Stationary source emissions - Demonstration of equivalence of an alternative method with a reference method

This European Standard specifies a procedure to demonstrate the equivalence of an alternative method (AM) with the reference method (RM) or the standard reference method (SRM), both implemented to determine the same measurand.
In particular, this European Standard provides the statistical tools and different criteria to evaluate the alternative method. This does not release the body performing the equivalence testing from bearing technical and analytical judgement on the evaluation of the different criteria.
Three steps are required for demonstration of equivalence:
   description of the alternative method and setting of the field of application (measurement range and type of gas matrix);
   determination of the performance characteristics of the alternative method and calculation of the expanded uncertainty where appropriate and check of compliance with the maximum expanded uncertainty allowed for the reference method;
   check of repeatability and lack of systematic deviation of the alternative method in the field or on a recognized test bench in comparison with the reference method for the type of matrix defined in the field of equivalence.
This European Standard requires that a reference method has been defined and validated.
This European Standard only considers the case of linear quantitative methods.
This European Standard has been drawn up for laboratories working in air quality measurements and consequently an example taken from this sector are presented in Annex A.

Emissionen aus stationären Quellen - Nachweis der Gleichwertigkeit eines Alternativverfahrens mit einem Referenzverfahren

Diese Europäische Norm legt ein Verfahren zum Nachweis der Gleichwertigkeit eines Alternativverfahrens (AM) mit dem Referenzverfahren (RM) oder dem Standardreferenzverfahren (SRM) fest, wobei beide zur Bestimmung derselben Messgröße eingesetzt werden.
Diese Europäische Norm enthält insbesondere die statistischen Methoden und verschiedene Kriterien zur Bewertung des Alternativverfahrens. Das entbindet aber nicht die für den Nachweis der Gleichwertigkeit zuständige Stelle von der Aufgabe, die Auswertung der verschiedenen Kriterien technisch und analytisch zu beurteilen.
Der Nachweis der Gleichwertigkeit beinhaltet drei Schritte:
   Beschreibung des Alternativverfahrens und Festlegung des Anwendungsbereichs (Messbereich und Art der Abgasmatrix);
   Bestimmung der Verfahrenskenngrößen des Alternativverfahrens und gegebenenfalls Berechnung der erweiterten Unsicherheit sowie Überprüfung der Einhaltung der maximal zulässigen erweiterten Unsicherheit für das Referenzverfahren;
   Überprüfung der Wiederholpräzision und des Fehlens systematischer Abweichungen des Alternativverfahrens beim Einsatz im Feld oder an einem anerkannten Prüfstand durch Vergleich mit dem Referenzverfahren für die Art der Abgasmatrix, die im Äquivalenzbereich festgelegt ist.
Diese Europäische Norm setzt voraus, dass das Referenzverfahren eindeutig festgelegt und validiert wurde.
Diese Europäische Norm ist nur bei linearen quantitativen Verfahren anwendbar.
Diese Europäische Norm ist auf manuelle und automatische Verfahren anwendbar.
Diese Europäische Norm wurde für Laboratorien erstellt, die Messungen im Bereich der Luftreinhaltung durchführen. Anhang A zeigt deshalb ein entsprechendes Beispiel aus diesem Bereich.

Émissions de sources fixes - Démonstration de l'équivalence d'une méthode 'alternative' avec une méthode de référence

Emisije nepremičnih virov - Dokazovanje enakovrednosti alternativne metode z referenčno metodo

Ta evropski standard določa postopek za dokazovanje enakovrednosti alternativne metode z referenčno metodo ali standardno referenčno metodo (SRM), pri čemer sta obe uporabljeni za določanje istih merjenih veličin.
Ta evropski standard podaja predvsem statistična orodja in različna merila za ovrednotenje alternativne metode. S tem organ za izvajanje enakovrednega preskušanja ni oproščen tehnične in analitične presoje pri ocenjevanju različnih meril.
Za prikaz enakovrednosti so zahtevani trije koraki:
opis alternativne metode in določitev področja uporabe (merilno območje in vrsta plinske matrike);
določitev lastnosti zmogljivosti alternativne metode in izračun razširjene negotovosti, kjer je to ustrezno, ter preverjanje skladnosti pri največji razširjeni negotovosti, ki je dovoljena za referenčno metodo;
preverjanje ponovljivosti in pomanjkanje sistematičnega odstopanja alternativne metode na terenu ali v priznanem preskusnem okolju v primerjavi z referenčno metodo za vrsto matrike, opredeljeno za enakovredno področje.
Ta evropski standard zahteva opredelitev in potrditev referenčne metode.
Ta evropski standard zajema samo linearne kvantitativne metode.
Ta evropski standard je bil pripravljen za laboratorije, ki izvajajo meritve kakovosti zraka, zato je primer za ta sektor na voljo v dodatku A.

General Information

Status
Published
Public Enquiry End Date
08-Feb-2015
Publication Date
11-Jun-2017
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
30-May-2017
Due Date
04-Aug-2017
Completion Date
12-Jun-2017

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Emissionen aus stationären Quellen - Nachweis der Gleichwertigkeit eines Alternativverfahrens mit einem ReferenzverfahrenÉmissions de sources fixes - Démonstration de l'équivalence d'une méthode 'alternative' avec une méthode de référenceStationary source emissions - Demonstration of equivalence of an alternative method with a reference method13.040.40Stationary source emissionsICS:Ta slovenski standard je istoveten z:EN 14793:2017SIST EN 14793:2017en,fr,de01-julij-2017SIST EN 14793:2017SLOVENSKI

STANDARDSIST-TS CEN/TS 14793:20051DGRPHãþD
SIST EN 14793:2017
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 14793
January
t r s y English Version

Stationary source emissions æ Demonstration of equivalence of an alternative method with a reference method Émissions de sources fixes æ Démonstration de l 5équivalence d 5une méthode alternative avec une méthode de référence

Emissionen aus stationären Quellen æ Nachweis der Gleichwertigkeit eines Alternativverfahrens mit einem Referenzverfahren This European Standard was approved by CEN on

t x September
t r s xä

egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä

translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä

CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Serbiaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey and United Kingdomä

EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels

t r s y CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN

s v y { uã t r s y ESIST EN 14793:2017
EN 14793:2017 (E) 2 Contents Page

European foreword ....................................................................................................................................................... 3 Introduction .................................................................................................................................................................... 4 1 Scope .................................................................................................................................................................... 5 2 Normative references .................................................................................................................................... 5 3 Terms and definitions ................................................................................................................................... 6 4 Symbols ............................................................................................................................................................... 9 5 Contents of the demonstration of equivalence.................................................................................. 11 5.1 General ............................................................................................................................................................. 11 5.2 Description of the alternative method ................................................................................................. 11 5.3 Determination of performance characteristics ................................................................................ 12 5.3.1 General ............................................................................................................................................................. 12 5.3.2 Manual method ............................................................................................................................................. 12 5.3.3 Automatic method ....................................................................................................................................... 13 5.4 Calculation of the expanded uncertainty of the AM ......................................................................... 13 5.5 Demonstration of equivalence in the field .......................................................................................... 14 5.5.1 Coverage of in field demonstration ....................................................................................................... 14 5.5.2 Evaluation of repeatability and trueness in relation to the RM .................................................. 15 6 Report of the demonstration of equivalence ..................................................................................... 18 Annex A (informative)

Example of comparison of repeatability and trueness of Thorin Method and Ion Chromatography Method for SO2 measurement in stack .............................. 21 Annex B (informative)

Critical values for Grubbs test ................................................................................ 32 Annex C (normative)

Minimum requirements for a test bench .............................................................. 33 Bibliography ................................................................................................................................................................. 34

SIST EN 14793:2017

EN 14793:2017 (E) 3 European foreword This document (EN 14793:2017) has been prepared by Technical Committee CEN/TC 264 “Air quality”, the secretariat of which is held by DIN. This document supersedes CEN/TS 14793:2005. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by July 2017, and conflicting national standards shall be withdrawn at the latest by July 2017. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 14793:2017

EN 14793:2017 (E) 4 Introduction Much has been published in the literature concerning method validation by collaborative study. CEN/TC 264 working groups try to follow these method validations when a new standard is prepared and the collaborative study is probably the preferred way of carrying out the validation. However, it is not always a suitable option for accredited laboratories. The application for which the method is required can be esoteric to the extent that no other laboratories would be interested in collaboration. Those that might be interested can be competitors. This European Standard provides one of possible methods of testing the equivalence of an alternative method (AM) with the standard reference method (SRM) or with a reference method (RM) if the legislator has not defined a standard reference method.

NOTE The term “reference method” is used in this standard to cover reference methods as well as standard reference methods. In the framework of certification of automated measuring systems used for the measurement of stationary source emissions this European Standard can be used in conjunction with EN 15267-4:2017 to demonstrate the equivalence of portable automated measuring systems (P-AMS) based on an AM with the standard reference method (SRM).

SIST EN 14793:2017

EN 14793:2017 (E) 5 1 Scope This European Standard specifies a procedure to demonstrate the equivalence of an alternative method (AM) with the reference method (RM) or the standard reference method (SRM), both implemented to determine the same measurand.

In particular, this European Standard provides the statistical tools and different criteria to evaluate the alternative method. This does not release the body performing the equivalence testing from bearing technical and analytical judgement on the evaluation of the different criteria. Three steps are required for demonstration of equivalence: — description of the alternative method and setting of the field of application (measurement range and type of gas matrix); — determination of the performance characteristics of the alternative method and calculation of the expanded uncertainty where appropriate and check of compliance with the maximum expanded uncertainty allowed for the reference method; — check of repeatability and lack of systematic deviation of the alternative method in the field or on a recognized test bench in comparison with the reference method for the type of matrix defined in the field of equivalence. This European Standard requires that a reference method has been defined and validated. This European Standard only considers the case of linear quantitative methods. This European Standard is applicable to manual and automated methods.

This European Standard has been drawn up for laboratories working in air quality measurements and consequently an example taken from this sector are presented in Annex A. 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.

EN ISO 14956, Air quality - Evaluation of the suitability of a measurement procedure by comparison with a required measurement uncertainty (ISO 14956) ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results — Part 1: General principles and definitions ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) SIST EN 14793:2017

EN 14793:2017 (E) 6 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 standard reference method

SRM reference method prescribed by European or national legislation

[SOURCE: EN 15259:2007] Note 1 to entry: Standard reference methods are used e.g. to calibrate and validate automated measuring systems permanently installed at stacks and for periodic measurements to check compliance with limit values.

3.2 reference method RM measurement method taken as a reference by convention, which gives the accepted reference value of the measurand Note 1 to entry: A reference method is fully described. Note 2 to entry: A reference method can be a manual or an automated method. Note 3 to entry: Alternative methods can be used if equivalence to the reference method has been demonstrated. [SOURCE: EN 15259:2007] 3.3 alternative method AM measurement method which complies with the criteria given by this European Standard with respect to the reference method Note 1 to entry: An alternative method can consist of a simplification of the reference method. 3.4 measurement method method described in a written procedure containing all the means and procedures required to sample and analyse, namely field of application, principle and/or reactions, definitions, equipment, procedures, presentation of results, other requirements and measurement report 3.5 calibration set of operations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring method or measuring system, and the corresponding values given by the applicable reference

3.6 accepted reference value value which serves as a reference value (or conventionally true value) of the sample, provided by the reference method or standard reference method

SIST EN 14793:2017

EN 14793:2017 (E) 7 3.7 demonstration of equivalence act of subjecting a measurement method to a study, which is based on a standardised and/or recognised protocol and which provides proof that, for its field of application, the measurement method satisfies pre-established performance criteria Note 1 to entry: In the framework of this European Standard, the demonstration of equivalence of a method is mainly based on an “in field” study that includes comparison to a reference method. 3.8 field of application

combination of the different types of matrix and the range of concentrations of the measured component covered, to which the measurement method is applied Note 1 to entry: As well as being an indication of all the satisfactory performance conditions for each factor, the field of application of the measurement method can also include warnings concerning known interferences caused by other components, or the inapplicability of certain matrices or conditions. 3.9 matrix all the components of the sample other than the measured component

Note 1 to entry: Some components of the matrix can influence the result of measurement. These components are called interferents.

3.10 measurand particular quantity subject to measurement

[SOURCE: EN 15259:2007] Note 1 to entry: The measurand is a quantifiable property of the stack gas under test, for example mass concentration of a measured component, temperature, velocity, mass flow, oxygen content and water vapour content. 3.11 measured component constituent of the waste gas for which a defined measurand is to be determined by measurement

[SOURCE: EN 15259:2007] Note 1 to entry: Measured component is also called determinand. 3.12 reference material substance or mixture of substances, with a known concentration within specified limits, or a device of known characteristics SIST EN 14793:2017

EN 14793:2017 (E) 8 3.13 linearity capacity of a measurement method, within certain limits, to provide an instrument response or results proportional to the quantity of the measurand to be determined in the sample Note 1 to entry: This proportionality is expressed through a defined a priori mathematical expression. Note 2 to entry: The linearity limits are the concentration limits in the experiment between which a linear calibration model can be applied with a known level of confidence. 3.14 lack of fit systematic deviation, within the measurement range, between the accepted value of a reference material applied to the measuring system and the corresponding result of measurement produced by the calibrated measuring system Note 1 to entry: In common language lack of fit is often called “linearity” or “deviation from linearity”. Lack of fit test is often called “linearity test”. 3.15 detection limit LD smallest quantity of the measurand which can be detected, but not quantified, in the experiment conditions described for the measurement method 3.16 quantification limit LQ smallest quantity of the measurand which can be quantified, in the experiment conditions described for the measurement method 3.17 repeatability closeness of agreement between independent test results obtained under stipulated conditions Note 1 to entry: Repeatability depends exclusively upon the distribution of random errors and has no relation with the true or specified value. Note 2 to entry: The measure of repeatability is calculated from the standard deviation of test results. A lower level of repeatability is reflected by a greater standard deviation. Note 3 to entry: The term “independent test results” signifies results obtained in such a way as not to be influenced by a previous result on the same or similar testing equipment. Quantitative measurements of repeatability depend critically upon the stipulated conditions. Repeatability and reproducibility conditions are specific groups of extreme conditions. 3.18 trueness closeness of agreement between the average value obtained from a large series of test results and an accepted reference value [SOURCE: ISO 5725-1:1994] Note 1 to entry: The measure of trueness is generally expressed in terms of a bias or a systematic deviation. SIST EN 14793:2017

EN 14793:2017 (E) 9 4 Symbols For the purpose of this document, the symbols listed in Table 1 apply.

Table 1 — Symbols and formulae Symbol Description Formula

0C intercept of the orthogonal regression line between AM and RM values ()()0sxCxzsz=−

1C slope of the orthogonal regression line between AM and RM values ()()1sxCsz=
dix difference between 1ix and 2ix for each value of i ()12diiixxx=−
ie ratio between dix and ix for each value of i diiixex=
e average value of the values ie 1niieen==∑
iG ratio between ()iee− and ()ise ()iiieeGse−=
DL detection limit
QL quantification limit
p number of trials
in number of parallel measurement for the AM and for the RM for a trial i

N total number of measurements for the AM and for the RM 1piiNn==∑ r correlation coefficient SPD(,)SSD()SSD()xzrxz=×

()ise standard deviation of the population of the ie ()()2111niiiseeen==−−∑
()2sx variance of the AM
()()2SSD1xsxp=−
()rsx repeatability standard deviation of the AM
SIST EN 14793:2017
EN 14793:2017 (E) 10
()2rsx repeatability variance of the AM ()()2112ipnijiijrxxsxNp==−=−∑∑.
()2sz variance of the RM ()()2SSD1zszp=−
()rsz repeatability standard deviation of the RM
()2rsz repeatability variance of the RM
()()2112ipnijiijrzzszNp==−=−∑∑
(),limitrsz maximum allowable repeatability standard deviation for the RM
()Rsz reproducibility standard deviation given in the RM standard
()SPD,xz sum of the products of the deviations for two variables x and z
()()()1SPD,piiixzxxzz==−×−∑
()SSDx sum of the squares of the mean deviations for the AM
()()21SSDpiixxx==−∑
()SSDz sum of the squares of the mean deviations for the RM ()()21SSDpiizzz==−∑.
RMU maximum permissible expanded uncertainty given in the RM standard
ijx concentration obtained by the AM for a trial i and repetition j

ix arithmetic mean of ijx for which in measurements have been taken 1inijjiixxn==∑

x grand average of ijx for which N measurements have been taken 11ipnijijxxN===∑∑

px outlier
ijz concentration obtained by the RM for a trial i and repetition j

iz arithmetic mean of ijz for which in measurements have been taken 1inijjiizzn==∑ SIST EN 14793:2017

EN 14793:2017 (E) 11

z grand average of ijz for which N measurements have been taken 11injpijizzN===∑∑

qz outlier
5 Contents of the demonstration of equivalence

5.1 General The demonstration of equivalence shall include the following items: — description of the alternative method (see 5.2); — determination of performance characteristics (see 5.3); — calculation of the expanded uncertainty of the alternative method (see 5.4); — demonstration of equivalence in the field (see 5.5). WARNING 1

The field of application of an alternative method can partially or completely cover the field of application of the reference method. However, if it covers the fields of application of several reference methods (horizontal method), several evaluations of each reference method shall be performed, e.g. in the case of multi-component measurement methods like FTIR. WARNING 2

The definition of the field of application depends entirely upon the laboratory applying the alternative method and the knowledge acquired during the development of the method. It is sometimes preferable to segment a field of application rather than to attempt to validate an overly general method. In this case, a validation file for each field of application shall be compiled. 5.2 Description of the alternative method The description shall permit all competent persons to use it (including the procedure and the calculations). The following items should be addressed: — title; — warnings and safety precautions (where relevant); — introduction; — purpose and field of application; — standard references; — definitions; — principle (sampling and analysis); — reagents and products (where relevant); — equipment (e.g.: description of the sampling line and measuring device); — procedures for quality checks; — definition of performance characteristics and determination procedures; SIST EN 14793:2017

EN 14793:2017 (E) 12 — presentation of results; — specific cases; — remarks; — test report; — annexes; — bibliography. The field of application of the alternative method shall be clearly defined in terms of: — measured component; — gas matrixes; — concentration range (the limit of quantification and the upper limit of the claimed concentration range shall be given); — external conditions (e.g. ambient temperature). NOTE Some of the above items might not be applicable to a specific method. 5.3 Determination of performance characteristics 5.3.1 General The performance characteristics shall be determined in accordance with the description of the alternative method. Identify all potentially important sources of uncertainty in accordance with relevant standards. Any performance characteristic that is not able to create a standard uncertainty of more than 5 % of the highest standard uncertainty of the others may be excluded from the selection. 5.3.2 Manual method Main sources of uncertainty for manual methods are attached to: — absorption efficiency of the absorption bottles; — calibration of the gas volume meter; — effect of temperature variation in the gas meter; — effect of ambient pressure variation in the gas meter; — humidity after the drying cartridge; — leakage of the sampling line; — absorption in the sampling system; — preparation of sample for analysis; — analysis; SIST EN 14793:2017

EN 14793:2017 (E) 13 — limit of detection and quantification; — lack of fit; — repeatability; — interferences; — calibration procedure; — reference materials. 5.3.3 Automatic method Main sources of uncertainty for automated methods are attached to:

— response time; — limit of detection and quantification; — lack of fit; — drift on a duration adapted to the measurement purpose; — repeatability; — dependence on sampling gas pressure; — dependence on ambient temperature; — dependence on voltage; — interferences; — leakage of the sampling line; — absorption in the sampling system; — adjustment of the analyser; — reference material (e.g. calibration gas). 5.4 Calculation of the expanded uncertainty of the AM The expanded uncertainty of the AM shall be calculated by building an uncertainty budget according to EN ISO 14956 or ISO/IEC Guide 98-3 (GUM). The maximum expanded uncertainty of the alternative method shall be compared with the reference’s and shall be lower or equal to the maximum expanded uncertainty specified by the reference method at the emission limit value. SIST EN 14793:2017

EN 14793:2017 (E) 14 5.5 Demonstration of equivalence in the field

5.5.1 Coverage of in field demonstration 5.5.1.1 General The demonstration of equivalence in the field shall be performed at suitable plant(s). If necessary, a combination of two sets of data drawn from trials performed on plant(s) and on a test bench recognized by the competent authorities and meeting the requirements in Annex C may be used.

5.5.1.2 Gas matrixes The “in field demonstration” covers the field of application of the method defined under the sole responsibility of the test laboratory. In practice, it is the responsibility of the laboratory to demonstrate that the field of application of the method is correctly covered, in terms of types of matrixes. The laboratory may determine the effect of each of the individual compounds present in the flue gases suspected to have an influence on the measurement result. Nevertheless, this experimental work in the laboratory cannot cover all the compounds that could interfere with the measurement results. Therefore, the possible effect of interferences shall be checked against the reference during experiment in the field by implementing both methods in parallel. The laboratory shall find suitable plant(s), where the gas matrix containing high level of interfering gases of the stack gas exists. If the comparison with the reference method shows that the alternative method is valid and if there are no technical reasons against it, the transfer of the validity from this type of plant to other kinds of plants shall be made regular. NOTE In the type approval or certification scheme for emission measurements, it is agreed that if the suitability of a method is demonstrated on a waste incineration, then this suitability can be extended to other types of plants with different gas matrixes like combustion or co-combustion plants. 5.5.1.3 Concentration range If the alternative method has shown in the laboratory an acceptable linearity (see 5.3) and expanded uncertainty (see 5.4) then the comparison in the field does not need to be carried out on the whole claimed concentration range where linearity has been checked. However, to be relevant, the statistical test for checking if there is no systematic deviation between AM and RM measurements, perform measurements in the field over all the claimed concentration range. At least 30 % of the total number of parallel measurements shall be performed in the lower 20 % of the range and at least 30 % in the upper third of the range. Criteria of acceptance of the demonstration are given in 5.5.2.3.3. To perform the demonstration and succeed to study a large concentration range, a combination of two sets of data drawn from trials performed on one or several plants of the same type can be accepted. An alternative might be to perform the comparison on a test bench recognized by the competent authorities to be able to generate the appropriate gas matrix. In this case, the test bench shall meet the requirements in Annex C.

If the claimed concentration range has not been chosen correctly, it can be limited, particularly if the repeatability or systematic deviation studies show that it is not possible to fulfil the criteria for acceptance of repeatability and trueness across the whole range of concentrations. In such cases, the AM shall be validated in one or more limited set of conditions. A validation file fulfilling the criteria for acceptance of the demonstration given in 5.5.2.2 and 5.5.2.3.3 is required for each range of concentration. SIST EN 14793:2017

EN 14793:2017 (E) 15 5.5.2 Evaluation of repeatability and trueness in relation to the RM 5.5.2.1 Organization In field demonstration of equivalence enables the comparison of repeatability standard deviations (see Table 2) and the determination of the regression line between AM and RM results to evaluate systematic deviation (trueness) in relation to the RM. To obtain comparison data of the AM and RM, perform simultaneously at least 30 measurements with the AM and with the RM, so that Table 2 can be drawn up. The number ni shall be at least two (paired measurements) and should be identical for each trial i. Table 2 — Organization of the in field demonstration Alternative method

Trials Parallel measurements Number of
measurements Means Variances
1 2 ...
ix ()2isx.
11x
12x ...
11nx
()21sx
... ... ... ... ... ... ... ...
1ix
2ix ...
iinx
()2isx
... ... ... ... ... ... ... ...
1px
2px ...
ppnx
()2psx
Reference method Trials Parallel measurements Number of
measurements Means Variances Differences
1 2 ...
()2isz
iixz− 1
11z
12z ...
11nz 1n
()21sz
11xz− ... ... ... ... ... ... ... ...
1iz
2iz ...
iinz
()2isz
iixz− ... ... ... ... ... ... ... ...
1pz
2pz ...
ppnz
()2psz

ppxz− 5.5.2.2 Repeatability Perform the calculations following the principle described in ISO 5725-2 according to the formulae given in Table 1. Apply them separately to each series of data and calculate the repeatability variances ()2rsx and ()2rsz for the AM and the RM. The two standard deviations ()rsx and ()rsz are deduced from these variances. Acceptance criteria for repeatability of the AM and RM in Formula (1) and Formula (2) shall be met: SIST EN 14793:2017

EN 14793:2017 (E) 16 ()(),limitrrsxsz≤ (1) ()(),limitrrszsz≤ (2) where the value of (),limitrsz is obtained from an equation of the maximum allowable repeatability standard deviation given in the RM standard. If this value is not specified in the RM standard, the laboratory shall determine this value from the standard deviation of the paired measurements of the RM. 5.5.2.3 Trueness 5.5.2.3.1 General The trueness of the AM is demonstrated on the basis of a linear relation between the two series of data obtained by the RM and AM with a slope close to one and an intercept close to zero (see criteria of acceptance in 5.5.2.3.3). In most cases the classical linear regression cannot be used because the uncertainty attached to each result given by the RM is not always negligible compared to the uncertainty of individual results given by the AM. Consequently, the orthogonal linear regression model shall be used. The regression line is computed so that the sum of the square orthogonal distances between the points and the line is minimal. The orthogonal regression is symmetrical in x and z and does not depend on the way the points have been plotted (see Figure 1).

Figure 1 — Illustration of orthogonal linear regression The orthogonal linear relation between

...

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