ISO 20181:2023
(Main)Stationary source emissions — Quality assurance of automated measuring systems
Stationary source emissions — Quality assurance of automated measuring systems
This document specifies procedures for establishing quality assurance levels (QAL) for automated measuring systems (AMS) installed on industrial plants for the determination of the flue gas components and other flue gas parameters. This document specifies: — a procedure (QAL2) to calibrate the AMS and determine the variability of the measured values obtained by it, so as to demonstrate the suitability of the AMS for its application, following its installation; — a procedure (QAL3) to maintain and demonstrate the required quality of the measurement results during the normal operation of an AMS, by checking that the zero and span characteristics are consistent with those determined during QAL1; — a procedure for the annual surveillance tests (AST) of the AMS in order to evaluate (i) that it functions correctly and its performance remains valid and (ii) that its calibration function and variability remain as previously determined. This document is designed to be used after the AMS has been certified in accordance with the series of documents EN 15267.
Émission des sources fixes — Assurance qualité des systèmes automatiques de mesurage
Emisije nepremičnih virov - Zagotavljanje kakovosti avtomatskih merilnih sistemov
General Information
Relations
Buy Standard
Standards Content (Sample)
SLOVENSKI STANDARD
SIST ISO 20181:2023
01-september-2023
Emisije nepremičnih virov - Zagotavljanje kakovosti avtomatskih merilnih
sistemov
Stationary source emissions - Quality assurance of automated measuring systems
Émission des sources fixes - Assurance qualité des systèmes automatiques de
mesurage
Ta slovenski standard je istoveten z: ISO 20181:2023
ICS:
13.040.40 Emisije nepremičnih virov Stationary source emissions
SIST ISO 20181:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 20181:2023
---------------------- Page: 2 ----------------------
SIST ISO 20181:2023
INTERNATIONAL ISO
STANDARD 20181
First edition
2023-02
Stationary source emissions — Quality
assurance of automated measuring
systems
Émission des sources fixes — Assurance qualité des systèmes
automatiques de mesurage
Reference number
ISO 20181:2023(E)
© ISO 2023
---------------------- Page: 3 ----------------------
SIST ISO 20181:2023
ISO 20181:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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 2023 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 20181:2023
ISO 20181:2023(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.6
4.1 Symbols . 6
4.2 Abbreviated terms . 7
5 Principle . 7
5.1 General . 7
5.2 Limitations . 9
5.3 Measurement site and installation . 9
5.4 Testing laboratories performing SRM measurements . 10
6 Calibration and validation of the AMS (QAL2) .10
6.1 General . 10
6.2 Functional test . 11
6.3 Parallel measurements with the SRM .12
6.4 Data evaluation . 14
6.4.1 Preparation of data . 14
6.4.2 Selection of data points from automated SRM . 15
6.4.3 Establishing the calibration function . 15
6.5 Calibration function of the AMS and its validity . 16
6.6 Calculation of variability . 18
6.7 Test of variability . 19
6.8 QAL2 report . . 19
7 Ongoing quality assurance during operation (QAL3) .20
7.1 General . 20
7.2 Procedures to maintain ongoing quality . 21
7.3 Choosing control charts . 21
7.4 Control chart limits . 22
7.4.1 General .22
7.4.2 Calculation of control chart limits using performance data .22
7.4.3 Calculation of control chart limits using the maximum permissible
uncertainty .23
7.5 Zero and span measurements .23
7.5.1 General .23
7.5.2 Frequency of zero and span measurements .23
7.5.3 Extractive gas analysis systems . 24
7.5.4 In-situ gas-monitoring AMS . 24
7.5.5 Particulate-monitoring AMS . 25
7.6 Documentation of control charts . 25
8 Annual surveillance test (AST).25
8.1 General . 25
8.2 Functional test . 26
8.3 Parallel measurements with the SRM . 26
8.4 Data evaluation . 27
8.5 Calculation of variability .28
8.6 Test of variability and validity of the calibration function .28
8.7 AST report .29
9 Documentation .29
iii
© ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
SIST ISO 20181:2023
ISO 20181:2023(E)
Annex A (normative) QAL2 and AST functional test of AMS .30
Annex B (normative) Test of linearity .34
Annex C (informative) Control charts .36
Annex D (normative) Documentation .46
Annex E (informative) Examples of calculation of the calibration function and of the
variability test .48
Annex F (informative) Example of calculation of the standard deviation s of the AMS at
AMS
zero and span level .63
Annex G (informative) Example of using the calibration function and testing the variability
and validity of the calibration function in the AST .66
Annex H (informative) Implementation of QAL1 .70
Annex I (normative) k and t values .71
v 0,95; N–1
Annex J (informative) Significant technical changes .72
Bibliography .74
iv
© ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 20181:2023
ISO 20181:2023(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 the European Committee for Standardization (CEN) (as EN 14181:2014)
and was adopted, without modification by Technical Committee ISO/TC 146, Air quality, Subcommittee
SC 1, Stationary source emission.
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.
v
© ISO 2023 – All rights reserved
---------------------- Page: 7 ----------------------
SIST ISO 20181:2023
ISO 20181:2023(E)
Introduction
This document describes the quality assurance procedures needed to ensure that an automated
measuring system (AMS) installed to measure emissions to air are capable of meeting the uncertainty
[1],[2],[3]
requirements on measured values e.g. given by legislation or more generally by competent
authorities.
Three different quality assurance levels (QAL1, QAL2, and QAL3) are defined to achieve this objective.
These quality assurance levels cover the suitability of an AMS for its measuring task (e.g. before or
during the purchase period of the AMS), the validation of the AMS following its installation, and the
control of the AMS during its ongoing operation on an industrial plant. An annual surveillance test
(AST) is also defined.
The suitability evaluation (QAL1) of the AMS and its measuring procedure are described in EN 15267-
3 and ISO 14956 where a methodology is given for calculating the total uncertainty of AMS measured
values. This total uncertainty is calculated from the evaluation of all the uncertainty components
arising from its individual performance characteristics that contribute.
vi
© ISO 2023 – All rights reserved
---------------------- Page: 8 ----------------------
SIST ISO 20181:2023
INTERNATIONAL STANDARD ISO 20181:2023(E)
Stationary source emissions — Quality assurance of
automated measuring systems
1 Scope
This document specifies procedures for establishing quality assurance levels (QAL) for automated
measuring systems (AMS) installed on industrial plants for the determination of the flue gas
components and other flue gas parameters.
This document specifies:
— a procedure (QAL2) to calibrate the AMS and determine the variability of the measured values
obtained by it, so as to demonstrate the suitability of the AMS for its application, following its
installation;
— a procedure (QAL3) to maintain and demonstrate the required quality of the measurement results
during the normal operation of an AMS, by checking that the zero and span characteristics are
consistent with those determined during QAL1;
— a procedure for the annual surveillance tests (AST) of the AMS in order to evaluate (i) that it functions
correctly and its performance remains valid and (ii) that its calibration function and variability
remain as previously determined.
This document is designed to be used after the AMS has been certified in accordance with the series of
documents EN 15267.
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.
EN 15259:2007, Air quality — Measurement of stationary source emissions — Requirements for
measurement sections and sites and for the measurement objective, plan and report
EN 15267-1, Air quality — Certification of automated measuring systems — Part 1: General principles
EN 15267-2, Air quality — Certification of automated measuring systems — Part 2: Initial assessment of the
AMS manufacturer’s quality management system and post certification surveillance for the manufacturing
process
EN 15267-3, Air quality — Certification of automated measuring systems — Part 3: Performance criteria
and test procedures for automated measuring systems for monitoring emissions from stationary sources
ISO 14956, Air quality — Evaluation of the suitability of a measurement procedure by comparison with a
required measurement uncertainty
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
1
© ISO 2023 – All rights reserved
---------------------- Page: 9 ----------------------
SIST ISO 20181:2023
ISO 20181:2023(E)
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
automated measuring system
AMS
measuring system permanently installed on site for continuous monitoring of emissions or
measurement of peripheral parameters
Note 1 to entry: An AMS is a method which is traceable to a reference method.
Note 2 to entry: Apart from the analyser, an AMS includes facilities for taking samples (e.g. sample probe, sample
gas lines, flow meters, regulators, delivery pumps) and for sample conditioning (e.g. dust filter, water vapour
removal devices, converters, diluters). This definition also includes testing and adjusting devices that are
required for regular functional checks.
3.2
extractive AMS
AMS having the detection unit physically separated from the gas stream by means of a sampling system
3.3
in-situ AMS
AMS having the detection unit in the gas stream or in a part of it
3.4
peripheral AMS
AMS used to gather the data required to convert the AMS measured value to standard conditions
Note 1 to entry: A peripheral AMS is used to measure e.g. water vapour, temperature, pressure and oxygen.
3.5
reference method
RM
measurement method taken as a reference by convention, which gives the accepted reference value of
the measurand
[SOURCE: EN 15259:2007]
3.6
standard reference method
SRM
reference method prescribed by European or national legislation
Note 1 to entry: Standard reference methods are used e.g. to calibrate and validate AMS and for periodic
measurements to check compliance with limit values.
[SOURCE: EN 15259:2007]
3.7
peripheral SRM
SRM used to gather the data required to convert the SRM measured values to AMS or standard
conditions
Note 1 to entry: A peripheral SRM is used to measure e.g. water vapour, temperature, pressure and oxygen.
3.8
standard conditions
conditions to which measured values have to be standardized to verify compliance with emission limit
values
[1] [2] [3]
Note 1 to entry: Standard conditions are specified e.g. in EU Directives , and .
2
© ISO 2023 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 20181:2023
ISO 20181:2023(E)
3.9
emission limit value
ELV
limit value related to the maximum permissible uncertainty
[1] [2] [3]
Note 1 to entry: For the EU Directives , and it is the daily emission limit value that relates to the uncertainty
requirement.
3.10
maximum permissible uncertainty
uncertainty requirement on AMS measured values given by legislation or competent authorities
3.11
legislation
directives, acts, ordinances or regulations
3.12
competent authority
organization or organizations which implement the requirements of EU Directives and regulate
installations which shall comply with the requirements of this document
3.13
calibration function
linear relationship between the values of the SRM and the AMS with the assumption of a constant
residual standard deviation
Note 1 to entry: For dust measuring AMS, a quadratic calibration function can be used as described in EN 13284-
2.
3.14
standard deviation
positive square root of the mean squared deviation from the arithmetic mean divided by the number of
degrees of freedom
Note 1 to entry: The number of degrees of freedom is the number of measurements minus 1.
3.15
confidence interval
interval estimator (T , T ) for the parameter θ with the statistics T and T as interval limits and for
1 2 1 2
which it holds that P[T < θ < T ] ≥ (1 – α)
1 2
[SOURCE: ISO 3534-1:2006]
Note 1 to entry: The two-sided 95 % confidence interval of a normal distribution is illustrated in Figure 1, where:
T = Θ – 1,96 σ is the lower 95 % confidence limit;
1 0
T = Θ + 1,96 σ is the upper 95 % confidence limit;
2 0
I = T – T = 2 × 1,96 × σ is the length of the 95 % confidence interval;
2 1 0
σ = I / (2 × 1,96) is the standard deviation associated with a 95 % confidence interval;
0
n is the number of observed values;
f is the frequency;
m is the measured value.
3
© ISO 2023 – All rights reserved
---------------------- Page: 11 ----------------------
SIST ISO 20181:2023
ISO 20181:2023(E)
Figure 1 — Illustration of the 95 % confidence interval of a normal distribution
In this document, the standard deviation σ is estimated in QAL2 by parallel measurements with
0
the SRM. It is assumed that the requirement for σ , presented in terms of a maximum permissible
0
uncertainty, is provided by the regulators (e.g. in some EU Directives). In the procedures of this
standard, the premise is that the maximum permissible uncertainty is given as σ itself, or as a quarter
0
of the length of the full 95 % confidence interval
Note 2 to entry: In some EU Directives (see [1],[2],[3]) the uncertainty of the AMS measured values is expressed
as half of the length of a 95 % confidence interval as a percentage P of the emission limit value E. Then, in order to
convert this uncertainty to a standard deviation, the appropriate conversion factor is σ =PE /, 196 .
0
3.16
variability
standard deviation of the differences of parallel measurements between the SRM and AMS
3.17
uncertainty
parameter associated with the result of a measurement that characterizes the dispersion of the values
that could reasonably be attributed to the measurand
[SOURCE: ISO/IEC Guide 98-3:2008]
3.18
measurand
particular quantity subject to measurement
[SOURCE: ISO/IEC Guide 98-3:2008]
Note 1 to entry: A measurand can be e.g. the mass concentration of a measured component or the waste gas
velocity, pressure or temperature.
3.19
measured component
constituent of the waste gas for which a defined measurand is to be determined by measurement
[SOURCE: EN 15259:2007]
3.20
peripheral parameter
specified physical or chemical quantity which is needed for conversion of measured values to specified
conditions
4
© ISO 2023 – All rights reserved
---------------------- Page: 12 ----------------------
SIST ISO 20181:2023
ISO 20181:2023(E)
3.21
measured value
estimated value of the measurand derived from a measured signal
Note 1 to entry: This usually involves calculations related to the calibration process and conversion to required
quantities.
Note 2 to entry: A measured value is a short-term average. The averaging time can be e.g. 10 min, 30 min or 1 h.
3.22
instrument reading
measured signal directly provided by the AMS without using the calibration function
3.23
zero reading
instrument reading on simulation of the input parameter at zero concentration
3.24
span reading
instrument reading for a simulation of the input parameter at a fixed elevated concentration
3.25
instability
change in the measured signal comprised of drift and dispersion over a stated maintenance interval
Note 1 to entry: Drift and dispersion specify the monotonic and stochastic change with time of the measured
signal, respectively.
3.26
drift
monotonic change of the calibration function over stated maintenance interval, which results in a
change of the measured signal
3.27
precision
closeness of agreement of results obtained from the AMS for successive zero readings and successive
span readings at defined time intervals
3.28
response time
t
90
time interval between the instant of a sudden change in the value of the input quantity to an AMS and
the time as from which the value of the output quantity is reliably maintained above 90 % of the correct
value of the input quantity
Note 1 to entry: The response time is also referred to as the 90 % time.
3.29
maintenance interval
maximum admissible interval of time for which the performance characteristics will remain within a
predefined range without external servicing, e.g. refill, calibration, adjustment
3.30
reference material
substance or mixture of substances, with a known concentration within specified limits, or a device of
known characteristics
3.31
CUSUM chart
calculation procedure in which the amount of drift and change in precision is compared to the
corresponding uncertainty components which are obtained during QAL1
5
© ISO 2023 – All rights reserved
---------------------- Page: 13 ----------------------
SIST ISO 20181:2023
ISO 20181:2023(E)
3.32
EWMA chart
calculation procedure in which the combined amount of drift and change in precision is compared to
the corresponding uncertainty components which are obtained during QAL1
Note 1 to entry: The EWMA chart averages the data in a way that gives less and less weight to data as they are
further removed in time.
4 Symbols and abbreviated terms
4.1 Symbols
a
intercept of the calibration function
best estimate of a
ˆ
a
b
slope of the calibration function
ˆ
best estimate of b
b
D
difference between SRM measured value y and calibrated AMS measured value ˆy
i
i
i
average of D
D
i
E emission limit value
2
k
test value for variability (based on a χ -test, with a β-value of 50 %, for N numbers of paired
v
measurements)
N number of paired samples in parallel measurements
P percentage value
s
standard deviation of the AMS used in QAL3
AMS
s standard deviation of the differences D in parallel measurements
D i
t value of the t distribution for a significance level of 95 % and a number of degrees of freedom
0,95; N–1
of N – 1
u uncertainty due to instability (expressed as a standard deviation)
inst
u uncertainty due to influence of temperature (expressed as a standard deviation)
temp
u uncertainty due to influence of pressure (expressed as a standard deviation)
pres
u uncertainty due to influence of voltage (expressed as a standard deviation)
volt
u any other uncertainty that may influence the zero and span reading (expressed as a standard
others
deviation)
th
x i measured signal obtained with the AMS at AMS measuring conditions
i
x
average of AMS measured signals x
i
th
y
i measured value obt
...
INTERNATIONAL ISO
STANDARD 20181
First edition
2023-02
Stationary source emissions — Quality
assurance of automated measuring
systems
Émission des sources fixes — Assurance qualité des systèmes
automatiques de mesurage
Reference number
ISO 20181:2023(E)
© ISO 2023
---------------------- Page: 1 ----------------------
ISO 20181:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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 2023 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 20181:2023(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.6
4.1 Symbols . 6
4.2 Abbreviated terms . 7
5 Principle . 7
5.1 General . 7
5.2 Limitations . 9
5.3 Measurement site and installation . 9
5.4 Testing laboratories performing SRM measurements . 10
6 Calibration and validation of the AMS (QAL2) .10
6.1 General . 10
6.2 Functional test . 11
6.3 Parallel measurements with the SRM .12
6.4 Data evaluation . 14
6.4.1 Preparation of data . 14
6.4.2 Selection of data points from automated SRM . 15
6.4.3 Establishing the calibration function . 15
6.5 Calibration function of the AMS and its validity . 16
6.6 Calculation of variability . 18
6.7 Test of variability . 19
6.8 QAL2 report . . 19
7 Ongoing quality assurance during operation (QAL3) .20
7.1 General . 20
7.2 Procedures to maintain ongoing quality . 21
7.3 Choosing control charts . 21
7.4 Control chart limits . 22
7.4.1 General .22
7.4.2 Calculation of control chart limits using performance data .22
7.4.3 Calculation of control chart limits using the maximum permissible
uncertainty .23
7.5 Zero and span measurements .23
7.5.1 General .23
7.5.2 Frequency of zero and span measurements .23
7.5.3 Extractive gas analysis systems . 24
7.5.4 In-situ gas-monitoring AMS . 24
7.5.5 Particulate-monitoring AMS . 25
7.6 Documentation of control charts . 25
8 Annual surveillance test (AST).25
8.1 General . 25
8.2 Functional test . 26
8.3 Parallel measurements with the SRM . 26
8.4 Data evaluation . 27
8.5 Calculation of variability .28
8.6 Test of variability and validity of the calibration function .28
8.7 AST report .29
9 Documentation .29
iii
© ISO 2023 – All rights reserved
---------------------- Page: 3 ----------------------
ISO 20181:2023(E)
Annex A (normative) QAL2 and AST functional test of AMS .30
Annex B (normative) Test of linearity .34
Annex C (informative) Control charts .36
Annex D (normative) Documentation .46
Annex E (informative) Examples of calculation of the calibration function and of the
variability test .48
Annex F (informative) Example of calculation of the standard deviation s of the AMS at
AMS
zero and span level .63
Annex G (informative) Example of using the calibration function and testing the variability
and validity of the calibration function in the AST .66
Annex H (informative) Implementation of QAL1 .70
Annex I (normative) k and t values .71
v 0,95; N–1
Annex J (informative) Significant technical changes .72
Bibliography .74
iv
© ISO 2023 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 20181:2023(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 the European Committee for Standardization (CEN) (as EN 14181:2014)
and was adopted, without modification by Technical Committee ISO/TC 146, Air quality, Subcommittee
SC 1, Stationary source emission.
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.
v
© ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
ISO 20181:2023(E)
Introduction
This document describes the quality assurance procedures needed to ensure that an automated
measuring system (AMS) installed to measure emissions to air are capable of meeting the uncertainty
[1],[2],[3]
requirements on measured values e.g. given by legislation or more generally by competent
authorities.
Three different quality assurance levels (QAL1, QAL2, and QAL3) are defined to achieve this objective.
These quality assurance levels cover the suitability of an AMS for its measuring task (e.g. before or
during the purchase period of the AMS), the validation of the AMS following its installation, and the
control of the AMS during its ongoing operation on an industrial plant. An annual surveillance test
(AST) is also defined.
The suitability evaluation (QAL1) of the AMS and its measuring procedure are described in EN 15267-
3 and ISO 14956 where a methodology is given for calculating the total uncertainty of AMS measured
values. This total uncertainty is calculated from the evaluation of all the uncertainty components
arising from its individual performance characteristics that contribute.
vi
© ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 20181:2023(E)
Stationary source emissions — Quality assurance of
automated measuring systems
1 Scope
This document specifies procedures for establishing quality assurance levels (QAL) for automated
measuring systems (AMS) installed on industrial plants for the determination of the flue gas
components and other flue gas parameters.
This document specifies:
— a procedure (QAL2) to calibrate the AMS and determine the variability of the measured values
obtained by it, so as to demonstrate the suitability of the AMS for its application, following its
installation;
— a procedure (QAL3) to maintain and demonstrate the required quality of the measurement results
during the normal operation of an AMS, by checking that the zero and span characteristics are
consistent with those determined during QAL1;
— a procedure for the annual surveillance tests (AST) of the AMS in order to evaluate (i) that it functions
correctly and its performance remains valid and (ii) that its calibration function and variability
remain as previously determined.
This document is designed to be used after the AMS has been certified in accordance with the series of
documents EN 15267.
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.
EN 15259:2007, Air quality — Measurement of stationary source emissions — Requirements for
measurement sections and sites and for the measurement objective, plan and report
EN 15267-1, Air quality — Certification of automated measuring systems — Part 1: General principles
EN 15267-2, Air quality — Certification of automated measuring systems — Part 2: Initial assessment of the
AMS manufacturer’s quality management system and post certification surveillance for the manufacturing
process
EN 15267-3, Air quality — Certification of automated measuring systems — Part 3: Performance criteria
and test procedures for automated measuring systems for monitoring emissions from stationary sources
ISO 14956, Air quality — Evaluation of the suitability of a measurement procedure by comparison with a
required measurement uncertainty
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
1
© ISO 2023 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 20181:2023(E)
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
automated measuring system
AMS
measuring system permanently installed on site for continuous monitoring of emissions or
measurement of peripheral parameters
Note 1 to entry: An AMS is a method which is traceable to a reference method.
Note 2 to entry: Apart from the analyser, an AMS includes facilities for taking samples (e.g. sample probe, sample
gas lines, flow meters, regulators, delivery pumps) and for sample conditioning (e.g. dust filter, water vapour
removal devices, converters, diluters). This definition also includes testing and adjusting devices that are
required for regular functional checks.
3.2
extractive AMS
AMS having the detection unit physically separated from the gas stream by means of a sampling system
3.3
in-situ AMS
AMS having the detection unit in the gas stream or in a part of it
3.4
peripheral AMS
AMS used to gather the data required to convert the AMS measured value to standard conditions
Note 1 to entry: A peripheral AMS is used to measure e.g. water vapour, temperature, pressure and oxygen.
3.5
reference method
RM
measurement method taken as a reference by convention, which gives the accepted reference value of
the measurand
[SOURCE: EN 15259:2007]
3.6
standard reference method
SRM
reference method prescribed by European or national legislation
Note 1 to entry: Standard reference methods are used e.g. to calibrate and validate AMS and for periodic
measurements to check compliance with limit values.
[SOURCE: EN 15259:2007]
3.7
peripheral SRM
SRM used to gather the data required to convert the SRM measured values to AMS or standard
conditions
Note 1 to entry: A peripheral SRM is used to measure e.g. water vapour, temperature, pressure and oxygen.
3.8
standard conditions
conditions to which measured values have to be standardized to verify compliance with emission limit
values
[1] [2] [3]
Note 1 to entry: Standard conditions are specified e.g. in EU Directives , and .
2
© ISO 2023 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 20181:2023(E)
3.9
emission limit value
ELV
limit value related to the maximum permissible uncertainty
[1] [2] [3]
Note 1 to entry: For the EU Directives , and it is the daily emission limit value that relates to the uncertainty
requirement.
3.10
maximum permissible uncertainty
uncertainty requirement on AMS measured values given by legislation or competent authorities
3.11
legislation
directives, acts, ordinances or regulations
3.12
competent authority
organization or organizations which implement the requirements of EU Directives and regulate
installations which shall comply with the requirements of this document
3.13
calibration function
linear relationship between the values of the SRM and the AMS with the assumption of a constant
residual standard deviation
Note 1 to entry: For dust measuring AMS, a quadratic calibration function can be used as described in EN 13284-
2.
3.14
standard deviation
positive square root of the mean squared deviation from the arithmetic mean divided by the number of
degrees of freedom
Note 1 to entry: The number of degrees of freedom is the number of measurements minus 1.
3.15
confidence interval
interval estimator (T , T ) for the parameter θ with the statistics T and T as interval limits and for
1 2 1 2
which it holds that P[T < θ < T ] ≥ (1 – α)
1 2
[SOURCE: ISO 3534-1:2006]
Note 1 to entry: The two-sided 95 % confidence interval of a normal distribution is illustrated in Figure 1, where:
T = Θ – 1,96 σ is the lower 95 % confidence limit;
1 0
T = Θ + 1,96 σ is the upper 95 % confidence limit;
2 0
I = T – T = 2 × 1,96 × σ is the length of the 95 % confidence interval;
2 1 0
σ = I / (2 × 1,96) is the standard deviation associated with a 95 % confidence interval;
0
n is the number of observed values;
f is the frequency;
m is the measured value.
3
© ISO 2023 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 20181:2023(E)
Figure 1 — Illustration of the 95 % confidence interval of a normal distribution
In this document, the standard deviation σ is estimated in QAL2 by parallel measurements with
0
the SRM. It is assumed that the requirement for σ , presented in terms of a maximum permissible
0
uncertainty, is provided by the regulators (e.g. in some EU Directives). In the procedures of this
standard, the premise is that the maximum permissible uncertainty is given as σ itself, or as a quarter
0
of the length of the full 95 % confidence interval
Note 2 to entry: In some EU Directives (see [1],[2],[3]) the uncertainty of the AMS measured values is expressed
as half of the length of a 95 % confidence interval as a percentage P of the emission limit value E. Then, in order to
convert this uncertainty to a standard deviation, the appropriate conversion factor is σ =PE /, 196 .
0
3.16
variability
standard deviation of the differences of parallel measurements between the SRM and AMS
3.17
uncertainty
parameter associated with the result of a measurement that characterizes the dispersion of the values
that could reasonably be attributed to the measurand
[SOURCE: ISO/IEC Guide 98-3:2008]
3.18
measurand
particular quantity subject to measurement
[SOURCE: ISO/IEC Guide 98-3:2008]
Note 1 to entry: A measurand can be e.g. the mass concentration of a measured component or the waste gas
velocity, pressure or temperature.
3.19
measured component
constituent of the waste gas for which a defined measurand is to be determined by measurement
[SOURCE: EN 15259:2007]
3.20
peripheral parameter
specified physical or chemical quantity which is needed for conversion of measured values to specified
conditions
4
© ISO 2023 – All rights reserved
---------------------- Page: 10 ----------------------
ISO 20181:2023(E)
3.21
measured value
estimated value of the measurand derived from a measured signal
Note 1 to entry: This usually involves calculations related to the calibration process and conversion to required
quantities.
Note 2 to entry: A measured value is a short-term average. The averaging time can be e.g. 10 min, 30 min or 1 h.
3.22
instrument reading
measured signal directly provided by the AMS without using the calibration function
3.23
zero reading
instrument reading on simulation of the input parameter at zero concentration
3.24
span reading
instrument reading for a simulation of the input parameter at a fixed elevated concentration
3.25
instability
change in the measured signal comprised of drift and dispersion over a stated maintenance interval
Note 1 to entry: Drift and dispersion specify the monotonic and stochastic change with time of the measured
signal, respectively.
3.26
drift
monotonic change of the calibration function over stated maintenance interval, which results in a
change of the measured signal
3.27
precision
closeness of agreement of results obtained from the AMS for successive zero readings and successive
span readings at defined time intervals
3.28
response time
t
90
time interval between the instant of a sudden change in the value of the input quantity to an AMS and
the time as from which the value of the output quantity is reliably maintained above 90 % of the correct
value of the input quantity
Note 1 to entry: The response time is also referred to as the 90 % time.
3.29
maintenance interval
maximum admissible interval of time for which the performance characteristics will remain within a
predefined range without external servicing, e.g. refill, calibration, adjustment
3.30
reference material
substance or mixture of substances, with a known concentration within specified limits, or a device of
known characteristics
3.31
CUSUM chart
calculation procedure in which the amount of drift and change in precision is compared to the
corresponding uncertainty components which are obtained during QAL1
5
© ISO 2023 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 20181:2023(E)
3.32
EWMA chart
calculation procedure in which the combined amount of drift and change in precision is compared to
the corresponding uncertainty components which are obtained during QAL1
Note 1 to entry: The EWMA chart averages the data in a way that gives less and less weight to data as they are
further removed in time.
4 Symbols and abbreviated terms
4.1 Symbols
a
intercept of the calibration function
best estimate of a
ˆ
a
b
slope of the calibration function
ˆ
best estimate of b
b
D
difference between SRM measured value y and calibrated AMS measured value ˆy
i
i
i
average of D
D
i
E emission limit value
2
k
test value for variability (based on a χ -test, with a β-value of 50 %, for N numbers of paired
v
measurements)
N number of paired samples in parallel measurements
P percentage value
s
standard deviation of the AMS used in QAL3
AMS
s standard deviation of the differences D in parallel measurements
D i
t value of the t distribution for a significance level of 95 % and a number of degrees of freedom
0,95; N–1
of N – 1
u uncertainty due to instability (expressed as a standard deviation)
inst
u uncertainty due to influence of temperature (expressed as a standard deviation)
temp
u uncertainty due to influence of pressure (expressed as a standard deviation)
pres
u uncertainty due to influence of voltage (expressed as a standard deviation)
volt
u any other uncertainty that may influence the zero and span reading (expressed as a standard
others
deviation)
th
x i measured signal obtained with the AMS at AMS measuring conditions
i
x
average of AMS measured signals x
i
th
y
i measured value obtained with the SRM
i
y
average of the SRM measured values y
i
y
SRM measured value y at standard conditions
i ,s
i
6
© ISO 2023 – All rights reserved
---------------------- Page: 12 ----------------------
ISO 20181:2023(E)
y
lowest SRM measured value at standard conditions
s,min
y
highest SRM measured value at standard conditions
s,max
best estimate for the ”true value”, calculated from the AMS measured signal x by means of
ˆ
y
i
i
the calibration function
best estimate for the ”true value”, calculated from the AMS measured signal x at standard
ˆy
i
i,s
conditions
ˆy best estimate for the ”true value”, calculated from the maximum value of the AMS measured
s,max
signals x at standard conditions
i
Z offset (the difference between the AMS zero reading and the zero)
α significance level
ε deviation between y and the expected value
i i
σ
standard deviation associated with the uncertainty derived from requirements of legislat
...
SLOVENSKI STANDARD
oSIST ISO 20181:2023
01-julij-2023
Emisije nepremičnih virov - Zagotavljanje kakovosti avtomatskih merilnih
sistemov
Stationary source emissions - Quality assurance of automated measuring systems
Émission des sources fixes - Assurance qualité des systèmes automatiques de
mesurage
Ta slovenski standard je istoveten z: ISO 20181:2023
ICS:
13.040.40 Emisije nepremičnih virov Stationary source emissions
oSIST ISO 20181:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
oSIST ISO 20181:2023
---------------------- Page: 2 ----------------------
oSIST ISO 20181:2023
INTERNATIONAL ISO
STANDARD 20181
First edition
2023-02
Stationary source emissions — Quality
assurance of automated measuring
systems
Émission des sources fixes — Assurance qualité des systèmes
automatiques de mesurage
Reference number
ISO 20181:2023(E)
© ISO 2023
---------------------- Page: 3 ----------------------
oSIST ISO 20181:2023
ISO 20181:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
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 2023 – All rights reserved
---------------------- Page: 4 ----------------------
oSIST ISO 20181:2023
ISO 20181:2023(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.6
4.1 Symbols . 6
4.2 Abbreviated terms . 7
5 Principle . 7
5.1 General . 7
5.2 Limitations . 9
5.3 Measurement site and installation . 9
5.4 Testing laboratories performing SRM measurements . 10
6 Calibration and validation of the AMS (QAL2) .10
6.1 General . 10
6.2 Functional test . 11
6.3 Parallel measurements with the SRM .12
6.4 Data evaluation . 14
6.4.1 Preparation of data . 14
6.4.2 Selection of data points from automated SRM . 15
6.4.3 Establishing the calibration function . 15
6.5 Calibration function of the AMS and its validity . 16
6.6 Calculation of variability . 18
6.7 Test of variability . 19
6.8 QAL2 report . . 19
7 Ongoing quality assurance during operation (QAL3) .20
7.1 General . 20
7.2 Procedures to maintain ongoing quality . 21
7.3 Choosing control charts . 21
7.4 Control chart limits . 22
7.4.1 General .22
7.4.2 Calculation of control chart limits using performance data .22
7.4.3 Calculation of control chart limits using the maximum permissible
uncertainty .23
7.5 Zero and span measurements .23
7.5.1 General .23
7.5.2 Frequency of zero and span measurements .23
7.5.3 Extractive gas analysis systems . 24
7.5.4 In-situ gas-monitoring AMS . 24
7.5.5 Particulate-monitoring AMS . 25
7.6 Documentation of control charts . 25
8 Annual surveillance test (AST).25
8.1 General . 25
8.2 Functional test . 26
8.3 Parallel measurements with the SRM . 26
8.4 Data evaluation . 27
8.5 Calculation of variability .28
8.6 Test of variability and validity of the calibration function .28
8.7 AST report .29
9 Documentation .29
iii
© ISO 2023 – All rights reserved
---------------------- Page: 5 ----------------------
oSIST ISO 20181:2023
ISO 20181:2023(E)
Annex A (normative) QAL2 and AST functional test of AMS .30
Annex B (normative) Test of linearity .34
Annex C (informative) Control charts .36
Annex D (normative) Documentation .46
Annex E (informative) Examples of calculation of the calibration function and of the
variability test .48
Annex F (informative) Example of calculation of the standard deviation s of the AMS at
AMS
zero and span level .63
Annex G (informative) Example of using the calibration function and testing the variability
and validity of the calibration function in the AST .66
Annex H (informative) Implementation of QAL1 .70
Annex I (normative) k and t values .71
v 0,95; N–1
Annex J (informative) Significant technical changes .72
Bibliography .74
iv
© ISO 2023 – All rights reserved
---------------------- Page: 6 ----------------------
oSIST ISO 20181:2023
ISO 20181:2023(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 the European Committee for Standardization (CEN) (as EN 14181:2014)
and was adopted, without modification by Technical Committee ISO/TC 146, Air quality, Subcommittee
SC 1, Stationary source emission.
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.
v
© ISO 2023 – All rights reserved
---------------------- Page: 7 ----------------------
oSIST ISO 20181:2023
ISO 20181:2023(E)
Introduction
This document describes the quality assurance procedures needed to ensure that an automated
measuring system (AMS) installed to measure emissions to air are capable of meeting the uncertainty
[1],[2],[3]
requirements on measured values e.g. given by legislation or more generally by competent
authorities.
Three different quality assurance levels (QAL1, QAL2, and QAL3) are defined to achieve this objective.
These quality assurance levels cover the suitability of an AMS for its measuring task (e.g. before or
during the purchase period of the AMS), the validation of the AMS following its installation, and the
control of the AMS during its ongoing operation on an industrial plant. An annual surveillance test
(AST) is also defined.
The suitability evaluation (QAL1) of the AMS and its measuring procedure are described in EN 15267-
3 and ISO 14956 where a methodology is given for calculating the total uncertainty of AMS measured
values. This total uncertainty is calculated from the evaluation of all the uncertainty components
arising from its individual performance characteristics that contribute.
vi
© ISO 2023 – All rights reserved
---------------------- Page: 8 ----------------------
oSIST ISO 20181:2023
INTERNATIONAL STANDARD ISO 20181:2023(E)
Stationary source emissions — Quality assurance of
automated measuring systems
1 Scope
This document specifies procedures for establishing quality assurance levels (QAL) for automated
measuring systems (AMS) installed on industrial plants for the determination of the flue gas
components and other flue gas parameters.
This document specifies:
— a procedure (QAL2) to calibrate the AMS and determine the variability of the measured values
obtained by it, so as to demonstrate the suitability of the AMS for its application, following its
installation;
— a procedure (QAL3) to maintain and demonstrate the required quality of the measurement results
during the normal operation of an AMS, by checking that the zero and span characteristics are
consistent with those determined during QAL1;
— a procedure for the annual surveillance tests (AST) of the AMS in order to evaluate (i) that it functions
correctly and its performance remains valid and (ii) that its calibration function and variability
remain as previously determined.
This document is designed to be used after the AMS has been certified in accordance with the series of
documents EN 15267.
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.
EN 15259:2007, Air quality — Measurement of stationary source emissions — Requirements for
measurement sections and sites and for the measurement objective, plan and report
EN 15267-1, Air quality — Certification of automated measuring systems — Part 1: General principles
EN 15267-2, Air quality — Certification of automated measuring systems — Part 2: Initial assessment of the
AMS manufacturer’s quality management system and post certification surveillance for the manufacturing
process
EN 15267-3, Air quality — Certification of automated measuring systems — Part 3: Performance criteria
and test procedures for automated measuring systems for monitoring emissions from stationary sources
ISO 14956, Air quality — Evaluation of the suitability of a measurement procedure by comparison with a
required measurement uncertainty
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
1
© ISO 2023 – All rights reserved
---------------------- Page: 9 ----------------------
oSIST ISO 20181:2023
ISO 20181:2023(E)
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
automated measuring system
AMS
measuring system permanently installed on site for continuous monitoring of emissions or
measurement of peripheral parameters
Note 1 to entry: An AMS is a method which is traceable to a reference method.
Note 2 to entry: Apart from the analyser, an AMS includes facilities for taking samples (e.g. sample probe, sample
gas lines, flow meters, regulators, delivery pumps) and for sample conditioning (e.g. dust filter, water vapour
removal devices, converters, diluters). This definition also includes testing and adjusting devices that are
required for regular functional checks.
3.2
extractive AMS
AMS having the detection unit physically separated from the gas stream by means of a sampling system
3.3
in-situ AMS
AMS having the detection unit in the gas stream or in a part of it
3.4
peripheral AMS
AMS used to gather the data required to convert the AMS measured value to standard conditions
Note 1 to entry: A peripheral AMS is used to measure e.g. water vapour, temperature, pressure and oxygen.
3.5
reference method
RM
measurement method taken as a reference by convention, which gives the accepted reference value of
the measurand
[SOURCE: EN 15259:2007]
3.6
standard reference method
SRM
reference method prescribed by European or national legislation
Note 1 to entry: Standard reference methods are used e.g. to calibrate and validate AMS and for periodic
measurements to check compliance with limit values.
[SOURCE: EN 15259:2007]
3.7
peripheral SRM
SRM used to gather the data required to convert the SRM measured values to AMS or standard
conditions
Note 1 to entry: A peripheral SRM is used to measure e.g. water vapour, temperature, pressure and oxygen.
3.8
standard conditions
conditions to which measured values have to be standardized to verify compliance with emission limit
values
[1] [2] [3]
Note 1 to entry: Standard conditions are specified e.g. in EU Directives , and .
2
© ISO 2023 – All rights reserved
---------------------- Page: 10 ----------------------
oSIST ISO 20181:2023
ISO 20181:2023(E)
3.9
emission limit value
ELV
limit value related to the maximum permissible uncertainty
[1] [2] [3]
Note 1 to entry: For the EU Directives , and it is the daily emission limit value that relates to the uncertainty
requirement.
3.10
maximum permissible uncertainty
uncertainty requirement on AMS measured values given by legislation or competent authorities
3.11
legislation
directives, acts, ordinances or regulations
3.12
competent authority
organization or organizations which implement the requirements of EU Directives and regulate
installations which shall comply with the requirements of this document
3.13
calibration function
linear relationship between the values of the SRM and the AMS with the assumption of a constant
residual standard deviation
Note 1 to entry: For dust measuring AMS, a quadratic calibration function can be used as described in EN 13284-
2.
3.14
standard deviation
positive square root of the mean squared deviation from the arithmetic mean divided by the number of
degrees of freedom
Note 1 to entry: The number of degrees of freedom is the number of measurements minus 1.
3.15
confidence interval
interval estimator (T , T ) for the parameter θ with the statistics T and T as interval limits and for
1 2 1 2
which it holds that P[T < θ < T ] ≥ (1 – α)
1 2
[SOURCE: ISO 3534-1:2006]
Note 1 to entry: The two-sided 95 % confidence interval of a normal distribution is illustrated in Figure 1, where:
T = Θ – 1,96 σ is the lower 95 % confidence limit;
1 0
T = Θ + 1,96 σ is the upper 95 % confidence limit;
2 0
I = T – T = 2 × 1,96 × σ is the length of the 95 % confidence interval;
2 1 0
σ = I / (2 × 1,96) is the standard deviation associated with a 95 % confidence interval;
0
n is the number of observed values;
f is the frequency;
m is the measured value.
3
© ISO 2023 – All rights reserved
---------------------- Page: 11 ----------------------
oSIST ISO 20181:2023
ISO 20181:2023(E)
Figure 1 — Illustration of the 95 % confidence interval of a normal distribution
In this document, the standard deviation σ is estimated in QAL2 by parallel measurements with
0
the SRM. It is assumed that the requirement for σ , presented in terms of a maximum permissible
0
uncertainty, is provided by the regulators (e.g. in some EU Directives). In the procedures of this
standard, the premise is that the maximum permissible uncertainty is given as σ itself, or as a quarter
0
of the length of the full 95 % confidence interval
Note 2 to entry: In some EU Directives (see [1],[2],[3]) the uncertainty of the AMS measured values is expressed
as half of the length of a 95 % confidence interval as a percentage P of the emission limit value E. Then, in order to
convert this uncertainty to a standard deviation, the appropriate conversion factor is σ =PE /, 196 .
0
3.16
variability
standard deviation of the differences of parallel measurements between the SRM and AMS
3.17
uncertainty
parameter associated with the result of a measurement that characterizes the dispersion of the values
that could reasonably be attributed to the measurand
[SOURCE: ISO/IEC Guide 98-3:2008]
3.18
measurand
particular quantity subject to measurement
[SOURCE: ISO/IEC Guide 98-3:2008]
Note 1 to entry: A measurand can be e.g. the mass concentration of a measured component or the waste gas
velocity, pressure or temperature.
3.19
measured component
constituent of the waste gas for which a defined measurand is to be determined by measurement
[SOURCE: EN 15259:2007]
3.20
peripheral parameter
specified physical or chemical quantity which is needed for conversion of measured values to specified
conditions
4
© ISO 2023 – All rights reserved
---------------------- Page: 12 ----------------------
oSIST ISO 20181:2023
ISO 20181:2023(E)
3.21
measured value
estimated value of the measurand derived from a measured signal
Note 1 to entry: This usually involves calculations related to the calibration process and conversion to required
quantities.
Note 2 to entry: A measured value is a short-term average. The averaging time can be e.g. 10 min, 30 min or 1 h.
3.22
instrument reading
measured signal directly provided by the AMS without using the calibration function
3.23
zero reading
instrument reading on simulation of the input parameter at zero concentration
3.24
span reading
instrument reading for a simulation of the input parameter at a fixed elevated concentration
3.25
instability
change in the measured signal comprised of drift and dispersion over a stated maintenance interval
Note 1 to entry: Drift and dispersion specify the monotonic and stochastic change with time of the measured
signal, respectively.
3.26
drift
monotonic change of the calibration function over stated maintenance interval, which results in a
change of the measured signal
3.27
precision
closeness of agreement of results obtained from the AMS for successive zero readings and successive
span readings at defined time intervals
3.28
response time
t
90
time interval between the instant of a sudden change in the value of the input quantity to an AMS and
the time as from which the value of the output quantity is reliably maintained above 90 % of the correct
value of the input quantity
Note 1 to entry: The response time is also referred to as the 90 % time.
3.29
maintenance interval
maximum admissible interval of time for which the performance characteristics will remain within a
predefined range without external servicing, e.g. refill, calibration, adjustment
3.30
reference material
substance or mixture of substances, with a known concentration within specified limits, or a device of
known characteristics
3.31
CUSUM chart
calculation procedure in which the amount of drift and change in precision is compared to the
corresponding uncertainty components which are obtained during QAL1
5
© ISO 2023 – All rights reserved
---------------------- Page: 13 ----------------------
oSIST ISO 20181:2023
ISO 20181:2023(E)
3.32
EWMA chart
calculation procedure in which the combined amount of drift and change in precision is compared to
the corresponding uncertainty components which are obtained during QAL1
Note 1 to entry: The EWMA chart averages the data in a way that gives less and less weight to data as they are
further removed in time.
4 Symbols and abbreviated terms
4.1 Symbols
a
intercept of the calibration function
best estimate of a
ˆ
a
b
slope of the calibration function
ˆ
best estimate of b
b
D
difference between SRM measured value y and calibrated AMS measured value ˆy
i
i
i
average of D
D
i
E emission limit value
2
k
test value for variability (based on a χ -test, with a β-value of 50 %, for N numbers of paired
v
measurements)
N number of paired samples in parallel measurements
P percentage value
s
standard deviation of the AMS used in QAL3
AMS
s standard deviation of the differences D in parallel measurements
D i
t value of the t distribution for a significance level of 95 % and a number of degrees of freedom
0,95; N–1
of N – 1
u uncertainty due to instability (expressed as a standard deviation)
inst
u uncertainty due to influence of temperature (expressed as a standard deviation)
temp
u uncertainty due to influence of pressure (expressed as a standard deviation)
pres
u uncertainty due to influence of voltage (expressed as a standard deviation)
volt
u any other uncertainty that may influence the zero and span reading (expressed as a standard
others
deviation)
th
x i measured signal obtained with the AMS at AMS measuring conditions
i
x
average of AMS measured signals x
i
th
y
i measure
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.