Stationary source emissions - Determination of mass concentration of sulphur oxides - Standard reference method

This European Standard specifies the standard reference method (SRM) for the determination of the sulphuric oxide SO2 in flue gases emitted to the atmosphere from ducts and stacks. It is based on a sampling system and two analytical principles: ion chromatography and the Thorin method.
This European Standard specifies the performance characteristics to be determined and the performance criteria to be fulfilled by measuring systems based on the measurement method. It applies to periodic monitoring and to the calibration or control of automatic measuring systems (AMS) permanently installed on a stack, for regulatory or other purposes.
This European Standard specifies criteria for demonstration of equivalence of an alternative method to the SRM by application of prEN 14793.
This European Standard has been evaluated during field tests on waste incineration, co-incineration and large combustion installations. It has been validated for sampling periods of 30 min in the range of 0,5 mg/m³ to 2 000 mg/m³ of SO2 for an ion-chromatography variant and 5 mg/m³ to 2 000 mg/m³ of SO2 for the Thorin method according to emission limit values laid down in the Directive 2010/75/EC.
The limit values of EU Directives are expressed in units of mg/m³ of SO2 on dry basis and at standard conditions of 273 K and 101,3 kPa.
NOTE   The characteristics of installations, the conditions during field tests and the values of repeatability and reproducibility in the field are given in Annex E.

Emissionen aus stationären Quellen - Bestimmung der Massenkonzentration von Schwefeloxiden - Standardreferenzverfahren

Diese Europäische Norm legt das Standardreferenzverfahren (SRM) zur Bestimmung des SO2-Gehalts in Abgasen, die aus Abgaskanälen in die Atmosphäre emittiert werden, fest. Es basiert auf einer Probenahmeeinrichtung und zwei analytischen Verfahren: die Ionenchromatographie und das Thorin-Verfahren.
Diese Europäische Norm legt zu bestimmende Verfahrenskenngrößen und Mindestanforderungen fest, die von Messeinrichtungen auf Basis dieses Messverfahrens eingehalten werden müssen. Sie gilt für wiederkehrende Messungen und für die Kalibrierung oder Überprüfung von automatischen Messeinrichtungen (AMS), die aus gesetzgeberischen oder anderen Gründen stationär an einem Abgaskanal installiert sind.
Diese Europäische Norm legt Anforderungen zum Nachweis der Gleichwertigkeit von Alternativverfahren (AM) mit dem Standardreferenzverfahren (SRM) durch Anwendung der prEN 14793 fest.
Diese Europäische Norm wurde in Feldversuchen an Abfallverbrennungsanlagen, Mitverbrennungsanlagen und Großfeuerungsanlagen validiert. Sie wurde mit Probenahmedauern von 30 min im Bereich von 0,5 mg/m3 bis 2 000 mg/m3 SO2 mit der ionenchromatographischen Variante und von 5 mg/m3 bis 2 000 mg/m3 SO2 für das Thorin-Verfahren validiert, entsprechend den in der Richtlinie 2010/75/EU festgelegten Emissionsgrenzwerten.
   In den EU-Richtlinien werden die Grenzwerte ausgedrückt in Milligramm SO2 je Kubikmeter in trockenem Gas und bei Normbedingungen von 273 K und 101,3 kPa.
ANMERKUNG   Die Einzelheiten der Anlagen, die Bedingungen bei den Feldversuchen und die Werte der Wiederhol- und der Vergleichpräzision im Feld werden in Anhang E aufgeführt.

Emissions de sources fixes - Détermination de la concentration massique des oxydes de soufre - Méthode de référence normalisée

La présente Norme européenne spécifie la méthode de référence normalisée (SRM) pour la détermination du dioxyde de soufre SO2 dans les effluents gazeux émis dans l'atmosphère par les conduits et cheminées. Elle est basée sur un système de prélèvement et deux principes d'analyse : la chromatographie d'échange d'ions et la méthode au Thorin.
La présente Norme européenne spécifie les caractéristiques de performance devant être déterminées et les critères de performance devant être remplis par les systèmes de mesurage fondés sur cette méthode de mesurage. Elle s'applique à la surveillance périodique et à l'étalonnage ou au contrôle des systèmes de mesurage automatisés (AMS, Automatic Measuring Systems) installés à demeure sur une cheminée, à des fins réglementaires ou à d'autres fins.
La présente Norme européenne spécifie les critères permettant de démontrer l'équivalence d'une méthode « alternative » à la méthode de référence normalisée par l'application du prEN 14793.
La présente Norme européenne a été évaluée au cours d’essais sur site pratiqués sur les installations destinées à l’incinération des déchets, à la coincinération et sur des grandes installations de combustion. Elle a été validée pour des périodes de prélèvement de 30 min, dans la gamme de 0,5 mg/m3 à 2 000 mg/m3 de SO2 pour la chromatographie d'échange d'ions et de 5 mg/m3 à 2 000 mg/m3 of SO2 pour la méthode au Thorin, conformément aux valeurs limites d'émission spécifiées dans la Directive 2010/75/CE.
Les valeurs limites des directives UE sont exprimées en mg/m3 de SO2, sur gaz secs et dans les conditions normales de 273 K et 101,3 kPa.
NOTE   Les caractéristiques des installations, les conditions des essais sur site et les valeurs de répétabilité et de reproductibilité sur site sont indiquées à l'Annexe E.

Emisije nepremičnih virov - Določevanje masne koncentracije žveplovih oksidov - Standardna referenčna metoda

Ta evropski standard določa standardno referenčno metodo (SRM) za določanje žveplovega dioksida SO2 v dimnih plinih, ki prehajajo v ozračje iz vodov in odvodnikov. Temelji na sistemu vzorčenja in dveh analitičnih metodah: ionski kromatografiji in Thorinovi metodi.
Ta evropski standard določa lastnosti zmogljivosti in merila zmogljivosti, ki jih morajo izpolnjevati merilni sistemi na podlagi te merilne metode. Uporablja se za redno spremljanje in umerjanje ali nadzor avtomatskih merilnih sistemov (AMS), ki so trajno nameščeni na odvodnik, in sicer za zakonske ter druge namene.
Ta evropski standard določa merila za prikaz enakovrednosti alternativne metode standardni referenčni metodi z uporabo standarda prEN 14793.
Ta evropski standard je bil ocenjen med preskusi sežiganja odpadkov, sosežiga in velikih kurilnih naprav na terenu. Potrjen je bil za 30-minutna obdobja vzorčenja v razponu 0,5–2000 mg/m³ SO2 za različico z ionsko kromatografijo in 5–2000 mg/m³ SO2 za Thorinovo metodo v skladu z mejnimi vrednostmi emisij, opredeljenimi v Direktivi 2010/75/ES.
Mejne vrednosti direktiv EU so izražene v mg/m³ SO2 na suhi osnovi in pri standardnih pogojih 273 K in 101,3 kPa.
OPOMBA:   Lastnosti naprav, pogoji med preskusi na terenu ter vrednosti ponovljivosti in reprodukcije na terenu so podani 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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SLOVENSKI STANDARD
SIST EN 14791:2017
01-julij-2017
Nadomešča:
SIST EN 14791:2005
Emisije nepremičnih virov - Določevanje masne koncentracije žveplovih oksidov -
Standardna referenčna metoda
Stationary source emissions - Determination of mass concentration of sulphur oxides -
Standard reference method
Emissionen aus stationären Quellen - Bestimmung der Massenkonzentration von
Schwefeloxiden - Standardreferenzverfahren
Emissions de sources fixes - Détermination de la concentration massique des oxydes de
soufre - Méthode de référence normalisée
Ta slovenski standard je istoveten z: EN 14791:2017
ICS:
13.040.40 Emisije nepremičnih virov Stationary source emissions
SIST EN 14791:2017 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 14791:2017

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SIST EN 14791:2017


EN 14791
EUROPEAN STANDARD

NORME EUROPÉENNE

January 2017
EUROPÄISCHE NORM
ICS 13.040.40 Supersedes EN 14791:2005
English Version

Stationary source emissions - Determination of mass
concentration of sulphur oxides - Standard reference
method
Emissions de sources fixes - Détermination de la Emissionen aus stationären Quellen - Bestimmung der
concentration massique des oxydes de soufre - Massenkonzentration von Schwefeloxiden -
Méthode de référence normalisée Standardreferenzverfahren
This European Standard was approved by CEN on 26 September 2016.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of 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 United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14791:2017 E
worldwide for CEN national Members.

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SIST EN 14791:2017
EN 14791:2017 (E)
Contents Page

European foreword . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Symbols and abbreviations . 13
4.1 Symbols . 13
4.2 Abbreviated terms . 14
5 Principle . 14
5.1 General . 14
5.2 Measuring principle . 14
6 Description of measuring system . 15
6.1 Reagents . 15
6.1.1 General . 15
6.1.2 Hydrogen peroxide . 15
6.1.3 Water . 15
6.1.4 Absorption solution, H O . 15
2 2
6.1.5 Reagents for chromatographic analysis . 15
6.1.6 Reagent for Thorin analysis . 16
6.2 Sampling equipment . 17
6.2.1 General . 17
6.2.2 Sampling probe . 17
6.2.3 Filter housing . 17
6.2.4 Particle filter . 18
6.2.5 Temperature controller . 18
6.2.6 Absorbers . 18
6.2.7 Sample gas pump . 18
6.2.8 Gas volume meter . 18
6.3 Analysis equipment . 19
6.3.1 Ion chromatograph . 19
6.3.2 Thorin method . 19
7 Performance characteristics of the SRM . 20
7.1 General . 20
7.2 Performance characteristics of the sampling system . 21
7.3 Performance characteristics of the analysis . 21
7.3.1 Sources of uncertainty . 21
7.3.2 Performance criterion of analysis . 22
7.4 Establishment of the uncertainty budget . 22
8 Field operation . 23
8.1 Measurement planning . 23
8.2 Sampling strategy. 23
8.2.1 General . 23
8.2.2 Measurement section and measurement plane . 23
2

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EN 14791:2017 (E)
8.2.3 Minimum number and location of measurement points . 24
8.2.4 Measurement ports and working platform . 24
8.3 Assembling the equipment. 24
8.4 Heating of the sample gas line . 24
8.5 Leak test . 24
8.6 Performing sampling . 25
8.6.1 Introduction of the sampling probe in the duct . 25
8.6.2 Sampling . 25
8.6.3 Rinsing of the sampling system and preparation of the samples . 25
8.7 Measurement series . 26
8.8 Field blank . 26
8.9 Absorption efficiency . 26
8.9.1 General . 26
8.9.2 Test of absorption efficiency . 26
9 Analytical procedure . 27
9.1 General . 27
9.2 Ion Chromatography method . 27
9.2.1 General procedure . 27
9.2.2 Interferences . 28
9.2.3 Calibration. 28
9.3 Thorin Method . 29
9.3.1 Pre-treatment of sample solution before analysis for Thorin method . 29
9.3.2 General procedure . 29
9.3.3 Preparation of a chemical blank solution . 30
9.3.4 Interferents . 30
10 Expression of results . 31
11 Equivalence of Thorin and ion chromatography methods . 33
11.1 General . 33
11.2 Range . 33
11.3 Matrix effect . 33
11.4 Comparison of repeatability and trueness . 33
12 Equivalence of an alternative method . 34
13 Measurement report . 34
Annex A (informative) Validation of the method in the field. 35
A.1 General . 35
A.2 Round robin test of analytical methods . 35
A.3 Field tests . 36
A.3.1 General . 36
A.3.2 Characteristics of installations . 36
A.3.3 Limits of quantification . 38
A.3.4 Repeatability and reproducibility . 38
A.3.4.1 General . 38
A.3.4.2 Repeatability . 39
A.3.4.3 Reproducibility . 41
A.3.5 Absorption efficiency . 42
3

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EN 14791:2017 (E)
Annex B (informative) Examples of absorbers . 43
Annex C (informative) Example of assessment of compliance of standard reference method
for SO with requirements on emission measurements . 44
2
C.1 Introduction . 44
C.2 Elements required for the uncertainty determinations . 44
C.3 Example of an uncertainty calculation . 44
C.3.1 Specific conditions in the field. 44
C.3.2 Performance characteristics . 46
C.3.3 Model equation and application of rule of uncertainty propagation . 47
C.3.3.1 Concentration of SO . 47
2
V
C
m,ref
m
C.3.3.2 Calculation of the combined uncertainty of and . 48
C.3.3.3 Calculation of sensitivity coefficients . 48
C.3.3.4 Results of the standard uncertainties calculations. 49
C.3.4 Estimation of the combined uncertainty . 52
Annex D (informative) Type of sampling equipment . 53
Annex E (informative) Example of comparison of repeatability and trueness of Thorin
Method and Ion Chromatography Method . 54
Annex F (informative) Calculation of the uncertainty associated with a concentration
expressed on dry gas and at an oxygen reference concentration . 64
F.1 Uncertainty associated with a concentration expressed on dry gas . 64
F.2 Uncertainty associated with a concentration expressed at a oxygen reference
concentration . 66
Annex G (informative) Significant technical changes . 68
Bibliography . 69


4

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SIST EN 14791:2017
EN 14791:2017 (E)
European foreword
This document (EN 14791:2017) has been prepared by Technical Committee CEN/TC 264 “Air quality”,
the secretariat of which is held by DIN.
This document supersedes EN 14791:2005.
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.
Annex G provides details of significant technical changes between this document and the previous
edition.
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.
5

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SIST EN 14791:2017
EN 14791:2017 (E)
1 Scope
This European Standard specifies the standard reference method (SRM) for the determination of the
sulphuric oxide SO in flue gases emitted to the atmosphere from ducts and stacks. It is based on a
2
sampling system and two analytical principles: ion chromatography and the Thorin method.
This European Standard specifies the performance characteristics to be determined and the
performance criteria to be fulfilled by measuring systems based on the measurement method. It applies
to periodic monitoring and to the calibration or control of automatic measuring systems (AMS)
permanently installed on a stack, for regulatory or other purposes.
This European Standard specifies criteria for demonstration of equivalence of an alternative method to
the SRM by application of EN 14793:2017.
This European Standard has been validated during field tests on waste incineration, co-incineration and
large combustion installations. It has been validated for sampling periods of 30 min in the range of
3 3 3 3
0,5 mg/m to 2 000 mg/m of SO for an ion-chromatography variant and 5 mg/m to 2 000 mg/m of
2
SO for the Thorin method according to emission limit values laid down in the Directive 2010/75/EU.
2
3
NOTE 1 Emission limit values for SO laid down in the Directive 2010/75/EU are in the range of 30 mg/m to
2
3
800 mg/m .
3
The emission limit values of EU Directives are expressed in units of mg/m of SO on dry basis and at
2
standard conditions of 273 K and 101,3 kPa.
NOTE 2 The characteristics of installations, the conditions during field tests and the values of repeatability and
reproducibility in the field are given 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.
prEN 13284-1:2015, Stationary source emissions ― Determination of low range mass concentration of
dust ― Part 1: Manual gravimetric method
EN 14793:2017, Stationary source emission – Demonstration of equivalence of an alternative method with
a reference method
EN 15259:2007, Air quality - Measurement of stationary source emissions - Requirements for
measurement sections and sites and for the measurement objective, plan and report
EN ISO 14956:2002, Air quality - Evaluation of the suitability of a measurement procedure by comparison
with a required measurement uncertainty (ISO 14956:2002)
ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty
in measurement (GUM:1995)
6

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SIST EN 14791:2017
EN 14791:2017 (E)
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]
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
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
[SOURCE: EN 14793:2017]
3.4
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.
[SOURCE: EN 14793:2017]
3.5
measuring system
set of one or more measuring instruments and often other devices, including any reagent and supply,
assembled and adapted to give information used to generate measured quantity values within specified
intervals for quantities of specified kinds
[SOURCE: JCGM 200:2012]
7

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SIST EN 14791:2017
EN 14791:2017 (E)
3.6
automated measuring system
AMS
entirety of all measuring instruments and additional devices for obtaining a result of measurement
Note 1 to entry: Apart from the actual measuring device (the analyser), an AMS includes facilities for taking
samples (e.g. probe, sample gas lines, flow meters and regulator, delivery pump) and for sample conditioning (e.g.
dust filter, pre-separator for interferents, cooler, converter). This definition also includes testing and adjusting
devices that are required for functional checks and, if applicable, for commissioning.
Note 2 to entry: The term “automated measuring system” (AMS) is typically used in Europe. The term
“continuous emission monitoring system” (CEMS) is also typically used in the UK and USA.
[SOURCE: EN 15267-4:2017]
3.7
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
Note 1 to entry: In case of automated measuring systems (AMS) permanently installed on a stack the applicable
reference is the standard reference method (SRM) used to establish the calibration function of the AMS.
Note 2 to entry: In case of manual methods the applicable reference can be reference materials used as
calibration standards to establish the relationship between the output signal of the analytical device and the
reference values.
Note 3 to entry: Calibration should not be confused with adjustment of a measuring system.
3.8
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.
3.9
influence quantity
quantity that is not the measurand but that affects the result of the measurement
Note 1 to entry: Influence quantities are e.g. ambient temperature, atmospheric pressure, presence of
interfering gases in the flue gas matrix or pressure of the gas sample.
3.10
measurement series
several successive measurements carried out on the same measurement plane and at the same process
operating conditions
8

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SIST EN 14791:2017
EN 14791:2017 (E)
3.11
measurement site
place on the waste gas duct in the area of the measurement plane(s) consisting of structures and
technical equipment, for example working platforms, measurement ports, energy supply
Note 1 to entry: Measurement site is also known as sampling site.
[SOURCE: EN 15259:2007]
3.12
measurement plane
plane normal to the centreline of the duct at the sampling position
Note 1 to entry: Measurement plane is also known as sampling plane.
[SOURCE: EN 15259:2007]
3.13
measurement port
opening in the waste gas duct along the measurement line, through which access to the waste gas is
gained
Note 1 to entry: Measurement port is also known as sampling port or access port.
[SOURCE: EN 15259:2007]
3.14
measurement line
line in the measurement plane along which the measurement points are located, bounded by the inner
duct wall
Note 1 to entry: Measurement line is also known as sampling line.
[SOURCE: EN 15259:2007]
3.15
measurement point
position in the measurement plane at which the sample stream is extracted or the measurement data
are obtained directly
Note 1 to entry: Measurement point is also known as sampling point.
[SOURCE: EN 15259:2007]
3.16
performance characteristic
one of the quantities (described by value
...

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Emissionen aus stationären Quellen - Bestimmung der Massenkonzentration von Schwefeloxiden - StandardreferenzverfahrenEmissions de sources fixes - Détermination de la concentration massique des oxydes de soufre - Méthode de référence normaliséeStationary source emissions - Determination of mass concentration of sulphur oxides - Standard reference method13.040.40Stationary source emissionsICS:Ta slovenski standard je istoveten z:EN 14791:2017SIST EN 14791:2017en,fr,de01-julij-2017SIST EN 14791:2017SLOVENSKI
STANDARDSIST EN 14791:20051DGRPHãþD



SIST EN 14791:2017



EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 14791
January
t r s y ICS
s uä r v rä v r Supersedes EN
s v y { sã t r r wEnglish Version
Stationary source emissions æ Determination of mass concentration of sulphur oxides æ Standard reference method Emissions de sources fixes æ Détermination de la concentration massique des oxydes de soufre æ Méthode de référence normalisée
Emissionen aus stationären Quellen æ Bestimmung der Massenkonzentration von Schwefeloxiden æ Standardreferenzverfahren 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
9
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 { sã t r s y ESIST EN 14791:2017



EN 14791:2017 (E) 2 Contents Page
European foreword . 5 1 Scope . 6 2 Normative references . 6 3 Terms and definitions . 7 4 Symbols and abbreviations . 13 4.1 Symbols . 13 4.2 Abbreviated terms . 14 5 Principle . 14 5.1 General . 14 5.2 Measuring principle . 14 6 Description of measuring system . 15 6.1 Reagents . 15 6.1.1 General . 15 6.1.2 Hydrogen peroxide . 15 6.1.3 Water . 15 6.1.4 Absorption solution, H2O2 . 15 6.1.5 Reagents for chromatographic analysis . 15 6.1.6 Reagent for Thorin analysis . 16 6.2 Sampling equipment . 17 6.2.1 General . 17 6.2.2 Sampling probe . 17 6.2.3 Filter housing . 17 6.2.4 Particle filter . 18 6.2.5 Temperature controller . 18 6.2.6 Absorbers . 18 6.2.7 Sample gas pump . 18 6.2.8 Gas volume meter . 18 6.3 Analysis equipment . 19 6.3.1 Ion chromatograph . 19 6.3.2 Thorin method . 19 7 Performance characteristics of the SRM . 20 7.1 General . 20 7.2 Performance characteristics of the sampling system . 21 7.3 Performance characteristics of the analysis . 21 7.3.1 Sources of uncertainty . 21 7.3.2 Performance criterion of analysis . 22 7.4 Establishment of the uncertainty budget . 22 8 Field operation . 23 8.1 Measurement planning . 23 8.2 Sampling strategy. 23 8.2.1 General . 23 8.2.2 Measurement section and measurement plane . 23 SIST EN 14791:2017



EN 14791:2017 (E) 3 8.2.3 Minimum number and location of measurement points . 24 8.2.4 Measurement ports and working platform . 24 8.3 Assembling the equipment. 24 8.4 Heating of the sample gas line . 24 8.5 Leak test . 24 8.6 Performing sampling . 25 8.6.1 Introduction of the sampling probe in the duct . 25 8.6.2 Sampling . 25 8.6.3 Rinsing of the sampling system and preparation of the samples . 25 8.7 Measurement series . 26 8.8 Field blank . 26 8.9 Absorption efficiency . 26 8.9.1 General . 26 8.9.2 Test of absorption efficiency . 26 9 Analytical procedure . 27 9.1 General . 27 9.2 Ion Chromatography method . 27 9.2.1 General procedure . 27 9.2.2 Interferences . 28 9.2.3 Calibration. 28 9.3 Thorin Method . 29 9.3.1 Pre-treatment of sample solution before analysis for Thorin method . 29 9.3.2 General procedure . 29 9.3.3 Preparation of a chemical blank solution . 30 9.3.4 Interferents . 30 10 Expression of results . 31 11 Equivalence of Thorin and ion chromatography methods . 33 11.1 General . 33 11.2 Range . 33 11.3 Matrix effect . 33 11.4 Comparison of repeatability and trueness . 33 12 Equivalence of an alternative method . 34 13 Measurement report . 34 Annex A (informative)
Validation of the method in the field. 35 A.1 General . 35 A.2 Round robin test of analytical methods . 35 A.3 Field tests . 36 A.3.1 General . 36 A.3.2 Characteristics of installations . 36 A.3.3 Limits of quantification . 38 A.3.4 Repeatability and reproducibility . 38 A.3.4.1 General . 38 A.3.4.2 Repeatability . 39 A.3.4.3 Reproducibility . 41 A.3.5 Absorption efficiency . 42 SIST EN 14791:2017



EN 14791:2017 (E) 4 Annex B (informative)
Examples of absorbers . 43 Annex C (informative)
Example of assessment of compliance of standard reference method for SO2 with requirements on emission measurements . 44 C.1 Introduction . 44 C.2 Elements required for the uncertainty determinations . 44 C.3 Example of an uncertainty calculation . 44 C.3.1 Specific conditions in the field. 44 C.3.2 Performance characteristics . 46 C.3.3 Model equation and application of rule of uncertainty propagation . 47 C.3.3.1 Concentration of SO2 . 47 C.3.3.2 Calculation of the combined uncertainty of m,refV and mC . 48 C.3.3.3 Calculation of sensitivity coefficients . 48 C.3.3.4 Results of the standard uncertainties calculations. 49 C.3.4 Estimation of the combined uncertainty . 52 Annex D (informative)
Type of sampling equipment . 53 Annex E (informative)
Example of comparison of repeatability and trueness
of Thorin Method and Ion Chromatography Method . 54 Annex F (informative)
Calculation of the uncertainty associated with a concentration expressed on dry gas and at an oxygen reference concentration . 64 F.1 Uncertainty associated with a concentration expressed on dry gas . 64 F.2 Uncertainty associated with a concentration expressed at a oxygen reference concentration . 66 Annex G (informative)
Significant technical changes . 68 Bibliography . 69
SIST EN 14791:2017



EN 14791:2017 (E) 5 European foreword This document (EN 14791:2017) has been prepared by Technical Committee CEN/TC 264 “Air quality”, the secretariat of which is held by DIN. This document supersedes EN 14791:2005. 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. Annex G provides details of significant technical changes between this document and the previous edition. 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 14791:2017



EN 14791:2017 (E) 6 1 Scope This European Standard specifies the standard reference method (SRM) for the determination of the sulphuric oxide SO2 in flue gases emitted to the atmosphere from ducts and stacks. It is based on a sampling system and two analytical principles: ion chromatography and the Thorin method.
This European Standard specifies the performance characteristics to be determined and the performance criteria to be fulfilled by measuring systems based on the measurement method. It applies to periodic monitoring and to the calibration or control of automatic measuring systems (AMS) permanently installed on a stack, for regulatory or other purposes.
This European Standard specifies criteria for demonstration of equivalence of an alternative method to the SRM by application of EN 14793:2017. This European Standard has been validated during field tests on waste incineration, co-incineration and large combustion installations. It has been validated for sampling periods of 30 min in the range of 0,5 mg/m3 to 2 000 mg/m3 of SO2 for an ion-chromatography variant and 5 mg/m3 to 2 000 mg/m3 of SO2 for the Thorin method according to emission limit values laid down in the Directive 2010/75/EU. NOTE 1
Emission limit values for SO2 laid down in the Directive 2010/75/EU are in the range of 30 mg/m3 to 800 mg/m3. The emission limit values of EU Directives are expressed in units of mg/m3 of SO2 on dry basis and at standard conditions of 273 K and 101,3 kPa. NOTE 2 The characteristics of installations, the conditions during field tests and the values of repeatability and reproducibility in the field are given 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. prEN 13284-1:2015, Stationary source
wã Manual gravimetric method EN 14793:2017, Stationary source emission – Demonstration of equivalence of an alternative method with a reference method EN 15259:2007, Air quality - Measurement of stationary source emissions - Requirements for measurement sections and sites and for the measurement objectiveá plan and report EN ISO 14956:2002, Air quality - Evaluation of the suitability of a measurement procedure by comparison with a required measurement uncertainty (ISO 14956:2002) ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part
yã Guide to the expression of uncertainty in measurement (GUM:1995) SIST EN 14791:2017



EN 14791:2017 (E) 7 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] 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
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 [SOURCE: EN 14793:2017] 3.4 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. [SOURCE: EN 14793:2017] 3.5 measuring system set of one or more measuring instruments and often other devices, including any reagent and supply, assembled and adapted to give information used to generate measured quantity values within specified intervals for quantities of specified kinds
[SOURCE: JCGM 200:2012] SIST EN 14791:2017



EN 14791:2017 (E) 8 3.6 automated measuring system AMS entirety of all measuring instruments and additional devices for obtaining a result of measurement Note 1 to entry: Apart from the actual measuring device (the analyser), an AMS includes facilities for taking samples (e.g. probe, sample gas lines, flow meters and regulator, delivery pump) and for sample conditioning (e.g. dust filter, pre-separator for interferents, cooler, converter). This definition also includes testing and adjusting devices that are required for functional checks and, if applicable, for commissioning. Note 2 to entry: The term “automated measuring system” (AMS) is typically used in Europe. The term “continuous emission monitoring system” (CEMS) is also typically used in the UK and USA. [SOURCE: EN 15267-4:2017] 3.7 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
Note 1 to entry: In case of automated measuring systems (AMS) permanently installed on a stack the applicable reference is the standard reference method (SRM) used to establish the calibration function of the AMS. Note 2 to entry: In case of manual methods the applicable reference can be reference materials used as calibration standards to establish the relationship between the output signal of the analytical device and the reference values.
Note 3 to entry: Calibration should not be confused with adjustment of a measuring system. 3.8 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. 3.9 influence quantity quantity that is not the measurand but that affects the result of the measurement Note 1 to entry: Influence quantities are e.g. ambient temperature, atmospheric pressure, presence of interfering gases in the flue gas matrix or pressure of the gas sample. 3.10 measurement series several successive measurements carried out on the same measurement plane and at the same process operating conditions SIST EN 14791:2017



EN 14791:2017 (E) 9 3.11 measurement site place on the waste gas duct in the area of the measurement plane(s) consisting of structures and technical equipment, for example working platforms, measurement ports, energy supply
Note 1 to entry: Measurement site is also known as sampling site. [SOURCE: EN 15259:2007] 3.12 measurement plane plane normal to the centreline of the duct at the sampling position Note 1 to entry: Measurement plane is also known as sampling plane. [SOURCE: EN 15259:2007] 3.13 measurement port opening in the waste gas duct along the measurement line, through which access to the waste gas is gained Note 1 to entry: Measurement port is also known as sampling port or access port. [SOURCE: EN 15259:2007] 3.14 measurement line line in the measurement plane along which the measurement points are located, bounded by the inner duct wall Note 1 to entry: Measurement line is also known as sampling line. [SOURCE: EN 15259:2007] 3.15 measurement point position in the measurement plane at which the sample stream is extracted or the measurement data are obtained directly
Note 1 to entry: Measurement point is also known as sampling point. [SOURCE: EN 15259:2007] 3.16 performance characteristic one of the quantities (described by values, tolerances, range) assigned to equipment in order to define its performance SIST EN 14791:2017



EN 14791:2017 (E) 10 3.17 quantification limit lowest amount of an analyte that is quantifiable with a given confidence level Note 1 to entry:
For a manual method the limit of quantification is usually calculated as 10 times the standard deviation of blank measurements provided that the blank value is negligible. This corresponds to a confidence level of 95 %.
3.18 absorption efficiency
ratio of quantity of the analyte q1 collected in the first absorber divided by the quantity of the analyte collected in the first and the second absorber (q1 + q2)
= q1 / (q1 + q2) 3.19 absorber device in which sulphur oxide is absorbed into an absorption liquid 3.20 repeatability in the laboratory closeness of the agreement between the results of successive measurements of the same measurand carried out under the same conditions of measurement Note 1 to entry: These conditions include: — same measurement method; — same laboratory; — same measuring system, used under the same conditions; — same location; — repetition over a short period of time. Note 2 to entry: Repeatability can be expressed quantitatively in terms of the dispersion characteristics of the results. Note 3 to entry: In this European Standard the repeatability is expressed as a value
...

SLOVENSKI STANDARD
oSIST prEN 14791:2015
01-januar-2015
(PLVLMHQHSUHPLþQLKYLURY'RORþHYDQMHPDVQHNRQFHQWUDFLMHåYHSORYLKGLRNVLGRY
6WDQGDUGQDUHIHUHQþQDPHWRGD
Stationary source emissions - Determination of mass concentration of sulphur oxides -
Standard reference method
Emissionen aus stationären Quellen - Bestimmung der Massenkonzentration von
Schwefeloxiden - Standardreferenzverfahren
Emissions de sources fixes - Détermination de la concentration massique des oxydes de
soufre - Méthode de référence normalisée
Ta slovenski standard je istoveten z: prEN 14791
ICS:
13.040.40 (PLVLMHQHSUHPLþQLKYLURY Stationary source emissions
oSIST prEN 14791:2015 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 14791:2015

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oSIST prEN 14791:2015

EUROPEAN STANDARD
DRAFT
prEN 14791
NORME EUROPÉENNE

EUROPÄISCHE NORM

October 2014
ICS 13.040.40 Will supersede EN 14791:2005
English Version
Stationary source emissions - Determination of mass
concentration of sulphur oxides - Standard reference method
Emissions de sources fixes - Détermination de la Emissionen aus stationären Quellen - Bestimmung der
concentration massique des oxydes de soufre - Méthode de Massenkonzentration von Schwefeloxiden -
référence normalisée Standardreferenzverfahren
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 264.

If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which
stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other language
made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to
provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2014 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 14791:2014 E
worldwide for CEN national Members.

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prEN 14791:2014 (E)
Contents
Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Terms and definitions .4
4 Symbols and abbreviated terms .9
5 Measuring principle . 10
6 Description of measuring equipment . 11
7 Performance characteristics of the SRM . 16
8 Sampling procedure . 19
9 Analytical procedure . 22
10 Expression of results . 26
11 Equivalence of Thorin and ion chromatography methods . 28
12 Equivalence with an alternative method . 28
13 Test report . 29
Annex A (informative) Type of sampling equipment . 30
Annex B (informative) Examples of absorbers . 31
Annex C (informative) Evaluation of the method in the field . 32
Annex D (informative) Example of assessment of compliance or reference method for SO with
2
requirements on emission measurements . 39
Annex E (informative) Test of equivalency of Thorin method and ion chromatography . 46
Annex F (informative) Calculation of the uncertainty associated with a concentration expressed
on dry gas and at a oxygen reference concentration . 52
Annex G (informative) Significant technical changes . 56
Bibliography . 57

2

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Foreword
This document (prEN 14791:2014) has been prepared by Technical Committee CEN/TC 264 “Air quality”, the
secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 14791:2005.
Annex G provides details of significant technical changes between this document and the previous edition.
3

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prEN 14791:2014 (E)
1 Scope
This European Standard specifies the standard reference method (SRM) for the determination of the sulphuric
oxide SO in flue gases emitted to the atmosphere from ducts and stacks. It is based on a sampling system
2
and two analytical principles: ion chromatography and the Thorin method.
This European Standard specifies the performance characteristics to be determined and the performance
criteria to be fulfilled by measuring systems based on the measurement method. It applies to periodic
monitoring and to the calibration or control of automatic measuring systems (AMS) permanently installed on a
stack, for regulatory or other purposes.
This European Standard specifies criteria for demonstration of equivalence of an alternative method to the
SRM by application of prEN 14793.
This European Standard has been evaluated during field tests on waste incineration, co-incineration and large
3
combustion installations. It has been validated for sampling periods of 30 min in the range of 0,5 mg/m to
3 3 3
2 000 mg/m of SO for an ion-chromatography variant and 5 mg/m to 2 000 mg/m of SO for the Thorin
2 2
method according to emission limit values laid down in the Directive 2010/75/EC.
3
The limit values of EU Directives are expressed in units of mg/m of SO on dry basis and at standard
2
conditions of 273 K and 101,3 kPa.
NOTE The characteristics of installations, the conditions during field tests and the values of repeatability and
reproducibility in the field are given in Annex E.
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.
prEN 14793:2014, Stationary source emission – Demonstration of equivalence of an alternative method with a
reference method
EN 15259:2007, Air quality – Measurement of stationary source emissions – Requirements for measurement
sections and sites and for the measurement objective, plan and report
EN ISO 14956:2002, Air quality – Evaluation of the suitability of a measurement procedure by comparison
with a required measurement uncertainty (ISO 14956:2002)
ISO/IEC Guide 98-3:2008, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
absorber
device in which sulphur oxide is absorbed into an absorption liquid
4

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3.2
absorption efficiency
ε
ratio of quantity of the analyte q collected in the first absorber divided by the quantity of the analyte collected
1
in the first and the second absorber (q + q )
1 2
ε = q / (q + q )
1 1 2
3.3
automated measuring system
AMS
measuring system permanently installed on site for continuous monitoring of emissions or measurement of
peripheral parameters
Note 1 to entry: An AMS is a method which is traceable to a reference method.
Note 2 to entry: Apart from the analyser, an AMS includes facilities for taking samples (e.g. probe, sample gas lines,
flow meters, regulators, delivery pumps) and for sample conditioning (e.g. dust filter, moisture removal devices,
converters, diluters). This definition also includes testing and adjusting devices that are required for regular functional
checks.
[SOURCE: FprEN 14181:2014]
3.4
calibration of an AMS
establishment of the statistical relationship between values of the measurand indicated by the automated
measuring system (AMS) and the corresponding values given by the standard reference method (SRM) used
during the same period of time and giving a representative measurement on the same measurement plane
Note 1 to entry: The result of calibration permits to establish the relationship between the values of the SRM and the
AMS (calibration function).
Note 2 to entry: Calibration should not be confused with adjustment of a measuring system.
3.5
calibration of the SRM
set of operations that establish, under specified conditions, the relationship between values of quantities
indicated by a measuring instrument or measuring system, and the corresponding values realized by standard
reference method implemented in the state of the art in order to provide representative results.
3.6
chemical blank value
sulphate ion content of an unexposed sample of the absorption solution, plus reagents that are added to the
solution before analysis if necessary
3.7
emission limit value
ELV
emission limit value according to EU Directives on the basis of 30 min, 1 h or 1 day
3.8
field blank
value determined by a specific procedure used to ensure that no significant contamination has occurred
during all steps of the measurement and to check that the operator can achieve a quantification level adapted
to the task
[SOURCE: CEN/TS 15675]
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3.9
influence quantity
quantity that is not the measurand but that affects the result of the measurement
Note 1 to entry: Influence quantities are e.g. ambient temperature, atmospheric pressure, presence of interfering gases
in the flue gas matrix or pressure of the gas sample.
3.10
measurand
quantity intended to be measured
[SOURCE: JCGM 200:2012]
3.11
measurement series
several successive measurements carried out on the same measurement plane and at the same process
operating conditions
3.12
measurement plane
plane normal to the centreline of the duct at the sampling position
Note 1 to entry: Measurement plane is also known as sampling plane.
[SOURCE: EN 15259:2007]
3.13
measurement point
position in the measurement plane at which the sample stream is extracted or the measurement data are
obtained directly
Note 1 to entry: Measurement point is also known as sampling point.
[SOURCE: EN 15259:2007]
3.14
measurement site
place on the waste gas duct in the area of the measurement plane(s) consisting of structures and technical
equipment, for example working platforms, measurement ports, energy supply
Note 1 to entry: Measurement site is also known as sampling site.
[SOURCE: EN 15259:2007]
3.15
measuring system
complete set of measuring instruments and other equipment assembled to carry out specified measurements
[VIM 3.2]
3.16
performance characteristic
one of the quantities (described by values, tolerances, range, …) assigned to equipment in order to define its
performance
6

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3.17
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]
3.18
standard reference method
SRM
reference method prescribed by European or national legislation
[SOURCE: EN 15259:2007]
3.19
repeatability in the laboratory
closeness of the agreement between the results of successive measurements of the same measurand carried
out under the same conditions of measurement
Note 1 to entry: These conditions include:
 same measurement procedure;
 same laboratory;
 same sampling equipment, used under the same conditions;
 same location;
 repetition over a short period of time.
Note 2 to entry: Repeatability may be expressed quantitatively in terms of the dispersion characteristics of the results.
Note 3 to entry: In this European Standard the repeatability is expressed as a value with a level of confidence of 95 %.
3.20
repeatability in the field
closeness of the agreement between the results of simultaneous measurements of the same measurand
carried out with two equipments under the same conditions of measurement
Note 1 to entry: These conditions include:
 same measurement procedure;
 two equipments, the performances of which are fulfilling the requirements of the reference method, used under the
same conditions;
 same location;
 implemented by the same laboratory;
 typically calculated on short periods of time in order to avoid the effect of changes of influence parameters (e.g.
30 min).
7

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Note 2 to entry: Repeatability may be expressed quantitatively in terms of the dispersion characteristics of the results.
Note 3 to entry: In this European Standard the repeatability under field conditions is expressed as a value with a level
of confidence of 95 %.
3.21
reproducibility in the field
closeness of the agreement between the results of simultaneous measurements of the same measurand
carried out with several sets of equipment under the same conditions of measurement
Note 1 to entry: These conditions are called field reproducibility conditions and include:
 same measurement procedure;
 several sets of equipment, the performance of which fulfils the requirements of the reference method, used under the
same conditions;
 same location;
 implemented by several laboratories.
Note 2 to entry: Reproducibility may be expressed quantitatively in terms of the dispersion characteristics of the
results.
Note 3 to entry: In this European Standard the reproducibility under field conditions is expressed as a value with a level
of confidence of 95 %.
3.22
uncertainty
parameter associated with the result of a measurement, that characterises the dispersion of the values that
could reasonably be attributed to the measurand
3.23
standard uncertainty
u
uncertainty of the result of a measurement expressed as a standard deviation
3.24
combined uncertainty
u
c
standard uncertainty attached to the measurement result calculated by combination of several standard
uncertainties according to the principles laid down in ISO/IEC Guide 98-3 (GUM)
3.25
expanded uncertainty
U
quantity defining a level of confidence about the result of a measurement that may be expected to encompass
a specific fraction of the distribution of values that could reasonably be attributed to a measurand
U = k × u

Note 1 to entry: In this European Standard, the expanded uncertainty is calculated with a coverage factor of k = 2, and
with a level of confidence of 95 %.
Note 2 to entry: The expression overall uncertainty is sometimes used to express the expanded uncertainty.
3.26
uncertainty budget
calculation table combining all the sources of uncertainty according to EN ISO 14956 or ISO/IEC Guide 98-3
in order to calculate the combined uncertainty of the method at a specified value
8

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4 Symbols and abbreviated terms
4.1 Symbols
For the purposes of this document, the following symbols apply.
C mass concentration of sulphur dioxide in the sample gas, in milligrams per cubic metre (of gas)
m
equivalent mass of sulphur dioxide of 1 mm of titration solution (barium perchlorate standard
f
a
volumetric solution) used for titration in Thorin method, in milligrams per millilitre
f ratio of the volume of the pre-treated sample solution (sample absorption solution pre-treated
v
before analyse) to the volume of the aliquot taken for the titration in Thorin method
2
L limit of quantification, in milligrams per litre of SO
4
Q
m weight of the sample solution (absorption solution used for sampling + rinsing solution), in grams
s
P absolute pressure at the gas volume meter, in kilopascals
m
P standard pressure: 101,3 kPa
std
P saturation vapour pressure of water at volume gas meter temperature, in kilopascals
sat (Tm)
q mass concentration of sulphate in sample absorption solution, in milligrams per litre (of solution)
s
q mass concentration of sulphate in chemical blank solution, in milligrams per litre (of solution)
cb
r repeatability, in milligrams per cubic metre or percentage
R reproducibility, in milligrams per cubic metre or percentage
R peak resolution S : volume of titration solution used for titration of sample absorption solution, in
s s
millilitre
S volume of titration solution used for titration of chemical blank solution, in millilitre
cb
S repeatability standard deviation, in milligrams per cubic metre or percentage
r
S reproducibility standard deviation, in milligrams per cubic metre or percentage
R
S maximum allowable repeatability standard deviation, in milligrams per cubic metre
r, limit
S volume of titration solution used for the titration of the aliquot of the pre-treated sample solution,
s
in millilitres
t retention time of the first peak, in seconds
1
t retention time of the second peak, in seconds
2
T temperature at the gas meter, in Kelvin
j
T mean temperature at the gas volume meter, in Kelvin
m
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T standard temperature, 273 K
std
V reading at the gas volume meter at the beginning of the sampling period, in cubic metres
1
V reading at the gas volume meter at the end of the sampling period, in cubic metres
2
V dry gas volume measured, corrected to standard conditions, in cubic metres
m (std)
V volume of the sample solution (absorption solution used for sampling + rinsing solution), in litres
s
w peak width, on the time axis, of the first peak, in seconds
1
peak width on the time axis, of the second peak, in seconds
w
2
ε absorption efficiency, in percentage
σ conductivity, in micro-siemens per metre
4
density of a liquid at 20 °C compared to water's at 4 °C, in kilograms per litre
ρ
20
χ volume content, in percentage
4.2 Abbreviated terms
For the purposes of this document, the following abbreviated terms apply.
PE Polyethene
PTFE Polytetrafluoroethene
5 Measuring principle
5.1 General
This European Standard describes the standard reference method (SRM) based on two alternative analytical
techniques for determining sulphur dioxide (SO ) content emitted to atmosphere from ducts and stacks. The
2
specific components and the requirements for the measuring system are described in Clauses 6 to Clause 8.
A number of performance characteristics with associated performance criteria are specified for the measuring
system (see Tables 1 and 2). The expanded uncertainty of the method shall meet the specifications given in
this European Standard. Requirements and recommendations for quality assurance and quality control are
given for measurements in the field (see Clause 6 and Clause 8).
5.2 Measuring principle
A sample of gas is extracted via a heated temperature-controlled probe. The sample is filtered and drawn
through hydrogen peroxide absorber solutions for a specified time and at a controlled flow rate. The sulphur
dioxide in the sampled gas is absorbed and oxidised to sulphate ion. The mass concentration of sulphate in
the absorption solutions is subsequently determined using ion chromatography or by titration with a barium
perchlorate solution using Thorin as indicator. SO is also absorbed and transformed in sulphate ion and is
3
therefore an interferent.
10

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oSIST prEN 14791:2015
prEN 14791:2014 (E)
This European Standard has been validated with a 0,3 % H O absorption solution for concentrations lower
2 2
3
than 1 000 mg/m and with a 3,0 % H O absorption solution for higher concentrations but lower than
2 2
3
2 000 mg/m . Typical concentration of the absorption solution is 0,3 % H O . However, for concentrations
2 2
3
higher than 1 000 mg/m it is recommended, in case of a bad efficiency either to decrease the flow or to
increase the H O concentration.
2 2
6 Description of measuring equipment
6.1 Reagents
6.1.1 General
During the analysis, use only reagents of recognised analytical grade.
Normal, accepted laboratory safety practices and cleaning procedures for glassware should be followed
during reagent preparation.
WARNING — Use the reagents in accordance with the appropriate health and safety regulations.
6.1.2 Hydrogen peroxide
4
Commercially available solution of H O mass content 30 %, ρ = 1,11 kg/l.
;
2 2
20
6.1.3 Water
–1
H O; ultra pure water with conductivity σ < 10 µS m .
2
6.1.4 Absorption solution, H O
2 2
The absorption solution is a hydrogen peroxide solution (6.1.2) diluted to a mass concentration of 0,3 % H O
2 2
3
in water (6.1.3). For flue-gas concentrations higher than 1 000 mg/m , it is suggested, in case of a bad
efficiency, either to decrease the flow, or to increase the concentration of the absorption solution.
For the preparation of the mass concentration of 0,3 % H O in water, thoroughly mix about 10 ml of 30 % of
2 2
H O (6.1.2) with 500 ml of water (5.1.3) and make up to 1 000 ml with water (6.1.3). Store the solution in a
2 2
glass or PE bottle in a dark place and for no longer than one week.
WARNING — Decomposition of the solution may occur and may lead to the explosion of the storage
bottle. It is recommended that the lid of this bottle is not closed too tightly or to use a security cap.
NOTE Cleanliness of the glassware is important to avoid a possible decomposition of hydrogen peroxide.
6.1.5 Reagents for chromatographic analysis
6.1.5.1 Eluent solution
The choice of eluent depends on the manufacturer's separator column and detector. For the exact
composition of the eluent, use a validated solvent for the method and/or refer to the instructions given by the
manufacturer.
-3
NOTE For an ion chromatograph using the suppressor technique, a typical eluent is a solution of 1,7×10 mol/l of
-3
NaHCO and 1,8×10 mol/l of Na CO .
3 2 3
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oSIST prEN 14791:2015
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2−
-3
6.1.5.2 Standard sulphate stock solution, 10,4×10 mol/l of SO
4
–3
Use a commercially available sulphate stock solution of 1 000 mg/l sulphate (10,4×10 mol/l) with a minimum
content of 99,0 %. As an alternative prepare the standard solution as follows:
Dissolve 1,814 g of analytical grade potassium sulphate (K SO ) in water (6.1.3) and dilute to a 1 000 ml
2 4
2-
volumetric flask. 1 ml of stock solution corresponds to 1 mg of SO .
4
NOTE Calibration standards are prepared by diluting the standard stock solution with the absorption solution as
specified in 9.2.3.2.
6.1.5.3 Regeneration solution for suppressor
For the exact composition of the suppressor regeneration solution, refer to the instructions given by the
manufacturer of the suppressor.
-3
NOTE An example is a solution of 12,5×10 mol/l of H SO .
2 4
6.1.6 Reagent for Thorin analysis
6.1.6.1 2-propanol [CH CH(OH)CH ]
3 3
Use commercially available 2-propanol [CH CH(OH)CH ] in analytical grade (minimum content 99,8 %).
3 3
6.1.6.2 Barium perchlorate, standard volumetric solution, [Ba(CIO ) ] = 0,005 mol/l
4 2
Use a commercially available barium perchlorate solution (80 % 2-propanol/20 % water) with concentration of
0,005 mol/l Ba(CIO ) , or prepare the standard solution as follows:
4 2
Dissolve 1,7 g of anhydrous barium perchlorate [Ba(CIO ) ] in about 200 ml of water in a 1 000 ml one-mark
4 2
volumetric flask. Make up to the mark with 2-propanol (5.1.6.1) and mix well.
Titrate the solution accurately against a 0,005 mol/l standard volumetric sulphuric acid solution.
1 ml of exactly 0,005 mol/l barium perchlorate solution is equivalent to a mass of sulphur dioxide of 0,320 mg;
(f = 0,320 mg/ml).
a
6.1.6.3 Potassium hydroxide, standard volumetric solution, [KOH] = 0,1 mol/l
Use a commercially available solution of 0,1 mol/l KOH in water.
NOTE This reagent is only necessary if the sampling gas contains high concentration of acid components (e.g. SO >
2
3 3 3
100 mg/m or HCl > 200 mg/m or NO > 400 mg/m ).

2
6.1.6.4 Perchloric acid, standard volumetric solution, [HClO ] = 0,1 mol/l
4
Prepare an approximate 1 % solution of perchloric acid by mixing 16 ml of a commercially available solution of
60 % perchloric acid in water (6.1.3) and make up to 1 000 ml with water. Store this solution in a glass or PE
bottle.
NOTE This reagent is only necessary if the sampling gas contents high concentrations of alkali components (e.g.
3
NH > 50 mg/m ).
3
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oSIST prEN 14791:2015
prEN 14791:2014 (E)
6.1.6.5 Thorin, {4-[2-arsonophenyl)-azo]-3-hydroxy-2,7 naphthalene-disulfonic acid disodium salt}
2 g/l solution
Thorin is also known as Thoron or Thoronol, the sodium salt of
-1(2-arsonophenyl)-azol-3 -hydroxy-2,7-naphthalene-disulfonic acid.
Dissolve 0,2 g of Thorin in water (6.1.3) in a 100 ml one-mark volumetric flask. Make up to the mark with water
and mix well.
Store this solution in a bottle made of glass or polyethylene.
6.2 Sampling equipment
6.2.1 General
A known volume of flue gas is extracted representatively from a duct or a chimney during a certain period of
time at a controlled flow rate. A filter removes the dust in the sampled volume, thereafter the gas stream is
passed through a series of absorbers containing an absorption solution.
All parts of the sampling equipment upstream of the first absorber shall not react with or adsorb SO (i.e.

2
borosilicate glass, quartz glass, PTFE or titanium are suitable materials).
If an unheated gas connector line is used between the heated filter and the first absorber, it shall be
thoroughly rinsed with fresh absorption solution after sampling and the rinsing solutions shall be combined
with the sample.
An example of a suitable sampling train is shown in Figure A.1.
6.2.2 Sampling probe
In order to reach the measurement point(s) of the measurement plane, probes of different lengths and inner
diameters may be used. The design and configuration of the probe used shall ensure the residence time of
the sample gas within the probe is minimised in order to reduce the response time of the measuring system.
NOTE 1 The probe may be marked before sampling in order to demonstrate that the measurement point(s) in the
measurement plane has (have) been reached.
When droplets are present in the flue gases, they may contain SO dissolved in it. In that case, the probe is
2
equipped with a nozzle a
...

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