Measurement of road tunnel air quality

This document describes methods for determining air speed and flow direction, CO, NO and NO2 concentrations and visibility in road tunnels using direct-reading instruments. This document specifically excludes requirements relating to instrument conformance testing.

Mesurage de la qualité de l'air du tunnel routier

Le présent document décrit des méthodes permettant de déterminer la vitesse et le sens d'écoulement de l'air, les concentrations en monoxyde de carbone (CO), en oxyde d'azote (NO) et en dioxyde d'azote (NO2), et la visibilité dans les tunnels routiers ŕ l'aide d'instruments ŕ lecture directe. Il exclut spécifiquement les exigences relatives aux essais de conformité des instruments.

Zunanji zrak - Merjenje kakovosti zraka v cestnih tunelih

General Information

Status
Published
Public Enquiry End Date
01-Mar-2021
Publication Date
15-Apr-2021
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Apr-2021
Due Date
06-Jun-2021
Completion Date
16-Apr-2021

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SLOVENSKI STANDARD
SIST ISO 23431:2021
01-maj-2021
Zunanji zrak - Merjenje kakovosti zraka v cestnih tunelih
Measurement of road tunnel air quality
Mesurage de la qualité de l'air du tunnel routier
Ta slovenski standard je istoveten z: ISO 23431:2021
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
93.060 Gradnja predorov Tunnel construction
SIST ISO 23431:2021 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST ISO 23431:2021
---------------------- Page: 2 ----------------------
SIST ISO 23431:2021
INTERNATIONAL ISO
STANDARD 23431
First edition
2021-03
Measurement of road tunnel air quality
Mesurage de la qualité de l'air d'un tunnel routier
Reference number
ISO 23431:2021(E)
ISO 2021
---------------------- Page: 3 ----------------------
SIST ISO 23431:2021
ISO 23431:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 23431:2021
ISO 23431:2021(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Test parameter — Air speed and flow direction .................................................................................................................. 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Principle ........................................................................................................................................................................................................ 3

4.3 Apparatus .................................................................................................................................................................................................... 4

4.3.1 Instrument ............................................................................................................................................................................ 4

4.3.2 Reference path length measurement device (open path instruments only) ............... 4

4.3.3 Transfer standard flow sensor ............................................................................................................................. 4

4.4 Procedure .................................................................................................................................................................................................... 4

4.5 Instrument checks and calibrations ..................................................................................................................................... 5

4.5.1 General...................................................................................................................................................................................... 5

4.5.2 Measurement path length (open path instruments only) ............................................................ 5

4.5.3 Initial check .......................................................................................................................................................................... 5

4.5.4 Cross-section calibration .......................................................................................................................................... 6

4.5.5 Zero check .............................................................................................................................................................................. 6

4.5.6 System component check ......................................................................................................................................... 6

4.5.7 Operational precision check .................................................................................................................................. 7

4.6 Maintenance .............................................................................................................................................................................................. 8

4.6.1 General...................................................................................................................................................................................... 8

4.6.2 On site checks ..................................................................................................................................................................... 8

4.7 Calculation and expression of results.................................................................................................................................. 8

4.8 Measurement uncertainty ............................................................................................................................................................. 9

5 Test parameters — Carbon monoxide, nitric oxide and nitrogen dioxide ...............................................9

5.1 General ........................................................................................................................................................................................................... 9

5.2 Principle ........................................................................................................................................................................................................ 9

5.3 Apparatus .................................................................................................................................................................................................10

5.3.1 Instrument .........................................................................................................................................................................10

5.3.2 Reference barometer .................................................................................................................................................11

5.3.3 Reference thermometer ..........................................................................................................................................11

5.3.4 Reference path length measurement device (for open path instruments only) ....11

5.3.5 Reference flow through calibration cell length measurement device (for

open path instruments only) ..............................................................................................................................11

5.4 Procedure .................................................................................................................................................................................................12

5.4.1 Open path instruments............................................................................................................................................12

5.4.2 Single point instruments ........................................................................................................................................12

5.5 Instrument checks and calibrations ..................................................................................................................................13

5.5.1 General...................................................................................................................................................................................13

5.5.2 Open path instruments............................................................................................................................................13

5.5.3 Single point instruments ........................................................................................................................................15

5.5.4 Measurement path length (for open path instruments only) ................................................15

5.5.5 Flow through calibration cell length (for open path instruments only) .......................15

5.5.6 Temperature and pressure checks ................................................................................................................15

5.5.7 Zero air ..................................................................................................................................................................................15

5.5.8 Reference test atmosphere ..................................................................................................................................16

5.5.9 Zero check ...........................................................................................................................................................................16

5.5.10 Zero calibration ..............................................................................................................................................................17

5.5.11 Span check ..........................................................................................................................................................................17

5.5.12 Span calibration .............................................................................................................................................................17

© ISO 2021 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 23431:2021
ISO 23431:2021(E)

5.5.13 Multipoint precision check ..................................................................................................................................18

5.5.14 System component check ......................................................................................................................................18

5.6 Maintenance ...........................................................................................................................................................................................19

5.6.1 General...................................................................................................................................................................................19

5.6.2 Cleaning of optical interfaces .............................................................................................................................19

5.6.3 Light source/electrochemical cell replacement ................................................................................19

5.6.4 Optical alignment .........................................................................................................................................................20

5.7 Calculation and expression of results...............................................................................................................................20

5.8 Measurement uncertainty ..........................................................................................................................................................20

6 Testing parameter — visibility ...........................................................................................................................................................21

6.1 General ........................................................................................................................................................................................................21

6.2 Principle .....................................................................................................................................................................................................21

6.3 Apparatus .................................................................................................................................................................................................22

6.3.1 Instrument .........................................................................................................................................................................22

6.3.2 Reference path length measurement device .................. .......................................................................23

6.4 Procedure .................................................................................................................................................................................................23

6.4.1 Transmissometer ..........................................................................................................................................................23

6.4.2 Scattered light instrument ....................................................................................................................................24

6.5 Instrument checks and calibrations ..................................................................................................................................24

6.5.1 General...................................................................................................................................................................................24

6.5.2 Zero check ...........................................................................................................................................................................25

6.5.3 Span check ..........................................................................................................................................................................25

6.5.4 Zero and span calibration .....................................................................................................................................25

6.5.5 Multipoint precision check ..................................................................................................................................26

6.5.6 System component check ......................................................................................................................................26

6.6 Maintenance ...........................................................................................................................................................................................27

6.6.1 General...................................................................................................................................................................................27

6.6.2 Cleaning of optical interfaces .............................................................................................................................27

6.6.3 Light source replacement ......................................................................................................................................27

6.6.4 Transmissometer optical alignment ............................................................................................................27

6.7 Calculation and expression of results...............................................................................................................................27

6.8 Measurement uncertainty ..........................................................................................................................................................28

7 Quality assurance and control.............................................................................................................................................................28

7.1 General ........................................................................................................................................................................................................28

7.2 Instrument log ......................................................................................................................................................................................28

7.3 Data acquisition and transfer ..................................................................................................................................................28

7.4 Data validation .....................................................................................................................................................................................28

8 Test report ................................................................................................................................................................................................................29

Bibliography .............................................................................................................................................................................................................................31

iv © ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 23431:2021
ISO 23431:2021(E)
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 documents 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 drawn to the possibility that some of the elements of this document may be the subject of

patent rights. 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 146, Air quality, Subcommittee SC 3,

Ambient atmospheres.

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.
© ISO 2021 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 23431:2021
ISO 23431:2021(E)
Introduction

The objective of this document is to provide road tunnel owners and operators with standard methods

for checking and calibrating instruments used in road tunnels to continuously monitor air speed,

carbon monoxide (CO), nitric oxide (NO) and nitrogen dioxide (NO ) concentrations and visibility.

Data from these instruments enables tunnel operators to manage the ventilation system in real time or

to take emergency measures (e.g. closure to traffic).

This document has been developed as a performance-based standard that allows for use of a number

of direct-reading instruments. Statements expressed in mandatory terms in notes to tables and figures

are deemed to be requirements of this document.

In order to improve traffic flow in central business districts and through sensitive environments, road

tunnels are increasingly used throughout the world to achieve the desired outcomes. There are a large

number of tunnels in operation, with a number of others in the planning stages.

Road tunnel projects are subject to environmental and/or planning approval conditions by regulatory

authorities that specify the parameters to be monitored in-tunnel, typically including air speed, CO, NO,

NO and visibility, with NO measured as a surrogate for NO , with, historically, 10 % of total nitrogen

2 2

oxides assumed to be NO . However, this assumption is no longer considered appropriate, given the

increased proportion of diesel fuelled vehicles in vehicle fleets. It can also be a requirement that the

tunnel ventilation system is controlled to:

a) reduce CO and NO concentrations within the tunnel environment to enable conformance with in-

tunnel air quality criteria for various averaging periods;
b) prevent or reduce portal emissions and resultant environmental impacts;
c) ensure appropriate visibility for different tunnel operating conditions; and

d) control smoke and improve the self-rescue time and security of tunnel users in emergency

situations such as fires.

Conformance with in-tunnel air quality criteria is typically determined by averaging measured CO and

measured or estimated NO concentrations from a number of instruments located on possible travel

paths throughout the tunnel system.

The number of instruments required to adequately characterise the tunnel environment is dependent

on a number of factors, including:
a) tunnel length and number of gradient changes and entry and exit ramps;
b) volume of traffic and types of vehicles;
c) exhaust ventilation system flowrate and control regime; and
d) regulatory requirements.

Consequently, this aspect is not addressed in this document. It is noted, however, that computational

fluid dynamics modelling can be used as a design tool to assist in the placement of instruments,

ensuring that indicative maximum and average concentrations are measured.
vi © ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
SIST ISO 23431:2021
INTERNATIONAL STANDARD ISO 23431:2021(E)
Measurement of road tunnel air quality
1 Scope

This document describes methods for determining air speed and flow direction, CO, NO and NO

concentrations and visibility in road tunnels using direct-reading instruments. This document

specifically excludes requirements relating to instrument conformance testing.
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 5802, Industrial fans — Performance testing in situ

ISO 6145, Gas analysis — Preparation of calibration gas mixtures using dynamic methods

ISO 10780, Stationary source emissions — Measurement of velocity and volume flowrate of gas streams

in ducts

ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in

me a s ur ement (GUM: 1995)

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
calibration

set of operations that establish, under specified conditions, the relationship between the value indicated

by a measuring instrument and the corresponding known value of a reference standard

3.2
certified reference material

reference material, characterized by a metrologically valid procedure for one or more specified

properties, accompanied by a reference material certificate that provides the value of the specified

property, its associated uncertainty, and a statement of metrological traceability

3.3
check
confirmation of acceptable instrument response, without adjustment
3.4
fall time

time interval, after a step decrease in input concentration, between initial instrument response and

10 % of initial instrument response
© ISO 2021 – All rights reserved 1
---------------------- Page: 9 ----------------------
SIST ISO 23431:2021
ISO 23431:2021(E)
3.5
full scale
nominated maximum concentration for which an instrument has been calibrated

Note 1 to entry: The full scale (FS) is selected to cover the normal range of values expected in the sampling

environment.
3.6
interference equivalent

positive or negative instrument response caused by a substance other than the one being measured

3.7
linearity

deviation of an instrument’s output from a linear best fit line when subjected to varying reference test

atmospheres
3.8
lower detectable limit

minimum pollutant concentration that produces a signal of exactly three times the repeatability

standard deviation
Note 1 to entry: See ISO 5725-1.
3.9
parameter
one of the characteristics related to an air sample

EXAMPLE Concentration of pollutant or other quantifiable property (e.g. air speed).

3.10
ppm
parts per million

ratio expressing the volume of gaseous pollutant contained in 1 000 000 volumes of atmosphere

Note 1 to entry: It may be expressed in terms of millilitres per cubic metre as the values are identical. Alternatively,

it is one million times the ratio of the partial pressure of gaseous pollutant to the pressure of the atmosphere in

which it is contained.
3.11
precision

variation about the mean of repeated measurements of the same pollutant concentration on the same

instrument, expressed as one standard deviation about the mean
3.12
range
nominal minimum and maximum concentrations that a method is capable of measuring

Note 1 to entry: The nominal range is specified by the lower and upper range limits in concentration units, e.g. 0

to 250 ppm.
3.13
reference test atmosphere

test atmosphere containing a known concentration of pollutant, typically generated by diluting the

contents of a cylinder containing a gaseous certified reference material (3.2)
3.14
rise time

time interval, after a step increase in input concentration, between the instrument initial response and

90 % of the final instrument response
2 © ISO 2021 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 23431:2021
ISO 23431:2021(E)
3.15
road tunnel

any fully enclosed length of roadway with a minimum length ranging between 90 m and 150 m

EXAMPLE National Fire Protection Association and UK Design Manual for Roads and Bridges.

3.16
span drift

percentage change in the instrument response to an on-scale pollutant concentration over a period of

continuous unadjusted operation
3.17

measurement of expanded uncertainty at a confidence interval of 95 % according to ISO/IEC Guide 98-3

3.18
zero air

air free from contaminants likely to cause a detectable response on the test instrument

3.19
zero drift

change in the instrument response to a zero-pollutant concentration over a period of continuous

unadjusted operation
4 Test parameter — Air speed and flow direction
4.1 General

Clause 4 describes continuous, direct-reading instruments for determining air speed and flow direction

in road tunnels. Providing the instrument performance is within the specifications given in Table 1,

alternate methods may be used within the context of this document.
4.2 Principle

Air speed and flow direction in modern road tunnels are typically measured using ultrasonic flow

sensors.

Ultrasonic sensor systems are based on the principle that the speed of air movement changes the transit

time of a sound pulse across a fixed distance, allowing calculation of the air speed and determination of

flow direction.

Instrument outputs may be used to control mechanical ventilation in a tunnel during both routine and

emergency operation.

The measurement of flow in road tunnels is important for emergency operation (e.g. vehicle fire),

enabling the control of air flow such that fumes are not dispersed in the tunne
...

INTERNATIONAL ISO
STANDARD 23431
First edition
2021-03
Measurement of road tunnel air quality
Mesurage de la qualité de l'air d'un tunnel routier
Reference number
ISO 23431:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 23431:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

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
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 23431:2021(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Test parameter — Air speed and flow direction .................................................................................................................. 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Principle ........................................................................................................................................................................................................ 3

4.3 Apparatus .................................................................................................................................................................................................... 4

4.3.1 Instrument ............................................................................................................................................................................ 4

4.3.2 Reference path length measurement device (open path instruments only) ............... 4

4.3.3 Transfer standard flow sensor ............................................................................................................................. 4

4.4 Procedure .................................................................................................................................................................................................... 4

4.5 Instrument checks and calibrations ..................................................................................................................................... 5

4.5.1 General...................................................................................................................................................................................... 5

4.5.2 Measurement path length (open path instruments only) ............................................................ 5

4.5.3 Initial check .......................................................................................................................................................................... 5

4.5.4 Cross-section calibration .......................................................................................................................................... 6

4.5.5 Zero check .............................................................................................................................................................................. 6

4.5.6 System component check ......................................................................................................................................... 6

4.5.7 Operational precision check .................................................................................................................................. 7

4.6 Maintenance .............................................................................................................................................................................................. 8

4.6.1 General...................................................................................................................................................................................... 8

4.6.2 On site checks ..................................................................................................................................................................... 8

4.7 Calculation and expression of results.................................................................................................................................. 8

4.8 Measurement uncertainty ............................................................................................................................................................. 9

5 Test parameters — Carbon monoxide, nitric oxide and nitrogen dioxide ...............................................9

5.1 General ........................................................................................................................................................................................................... 9

5.2 Principle ........................................................................................................................................................................................................ 9

5.3 Apparatus .................................................................................................................................................................................................10

5.3.1 Instrument .........................................................................................................................................................................10

5.3.2 Reference barometer .................................................................................................................................................11

5.3.3 Reference thermometer ..........................................................................................................................................11

5.3.4 Reference path length measurement device (for open path instruments only) ....11

5.3.5 Reference flow through calibration cell length measurement device (for

open path instruments only) ..............................................................................................................................11

5.4 Procedure .................................................................................................................................................................................................12

5.4.1 Open path instruments............................................................................................................................................12

5.4.2 Single point instruments ........................................................................................................................................12

5.5 Instrument checks and calibrations ..................................................................................................................................13

5.5.1 General...................................................................................................................................................................................13

5.5.2 Open path instruments............................................................................................................................................13

5.5.3 Single point instruments ........................................................................................................................................15

5.5.4 Measurement path length (for open path instruments only) ................................................15

5.5.5 Flow through calibration cell length (for open path instruments only) .......................15

5.5.6 Temperature and pressure checks ................................................................................................................15

5.5.7 Zero air ..................................................................................................................................................................................15

5.5.8 Reference test atmosphere ..................................................................................................................................16

5.5.9 Zero check ...........................................................................................................................................................................16

5.5.10 Zero calibration ..............................................................................................................................................................17

5.5.11 Span check ..........................................................................................................................................................................17

5.5.12 Span calibration .............................................................................................................................................................17

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 23431:2021(E)

5.5.13 Multipoint precision check ..................................................................................................................................18

5.5.14 System component check ......................................................................................................................................18

5.6 Maintenance ...........................................................................................................................................................................................19

5.6.1 General...................................................................................................................................................................................19

5.6.2 Cleaning of optical interfaces .............................................................................................................................19

5.6.3 Light source/electrochemical cell replacement ................................................................................19

5.6.4 Optical alignment .........................................................................................................................................................20

5.7 Calculation and expression of results...............................................................................................................................20

5.8 Measurement uncertainty ..........................................................................................................................................................20

6 Testing parameter — visibility ...........................................................................................................................................................21

6.1 General ........................................................................................................................................................................................................21

6.2 Principle .....................................................................................................................................................................................................21

6.3 Apparatus .................................................................................................................................................................................................22

6.3.1 Instrument .........................................................................................................................................................................22

6.3.2 Reference path length measurement device .................. .......................................................................23

6.4 Procedure .................................................................................................................................................................................................23

6.4.1 Transmissometer ..........................................................................................................................................................23

6.4.2 Scattered light instrument ....................................................................................................................................24

6.5 Instrument checks and calibrations ..................................................................................................................................24

6.5.1 General...................................................................................................................................................................................24

6.5.2 Zero check ...........................................................................................................................................................................25

6.5.3 Span check ..........................................................................................................................................................................25

6.5.4 Zero and span calibration .....................................................................................................................................25

6.5.5 Multipoint precision check ..................................................................................................................................26

6.5.6 System component check ......................................................................................................................................26

6.6 Maintenance ...........................................................................................................................................................................................27

6.6.1 General...................................................................................................................................................................................27

6.6.2 Cleaning of optical interfaces .............................................................................................................................27

6.6.3 Light source replacement ......................................................................................................................................27

6.6.4 Transmissometer optical alignment ............................................................................................................27

6.7 Calculation and expression of results...............................................................................................................................27

6.8 Measurement uncertainty ..........................................................................................................................................................28

7 Quality assurance and control.............................................................................................................................................................28

7.1 General ........................................................................................................................................................................................................28

7.2 Instrument log ......................................................................................................................................................................................28

7.3 Data acquisition and transfer ..................................................................................................................................................28

7.4 Data validation .....................................................................................................................................................................................28

8 Test report ................................................................................................................................................................................................................29

Bibliography .............................................................................................................................................................................................................................31

iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 23431:2021(E)
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 documents 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 drawn to the possibility that some of the elements of this document may be the subject of

patent rights. 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 146, Air quality, Subcommittee SC 3,

Ambient atmospheres.

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.
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 23431:2021(E)
Introduction

The objective of this document is to provide road tunnel owners and operators with standard methods

for checking and calibrating instruments used in road tunnels to continuously monitor air speed,

carbon monoxide (CO), nitric oxide (NO) and nitrogen dioxide (NO ) concentrations and visibility.

Data from these instruments enables tunnel operators to manage the ventilation system in real time or

to take emergency measures (e.g. closure to traffic).

This document has been developed as a performance-based standard that allows for use of a number

of direct-reading instruments. Statements expressed in mandatory terms in notes to tables and figures

are deemed to be requirements of this document.

In order to improve traffic flow in central business districts and through sensitive environments, road

tunnels are increasingly used throughout the world to achieve the desired outcomes. There are a large

number of tunnels in operation, with a number of others in the planning stages.

Road tunnel projects are subject to environmental and/or planning approval conditions by regulatory

authorities that specify the parameters to be monitored in-tunnel, typically including air speed, CO, NO,

NO and visibility, with NO measured as a surrogate for NO , with, historically, 10 % of total nitrogen

2 2

oxides assumed to be NO . However, this assumption is no longer considered appropriate, given the

increased proportion of diesel fuelled vehicles in vehicle fleets. It can also be a requirement that the

tunnel ventilation system is controlled to:

a) reduce CO and NO concentrations within the tunnel environment to enable conformance with in-

tunnel air quality criteria for various averaging periods;
b) prevent or reduce portal emissions and resultant environmental impacts;
c) ensure appropriate visibility for different tunnel operating conditions; and

d) control smoke and improve the self-rescue time and security of tunnel users in emergency

situations such as fires.

Conformance with in-tunnel air quality criteria is typically determined by averaging measured CO and

measured or estimated NO concentrations from a number of instruments located on possible travel

paths throughout the tunnel system.

The number of instruments required to adequately characterise the tunnel environment is dependent

on a number of factors, including:
a) tunnel length and number of gradient changes and entry and exit ramps;
b) volume of traffic and types of vehicles;
c) exhaust ventilation system flowrate and control regime; and
d) regulatory requirements.

Consequently, this aspect is not addressed in this document. It is noted, however, that computational

fluid dynamics modelling can be used as a design tool to assist in the placement of instruments,

ensuring that indicative maximum and average concentrations are measured.
vi © ISO 2021 – All rights reserved
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INTERNATIONAL STANDARD ISO 23431:2021(E)
Measurement of road tunnel air quality
1 Scope

This document describes methods for determining air speed and flow direction, CO, NO and NO

concentrations and visibility in road tunnels using direct-reading instruments. This document

specifically excludes requirements relating to instrument conformance testing.
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 5802, Industrial fans — Performance testing in situ

ISO 6145, Gas analysis — Preparation of calibration gas mixtures using dynamic methods

ISO 10780, Stationary source emissions — Measurement of velocity and volume flowrate of gas streams

in ducts

ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in

me a s ur ement (GUM: 1995)

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
calibration

set of operations that establish, under specified conditions, the relationship between the value indicated

by a measuring instrument and the corresponding known value of a reference standard

3.2
certified reference material

reference material, characterized by a metrologically valid procedure for one or more specified

properties, accompanied by a reference material certificate that provides the value of the specified

property, its associated uncertainty, and a statement of metrological traceability

3.3
check
confirmation of acceptable instrument response, without adjustment
3.4
fall time

time interval, after a step decrease in input concentration, between initial instrument response and

10 % of initial instrument response
© ISO 2021 – All rights reserved 1
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ISO 23431:2021(E)
3.5
full scale
nominated maximum concentration for which an instrument has been calibrated

Note 1 to entry: The full scale (FS) is selected to cover the normal range of values expected in the sampling

environment.
3.6
interference equivalent

positive or negative instrument response caused by a substance other than the one being measured

3.7
linearity

deviation of an instrument’s output from a linear best fit line when subjected to varying reference test

atmospheres
3.8
lower detectable limit

minimum pollutant concentration that produces a signal of exactly three times the repeatability

standard deviation
Note 1 to entry: See ISO 5725-1.
3.9
parameter
one of the characteristics related to an air sample

EXAMPLE Concentration of pollutant or other quantifiable property (e.g. air speed).

3.10
ppm
parts per million

ratio expressing the volume of gaseous pollutant contained in 1 000 000 volumes of atmosphere

Note 1 to entry: It may be expressed in terms of millilitres per cubic metre as the values are identical. Alternatively,

it is one million times the ratio of the partial pressure of gaseous pollutant to the pressure of the atmosphere in

which it is contained.
3.11
precision

variation about the mean of repeated measurements of the same pollutant concentration on the same

instrument, expressed as one standard deviation about the mean
3.12
range
nominal minimum and maximum concentrations that a method is capable of measuring

Note 1 to entry: The nominal range is specified by the lower and upper range limits in concentration units, e.g. 0

to 250 ppm.
3.13
reference test atmosphere

test atmosphere containing a known concentration of pollutant, typically generated by diluting the

contents of a cylinder containing a gaseous certified reference material (3.2)
3.14
rise time

time interval, after a step increase in input concentration, between the instrument initial response and

90 % of the final instrument response
2 © ISO 2021 – All rights reserved
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ISO 23431:2021(E)
3.15
road tunnel

any fully enclosed length of roadway with a minimum length ranging between 90 m and 150 m

EXAMPLE National Fire Protection Association and UK Design Manual for Roads and Bridges.

3.16
span drift

percentage change in the instrument response to an on-scale pollutant concentration over a period of

continuous unadjusted operation
3.17

measurement of expanded uncertainty at a confidence interval of 95 % according to ISO/IEC Guide 98-3

3.18
zero air

air free from contaminants likely to cause a detectable response on the test instrument

3.19
zero drift

change in the instrument response to a zero-pollutant concentration over a period of continuous

unadjusted operation
4 Test parameter — Air speed and flow direction
4.1 General

Clause 4 describes continuous, direct-reading instruments for determining air speed and flow direction

in road tunnels. Providing the instrument performance is within the specifications given in Table 1,

alternate methods may be used within the context of this document.
4.2 Principle

Air speed and flow direction in modern road tunnels are typically measured using ultrasonic flow

sensors.

Ultrasonic sensor systems are based on the principle that the speed of air movement changes the transit

time of a sound pulse across a fixed distance, allowing calculation of the air speed and determination of

flow direction.

Instrument outputs may be used to control mechanical ventilation in a tunnel during both routine and

emergency operation.

The measurement of flow in road tunnels is important for emergency operation (e.g. vehicle fire),

enabling the control of air flow such that fumes are not dispersed in the tunnel tube. The choice of cross

section or single point air flow measurements for this purpose is dependent on local technical practices.

Air flow measurement can also be important for the management of mechanical ventilation, either to

dilute pollutants, or to control the atmospheric discharges at the portals.

Ultrasonic sensors are either open path or single point instruments, installed at various locations along

the tunnel length, including portals and exit ramps.

Open path ultrasonic flow sensors measure the average value over the tunnel width, with transceiver

pairs installed on opposing walls at an angle of 45° to 60° to the tunnel axis. In order to eliminate

potential measurement errors caused by variations in ultrasonic sound speed due to temperature and

pressure, the transceiver unit
...

NORME ISO
INTERNATIONALE 23431
Première édition
2021-03
Mesurage de la qualité de l'air d'un
tunnel routier
Measurement of road tunnel air quality
Numéro de référence
ISO 23431:2021(F)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 23431:2021(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2021

Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, 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, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut

être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.

ISO copyright office
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Web: www.iso.org
Publié en Suisse
ii © ISO 2021 – Tous droits réservés
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ISO 23431:2021(F)
Sommaire Page

Avant-propos ................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Domaine d’application ................................................................................................................................................................................... 1

2 Références normatives ................................................................................................................................................................................... 1

3 Termes et définitions ....................................................................................................................................................................................... 1

4 Paramètre d’essai — Vitesse et sens du courant d’air ................................................................................................... 3

4.1 Généralités .................................................................................................................................................................................................. 3

4.2 Principe ......................................................................................................................................................................................................... 3

4.3 Appareillage............................................................................................................................................................................................... 4

4.3.1 Instrument ............................................................................................................................................................................ 4

4.3.2 Dispositif de mesure de référence de la longueur du trajet (instruments à

trajet ouvert uniquement) ....................................................................................................................................... 4

4.3.3 Capteur de débit étalon de transfert ............................................................................................................... 5

4.4 Mode opératoire .................................................................................................................................................................................... 5

4.5 Contrôles et étalonnages des instruments ...................................................................................................................... 5

4.5.1 Généralités ............................................................................................................................................................................ 5

4.5.2 Longueur du trajet de mesure (instruments à trajet ouvert uniquement) ................... 6

4.5.3 Contrôle initial ................................................................................................................................................................... 6

4.5.4 Étalonnage de section ........................................................................................................................................... ....... 6

4.5.5 Contrôle du zéro ............................................................................................................................................................... 7

4.5.6 Contrôle des composants du système ........................................................................................................... 7

4.5.7 Contrôle fonctionnel de la précision ............................................................................................................... 7

4.6 Maintenance .............................................................................................................................................................................................. 8

4.6.1 Généralités ............................................................................................................................................................................ 8

4.6.2 Contrôles sur site ............................................................................................................................................................. 9

4.7 Calcul et expression des résultats .......................................................................................................................................... 9

4.8 Incertitude de mesure ...................................................................................................................................................................... 9

5 Paramètres d’essai — Monoxyde de carbone, oxyde d’azote et dioxyde d’azote ............................10

5.1 Généralités ...............................................................................................................................................................................................10

5.2 Principe ......................................................................................................................................................................................................10

5.3 Appareillage............................................................................................................................................................................................11

5.3.1 Instrument .........................................................................................................................................................................11

5.3.2 Baromètre de référence ..........................................................................................................................................12

5.3.3 Thermomètre de référence ..................................................................................................................................12

5.3.4 Dispositif de mesure de référence de la longueur du trajet (pour les

instruments à trajet ouvert uniquement) ...............................................................................................12

5.3.5 Dispositif de mesure de référence de la longueur du trajet de la cellule
d’étalonnage à débit continu (pour les instruments à trajet ouvert

uniquement) .....................................................................................................................................................................12

5.4 Mode opératoire .................................................................................................................................................................................13

5.4.1 Instruments de mesure à trajet ouvert ......................................................................................................13

5.4.2 Instruments de mesure en un seul point .................................................................................................14

5.5 Contrôles et étalonnages des instruments ...................................................................................................................14

5.5.1 Généralités .........................................................................................................................................................................14

5.5.2 Instruments de mesure à trajet ouvert ......................................................................................................14

5.5.3 Instruments de mesure en un seul point .................................................................................................16

5.5.4 Longueur du trajet de mesure (pour les instruments à trajet ouvert

uniquement) .....................................................................................................................................................................16

5.5.5 Longueur de référence de la cellule d’étalonnage à débit continu (pour les

instruments à trajet ouvert uniquement) ...............................................................................................16

5.5.6 Contrôles de la température et de la pression ....................................................................................17

5.5.7 Air de zéro ..........................................................................................................................................................................17

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ISO 23431:2021(F)

5.5.8 Atmosphère d’essai de référence ....................................................................................................................17

5.5.9 Contrôle du zéro ............................................................................................................................................................17

5.5.10 Étalonnage du zéro .....................................................................................................................................................18

5.5.11 Contrôle du point d’échelle ..................................................................................................................................18

5.5.12 Étalonnage du point d’échelle ...........................................................................................................................19

5.5.13 Contrôle de précision multipoint....................................................................................................................19

5.5.14 Contrôle des composants du système ........................................................................................................20

5.6 Maintenance ...........................................................................................................................................................................................21

5.6.1 Généralités .........................................................................................................................................................................21

5.6.2 Nettoyage des interfaces optiques .................................................................................................................21

5.6.3 Remplacement de la source lumineuse/d’une cellule électrochimique .......................21

5.6.4 Alignement optique ....................................................................................................................................................21

5.7 Calcul et expression des résultats .......................................................................................................................................22

5.8 Incertitude de mesure ...................................................................................................................................................................22

6 Paramètre d’essai — Visibilité ............................................................................................................................................................22

6.1 Généralités ...............................................................................................................................................................................................22

6.2 Principe ......................................................................................................................................................................................................23

6.3 Appareillage............................................................................................................................................................................................24

6.3.1 Instrument .........................................................................................................................................................................24

6.3.2 Dispositif de mesure de référence de la longueur du trajet ....................................................25

6.4 Mode opératoire .................................................................................................................................................................................25

6.4.1 Transmissomètre ..........................................................................................................................................................25

6.4.2 Instrument de diffusion de la lumière ........................................................................................................26

6.5 Contrôles et étalonnages des instruments ...................................................................................................................26

6.5.1 Généralités .........................................................................................................................................................................26

6.5.2 Contrôle du zéro ............................................................................................................................................................27

6.5.3 Contrôle du point d’échelle ..................................................................................................................................27

6.5.4 Étalonnage du zéro et du point d’échelle.................................................................................................28

6.5.5 Contrôle de précision multipoint....................................................................................................................28

6.5.6 Contrôle des composants du système ........................................................................................................28

6.6 Maintenance ...........................................................................................................................................................................................29

6.6.1 Généralités .........................................................................................................................................................................29

6.6.2 Nettoyage des interfaces optiques .................................................................................................................29

6.6.3 Remplacement de la source lumineuse .....................................................................................................29

6.6.4 Alignement optique du transmissomètre ...............................................................................................29

6.7 Calcul et expression des résultats .......................................................................................................................................30

6.8 Incertitude de mesure ...................................................................................................................................................................30

7 Contrôle et assurance de la qualité ................................................................................................................................................30

7.1 Généralités ...............................................................................................................................................................................................30

7.2 Journal d’instrument .......................................................................................................................................................................30

7.3 Acquisition et transfert des données ................................................................................................................................31

7.4 Validation des données .................................................................................................................................................................31

8 Rapport d’essai ....................................................................................................................................................................................................32

Bibliographie ...........................................................................................................................................................................................................................33

iv © ISO 2021 – Tous droits réservés
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ISO 23431:2021(F)
Avant-propos

L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes

nationaux de normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est

en général confiée aux comités techniques de l'ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l'ISO participent également aux travaux.

L'ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier, de prendre note des différents

critères d'approbation requis pour les différents types de documents ISO. Le présent document a été

rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www

.iso .org/ directives).

L'attention est attirée sur le fait que certains des éléments du présent document peuvent faire l'objet de

droits de propriété intellectuelle ou de droits analogues. L'ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l'élaboration du document sont indiqués dans l'Introduction et/ou dans la liste des déclarations de

brevets reçues par l'ISO (voir www .iso .org/ brevets).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un

engagement.

Pour une explication de la nature volontaire des normes, la signification des termes et expressions

spécifiques de l'ISO liés à l'évaluation de la conformité, ou pour toute information au sujet de l'adhésion

de l'ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles

techniques au commerce (OTC), voir www .iso .org/ avant -propos.

Le présent document a été élaboré par le Comité technique ISO/TC 146, Qualité de l’air, sous-comité

SC 3, Atmosphères ambiantes.

Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent

document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes

se trouve à l’adresse www .iso .org/ fr/ members .html.
© ISO 2021 – Tous droits réservés v
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ISO 23431:2021(F)
Introduction

L’objectif du présent document est de fournir aux maîtres d’ouvrage et exploitants de tunnels routiers

des méthodes normalisées pour la vérification et l’étalonnage des instruments utilisés dans les tunnels

routiers afin de surveiller en continu la vitesse de l’air, les concentrations en monoxyde de carbone (CO),

en oxyde d’azote (NO) et en dioxyde d’azote (NO ) ainsi que la visibilité.

Les données de ces instruments permettent aux exploitants de tunnels de piloter le système de

ventilation en temps réel ou de prendre des mesures d’urgence (par exemple, fermeture à la circulation).

Le présent document a été élaboré comme une norme fondée sur les performances permettant

l’utilisation d’un certain nombre d’instruments à lecture directe. Les énoncés exprimés en termes

obligatoires dans les notes aux tableaux et aux figures sont réputés être des exigences du présent

document.

Afin d’améliorer le débit de circulation dans les grands centres d’affaires et dans les environnements

sensibles, les tunnels routiers sont de plus en plus utilisés dans le monde entier pour atteindre les

résultats escomptés. Il existe un grand nombre de tunnels en service et plusieurs autres sont à l’étude.

Les projets de tunnels routiers sont soumis à validation sur des critères environnementaux et/ou

d’aménagement par les autorités réglementaires qui spécifient les paramètres à surveiller dans le

tunnel, lesquels incluent généralement la vitesse de l’air, le CO, le NO, le NO et la visibilité, le NO étant

mesuré comme valeur de substitution au NO , en se basant sur le ratio historique de 10 % des oxydes

d’azote totaux qui sont du NO . Toutefois, cette hypothèse n’est plus considérée comme appropriée

compte tenu de la proportion accrue de véhicules à moteur diesel dans les parcs automobiles. Il peut

également être exigé que le système de ventilation du tunnel soit contrôlé de sorte à:

a) réduire les concentrations en CO et en NO à l’intérieur du tunnel afin de respecter les critères de

qualité de l’air à l’intérieur du tunnel pour diverses périodes de calcul de moyennes;

b) prévenir ou réduire les émissions au niveau des têtes de tunnel et les impacts environnementaux

qui en résultent;

c) assurer une visibilité adéquate pour les différentes conditions d’exploitation du tunnel;

d) contrôler les fumées et améliorer le temps d’auto-évacuation et la sécurité des usagers du tunnel

dans les situations d’urgence telles que les incendies.

La conformité avec les critères de qualité de l’air à l’intérieur du tunnel est généralement déterminée

en calculant la moyenne des concentrations en CO et en NO mesurées ou estimées à l’aide d’un certain

nombre d’instruments placés le long de chaque tube de l’ouvrage.

Le nombre d’instruments requis pour surveiller correctement la qualité de l’air du tunnel dépend d’un

certain nombre de facteurs, incluant:

a) la longueur du tunnel ainsi que le nombre de changements de déclivité et de bretelles d’entrée et

de sortie;
b) la densité du trafic et les types de véhicules;

c) le débit et le régime de contrôle du système de ventilation pour gérer les fumées ou l’air vicié;

d) les exigences réglementaires.

Par conséquent, cet aspect n’est pas abordé dans le présent document. Il convient toutefois de noter que

la modélisation numérique de la mécanique des fluides peut être utilisée comme outil de conception

pour aider à la mise en place des instruments, en garantissant que les concentrations maximales et

moyennes indicatives sont mesurées.
vi © ISO 2021 – Tous droits réservés
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NORME INTERNATIONALE ISO 23431:2021(F)
Mesurage de la qualité de l'air d'un tunnel routier
1 Domaine d’application

Le présent document décrit des méthodes permettant de déterminer la vitesse et le sens d’écoulement

de l’air, les concentrations en monoxyde de carbone (CO), en oxyde d’azote (NO) et en dioxyde d’azote

(NO ), et la visibilité dans les tunnels routiers à l’aide d’instruments à lecture directe. Il exclut

spécifiquement les exigences relatives aux essais de conformité des instruments.
2 Références normatives

Les documents suivants sont cités dans le texte de sorte qu’ils constituent, pour tout ou partie de leur

contenu, des exigences du présent document. Pour les références datées, seule l’édition citée s’applique.

Pour les références non datées, la dernière édition du document de référence s'applique (y compris les

éventuels amendements).
ISO 5802, Ventilateurs industriels — Essai de performance in situ

ISO 6145, Analyse des gaz — Préparation des mélanges de gaz pour étalonnage à l'aide de méthodes

dynamiques

ISO 10780, Émissions de sources fixes — Mesurage de la vitesse et du débit-volume des courants gazeux

dans des conduites

Guide ISO/IEC 98-3, Incertitude de mesure — Partie 3: Guide pour l’expression de l’incertitude de mesure

(GUM: 1995)

ISO/IEC 17025, Exigences générales concernant la compétence des laboratoires d'étalonnages et d'essais

3 Termes et définitions

Pour les besoins du présent document, les termes et définitions suivants s’appliquent.

L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en

normalisation, consultables aux adresses suivantes:

— ISO Online browsing platform: disponible à l’adresse https:// www .iso .org/ obp

— IEC Electropedia: disponible à l’adresse http:// www .electropedia .org/
3.1
étalonnage

ensemble des opérations permettant d’établir, dans des conditions spécifiées, les rapports existant

entre la valeur indiquée par un instrument de mesure et la valeur connue correspondante d’un étalon

de référence
3.2
matériau de référence certifié

matériau de référence caractérisé par un mode opératoire métrologiquement valide applicable

à une ou plusieurs propriétés spécifiées et accompagné d’un certificat de matériau de référence qui

indique la valeur de la propriété spécifiée, son incertitude associée, et une expression de la traçabilité

métrologique
© ISO 2021 – Tous droits réservés 1
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ISO 23431:2021(F)
3.3
contrôle
confirmation de la réponse acceptable d’un instrument, sans réglage
3.4
temps de descente

intervalle de temps entre la réponse initiale de l’instrument et 10 % de la réponse initiale de

l’instrument, après une diminution progressive de la concentration d’entrée
3.5
pleine échelle
concentration maximale désignée pour laquelle un instrument a été étalonné

Note 1 à l'article: La pleine échelle (PE) est sélectionnée de sorte à couvrir la plage normale des valeurs attendues

dans l’environnement de prélèvement.
3.6
équivalent d’interférence

réponse positive ou négative de l’instrument induite par une substance autre que celle mesurée

3.7
linéarité

divergence du relevé d’un instrument par rapport à une ligne d’ajustement linéaire optimal lorsque

celui-ci est soumis à des atmosphères d’essai de référence variables
3.8
limite inférieure de détection

concentration minimale en polluant qui produit un signal d’exactement trois fois l’écart-type de

répétabilité
Note 1 à l'article: Voir l’ISO 5725-1.
3.9
paramètre
une des caractéristiques liées à un échantillon d’air

EXEMPLE Concentration en polluant ou autres valeurs quantifiables (par exemple, la vitesse de l’air).

3.10
ppm
parties par million

rapport exprimant le volume de polluant gazeux contenu dans 1 000 000 volumes d’atmosphère

Note 1 à l'article: et pouvant être exprimé en millilitres par mètre cube, les valeurs étant identiques. En variante,

ce rapport est égal à un million de fois le rapport entre la pression partielle du polluant gazeux et la pression de

l’atmosphère dans laquelle il est contenu.
3.11
fidélité

variation autour de la moyenne des mesures obtenues par mesurages répétés de la même concentration

en polluant avec le même instrument, exprimée sous la forme d’un écart-type autour de la moyenne

3.12
plage

concentrations minimale et maximale nominales qu’une méthode est capable de mesurer

Note 1 à l'article: La plage nominale est spécifiée par les limites inférieure et supérieure de la plage en unités de

concentration, par exemple 0 ppm à 250 ppm.
2 © ISO 2021 – Tous droits réservés
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ISO 23431:2021(F)
3.13
atmosphère d’essai de référence

atmosphère d’essai contenant une concentration connue en polluant, généralement créée par la dilution

du contenu d’une bouteille contenant un matériau de référence certifié (3.2) gazeux

3.14
temps de montée

intervalle de temps entre la réponse initiale de l’instrument et 90 % de la réponse finale de l’instrument,

après une augmentation progressive de la concentration d’entrée
3.15
tunnel routier

toute longueur de route entièrement confinée d’une longueur minimale comprise entre 90 m et 150 m

EXEMPLE National Fire protection Association et UK Design Manual for Roads and Bridges.

3.16
dérive au point d’échelle

variation, en pourcentage, de la réponse d’un instrument à une concentration en polluant à l’échelle sur

une période d’exploitation en continu non ajustée
3.17

mesurage de l’incertitude élargie à un intervalle de confiance de 95 % conformément au

Guide ISO/IEC 98-3
3.18
air de zéro

air exempt de contaminants susceptibles d’induire une réponse détectable sur l’instrument d’essai

3.19
dérive au zéro
variation de la réponse
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23431
ISO/TC 146/SC 3
Measurement of road tunnel air quality
Secretariat: ANSI
Voting begins on: Mesurage de la qualité de l'air du tunnel routier
2020­12­10
Voting terminates on:
2021­02­04
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
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 23431:2020(E)
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. ISO 2020
---------------------- Page: 1 ----------------------
ISO/FDIS 23431:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 23431:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Test parameter — Air speed and flow direction .................................................................................................................. 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Principle ........................................................................................................................................................................................................ 3

4.3 Apparatus .................................................................................................................................................................................................... 4

4.3.1 Instrument ............................................................................................................................................................................ 4

4.3.2 Reference path length measurement device (open path instruments only) ............... 4

4.3.3 Transfer standard flow sensor ............................................................................................................................. 4

4.4 Procedure .................................................................................................................................................................................................... 4

4.5 Instrument checks and calibrations ..................................................................................................................................... 5

4.5.1 General...................................................................................................................................................................................... 5

4.5.2 Measurement path length (open path instruments only) ............................................................ 5

4.5.3 Initial check .......................................................................................................................................................................... 5

4.5.4 Cross­section calibration .......................................................................................................................................... 6

4.5.5 Zero check .............................................................................................................................................................................. 6

4.5.6 System component check ......................................................................................................................................... 6

4.5.7 Operational precision check .................................................................................................................................. 7

4.6 Maintenance .............................................................................................................................................................................................. 8

4.6.1 General...................................................................................................................................................................................... 8

4.6.2 On site checks ..................................................................................................................................................................... 8

4.7 Calculation and expression of results.................................................................................................................................. 8

4.8 Measurement uncertainty ............................................................................................................................................................. 9

5 Test parameters — Carbon monoxide, nitric oxide and nitrogen dioxide ...............................................9

5.1 General ........................................................................................................................................................................................................... 9

5.2 Principle ........................................................................................................................................................................................................ 9

5.3 Apparatus .................................................................................................................................................................................................10

5.3.1 Instrument .........................................................................................................................................................................10

5.3.2 Reference barometer .................................................................................................................................................11

5.3.3 Reference thermometer ..........................................................................................................................................11

5.3.4 Reference path length measurement device (for open path instruments only) ....11

5.3.5 Reference flow through calibration cell length measurement device (for

open path instruments only) ..............................................................................................................................11

5.4 Procedure .................................................................................................................................................................................................12

5.4.1 Open path instruments............................................................................................................................................12

5.4.2 Single point instruments ........................................................................................................................................12

5.5 Instrument checks and calibrations ..................................................................................................................................13

5.5.1 General...................................................................................................................................................................................13

5.5.2 Open path instruments............................................................................................................................................13

5.5.3 Single point instruments ........................................................................................................................................14

5.5.4 Measurement path length (for open path instruments only) ................................................15

5.5.5 Flow through calibration cell length (for open path instruments only) .......................15

5.5.6 Temperature and pressure checks ................................................................................................................15

5.5.7 Zero air ..................................................................................................................................................................................15

5.5.8 Reference test atmosphere ..................................................................................................................................15

5.5.9 Zero check ...........................................................................................................................................................................16

5.5.10 Zero calibration ..............................................................................................................................................................16

5.5.11 Span check ..........................................................................................................................................................................17

5.5.12 Span calibration .............................................................................................................................................................17

© ISO 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 23431:2020(E)

5.5.13 Multipoint precision check ..................................................................................................................................18

5.5.14 System component check ......................................................................................................................................18

5.6 Maintenance ...........................................................................................................................................................................................19

5.6.1 General...................................................................................................................................................................................19

5.6.2 Cleaning of optical interfaces .............................................................................................................................19

5.6.3 Light source/electrochemical cell replacement ................................................................................19

5.6.4 Optical alignment .........................................................................................................................................................19

5.7 Calculation and expression of results...............................................................................................................................20

5.8 Measurement uncertainty ..........................................................................................................................................................20

6 Testing parameter — visibility ...........................................................................................................................................................20

6.1 General ........................................................................................................................................................................................................20

6.2 Principle .....................................................................................................................................................................................................21

6.3 Apparatus .................................................................................................................................................................................................22

6.3.1 Instrument .........................................................................................................................................................................22

6.3.2 Reference path length measurement device .................. .......................................................................23

6.4 Procedure .................................................................................................................................................................................................23

6.4.1 Transmissometer ..........................................................................................................................................................23

6.4.2 Scattered light instrument ....................................................................................................................................24

6.5 Instrument checks and calibrations ..................................................................................................................................24

6.5.1 General...................................................................................................................................................................................24

6.5.2 Zero check ...........................................................................................................................................................................25

6.5.3 Span check ..........................................................................................................................................................................25

6.5.4 Zero and span calibration .....................................................................................................................................25

6.5.5 Multipoint precision check ..................................................................................................................................25

6.5.6 System component check ......................................................................................................................................26

6.6 Maintenance ...........................................................................................................................................................................................26

6.6.1 General...................................................................................................................................................................................26

6.6.2 Cleaning of optical interfaces .............................................................................................................................27

6.6.3 Light source replacement ......................................................................................................................................27

6.6.4 Transmissometer optical alignment ............................................................................................................27

6.7 Calculation and expression of results...............................................................................................................................27

6.8 Measurement uncertainty ..........................................................................................................................................................27

7 Quality assurance and control.............................................................................................................................................................28

7.1 General ........................................................................................................................................................................................................28

7.2 Instrument log ......................................................................................................................................................................................28

7.3 Data acquisition and transfer ..................................................................................................................................................28

7.4 Data validation .....................................................................................................................................................................................28

8 Test report ................................................................................................................................................................................................................29

Bibliography .............................................................................................................................................................................................................................31

iv © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 23431:2020(E)
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 non­governmental, 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 documents 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 drawn to the possibility that some of the elements of this document may be the subject of

patent rights. 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 146, Air quality, Subcommittee SC 3,

Ambient atmospheres, in collaboration with the European Committee for Standardization (CEN)

Technical Committee CEN/TC216, Gas detectors, in accordance with the Agreement on technical

cooperation between ISO and CEN (Vienna Agreement).

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.
© ISO 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/FDIS 23431:2020(E)
Introduction

The objective of this document is to provide road tunnel owners and operators with standard methods

for checking and calibrating instruments used in road tunnels to continuously monitor air speed,

carbon monoxide (CO), nitric oxide (NO) and nitrogen dioxide (NO ) concentrations and visibility.

Data from these instruments enables tunnel operators to manage the ventilation system in real time or

to take emergency measures (e.g. closure to traffic).

This document has been developed as a performance­based standard that allows for use of a number

of direct-reading instruments. Statements expressed in mandatory terms in notes to tables and figures

are deemed to be requirements of this document.

In order to improve traffic flow in central business districts and through sensitive environments, road

tunnels are increasingly used throughout the world to achieve the desired outcomes. There are a large

number of tunnels in operation, with a number of others in the planning stages.

Road tunnel projects are subject to environmental and/or planning approval conditions by regulatory

authorities that specify the parameters to be monitored in-tunnel, typically including air speed, CO, NO,

NO and visibility, with NO measured as a surrogate for NO , with, historically, 10 % of total nitrogen

2 2

oxides assumed to be NO . However, this assumption is no longer considered appropriate, given the

increased proportion of diesel fuelled vehicles in vehicle fleets. It can also be a requirement that the

tunnel ventilation system is controlled to:

a) reduce CO and NO concentrations within the tunnel environment to enable conformance with in­

tunnel air quality criteria for various averaging periods;
b) prevent or reduce portal emissions and resultant environmental impacts;
c) ensure appropriate visibility for different tunnel operating conditions; and

d) control smoke and improve the self-rescue time and security of tunnel users in emergency

situations such as fires.

Conformance with in-tunnel air quality criteria is typically determined by averaging measured CO and

measured or estimated NO concentrations from a number of instruments located on possible travel

paths throughout the tunnel system.

The number of instruments required to adequately characterise the tunnel environment is dependent

on a number of factors, including:
a) tunnel length and number of gradient changes and entry and exit ramps;
b) volume of traffic and types of vehicles;
c) exhaust ventilation system flowrate and control regime; and
d) regulatory requirements.

Consequently, this aspect is not addressed in this document. It is noted, however, that computational

fluid dynamics modelling can be used as a design tool to assist in the placement of instruments,

ensuring that indicative maximum and average concentrations are measured.
vi © ISO 2020 – All rights reserved
---------------------- Page: 6 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23431:2020(E)
Measurement of road tunnel air quality
1 Scope

This document describes methods for determining air speed and flow direction, CO, NO and NO

concentrations and visibility in road tunnels using direct-reading instruments. This document

specifically excludes requirements relating to instrument conformance testing.
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.

ISO 5802, Industrial fans — Performance testing in situ

ISO 6145, Gas analysis — Preparation of calibration gas mixtures using dynamic methods

ISO 10780, Stationary source emissions — Measurement of velocity and volume flowrate of gas streams

in ducts

ISO/IEC Guide 98­3, Uncertainty of measurement — Guide 98-3: 2008 Part 3: Guide to the expression of

uncertainty in measurement

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
calibration

set of operations that establish, under specified conditions, the relationship between the value indicated

by a measuring instrument and the corresponding known value of a reference standard

3.2
certified reference material

reference material, characterized by a metrologically valid procedure for one or more specified

properties, accompanied by a reference material certificate that provides the value of the specified

property, its associated uncertainty, and a statement of metrological traceability

3.3
check
confirmation of acceptable instrument response, without adjustment
3.4
fall time

time interval, after a step decrease in input concentration, between initial instrument response and

10 % of initial instrument response
© ISO 2020 – All rights reserved 1
---------------------- Page: 7 ----------------------
ISO/FDIS 23431:2020(E)
3.5
full scale
nominated maximum concentration for which an instrument has been calibrated

Note 1 to entry: The full scale (FS) is selected to cover the normal range of values expected in the sampling

environment.
3.6
interference equivalent

positive or negative instrument response caused by a substance other than the one being measured

3.7
linearity

deviation of an instrument’s output from a linear best fit line when subjected to varying reference test

atmospheres
3.8
lower detectable limit

minimum pollutant concentration that produces a signal of exactly three times the repeatability

standard deviation
Note 1 to entry: See ISO 5725-1.
3.9
parameter
one of the characteristics related to an air sample

EXAMPLE Concentration of pollutant or other quantifiable property (e.g. air speed).

3.10
ppm
parts per million

ratio expressing the volume of gaseous pollutant contained in 1 000 000 volumes of atmosphere

Note 1 to entry: It may be expressed in terms of millilitres per cubic metre as the values are identical. Alternatively,

it is one million times the ratio of the partial pressure of gaseous pollutant to the pressure of the atmosphere in

which it is contained.
3.11
precision

variation about the mean of repeated measurements of the same pollutant concentration on the same

instrument, expressed as one standard deviation about the mean
3.12
range
nominal minimum and maximum concentrations that a method is capable of measuring

Note 1 to entry: The nominal range is specified by the lower and upper range limits in concentration units, e.g. 0

to 250 ppm.
3.13
reference test atmosphere

test atmosphere containing a known concentration of pollutant, typically generated by diluting the

contents of a cylinder containing a gaseous certified reference material (3.2)
3.14
rise time

time interval, after a step increase in input concentration, between the instrument initial response and

90 % of the final instrument response
2 © ISO 2020 – All rights reserved
---------------------- Page: 8 ----------------------
ISO/FDIS 23431:2020(E)
3.15
road tunnel

any fully enclosed length of roadway with a minimum length ranging between 90 m and 150 m

EXAMPLE National Fire Protection Association and UK Design Manual for Roads and Bridges.

3.16
span drift

percentage change in the instrument response to an on­scale pollutant concentration over a period of

continuous unadjusted operation
3.17

measurement of expanded uncertainty at a confidence interval of 95 % according to ISO/IEC Guide 98-3

3.18
zero air

air free from contaminants likely to cause a detectable response on the test instrument

3.19
zero drift

change in the instrument response to a zero­pollutant concentration over a period of continuous

unadjusted operation
4 Test parameter — Air speed and flow direction
4.1 General

Clause 4 describes continuous, direct-reading instruments for determining air speed and flow direction

in road tunnels. Providing the instrument performance is within the specifications given in Table 1,

alternate methods may be used within the context of this document.
4.2 Principle

Air speed and flow direction in modern road tunnels are typically measured using ultrasonic flow

sensors.

Ultrasonic sensor systems are based on the principle that the speed of air movement changes the transit

time of a sound pulse across a fixed distance, allowing calculation of the air speed and determination of

flow direction.

Instrument outputs may be used to control mechanical ventilation in a tunnel during both routine and

emergency operation.

The measurement of flow in road tunnels is important for emergency operation (e.g. vehicle fire),

enabling the control of air flow such that fumes
...

SLOVENSKI STANDARD
kSIST ISO/FDIS 23431:2021
01-februar-2021
Zunanji zrak - Merjenje kakovosti zraka v cestnih tunelih
Measurement of road tunnel air quality
Mesurage de la qualité de l'air du tunnel routier
Ta slovenski standard je istoveten z: ISO/FDIS 23431
ICS:
13.040.20 Kakovost okoljskega zraka Ambient atmospheres
93.060 Gradnja predorov Tunnel construction
kSIST ISO/FDIS 23431:2021 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
kSIST ISO/FDIS 23431:2021
---------------------- Page: 2 ----------------------
kSIST ISO/FDIS 23431:2021
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 23431
ISO/TC 146/SC 3
Measurement of road tunnel air quality
Secretariat: ANSI
Voting begins on: Mesurage de la qualité de l'air du tunnel routier
2020­12­10
Voting terminates on:
2021­02­04
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
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 23431:2020(E)
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. ISO 2020
---------------------- Page: 3 ----------------------
kSIST ISO/FDIS 23431:2021
ISO/FDIS 23431:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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
CH­1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
kSIST ISO/FDIS 23431:2021
ISO/FDIS 23431:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Test parameter — Air speed and flow direction .................................................................................................................. 3

4.1 General ........................................................................................................................................................................................................... 3

4.2 Principle ........................................................................................................................................................................................................ 3

4.3 Apparatus .................................................................................................................................................................................................... 4

4.3.1 Instrument ............................................................................................................................................................................ 4

4.3.2 Reference path length measurement device (open path instruments only) ............... 4

4.3.3 Transfer standard flow sensor ............................................................................................................................. 4

4.4 Procedure .................................................................................................................................................................................................... 4

4.5 Instrument checks and calibrations ..................................................................................................................................... 5

4.5.1 General...................................................................................................................................................................................... 5

4.5.2 Measurement path length (open path instruments only) ............................................................ 5

4.5.3 Initial check .......................................................................................................................................................................... 5

4.5.4 Cross­section calibration .......................................................................................................................................... 6

4.5.5 Zero check .............................................................................................................................................................................. 6

4.5.6 System component check ......................................................................................................................................... 6

4.5.7 Operational precision check .................................................................................................................................. 7

4.6 Maintenance .............................................................................................................................................................................................. 8

4.6.1 General...................................................................................................................................................................................... 8

4.6.2 On site checks ..................................................................................................................................................................... 8

4.7 Calculation and expression of results.................................................................................................................................. 8

4.8 Measurement uncertainty ............................................................................................................................................................. 9

5 Test parameters — Carbon monoxide, nitric oxide and nitrogen dioxide ...............................................9

5.1 General ........................................................................................................................................................................................................... 9

5.2 Principle ........................................................................................................................................................................................................ 9

5.3 Apparatus .................................................................................................................................................................................................10

5.3.1 Instrument .........................................................................................................................................................................10

5.3.2 Reference barometer .................................................................................................................................................11

5.3.3 Reference thermometer ..........................................................................................................................................11

5.3.4 Reference path length measurement device (for open path instruments only) ....11

5.3.5 Reference flow through calibration cell length measurement device (for

open path instruments only) ..............................................................................................................................11

5.4 Procedure .................................................................................................................................................................................................12

5.4.1 Open path instruments............................................................................................................................................12

5.4.2 Single point instruments ........................................................................................................................................12

5.5 Instrument checks and calibrations ..................................................................................................................................13

5.5.1 General...................................................................................................................................................................................13

5.5.2 Open path instruments............................................................................................................................................13

5.5.3 Single point instruments ........................................................................................................................................14

5.5.4 Measurement path length (for open path instruments only) ................................................15

5.5.5 Flow through calibration cell length (for open path instruments only) .......................15

5.5.6 Temperature and pressure checks ................................................................................................................15

5.5.7 Zero air ..................................................................................................................................................................................15

5.5.8 Reference test atmosphere ..................................................................................................................................15

5.5.9 Zero check ...........................................................................................................................................................................16

5.5.10 Zero calibration ..............................................................................................................................................................16

5.5.11 Span check ..........................................................................................................................................................................17

5.5.12 Span calibration .............................................................................................................................................................17

© ISO 2020 – All rights reserved iii
---------------------- Page: 5 ----------------------
kSIST ISO/FDIS 23431:2021
ISO/FDIS 23431:2020(E)

5.5.13 Multipoint precision check ..................................................................................................................................18

5.5.14 System component check ......................................................................................................................................18

5.6 Maintenance ...........................................................................................................................................................................................19

5.6.1 General...................................................................................................................................................................................19

5.6.2 Cleaning of optical interfaces .............................................................................................................................19

5.6.3 Light source/electrochemical cell replacement ................................................................................19

5.6.4 Optical alignment .........................................................................................................................................................19

5.7 Calculation and expression of results...............................................................................................................................20

5.8 Measurement uncertainty ..........................................................................................................................................................20

6 Testing parameter — visibility ...........................................................................................................................................................20

6.1 General ........................................................................................................................................................................................................20

6.2 Principle .....................................................................................................................................................................................................21

6.3 Apparatus .................................................................................................................................................................................................22

6.3.1 Instrument .........................................................................................................................................................................22

6.3.2 Reference path length measurement device .................. .......................................................................23

6.4 Procedure .................................................................................................................................................................................................23

6.4.1 Transmissometer ..........................................................................................................................................................23

6.4.2 Scattered light instrument ....................................................................................................................................24

6.5 Instrument checks and calibrations ..................................................................................................................................24

6.5.1 General...................................................................................................................................................................................24

6.5.2 Zero check ...........................................................................................................................................................................25

6.5.3 Span check ..........................................................................................................................................................................25

6.5.4 Zero and span calibration .....................................................................................................................................25

6.5.5 Multipoint precision check ..................................................................................................................................25

6.5.6 System component check ......................................................................................................................................26

6.6 Maintenance ...........................................................................................................................................................................................26

6.6.1 General...................................................................................................................................................................................26

6.6.2 Cleaning of optical interfaces .............................................................................................................................27

6.6.3 Light source replacement ......................................................................................................................................27

6.6.4 Transmissometer optical alignment ............................................................................................................27

6.7 Calculation and expression of results...............................................................................................................................27

6.8 Measurement uncertainty ..........................................................................................................................................................27

7 Quality assurance and control.............................................................................................................................................................28

7.1 General ........................................................................................................................................................................................................28

7.2 Instrument log ......................................................................................................................................................................................28

7.3 Data acquisition and transfer ..................................................................................................................................................28

7.4 Data validation .....................................................................................................................................................................................28

8 Test report ................................................................................................................................................................................................................29

Bibliography .............................................................................................................................................................................................................................31

iv © ISO 2020 – All rights reserved
---------------------- Page: 6 ----------------------
kSIST ISO/FDIS 23431:2021
ISO/FDIS 23431:2020(E)
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 non­governmental, 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 documents 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 drawn to the possibility that some of the elements of this document may be the subject of

patent rights. 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 146, Air quality, Subcommittee SC 3,

Ambient atmospheres, in collaboration with the European Committee for Standardization (CEN)

Technical Committee CEN/TC216, Gas detectors, in accordance with the Agreement on technical

cooperation between ISO and CEN (Vienna Agreement).

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.
© ISO 2020 – All rights reserved v
---------------------- Page: 7 ----------------------
kSIST ISO/FDIS 23431:2021
ISO/FDIS 23431:2020(E)
Introduction

The objective of this document is to provide road tunnel owners and operators with standard methods

for checking and calibrating instruments used in road tunnels to continuously monitor air speed,

carbon monoxide (CO), nitric oxide (NO) and nitrogen dioxide (NO ) concentrations and visibility.

Data from these instruments enables tunnel operators to manage the ventilation system in real time or

to take emergency measures (e.g. closure to traffic).

This document has been developed as a performance­based standard that allows for use of a number

of direct-reading instruments. Statements expressed in mandatory terms in notes to tables and figures

are deemed to be requirements of this document.

In order to improve traffic flow in central business districts and through sensitive environments, road

tunnels are increasingly used throughout the world to achieve the desired outcomes. There are a large

number of tunnels in operation, with a number of others in the planning stages.

Road tunnel projects are subject to environmental and/or planning approval conditions by regulatory

authorities that specify the parameters to be monitored in-tunnel, typically including air speed, CO, NO,

NO and visibility, with NO measured as a surrogate for NO , with, historically, 10 % of total nitrogen

2 2

oxides assumed to be NO . However, this assumption is no longer considered appropriate, given the

increased proportion of diesel fuelled vehicles in vehicle fleets. It can also be a requirement that the

tunnel ventilation system is controlled to:

a) reduce CO and NO concentrations within the tunnel environment to enable conformance with in­

tunnel air quality criteria for various averaging periods;
b) prevent or reduce portal emissions and resultant environmental impacts;
c) ensure appropriate visibility for different tunnel operating conditions; and

d) control smoke and improve the self-rescue time and security of tunnel users in emergency

situations such as fires.

Conformance with in-tunnel air quality criteria is typically determined by averaging measured CO and

measured or estimated NO concentrations from a number of instruments located on possible travel

paths throughout the tunnel system.

The number of instruments required to adequately characterise the tunnel environment is dependent

on a number of factors, including:
a) tunnel length and number of gradient changes and entry and exit ramps;
b) volume of traffic and types of vehicles;
c) exhaust ventilation system flowrate and control regime; and
d) regulatory requirements.

Consequently, this aspect is not addressed in this document. It is noted, however, that computational

fluid dynamics modelling can be used as a design tool to assist in the placement of instruments,

ensuring that indicative maximum and average concentrations are measured.
vi © ISO 2020 – All rights reserved
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kSIST ISO/FDIS 23431:2021
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 23431:2020(E)
Measurement of road tunnel air quality
1 Scope

This document describes methods for determining air speed and flow direction, CO, NO and NO

concentrations and visibility in road tunnels using direct-reading instruments. This document

specifically excludes requirements relating to instrument conformance testing.
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.

ISO 5802, Industrial fans — Performance testing in situ

ISO 6145, Gas analysis — Preparation of calibration gas mixtures using dynamic methods

ISO 10780, Stationary source emissions — Measurement of velocity and volume flowrate of gas streams

in ducts

ISO/IEC Guide 98­3, Uncertainty of measurement — Guide 98-3: 2008 Part 3: Guide to the expression of

uncertainty in measurement

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
calibration

set of operations that establish, under specified conditions, the relationship between the value indicated

by a measuring instrument and the corresponding known value of a reference standard

3.2
certified reference material

reference material, characterized by a metrologically valid procedure for one or more specified

properties, accompanied by a reference material certificate that provides the value of the specified

property, its associated uncertainty, and a statement of metrological traceability

3.3
check
confirmation of acceptable instrument response, without adjustment
3.4
fall time

time interval, after a step decrease in input concentration, between initial instrument response and

10 % of initial instrument response
© ISO 2020 – All rights reserved 1
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kSIST ISO/FDIS 23431:2021
ISO/FDIS 23431:2020(E)
3.5
full scale
nominated maximum concentration for which an instrument has been calibrated

Note 1 to entry: The full scale (FS) is selected to cover the normal range of values expected in the sampling

environment.
3.6
interference equivalent

positive or negative instrument response caused by a substance other than the one being measured

3.7
linearity

deviation of an instrument’s output from a linear best fit line when subjected to varying reference test

atmospheres
3.8
lower detectable limit

minimum pollutant concentration that produces a signal of exactly three times the repeatability

standard deviation
Note 1 to entry: See ISO 5725-1.
3.9
parameter
one of the characteristics related to an air sample

EXAMPLE Concentration of pollutant or other quantifiable property (e.g. air speed).

3.10
ppm
parts per million

ratio expressing the volume of gaseous pollutant contained in 1 000 000 volumes of atmosphere

Note 1 to entry: It may be expressed in terms of millilitres per cubic metre as the values are identical. Alternatively,

it is one million times the ratio of the partial pressure of gaseous pollutant to the pressure of the atmosphere in

which it is contained.
3.11
precision

variation about the mean of repeated measurements of the same pollutant concentration on the same

instrument, expressed as one standard deviation about the mean
3.12
range
nominal minimum and maximum concentrations that a method is capable of measuring

Note 1 to entry: The nominal range is specified by the lower and upper range limits in concentration units, e.g. 0

to 250 ppm.
3.13
reference test atmosphere

test atmosphere containing a known concentration of pollutant, typically generated by diluting the

contents of a cylinder containing a gaseous certified reference material (3.2)
3.14
rise time

time interval, after a step increase in input concentration, between the instrument initial response and

90 % of the final instrument response
2 © ISO 2020 – All rights reserved
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kSIST ISO/FDIS 23431:2021
ISO/FDIS 23431:2020(E)
3.15
road tunnel

any fully enclosed length of roadway with a minimum length ranging between 90 m and 150 m

EXAMPLE National Fire Protection Association and UK Design Manual for Roads and Bridges.

3.16
span drift

percentage change in the instrument response to an on­scale pollutant concentration over a period of

continuous unadjusted operation
3.17

measurement of expanded uncertainty at a confidence interval of 95 % according to ISO/IEC Guide 98-3

3.18
zero air

air free from contaminants likely to cause a detectable response on the test instrument

3.19
zero drift

change in the instrument response to a zero­pollutant concentration over a period of continuous

unadjusted operation
4 Test parameter — Air speed and flow direction
4.1 General
Clause 4 des
...

PROJET
NORME ISO/FDIS
FINAL
INTERNATIONALE 23431
ISO/TC 146/SC 3
Mesurage de la qualité de l'air du
Secrétariat: ANSI
tunnel routier
Début de vote:
2020-12-10
Measurement of road tunnel air quality
Vote clos le:
2021-02-04
LES DESTINATAIRES DU PRÉSENT PROJET SONT
INVITÉS À PRÉSENTER, AVEC LEURS OBSER-
VATIONS, NOTIFICATION DES DROITS DE PRO-
PRIÉTÉ DONT ILS AURAIENT ÉVENTUELLEMENT
CONNAISSANCE ET À FOURNIR UNE DOCUMEN-
TATION EXPLICATIVE.
OUTRE LE FAIT D’ÊTRE EXAMINÉS POUR
ÉTABLIR S’ILS SONT ACCEPTABLES À DES FINS
INDUSTRIELLES, TECHNOLOGIQUES ET COM-
Numéro de référence
MERCIALES, AINSI QUE DU POINT DE VUE
ISO/FDIS 23431:2020(F)
DES UTILISATEURS, LES PROJETS DE NORMES
INTERNATIONALES DOIVENT PARFOIS ÊTRE
CONSIDÉRÉS DU POINT DE VUE DE LEUR POSSI-
BILITÉ DE DEVENIR DES NORMES POUVANT
SERVIR DE RÉFÉRENCE DANS LA RÉGLEMENTA-
TION NATIONALE. ISO 2020
---------------------- Page: 1 ----------------------
ISO/FDIS 23431:2020(F)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2020

Tous droits réservés. Sauf prescription différente ou nécessité dans le contexte de sa mise en œuvre, 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, ou la diffusion sur l’internet ou sur un intranet, sans autorisation écrite préalable. Une autorisation peut

être demandée à l’ISO à l’adresse ci-après ou au comité membre de l’ISO dans le pays du demandeur.

ISO copyright office
Case postale 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Genève
Tél.: +41 22 749 01 11
E-mail: copyright@iso.org
Web: www.iso.org
Publié en Suisse
ii © ISO 2020 – Tous droits réservés
---------------------- Page: 2 ----------------------
ISO/FDIS 23431:2020(F)
Sommaire Page

Avant-propos ................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Domaine d’application ................................................................................................................................................................................... 1

2 Références normatives ................................................................................................................................................................................... 1

3 Termes et définitions ....................................................................................................................................................................................... 1

4 Paramètre d’essai — Vitesse et sens du courant d’air ................................................................................................... 3

4.1 Généralités .................................................................................................................................................................................................. 3

4.2 Principe ......................................................................................................................................................................................................... 3

4.3 Appareillage............................................................................................................................................................................................... 4

4.3.1 Instrument ............................................................................................................................................................................ 4

4.3.2 Dispositif de mesure référence de la longueur du trajet (instruments à

trajet ouvert uniquement) ....................................................................................................................................... 4

4.3.3 Capteur de débit étalon de transfert ............................................................................................................... 5

4.4 Mode opératoire .................................................................................................................................................................................... 5

4.5 Contrôles et étalonnages des instruments ...................................................................................................................... 5

4.5.1 Généralités ............................................................................................................................................................................ 5

4.5.2 Longueur du trajet de mesure (instruments à trajet ouvert uniquement) ................... 6

4.5.3 Contrôle initial ................................................................................................................................................................... 6

4.5.4 Étalonnage de section ........................................................................................................................................... ....... 6

4.5.5 Contrôle du zéro ............................................................................................................................................................... 7

4.5.6 Contrôle des composants du système ........................................................................................................... 7

4.5.7 Contrôle fonctionnel de la précision ............................................................................................................... 7

4.6 Maintenance .............................................................................................................................................................................................. 8

4.6.1 Généralités ............................................................................................................................................................................ 8

4.6.2 Contrôles sur site ............................................................................................................................................................. 9

4.7 Calcul et expression des résultats .......................................................................................................................................... 9

4.8 Incertitude de mesure ...................................................................................................................................................................... 9

5 Paramètres d’essai — Monoxyde de carbone, oxyde d’azote et dioxyde d’azote ............................10

5.1 Généralités ...............................................................................................................................................................................................10

5.2 Principe ......................................................................................................................................................................................................10

5.3 Appareillage............................................................................................................................................................................................11

5.3.1 Instrument .........................................................................................................................................................................11

5.3.2 Baromètre de référence ..........................................................................................................................................12

5.3.3 Thermomètre de référence ..................................................................................................................................12

5.3.4 Dispositif de mesure de la longueur du trajet de référence (pour les

instruments à trajet ouvert uniquement) ...............................................................................................12

5.3.5 Dispositif de mesure de la longueur de référence de la cellule
d’étalonnage à débit continu (pour les instruments à trajet ouvert

uniquement) .....................................................................................................................................................................12

5.4 Mode opératoire .................................................................................................................................................................................13

5.4.1 Instruments de mesure à trajet ouvert ......................................................................................................13

5.4.2 Instruments de mesure en un seul point .................................................................................................14

5.5 Contrôles et étalonnages des instruments ...................................................................................................................14

5.5.1 Généralités .........................................................................................................................................................................14

5.5.2 Instruments de mesure à trajet ouvert ......................................................................................................14

5.5.3 Instruments de mesure en un seul point .................................................................................................16

5.5.4 Longueur du trajet de mesure (pour les instruments à trajet ouvert

uniquement) .....................................................................................................................................................................16

5.5.5 Longueur de référence de la cellule d’étalonnage à débit continu (pour les

instruments à trajet ouvert uniquement) ...............................................................................................16

5.5.6 Contrôles de la température et de la pression ....................................................................................17

5.5.7 Air de zéro ..........................................................................................................................................................................17

© ISO 2020 – Tous droits réservés iii
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ISO/FDIS 23431:2020(F)

5.5.8 Atmosphère d’essai de référence ....................................................................................................................17

5.5.9 Contrôle du zéro ............................................................................................................................................................17

5.5.10 Étalonnage du zéro .....................................................................................................................................................18

5.5.11 Contrôle du point d’échelle ..................................................................................................................................18

5.5.12 Étalonnage du point d’échelle ...........................................................................................................................19

5.5.13 Contrôle de précision multipoint....................................................................................................................19

5.5.14 Contrôle des composants du système ........................................................................................................20

5.6 Maintenance ...........................................................................................................................................................................................21

5.6.1 Généralités .........................................................................................................................................................................21

5.6.2 Nettoyage des interfaces optiques .................................................................................................................21

5.6.3 Remplacement de la source lumineuse/d’une cellule électrochimique .......................21

5.6.4 Alignement optique ....................................................................................................................................................21

5.7 Calcul et expression des résultats .......................................................................................................................................22

5.8 Incertitude de mesure ...................................................................................................................................................................22

6 Paramètre d’essai — Visibilité ............................................................................................................................................................22

6.1 Généralités ...............................................................................................................................................................................................22

6.2 Principe ......................................................................................................................................................................................................23

6.3 Appareillage............................................................................................................................................................................................24

6.3.1 Instrument .........................................................................................................................................................................24

6.3.2 Dispositif de mesure de la longueur du trajet de référence ....................................................25

6.4 Mode opératoire .................................................................................................................................................................................25

6.4.1 Transmissomètre ..........................................................................................................................................................25

6.4.2 Instrument de diffusion de la lumière ........................................................................................................26

6.5 Contrôles et étalonnages des instruments ...................................................................................................................26

6.5.1 Généralités .........................................................................................................................................................................26

6.5.2 Contrôle du zéro ............................................................................................................................................................27

6.5.3 Contrôle du point d’échelle ..................................................................................................................................27

6.5.4 Étalonnage du zéro et du point d’échelle.................................................................................................28

6.5.5 Contrôle de précision multipoint....................................................................................................................28

6.5.6 Contrôle des composants du système ........................................................................................................28

6.6 Maintenance ...........................................................................................................................................................................................29

6.6.1 Généralités .........................................................................................................................................................................29

6.6.2 Nettoyage des interfaces optiques .................................................................................................................29

6.6.3 Remplacement de la source lumineuse .....................................................................................................29

6.6.4 Alignement optique du transmissomètre ...............................................................................................29

6.7 Calcul et expression des résultats .......................................................................................................................................30

6.8 Incertitude de mesure ...................................................................................................................................................................30

7 Contrôle et assurance de la qualité ................................................................................................................................................30

7.1 Généralités ...............................................................................................................................................................................................30

7.2 Journal d’instrument .......................................................................................................................................................................30

7.3 Acquisition et transfert des données ................................................................................................................................31

7.4 Validation des données .................................................................................................................................................................31

8 Rapport d’essai ....................................................................................................................................................................................................32

Bibliographie ...........................................................................................................................................................................................................................33

iv © ISO 2020 – Tous droits réservés
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ISO/FDIS 23431:2020(F)
Avant-propos

L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes

nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est

en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude

a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,

gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.

L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui

concerne la normalisation électrotechnique.

Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont

décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents

critères d’approbation requis pour les différents types de documents ISO. Le présent document a été

rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www

.iso .org/ directives).

L’attention est attirée sur le fait que certains des éléments du présent document peuvent faire l’objet de

droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable

de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant

les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de

l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de

brevets reçues par l’ISO (voir www .iso .org/ brevets).

Les appellations commerciales éventuellement mentionnées dans le présent document sont données

pour information, par souci de commodité, à l’intention des utilisateurs et ne sauraient constituer un

engagement.

Pour une explication de la nature volontaire des normes, la signification des termes et expressions

spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion

de l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles

techniques au commerce (OTC), voir le lien suivant: www .iso .org/ iso/ fr/ avant -propos.

Le présent document a été élaboré par le Comité technique ISO/TC 146, Qualité de l’air, sous-comité SC 3,

Atmosphères ambiantes, en collaboration avec le Comité technique CEN/TC 216 du Comité européen de

normalisation (CEN), Détecteurs de gaz, conformément à l’Accord de coopération technique entre l’ISO

et le CEN (Accord de Vienne).

Il convient que l’utilisateur adresse tout retour d’information ou toute question concernant le présent

document à l’organisme national de normalisation de son pays. Une liste exhaustive desdits organismes

se trouve à l’adresse www .iso .org/ fr/ members .html.
© ISO 2020 – Tous droits réservés v
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ISO/FDIS 23431:2020(F)
Introduction

L’objectif du présent document est de fournir aux maîtres d’ouvrage et exploitants de tunnels routiers

des méthodes normalisées pour la vérification et l’étalonnage des instruments utilisés dans les tunnels

routiers afin de surveiller en continu la vitesse de l’air, les concentrations en monoxyde de carbone (CO),

en oxyde d’azote (NO) et en dioxyde d’azote (NO ) ainsi que la visibilité.

Les données de ces instruments permettent aux exploitants de tunnels de piloter le système de

ventilation en temps réel ou de prendre des mesures d’urgence (par exemple, fermeture à la circulation).

Le présent document a été élaboré comme une norme fondée sur les performances permettant

l’utilisation d’un certain nombre d’instruments à lecture directe. Les énoncés exprimés en termes

obligatoires dans les notes aux tableaux et aux figures sont réputés être des exigences du présent

document.

Afin d’améliorer le débit de circulation dans les grands centres d’affaires et dans les environnements

sensibles, les tunnels routiers sont de plus en plus utilisés dans le monde entier pour atteindre les

résultats escomptés. Il existe un grand nombre de tunnels en service et plusieurs autres sont à l’étude.

Les projets de tunnels routiers sont soumis à validation sur des critères environnementaux et/ou

d’aménagement par les autorités réglementaires qui spécifient les paramètres à surveiller dans le

tunnel, lesquels incluent généralement la vitesse de l’air, le CO, le NO, le NO et la visibilité, le NO étant

mesuré comme valeur de substitution au NO , en se basant sur le ratio historique de 10 % des oxydes

d’azote totaux qui sont du NO . Toutefois, cette hypothèse n’est plus considérée comme appropriée

compte tenu de la proportion accrue de véhicules à moteur diesel dans les parcs automobiles. Il peut

également être exigé que le système de ventilation du tunnel soit contrôlé de sorte à:

a) réduire les concentrations en CO et en NO à l’intérieur du tunnel afin de respecter les critères de

qualité de l’air à l’intérieur du tunnel pour diverses périodes de calcul de moyennes;

b) prévenir ou réduire les émissions au niveau des têtes de tunnel et les impacts environnementaux

qui en résultent;

c) assurer une visibilité adéquate pour les différentes conditions d’exploitation du tunnel;

d) contrôler les fumées et améliorer le temps d’auto-évacuation et la sécurité des usagers du tunnel

dans les situations d’urgence telles que les incendies.

La conformité avec les critères de qualité de l’air à l’intérieur du tunnel est généralement déterminée

en calculant la moyenne des concentrations en CO et en NO mesurées ou estimées à l’aide d’un certain

nombre d’instruments placés le long de chaque tube de l’ouvrage.

Le nombre d’instruments requis pour surveiller correctement la qualité de l’air du tunnel dépend d’un

certain nombre de facteurs, incluant:

a) la longueur du tunnel ainsi que le nombre de changements de déclivité et de bretelles d’entrée et

de sortie;
b) la densité du trafic et les types de véhicules;

c) le débit et le régime de contrôle du système de ventilation pour gérer les fumées ou l’air vicié;

d) les exigences réglementaires.

Par conséquent, cet aspect n’est pas abordé dans le présent document. Il convient toutefois de noter que

la modélisation numérique de la mécanique des fluides peut être utilisée comme outil de conception

pour aider à la mise en place des instruments, en garantissant que les concentrations maximales et

moyennes indicatives sont mesurées.
vi © ISO 2020 – Tous droits réservés
---------------------- Page: 6 ----------------------
PROJET FINAL DE NORME INTERNATIONALE ISO/FDIS 23431:2020(F)
Mesurage de la qualité de l'air du tunnel routier
1 Domaine d’application

Le présent document décrit des méthodes permettant de déterminer la vitesse et le sens d’écoulement

de l’air, les concentrations en monoxyde de carbone (CO), en oxyde d’azote (NO) et en dioxyde d’azote

(NO ), et la visibilité dans les tunnels routiers à l’aide d’instruments à lecture directe. Il exclut

spécifiquement les exigences relatives aux essais de conformité des instruments.
2 Références normatives

Les documents ci-après, dans leur intégralité ou non, sont des références normatives indispensables à

l’application du présent document. Pour les références datées, seule l’édition citée s’applique. Pour les

références non datées, la dernière édition du document de référence s’applique (y compris les éventuels

amendements).
ISO 5802, Ventilateurs industriels — Essai de performance in situ

ISO 6145, Analyse des gaz — Préparation des mélanges de gaz pour étalonnage à l'aide de méthodes

dynamiques

ISO 10780, Émissions de sources fixes — Mesurage de la vitesse et du débit-volume des courants gazeux

dans des conduites

Guide ISO/IEC 98-3, Incertitude de mesure — Partie 3: Guide pour l’expression de l’incertitude de mesure

(GUM: 1995)

ISO/IEC 17025, Exigences générales concernant la compétence des laboratoires d'étalonnages et d'essais

3 Termes et définitions

Pour les besoins du présent document, les termes et définitions suivants s’appliquent.

L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en

normalisation, consultables aux adresses suivantes:

— ISO Online browsing platform: disponible à l’adresse https:// www .iso .org/ obp;

— IEC Electropedia: disponible à l’adresse http:// www .electropedia .org/ .
3.1
étalonnage

ensemble des opérations permettant d’établir, dans des conditions spécifiées, les rapports existant

entre la valeur indiquée par un instrument de mesure et la valeur connue correspondante d’un étalon

de référence
3.2
matériau de référence certifié

matériau de référence caractérisé par un mode opératoire métrologiquement valide applicable

à une ou plusieurs propriétés spécifiées et accompagné d’un certificat de matériau de référence qui

indique la valeur de la propriété spécifiée, son incertitude associée, et une expression de la traçabilité

métrologique
© ISO 2020 – Tous droits réservés 1
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ISO/FDIS 23431:2020(F)
3.3
contrôle
confirmation de la réponse acceptable d’un instrument, sans réglage
3.4
temps de descente

intervalle de temps entre la réponse initiale de l’instrument et 10 % de la réponse initiale de

l’instrument, après une diminution progressive de la concentration d’entrée
3.5
pleine échelle
concentration maximale désignée pour laquelle un instrument a été étalonné

Note 1 à l'article: La pleine échelle (PE) est sélectionnée de sorte à couvrir la plage normale des valeurs attendues

dans l’environnement de prélèvement.
3.6
équivalent d’interférence

réponse positive ou négative de l’instrument induite par une substance autre que celle mesurée

3.7
linéarité

divergence du relevé d’un instrument par rapport à une ligne d’ajustement linéaire optimal lorsque

celui-ci est soumis à des atmosphères d’essai de référence variables
3.8
limite inférieure de détection

concentration minimale en polluant qui produit un signal d’exactement trois fois l’écart-type de

répétabilité
Note 1 à l'article: Voir l’ISO 5725-1.
3.9
paramètre
une des caractéristiques liées à un échantillon d’air

EXEMPLE Concentration en polluant ou autres valeurs quantifiables (par exemple, la vitesse de l’air).

3.10
ppm
parties par million

rapport exprimant le volume de polluant gazeux contenu dans 1 000 000 volumes d’atmosphère

Note 1 à l'article: et pouvant être exprimé en millilitres par mètre cube, les valeurs étant identiques. En variante,

ce rapport est égal à un million de fois le rapport entre la pression partielle du polluant gazeux et la pression de

l’atmosphère dans laquelle il est contenu.
3.11
fidélité

variation autour de la moyenne des mesures obtenues par mesurages répétés de la même concentration

en polluant avec le même instrument, exprimée sous la forme d’un écart-type autour de la moyenne

3.12
plage

concentrations minimale et maximale nominales qu’une méthode est capable de mesurer

Note 1 à l'article: La plage nominale est spécifiée par les limites inférieure et supérieure de la plage en unités de

concentration, par exemple 0 ppm à 250 ppm.
2 © ISO 2020 – Tous droits réservés
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ISO/FDIS 23431:2020(F)
3.13
atmosphère d’essai de référence

atmosphère d’essai contenant une concentration connue en polluant, généralement créée par la dilution

du cont
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.