SIST ISO 14385-2:2019
Stationary source emissions - Greenhouse gases - Part 2: Ongoing quality control of automated measuring systems
Stationary source emissions - Greenhouse gases - Part 2: Ongoing quality control of automated measuring systems
This document specifies procedures for establishing quality assurance for automated measuring systems (AMS) installed on industrial plants for the determination of the concentration of greenhouse gases in flue and waste gas and other flue gas parameters. This part of ISO 14385 specifies the following: - a procedure 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 using the relevant procedure in ISO 14956; - a procedure for the annual surveillance tests (AST) of the AMS in order to evaluate a) that it functions correctly and its performance remains valid and b) that its calibration function and variability remain as previously determined. This part of ISO 14385 is designed to be used after the AMS has been accepted according to the procedures specified in ISO 14956. This part of ISO 14385 is restricted to quality assurance (QA) of the AMS and does not include QA of the data collection and recording system of the plant.
Émissions de sources fixes - Gaz à effet de serre - Partie 2: Contrôle qualité continu des systèmes de mesurage automatiques
Emisije nepremičnih virov - Toplogredni plini - 2. del: Zagotavljanje kakovosti avtomatskih merilnih sistemov
Ta dokument določa postopke za vzpostavitev ravni zagotavljanja kakovosti avtomatskih merilnih sistemov (AMS) v industrijskih obratih za določanje koncentracije toplogrednih plinov v dimovodih ter odpadnih plinov in drugih parametrov dimnega plina. Ta del standarda ISO 14385 vključuje: – postopek za vzdrževanje in dokazovanje zahtevane kakovosti rezultatov meritev med normalnim obratovanjem avtomatskega merilnega sistema s preverjanjem, ali so ničelne in razponske značilnosti skladne s tistimi, določenimi z ustreznim postopkom v standardu ISO 14956; – postopek za letne nadzorne preskuse (AST) avtomatskega merilnega sistema, s katerimi se oceni, a) ali pravilno deluje in podaja veljavne rezultate ter b) ali sta njegova funkcija kalibracije in variabilnost še vedno v stanju, kot je bilo predhodno ugotovljeno. Ta del standarda ISO 14385 je zasnovan tako, da se uporablja po tem, ko je avtomatski merilni sistem potrjen in sprejet v skladu s postopki, določenimi v standardu ISO 14956. Ta del standarda ISO 14385 je omejen na zagotavljanje kakovosti avtomatskih merilnih sistemov in ne vključuje zagotavljanja kakovosti zbirke podatkov in sistema za beleženje v obratu.
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INTERNATIONAL ISO
STANDARD 14385-2
First edition
2014-08-01
Stationary source emissions —
Greenhouse gases —
Part 2:
Ongoing quality control of automated
measuring systems
Émissions de sources fixes — Gaz à effet de serre —
Partie 2: Contrôle qualité continu des systèmes de mesurage
automatiques
Reference number
ISO 14385-2:2014(E)
©
ISO 2014
---------------------- Page: 1 ----------------------
ISO 14385-2:2014(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2014
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 14385-2:2014(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviations . 2
4.1 Symbols . 2
4.2 Abbreviations . 2
5 Principle . 3
5.1 General . 3
5.2 Limitations . 3
5.3 Measurement site and installation . 4
5.4 Testing laboratories performing SRM measurements . 4
6 Ongoing quality assurance during operation . 4
6.1 General . 4
6.2 Procedures to maintain ongoing quality . 5
6.3 Choosing control charts . 6
6.4 Setting parameters for control charts . 6
6.5 Zero and span measurements . 8
6.6 Documentation of control charts . 9
6.7 Check on validity of measured values .10
7 Annual surveillance test (AST) .10
7.1 Functional test .10
7.2 Parallel measurements with an SRM .10
7.3 Data evaluation .12
7.4 Calculation of variability .13
7.5 Test of variability and validity of the calibration function .13
7.6 AST report .14
8 Documentation .14
Annex A (normative) AST functional test of AMS .15
Annex B (normative) Test of linearity .19
Annex C (informative) Documentation .21
Annex D (informative) Shewhart control charts .23
Annex E (informative) Exponentially weighted moving average (EWMA) charts .26
Annex F (informative) Example of calculation of the standard deviation σ of the AMS at zero
AMS
and span level .29
Bibliography .32
© ISO 2014 – All rights reserved iii
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ISO 14385-2:2014(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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 146, Air quality, Subcommittee SC 1, Stationary
source emissions.
ISO 14385 consists of the following parts, under the general title Stationary source emissions —
Greenhouse gases:
— Part 1: Calibration of automated measuring systems
— Part 2: Ongoing quality control of automated measuring systems
iv © ISO 2014 – All rights reserved
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ISO 14385-2:2014(E)
Introduction
The measurement of greenhouse gas emissions (carbon dioxide, nitrous oxide, methane) in a framework
of emission trading requires an equal and known quality of data.
This part of ISO 14385 describes the quality assurance procedures for calibration and ongoing quality
control needed to ensure that automated measuring systems (AMS) installed to measure emissions
of greenhouse gases to air are capable of meeting the uncertainty requirements on measured values
specified by legislation, competent authorities, or in an emission trade scheme.
© ISO 2014 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 14385-2:2014(E)
Stationary source emissions — Greenhouse gases —
Part 2:
Ongoing quality control of automated measuring systems
1 Scope
This part of ISO 14385 specifies procedures for establishing quality assurance for automated measuring
systems (AMS) installed on industrial plants for the determination of the concentration of greenhouse
gases in flue and waste gas and other flue gas parameters.
This part of ISO 14385 specifies the following:
— a procedure 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 using the relevant procedure in ISO 14956;
— a procedure for the annual surveillance tests (AST) of the AMS in order to evaluate a) that it functions
correctly and its performance remains valid and b) that its calibration function and variability
remain as previously determined.
This part of ISO 14385 is designed to be used after the AMS has been accepted according to the procedures
specified in ISO 14956.
This part of ISO 14385 is restricted to quality assurance (QA) of the AMS and does not include QA of the
data collection and recording system of the plant.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 14385-1, Stationary source emissions — Greenhouse gases — Part 1: Calibration of automated
measuring systems
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 terms and definitions given in ISO 14385-1 and the following
apply.
3.1
control chart
graphical presentation of the regular recording of the difference of the reading of an instrument or
measuring system, when measuring the pollutant concentration in a gas with known concentration, and
the nominal value of the pollutant concentration in that gas
© ISO 2014 – All rights reserved 1
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ISO 14385-2:2014(E)
4 Symbols and abbreviations
4.1 Symbols
D difference between SRM value y and calibrated AMS measured value ŷ
i i i
average of D
D i
2
k test value for variability (based on a χ -test, with a β-value of 50 %, for N numbers of paired meas-
v
urements)
N number of paired samples in parallel measurements
S standard deviation of the AMS used in ongoing quality control
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 of
0,95; N–1
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 can 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
average of AMS measured signals x
x i
th
y i measured value obtained with the SRM
i
average of the SRM measured values y
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
ŷ best estimate for the “true value”, calculated from the AMS measured signal x by means of the
i i
calibration function
ŷ best estimate for the ”true value”, calculated from the AMS measured signal x at standard condi-
i,s i
tions
ŷ best estimate for the ”true value”, calculated from the maximum value of the AMS measured sig-
s,max
nals x at standard conditions
i
ԑ deviation between y and the expected value
i i
standard deviation associated with the uncertainty derived from requirements of legislation
σ0
4.2 Abbreviations
AMS automated measuring system
AST annual surveillance test
2 © ISO 2014 – All rights reserved
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ISO 14385-2:2014(E)
EWMA chart exponentially weighted moving average chart
QA quality assurance
SRM Standard Reference Method
5 Principle
5.1 General
An AMS to be used shall have been proven suitable for its measuring task (parameter and composition
of the flue gas) by use of the procedures, as specified by ISO 14956. Using this part of ISO 14385, it shall
be proven that the total uncertainty of the results obtained from the AMS meets the specification for
uncertainty stated in legislation or in requirements and specifications established in an international
trading program. In ISO 14956, the total uncertainty required by the relevant regulations is calculated
by summing all the relevant uncertainty components arising from the individual performance.
NOTE It is advisable that uncertainty figures are provided by independent testing bodies.
This part of ISO 14385 provides two procedures.
— 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 of the AMS, based on those
used in the procedure for zero and span repeatability tests according to ISO 14956:2002, and then
evaluating the results obtained using control charts. Zero and span adjustments or maintenance of
the AMS can be necessary, depending on the results of this evaluation.
— A procedure which is used to evaluate whether the measured values obtained from the AMS still
meet the maximum permissible uncertainty criteria, as demonstrated in the calibration procedure
(ISO 14385-1). It also determines whether the calibration function obtained during the calibration
procedure 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.
5.2 Limitations
Figure 2 illustrates the components of the AMS covered by this part of ISO 14385.
Figure 2 — Limits for the QA of the AMS excluding the data acquisition and handling system
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ISO 14385-2:2014(E)
NOTE 1 The influence of the uncertainty of the measurement results, which arise from the data acquisition
recording and handling system of the AMS or of the plant system, and its determination, are excluded from this
part of ISO 14385.
NOTE 2 The performance of the data collection and recording system 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.
When conducting parallel measurements, the measured signals from the AMS are taken directly from
the AMS (e.g. expressed as analogue or digital signal) during the AST procedures specified in this part
of ISO 14385, by using an independent data collection system provided by the organization(s) carrying
out the AST tests. All data shall be recorded in their uncorrected form (without corrections for, e.g.
temperature and oxygen). A plant data collection system with quality control can additionally 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 national or international
standards, as specified by legislation, competent authorities, or in emission trade scheme. Special
attention shall be given to ensure that the AMS is readily accessible for regular maintenance and other
necessary activities.
NOTE The AMS is intended to be positioned as far as practical in a position where it measures a sample,
which is representative of the stack gas composition.
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 shall readily allow parallel measurements to be performed
using an SRM. The sampling ports for measurements with the SRM shall be placed as close as possible,
but not more than three times the equivalent diameter up-stream or down-stream of the location of the
AMS, in order to achieve comparable measurements between AMS and SRM.
It is necessary to have good access to the AMS to enable inspections to take place and also to minimize
time taken to implement the quality assurance procedures of this part of ISO 14385. 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, which perform the measurements with the SRM, shall have an accredited
quality assurance system according to ISO/IEC 17025 or shall be approved directly by the relevant
competent authority. They shall also have sufficient experience in performing the measurements
using the appropriate SRM. The SRM used shall be an international or national standard to ensure the
provision of data of an equivalent scientific quality.
6 Ongoing quality assurance during operation
6.1 General
An AMS can drift or become less precise during routine operation. Drift or instability can be due to,
for example, changes in the AMS, such as contamination of an optical surface, a gradual failure of a
component, or a blockage in a filter. Such changes cause systematic errors in the data from the AMS.
On the other hand, AMS are also subject to short-term variations in stability and precision due to the
influences of factors such as changes in ambient temperature. These variations cause random errors.
The magnitude of the random errors is assessed during the certification process of the AMS.
4 © ISO 2014 – All rights reserved
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ISO 14385-2:2014(E)
After the acceptance and calibration of the AMS, further quality assurance and quality control procedures
shall be followed so as to ensure that the measured values obtained with the AMS meet the stated or
maximum permissible uncertainty on a continuous basis (also described as ongoing quality control). The
implementation and performance of the procedures given in this part of ISO 14385 are the responsibility
of the plant owner (i.e. the owner of the AMS). It is also the responsibility of the plant owner to ensure that
the AMS is operating inside the valid calibration range (see 6.5). The procedures shall be implemented
and be in place at the same time that the collection of emission data by means of the AMS is mandatory
for reporting to the authorities. It is recommended, however, that these procedures commence as soon
as possible after the installation of the AMS in order to gain as much information on the performance of
the AMS as possible. This can begin before the AMS has to be calibrated with the SRM in order to fulfil
the procedure requirements according to ISO 14385-1.
The instrument reading shall reflect the actual drifts in both zero and span readings. Negative instrument
readings at zero level shall be recorded.
For some monitors, it is difficult to achieve a zero and span readings. In those situations, the supplier
shall give instructions on how to achieve readings that reflect the actual drift in zero and span readings,
as demonstrated in the procedures according to ISO 14956, and conforming to the definition of the zero
reading.
6.2 Procedures to maintain ongoing quality
The aim of the procedure is to maintain and demonstrate the quality of the AMS, so that the requirements
for the stated zero and span repeatability and drift values are met during ongoing operation and the AMS
is maintained in the same operational condition as when installed. This shall be achieved by confirming
that the drift and precision determined during the procedures according to ISO 14956 remain under
control. A suitable methodology shall determine the combined drift and precision of the AMS.
The methodology shall identify whether an extra-maintenance (e.g. by the manufacturer) is necessary in
order to adjust the AMS. The procedure uses control charts which plot the drifts (zero and span) against
the time. In this procedure, reference materials are needed. The value of the reference material shall be
known. The drift and precision components obtained from the procedure described in ISO 14956 and
the uncertainty shall be combined and compared against the combined drift and precision obtained in
the field.
Control charts require regular and ideally frequent measurements. The needed frequency of the ongoing
quality control is at least the period of the maintenance interval. In order to extend a maintenance
interval, some AMS suppliers developed automatic checks and adjustments which guarantee very
limited drifts over time. Regular measurements at zero and reference points are the foundations of the
procedure. Using control charts to show trends in the zero and reference point measurements show
each measurement in context and can help prevent the operator from making adjustments to the AMS
only when required.
A frequency of the ongoing quality of at least once every 2 weeks is recommended. Depending on the
results of the zero and span checks, this frequency can be changed.
Therefore, ongoing quality control requires plant operators to have a procedure which describes the
requirements for
— measuring zero and span values,
— plotting these values on control charts, and
— using the control charts to determine whether there are systematic errors, whether the random
errors exceed the acceptable limits established by the implementation requirements in an
international trading scheme.
The following sub-sections describe the following:
— choosing control charts;
© ISO 2014 – All rights reserved 5
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ISO 14385-2:2014(E)
— setting parameters for control charts;
— zero and span measurements;
— documentation and interpretation of the control charts.
6.3 Choosing control charts
6.3.1 General
Any type of control chart, manual or automated, can be used. Different charts have different advantages
and can be more or less complicated to use, depending on the type of chart chosen. This part of ISO 14385
describes two types of chart: the Shewhart chart and the EWMA chart.
6.3.2 Shewhart chart
Shewhart charts simply plot the readings and test them against multiples of S . Its advantage is its
AMS
simplicity; its disadvantage is that the approach is not as sensitive as other approaches such as EWMA
charts. Furthermore, Shewhart charts cannot distinguish between systematic errors and random
errors. Shewhart charts only indicate if the AMS has drifted or whether the precision has worsened.
However, the Shewhart chart method is simple to set up and understand, and it is well suited for manual
procedures.
Annex D describes in detail the procedure for Shewhart chart.
6.3.3 EWMA chart
Compared with the Shewhart chart, the exponentially weighted moving average (EWMA) chart is more
appropriate for early detection of small- or medium-sized maladjustments. It keeps the graphical format
of the Shewhart chart. This approach also implements only one decision rule. The approach also reduces
the risks of unnecessary intervention due to the natural variability of the process.
Annex E describes in detail the procedure for EWMA chart.
6.3.4 Built-in methods
An alternative to an external control chart is to use an instrument built-in method. Many instruments
have a built-in check of zero and span points, and give alarm, if set limits are surpassed.
Some AMS equipped with automatic systems for zero and span checks do not ordinarily output the data
for zero and span drift for plotting on control charts, even though the automatic systems are designed to
achieve the same result as control charts, i.e. measuring drift and alerting the plant operator if the AMS
has drifted out of control. Some systems also automatically adjust the zero and/or the span point in order.
If a plant operator has such a system, it can be accepted as a method for ongoing quality control provided
that an assessment of the total drifts and adjustments are possible during the AMS maintenance by the
AMS supplier and that the information is also accessible to the operator and for third party auditing.
6.4 Setting parameters for control charts
6.4.1 Calculation of the standard deviation S using performance data
AMS
The standard deviation S shall be derived from the information obtained for the calculations
AMS
according to ISO 14956. S shall be calculated considering actual plant conditions and not the test
AMS
conditions during the procedures according to ISO 14956.
For example, during establishing performance characteristics of an instrument testing the influence of
ambient temperature on the AMS could be defined in a range such as 5 °C to 40 °C. However, if the AMS
6 © ISO 2014 – All rights reserved
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ISO 14385-2:2014(E)
is kept in a climate controlled enclosure where the temperature varies from 18 °C to 23 °C, then the
operator uses a temperature variation of 5 °C in the calculation for S .
AMS
S shall be calculated by
AMS
22 22 2
Su=+uu++uu+ (1)
AMSinsttempvoltpresothers
where
u is the uncertainty from instability;
inst
u is the uncertainty relating from variations in ambient temperature;
temp
u is the uncertainty relating from variations in voltage;
volt
u is the uncertainty relating from variations in ambient pressure;
pres
u is any other uncertainty that can influence the reading on zero and span reference
others
material (e.g. dilution).
NOTE 1 S is expressed as a standard deviation; therefore, all above uncertainties are expressed as standard
AMS
de
...
SLOVENSKI STANDARD
SIST ISO 14385-2:2019
01-december-2019
Emisije nepremičnih virov - Toplogredni plini - 2. del: Zagotavljanje kakovosti
avtomatskih merilnih sistemov
Stationary source emissions - Greenhouse gases - Part 2: Ongoing quality control of
automated measuring systems
Émissions de sources fixes - Gaz à effet de serre - Partie 2: Contrôle qualité continu des
systèmes de mesurage automatiques
Ta slovenski standard je istoveten z: ISO 14385-2:2014
ICS:
13.020.40 Onesnaževanje, nadzor nad Pollution, pollution control
onesnaževanjem in and conservation
ohranjanje
13.040.40 Emisije nepremičnih virov Stationary source emissions
SIST ISO 14385-2:2019 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 14385-2:2019
---------------------- Page: 2 ----------------------
SIST ISO 14385-2:2019
INTERNATIONAL ISO
STANDARD 14385-2
First edition
2014-08-01
Stationary source emissions —
Greenhouse gases —
Part 2:
Ongoing quality control of automated
measuring systems
Émissions de sources fixes — Gaz à effet de serre —
Partie 2: Contrôle qualité continu des systèmes de mesurage
automatiques
Reference number
ISO 14385-2:2014(E)
©
ISO 2014
---------------------- Page: 3 ----------------------
SIST ISO 14385-2:2019
ISO 14385-2:2014(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2014
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 14385-2:2019
ISO 14385-2:2014(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviations . 2
4.1 Symbols . 2
4.2 Abbreviations . 2
5 Principle . 3
5.1 General . 3
5.2 Limitations . 3
5.3 Measurement site and installation . 4
5.4 Testing laboratories performing SRM measurements . 4
6 Ongoing quality assurance during operation . 4
6.1 General . 4
6.2 Procedures to maintain ongoing quality . 5
6.3 Choosing control charts . 6
6.4 Setting parameters for control charts . 6
6.5 Zero and span measurements . 8
6.6 Documentation of control charts . 9
6.7 Check on validity of measured values .10
7 Annual surveillance test (AST) .10
7.1 Functional test .10
7.2 Parallel measurements with an SRM .10
7.3 Data evaluation .12
7.4 Calculation of variability .13
7.5 Test of variability and validity of the calibration function .13
7.6 AST report .14
8 Documentation .14
Annex A (normative) AST functional test of AMS .15
Annex B (normative) Test of linearity .19
Annex C (informative) Documentation .21
Annex D (informative) Shewhart control charts .23
Annex E (informative) Exponentially weighted moving average (EWMA) charts .26
Annex F (informative) Example of calculation of the standard deviation σ of the AMS at zero
AMS
and span level .29
Bibliography .32
© ISO 2014 – All rights reserved iii
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SIST ISO 14385-2:2019
ISO 14385-2:2014(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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 146, Air quality, Subcommittee SC 1, Stationary
source emissions.
ISO 14385 consists of the following parts, under the general title Stationary source emissions —
Greenhouse gases:
— Part 1: Calibration of automated measuring systems
— Part 2: Ongoing quality control of automated measuring systems
iv © ISO 2014 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 14385-2:2019
ISO 14385-2:2014(E)
Introduction
The measurement of greenhouse gas emissions (carbon dioxide, nitrous oxide, methane) in a framework
of emission trading requires an equal and known quality of data.
This part of ISO 14385 describes the quality assurance procedures for calibration and ongoing quality
control needed to ensure that automated measuring systems (AMS) installed to measure emissions
of greenhouse gases to air are capable of meeting the uncertainty requirements on measured values
specified by legislation, competent authorities, or in an emission trade scheme.
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SIST ISO 14385-2:2019
INTERNATIONAL STANDARD ISO 14385-2:2014(E)
Stationary source emissions — Greenhouse gases —
Part 2:
Ongoing quality control of automated measuring systems
1 Scope
This part of ISO 14385 specifies procedures for establishing quality assurance for automated measuring
systems (AMS) installed on industrial plants for the determination of the concentration of greenhouse
gases in flue and waste gas and other flue gas parameters.
This part of ISO 14385 specifies the following:
— a procedure 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 using the relevant procedure in ISO 14956;
— a procedure for the annual surveillance tests (AST) of the AMS in order to evaluate a) that it functions
correctly and its performance remains valid and b) that its calibration function and variability
remain as previously determined.
This part of ISO 14385 is designed to be used after the AMS has been accepted according to the procedures
specified in ISO 14956.
This part of ISO 14385 is restricted to quality assurance (QA) of the AMS and does not include QA of the
data collection and recording system of the plant.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 14385-1, Stationary source emissions — Greenhouse gases — Part 1: Calibration of automated
measuring systems
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 terms and definitions given in ISO 14385-1 and the following
apply.
3.1
control chart
graphical presentation of the regular recording of the difference of the reading of an instrument or
measuring system, when measuring the pollutant concentration in a gas with known concentration, and
the nominal value of the pollutant concentration in that gas
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4 Symbols and abbreviations
4.1 Symbols
D difference between SRM value y and calibrated AMS measured value ŷ
i i i
average of D
D i
2
k test value for variability (based on a χ -test, with a β-value of 50 %, for N numbers of paired meas-
v
urements)
N number of paired samples in parallel measurements
S standard deviation of the AMS used in ongoing quality control
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 of
0,95; N–1
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 can 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
average of AMS measured signals x
x i
th
y i measured value obtained with the SRM
i
average of the SRM measured values y
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
ŷ best estimate for the “true value”, calculated from the AMS measured signal x by means of the
i i
calibration function
ŷ best estimate for the ”true value”, calculated from the AMS measured signal x at standard condi-
i,s i
tions
ŷ best estimate for the ”true value”, calculated from the maximum value of the AMS measured sig-
s,max
nals x at standard conditions
i
ԑ deviation between y and the expected value
i i
standard deviation associated with the uncertainty derived from requirements of legislation
σ0
4.2 Abbreviations
AMS automated measuring system
AST annual surveillance test
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ISO 14385-2:2014(E)
EWMA chart exponentially weighted moving average chart
QA quality assurance
SRM Standard Reference Method
5 Principle
5.1 General
An AMS to be used shall have been proven suitable for its measuring task (parameter and composition
of the flue gas) by use of the procedures, as specified by ISO 14956. Using this part of ISO 14385, it shall
be proven that the total uncertainty of the results obtained from the AMS meets the specification for
uncertainty stated in legislation or in requirements and specifications established in an international
trading program. In ISO 14956, the total uncertainty required by the relevant regulations is calculated
by summing all the relevant uncertainty components arising from the individual performance.
NOTE It is advisable that uncertainty figures are provided by independent testing bodies.
This part of ISO 14385 provides two procedures.
— 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 of the AMS, based on those
used in the procedure for zero and span repeatability tests according to ISO 14956:2002, and then
evaluating the results obtained using control charts. Zero and span adjustments or maintenance of
the AMS can be necessary, depending on the results of this evaluation.
— A procedure which is used to evaluate whether the measured values obtained from the AMS still
meet the maximum permissible uncertainty criteria, as demonstrated in the calibration procedure
(ISO 14385-1). It also determines whether the calibration function obtained during the calibration
procedure 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.
5.2 Limitations
Figure 2 illustrates the components of the AMS covered by this part of ISO 14385.
Figure 2 — Limits for the QA of the AMS excluding the data acquisition and handling system
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NOTE 1 The influence of the uncertainty of the measurement results, which arise from the data acquisition
recording and handling system of the AMS or of the plant system, and its determination, are excluded from this
part of ISO 14385.
NOTE 2 The performance of the data collection and recording system 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.
When conducting parallel measurements, the measured signals from the AMS are taken directly from
the AMS (e.g. expressed as analogue or digital signal) during the AST procedures specified in this part
of ISO 14385, by using an independent data collection system provided by the organization(s) carrying
out the AST tests. All data shall be recorded in their uncorrected form (without corrections for, e.g.
temperature and oxygen). A plant data collection system with quality control can additionally 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 national or international
standards, as specified by legislation, competent authorities, or in emission trade scheme. Special
attention shall be given to ensure that the AMS is readily accessible for regular maintenance and other
necessary activities.
NOTE The AMS is intended to be positioned as far as practical in a position where it measures a sample,
which is representative of the stack gas composition.
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 shall readily allow parallel measurements to be performed
using an SRM. The sampling ports for measurements with the SRM shall be placed as close as possible,
but not more than three times the equivalent diameter up-stream or down-stream of the location of the
AMS, in order to achieve comparable measurements between AMS and SRM.
It is necessary to have good access to the AMS to enable inspections to take place and also to minimize
time taken to implement the quality assurance procedures of this part of ISO 14385. 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, which perform the measurements with the SRM, shall have an accredited
quality assurance system according to ISO/IEC 17025 or shall be approved directly by the relevant
competent authority. They shall also have sufficient experience in performing the measurements
using the appropriate SRM. The SRM used shall be an international or national standard to ensure the
provision of data of an equivalent scientific quality.
6 Ongoing quality assurance during operation
6.1 General
An AMS can drift or become less precise during routine operation. Drift or instability can be due to,
for example, changes in the AMS, such as contamination of an optical surface, a gradual failure of a
component, or a blockage in a filter. Such changes cause systematic errors in the data from the AMS.
On the other hand, AMS are also subject to short-term variations in stability and precision due to the
influences of factors such as changes in ambient temperature. These variations cause random errors.
The magnitude of the random errors is assessed during the certification process of the AMS.
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After the acceptance and calibration of the AMS, further quality assurance and quality control procedures
shall be followed so as to ensure that the measured values obtained with the AMS meet the stated or
maximum permissible uncertainty on a continuous basis (also described as ongoing quality control). The
implementation and performance of the procedures given in this part of ISO 14385 are the responsibility
of the plant owner (i.e. the owner of the AMS). It is also the responsibility of the plant owner to ensure that
the AMS is operating inside the valid calibration range (see 6.5). The procedures shall be implemented
and be in place at the same time that the collection of emission data by means of the AMS is mandatory
for reporting to the authorities. It is recommended, however, that these procedures commence as soon
as possible after the installation of the AMS in order to gain as much information on the performance of
the AMS as possible. This can begin before the AMS has to be calibrated with the SRM in order to fulfil
the procedure requirements according to ISO 14385-1.
The instrument reading shall reflect the actual drifts in both zero and span readings. Negative instrument
readings at zero level shall be recorded.
For some monitors, it is difficult to achieve a zero and span readings. In those situations, the supplier
shall give instructions on how to achieve readings that reflect the actual drift in zero and span readings,
as demonstrated in the procedures according to ISO 14956, and conforming to the definition of the zero
reading.
6.2 Procedures to maintain ongoing quality
The aim of the procedure is to maintain and demonstrate the quality of the AMS, so that the requirements
for the stated zero and span repeatability and drift values are met during ongoing operation and the AMS
is maintained in the same operational condition as when installed. This shall be achieved by confirming
that the drift and precision determined during the procedures according to ISO 14956 remain under
control. A suitable methodology shall determine the combined drift and precision of the AMS.
The methodology shall identify whether an extra-maintenance (e.g. by the manufacturer) is necessary in
order to adjust the AMS. The procedure uses control charts which plot the drifts (zero and span) against
the time. In this procedure, reference materials are needed. The value of the reference material shall be
known. The drift and precision components obtained from the procedure described in ISO 14956 and
the uncertainty shall be combined and compared against the combined drift and precision obtained in
the field.
Control charts require regular and ideally frequent measurements. The needed frequency of the ongoing
quality control is at least the period of the maintenance interval. In order to extend a maintenance
interval, some AMS suppliers developed automatic checks and adjustments which guarantee very
limited drifts over time. Regular measurements at zero and reference points are the foundations of the
procedure. Using control charts to show trends in the zero and reference point measurements show
each measurement in context and can help prevent the operator from making adjustments to the AMS
only when required.
A frequency of the ongoing quality of at least once every 2 weeks is recommended. Depending on the
results of the zero and span checks, this frequency can be changed.
Therefore, ongoing quality control requires plant operators to have a procedure which describes the
requirements for
— measuring zero and span values,
— plotting these values on control charts, and
— using the control charts to determine whether there are systematic errors, whether the random
errors exceed the acceptable limits established by the implementation requirements in an
international trading scheme.
The following sub-sections describe the following:
— choosing control charts;
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— setting parameters for control charts;
— zero and span measurements;
— documentation and interpretation of the control charts.
6.3 Choosing control charts
6.3.1 General
Any type of control chart, manual or automated, can be used. Different charts have different advantages
and can be more or less complicated to use, depending on the type of chart chosen. This part of ISO 14385
describes two types of chart: the Shewhart chart and the EWMA chart.
6.3.2 Shewhart chart
Shewhart charts simply plot the readings and test them against multiples of S . Its advantage is its
AMS
simplicity; its disadvantage is that the approach is not as sensitive as other approaches such as EWMA
charts. Furthermore, Shewhart charts cannot distinguish between systematic errors and random
errors. Shewhart charts only indicate if the AMS has drifted or whether the precision has worsened.
However, the Shewhart chart method is simple to set up and understand, and it is well suited for manual
procedures.
Annex D describes in detail the procedure for Shewhart chart.
6.3.3 EWMA chart
Compared with the Shewhart chart, the exponentially weighted moving average (EWMA) chart is more
appropriate for early detection of small- or medium-sized maladjustments. It keeps the graphical format
of the Shewhart chart. This approach also implements only one decision rule. The approach also reduces
the risks of unnecessary intervention due to the natural variability of the process.
Annex E describes in detail the procedure for EWMA chart.
6.3.4 Built-in methods
An alternative to an external control chart is to use an instrument built-in method. Many instruments
have a built-in check of zero and span points, and give alarm, if set limits are surpassed.
Some AMS equipped with automatic systems for zero and span checks do not ordinarily output the data
for zero and span drift for plotting on control charts, even though the automatic systems are designed to
achieve the same result as control charts, i.e. measuring drift and alerting the plant operator if the AMS
has drifted out of control. Some systems also automatically adjust the zero and/or the span point in order.
If a plant operator has such a system, it can be accepted as a method for ongoing quality control provided
that an assessment of the total drifts and adjustments are possible during the AMS maintenance by the
AMS supplier and that the information is also accessible to the operator and for third party auditing.
6.4 Setting parameters for control charts
6.4.1 Calculation of the standard deviation S using performance data
AMS
The standard deviation S shall be derived from the information obtained for the calculations
AMS
a
...
SLOVENSKI STANDARD
oSIST ISO 14385-2:2018
01-september-2018
(PLVLMHQHSUHPLþQLKYLURY7RSORJUHGQLSOLQLGHO =DJRWDYOMDQMHNDNRYRVWL
DYWRPDWVNLKPHULOQLKVLVWHPRY
Stationary source emissions - Greenhouse gases - Part 2: Ongoing quality control of
automated measuring systems
Émissions de sources fixes - Gaz à effet de serre - Partie 2: Contrôle qualité continu des
systèmes de mesurage automatiques
Ta slovenski standard je istoveten z: ISO 14385-2:2014
ICS:
13.020.40 Onesnaževanje, nadzor nad Pollution, pollution control
onesnaževanjem in and conservation
ohranjanje
13.040.40 (PLVLMHQHSUHPLþQLKYLURY Stationary source emissions
oSIST ISO 14385-2:2018 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST ISO 14385-2:2018
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oSIST ISO 14385-2:2018
INTERNATIONAL ISO
STANDARD 14385-2
First edition
2014-08-01
Stationary source emissions —
Greenhouse gases —
Part 2:
Ongoing quality control of automated
measuring systems
Émissions de sources fixes — Gaz à effet de serre —
Partie 2: Contrôle qualité continu des systèmes de mesurage
automatiques
Reference number
ISO 14385-2:2014(E)
©
ISO 2014
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oSIST ISO 14385-2:2018
ISO 14385-2:2014(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2014
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved
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oSIST ISO 14385-2:2018
ISO 14385-2:2014(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviations . 2
4.1 Symbols . 2
4.2 Abbreviations . 2
5 Principle . 3
5.1 General . 3
5.2 Limitations . 3
5.3 Measurement site and installation . 4
5.4 Testing laboratories performing SRM measurements . 4
6 Ongoing quality assurance during operation . 4
6.1 General . 4
6.2 Procedures to maintain ongoing quality . 5
6.3 Choosing control charts . 6
6.4 Setting parameters for control charts . 6
6.5 Zero and span measurements . 8
6.6 Documentation of control charts . 9
6.7 Check on validity of measured values .10
7 Annual surveillance test (AST) .10
7.1 Functional test .10
7.2 Parallel measurements with an SRM .10
7.3 Data evaluation .12
7.4 Calculation of variability .13
7.5 Test of variability and validity of the calibration function .13
7.6 AST report .14
8 Documentation .14
Annex A (normative) AST functional test of AMS .15
Annex B (normative) Test of linearity .19
Annex C (informative) Documentation .21
Annex D (informative) Shewhart control charts .23
Annex E (informative) Exponentially weighted moving average (EWMA) charts .26
Annex F (informative) Example of calculation of the standard deviation σ of the AMS at zero
AMS
and span level .29
Bibliography .32
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ISO 14385-2:2014(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 on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 146, Air quality, Subcommittee SC 1, Stationary
source emissions.
ISO 14385 consists of the following parts, under the general title Stationary source emissions —
Greenhouse gases:
— Part 1: Calibration of automated measuring systems
— Part 2: Ongoing quality control of automated measuring systems
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ISO 14385-2:2014(E)
Introduction
The measurement of greenhouse gas emissions (carbon dioxide, nitrous oxide, methane) in a framework
of emission trading requires an equal and known quality of data.
This part of ISO 14385 describes the quality assurance procedures for calibration and ongoing quality
control needed to ensure that automated measuring systems (AMS) installed to measure emissions
of greenhouse gases to air are capable of meeting the uncertainty requirements on measured values
specified by legislation, competent authorities, or in an emission trade scheme.
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oSIST ISO 14385-2:2018
INTERNATIONAL STANDARD ISO 14385-2:2014(E)
Stationary source emissions — Greenhouse gases —
Part 2:
Ongoing quality control of automated measuring systems
1 Scope
This part of ISO 14385 specifies procedures for establishing quality assurance for automated measuring
systems (AMS) installed on industrial plants for the determination of the concentration of greenhouse
gases in flue and waste gas and other flue gas parameters.
This part of ISO 14385 specifies the following:
— a procedure 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 using the relevant procedure in ISO 14956;
— a procedure for the annual surveillance tests (AST) of the AMS in order to evaluate a) that it functions
correctly and its performance remains valid and b) that its calibration function and variability
remain as previously determined.
This part of ISO 14385 is designed to be used after the AMS has been accepted according to the procedures
specified in ISO 14956.
This part of ISO 14385 is restricted to quality assurance (QA) of the AMS and does not include QA of the
data collection and recording system of the plant.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 14385-1, Stationary source emissions — Greenhouse gases — Part 1: Calibration of automated
measuring systems
ISO 14956, Air quality — Evaluation of the suitability of a measurement procedure by comparison with a
required measurement uncertainty
3 Terms a nd definiti ons
For the purposes of this document, the terms and definitions given in ISO 14385-1 and the following
apply.
3.1
control chart
graphical presentation of the regular recording of the difference of the reading of an instrument or
measuring system, when measuring the pollutant concentration in a gas with known concentration, and
the nominal value of the pollutant concentration in that gas
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4 Symbols and abbreviations
4.1 Symbols
D difference between SRM value y and calibrated AMS measured value ŷ
i i i
average of D
D i
2
k test value for variability (based on a χ -test, with a β-value of 50 %, for N numbers of paired meas-
v
urements)
N number of paired samples in parallel measurements
S standard deviation of the AMS used in ongoing quality control
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 of
0,95; N–1
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 can 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
average of AMS measured signals x
x i
th
y i measured value obtained with the SRM
i
average of the SRM measured values y
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
ŷ best estimate for the “true value”, calculated from the AMS measured signal x by means of the
i i
calibration function
ŷ best estimate for the ”true value”, calculated from the AMS measured signal x at standard condi-
i,s i
tions
ŷ best estimate for the ”true value”, calculated from the maximum value of the AMS measured sig-
s,max
nals x at standard conditions
i
ԑ deviation between y and the expected value
i i
standard deviation associated with the uncertainty derived from requirements of legislation
σ0
4.2 Abbreviations
AMS automated measuring system
AST annual surveillance test
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oSIST ISO 14385-2:2018
ISO 14385-2:2014(E)
EWMA chart exponentially weighted moving average chart
QA quality assurance
SRM Standard Reference Method
5 Principle
5.1 General
An AMS to be used shall have been proven suitable for its measuring task (parameter and composition
of the flue gas) by use of the procedures, as specified by ISO 14956. Using this part of ISO 14385, it shall
be proven that the total uncertainty of the results obtained from the AMS meets the specification for
uncertainty stated in legislation or in requirements and specifications established in an international
trading program. In ISO 14956, the total uncertainty required by the relevant regulations is calculated
by summing all the relevant uncertainty components arising from the individual performance.
NOTE It is advisable that uncertainty figures are provided by independent testing bodies.
This part of ISO 14385 provides two procedures.
— 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 of the AMS, based on those
used in the procedure for zero and span repeatability tests according to ISO 14956:2002, and then
evaluating the results obtained using control charts. Zero and span adjustments or maintenance of
the AMS can be necessary, depending on the results of this evaluation.
— A procedure which is used to evaluate whether the measured values obtained from the AMS still
meet the maximum permissible uncertainty criteria, as demonstrated in the calibration procedure
(ISO 14385-1). It also determines whether the calibration function obtained during the calibration
procedure 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.
5.2 Limitations
Figure 2 illustrates the components of the AMS covered by this part of ISO 14385.
Figure 2 — Limits for the QA of the AMS excluding the data acquisition and handling system
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ISO 14385-2:2014(E)
NOTE 1 The influence of the uncertainty of the measurement results, which arise from the data acquisition
recording and handling system of the AMS or of the plant system, and its determination, are excluded from this
part of ISO 14385.
NOTE 2 The performance of the data collection and recording system 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.
When conducting parallel measurements, the measured signals from the AMS are taken directly from
the AMS (e.g. expressed as analogue or digital signal) during the AST procedures specified in this part
of ISO 14385, by using an independent data collection system provided by the organization(s) carrying
out the AST tests. All data shall be recorded in their uncorrected form (without corrections for, e.g.
temperature and oxygen). A plant data collection system with quality control can additionally 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 national or international
standards, as specified by legislation, competent authorities, or in emission trade scheme. Special
attention shall be given to ensure that the AMS is readily accessible for regular maintenance and other
necessary activities.
NOTE The AMS is intended to be positioned as far as practical in a position where it measures a sample,
which is representative of the stack gas composition.
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 shall readily allow parallel measurements to be performed
using an SRM. The sampling ports for measurements with the SRM shall be placed as close as possible,
but not more than three times the equivalent diameter up-stream or down-stream of the location of the
AMS, in order to achieve comparable measurements between AMS and SRM.
It is necessary to have good access to the AMS to enable inspections to take place and also to minimize
time taken to implement the quality assurance procedures of this part of ISO 14385. 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, which perform the measurements with the SRM, shall have an accredited
quality assurance system according to ISO/IEC 17025 or shall be approved directly by the relevant
competent authority. They shall also have sufficient experience in performing the measurements
using the appropriate SRM. The SRM used shall be an international or national standard to ensure the
provision of data of an equivalent scientific quality.
6 Ongoing quality assurance during operation
6.1 General
An AMS can drift or become less precise during routine operation. Drift or instability can be due to,
for example, changes in the AMS, such as contamination of an optical surface, a gradual failure of a
component, or a blockage in a filter. Such changes cause systematic errors in the data from the AMS.
On the other hand, AMS are also subject to short-term variations in stability and precision due to the
influences of factors such as changes in ambient temperature. These variations cause random errors.
The magnitude of the random errors is assessed during the certification process of the AMS.
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oSIST ISO 14385-2:2018
ISO 14385-2:2014(E)
After the acceptance and calibration of the AMS, further quality assurance and quality control procedures
shall be followed so as to ensure that the measured values obtained with the AMS meet the stated or
maximum permissible uncertainty on a continuous basis (also described as ongoing quality control). The
implementation and performance of the procedures given in this part of ISO 14385 are the responsibility
of the plant owner (i.e. the owner of the AMS). It is also the responsibility of the plant owner to ensure that
the AMS is operating inside the valid calibration range (see 6.5). The procedures shall be implemented
and be in place at the same time that the collection of emission data by means of the AMS is mandatory
for reporting to the authorities. It is recommended, however, that these procedures commence as soon
as possible after the installation of the AMS in order to gain as much information on the performance of
the AMS as possible. This can begin before the AMS has to be calibrated with the SRM in order to fulfil
the procedure requirements according to ISO 14385-1.
The instrument reading shall reflect the actual drifts in both zero and span readings. Negative instrument
readings at zero level shall be recorded.
For some monitors, it is difficult to achieve a zero and span readings. In those situations, the supplier
shall give instructions on how to achieve readings that reflect the actual drift in zero and span readings,
as demonstrated in the procedures according to ISO 14956, and conforming to the definition of the zero
reading.
6.2 Procedures to maintain ongoing quality
The aim of the procedure is to maintain and demonstrate the quality of the AMS, so that the requirements
for the stated zero and span repeatability and drift values are met during ongoing operation and the AMS
is maintained in the same operational condition as when installed. This shall be achieved by confirming
that the drift and precision determined during the procedures according to ISO 14956 remain under
control. A suitable methodology shall determine the combined drift and precision of the AMS.
The methodology shall identify whether an extra-maintenance (e.g. by the manufacturer) is necessary in
order to adjust the AMS. The procedure uses control charts which plot the drifts (zero and span) against
the time. In this procedure, reference materials are needed. The value of the reference material shall be
known. The drift and precision components obtained from the procedure described in ISO 14956 and
the uncertainty shall be combined and compared against the combined drift and precision obtained in
the field.
Control charts require regular and ideally frequent measurements. The needed frequency of the ongoing
quality control is at least the period of the maintenance interval. In order to extend a maintenance
interval, some AMS suppliers developed automatic checks and adjustments which guarantee very
limited drifts over time. Regular measurements at zero and reference points are the foundations of the
procedure. Using control charts to show trends in the zero and reference point measurements show
each measurement in context and can help prevent the operator from making adjustments to the AMS
only when required.
A frequency of the ongoing quality of at least once every 2 weeks is recommended. Depending on the
results of the zero and span checks, this frequency can be changed.
Therefore, ongoing quality control requires plant operators to have a procedure which describes the
requirements for
— measuring zero and span values,
— plotting these values on control charts, and
— using the control charts to determine whether there are systematic errors, whether the random
errors exceed the acceptable limits established by the implementation requirements in an
international trading scheme.
The following sub-sections describe the following:
— choosing control charts;
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oSIST ISO 14385-2:2018
ISO 14385-2:2014(E)
— setting parameters for control charts;
— zero and span measurements;
— documentation and interpretation of the control charts.
6.3 Choosing control charts
6.3.1 General
Any type of control chart, manual or automated, can be used. Different charts have different advantages
and can be more or less complicated to use, depending on the type of chart chosen. This part of ISO 14385
describes two types of chart: the Shewhart chart and the EWMA chart.
6.3.2 Shewhart chart
Shewhart charts simply plot the readings and test them against multiples of S . Its advantage is its
AMS
simplicity; its disadvantage is that the approach is not as sensitive as other approaches such as EWMA
charts. Furthermore, Shewhart charts cannot distinguish between systematic errors and random
errors. Shewhart charts only indicate if the AMS has drifted or whether the precision has worsened.
However, the Shewhart chart method is simple to set up and understand, and it is well suited for manual
procedures.
Annex D describes in detail the procedure for Shewhart chart.
6.3.3 EWMA chart
Compared with the Shewhart chart, the exponentially weighted moving average (EWMA) chart is more
appropriate for early detection of small- or medium-sized maladjustments. It keeps the graphical format
of the Shewhart chart. This approach also implements only one decision rule. The approach also reduces
the risks of unnecessary intervention due to the natural variability of the process.
Annex E describes in detail the procedure for EWMA chart.
6.3.4 Built-in methods
An alternative to an external control chart is to use an instrument built-in method. Many instruments
have a built-in check of zero and span points, and give alarm, if set limits are surpassed.
Some AMS equipped with automatic systems for zero and span checks do not ordinarily output the data
for zero and span drift for plotting on control charts, even though the automatic systems are designed to
achieve the same result as control charts, i.e. measuring drift and alerting the plant operator if the AMS
has drifted out of control. Some systems also automatically adjust the zero and/or the span point in order.
If a plant operator has such a system, it can be accepted as a method for ongoing quality control provided
that an assessment of the total drifts and adjustments are possible during the AMS maintenance by the
AMS supplier and that the information is also accessible to the operator and for third party auditing.
6.4 Setting parameters for control charts
6.4.1 Calculation of the standard deviation S using performance data
AMS
The standard deviation S shall be derived from the inform
...
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