ISO/DTS 18222.3

Natural gas — Correlation between odorant concentration in air and odour intensity

This document describes how to establish the correlation between odorant concentration in air and odour intensity, usually presented in the form of odour intensity curves, following the odour intensity scale presented in Clause 5. This document does not fix a required level of odour intensity in the natural gas: this prescription is specified by local/national regulation.

Gaz naturel — Corrélation entre la concentration d’odorant dans l’air et l'intensité de l'odeur

General Information

• Status: Not Published
• ICS: 75.060 - Natural gas
• Technical Committee: ISO/TC 193 - Natural gas
• Drafting Committee: ISO/TC 193 - Natural gas
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 08-May-2025
• Completion Date: 08-May-2025

Standards Content (Sample)

FINAL DRAFT
Technical
Specification
ISO/TC 193
Natural gas — Correlation between
Secretariat: NEN
odorant concentration in air and
Voting begins on:
odour intensity
2025-05-08
Gaz naturel — Corrélation entre la concentration d’odorant dans
Voting terminates on:
l’air et l'intensité de l'odeur
2025-07-03
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
Technical
Specification
ISO/TC 193
Natural gas — Correlation between
Secretariat: NEN
odorant concentration in air and
Voting begins on:
odour intensity
Gaz naturel — Corrélation entre la concentration d’odorant dans
Voting terminates on:
l’air et l'intensité de l'odeur
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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 Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms .1
3.2 Specific definitions for the gas odorants .2
4 Principle . 3
5 Odour intensity scale . 3
6 Apparatus . 3
6.1 General .3
6.2 Test room .3
6.3 Dynamic olfactometer .3
6.4 Sample bag .4
7 Panel selection . 4
8 Sampling . 4
9 Safety precautions. 4
10 Environmental conditions . 4
11 Panel training and examination . . 4
12 Stimulus presentation . 5
13 Time between two presentations . 5
14 Expression of the results . 6
15 Precision of the method . 6
16 Uncertainty of the method . 7
16.1 Calculation of uncertainty .7
16.2 Uncertainty of the odour intensity corresponding to a stated concentration .7
16.3 Uncertainty of the concentration corresponding to a stated odour intensity .8
16.4 Numerical example of uncertainty calculations .9
17 Test report . 10
Bibliography .12

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 193, Natural gas.
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
The odour intensity of an odorant in air is generally determined by human sense of smell. The odour intensity
of odorants in air is determined by a group of specially trained persons who indicate in olfactory degrees
the amount of the sensorial perception.
This document describes a procedure of training using the specified odorant concentrations in order to
provide a common reference for determining odour intensity.

v
FINAL DRAFT Technical Specification ISO/DTS 18222.3:2025(en)
Natural gas — Correlation between odorant concentration in
air and odour intensity
1 Scope
This document describes how to establish the correlation between odorant concentration in air and odour
intensity, usually presented in the form of odour intensity curves, following the odour intensity scale
presented in Clause 5.
This document does not fix a required level of odour intensity in the natural gas: this prescription is specified
by local/national regulation.
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 5492:2008, Sensory analysis — Vocabulary
ISO 14532:2014, Natural gas — Vocabulary
EN 13725:2022, Stationary source emissions - Determination of odour concentration by dynamic olfactometry
and odour emission rate
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5492, ISO 14532 and the
following 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
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 General terms
3.1.1
odour intensity
strength of odour perception (3.1.2)
Note 1 to entry: According to the general law established by Weber, Fechner and Stevens, odour intensity is
proportional to the logarithm of the odorant concentration.
Note 2 to entry: In this document, odour intensity is expressed as the olfactory degree (see Table 1).
3.1.2
odour perception
awareness of the effect of volatile substances by the olfactory organ
[SOURCE: ISO 14532:2014, 2.8.3]

3.1.3
sensory fatigue
form of sensory adaption in which a decrease in sensitivity occurs
[SOURCE: ISO 5492:2008, 2.7]
3.1.4
terminal threshold
saturation threshold
minimum value of an intense sensory stimulus above which no difference in intensity can be perceived
[SOURCE: ISO 5492:2008, 2.28, modified — The admitted term "saturation threshold" has been added and
Note 1 to entry has been deleted.]
3.2 Specific definitions for the gas odorants
3.2.1
panel of smellers
group of persons (smellers) trained to recognize odour intensities
Note 1 to entry: In this document, the term “panel” is used instead of “panel of smellers”.
3.2.2
detection threshold
odorant concentration at which 50 % of the population detects with a probability of 0,5 under test conditions
...

ISO/TC 193
Secretariat: NEN
Date: 2025-05-07
Natural gas — Correlation between odorant concentration in air and
odour intensity
Gaz naturel — Corrélation entre la concentration d’odorant dans l’air et l'intensité de l'odeur

Formatted: Font: 11 pt
Formatted: Font: 11 pt
Formatted: Font: Bold
Formatted: HeaderCentered
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: + 41 22 749 01 11
E-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
Formatted: FooterPageRomanNumber
ii © ISO 2024 – All rights reserved
ii
Formatted: Font: 11 pt
Formatted: Font: 11 pt
Formatted: Font: Bold
Contents
Formatted: HeaderCentered, Left
Foreword . ivv
Introduction . vvi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 General terms . 1
3.2 Specific definitions for the gas odorants . 2
4 Principle . 3
5 Odour intensity scale . 3
6 Apparatus . 4
6.1 General . 4
6.2 Test room . 4
6.3 Dynamic olfactometer . 4
6.4 Sample bag . 4
7 Panel selection . 4
8 Sampling . 4
9 Safety precautions . 4
10 Environmental conditions . 4
11 Panel training and examination . 5
12 Stimulus presentation . 6
13 Time between two presentations . 6
14 Expression of the results . 7
15 Precision of the method . 7
16 Uncertainty of the method . 8
16.1 Calculation of uncertainty . 8
16.2 Uncertainty of the odour intensity corresponding to a stated concentration . 8
16.3 Uncertainty of the concentration corresponding to a stated odour intensity . 9
16.4 Numerical example of uncertainty calculations . 10
17 Test report . 12
Bibliography . 13

Formatted: FooterPageRomanNumber
iii
Formatted: Font: 11 pt
Formatted: Font: 11 pt
Formatted: Font: Bold
Foreword
Formatted: HeaderCentered
ISO (the International Organization for Standardization) is a worldwide federation of national standards Formatted: Adjust space between Latin and Asian text,
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through Adjust space between Asian text and numbers
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 documentsdocument 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).
Attention is drawnISO draws attention to the possibility that some of the elementsimplementation of this
document may beinvolve the subjectuse 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. Details of any patent rights identified during the development of the
document will be in the Introduction and/or on the ISO list of patent declarations received (see
www.iso.org/patents).
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 193, Natural gas.
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.
Formatted: FooterPageRomanNumber
iv © ISO 2024 – All rights reserved
iv
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Formatted: Font: 11 pt
Formatted: Font: Bold
Introduction
Formatted: HeaderCentered, Left
The odour intensity of an odorant in air is generally determined by human sense of smell. The odour intensity
of odorants in air is determined by a group of specially trained persons who indicate in olfactory degrees the
amount of the sensorial perception.
To provide a common reference for the odour intensity determination,This document describes a procedure
of training using the specified odorant concentrations is described in this documentin order to provide a
common reference for determining odour intensity.
Formatted: FooterPageRomanNumber
v
FINAL DRAFT TECHNICAL SPECIFICATION ISO/DTS 18222.3:2024(E)

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Natural gas — Correlation between odorant concentration in air
Latin and Asian text, Adjust space between Asian text
and numbers
and odour intensity
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1 Scope
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This document describes how to establish the correlation between odorant concentration in air and Adjust space between Asian text and numbers
odour intensity, usually presented in the form of odour intensity curves, following the odour intensity
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scale presented in Clause 5.
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This document does not fix a required level of odour intensity in the natural gas: this prescription is
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specified by local/national regulation.
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Formatted: Adjust space between Latin and Asian text,
2 Normative references
Adjust space between Asian text and numbers, Tab
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
The following documents are referred to in the text in such a way that some or all of their content
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
constitutes requirements of this document. For dated references, only the edition cited applies. For
Formatted: Default Paragraph Font
undated references, the latest edition of the referenced document (including any amendments) applies.
Formatted: Default Paragraph Font
ISO 5492:2008, Sensory analysis — Vocabulary
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ISO 14532:2014, Natural gas — Vocabulary
Formatted: Default Paragraph Font
Formatted: Default Paragraph Font
EN 13725:2022, Stationary source emissions - Determination of odour concentration by dynamic
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olfactometry and odour emission rate
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3 Terms and definitions
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Formatted: Adjust space between Latin and Asian text,
For the purposes of this document, the terms and definitions given in ISO 5492, ISO 14532 and the
Adjust space between Asian text and numbers
following apply.
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ISO and IEC maintain terminology databases for use in standardization at the following addresses:
Formatted: Default Paragraph Font
— — ISO Online browsing platform: available at https://www.iso.org/obp Formatted: Default Paragraph Font
Formatted: Default Paragraph Font
— — IEC Electropedia: available at https://www.electropedia.org/
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Adjust space between Asian text and numbers, Tab
3.1 General terms
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
3.1.1 3.1.1
odour intensity
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strength of odour perception (3.1.2)(3.1.2)
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stops: Not at 0.71 cm
Note 1 to entry: According to the general law established by Weber, Fechner and Stevens, the odour intensity is
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proportional to the logarithm of the odorant concentration.
Asian text, Adjust space between Asian text and
numbers
Note 2 to entry: Expressed inIn this document, odour intensity is expressed as the olfactory degree (see
Table 1).Table 1). Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers, Tab
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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3.1.2 3.1.2
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odour perception
awareness of the effect of volatile substances by the olfactory organ
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[SOURCE: ISO 14532:2014, 2.8.3]
Asian text, Adjust space between Asian text and
numbers
3.1.3 3.1.3
sensory fatigue Formatted: Default Paragraph Font
form of sensory adaption in which a decrease in sensitivity occurs
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[SOURCE: ISO 5492:2008, 2.7]
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3.1.4 3.1.4
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terminal threshold
saturation threshold Formatted: Default Paragraph Font
minimum value of an intense sensory stimulus above which no difference in intensity can be perceived
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[SOURCE: ISO 5492:2008, 2.28, modified — The admitted term "saturation threshold" has
...