SIST 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
Ta dokument je kot standard EN 14181:2014 pripravil Evropski odbor za standardizacijo (CEN), sprejet pa je bil brez sprememb.
Ta dokument določa postopke za vzpostavitev ravni zagotavljanja kakovosti (QAL) za avtomatske merilne sisteme, nameščene v industrijskih obratih za ugotavljanje komponent dimnega plina in drugih parametrov dimnega plina.
Ta dokument določa:
– postopek (QAL2) za kalibriranje avtomatskega merilnega sistema in ugotavljanje variabilnosti z njim pridobljenih izmerjenih vrednosti, da se dokaže primernost avtomatskega merilnega sistema za uporabo po njegovi namestitvi;
– postopek (QAL3) za vzdrževanje in dokazovanje potrebne kakovosti rezultatov meritev med običajnim delovanjem avtomatskega merilnega sistema s preverjanjem, da so značilnosti ničelne točke in merilnega območja skladne z značilnostmi, ki so ugotovljene med postopkom QAL1;
– postopek za letne nadzorne teste (AST) avtomatskega merilnega sistema, s katerimi se oceni, (i) ali pravilno deluje in daje veljavne rezultate ter (ii) ali sta njegova funkcija kalibracije in variabilnost še vedno v stanju, kot je bilo predhodno ugotovljeno.
Ta dokument se uporablja po certifikaciji avtomatskega merilnega sistema v skladu s serijo dokumentov EN 15267.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii
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
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
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
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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
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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
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
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
— 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 .
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;
n is the number of observed values;
f is the frequency;
m is the measured value.
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
the SRM. It is assumed that the requirement for σ , presented in terms of a maximum permissible
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
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 .
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
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
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
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
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
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 legislation
4.2 Abbreviated terms
AMS automated measuring system
AST annual surveillance test
CUSUM cumulative sum
DAHS data acquisition and handling system
ELV emission limit value
EWMA exponentially weighted moving-average
QA quality assurance
QAL quality assurance level
QAL1 first quality assurance level
QAL2 second quality assurance level
QAL3 third quality assurance level
QC quality control
SRM standard reference method
5 Principle
5.1 General
An AMS to be used at installations shall have been proven suitable for its measuring task (parameter
and composition of the flue gas) by use of the QAL1 procedure, as specified by EN 15267-1 EN 15267-
2, EN 15267-3 and ISO 14956. Using these standards, it shall be proven that the total uncertainty of
the results obtained from the AMS meets the specification for uncertainty stated in the applicable
regulations. In QAL1 the total uncertainty required by the applicable regulation is calculated by
summing in an appropriate manner all the relevant uncertainty components arising from the individual
performance characteristics.
In case of new installations of AMS, the AMS shall have been certified in accordance with EN 15267-1,
EN 15267-2, and EN 15267-3.
In case of AMS already installed at plants which have not been certified according to EN 15267-1,
EN 15267-2, and EN 15267-3, or AMS already installed at plants which were certified according to
EN 15267-1, EN 15267-2, and EN 15267-3 but where the ELV and the uncertainty requirement have
subsequently changed, the procedure described in H.2 may be applied. However, H.2 does not apply to
new installations of old AMS which have not been certified according to EN 15267-1, EN 15267-2 and
EN 15267-3.
NOTE 1 SRM measurements, influences by peripheral parameters and the sampling site can contribute to the
uncertainty of the AMS measured values determined in QAL2.
NOTE 2 EN 15267-3 requires that the total uncertainty of the AMS measured values determined in the
performance test should be at least 25 % below the maximum permissible uncertainty specified e.g. in applicable
regulations to provide a sufficient margin for the uncertainty contributions from the individual installation of
the AMS to pass QAL2 and QAL3 successfully.
The QAL2 and AST procedures involve testing laboratories, whereas the QAL3 procedures involve the
plant operators.
QAL2 is a procedure for the determination of the calibration function and its variability, and a test of the
variability of the measured values of the AMS compared with the maximum permissible uncertainty
given by legislation. The QAL2 tests are performed on suitable AMS that have been correctly installed
and commissioned. A calibration function is established from the results of a number of parallel
measurements performed with the standard reference method (SRM). The variability of the measured
values obtained with the AMS is then evaluated against the maximum permissible uncertainty.
The QAL2 procedures are repeated periodically, after a major change of plant operation, after a failure
of the AMS or as required by legislation.
QAL3 is a procedure which is used to check drift and precision in order to demonstrate that the AMS
is in control during its operation so that it continues to function within the required specifications for
uncertainty. This is achieved by conducting periodic zero and span checks on the AMS – based on those
used in the procedure for zero and span repeatability tests carried out in QAL1 – and then evaluating
the results obtained using control charts. Zero and span adjustments or maintenance of the AMS, may
be necessary depending on the results of this evaluation.
The AST is a procedure which is used to evaluate whether the uncertainty of the measured values
obtained from the AMS still meet the uncertainty criteria – as demonstrated in the previous QAL2 test.
It also determines whether the calibration function obtained during the previous QAL2 test is still valid.
The validity of the measured values obtained with the AMS is checked by means of a series of functional
tests as well as by the performance of a limited number of parallel measurements using an appropriate
SRM.
NOTE 3 There are several concentration ranges relevant to the application of this document:
— certification range
This is the range over which the AMS has been certified. It is generally recommended that this range be related to
the ELV given in relevant EU Directives of the processes under which the AMS will be used. EN 15267-3 requires
that the certification range be no greater than 1,5 times the daily ELV for waste incineration plants and 2,5 times
the daily ELV for large combustion plants. Where there is a choice, the daily ELV is used.
— calibration range
This is the range over which the AMS has been calibrated under the QAL2 procedure.
— measuring range
This is the range at which the AMS is set to operate during use. There are usually requirements from national
competent authorities that the range encompasses the maximum short-term ELV. The measuring range can be
greater than the certification range.
5.2 Limitations
Figure 2 illustrates the components of the AMS covered by this document.
Figure 2 — Limits for the QA of the AMS excluding the data acquisition and handling system
NOTE 1 The influence of the uncertainty of the measurement results, which arise from the data acquisition
and handling system of the AMS or of the plant system, and its determination, are not covered by this standard.
NOTE 2 The performance of the data acquisition and handling system (DAHS) can be as influential as the AMS
performance in determining the quality of the results obtained from the whole measuring system/process. There
are different requirements for data collection, recording and presentation in different countries. A document on
quality assurance of DAHS is currently under preparation.
When conducting parallel measurements, the measured signals from the AMS shall be taken directly
from the AMS (e.g. expressed as analogue or digital signal) during the QAL2 and AST procedures
specified in this standard, by using an independent data collection system provided by the
organization(s) carrying out the QAL2 and AST tests. All data shall be recorded in their uncorrected
form (without corrections e.g. for temperature and oxygen). A plant data collection system with ongoing
quality control can alternatively be used to collect the measured signal from the AMS.
5.3 Measurement site and installation
The AMS shall be installed in accordance with the requirements of the relevant European and/or
international standards. Special attention shall be given to ensure that the AMS is readily accessible for
regular maintenance and other necessary activities.
The AMS should be positioned as far as practical in a position where it measures a sample that
is representative of the stack gas composition. EN 15259 describes a procedure to identify the best
sampling location for the AMS, in order to provide representative measurements. It also defines the
optimum location for undertaking parallel SRM measurements for the QAL2.
All measurements shall be carried out on a suitable AMS and peripheral AMS installed within an
appropriate working environment.
The working platform used to access the AMS and the working platform used to perform the SRM
measurements shall be in accordance with the requirements of EN 15259. The sampling ports for
measurements with the SRM shall be placed in such a location to avoid mutual interference between
SRM and AMS in order to achieve comparable measurements between AMS and SRM.
NOTE Lack in the fulfilment of these conditions can result in higher measurement uncertainties, potentially
resulting in nonconformity with the requirements given by EU Directives.
It is necessary to have good access to the AMS to enable inspections to take place and also to minimize
the time taken to implement the quality assurance procedures of this standard. A clean, well-ventilated
and well-lit working space around the AMS is required to enable the staff to perform this work
effectively. Suitable protection is required for the personnel and the equipment, if the working platform
is exposed to the weather.
5.4 Testing laboratories performing SRM measurements
The testing laboratories performing the measurements with the SRM shall be accredited for this task
according to ISO/IEC 17025, or shall be approved directly by the relevant competent authority.
NOTE CEN/TS 15675 provides clarification and additional information on the application of ISO/IEC 17025
to periodic measurements used e.g. for the calibration of AMS.
6 Calibration and validation of the AMS (QAL2)
6.1 General
QAL2 covers the following items:
— functional test of the AMS including check of correct installation;
— parallel measurements with the SRM;
— data evaluation;
— determination of the calibration function of the AMS and its range of validity;
— calculation of variability of the AMS measured values;
— test of variability of the AMS measured values;
— reporting.
The sequence of the combined tests is shown in Figure 3.
Figure 3 — Flow diagram for the calibration and variability tests
A QAL2 procedure shall be performed for all measurands:
— at least every 5 years for every AMS or more frequently if so required by legislation or by the
competent authority;
Furthermore, a QAL2 shall be performed for all the measurands influenced by:
— any major change in plant operation (e.g. change in flue gas abatement system or change of fuel), or
— any major changes or repairs to the AMS, which will influence the results obtained significantly.
The results of QAL2 shall be implemented within six months after the changes. During the period before
a new calibration function has been established the previous calibration function (where necessary
with extrapolation) shall be used.
NOTE In some EU member countries the local authorities allow in individual cases the continued use
of the previous calibration function if it can be proven by use of a specified statistical procedure that the new
calibration function does not significantly differ from the previous one.
Examples of calculation of the calibration function and of the variability test are given in Annex E.
6.2 Functional test
The requirements for installation and the measurement site as specified in 5.3 shall be fulfilled.
Before calibration (see 6.3 and 6.5) and the test for variability (see 6.6 and 6.7) are performed, it shall
be proven that the AMS is commissioned satisfactorily, e.g. as specified by the AMS supplier and/or
manufacturer. It shall also be shown and documented that the AMS gives a zero reading on a zero
concentration.
NOTE For some AMS it is difficult to achieve a zero reading. In those situations, the AMS can be removed
from the stack, and zeroed using a test bench or similar. As an alternative, a measuring path, which enables this
zero test to be carried out, can be installed in the stack.
The functional test before calibration shall be performed according to Annex A. It is recommended to
perform the functional test not more than one month before parallel measurements are started. The
functional test shall be performed by an experienced testing laboratory, which has been recognized by
the competent authority.
The specific precautions to be taken should depend on the individual location. Special attention should
be made for particulate measurements.
Since the AMS and SRM measured values are converted to standard conditions by independently
determined data sets of the peripheral parameters, the uncertainties in the peripheral parameters
are attributed to the AMS of the air pollutant in the variability test. Therefore, it is recommended to
perform the relevant steps of the functional test specified in Annex A for measuring systems of the
peripheral parameters to minimize uncertainties caused by the peripheral parameters.
6.3 Parallel measurements with the SRM
Parallel measurements shall be performed with the AMS and SRM in order to calibrate and validate the
AMS by use of an independent method.
It is not sufficient to use reference materials alone to obtain the calibration functions and this is therefore
not permitted. This is because these reference materials do not replicate sufficiently the matrix stack
gas, they cannot be used to establish that the sampling point(s) of the AMS are representative, and
they are not used with the sampling system in all cases. However, if there are limited variations in the
results obtained in the AMS/SRM tests, and the measured concentrations are well below the ELV, an
extrapolation of the calibration function to the ELV may be verified by the use of appropriate reference
materials, taking into account the effects of interfering substances on the AMS, where appropriate.
If clear and distinct operating modes of the plant process are part of its normal operation (for example
changes of fuel), additional calibrations shall be performed and a calibration function established for
each operational mode.
NOTE 1 It can be possible to establish one calibration function fulfilling the variability requirements that
covers the range of conditions within which the plant operates.
In order to ensure that the calibration fun
...
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 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.
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Phone: +41 22 749 01 11
Email: copyright@iso.org
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Published in Switzerland
ii
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
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
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
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
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
— 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 .
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;
n is the number of observed values;
f is the frequency;
m is the measured value.
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
the SRM. It is assumed that the requirement for σ , presented in terms of a maximum permissible
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
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 .
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
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
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
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
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
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 legislation
4.2 Abbreviated terms
AMS automated measuring system
AST annual surveillance test
CUSUM cumulative sum
DAHS data acquisition and handling system
ELV emission limit value
EWMA exponentially weighted moving-average
QA quality assurance
QAL quality assurance level
QAL1 first quality assurance level
QAL2 second quality assurance level
QAL3 third quality assurance level
QC quality control
SRM standard reference method
5 Principle
5.1 General
An AMS to be used at installations shall have been proven suitable for its measuring task (parameter
and composition of the flue gas) by use of the QAL1 procedure, as specified by EN 15267-1 EN 15267-
2, EN 15267-3 and ISO 14956. Using these standards, it shall be proven that the total uncertainty of
the results obtained from the AMS meets the specification for uncertainty stated in the applicable
regulations. In QAL1 the total uncertainty required by the applicable regulation is calculated by
summing in an appropriate manner all the relevant uncertainty components arising from the individual
performance characteristics.
In case of new installations of AMS, the AMS shall have been certified in accordance with EN 15267-1,
EN 15267-2, and EN 15267-3.
In case of AMS already installed at plants which have not been certified according to EN 15267-1,
EN 15267-2, and EN 15267-3, or AMS already installed at plants which were certified according to
EN 15267-1, EN 15267-2, and EN 15267-3 but where the ELV and the uncertainty requirement have
subsequently changed, the procedure described in H.2 may be applied. However, H.2 does not apply to
new installations of old AMS which have not been certified according to EN 15267-1, EN 15267-2 and
EN 15267-3.
NOTE 1 SRM measurements, influences by peripheral parameters and the sampling site can contribute to the
uncertainty of the AMS measured values determined in QAL2.
NOTE 2 EN 15267-3 requires that the total uncertainty of the AMS measured values determined in the
performance test should be at least 25 % below the maximum permissible uncertainty specified e.g. in applicable
regulations to provide a sufficient margin for the uncertainty contributions from the individual installation of
the AMS to pass QAL2 and QAL3 successfully.
The QAL2 and AST procedures involve testing laboratories, whereas the QAL3 procedures involve the
plant operators.
QAL2 is a procedure for the determination of the calibration function and its variability, and a test of the
variability of the measured values of the AMS compared with the maximum permissible uncertainty
given by legislation. The QAL2 tests are performed on suitable AMS that have been correctly installed
and commissioned. A calibration function is established from the results of a number of parallel
measurements performed with the standard reference method (SRM). The variability of the measured
values obtained with the AMS is then evaluated against the maximum permissible uncertainty.
The QAL2 procedures are repeated periodically, after a major change of plant operation, after a failure
of the AMS or as required by legislation.
QAL3 is a procedure which is used to check drift and precision in order to demonstrate that the AMS
is in control during its operation so that it continues to function within the required specifications for
uncertainty. This is achieved by conducting periodic zero and span checks on the AMS – based on those
used in the procedure for zero and span repeatability tests carried out in QAL1 – and then evaluating
the results obtained using control charts. Zero and span adjustments or maintenance of the AMS, may
be necessary depending on the results of this evaluation.
The AST is a procedure which is used to evaluate whether the uncertainty of the measured values
obtained from the AMS still meet the uncertainty criteria – as demonstrated in the previous QAL2 test.
It also determines whether the calibration function obtained during the previous QAL2 test is still valid.
The validity of the measured values obtained with the AMS is checked by means of a series of functional
tests as well as by the performance of a limited number of parallel measurements using an appropriate
SRM.
NOTE 3 There are several concentration ranges relevant to the application of this document:
— certification range
This is the range over which the AMS has been certified. It is generally recommended that this range be related to
the ELV given in relevant EU Directives of the processes under which the AMS will be used. EN 15267-3 requires
that the certification range be no greater than 1,5 times the daily ELV for waste incineration plants and 2,5 times
the daily ELV for large combustion plants. Where there is a choice, the daily ELV is used.
— calibration range
This is the range over which the AMS has been calibrated under the QAL2 procedure.
— measuring range
This is the range at which the AMS is set to operate during use. There are usually requirements from national
competent authorities that the range encompasses the maximum short-term ELV. The measuring range can be
greater than the certification range.
5.2 Limitations
Figure 2 illustrates the components of the AMS covered by this document.
Figure 2 — Limits for the QA of the AMS excluding the data acquisition and handling system
NOTE 1 The influence of the uncertainty of the measurement results, which arise from the data acquisition
and handling system of the AMS or of the plant system, and its determination, are not covered by this standard.
NOTE 2 The performance of the data acquisition and handling system (DAHS) can be as influential as the AMS
performance in determining the quality of the results obtained from the whole measuring system/process. There
are different requirements for data collection, recording and presentation in different countries. A document on
quality assurance of DAHS is currently under preparation.
When conducting parallel measurements, the measured signals from the AMS shall be taken directly
from the AMS (e.g. expressed as analogue or digital signal) during the QAL2 and AST procedures
specified in this standard, by using an independent data collection system provided by the
organization(s) carrying out the QAL2 and AST tests. All data shall be recorded in their uncorrected
form (without corrections e.g. for temperature and oxygen). A plant data collection system with ongoing
quality control can alternatively be used to collect the measured signal from the AMS.
5.3 Measurement site and installation
The AMS shall be installed in accordance with the requirements of the relevant European and/or
international standards. Special attention shall be given to ensure that the AMS is readily accessible for
regular maintenance and other necessary activities.
The AMS should be positioned as far as practical in a position where it measures a sample that
is representative of the stack gas composition. EN 15259 describes a procedure to identify the best
sampling location for the AMS, in order to provide representative measurements. It also defines the
optimum location for undertaking parallel SRM measurements for the QAL2.
All measurements shall be carried out on a suitable AMS and peripheral AMS installed within an
appropriate working environment.
The working platform used to access the AMS and the working platform used to perform the SRM
measurements shall be in accordance with the requirements of EN 15259. The sampling ports for
measurements with the SRM shall be placed in such a location to avoid mutual interference between
SRM and AMS in order to achieve comparable measurements between AMS and SRM.
NOTE Lack in the fulfilment of these conditions can result in higher measurement uncertainties, potentially
resulting in nonconformity with the requirements given by EU Directives.
It is necessary to have good access to the AMS to enable inspections to take place and also to minimize
the time taken to implement the quality assurance procedures of this standard. A clean, well-ventilated
and well-lit working space around the AMS is required to enable the staff to perform this work
effectively. Suitable protection is required for the personnel and the equipment, if the working platform
is exposed to the weather.
5.4 Testing laboratories performing SRM measurements
The testing laboratories performing the measurements with the SRM shall be accredited for this task
according to ISO/IEC 17025, or shall be approved directly by the relevant competent authority.
NOTE CEN/TS 15675 provides clarification and additional information on the application of ISO/IEC 17025
to periodic measurements used e.g. for the calibration of AMS.
6 Calibration and validation of the AMS (QAL2)
6.1 General
QAL2 covers the following items:
— functional test of the AMS including check of correct installation;
— parallel measurements with the SRM;
— data evaluation;
— determination of the calibration function of the AMS and its range of validity;
— calculation of variability of the AMS measured values;
— test of variability of the AMS measured values;
— reporting.
The sequence of the combined tests is shown in Figure 3.
Figure 3 — Flow diagram for the calibration and variability tests
A QAL2 procedure shall be performed for all measurands:
— at least every 5 years for every AMS or more frequently if so required by legislation or by the
competent authority;
Furthermore, a QAL2 shall be performed for all the measurands influenced by:
— any major change in plant operation (e.g. change in flue gas abatement system or change of fuel), or
— any major changes or repairs to the AMS, which will influence the results obtained significantly.
The results of QAL2 shall be implemented within six months after the changes. During the period before
a new calibration function has been established the previous calibration function (where necessary
with extrapolation) shall be used.
NOTE In some EU member countries the local authorities allow in individual cases the continued use
of the previous calibration function if it can be proven by use of a specified statistical procedure that the new
calibration function does not significantly differ from the previous one.
Examples of calculation of the calibration function and of the variability test are given in Annex E.
6.2 Functional test
The requirements for installation and the measurement site as specified in 5.3 shall be fulfilled.
Before calibration (see 6.3 and 6.5) and the test for variability (see 6.6 and 6.7) are performed, it shall
be proven that the AMS is commissioned satisfactorily, e.g. as specified by the AMS supplier and/or
manufacturer. It shall also be shown and documented that the AMS gives a zero reading on a zero
concentration.
NOTE For some AMS it is difficult to achieve a zero reading. In those situations, the AMS can be removed
from the stack, and zeroed using a test bench or similar. As an alternative, a measuring path, which enables this
zero test to be carried out, can be installed in the stack.
The functional test before calibration shall be performed according to Annex A. It is recommended to
perform the functional test not more than one month before parallel measurements are started. The
functional test shall be performed by an experienced testing laboratory, which has been recognized by
the competent authority.
The specific precautions to be taken should depend on the individual location. Special attention should
be made for particulate measurements.
Since the AMS and SRM measured values are converted to standard conditions by independently
determined data sets of the peripheral parameters, the uncertainties in the peripheral parameters
are attributed to the AMS of the air pollutant in the variability test. Therefore, it is recommended to
perform the relevant steps of the functional test specified in Annex A for measuring systems of the
peripheral parameters to minimize uncertainties caused by the peripheral parameters.
6.3 Parallel measurements with the SRM
Parallel measurements shall be performed with the AMS and SRM in order to calibrate and validate the
AMS by use of an independent method.
It is not sufficient to use reference materials alone to obtain the calibration functions and this is therefore
not permitted. This is because these reference materials do not replicate sufficiently the matrix stack
gas, they cannot be used to establish that the sampling point(s) of the AMS are representative, and
they are not used with the sampling system in all cases. However, if there are limited variations in the
results obtained in the AMS/SRM tests, and the measured concentrations are well below the ELV, an
extrapolation of the calibration function to the ELV may be verified by the use of appropriate reference
materials, taking into account the effects of interfering substances on the AMS, where appropriate.
If clear and distinct operating modes of the plant process are part of its normal operation (for example
changes of fuel), additional calibrations shall be performed and a calibration function established for
each operational mode.
NOTE 1 It can be possible to establish one calibration function fulfilling the variability requirements that
covers the range of conditions within which the plant operates.
In order to ensure that the calibration function is valid for the range of conditions within which the
plant will operate, the concentrations during the calibration shall be varied as much as possible within
the normal operations of the plant. This shall ensure that the calibration of the AMS is valid over as
large a range as possible, and also that it covers most operational situations.
NOTE 2 Careful measurement planning can identify the optimum time for the parallel measurements, when
the emissions are at their highest or most varied.
The test for variability shall be performed (see 6.7) for each calibration function, i.e. for each operating
mode of the plant.
The SRM shall be used to sample the emissions at a sampling plane in the duct, which fulfils the
requirements of EN 15259, and is as close as possible to the AMS.
The presence of the SRM equipment shall not influence or disturb the AMS measurements and vice
versa.
NOTE 3 Although EN 15259 allows simplified sampling of gaseous components in cases of homogeneous flue
gas or negligible concentration variations, grid measureme
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