oSIST ISO 7935:2025

Stationary source emissions - Determination of the mass concentration of sulfur dioxide in flue gases - Performance characteristics of automated measuring systems

This document specifies a method for the determination of sulfur dioxide (SO2) in flue gases of stationary sources and describes the fundamental structure and the key performance characteristics of automated measuring systems.
The method allows continuous monitoring with permanently installed measuring systems of SO2 emissions.
This document describes extractive systems and in situ (non-extractive) systems in connection with a range of analysers that operate using, for example, the following principles:
— non-dispersive infrared absorption (NDIR);
— Fourier transform infrared (FTIR) spectroscopy;
— laser spectroscopic technique or tunable laser spectroscopy (TLS);
— non-dispersive ultraviolet absorption (NDUV);
— differential optical absorption spectroscopy (DOAS).
Other equivalent instrumental methods can be used provided they meet the minimum performance requirements specified in this document. The measuring system can be validated with reference materials, according to this document, or comparable methods.
Automated measuring system (AMS) based on the principles listed above has been used successfully in this application for the measuring ranges as shown in Annex E.

Émissions de sources fixes - Détermination de la concentration en masse de dioxyde de soufre - Caractéristiques de performance des systèmes de mesurage automatiques

Emisije nepremičnih virov - Določanje masne koncentracije žveplovega dioksida v odpadnih plinih - Delovne karakteristike avtomatskih merilnih sistemov

General Information

• Status: Not Published
• Public Enquiry End Date: 02-Feb-2025
• ICS: 13.040.40 - Stationary source emissions
• Technical Committee: KAZ - Air quality
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 28-Nov-2024
• Due Date: 17-Apr-2025
• Ref Project: ISO 7935:2024 - Stationary source emissions — Determination of the mass concentration of sulfur dioxide in flue gases — Performance characteristics of automated measuring systems

Relations

• Revises: SIST ISO 7935:1996 - Stationary source emissions -- Determination of the mass concentration of sulfur dioxide -- Performance characteristics of automated measuring methods
• Effective Date: 01-Jan-2025

Standards Content (Sample)

International
Standard
ISO 7935
Second edition
Stationary source emissions —
2024-02
Determination of the mass
concentration of sulfur dioxide
in flue gases — Performance
characteristics of automated
measuring systems
Émissions de sources fixes — Détermination de la concentration
en masse de dioxyde de soufre — Caractéristiques de
performance des systèmes de mesurage automatiques
Reference number
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 4
4.1 Symbols .4
4.2 Abbreviated terms .5
5 Principle . 5
6 Description of the automated measuring systems . 5
6.1 Sampling and sample gas conditioning systems .5
6.2 Analyser equipment .6
7 Performance characteristics and criteria . 6
7.1 Performance criteria .6
7.2 Determination of the performance characteristics .7
7.2.1 Performance test .7
7.2.2 Ongoing quality control .7
8 Selection and installation procedure . 7
8.1 Choice of the measuring system .7
8.2 Sampling .8
8.2.1 Sampling location .8
8.2.2 Representative sampling .8
8.3 Calculation of conversion from volume to mass concentration for SO .8
9 Quality assurance and quality control procedures . 8
9.1 General .8
9.2 Frequency of checks.9
9.3 Calibration, validation and measurement uncertainty .9
10 Test report . 10
Annex A (informative) Extractive SO measurement systems .11
Annex B (informative) In situ SO measurement systems .20
Annex C (normative) Operational gases .24
Annex D (normative) Procedures for determination of the performance characteristics .25
Annex E (informative) Examples of the results for the assessment of SO AMS — SO
2 2
measurement .33
Annex F (informative) Calculation of uncertainty of measurement of SO .37
Bibliography .43

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 1, Stationary
source emissions.
This second edition cancels and replaces the first edition (ISO 7935:1992), which has been technically
revised.
The main changes are as follows:
— the structure and the components have been updated to be similar to the latest editions of e.g. ISO 10849
(measurement of nitrogen oxides), ISO 12039 (measurement of CO, CO and O ), ISO 17179 (measurement
2 2
of NH ), ISO 13199 (measurement of total VOC), ISO 25140 (measurement of CH ), ISO 21258 (measurement
3 4
of N O);
— Clause 3 has been revised with the addition or deletion and change in terms and definitions;
— a new analytical technique has been added (laser spectroscopic technique or tunable laser spectroscopy)
for measurement of SO ;
— the performance characteristics and criteria as well as QA/QC procedures have been changed to
harmonize with latest ISO standards;
— examples of performance test results and the results of uncertainty calculation have been added for SO
measurement.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
Sulfur dioxide (SO ) can arise in considerable quantities from combustion of fossil fuels used for energy
generation, industrial activities processing sulfur or sulfur containing material, and from combustion of
sulfur containing waste. The waste gas from these processes, containing sulfur dioxide, is usually discharged
into the ambient atmosphere, via a duct or a chimney.
For evaluating the mass concentration of sulfur dioxide present in the waste gas of stationary source
emissions, a number of highly developed methods of integrated sampling and subsequent determination by
chemical analysis and automated measuring systems are available.

v
International Standard ISO 7935:2024(en)
Stationary source emissions — Determination of the mass
concentration of sulfur dioxide in flue gases — Performance
characteristics of automated measuring systems
1 Scope
This document specifies a method for the determination of sulfur dioxide (SO ) in flue gases of stationary
sources and describes the fundamental structure and the key performance characteristics of automated
measuring systems.
The method allows continuous monitoring with permanently installed measuring systems of SO emissions.
This document describes extractive systems and in situ (non-extractive) systems in connection with a range
of analysers that operate using, for example, the following principles:
— non-dispersive infrared absorption (NDIR);
— Fourier transform infrared (FTIR) spectroscopy;
— laser spectroscopic technique or tunable laser spectroscopy (TLS);
— non-dispersive ultraviolet absorption (NDUV);
— differential optical absorption spectroscopy (DOAS).
Other equivalent instrumental methods can be used provided they meet the minimum performance
requirements specified in this document. The measuring system can be validated with reference materials,
according to this document, or comparable methods.
Automated measuring system (AMS) based on the principles listed above has been used successfully in this
application for the measuring ranges as shown in Annex E.
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.
ISO 9169, Air quality — Definition and determination of performance characteristics of an automatic measuring
system
ISO 14956, Air quality — Evaluation of the suitability of a measurement procedure by comparison with a
required measurement uncertainty
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IE
...

SLOVENSKI STANDARD
01-januar-2025
Emisije nepremičnih virov - Določanje masne koncentracije žveplovega dioksida v
odpadnih plinih - Delovne karakteristike avtomatskih merilnih sistemov
Stationary source emissions - Determination of the mass concentration of sulfur dioxide
in flue gases - Performance characteristics of automated measuring systems
Émissions de sources fixes - Détermination de la concentration en masse de dioxyde de
soufre - Caractéristiques de performance des systèmes de mesurage automatiques
Ta slovenski standard je istoveten z: ISO 7935:2024
ICS:
13.040.40 Emisije nepremičnih virov Stationary source emissions
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

International
Standard
ISO 7935
Second edition
Stationary source emissions —
2024-02
Determination of the mass
concentration of sulfur dioxide
in flue gases — Performance
characteristics of automated
measuring systems
Émissions de sources fixes — Détermination de la concentration
en masse de dioxyde de soufre — Caractéristiques de
performance des systèmes de mesurage automatiques
Reference number
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 4
4.1 Symbols .4
4.2 Abbreviated terms .5
5 Principle . 5
6 Description of the automated measuring systems . 5
6.1 Sampling and sample gas conditioning systems .5
6.2 Analyser equipment .6
7 Performance characteristics and criteria . 6
7.1 Performance criteria .6
7.2 Determination of the performance characteristics .7
7.2.1 Performance test .7
7.2.2 Ongoing quality control .7
8 Selection and installation procedure . 7
8.1 Choice of the measuring system .7
8.2 Sampling .8
8.2.1 Sampling location .8
8.2.2 Representative sampling .8
8.3 Calculation of conversion from volume to mass concentration for SO .8
9 Quality assurance and quality control procedures . 8
9.1 General .8
9.2 Frequency of checks.9
9.3 Calibration, validation and measurement uncertainty .9
10 Test report . 10
Annex A (informative) Extractive SO measurement systems .11
Annex B (informative) In situ SO measurement systems .20
Annex C (normative) Operational gases .24
Annex D (normative) Procedures for determination of the performance characteristics .25
Annex E (informative) Examples of the results for the assessment of SO AMS — SO
2 2
measurement .33
Annex F (informative) Calculation of uncertainty of measurement of SO .37
Bibliography .43

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 1, Stationary
source emissions.
This second edition cancels and replaces the first edition (ISO 7935:1992), which has been technically
revised.
The main changes are as follows:
— the structure and the components have been updated to be similar to the latest editions of e.g. ISO 10849
(measurement of nitrogen oxides), ISO 12039 (measurement of CO, CO and O ), ISO 17179 (measurement
2 2
of NH ), ISO 13199 (measurement of total VOC), ISO 25140 (measurement of CH ), ISO 21258 (measurement
3 4
of N O);
— Clause 3 has been revised with the addition or deletion and change in terms and definitions;
— a new analytical technique has been added (laser spectroscopic technique or tunable laser spectroscopy)
for measurement of SO ;
— the performance characteristics and criteria as well as QA/QC procedures have been changed to
harmonize with latest ISO standards;
— examples of performance test results and the results of uncertainty calculation have been added for SO
measurement.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
Sulfur dioxide (SO ) can arise in considerable quantities from combustion of fossil fuels used for energy
generation, industrial activities processing sulfur or sulfur containing material, and from combustion of
sulfur containing waste. The waste gas from these processes, containing sulfur dioxide, is usually discharged
into the ambient atmosphere, via a duct or a chimney.
For evaluating the mass concentration of sulfur dioxide present in the waste gas of stationary source
emissions, a number of highly developed methods of integrated sampling and subsequent determination by
chemical analysis and automated measuring systems are available.

v
International Standard ISO 7935:2024(en)
Stationary source emissions — Determination of the mass
concentration of sulfur dioxide in flue gases — Performance
characteristics of automated measuring systems
1 Scope
This document specifies a method for the determination of sulfur dioxide (SO ) in flue gases of stationary
sources and describes the fundamental structure and the key performance characteristics of automated
measuring systems.
The method allows continuous monitoring with permanently installed measuring systems of SO emissions.
This document describes extractive systems and in situ (non-extractive) systems in connection with a range
of analysers that operate using, for example, the following principles:
— non-dispersive infrared absorption (NDIR);
— Fourier transform infrared (FTIR) spectroscopy;
— laser spectroscopic technique or tunable laser spectroscopy (TLS);
— non-dispersive ultraviolet absorption (NDUV);
— differential optical absorption spectroscopy (DOAS).
Other equivalent instrumental methods can be used provided they meet the minimum performance
requirements specified in this document. The measuri
...