnetic oxygen sensor . 11
Figure 3 – Differential pressure oxygen sensor . 12
Figure 4 – Typical sampling systems – Filtered and dried system with pump for wet
samples . 14
Figure 5 – Typical sampling system – Steam-aspirated system with water wash for wet
samples . 15
Figure 6 – General test arrangement – Dry gases . 20
Figure 7 – Test apparatus to apply gases and water vapour to analysis systems . 22

Table A.1 – Zero correction factors for current gases . 23

– 4 – IEC 61207-3:2019 RLV © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GAS ANALYZERS –
EXPRESSION OF PERFORMANCE –
Part 3: Paramagnetic oxygen analyzers

FOREWORD
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International Standard IEC 61207-3 has been prepared by sub-committee 65B: Measurement
and control devices, of IEC technical committee 65: Industrial-process measurement, control
and automation.
This third edition cancels and replaces the second edition published in 2002. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) all references (normative and informative) have been updated, deleted or added to as
appropriate;
b) all the terms, descriptions and definitions relating to the document have been updated
where appropriate;
c) all references to “errors” have been replaced by “uncertainties” and appropriate updated
definitions applied.
The text of this International Standard is based on the following documents:
FDIS Report on voting
65B/1155/FDIS 65B/1157/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
This International Standard is to be used in conjunction with IEC 61207-1:2010.
A list of all parts in the IEC 61207 series, published under the general title Gas analyzers –
Expression of performance, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.

– 6 – IEC 61207-3:2019 RLV © IEC 2019
INTRODUCTION
Paramagnetic oxygen analyzers respond to the partial pressure of oxygen in the measured
gas, and not the volumetric concentration is then determined by knowledge of the total
pressure, as in many other gas analyzers. Due to this fact, many paramagnetic oxygen
analyzers use pressure compensation (see 4.4.4 and 4.4.5). They are used in a wide range of
industrial, laboratory, medical, and other applications where the rated measuring range of the
analyzer is between 0 % to 1 % and 0 % to 100 %, at reference pressure (usually near
atmospheric).
Only a few gases display significant paramagnetism (for example, oxygen, nitric oxide and
nitrogen dioxide), and oxygen has a particularly strong the strongest paramagnetic
susceptibility (see Annex A) among gases. By employing this particular property of oxygen,
analyzers have been designed that can be highly specific to the measurement in most
industrial and medical applications, where, for example, high background levels of
hydrocarbons or moisture may be present.
There are several different techniques described for measuring the paramagnetic properties
of oxygen by its paramagnetic property, but three main methods have evolved over many
years of commercial application.
The three methods are:
– automatic null balance;
– thermomagnetic or magnetic wind;
– differential pressure or Quincke.
These methods all require the sample gas to be clean and dry non-condensing, though some
versions work at elevated temperatures so that samples that are likely to condense at a lower
temperature can be analyzed. Because of this requirement, analyzers often require a sample
system to condition the sample prior to measurement.

GAS ANALYZERS –
EXPRESSION OF PERFORMANCE –
Part 3: Paramagnetic oxygen analyzers

1 Scope and object
This part of IEC 61207 applies to the three main methods for measuring oxygen by its
paramagnetic property, which are outlined in the introduction. It considers essential ancillary
units and applies to analyzers installed indoors and outdoors.
NOTE Safety-critical applications can require an additional requirement of requirements from
system and analyzer specifications not covered in this document.
This document is intended
– to specify terminology and definitions related to the functional performance of para-
magnetic gas analyzers for the measurement of oxygen in a source gas;
– to unify methods used in making and verifying statements on the functional performance of
such analyzers;
– to specify what tests should be are performed to determine the functional performance and
how such tests should be are carried out;
– to provide basic documents to support the application of internationally recognized quality
management standards of quality assurance (ISO 9001, ISO 9002 and ISO 9003).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60654-1:1993, Industrial-process measurement and control equipment – Operating
conditions – Part 1: Climatic conditions
IEC 61115:1992, Expression of performance of sample handling systems for process
analyzers
IEC 61207-1:1994, Expression of performance of gas analyzers – Part 1: General
ISO 9001:2000, Quality management systems – Requirements
ISO 9002:1994, Quality systems – Model for quality assurance in production, installation and
servicing
ISO 9003:1994, Quality systems – Model for quality assurance in final inspection and test
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

– 8 – IEC 61207-3:2019 RLV © IEC 2019
NOTE Although cgs (centimetre-gram-second) units have been used in this document, SI (Système International)
units (such as defined in IUPAC [1] ) can also be used.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
magnetic susceptibility
measure (X) of the variation of the intensity of a magnetic field H, existing in a vacuum, when
the vacuum is substituted (filled) by the test substance, expressed as:
H − H
X =
H
where
H is the magnetic field intensity in vacuum
H is the magnetic field intensity in the test substance
Note 1 to entry: H – H is also known as the magnetisation MV (magnetic dipole per unit volume) and therefore
this is also the volume magnetic susceptibility.
3.2
paramagnetism
property of substances causing an increase of the magnetic field intensity (X > 0)
3.3
diamagnetism
property of substances causing a diminution of the magnetic field intensity
(X < 0 because H < H)
3.4
specific magnetic susceptibility
ratio of magnetic susceptibility to the density derived as follows:
X
X =
s
D
where
−3
D is the density of the considered substance, expressed in g·cm at 273,15 K (0 °C) and,
101,3 kPa (= 1 bar).
3 −1
Note 1 to entry: The measuring unit of X is therefore cm ·g . This is also known as the mass magnetic
s
susceptibility.
3.5
molar magnetic susceptibility
X
m
specific magnetic susceptibility multiplied by the molecular weight mass (M) of the substance
considered:
X X⋅ M
ms
__________
Numbers in square brackets refer to the bibliography
=
where
−1
M is expressed in g per mole (g·mol ) (for oxygen M = 32 31,998 8)
3 −1
Note 1 to entry: The measuring unit of X is therefore cm ·mol .
m
Note 12 to entry: Electrons determine the magnetic properties of matter in two ways:
– an electron can be considered as a small sphere of negative charge spinning on its axis. This spinning charge
produces a magnetic moment;
– an electron travelling in an orbit around a nucleus will also produce a magnetic moment.
It is the combination of the spin moment and the orbital moment that governs the resulting magnetic properties of
an individual atom or ion.
In paramagnetic materials, the main contribution to the magnetic moment comes from unpaired electrons. It is the
configuration of the orbital electrons and their spin orientations that establish the paramagnetism of the oxygen
molecule and distinguish it from most other gases.
Note 23 to entry: When paramagnetic gases are placed within an external magnetic field, the flux within the gas is
higher than it would be in a vacuum, thus paramagnetic gases are attracted to the part of the magnetic field with
the strongest magnetic flux. On the contrary, diamagnetic substances contain magnetic dipoles which cancel out
some lines of force from the external field; thus diamagnetic gases are subject to repulsion by the magnetic flux.
Note 34 to entry: The molar magnetic susceptibility of oxygen is inversely proportional to the absolute
temperature T. According to Van Vleck [2] the molar susceptibility of oxygen can be approximated by Equation (4).
8L ⋅ µ
B
For oxygen, X = (4)
m
3kT
where
3 −1
X is the molar susceptibility of oxygen, expressed in cm ·mol ;

m
23 −1
L is the Avogadro constant = 6,022 7 × 10 mol ;
−24 2
µ is the Bohr magneton = 9,274 × 10 A·m ;
B
−23 −1
k is the Boltzmann constant = 1,38 × 10 J·K ;
T is the temperature, expressed in K (kelvin).
Equation (4) can be written as follows:
−6 3 −1
X = × 10 cm ·mol (only for oxygen).
m
T
Note 5 to entry: A full understanding of paramagnetism and diamagnetism can be obtained from physics and
inorganic chemistry textbooks. The explanation in this document is to give the user of paramagnetic oxygen
analyzers a simple understanding of the physical property utilized.
3.6
automatic null balance analyzer
analyzer that uses, as a general principle of operation, the displacement of a body
this type of
containing a vacuum or a diamagnetic gas, from a region of high magnetic field by
paramagnetic oxygen molecules
Note 1 to entry: See Figure 1.

– 10 – IEC 61207-3:2019 RLV © IEC 2019

Figure 1 – Magnetic auto-balance system with current feedback
Note 2 to entry: The measuring cell typically employs a glass dumb-bell, with the spheres containing nitrogen,
suspended on a torsion strip between magnetic pole pieces or magnets that concentrate the flux produce a very
strong magnetic field gradient around the dumb-bell. The measuring cell has to be placed in a magnetic circuit. The
dumb-bell is then deflected when oxygen molecules enter the measuring cell, a force being exerted on the dumb-
bell by the oxygen molecules which are attracted to the strongest part of the magnetic field. By use of an optical
levers, a feed-back magnetic actuation coil, and suitable electronics to generate a feedback signal that nulls the
magnetic susceptibility force, an output that is directly proportional to the partial pressure of oxygen can be
achieved. The transducer is usually can be maintained at a constant temperature to prevent the variations in
magnetic susceptibility with to temperature from introducing errors uncertainties. Alternatively, built-in temperature
sensors may be used to provide temperature compensation of the oxygen reading. Additionally, the elevated
temperature helps in applications where the sample is not particularly dry. Some analyzers are designed so that
the transducer operates at a temperature in excess of 373,15 K (100 °C) to further facilitate applications where
condensates would form at a lower temperature. Paramagnetic sensor orientation may also affect the oxygen
measurement uncertainty and this may be corrected by using a compensation algorithm using, for example, a
three-dimensional accelerometer to determine the sensor orientation relative to its orientation during calibration.
Due to the mechanical nature of this type of device, there is some inherent susceptibility to vibrational and
gyroscopic motion, potentially resulting in increased measurement uncertainty.
3.7
thermomagnetic (magnetic-wind) analyzer
3.7.1
magnetic wind analyzer
this type of analyzer utilizes that uses the temperature dependence of the magnetic
susceptibility to generate a magnetically induced gas flow which can then be measured by a
flow sensor
Note 1 to entry: The sample gas passes into a chamber designed in such a way that the inlet splits the flow.
Note 2 to entry: See Figure 2.

Figure 2 – Thermomagnetic oxygen sensor
Note 3 to entry: The two flows recombine at the outlet. A connecting tube is placed centrally with the flow sensor
wound on it. Half of the connecting tube is placed between the poles of a strong magnet. The flow sensor is
effectively two coils of wire heated to about 353,15 K (80 °C) by passage of a current. The cold oxygen molecules
are diverted by the magnetic field into the central tube, and, as they heat up, their magnetic susceptibility is
reduced and more cold oxygen molecules enter the connecting tube. A flow of oxygen is generated in this way
through the transversal connecting tube, with the effect of cooling the first coil (which is placed in the magnetic
field area), while the temperature of the second coil is not essentially influenced by this transversal flow. Since the
two coils are wound with thermosensitive wire (for example, platinum wire) and connected together to build a
Wheatstone bridge, the resulting unbalance current is a nearly proportional function of the oxygen partial pressure
in the test gas.
More recent analyzers use more refined measuring cells, toroidal shaped resistors instead of the two-coil flow
sensor, and employ temperature control to minimize ambient temperature changes.
As this method relies on heat transfer, the thermal conductivity of background gases will affect the oxygen reading
and the composition of the background has to be known. Some analyzers can give a first-order correction for this
by utilizing further compensation devices.
Thermomagnetic analyzers do not produce a strictly linear output and additional signal processing is required to
linearize the output.
– 12 – IEC 61207-3:2019 RLV © IEC 2019
3.8
differential pressure ( Quincke) analyzer
3.8.1
differential pressure analyzer
this type of analyzer utilizes that uses a pneumatic balance system established by using a
flowing reference gas (such as nitrogen or air)
Note 1 to entry: The measuring cell is designed so that at the reference gas inlet the flow is divided into two
paths. These flows recombine at the reference gas outlet, where the sample is also introduced. A differential
pressure sensor (or microflow sensor) is positioned across the two reference gas flows so that any imbalance is
detected. A magnet is situated in the vicinity of the reference gas outlet in one arm of the measuring cell so that
oxygen in the sample is attracted into the arm, thereby causing a small back pressure which is detected by the
pressure sensor (see Figure 3).

Figure 3 – Differential pressure oxygen sensor
Note 2 to entry: Differential pressure analyzers are independent of thermal conductivity of background gases, and
as only the reference gas comes in contact with the sensor, corrosion problems are minimal. Some instruments use
pulsed magnetic fields to improve tilt sensitivity, and certain designs compensate for vibration effects.
3.9
hazardous area
area where there is a possibility of release of potentially flammable gases, vapours or dusts.
Restrictions in the use of electrical equipment apply in hazardous areas
area in which an explosive gas atmosphere is present, or may be expected to be present, in
quantities such as to require special precautions for the construction, installation and use of
devices
3.10
essential ancillary unit
essential ancillary units are those unit without which the analyzer will not operate within
specifications
EXAMPLE: Calibration systems, reference gas systems, sample systems.
3.11
sample systems
see figures 4 and 5 for typical sampling systems. For full details of sample systems require-
ments, see IEC 61115.
A sample system is a system of component parts assembled on a panel or in an analyzer
house with the purpose of transporting the sample gas from the sampling point to the analyzer
and presenting the sample in such a manner that reliable measurements can be obtained
Note 1 to entry: The components used can include
– pressure regulators;
– flow meters;
– flow controllers;
– filtration units;
– pumps;
– valves (manual and/or electrically operated);
– catch or knockout pots;
– coolers;
– heaters;
– drying units;
– scrubbing units.
Note 2 to entry: See Figure 4 and Figure 5 for examples of typical sampling systems. For full details of sample
system requirements, see IEC 61115 [3]. These components will usually be designed as a sample system by the
user or, more often, by a manufacturer, so that the analyzer requirements defined in the specification are within the
rated operating range. The required system design is therefore very dependent on the sample conditions of the
process. Variations in sample pressure, temperature, dust loading, and pressure of other gases and vapours will
affect the final sample system design.

– 14 – IEC 61207-3:2019 RLV © IEC 2019

Figure 4 – Typical sampling systems –
Filtered and dried system with pump for wet samples

Figure 5 – Typical sampling system – Steam-aspirated system
with water wash for wet samples
3.12
sample dew point
dew point of a sample expressed in K and is the temperature at or below which condensation
occurs
Note 1 to entry: The analyzer should be operated at a minimum of 5 K above the sample dew point to prevent
formation of condensate.
Note 2 to entry: The presence of condensation at the inlet of an analyzer will usually cause malfunction.
Condensate may form from water vapour or other vapours depending on the nature of the sample.
3.13
reference gas
the Quincke analyzer requires a reference gas of known constant composition
Note 1 to entry: Pure nitrogen is usually employed. The reference gas can have an oxygen content, for example
air. This has the effect of giving a suppressed zero and is useful when measuring high oxygen concentrations as it
reduces the influence of barometric pressure.

– 16 – IEC 61207-3:2019 RLV © IEC 2019
4 Procedures for specification
4.1 General
The procedures are detailed in IEC 61207-1. This covers:
– operation and storage requirements;
– specification of ranges of measurement and output signals;
– limits of errors uncertainties;
– recommended reference values and rated ranges of influence quantities (see IEC 60654-1).
In this part of IEC 61207, requirements for essential ancillary units and services are given.
Additional characteristics for specification of performance and important aspects of
performance relevant to paramagnetic analyzers are detailed.
4.2 Specification of essential ancillary units and services
4.2.1 Sampling system
The sampling system must shall be specified to supply the sample within the rated range of
influence quantities of the analyzer.
NOTE 1  Simple elements of the sampling system may be included in the analyzer. Sample
flow meters, sample flow regulation, bypass flow meters, bypass flow regulations, sample
filters are often part of the analyzer.
NOTE 2  If certain system elements are included in the analyzer the rated range of influence
quantities will be less severe compared to an analyzer without any sampling system.
The sampling system will add a delay in addition to the response time of the analyzer. Hence,
the sample system response time should be specified.
The chemical composition of the sample stream must shall be considered in the system
specification. Special precautions need to be taken for flammable samples, toxic samples or
corrosive samples.
Some materials are permeable to oxygen (for example, silicones) and should be avoided the
measurement uncertainties that may be introduced by them should be considered and
avoided if necessary. For systems measuring very high concentrations of oxygen, the
sampling system components should be clean for oxygen service to prevent any dangerous
reactions with flammable contaminants.
4.2.2 Services
4.2.2.1 General
Paramagnetic oxygen analyzers will require facilities for calibration after installation. Bottled
calibration gases and pressure regulation facilities are generally required. Quincke analyzers
will additionally require facilities for supplying the reference gas.
NOTE Nitrogen is usually employed for zero calibration. The span gas will usually be a known concentration of
oxygen in nitrogen typically about 80 % of the measuring range. Air contains between 20,64 % and 20,95 % O by
volume due to varying humidity. Dry air or instrument air at 20,95 % O can therefore be used for span calibrations.
If the oxygen level of the sample gas is high, then 100 % O is usually used as the span gas.
4.2.2.2 Rated range of calibration and reference gas pressure
Calibration and reference gas pressure shall be within the rated range of sample pressure for
the analyzer, to prevent possible damage to the paramagnetic sensor.

4.2.2.3 Rated range of calibration and reference gas flow
Calibration and reference gas flow shall be within the rated range of sample flow for the
analyzer. For minimum errors uncertainties, the calibration gas flow should be set the same
as the sample flow. Excessively high calibration and reference gas flows can damage the
paramagnetic sensor, particularly from a large pressure impulse, which may occur if the flow
outlet becomes blocked and then quickly released.
4.3 Additional characteristics related to specification of performance
4.3.1 The following additional characteristics to those detailed in IEC 61207-1 may be
required to be specified to define the performance of a paramagnetic analyzer or its suitability
for a particular application. Depending on the analyzer design details or application, some of
these additional terms may be omitted.
4.3.2 Hazardous classification of the area in which the analyzer is to be located. General
purpose analyzers will not be suitable for location in hazardous areas.
4.3.3 Flammable gases or vapours should only be sampled by analyzers which are
specified as suitable and should be vented from the analyzer in a safe manner.
4.3.4 If the sample gas is toxic, this should be specified, as special maintenance ins-
tructions may be required to ensure leak-free operation. Installation of the analyzer must shall
also take into account how the sample gas is vented, returned to process, or otherwise dealt
with.
4.3.5 The attitude orientation of the analyzer should be considered. In fixed installations,
analyzers should be located positioned in an upright attitude manner so that any errors
uncertainties due to tilt are minimized. For moving installations that move (for example,
ships), the rated range of tilt should be specified.
4.3.6 The vibration sensitivity of the analyzer should be considered. For applications where
the vibration levels are outside the rated range of the analyzer, anti-vibration mountings are
recommended.
4.3.7 The response time of the analyzer and its sampling system should be considered.
The response time specified for the analyzer will usually be considerably less than the
sampling system, but is dependent on the sampling system design.
NOTE Some paramagnetic analyzers are designed with adjustable sample flow and bypass flow sample systems.
4.4 Important aspects related to specification of performance
4.4.1 General
Although covered in IEC 61207-1, the following aspects are particularly relevant to
paramagnetic analyzers.
4.4.2 Rated range of ambient temperature
The performance of an analyzer is normally ambient temperature-dependent and will have a
defined operating range of temperatures within which it will operate within its specification.
4.4.3 Rated range of sample gas temperature
NOTE The magnetic susceptibility of oxygen is temperature-dependent, and large errors
uncertainties in the measurement value occur unless the analyzer is designed to compensate
for the temperature of the sensor. In practice, the temperature of the paramagnetic sensor will
depend on ambient temperature and gas temperature. Process paramagnetic oxygen
analyzers usually employ temperature-controlled sensors (in addition to temperature

– 18 – IEC 61207-3:2019 RLV © IEC 2019
compensation) to minimize effects of sample temperature changes and ambient temperature
changes. Simple analyzers may not have temperature-controlled sensors, in which case
calibration should precede measurements so that ambient temperature effects and sample
temperature effects are taken into account.
4.4.4 Rated range of ambient pressure
NOTE Measurement values are dependent on sample pressure. If the analyzer is vented to
atmosphere, so that the sample within the sensor is at ambient pressure, changes in
errors uncertainties in the measured value. For analyzers where
barometric reading will cause
the measured value is directly proportional to the sample pressure (automatic null balance
analyzer), error uncertainty can occur in O readings (% O ),
2 2
PP −
mc
∆×O =  O (5)
mm
P
c
where
O is the oxygen reading at time of measurement in % O ;
m 2
P is the absolute ambient pressure at time of measurement in kPa;
m
P is the absolute ambient pressure at time of calibration in kPa.
c
Barometric pressure compensation is usually offered by manufacturers to minimize this type
of error uncertainty.
4.4.5 Rated range of sample pressure
If the sample is returned to the process stream (assuming process pressure is within the rated
range of sample pressure), variations in process pressure will cause similar errors
uncertainties to those described in 4.4.4.
Sample pressure compensation is usually offered by manufacturers of process analyzers so
that this type of error uncertainty is minimized.
4.4.6 Rated range of sample flow
Errors Uncertainties in indicated value due to sample flow can be minimized by setting the
calibration flow rates to the expected sample flow rates.
4.4.7 Rated range of sample dew point
Samples must shall be supplied within the rated range of the sample dew point to increase
performance reliability. Also, differences in indicated value will occur if the measurement is
made on a wet basis compared to a dry basis.
NOTE 1 If the rated range of sample dew point for an analyzer is low, then the sampling system may can have to
remove water vapour from the sample. If, for example, 10 % water vapour were removed by the sample system, the
corresponding indicated oxygen value would be 100/90 times greater than the value in the wet sample.
NOTE 2 Some oxygen analyzers are designed so that the sensor is controlled at temperatures within the range
333,15 K to 393,15 K (60 °C to 120 °C). This will enable relatively wet samples to be analyzed reliably. For
example, a sample saturated with water vapour at 294,15 K (21 °C) contains approximately 2,5 % water vapour.
This wet sample would normally be within the rated range of the sample dew point for an analyzer wherein the
sensor is controlled at 333,15 K (60 °C). However, the water content in the sample will produce a volumetric error
compared to a measurement made on a dry basis where the water has been removed prior to measurement.
4.4.8 Rated range of sample particulate content
Paramagnetic oxygen analyzers usually require a relatively clean sample to ensure reliable
), and
operation. The rated range of particulates defined in mass per cubic metre (mg/m
maximum particulate size in microns (µm) should not be exceeded.

4.4.9 Rated range of interference errors uncertainties
NOTE Paramagnetic oxygen analyzers are by design specifically measuring the magnetism of
the sample gas. Oxygen has a high magnetic susceptibility and the measurement is therefore
quite specific, but see Annex A for interferences of other common gases. Nitrogen oxide, in
particular, has a significant cross-interference.
Some oxygen analyzers will have interference errors uncertainties from properties of gases
other than the magnetic susceptibility. For example, gases of high thermal conductivity in the
errors uncertainties in the indicated value in magnetic wind analyzers,
sample may introduce
though modern analyzers may partially compensate for this.
Water vapour content shall be in the rated range of the sample dew point (see 4.4.7).
Interference errors uncertainties, other than those due to volumetric effects, may occur.
4.4.10 Rated range of linearity error uncertainty
Some analyzers are inherently linear and have very small linearity errors uncertainties.
4.4.11 Rated ranges of influence quantities
Ranges for climatic conditions, mechanical conditions and main supply conditions are
specified in IEC 60654-1.
NOTE In addition, paramagnetic oxygen analyzers may can be affected by the presence of nearby magnetic
material fields.
5 Procedures for compliance testing
5.1 Introduction Analyzer testing
5.1.1 General
The tests considered in Clause 5 apply to the complete analyzer as supplied by the
manufacturer and include all essential ancillary equipment. The analyzer will be set up by the
manufacturer, or in accordance with his instruction, prior to testing.
5.1.2 Test equipment
The following test equipment for verification of values that confirm the performance of
paramagnetic oxygen analyzers will be required.
a) Gas mixing equipment to prepare the required test gases (certified calibration gases can
be used).
b) Equipment to present the test gases to the analyzer at the required pressure, flow and
temperature. Gases have to be switched over to enable response time measurements.
c) Equipment to measure interference errors uncertainties. This will also include temperature
controlled bubblers or other moisture generation equipment so that the effects of water
vapour can be measured.
d) An environmental chamber will be required to measure appropriate influence errors
uncertainties, such as temperature or humidity.
e) Equipment for determining influence quantities from variation in supply voltage, frequency
and supply interruption.
uncertainties due to electromagnetic
f) Equipment to determine influence errors
susceptibility. Radiated emissions may have to be determined.
g) Equipment to determine influence errors uncertainties under vibration.
Figure 6 shows the general test arrangement for dry gases.

– 20 – IEC 61207-3:2019 RLV © IEC 2019

* Dead space to be minimized to avoid uncertainties in response time measurement.
Figure 6 – General test arrangement – Dry gases
5.2 Testing procedures
5.2.1 General
The following relevant testing procedures are detailed in IEC 61207-1.
– Intrinsic error uncertainty.
– Linearity error uncertainty.
– Repeatability err
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