IEC 61207-7:2013

IEC 61207-7 ®
Edition 1.0 2013-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Expression of performance of gas analyzers –
Part 7: Tuneable semiconductor laser gas analyzers

Expression des performances des analyseurs de gaz –
Partie 7: Analyseurs de gaz laser à semiconducteurs accordables

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite ni
utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les
microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé Fax: +41 22 919 03 00
CH-1211 Geneva 20 info@iec.ch
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

Useful links:
IEC publications search - www.iec.ch/searchpub Electropedia - www.electropedia.org
The advanced search enables you to find IEC publications The world's leading online dictionary of electronic and
by a variety of criteria (reference number, text, technical electrical terms containing more than 30 000 terms and
committee,…). definitions in English and French, with equivalent terms in
It also gives information on projects, replaced and additional languages. Also known as the International
withdrawn publications. Electrotechnical Vocabulary (IEV) on-line.

IEC Just Published - webstore.iec.ch/justpublished Customer Service Centre - webstore.iec.ch/csc
Stay up to date on all new IEC publications. Just Published If you wish to give us your feedback on this publication
details all new publications released. Available on-line and or need further assistance, please contact the
also once a month by email. Customer Service Centre: csc@iec.ch.

A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.

Liens utiles:
Recherche de publications CEI - www.iec.ch/searchpub Electropedia - www.electropedia.org
La recherche avancée vous permet de trouver des Le premier dictionnaire en ligne au monde de termes
publications CEI en utilisant différents critères (numéro de électroniques et électriques. Il contient plus de 30 000
référence, texte, comité d’études,…). termes et définitions en anglais et en français, ainsi que
Elle donne aussi des informations sur les projets et les les termes équivalents dans les langues additionnelles.
publications remplacées ou retirées. Egalement appelé Vocabulaire Electrotechnique
International (VEI) en ligne.
Just Published CEI - webstore.iec.ch/justpublished
Service Clients - webstore.iec.ch/csc
Restez informé sur les nouvelles publications de la CEI.
Just Published détaille les nouvelles publications parues. Si vous désirez nous donner des commentaires sur
Disponible en ligne et aussi une fois par mois par email. cette publication ou si vous avez des questions
contactez-nous: csc@iec.ch.
IEC 61207-7 ®
Edition 1.0 2013-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Expression of performance of gas analyzers –

Part 7: Tuneable semiconductor laser gas analyzers

Expression des performances des analyseurs de gaz –

Partie 7: Analyseurs de gaz laser à semiconducteurs accordables

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX T
ICS 19.040; 71.040.40 ISBN 978-2-8322-1117-5

– 2 – 61207-7  IEC:2013
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Procedure for specification . 10
4.1 General . 10
4.2 In situ analyzers . 10
4.2.1 Additional operation and maintenance requirements . 10
4.2.2 Additional terms related to the specification of performance . 10
4.2.3 Additional limits of uncertainties . 11
4.3 Extractive analyzers . 11
4.3.1 Additional operation and maintenance requirements . 11
4.3.2 Additional terms related to the specification of performance . 12
4.4 Recommended standard values and range of influence quantities . 12
4.5 Laser safety . 12
5 Procedures for compliance testing . 12
5.1 In situ analyzers . 12
5.1.1 General . 12
5.1.2 Apparatus to simulate measurement condition . 13
5.1.3 Apparatus to generate test gas mixture . 13
5.1.4 Apparatus to investigate the attenuation induced by opaque dust,
liquid droplets and other particles . 13
5.1.5 Testing procedures . 14
5.2 Extractive analyzers . 16
5.2.1 General . 16
5.2.2 Apparatus to generate test gas mixture . 16
5.2.3 Testing procedures . 16
Annex A (informative) Systems of tuneable semiconductor laser gas analyzers . 18
Annex B (normative) Examples of the test apparatus . 19
Bibliography . 23

Figure A.1 – Tuneable semiconductor laser gas analyzers . 18
Figure B.1 – Example of a test apparatus to simulate measurement condition for
across-duct and open-path analyzers . 19
Figure B.2 – Example of a test apparatus to simulate measurement condition for probe
type analyzers . 19
Figure B.3 – Example of apparatus to generate the test gas mixture . 20
Figure B.4 – Delay time, rise time and fall time . 21
Figure B.5 – Example of a grid to simulate the attenuation by the dust in optical path . 22

61207-7  IEC:2013 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EXPRESSION OF PERFORMANCE OF GAS ANALYZERS –

Part 7: Tuneable semiconductor laser gas analyzers

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). 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. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61207-7 has been prepared by subcommittee 65B: Measurement
and control devices, of IEC technical committee 65: Industrial-process measurement, control
and automation.
The text of this standard is based on the following documents:
FDIS Report on voting
65B/876/FDIS 65B/891/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This International Standard is to be used in conjunction with IEC 61207-1:2010.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – 61207-7  IEC:2013
A list of all parts of the IEC 61207 series, under the general title Expression of performance of
gas analyzers, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
The contents of the corrigendum of June 2015 have been included in this copy.
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 document using a
colour printer.
61207-7  IEC:2013 – 5 –
INTRODUCTION
This part of IEC 61207 includes the terminology, definitions, statements and tests that are
specific to tuneable semiconductor laser gas analyzers, which utilize tuneable semiconductor
laser absorption spectroscopy (TSLAS).
Tuneable semiconductor laser gas analyzers utilize tuneable semiconductor lasers (e.g. diode
lasers, quantum cascade lasers, interband cascade lasers) as light sources, whose
wavelength covers ultraviolet, visible and infrared part of the electromagnetic spectrum, to
detect the absorption spectra and thus determine the concentration of gases to be analyzed.
These analyzers may employ different TSLAS techniques such as direct absorption
spectroscopy, frequency modulation spectroscopy (FMS), wavelength modulation
spectroscopy (WMS), etc. Multi-pass absorption spectroscopy, photoacoustic spectroscopy
(PAS), and cavity-enhanced absorption spectroscopy (CEAS) such as cavity-ringdown
spectroscopy (CRDS) are also used to take advantage of their high detection sensitivity.
Tuneable semiconductor laser gas analyzers are usually used to measure concentration of
small molecule gases, such as oxygen, carbon monoxide, carbon dioxide, hydrogen sulfide,
ammonia, hydrogen fluoride, hydrogen chloride, nitrogen dioxide, water vapour etc.
There are two main types of tuneable semiconductor laser gas analyzers: extractive and in
situ analyzers. The extractive analyzers measure the sample gas withdrawn from a process or
air by a sample handling system. The in situ analyzers measure the gas in its original place,
including across-duct, probe and open-path types. Across-duct analyzers either have a laser
source and a detector mounted on opposite sides of a duct, or both the laser and the detector
are mounted on the same side and a retroreflector on the opposite side of a duct. Probe
analyzers comprise a probe mounted into the duct, and the measured gas either passes
through or diffuses into the measuring optical path inside the probe. And open-path analyzers
measure the gas in an open environment with a hardware approach similar to across duct
analyzers (source and detector on opposite sides of the open area or a retroreflector on one
side and the source and detector on the opposite side), except the sample is in an open path
and not contained in a duct.
NOTE 1 Traditionally, only diode lasers were employed, and thus tuneable diode laser gas analyzers and
tuneable diode laser absorption spectroscopy (TDLAS) are widely used terms. However, with the development of
laser technology, many other types of semiconductor lasers, such as quantum cascade lasers (QCLs) and
interband cascade lasers (ICLs) have been developed and employed in laser gas analyzers. Therefore, the term of
semiconductor laser rather than diode laser is used in this standard to reflect this technology advancement.
NOTE 2 Though tuneable semiconductor laser photoacoustic spectroscopy (PAS) is in principle different from
absorption spectroscopy typically used in tuneable semiconductor laser gas analyzers, the hardware and data
reduction software are almost the same for analyzers utilizing these two spectroscopy technologies, and thus PAS
is considered a variant of absorption spectroscopy and this standard also applies to the analyzers based on PAS.

– 6 – 61207-7  IEC:2013
EXPRESSION OF PERFORMANCE OF GAS ANALYZERS –

Part 7: Tuneable semiconductor laser gas analyzers

1 Scope
This part of IEC 61207 applies to all aspects of analyzers utilizing TSLAS for the
concentration measurement of one or more gas components in a gaseous mixture or vapour.
It applies to analyzers utilizing tuneable semiconductor lasers as sources and utilizing
absorption spectroscopy, such as direct absorption, FMS, WMS, multi-pass absorption
spectroscopy, CRDS, ICOS, PAS and CEAS techniques, etc.
It applies both to in situ or extractive type analyzers. This standard includes the following, it
– specifies the terms and definitions related to the functional performance of gas analyzers,
utilizing tuneable semiconductor laser gas absorption spectroscopy, for the continuous
measurement of gas or vapour concentration in a source gas,
– unifies methods used in making and verifying statements on the functional performance of
this type of analyzers,
– specifies the type of tests to be performed to determine the functional performance and
how to carry out these tests,
– provides basic documents to support the application of the standards of quality assurance
with in ISO 9001
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. 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 60654-2:1979, Operating conditions for industrial-process measurement and control
equipment – Part 2: Power
Amendment 1:1992
IEC 60654-3:1983, Operating conditions for industrial-process measurement and control
equipment – Part 3: Mechanical influences
IEC 60825-1:2007, Safety of laser products – Part 1: Equipment classification and
requirements
IEC 61207-1:2010, Expression of performance of gas analyzers – Part 1: General

61207-7  IEC:2013 – 7 –
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
semiconductor laser
solid-state laser, in which the semiconductor material is used as active media
3.2
diode laser
semiconductor laser which is formed from a p-n junction and powered by injected electric
current
3.3
quantum cascade laser
semiconductor laser whose laser emission is achieved through the use of intersubband
transitions in a repeated stack of semiconductor multiple quantum structure, and typically
emits in the mid- to far-infrared portion of the electromagnetic spectrum
3.4
interband cascade laser
semiconductor laser whose laser emission is achieved through the use of interband
transitions between electrons and holes in a repeated stack of semiconductor multiple
quantum structure, but, instead of losing an electron to the valence band, the valence electron
can tunnel into the conduction band of the next quantum structure, and this process can be
repeated throughout the multiple quantum structure
3.5
extractive analyzer
analyzer which receives and analyzes a continuous stream of gas withdrawn from a process
by a sample handling system
3.6
in situ analyzer
analyzer which measures the gas in its original place, including across-duct, probe and open-
path types
3.7
tuneable semiconductor laser absorption spectroscopy
TSLAS
spectroscopy which utilizes a tuneable semiconductor laser as radiation source, tunes the
emission wavelength of the laser over the characteristic absorption lines of measured species
in the laser beam path, detects the reduction of the measured signal intensity, and then
determines the gas concentration
3.8
tuneable semiconductor laser gas analyzer
gas analyzer which utilizes TSLAS to measure the concentration of one or more gas
components in a gaseous mixture or vapour
3.9
wavelength modulation spectroscopy
laser gas absorption spectroscopy, in which the wavelength of the laser beam is continuously
modulated across the absorption line and the signal is detected at a harmonic of the
modulation frequency
Note 1 to entry: Wavelength modulation spectroscopy utilizes a modulation frequency which is less than the half-
width frequency of the transition lineshape.

– 8 – 61207-7  IEC:2013
3.10
frequency modulation spectroscopy
spectroscopy that uses a modulation frequency larger than the half-width frequency of the
transition lineshape which results in a pair of sidebands separated from the carrier by the
modulation frequency
Note 1 to entry: An alteration of any of the sidebands by absorption causes an unbalance and therefore a net
signal which can be detected by a high speed photodetector.
3.11
cavity enhanced absorption spectroscopy
spectroscopy which utilizes the resonance of laser beam in high-finesse optical cavity to
prolong the effective path lengths
3.12
photoacoustic spectroscopy
spectroscopy which is based on the photoacoustic effect
Note 1 to entry: The acoustic effect is the energy from the laser beam transformed into kinetic energy of the
absorbing gas molecules. This results in local heating and thus a pressure wave or sound. By measuring the sound
intensity, the gas concentration can be determined.
3.13
multi-pass absorption spectroscopy
absorption spectroscopy utilizing a multi-pass gas cell, in which the reflected laser beam
passes through the gas multi-times to increase optical path length
3.14
transmittance
ratio of incident light energy transmitted to the total light energy incident on a given sample
3.15
transmittance influence uncertainty
maximum difference between the indicated values of gas concentration when transmittance
assumes any value larger than the rated minimum transmittance, while all other values are at
reference conditions
EXAMPLE Transmittance is reduced by dust, liquid droplets, and other particles in the measured gas and the
pollution of optical windows.
3.16
purge
method using zero gas to blow parts of the analyzer during measurement or calibration to
prevent the optical components from staining or being coated, and to implement positive
pressure explosion protection, or to avoid interference from gases outside measured path
3.17
purged optical path length
length of optical path filled with purge gas
3.18
gas temperature
temperature of measured gases
EXAMPLE Temperature of gas in the duct for across-duct analyzers, temperature of gas in the probe cavity for
probe analyzers, ambient gas temperature in the open environment for open-path analyzers, gas temperature in
the gas cell for extractive analyzers.

61207-7  IEC:2013 – 9 –
3.19
gas pressure
pressure of measured gases
EXAMPLE The pressure in duct for across-duct and probe analyzers, ambient pressure of the open environment
for open-path analyzers, and the pressure in gas cell for extractive analyzers.
3.20
gas temperature influence uncertainty
maximum difference between the indicated values of gas concentration when the temperature
assumes any value within the rated range of gas temperature, all others being at reference
conditions
3.21
gas temperature influence uncertainty for calibration
maximum difference between the indicated values of gas concentration when the temperature
assumes any value within the rated range of calibration gas temperature, all others being at
reference conditions
3.22
gas pressure influence uncertainty
maximum difference between the indicated values of gas concentration when the pressure
assumes any value within the rated range of gas pressure, all others being at reference
conditions
3.23
gas pressure influence uncertainty for calibration
maximum difference between the indicated values of gas concentration when the pressure
assumes any value within the rated range of calibration gas pressure, all others being at
reference conditions
3.24
laser safety
safety design for use and implementation of lasers to minimise the risk of laser accidents,
especially those involving eye injuries
3.25
optical interference noise
interference fringes generated through multiple beam interferences between optical surfaces
within the coherent light source and the detector
Note 1 to entry: Interference fringes cause oscillation of the photocurrent during wavelength scanning. This
oscillation results in noise added to the absorption signal.
3.26
interfering components
components which interfere with the measurement of target species
Note 1 to entry: These interfering components include not only optically absorbing species by the fact that the
absorbance spectrum overlaps to the target species, but also non-optically absorbing species by line broadening of
the target species. (this can make stating/determining the measurement accuracy difficult).
Note 2 to entry: Namely, shape of optical absorbance spectrum of target species to be measured can be changed
itself significantly by change of background gas composition.

– 10 – 61207-7  IEC:2013
4 Procedure for specification
4.1 General
The procedures for specification are detailed in IEC 61207-1. This covers:
– operation and storage requirements;
– specification of ranges of measurement and output signals;
– limits of uncertainties;
– recommended reference values and rated ranges of influence quantities (see IEC 60654-1,
IEC 60654-2, IEC 60654-3).
In this standard, additional operation and service requirements are given. Additional terms for
specification of performance and important aspects of performance relevant to tuneable
semiconductor laser gas analyzers are also detailed.
4.2 In situ analyzers
4.2.1 Additional operation and maintenance requirements
4.2.1.1 Facilities and requirements for purge
The quality of purge gas such as dust and oil load, concentration limit of measured gas
component in the purge gas, and rated range of purge gas pressure and flow rate shall be
stated.
4.2.1.2 Facilities and methods for calibration or electronic and optical integrity
checking
The rated range of temperature, pressure and flow rate of calibration gas shall be stated.
The gas components and their corresponding concentration levels in calibration gas shall be
stated.
Facilities and procedures for optical aligning shall be stated.
4.2.1.3 Facilities and requirements for automatic compensation for gas temperature
or pressure variations
Specifications of required temperature or pressure sensors shall be stated.
4.2.1.4 Facilities and requirements for essential maintenance
Maintenance methods, facilities and the time intervals for maintenance shall be stated.
4.2.2 Additional terms related to the specification of performance
4.2.2.1 Rated minimum transmittance, above which the measurement uncertainty of the
analyzers is below the specified uncertainty limit, shall be stated.
4.2.2.2 Rated range of optical path length, which is required to ensure sufficient gas
absorption and transmittance.
4.2.2.3 Rated range of gas temperature, within which the measurement uncertainty of the
analyzers is below the specified uncertainty limit, shall be stated.

61207-7  IEC:2013 – 11 –
4.2.2.4 Rated range of gas pressure, within which the measurement uncertainty of the
analyzers is below the specified uncertainty limit, shall be stated.
4.2.2.5 Rated range of calibration gas temperature, within which the uncertainty of
calibration is below the specified uncertainty limit, shall be stated.
4.2.2.6 Rated range of calibration gas pressure, within which the uncertainty of calibration is
below the specified uncertainty limit, shall be stated.
4.2.2.7 Rated range of gas flow rate, within which the measurement uncertainty of the
analyzers is below the specified uncertainty limit, shall be stated.
4.2.2.8 Rated range of interfering components, within which the measurement uncertainty of
the analyzers is below the specified uncertainty limit, shall be stated.
NOTE The interfering components can normally include water vapour, carbon dioxide, nitric oxide, oxygen,
hydrogen chloride, carbon monoxide, etc.
4.2.2.9 Rated range of operating ambient temperature, within which the measurement
uncertainty of the analyzers is below the specified uncertainty limit, shall be stated.
4.2.2.10 Rated range of operating ambient pressure, within which the measurement
uncertainty of the analyzers is below the specified uncertainty limit, shall be stated.
4.2.3 Additional limits of uncertainties
4.2.3.1 Gas temperature influence uncertainty.
4.2.3.2 Gas temperature influence uncertainty for calibration.
4.2.3.3 Gas pressure influence uncertainty.
4.2.3.4 Gas pressure influence uncertainty for calibration.
4.2.3.5 Transmittance influence uncertainty.
4.3 Extractive analyzers
4.3.1 Additional operation and maintenance requirements
4.3.1.1 Facilities and requirements for purge
The quality of purge gas such as dust and oil load, concentration limit of measured gas
component in the purge gas, and rated range of purge gas pressure and flow rate shall be
stated.
4.3.1.2 Facilities and methods for calibration or electronic and optical integrity
checking
The rated range of temperature, pressure and flow rate of calibration gas shall be stated.
The gas components and their corresponding concentration levels in calibration gas shall be
stated.
4.3.1.3 Facilities and requirements for essential maintenance
Maintenance methods, facilities and the time intervals for maintenance shall be stated.

– 12 – 61207-7  IEC:2013
4.3.2 Additional terms related to the specification of performance
4.3.2.1 Rated minimum transmittance, above which the measurement uncertainty of the
analyzers is below the specified uncertainty limit, shall be stated.
4.3.2.2 Rated range of gas temperature, within which the measurement uncertainty of the
analyzers is below the specified uncertainty limit, shall be stated.
4.3.2.3 Rated range of gas pressure, within which the measurement uncertainty of the
analyzers is below the specified uncertainty limit, shall be stated.
4.3.2.4 Rated range of calibration gas temperature, within which the uncertainty of
calibration is below the specified uncertainty limit, shall be stated.
4.3.2.5 Rated range of calibration gas pressure, within which the uncertainty of calibration is
below the specified uncertainty limit, shall be stated.
4.3.2.6 Rated range of gas flow rate, within which the measurement uncertainty of the
analyzers is below the specified uncertainty limit, shall be stated.
4.3.2.7 Rated range of interfering components, within which the measurement uncertainty of
the analyzers is below the specified uncertainty limit, shall be stated.
NOTE The interfering components normally include water vapour, carbon dioxide, nitric oxide, oxygen, hydrogen
chloride, carbon monoxide, etc.
4.3.2.8 Rated range of operating ambient temperature, within which the measurement
uncertainty of the analyzers is below the specified uncertainty limit, shall be stated.
4.3.2.9 Rated range of operating ambient pressure, within which the measurement
uncertainty of the analyzers is below the specified uncertainty limit, shall be stated.
4.4 Recommended standard values and range of influence quantities
The rated ranges and use of influence quantities for climatic conditions, mechanical
conditions and main supply conditions shall be in accordance with those defined in
IEC 60654-1, IEC 60654-2, IEC 60654-3.
4.5 Laser safety
The laser classification of light source of analyzer shall be in accordance with those defined in
IEC 60825-1.
5 Procedures for compliance testing
5.1 In situ analyzers
5.1.1 General
For the verification of values specifying the performance see IEC 61207-1, together with the
following.
The tests considered in 5.1 apply to the complete analyzer as supplied by the manufacturer.
The analyzer will be set up in accordance with the instruction delivered by the manufacturer.

61207-7  IEC:2013 – 13 –
5.1.2 Apparatus to simulate measurement condition
The test apparatus for in situ analyzers (see Figure B.1) shall include mechanical components
required to present test gases to the measurement path at the appropriate temperature and
pressure. For across-duct or open-path analyzers an optical cell is required with transparent
wedged windows to minimise optical interference noise. This optical cell should be placed in
the uniform temperature region of furnace, and purge tubes are arranged between the
analyzer and the optical cell to avoid interference from air. For delay, rise and fall time
measurements, another gas cell filled with either zero or span gas is required. Purge tubes
and both cells should be of sufficient diameter to accommodate the analyzer beam width. For
probe type analyzers, the test apparatus may have a sealed end-cap for the probe, with
appropriate gas connections installed. This entire apparatus is then placed within a furnace
(see Figure B.2).
To simulate the measurement conditions, it is required that gas absorbance in test conditions
is comparable to that in measurement conditions. For example, when the pressure and
temperature are the same for measurement and test conditions, the cell length and the gas
concentration to be measured can be selected as follows:
X L ＝X L
a a t t
where
X is the maximum gas concentration in the measurement condition;
a
L is the optical path length in the measurement condition;
a
X is the gas concentration in gas cell;
t
L is the length of the optical cell.
t
5.1.3 Apparatus to generate test gas mixture
Test gas mixture can either use standard gas or gas generated by a test gas generator, which
requires at least two gas flow controllers to adjust the flow rates of standard and dilution
gases (see Figure B.3). The standard and dilution gases are mixed in a gas mixing device to
obtain uniform gas mixture. The concentration of the test component in the gas mixture can
be calculated as follows:
X＝X R /(R + R )
t s s s d
where
X is the concentration of the test component in the standard gas;
s
R is the flow rate of standard gas;
s
X is the concentration of the test component in the gas mixture;
t
R is the flow rate of dilution gas.
d
5.1.4 Apparatus to investigate the attenuation induced by opaque dust, liquid
droplets and other particles
Test equipment for in situ analyzers shall include an apparatus to investigate the attenuation
induced by dust, liquid droplets and other particles in optical path. Such an apparatus can be
a set of neutral density filters or grids with different transmittance to simulate the attenuation
induced by opaque dust, liquid droplets and other particles; each grid has square mesh holes
as illustrated in Figure B.5.
– 14 – 61207-7  IEC:2013
5.1.5 Testing procedures
5.1.5.1 General
The following relevant testing procedures are detailed in IEC 61207-1:
– intrinsic uncertainty;
– linearity uncertainty;
– repeatability;
– output fluctuation;
– warm-up time;
– variations (influence uncertainties);
– interference uncertainty.
Additional test details required for in situ tuneable semiconductor laser gas analyzers are
given below.
5.1.5.2 Drift
The test period should be chosen appropriately for the specific application from the following
values:
– 24 h;
– 7 days;
– 30 days;
– 3 months;
– 6 months;
– 1 year.
The readings may be corrected for temperature and pressure variations.
The test procedure detailed in 5.6.5 of IEC 61207-1:2010 is used except the following. Test
gas with appropriate stable concentration is applied to the analyzer until a stable indication is
given and at least 12 indicated values are recorded continuously, and then average value is
calculated. This procedure is carried out at the beginning and end of the specified test period,
and at a minimum of six, approximately evenly spread, time intervals within the test period.
The drift over the time period is the maximum difference of the calculated average values.
The readings of tuneable semiconductor laser gas analyzers may have periodical fluctuations
in hour scale, which is caused by optical interference noise and should be considered as part
of the drift. So the slope of linear regression of indicated values as specified in IEC 61207-1
cannot provide an accurate estimate of the drift.
5.1.5.3 Delay time, rise time and fall time
For across-duct and open-path analyzers, perform continuous measurement and wait until a
stable indication is given. Insert a gas cell filled with zero (span) gas into the light path (see
Figure B.1) and designate this moment as the start time of the step change for falling (rising)
delay time. When indicated values become stable, remove the gas cell from the light path and
designate this moment as the start time of the step change for rising (falling) delay time. The
measurement is continued until the indicated values become stable.

61207-7  IEC:2013 – 15 –
The values for delay time, rise time and fall time as defined in 3.5.13, 3.5.14 and 3.5.15 of
IEC 61207-1:2010 are determined from the recorded data, in conjunction with logged time
intervals (see Figure B.4).
The time interval of gas cell replacement shall be much shorter than the rise (fall) time of
analyzers.
NOTE The procedure for extractive (5.6.6 of IEC 61207-1:2010) analyzers is also applicable for in situ analyzers
as long as the gas exchange time is negligible against the response times of the analyzer.
5.1.5.4 Transmittance influence uncertainty
The analyzer is presented with a continued flow of test gas mixture giving a full scale or near
full scale indication. The indicated value is recorded until any change in reading is less than
or equal to the intrinsic uncertainty of the analyzer. Then sequentially insert the neutral
density filters or grids with rated minimum transmittance and at least three neutral density
filters or grids whose transmittances approximately evenly spread within the rated range of
transmittance into the optical path of analyzer (see Figure B.1), and the indicated values are
recorded correspondingly. This procedure shall be repeated at least three times, and the
averages of indicated reading for each test transmittance are calculated. The transmittance
influence uncertainty is the maximum difference of the calculated average values.
5.1.5.5 Gas temperature influence uncertainty
Control the temperature of the test gas to upper and lower limits of rated range of gas
temperature, and to a minimum of three, approximately evenly spread, temperatures within
the rated range of gas temperature, and control the pressure of the test gas to the middle of
rated range of gas pressure. The indicated values at each temperature are recorded. This
procedure is carried out at least three times and the averages of indicated values for each
test temperature are calculated. The gas temperature influence uncertainty is the maximum
difference of the calculated average values.
5.1.5.6 Gas temperature influence uncertainty for calibration
Control the temperature of the test gas to upper and lower limits of rated range of calibration
gas temperature, and to a minimum of three, approximately evenly spread, temperatures
within the rated range of calibration gas temperature, and control the pressure of test gas to
the middle of rated range of calibration gas pressure. The indicated values at each
temperature are recorded. This procedure is carried out at least three times and the averages
of indicated values for each test temperature are calculated. The gas temperature influence
uncertainty for calibration is the maximum difference of the calculated average values.
5.1.5.7 Gas pressure influence uncertainty
Control the pressure of the test gas to upper and lower limits of rated range of gas pressure,
and to a minimum of three, approximately evenly spread, pressures within the rated range of
gas pressure, and control the temperature of test gas to the middle of rated range of gas
temperature. The indicated values at each pressure are recorded. This procedure is carried
out at least three times and the averages of indicated values for each test pressure are
calculated. The gas pressure influence uncertainty is the maximum difference of the
calculated average values.
5.1.5.8 Gas pressure influence uncertainty for calibration
Control the pressure of the test gas to upper and lower limits of rated range of calibration gas
pressure, and to a minimum of three, approximately evenly spread, pressures within the rated
range of calibration gas pressure, and control the temperature of test gas to the middle of
rated range of calibration gas temperature. The indicated values at each pressure are
recorded. This procedure is carried out at least three times and the averages of indicated
reading for each pressure are calculated. The gas pressure influence uncertainty for
calibration is the maximum difference of the calculated average values.

– 16 – 61207-7  IEC:2013
5.2 Extractive analyzers
5.2.1 General
For the verification of values specifying the performance, see IEC 61207-1, together with the
following.
The tests considered in 5.2 apply to the complete analyzer as supplied by the manufacturer.
The analyzer will be set up in accordance with the instruction delivered by the manufacturer.
5.2.2 Apparatus to generate test gas mixture
Test gas mixture can either use standard gas or gas generated by a
...